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2004 Part 3     Front Cover (2004 - Part 3)    No author information available Summary:         Table of Contents (2004 - Part 3)    No author information available Summary: Not available         Accelerating applications of RF superconductivity-success stories    H. Padamsee Summary: RF superconductivity has become an important technology for accelerators at the energy and luminosity frontiers as well as at the cutting edge of nuclear physics and basic materials science. Nearly one kilometer of superconducting cavities have been installed in accelerators to provide more than 5 gigavolts of acceleration. Superconducting cavities support beam currents above one ampere, and deliver up to 380 kW of beam power. Steady advances in science and technology are responsible for spectacular increases in performance since the large installations of CEBAF (Jefferson Lab) and LEP-II (CERN) during the 1990's. The gradient of niobium cavities has more than tripled over the last decade, spurring new accelerators. The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory switched to superconducting technology in 2000. The X-ray Free Electron Laser at DESY will provide angstrom-wavelength beams of unprecedented brilliance. Recently an International Technology Recommendation Panel selected the superconducting option for the International Linear Collider. The 500 GeV collider will require 20,000 superconducting cavities, each about one meter long, operating at 2 K. Energy Recovery Linac (ERL) studies are flowering for a variety of applications: ultra-fast, high brilliance light sources as well as electron beams for cooling or colliding with ions in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab. Designs for the nuclear Rare Isotope Accelerator (RIA) demand high performance cavities. With many years of operating experience at major accelerators demonstrating a robust technology, SRF is ready to launch major initiatives.         John Hulm-scientist and friend-a remembrance    T.H. Geballe Summary: One of John's important contributions was the discovery in 1952 of superconductivity in the compound of vanadium and silicon (V3Si) made with his student Hardy at the University of Chicago, where he was an assistant professor. This opened a rich new field of superconductivity.John lives on as an unforgettable human being in my mind and I would guess in the minds of many. He was highly respected for his scientific wisdom and his administrative fairness and honesty. Alas, those glory days of research at Westinghouse with outstanding scientists gathered by Zener and Condon, and continued under John's leadership as the Chief Scientist, live on only in memory. I could say the equivalent about Bell Labs as well. I am grateful that he, and I (and many others too) were there during those golden days.         Fifty years of superconductivity-and the next fifty too    D.C. Larbalestier Summary: John Hulm made major contributions to the field of superconductivity as an academic scientist, applied scientist, later as manager at Westinghouse Central Research Laboratory of one of the largest industrial research programs in the field, and finally as a senior statesman of superconductivity. A brief memoir of my interactions as a younger generation scientist is presented. I was particularly impressed by his belief that development of new and better superconductors in practical forms underpins the development of superconducting technology.         The history and future of A15s in Japan    K. Tachikawa and T. Takeuchi Summary: Tapes and wires of V/sub 3/Ga were first made in Japan based on the discovery of the effect of Cu additive for the promotion of V/sub 3/Ga synthesis. The bronze process applied to V/sub 3/Ga was extended to the fabrication of Nb/sub 3/Sn. The Ti addition to the bronze matrix was also initiated in Japan so as to improve significantly high-field performance. The so-called internal tin and Nb tube processes were also initiated in Japan. These achievements on V/sub 3/Ga and Nb/sub 3/Sn lead into the recent active development of high-field, large-scale, and refrigerator-cooled superconducting magnet applications. As for Nb/sub 3/Al, which shows excellent strain tolerance, various approaches were made in Japan to achieve stoichiometry and fine grain structures. Among them the Jelly-Roll process is the most reliable method to produce long-lengths of Nb/sub 3/Al wire for fusion uses. High performance Nb/sub 3/Al conductors for high-field use are being produced by the rapidly heating, quenching and transformation annealing (RHQT) process. Future progress in the A15 conductor development in Japan may be expected through improved processes.         Phase formation from liquid phase under various post-annealing conditions    F. Nakao and K. Osamura Summary: The process of phase formation from the liquid phase during post-annealing process has been studied precisely using the powder XRD Rietveld analysis. Mass fraction of the liquid phase was estimated to be 9.3% from the sum of phases that formed during post-annealing. Phase conversion from the liquid phase depended strongly on post-annealing temperature and its regime is mainly divided into two patterns. The first is the conversion into (Bi,Pb)2212 and CaPbO/sub 4/ and the second is into (Pb,Bi)3221 and AEC. The former regime was observed during post-annealing at around 1073 K, whereas the latter occurred at around 1053 K. The liquid phase existed at (Bi,Pb)2223 grain boundaries is suggested to limit superconducting current path. The increase of critical current by 1.4 times after post-annealing is closely related with the crystallization of grain boundary liquid.         Calculated I-V characteristics and their critical scaling of Ag/Bi2223 tapes based on weak link path model    K. Ogawa and K. Osamura Summary: A numerical analysis of current-voltage (I-V) characteristics of silver sheathed (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10+/spl delta// tapes is carried out to investigate their correlation with microscopic inhomogeneities based on Weak Link Path Model. The dependence of I-V curves is calculated on the various local distributions of critical currents. Furthermore, by assuming a relationship between local distribution and temperature T, T dependence of I-V curves is examined. As a result, n value and critical current dependence on the shape of local distribution is obtained. Moreover, it is revealed that T dependent I-V characteristics show critical scaling behavior like glass-liquid transition of vortex phase as a percolation transition of non-SC links.         Effect of pre-annealing temperature and atmosphere on the microstructure and transport property of Bi-2223/Ag tapes    C.H. Jiang, H. Kumakura and T. Koizumi Summary: The phase assemblage and Bi-2212 texture in Bi-2223/Ag tapes before the heat treatment were varied by pre-annealing the tapes at different temperatures and in pure Ar or air for 10 h. Then all the tapes were isothermally heat treated at 840/spl deg/C in air for 4 cycles with intermediate pressings. The J/sub c/ of the samples pre-annealed in pure Ar were lowered no matter which annealing temperature was used. The best J/sub c/ was obtained in the samples pre-annealed at 800/spl deg/C in air, which was in an average value of 21.7 kA cm/sup -2/, being increased by 25% compared with that of the unannealed tapes (17.3 kA cm/sup -2/). The transport properties of various pre-annealed samples were correlated to the phase evolutions, growth and pre-alignment of Bi-2212 grains during pre-annealing.         SEM observation on the nucleation and grain growth of Bi-2223 phase in Ag-sheathed BSCCO tapes    C.H. Jiang, J.M. Yoo, G.W. Qiao and H. Kumakura Summary: The SEM observation on the surface morphologies of quenched Bi-2223/Ag tapes after various sintering time indicates that Bi-2223 grains nucleated on the partially melted Bi-2212 grains at the initial stage of reaction and some of them were in the form of twin grains. Then they grew into plate-like grains with the growth of the twin grains and the consumption of the mother Bi-2212 grains. Remarkably, at the growth fronts of Bi-2223 grains the growth steps show the existence of preferential growing sites, which played an important role during the whole growing process of Bi-2223 grains. The appearance of preferential growing sites is thought to be related to the inhomogeneously distributed chemical composition and liquid phase in the reaction system. Based on the microstructure observation and kinetic analysis, it is suggested that both the intercalation process and the two dimensional diffusion controlled nucleation and growth process might be responsible for the nucleation of Bi-2223 phase, but with only the later accounting for the 2223 grain growth.         The influence of processing conditions on the structure and critical properties of Bi-2223 composite tapes    A.K. Shikov, D.B. Gusakov, D.N. Rakov, V.A. Vargin, I.I. Akimov, E.V. Kotova, M.I. Medvedev and V.S. Kruglov Summary: SEM, XRD-data, and critical properties are presented which concern to Bi-2223 composite tapes processed under various conditions. The multifilamentary tapes were made by the PIT procedure with using of extrusion and/or drawing and tape rolling. Initial properties of powder precursors, filling factor, tape rolling, and heat treatment conditions as well as O/sub 2/-content in working atmosphere were varied. The achieved critical properties are described and analyzed. In particular, on basis of XRD-data significant differences in Bi-2223 grains substructure for tapes having different levels of critical current have been revealed.         Characteristics of critical current and index n of Bi-2223/Ag tape up to 30 T at 4.2 K    Jung Ho Kim, Jinho Joo, Seyong Choi, W. Nah, Dong-Woo Ha, Hong-Soo Ha, A. Matsumoto, H. Kumakura, T. Koizumi, M. Sugano and T. Kiyoshi Summary: We fabricated 55-filament Bi-2223/Ag tape and evaluated the dependence of critical current (I/sub c/) and index n in an external magnetic field up to 30 T at 4.2 K, in order to explore the possible application for a magnet in persistent current mode. I/sub c/ and index n were characterized as a function of temperature and the magnitude and orientation of the magnetic field by increasing and decreasing field. It was observed that I/sub c/ was dependent on the magnitude and orientation of the magnetic field. The I/sub c/ decreased exponentially as the field increased; in a parallel and increasing field, I/sub c/ was 128 A at 30 T, which is approximately 40% of the I/sub c/ in self-field. On the other hand, index n was not significantly dependent on the field up to 30 T, nor did it vary significantly on increasing or decreasing field; the n value in the range of 0.1/spl sim/1 /spl mu/V/cm was 23.0/spl plusmn/5.2 and 27.8/spl plusmn/8.0 on increasing and decreasing field, respectively, in the range of 0/spl sim/30 T. In addition, we observed that local I/sub c/ and index n of a long length of tape (4.2 m) were dispersed over a wide range and that the variation of each of these two values with the position of the tape was similar, suggesting that these properties depend on the microstructural uniformity.         Synthesis and characterization of fine and homogeneous BSCCO-2223 precursor powder by spray pyrolysis process for PIT process    Jaimoo Yoo, Jae-Woong Ko, Young-Kuk Kim and Kook-Chae Chung Summary: Homogeneous and fine BSCCO precursor powders were prepared by spray pyrolysis (SP) method starting from an aqueous solution of metal nitrates. The influence of solution concentration, furnace reaction temperature and types of spray on microstructure and average particle size were investigated. The synthesized precursor powders had a narrow particle size distribution and low carbon content. The reactivity of precursor powder by SP method is very high, attributed to the fine and narrow particle size distribution of precursor powders. The precursor powder by SP method promoted a very quick formation of the 2223 phase for short sintering time. The XRD result shows high possibility of reducing secondary phases such as large AEC and almost phase pure microstructure through more homogeneous reaction.         Influence of modification of annealing and sheath materials on critical current density of Bi-2223/Ag tapes    Dong-Woo Ha, Sang-Chul Kim, Joo-Saeng Yang, Sang-Soo Oh and Hong-Soo Ha Summary: It is important to improve critical current density of silver-sheathed Bi-2223 tapes for practical applications of material. Bi-2223/Ag superconducting wires with various sheath materials were fabricated by stacking, drawing process with different pre-annealing schedules. Two kinds of powders were prepared. One was pre-annealed at 760/spl deg/C and low oxygen partial pressure, and the other was only calcined state. Before rolling process, round wires were pre-annealed at 760/spl deg/C and in a low oxygen partial pressure. Bi-2223/Ag conductor was needed softening annealing at low temperature during drawing process because pre-annealed precursor powder brought about decrease in workability. Pre-annealing let tetragonal structure of Bi-2212 phase of precursor transform to orthorhombic structure and reduce the fraction of second phases at superconducting wire, which could increase critical current density. However the breakages occurred at Ag-alloy sheathed long Bi-2223/Ag tapes during rolling after pre-annealing. Several pre-annealing scenarios were introduced to reduce the breakages during rolling process. We could achieve proper pre-annealing conditions for Ag-alloy clad Bi-2223 tapes by the analysis of mechanical properties. We could achieve highest Je of 8800 A/cm/sup 2/ at Bi-2223 tape by two-step pre-annealing.         Electrical behavior of Bi-2223/Ag tapes under applied alternating over-currents    Seong-Woo Yim, Sung-Hun Lim, Hye-Rim Kim, Si-Dole Hwang and K. Kishio Summary: As a study for the protection of HTS power machines operated under AC conditions, the electrical behavior of Bi-2223/Ag tapes with applied alternating over-currents was investigated. Using the HTS tape of 57 A I/sub c/ and 106 K T/sub c/, we measured the V-I curves for the over-critical current region from 150 A/sub p/ to 507 A/sub p/. From the experimental results, 3 matters were investigated. Firstly, using the resistance increase data obtained from the curves, quench development was analyzed as a function of the amplitude and duration of the applied currents. Secondly, to understand these phenomena in detail, we investigated the current distribution between the superconductor and the metal sheath in Bi-2223/Ag tape, applying the equivalent equations and data of V-I curves. Finally, we confirmed the relationship between the resistance and temperature generated by the over-critical current experimentally. As a result, we could find the optimal operating condition considering the protection of the HTS tape against the alternating over-current.         Influence of compressive length of normal stress on degradation in Bi-2223 tapes    T. Takao, T. Ito, K. Umekawa, Y. Fukasawa, H. Tanaka and M. Umeda Summary: We have applied transversal-compressive force to typical Bi-2223 tapes with multi-filaments and a Ag-alloy matrix. The degradation of superconducting performance of the tapes against the compressive force was measured. In the experiment, damaged lengths along the tape were changed, and hence, the dependence of the damaged lengths on the I/sub c/ degradation were also evaluated. According to the experimental results, in spite of the same stress to the tapes, the I/sub c/ degradation clearly depended on the loaded length along the tape. Therefore, the superconducting property degraded with increasing of the damaged length. When the transversal-compressive force is applied to the tape surfaces, it should be carefully noted that the degradation depends on the damaged length along the tape.         Effect of combined bending strain and thermal cycling on the voltage-current characteristic curves of Bi-2223 tapes    C.Y. Shigue, C.A. Baldan, U.R. Oliveira, F.J.H. Carvalho Jr. and E.R. Filho Summary: High critical temperature superconductors are evolving from a scientific research subject into large-scale application devices. In order to meet this development demand they must withstand high current capacity under mechanical loads arising from thermal contraction during cooling from room temperature down to operating temperature (usually 77 K) and due to the electromagnetic forces generated by the current and the induced magnetic field. Among the HTS materials, the Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ compound imbedded in an Ag/AgMg sheath has shown the best results in terms of critical current at 77 K and tolerance against mechanical strain. Aiming to evaluate the influence of thermal stress induced by a number of thermal shock cycles we have evaluated the V-I characteristic curves of samples mounted onto semicircular holders with different curvature radius (9.75 to 44.5 mm). The most deformed sample (/spl epsiv/=1.08%) showed the largest reduction of critical current (40%) compared to the undeformed sample and the highest sensitivity to thermal stress (I/sub c//I/sub c0/=0.5). The V-I characteristic curves were also fitted by a potential curve displaying n-exponents varying from 20 down to 10 between the initial and last thermal shock cycle.         Optimization of CIP process on superconducting property of Bi-2223/Ag wires composite bulk    S. Yoshizawa, S. Hirano, Y. Hishinuma and A. Nishimura Summary: In order to improve superconducting property of Bi-2223 superconductor bulk, 5 mm in width, 22 mm in length and ca. 2 mm in thickness, silver (Ag) wires of 0.4 mm in diameter were composed in the bulk. The composite was made by stacking alternately Ag wires and the calcined powder. The pressed sample was sintered at 840/spl deg/C for 50 hours in air. After treatment with a cold isostatic press (CIP) as an intermediate pressing, the sample was sintered again. With 6 times of CIP processing, the maximum critical current density (J/sub c/) at 77.3 K of the sample composed with twenty-four Ag wires was obtained to be 950 A/cm/sup 2/. SEM and EPMA observation results showed that highly c-axis oriented and densely structured Bi-2223 plate-like grains could be formed around the interfacial region between the superconducting oxide and the metal Ag.         Effect of precursor phase composition on 2223 phase formation in Ag-sheathed tapes    M.O. Rikel, A. Wolf, S. Arsac, M. Zimmer and J. Bock Summary: Metastable phase states of BPSCCO 2223 precursor were studied as a function of annealing temperature, time, and oxygen partial pressure. Reproducible, but path-dependent changes in precursor phase composition during annealing are mostly governed by changes in Pb solubility in the (Bi,Pb)2212 phase. Studying phase formation upon heat treatment of tapes made by Nexans customers, we found that BPSCCO phase composition affects melting behavior of (Bi,Pb)2223/Ag tapes, phase recrystallization upon heating, and early stages of Bi2223 phase formation.         Progress in the preparation of technical HTS-tapes of type Bi-2223/Ag-alloy of industrial lengths    T.J. Arndt, A. Aubele, H. Krauth, M. Munz and B. Sailer Summary: We report about the improvements on overall critical current density j/sub e/, long-length processing, mechanical properties, and insulation. These topics are discussed for Bi-2223/Ag-alloy tapes for typical DC-applications, for AC-applications which require twisted filaments to achieve low-loss properties and for current-lead-applications (EAS is producing Bi-2223/AgMgAu-HTS-tapes for the CERN-LHC-Project). The state-of-the art production of Bi-2223/Ag-alloy tapes at EAS allows for overall current densities of >100 A/mm/sup 2/. There is progress out of the development line to a value of more than 120 A/mm/sup 2/, which will be transferred to the production line in the near future. Regarding AC-tapes with twisted filaments, it is possible to prepare tapes without a reduction in overall current density if the preparation parameters are kept within a well defined window. Both types of tapes are available in piece-lengths of up to 1500 m. The requirements on the piece-lengths of Bi-2223/AgMgAu-HTS-tapes for current leads are less stringent. This type of tape is available in piece-lengths up to 300 m with overall current densities up to 90 A/mm/sup 2/.         Development of HTS BSCCO wire for power applications    H.P. Yi, X.H. Song, L. Liu, R. Liu, J. Zong, J.S. Zhang, A.K.M. Alamgir, Q. Liu, Z. Han and Y.K. Zheng Summary: As the first company engaged in commercial manufacture of HTS BSCCO wires in China, Innost has devoted great efforts to improve the electrical performances and practical properties of its HTS wire products. Based on huge amount of fundamental research work, the short sample can achieve 120 A of I/sub c/ and 12 kA/cm/sup 2/ of J/sub e/. Under strict quality control, Innost's HTS wire can be manufactured reproducibly with length up to 1 km, I/sub c/ over 90 A and J/sub e/ over 9 kA/cm/sup 2/. Meanwhile, to demonstrate technical feasibility and reliability of HTS power apparatus, diversified wire-design has been carried out, including reducing AC losses and thermal conductivity, increasing insulating properties and mechanical strength, and so on. Up to now, Innost's diversified wire products have been widely used in domestic and international R&D projects of HTS application.         Development of Bi-2223 superconducting wires for AC applications    N. Ayai, K. Hayashi and K. Yasuda Summary: Advanced silver sheathed Bi-2223 superconducting tapes have been developed for AC-applications such as electric power cables and transformers, which require reduced AC-losses. Twisted multi-filament and inter-filament resistive barriers were applied to eliminate the electromagnetic inter-filament coupling, which is the primary mechanism in enhancing AC-losses. A multi-filamentary wire with a honeycomb type thin ceramic barrier was designed and manufactured in an attempt to realize low AC-losses without degrading the transport properties of the conductor. AC-losses of the manufactured wire were reduced drastically when compared to those of conventional wires without barriers. Using the measured properties of the manufactured wire as a basis, a design study along with projected AC-losses for a superconducting power cable is presented.         A shell model for the filament structure of Bi-2223 conductors    T.G. Holesinger, J.A. Kennison, S. Liao, Y. Yuan, J. Jiang, X.Y. Cai, E.E. Hellstrom, D.C. Larbalestier, R.M. Baurceanu, V.A. Maroni and Y. Huang Summary: Phase development during the first few minutes of heat treatment of first generation (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub y/ (Bi-2223) multifilamentary wires determines to a large extent the overall microstructure, the efficiency of primary phase development, competing secondary phase development, texture evolution, and grain-to-grain connectivity. It is shown that the filament structure of these wires can be described in terms of a shell model. The shell next to the silver sheath is comprised of well-formed Bi-2223 colonies grapho-epitaxially aligned to the silver sheath and only a few grains (average one colony) thick. Inside this shell is a less well-aligned, less phase pure, more porous Bi-2223 structure through which current is carried in a nonuniform manner as shown by MOI.         Characterization of critical current density in silver-sheathed Bi-2223 tape    T. Matsushita, Y. Himeda, M. Kiuchi, J. Fujikami and K. Hayashi Summary: The critical current property of a superconducting Bi-2223 tape produced by the over pressure processing at the final heat treatment was investigated. The critical current density increased by a factor of 1.6-1.8 at 77.3 K in comparison with the tape produced by the usual process. Thus, the critical current increased in spite of a reduction in the filament thickness. It was also found that the irreversibility field increased by a factor of 1.34 at 77.3 K by the new process. As a result, the enhancement of the critical current density at higher fields is remarkable. These results suggest that the over pressure process not only enriches the mass concentration of the superconducting phase but also contributes to the c-axis alignment. This is supported directly by the reduction of FWHM of rocking curve and indirectly by an enhancement the n value. The critical current property at lower temperatures is also investigated and the possibility of the further improvement of the property is discussed.         Flexible HTS wires: from start-up of a full-sized plant to industrial applications    J. Kellers, M. Backer, C. Buhrer, J. Muller, A. Rath, S. Remke and J. Wiezoreck Summary: For over a decade high temperature superconducting (HTS) wires have seen a continuous performance increase and have arrived at the level of technical maturity. Among the manufacturers of such wires, Trithor is the only European company that specializes exclusively in HTS wires. To meet the increasing demand for HTS wires, Trithor completed a full-sized manufacturing plant with a design capacity of 2,500 km per year. This paper reports on the plant design. Performance, reliability, quality and cost are of equal importance to the wire user. This paper addresses these areas and presents wire data. Added value in form of high performance insulation, efficient current leads, and coil winding has become available. Performance attributes will be reported in this paper. HTS wire has industrial application throughout the power infrastructure. This paper also provides information on the various prototype applications of Trithor wire. Whereas BSCCO-2223 class multifilamentary composite wire is commercially available now, the YBCO coated conductor wire to be developed by a consortium led by Trithor enables similar or improved performance at further reduced cost. 2G wire will contribute to a widespread use of HTS from 2010 onwards.         Long term anneal study and composition variation for reducing residual Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ (2212) in (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ (2223) wires    J. Jiang, X.Y. Cai, Y. Yuan, A.A. Polyanskii, E.E. Hellstrom, D.C. Larbalestier, V.A. Maroni, T.G. Holesinger and Y. Huang Summary: Recent experiments showed that Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ (2212) intergrowths are a major current limiting mechanism in (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ (2223) wires and that reduced Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ (2212) correlates to enhanced critical current density J/sub c/. We performed a final 500 h post heat treatment on commercial 2223 wire to study whether an extended heat treatment would reduce the 2212 phase content. This heat treatment did not change the 2212 content or J/sub c/, indicating the fully processed 2223 wires were already very close to their terminal phase state. In an attempt to reduce the 2212 content, we slightly modified the standard composition in the Ca and Cu rich directions, investigating: Ca-rich; Cu-rich; Ca plus Cu-rich; Sr-poor; and Ca substitution for Sr. Although the 2212 content was not reduced by modifying the composition, the result further confirmed the correlation between J/sub c/ and residual 2212 in 2223 wires.         The origin of the Pb-rich Bi/sub 3/Sr/sub 2/Ca/sub 2/Cu/sub 1/O/sub x/ (3221) phase during post annealing of (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x//Ag composite conductors    Y. Yuan, X.Y. Cai, J. Jiang, Y. Huang, D.C. Larbalestier and E.E. Hellstrom Summary: We studied the origin of (Bi,Pb)/sub 3/Sr/sub 2/Ca/sub 2/Cu/sub 1/O/sub x/ (3221) in (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/-based (2223) wires by varying the amount of 2223 and remnant liquid in wires using slow-cooling and quenching experiments on 2223 green wires. The 3221 phase forms from crystallization of remnant liquid.         Controlled over pressure processing of Bi2223 long length wires    S. Kobayashi, T. Kato, K. Yamazaki, K. Ohkura, K. Fujino, J. Fujikami, E. Ueno, N. Ayai, M. Kikuchi, K. Hayashi, K. Sato and R. Hata Summary: By applying the high isostatic pressure in the final heat treatment, we have raised the critical current (I/sub c/) of multifilamentary (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ (Bi2223) long length wires by greater than 30%. Mechanical performance has reached levels over 250 MPa critical tensile stress at 77 K. The density of filaments in Bi2223 wire was estimated from mass density measurement and found to be increased to filament density. The controlled overpressure process has been found to advantageously heal cracks and porosities of filaments. Densification of the filaments prevents liquid nitrogen penetration during long term exposure to liquid nitrogen of Bi2223 wire for use in power cable applications. Ballooning caused by trapped nitrogen, that expands when warming up to room temperature, doesn't occur in the controlled overpressure processed wire. These high performance levels in long length Bi2223 wires have enabled commercial level products and projects such as power cables, magnets and many others.         Bi-2212 phase formation process in multifilamentary Bi-2212/Ag wires and tapes    T. Koizumi, T. Hasegawa, J. Nishioka, Y. Hikichi, T. Nakatsu, H. Kumakura, H. Kitaguchi, A. Matsumoto and S. Nagaya Summary: We investigated phase formations of multifilamentary Bi-2212/Ag wires during the heat-treatment. We carried out systematic quenching experiments. In the partial-melting process in pure O/sub 2/, when heating rate was 10/spl deg/C/h, melting of filaments was started from central filaments and spread to the edge-located filaments. However, when heating rate was 5/spl deg/C/h, melting of filaments was caused uniformly. In the partial-melting process in 8% O/sub 2/ also, melting of filaments occurred caused uniformly. Phase identification indicates that the existing alkaline earth cuprate was 2:1 alkaline earth cuprate in 8% O/sub 2/ while alkaline earth cuprate was 14:24 alkaline earth cuprate in pure O/sub 2/. These results showed effect of O/sub 2/ partial pressure in filaments. In the slow solidification process, the Bi-2212 phase grew up greatly and broke through the silver matrix in pure O/sub 2/, but the grain growth was suppressed in 8% O/sub 2/, resulting in the suppressing of bridging of Bi-2212 filaments.         Effect of high oxygen pressure post-annealing on the J/sub c/-B characteristics of Bi-2212/Ag tapes    T. Nakane, M. Isobe, T. Mochiku, A. Matsumoto, H. Kitaguchi and H. Kumakura Summary: The effect of oxygen partial pressure, p(O/sub 2/), during the post-annealing process in the fabrication of Bi-2212/Ag tapes was investigated with respect to the critical current density, J/sub c/. High p(O/sub 2/) post-annealing was performed using encapsulation techniques, autoclave furnace and an O/sub 2/-hot isostatic press apparatus. The p(O/sub 2/) was regulated from 1 atm up to 100 atm, and the temperature of this process was fixed at 300/spl deg/C. A p(O/sub 2/) of 6 atm at 300/spl deg/C resulted in the highest J/sub c/ at 4.2 K. This result is consistent for the three different post-annealing techniques. A distinctive change in microstructure was not observed even though the high p(O/sub 2/) post-annealing promoted oxygenation of the Bi-2212 layer. High p(O/sub 2/) post-annealing improves the J/sub c/ of Bi-2212/Ag tape by decreasing electromagnetic anisotropy in the oxide layer. However, an increase in excess oxygen content produces not only a decrease in the electromagnetic anisotropy, but also a decrease in T/sub c/ of the Bi-2212 layer. The degradation of J/sub c/ by higher p(O/sub 2/) post-annealing is considered to be due to the deterioration of T/sub c/. The experimental data suggest that high p(O/sub 2/) post-annealing is one of the most effective techniques for improved J/sub c/, and that post-annealing condition have to be optimized in order to obtain Bi-2212/Ag tape with the highest J/sub c/.         Phase formation and evolution, texturing and current transport in Ag/Bi2212 PIT monofilamentary tapes    D. Rodrigues Jr., A.R. Bigansolli, E. Cursino and P.S. Papini Summary: Superconducting tapes of ceramic material capable of transporting high current densities at high operation temperatures have been revealed as promising conductors in applied superconductivity. Tapes of Ag/Bi2212 present excellent characteristics and their processing techniques are being improved. This work presents a study on the formation of phases and the texturing behavior of Ag/Bi2212 monofilamentary tapes after several heat treatments with different cooling rates from 890/spl deg/C to 830/spl deg/C and silver doping, allowing an optimization of the heat treatment profiles aiming the obtainment of close to stoichiometric superconducting phases with high texturing. The tapes were fabricated using Bi2212 precursor powder and the powder-in-tube (PIT) method. The powder was pressed inside the Ag tube, and the set was mechanically deformed by swaging and rolling to the final thickness of 150 /spl mu/m. After heat treatment, the samples were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) equipped with Energy Dispersive Spectrometer (EDS). The results show the effect of each heat treatment profile on the microstructure and superconducting characteristics of the Ag/Bi2212 tapes, as well as they show the ways to obtain the best texturing of the samples aiming high current transport.         Temperature dependence of critical current at 4.2 K-55 K of conduction-cooled Bi2212/Ag wires for SMES    H. Kojima, S. Noguchi, C. Kurupakorn, N. Hayakawa, M. Goto, N. Hirano, S. Nagaya and H. Okubo Summary: In this paper, fundamental characteristics of conduction-cooled Bi2212/Ag wires and coils for HTS SMES were investigated, in terms of critical current at different temperatures at 4.2 K-55 K. Experimental results revealed that the critical current did not always increase with the temperature decrease, but was saturated or even decreased, depending on the test sample condition. Thermal analysis considering temperature dependence of specific heat and thermal conductivity of the materials could explain the critical current-temperature characteristics, and suggest the possibility to optimize the operating temperature of SMES.         Development of round multifilament Bi-2212/Ag wires for high field magnet applications    Hanping Miao, K.R. Marken Jr., M. Meinesz, B. Czabaj and Seung Hong Summary: Bi-2212/Ag conductor is one of the most promising materials for expanding superconducting magnet applications to higher fields and/or temperatures than present LTS systems. From the view point of practical application, Bi-2212 round wires have significant advantages over more typical HTS tape conductors, such as no anisotropy, ease of handling and simpler coil winding, allowing considerable flexibility in the magnet design. Development efforts at OST have been aimed at enhancing transport properties in long length round wires for high field magnet applications. Recently, significant improvements in the J/sub E/ and J/sub c/ performance have been achieved by optimizing the starting powders, the filament size and fill factor, the deformation processes, and the melt-solidification parameters. The highest J/sub E/ of 266 A/mm/sup 2/ and J/sub c/ of 950 A/mm/sup 2/ at 4.2 K, 45 T with n-value of 17 was obtained in 0.81 mm wire. In this paper progress on the development of Bi-2212 round wires will be reported.         Field dependence of the critical current and its relation to the anisotropy of BSCCO conductors and coils    H.W. Weijers, Bt. Haken, H.H.Jt. Kate and J. Schwartz Summary: The design of HTS magnets is often based on the properties of a number of short samples that are presumed to be representative of the conductor to be used. Variability in conductor properties and inhomogeneity in the magnetic field distribution within the magnets, coupled with conductor anisotropy, provide a significant challenge to accurately predict the field dependence of the magnet critical current. This work is based on measured superconducting properties of Bi-2212 and Bi-2223 conductors at 4.2 K in parallel and perpendicular magnetic fields up to 33 T. Properties of double pancake units and stacks, from the same or similar conductor batches, are presented, based on measurements at self-field and in applied co-axial background magnetic fields up to 19 T. Modeling of this data is based on short sample properties in perpendicular field; the average grain misalignment is used as the parameter to quantify the anisotropy. Correlations and discrepancies between the measured data and models based on short sample data are discussed for Bi-2212 and Bi-2223 conductors.         Compositional and microstructural analysis of high I/sub c/ and J/sub c/ Bi-2212 conductors    T.G. Holesinger, J.A. Kennison, K.R. Marken Jr., Hanping Miao, M. Meinesz and S. Campbell Summary: Compositional analysis of the Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/ (Bi-2212) and secondary phases in high-current Bi-2212 conductors was performed. The composition of the Bi-2212 phase in dip-coated Bi-2212 tapes tended toward the Sr-rich end of the Bi-2212 solid solution. The strontium and calcium contents of the Bi-2212 phase in round wire tended to lie closer to the starting composition of the powder. In all cases, there was an excess of bismuth and a deficiency of the alkaline earths with respect to the ideal 2212 stoichiometry. Microstructural analysis by transmission electron microscopy has shown the presence of Bi-2201 intergrowths within Bi-2212 grains and amorphous layers within the colonies of Bi-2212.         High rate deposition by PLD of YBCO films for coated conductors    T. Watanabe, R. Kuriki, H. Iwai, T. Muroga, S. Miyata, A. Ibi, Y. Yamada and Y. Shiohara Summary: In order to scale-up high-performance YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) coated conductors, we have been investigating pulsed laser deposition (PLD) of YBCO on the "self-epitaxial" PLD-CeO/sub 2/ layer on an ion-beam-assisted deposition (IBAD)-Gd/sub 2/Zr/sub 2/O/sub 7/ (GZO) buffered Hastelloy tape. Our continuous PLD system was designed so that the laser beam scans YBCO targets during deposition and raises plural and discrete plumes (multi-plume), and the substrate was turned three times (multi-turn) around the substrate heater to enlarge its deposition area. The multi-plume and multi-turn (MPT) PLD indicated a capability to unite high rate deposition and high J/sub c/ by enlarging the deposition area under the proper condition. A 21 m long YBCO coated conductor with high end-to-end I/sub c/ of 85.0 A and J/sub c/ of 1.13 MA/cm/sup 2/ was prepared by MPT-PLD. The uniformities of the grain alignment and transport property were also achieved. Furthermore, we succeeded in deposition of a 45.8 m long YBCO layer. The I/sub c/ was as high as 182 A, that the multiplication of I/sub c/ and length reached the highest value of 8.34 kA m.         Transport properties of Ca-doped YBCO coated conductors    N.A. Rutter, J.H. Durrell, S.H. Mennema, M.G. Blamire and J.L. MacManus-Driscoll Summary: The authors have doped RABiTS coated conductor tapes with Ca in an attempt to enhance the transport properties. By diffusing Ca into the YBCO film from a CaZrO/sub 3/ overlayer, the authors have been able to preferentially dope the grain boundaries of the superconductor. Hence it has been possible to obtain doped tapes which do not have a significantly degraded T/sub c/. The authors have measured the critical currents of doped and undoped samples over a wide range of temperature, magnetic field, and magnetic field angle in order to study the effect of Ca on the grain boundaries. The authors find that doping using short anneal times produces enhanced critical currents in large magnetic fields.         High magnetic field properties of critical current density in Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// coated conductor fabricated by improved TFA-MOD process    M. Inoue, T. Kiss, Y. Tsuda, H. Sawa, M. Takeo, S. Awaji, K. Watanabe, Y. Iijima, K. Kakimoto, T. Saitoh, J. Matsuda, Y. Tokunaga, T. Izumi and Y. Shiohara Summary: Current transport characteristics in a Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) coated conductor fabricated by a trifluoroacetates-metal organic deposition (TFA-MOD) process were investigated over a wide range of temperature and magnetic field up to 25 T. Improved TFA-MOD process was successfully introduced for the better property of critical current density, J/sub c/, at high magnetic fields. The J/sub c/ and critical current, I/sub c/, values of multi-coated film with 1.2 /spl mu/m thickness and 1 cm width were 2.1 MA/cm/sup 2/ and 251 A at 77 K in self-field. Additionally, the superior J/sub c/ properties remained even at high magnetic fields over 20 T and lower temperature, e.g. J/sub c/ value at 30 K in 25 T was 1.0 MA/cm/sup 2/. The J/sub c/ value was about 2.5 times higher than those of previous TFA-MOD process at wide range of magnetic field. Moreover, the statistical distribution of J/sub c/ in the conductor was also estimated within a framework of the percolation model. The uniformity in the YBCO coated conductor was improved by optimizing the TFA-MOD process.         Temperature and magnetic field dependence of critical currents in YBCO coated conductors with processing-induced variations in pinning properties    A.A. Gapud, R. Feenstra, D.K. Christen, J.R. Thompson and T.G. Holesinger Summary: Several applications of high-temperature super-conducting wire require high currents at intermediate magnetic fields B and over a range of orientations; however, such conditions are at present achievable only at low temperatures (/spl sim/30 K). The goal of this study is to determine the feasibility of higher operating temperatures for these applications by investigating temperature dependent, low- and high-field pinning properties of YBCO coated conductor samples. The YBCO films were grown on RABiTS templates by a PVD ex situ BaF/sub 2/ process. Variations in pinning properties were induced by introducing excess yttrium (Y) in the precursor and controllably increasing the growth rate. The main result is a more uniform dependence of J/sub c/ over all orientations of B, along with high irreversibility field B/sub irr/ and high critical current densities J/sub c/. Results also show that for films with various pinning properties and processed under different conditions the self-field J/sub c/ at 77 K is an effective indicator of performance in the temperatures and fields of interest.         Influence of tilted geometries on critical current in superconducting thin films    B. Maiorov, B.J. Gibbons, S. Kreiskott, V. Matias, Q.X. Jia, T.G. Holesinger and L. Civale Summary: We present measurements of the angular dependent critical current (J/sub c/) of DyBa/sub 2/Cu/sub 3/O/sub 7/ on single crystal SrTiO/sub 3/ and YBa/sub 2/Cu/sub 3/O/sub 7/ on tilted Ion Beam Assisted Deposition MgO substrate. These experiments demonstrate that J/sub c/ angular dependences of tilted defects are a useful tool to detect misalignments between the internal and applied magnetic fields. The results show that, in order to understand vortex pinning in thin anisotropic samples below certain value of magnetic field, this misalignment must be taken into account.         Normal zone initiation and propagation in Y-Ba-Cu-O coated conductors with Cu stabilizer    Xiaorong Wang, A.R. Caruso, M. Breschi, Guomin Zhang, U.P. Trociewitz, H.W. Weijers and J. Schwartz Summary: In the ongoing effort to investigate the normal zone behavior of coated conductors, the effects of a localized, pulsed heat disturbance on a YBa/sub 2/Cu/sub 3/O/sub x//Ni-alloy conductor with Cu stabilizer was investigated. The sample was conduction cooled by a GM cryocooler in a vacuum environment, establishing nearly adiabatic conditions. A NiCr wire heater mounted on the sample was used to provide the heat pulse that initiated the normal zone. Consecutive voltage taps along the length of both sides of the sample monitored the propagation of the normal zone. Several thermocouples were glued on both sides of the sample to measure the temperature profile of the conductor. The minimum quench energies and normal zone propagation velocities were measured at ambient temperatures from 58 K to 79 K and transport current ranging from 30% to 90% of I/sub c/. The voltage and temperature profiles are presented and discussed.         Development of long Y-123 coated conductors for coil-applications by IBAD/PLD method    Y. Iijima, K. Kakimoto, Y. Sutoh, S. Ajimura and T. Saitoh Summary: Long length Y-123 superconducting tapes were produced by reel-to-reel continuous vacuum processing, by using Ion-Beam-Assisted Deposition (IBAD) and Pulsed-Laser-Deposition (PLD). Biaxially textured Gd/sub 2/Zr/sub 2/O/sub 7/ buffer layers up to 255-m long were fabricated by IBAD with production speed of 0.5-1.0 m/h. Y-123 films were formed on them by PLD with production speed of 1.0-4.0 m/h. A 105-m long Y-123 film was fabricated with uniform thickness of 1.0 /spl mu/m and /spl Delta//spl phi/ of 3-4/spl deg/. I/sub c/ of 126 A was obtained in end-to-end at 77 K, 0 T, whose I-V curve had n-value of 28.5. I/sub c/ times length reached 13,230 Am. Another 70-m long Y-123 tape with I/sub c/ over 90 A (77 K, 0 T) was wound into a Solenoid type magnet whose inner diameter was 60 mm. The central field of 0.27 T was obtained at 66 K, with operating current of 130 A.         Scale up of applications-ready practical Y-Ba-Cu-O coated conductors    V. Selvamanickam, A. Knoll, Y. Xie, Y. Li, Y. Chen, J. Reeves, X. Xiong, Y. Qiao, T. Salagaj, K. Lenseth, D. Hazelton, C. Reis, H. Yumura and C. Weber Summary: YBa/sub 2/Cu/sub 3/O/sub x/ (YBCO) coated conductors have been produced in 100 m lengths in pilot scale facilities established at SuperPower. In addition to scaling up coated conductors to long lengths with high critical current, we have modified the basic conductor for enhanced in-field performance and low ac losses. In addition, our coated conductors have been produced in practical configurations in 4 mm widths and with a surround copper stabilizer. The conductors were slit first to a 4 mm width and then subjected to electroplating to apply the copper stabilizer. Mechanical and electrical properties of the complete conductor have been elaborately tested. 61 m of 4 mm wide, surround copper stabilized conductor was provided to Sumitomo Electric Industries who fabricated a 1 m cable using the conductor. The cable exhibited the lowest ac losses reported with HTS conductors. SuperPower also fabricated a pancake coil with 7.4 m of coated conductor, which generated a maximum magnetic field of 0.28 T at 77 K.         Rapid production of buffered substrates and long length coated conductor development using IBAD, PLD methods and "Self-Epitaxial" ceria buffer    Y. Yamada, T. Watanabe, T. Muroga, S. Miyata, H. Iwai, A. Ibi, Y. Shiohara, T. Katoh and T. Hirayama Summary: Activities at SRL-Nagoya Coated Conductor Center (NCCC) are presented including rapid production of 100 to 220 m buffered substrate tapes and a 46 m YBCO coated conductor using reel-to-reel equipment of both IBAD and PLD systems. A 220 m long IBAD and a 100 m long CeO/sub 2/ capped substrate have been successfully and stably produced. Furthermore, the PLD-CeO/sub 2/, which we call the "Self-Epitaxial" method, is found to be effective to increase a production rate. The combination of IBAD and PLD-CeO/sub 2/ enhanced the overall buffer processing rate up to 2 m/h. This is much higher than the rate of 0.5 to 1 m/h of the conventional IBAD method. We also recently introduced a new PLD system for YBCO, which utilizes a multi-plume and multi-turn deposition, MPT-PLD method. This system is now successfully operating and then very recently we have achieved the record of I/sub c//spl times/L (critical current times length) of 8335 Am. A 45.8 m long YBCO coated conductor carried the high I/sub c/ of 182 A. The MPT-PLD method is also effective to increase the thickness of YBCO with high J/sub c/. Consequently, I/sub c/ as high as 300 A was also obtained for a short sample test. Therefore, the new system of MPT-PLD is very promising for long YBCO tape fabrication.         Long-length YBCO coated stainless steel tapes with high critical currents    A. Usoskin, A. Rutt, J. Knoke, H. Krauth and T. Arndt Summary: Progress in developing long-length YBCO coated conductors (CC) with high critical currents, up to almost 500 A per cm-width, is reported. Coated tapes based on commercial quality stainless steel substrates are manufactured employing a HR-PLD-YBCO together with an IBAD-YSZ processing route (HR-PLD: high-rate pulse laser deposition, IBAD: ion-beam assisted deposition). At 77 K in self field, critical currents up to 495 A per cm tape width were achieved in 4-10 mm wide and 5-9 m long tapes. With a 0.1 mm thick substrate tape employed for CC manufacturing, the engineering current density achieved corresponds to 494 A/mm/sup 2/. At 4.2 K and a parallel magnetic field of 23.5 T, a critical current of typically 1,350 A per cm width was observed. Study of mechanical properties of the coated tapes revealed their outstanding performance under bending and axial stress. Influence of thick shunt layers on the performance of the coated conductor was studied.         Commercial coated conductor fabrication based on inclined substrate deposition    W. Prusseit, G. Sigl, R. Nemetschek, C. Hoffmann, J. Handke, A. Lumkemann and H. Kinder Summary: Due to the complex layered architecture the fabrication of coated conductors consists of a multitude of processing steps. We present a viable and economic route to produce second generation HTS tape from the initial substrate preparation to the final metal coating. The most important and technically challenging steps are the deposition of an oriented buffer layer and the superconductor film in a reel to reel configuration. New evaporation techniques have been developed to enable reliable, high rate tape coating. Highly oriented MgO-buffer layers are realized by inclined substrate deposition (ISD) yielding an in-plane orientation of 7/spl deg/-8/spl deg/ FWHM and critical current densities up to 2.5 MA/cm/sup 2/. Buffered tape has been fabricated up to 40 m length. The subsequent HTS deposition has been performed up to 12 m and reaches current levels of 200 A/cm. High resolution critical current scans help to reveal defects and to track problems in the manufacturing process.         Second generation HTS wire based on RABiTS substrates and MOD YBCO    U. Schoop, M.W. Rupich, C. Thieme, D.T. Verebelyi, W. Zhang, X. Li, T. Kodenkandath, N. Nguyen, E. Siegal, L. Civale, T. Holesinger, B. Maiorov, A. Goyal and M. Paranthaman Summary: The performance of Second Generation (2G) high temperature superconducting wire manufactured by continuous reel-to-reel processes is nearing the 300 A/cm-width (77 K, self field) performance threshold for commercial power cable applications. The 2G manufacturing approach under development at American Superconductor is based on the combination of the RABiTS substrate-buffer technology with metal organic deposition (MOD) of the YBCO layer. The capability of this process has been demonstrated in multiple 10 meter lengths with critical currents exceeding 250 A/cm-width with high uniformity and reproducibility. Critical currents of 380 A/cm-width have been achieved in short length samples prepared by the same basic process. The incorporation of nanoparticles ("nanodots") into the YBCO layer using the MOD process has resulted in a 2-fold improvement in the critical current at 65 K in a 3 T field. The research and development focus at ASMC is now directed toward the economical scale-up of the RABiTS/MOD process, optimization of the conductor properties for targeted applications and the use of 2G wire in initial demonstration applications.         Liquid phase enhanced hybrid MOD approach for high performance YBCO films development    Y. Xu, A. Goyal, K. Leonard, L. Heatherly and P. Martin Summary: High performance YBCO films have been realized through MOD approach by hybrid of Ba-TFA with TMAP (trimethylacetates with propionic). High I/sub c/ over 140 A/cm-w and high J/sub c/ up to 2.4 MA/cm/sup 2/ at 77 K for 0.6 /spl mu/m YBCO films on RABiTS have been shown on un-bridged and bridged samples. Texture characterizations performed in XRD four-circle diffractometer confirmed well-aligned YBCO grains with a volume fraction of cubic phase /spl sim/95%. T/sub c/ measurements showed sharp transitions in less than 1 K and zero resistance above 90 K. The formation of YBCO phase follows the mechanism of interface island nucleation and epitaxial growth. The liquid phase in the precursor enhances Y123 epi-growth and accelerates the conversion process.         Investigation of multi-deposition for high I/sub c/ YBCO coated conductors prepared by PLD on self-epitaxial CeO/sub 2/ buffers    T. Watanabe, H. Iwai, A. Ibi, T. Muroga, S. Miyata, Y. Yamada, Y. Shiohara, T. Kato and T. Hirayama Summary: For fabrication of YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) coated conductors with high J/sub c/, we have investigated pulsed laser deposition (PLD) of YBCO on the "self-epitaxial" PLD-CeO/sub 2/ layer on an ion beam assisted deposition (IBAD)-Gd/sub 2/Zr/sub 2/O/sub 7/ (GZO) buffered Hastelloy tape. A multiple coating of YBCO layer (multi-deposition) improved the uniformity in transport properties. In order to increase I/sub c/, we investigated the proper depositing conditions for a thick YBCO layers. It was found that raising the referential deposition temperature, in accordance with the YBCO layer growths, is effective to suppress a-axis oriented grains and increase I/sub c/. A high I/sub c/ as high as 293 A was obtained in a 10 cm long conductor. Furthermore, we succeeded in the deposition of a 0.8 m long YBCO coated conductor with the end-to-end I/sub c/ of 225 A and J/sub c/ of 1.13 MA/cm/sup 2/. The latter coated conductor also exhibited good uniformity, whose standard deviation of I/sub c/ distribution is 2.2%. These results demonstrated that the multi-deposition applying heater temperature increase corresponding to the YBCO thickness is effective in a preparation of high I/sub c/ and uniform YBCO coated conductors.         Formation of strongly biaxial-textured Ni Layer for YBCO coated conductor by electrodeposition process    J. Yoo, Young-Kuk Kim, Jaewoong Ko, Kyu-Hwan Lee, Kookchae Chung and Hyungsik Chung Summary: A new method of strongly biaxial-textured Ni substrate for YBCO coated conductor has been developed by electrodeposition using cube-textured cathode such as Ni single crystal, RaBiTS-processed Ni or Ni-W tape. Electrodeposited Ni layers using Ni single crystal as a cathode were characterized with /spl theta/-scan and /spl phi/-scan methods, and it showed excellent out-of-plane (/spl Delta//spl theta/=1.6/spl deg/) and in-plane alignment (/spl Delta//spl phi/=3.6/spl deg/). In addition, electrodeposited Ni layers using RaBiTS tape as a cathode show good biaxial texture (/spl Delta//spl theta/=5.7/spl deg/,/spl Delta//spl phi/=9.6/spl deg/) and smooth surface. XRD characterization shows that biaxial texture of cathode was transferred to electrodeposit and texture of electrodeposited Ni layers changes with deposition time. Finally, a CeO/sub 2/ buffer layer has been deposited by MOD process to show the compatibility of substrate with further buffer layer processing. Our modified electrodeposition process shows good possibility of providing a simple and effective way to high quality cube-textured Ni substrates for YBCO coated conductor.         Continuous deposition of thermally co-evaporated YBCO/CeO/sub 2//Ni coated conductors    A. Gauzzi, M. Bindi, L. Gianni, S. Ginocchio, S. Zannella, A. Baldini, B. Holzapfel and F. Bolzoni Summary: By using a simple single-pass reel-to-reel system, we demonstrate a simple and robust in-situ route for the continuous deposition of 1-2 m long Coated Conductors (CC) consisting of 1 /spl mu/m thick superconducting YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) films deposited by thermal co-evaporation onto 100 nm thick CeO/sub 2/ buffered cube textured Ni tapes. The buffer layer was deposited by either e-beam or thermal evaporation using respectively ceria or metallic cerium. The structural and morphological properties of the samples were investigated by X-ray /spl thetav/-2/spl thetav/ Bragg-Brentano, and pole figure diffraction, Nomarsky optical microscopy and Scanning Electron Microscopy (SEM) analysis. The 123 composition was controlled during deposition by means of an atomic absorption system. The optimized buffer layer and YBCO layer are grown at 690/spl deg/C in respectively forming gas and oxygen partial pressures of 5/spl times/10/sup -5/ mbar. These conditions ensure the growth of dense and crack-free layers with good biaxial texture, as indicated by FWHM's values in the 5-7/spl deg/ range for both in- and out-of-plane orientations. Zero-resistance critical temperatures T/sub c/=86-87 K with transition widths /spl Delta/T/sub c/<3 K are reproducibly obtained. End-to-end critical current densities J/sub c/ at 77 K and self-field typically are in the 1.5-2.5 MA/cm/sup 2/ range, as measured by transport measurements. It is found that tape motion does not significantly affect these properties.         Improved YBCO coated conductors using alternate buffer architectures    M.P. Paranthaman, S. Sathyamurthy, M.S. Bhuiyan, A. Goyal, T. Kodenkandath, X. Li, W. Zhang, C.L.H. Thieme, U. Schoop, D.T. Verebelyi and M.W. Rupich Summary: The Rolling-Assisted Biaxially Textured Substrates (RABiTS) process has been identified as one of the leading candidates for the fabrication of high performance YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) coated conductors. The RABiTS process uses standard thermomechanical processing to obtain long lengths of flexible, biaxially oriented substrates with smooth surfaces. The strong biaxial texture of the metal is then transferred to the superconductor by the deposition of intermediate oxide buffers that serve both as a chemical and structural buffer. The typical three-layer RABiTS architecture consists of an e-beam Y/sub 2/O/sub 3/ seed, sputtered YSZ barrier and a sputtered CeO/sub 2/ cap layer. Chemical solution deposition of buffer layers offers potential cost advantage relative to physical vapor deposition (PVD) processes. Our main goal of this study is to develop simplified buffer architectures and demonstrate high J/sub c/ Metal-Organic Deposition (MOD)-YBCO films on all-MOD buffers. La/sub 2/Zr/sub 2/O/sub 7/ (LZO)/CeO/sub 2/ buffers have been identified as potential candidates for this study. MOD-YBCO films with a critical current, I/sub c/ of 212 A/cm have been achieved on MOD-LZO seeds with sputtered YSZ and CeO/sub 2/ cap layers. In addition, MOD-YBCO films with a critical current, I/sub c/ of 140 A/cm have been achieved on all MOD buffers of LZO/CeO/sub 2/ for the first time. This offers a potential toward fabrication of lower cost YBCO coated conductors.         YbBa/sub 2-x/Sr/sub x/Cu/sub 3/O/sub 7-/spl delta// coated conductor development by sol-gel process    L. Arda, S. Aktas and Y.S. Hascicek Summary: YbBa/sub 2-x/Sr/sub x/Cu/sub 3/O/sub 7-/spl delta// coated conductors were grown on Gd/sub 1.8/Ho/sub 0.2/O/sub 3/ buffer layered biaxially textured-Ni (100) substrates by the reel-to-reel sol-gel dip coating system. Sample with different Sr substitution ratio (x=0.0, 0.1, 0.2, 0.3, 0.4, and 0.6) were heat treated using varying heat treatment parameters. The surface morphologies and microstructure of all samples were investigated by ESEM, EDS and XRD. The critical current measurements were performed using four-wire method with the 1 /spl mu/V/cm criterion. The critical current density, J/sub c/ was measured to be 10/sup 5/ A/cm/sup 2/ at 4.2 K and 10/sup 4/ A/cm/sup 2/ at 75 K in-self field for YbB/sub 1.9/Sr/sub 0.1/Cu/sub 3/O/sub 7-/spl delta// sample.         Fluorine analysis and microstructural evolution in coated YBCO conductor deposited by metal trifluoroacetate process    M.V. Rane, H. Efstathiadis, H. Bakhru, M.W. Rupich, X. Li, W. Zhang, T. Kodenkandath and P. Haldar Summary: A solution based processes using metal trifluoroacetate (TFA) precursors is being developed for commercialization of Yttrium Barium Copper Oxide (YBCO) coated conductors. This nonvacuum technique uses inexpensive precursors and has the advantage of easy scalability, ease of composition control, eliminates carbonate formation during decomposition, and helps maintain film uniformity during heat treatment. However, fluorine remains incorporated in the YBCO film, depending on process conditions, and may result in a reduction of Jc. An appropriate heat treatment schedule ensures reduction of fluorine in the YBCO films as well as an improvement in microstructural properties. The aim of this work was to investigate the fluorine depth profile, density, and microstructural evolution of metal organic deposited (MOD) YBCO films with heat treatment using focused ion beam (FIB) microscopy, nuclear reaction analysis (NRA), and Rutherford backscattering spectroscopy (RBS). Multilayer structures studied consisted of 0.7 /spl mu/m to 2.0 /spl mu/m-thick YBCO layers deposited on a NiW alloy substrate buffered with CeO/sub 2//YSZ/Y/sub 2/O/sub 3/.         YBCO thin films prepared by fluorine-free polymer-based chemical solution deposition    C. Apetrii, H. Schlorb, M. Falter, I. Lampe, L. Schultz and B. Holzapfel Summary: We describe a new chemical solution deposition (CSD) route toward inexpensive and environmentally friendly preparation of YBCO coated conductors. This route is based on a fluorine-free polymer and exhibits some advantages compared to the TFA route, where trifluoroacetate precursors are used and aggressive HF is formed during the heat treatment. In this work, the main parameters influencing the structure and properties of YBCO films prepared by means of the polymer method are investigated. For the preparation of the YBCO films, stoichiometric amounts of Y, Ba and Cu nitrates were dissolved in a solution of polyacrylic acid in dimethylformamide. This metal polymer precursor solution was spin coated onto strontium titanate (STO) single crystals. After drying in air, the films were heat treated in an oxygen containing nitrogen atmosphere. The film structure was analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). T/sub c/ and J/sub c/ were measured inductively. The preliminary results show that the amount of oxygen during heating and in the dwell time strongly influences the superconducting properties. Good superconducting properties, with T/sub c/ of 89.9 K (/spl Delta/T/sub c/=1.1 K) and J/sub c/ of 10/sup 6/ A/cm/sup 2/ at 77 K, have been obtained on epitaxially grown 250-nm-thick YBCO films using the polymer-based precursors.         Magnetic-field properties of high critical current density YBCO films deposited by TFA-MOD    S.B. Kim, S. Murase, Y. Yamada, T. Araki and I. Hirabayashi Summary: The critical current density, Jc, of metal-organic deposition process using trifluoroacetates (TFA-MOD) based YBCO films was measured between 20 K and 77 K in magnetic fields up to 9.5 T as a function of the field direction. C-axis oriented YBCO films was deposited on LaAlO/sub 3/ single crystalline substrates and also on CeO/sub 2/ buffered IBAD (YSZ/Hastelloy) substrates by TFA-MOD method. The obtained Jc values at 77 K and 0 T were 7 and 1.7 MA/cm/sup 2/ for LaAlO/sub 3/ and IBAD substrates, respectively. High Jc values over 10/sup 5/ A/cm/sup 2/ were maintained up to 4 T (B//c-axis) for the LaAlO/sub 3/ substrate and up to 3 T (B//c-axis) for the CeO/sub 2/ buffered IBAD substrate. These results imply that TFA-MOD with simple fabrication process is very promising for the practical YBCO coated conductor. And the dependences on temperature and angular of the Jc at various external magnetic fields for some different thicknesses YBCO films was reported.         Fabrication of high-jc YBCO films by the TFA-MOD Process using YBCO powder as precursor    Geo-Myung Shin, Sung-Hun Wee, Hee-Gyoun Lee, Gye-Won Hong, Kyu-Jeong Song, Chan Park, Seung-Hyun Moon and Sang-Im Yoo Summary: YBCO thin films were prepared on LaAlO/sub 3/ (100) single-crystal substrates using the metal-organic deposition of trifluoroacetates (TFA-MOD). Unlike the normal TFA-MOD process, TFA-based solutions were prepared dissolving YBCO powder into the trifluoroacetic acid solvent. The solutions were coated on the substrates by spin coating, fired at the temperature up to 400/spl deg/C in 4.2% humid and oxygen atmosphere, fired again at the temperature region of 725-850/spl deg/C for 2 h in 4.2% humidity and 1000 ppm oxygen partial pressure, and finally oxygenated at 450/spl deg/C for 1 h. Similar to the normal TFA-MOD process, both microstructure and superconducting properties of YBCO films were highly sensitive to the firing temperature. Optimally processed YBCO films of /spl sim/250 nm thickness exhibited T/sub C,zero/ of 90 K and J/sub C/ of 2.9 MA/cm/sup 2/ at 77 K in a self-field. The present results clearly evidence that our cost-effective modified TFA-MOD process is applicable to the fabrication of YBCO coated conductors.         Effects of heating rate in calcination process on microstructures of Y123 precursor and final films formed by advanced TFA-MOD method    J.S. Matsuda, K. Nakaoka, Y. Tokunaga, R. Teranishi, S. Koyama, Y. Aoki, H. Fuji, A. Yajima, Y. Yamada, T. Izumi and Y. Shiohara Summary: We have investigated the effects of heating rates in the calcination process on microstructures of Y123 precursor and final films. As a result, it was found that there is CuO segregation in the vicinity of the Y123 precursor film surface, when the precursor is prepared at a rapid heating rate in the calcination. In the case of heat-treating this precursor film in the crystallization process, many large pores and misoriented Y123 crystals tend to remain in the Y123 final film. It is important to control the heating rate in the calcination, in order to attain higher J/sub C/ of the Y123 final films.         Low-pressure conversion studies for YBCO precursors derived by PVD and MOD methods    F.A. List, P.G. Clem, L. Heatherly, J.T. Dawley, K.J. Leonard, D.F. Lee and A. Goyal Summary: The rate at which thin film YBCO precursor converts to high J/sub c/ superconductor depends on many factors including the method by which the precursor is prepared, the precursor film thickness, and the conditions during precursor deposition and conversion. Using in-situ X-ray diffraction and reduced pressures, we have examined and compared conversion rates for precursors prepared by physical vapor deposition (PVD) and metal-organic deposition (MOD). For conversion conditions found to be optimal for obtaining high J/sub c/ and high precursor conversion rate (G/sub p/) for PVD precursors, the G/sub p/ is nearly identical (/spl sim/0.2 nm/sec) for the both PVD and MOD precursors. The development of crystalline BaF/sub 2/ is, however, distinctly different for the two precursors. This may suggest that conversions of these PVD and MOD precursors follow different chemical pathways. For both precursors, higher G/sub p/ is realized using higher water pressure and ramp rate. Although G/sub p/ is higher, YBCO is randomly oriented and J/sub c/ is zero for the PVD precursor. The MOD precursor seems to be generally more tolerant of higher reaction rates than the PVD precursor. The reaction rate versus P/sub H2O/ determined for both precursor types shows a square root of P/sub H2O/ dependence of G/sub p/. This behavior is consistent with a reaction rate limited by gas-phase HF removal.         Comparison of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// precursors made using TFA-MOD and BaF/sub 2/ ex-situ processes and their post-deposition processing under low pressure conditions    Yifei Zhang, M.P. Paranthaman, R. Feenstra, T. Aytug and D.K. Christen Summary: Two ex-situ techniques including metal-organic deposition using solution from trifluoroacetates (TFA-MOD) and electron beam co-evaporation using BaF/sub 2/ are regarded as promising candidates for fabricating long-length, uniform, high critical current density (J/sub c/) YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) superconducting films for practical applications. It is generally accepted that the precursors made by these two methods and their post-deposition processing are basically similar. Typical MOD-TFA and e-beam BaF/sub 2/ precursors were made and then annealed in our low-pressure processing system. It was found that the conditions required for the conversion of these two types of precursors are quite different. The precursors were compared in terms of the differences in their composition and pre-conversion structure. The conversion behaviors were studied by structure characterization and property measurement. The effect of composition, especially the fluorine content on the conversion reaction is discussed.         High-Jc thick YBCO coated conductors by TFA-MOD process    R. Teranishi, J. Matsuda, K. Nakaoka, H. Fuji, Y. Aoki, Y. Kitoh, T. Izumi, Y. Yamada and Y. Shiohara Summary: The TFA-MOD process was applied to fabricate YBCO films on PLD-CeO/sub 2//IBAD-Gd/sub 2/Zr/sub 2/O/sub 7//Hastelloy substrates. In order to obtain higher Ic performance, thicker films maintaining high J/sub c/ values are required. J/sub c/ depends strongly on the YBCO crystal alignment. Dependences of J/sub c/ on /spl Delta//spl phi/ of the CeO/sub 2/ substrates has been investigated. It was found that the J/sub c/ value increased with improvement of the crystal alignment of the CeO/sub 2/ buffer layers. Also, the J/sub c/ value depended strongly on the P/sub H2O/ during the crystallization. The pore size in the film was smaller in the high J/sub c/ films fabricated under medium P/sub H2O/ and becomes larger in the low-J/sub c/ films under low and high P/sub H2O/. Furthermore, crack formation was observed in thick films crystallized at high P/sub H2O/. The large pore causes local reduction of current paths and additionally introduces the concentration of electric fields. It was found that both the porosity and crack formations limit the J/sub c/ properties. Finally, a YBCO film with 2.05 /spl mu/m in thickness was fabricated on a CeO/sub 2//Gd/sub 2/Zr/sub 2/O/sub 7/ layer buffered Hastelloy substrate with /spl Delta//spl phi//spl sim/4/spl deg/. A J/sub c/ value of 2.02 MA/cm/sup 2/ and transport I/sub c/ value of 413 A at 77 K, self-field were obtained.         Transport properties of YBa/sub 2/Cu/sub 3/O/sub 7/ and NdBa/sub 2/Cu/sub 3/O/sub 7/ films prepared on textured Ag tapes    T. Doi, T. Kozono, Y. Hakuraku, N. Kashima and S. Nagaya Summary: We obtained the {100}<001> textured Ag tape with both a good biaxial crystal orientation and a smooth surface, by precise control of the rolling process parameters. On this {100}<001> textured Ag tape, YBa/sub 2/Cu/sub 3/O/sub 7/ (Y-123) and NdBa/sub 2/Cu/sub 3/O/sub 7/ (Nd-123) films were deposited by using a pulsed laser deposition method. "Y-123/Nd-123/{100}<001> textured Ag tape" sample had both good biaxial orientation and smooth surface, as a result, relatively high J/sub c/ of 0.57/spl times/10/sup 6/ A/cm/sup 2/ at 77 K in self field was achieved. Present J/sub c/ value is not competitive comparing with the other techniques for coated conductors (CC), such as IBAD or RABiTS, however, it is very promising. We believe that the J/sub c/ of CC using {100}<001> textured Ag tapes will increase after optimizing the Y-123 deposition process.         Long and high rate production of IBAD templates for YBCO coated conductors    S. Miyata, T. Muroga, H. Iwai, A. Ibi, T. Watanabe, Y. Yamada, Y. Shiohara, T. Kato and T. Hirayama Summary: Ion-beam-assisted deposition (IBAD) is a promising method for preparation of biaxially textured templates for YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) coated conductors. For the purpose of practical applications, many groups make efforts to obtain long and high-performance YBCO superconducting wires based on IBAD templates. In our laboratory, long IBAD template tape fabrication using a reel-to-reel system was developed and up to now, we have fabricated a 220-m-long tape successfully and 103-220 m tapes have been obtained steadily. On these IBAD template tapes, high critical current (I/sub c/) performances were demonstrated and a large I/sub c/ value of 182 Amps was attained with pulsed laser deposited YBCO conductors on 46 m in length. These values give a product of I/sub c//spl times/L over 8000 Am.         Development of textured Au Layer on Ni substrate for YBCO coated conductors    Jun Hyung Lim, Jung Ho Kim, S.H. Jang, Kyu Tae Kim, Jin Sung Lee, Jinho Joo, Chan-Joong Kim, Hong-Soo Ha and Chan Park Summary: Much effort has been made to develop new metallic buffers to explore the possibility of designing YBCO coated conductors (CC's) with a simple architecture. We selected Au because of its small lattice mismatch to Ni and chemical novelty, and plated it on a biaxially textured Ni substrate by the electroless-plating method. The texture of Au/Ni template was evaluated by X-ray pole-figure and orientation distribution function (ODF) analysis. The surface roughness and grain boundary morphology were characterized by atomic force microscopy (AFM). We fabricated the cube textured Au/Ni template for the CC and evaluated its texture formation and microstructural evolution. Texture analysis indicated that the Au layer was epitaxially deposited on the Ni substrate and formed a strong cube texture when the processing variables were optimized. The full-width at half-maximum (FWHM) was 8.4/spl deg/ for out-of-plane and 9.98/spl deg/ for in-plane texture when the plating time was 30 min. In addition, the root-mean-square (RMS) and the depth of the grain boundary for the Au layer were 14.6 nm and 160 /spl Aring/, respectively, which are significantly smaller than the corresponding values for the Ni substrate (27.0 nm and 800 /spl Aring/), indicating that the electroless-plated Au layer had a relatively smooth surface and effectively mollified grain grooves.         Investigation of processing variables of Ni substrate for YBCO coated conductors    Jun Hyung Lim, Kyu Tae Kim, Ho Jin Kim, Jinho Joo, W. Nah, Gye Won Hong, Jung-Goo Lee and H. Mori Summary: We fabricated cube textured Ni substrates for YBCO coated conductors from the initial specimens prepared by powder metallurgy (P/M) and casting and evaluated the effects of annealing temperature on microstructural evolution and texture formation. To characterize the roles of the two preparation methods, the initial specimens were prepared to be of the same size and experienced the same rolling conditions, and were then annealed in the temperature range of 600/spl deg/C to 1200/spl deg/C. The texture was evaluated by X-ray pole-figure analysis and transmission electron microscopy (TEM). The texture analysis indicated that a strong cube texture formed for the substrate made by P/M and this texture did not vary significantly with annealing temperature in the range of 600-1200/spl deg/C. On the other hand, the texture of the substrate made by casting was more dependent on the annealing temperature, and a twin texture ({221}<221>) and several minor texture components began to form at 1000/spl deg/C. Microstructural observation showed that the morphology of deformation band together with micro-band in the as-rolled tape prepared by P/M was more homogeneous and of higher density than that produced by casting, resulting in a strong cube texture in wider range of annealing temperatures and a finer microstructure after recrystallization.         Effect of W addition on the microstructure and properties of Ni-W substrates for coated conductors    Kyu Tae Kim, Jun Hyung Lim, Jung Ho Kim, S.H. Jang, Jinho Joo, Chan-Joong Kim, Kyu Jeong Song and Hyung Sub Shin Summary: We fabricated Ni and Ni-W alloys for use as substrates in YBCO coated conductor applications and evaluated the effects of the W addition on the texture, microstructure, and mechanical and magnetic properties of the substrate. Pure Ni and Ni-W (2, 3, and 5 at.%) alloys were prepared by plasma arc melting and then cold rolled and annealed in the temperature range of 600-1300/spl deg/C. The texture of the substrates was evaluated by pole-figure and orientation distribution function (ODF) analysis. The magnetic properties were also evaluated using the physical property measurement system (PPMS). It was observed that the Ni-W substrates had a stronger cube texture and a wider annealing temperature range in which the cube texture became stable than those of the pure Ni substrate. The full-width at half-maximums (FWHMs) of in-plane texture for the Ni-W substrate were 4.42/spl deg/-5.57/spl deg/ at an annealing temperature of 800/spl deg/C-1300/spl deg/C, while that of pure Ni was 9.5/spl deg/ at 800/spl deg/C. Therefore, it is considered that the addition of W enhances the formation of the cube texture and improves the texture stability at higher annealing temperatures. In addition, the Ni-W substrates had a smaller grain size and higher mechanical strength and hardness, as compared to those of the pure Ni substrate. These improvements are probably due to various strengthening mechanisms, such as solid solution hardening and/or grain size strengthening. PPMS analysis showed that the addition of W effectively reduced the saturation magnetization in an applied magnetic field, as well as the Curie temperature.         Thermal treatments for biaxially textured Cu-Ni alloys for YBCO coated conductors    J.L. Soubeyroux, C.E. Bruzek, A. Girard and J.L. Jorda Summary: We have studied the thermal treatments necessary to texture Cu-Ni alloys in view of applications as substrate for the YBCO coated conductors. Several alloy compositions chosen in order to avoid magnetism of the tapes have been elaborated by the rolling (RABiTS) method. Analyzes of the texture as a function of annealing temperature have been done by X-ray and neutron diffractions, pole figures by EBSD and X-rays. The results show that the annealing temperature is dependant of the alloy composition and must be determined precisely for each composition. Good biaxial textures have been obtained on these cheap alloys.         YBCO films and CeO/sub 2//YSZ/CeO/sub 2/ buffer layers grown on Ni-Cr-W RABiTS with a Pd seed layer    G. Celentano, V. Galluzzi, A. Mancini, A. Rufoloni, A. Vannozzi, A. Augieri, T. Petrisor, L. Ciontea, A. Tuissi, E. Villa and U. Gambardella Summary: A CeO/sub 2//YSZ/CeO/sub 2/ buffer layer structure was epitaxially deposited by pulsed laser deposition on a Pd seed layer grown on non magnetic Ni/sub 88/Cr/sub 8/W/sub 4/ alloy. Structural analyzes performed by x-ray diffraction and EBSD show a good texture, with typical YBCO FWHM of about 5/spl deg/ and 8.5/spl deg/ for in-plane and out-of-plane orientations, respectively. About 300 nm YBCO films deposited by PLD on such a buffer layer structure, show typical values of critical temperature of about 89 K and a critical current density greater than 0.6 MA/cm/sup 2/ at 77 K and self field.         Continuous deposition and rapid fabrication of self-epitaxial CeO/sub 2/ cap layers by PLD method on IBAD buffers    T. Muroga, S. Miyata, T. Watanabe, A. Ibi, Y. Yamada and Y. Shiohara Summary: We have fabricated long buffered substrate tapes by a reel-to-reel process. The architecture is a self-epitaxial PLD-CeO/sub 2/ cap layer on an IBAD-Gd/sub 2/Zr/sub 2/O/sub 7/ buffered Hastelloy-C 276 tape. At the same time, we have investigated the effect of the deposition temperature for self-epitaxial growth of the PLD-CeO/sub 2/ cap layer. We found that a deposition temperature of 500/spl deg/C for the self-epitaxial PLD-CeO/sub 2/ cap layer is the best in the range of 200/spl deg/C and 800/spl deg/C for O/sub 2/ pressure of 10-30 mTorr in terms of the in-plane grain alignment. At the deposition temperature of 500/spl deg/C in the reel-to-reel process, we obtained a PLD-CeO/sub 2/ cap layer with /spl Delta//spl phi/ values of about 5 degrees at a tape transfer speed of 6 m/h for IBAD-GZO tapes with /spl Delta//spl phi/ values of about 15 degrees in 100 m class long tapes. Furthermore, we also obtained a PLD-CeO/sub 2/ cap layer with better /spl Delta//spl phi/ values of 3.7-4.4 degrees at a tape transfer speed of 2 m/h for a 55 m long tape.         Preparation of CeO/sub 2/-buffer layers for large-area MOD-YBCO films (10/spl times/30 cm/sup 2/) with high-J/sub c/    M. Sohma, I. Yamaguchi, K. Tsukada, W. Kondo, K. Kamiya, S. Mizuta, T. Manabe and T. Kumagai Summary: Epitaxial cerium oxide (CeO/sub 2/; thickness: 40 nm) buffer layers were deposited on large area (maximum size 10/spl times/30 cm/sup 2/) R-cut single-crystal sapphire (/spl alpha/-Al/sub 2/O/sub 3/) substrates by double electron-beam guns. Substrate heater-and-holder system was modified to maintain the substrate temperature uniform over the large area during deposition. Oxygen gas of a pressure 4/spl times/10/sup -2/ Pa was introduced to keep radio frequency plasma. When the substrate temperature was controlled in the range 640/spl deg/-700/spl deg/C, the CeO/sub 2/ buffer showed a complete [001] orientation and very smooth surfaces by x-ray diffraction analysis and atomic force microscopic observations, respectively, in the whole area of the large size substrates. These buffer layers without post-deposition annealing were quite suitable for preparing YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) films by a metal-organic deposition (MOD) using a metal acetylacetonate-based solution. The average critical current density of the 210-nm-thick MOD-YBCO film was in excess of 2.6 MA/cm/sup 2/ measured by an inductive method at 77.3 K.         Synthesis and characterization of Cu-doped SrTiO/sub 3/ powders and sol-gel processed buffer layers on IBAD MgO templates    A. Ayala, T.G. Holesinger, P.G. Clem, V. Matias, Q.X. Jia, Haiyan Wang, S.R. Foltyn and B. Gibbons Summary: Copper-doped SrTiO/sub 3/ (STO) powders were processed by conventional bulk preparation techniques to establish solubility limits of Cu in STO. The maximum solubility of Cu in STO was identified to be /spl sim/1%. Epitaxial Cu-doped SrTiO/sub 3/ (STO) buffer layers were then prepared by pulsed laser deposition (PLD) and chemical solution deposition (CSD) on ion-beam-assisted deposition (IBAD) magnesium oxide (MgO) flexible metallic textured tapes. Transmission electron microscopy (TEM) analysis of the /spl sim/100 nm thick buffer layer deposited by PLD showed a smooth Cu-doped STO/MgO interface. Films deposited by CSD had an average film thickness of 30 nm and exhibited growth by heterogeneous nucleation with no secondary reaction phases. YBa/sub 2/Cu/sub 3/O/sub 7-/spl part// (YBCO) films were deposited onto the Cu-doped STO buffer layers by PLD.         Fabrication of meter-long coated conductor using RABiTS-PVD methods    Rock-Kil Ko, Chan Park, Ho-Sup Kim, Jun-Ki Chung, Hong-Soo Ha, Dongqi Shi, Kyu-Jeong Song, Sang-Im Yoo, Seung-Hyun Moon and Young-Cheol Kim Summary: The practical application of HTS materials in power devices requires the HTS conductor which is long, powerful (high current carrying), and affordable. Many different methods for making practical coated conductor include multiple ways of obtaining texture templates and a variety of film deposition methods which include both physical and chemical routes. In this work, three film deposition systems (pulsed laser deposition, sputtering, and evaporation) equipped with reel-to-reel metal tape moving apparatus were installed and used to make meter-long coated conductor. Buffer architecture of CeO/sub 2//YSZ/Y/sub 2/O/sub 3/ was continuously deposited on Ni alloy using sputtering, evaporation, and PLD. YBCO superconducting layer was continuously deposited on buffered metal tape by pulsed laser deposition. End-to-end critical current I/sub c/ of 80 A and critical current density J/sub c/ of 1.3 MA cm/sup -2/ for 600 nm-thick YBCO at 77 K, self-field have been achieved in 1 cm-wide tape over 1 meter length. Longitudinal distribution of the I/sub c/ values was between 72 A/cm and 90 A/cm.         Development of single solution buffer layers on textured Ni substrate for HTS coated conductors    Y.X. Zhou, X. Zhang, H. Fang, P.T. Putman and K. Salama Summary: Much effort has recently been made to develop chemical methods for the manufacturing of coated conductors because of their scalability, low cost and high deposition rate. In this research, epitaxial buffer layers of Gd/sub 2/Zr/sub 2/O/sub 7/ (GZO) have been grown on Ni substrates using a newly developed metal organic decomposition (MOD) approach. The solution prepared from metal-organic precursors was deposited on Ni substrates using the dip coating technique and then was annealed at a high temperature. Texture analysis shows full-width-at-half-maximum (FWHM) values for out-of-plane and in-plane alignments as 6.5/spl deg/ and 8.1/spl deg/, respectively. Pole figure studies indicate a single cube-on-cube texture while SEM micrographs reveal a dense, continuous, and crack-free buffer layer. MOCVD was used to grow 1 /spl mu/m YBCO film on this GZO buffered Ni substrate. A critical current, J/sub c/, of about 1.3 MA/cm/sup 2/ at 77 K and self-field was obtained on YBCO (MOCVD)/GZO(MOD)/Ni. These results give promise to using a single buffer layer for scalable coated conductors.         High-Ic HoBCO coated conductors by PLD method    K. Ohmatsu, S. Hahakura, K. Hasegawa and M. Ueyama Summary: Ho/sub 1/Ba/sub 2/Cu/sub 3/O/sub x/ (HoBCO) coated conductors by using Pulsed Laser Deposition (PLD) have been developed on textured Ni-alloy substrates. Hetero-epitaxial growth of CeO/sub 2//YSZ/CeO/sub 2/ was developed to introduce in-plane alignment for buffer layers. CeO/sub 2/ seed and cap layers were deposited by RF sputtering. YSZ diffusion layer was deposited by PLD. The most advantage of buffer layers are high growth rate and large deposition area by using in-plane alignment of textured substrate. This was demonstrated by a high production speed of buffer layers. CeO/sub 2/ and YSZ buffer layers show a high production speed of 7 m/h and 8 m/h, respectively. As for the HoBCO deposition, a production speed of 10 m/h was demonstrated by using high growth rate of 4 /spl mu/m/min in our PLD process. Ic of the short sample reached 357 A/cm-width at 77 K, 0 T, and 2,423 A/cm-width at 30 T, 4.2 K. Long length HoBCO conductors up to 35 m were performed by using reel to reel tape transfer system of each process.         High-J/sub c/ Gd-Ba-Cu-O epitaxial films prepared by pulsed laser deposition    K. Matsumoto, D. Takahara, T. Horide, A. Ichinose, S. Horii, Y. Yoshida, M. Mukaida and K. Osamura Summary: For applications of high-temperature cuprate superconductors in magnetic fields at 77 K, a RBa/sub 2/Cu/sub 3/O/sub x/ (R123; R=Nd, Sm, Gd, etc.) film is one of the promising materials due to its high critical temperature T/sub c/ and high irreversibility field B/sub irr/. Especially, a substitution between R and Ba sites that results in a T/sub c/ degradation is not likely to occur in GdBa/sub 2/Cu/sub 3/O/sub x/ (Gd123) films, compared to the cases of Nd and Sm ions. This is an advantage for an application of Gd123 film. We studied the c-axis oriented Gd123 film for obtaining a high critical current density J/sub c/ in a magnetic field at 77 K. The substrate temperature to deposit the epitaxial films on MgO(100) was varied between 700-800/spl deg/C under an oxygen partial pressure of 200 mTorr. T/sub c/ values of the films were within 89.8-92.7 K. Interestingly, the J/sub c/ at 77 K for 5 T (B//c) reached 0.2 MA/cm/sup 2/. The values are three times higher than those of Y123 films, which indicate that Gd123 films have the superior potentiality in magnetic fields at 77 K.         Comparative study of REBa/sub 2/Cu/sub 3/O/sub 7/ films for coated conductors    Q.X. Jia, B. Maiorov, H. Wang, Y. Lin, S.R. Foltyn, L. Civale and J.L. MacManus-Driscoll Summary: We carried out systematic investigation on the processes and characteristics of REBa/sub 2/Cu/sub 3/O/sub 7/ or RE123 (RE=Nd, Sm, Eu, Dy, Ho, Er, and Yb) films on single crystal SrTiO/sub 3/ for coated conductors. The higher transition temperature, the higher growth rate, and the much better surface morphology for the large RE's such as Nd123, Sm123, and Eu123 make them attractive for thick films. The larger processing window for some other RE123 materials such as Dy123 and Yb123, on the other hand, makes them striking for scale-up and fabrication of long-length conductors. In the case of mixed RE's, enhanced pinning from ion size variance is also observed. We present our comparative study of the field- and angle-dependent critical current densities between these RE123 and Y123 films.         High critical current density in high field in Sm/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub 6+y/ thin films    Y. Yoshida, Y. Ichino, M. Miura, Y. Takai, K. Matsumoto, A. Ichinose, S. Horii and M. Mukaida Summary: Critical current density (J/sub c/), irreversibility field (B/sub irr/) and microstructure in epitaxial SmBa/sub 2/Cu/sub 3/O/sub 7-x/ (SmBCO) films are reported. We have developed a novel approach to deposit high performance Sm/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub 6+y/ (Sm-123) at relatively low substrate temperature on MgO. The use of thin SmBCO seed layer grown at a high substrate temperature enabled us to obtain fully c-axis oriented SmBCO films with high critical current density (J/sub c/) of 2.8/spl times/10/sup 5/ A/cm/sup 2/ under 5 T for B//c at 77 K. This value is as high as in the optimized NbTi superconducting wires achieved for 5 T at 4.2 K. Compared with YBa/sub 2/Cu/sub 3/O/sub 7-y/ films, Sm-123 films showed higher J/sub c/ in high fields at 77 K. Transmission electron microscopy TEM analyses clarified the Sm/Ba composition ratio fluctuations in the Sm-123 matrix composition in the range of x=0/spl sim/0.14 with a wavelength of 50/spl sim/100 nm.         Microstructural study of EuBa/sub 2/Cu/sub 3/O/sub 7/ films by high resolution X-ray diffraction    Y. Lin, H. Wang, M.E. Hawley, S.R. Foltyn and Q.X. Jia Summary: Recent studies have shown that EuBa/sub 2/Cu/sub 3/O/sub 7/ (Eu123) films exhibit excellent surface morphology, high transition temperature, and interesting field-dependent critical current density, which are important for thin film devices and coated conductor applications. In this paper, we report our detailed studies of the microstructures of the Eu123 films deposited under different conditions. We have used high-resolution x-ray diffraction (HRXRD) to investigate the texture evolution and micro-domains of the films. Reciprocal space maps (RSMs) show that the a-axis growth of Eu123 films on SrTiO/sub 3/ substrates at a given deposition temperature is directly related to the deposition rate. On the other hand, by inserting a DyBa/sub 2/Cu/sub 3/O/sub 7/ (Dy123) seed layer, the a-axis growth can be totally eliminated. HRXRD study further reveals that micro-domains with different c-axis lattice parameters are often formed in the Eu123/Dy123, which may result from different oxygen content.         Continuous fabrication of IBAD-MgO based coated conductors    V. Matias, B.J. Gibbons, A.T. Findikoglu, P.C. Dowden, J. Sullard and J.Y. Coulter Summary: Reel-to-reel tape processing capable of fabricating tens of meters of coated conductor has been set up at Los Alamos National Laboratory. These reel-to-reel facilities include electropolishing, IBAD-MgO texturing, buffer layer deposition, REBaCuO pulsed laser deposition and position dependent critical current and ac-loss measurement. The systems enable development of long-length coated conductors as well as high-throughput experimentation. IBAD-MgO is an extremely fast process, demonstrated at 100 meters/hour, but requires smooth surfaces over long lengths, which is achieved in our laboratory by electropolishing of metal alloy tapes. Barrier and buffer layers are optimized to minimize interdiffusion from the substrate into the superconductor and to maximize crystalline alignment. YBCO is deposited in a multi-zone heater that allows for an engineered heating power profile as the YBCO film is deposited. Currently the best critical current result on a 1 meter length for a 3 /spl mu/m thick YBCO layer is 350 A (self field, 75.5 K).         Nucleation of YBa/sub 2/Cu/sub 3/O/sub 7/ from precursor films using the barium fluoride process    V.F. Solovyov, H.J. Wiesmann and M. Suenaga Summary: Coated-conductor applications of YBCO require YBCO layers with high J/sub c/ and a thickness of several micrometers. The barium fluoride process offers a convenient way of depositing crack-free fluorinated precursor layers up to 5 microns thick. However, converting thick precursor layers into c-axis-oriented YBCO films is challenging due to extensive nucleation of random grains. In this paper we address this problem with both a theoretical and experimental analysis of YBCO nucleation. We utilized optical polarization contrast to observe YBCO nuclei imbedded in the precursor matrix. We observed that the nuclei density strongly depends on processing parameters, with the oxygen partial pressure being one of the strongest factors. During ex-situ processing the nuclei merge and form grains and the nuclei density is, therefore, directly related to the grain size of YBCO film. It is desirable to have a small grain structure, since large grains do not connect well and the J/sub c/ of such a film is low. However, attempts to increase the nuclei density also generates more randomly oriented grains. Therefore the optimization of ex-situ processing is essentially finding a balance between c-axis grain density and random grain content.         Progress in R&D for coated conductors by TFA-MOD processing    T. Izumi, H. Fuji, Y. Aoki, R. Teranishi, K. Nakaoka, J. Matsuda, Y. Kitoh, Y. Yamada, Y. Shiohara, Y. Iijima, T. Saitoh, T. Goto, A. Yoshinaka and A. Yajima Summary: Recent progress in the research and development of the TFA-MOD processing for the coated conductors in Japan was reviewed. For the higher Ic performance, the optimizations both in the calcinations and crystallization steps have taken place. Consequently, the extremely high Ic value of 413 A was achieved by the combination of the information from the above investigations and the use of highly textured CeO/sub 2/ cap layered substrates. Concerning the development of long tapes, a 8.6-m-long tape with its end-to-end Ic value of 119 A was successfully grown by a reel-to-reel system. Additionally, improvement of the production rate in the calcination step was realized by designing a multi-turn system.         High J/sub c/ YBCO thin films and multilayers grown by chemical solution deposition    A. Pomar, M. Coll, A. Cavallaro, J. Gazquez, J.C. Gonzalez, N. Mestres, F. Sandiumenge, T. Puig and X. Obradors Summary: Chemical solution deposition (CSD) has emerged as a very competitive technique to obtain superconducting films of high quality. However, there is still few knowledge about how underlying microstructure can affect the performances of the YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) films. Here we will summarize our recent progress in this subject. We have grown YBCO thin films by the so called trifluoroacetate route on top of buffer layers also grown by CSD. By modifying the growth conditions of SrTiO/sub 3/ and BaZrO/sub 3/ buffer layers we have investigated the influence of surface roughness and grain size. The role of lattice parameter mismatch has been studied by producing multibuffered architectures such as SrTiO/sub 3//BaZrO/sub 3//LAO. It has been proved that YBCO thin films with critical currents in excess of 1 MA/cm/sup 2/ at 77 K in self field can be achieved, thus demonstrating the abilities of the CSD technique.         Fabrication of YBCO superconducting tape by metal organic chemical vapor deposition method    Byung-Hyuk Jun, Jun-Kyu Choi, Ho-Jin Kim and Chan-Joong Kim Summary: YBCO films for coated conductors (CC) were fabricated by a metal organic chemical vapor deposition (MOCVD) system of hot-wall type using a single source. The deposition condition was optimized using (100) SrTiO/sub 3/ single crystal substrates in a steady state, and then the substrate was replaced by moving IBAD template (CeO/sub 2//IBAD-YSZ/stainless steel) of 40 cm/hr. Two different types of IBAD templates with thin CeO/sub 2/ and thick CeO/sub 2/ layers were used. The mole ratio of MO source was Y(tmhd)/sub 3/:Ba(tmhd)/sub 2/:Cu(tmhd)/sub 2/=1:2.1:2.9, and the YBCO films were prepared at the deposition temperatures of 780/spl sim/890/spl deg/C. The a-axis growth was observed together with the c-axis growth up to 830/spl deg/C, while the c-axis growth became dominant above 830/spl deg/C. The top surface of the c-axis film was fairly dense and crack-free. In case of the YBCO film with a 2.2 /spl mu/m thickness deposited on the SrTiO/sub 3/ substrate at 860/spl deg/C, the deposition rate was as high as 0.37 /spl mu/m/min. The critical current and critical current density of the film was 104 A/cm-width and 0.47 MA/cm/sup 2/, respectively. The YBCO film deposited on the IBAD template with a thin CeO/sub 2/ layer showed a low critical current of 2.5 A/cm-width, while the YBCO film deposited on the IBAD template with a thick CeO/sub 2/ layer showed a higher critical current of 50 A/cm-width. It indicates that the stable buffer layer at high deposition temperature is needed for the MOCVD process.         Spray pyrolysis of YBa/sub 2/Cu/sub 3/O/sub 7-x/ coated conductors on (100) SrTiO/sub 3/ substrate    H.L. Suo, M. Schindl, N. Clayton, N. Musolino and R. Flukiger Summary: YBa/sub 2/Cu/sub 3/O/sub 7-x/ films have been deposited using spray pyrolysis on (100) SrTiO/sub 3/ substrate. An extended study on the optimization of the composition, carrying gas flow, deposition temperature as well as annealing time was performed. It was found that these parameters are strongly correlated and affect the morphology, orientation and superconducting properties of the YBCO films. As grown films already exhibit J/sub c/ values of 10/sup 4/ A/cm/sup 2/, thus indicating that the correct structure is already formed during deposition. It was found that the temperature gradient in the pyrolysis zone played a fundamental role during the deposition. After modification of this heat gradient by adding a metallic susceptor, a noticeable improvement in the properties of the films was obtained. An in-plane orientation FWHM value of 0.70/spl deg/ was measured from the (102) pole figure. The films exhibited a T/sub c/ onset of 91 K (/spl Delta/T/sub c/=1.5 K), while the J/sub c/ value at 77 K in self-field approached 10/sup 5/ A/cm/sup 2/. Based on an assumed typical intragranular critical current density, we found a 40/spl times/40 /spl mu/m area in our best film where the assumed critical current density is well above 10/sup 6/ A/cm/sup 2/.         MOCVD and spray pyrolysis for coated conductor synthesis    L. Vergnieres, S. Donet, C. Jimenez, P. Odier, F. Weiss, C.E. Bruzek and J.M. Saugrain Summary: A reel-to-reel MOCVD system has been optimized to get high quality YBCO coated conductor tapes. The buffer layer architectures, the superconducting film as well as the silver shunt layer were deposited in this reactor. Reported stacking are YSZ/CeO/sub 2//YBCO and CeO/sub 2//YBCO, respectively, on Ni/CeO/sub 2/ alloys (5%W) and on SS/YSZ (IBAD) tapes. Epitaxial growth was depicted with a strong in-plane and out-of-plane texture: FWHM of YBCO phi-scans were 6.6/spl deg/ on Ni tapes and 8.3/spl deg/ on IBAD hastelloy ones. High performance was obtained with Jc values reaching 0.6 MA/cm/sup 2/ at 77 K (sf) on Ni tape and larger than 1.3 MA/cm/sup 2/ on IBAD substrates. Critical currents over 80 A/cm were attained on samples prepared with a tape velocity set at 4.6 m/h. Beside MOCVD, spray pyrolysis has been developed as an alternative method to decrease significantly the equipment and the production costs. This technique works at atmospheric pressure and uses an aqueous solution of nitrates as precursors. First transport measurements gave Ic values close to 20 A/cm (77 K, sf) on single crystals. Textured YBCO was also deposited on metallic tapes.         Fabrication of coated conductors by multiple-stage CVD    N. Kashima, T. Niwa, M. Mori, S. Nagaya, T. Muroga, S. Miyata, T. Watanabe, Y. Yamada, T. Izumi and Y. Shiohara Summary: The multiple-stage Chemical Vapor Deposition technique was developed for making a long coated conductor with high deposition speed. In this paper, a multi-coating of YBCO layer using 6-stage CVD system was described. Substrates were PLD-CeO/sub 2//IBAD-Gd/sub 2/Zr/sub 2/O/sub 7//Hastelloy. Thickness of each layer was about 1.0 /spl mu/m, 1.0 /spl mu/m and 0.1 mm respectively. /spl Delta//spl phi/ of CeO/sub 2/ layer was about 9-10/spl deg/. Deposition rate of YBCO layer was 25 m/h and 5 m/h. Number of passing was 10 times and 2 times respectively. I/sub c/ of the tape which was prepared at a speed of 25 m/h /spl times/ 10 passes was 100 A/cm. Thickness of total YBCO layer was about 1 /spl mu/m and its J/sub c/ was 1 MA/cm/sup 2/. I/sub c/ of the tape which was prepared at a speed of 5 m/h /spl times/ 2 passes was 101 A/cm. Thickness of total YBCO layer was also 1 /spl mu/m and its J/sub c/ was 1 MA/cm/sup 2/.         Preparation of YBa/sub 2/Cu/sub 3/O/sub x/ film deposited on various substrates by MOCVD Processing    Ho-Jin Kim, Jinho Joo, Jun-Kyu Choi, Byung-Hyuk Jun and Chan-Joong Kim Summary: YBa/sub 2/Cu/sub 3/O/sub x/ films were deposited on various substrates (MgO, SrTiO/sub 3/, IBAD, and textured Ni) by metalorganic chemical vapor deposition (MOCVD) processing. The deposition condition was optimized using MgO and SrTiO/sub 3/ single crystal substrates. At low deposition temperatures (T/sub d/) below 700/spl deg/C, a-axis films were obtained, a-axis and c-axis films at the intermediated T/sub d/ of 720/spl deg/C-740/spl deg/C, and fully c-axis films were obtained at T/sub d/ above 740/spl deg/C. The critical current (I/sub c/) of the YBCO films with the film thickness of 0.6 /spl mu/m was 49 A/cm-width (J/sub c/=0.82 MA/cm/sup 2/). When the film thickness increased to 1.6 /spl mu/m, the I/sub c/ increased to 84.4 A/cm-width, but J/sub c/ decreased to 0.53 MA/cm/sup 2/. The degradation of J/sub c/ is attributed to the formation of a-axis grains and grains misoriented from the c-axis in the upper part of the films. The YBCO films were successfully deposited on CYC (CeO/sub 2//Y-stabilized ZrO/sub 2/(YSZ)/CeO/sub 2/ on textured Ni), CYY(CeO/sub 2//YSZ/Y/sub 2/O/sub 3/ on textured Ni), and IBAD(CeO/sub 2//YSZ on stainless steel) templates. The I/sub c/s of the YBCO films were 9.5 A/cm-width, 45.8 A/cm-width, and 46.3 A/cm-width, respectively.         Fast growth process of long-length YBCO coated conductor with high critical current density    Yijie Li, J. Reeves, X. Xiong, Y. Qiao, Y. Xie, P. Hou, A. Knoll, K. Lenseth and V. Selvamanickam Summary: On the basis of previously reported 10 m long YBCO tape with over 100 A/cm performance, we are working toward scaling up the YBCO coating process to 100 m lengths. We are using a high tape speed of 15 m/h for fabrication of long lengths. To understand the mechanism of high growth rates of YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) on buffered metal substrates, the relationship between critical current density and YBCO film thickness has been systematically investigated. When YBCO thickness was below one micrometer, the critical current density (J/sub c/) was over 2 MA/cm/sup 2/. As YBCO thickness was increased, J/sub c/ decreased gradually. However, J/sub c/ still remained 0.91 MA/cm/sup 2/ at a YBCO thickness of 4.2 /spl mu/m. Critical current (I/sub c/) was 380 A across 1 cm wide tape at 77 K. To scale up the YBCO coating process, the deposition rate was increased to a growth rate of 70 nm/s, corresponding to a tape speed of 15 m/h. The average phi-scan rocking curve of YBCO films was /spl sim/3/spl deg/ on 11/spl deg/ buffered metal tape. The omega scan rocking curve (FWHM) was just 1.5/spl deg/. J/sub c/ of 2 MA/cm/sup 2/ at 77 K and self-field was achieved at a high deposition rate of 70 nm/s and a tape speed of 15 m/h by optimizing deposition parameters. The high rate process has been transferred to long lengths and results will be discussed in this manuscript.         Critical state of YBCO superconductors with artificially patterned holes    E. Bartolome, X. Granados, T. Puig, X. Obrados, E.S. Reddy and S. Kracunovska Summary: The magnetic behavior of melt-textured YBCO materials containing columnar holes has been systematically investigated with the help of a new "current-tracer" software based on the critical state model, and magnetic Hall probe imaging. The influence of the different geometrical distribution of holes, hole size and hole density on the remanent magnetization profiles and the effective-to-local critical current density ratio is discussed. For the single-crystalline YBCO samples with artificially patterned holes studied, the measured magnetization maps and J/sub c//sup eff//Jc ratios agree nicely with the simulations.         The effect of oxygen partial pressure on melt growth processing for filamentary Dy-Ba-Cu-O Superconductors    E. Ban, Y. Ikebe, Y. Matsuoka and K. Watanabe Summary: Precursor filaments of Dy-Ba-Cu-O super-conductor were prepared by a solution spinning method and partially melting in an atmosphere gas with various oxygen concentrations. It was found that the transport Jc value at 77 K and 0 T of the filamentary sample was strongly dependent on the partial-melting temperature and gas atmosphere. The samples partially melted under flowing 1%O/sub 2/+Ar gas exhibited Jc values larger than 10/sup 4/ A/cm/sup 2/ over a wide temperature range of 980-1040/spl deg/C and a dense microstructure. The filamentary sample with the starting composition of Dy:Ba:Cu=1.18:2.12:3.09 treated at 1020/spl deg/C under flowing 1%O/sub 2/+Ar showed a transport Jc value greater than 4.3/spl times/10/sup 4/ A/cm/sup 2/ at 77 K and 0 T, and the Jc value of 2.0/spl times/10/sup 3/ A/cm/sup 2/ was maintained up to the magnetic fields of 14 T. The samples partially melted in 20%O/sub 2/+Ar gas and 100%O/sub 2/ gas showed relatively low Jc value of 6.0/spl times/10/sup 3/ A/cm/sup 2/ and 1.2/spl times/10/sup 2/ A/cm/sup 2/ at most.         Critical current density of HTS single crystal YBCO thin films in applied dc field    Y.V. Cherpak, V.A. Komashko, S.A. Pozigun, A.V. Semenov, C.G. Tretiatchenko, E.A. Pashitskii and V.M. Pan Summary: Magnetic field and angle dependencies of critical current density J/sub c/(H,/spl theta/) are measured for single-crystal c-oriented epitaxial YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films with high J/sub c//spl ap/2 MA/cm/sup 2/ at 77 K. Films are deposited by off-axis dc magnetron sputtering onto r-cut sapphire substrates buffered with CeO/sub 2/. Experimental evidences of the dominant contribution of extended linear defects (growth-induced out-of-plane edge dislocations) to pinning mechanism and critical current behavior are presented. A consistent model of vortex lattice depinning from a linear defect system is developed. Detailed J/sub c/(H) measurements start from very low fields (<0.001 T). Qualitatively different angle dependencies J/sub c/(/spl theta/) are obtained in different field ranges. Their evolution is comprehended on the base of depinning model. The "peak-effect" observed in J/sub c/(H)-dependencies at parallel magnetic field is discussed as a contribution of electromagnetic pinning.         J/sub c/(H) crossover in YBCO thick films and Bi2223/Ag tapes with columnar defects    Qiang Li, M. Suenaga, S.R. Foltyn and H. Wang Summary: We report a study of critical current density J/sub c/ as a function of temperature T, magnetic field H, and film thickness d in a series of high quality YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) films. A crossover in the thickness dependence of J/sub c/(H) curves was observed for T>50 K, where thinner film carries significantly lower J/sub c/(H) than thicker film at high fields, while the opposite was observed at low fields. This J/sub c/(H) crossover behavior seems to be a general feature for a superconducting system with a spectrum of pinning density, whose trend opposes to the effective volume faction for J/sub c/. This generalization is supported by examining J/sub c/(H) crossover behaviors observed earlier in the Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10+/spl delta//(Bi2223)/Ag tapes irradiated with 5.8 GeV Pb ions, where enhanced J/sub c/(H) at high fields is attributed to the density increase in the columnar flux pinning centers.         Effect of strain on grain and grain-boundary critical currents of YBCO coated conductors    A. Palau, T. Puig, X. Obradors, R. Feenstra and H.C. Freyhardt Summary: We present a comparative analysis on tensile strain tolerance of critical currents for IBAD and RABiTS coated conductors. These measurements have been performed with a recently developed methodology based on dc-magnetization measurements, which enables us to analyze the grain and grain-boundary critical current densities simultaneously. We show that the percolative grain-boundary critical current density may be reduced by 50% with deformations of /spl epsiv//spl sim/0.32% and 1% for RABiTS and IBAD, respectively, while the grain critical current and thus the pinning properties of the grains are not affected by the deformation process.         Transport measurements and J/sub c/ simulations for RABiTS based coated conductors-doping and grain architecture    J. Hanisch, Chuanbing Cai, V.S. Sarma, L. Schultz and B. Holzapfel Summary: The critical current density in RABiTS (rolling assisted biaxially textured substrates) based coated conductors is limited by the network of small-angle grain boundaries up to a texture dependent crossover field H/sub co/. The current flow through this network is percolative in nature and thus depends on misorientation angle distribution, the width and length of the tape, and on the grain shape. These dependencies were simulated using a fast and simple limiting path algorithm on real grain boundary networks obtained by electron backscattering diffraction (EBSD) and cross-checked with transport measurements. A strong dependence of J/sub c/ on conductor width below 20 grains and a large increase in J/sub c/ for elongated grains was found. H/sub co/ of tapes with very sharp cube textures are around 1 T at 77 K. Hence, the intra-grain pinning must be increased for a further improvement of coated conductors applied in higher magnetic fields. With transport measurements on YBa/sub 2/(Cu/sub 1-x/Zn/sub x/)/sub 3/O/sub 7-/spl delta// single crystalline thin films, the possibility of a J/sub c/ increase due to Zn doping was investigated. Monolayer films with Zn contents up to 0.2%, however, showed a decrease in J/sub c/ and H/sub irr/, whereas multilayer films with x=0.017% and x=0.025% Zn) showed an increase in J/sub c/ at 77 K.         Coordinated characterization of coated conductors (C/sup 4/)    V.A. Maroni, K. Venkataraman, D.J. Miller, S. Trasobares, Y. Lei, J.M. Hiller, K.E. Gray, V.K. Vlasko-Vlasov, H. Claus, J. Reeves, M.W. Rupich, W. Zhang, T. Kodenkandath and X. Li Summary: Argonne National Laboratory, in collaboration with American Superconductor and SuperPower, Inc., has established/implemented a coordinated set of characterization methods for coated conductor specimens that can be applied in a manner compatible with further processing or utilization of the respective specimen. These characterization methods include measurements of superconductor transport properties, phase composition, microstructure, and epitaxy quality for YBCO coated conductors that range in size up to multi-meter-length tapes. Recent examinations involving the integrated application of magneto-optical imaging (MOI), Raman microspectroscopy, and focused-ion-beam-assisted transmission electron microscopy (TEM) to meter-length tapes have pinpointed specific microstructural and chemical defects that correlated with poor Ic performance.         Critical currents I/sub c/(77 K)>350 A/cm-width achieved in ex situ YBCO coated conductors using a faster conversion process    R. Feenstra, A.A. Gapud, F.A. List, E.D. Specht, D.K. Christen, T.G. Holesinger and D.M. Feldmann Summary: Implementation of improved processing for BaF/sub 2/ ex situ YBCO coatings from e-beam evaporated precursors enables faster conversion with rates up to 12 /spl Aring//s and critical currents I/sub c/ at 77 K greater than 350 A/cm-width on a RABiTS template. Details of the faster processing are described and compared to an earlier slower process. A linear relation between I/sub c/ and YBCO layer thickness provides evidence of new opportunities to further improve I/sub c/.         Identification of intrinsic ab-plane pinning in YBa/sub 2/Cu/sub 3/O/sub 7/ thin films and coated conductors    L. Civale, B. Maiorov, J.L. MacManus-Driscoll, H. Wang, T.G. Holesinger, S.R. Foltyn, A. Serquis and P.N. Arendt Summary: The angular-dependent critical current density J/sub c/ in YBa/sub 2/Cu/sub 3/O/sub 7/ films grown by pulsed laser deposition exhibit a sharp peak for magnetic field orientations near the ab plane, which arises from the combined effects of intrinsic pinning and extended defects parallel to the planes. An analysis of the temperature and field dependence of the height and width of this peak allows us to distinguish both contributions. We find that, in a film on single crystal substrate, the peak at low fields is due primarily to the extended defects, but at high fields it is dominated by intrinsic pinning. We compare these results with those of coated conductors with a larger density of ab-oriented correlated defects. We show a novel effect consisting in an inverse correlation between J/sub c/ and the power law exponent (N) of the I-V curves that only occurs in the intrinsic-pinning dominated regime, and we present an interpretation of its origin.         A new measurement method for AC losses in circular disks of superconducting films in perpendicular magnetic fields    M. Suenaga, J.R. Clem and S.R. Foltyn Summary: An expression P=2R/sub c/V/sub L rms/H/sub a rms/ was theoretically derived for the ac power losses in a circular superconducting disk in a perpendicular ac applied magnetic field when the losses are measured by a planar circular pickup coil surrounding the disk. Here, R/sub c/ is the radius of the pickup coil, which is coplanar with the disk, and V/sub L rms/ and H/sub a rms/ are rms values of the loss voltage and applied magnetic field. This method of measuring losses has an advantage over a susceptibility technique, since the coil need not be calibrated. However, this expression is valid only for large values of R/sub c/ relative to the radius R of the disk, since the dipole approximation was used in the derivation. We experimentally evaluated the minimum value of the diameter 2R/sub c/ for which this method provided approximately correct losses. A YBa/sub 2/Cu/sub 3/O/sub 7/ disk with diameter 2R/spl ap/5.3 mm was used for the measurements. The electronically determined apparent losses at all field values decreased with increasing coil radius, and asymptotically approached a constant value for R/sub c//R>/spl sim/3.         AC losses of coated conductors in perpendicular fields and concepts for twisting    M.D. Sumption, P.N. Barnes and E.W. Collings Summary: AC losses for striped and unstriped YBCO coated conductors are presented. The loss for a sample subdivided into 10 filaments is shown to be reduced by the expected factor of 10. Various concepts for introducing strand twisting are investigated, and some estimates are given for their superconductive filling factors and the resulting twisting-induced strain. Additionally, the concept of winding induced effective twist is described, and the effective induced twist pitch is shown to be approximately two times the length of the winding. The influence of end-soldering of the strands is described, and simple estimates of the coupling losses are given for a striped strand with soldered ends in conjunction with an effective induced twist.         AC losses in striated YBCO coated conductors    M. Majoros, B.A. Glowacki, A.M. Campbell, G.A. Levin, P.N. Barnes and M. Polak Summary: We measured AC losses in RABiTS nonstriated as well as striated coated conductors provided by the US Air Force Research Laboratory. In addition, samples with different kinds of well defined inter-filament bridging have been measured and their losses compared with those of samples with unbridged filaments and with mono-layer samples. This bridging is designed to aid current sharing between filaments, which is advantageous, but it is necessary to determine if the effect on AC losses is detrimental. It was found that AC losses of striated samples with multiple bridges are higher than those of the samples with no bridges due to significant filament coupling but even so the losses are still substantially lower than those of a monolayer sample.         A method to reduce magnetization losses in assembled conductors made of YBCO coated conductors    O. Tsukamoto, N. Sekine, M. Ciszek and J. Ogawa Summary: A method is proposed to reduce AC magnetization losses in YBCO tape-shaped coated conductors subject to external AC magnetic fields. To reduce the magnetization losses, it is well known that the YBCO film should be subdivided into multiple filaments. In this multifilamentary conductor, the electromagnetic coupling between the filaments should be suppressed to reduce the AC losses by twisting the conductor somehow. The proposed method is that a YBCO layer on a substrate of a coated conductor is subdivided into multiple filaments by slanted striations and that a quasi-twisted assembled conductor is composed by soldering a pair of those striated tapes. The effect of the twisting is obtained by this composition without twisting the conductor itself. A numerical simulation showed that magnetization losses in a quasi-twisted conductor were greatly reduced at a sacrifice of a slight increase of the transport current losses.         Low AC loss structures in YBCO coated conductors with filamentary current sharing    P.N. Barnes, G.A. Levin, C. Varanasi and M.D. Sumption Summary: Architectural design improvements, such as filamentation, to YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) coated conductors can result in a more ac-tolerant version of the conductor. However, finely made striations in the conductor make filament breakage more probable. In this case, weakly linking the filaments can enable current sharing among the filaments of striated coated conductors while maintaining reduced hysteretic losses. Data is presented for a YBCO sample divided into superconducting filaments separated such that the transverse critical current density of the striation is significantly less than the longitudinal critical current density along the filaments. A LAO substrate was physically scribed with parallel incisions to adversely affect the subsequent epitaxial growth of the YBCO layer between the striations. Vibrating sample magnetometry measurements verified a reduction in hysteretic loss compared to a control sample of epitaxially grown YBCO on an unscribed LAO substrate. Since filamentation requires a twist in the conductor for practical applications, a discussion is also given outlining an alternate means of accomplishing this by placing a twist in the coated conductor architecture itself.         AC loss measurement with a phase difference between current and applied magnetic field    D.N. Nguyen, P.V.P.S.S. Sastry, G.M. Zhang, D.C. Knoll and J. Schwartz Summary: Total AC losses in multi-filamentary, silver-sheathed Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub y/ (Bi-2223) tape were measured as functions of transport current, applied magnetic field and frequency by electromagnetic and calorimetric methods. Results of both methods agree well with each other. The calorimetric method was employed to investigate the effect of the phase difference between transport current and applied field, /spl Delta//spl phi/, on total AC loss. Total loss changes significantly with /spl Delta//spl phi/ when applied magnetic field is perpendicular to the surface of the sample. The effect of /spl Delta//spl phi/ on total loss in parallel magnetic applied field is smaller.         Critical current and AC loss of Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10//Ag tapes subjected to tensile stress    Guo Min Zhang, D.N. Nguyen, A. Mbaruku, P.V.P.S.S. Sastry and J. Schwartz Summary: Practical applications of HTS tapes cannot avoid various stresses and strains, including tension, bending and/or torsion. These loads directly affect the critical current and AC losses of HTS tapes. Thus the investigation of the effect of stress/strain on HTS tapes is important for practical applications. Here, the critical currents and AC losses are measured at 77 K for different Bi2223/Ag composite tapes under different room temperature stress/strain. The strain dependence of the critical currents and AC losses of Bi2223/Ag composite superconducting tapes are studied. A comparison is given for the measured results and the values calculated from the formulae developed from the Norris formula and critical current-strain relationship.         AC magnetization loss reduction by striation in YBCO-123/Hastelloy coated conductors    O. Tsukamoto, M. Ciszek, N. Sekine and H. Suzuki Summary: In the work we present experimental results of AC magnetization losses reduction due to striation process in YBCO-123/Hastelloy coated conductors. The measurements were carried out in a sinusoidally varying external magnetic field, with amplitudes up to 100 mT, in a frequency range of 8.5-85.4 Hz, and at temperature of 77 K. The field was oriented perpendicularly to the face of the tapes. Sample tapes were successively patterned into a form of narrow, parallel strips, by means of a photoresist lithography and chemical wet etching technique. Experimental results are discussed in a framework of existing theoretical models for energy dissipation in thin films in perpendicular AC magnetic fields.         AC loss of YBCO coated conductors fabricated by IBAD/PLD method    T. Nishioka, N. Amemiya, N. Enomoto, Zhenan Jiang, Y. Yamada, T. Izumi, Y. Shiohara, T. Saitoh, Y. Iijima and K. Kakimoto Summary: The AC losses of YBCO coated conductors fabricated by the IBAD/PLD method were electromagnetically measured. Both the magnetization loss without transport current and the total AC loss during the simultaneous application of AC transport current and an AC external magnetic field were measured. The AC losses were numerically calculated using the one-dimensional FEM model. The magnetic field dependence and the spatial distribution of critical current density were taken into account in numerical calculations, and the calculated AC losses were compared with the measured AC losses. The critical current, the transport current, and the applied external magnetic field were varied in order to calculate the total AC loss systematically.         AC losses in first and second generation high T/sub c/ tapes and MgB/sub 2/ tapes    S. Ginocchio, E. Perini, R. Jakomin, F. Fontana, S. Zannella and L. Martini Summary: Technical and economical assessments for future power applications of High T/sub c/ superconductivity require the evaluation and comparison of AC losses in first and second generation high T/sub c/ tapes. An electrical and a thermometric method were developed and used to measure transport AC loss in OPIT Bi-2223/Ag tapes, Y-123 coated conductors and in new MgB/sub 2/-based superconductors, simulating the AC conditions typical of power devices. The results were compared with analytical models for AC losses calculation. The effect of the magnetic substrates used in coated conductors was also investigated and a simple calculation model was proposed.         Numerical analysis of AC loss characteristics of YBCO coated conductors arranged in parallel    Y. Ichiki and H. Ohsaki Summary: AC losses and electromagnetic phenomena in assembled conductors composed of YBCO coated conductors arranged in parallel were studied by finite element method (FEM). The analysis tool is based on the current vector potential method with thin-plate approximation and with strongly nonlinear E-J characteristics (E: electric field, J: current density) of superconductor. In this paper the dependence of AC losses and electromagnetic phenomena on the intervals between the conductors was investigated.         Numerical analysis of magnetization loss in finite-length multifilamentary YBCO coated conductors    S. Kasai and N. Amemiya Summary: In typical YBCO coated conductors with a width of 10 mm, a large AC loss is generated in a perpendicular transverse magnetic field. One of the means of reducing the AC loss is to divide the YBCO film into narrow filaments. The AC loss characteristics of multifilamentary YBCO coated conductors having a finite length were studied by numerical electromagnetic analysis using FEM. We neglected the current component perpendicular to the wide face of conductor; thus, the problem to be solved was reduced to a two-dimensional one on a plane parallel to the wide face of the conductor. An equivalent nonlinear resistivity obtained from a power law E-J relation was used to represent the superconducting property of filaments. The magnetization losses were calculated from the temporal evolution of current distribution in YBCO coated conductors. The frequency dependence of the calculated magnetization loss was discussed based on the change in the current distribution in the conductor. The conductor specifications as well as the operating conditions were varied in order to study their influence on AC loss characteristics.         Calculation of AC losses in HTS tape with FEA program ANSYS    Chen Gu and Zhenghe Han Summary: The commercially available finite element analysis program ANSYS, primarily designed for solving problems for ferromagnetic materials and conventional conductors, has been used for simulating the ac losses in HTS tape carrying transport current or exposed to a perpendicular field. Details on how to develop the program as a calculation tool for HTS materials are presented; in particular some factors related to the numerical accuracy and efficiency are discussed. The approach is based on a 2D electromagnetic transient analysis, where the conductivity of the HTS material is simulated in terms of a power law. The commonly used flux creep model and Bean model can be realized by adjusting the power law index value from 2 to /spl infin/. For the Bean model, the simulated results are verified by comparison with the analytical formulas given by Norris, which shows the error to be less than 0.5%. For the flux creep model, the accuracy is estimated by comparison with Brandt's method for a basic cylinder geometry, showing a good agreement.         Numerical calculation of Ac losses in stacked Bi-2223 tapes exposed to oblique magnetic field    T. Hayashi, K. Kajikawa, M. Iwakuma and K. Funaki Summary: We numerically calculated ac losses in a parallel conductor composed of three Bi-2223 tapes exposed to an external transverse magnetic field by means of a previously proposed two-dimensional finite element method that directly analyses the magnetic field distribution around the conductor. In this analysis, we can set a transport current in each Bi-2223 tape individually. Assuming no transport current in each tape, we estimated the ac losses in the parallel conductor with perfect transposition. We also calculated the ac losses in the parallel conductor without transposition under the condition that the total transport current is zero. It was found in the parallel field configuration that the ac losses are drastically decreased due to the transposition in a range of higher amplitude. In the case of perpendicular field, on the other hand, the ac losses are scarcely dependent on the transposition. Furthermore we numerically estimated the dependence of the ac loss on the field angle to the flat surface of the tapes in the transposed parallel conductor. The obtained results well explain the experimental ones especially in the higher amplitude of applied field.         Modeling of current density distributions in critical state by commercial FE codes    S. Farinon, P. Fabbricatore, F. Gomory, M. Greco and E. Seiler Summary: The method of minimum magnetic energy variation has proved its merit in modeling the magnetic field interaction with hard type-II superconductors. Its main advantage is that the front of flux penetration is calculated starting from a physical principle equivalent to the Bean's critical state model. We have developed a procedure that adapts the above-mentioned method to the environment of the commercial finite element code ANSYS. As a step forward with respect to existing works, this allows to include magnetic materials into simulations. The case of a superconducting strip covered by a ferromagnetic sheath is reported.         Estimation of apparent AC transport losses for cylindrical conductors composed of superconductor tapes    R. Inada, Y. Nakamura, A. Oota and T. Fukunaga Summary: The distributions of resistive electric field under alternating current transmission and the apparent AC transport losses have been investigated on cylindrically assembled conductors with superconductor tapes through the numerical calculations. Several superconductor tapes with a rectangular cross section of various sizes were arranged on a cylindrical former, in a parallel way to the conductor axis. Numerical calculation of the resistive electric field distributions and the apparent AC transport losses were performed, by taking account of the geometry and the arrangements of tape strands under Bean's critical state model. The influence of the form and arrangement of tape strands on the electric field distributions and the apparent losses is discussed.         Formation of submicron-thick oxide barrier for reducing AC loss in multifilamentary Bi2223 tapes    K. Osamura, N. Wada, T. Ogawa and F. Nakao Summary: Barrier surrounding oxide superconducting core is effective in reducing AC loss of the multifilamentary tape. Metallic magnesium was chosen as its precursor material. Through the ordinary deformation process to fabricate the tape, the magnesium layer was easily thinned up to sub-micron. By the successive oxidation treatment, the barrier became a stable MgO layer. Usefulness of ductile material has been demonstrated to produce ultra-thin barrier.         AC losses in HTS bulk at various temperatures    K. Yamagishi, I. Asaba, S. Sekizawa, O. Tsukamoto, J. Ogawa, K. Kikukawa and M. Hirakawa Summary: HTS bulks applied to electric machines are exposed to AC magnetic field perturbations which cause AC losses in the bulks. AC losses affect the efficiency of the machines and decay the trapped magnetic field in an HTS bulk. Critical current density and the maximum trapped magnetic field of a bulk are enhanced as temperature is decreased. Thereby, the lower temperature operation of the bulk is preferable. The AC losses in the bulk and their influence on the trapped magnetic field are dependent on the temperature. Therefore, to estimate the efficiency and decay of the trapped magnetic field at various operation temperatures, it is necessary to know the temperature dependence of the AC losses. We investigated AC loss characteristics of a bulk at various temperatures. In the work, AC losses were measured for the amplitude of the AC external magnetic field up to 0.08 T and frequency 17.3 Hz/spl sim/62.2 Hz at the temperature 65 K/spl sim/100 K. It is also shown that the temperature dependences of the AC losses are well estimated by a theoretical model based on the Bean model.         Measurement of AC losses in MgB/sub 2/ wire and bulk conductors at different temperatures    Y. Yang, E.A. Young, M. Bianchetti, C. Beduz, E. Martinez and G. Giunchi Summary: AC loss measurements were carried out on MgB/sub 2/ wire and bulk conductors at temperatures between 25 K and 40 K in applied field up to 0.2 T transverse to conductor length. For bulk conductors in the shape of a flat plate (3 mm /spl times/ 0.5 mm), loss behavior of a thin strip Q/spl prop/H/sub 0//sup 4/ was observed. A reduction of width to 1 mm leads to a change in loss behavior similar to a round wire with Q/spl prop/H/sub 0//sup 3/. For the ex-situ MgB/sub 2/ wire of Ni sheath, losses were totally dominated by the hysteresis of ferromagnetic Ni. While the losses in the superconducting core is greatly reduced by the strong magnetic shielding by the Ni sheath, a small increase in the Ni loss was observed upon superconducting transition in the core. This is attributed to the compression of magnetic flux due to the diamagnetic superconducting core. Such an interpretation is supported by measurements of PbBi2223 tape in a cavity of an iron block.         Angular dependence of AC transport losses in stacks of Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10//Ag tapes    Guo Min Zhang, P.V.P.S.S. Sastry, J. Schwartz, Liang Zhen Lin, Li Ye Xiao and Yun Jia Yu Summary: In most power applications, the superconducting tapes carry AC transport currents and are exposed to applied AC or/and DC fields with different orientations. Because of the anisotropy of high temperature superconductors, AC losses depend on both the strength and the orientation of the magnetic field. To achieve high current carrying capacity, several tapes are often stacked. Thus an estimation of AC losses in stacked tapes is necessary for the design of superconducting devices. Here, AC transport losses in single, double- and triple-stacked Bi2223/Ag tapes were measured under different magnetic fields. The measurements were carried out at 77 K with the field angle between the tape surface and the direction of magnetic field varied from 0/spl deg/ to 90/spl deg/. The experimental results on the angular dependence of the AC losses are reported and analyzed.         I-V curves of BSCCO tape carrying DC current exposed to perpendicular and parallel AC fields    A. Friedman, Y. Wolfus, F. Kopansky, I. Soshnikov, V. Roitberg, S. Asulay, B. Kalisky and Y. Yeshurun Summary: A study of the DC I-V curves of BSCCO tapes exposed to AC perpendicular and parallel magnetic fields is presented. AC magnetic fields with amplitudes up to 700 G and frequencies from 1 to 430 Hz have been applied perpendicular and parallel to tapes carrying DC currents at T=77 K. Both field orientations result in a significant DC electric field increase, in comparison to applying DC magnetic fields of the same intensity. However, the observed I-V curves behavior is different for the perpendicular and parallel cases. In the perpendicular case, we distinguish between two frequency regimes: for frequencies above 40 Hz, the observed I-V curves obey the empirical power law dependence with current density, J/sub C/, and power index, n, that strongly depend on the field amplitude. For frequencies below 20 Hz, the observed I-V curves deviate from power law description. In the parallel field case, the I-V curve can be regarded as a superposition of an additional DC voltage over the no field I-V curve. This additional voltage increases with increasing current, peaks near the critical current and decreases thereafter. The results are discussed assuming a narrowing down of the DC current path under the application of a perpendicular AC field. Shaking of the pinned vortices under the application of a parallel AC field is assumed for explaining the results in this case.         Measurements of AC transport current losses in HTS tapes in an assembled conductor    O. Tsukamoto, Y. Yamato, S. Nakamura and J. Ogawa Summary: We developed an electric method to measure AC transport current losses in HTS tapes placed parallel on a flat plane to study on influence of magnetic field produced by the neighboring tapes on AC loss characteristics of a tape in an assembled conductor. To measure the AC losses in a tape in such arrangement electrically, proper cares for potential leads arrangements are necessary to avoid spurious loss components mixed in the measured data. In our method a combination of spiral and rectangular loops was used. Configuration of the loop arrangements was determined by a study of energy flows among the tapes. The validity of the method was verified by a calorimetric measurement conducted with the same arrangement of the tapes. The experimental data showed that the AC losses in the tape were significantly affected by the magnetic fields produced by the neighboring tapes.         Transport alternating current losses of BSCCO and YBCO tapes    Seog-Whan Kim, Jin-Hong Joo, Kyu Jeong Song, Chan Park, Rock-Kil Ko, Hong-Soo Ha, Ho-Sup Kim, Seung-Hyun Moon, Sang-Im Yoo and Kyungwoo Ryu Summary: After the discovery of HTS (High Temperature Superconductor), many types of HTS conductors have been developed. Several BSCCO tapes fabricated by PIT (Powder In Tube) method became commercially available, and the transport current loss characteristics of BSCCO tapes have been investigated by many research groups. The transport current loss characteristics of YBCO tapes, however, are not well studied. This is because measuring transport current requires tape samples over a certain length (15 cm for our own system). Many groups are currently focusing their effort on manufacturing long YBCO tape conductors, and new world records of length and current carrying capability are replacing the old ones in an increasingly fast rate. This paper deals with transport current losses of commercially available BSCCO tapes and YBCO tapes made at Korea Electrotechnology Research Institute (KERI) of Korea. YBCO tapes show relatively high transport current losses. This can be explained by the fact that the YBCO tape does not consist of filaments. Measurement results of the tapes are presented with analyses and discussions.         Analysis of coupling losses in multifilamentary untwisted BSCCO/Ag tapes through a.c. susceptibility measurements    D. Zola, F. Gomory, M. Polichetti, F. Strycek, J. Souc, P. Kovac and S. Pace Summary: Losses as a function of the a.c. magnetic field amplitude (B/sub 0/) have been evaluated at 77 K in untwisted BSCCO(2223)/Ag tapes, at different frequencies, by measuring the imaginary part of a.c. magnetic susceptibility. In particular, the measurements were performed on different portions of the same tape, obtained by cutting it in pieces with different length, starting from around 120/spl ap/mm down to 10/spl ap/mm. The experimental results show that the losses depend on the sample length, but this observed behavior can not be always ascribed to the coupling mechanism among filaments. In this work we discuss the observed experimental behavior for different typologies of tapes. The data are analyzed by comparing them with the results obtained by means of analytical models allowing us to characterize the tapes with respect to the coupling mechanisms.         YBCO thin film sputtering: an efficient way to promote microwave properties    F. Abbott, A.F. Degardin and A.J. Kreisler Summary: To obtain high quality YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) films by on-axis rf-magnetron sputtering, we have undertaken a twofold study: first, we have investigated the role of sputtering plasma parameters (dc self-bias voltage, rf power, oxygen flux and water vapor flux introduced into the plasma) in order to limit resputtering effect. In particular, we have shown the significance of mastering the dc self-bias voltage. Secondly, we have deposited YBCO films on [001] LaAlO/sub 3/ substrates taking into account the optimum flux conditions previously determined, and put into light the effect of the substrate temperature. Cross-optimization of the microstructural, electrical and microwave properties has been performed with respect to substrate temperature. A narrow optimal temperature window has been established to obtain films suitable for microwave applications.         A simple measurement technique for critical current density by using a permanent magnet    S. Ohshima, K. Takeishi, A. Saito, M. Mukaida, Y. Takano, T. Nakamura, T. Suzuki and M. Yokoo Summary: We developed a novel nondestructive and contactless method for measurements of critical current density (J/sub c/) in high-temperature superconductor (HTS) thin films by using a permanent magnet (Sm/sub 2/Co/sub 17/). This measurement technique is based on a repulsive force (F/sub r/) and attractive force (F/sub a/) between the magnet and HTS film caused by the shielding currents and pinning forces. The F/sub r/ and F/sub a/ were measured by using a high-resolution load sensor changing the distance (L) between the magnet and HTS film. An effective maximum repulsive force (F/sub m,eff/) could be determined from an extrapolated value of the F/sub r/ vs. L curve for L=0 mm. We investigated the relationship of the J/sub c/ to the F/sub m,eff/ in many HTS (YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// and ErBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//) samples. The standard J/sub c/ of HTS films was measured by using an inductive measurement system produced from THEVA GmbH. We found that the J/sub c/ is almost proportional to the two-thirds power of the F/sub m,eff/ normalized by the film thickness. This result indicates that the simple permanent magnet technique can be easily estimate the J/sub c/ of the HTS films. This system has good reproducibility for the J/sub c/ measurements and is useful to provide a rapid, routine characterization of the superconductivity in the HTS materials.         Characterization of local dielectric properties of superconductor YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// using evanescent microwave microscopy    R.A. Kleismit, G. Kozlowski, R. Biggers, I. Maartense, M.K. Kazimierczuk and D.B. Mast Summary: A near-field evanescent microwave microscope based on a coaxial transmission line resonator with a tungsten tip protruding through an end-wall aperture is used to measure local dielectric properties of thin film YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// in superconducting state below critical temperature T/sub c/=91 K at T=79.4 K and in normal state at room temperature (T=298 K). The dielectric property of the superconductor within the near field of the tip frustrates the electric field and measurably changes the transmission line's resonant frequency. The shift of the resonator's frequency is measured as a function of tip-sample separation and associated change in quality factor (Q) image scans of the thin film is obtained. A quantitative relationship between the real and imaginary parts of the local dielectric constant and the frequency shift using the method of images is established. The comparison between experimental data and theory based on this method is given and discussed for YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin film deposited on LaAlO/sub 3/ substrate.         Measurements of millimeter-wave surface resistance and temperature dependence of reactance of thin HTS films using quasi-optical dielectric resonator    N.T. Cherpak, A.A. Barannik, S.A. Bunyaev, Y.V. Prokopenko and S.A. Vitusevich Summary: The technique proposed by authors earlier for accurate measurement of large-area HTS thin film surface resistance (R/sub s/) is developed further. It is based on application of quasioptical dielectric resonators (QDR). Data on R/sub s/ of individual Y-123 films obtained at 77 K by using "round robin" procedure are presented. The main attention is paid to developing technique of temperature dependence measurement of thin film surface reactance variation (/spl Delta/X/sub s/). The dependence obtained by experiment is analyzed by means of fitting procedure that allows one to determine the validity of theoretical models for the temperature dependence of field penetration depth. Particularly, the 3D XY critical regime, Ginzburg-Landau behavior and two-fluid model are compared near T/sub c/. Our data show that the former approach best follows the observed dependence.         Distribution of inductive J/sub c/ in two-dimensional large-size YBCO films prepared by fluorine-free MOD on CeO/sub 2/-buffered sapphire    T. Manabe, M. Sohma, I. Yamaguchi, W. Kondo, K. Tsukada, K. Kamiya, S. Mizuta and T. Kumagai Summary: Distribution of J/sub c/ in the two-dimensional large-size YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) film was investigated by an inductive method for the application to fault current limiter elements. The YBCO films were prepared by metal-organic deposition (MOD) using a fluorine-free acetylacetonate-based complex solution on R-plane sapphire with an evaporated-CeO/sub 2/ buffer layer. The average J/sub c/ values of 1-3 MA/cm/sup 2/ at 77 K were obtained for 1 cm /spl times/ 12 cm-, 3 cm /spl times/ 12 cm-, and 10 cm /spl times/ 30 cm-rectangular YBCO films as well as on 2-inch-diameter films. In contrast with the TFA-MOD method via BaF/sub 2/ precursor, the fluctuation of J/sub c/ in the present films was fairly small; no significant size effects or shape effects were recognized on the fluctuation of J/sub c/. Instead, fluctuation of J/sub c/ depended on the average J/sub c/ values; higher-J/sub c/ films tended to exhibit more uniform J/sub c/ distribution.         Metal organic deposition of epitaxial Y123 films using a low-cost vacuum technique    I. Yamaguchi, T. Manabe, M. Sohma, K. Tsukada, W. Kondo, K. Kamiya, S. Mizuta and T. Kumagai Summary: Epitaxial YBa/sub 2/Cu/sub 3/O/sub 7/ (Y123) films were obtained by metal-organic deposition (MOD) using a simple, low-cost vacuum technique without gas flowing. The total pressure and oxygen partial pressure in the furnace were controlled to be 10 kPa and 10 Pa, respectively, by evacuation with a rotary pump followed by refilling with a mixture of O/sub 2/ and N/sub 2/ (O/sub 2/ content: 1000 ppm). XRD analyses exhibited that c-axis-oriented epitaxial Y123 films have successfully been obtained on CeO/sub 2/-buffered YSZ (100) (CbZ) and CeO/sub 2/-buffered sapphire (012) (CbS) substrates. In-plane alignments of these films were as high as that of the CeO/sub 2/ buffer layer. The film on the CbZ demonstrated a high critical current density J/sub c/ of /spl sim/2.1 MA/cm/sup 2/ at 77 K all over the film; the fluctuation of J/sub c/ being within /spl plusmn/10% of the average. Inductive T/sub c/ measurement showed a very sharp peak with T/sub c/=90.5 K. Inductive-J/sub c/ and T/sub c/ of the Y123 film on CbS were 1.1 MA/cm/sup 2/ and 89.6 K, respectively, whereas the T/sub c/ of the Y123 film on LaAlO/sub 3/ was lower than 77 K owing to the occurrence of the a-axis grains.         Grain boundary properties of Tl-2212 and Tl-1223 thin films    C. Dark, S. Speller, H. Wu, A. Sundaresan, Y. Tanaka, G. Burnell and C.R.M. Grovenor Summary: After more than 15 years active research, it is now clear that in YBCO grain boundaries act as severe weak links, and in order to produce YBCO thin films carrying high critical currents it is necessary to grow epitaxial films on appropriate substrates. We asked the question whether grain boundaries in thallium based superconductors cause the same degradation of properties, by adding to the very limited published data on the properties of grain boundaries in Tl-HTS systems. We have measured the properties of a statistically significant number of both 'artificial' grain boundaries on LaAlO/sub 3/, LSAT and SrTiO/sub 3/ bicrystal substrates and 'natural' grain boundaries in films grown on MgO substrates. The J/sub c/ values of the bicrystal films are surprisingly high when compared to values for YBCO bicrystals, and for Tl-2212 were the same for 30/spl deg/ and 24/spl deg/ grain boundaries. The 'natural' grain boundaries showed two distinct type of electrical behavior, both with significantly higher J/sub c/ values when compared to 'artificial' boundaries of similar misorientation. The J/sub c/ values of the natural grain boundaries from the bi-epitaxial films show no decrease in J/sub c/ with misorientation angle. The normalized values of J/sub c/ for these Tl-2212 grain boundaries do not fall on the generic J/sub c///spl theta/ trend line for YBCO boundaries.         Fabrication of a/c axes oriented grain boundaries in YBCO films by selective growth    Y. Shingai, M. Mukaida, A. Ichinose, S. Horii, Y. Yoshida, K. Matsumoto, F. Hirose, K. Koike, A. Saito and S. Ohshima Summary: The a/c axes grain boundaries of YBCO films are very interesting from the viewpoints of Josephson junction technology and the magnetic flux pinning. In this paper, we intend to flow superconducting current along the grain boundary and to prevent the magnetic flux motion from passing across the grain boundary. The a/c axes grain boundaries were fabricated on SrLaGaO/sub 4/ (100) substrates by pulsed laser deposition on Gd/sub 2/CuO/sub 4/ (GCO) buffer layers. The preferred orientation and in-plane orientation of the films were characterized by X-ray /spl theta//2/spl theta/ diffraction and /spl phi/-scan spectroscopy. 4-micrometer pitch GCO patterns were fabricated by a lithography technology. Subsequently, the YBCO films were deposited on the pattern. A TEM image showed that a-axis grains grew over c-axis grains.         Enhanced T/sub c/ and H/sub c2/ near the metal/insulator transition    R.J. Soulen Jr. and M.S. Osofsky Summary: We have studied the behavior of H/sub c2/ for the Nb/sub 1-x/Ti/sub x/ system as a function of disorder (i.e, x). To account for the observed behavior we substituted expressions for /spl gamma/ and T/sub c/, previously derived for disordered systems, into the GLAG expression for H/sub c2/. This extension accounts very well for the data for the NbTi system and, accordingly, we are studying its application to data for several other superconducting systems.         Fabrication and optical properties of ultrathin ferromagnet/superconductor metallic bilayers    G.P. Pepe, L. Parlato, R. Latempa, P. D'Acunto, N. Marrocco, C. De Lisio, C. Altucci, G. Peluso, A. Barone, T. Taneda and R. Sobolewski Summary: Ferromagnet/superconductor (F/S) bilayers composed of ultrathin metallic films demonstrate new proximity effects and show a peculiar behavior of the superconductor-order parameter. In terms of applications, F films provide additional "anchoring" of the S film vortex lattice, resulting in increased critical current. By changing composition and the thickness ratio of the F/S bilayer, one can modify the quasiparticle dynamics through an effective enhancement or suppression of the quasiparticle lifetime under nonequilibrium conditions. The latter effect should lead to "custom-designed" superconducting detectors, with the sensitivity and photoresponse speed tailored to a given application. We present fabrication details of nanometer-thickness NiCu/Nb bilayers of different F/S ratios. The NiCu/Nb structures have been implemented to fabricate Josephson junctions and tested using femtosecond optical spectroscopy. The time-resolved photoresponse experiments allowed us to measure the quasiparticle relaxation dynamics in our bilayers. In addition, the photoresponse temperature dependence studies revealed the spatial evolution of the superconductor-order parameter across the bilayer. Comparison between the bilayer data and the single-material data is also presented.         Electrostatic modulation of conductivity in Nd/sub 1.2/Ba/sub 1.8/Cu/sub 3/O/sub y/ thin films    A. Cassinese, G.M. De Luca, A. Gambardella, A. Prigiobbo, M. Salluzzo and R. Vaglio Summary: HTS properties can be modified by changing the carrier number n/sub h/ per CuO/sub 2/ plane. The astonishing generality of the HTS phase diagram (temperature vs. number of holes), poses many questions concerning the fundamental aspects of the physics of such materials and, at the same time, offers an interesting instrument for the control of their transport properties and for the realization of new devices. Using field effect devices, we have modified the number of carriers in the surface layers of Nd/sub 1.2/Ba/sub 1.8/Cu/sub 3/O/sub 7/ epitaxial films, grown on SrTiO/sub 3/ substrate, having thickness ranging between 4 and 10 unit cells (u.c.). The films investigate below 9 u.c. present a Variable Range Hopping Mott-insulator temperature dependence of the resistivity analogous to other insulators belonging to the families of strongly correlated systems. The gate can be applied both on the top layer through an Al/sub 2/O/sub 3/ layer (gate up configuration) or by applying the electrical field on the back side of the SrTiO/sub 3/ substrate (gate down configuration). The devices are fabricated by a completely in situ technique, avoiding superface and inter-layers impurities. Here we report on the I-V characteristics and on resistive measurements obtained mainly with gate down configuration on insulating samples. Particular interest was devoted to the understanding of the maximum modulation achievable in this compound as well. Considerations on superconducting samples (10 u.c.) are also reported as well as on the possibility on the possibilities of superconductor-insulator transitions.         The distribution of transport current in YBCO coated conductor with zipper striations    L.B. Wang, P. Selby, C. Khanal, G. Levin, T.J. Haugan, P.N. Barnes and C. Kwon Summary: An YBCO coated conductor with a zipper pattern striation is investigated by scanning laser microscopy (SLM). The distribution of transport current deduced from the VTSLM images shows that striations act as artificial barriers forcing the current to flow around them. Current sharing and redistribution are observed at the zipper area. We find the major dissipation mechanism in the sample in the superconducting state to be the current crowding at bottleneck areas. The bottleneck seems to be caused by the disabled filaments at and around the zipper area. Some filaments show the dissipation away from the zipper area. In general, we find that the lower J/sub c//sup */ areas have lower T/sub c//sup */ and high /spl delta/V/sub m/, which we consider as a sign of the current crowding. For the first time, we have demonstrated that there is a high temperature signature of the lower J/sub c//sup */ (high dissipation) area and VTSLM can detect the signature.         Imaging local dissipation and magnetic field in YBCO films with artificial defects    D.V. Abraimov, D.M. Feldmann, A.A. Polyanskii, A. Gurevich, S. Liao, G. Daniels, D.C. Larbalestier, A.P. Zhuravel and A.V. Ustinov Summary: We used Low Temperature Laser Scanning Microscopy (LTLSM) to investigate dc current flow in high-J/sub c/ YBCO thin films with artificially prepared defects and correlated the LTLSM response to Magneto Optical Images (MOI). Artificial defects model current blockages such as cracks, high angle grain boundaries or voids. Because the LTLSM voltage response is associated with the local electric field, while MOI shows the local perpendicular magnetic field, the combination of techniques gives complementary local information about the effect of current-limiting defects in superconductors.         Novel approach to microcrack-free thick YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films on r-cut sapphire buffered with CeO/sub 2/    Jia Cai Nie, H. Yamasaki, Y. Nakagawa, K. Develos-Bagarinao, M. Murugesan, H. Obara and Y. Mawatari Summary: Stoichiometric YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) films were fabricated by pulsed laser deposition on deliberately miscut Al/sub 2/O/sub 3/ (11_02) buffered with CeO/sub 2/. Atomic force microscopy observations demonstrated that 600 nm-thick YBCO films were microcrack-free. Characterization of the films revealed a porous morphology, consisting of interconnected islands and deep holes (pores). This feature is considered as one of the sources contributing to the strain-relieving mechanism responsible for the increase in film thickness without microcracking. We observed T/sub c/=90/spl plusmn/0.5 K, J/sub c/ (77.3 K, 0 T)=1.5-2.0/spl times/10/sup 6/ A/cm/sup 2/, and J/sub c/t (77.3 K, 0 T)/spl sim/120 A/cm. In addition, this new approach, using the deliberately miscut sapphire as a substrate for YBCO, is also applicable to other kinds of deposition techniques.         Control of porosity and composition in large-area YBCO films to achieve micrometer thickness and high J/sub c/ on sapphire substrates    K.D. Bagarinao, H. Yamasaki, J.C. Nie, M. Murugesan, H. Obara and Y. Nakagawa Summary: Relatively thick YBCO thin films (thickness d>0.5 /spl mu/m) ideal for fault current limiter as well as microwave applications have been successfully prepared by large-area pulsed laser deposition (PLD) on CeO/sub 2/-buffered sapphire substrates. The attainment of an unusually high film thickness (up to 2.0 /spl mu/m) without microcracking is attributed in part to the presence of pores correlated with yttrium-rich composition in the films. The effect of using YBCO targets with varied Y:Ba:Cu ratios on film porosity and surface morphology was investigated in detail. Using the optimum target composition, uniform critical current densities (J/sub c/) ranging from /spl sim/4.5 MA/cm/sup 2/ at d/spl sim/0.23 /spl mu/m to /spl sim/1.75 MA/cm/sup 2/ at d/spl sim/0.6 /spl mu/m have been achieved. Characterization of a film with d/spl sim/0.5 /spl mu/m showed low microwave surface resistance values [R/sub s/(77.3 K)/spl ap/2.09 m/spl Omega/ and R/sub s/(20 K)/spl ap/227 /spl mu//spl Omega/ at 22 GHz] comparable to the best YBCO films reported by other studies.         MBE growth of large area RE-123 superconductor thin films for microwave applications    J. Kurian and M. Naito Summary: Large area high quality epitaxial thin films are required for many commercial microwave applications of high temperature superconductors. Although there exists different techniques for the growth of high temperature superconductor films, molecular beam epitaxy (MBE) growth has the advantage of achieving better homogeneity and scalability. We have succeeded in growing high quality RE-123 (RE=La, Nd, Eu, Gd, Dy) superconductor films by MBE. The growth of high quality films by MBE requires strict compositional control and optimization of growth temperature and oxidation conditions. Strict compositional control is the most vital in achieving best characteristics of the films and we have found that composition close to 123 yields the best results. By optimizing the different growth parameters, we have grown high quality RE-123 films with high T/sub C/(0) & J/sub C/, low resistivity and low microwave surface resistance. Among the different RE-123 films we have investigated so far, Nd-123 superconductor films shows the better characteristics. Nd-123 films grown on (100) MgO under optimized conditions gave a T/sub C/(0) of 94 K with a J/sub C/ above 3.5 MA/cm/sup 2/ at 77 K. These Nd-123 films show excellent metallicity (/spl rho//sub 300 K///spl rho//sub 100 K//spl sim/3) with room temperature resistivity of /spl sim/140 /spl mu//spl Omega/.cm. The films had excellent in-plane orientation and high crystallinity. The MBE grown Nd-123 films show low microwave surface resistance (/spl sim/870 /spl mu//spl Omega/ at 77 K @ 22 GHz) making them better candidate for microwave applications.         Growth and properties of YBCO-coated conductors fabricated by inclined-substrate deposition    B. Ma, K.K. Uprety, R.E. Koritala, B.L. Fisher, S.E. Dorris, D.J. Miller, V.A. Maroni and U. Balachandran Summary: YBCO-coated conductors with high current-carrying capability are desirable for electric power transmission applications. Inclined-substrate deposition (ISD) is capable of producing high-quality biaxially textured template films, which are important for fabrication of YBCO-coated conductors. We have grown biaxially textured ISD-MgO template films on flexible metallic substrates at deposition rates of 2-10 nm/sec. Columnar grains with a roof-tile-shaped surface structure were observed on the ISD-MgO films. X-ray pole figure analysis revealed that the ISD-MgO film is biaxially textured and its c-axis is titled at an angle from the substrate normal. Strontium ruthenium oxide (SRO) buffer films were epitaxially grown on ISD-MgO by pulsed laser deposition prior to the deposition of YBCO. Low /spl phi/-scan full-width at half maximum (FWHM) values of 6/spl deg/ and 7/spl deg/ were observed for YBCO and SRO, respectively. T/sub c/ of 91 K with a sharp transition and transport J/sub c/ over 1.4 MA/cm/sup 2/ at 77 K in self-field were measured on YBCO coated conductors grown with ISD MgO architectures using a SRO buffer.         Solution deposition approach to high J/sub c/ coated conductor fabrication    S. Sathyamurthy, M. Paranthaman, M.S. Bhuiyan, E.A. Payzant, D.F. Lee, A. Goyal, X. Li, T. Kodenkandath, U. Schoop and M. Rupich Summary: Great strides have been made in YBCO coated conductor fabrication using the RABiTS approach in the past few years and critical current densities (J/sub c/) of over 3 MA/cm/sup 2/ on 10 meter long tapes have been achieved. Solution deposition for buffer layer processing has the potential to reduce the process complexity and make the conductor fabrication more cost-effective. In our work, we have demonstrated that several of the standard buffer layers can be replaced by sol-gel processed lanthanum zirconium oxide (LZO) layer. A J/sub c/ of about 2 MA/cm/sup 2/ has been demonstrated on LZO films for pulsed laser deposited YBCO and J/sub c/ up to 1.5 MA/cm/sup 2/ have been demonstrated for MOD-YBCO using a sputtered CeO/sub 2/ cap layer on the sol-gel LZO films. Solution processed buffer layers have been found to have rapid growth kinetics which could potentially mean high rate processing of these buffer layers. Using simulated ex-situ YBCO annealing studies, it has been determined that the performance of 80-120 nm thick LZO films is comparable to the standard 3-layer vapor deposited CeO/sub 2//YSZ/Y/sub 2/O/sub 3/ buffer stack. Using a 120 nm thick LZO layers on NiW substrates, in collaboration with American Superconductor Corp., all-solution coated conductors with the stacking sequence MOD-YBCO/Solution CeO/sub 2//Solution LZO/NiW, critical currents of up to 140 A/cm has been measured. Such high critical currents on an all-solution conductor offers promise for cost-effective scale-up of coated conductor processing.         Iridium: an oxygen diffusion barrier and a conductive seed Layer for RABiTS-based coated conductors    T. Aytug, M. Paranthaman, H.Y. Zhai, K.J. Leonard, A.A. Gapud, J.R. Thompson, P.M. Martin, A. Goyal and D.K. Christen Summary: For power applications of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) coated conductors, it is necessary to electrically stabilize the conductor. An economic way to achieve this, which also benefits the engineering J/sub E/, is to grow conductive buffer layers directly on textured Cu or Ni metal surfaces. However, due to poor oxidation resistance and high reactivity/diffusivity of Cu or Ni, an insulating oxide layer usually forms at the metal/substrate interface, degrading the electrical connectivity of the entire architecture. To overcome this problem, we have developed a new conductive, nonmagnetic buffer layer architecture of La/sub 0.7/Sr/sub 0.3/MnO/sub 3//Ir on textured Ni-based tapes. This structure serves as a barrier to both inward diffusion of oxygen and outward diffusion of metal cations. Using PLD to grow YBCO, we demonstrate ideal electrical coupling to the metal substrate. Critical current (I/sub c/) values for 1 /spl mu/m thick YBCO coatings exceed 100 A/cm-width at 77 K on a Ni-W RABiTS template.         Investigation of TiN seed Layers for RABiTS architectures with a single-Crystal-like out-of-plane texture    C. Cantoni, A. Goyal, U. Schoop, X. Li, M.W. Rupich, C. Thieme, A.A. Gapud, T. Kodenkandath, T. Aytug, M. Paranthaman, K. Kim, J.D. Budai and D.K. Christen Summary: Sharpening of the substrate texture is key to obtain critical current densities approaching single crystal values in coated conductors. In particular, great improvements in J/sub c/ are obtained by narrowing the substrate texture down to values of 3-4/spl deg/ for both phi-scan and omega-scan FWHM. The best Ni-alloy substrates used today for RABiTS show FWHM's of 6-5/spl deg/. Although the majority of buffer layers deposited on these tapes by various techniques approximately duplicate the substrate's grain alignment, some materials have been found to develop much sharper out-of-plane texture. Here we report on growth and structural characterization of TiN seed layers on various textured metal tapes. TiN seed layers deposited by PLD have consistently shown tilting of the c-axis toward the direction of the sample's surface normal. We address the extent of such tilt and discuss feasibility of alternative RABiTS architectures that use a TiN seed layer to provide very sharp out-of-plane texture and serve as an effective metal-ion diffusion barrier.         Hetero-epitaxial growth of YBCO thin films on the a-cut plane sapphire substrates    S. Ohshima, M. Shirakawa, T. Nishimura, A. Saito and M. Mukaida Summary: We examined the hetero-epitaxial growth of YBCO thin films on the a-cut plane sapphire substrates for the passive microwave applications, because the a-cut plane sapphire substrates have smaller in-plane anisotropy of the dielectric constant compared with that of r-cut plane sapphire substrates. The CeO/sub 2/ buffer layers and YBCO thin films were prepared by an inductive-coupled plasma sputtering method. We found that perfect in-plane alignment of the CeO/sub 2/ buffer layer could be obtained on the a-cut plane sapphire substrates. Also we could obtain the hetero-epitaxial YBCO thin films on CeO/sub 2//a-cut plane sapphire substrates. Tc of the YBCO thin films was approximately 89 K, and the surface resistance (Rs) of the YBCO thin films was approximately 1 m/spl Omega/ at 50 K and at 22 GHz, equivalently to values for YBCO thin films fabricated on the r-cut plane sapphire substrates.         MOCVD of buffer Layers and Superconducting Layers on moving textured nickel tapes    O. Stadel, S.V. Samoilenkov, J. Schmidt, H. Keune, G. Wahl, O.Yu. Gorbenko, O.V. Melnikov and A.R. Kaul Summary: Buffer layers and YBCO have been continuously deposited on textured Ni5%W tapes in a reel-to-reel MOCVD system. The buffer layers were perovskites with the composition (AA')(BB')O/sup 3/ (A, A'=La, Sr, Ca, Ba and B, B'=Cr, Mn, Fe, Co, Ni). The buffer layers were well textured with in-plane FWHM down to 5.5/spl deg/ and out-of-plane FWHM down to 2.2/spl deg/.         X-ray diffraction anomalies and random intercalation in H-loaded Y-Ba-Cu-O films    D. Ariosa, V.N. Tsaneva and Z.H. Barber Summary: A model has been developed to account for the structural peculiarities observed by X-ray diffraction of hydrogen-loaded Y123 films deposited in an O/sub 2//Ar+H/sub 2/O atmosphere. The model considers the random inter-growth of two very similar structures with slightly different c-axis or, equivalently, the random intercalation of a small spacer in the Y123 matrix causing displacement disorder along the c-axis direction. It quantitatively reproduces both the nonmonotonous deviations of Bragg-peaks and their progressive weakening and broadening for higher diffraction orders. The model offers the possibility to evaluate both the fraction of secondary phase and its c-axis lattice parameter. In the example given, we have been able to identify 28% of intercalated hydrogen bronze H/sub 0.66/[Y123] with 4% elongated c-axis. A simplified procedure for the diagnosis and characterization of random intercalates is extracted from the model. Similar structures observed in other perovskite-based layered oxides are discussed within this framework.         La,Sr)TiO/sub 3/ as a conductive buffer for high-temperature superconducting coated conductors    Kyunghoon Kim, D.P. Norton, C. Cantoni, T. Aytug, A.A. Gapud, M.P. Paranthaman, A. Goyal and D.K. Christen Summary: The perovskite (La,Sr)TiO/sub 3/ was investigated as a possible conducting oxide buffer layer for high-temperature superconducting coated conductors. In particular, the growth of LSTO films on SrTiO/sub 3/ single crystal, Ni-W, and Cu tapes was performed using pulsed laser deposition. LSTO films were grown in vacuum at a temperature of 750/spl deg/C. From the /spl omega/-scan, the FWHM values of LSTO (004) on Ni-W and Cu tape were 7.48/spl deg/ and 6.21/spl deg/, which showed improvement in the out-of-plane texture for the film as compared to the substrate metal tapes. The /spl phi/-scans through the LSTO (112) on both metal tapes indicated in-plane-aligned LSTO grains. YBa/sub 2/Cu/sub 3/O/sub 7/ films were deposited on all three structures by pulsed laser ablation; samples on LSTO/SrTiO/sub 3/ single crystals had a superconducting transition of 91/spl deg/K and a Jc value of 3.0 MA/cm/sup 2/. This shows that LSTO is a good template for the YBCO film in terms of epitaxial and chemically stable growth.         One-step sol-gel growth of textured buffer layers on cold-rolled Ni substrates for coated conductor fabrication    Sansheng Wang, Sheng Chen, Honglan Fu, Kai Shi, Li Liu, Qing Liu and Zhenghe Han Summary: We report a newly developed simple one-step annealing process, namely the simultaneous texture (STEX) technique, for cheap and convenient fabrication of buffer layers on rolled Ni tapes. Textured CeO/sub 2/ buffer layers have been prepared using this new process from solutions of cerium nitrite in acetyl acetone. Ba/sub x/Sr/sub 1-x/TiO/sub 3/ buffer layers have also been prepared from solutions of strontium acetate, barium acetate, titanium (IV) butoxide in 2-metoxyethanol and acetic acid. For both cases, an analysis of X-ray diffraction omega and phi scans indicates that cube-on-cube texture formation takes place during STEX processing. The possible mechanisms related to the STEX method are analyzed and discussed. The preparation of multi-layer configurations, and of subsequent YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) film growth on STEX-prepared buffer layers is also reported.         Growth of lanthanum manganate buffer layers for coated conductors via a metal-organic decomposition process    K. Venkataraman, E.E. Hellstrom and M. Paranthaman Summary: Perovskite LaMnO/sub 3/ (LMO) in thin film embodiment has been identified as a potential candidate for use as a buffer layer in coated conductors. This paper delineates the process-properties relationships investigated for the metal-organic decomposition (MOD) growth of LMO thin films on bare cube-textured Ni-W tape sections. Epitaxial films of pseudocubic perovskite LMO were obtained for samples fired at 1100/spl deg/C in a humidified forming gas (Ar/4% H/sub 2/, P/sub H2O//spl sim/2 Torr) ambient atmosphere. The surface morphology, epitaxy, and composition of the films are reported.         Studies on Ba/sub 2/YNbO/sub 6/ buffer layers for subsequent YBa/sub 2/Cu/sub 3/O/sub 7-x/ film growth    S. Sathiraju, P.N. Barnes, C. Varanasi and R. Wheeler Summary: In this paper, we are reporting a dielectric oxide buffer Ba/sub 2/YNbO/sub 6/ (BYNO) and its performance on various substrates for a potential buffer layer for the growth of YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) coated conductors. Ba/sub 2/YNbO/sub 6/ is a moderate dielectric. Using pulsed laser deposition, epitaxial BYNO films were grown at 850/spl deg/C with an oxygen pressure of 200 mTorr on single crystal MgO (100) substrate and ion beam assisted sputter deposited MgO buffered hastelloy metal substrates. The surface morphology of the BYNO films reveals out growths even though the average surface roughness is only 2-8 nm. The texture of BYNO films is /spl sim/8/spl deg/ and thickness of these layers /spl sim/100 nm on metal substrates. Highly c-axis oriented YBCO films were deposited on BYNO buffered substrates. Critical transition temperatures (T/sub c0/) determined from electrical transport measurements vary between 88-89 K and corresponding critical current densities (J/sub c/) ranging from 0.5-1 MA/cm/sup 2/ at 77 K.         Critical current density enhancement in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films by twin domains of LaAlO/sub 3/ substrates    Zuxin Ye, Qiang Li, W.D. Si and P.D. Johnson Summary: Magnetic flux penetration into a 0.2 /spl mu/m-thick YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thin film grown on a crystalline LaAlO/sub 3/ (LAO) substrate was studied using magneto-optical imaging techniques. Enhanced critical current density J/sub c/ was observed at the location corresponding to twin domains on the underlying substrate. We attribute this J/sub c/ enhancement to increased pinning defects in the YBCO layer induced by the naturally formed nano-scaled surface roughness on the LAO substrate. Our results suggest that the substrate surface roughness might be helpful in J/sub c/ improvement of YBCO thin films grown on metal substrates by pulsed laser deposition.         Preparation and texture evolution of epitaxially grown CeO/sub 2/ buffer layers using inorganic salts as starting materials for YBCO coated conductors    Sheng Chen, Sansheng Wang, Kai Shi, Qing Liu and Zhenghe Han Summary: We report the texture evolution of CeO/sub 2/ thin films epitaxially grown on yttria-stabilized-zirconia (YSZ) and Ni substrates using inorganic cerium salts as starting materials. The effect of organic solvents on the precursor solution properties is discussed. Inorganic cerium nitrate dissolved in different solvents and chelating agents were spin-coated and annealed. CeO/sub 2/ films grown on YSZ substrates showed an enhancement of the out-of-plane texture when thermal annealing process was carried out in an oxidizing atmosphere. Texture analysis revealed that a bi-axially aligned cube-textured CeO/sub 2/ buffer layer could be grown over a wide processing temperature range. High temperature annealing is most beneficial for improvement of the in-plane texture. The results suggest an effective new low-cost way to fabricate CeO/sub 2/ thin film templates for YBCO coated conductors.         Use of SrTiO/sub 3/ as a single buffer layer for RABiTS YBCO coated conductor    Jun-Ki Chung, Rock-Kil Ko, Dong-Qi Shi, Hong-Soo Ha, Hosup Kim, Kyu-Jeong Song, Chan Park, Seung-Hyun Moon and Sang-Im Yoo Summary: SrTiO/sub 3/ (STO) films were epitaxially deposited by PLD on textured Ni-3wt%W (Ni-3W) substrates. The STO film was deposited in two steps-reducing atmosphere first, and then oxidizing atmosphere-to prevent the oxidation of the metal surface from hindering the epitaxial relationship between the film and the substrate. The deposited STO films exhibited sharp biaxial texture and dense surface. YBCO films were epitaxially deposited on STO/Ni-3W and showed J/sub c/(77K, self field)=1.2MA/cm/sup 2/ and T/sub c/(onset)=88 K. Auger electron spectrometry depth profile analyses show that the STO film can block the diffusion of the metal from the substrate. This work has shown that STO films epitaxially deposited on textured Ni-3W substrate can be used as a single buffer layer of the high current carrying YBCO coated conductor.         Preparation of MZrO/sub 3/ (M=Ba,Sr) buffer layers on surface oxidized Ni/NiO templates by PLD and MOD    R. Huhne, B. Holzapfel, A. Kursumovic, J.E. Evetts, A. Cavallaro, F. Sandiumenge, A. Pomar, T. Puig and X. Obradors Summary: The preparation of cube textured NiO buffer layers on biaxially textured Ni tapes using surface oxidation epitaxy (SOE) offers a cheap and scalable route for the production of long-length YBCO coated conductors. A second buffer layer is necessary to ensure epitaxial growth of the YBCO as well as to prevent Ni contamination of the superconducting layer. Zirconate buffer layers offer a close lattice misfit to NiO as well as a high stability during the YBCO deposition. BaZrO/sub 3/ and SrZrO/sub 3/ buffers were successfully deposited on NiO using pulsed laser deposition. Additionally, BaZrO/sub 3/ films were prepared on NiO using metal-organic decomposition. All buffers show a high quality epitaxial growth with an in-plane orientation similar to the underlying NiO. The subsequent deposition of YBCO on top of these buffers resulted in epitaxial layers with a T/sub c/ above 85 K and j/sub c/ up to 1 MA/cm/sup 2/ on NiO if a thin intermediate SrTiO/sub 3/ layer is used. Microstructural investigations showed that the roughness and the surface topography of the buffer layers is mainly determined by the quality of the NiO layer.         YBCO thin films on TiO/sub 2/ buffer layer deposited by RF magnetron sputtering    Y. Nakamura, Y. Isozaki, M. Miura, T. Kuroiwa, Y. Yoshida, K. Matsumoto, A. Ichinose, S. Horii, M. Mukaida and S. Ohshima Summary: Rutile structure TiO/sub 2/ buffer layers and YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) thin films have been deposited on (100) MgO substrates by RF magnetron sputtering. It was found that, high quality c-axis oriented YBCO thin films could be obtained on MgO with very thin [110] oriented rutile structure TiO/sub 2/ buffer layers. The crystal structure of TiO/sub 2/ thin films changed from (100) oriented anatase structure TiO/sub 2/ to [110] oriented rutile structure TiO/sub 2/ with increasing substrate temperature. The [110] oriented rutile structure TiO/sub 2/ thin films deposited with the optimal deposition condition had smooth surfaces. YBCO thin films on [110] oriented rutile structure TiO/sub 2/ buffer layers had better crystallinity and surface flatness than YBCO thin films deposited on bare MgO substrates.         Surface roughness of magnesium oxide buffer layers grown by inclined substrate deposition    R.E. Koritala, B. Ma, D.J. Miller, K.K. Uprety, B.L. Fisher and U. Balachandran Summary: Biaxially textured MgO films were grown by inclined substrate deposition (ISD) as template layers for YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO)-coated conductors. The surface roughness of films deposited at different angles and with varying thickness was examined by atomic force microscopy. Results were correlated with the texture, measured by X-ray diffraction, to determine the optimal thickness and deposition angle.         Deposition of Gd/sub 2/O/sub 3/ buffer layers on Ni-based substrates by aerosol spray pyrolysis    Feng Lu and E.E. Hellstrom Summary: Aerosol spray pyrolysis (ASP) was used to deposit Gd/sub 2/O/sub 3/ on pure Ni and Ni(5at%W). The H/sub 2/:H/sub 2/O ratio in the gas stream, consisting of forming gas + the aqueous nitrate mist, was adjusted to 0.75, which prevented the Ni(W) substrate from oxidizing. A dense, /spl sim/600 nm thick layer of Gd/sub 2/O/sub 3/ could be deposited on a textured Ni(5at%W) substrate at 900/spl deg/C in 20 min. The Gd/sub 2/O/sub 3/ was not textured and the surface was rough.         Deposition and characterization of Y/sub 1-x/Ca/sub x/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// epitaxial thin films    C. Cancellieri, A. Augieri, V. Boffa, G. Celentano, L. Ciontea, F. Fabbri, V. Galluzzi, U. Gambardella, G. Grassano, T. Petrisor and R. Tebano Summary: We report on the superconducting properties of epitaxial thin films Y/sub 1-x/Ca/sub x/Ba/sub 2/Cu/sub 3/O/sub 7-y/ with 0/spl les/x/spl les/0.2, grown on SrTiO/sub 3/ [001] by Pulsed Laser Deposition (PLD) technique. The partial substitution of Ca/sup 2+/ at the Y/sup 3+/site in YBCO leads to a monotonic decrease of the zero resistance critical temperature, T/sub c/. The oxygen stoichiometry is varied by means of post-deposition thermal treatment varying the oxygen partial pressure. The dependence of T/sub c/ on annealing oxygen pressure can be attributed to an overdoping effect and/or to a cation disorder.         Critical current density characteristics in YBCO films on MgO substrates by pulsed laser deposition    O. Miura, Y. Ono, D. Ito and K. Matsumoto Summary: It is known that both low angle grain boundaries and linear dislocation defects act as strong flux pinning centers in YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) thin films achieving high critical current density J/sub c/. In this experiment, in order to effectively introduce such functional pinning centers, YBCO thin films were fabricated on (100) MgO substrates with a large lattice mismatch of 8.8% by PLD method with varying the substrate temperatures. By AFM studies of the surface morphology after a short-time etching by a 1% Br/ethanol solution, both submicron-sized large etch pits and very small dotted etch pits are clearly observed. It is speculated that small etch pits correspond to edge or screw dislocations and large pits are thick plate-like crystal defects like high angle grains or a-axis oriented domains. It was observed that J/sub c/ was independent of B up to characteristic field B/sup */. According to the single vortex pinning, the effective pinning densities N/sub eff/ and the average of the elementary pinning force f/sub pav/ were estimated from B/sup */. N/sub eff/ approximately coincide with the etch pit densities, and f/sub pav/ is the same order as f/sub p/ estimated using normal conductive pin model. Thus, it is almost certain that both linear defects and thick plates act as effective pins up to B/sup */. On the other hand, in higher fields, the bulk pinning force density varies as B/sup 0.5/, consistent with flux pinning model where surface area of the thick plates is dominant pinning centers.         Microstructures and enhancement of critical current density in YBa/sub 2/Cu/sub 3/O/sub 7/ thin films grown by pulsed laser deposition on various single crystal substrates modified by Ag nano-dots    A.H. Li, M. Ionescu, H.K. Liu, T. Silver, X.L. Wang and S.X. Dou Summary: YBa/sub 2/Cu/sub 3/O/sub 7/ (Y123) thin films were grown by pulsed laser deposition (PLD) on YSZ (100), SrTiO3 (100), and LaAlO3 (100) single crystal substrates. Prior to the film deposition, a discontinuous layer of Ag nano-dots was deposited on the substrates. The Y123 films grown on such surfaces modified with Ag nano-dots were characterized by Atomic Force Microscopy (AFM), X-ray diffraction (XRD), scanning electron microscopy (SEM), AC susceptibility and DC magnetization. The effects of the density of Ag nano-dots, which was controlled by the numbers of PLD shots, on the microstructures and resultant critical current density J/sub c/ have been studied systematically. Results showed that at fixed physical deposition conditions J/sub c/ increased monotonically with number of Ag shots, n, for films grown on both STO and LAO substrates. At 77 K, the J/sub c/ increased from 10/sup 6/ to 3.2/spl times/10/sup 6/ A/cm/sup 2/ for LAO and from 8/spl times/10/sup 5/ to 3.5/spl times/106 A/cm/sup 2/ for STO as n increased from 0 to 150. At 5 K, the enhancement of J/sub c/ was approximately four times at both low and high fields. However, for films grown on YSZ substrate, J/sub c/ increased from 2/spl times/10/sup 5/ to 2/spl times/10/sup 6/ A/cm/sup 2/ as Ag shots increased from 0 to 30, and decreased to 9/spl times/10/sup 5/ for n/spl ges/60. Detailed microstructure investigations indicated that the crystallinity and ab alignment gradually improved as the number of Ag-nano-dots increased.         YBCO films prepared by PLD using nanocrystalline targets doped with BaZrO/sub 3/ or Y211    M. Peurla, H. Huhtinen, P. Paturi, Y.P. Stepanov, J. Raittila and R. Laiho Summary: YBCO thin films were prepared by pulsed laser deposition from a pure nanocrystalline YBCO target and similar targets doped with BaZrO/sub 3/ or Y/sub 2/BaCuO/sub 5/ (Y211 phase) in order to investigate the effect of these impurities on magnetic flux pinning. The doped targets were pressed from nanopowders prepared by a sol-gel method from starting solutions whose nominal molar ratios corresponded to compositions YBCO+2.2 and 6.5 wt% BaZrO/sub 3/ and YBCO+3.0 wt% Y211 phase. The biggest changes in the superconducting properties relative to the films prepared from the pure target were observed in the films ablated from the BaZrO/sub 3/-doped targets. Although the doping reduces the critical temperature, the critical current density calculated from the hysteresis loops is significantly increased in external magnetic fields above 0.15 T. Addition of Y211 to the target is found not to be as effective for improving the flux pinning of the films in high magnetic fields as addition of the BaZrO/sub 3/. J/sub c/'s in zero field and 77 K were 1.2 MA/cm/sup 2/ in the pure YBCO film, 1.1 MA/cm/sup 2/ in the 2.2 wt% BaZrO/sub 3/ doped film and 3.2 MA/cm/sup 2/ in the 3.0 wt% Y211 doped film.         High quality SmBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films on SrTiO/sub 3/ (100) substrates deposited by pulsed electron beam deposition    Kyoung Pil Ko, Seung Hyun Moon, Kyu Jeong Song, Chan Park and Sang Im Yoo Summary: We for the first time report a successful fabrication of a high-J/sub C/ SmBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//(SmBCO) thin film (/spl sim/240 nm thickness) on SrTiO/sub 3/ (100) substrate by the pulsed electron beam deposition (PED) process. For this study, we systematically investigated the effect of processing parameters, including substrate temperature (Ts), ambient oxygen pressure (PO/sub 2/), and target-to-substrate distance, on superconducting properties, including critical temperature (T/sub C/) and critical current density (J/sub C/), of PED-processed SmBCO films. The highest J/sub C/ value of 1.37 MA/cm/sup 2/ at 77 K in self field was obtained from an optimally processed sample using Ts of 900/spl deg/C (corresponding to real substrate temperature of 810/spl deg/C), PO/sub 2/ of 15 mTorr, and target-to-substrate distance of 9 cm, evidencing that this process is a potential alternative to the PLD process.         BSCCO/STO/BSCCO structures by the MOD method    H. Iwasaki, S. Machikawa, S. Yufune, T. Ishibashi and K. Sato Summary: Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/(BSCCO)/SrTiO/sub 3/(STO)/BSCCO trilayer structures were prepared by the metal-organic decomposition (MOD) method. In this study, annealing condition of BSCCO thin films prepared by the MOD method were investigated. High quality films having critical temperature (Tc) of 84 K were obtained on STO [001] substrate by a 2-step annealing process with 100% O/sub 2/ for 2 h at 870/spl deg/C and 10% O/sub 2/ for 2 h at 885/spl deg/C. The STO layer prepared by the MOD method was grown epitaxially on the BSCCO thin films, and the top BSCCO layer was also grown epitaxially on the STO layer. The BSCCO/STO/BSCCO structure showed a Tc of 77 K.         Transport characterization of silicon-YBCO buffered multilayers deposited by magnetron sputtering    A. Chiodoni, C. Camerlingo, R. Gerbaldo, L. Gozzelino, F. Laviano, B. Minetti, C.F. Pirri, G. Rombola, G. Tallarida, E. Tresso and E. Mezzetti Summary: The paper reports on results concerning the Si/YSZ/CeO/sub 2//YBCO multilayer prepared by means of magnetron sputtering. Such multilayer is considered for the possibility to compound the integration of YBCO films with silicon-based devices, with the unique, in perspective, properties of YBCO concerning photon sensors. We characterized YBCO films in such multilayer configuration by means of structural and dc transport measurements. It turns out that some granularity affects the transport properties of the YBCO film and lowers the critical currents. However, the lower temperature E-J characteristics are sharp enough to consider exploiting the transition between under critical and over critical (flux flow) state for future silicon-integrated broad-band photon sensors.         Preparation of stacked structures based on HTS by MOCVD: growth problems of c-axis and non c-axis BiSrCaCuO/Bi/sub 4/Ti/sub 3/O/sub 12/ heterostructures    K. Endo and P. Badica Summary: Several articles report two-layer c-axis heterostructures of Bi/sub 4/Ti/sub 3/O/sub 12/ on BiSrCaCuO. However in some applications, or for integration purposes, multi-layer geometries composed of alternating c-axis or non c-axis thin films might be useful. From this perspective we investigated growth of c-axis and non c-axis BiSrCaCuO on Bi/sub 4/Ti/sub 3/O/sub 12/ structures. The paper mainly focuses on evaluation of the structures from the growth, stability/interdiffusion, uniformity/morphology points of view based on structural and microstructural data.         The effect of composition and oxygen pressure on the superconducting properties of NdBa/sub 2/Cu/sub 3/O/sub 7-x/ thin films, deposited by rotatable magnetron sputtering    I. De Roeck, G. De Winter, R. De Gryse, J. Denul, A. Segers, E. Hollmann and R. Wordenweber Summary: Rotatable magnetron sputtering is still a promising technique for scaling up of large area deposition of high temperature superconducting thin films. Furthermore, it represents a standard equipment for very large area web coating and glass coating in industrial environment. We have already demonstrated that with rotatable magnetron sputtering epitaxial c-axis oriented NdBa/sub 2/Cu/sub 3/O/sub 7-x/ (NBCO) thin films could be obtained on MgO and YSZ single crystals and buffered tapes. The superconducting properties, like T/sub c/ and J/sub c/, of these films are still reduced due to low pressure sputtering. The c-axis lattice parameter is expanded or the sputtered NBCO thin film exists of 2 phases, one with the correct c-axis parameter and the other phase shows an elongated c-axis parameter, which influences the superconducting properties. In this work we will investigate the properties of thin films, sputtered with a nonstoichiometric target at low pressure (classical sputter regime). Especially, the influence of the oxygen partial pressure is very important and will be studied.         Deposition of Bi/sub 2/Sr/sub 2/Ca/sub n-1/Cu/sub n/O/sub y/ (bi-based) superconducting thin films by rf magnetron sputtering method under external magnetic field    N. Fujiwara, T. Onishi and S. Kishida Summary: We deposited Bi/sub 2/Sr/sub 2/Ca/sub n-1/Cu/sub n/O/sub y/ (Bi-based) superconducting thin films by rf magnetron sputtering method under external magnetic field, and investigated the effect of the external magnetic field on the growth and the superconductivity of the thin films. From the results, we found that the superconducting transition temperatures (T/sub c/) of the Bi-based thin films were improved by applying the external magnetic field during film deposition. The thin film with the highest T/sub c/ was produced by this method and showed the zero-resistance by the about 70 K without any annealing processes.         Effect of Sm/Ba substitution on the J/sub c/ in magnetic field of SmBCO thin films by low temperature growth technique    M. Miura, M. Itoh, Y. Ichino, Y. Yoshida, Y. Takai, K. Matsumoto, A. Ichinose, S. Horii and M. Mukaida Summary: We have reported superconducting properties of Sm/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub y/ (SmBCO; x=0.08) thin films prepared by the low temperature growth technique (LTG). LTG process is consisted of two steps as follows; a seed layer is deposited at 830/spl deg/C on MgO(100), and then upper layer is deposited at 740-780/spl deg/C on the seed layer. In order to investigate the effect of the fluctuations Sm/Ba composition ratio in the SmBCO matrix, we deposited upper layer with the Sm/Ba composition of x=0-0.12. The SmBCO films with x=0.04 and 0.08 show critical current density (J/sub c/) at 77 K of up to 5/spl times/10/sup 6/ A/cm/sup 2/ under 0 T and 1/spl times/10/sup 5/ A/cm/sup 2/ under 5 T for B//c at 77 K, respectively. The J/sub c/ of x=0.12 film dropped more sharply compared with the cases of x=0.04 and 0.08 films. From the microstructure analysis, it was found that the main phase of x=0.12 film was Sm-rich (Sm/sub 1.1/Ba/sub 1.9/Cu/sub 3/O/sub y/) phase, while that of x=0.04 and 0.08 films was stoichiometry. We speculated that the low-J/sub c/ of x=0.12 film in the magnetic fields was ascribed to the low physical meters of T/sub c/ and irreversibility field of the Sm-rich SmBCO main phase.         Laser scanning microscopy studies on detwinned YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films    J. Nam, R.A. Hughes, A. Dabkowski and J.S. Preston Summary: YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films are heavily microtwinned due to the crystal's orthorhombic unit cell and the confining effects of underlying substrate. Single crystal YBCO can be detwinned by thermally annealing the sample while applying uniaxial pressure. A similar technique has been devised to detwin a portion of a YBCO thin film. Through the use of photolithographic techniques, a suspended YBCO microbridge structure is fabricated, but with both ends of the bridge anchored to the substrate. During a subsequent anneal, the ends of the bridge induce a uniaxial stress along its length that arises from the lattice misfit and the thermal expansion coefficient mismatch between YBCO and the underlying materials. Without the confining effects of the substrate the suspended material can either detwin or twin on a macro length scale; the extent of which is largely determined by the substrate material. The ability to produce superconducting YBCO bridges that range from heavily microtwinned, to macrotwinned, to nearly detwinned provides an ideal experimental system. To study these phenomena, an optical and laser scanning microscopy set-up was employed. The images obtained provide insight into the role that twins play in determining the transport properties of superconducting YBCO thin films.         YBCO/YCBCO multi-layer healing technique for YBCO coated conductors    R.L. Meng, A. Baikalov, D. Pham, I.A. Rusakova, Y.Y. Sun, J. Cmaidalka, C. Wang, M.N. Iliev and C.W. Chu Summary: The influence of (Y/sub 0.8/Ca/sub 0.2/)Ba/sub 2/Cu/sub 3/O/sub y/ (YCBCO) over-layers on YBCO film properties has been studied on multi-layer YBCO/YCBCO films. The films were deposited on [001] MgO single-crystal substrates by pulsed-laser deposition. The results unambiguously demonstrate that a YCBCO over-layer can greatly improve the overall crystallinity of the YBCO films and thus their J/sub c/. An optimal layer-number (n) of the multi-layer YBCO (n layers)/YCBCO (n-1 layers) has been identified to produce a maximum J/sub c/ enhancement. The observations suggest that the YBCO/YCBCO multi-layer healing technique (MLHT) mentioned above may be used for the fabrication of low cost, high performance YBCO coated conductors by relaxing the stringent and costly requirements for precise atomic alignment employed in previous fabrication methods.         Large single grain (RE)-Ba-Cu-O superconductors with nano-phase inclusions    N.H. Babu, E.S. Reddy, Y. Shi, K. Iida, T.D. Withnell and D.A. Cardwell Summary: Nano-phase (5-20 nm) particles of YBa/sub 2/(Cu/sub 0.5/M/sub 0.5/)O/sub 6/ [where M=Nb, Ta, Mo, W, Zr and Hf] have been introduced successfully into RE-Ba-Cu-O single grain superconductors. A study to enlarge the size of a single grain containing these particles has been carried out involving measurement of the growth rate as a function of YBa/sub 2/(Cu/sub 0.5/M/sub 0.5/)O/sub 6/ phase concentration and degree of undercooling. The influence of the change in YBa/sub 2/(Cu/sub 0.5/M/sub 0.5/)O/sub 6/ concentration on microstructural features is also investigated and the superconducting properties of these large grain superconductors are presented.         Shaping of melt textured samples for fault current limiters    C. Harnois, S. Meslin, J.G. Noudem, D. Chateigner, B. Ouladdiaf and X. Chaud Summary: Resistive fault current limiters require long length of superconducting materials with relatively low sections. Meander is now a frequently used geometry for this type of application. Nevertheless, the shaping of a textured sample is a quite delicate operation because of its brittle character. Cracks are often observed in the final meander and reduce the life time of these samples. Recently, we have presented a new process that allows overcoming this problem. Sintered pellets are drilled to adopt the chosen geometry. Then, the texturing process is performed. By this way, no large mechanical stresses are applied to the fragile textured samples. Here, the idea is to reproduce the meander pattern. Holes performed do not cross the whole sample thickness but alternatively emerge from top or bottom of the pellet. Slices extracted from the textured samples face like meanders. Different geometries have been tested with holes emerging perpendicular to the (ab) planes or parallel to the (ab) planes. The annealing time under oxygen flow has been studied to fit the required critical current densities values, which were evaluated through transport measurements at 77 K. SEM studies allow comparing both configurations and in particular the crack existence. The quality of the textured material around the holes was found to be not deteriorated compared to the bulk microstructure. Finally, the influence of the holes on the texture quality was studied by neutron diffraction.         Superconducting and mechanical properties of RE-Ba-Cu-O/Ag bulk superconductors    H. Fujimoto Summary: Melt-processed REBaCuO (RE: rare earth) superconductors have a high J/sub c/ at 77 K and a high magnetic field, which are expected to be used for high field applications such as superconducting permanent magnets with liquid nitrogen refrigeration, flywheels, current leads and so on. In this study, we discuss Ag-doped YBaCuO and SmBaCuO bulks melt-processed in air and their characteristic superconducting and mechanical properties. Isothermal undercooling growth in air with oxygen annealing and the Nd123/MgO thin film cold seeding technique were applied to seek a highly efficient process, homogeneity of composition, and feasibility of batch production. Single-domain growth of superconducting phases was achieved. The results of mechanical properties, e.g. flexural stress of REBaCuO bulk superconductors show the beneficial effect of Ag particles in the RE123 superconducting phase on strengthening and toughening the material. The results imply that the melt process is feasible for producing larger bulks in large-scale applications. Applications of superconducting technology to railways are also discussed.         Growth and superconducting properties of Pb-free and Pb-doped bi-2223 crystals    E. Giannini, N. Clayton, N. Musolino, A. Piriou, R. Gladyshevskii and R. Flukiger Summary: High quality single crystals of both Pb-free and Pb-doped Bi-2223 (with sizes up to 3/spl times/2/spl times/0.1mm/sup 3/) were grown by means of a newly developed "Vapor-Assisted Travelling Solvent Floating Zone" technique in an image furnace. This technique allowed us to grow large Pb-doped Bi-2223 crystals for the first time. Post-annealing in high pressure oxygen (up to 10 MPa) enhanced T/sub c/ (up to 111 K) and sharpened the superconducting transition. The crystal structures of both Bi-2223 and Bi,Pb-2223 were refined and are reported in this paper. The unit cell of the Pb-free average structure is pseudo-tetragonal with a=5.4210(7), b=5.4133(6) and c=37.009(7) /spl Aring/. An incommensurate structural modulation along the direction of one of the short cell vectors has been defined (q/spl sim/0.21 a/sup */); however, the structure can be conveniently described in a supercell with a 5-fold volume (a=27.105(4) /spl Aring/). One additional O atom per translation unit of the modulation wavelength was found to be inserted into the BiO layers. Approximately 8% of the Ca sites are occupied by Bi atoms, and the refined composition is found to be Bi:Sr:Ca:Cu:O=2.16:2:1.84:3:10.16. Similar features are found in the Pb-doped phase. The magnetization of Pb-free Bi-2223 crystals has been studied. The vortex phase diagram has been traced and the anisotropy of Bi-2223 is found to be /spl gamma/=53 from measurements of the lower critical field, which is much smaller than that of Bi-2212 (/spl gamma/=165). Bi-2223 has a higher critical current density, and a reduced magnetic relaxation rate compared to Bi-2212, both of which are signatures of more effective pinning in Bi-2223 due to its reduced anisotropy.         Magnetic characterization of welded YBaCuO-bulk samples    M. Zeisberger, T. Habisreuther, D. Litzkendorf and W. Gawalek Summary: The welding of individually grown pieces of high temperature superconductor bulk material is the most promising way to obtain larger single domain tiles which are required for cryomagnetic applications. In this paper we present a method for the characterization of this kind of material. The method is based on the inductive measurement of the total current in ring samples using a Rogowski coil and an integrator circuit. The advantage of this technique is that it allows a direct measurement of the current crossing the artificial grain boundary without being influenced by the intergrain current and is independent of the sample size and geometry. We present the principle of the measurement and the calibrations of the system. The independence of the output signal on intragrain currents is demonstrated. The application of the method for the characterization of a welded sample is shown.         Processing of high-performance (Gd, Y)-Ba-Cu-O bulk superconductors with fine RE211 pinning centers    S. Nariki, N. Sakai, M. Murakami and I. Hirabayashi Summary: We have investigated the superconducting properties of (Gd, Y)-Ba-Cu-O bulk superconductors fabricated from precursors of Gd123-Y211 in a reduced oxygen atmosphere. The employment of ball-milled ultra-fine Y211 powder as a precursor material was very effective in enhancing critical current density (J/sub c/), since RE211 inclusions in the melt-textured samples could be drastically refined with decreasing the particle size of Y211 starting powder. The maximum J/sub c/ value reached an extremely high value of 380 kA/cm/sup 2/ at 77 K in self-field. However, size reduction of RE211 led to inhomogeneous distribution of RE211 inclusions. The trapped magnetic fields of Ag-added single-grain samples 25 mm and 33 mm in diameters were 1.5 T and 2.0 T at 77 K, respectively.         High-T/sub c/ superconductors-based nanocomposites with improved intergrain coupling and enhanced bulk pinning    T. Prozorov, B. McCarty, Baowei Liu and R. Prozorov Summary: Heterogeneous sonochemical synthesis was used to modify superconducting properties of granular YBa/sub 2/Ca/sub 3/CuO/sub 7-/spl delta// and Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+x/. Sonication of liquid-powder alkane slurries produces material with enhanced intergrain coupling and improved current-carrying capabilities. Co-sonication with metals and organometallics results in highly compact nanocomposites with increased magnetic irreversibility. Ultrasonic irradiation of YBa/sub 2/Ca/sub 3/CuO/sub 7-/spl delta// carried under partial oxygen atmosphere produces similar morphological effects and increases superconducting transition temperature due to effective surface saturation with oxygen. Detailed chemical and physical characterization of sonochemically prepared high-T/sub c/ nanocomposites is presented.         Study of the heterogeneous nucleation of 211-particle by the addition of CeO/sub 2/ precursor with different sizes    Chun-Chih Wang, Shih-Yun Chen, Po-An Lai, In-Gann Chen and Maw-Kuen Wu Summary: The microstructure and superconducting properties of air-processed melt-textured grown Y-Ba-Cu-O samples with the addition of CeO/sub 2/ precursor of different sizes, e.g. micro-scale and nano-scale were studied. Samples with micro-scale CeO/sub 2/ addition exhibit an enhanced Jc, which were attributed to the refinement of 211-particles. The mechanism for refining the 211-particles was proposed to be the formation of new nuclei sites from the reaction of CeO/sub 2/ and Y2-1-1 matrix in the melt-grown process. By reducing the CeO/sub 2/ precursors to nano-scale from micro-scale, significantly more heterogeneous nucleation site will be introduced with the same amounts of CeO/sub 2/ additions. And the J/sub c/ will be enhanced with the refining of 211 particles. But in this study, it shows the opposite results. The higher J/sub c/ value is enhanced by doping micro-scale CeO/sub 2/. Pinning forces vs. magnetic field studies indicated that both the nano- and micro- CeO/sub 2/ samples have the same pinning mechanisms as compared with that of the un-doped sample.         Flux pinning at grain boundaries in liquid phase sintered YBCO    Y. Yamada, T. Kuwahara, T. Donishi and S. Kubo Summary: Flux pinning behavior in liquid phase sintered YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) has been investigated in terms of preparation processing and pinning behavior. Liquid phase sintering method, which composed of two processes, mixing of YBCO precursor and liquid phase component and sintering at temperatures above the melting point of the liquid phase component, showed obvious Jc increase at high magnetic fields. Structure of the samples showing the increase of Jc by the liquid phase sintering is quite different from that showing no Jc increase. Structural dependence suggests that this pinning effect possibly originates from grain boundaries and oxygen deficiencies in the samples.         Trapped field in individual and stacked rings of bulk melt processed Y-Ba-Cu-O    T.D. Withnell, N.H. Babu, M. Majoros, E.S. Reddy, D.M. Astill, Y. Shi, D.A. Cardwell, A.M. Campbell, N. Kerley and S. Zhang Summary: Single grain rare earth barium cuprate [(RE)BCO] high temperature superconductors can trap large magnetic fields. In principle, samples can be stacked to form a quasipermanent magnet with a high length to width aspect ratio for engineering applications. The flux trapping properties of a stack of ring-shaped samples of Y-Ba-Cu-O (YBCO) were measured both on the surface and through the bore. Significant discrepancies between the experimental results and the predictions of a simple theory based on the Biot-Savart model were observed. These differences can be accounted for by the presence of a high density of small cracks parallel to the ab planes, which inhibit the circulation of current around the sample.         Grain boundaries in multi-seeded melt-grown superconductors    S. Haindl, M. Eisterer, H.W. Weber, N.H. Babu and D.A. Cardwell Summary: Future applications of high temperature superconductors require bulk materials of a complex shape. The multi-seeded-melt-growth process (MSMG) represents a promising technique for obtaining qualitatively well oriented bulk materials with different kinds of shape. In the MSMG process, several seeds are placed on a precursor pellet, from which the growth of the bulk starts. A certain problem of the MSMG process is that grain boundaries become inevitable when the growth fronts of two neighboring seeds collide. These grain boundaries are responsible for a reduction of the critical currents and pose a problem for high current applications. By polishing the sample step by step, the influence of the grain boundaries was investigated by scanning Hall probe measurements and by the magnetoscan technique. Additionally, optical microscopy and electron microscopy were employed to investigate the details of the microstructure.         Enlargement effect of the crucible size on Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/ single crystals grown by a modified vertical Bridgman method    H. Tanaka, Y. Echizen, S. Kishida and K. Ando Summary: Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/ (Bi-2212) superconducting single crystals were prepared by a modified vertical Bridgman method using large alumina crucibles of a 26 mm bore diameter with cone-shaped bottom. In order to obtain large and high quality single crystals, we optimized growth conditions using the large crucibles. We obtained a large plate-like single crystal with a size of 17.0 mm /spl times/ 5.5 mm when the crystal growth was carried out with the rotation speed of 50 rpm and at the temperature for starting the crystal growth of 1000/spl deg/C. In the single crystal, the FWHM value of the (0010) x-ray diffraction peak which was assigned to a Bi-2212 superconductor was small and about 0.06/spl deg/. T/sub c/ of the single crystal was about 87 K, which was higher than T/sub c/=82 K of the single crystals grown with smaller crucibles whose bore diameter is 35% less than the large crucibles.         Mechanical fragility and tri-dimensional crack structure in NdBaCuO top seeded and multi-seeded melt-textured samples    M. Gombos, V. Gomis, A. Vecchione, R. Ciancio, R. Fittipaldi, A.E. Carrillo, S. Pace and X. Obradors Summary: In large TS-MTG Nd123 single-domain samples, the main lifetime limiting problem is the appearing of macroscopic fissures in the bulk, that evolve into cracks and lead to sample destruction. To analyze this phenomenon we grew single-seeded pellets and multi-seeded bars, and characterized them by XRD, PLOM, SEM and EDS. We measured inductively their superconducting properties Tc and Jc. Fissures appear to belong to micro-fissures families, parallel to the crystallographic planes. We correlate their origin to local tetra-ortho structural transition, due to spontaneous oxygenation during growth process, and their evolution toward cracks to elastic relaxation of Nd422-rich quenched liquid deposits present in the growing front concavities. MS-TSG bars growth dynamics appear to differ from pellets one. In fact, with appropriate inter-seed spacing, the absence of quenched liquid deposits near the boundaries joining adjacent domains was observed. This fact reduces mechanical fragility perpendicularly to boundaries, but does not affect the fragility along the same. Further studies are in progress on this aspect.         Investigation of Pb-free Bi-2223 high temperature sintering    A. Polasek, L.A. Saleh, H. Borges, E. Hering, G.S. de Oliveira, E.T. Serra, J.H.G. Lima and F. Rizzo Summary: The Bi-2223 performance could be significantly improved by melt processing. However, it is a very difficult task, partly due to the volatility of Pb, its main dopant. On the other hand, it is also a hard task to obtain high Pb-free 2223 amounts, even by sinterization using a primary phase field composition (Bi/sub 2.5/Sr/sub 1.9/Ca/sub 2.1/Cu/sub 3/O/sub x/). In the present work, we investigate the sinterization of Pb-free 2223 in the presence of appreciable liquid fractions. The samples were analyzed by XRD, SEM/EDS and Magnetic Susceptibility. The results show significant Pb-free 2223 amounts after sintering at temperatures close to the melting. Such investigation represents an additional step toward the elucidation of the Pb-free 2223/melt equilibrium.         Process parameter dependent characteristics of centrifugally formed HTS Bi-2212 tubes    C.W. Park, N.I. Lee, G.E. Jang, D.W. Ha and T.H. Sung Summary: HTS Bi-2212 tubes were fabricated in terms of many different processing parameters by Centrifugal Forming Method. Initially powder was melted by induction heating. The optimum range of melting temperatures and mold preheating temperature were 1050/spl deg/C/spl sim/1100/spl deg/C and 500/spl deg/C for 30 min respectively. The nominal mold rotating speed was 1,000 rpm. A tube was annealed at 840/spl deg/C for 80 Hrs in oxygen atmosphere. The plates like grains more than 40 /spl mu/m were well developed along the rotating direction of mold. It was found that the tube processed with higher mold preheating temperature and faster rate of mold rotation speed shows better electric characteristics as compared with the tube normally processed. Uniform tube fabrication is one of the critical issues to satisfy the simultaneous quenching for the successful application in the resistive SCFCL.         Morphological and structural study on GdSr/sub 2/RuCu/sub 2/O/sub 8/ melt-textured samples    R. Ciancio, M. Gombos, A. Vecchione, R. Fittipaldi and S. Pace Summary: Strongly anisotropic magnetic and superconducting properties have been recently observed to coexist in Gd1212 (GdSr/sub 2/RuCu/sub 2/O/sub 8/). Magnetic ordering appears to be due to Ru planes while Cu planes are correlated to the superconducting properties. The unavailability of single crystals makes relevant the fabrication of oriented samples of macroscopic size by melt texturing techniques. Then we have grown MTG samples starting from 1 cm diameter pellets. Gd1210 (GdSr/sub 2/RuO/sub 6/) is added, analogously to Y211 in YBCO MTG processes. Preliminary studies have been performed on Gd1212 powders to explore the range of temperatures and the reactions involved. XRD analysis shows that a certain degree of orientation is present in our samples. By Polarized Light Optical Microscopy we have observed large oriented domains of almost millimeter size. Larger domains are expected by optimization of growth parameters. Images show even a homogeneous distribution of Gd1210 precipitates with a mean size of a few micrometers. SEM and EDS analyses have also been performed, confirming optical observations. Resistivity measurements show a 12 K wide superconductive transition with T/sub c/ onset at about 40 K. Optimization of successive annealing treatments are expected to reduce this width.         Macroscopic magnetic flux motion in Y-Ba-Cu-O bulk superconductor during pulsed field magnetization    R. Shiraishi, K. Fujiyama and H. Ohsaki Summary: Pulsed Field Magnetization (PFM) is one of the key technologies for utilizing RE-Ba-Cu-O bulk superconductors as a strong flux source for various applications. However, the performance of PFM is dependent on the conditions of applied magnetic field, cooling method, etc. and therefore, efficient and effective magnetization is an essential issue for practical use of PFM for high-performance bulk superconductors. In this work, macroscopic magnetic flux motion in Y-Ba-Cu-O bulk superconductor during PFM was observed using five co-axial pick-up coils.         Enhanced concentration of the magnetic flux in a superconducting cylinder    T. Asano, K. Itoh, S. Matsumoto, T. Kiyoshi, H. Wada and G. Kido Summary: The performance of a flux concentrator using an YBCO oxide superconductor was tested to raise the steady state magnetic field generated by the existing magnet. This concentrator was composed of an outside hollow cylinder and a pair of half cylinders that goes in and out in the outside cylinder. This flux concentrator generated additional magnetic field more than 1.6 T for an applied magnetic field 28 T.         Characterization and critical currents of the Superconducting ferromagnet RuSr/sub 2/GdCu/sub 2/O/sub 8/    R. Cobas, S.M. Perez Jr. and J.A. Aguiar Summary: Superconducting ferromagnet Ru/sub 1-x/Sr/sub 2/Gd Cu/sub 2+x/O/sub 8/ with x=0, 0.2 and 0.4 has been synthesized and characterized structurally, microstructurally and electrically by x-ray diffraction, scanning electron microscopy and resistivity measurements. Arrhenius plots of ln(/spl rho///spl rho//sub o/) vs T and potential energy are being reported. Two-different regimens of pinning are found. We show that U/sub 0/ data can be interpreted in terms of a possible structural change in the grain boundaries.         Fabrication and transport current properties of directionally solidified Y123 thin fiber    Y. Nakamura, T. Misu, Y. Ooishi, R. Inada and A. Oota Summary: In this paper, the effect of fabrication conditions on the microstructure and transport J/sub c/ properties of thin Y123 fibers were investigated. Fibers with 0.5 mm in diameter were directionally solidified by a zone melting method. The continuous growth structure was achieved in the samples grown at high pulling rates up to 10 mm/h, and the size of trapped Y211 particles was decreased with increasing pulling rate. The transport J/sub c/ values were maximum in the sample pulled at 6 mm/h, and the best I/sub c/ and corresponding J/sub c/ values achieved were 134 A and 1/spl times/10/sup 5/ A/cm/sup 2/ at 77 K self-field, respectively. Since the ab-plane of the Y123 crystal is reported to align parallel with the longitudinal direction of the sample grown at high pulling rate, this high J/sub c/ value was associated with this preferential crystal orientation as well as fine Y211 particles. Further increase of the pulling rate, however, resulted in the degradation of the crystallinity of the Y123, and the J/sub c/ values were decreased. The suppression of the formation of sub-domain structure and the preservation of better crystal orientation are therefore required to attain a high J/sub c/ value.         A new growth technique of Ca-free Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub x/ single-crystal whiskers using antimony-doped precursors    M. Nagao, K.S. Yun, H.B. Wang, K. Inomata, S. Kim, Y. Takano, T. Hatano, T. Yamashita, M. Tachiki, H. Maeda and M. Sato Summary: Single-crystal whiskers of Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub x/ with a length of about 4 mm were grown from an Sb-doped precursor. The optimum nominal composition of precursors in this Sb-doping method is Y/sub 2/Ba/sub 2.75/Cu/sub 3/Sb/sub 0.5/O/sub x/. Sb is not detected in the whiskers by energy-dispersive x-ray spectroscopy (EDS). The standard 4-probe transport measurements for the as-grown whiskers show a critical temperature T/sub C/ of about 90 K and a c-axis critical current density J/sub C/ of 9.51/spl times/10/sup 4/ A/cm/sup 2/ at 89 K.         Technical analysis on the application of HTS bulk in "Permanent Magnet" motor    M. Qiu, H.K. Huo, Z. Xu, D. Xia, L.Z. Lin and G.M. Zhang Summary: HTS materials can be used to develop novel permanent magnet (PM) motor. Based on the experimental and theoretical investigations, it was observed that the multi-impulse magnetization strategy should be selected for the constraints such as the temperature distributions and mechanical strength of the motor. The asymmetrical field distribution of HTS would induce torque ripples and unbalanced force. Proper cares have to be taken to avoid irreversible demagnetization. Resin impregnation and enclosing the rotor in a can/sleeve may provide the rotor enough mechanical strength to enable its high speed applications.         Relationship between critical current properties and microstructure of Er123 melt-solidified bulks    T. Nakashima, T. Maruyama, M. Honzumi, S. Horii, J. Shimoyama and K. Kishio Summary: We report impurities doping effectors of Pt and/or CeO/sub 2/ of microstructures, critical temperatures and critical current density (J/sub c/) in both a-growth and c-growth regions of the ErBa/sub 2/Cu/sub 3/O/sub y/ (Er123) melt-solidified bulks. The volume fraction of the Er/sub 2/BaCuO/sub 5/ (Er211) particles in Er123 matrix was always lower in the c-growth region than in the a-growth region. However, the second peaks of J/sub c/-B curves were more prominent in the c-growth region and its maximum J/sub c/ value reached 53 kA/cm/sup 2/ at 77 K under a magnetic field of 1 T for the bulk of the co-doping of 0.5 wt% Pt and 1.0 wt% CeO/sub 2/. Whereas the Er211 particles were finely dispersed in Er123 matrix in each case of Pt- or CeO/sub 2/-addition, the co-doping of Pr and CeO/sub 2/ showed most refined effect of the dispersion of Er211 particles. From the results of microstructures and J/sub c/, J/sub c/ value at zero field was found to be systematically improved with the reduction of diameter of the Er211 particles.         Fabrication and transport properties of MgB/sub 2/ mono-core wire and solenoid coil    K. Tanaka, H. Kitaguchi, H. Kumakura, M. Hirakawa, H. Yamada and M. Okada Summary: Round 100 m long class MgB/sub 2/ mono-core wires with Fe/Cu composite sheaths were successfully fabricated using an in situ PIT method. The J/sub c/ of the round MgB/sub 2//(Fe/Cu) wires reached 380 A/mm/sup 2/ at 4.2 K and 6 T, and exceeded 2500 A/mm/sup 2/ at 3 T. High areal reduction of the MgB/sub 2/ core was found to be effective in improving the transport properties of the MgB/sub 2/ wires. Using a 58 m long MgB/sub 2//(Fe/Cu) wire, we made a solenoid coil with 495 turns and tested it in liquid helium. The dimensions of the MgB/sub 2/ coil were 30 mm in inner diameter, 48 mm in outer diameter, and 50 mm in height. The I/sub c/ of the coil reached 214 A, which corresponds to a J/sub coil/=238 A/mm/sup 2/ and a core-J/sub c/=1420 A/mm/sup 2/. The coil generated a magnetic field at a center of B/sub o/=2.05 T and a maximum magnetic field of B/sub m/=2.17 T.         Improved superconducting properties of in-situ PIT-processed MgB/sub 2/ tapes    H. Kumakura, H. Kitaguchi, A. Matsumoto and H. Hatakeyama Summary: We fabricated pure and SiC-added MgB/sub 2//Fe composite tapes using a MgH/sub 2/ starting powder and applying heat treatments at 600-800/spl deg/C. At 4.2 K, upper critical field (B/sub c2/) of 27 T and 22.5 T were obtained for the SiC-added tapes. This B/sub c2/ at 4.2 K is comparable to that of the bronze-processed Nb/sub 3/Sn. For both the pure and SiC-doped tapes, the critical temperature (T/sub c/) values increased with increasing heat treatment temperature. The slope of the upper critical field vs. temperature (B/sub c2/-T) curves, dB/sub c2//dT, of the pure MgB/sub 2/ tape decreased with increasing temperature, a change leading to the lower B/sub c2/ at 4.2 K. Thus, the critical current density (J/sub c/) of pure MgB/sub 2/ tapes in high magnetic fields at 4.2 K decreased with increasing heat treatment temperature. The dB/sub c2//dT of the SiC-added tape, on the other hand, is almost independent of heat treatment temperature. Thus, the J/sub c/ at 4.2 K of SiC-added tape is also independent of heat treatment temperature. In the high temperature region, due to the higher T/sub c/ values, the J/sub c/ of the tapes heat-treated at 800/spl deg/C exhibit higher values than the tapes heat-treated at 600/spl deg/C. At 20 K, B/sub c2/ values of 9-10 T were obtained for the pure MgB/sub 2/ tape heat-treated at 600/spl deg/C and the SiC doped tape heat-treated at 800/spl deg/C. These B/sub c2/ values at 20 K are comparable to that of commercial Nb-Ti at 4.2 K. The 5 at.% SiC-added tape heat-treated at 800/spl deg/C shows J/sub c/(MgB/sub 2/ core) values higher than 10/sup 4/ A/cm/sup 2/ at 20 K in 5 T and at 30 K in 1 T. These J/sub c/ values are among the highest obtained for MgB/sub 2/ tapes.         Optimization of critical currents in MgB/sub 2/ wires and coils    A. Serquis, L. Civale, D.L. Hammon, G. Serrano and V.F. Nesterenko Summary: We present an analysis of the effect of SiC doping and heat treatments, including hot isostatic pressing (HIPing), on the microstructure, magnetization and transport properties of MgB/sub 2/ wires and coils prepared by the powder in tube (PIT) method. The HIPed wires have higher critical current densities (J/sub c/) than the annealed wires, especially at high temperatures and magnetic fields, and higher irreversibility field. The improvements are due to the reduction of porosity and to a high density of structural defects, which are the likely source of vortex pinning. We demonstrate that the high-quality properties mentioned above can be retained in longer wires. At 25 K our champion 6-layer coil, made with 25 meters of wire, was able to generate a field of 1 T at self-field. We were able to achieve even higher J/sub c/'s in another coil by combining the addition of SiC and HIPing. We also observed a larger upper critical field due to the SiC doping, which drives the sample to the dirty limit.         Enhanced critical current density in nanocrystalline mechanically alloyed MgB/sub 2/ bulk and Fe sheathed tapes    O. Perner, W. Hassler, C. Fischer, G. Fuchs, B. Holzapfel, L. Schultz and J. Eckert Summary: The application of the mechanical alloying (MA) technique for MgB/sub 2/ powder, tape and bulk preparation is a unique tool to obtain enhanced magnetic flux pinning by a combination of microstructure refinement and exact stoichiometry control of the MgB/sub 2/ compound. Additionally, variation of the stoichiometry as well as doping with MgO and SiO/sub 2/ lead to substantially increased critical current densities compared to the stoichiometric composition. MgB/sub 2/ bulk samples with a Mg excess of 5 wt.% show a critical current density J/sub c/ of about 1.5/spl middot/10/sup 6/ A/cm/sup 2/ at 7.5 K in self field. Doping with MgO, which improves J/sub c/ (1.6/spl middot/10/sup 6/ A/cm/sup 2/ at 7.5 K in self field), is more effective than doping with SiO/sub 2/. Stoichiometric and Mg-enriched partially reacted MA MgB/sub 2/ precursor powders were also used for powder-in-tube (PIT) tape fabrication with Fe sheath. By using this precursor the tapes can be annealed at relatively low temperatures of 500-600/spl deg/C. Despite reduced T/sub c/ values of 29-32 K, maximum critical current densities J/sub c/ of 35 kA/cm/sup 2/ and 9 kA/cm/sup 2/ in external magnetic fields of 7.5 T and 10 T, respectively, are achieved at 4.2 K. Microstructure investigations reveal that the high J/sub c/ values may be mainly due to the remarkably small MgB/sub 2/ grain size and defects, particularly MgO precipitates.         Anisotropy of J/sub c/ in ex situ MgB/sub 2//Fe monofilamentary tapes    P. Lezza, R. Gladyshevskii, C. Senatore, G. Cusanelli, HongLi Suo and R. Flukiger Summary: The anisotropy of the critical current density of Fe-sheathed ex situ MgB/sub 2/ monofilamentary tapes has been measured at various magnetic fields and temperatures and has been found to be influenced by the particle size of the starting material. Already reacted powders were milled in order to obtain different starting particle sizes. In order to understand the origin of the anisotropy, we have undertaken an X-ray study on the degree of texturing in the filaments after mechanical removal of the Fe sheath. The degree of texturing of the filaments at the interface Fe/MgB/sub 2/ and at the center of the filaments has been determined. A moderate texture has been found, being slightly higher at the interface.         Development of Fe-sheathed MgB/sub 2/ wires and tapes for electric power applications    H. Fang, P. Gijavanekar, Y.X. Zhou, P.T. Putman and K. Salama Summary: Superconducting coils with different dimensions were manufactured via a wind-reaction process by using Fe-sheathed MgB/sub 2/ wires, which were fabricated using the powder-in-tube method and ultra-fine starting precursors. Very good grain connectivity as well as high core density was obtained in Fe-sheathed wires and tapes. At 20 K and self-field, the critical current of the coil with ID 12 mm and 12 turns is 360 A, which is equivalent to the J/sub c/ of 1.8/spl times/10/sup 5/ A/cm/sup 2/. At 6 Tesla external magnetic field and 4.2 K, the coil with ID 14 cm and 10 turns possesses the J/sub c/ of 1/spl times/10/sup 4/ A/cm/sup 2/. In-field current carrying capability of MgB/sub 2/ wires and tapes were further enhanced by Ti additive. These results demonstrate the potential of MgB/sub 2/ superconducting wires and tapes for large-scale applications.         Effect of various additions on upper critical field and irreversibility field of in-situ MgB/sub 2/ superconducting bulk material    M. Bhatia, M.D. Sumption and E.W. Collings Summary: The effect of silicon carbide, carbon and metal-diboride (NbB/sub 2/, ZrB/sub 2/, and TiB/sub 2/) additions on the irreversibility field, H/sub irr/ and the upper critical field H/sub c2/ of bulk superconducting MgB/sub 2/ have been studied. Samples with 10 mole % of SiC and C and 7.5% of above named metal diboride additions were made separately by a powder milling and compaction technique along with the control sample. These samples were heat-treated at various schedules and H/sub c2/ and H/sub irr/ values were measured. An increase in /spl mu//sub o/H/sub c2/ from 20.5 T for pure sample to more than 33 T and enhancement of /spl mu//sub o/H/sub irr/ from 16 T to a maximum of 28 T for SiC doped sample was observed at 4.2 K. For a ZrB/sub 2/ doped sample 24 T and 28.6 T of /spl mu//sub o/H/sub irr/ and /spl mu//sub o/H/sub c2/ respectively we obtained with only 2 K drop in the T/sub c/.         Microstructure and J/sub c/-B performance of powder-in-tube MgB/sub 2/ wire made by using Mg/sub 2/Cu powders with low melting point    A. Kikuchi, Y. Iijima, N. Banno, T. Takeuchi and K. Inoue Summary: MgB/sub 2/ superconducting wires can be synthesized through a new route by using Mg/sub 2/Cu instead of pure Mg. The brittle Mg/sub 2/Cu compound can be easily broken into the fine powders by a mechanical grinding. In addition, its melting point are lower than that of pure Mg, thus the diffusion reaction for synthesizing MgB/sub 2/ may be promoted through their liquid states. Both of J/sub c/ and B/sub irr/ at 4.2 K improved apparently with decreasing the size of Mg/sub 2/Cu powders as a starting material. 100 A/mm/sup 2/ was obtained at 4.2 K and 4 T on the Fe-sheathed MgB/sub 2/ wire made by using Mg/sub 2/Cu powder with a diameter of a few microns. These improvements may be due to the enhancement of homogeneity of the powder mixture. According to the STEM observation, a lot of small MgCu/sub 2/ particles with a size of about 10 nm were dispersed in the MgB/sub 2/ matrix synthesized through a fine Mg/sub 2/Cu powders. They may act as the pinning centers in the present MgB/sub 2/ wires.         MgB/sub 2/ tapes with non-magnetic sheath: effect of the sintering temperature on the superconducting properties    V. Braccini, D. Nardelli, A. Malagoli, A. Tumino, C. Fanciulli, C. Bernini, A.S. Siri and G. Grasso Summary: A nonmagnetic sheath, namely a Ni/Cr alloy (Ni80/Cr20), was used to fabricate MgB/sub 2/ tapes through the powder-in-tube (PIT) ex-situ technique. A series of samples sintered at different temperatures between 200/spl deg/C and 950/spl deg/C were prepared in order to correlate all the superconducting properties between them and with the sintering temperature. The possibility of using a nonmagnetic but at the same time hard sheath chemically compatible with the MgB/sub 2/ phase made possible a simpler interpretation of transport and magnetic measurements in magnetic field. With the chosen cold working parameters, we found that the amount of MgB/sub 2/ lattice strain was not sufficient to produce any enhancement of the upper critical field. The effect of the heat treatment temperature was on one hand to increase the grain connectivity but also to reduce the pinning properties of the superconductor.         High critical current of Cu-sheathed MgB/sub 2/ wire at 20 K    H. Fang, P. Gijavanekar, Y.X. Zhou, G. Liang, P.T. Putman and K. Salama Summary: For large-scale electric power applications of MgB/sub 2/ wire, especially at AC environments, development of nonmagnetic sheath material is essential. In this study, Cu-sheathed MgB/sub 2/ wire was fabricated using the powder-in-tube method and ultra-fine Mg and B precursor prepared by high-energy ball milling. Lowering the annealing temperature and shortening the annealing time effectively limit the reaction between Mg and Cu. Critical current density of the wire annealed at 700/spl deg/C for 5 minutes is 4.3/spl times/10/sup 4/ A/cm/sup 2/ at 20 K and self-field. Adding excess Mg in precursor further enhances critical current to 250 A at 20 K and self-field. These results demonstrate the potential of Cu-sheathed MgB/sub 2/ wires for large-scale applications.         Effect of nano-particle doping on the upper critical field and flux pinning in MgB/sub 2/    S.X. Dou, S. Soltanian, W.K. Yeoh and Y. Zhang Summary: The effect of nano particle doping on the critical current density of MgB/sub 2/ is reviewed. Most nano-particle doping leads to improvement of J/sub c/(H) performance while some shows a negative effect as with Cu and Ag. Nano-carbon containing dopants have two distinguishable contributions to the enhancement of J/sub c/ field performance: increase of upper critical field and improvement of flux pinning. Among all the dopants studied so far, nano SiC doping showed the most significant and reproducible enhancement in J/sub c/(H). The nano SiC doping introduced many precipitates at a scale below 10 nm, which serve as strong pinning centers. J/sub c/ for the nano SiC doped samples increased by more than an order of magnitude at high fields and all temperatures compared to the undoped samples. The significant enhancement in J/sub c/(H) of nano-SiC doping has been widely verified and confirmed, having a great potential for applications. An attempt is made to clarify the controversy on the effects of nano Fe and Ti doping on J/sub c/.         Critical field of magnesium diboride in substituted and irradiated samples    C. Tarantini, V. Braccini, C. Ferdeghini, F. Gatti, P. Manfrinetti, D. Marre, A. Palenzona, I. Pallecchi, C. Bernini, A. Tumino, I. Sheikin, H.U. Aebersold, E. Lehmann and M. Putti Summary: We studied the upper critical field in poly-crystalline MgB/sub 2/ samples in which disorder was introduced by different ways: Al substitution and neutron irradiation. We observed that by Al doping critical temperature T/sub c/ decreases, the resistivity increases but the upper critical field, H/sub c2/, decreases. This behavior can be explained considering that Al substitutions affect only /spl pi/ bands leaving /spl sigma/ bands in clean regime; the decrease of H/sub c2/ can be correlated with suppression of the larger gap in doped samples. On the other hand neutron irradiation produces an increase of H/sub c2/. Neutron irradiation was carried on up to fluences of 1.4/spl middot/10/sup 20/ n/cm/sup 2/. To obtain a disorder structure homogeneously distributed, the experiment was carried out on bulk samples prepared with the /sup 11/B isotope. Up to fluences of 10/sup 18/ n/cm/sup 2/ the critical temperature is slightly diminished (36 K) and the superconducting properties are improved; the upper critical field is significantly increased: from 13.5 T to 20.3 T at 12 K. For larger neutron fluences the critical temperature is suppressed down to 9.2 K and the superconducting properties come out strongly degraded.         Thermodynamics of MgB/sub 2/-by calorimetry and Knudsen thermogravimetry    L.P. Cook, R. Klein, W. Wong-Ng, Q. Huang, R.A. Ribeiro and P.C. Canfield Summary: The vapor pressure of MgB/sub 2/, corresponding to the reaction, 2MgB/sub 2/(cr)/spl rarr/MgB/sub 4/(cr)+Mg(g), has been measured by Knudsen effusion vacuum thermogravimetry. The vapor pressure over the range 600/spl deg/C-850/spl deg/C can be expressed as: logp/sub mg/(Pa)=-1.129141(10000/T)+7.328161, where T is the temperature in Kelvin. By extrapolation, the 0.1 MPa decomposition temperature of MgB/sub 2/ is estimated to be 1268/spl deg/C. In a separate calorimetric investigation on the same material, using the isoperibol solution method, we measured the enthalpy of formation of MgB/sub 2/, /spl Delta//sub f/H/sub MgB2//spl deg/(298.15), to be -(155.9/spl plusmn/14.2)kJ/spl middot/mol/sup -1/. By combining the vapor pressure data and the enthalpy data, the Mg-rich part of the Mg-B phase diagram can be calculated. The measured vapor pressures are approximately an order of magnitude higher than those derived from published thermodynamic data. The lower limit of Mg pressures for the deposition of high-purity MgB/sub 2/ thin films at any given temperature may therefore be at a higher value than previously thought.         High density MgB/sub 2/ bulk materials of different grains size: supercurrents instability and losses in variable magnetic fields    G. Giunchi, S. Ginocchio, S. Raineri, D. Botta, R. Gerbaldo, B. Minetti, R. Quarantiello and A. Matrone Summary: The bulk MgB/sub 2/ material shows very promising characteristics to be applied in many AC devices, i.e. as electric motors, as magnetic field screening apparatus or as variable inductor or resistor for Fault Current Limitation. In all these cases the evaluation of supercurrents persistency and of the AC losses represents the first practical issue to be addressed. We report on the evaluation of these characteristics on very high density MgB/sub 2/ bulk materials, obtained by reactive liquid Mg infiltration of Boron powders preform. Varying the granularity of the original Boron powders, bulks of very different grains size distribution are produced that show different current carrying capability in magnetic field and temperature, indicating a different flux structure and dynamics. Performing AC susceptibility analysis in the low frequency range, the losses have been evaluated on several shapes of the probe materials from the cylindrical one to the slab one type and for several temperatures below Tc. For ring type samples the screening effect of the superconducting currents has been evaluated, in presence of static and variable magnetic fields. The results have been interpreted in term of the critical state model, evidencing the large effects of the thermal instability erasing from the thickness of the samples.         Upper critical fields up to 60 T in dirty magnesium diboride thin films    C. Ferdeghini, V. Ferrando, C. Tarantini, E. Bellingeri, G. Grasso, A. Malagoli, D. Marre, M. Putti, P. Manfrinetti, A. Pogrebnyakov, J.M. Redwing, X.X. Xi, R. Felici and E. Haanappel Summary: Upper critical fields of several magnesium diboride thin films were measured up to 28 T at the Grenoble High Magnetic Field Laboratory (GHMFL) in Grenoble and up to 60 T at the Laboratoire National des Champs Magne/spl acute/tiques Pulse/spl acute/s (LNCMP) in Toulouse. The samples were prepared both by pulsed laser deposition (PLD) and hybrid physical chemical vapor deposition (HPCVD) technique; they have critical temperatures between 29 and 39 K and normal state resistivities between 5 and 250 /spl mu//spl Omega/ cm; one of them has been intentionally doped with carbon. The measured critical fields, /spl mu//sub 0/H/sub c2/, were exceptionally high; we obtained the record value of 52 T at 4.2 K in the parallel orientation. In contrast with the BCS predictions, no saturation in H/sub c2/ at low temperature was observed. Furthermore, films with a wide range of resistivity values showed similar critical fields, suggesting that in a two band system resistivity and H/sub c2/ are not trivially linked. The high H/sub c2/ values seem to be related with the expanded c-axis. The structure of one of the samples was carefully investigated with X-ray diffraction at European Synchrotron Radiation Facility (ESRF) in Grenoble.         Effects of heat treatments on microstructure formation in MgB/sub 2//YSZ/Hastelloy film    S. Hata, H. Sosiati, N. Kuwano, Y. Tomokiyo, A. Matsumoto, M. Fukutomi, H. Kitaguchi, K. Komori and H. Kumakura Summary: Annealing processes in MgB/sub 2/ films deposited on yttria-stabilized zirconia (YSZ)-buffered Hastelloy substrates were studied by transmission electron microscopy. The MgB/sub 2/ films with Mg-rich compositions were fabricated at room temperature using a pulsed laser deposition (PLD) method. The as-deposited films do not exhibit clear superconducting transitions, and have inhomogeneous microstructures composed of amorphous regions and a small amount of crystalline MgB/sub 2/ and MgO with several tens of nm in size. Various sizes of voids are also incorporated within the amorphous regions. After the annealing at 600 or 680/spl deg/C, the films exhibit clear superconducting transitions. The amorphous regions crystallize into fine grains of MgB/sub 2/ or MgO 5-50 nm in size. The voids remain in the annealed films and their sizes depend on the annealing condition. Magnesium-and oxygen-rich layers are formed near the MgB/sub 2//YSZ interface and the film surface. It is suggested that the finer grains of MgB/sub 2/ and MgO obtained by the lower-temperature annealing give a larger critical current density under a high magnetic field.         Enhancement of T/sub c/ in MgB/sub 2/ thin films by laser local annealing    C. Portesi, A.M. Rossi and E. Monticone Summary: Films of magnesium diboride are promising for superconducting electronic and for detector applications. One of the main obstacles for device fabrication by traditional lithography is the sensitivity of this material to the chemical solutions normally employed in the standard structuring process. Moreover, underetching often limits the patterns resolution. By focused laser beam, high temperature can be reached suddenly in areas of few micrometer square, therefore in principle MgB/sub 2/ film patterning is feasible by local laser modification. In this work we investigate the effect of laser processing on MgB/sub 2/ thin films deposited by in-situ method. Before the exposure to the laser, the strip was wirebonded to enable the resistance to be monitored during the experiment. Increasing the power from 0.1 to 1 Watt, the room temperature resistance of the stripline increased until reaching the open circuit for higher laser power. By optical inspection, we observed that the color of irradiated area changed from yellow to black. The structure defined by laser presented a periodicity of about 1.7 /spl mu/m, where the width of each tracks was 1.5 /spl mu/m, thus comparable to the laser spot size. The T/sub c/ of the strip was increased by the laser process. This technique open the possibility to pattern superconducting film for device fabrication and circuits.         In-situ annealing effects on MgB/sub 2/ thin films fabricated by electron beam deposition    Z. Mori, T. Doi, Y. Ishizaki, K. Nagatomo, S. Hamada, Y. Hakuraku, M. Okada, K. Saitoh and H. Kitaguchi Summary: Although the as-grown method is becoming the main current for fabrication of MgB/sub 2/ thin films, the in-situ annealing method is still indispensable and effective for obtaining thin films with a high zero resistivity temperature and current density. We have investigated the effects of in-situ annealing on the superconducting properties of MgB/sub 2/ thin films. MgB/sub 2/ thin films were fabricated by electron beam epitaxy on C-plane sapphire (Al/sub 2/O/sub 3/) substrate. Thin films were produced by simultaneously evaporating B and Mg metal in a high vacuum of 3/spl times/10/sup -7/ Pa. Substrate temperature was 265/spl deg/C. The zero resistivity temperature of the as-grown thin films was 31 K. Electron beam deposition was followed by in-situ annealing in a high vacuum. In the optimal annealing process (a thin film is heated at 600/spl deg/C for one hour) we have consistently obtained thin films with a zero resistivity temperature of 35 K. In contrast, the critical current density of MgB/sub 2/ thin films was decreased by annealing. This suggests that the crystal grain boundaries in the MgB/sub 2/ thin films are working as a flux pinning site, and crystal growth from annealing brought about the reduction of current density.         MgB/sub 2/ thin films grown at different temperatures by hybrid physical-chemical vapor deposition    B.T. Liu, X.X. Xi, V. Vaithyanathan and D.G. Schlom Summary: We have grown MgB/sub 2/ films at different substrate temperatures by hybrid physical-chemical vapor deposition. X-ray diffraction analysis shows epitaxial growth at all temperatures, as measured at the substrate surface, between 550-700/spl deg/C. An optimal deposition temperature was found around 650/spl deg/C, at which the rocking curve is the narrowest, the residual resistivity is the lowest, and T/sub c/ is the highest. For the films deposited at lower temperatures, the rocking curve broadens, indicating a decreasing quality of crystallinity. The residual resistivity increases but the superconducting transition temperature remains nearly constant around 40 K when the deposition temperature is decreased to 550/spl deg/C. The deposition of epitaxial films with excellent superconducting properties at low substrate temperatures is important for device and circuit processing utilizing MgB/sub 2/.         As-grown superconducting MgB/sub 2/ films prepared by electron beam deposition    M. Okuzono, T. Doi, Y. Ishizaki, Y. Kobayashi, Y. Hakuraku and H. Kitaguchi Summary: As-grown superconducting MgB/sub 2/ thin films were prepared on Al/sub 2/O/sub 3/ [001] single crystals by electron beam deposition technique by changing the substrate temperature, the flux rate ratio of Mg/B and the basal pressure before the deposition starting. Higher Mg deposition rate and lower basal pressure gave a lower normal state resistivity of the MgB/sub 2/ thin films and gave a higher critical temperature. Magnetic hysteresis of the MgB/sub 2/ film prepared under lower basal pressure was smaller than that of the film prepared under higher basal pressure. Although the critical temperature of the MgB/sub 2/ film prepared under higher basal pressure became lower, the critical current density was enhanced. Higher basal pressure introduced some pinning centers in to MgB/sub 2/ films. These results suggest that precision control of the atmosphere during the MgB/sub 2/ deposition is very important for obtaining the high critical current density.         Superconducting properties and crystallinity of as-grown MgB/sub 2/ thin films synthesized using an in-plane-lattice near-matched epitaxial buffer layer    T. Kato, K. Yamanaka, S. Yata, Y. Yamada, S. Kubo, A. Matsushita, O. Sakata, S. Kimura and M. Takata Summary: As-grown MgB/sub 2/ thin films were synthesized at a low temperature of 270/spl deg/C on an in-plane-lattice-near-matched TiZr buffer layer grown on Al/sub 2/O/sub 3/-C substrate and Al/sub 2/O/sub 3/ substrate without buffer. The critical temperature (T/sub c/), critical current density (J/sub c/) and crystallinity of MgB/sub 2/ on TiZr buffered substrates were found to be high compared with those of MgB/sub 2/ on Al/sub 2/O/sub 3/; the improved T/sub c/ was around 35 K and J/sub c/ 6.6/spl times/10/sup 5/ A/cm/sup 2/ at 5 K under the magnetic field of 1 T perpendicular to the film surface. The epitaxial relationship of MgB/sub 2/ thin film on buffer layer was MgB/sub 2/[01-10]/spl par/TiZr[01-10]/spl par/Al/sub 2/O/sub 3/[11-20], but MgB/sub 2/ thin film without buffer layer had no epitaxial relationship.         Superconducting and microstructural properties of two types of MgB/sub 2/ films prepared by pulsed laser deposition    Yue Zhao, M. Ionescu, M. Roussel, A.V. Pan, J. Horvat and S.X. Dou Summary: Significant differences in superconducting and microstructural properties between two types of MgB/sub 2/ films prepared by pulsed laser deposition were determined. A very high H/sub c2/-T slope of 1.1 T/K was achieved in the in situ film. The J/sub c/-H curves of the in situ film also show a much weaker field dependence than that of the ex situ film. The magneto-optical (MO) images show that at 4 K the flux penetrates the in situ MgB/sub 2/ film through random paths, while for the ex situ film, the flux penetration pattern is mostly repeatable, indicating a defect-controlled flux penetration. Microstructural study (transmission electron microscopy and atomic force microscopy) revealed a relatively big grain size in the ex situ film. The correlation between the superconducting properties, microstructure and preparation conditions is discussed with regard to the two types of films.         A potential integrated low temperature approach for superconducting MgB/sub 2/ thin film growth and electronics device fabrication by ion implantation    Nianhua Peng, C. Jeynes, R.M. Gwilliam, K.J. Kirkby, R.P. Webb, Guosheng Shao, D.M. Astill and W.Y. Liang Summary: By implanting high fluence B into Mg targets, we demonstrate clearly that superconducting MgB/sub 2/ thin films can be formed at a low process temperature. The superconducting transition temperature T/sub c/ values observed are dependent on the growth condition. The ion beam synthesis experimental data are discussed and compared with simulation results of the B implantation process in Mg target. We propose that ion beam synthesis of MgB/sub 2/ is a potential approach for the mass production of superconducting electronics devices.         Characteristics of as-grown MgB/sub 2/ thin films made by sputtering    H. Shimakage, S. Miki, K. Tsujimoto, Z. Wang, T. Ishida and M. Tonouchi Summary: We describe the characteristics of MgB/sub 2/ thin films, which were deposited by sputtering. Under optimized conditions, the critical temperature was 29 K and the surface roughness of the films was 10 nm. The 1-micrometer-wide, 47.3-centimeter-long meander lines fabricated using the films had almost the same critical temperature and resistivity as of the MgB/sub 2/ films. However, magnetic susceptibility data showed that there was a relatively broad (approximately 8 K) superconductivity transition, which indicates that the films had nonuniformity in the thickness direction. From the magnetic-field dependence of the resistivity- temperature curve, H/sub C2/(0) was estimated to be 12 T in the ab-axis direction and 10 T in the c-axis direction. We also estimated that the coherent length was 4.8 nm in the c-axis direction and 5.7 nm in the ab-axis direction. The anisotropy value was 1.2, which is smaller than the values reported elsewhere. From the magnetic susceptibility measurements, the critical current density was estimated to be 1.7/spl times/10/sup 6/ A/cm/sup 2/.         Magneto-optical imaging studies of flux propagation in ultra-pure and carbon-doped MgB/sub 2/ thin films    Zuxin Ye, Qiang Li, Yufeng Hu, A.V. Pogrebnyakov, Y. Cui, X.X. Xi, J.M. Redwing and Qi Li Summary: The mixed state in c-axis oriented ultra-pure MgB/sub 2/ thin films and carbon-doped MgB/sub 2/ thin films produced by hybrid physical-chemical vapor deposition was studied using magneto-optical imaging (MOI) technique. In the ultra-pure MgB/sub 2/ films, a regular magnetic flux penetration pattern was observed, as expected from the Bean critical state model. This is in striking contrast to earlier MOI observations of MgB/sub 2/ films made by pulse laser deposition, where dentritic flux jumps were usually abundant at temperature below 10 K. In our carbon-doped MgB/sub 2/ thin films, similar dentritic flux jumps were also observed at low temperature and low applied magnetic field. It is evident that the dendritic flux jumps or stability of the film is strongly influenced by the material parameters of the films, rather than inherent in all MgB/sub 2/ thin films.         Superconducting nanocomposites: enhancement of bulk pinning and improvement of intergrain coupling    R. Prozorov, T. Prozorov and A. Snezhko Summary: Heterogeneous sonochemical method was applied for synthesis of novel superconducting nanocomposites consisting of magnetic (and/or nonmagnetic) nanoparticles embedded into the bulk of ceramic superconductors . In addition to in-situ production of the efficient pinning centers, this synthesis method considerably improves the interbrain coupling. Significant enhancement of the magnetic irreversibility is reported for Fe/sub 2/O/sub 3/ nanoparticles embedded into the bulk of MgB/sub 2/ superconductor. Nonmagnetic Mo/sub 2/O/sub 5/ nanoparticles also increase pinning strength, but less than magnetic Fe/sub 2/O/sub 3/. Detailed magnetization and electron microscopy characterization is presented. Theory of bulk magnetic pinning due to ferromagnetic nanoparticles of finite size embedded into the superconducting matrix is developed.         Field dependence of the critical current density of MgB/sub 2/ conductors between 4.2 K and 30 K up to 20 T    L. Arda, M. Ozdemir, Y. Akin, S. Aktas, M. Tomsic and Y.S. Hascicek Summary: The critical current density (J/sub c/) of the monofilament Monel/Fe/MgB/sub 2/ wire was measured between 4.2 K and 30 K with a Variable Temperature Insert (VTI) in a 20 T superconducting magnet using the analog DC pulse four-wire method with 1 /spl mu/v/cm criterion. The critical current density, J/sub c/ was measured to be 0.16/spl times/10/sup 5/ A/cm/sup 2/ at 4 T at 21 K for a MgB/sub 2/ sample which was annealed at 700/spl deg/C for 5 min and at 900/spl deg/C for 5 min under Ar gas flow. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) analysis were used to characterize the microstructure of the samples.         Effect of carbon nanotube size on superconductivity properties of MgB/sub 2/    W.K. Yeoh, J. Horvat, S.X. Dou and P. Munroe Summary: Experimental results are presented for the incorporation of carbon nanotube in polycrystalline MgB/sub 2/ superconductor based on X-ray diffraction and transmission electron microscopy measurements. Electron microscopy studies show that nanotubes are embedded into the MgB/sub 2/ matrix with a fraction of nanotubes found to be unreacted and entangled. In contrast, magnetization measurements indicate a change in the critical current density with the length of nanotubes and not with their outside diameter. This implies that longer nanotubes tend to entangle, preventing their homogenous mixing with MgB/sub 2/ and dispersion. Overall, carbon nanotube doping of MgB/sub 2/ enhanced the critical density and depressed the critical temperature.         The effect of nano-powder additions on the superconducting properties of MgB/sub 2/    K.J. Song, S.W. Kim, C. Park, J.K. Chung, J.S. Yang, J.H. Joo, R.K. Ko, H.S. Ha, H.S. Kim, D.W. Ha, S.S. Oh, E.Y. Lee, Y.K. Kwon and G.H. Rim Summary: To investigate the effect of Ag or SiC nano-powder additions on the superconducting properties of MgB/sub 2/, a series of superconducting (Ag)/sub (x)wt.-%/(MgB/sub 2/)/sub (100-x)wt.-%/(Ag/sub x/-MgB/sub 2/) and (SiC)/sub (x)wt.-%/(MgB/sub 2/)/sub (100-x)wt.-%/((SiC)/sub x/-MgB/sub 2/)(0/spl les/x/spl les/20), containing Ag and SiC nano-powders, respectively, of different diameters (30 nm and 130 nm), were prepared by a simple solid-state reaction route, cold-pressed into a pellet form and investigated. To maintain the same environment of MgB/sub 2//stainless-steel tapes/wires, Ag/sub x/-MgB/sub 2/ and (SiC)/sub x/-MgB/sub 2/ pellets made out of the mixed powders were put inside stainless steel tubes and then sintered at 900/spl deg/C for two hours in Ar atmosphere. Characterization performed included both X-ray diffraction and magnetization. No impurity phase was identified for as-rolled samples. However, both the Ag/sub x/-MgB/sub 2/ and (SiC)/sub x/-MgB/sub 2/ composite pellets, when sintered, contain various impurity phases. The isothermal magnetizations M(H) of a series of samples were measured at temperatures between 5 and 50 K in fields up to 5 T, using a PPMS-9 (Quantum Design). The optimal amounts of Ag and SiC nano-powder in Ag/sub x/-MgB/sub 2/ and (SiC)/sub x/-MgB/sub 2/ to obtain the largest flux pinning effect are /spl sim/8 and /spl sim/4 wt.-%, respectively. The "two-step" structures in ZFC M(T) curves of (SiC)/sub x/-MgB/sub 2/ were more developed than Ag/sub x/-MgB/sub 2/. The best flux pinning centers can be created by adding a suitable size and amount of SiC nano-powder, not too large to increase the decoupling between the MgB/sub 2/ grains.         Doping effects on critical current properties of MgB/sub 2/ bulks synthesized by modified powder-in-tube method    A. Yamamoto, J. Shimoyama, S. Ueda, Y. Katsura, S. Horii and K. Kishio Summary: Doping effects of B/sub 4/C and SiC on the superconducting properties of MgB/sub 2/ bulks synthesized by low-temperature solid-solid reaction and high-temperature liquid-solid reaction were systematically studied. Reduction of T/sub c/ and shortening of a-axis length are found to be derived from the substitution of carbon, not depending on carbon source. Field dependence of J/sub c/ at 5 K is strongly correlated with lowered T/sub c/ by doping. Moreover, our results indicate that the B/sub 4/C is also an effective dopant for the improving J/sub c/ under magnetic fields besides SiC, if the carbon substitution level is suitable. On the other hand, SiC was found to have advantageous points as a carbon source, because a moderate amount of carbon can incorporate into MgB/sub 2/ bulk even through the low-temperature reaction, /spl sim/600/spl deg/C.         Temperature and frequency dependence of the dissipated energy density in MgB/sub 2/ bulk    D. Botta, A. Chiodoni, R. Gerbaldo, L. Gozzelino, F. Laviano, G. Giunchi and B. Minetti Summary: This paper reports on an ac susceptometric analysis to evaluate the ac losses as a function of frequency and temperature at different external dc applied fields in MgB/sub 2/ twin bulk samples. The two investigated samples come from the same preparation batch. In agreement with partial results in literature, it turns out that the ac losses exhibit, as a function of frequency, a nonmonotonic behavior that is strongly temperature-dependent. In the lower range of analyzed temperatures the results are significantly affected by high-energy heavy ion irradiation. These last findings put forward puzzling questions about the creep dynamics in MgB/sub 2/. Finally the issue of a comparison with the ac losses in Ag sheathed/Bi2223 tapes is addressed. The comparison is made by means of measurements once performed with the same apparatus. It turns out that, taking into account the expected differences due to different ac applied fields, the absolute values of the dissipated energy density in MgB/sub 2/ and Ag/Bi2223 monofilamentary tape are of the same magnitude order and exhibit a similar behavior.         Crystal growth and critical current densities of polycrystalline MgB/sub 2/ superconductor    M. Maeda, K. Mizuno, A. Takashi, D. Uchiyama, T. Kawakami, H. Kobayashi, K. Yasohama and Y. Kubota Summary: We have investigated crystal growth and critical current densities of MgB/sub 2/ which was synthesized using stoichiometry or excess Mg and two kinds of B grain size. Excess Mg plays a role not only to promote crystal growth but also to make crystal grains fine. During crystal growth, the critical current densities decrease, although the density remains constant, approximately. Irrespective of the starting B powder, J/sub CM/ is the highest in the sample with the smallest crystal grains and highest density of MgB/sub 2/. The effects of excess Mg creates the possibility to control crystal size of MgB/sub 2/ by adjusting the quantity of Mg.         Glass-collective pinning and flux creep dynamics regimes in MgB/sub 2/ bulk    D. Di Gioacchino, P. Tripodi and J.D. Vinko Summary: Superconducting dynamic response in zero field cooling (ZFC) of MgB/sub 2/ bulk has been analyzed using high harmonic ac susceptibility measurements (/spl chi//sub n/). The driving external ac magnetic field is in the frequency range [107Hz         Microwave properties of MgB/sub 2/ thin films grown by reactive evaporation    B.H. Moeckly, K.E. Kihlstrom, A.T. Findikoglu and D.E. Oates Summary: We have grown MgB/sub 2/ films using the deposition technique of reactive evaporation. This method allows high-quality, large-area, double-sided films to be grown on a large variety of substrate materials. These films are therefore well suited for applications, several of which may exploit the low-loss high-frequency properties of MgB/sub 2/, including passive microwave resonators and filters, nuclear magnetic resonance coils, and RF cavities for particle accelerators. Determining the surface resistance and nonlinear properties of our films can thus give us an idea of their suitability for these applications, as well as tell us something about their fundamental superconducting nature. We have begun measuring the microwave properties of our films using both a parallel plate technique and by patterning the films into stripline resonators and lumped-element resonators and filters. The films display very low surface resistance values.         Properties of MgB/sub 2/ films with very high transport critical current densities    H. Kitaguchi, T. Doi, Y. Kobayashi, A. Matsumoto, H. Sosiati, S. Hata, M. Fukutomi and H. Kumakura Summary: Magnesium diboride, MgB/sub 2/, thin films are fabricated through two different kinds of process. One is an in-situ process by using electron beam deposition and the other is an ex-situ process by using the combination of pulsed laser deposition and heat treatment. The critical current density, J/sub c/, is investigated as a function of external magnetic field in the range of 0-7 T and/or temperatures ranging from 4.2 K to the critical temperature by using dc 4-probe transport method. The in-situ processed film shows very high J/sub c/, e.g., 7.1/spl times/10/sup 6/, 1.2/spl times/10/sup 6/, and 1.4/spl times/10/sup 5/ A/cm/sup 2/ in 0, 4, and 7 T (perpendicular fields), respectively. Angular dependence of J/sub c/ is much different between the two kinds of films. J/sub c/-angle (magnetic field) curves of the in-situ processed film show two peaks; one is around the field perpendicular to the film surface and the other is around the parallel field. On the contrary, the curves of the ex-situ processed film have only one peak around the parallel field. Microstructure analyses show that the in-situ film has columnar grains aligned perpendicular to the film surface and that the ex-situ one has granular grains with random orientations. These results indicate that the grain boundaries between columnar grains act as effective pinning centers and enhance J/sub c/ in the perpendicular fields.         Microwave characterization of as-grown MgB/sub 2/ thin films prepared by molecular beam epitaxy    M.V. Jacob, J. Mazierska, Y. Harada, T. Takahashi and M. Yoshizawa Summary: The MgB/sub 2/ superconductor with T/sub C/ of 39 K has great potential to replace some LTS materials in superconducting electronics. Thin films with low surface resistance, (R/sub S/) and negligible nonlinear effects are necessary to realize MgB/sub 2/ circuits for microwave applications. The R/sub S/ of MgB/sub 2/ thin films varies significantly depending on the method of deposition and deposition conditions. We have investigated microwave properties of MgB/sub 2/ thin films grown on MgO substrate by the Molecular Beam Epitaxy method with novel co-evaporation conditions at low deposition rate in ultra-high vacuum. The R/sub S/ of as-grown MgB/sub 2/ thin films have been measured using the Hakki-Coleman Sapphire dielectric resonator technique. High measurement accuracy was accomplished by using multifrequency measurements of S-parameters and the Transmission Mode Q-Factor technique for data processing to obtain the unloaded Q/sub o/-factor and resonant frequency of the dielectric resonator. Measured R/sub s/ of the MgB/sub 2/ films of 400 /spl mu//spl Omega/ was obtained at frequency of 24.6 GHz and temperature of 13 K. Microwave power characteristics of R/sub s/ indicates stable operation of MgB/sub 2/ devices for the input power up to 10 dBm.         Carbon-doped MgB/sub 2/ thin films grown by hybrid physical-chemical vapor deposition    A.V. Pogrebnyakov, J.M. Redwing, J.E. Giencke, C.B. Eom, V. Vaithyanathan, D.G. Schlom, A. Soukiassian, S.B. Mi, C.L. Jia, J. Chen, Y.F. Hu, Y. Cui, Qi Li and X.X. Xi Summary: Carbon-doped MgB/sub 2/ thin films have been produced with hybrid physical-chemical vapor deposition (HPCVD) by adding a carbon-containing metalorganic magnesium precursor, bis(methylcyclopentadienyl)magnesium, to the carrier gas. The amount of the carbon added, thus the carbon content in the films, was controlled by the flow rate of a secondary hydrogen gas flow through the precursor bubbler. X-ray diffraction and electron microscopy showed that the carbon-doped MgB/sub 2/ films are textured with c-axis oriented columnar nano-grains and highly resistive amorphous areas at the grain boundaries. When the amount of carbon in the films increases, the resistivity increases dramatically while T/sub c/ decreases much more slowly as the current-carrying cross section is reduced by the grain boundaries. The temperature-dependent part of the resistivity, /spl Delta//spl rho//spl equiv//spl rho/(300 K)-/spl rho/(50 K), increases only modestly until the highly resistive grain boundaries completely cut off the conducting path. The impact of the reduced cross section on critical current density J/sub c/ is discussed.         Superconducting MgB/sub 2/ thin films grown by a two-step process for tunnel junctions    T. Uchiyama, T. Takeda, H. Koga and I. Iguchi Summary: We present two novel preparation methods making use of the two-step process for superconducting MgB/sub 2/ thin films. We call them the cap and melt (CM) and the metal-plate cap and melt (MCM) methods. The MCM method, which is an improved CM method, enables us to raise more Mg pressure locally in the sample than the CM method. Using the MCM method, the MgB/sub 2/ thin films with T/sub c/>30 K were obtained. We have also succeeded in fabricating MgB/sub 2/ mesa structures of the size of 15 /spl mu/m/spl times/15 /spl mu/m-75 /spl mu/m/spl times/75 /spl mu/m useful for tunnel-junction fabrication. For mesa-structure fabrication, a lift-off procedure was employed in the MCM method to avoid the slow milling rate of MgB/sub 2/ material. The MgB/sub 2/ mesas showed almost the same critical temperature as that of the single films, as measured from the observation of Meissner state of the mesa by a scanning superconducting quantum interference device microscopy.         Third harmonic susceptibility and pinning properties of Fe/MgB/sub 2/ tapes    C. Senatore, N. Clayton, P. Lezza, S. Pace and R. Flukiger Summary: We report a study of the pinning properties of Fe/MgB/sub 2/ tapes performed by means of ac and dc magnetic measurements. In particular, the third harmonic response of the ac susceptibility has been measured as a function of the dc magnetic field up to 9 T, at different temperatures, for various frequencies and amplitudes of the ac field. The irreversibility line has been determined using the third harmonic onset criterion for samples made with different ball milled MgB/sub 2/ powders. The study of the harmonic response allows to probe the nature of the vortex pinning and to analyze its influence on the enhancement of the irreversibility field in strongly ball-milled samples. We have investigated the dynamic regimes governing the vortex motion in the tapes by comparing the experimental curves with numerical simulations of the nonlinear diffusion equation for the magnetic field. Furthermore, the pinning mechanism governing the electrical transport properties has been determined by studying the magnetic field dependence of the volume pinning force F/sub P/=J/sub c//spl times/B, calculated by extracting the critical current density J/sub c/(B,T) from magnetic hysteresis loops. Scaling of the F/sub P/(B) curves at different temperatures allows us to establish that the pinning centres are confined to the grain boundaries.         The microstructures and superconducting properties of MgB/sub 2/ tapes processed in-situ by a ball-milling method    A. Matsumoto, H. Kumakura, H. Kitaguchi, H. Hatakeyama, H. Yamada and M. Hirakawa Summary: We investigated the microstructures and superconducting properties of MgB/sub 2/ tapes fabricated by an in situ powder-in-tube method using ball-milled powders. The ball-milling technique was briefly applied to various powders, such as Mg, MgH/sub 2/, and B powder, and to powder mixtures of Mg and B, MgH/sub 2/ and B, and Mg+B+SiC. They were heat treated at the relatively lower temperature of 600/spl deg/C for 1 hour under an argon gas atmosphere. Though the ball-milling had almost no effect on the critical current density (J/sub c/) values when we used MgH/sub 2/ powder, we did observe a clear effect for Mg powder. Significant enhancements of the J/sub c/ values were obtained for the ball-milled powders of Mg+B and Mg+B+SiC. For the latter powder, we obtained a J/sub c/ value of 1.2/spl times/10/sup 4/ A/cm/sup 2/ at 4.2 K and 10 T. Those values are nearly equal to the excellent values of the in-situ processed tape of MgH/sub 2/+B+SiC powder that was not ball-milled. The high J/sub c/ values may be due to the fine B powder abrading Mg particles in the ball-milling processing, thereby producing fresh Mg and B surfaces.         Superconducting properties of powder-in-tube MgB/sub 2/ tapes prepared with fine powders    H. Yamada, M. Hirakawa, H. Kumakura, A. Matsumoto and H. Kitaguchi Summary: It is necessary to increase the Jc values to develop useful MgB/sub 2/ tape. We investigated superconducting properties of in situ processed Powder-In-Tube (PIT) MgB/sub 2/ tapes prepared with fine powders. Fine crystalline Mg powder with the average particle size of about 300 nm was fabricated by applying the thermal plasma method. In addition, 5/spl sim/15 mol% SiC powder doping was tried to enhance the Jc values. The transport Jc value of the 10 mol% SiC-doped tapes reached 250 A/mm/sup 2/ at 4.2K and 10 T. Furthermore we measured the upper critical field, B/sub c2/, and the irreversibility field, B/sub irr/, of the tapes. At 4.2K, the B/sub c2/ and B/sub irr/ of the SiC-doped tape reached 24 T and 21.5 T, respectively. This B/sub irr/ was almost equal to the B/sub c2/ of a conventional bronze-processed Nb/sub 3/Sn conductor. At 20 K, the extrapolated B/sub irr/ was around 9 T, which was comparable to the B/sub c2/ of commercial NbTi at 4.2 K. These results indicate that MgB/sub 2/ tape is promising not only for the high-field applications but also for the applications at 20 K with a convenient cryocooler.         SiC addition for MgB/sub 2/ superconducting wire by suspension spinning    T. Goto, K. Watanabe and G. Nishijima Summary: The effect of nanoscale SiC addition on the field dependence of J/sub c/ for MgB/sub 2/ superconducting wire by suspension spinning was examined to enhance the flux pinning. The suspension spinning of commercially available MgB/sub 2/ and SiC powders was examined to fabricate a long superconducting MgB/sub 2/ wire by using the spinning medium of poly(vinyl alcohol) (PVA) or polyacrylonitrile (PAN). The as-drawn filaments were uniaxially pressed under 20 MPa at 200/spl deg/C for 8 h to remove volatile components and connect the MgB/sub 2/ grains. The filamentary samples were enveloped by an iron sheet with a pellet of mixed powder of Mg and B to prevent Mg loss, and vacuum-sealed in a fused quartz tube and sintered. The field dependence of J/sub c/ for the samples was examined at 4.2 K in magnetic fields up to 14 T. The J/sub c/ of the sample was strongly dependent on the spinning medium and sintering condition. Addition of 5 at% SiC in the sample spun by PVA medium attained the maximum J/sub c/ value more than 1000 A/cm/sup 2/ at 4.2 K by applying the field of 14 T.         Microstructure and critical current densities of MgB/sub 2//Cu wires    K. Mizuno, D. Uchiyama, M. Maeda, T. Akao, T. Kawakami, Y. Kubota, H. Kobayashi and K. Yasohama Summary: Cu sheathed MgB/sub 2/ wires with a diameter of 2.50 mm and 0.93 mm have been fabricated by the In-Situ Powder-in-Tube PIT method. We have studied three subjects; the morphology of the wire core affected by the fabrication process of cold rolling, compounds in the core produced by the heat-treatment and effect of the microstructure on critical current densities Jc. The value of Jc is 10/sup 3/ A/cm/sup 2/ in 2 T at 25 K for the wire of 2.50 mm diameter. This value is three times higher than that of the wires of 0.93 mm diameter. EDS analysis and X-ray diffraction patterns have shown that in the wire with a diameter of 0.93 mm Cu and Mg diffusion on heat-treatment process, leading to formation of Cu-Mg compounds. We have paid attention to texture change of the wire core from granular to filamentary by the cold rolling process. It has been supposed that this filamentary texture gives an effect on the formation of MgB/sub 2/ and Jc value.         Fabrication of fine and homogeneous MgB/sub 2/ nano powders by spray pyrolysis    Jae-Woong Ko, Jaimoo Yoo, Young-Kuk Kim, Kook-Chae Chung, Hyungsik Chung and Sang-Im Yoo Summary: Homogeneous nano-sized spherical MgB/sub 2/ powders were fabricated by spray pyrolysis. The influence of solution concentration, furnace reaction temperature and mass flow of carrier gas on morphology and average particle size were investigated. MgB/sub 2/ powders were synthesized with or without further heat treatment. For adequate preparation conditions, it has mostly spherical, solid and narrow particle size distribution. Average particle size (X/sub 50/) distribution was below 100 nm. The critical temperature for the synthesized MgB/sub 2/ was around 36 K.         Low-field behavior of Ti-added MgB/sub 2//Cu superconducting wires    A. Gencer, A. Kilic, S. Okur, N. Guclu, L. Ozyuzer and I. Belenli Summary: We report on low-field magnetic properties of Ti-added (0-20 wt. % of Ti) Cu-clad MgB/sub 2/ superconducting wires. Wires were produced by mixing appropriate amount of Ti and reacted MgB/sub 2/ powder which was then placed inside Cu tubes with a diameter of 6 mm. The tubes were then cold worked by rolling or drawing to smaller diameters and then annealed at various temperatures to enhance the grain connectivity. XRD studies show that Ti addition results in new but minor phases. We have then measured ac susceptibilities in the temperature range between 20 K and 40 K in ac fields of 20-1600 A/m. The data show that an additional loss mechanism is established with Ti-addition. The calculated ac losses are increasing with increasing Ti-content in the main superconducting matrix.         Variable-temperature critical-current measurements on a Nb/sub 3/Sn wire    L.F. Goodrich and T.C. Stauffer Summary: We made variable-temperature critical-current (I/sub c/) measurements on a commercial multifilamentary Nb/sub 3/Sn wire for temperatures (T) from 4 to 17 K and magnetic fields (H) from 0 to 12 T using transport current. The sample had a diameter of 0.811 mm and a Cu/non-Cu ratio of about 1.5. The measurements cover the range of critical currents from less than 0.01 A to over 700 A. To verify the measurements at variable temperature, we compared critical currents up to 400 A on a specimen that was immersed in liquid helium to those on the same specimen in flowing helium gas. This comparison indicated our ability to control and measure specimen temperature was within 40 mK. The critical-current data presented include electric field/current (E-I) characteristics, and E-T characteristics at constant I and H, I/sub c/(H) at constant T, and I/sub c/(T) at constant H. Such data may be used to determine the temperature margin of magnet applications.         Investigation of instability in high J/sub c/ Nb/sub 3/Sn strands    A.K. Ghosh, L.D. Cooley and A.R. Moodenbaugh Summary: Magnetization measurements show that modern high current-density Nb/sub 3/Sn strands made for HEP programs exhibit flux-jump instabilities at low fields, due to their having large effective filament diameters. Such instabilities might be problematic because they can initiate a quench in low-field regions of magnets. We explored magnetization and transport measurements of the most recent high J/sub c/ Nb/sub 3/Sn strands and cables to probe the instability behavior. In the regime where flux jumps are seen by magnetization measurements, transport current measurements show a threshold for stability. This threshold is significantly lower than the critical current at higher fields, and above this threshold, quenching in the strand could be initiated by ramping the magnetic field. The threshold current depends on the wire size and internal filament design, and is consistent with stability criteria. In cables, quench currents were nearly independent of field after training, and were far below the expected critical currents. Details of these measurements and their implications for testing and use in magnets are discussed.         Instabilities in transport current measurements of Nb/sub 3/Sn strands    E. Barzi, N. Andreev, B. Bordini, L. Del Frate, V.V. Kashikhin, D. Turrioni, R. Yamada and A.V. Zlobin Summary: The critical current of Nb/sub 3/Sn strands used in Fermilab's high field magnets was measured at low and high fields under various experimental conditions using the voltage-current (V-I) and voltage-field (V-H) methods. The strands were produced using Modified Jelly Roll, Restacked Rod Process and Powder-in-Tube technologies. V-I characteristics at fields above 10-12 T with a smooth transition from the superconducting to normal phase allowed determining strand critical current. V-I and V-H measurements at low fields showed premature quenches due to magnetic instability in strands with high critical current density and large effective filament size. The results of the strand critical current measurements at low and high fields are herein presented.         Invariant strain analysis of the critical temperature T/sub c/ of Nb/sub 3/Sn    W.D. Markiewicz Summary: An analysis has been made that incorporates the strain dependence of the critical temperature T/sub c/ of Nb/sub 3/Sn in a calculation using the formalism of strong superconductivity. The critical temperature in the absence of strain depends on the harmonic phonon spectrum. The value of T/sub c/ can be related to the acoustic phonon modes. It is found that the phonon frequency characteristics can be determined, in a simple model, from a scalar strain energy potential that is a function of the invariants of the strain tensor under the cubic symmetry group and that includes harmonic and anharmonic terms. The strain dependent anharmonic phonon spectrum is found to result in the strain dependence of T/sub c/. A calculation of the normalized strain dependence T/sub c/(/spl epsiv/)/T/sub cm/ is presented for assumed wire and tape composite conductors and shown to agree with measurements from the literature over the full range of strain. The correspondence of the various strain scalar invariants with various aspects of the typical strain profile is discussed. The analysis contains the influence of the hydrostatic strain on T/sub c/ and relates the observed asymmetry in the strain profile between compressive and tensile intrinsic strain to the principle part of the third strain invariant.         Manufacture and superconductivity of tantalum matrix RHQT processed Nb/sub 3/Al superconductors    T. Takeuchi, N. Tatsumi, S. Nimori, H. Kitaguchi, N. Banno, Y. Iijima, A. Kikuchi and K. Inoue Summary: The replacement of Nb matrix with Ta for rapid-heating, quenching and transformation annealing (RHQT) processed Nb/sub 3/Al conductor seems to be advantageous for facilitating the RHQ operation due to a higher mechanical strength at elevated temperatures and less reactivity with the molten Ga in the quench bath and suppressing flux jumps in low magnetic fields. We have fabricated three grades of the Ta matrix precursor, in which the volume fraction of Ta matrix is different, so as to examine the drawability of such Ta matrix precursors. Also examined are the effects of using the Ta matrix on the RHQ condition, T/sub c/ values after quenching and subsequent annealing, respectively, J/sub c/ (core), overall residual resistivity, and magnetization curves. We have succeeded in drawing all of Ta matrix precursors and confirmed the favorable existence of a plateau region in the I/sub RHQ/-T/sub c/ relationship even for the Ta matrix RHQT Nb/sub 3/Al conductors. The resulting superconducting properties were comparative to those of Nb matrix conductors. The replacement of Nb matrix with Ta was very effective in suppressing flux jumps even at 4.2 K.         Cu ion plating as a technique for enhancing the mechanical, electrical and thermal bonding between Cu stabilizer and the RHQT-processed Nb/sub 3/Al conductors    A. Kikuchi, Y. Sakurai, K. Tagawa, T. Takeuchi, H. Kitaguchi, Y. Iijima, N. Banno and K. Inoue Summary: The surface of RHQT-processed Nb/sub 3/Al wires with pure Nb matrix are covered by a strong stable Nb oxide surface layer. In order to obtain good mechanical, electrical and thermal bonding between the Cu stabilizer and RHQT-processed Nb/sub 3/Al wires, it is required to destroy the Nb oxide layer on the surface of the wire. We tried to fabricate a thin Cu layer on the surface of the RHQT-processed Nb/sub 3/Al wires through the Cu ion-plating technique. Before electroplating of thick Cu stabilizers, Cu was ion-plated to a thickness of about 1 /spl mu/m. The Cu ion-plated wire showed no folded projections, cracks, or exfoliation of the Cu stabilizer even when the wire was bent through 180 degrees, showing that Cu and the wire were tightly bonded mechanically. This tight bonding between Cu and the wires should be due to the removal of stable Nb oxide layers from the surface of the wire. The V-I characteristic of wires that were ion-plated and then applied with an appropriate amount of Cu by an electroplating showed no quenching, and the wires were able to carry current up to the normal critical current transition. The measured values of recovery current were almost equivalent to the calculated values, showing that the ion-plated Cu/Nb interface had a very tight bond, allowing good electrical and thermal conductivity. In addition, a reel to reel Cu-ion plating apparatus for the long length wires is demonstrated, and Cu ion plating has been successfully carried out on 100 m long RHQT-processed Nb/sub 3/Al wire at present.         Flux pinning in RHQT-processed Nb/sub 3/Al after various transformation heat treatments    F. Buta, M.D. Sumption and E.W. Collings Summary: Jelly-roll Nb-Al strands were rapidly heated and quenched (RHQ) to bcc phase from temperatures around 1900/spl deg/C. Transformation heat treatments were subsequently applied to convert the as-quenched bcc phase into superconducting A15 phase. These heat treatments consisted of a fast ramp (0.5 to 10 min) to 1000/spl deg/C followed by a long hold (10 h) at 800/spl deg/C. Magnetization measurements performed by vibrating sample magnetometry under fields up to 30 T were used to determine the irreversibility field, the upper critical field and the dependence of the critical current density on the field. These properties were all found to be higher for samples with high initial heating rate in the transformation heat treatment. Some variability of the critical current density was observed for samples prepared under apparently the same conditions. The scaling of the bulk pinning force density over temperatures ranging from 4.2 K to 8 K is analyzed.         Effect of third-element additions on the upper critical field of bronze-processed Nb/sub 3/Sn    H. Kurahashi, K. Itoh, S. Matsumoto, T. Kiyoshi, H. Wada, Y. Murakami, H. Yasunaka, S. Hayashi and Y. Otani Summary: A direct measurement has been carried out of the upper critical magnetic field (B/sub c2/) of bronze-processed Nb/sub 3/Sn wires with and without the addition of various third-elements to the Cu-Sn matrix using a hybrid-magnet at the Tsukuba Magnet Laboratory at fields up to 30 T. The B/sub c2/ of pure Nb/sub 3/Sn rose with increasing heat treatment temperature up to 880/spl deg/C (B/sub c2/=24.7 T at 4.2 K), above which point it decreased rapidly. Its value was independent of the Sn content in the bronze. In the Ti addition samples, the optimum value of B/sub c2/ (=26 T at 4.2 K) depended on both Ti content and heat treatment temperature. When Sb was added, B/sub c2/ showed a sharp fall below a heat treatment of 700/spl deg/C due to the replacement at the Sn site by a Sb atom.         Properties and flux pinning of Cu-Nb superconductors with nanometric-scale pinning centers    D. Rodrigues Jr., C.A. Rodrigues, E.B. Silveira and E.G.M. Romao Summary: The introduction of normal phases into the superconducting phases is one of the most efficient forms to improve the pinning center densities and the critical current densities J/sub c/ of superconductors. Controlled generation of pinning centers with a projected distribution can contribute to estimate the pinning forces and mechanisms acting on the flux lines and to determine procedures to improve J/sub c/. The introduction of nanometric-scale Cu regions into the Nb filaments region during the fabrication of Cu-Nb (or Cu-Nb/sub 3/Sn) composite superconductors changes the properties of the superconducting phase, mainly due to the proximity effect. The present work shows the development and characterization of Cu-Nb composites prepared by successive bundlings followed by swaging and wire drawing, leading to dimensions of the Cu regions as small as 43 nm. The samples were characterized by SEM and by the measurements of electrical resistivity as a function of temperature, critical temperatures T/sub c/, J/sub c/ vs. H, and F/sub p/ vs. H, in different steps of deformation and different dimensions of Cu and Nb, in comparison to the superconducting coherence length /spl xi/. The results helped to determine the influences of the Cu presence and of the proximity effect on the superconducting properties, leading to important conclusions useful to the optimization of J/sub c/ in superconductors.         Results on mono element internal tin Nb/sub 3/Sn conductors (MEIT) with Nb7.5Ta and Nb(1Zr+O/sub x/) filaments    B.A. Zeitlin, E. Gregory, J. Marte, M. Benz, Tae Pyon, R. Scanlan and D. Dietderich Summary: Results on high current density high volume fraction Nb7.5Ta MEIT conductor incorporating a Sn+Ti source with a J/sub c/ of more than of 3000 A/mm/sup 2/ at 12 T are presented and compared to a MEIT conductor incorporating Ti in the Sn. The effect of two fins on the D/sub eff/ and magnetization are discussed. Results on moderate volume fraction MEIT conductors with Nb1Zr filaments both with and without the addition of Oxygen are presented. The effect of oxygen on Jc, grain size and layer Jc are presented and discussed.         Ti and Sn diffusion and its influence on phase formation in internal-tin Nb/sub 3/Sn superconductor strands    X. Wu, X. Peng, M.D. Sumption, M. Tomsic, E. Gregory and E.W. Collings Summary: Nb/sub 3/Sn superconductor wires were investigated in terms of Nb/sub 3/Sn phase formation and Ti diffusion. Two series of subelement strands (HP and EG) with Ta, Ti addition were fabricated. For comparison, a special model sample consisting of an annular Nb region containing Sn and surrounded by Cu was fabricated. All samples were given a standard initial up-ramp-and-hold schedule (185/spl deg/C/24 h (ramp rate 10/spl deg/ C/hour) + 340/spl deg/C/ 48 h (ramp rate 25/spl deg/C/hour) + 700/spl deg/C/up to 150 h (ramp rate 10/spl deg/ C/hour)). Reaction heat treatments at 700/spl deg/C were performed for various times on these subelements. The diffusion of Sn and Ti was studied by SEM, EDS, EPMA and STEM analysis. The Nb/sub 3/Sn reaction rate was determined for strands with and without Ti, and Ti was seen to double the rate of Nb/sub 3/Sn formation for these strands. EDS analysis showed that within the filament annular shell, an even distribution of Ti existed with a concentration of 0.4-1.0 at. %. However, for the highest Ti bearing sample, it had a Ti Nausite at the filament boundaries which may reduce the strands superconductor property.         Heat treatment optimization of differently alloyed Nb/sub 3/Sn superconductors    H. Mueller and T. Schneider Summary: For an upgrade of our HOMER II magnet facility from 20 T to 24 T one possibility is to build insert coils made of alloyed Nb/sub 3/Sn wires. These wires require a heat treatment (HT) to form the superconducting phase by solid state diffusion. The temperature and duration of the HT determines the size of the superconducting layers and the grain structure within these layers and hence physical properties like critical current and n-value. To optimize the HT with regards to the planned operation at very high magnetic fields, two differently alloyed conductors were heat treated between 600/spl deg/C and 750/spl deg/C for 50 h up to 350 h. Critical currents and n-values are determined by E(I)-measurements in magnetic fields up to 15 T. Special attention is drawn to the upper critical field and the maximum pinning force, which allow, in principle, an extrapolation of the measured data to higher magnetic fields. The results show differences of the optimum HT for different magnetic background fields, which will be discussed.         Development and research of the Nb/sub 3/Sn superconductor with improved structure of superconductive layer    A.E. Vorobieva, A.K. Shikov, V.I. Pantsyrny, E.A. Dergunova, K.A. Mareev, D.A. Farafonov, L.I. Vojdaev and V.M. Lomaev Summary: The creation of a fine uniform grain structure in Nb/sub 3/Sn superconductive layers is one of the methods to increase its current-carrying ability. In this work superconductors with ring filaments were developed, produced and studied. The ring filaments have been distributed uniformly in the bronze matrix to supply more uniform Sn diffusion from the bronze matrix to the filaments. The microstructure of the superconducting layer has been investigated using by SEM and TEM methods, and the critical current dependence on the diffusion heat treatment procedure has been studied. It is shown that Nb/sub 3/Sn layer in such type of filaments has more uniform and fine grain structure without column zone than the ordinary shape of filaments. That leads to an increase for the critical current density of the Nb/sub 3/Sn layer of wire with ring filaments and allows us to reduce the duration of the reaction.         Effects of Cu stabilizer configuration on thermal stability of Nb/sub 3/Sn composite superconductors under cryocooling condition    K. Watanabe, T. Mitsuhashi, N. Nanato, S.B. Kim, S. Murase, G. Nishijima and K. Miyoshi Summary: It is known that current sharing effects of the stabilizer are limited in cryocooling conditions being different from poolboiling. Therefore we have studied stability under it, focusing on minimum quench energy (MQE) of Nb/sub 3/Sn superconductors under various conditions of the applied magnetic field, temperature, and the transport current, for various volume fractions and configurations of Cu stabilizer. From the experimental results, the larger the external Cu volume fraction, the higher the MQE was obtained. All MQE data were summarized by only one line in characteristics of normalized MQE and normalized B(B/B/sub c2/). The obtained MQE behavior was to be characterized by only one empirical equation. It is thought that the obtained formula is useful for a standard of designing the Nb/sub 3/Sn superconductor and its coil under cryocooled condition.         Neutron irradiation effects on A15 multifilamentary wires    S. Haindl, M. Eisterer, R. Muller, R. Prokopec, H.W. Weber, M. Muller, H. Kirchmayr, T. Takeuchi and L. Bargioni Summary: Whereas Nb/sub 3/Sn wires are commercially available and produced in long lengths for the fabrication of large high field magnets, Nb/sub 3/Al is emerging as a candidate material for even higher fields, particularly for nuclear fusion devices. We are therefore investigating the basic superconducting parameters of both materials, such as the transition temperature, the critical current densities and the upper critical fields, as a function of gamma dose and fast neutron fluence. Whereas the transition temperature of these multifilamentary wires is found to decrease slightly, both J/sub C/ and the upper critical fields (as determined from Kramer plots) increase with neutron fluence, in agreement with previous work on A15 systems. The enhancement of the critical currents amounts to approximately 15%. Further irradiation work to higher fluences is under way, in order to investigate the limits of these materials for applications in a radiation environment.         ITT Nb/sub 3/Sn processing and properties    C.V. Renaud Jr., T. Wong and L.R. Motowidlo Summary: Multifilament Nb/sub 3/Sn superconductor has been produced by the internal-tin-tube (ITT) approach. In this approach, tubular niobium filaments containing either solid or powder cores of high tin content (e.g., greater than or equal to 90 percent tin) are processed into multifilament conductors containing filament diameters as small as 30 micrometers. The ultimate goal is to maximize noncopper critical current density while minimizing noncontributing conductor volume. The emphasis to date has been on wire fabrication rather than property optimization. Comparison to recent progress in our powder-in-tube A15 conductor is made. Niobium tube fabrication, wire processing, filament quality and Nb/sub 3/Sn microstructure are discussed, and the superconducting properties are presented.         Microstructural investigation of internal-tin Nb/sub 3/Sn strands    X. Peng, M.D. Sumption, M. Tomsic, E. Gregory and E.W. Collings Summary: Various types of internal-Sn multifilamentary strand were studied in an attempt to correlate fracture, subelement hardness, and interfacial conditions. Wire fracture (one of the main factors limiting the piece-length of multifilamentary precursor wires) is empirically known to increase with strand complexity. In an attempt to quantify this, a number of internal-tin multifilamentary precursor wires exhibiting various levels of drawability were investigated by microhardness as well as optical and electron microscopy. The progression of cross sectional stability was observed via optical microscopy as a function of wire drawing. Microanalysis both in the Scanning Electron Microscope (SEM) and the Scanning Transmission Electron Microscope (STEM) were used to study the interdiffusion of various elements through the interface between the restacked subelement and between the outer Cu sleeve, as well as inside the subelement. Comparing the hardness distribution along different regions of the interfaces between sleeve and subelement as well as between the subelements suggests possible causes for the occurrence of fracture.         Finite element analysis of drawing of multifilamentary wires    X. Peng, M.D. Sumption and E.W. Collings Summary: Co-deformation and possible fracture during the drawing of internal tin multifilamentary superconductor wires was investigated by FEM simulation. A thermomechanical, elasto-plastic finite-element method was applied to simulate the drawing process. The experimental conditions and materials of interest to composite superconductor manufacture were assumed. In this 3D FEM model, the billet configuration was 6 around 1, with the subelement simulated as an assembly of Cu-clad Nb filaments array enclosing a pure Sn core. The outer sleeve was Cu. The initial state of the billet was assumed to be one without subelement-to-subelement bonding. A simple ductile fracture criterion was employed in this investigation to estimate the possible occurrence of fracture with different area reductions.         Extrusion of a hole for tin core insertion in the subelement billet for internal tin superconductor    S. Datta, X. Fu and P.M. McIntyre Summary: A process has been developed for extrusion of a hollow Nb/Cu subelement billet for internal-tin Nb/sub 3/Sn superconductor. The development is part of a comprehensive strategy for cost reduction in fabrication of high-performance Nb/sub 3/Sn wire. A hollow-core billet was extruded using a tapered-mandrel die so that the hollow core was preserved through the extrusion process. The extrusion went well, but a mistake in our preparation of the rods that filled the billet caused the resulting extrusion to be unusable for drawing. A small admixture of Cu-clad NbTi rods was interspersed among pure Nb rods in the billet stack. The initial cold drawing of the NbTi rods caused them to harden dramatically compared to the Nb rods. When the billet was extruded the NbTi rods did not reduce in dimension and instead arranged themselves end-on in the final extrusion. Notwithstanding this disappointment, the inner and outer Cu boundaries extruded without deformation and the center hole has a clean, smooth surface that would be suitable for insertion of a Sn core rod after pickling.         Microstructural refinement of tantalum for Nb/sub 3/Sn superconductor diffusion barriers    S.N. Mathaudhu, R.E. Barber and K.T. Hartwig Summary: Cast pure Ta was deformation processed via equal channel angular extrusion and then recrystallized to produce a uniform, fine-grained bulk material. Extrusions were performed on 25/spl times/25/spl times/150 mm billets at room temperature in 90/spl deg/ tooling to strains of 9.3. The Vickers microhardness reaches near maximum levels after four extrusions. As-worked microstructures are composed of nonuniform submicron grains with apparent banding. A homogeneous and fine grained recrystallized microstructure (average grain size /spl sim/8 /spl mu/m) free of banding is obtained after four extrusions via route E multipass processing and a 1000/spl deg/C heat treatment. The high microstructural homogeneity of such a material may exhibit better co-reduction characteristics with surrounding Cu over conventionally processed Ta for superconductor diffusion barrier applications.         Severe plastic deformation of bulk Nb for Nb/sub 3/Sn superconductors    S.N. Mathaudhu, S. Blum, R.E. Barber and K.T. Hartwig Summary: Cast pure Nb with very large grains was processed by multipass equal channel angular extrusion (ECAE) to refine the microstructure. Extrusions were performed on 25 and 50 mm square cross section bars in a right angle die at room temperature following different extrusion routes to strains above nine. The hardness of Nb reaches a saturation level after eight extrusion passes where it is /spl sim/20% above that of fully worked Cu. Recrystallization bands appear to be absent in material processed by a new multipass route (E) which imparts shear on three intersecting planes and gives high processing yields. Hardness and optical microscopy measurements on recrystallized specimens are similar for 25 and 50 mm square bars which indicates a favorable scale-up response. Comparisons to commercially processed Nb and a cost estimate indicate that ECAE may be a viable method for manufacturing fine-grained, homogenous Nb for Nb/sub 3/Sn multifilamentary superconductor applications.         Superconducting properties and thermal stability of high-strength Nb/sub 3/Sn wire with Ta-reinforced filaments    G. Nishijima, K. Watanabe, S. Murase, K. Katagiri and G. Iwaki Summary: Superconducting properties of high-strength Nb/sub 3/Sn wires with Ta-reinforced filaments were evaluated at various temperatures and magnetic fields. Mechanical properties were also investigated at 4.2 K. The critical current was measured at temperatures up to 14 K and in magnetic fields up to 15 T. The data were well scaled by using empirical scaling laws. The stress-strain curve showed that the stress corresponding to 0.5% strain was 284 MPa. The value is twice as large as that of conventional Nb/sub 3/Sn wires, indicating that the high-strength Ta reinforcement enhances the mechanical property of the wire. Furthermore, the wire was sufficiently ductile. To evaluate the thermal stability, minimum quench energy and normal zone propagation velocity were measured under a cryocooled condition. The Ta reinforced Nb/sub 3/Sn wire shows relatively high stability and large propagation velocity. The results suggest that the Ta reinforced Nb/sub 3/Sn wire has sufficient applicability for cryocooled superconducting magnet windings.         Degradation and reversibility of critical current due to transverse compressive stress in Ta-reinforced Nb/sub 3/Sn superconducting strand    T. Takao, T. Ito, K. Umekawa, Y. Fukasawa, H. Tanaka and M. Umeda Summary: We have experimentally studied the degradation of the superconducting properties owing to transverse compressive stress in two kinds of Ta-reinforced Nb/sub 3/Sn superconductor. This paper reports the I/sub c/ degradation of those conductors due to stress exceeding the irreversible strain limit and the I/sub c/ behavior after releasing the stress. The I/sub c/ was measured in a 14 T background magnetic field at 4 K while applying a transverse compressive stress to the Nb/sub 3/Sn conductors. After measuring the I/sub c/, the stress was released to zero, and the I/sub c/ was measured again. And then, a stress that was a little larger than the former stress was applied again and the I/sub c/ was measured. According to the experimental results on the better performance conductor, even if the I/sub c/ decreased to 60 percent of the initial value, the I/sub c/ recovered to approximately 90% of the initial value when the stress became zero. The measured results of those conductors are shown, and the performance of the conductors against the transverse-compressive force is compared.         Scaling of the V-I characteristics in the ITER type Nb/sub 3/Sn strands in relation to the applied field and temperature    N.I. Kozlenkova, V.I. Pantsyrnyi, A.K. Shikov, A.E. Vorobieva and A.E. Mitin Summary: A description of voltage-current characteristics VCC (T,B) is presented in this paper. To describe an experimental VCC (T,B) database of ITER Nb/sub 3/Sn strands a relation is used containing four fitting parameters. Three parameters, namely: C, T/sub cm/ (0), and H/sub cm/ (0) describe I/sub C/(T,B) and one additional parameter characterizes the smoothness of the transition. The question is considered on the accuracy of measurement of the T, B, and I values needed to determine the fitting parameters accurately.         Critical currents of Nb/sub 3/Sn wire subject to applied transverse stress    H. Kitaguchi, S. Kimura, T. Shimonosono, S. Hanai, T. Takeuchi and K. Inoue Summary: We investigated the influence of transverse stress on the critical current, I/sub c/. We tested a Nb/sub 3/Sn, wire fabricated thorough the powder-in-tube route, mainly at 16 K and 2 T. In the stress window of 0-42 MPa, a reversible relation was confirmed between I/sub c/ and the compressive stress, /spl sigma//sub t/. After a slight increase of I/sub c/ at very small /spl sigma/, I/sub c/ decreases with further increase of /spl sigma//sub t/. When we unloaded within this stress window, I/sub c/ recovered to its virgin loading curve. I/sub c/ is more sensitive on /spl sigma//sub t/ in this work than in the I/sub c/-/spl sigma//sub t/ relations reported so far. This can be attributed to the lower B/sub c2/ at 16 K (3.8 T by Kramer's extrapolation) and possibly a nonuniform stress distribution in the present work. /spl sigma//sub t/ greater than 49 MPa caused an irreversible I/sub c/ degradation due to a plastic deformation of the filaments.         A device to evaluate the in-field transport properties of superconductors under strain    U.P. Trociewitz, R.P. Walsh, V.J. Toplosky, B. Trociewitz, H.W. Weijers and J. Miller Summary: A tensile test device has been built to investigate the in-field transport properties of research grade Nb/sub 3/Sn internal tin superconducting wires under axial strain. The device is operated by a stepper-motor and worm gear assembly and is rated for maximum loads up to 2.5 kN. Tensile strains of 1% can be easily accommodated. The probe is instrumented with vapor-cooled current leads and high temperature superconducting current lead extensions to allow for high transport currents up to 1.5 kA. The setup was operated in the NHMFL large bore resistive magnet in fields up to 20 T. Preliminary tests on short wire samples were carried out. Results of I/sub c/(B,/spl epsiv/) measurements at 4.2 K and n-values are presented.         Strain dependence of critical current in internal tin process Nb/sub 3/Sn strands    Sangjun Oh, Soo Hyeon Park, Chulhee Lee, Yongbok Chang, Keeman Kim and Pyeong-Yeol Park Summary: The development of a high performance superconducting magnet requires a thorough understanding of the strain effect in the critical current density (J/sub c/) of Nb/sub 3/Sn strands. A modified version of the WASP device is used for the investigation of the strain effect. The spring is made of BeCu alloy and is capable of applying strain up to 0.7% reversibly at 4.2 K. Several types of high performance Nb/sub 3/Sn strands (J/sub c/>1000 A/mm/sup 2/ at 12 T and 4.2 K) have been developed using internal tin process. A comparative study on the axial strain dependence of the critical current is performed.         Compressive pre-strain in Nb/sub 3/Sn strand by steel tube and effect on the critical current measured on standard ITER barrel    A. Nijhuis, W.A.J. Wessel, H.G. Knoopers, Y. Ilyin, A. della Corte and H.H.Jt. Kate Summary: The large Cable-In-Conduit Conductors (CICC) designed for the magnet coils in the International Thermonuclear Experimental Reactor (ITER), are composed of Nb/sub 3/Sn strand bundles in a Stainless Steel (SS) or Incoloy conduit. Both, the thermal contraction of the strand composite and the conduit material, define the final pre-strain after cooling down and thus affect the strand critical current (I/sub c/). The transverse forces, introduced when charging a coil, in addition affect the overall strain state due to bending and pinching of strands. Recently, periodic bending tests were applied on strand samples without additional axial compressive pre-strain. Here we explore the method of swaging a SS-tube around a strand to imitate the cool-down strain effect of the conduit. The experimental results of the I/sub c/ measurements at 12 T and 4.2 K are presented for a Nb/sub 3/Sn PIT strand with and without swaged SS tube on both Ti-6Al-4V and SS standard ITER sample holder (barrels). The effect of gluing the sample to the barrel is also investigated. The intrinsic strain state of the samples is verified by measurement of the I/sub c/ versus applied strain with the Pacman spring.         Effects of bending on cracking and critical current of Nb/sub 3/Sn ITER wires    B.J. Senkowicz, M. Takayasu, P.J. Lee, J.V. Minervini and D.C. Larbalestier Summary: Critical current (I/sub c/) measurements and microscopic crack investigations were performed on short samples of ITER (International Thermonuclear Experimental Reactor) wires, designed for the CSMC (Central Solenoid Model Coil), that were bent to curvatures ranging up to 0.3% at room temperature. I/sub c/ was found to improve significantly with bending. Microstructural investigation revealed that IGC and VAC samples were nearly crack-free at all bend strains while Furukawa samples had significant cracking due to polishing and unrelated to bending.         Microstructure, microchemistry and the development of very high Nb/sub 3/Sn layer critical current density    P.J. Lee and D.C. Larbalestier Summary: The non-Cu critical current density, J/sub c/, in engineering quality Nb/sub 3/Sn strand has increased beyond 3000 A/mm/sup 2/ at 12 T 4.2 K. Strand of this type, fabricated by a rod-in-tube technique using Nb-Ta alloy has been used by the Superconducting Magnet Group at LBNL to successfully fabricate a 16 T (4.2 K) dipole accelerator magnet. The grain size of this strand has been measured across the A15 layer and was found to be small (130 nm diameter) and homogeneous in morphology and size. This is despite a broad A15 layer thickness of 10 to 20 /spl mu/m. We have also measured the Sn concentration across A15 layers in this and two other high J/sub c/ strands. Although the Sn concentration in the A15 layers adjacent to the original Sn source were similarly high (/spl sim/24.5 at.%Sn) for all strands, the decline in Sn concentration across the A15 layer was markedly different. We found that the gradient in Sn concentration across the layer was reduced by higher temperature heat treatment. However the benefit to high field J/sub c/ of an improved overall irreversibility field, H/sup */, due to better A15 stoichiometry, is offset by the larger grain size produced at higher temperature and thus a lower density of flux pinning sites.         The introduction of Titanium into internal-Tin Nb/sub 3/Sn by a variety of procedures    E. Gregory, M. Tomsic, M.D. Sumption, X. Peng, X. Wu, E.W. Collings and B.A. Zeitlin Summary: The advantages of titanium as a third element in Nb/sub 3/Sn have been known for many years. It increases the upper critical field and lowers the critical current density at lower fields, thus reducing the losses, which are usually measured in this field region. Several methods for the introduction of titanium are listed and discussed briefly. The two methods discussed in more detail are both introduction by way of Nb47wt.%Ti. One is by wrapping foils around the filaments and the other by introducing rods into the filament array. A relatively uniform distribution of Ti in the filaments, results from both methods. Scanning Electron Microscopy (SEM) was used to illustrate the various phases, produced under different heat treatment conditions. Energy Dispersive Spectroscopy, (EDS) and Wavelength Dispersive Spectroscopy, (WDS) were both used to obtain compositional data.         The influence of Ti doping methods on the high field performance of (Nb,Ta,Ti)/sub 3/Sn multifilamentary wires using Osprey bronze    V. Abacherli, D. Uglietti, P. Lezza, B. Seeber, R. Flukiger, M. Cantoni and P.-A. Buffat Summary: We have analyzed the influence of the two different Ti doping methods on the superconducting properties of bronze processed (Nb,Ta,Ti)/sub 3/Sn multifilamentary wires with identical configuration, consisting of a Nb7.5wt.%Ta alloy processed to 14641 filaments of 4.5 micrometer size embedded in an Osprey bronze and externally stabilized by Cu. The first doping method introduces NbTi rods into NbTa filaments in a Cu15.4Sn Osprey bronze and has been applied to two wires containing 1 and 2 wt.%Ti in the filaments, respectively. The second method uses a Ti added Cu15.5Sn0.25Ti Osprey bronze, while the filaments of two thereby fabricated wires contain 0 and 0.5wt.%Ti, respectively. A reference wire containing no Ti addition was also prepared. All five wires were manufactured by three hot extrusion steps, cold drawing and several intermediate anneals. Wire samples with round cross section have been prepared and reacted between 600 and 730/spl deg/C. The residual Sn content in the bronze after reaction and the residual niobium ratio of the filaments were determined by means of EDX and SEM analysis, respectively. The grain size of the A15 layer has been compared by FE-SEM and the local composition profile has been observed by systematic quantitative EDX measurements made on a TEM. Non-Cu J/sub c/ values up to 300 Amm/sup -2/ and n values up to 50 at 17 T and 4.2 K reveal clearly the Ti added bronze as more performing.         High-field performance and structure of (Nb,Ta)/sub 3/Sn wires prepared from Sn-Ta matrix    K. Tachikawa, Y. Ikeda, Y. Koyata, T. Nakaze and T. Takeuchi Summary: Sn-Ta-Cu buttons with enough ductility to be fabricated into thin sheets were synthesized by melting a mixture of Sn+Ta+(Cu) powder. (Nb,Ta)/sub 3/Sn wires have been prepared by a Jelly Roll (JR) process and a filamentary process. In the JR process a Sn-Ta(-Cu) sheet was laminated with a Nb sheet forming a JR composite. In the filamentary process a Sn-Ta(-Cu) sheet was wrapped around thirteen Nb-1.0 at%Ta rods forming a filamentary composite. Both composites were fabricated into wires without intermediate annealing, and then heat treated. The effect of Ge and Ti addition to the Sn-Ta-Cu sheet has been studied in the JR wires. A small amount of Ge addition improves the workability of the sheet, while that of Ti addition enhances appreciably the J/sub c/ of the JR wires. Meanwhile, the 13-core filamentary wires exhibit equivalent high-field performance as that of the JR wires. Present new (Nb,Ta)/sub 3/Sn wires can be fabricated through a relatively easy process, and show attractive J/sub c/ in the field range of 22-23 T at 4.2 K and that of 24-25 T at 2.1 K.         Nb/sub 3/Sn multi-filamentary superconducting wires prepared by Ta-Sn powder in tube process    T. Miyazaki, H. Kato, K. Zaitsu, T. Miyatake, M. Hamada and K. Tachikawa Summary: Nb/sub 3/Sn multi-filamentary superconducting wires prepared by Ta-Sn powder in tube (TS-PIT) process have been developed. To develop the TS-PIT wire with applicable scale, a two stage approach was examined. At the first stage, two kinds of test wires with single and 19 filaments were fabricated by using 10 kg class billets. The critical current density (Jc) of the single filament wire was 167 A/mm/sup 2/ at 21 T and 4.2 K. Based on results of the first stage developments 50 kg class scale wire with 54 filaments was progressed in the following stage. This wire showed Jc of 136 A/mm/sup 2/ at 21 T, 4.2 K. Beside Jc, RRR and 0.2% yield strength were estimated. From these estimations, it was clear that the wire in the second stage has efficient applicable properties to the high field magnet. In both stage, microscopic analysis were followed for samples and found that over 50% in the sheath area reacted uniformly and the grain size was extremely fine. Through this development, TS-PIT processed multi-filament Nb/sub 3/Sn superconducting wire has been developed to applicable quality and scale.         Magnetization studies of high J/sub c/ Nb/sub 3/Sn strands    A.K. Ghosh, L.D. Cooley, A.R. Moodenbaugh, J.A. Parrell, M.B. Field, Y. Zhang and S. Hong Summary: Magnetization measurements have been made on several high J/sub c/ Nb/sub 3/Sn strands fabricated by different internal-Sn designs. In general these conductors have high magnetization at low fields, often exhibiting flux-jumps that are characteristic of large superconductor diameter. The effective filament size d/sub eff/ is approximately the size of the sub-element because the filament pack within each sub-element is fully coupled. Dividing the filament pack of the sub-element by adding Ta is effective for reducing d/sub eff/ and magnetization instability. But, some residual coupling across the dividers seems to remain below 6 K, perhaps due to Ta/sub 3/Sn. Implications for accelerator magnets are discussed.         Magnetization and d/sub eff/ in multifilamentary Nb/sub 3/Sn strands    X. Peng, M.D. Sumption and E.W. Collings Summary: The magnetization of various design internal-Sn type Nb/sub 3/Sn strands was analyzed in terms of effective filament diameter, d/sub eff/. Assuming circular geometry and ignoring demagnetization, values of d/sub eff/ have been calculated numerically for various configurations including unsplit subelement and split subelement cases with 2, 3, 4 and 6 splits. In the numerical calculation, the magnetization was treated as the summation of the magnetization of sections aligned perpendicular to the applied field. The angle-averaged d/sub eff/ value was calculated for every degree over the split regions. The d/sub eff/ of single restacked strands using subelements with various numbers of splits has been calculated and the results show the influence of the split design of strands on the magnetization in high fields. Furthermore, the numerical results were compared with the reported simplified analytical results, about 20% difference indicates the approximation of the simplification.         Structure and properties of differently directed deformed niobium-titanium alloy    O.V. Chernyi, G.E. Storozhilov, N.F. Andrievskaya, V.O. Ilichova, Y.D. Starodubov, O.I. Volchok, L.A. Chirkina, M.B. Lazareva and V.S. Okovit Summary: Cylindrical blanks of Nb-48.5 wt.%Ti alloy were prepared with a variable degree of plastic strain at different temperatures of the treatment by using the thermomechanical treatment consisting of deformation of the ingot via upsetting in a closed container and its subsequent extrusion from this container to the initial size. The true strain value over one cycle of such a treatment is approximately 1.6, with the number of cycles varying from 1 to 5. Measurements were taken of strength, plastic and elastic characteristics of the differently directed deformed alloy over different stages of superconductor fabrication. TEM was used to study the microstructure of the alloy in the course of plastic deformation. It is established that such combined treatment promotes formation of a better homogeneous dispersed structure. With that the current characteristics of the niobium-titanium superconductor increase. The highest critical current density after such a treatment was 4.1 k/mm/sup 2/ under the applied magnetic field 5 T at 4.2 K.         J/sub C/(B,T) characterization of NbTi strands used in ITER PF-relevant insert and full-scale sample    L. Zani, E. Mossang, M. Tena, J.-P. Serries and H. Cloez Summary: In the framework of the R&D for the ITER Poloidal Field Coils (PFC), a testing campaign was achieved on NbTi strands used in PFC-relevant modules. Three candidate NbTi strands have been used for manufacture of two Full-Size Joint Samples (PFIS and PF-FSJS) and the PF Conductor Insert (PFCI): - one strand manufactured by Europa Metalli (Italy), Ni plated and 0.81 mm diameter; - one strand manufactured by Alstom (France), with a CuNi barrier and 0.81 mm diameter; - one strand manufactured by Bochvar VNIINM (Russia), Ni plated and 0.73 mm diameter. An extensive test campaign has been performed at GHMFL (CNRS, Grenoble) in 2003 using the CEA VTC facility at temperatures ranging from 4.2 K to 7.5 K and at magnetic fields ranging from 2.5 to 10.5 T. The results showed that all three strands have quite close performances in the ITER PFC operating range despite their structural differences and that due to the critical current density curvature with temperature, they fail to meet the 1.5 K PFC temperature margin criterion by 0.2 to 0.3 K. Additionally, applications of corresponding fits to PF-FSJS tests showed consistent results and finally a brief discussion on fitting formula is presented.         Removal of supermicron particles from precursor powders for PIT fabrication of Nb/sub 3/Sn and Bi-2212 multifilament conductors    P.M. McIntyre, X. Fu, M. Hatridge, K. Kihm, T.K. Kim, D.J. Phares, S. Shastri and D. Smith Summary: A technique is being developed for separating all particles larger than /spl sim/1 micron from the precursor powders that are used in powder-in-tube (PIT) fabrication of superconductors. For both Nb/sub 3/Sn and Bi-2212, elimination of large particles enables drawing a multi-filament restack to smaller final filament size, with benefits for overall current density and suppression of persistent current effects. The technique uses virtual impact (VI) sizing, in which the powder is dispersed in an aerosol stream and passed through a nozzle array which separates particles larger and smaller than a critical size into separate flow channels. Unlike other separation techniques, VI exhibits a sharp threshold and yields extremely clean removal of large particles. Successful operation of a pilot system, studies of the separation dynamics, and issues relating to scale-up are presented.         A success story: LHC cable production at ALSTOM-MSA    P. Mocaer, G. Grunblatt, C. Verwaerde and C. Kohler Summary: ITER ,when constructed ,will be the equipment using the largest amount of superconductor strands ever built (Nb3Sn and NbTi). ALSTOM-MSA Magnets and Superconductors SA, "ALSTOM-MSA" received in 1998 the largest orders to date for the delivery of superconducting strands and cables (3100 km of cables for dipole and quadrupole magnets and various strands) for the Large Hadron Collider (LHC) being built at CERN Geneva. These orders to ALSTOM-MSA correspond to more than 600 metric tons of superconducting strands, an amount to be compared to around 600 metric tons of Nb3Sn strands and 250 metric tons of NbTi strands necessary for ITER. Starting from small and short R&D programs in the early nineties, ALSTOM-MSA has reached its industrial targets and has, as of September 2004, delivered around 74% of the whole orders with products meeting high quality standards. Production is going on at contractual delivery rate and with satisfactory financial results to finish deliveries around end 2005, taking into account additional orders from CERN received mid 2004. We will explain how we have succeeded to transform a "cottage industry" (40 people in 1997) to a "world class" production activity (170 people in 2004). Main industrial problems now solved such as investments and industrial set up and ramp up to reach plateau production as well as more technical problems closely linked to industrial ones such as multifilament wire breaks , strand magnetization, coating process (0.15 /spl mu/m controlled) and others, will be addressed and the various methods used to solve such problems will be reviewed.         Process simulation of reactive DC magnetron sputtering for thin film deposition of niobium-titanium nitride    H. Maezawa, T. Sato and T. Noguchi Summary: A process simulation for depositions of Niobium-Titanium Nitride (NbTiN) films with a reactive magnetron sputtering system was demonstrated. In the modeling, V/sub Ar/-dependent sputtering yields with quasi target erosion profile were newly incorporated for the precise optimization of the sputtering conditions. The numerical results were found to agree well with the experimental data. We present the dependence of the film resistivity and T/sub c/ on the chemical composition. It was also confirmed by the simulation that /spl Delta/V can be a good indicator to control the chemical compositions for the fabrications of high T/sub c/ films. In addition, the resistivity and stress were found to deeply relate to the total process pressure and residual N/sub 2/ gas in the plasma as suggested in the atomic peening model. Preliminary results suggest that the process simulation has a potential of the useful tool to control the properties of superconducting films.         Gallium ion implantation into niobium thin films using a focused-ion beam    A.M. Datesman, J.C. Schultz, T.W. Cecil, C.M. Lyons and A.W. Lichtenberger Summary: We have implanted 30 keV gallium ions into niobium films 100 /spl Aring/ thick using a focused-ion beam (FIB). The nature of the FIB tool allows the irradiation of a specific, controllable, area of the substrate, from hundreds of square microns down to an arbitrary, user-defined pattern defined by a 70 /spl Aring/ stencil. A sacrificial layer of gold covering the niobium controls the range of the incident gallium ions and prevents the niobium film from sputtering away under bombardment. This article examines the behavior of these films phenomenologically, including information about the changes in transition temperature and resistance of the implanted samples. Also a curious unexplained feature of the resistive transition at implant doses below about 3/spl times/10/sup 19/ cm/sup -3/ will be presented and discussed.         Tuning of tungsten thin film superconducting transition temperature for fabrication of photon number resolving detectors    A.E. Lita, D. Rosenberg, S. Nam, A.J. Miller, D. Balzar, L.M. Kaatz and R.E. Schwall Summary: Tungsten thin films can form in one of two crystal structures: alpha (bcc), with a superconducting transition temperature (T/sub c/) of 15 mK, and beta (A15), with a T/sub c/ between 1 and 4 K. Films with intermediate T/sub c/s are composed of both alpha and beta phases. We have investigated how to tune the film T/sub c/ in order to obtain certain values (T/sub c/ /spl sim/ 100 mK) suitable for the fabrication of photon number resolving transition-edge sensor (TES) and arrays of TES detectors for astronomical and quantum information applications. Variation of deposition conditions, and also the choice of the underlayer/coating for equal deposition conditions, affect the T/sub c/s of tungsten films. We have used x-ray diffraction to determine the structure of tungsten thin films and film stress. The results indicates that the film stress state depends on the underlying substrate and coating. To understand the variation of T/sub c/ values and to allow precise tuning of these values, we have investigated substrates and coatings for tungsten film multilayer stacks and determined tungsten film stress by x-ray diffraction at both room temperature and 8 K.         In-situ resistance measurements of RHQT processed Nb/sub 3/Al superconductors    K.S. Tan, S.C. Hopkins, I. Pong, R.J. Stearn, B.A. Glowacki, A. Kikuchi, T. Takeuchi and K. Inoue Summary: The bcc supersaturated solid solution, Nb(Al)/sub ss/ obtained by rapid heating and quenching of a multifilamentary Nb/Al composite wire has shown a change from a disordered to an ordered structure before finally transforming to the A15 Nb/sub 3/Al phase. It is believed that such ordering is responsible for suppressing the critical temperature, T/sub c/, the upper critical magnetic field, B/sub c2/, and the critical current density, J/sub c/. The ordering of the bcc phase can be suppressed by increasing the heating rate, and therefore this should improve the superconducting properties of the resulting Nb/sub 3/Al wires. Enhancement of J/sub c/ can also be achieved if the Nb(Al)/sub ss/ phase is mechanically deformed before transformation. The transformation process was studied in as-quenched and mechanically deformed Nb/Nb(Al)/sub ss/ wires by in-situ resistance measurement under heating at two different rates, 200/spl deg/C/h and 800/spl deg/C/h. The electrical resistivities of the wires decrease abruptly during the transformation from bcc to A15 phases and the process is much faster for mechanically deformed wires. Also, the heating rate affects the onset temperature of the A15 transformation. The results also show that the J/sub c/ of the transformed Nb/sub 3/Al wires increases with increasing reduction in area.         Fabrication of V-based Laves phase compound multifilamentary wires by applying a rapidly-heating/quenching process to PIT precursors and using a V tube    Y. Hishinuma, A. Kikuchi, Y. Iijima, Y. Yoshida, T. Takeuchi, A. Nishimura and K. Inoue Summary: We fabricated V-based Laves phase compound such as V/sub 2/(Hf,Zr) multifilamentary wire by applying a rapidly-heating/quenching (RHQ) process. Pure Hf and Zr metal powders were mixed and it put in high pure V tube composed with tantalum (Ta), and it was drawn in order to make wire (powder-in-tube (PIT) method). The wires were heat-treated by RHQ process, and some were annealed additionally in vacuum. Since Ta has a higher melting point than V, it is expected that the alloying prevents from breakage of the precursor wire during RHQ treatment because the maximum temperature exceeds 2500 K. SEM observation confirmed that the thick reaction layer within about 10 microns was formed on the boundary of the powder mixture filament and the V matrix after the RHQ. T/sub c/ values of the as-quenched samples increased with increasing maximum temperature during RHQ process, and the maximum mid point T/sub c/ value was about 8.0 K. The transport J/sub c/ properties under magnetic fields were also investigated.         Trial manufacture of a 2.5 km class long-length of Nb-matrix jelly-roll Nb/Al precursor wire for RHQT process    K. Tagawa, T. Takeuchi, N. Banno, Y. Iijima, A. Kikuchi, H. Kitaguchi, G. Iwaki and Y. Sakurai Summary: Since the RHQT-Nb/sub 3/Al conductor shows excellent superconducting characteristics in high magnetic fields, its application to a 1 GHz NMR insert coil is in particular expected. For such an application, the development of a long-length of RHQT-Nb/sub 3/Al wire is indispensable. However, the unit length of wire achieved was no more than 400 m so far, due to a restricted size of the multi-billet, while about a 2.5 km-length of wire is necessary for the NMR insert coil application. Thus, an attempt was made to produce a 2.5 km-length of precursor wire by using a large-sized billet, and we have succeeded in producing such a long-length of precursor wire (2.6 km) without any breaking of wire during hydrostatic extrusion and subsequent drawing processes.         Fabrication and superconducting properties of ex-situ PIT processed A15 type tape conductors    H. Kumakura, A. Matsumoto, H. Kitaguchi, H. Yamada, M. Hirakawa and K. Tachikawa Summary: We fabricated three kinds of A15-type superconducting tapes by applying ex situ Powder-In-Tube method. Nb/sub 3/Sn, Nb/sub 3/Al, or V/sub 3/Si superconducting powder was tightly packed into a stainless steel (SUS 316) tube or a Cu-10wt%Ni tube. These tubes were cold-rolled into tapes. All tapes showed substantial J/sub c/ values at 4.2 K without any heat treatment. The SUS 316 tube with superior mechanical hardness was effective for obtaining high density A15 cores and realizing high J/sub c/ values although T/sub c/ values were depressed by the lattice distortion. Annealing after cold rolling recovered T/sub c/ values and enhanced J/sub c/ values of all three kinds of tapes. J/sub c/ increased with increasing annealing temperature. More than two orders of magnitude higher J/sub c/ values were obtained for Nb/sub 3/Sn and V/sub 3/Si tapes after the annealing at 900/spl deg/C, while the J/sub c/ enhancement of Nb/sub 3/Al tape was smaller than one order of magnitude. This difference of J/sub c/ enhancement can be explained by the difference of microstructural change by the annealing. The field dependence of J/sub c/ decreased with increasing annealing temperature, which can also be explained by the recovery of T/sub c/.         Mechanical properties of YBaCuO formed on Ni-based alloy substrates with IBAD buffer layers    K. Shikimachi, N. Kashima, S. Nagaya, T. Muroga, S. Miyata, T. Watanabe, Y. Yamada, T. Izumi and Y. Shiohara Summary: Mechanical properties of YBaCuO superconducting tape produced by a multi-stage metal-organic chemical vapor deposition (MOCVD) technique have been investigated. It is important for YBaCuO superconducting tape to tolerate stress strain and maintain flexibility in order to be used for electric power applications, magnetic applications, and so on. At this time, we have produced an approximately 0.25 /spl mu/m YBaCuO layer on a pulse laser deposition (PLD)-CeO/sub 2//ion beam assisted (IBAD)-Gd/sub 2/Zr/sub 2/O/sub 7//Ni-based alloy substrate by an MOCVD technique, and approximately 4 /spl mu/m Ag was sputtered on it as a protective layer. The thickness of each layer was approximately 1.0 /spl mu/m, 1.0 /spl mu/m and 0.1 mm respectively. Its critical current was about 50 A. The mechanical properties of YBaCuO tape formed on Ni-based alloy substrates with a CeO/sub 2//Gd/sub 2/Zr/sub 2/O/sub 7/ buffer layer will be described. Tensile or compressive bend stress tests were conducted, and normalized critical current and the value n were evaluated. The degradation of its critical current was confirmed not to be in the big problem level in manufacturing applications. In addition, the surfaces of YBaCuO layers were observed by scanning electron microscopy and no crack was observed on them. Next, axial tensile stress tests were conducted and the YBaCuO tape was compared with biaxially textured Ni-3at.%W alloy substrates and YBaCuO layers on Ag substrates. Axial tensile stress characteristics of the YBaCuO tape were confirmed to be much higher than others. The YBaCuO tape was confirmed to have adequate axial tensile stress characteristics for designing a coil which can tolerate electromagnetic force.         Effect of mechanical loading on the I/sub c/ degradation behavior of Bi-2223 tapes    C.A. Baldan, C.Y. Shigue, E.R. Filho and U.R. Oliveira Summary: During the winding process of HTS coils the tapes of Bi-2223 are subjected to the influence of bending strain, axial strain, compressive force and torsional deformation resulting in I/sub c/ degradation. In the literature the effects of the individual strain components are separately analyzed in spite of during coil winding and energizing the strain-stress effects are combined. In this work using commercial tapes of Bi-2223 Ag/AgMg with and without stainless steel reinforcement several samples were wound on cylindrical FRP G-10 holder in which different combined strains are applied. Measurements of I-V characteristic curves are done to determine the degree of critical current degradation and the operational limits. The results are compared with the I/sub c/ values of short samples and other specimens subjected to deformation generated by loading types such as tensile and bending strain.         Fatigue behavior and its influence on the critical current of externally reinforced Bi-2223 superconducting tape    Hyung-Seop Shin, J.R.C. Dizon, Ki-Hyun Kim, Sang-Soo Oh and Dong-Woo Ha Summary: The endurance evaluation of HTS conductors for practical applications is necessary. The mechanical properties and the critical current, I/sub c/, of multifilamentary Bi-2223 superconducting tapes, externally reinforced with stainless steel foils, subjected to high cycle fatigue loading in the longitudinal direction were investigated at 77 K. The relations between the applied stress amplitude and the fatigue life (S-N curves) were obtained using the externally reinforced Bi-2223 tapes, and its transport property was evaluated with the increase of repeated cycles at different stress amplitudes. The effect of the stress ratio, R, on the I/sub c/ degradation behavior under fatigue loading was also examined considering the practical application situation of HTS tapes. Microstructure observation was performed in order to understand the I/sub c/ degradation mechanism in fatigued Bi-2223 tapes.         Compressive pre-strain in high-niobium-fraction Nb/sub 3/Sn superconductors    J.W. Ekin, N. Cheggour, M. Abrecht, C. Clickner, M. Field, Seung Hong, J. Parrell and Youzhu Zhang Summary: Multifilamentary Nb/sub 3/Sn superconducting strands fabricated with high niobium fractions have exceptionally high critical-current densities but are sometimes marginally stable during testing. We report a technique for determining the pre-strain in such conductors, in which additional stabilizing copper is electroplated onto the conductor and the pre-strain is determined by extrapolation to the as-fabricated niobium fraction. This technique is used to measure the pre-strain in conductors with high niobium fractions of 20% to 30%. Values of the pre-strain /spl epsiv//sub max/ in these conductors are reduced to the range 0.1% to 0.2%, which is significantly less than the /spl epsiv//sub max/ values of 0.2% to 0.4% in traditional bronze-process Nb/sub 3/Sn conductors (where niobium fractions are typically about 10% to 15%). However, including about 20% dispersion-strengthened copper into the conductor matrix restores /spl epsiv//sub max/ to the range 0.25% to 0.35%, thus providing practical levels of /spl epsiv//sub max/ for magnet design in high-niobium-fraction strands.         Large T/sub c/, B/sub c2/ and I/sub c/ enhancement effect due to the prebending treatment for bronze route Nb/sub 3/Sn wires    K. Watanabe, S. Awaji, H. Oguro, G. Nishijima, K. Miyoshi and S. Meguro Summary: In order to develop a react-and-wind (R&W) processed Nb/sub 3/Sn superconducting magnet, we investigated the influence on the superconducting properties due to the prebending treatment. Since a reacted Nb/sub 3/Sn superconducting wire reveals a very sensitive response from stress and strain, we focus on the prebending treatment which is repeatedly applied to the Nb/sub 3/Sn wire through several pulleys in the R&W coil winding process. We found that the prebending treatment doubles the I/sub c/ value at 20 T and 4.2 K for bronze route Nb/sub 3/Sn wires. This I/sub c/ enhancement effect comes from the T/sub c/ and B/sub c2/ enhancement. It turned out that T/sub c/ increases from 17.4 to 17.9 K and as a result B/sub c2/ also increases from 23.7 to 25.2 T at 4.5 K for bronze route multifilamentary Nb/sub 3/Sn wires prebent at bending strain of 1.0% and at 5 repeated times.         Deformation behavior of Nb/sub 3/Sn type superconductors    J. Chen, Ke Han, P.N. Kalu and W.D. Markiewicz Summary: Commercially available Nb/sub 3/Sn type superconductors have at least four components with different shear modulus /spl mu/. All the components are polycrystalline and therefore the yield stress in shear is of order /spl mu//500. The materials are subject to both thermal and mechanical stresses when in service. The stress levels can be well beyond the yield stress of the materials and therefore plastic flow occurs in selected components, such as Cu stabilizer and Cu-Sn matrix. Because deformation occurs at cryogenic temperatures and limited dynamic recover occurs, a high density of dislocations are accumulated. If the plastic deformation is large, deformation may be accommodated by twinning. The change of the deformation mechanisms will alter the strain-hardening rate and has an impact on the material properties. On the other hand, change of the microstructure can influence the plastic deformation behavior so that materials can be strengthened. This paper will first address the strain-hardening behavior of various components separately and then Nb/sub 3/Sn superconductor composites. A semi-empirical model is introduced to address the possible practical strengthening approaches for Nb/sub 3/Sn type superconductors.         Modeling of the effect of Nb/sub 3/Sn strand composition on thermal strains and superconducting performance    N. Mitchell Summary: The effect of applied and thermal strain on the superconducting performance of Nb/sub 3/Sn strands is well known. Prediction of the strand performance depends on an accurate knowledge of the strand strain state. As well as operating strains due to mechanical loads on the conductor, the strand has a complex system of internal strains due to the fabrication process and partial annealing at the reaction heat treatment temperature (about 600 C). Nb/sub 3/Sn strands are now available with a range of different matrices around the superconducting filaments, varying both in mechanical properties and geometry. Starting from a database of mechanical properties, this paper will use finite element analysis to model the elasto-plastic behavior of the matrix, predicting the filament multi-axial strain state.         Magnetic-field dependence of the reversible axial-strain effect in Y-Ba-Cu-O coated conductors    N. Cheggour, J.W. Ekin and C.L.H. Thieme Summary: The critical-current density J/sub c/ of an yttrium-barium-copper-oxide (YBCO) coated conductor deposited on a biaxially-textured Ni-5at.%W substrate was measured at 76.5 K as a function of axial tensile strain /spl epsiv/ and magnetic field B applied parallel to the YBCO (a,b) plane. Reversibility of J/sub c/ with strain was observed up to /spl epsiv//spl sime/0.6% over the entire field range studied (from 0.05 to 16.5 T), which confirms the existence of an intrinsic strain effect in YBCO coated conductors. J/sub c/ vs. /spl epsiv/ depends strongly on magnetic field. The decrease of J/sub c/(/spl epsiv/) grows systematically with magnetic field above 2-3 T, and, unexpectedly, the reverse happens below 2 T as this decrease shrinks with increasing field. The pinning force density F/sub p/=J/sub c//spl times/B scaled with field for all values of strain applied, which shows that F/sub p/ can be written as K(T,/spl epsiv/)b/sup p/(1-b)/sup q/, where p and q are constants, K is a function of temperature and strain, b=B/B/sub c2//sup */ is the reduced magnetic field, and B/sub c2//sup */ is the effective upper critical field at which F/sub p/(B) extrapolates to zero.         Reversible strain dependence of critical current in 100 a class coated conductors    M. Sugano, K. Osamura, W. Prusseit, R. Semerad, T. Kuroda, K. Itoh and T. Kiyoshi Summary: The strain dependence of the critical current was studied for YBCO and DyBCO coated conductors with different buffer layers on Hastelloy substrates. A maximum of I/sub c/ was observed for both the YBCO and DyBCO tapes, however the sign of the strain at the I/sub c/ peak was opposite for the two superconductors. A reversible variation of I/sub c/ with applied strain was found and the reversible strain limit was observed to depend on the buffer layer. For the IBAD-CeO/sub 2//YSZ buffered YBCO tapes, I/sub c/ recovers reversibly when the applied strain is reduced starting from 0.30%. For those with an ISD-MgO buffer layer the irreversible degradation starts at a strain less than 0.22%. The reason for this difference is discussed based on microscopic observations. Quenching occurred during V-I measurements after the applied strain exceeded 0.30%, which is close to the yield strain of the composite tape.         Nanohardness and crack resistance of HTS YBCO thin films    A. Verdyan, Y.M. Soifer, J. Azoulay, E. Rabkin and M. Kazakevich Summary: Nanoindentation and nanoscratching using atomic force microscope (AFM) were employed to study the local mechanical properties of high TC superconductors YBCO thin films featuring high critical current density. Two YBCO films sputtered on two different substrates featuring substantial different hardness and Young's modules (sapphire and SrTiO3) were studied. The microstructure and the mechanical properties such as hardness (H), Young's modulus (E) and scratch parameters were investigated. The intrinsic hardness and Young's modulus of YBCO thin films were found to be H /spl sim/ 8.5 GPa, and E /spl sim/ 210 GPa, respectively. The substrate's influences on the mechanical parameters were found to be insignificant as long as the indentation penetration depth was below approximately 25% of the film thickness.         Temperature dependence of intermodulation distortion in YBCO: understanding nonlinearity    D.E. Oates, S.-H. Park, D. Agassi, G. Koren and K. Irgmaier Summary: Intermodulation distortion (IMD) in high-T/sub c/ superconductor (HTS) devices continues to be important, and a complete understanding is lacking. We have measured the third-order IMD vs power as a function of temperature from 1.7 K to T/sub c/ for YBCO films of several fabrication methods on lanthanum aluminate and sapphire. The measurements used a stripline resonator at either 1.5 GHz or 2.3 GHz depending on the substrate. The results show increasing IMD with decreasing temperature at low power levels. The IMD diverges nearly as 1/T/sup 2/ for temperatures below 5 K. This temperature and power dependence of the IMD is an observation of the nonlinear Meissner effect that has been predicted for superconductors with d-wave symmetry but has not been previously observed. The results agree with a rigorous, many-body calculation that yields directly the lowest-order correction of the nonlinear penetration depth as a function of the current. We discuss the role of intrinsic and extrinsic properties in the IMD. We also discuss the implications for practical devices operated at usual cryocooler temperatures.         Investigation into microwave power dependence of high quality Tl-1223 thin films on LSAT substrate    M.V. Jacob, A. Sundaresan, J. Mazierska and Y. Tanaka Summary: The microwave power dependence of high quality Tl(Ba,Sr)/sub 2/Ca/sub 2/Cu/sub 3/O/sub y/ thin films grown on 1'' diameter LSAT substrates using the Amorphous Phase Epitaxy method has been investigated in this paper. We have performed surface resistance (R/sub S/) measurements of Tl-1223 thin films on LSAT using the Hakki-Coleman sapphire dielectric resonator technique in the temperature range 15-94 K. High accuracy in measurements was achieved by using the multi-frequency Transmission Mode Q-Factor Technique. The Tl-1223 films exhibited low surface resistance comparable to YBCO films. When RF power levels were increased the onset of nonlinearity was observed at 0 dBm for all measured temperatures (17, 50, 70 and 84 K).         Effects of grain boundaries on microwave surface resistance of superconducting films    Y. Mawatari Summary: Microwave surface resistance of superconducting films with grain boundaries (GBs) is theoretically investigated as the functions of the critical current density J/sub cj/ at GB junctions and of the film thickness d. The two-fluid model is used for electrical current in the grains, whereas the Josephson-junction model is adopted for tunneling current across GBs. Theoretical expressions of the surface resistance R/sub sf/ are obtained not only for weakly coupled GBs with small J/sub cj/ but also for strongly coupled GBs with large J/sub cj/. The results show that R/sub sf/ nonmonotonically depends on the critical current density J/sub cj/ at GB junctions, and R/sub sf/ of superconductors with GBs can be smaller than the surface resistance for ideal homogeneous superconductors without GB. The R/sub sf/ is proportional to 1/d for thin films of d/spl Lt/d/sub cr/ and R/sub sf/ is independent of d for thick slabs of d/spl Gt/d/sub cr/, where the crossover thickness d/sub cr/ is much larger than 2/spl lambda/ (where /spl lambda/ is the London penetration depth) for weakly coupled GBs.         Effects of non-uniform columnar defect distribution on the microwave properties of Y-Ba-Cu-O coplanar resonators    G. Ghigo, L. Gozzelino, F. Laviano, D. Andreone and E. Mezzetti Summary: This paper reports on nonuniform heavy ion irradiations of YBCO coplanar resonators aimed at controlling vortex-induced microwave dissipation and nonlinearity. The adopted moving-target irradiation technique allows producing tailored profiles of columnar defect density to get an optimal compromise between defect-induced enhancement of vortex pinning and addition of dissipative scattering. The same samples were characterized before and after irradiation in order to evaluate the surface impedance, by means of data analysis suitable to account also for the substrate properties. In the case of the modulated dose profile, matching the fundamental-mode field distribution along the resonator, the onset of nonlinearity is shifted toward higher circulating power, without increasing dissipation. Finally, the possibility to locally modify by irradiation the properties of the material to obtain the confinement of external perturbations, while maintaining the current continuity throughout the whole device, has been preliminarily tested.         A current-density scale for characterizing nonlinearity in high-T/sub c/ superconductors    K.T. Leong, J.C. Booth and S.A. Schima Summary: In this paper, we characterize microwave nonlinearity in a high temperature superconducting (HTS) thin-film by measuring a geometry-independent current-density scale j/sub o/. The quantity j/sub o/ specifies the strength of a material-dependent nonlinearity, and can be used to calculate the nonlinear microwave response of planar superconducting transmission-line devices. Our procedure for determining j/sub o/ involves microwave measurements on superconducting coplanar waveguide devices patterned onto the HTS sample. In a YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) sample, we obtained a maximum experimental value for j/sub o/ of approximately 3.26/spl times/10/sup 8/ A/cm/sup 2/ at 25 K. From the measured temperature-dependence of j/sub o/ in our YBCO sample, and assuming a theoretical pair-breaking current density j/sub c/ equal to 3/spl times/10/sup 8/ A/cm/sup 2/, we calculated the temperature dependence of the quasiparticle factor b(T). The curve of the experimentally obtained b(T) matched well with a theoretically-predicted behavior in the scenario of d-wave symmetry in the superconducting order parameter.         Nonlinearity in the microwave properties of MgB/sub 2/ thin films: power dependence and intermodulation distortion    A. Andreone, M. Aurino, G. Cifariello, E. Di Gennaro, G. Lamura, P. Orgiani, R. Vaglio and X.X. Xi Summary: We present here measurements carried out by using a dielectrically loaded copper cavity operating at 7 GHz on MgB/sub 2/ thin films synthesized by hybrid physical-chemical vapor deposition. Microwave data on samples having critical temperatures above 41 K, very low resistivity values, and residual resistivity ratio between 15 and 17, are presented. The dependence of the nonlinear surface losses and of the third order intermodulation products on the power feeding the cavity is analyzed, with the aim of shedding a light on the primary dissipation mechanisms. At low power, data from both power dependence and third order products seem to indicate that we are observing a nonlinear response which is inherent to the conventional s-wave nature of this novel compound. At intermediate-to-high circulating power values, vortex penetration appears to be the limiting mechanism for the power handling capability of MgB/sub 2/ films.         Unexpected effect of field angle in magnetoresistance measurements of high-purity Nb    L.F. Goodrich, T.C. Stauffer, J.D. Splett and D.F. Vecchia Summary: We report on unexpected field-angle dependence of magnetoresistance measurements of commercial, high-purity Nb discovered during our study of residual resistivity ratio (RRR) measurements. The RRR value indicates the purity and the low-temperature thermal conductivity of the Nb and is used as a specification for superconducting radio-frequency cavities. The RRR is typically defined as the ratio of the electrical resistivities measured at 273 K and 4.2 K. One way to obtain the normal-state resistivity at 4.2 K is to measure the resistivity versus magnetic field at 4.2 K and extrapolate to zero field. The field-angle dependence was measured when a specimen was rotated while the field was transverse to the specimen current. The resistance changed by about 10% as the angle varied at 8 T and the local maxima and minima of the resistance were separated by about 30/spl deg/. This was observed on three polycrystalline Nb bar specimens with nominal dimensions of 64 mm /spl times/ 6.7 mm /spl times/ 3.3 mm and voltage taps separated by 30 mm. A similar field-angle dependence was obtained on a polycrystalline Cu wire specimen. This phenomenon has implications for Nb RRR measurements and interlaboratory comparisons.         Development of a low-temperature electro-mechanical testing device    A.L. Mbaruku, U.P. Trociewitz and J. Schwartz Summary: Understanding the strain-sensitivity of high temperature superconductors is important for the development of applications. Conductors for magnets experience mechanical loads during all stages of manufacturing and thermal cycling, as well as Lorentz force induced loads during operation. Thus, it is important to study the effects of mechanical loads on HTS conductors in the presence of magnetic field. Here we report on the development of a tensile testing device that was designed to characterize the in-field electromechanical behavior of HTS conductors. The device is capable of applying tension or compression, controlled fatigue cycles, and in-situ transport critical current measurements. We report on the development and capabilities of the device, as well as the initial stress-strain results at room temperature.         Numerical investigations on relation between critical current density and third harmonic voltage in HTS    A. Kamitani, S. Ikuno and T. Yokono Summary: The inductive method for measuring the critical current density is investigated by using the numerical simulation. When the high-temperature superconductor is exposed to the magnetic field generated by the ac coil current, the voltage induced in the coil contains not only a linear component but higher harmonics. The harmonic voltages are numerically calculated as a function of the coil current. The results of computations show that, above a certain limit of the coil current, the third harmonic voltage is suddenly excited. In addition, it is also found that the square root of the third harmonic voltage is approximately a linear function of the coil current.         Indirect measurement of AC current distributions in a Bi-2223 solenoidal coil by a pickup coil method    S. Kawabata and T. Fukushima Summary: In order to investigate AC current distributions in high Tc superconducting (HTS) coils, we have developed a measurement method to evaluate the current distributions in a HTS solenoidal coil. In this method, the current distributions are indirectly found from the results of the field distributions measured by pickup coils located around the sample coil surface. To confirm the accuracy and sensitivity of this method, current distributions in a test coil made of insulated copper wires are measured. Numerical and measured field distributions are compared, and it is found that our method is accurate enough to measure the current distributions for the HTS coils. Using this method, we measured the current distributions in a Bi-2223 solenoidal coil at room temperature and 77 K. The comparison between the experimental and numerical results shows that the current distributions in the HTS coil are not uniform. On the basis of the obtained results, the characteristics of the AC current distributions in the HTS coils are discussed.         Critical current determination of artificially welded HTS samples by in-field Hall mapping technique    X. Granados, B. Bozzo, S. Iliescu, E. Bartolome, T. Puig, X. Obradors, J. Amoros and M. Carrera Summary: The direct observation of the magnetic field at the surface of SC samples when the field is applied or in the remanent state, allows the observation of the current distribution along the magnetization loop by using inverse problem solvers. Furthermore, the mean value of the field reflects well the magnetization of the sample obtaining the magnetization loop taken in account both possibilities, the In-Field Hall Mapping technique, thus, has revealed as a powerful characterization technique. This technique can be improved by including the critical state simulation, giving so a very complete way to characterize artificially welded superconducting samples, thus allowing the identification of the critical current flowing through the surface between domains as is the case of the effect of welded bulks. Some examples of the characterization procedures are reported.         Precise determination of the threshold current for third-harmonic voltage generation in the ac inductive measurement of critical current densities of superconducting thin films    H. Yamasaki, Y. Mawatari and Y. Nakagawa Summary: In an ac inductive method to measure critical current densities J/sub c/ of superconducting films by detecting third-harmonic voltages V/sub 3/ cos 3/spl omega/t, ac magnetic fields are generated with ac currents I/sub 0/ cos /spl omega/t in a small coil mounted just above the film. J/sub c/ is calculated from the threshold coil current I/sub th/, at which full penetration of magnetic field is achieved and V/sub 3/ starts to emerge. For convenience, I/sub th/ has been usually determined by a constant-voltage criterion, e.g., V/sub 3///spl radic/2 = 50 /spl mu/V. However, V/sub 3/ is proportional to I/sub th/, and the determination of I/sub th/ by the constant-voltage criterion inherently causes a systematic error. We confirmed this by comparing the obtained J/sub c/ with those obtained from dc magnetization and by a transport method. We propose to use a constant-resistance criterion, such as V/sub 3//I/sub 0/ = 2 m/spl Omega/, as an alternative method to determine I/sub th/ accurately.         Spatial inhomogeneities of Gd-Ba-Cu-O bulk superconductors evaluated by different Hall probe scanning methods    T. Kono, N. Sakai, S. Nariki, I. Hirabayashi, M. Murakami and N. Koshizuka Summary: We studied spatial inhomogeneities of Gd-Ba-Cu-O bulk superconductors by using two different types of Hall probe scanning methods. One is a conventional scanning Hall probe (SHP) method, which can measure the trapped flux density distribution of superconductors after magnetized by external fields. The other is a recently developed magneto-scan method, which scans a Hall probe together with a permanent magnet and can detect shielding behavior of the sample surface without applying an external field. In the SHP method, the flux density distributions obtained by the field cooling (FC) scan were compared with those in the zero field cooling (ZFC) scan. It was found that the ZFC scan can acquire much more information on the sample inhomogeneity than the FC scan. The magneto-scan method was also adopted to the characterization of the same sample. It was found that this method was more sensitive than the SHP method, and allowed us to clearly detect some degradations in the vicinity of the seed crystal in the sample surface.         Dynamic field mapping for obtaining the current distribution in high-temperature superconducting tapes    B. Dutoit, J. Duron, S. Stavrev and F. Grilli Summary: The magnetic field profile on the surface of Bi-2223/Ag tapes has been dynamically measured across the width of the samples. The experimental technique uses a Hall-probe array with 7 sensors connected to a multiple channel lock-in amplifier especially programmed for fast and synchronous data acquisition measurements. The speed of the system is high enough to measure real-time profiles with 7 probes and 50 Hz sine current through the sample. A numerical method to estimate the current distribution inside the tapes using the measured field profile data is proposed. The inverse problem has been solved using certain assumptions on the current distribution in the superconductor. Validation of the results has been done by comparison with finite element method simulations.         Quench propagation ignition using single-mode diode laser    F. Trillaud, F. Ayela, A. Devred, M. Fratini, D. Leboeuf and P. Tixador Summary: The stability of NbTi-based multifilamentary composite wires subjected to local heat disturbances of short durations is studied in pool boiling helium conditions. A new type of heater is being developed to characterize the superconducting to normal state transition. It relies on a single-mode Diode Laser with an optical fiber illuminating the wire surface. This first paper focuses mainly on the feasibility of this new heater technology and eventually discusses the difficulties related to it. A small overview of Diode Lasers and optical fibers revolving around our application is given. Then, we describe the experimental setup, and present some recorded voltage traces of transition and recovery processes. In addition, we present also some energy and Normal Zone Propagation Velocity data and we outline ameliorations that will be done to the system.         Critical current vs. Strain for LTS wires up to 21 T    D. Uglietti, B. Seeber, V. Abacherli, N. Banno and R. Flukiger Summary: We have developed a device for the electro-mechanical characterization of long high current technical LTS wires and tapes up to 21 T. Our device is based on the concept of the Walters spring (WASP), which allows us to measure long length wires (up to 80 cm) and to obtain an absolute measurement of the strain value. The long length of the conductors allowed us to measure the V-I relation under strain over three decades of electric field (down to 0.01 /spl mu/V/cm) with currents up to 1000 A. This constitutes a progress in view of the characterization of the conductors for NMR applications at high field, which must operate in persistent mode. We report on I/sub c/ vs. strain measurements at fields up to 21 T for various types of Nb/sub 3/Sn wires prepared by different techniques (industrial wires as well as wires prepared in our laboratory) and for a copper cladded Nb/sub 3/Al wire, prepared at NIMS (Tsukuba). We show that the new, sharper criterion gives a new insight on the reversible behavior of the I vs. strain curve as well as of the variation of the exponential n factor under uniaxial tensile strain. The results on Nb/sub 3/Sn are analyzed in the context of the scaling laws proposed by J. Ekin.         Low temperature scanning laser microscopy of YBCO coated IBAD tapes    T. Kiss, M. Inoue, M. Yasunaga, H. Tokutomi, Y. Iijima, K. Kakimoto, T. Saitoh, Y. Tokunaga, T. Izumi and Y. Shiohara Summary: Spatially resolved measurements of dissipative state in YBCO coated conductors have been carried out by use of the low temperature scanning laser microscopy (LTSLM). It has been shown that the current dependent dissipation peak is well scaled by the Gaussian distribution, and its normalized distribution becomes narrower in inversely proportion to the square root of power index in the local current-voltage characteristic. From the LTSLM analysis, we can collect positional information of current limiting coordinate as well as spatial variation of local critical current. Optimizing the measurement condition, we also succeeded to visualize the dissipation even in the tape which is covered by a 10 /spl mu/m thick Ag stabilization layer.         Measurement of AC profiles of magnetic field above HTSc tape using Hall probe technique with help of DAQ cards and triggering    L. Frolek and E. Demencik Summary: Power applications of superconductors, such as transformers, power cables, motors, and generators require the study of the influence of AC magnetic fields on properties of high-temperature superconductors. Our contribution comprises a convenient method for a measurement of components of magnetic fields generated by induced currents circulating in a HTSc sample located in an AC magnetic field. Also, a data acquisition system is presented that allows for the measurement of signal proportional to the position and to the component of magnetic flux density by a Hall probe at a defined level of an applied magnetic field in each period simultaneously with the help of triggering. This differential Hall measurement enables us to acquire magnetic field profiles or maps in the vicinity of the sample corresponding to a certain value of the magnetic field applied. It is possible to obtain results for any value of the magnetic field applied in the course of the period, i.e. from zero up to a maximum value of the magnetic field at the rising or falling slopes according to trigger conditions. In particular, it can be used to investigate the current distribution in the sample during the AC cycle or defect detection in HTSc tapes.         The surface charge on coated superconductors carrying transport current    W.J. Carr Jr. Summary: A careful solution of Maxwell's equations for the case of a circuit carrying a forced transport current in zero applied magnetic field shows that the current in the circuit is not divergenceless. A small component of the current diverges into the surface leading to a surface charge. This current along with the surface charge it produces is computed for two parallel strips of coated conductor with one strip acting as the return path for the other. Although the component of current with divergence is too small to be of much importance for the vector potential, it is completely responsible for the surface charge and scalar potential.         Measurements of temperature dependence of partial discharge in air gaps between insulated Bi-Sr-Ca-Cu-O tapes    R. Grabovickic, D.R. James, I. Sauers, A.R. Ellis, P.C. Irwin, K. Weeber, L. Li and A.D. Gadre Summary: Partial discharge (PD) in trapped air-filled gaps between two adjacent insulated high temperature superconducting (HTS) tapes made of Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ (BSCCO) was investigated experimentally. PD measurements were performed at several temperatures ranging from 295 K to 41 K. At each temperature a series of AC voltages of equal duration and increasing magnitude was applied to the inter-turn insulation until PD was initiated and observed on the insulation condition monitor ICM digital PD system. The PD data are presented in the form of phase and amplitude resolved PD (PRPD) patterns. The voltage at which PD initiation (PDIV) and extinction (PVEV) is observed at a particular temperature was measured on an oscilloscope. Experimentally obtained PDIV and PDEV values are compared with the Paschen curve values for air and the effect of temperature on PDIV is discussed. The data show that relatively low PD onsets can occur even when the insulation is cooled to the 40 to 50 K range which may be due to the presence of ice layers on the surface of the voids.         Detection of hermetic defects in HTS wire    N. Long, N. Ross, A. Otto and S. Fleshler Summary: There are important applications of HTS in which the wire comes into direct contact with liquid coolants. If the coolant penetrates into the wire filaments through small leakage paths then a catastrophic failure may result upon warming of the wire as the liquid rapidly expands into a gas. It is therefore desirable to have a simple nondestructive test for hermeticity of long lengths of tapes. A number of tests for detecting hermetic defects with an emphasis on their feasibility within a manufacturing context are considered. The most promising technique is a colormetric test using ammonia as a tracer gas. We correlate results from colormetric tests with pressurized liquid nitrogen testing.         Investigation of current percolation characteristics in coated conductors    L.B. Wang, G. You, K.R. Barraca, K. Waller, J.M. Mahoney, J.L. Young and C. Kwon Summary: The IBAD and RABiTS coated conductors are investigated by variable temperature scanning laser microscopy (VTSLM). In 50 /spl mu/m scanning step images, IBAD samples appear to have more uniform current distribution than RABiTS samples, which can be related to the smaller grain sizes in IBAD. The images of IBAD samples taken with higher resolution reveal feather-like clusters with 40-150 /spl mu/m in diameter. In RABiTS, the shape and size of percolation clusters are clear and do not change between high and low resolution images, and they are estimated to be 50-150 /spl mu/m. VTSLM images prove that the current percolation in the transition region is due to the combination of the grain boundary network and the critical temperature variation. At the temperature below the critical temperature, the images of VTSLM show that the current bottleneck area causes the major local dissipation limiting I/sub c/. We also find that the dissipation areas have lower T/sub c//sup */ and high /spl delta/V/sub m/, an important characteristic shared among all the lower J/sub c//sup */ areas.         Analytical & numerical modelings of elliptical superconducting filament magnetization    T. Satiramatekul, F. Bouillault, A. Devred and L. Bottura Summary: This paper deals with the two-dimensional computation of magnetization in an elliptic superconducting filament by using numerical and analytical methods. The numerical results are obtained from the finite element method and by using Bean's model. This model is well adapted for Low T/sub c/ superconductor studies. We observe the effect of the axis ratio and of the field angle to the magnetic moment per unit length at saturation, and also to the cycle of magnetization. Moreover, the current density and the distribution of the electromagnetic fields in the superconducting filament are also studied.         Critical current degradation in HTS wires due to cyclic mechanical strain    D.T. Ryan, Liang Li, Xianrui Huang, J.W. Bray, E.T. Laskaris, K. Sivasubramaniam, A.D. Gadre, J.M. Fogarty, E.J. Harley, A. Otto and A. den Ouden Summary: HTS wires, which may be used in many devices such as magnets and rotating machines, may be subjected to mechanical strains from electromagnetic, thermal and centripetal forces. In some applications these strains will be repeated several thousand times during the lifetime of the device. We have measured critical current degradation due to repeated strain cycles for both compressive and tensile strains. Results for BSCCO-2223 HTS conductor samples are presented for strain values up to 0.5% and cycle numbers up to and beyond 10/sup 4/.         Shielding current density analysis of axisymmetric HTS by element-free Galerkin method    S. Ikuno and A. Kamitani Summary: The numerical method for shielding current density in axisymmetric high-T/sub c/ superconductors (HTS) applying the element-free Galerkin (EFG) method is presented. In the present study, the axisymmetric simulation code for analysing the time evolution of the shielding current density on HTS by using EFG is developed, and the shielding performances against the AC/DC-hybrid applied magnetic flux are evaluated by the code. The results of computations show that the shielding ability decreases as the applied magnetic flux of DC mode increases.         Dependence of surface resistance in HTS thin films on a DC magnetic field    A. Saito, M. Shirakawa, K. Kitamura, Y. Noguchi, M. Mukaida, H. Yamasaki, Y. Nakagawa and S. Ohshima Summary: We investigated the behavior of the surface resistance (R/sub s/) of high-temperature superconductor (HTS) thin films exposed to a dc magnetic field (parallel to the c-axis). Measurements were done using the dielectric resonator method and superconducting magnet system. The DyBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (DyBCO) and YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thin films (produced by THEVA GmbH) were prepared through a thermal co-evaporation method. The resonant frequency of the TE/sub 011/ mode in the resonator was approximately 22 GHz. A dc magnetic field of up to 5 T was applied vertically to two parallel superconducting thin films placed into a closed-type Cu cavity. R/sub s/ of the DyBCO and YBCO thin films increased as the applied dc magnetic field increased. The R/sub s/ ratio (defined as R/sub s/(5 T)/R/sub s/(0 T)) of the DyBCO and YBCO thin films at 4.5 K was approximately 5 and 50, respectively. These results indicate that the DyBCO thin film may be better for use in low-temperature nuclear magnetic resonance applications.         Relationship between surface resistance and critical current density of HTS thin films in a DC magnetic field    A. Saito, M. Shirakawa, K. Kitamura, Y. Noguchi, M. Mukaida, H. Yamasaki, Y. Nakagawa and S. Ohshima Summary: We investigated the relationship between the surface resistance (R/sub s/) and critical current density (J/sub c/) of DyBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (DyBCO) thin films in a dc magnetic field. The R/sub s/ of DyBCO films at 21.8 GHz was measured using a dielectric resonator method and the J/sub c/ was determined by magnetic measurement and Bean's model. A dc magnetic field of up to 5 T was applied along the c-axis of the films. The relationship between the R/sub s/ and J/sub c/ of DyBCO thin films under a zero magnetic field was explained by the following equation, R/sub s/=/spl alpha//spl times/10/sup 7//J/sub c/, where /spl alpha/ is a constant of 1.2, and the units of the R/sub s/ and J/sub c/ are ohm and A/m/sup 2/, respectively. In addition, the R/sub s/ in dc magnetic fields up to 5 T were inversely proportional to the J/sub c/. However, the parameter /spl alpha/, which was fitted from the R/sub s/-J/sub c/ characteristics in each magnetic field, increased slightly with an increase the magnitude of the applied field. These results indicate that the relationship between the R/sub s/ and J/sub c/ in a zero magnetic field may be a general property of HTS thin films and that the /spl alpha/ in DyBCO thin films depends on the magnitude of the applied magnetic field.         Accurate measurements of the intrinsic surface impedance of thin YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films using a modified two-tone resonator method    J.H. Lee, W.I. Yang, M.J. Kim, J.C. Booth, K. Leong, S. Schima, D. Rudman and Sang Young Lee Summary: We propose a modified two-tone method that could be used for sensitive measurements of the intrinsic microwave surface impedance (Z/sub S/) of thin superconductor films and the tan/spl delta/ of a low-loss dielectric. An open-gap resonator scheme is used to measure the penetration depth (/spl lambda/) of thin superconductor films and extract the intrinsic Z/sub S/ of the superconductor films from its measured R/sub S//sup eff/ and /spl lambda/. We use a very small gap of 10 /spl mu/m between the top plate and the rest parts of the resonator. The tan/spl delta/ of rutile in the low 10/sup -7/ range and the dielectric constant as high as /spl sim/110 are observed at temperatures below 10 K at /spl sim/15.2 GHz, which enable to measure the R/sub S/ of the 10 mm-in-diameter YBCO films as low as /spl sim/100 /spl mu//spl Omega/ at the same frequency (f). The discrepancy between the R/sub S//sup eff/ at /spl sim/15.2 GHz and that at /spl sim/8.5 GHz scaled to /spl sim/15.2 GHz appears less than 2% when the relations of R/sub S/ /spl prop/ f/sup 2/ and tan/spl delta/ /spl prop/ f are used. We describe usefulness of our measurement method for measuring the intrinsic microwave properties of various superconductor samples.         Effects of residual surface resistance on the microwave properties of YBCO thin films    A. Porch, D.W. Huish, A.V. Velichko, M.J. Lancaster, J.S. Abell, A. Perry and D.P. Almond Summary: The performance of a planar microwave device fabricated from a YBCO thin film is strongly dependent on the quality and uniformity of the film. In this paper we present a full set of results of the microwave surface impedance at 8 GHz of three films deposited on MgO substrates and patterned into coplanar resonators. We use the Modulated Optical Reflectance (MOR) technique as a complementary, noncontacting, room temperature method of assessing the uniformity of the films. The three films studied have highly uniform MOR signals across the whole of their surfaces, indicative of thin films of very good electrical quality. However, although the measured Q factors of all three resonators are high, they vary significantly from 15000 to 30000 at 15 K, a result that is uncorrelated with the observed uniformity of the MOR signals. We interpret this variability as being due to residual surface resistance associated with microstructural defects that are impossible to detect using MOR. On subtracting the residual resistance we find that the intrinsic, linear microwave properties (i.e. quasiparticle conductivity /spl sigma//sub 1/ and penetration depth /spl lambda/) are very similar, consistent with the uniformity of the MOR signals.         RF properties of (RE)Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// (RE=Er, Ho, and Dy) superconducting thin films for wireless communications    L.S.-J. Peng and B.H. Moeckly Summary: We have grown and optimized several thin-film materials similar to YBCO, but with Y replaced by an alternative rare earth element. Because many of these elements sublime rather than melt readily, compositional control of these materials during deposition can be more difficult than for YBCO, which has a relatively wide process window. However, using the deposition technique of reactive coevaporation (RCE), we are able to grow high quality, epitaxial (RE)Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// films on 2''-diameter substrates. We will report on the growth conditions, crystal structure, and T/sub c/ values of these films. We will also discuss the Q values of lumped-element microwave resonators patterned from these films. We show that the excellent RF properties of our films make them suitable for use in wireless communications applications.         Microstructure and properties of groove-shaped artificial pinning centers introduced by microfabrication    N. Harada, Y. Goto, T. Yasuda, M. Tsuda and T. Hamajima Summary: Effective flux pinning centers are required for the development of practical superconductors in order to achieve high critical current density. In the case of metallic superconductors, a drawing process introduces artificial pinning centers in metallic superconductors. However, artificial pinning centers cannot be introduced into high-Tc superconductors through the drawing process because these superconductors are brittle. We consider the microfabrication technique, instead of the drawing process, in order to introduce artificial pinning centers into the superconductors. Groove-shaped artificial pinning centers are introduced into a 0.5 /spl mu/m thick evaporated Nb film on a sapphire substrate by photolithography. The groove-shaped pattern with a spacing of 4 /spl mu/m was introduced by etching on a 0.9 /spl times/ 0.9 mm region of the Nb film. Nb films with varying groove depths were prepared, and the groove depth dependence on critical current density was investigated for the width of the hysteresis curve of the magnetic moment. The hysteresis curves of the specimens with grooves were measured with a SQUID magnetometer. The width of the hysteresis curve decreases with an increasing groove depth for over 70% of the film thickness.         Microstructures of high-T/sub c/ superconducting films having artificial pinning centers    A. Ichinose, K. Matsumoto, M. Mukaida, Y. Yoshida, S. Horii and S. Akita Summary: REBa/sub 2/Cu/sub 3/O/sub y/ (REBCO) is expected to be used in numerous applications, such as power transmission cables, high-field magnets and generators, due to the possibility of a high critical current density at 77 K under a high magnetic field. Biaxially textured REBCO superconducting tapes are developed to obtain high-J/sub c/. However, the J/sub c/-B characteristics of REBa/sub 2/Cu/sub 3/O/sub y/ films have a magnetic field angle dependency. When the magnetic field is applied parallel to the film surface, the reduction in J/sub c/ is not larger under a high magnetic field of 10 T. When the magnetic field is applied perpendicular to the film surface, the reduction in J/sub c/ is significantly large under a magnetic field of more than around 5 T at 77 K. From the viewpoint of realizing wide applications of high-T/sub c/ superconductors, it is important to improve the J/sub c/-B characteristics of REBCO films under magnetic fields higher than 5 T applied perpendicular to the film surface. Our group focuses on artificial pinning centers (APCs) introduced into REBCO films. The J/sub c/-B characteristics of certain films are improved by the introduction of APCs. The microstructures of these films are investigated using transmission electron microscopy (TEM). We report on the microstructures of REBCO films with APCs.         Nd-doped YBa/sub 2/Cu/sub 3/O/sub 7-x/ films deposited by pulsed laser ablation    C.V. Varanasi, J.C. Tolliver, T.J. Haugan, S. Sathiraju, I. Maartense and P.N. Barnes Summary: Nd doped YBa/sub 2/Cu/sub 3/O/sub 7-x/ targets (Nd/sub x/Y/sub 1-x/Ba/sub 2/Cu/sub 3/O/sub 7-x/; x=0, 0.2, 0.4, 1) were prepared in-house and were used to deposit films by pulsed laser ablation in 300 mTorr of oxygen to study the Nd substitution effects on the film properties. Film composition was found to match very closely to the composition of the targets as determined from X-ray photoelectron spectroscopy. The critical transition temperature (T/sub c/) was found to be reduced as the Nd substitutions were increased in the films. Raman spectra taken from the films indicate that c-axis misalignment and some cation disorder may be present in the films with poor T/sub c/. Transport critical current density (J/sub c/) of 3/spl times/10/sup 6/ A/cm/sup 2/ was measured in Nd/sub 0.4/Y/sub 0.6/Ba/sub 2/Cu/sub 3/O/sub 7-x/ films.         Tb and Ce doped Y123 films processed by pulsed laser deposition    J.W. Kell, T.J. Haugan, M.F. Locke and P.N. Barnes Summary: To evaluate possible flux pinning enhancement in YBa/sub 2/Cu/sub 3/O/sub 7-z/ (Y123) films due to partial rare-earth ion substitutions, Ce and Tb doping are studied. Bulk ceramic targets of varying compositions (Y/sub 1-x/RE/sub x/Ba/sub 2/Cu/sub 3/O/sub 7-z/) were made with several doping levels (x=0.001 to 0.1, RE=Ce or Tb) by using regular solid-state reaction and sintering procedures. These targets were used to deposit Ce and Tb doped YBCO films onto SrTiO/sub 3/ single crystal substrates by pulsed laser ablation. Doped YBCO films were characterized for T/sub c/, magnetic field dependence of J/sub c/ (at 77 K), microstructure, and other properties. The results are compared to undoped YBCO films processed in similar manner.         Microstructure and field angle dependence of critical current densities in REBa/sub 2/Cu/sub 3/O/sub y/ thin films prepared by PLD method    Y. Ichino, R. Honda, M. Miura, M. Itoh, Y. Yoshida, Y. Takai, K. Matsumoto, M. Mukaida, A. Ichinose and S. Horii Summary: A c-axis oriented epitaxial REBa/sub 2/Cu/sub 3/O/sub y/ (RE123) thin film performs excellent superconducting properties in magnetic field. Recently, we reported that a critical current density (J/sub c/) in the RE123 thin film was improved by a deliberate composition control. A Sm/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub y/ (Sm123) thin film with a small amount of Sm/Ba substitution x showed the great J/sub c//spl sim/0.17 MA/cm/sup 2/ in 5 T at 77.3 K, while the J/sub c/ in (Yb/sub 1-z/Nd/sub z/)Ba/sub 2/Cu/sub 3/O/sub y/ (Yb/Nd123) thin films depended on an amount of mixed crystal ratio z. In this report, we studied J/sub c/ as a function of magnetic field and field orientation with respect to ab-planes. In low magnetic field, the J/sub c/ of Sm123 thin film was almost independent of the applied angle of the field. In the case of Yb/Nd123 thin film, extremely high J/sub c/ were observed when the magnetic field was aligned parallel or perpendicular to the surface of the film. Because compositional fluctuations in RE123 thin films were observed by transmission electron microscopy, we found that the pinning centers in RE123 thin films are strongly affected by the composition in the thin films.         Angular dependence of critical current density in Y-Ba-Cu-O thin films    T. Horide, K. Matsumoto, A. Ichinose, Y. Yoshida, S. Horii, M. Mukaida and K. Osamura Summary: c-axis oriented YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thin films for coated conductor applications have anisotropic behaviors of critical current density (J/sub c/) in magnetic fields. The anisotropic vortex pinning in YBCO films fabricated on SrTiO/sub 3/(100) single crystal substrates by pulsed laser deposition was investigated based on the field angular dependencies of J/sub c/, which were measured using the constant Lorentz force configuration (CLFC) and a variable Lorentz force configuration (VLFC). J/sub c/(/spl theta/) as a function of angle /spl theta/ between the ab-plane direction and the magnetic field direction had a sharp peak at /spl theta/=0/spl deg/, which was attributed to the intrinsic pinning. Besides, J/sub c/(/spl theta/) did not depend on the intensity of the Lorentz force when the magnetic field was applied near /spl theta/=90/spl deg/. This indicates that J/sub c/(/spl theta/) in this region is determined by the depinning of the vortex segment trapped by the pinning centers parallel to c-axis of the film. A transition from the intrinsic pinning to the extrinsic pinning is also discussed.         Anisotropic enhancement of flux pinning in mixed rare earth 123-type thin films    C. Cai, J. Hanisch, T. Gemming and B. Holzapfel Summary: By transport measurements, we demonstrate that critical current density and irreversibility field are improved in the mixed rare earth NEG123 films for both field directions of H/spl par/c and H/spl perp/c. Angular dependence of the enhanced flux pinning force at low temperature and field is characterized by two peaks at H/spl par/c and H/spl perp/c, respectively. This may be attributed to favorite distribution of stress fields in such two directions due to 2D lattice misfits. With increasing temperature and field, the strongest improvement of flux pinning take places only at the field perpendicular to the (a, b) plane where intrinsic flux pinning is absent, thus allowing the stress field, such an uncorrelated disorder, to be most effective by collective pinning behavior.         Effect of the particle size of micro-scale and nano-scale additions on the formation of compositional fluctuations in Sm-Ba-Cu-O material    Shih-Yun Chen, Chun-Chih Wang, In-Gann Chen and Maw-Kuen Wu Summary: Recently, many studies imply that the existence of field induced pinning centers, which include RE-rich clusters and compositional fluctuations, contribute to the flux pinning in high field regions. The mechanisms to introduce field induced pinning centers have been proposed for different single grained high T/sub c/ superconductor systems. Our previous studies indicated that the addition of nano-scale RE/sub 2/BaCuO/sub 5/ (RE211, RE: rare elements) form nano-sized compositional fluctuations during the melt-growth process and thus act as field induced pinning centers. It has been noted that samples with the addition of nano-Nd/sub 4/Ba/sub 2/Cu/sub 2/O/sub 10/ (Nd422) particles exhibit a higher J/sub c/-H performance than those with nano-Sm211 precursors, which were supposed to be the result of the different solubility, peritectic temperature, and atomic size of Nd compared to Sm. It is therefore believed that the optimum size of compositional fluctuations will be related to the diffusivities of RE elements, solubility, and the precursor particle size. In this study, Nd/sub 4/Ba/sub 2/Cu/sub 2/O/sub 10/ (Nd422) particles of two different sizes: micro scale and nano scale, were used to reveal the size effect. Different microstructures and J/sub c/-H performance were observed which are related to different reactions between the Nd422 additions and the 123 matrix during the melt-textured growth process.         Effect of Zr addition on the field dependence of transport J/sub c/ for filamentary (Nd/sub 0.33/Eu/sub 0.38/Gd/sub 0.28/)Ba/sub 2/Cu/sub 3/O/sub x/ superconductors    E. Sato, T. Goto, Y. Hirata and K. Watanabe Summary: We have studied the effect of Zr addition on the field dependence of transport J/sub c/ for filamentary (Nd-Eu-Gd)Ba/sub 2/Cu/sub 3/O/sub x/ superconductors to enhance the flux pinning. We prepared the filamentary (Nd/sub 0.33/Eu/sub 0.38/Gd/sub 0.28/)Ba/sub 2/Cu/sub 3/O/sub x/Zr/sub y/ (y=0, 0.001, 0.002) precursors by a solution spinning method. The precursor was partially melted in flowing 0.1%O/sub 2/+Ar under various heating conditions to obtain high J/sub c/ value. The optimum heating condition was dependent on sample diameter. A maximum J/sub c/ value of 3/spl times/10/sup 4/ A/cm/sup 2/ at 77 K and self-field was attained for the sample with 0.001 at% Zr. The samples had well aligned texture along the filament diameter as well as the length. The J/sub c/ was measured at 77 K in applied magnetic fields up to 14 T by rotating the sample along the direction perpendicular to the filament length. Anisotropic behavior of the field dependence of J/sub c/ was detected. Although the J/sub c/ values measured at the optimum angle for the samples with 0.001 at% Zr decreased with increasing the applied fields above 10 T, the J/sub c/ values for the Zr addition samples were higher than that for the non addition sample by applying the fields up to 11 T.         Vortex dynamics in percolative superconductors containing fractal clusters of a normal phase    Y.I. Kuzmin Summary: The effect of fractal clusters on magnetic and transport properties of percolative superconductors is studied. The superconductor contains percolative superconducting cluster carrying a transport current and clusters of a normal phase. It is found that normal phase clusters have essential fractal features. The fractal dimension of the boundary of normal phase clusters is estimated. The current-voltage (V-I) characteristics of superconductors containing fractal clusters are obtained. It is found that the fractality of the cluster boundary intensifies pinning. This feature permits to enhance the current-carrying capability of the superconductors.         A semi-quantitative method to analyze the complex pinning mechanisms in single-grained high-T/sub c/ superconductors    Shih-Yun Chen, In-Gann Chen and Maw-Kuen Wu Summary: To clarify the relationship between J/sub c/-H performance and microstructure, a determination of the flux pinning mechanism is necessary. However, multiple active pinning centers originating from different crystalline or chemical inhomogeneities may co-exist in most bulk high-T/sub c/ superconductors. This study presents a method to analyze the volume pinning forces of single-grained high-T/sub c/ superconductors with multiple additives (i.e. multiple pinning mechanisms) by means of the scaling theory of volume pinning force F/sub p/(H). The J/sub c/-H curves as well as F/sub p//F/sub p,max/ vs. h/sup p/(1-h)/sup q/ curves, where F/sub p,max/ is the maximum volume pinning force, h=H/H/sub irr/, and the parameters p and q depend on the characteristics of flux pinning can be divided into two parts with different pinning mechanisms, i.e. J/sub c/spl delta/Tc/ (/spl Delta//spl kappa/ pinning) and J/sub c/spl delta/l/ (normal pinning), respectively. By comparing the magnitude of the pinning force attributed to J/sub c/spl delta/Tc/ and J/sub c/spl delta/l/, respectively, a semi-quantitative description of complex pinning behavior of single-grained superconductors with multiple pinning mechanisms can be obtained. It is found that the dominant pinning mechanism of RE-Ba-Cu-O materials (REBCO, RE: Sm and Nd) with nano-scale 211 additions is /spl delta/T/sub c/ pinning, while those with CeO/sub 2/ and Pt/CeO/sub 2/ additions is /spl delta/l pinning. The relationship between these two pinning mechanisms with varying temperature and addition is also discussed.         Nonlinear magnetic diffusion in single-domain YBCO cylinders under pulsed field conditions    T.R. Askew, J.C. O'Daniel, J.M. Weber and Y.S. Cha Summary: A step-function increase in magnetic field has been applied to various single-domain Y-Ba-Cu-O rings and disks at 77 K. The magnetic field in the center of these structures exhibits an exponential approach to an equilibrium value, as predicted by simple diffusion theory. The measured time constants are in the millisecond range and show nonlinear behavior, as predicted in recently advanced theories of magnetic diffusion under flux flow conditions. Measurements of trapped magnetic field, critical current density, and current-voltage (I-V) characteristics are compared to results obtained by measurement of magnetic diffusion. The single-domain structures are intended for use in penetration-type fault current limiters, an application where the magnetic diffusion time constants have a strong influence on device design.         Effect of metal ring setting outside HTSC bulk disk on trapped field and temperature rise in pulse field magnetizing    H. Fujishiro, K. Yokoyama, M. Kaneyama, T. Oka and K. Noto Summary: In order to enhance the trapped field in cryo-cooled HTSC bulks using pulse field magnetizing (PFM), a metal ring (stainless steel 304 and/or Al) has been tightly set onto the SmBaCuO bulk disk and the relation between the total trapped flux /spl Phi//sub T//sup P/, the trapped field B/sub T//sup P/, and the temperature rise /spl Delta/T, has been investigated as a function of the applied pulse field B/sub ex/. The /spl Phi//sub T//sup P/ and B/sub T//sup P/ values are enhanced about 10 /spl sim/ 20% by the metal ring due to the reduction in the temperature rise /spl Delta/T. These results suggest that a part of the generated heat Q due to the flux motion in the peripheral region promptly transfers to the metal ring and the heat transfer to the cold stage is improved by the ring setting.         Pinning enhancement of YBa/sub 2/Cu/sub 3/O/sub 7-d/ thin films with Y/sub 2/BaCuO/sub 5/ nanoparticulates    P.N. Barnes, T.J. Haugan, M.D. Sumption and B.C. Harrison Summary: A comparison study is given of a typical superconducting YBa/sub 2/Cu/sub 3/O/sub 7-d/ (Y123) film and a Y123 film containing a nonsuperconducting Y/sub 2/BaCuO/sub 5/ (Y211) phase nanoparticulate dispersion. The inclusion of the second phase nanoparticulates was for the express purpose of increasing superconducting film's magnetic pinning strength with the resultant improved in-field critical current density. LaAlO/sub 3/ substrates were used and the Y123 and Y211 nanoparticulates were grown by pulsed laser deposition (PLD). The Y211 nanoparticulate dispersion in the Y123 resulted from multiple consecutive depositions by PLD of the respective targets. The Y123 phase maintained excellent epitaxy with high in-plane orientation with and without the Y211 inclusions. With the Y211 additions, the critical current densities of the films increased significantly in applied magnetic fields as compared to the high quality Y123 film with no Y211 additions.         Addition of alternate phase nanoparticle dispersions to enhance flux pinning of Y-Ba-Cu-O thin films    T.J. Haugan, P.N. Barnes, T.A. Campbell, J.M. Evans, J.W. Kell, L.B. Brunke, J.P. Murphy, C. Varanasi, I. Maartense, W. Wong-Ng and L.P. Cook Summary: Nanoparticle dispersions of various phases were added to YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO or 123) thin films by multilayer pulsed laser deposition, to determine their effect on flux pinning. The different pinning materials examined include Y/sub 2/BaCuO/sub 5/ (Y211 or green-phase), La/sub 2/BaCuO/sub 5/ (La211 or brown-phase), Y/sub 2/O/sub 3/, CeO/sub 2/, and MgO, with lattice constant mismatches varying from 0.5% to 12% with respect to YBCO. Y211 and Y/sub 2/O/sub 3/ provided significant pinning increases at temperatures of 65 K and 77 K, however other phases provided enhancements only at 65 K (for CeO/sub 2/ and La211) for limited range of applied field strengths. An interesting correlation between T/sub c/ transition widths and pinning strengths was observed. The additions produced markedly different nanoparticle and film microstructures, as well as superconducting properties.         J/sub c/ enhancement in YBa/sub 2/Cu/sub 3/O/sub x/ thin films by introduction of one-dimensional artificial pinning centers    K. Matsumoto, T. Horide, P. Mele, A. Ichinose, S. Horii, Y. Yoshida, M. Mukaida and K. Osamura Summary: A novel technology to introduce artificial pinning centers (APCs) into YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thin films prepared by pulsed laser deposition (PLD) was investigated for a drastic improvement of J/sub c/ in the films. Linear-like defects (one-dimensional APCs) were introduced perpendicular to the surface of the c-axis oriented films during the deposition process by using distributed Y/sub 2/O/sub 3/ nano-islands on substrates. The density of nano-islands was varied within 0.8-1.2/spl times/10/sup 10//cm/sup 2/ by PLD. A normalized resistivity as a function of temperature in magnetic fields shows a sharper resistivity drop for the film with APC, compared to pure YBCO film. J/sub c/ of the film with APC was also increased to 0.12 MA/cm/sup 2/ (77 K, B//c, 5 T), which was about two times higher than that of the pure YBCO film. The film had a very large J/sub c/ peak when the field was applied close to the c-axis. The peak J/sub c/ increased with the number density of Y/sub 2/O/sub 3/ nano-islands. This indicates that strong APCs parallel to the c-axis were incorporated into the YBCO film.         Generic positive effects of low level impurity doping on flux pinning properties of HTSC and MgB/sub 2/    J. Shimoyama, T. Maruyama, M. Shigemori, S. Uchida, S. Ueda, A. Yamamoto, Y. Katsura, S. Horii and K. Kishio Summary: Low level impurity doping effects on flux pinning properties have systematically studied for Bi(Pb)2212 single crystals, Y123 melt-solidified bulk and MgB/sub 2/ polycrystalline bulks. In all these systems, moderately dilute impurity doping was found to be effective for improving critical current properties without losing their original T/sub c/. For Bi(Pb)2212, iron, cobalt, nickel and yttrium were effective dopant for enhancement of J/sub c/ particularly under low fields. Second peak effect in J/sub c/-H properties of Y123 were observed in Sr doped Y123 bulk. These positive effects were happened only when mean distance of impurity ions was longer than the vortex core size, 2/spl xi//sub ab/. In the case of MgB/sub 2/, both aluminum doping for magnesium and carbon doping for boron improved J/sub c/ with their low doping levels less than 1%.         Transport characteristics in c-axis La/sub 2-x/Sr/sub x/CuO/sub 4/ (LSCO) single crystals    Sang-Jae Kim, T. Hatano, Gui-Sik Kim, T. Tachiki, I. Tanaka, Y. Takano, M. Tachiki and T. Yamashita Summary: c-axis micro-bridges of La/sub 2-x/Sr/sub x/CuO/sub 4/ (LSCO) single crystals were fabricated by the focused-ion-beam (FIB) etching method. Small rectangular LSCO pieces were fabricated by cutting and grinding single crystals of underdoped LSCO of x=0.09. The size of LSCO single crystals between electrodes was cut to (5-20)/spl times/40 /spl mu/m/sup 2/ in the ab-plane by using the FIB etching method. The junction resistance exhibited clear two-step structures corresponding to the superconducting transition of two different components of crystal structure. Superconductor-insulator-superconductor (SIS) like-branch structures on I-V curves of the LSCO stacks were observed for the first time. The branch structures show voltage jumps of several tens mV in the range of 2 K to 5 K with temperature dependence. When the temperature is changed from 2 K to 5 K, the critical current around zero bias regions splits into a few small voltage jumps with intervals of several mV in the range of 1 mV to 3 mV.         Mechanism of a high irreversibility field for (Nd, Eu, Gd)Ba/sub 2/Cu/sub 3/O/sub 7/ bulk    S. Awaji, N. Isono, K. Watanabe, M. Muralidhar, M. Murakami, N. Koshizuka and K. Noto Summary: In order to study the mechanism of the high irreversibility field, we measured the high field transport properties for bulk NEG123 samples with high irreversibility field. It was found that the Bose glass behavior is observed for both NEG123 bulk samples with 3% and 40% NEG211 additions. However, the 40%NEG211 sample with a low irreversibility field showed a higher effective matching field of the c-axis correlated disorder than the 3%NEG211 sample with a high irreversibility field. It is suggested that the c-axis correlation varies among samples and the strong correlation along the c-axis, which may arise from the alignment of the RE-rich NEG211 clusters, is important for the realization of the high irreversibility field.         Author Index (2004 - Part 3)    No author information available Summary: Not available         Upcoming Special Conference Issues (2004 - Part 3)    No author information available Summary: Not available

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