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2002 Part 3     Front Cover (2002 - Part 3)    No author information available Summary: Not available         Table of Contents (2002 - Part 3)    No author information available Summary: Not available         Progress and future prospects of research and development on coated conductors in Japan    T. Watanabe, Y. Shiohara and T. Izumi Summary: Second generation superconducting tape made of an REBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (RE-Ba-Cu-O) is expected to show improved magnetic field dependence and more economical production cost than that shown by the first generation one of Bi-compound tape. It consists of at least three layers: a metal layer, a buffer layer of some oxide, and a superconducting layer of RE-Ba-Cu-O. Therefore, it is called a "coated conductor." There are several choices of materials and processes when making a metal-buffer layer structure and the processing of the RE-Ba-Cu-O layer. The main difficulties in producing a long superconducting tape are that the RE-Ba-Cu-O layer grains must be in-plane aligned and any defects must not exist throughout the whole length of the tape. Several different processes to obtain the biaxially textured buffer layers or metal substrates, as well as nonvacuum process for deposition of superconducting layers and buffer layers, have been developed. At present, we have developed a coated conductor tape, 30 m in length and about 0.1 mm in thickness, by means of ion beam assisted deposition (IBAD) and pulsed laser deposition (PLD), with J/sub c/ of 0.79 MA/cm/sup 2/ at 77 K. This presentation will review the current status of R & D on coated conductors in Japan, which includes developments of textured metal substrates including surface-oxidation epitaxy, IBAD and inclined substrate deposition for a buffer layer, and PLD and metal organic deposition for the superconducting layer.         Large area YBCO-coated stainless steel tapes with high critical currents    A. Usoskin, H.C. Freyhardt, A. Issaev, J. Dzick, J. Knoke, M.P. Oomen, M. Leghissa and H.-W. Neumueller Summary: Recent progress in developing large area HTS-coated stainless steel tapes is reported. YBCO films have been grown on IBAD-YSZ buffered 0.1 mm-thick steel tapes using a high-rate pulsed-laser-deposition technique which allows a deposition rate up to 70 nm /spl middot/ m/sup 2//h. The coated conductors (CC) are provided with an optimized shunt layer and current contacts which reduce the generation of Joule's heat. An advanced technique for critical current I/sub c/ measurements was developed. The effects of self-field and time relaxation of current in helically wound tapes are analyzed. In long tapes of 10 m /spl times/ 4 mm, the highest I/sub c/ of 78 A at 77 K was observed. Critical currents of 67-75 A were reproducibly achieved in (8-10) m /spl times/ 4 mm coated tapes. For shorter tapes with a length of 0.2-1 m, critical currents of 317-391 A/cm width of the tape were observed. Fifteen wider CC tapes of 0.6 m /spl times/ 43 mm with I/sub c/ = 700 A have been manufactured and employed in newly developed fault current limiters with a nominal current of 3 kA. Critical current densities J/sub c/ = (1.3-2.5) MA/cm/sup 2/ at 77 K were observed in YBCO films. The CC tapes exhibit favorable behavior under axial stress and sufficiently small ac losses.         YBCO coated conductors by an MOD/RABiTS/spl trade/ process    M.W. Rupich, U. Schoop, D.T. Verebelyi, C. Thieme, W. Zhang, X. Li, T. Kodenkandath, N. Nguyen, E. Siegal, D. Buczek, J. Lynch, M. Jowett, E. Thompson, J.-S. Wang, J. Scudiere, A.P. Malozemoff, Q. Li, S. Annavarapu, S. Cui, L. Fritzemeier, B. Aldrich, C. Craven, F. Niu, R. Schwall, A. Goyal and M. Paranthaman Summary: Commercialization of YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) superconducting coated conductor composite (CCC) technology requires a cost-effective continuous manufacturing process. High critical current YBCO CCC wires with excellent uniformity over length have been fabricated using an all-continuous process. The conductor architecture consists of a metal organic derived YBCO layer, coated on a deformation-textured NiW alloy substrate buffered with Y/sub 2/O/sub 3//YSZ/CeO/sub 2/. Critical current at 77 K, self-field, of up to 118 A was achieved in 1 cm-wide tapes over 1.25 meter lengths, with a standard deviation of 3% measured on a 5 cm scale. The high uniformity and performance supports the feasibility of commercial long-length CCC wire based on deformation textured metal substrates and solution-based deposition of YBCO.         Development of HoBCO tapes fabricated by ISD process    K. Ohmatsu, K. Muranaka, T. Taneda, K. Fujino, H. Takei, N. Hobara, S. Honjo and Y. Takahashi Summary: Ho/sub 1/Ba/sub 2/Cu/sub 3/O/sub x/ (HoBCO) tapes by using pulsed laser deposition (PLD) have been developed on flexible Ni-alloy substrates. Inclined substrate deposition (ISD) was developed to introduce in-plane alignment for buffer layers. YSZ was deposited by PLD combined with ISD as a buffer layer on Ni-alloy tape. The advantage of ISD is a high growth rate due to the self in-plane alignment without any other assistance. This was demonstrated by using a CeO/sub 2/ buffer layer. A CeO/sub 2/ buffer layer shows high growth rates of 1 - 2 /spl mu/m/min. As for the growth rate of HoBCO, 4 /spl mu/m/min. was confirmed. Scale-up of the PLD system for making a long tape was performed. In this system, a 200 W-KrF excimer laser over 100 h continuous operation, a large deposition chamber including long ramp heater and three 10-in target system, and a reel to reel tape transfer system up to several hundred meters were introduced and combined. The continuous sputtering system for silver layer and O/sub 2/ annealing system were also introduced. By using these systems, a 50 m CeO/sub 2/ buffer was continuously deposited on a Ni-alloy tape. The deposition tape speed was 0.75 m/h, thickness was 2 /spl mu/m, and full-width at half-maximum was 23/spl deg/ in average. By depositing HoBCO on a part of this CeO/sub 2//Ni-alloy tape, Ic = 29 A/cm-width and Jc = 0.27 MA/cm/sup 2/ were demonstrated.         Fabrication and transport characteristics of long length Y-123 coated conductors processed by IBAD and PLD    Y. Iijima, K. Kakimoto and T. Saitoh Summary: Tapes of 30-m length high-J/sub c/ Y-123 were processed 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 60-m length were fabricated by IBAD with production speed of 0.5 - 1.0 m/h. Y-123 films were processed on them by PLD with production speed of 1.0 - 4.0 m/h. A 30-m Y-123 film was obtained with uniform thickness of 0.5 /spl mu/m and /spl Delta//spl phi/ of 8 - 11/spl deg/. I/sub c/ of 49 A (J/sub c/ = 0.99 MA/cm/sup 2/) was obtained in 10-m length part end-to-end, whose I-V curve had high n-value of 46. The 30-m length end-to-end I/sub c/ value was 40 A (J/sub c/ = 0.8 MA/cm/sup 2/), where I/sub c/ times length reached 1200 Am.         Microstructural and electrical characterization of gas cluster ion beam-smoothed YBCO films    M.S. Hatzistergos, H. Efstathiadis, E. Lifshin, A.E. Kaloyeros, J.L. Reeves, V. Selvamanickam, L.P. Allen and R. MacCrimmon Summary: The decrease in the critical current density (J/sub c/) of YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) films with increasing film thickness was investigated for 0.2 - 2.4-/spl mu/m-thick films grown on single crystal substrates. Microstructural and electrical properties were characterized by focused ion beam (FIB) microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy in a field emission scanning electron microscope, atomic force microscopy, and current-voltage measurements at 77 K in self-field. FIB cross sections directly showed that the top 30% -40% thickness of YBCO films contained pores, misoriented YBCO grains, and Ba-rich second phase particles that collectively produced a "dead top layer" which is believed to limit the J/sub c/ of YBCO films thicker than 1 /spl mu/m. A gas cluster ion beam etching and smoothing process partially removed the dead top layer and smoothed the film surface. In a 0.9-/spl mu/m-thick YBCO film, removal of a 0.22-/spl mu/m-thick dead layer yielded a 35% increase in J/sub c/ (up to 2.8 MA/cm/sup 2/) and a 25% decrease in film roughness. In a 1.3-/spl mu/m-thick YBCO film, removal of a 0.45-/spl mu/m-thick dead layer yielded an 85% increase in J/sub c/ (up to 1.1 MA/cm/sup 2/) and a 49% decrease in surface roughness. This study suggests that eliminating the dead top layer and smoothing the film surface might be key processing steps in the production of thick YBCO films with high J/sub c/.         A method for improving nucleation of thick YBCO films in the ex-situ process    V.F. Solovyov, H.J. Wiesmann, Li-Jun Wu, Yimei Zhu, M. Suenaga, D. Norton and K.R. Marken Jr. Summary: Some coated conductor applications require a YBCO layer at least 5 /spl mu/m thick with high J/sub c/. The growth of thick c-axis oriented epitaxial layers using the barium fluoride ex-situ technology is not always possible. Films over 3 /spl mu/m thick have more undesirable a-oriented and random grains than thinner ones. We present an analysis of thick film nucleation and conclude that thick precursor layers impede out-diffusion of the ex-situ reaction product, HF. High impedance for HF diffusion results in large variations of the chemical potential of the growth reaction and disruption of the nucleation process. We conclude that a solution for c-axis growth is control of the precursor permeability. A method is described for controlling the permeability of precursor layers. Using this technique we were able to grow c-axis oriented 5-/spl mu/m thick films on oxide-buffered Ni tape with J/sub c/(0 T) = 4 /spl times/ 10/sup 5/ A/cm/sup 2/ and J/sub c/(1 T) = 8 /spl times/ 10/sup 4/ A/cm/sup 2/.         Continuous tape coating by thermal evaporation    R. Nemetschek, W. Prusseit, B. Holzapfel, J. Eickemeyer, U. Miller and E. Maher Summary: Among the various coating techniques, thermal evaporation currently allows the highest YBCO volume deposition rates because of its large area capability. This "simultaneous large area deposition" capability translates into long tape lengths when the deposition area is densely filled up with metal tape. On short rolling-assisted biaxially textured substrate samples thermal evaporation has already established critical current densities in excess of 1 MA/cm/sup 2/ at 77 K, with very promising performance in magnetic fields. Recently, the deposition technique has been scaled up using a multiturn tape winder giving a simultaneously coatable length of about 4 m of 1-cm-wide tape. The reel-to-reel tape deposition system is designed for long term continuous operation based on in-situ refillable evaporation sources and controlled using feedback from atomic absorption spectroscopy measurements in the vapor phase. Here, the authors present results on the first coated conductor tape continuously fabricated by this technique.         Fabrication of high J/sub c/YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// tapes using the newly developed lanthanum manganate single buffer layers    M.P. Paranthaman, T. Aytug, S. Kang, R. Feenstra, J.D. Budai, D.K. Christen, P.N. Arendt, L. Stan, J.R. Groves, R.F. DePaula, S.R. Foltyn and T.G. Holesinger Summary: High J/sub c/YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) films have been fabricated on LaMnO/sub 3/ buffered ion-beam assisted deposition (IBAD) MgO template layers. A LaMnO/sub 3/ buffer layer is compatible with MgO surfaces and also provides a good template for growing high current density YBCO films. LaMnO/sub 3/ buffer layers were deposited using rf magnetron sputtering. On LaMnO/sub 3/-buffered-MgO [100] single crystal substrates, YBCO films with a J/sub c/ of over 4 M/cm/sup 2/ were grown using both pulsed laser deposition (PLD) and ex-situ BaF/sub 2/ process. Using PLD, J/sub c/ of 1.8 MA/cm/sup 2/ at 77 K was obtained on 200-nm-thick YBCO films grown on LaMnO/sub 3/-buffered MgO IBAD/Ni-alloy substrates. In addition, an I/sub c/ of 230 A/cm-width was obtained for 1.65-/spl mu/m-thick YBCO films grown on LaMnO/sub 3/-buffered MgO IBAD/Ni-alloy substrates using PLD at Los Alamos National Laboratory. This performance is comparable to the best single-layer results achieved on IBAD-MgO substrates.         Fabrication of Y-Ba-Cu-O films on surface-oxidation epitaxy (SOE) processed substrates    T. Watanabe, Y. Ohashi, T. Maeda, M. Mimura and I. Hirabayashi Summary: The surface-oxidation-epitaxy (SOE) method promotes simple and cost-effective process to form a biaxially textured NiO template for epitaxial growth of YBa/sub 2/Cu/sub 3/O/sub x/ (Y-Ba-Cu-O) film. SOE tapes of 100 m in length were prepared by the reel-to-reel oxidation system with the tape moving speed of 10 m/h. A highly biaxially textured NiO layer, which had /spl Delta//spl phi/ (full width at half maximum from X-ray /spl phi/-scan) of less than 23/spl deg/ throughout the whole length, was successfully formed under appropriate conditions of temperature and atmosphere. In order to improve surface conditions for obtaining high critical current density (J/sub c/) for Y-Ba-Cu-O film on the SOE-tapes, we have investigated the effect of thin oxide cap layers such as MgO, SrTiO/sub 3/, CeO/sub 2/, and so on. When BaZrO/sub 3/ was used as a cap layer, J/sub c/ and critical current (I/sub c/) of Y-Ba-Cu-O films grown by the pulsed laser deposition (PLD) at 77 K were measured to be 1.3 MA/cm/sup 2/ and 137 A, respectively. These values were for a 10 mm-width short tape. A continuous deposition of YBCO on 10-cm long /spl times/10-mm wide SOE tape with SrTiO/sub 3/ or BaZrO/sub 3/ cap layer was also investigated. The end-to-end I/sub c/ was 1 A (J/sub c/ of 1.6 /spl times/10/sup 4/ A/cm/sup 2/) for SrTiO/sub 3/ cap layer and 4 A (J/sub c/ of 5.6 /spl times/10/sup 4/ A/cm/sup 2/) for BaZrO/sub 3/ one.         Accelerated coated conductor program at Los Alamos National Laboratory    V. Matias, B.J. Gibbons, A.T. Findikoglu, S. Kreiskott, L. Bronisz and D. Peterson Summary: In order to accelerate research and development of coated conductors (CC), a new facility has been developed at Los Alamos National Laboratory (LANL) with labs dedicated to scaled-up fabrication and characterization of CC. These laboratories include facilities for metal tape preparation, ion-beam assisted deposition (IBAD) of template layers, superconductor deposition by laser ablation (PLD), as well as materials characterization including low-temperature transport measurements. The work builds on the prior successes of the LANL CC program, such as the benchmark results of critical currents over 300 A on 1-cm-wide short samples deposited via IBAD and PLD. The new labs have recently been completed and include the ability for reel-to-reel tape processing and characterization. Fabrication of long lengths of tape (>10 m) allow for high-throughput experimentation by linear combinatorial design. This facility is also made to enable collaboration with industrial and other partners.         Scale up of high-performance Y-Ba-Cu-O coated conductors    V. Selvamanickam, H.-G. Lee, Y. Li, J. Reeves, Y. Qiao, Y.Y. Xie, K. Lenseth, G. Carota, M. Funk, K. Zdun, J. Xie, K. Likes, M. Jones, L. Hope and D.W. Hazelton Summary: YBa/sub 2/Cu/sub 3/O/sub x/ (YBCO) coated conductors have been produced in meter lengths in pilot scale facilities established at IGC-SuperPower. Highly-smooth nickel alloy substrates have been polished in reel-to-reel polishing facility, with a uniform roughness of 2 nm. A pilot-scale ion beam assisted deposition (IBAD) facility has been used to produce 1 to 5 m lengths of buffered tapes with a uniform in-plane texture of 11 degrees and a surface roughness of 12 nm. YBCO has been deposited on meter-lengths of substrates by both pulsed laser deposition (PLD), and metal organic chemical-vapor deposition (MOCVD). End-to-end critical current of 43 A has been achieved in meter-long PLD-based YBCO. Meter-long YBCO tapes with a critical current of 90 A have been produced in MOCVD facility.         Bi-2212: an HTS coated conductor    R.D. Blaugher, R.N. Bhattacharya and J. Chen Summary: The Bi-2223 high-temperature-superconductor (HTS) powder-in-tube (PIT) tape, with useful performance for long lengths, has provided the ability to construct a wide range of HTS electric power components. The eventual commercialization of HTS power apparatus is primarily dependent on lowering the cost of HTS conductor. The present performance and cost of state-of-the-art Bi-2223 HTS tape, although acceptable for prototype construction, is viewed as a major factor that may compromise eventual commercialization. The so-called "second generation" coated conductor development, with emphasis on conductors employing HTS YBCO films, is viewed as the solution to this performance and cost issue. The potential for Bi-2212 for producing a low-cost HTS coated conductor as an alternative to Bi-2223 PIT (and YBCO) will be discussed with some recent results on Bi-2212 "coated conductor" development.         High-Ic YBCO coated conductors by metal organic deposition method using trifluoroacetates    T. Izumi, T. Honjo, Y. Tokunaga, H. Fuji, R. Teranishi, Y. Iijima, T. Saitoh, Y. Nakamura and Y. Shiohara Summary: For the development of the YBa/sub 2/Cu/sub 3/O/sub y/ (YBCO) coated conductors, processing of the thicker film and long tape have been investigated using the metal organic deposition (MOD) method with the trifluoroacetates solution. About 1 micro-meter thick MOD film was realized by the control of the P/sub H2O/ condition during annealing for the formation of the YBCO layer. The improvement was explained by the competition between the nucleation of the undesirable grains and the epitaxial growth up to the surface. By applying the suitable condition to the metallic substrate system, high critical current density (Jc) and critical current corresponding to 1 cm wide tape (Ic/sup */) were realized as to be 1.6 MA/cm/sup 2/ and 153 A/cm-w in the film with 1 micrometer thickness, respectively. For the fundamental investigation of long tape processing, influence of the gas flow direction during annealing for the YBCO formation was investigated. Although nonuniformities in the X-ray diffraction (XRD) intensities and Jc values were recognized in the film grown under the gas flow parallel to the long direction of the tape, both of them was improved by changing the gas flow direction to the transverse one.         Influence of porosity on the critical currents of trifluoroacetate-MOD YBa/sub 2/Cu/sub 3/O/sub 7/ films    O. Castano, A. Cavallaro, A. Palau, J.C. Gonzalez, M. Rosell, T. Puig, S. Pinol, N. Mestres, F. Sandiumenge, A. Pomar and X. Obradors Summary: The influence of porosity on the superconducting properties have been investigated on YBa/sub 2/Cu/sub 3/O/sub 7/ thin films deposited on LaAlO/sub 3/ [100] substrates by the so-called Trifluoroacetate (TFA) route. Micro-Raman spectroscopy have been used to determine the concentration of c-axis grains /spl delta/ in different samples and their influence on the final film porosity as observed from SEM imaging. This has been compared with measurements of resistivity and critical currents in the same samples. We prove that this /spl delta/ fraction is the main parameter controlling the porosity and hence the normal-state resistivity of the thin films. The optimization of the microstructure of these YBa/sub 2/Cu/sub 3/O/sub 7/ TFA films allow to have high critical currents : J/sub c/ = 3 /spl times/ 10/sup 6/ A/cm/sup 2/ at 77 K.         Preparation of YBCO coated conductor by the TFA-MOD method    Y. Takahashi, Y. Aoki, T. Hasegawa, Y. Iijima, T. Saito, T. Watanabe, I. Hirabayashi, Y. Yamada, T. Maeda, T. Honjo and Y. Shiohara Summary: The MOD method is well known as a low-cost process for a coated conductor. We have manufactured long-length YBCO coated conductors by the TFA-MOD process using various metallic tapes. In this work, we applied a continuous coating technique, a so-called bead-coating process, to prepare YBCO precursor films on CeO/sub 2/ (PLD)/ Zr/sub 2/Gd/sub 2/O/sub 7/ (IBAD)/ Hastelloy tapes. The YBCO films prepared by this process reveal high in-plane crystal alignment after an appropriate heat treatment. The double-coated 10 cm-long YBCO films made by the bead-coating process exhibit maximum I/sub c/ and J/sub c/ values of 25 A/cm-width and 0.5 MA/cm/sup 2/, respectively. We also deposited oxide buffer layers on {100}<001> Ni tapes using the MOD method to make low-cost YBCO tapes by a so-called All-MOD process. We observed highly in plane textured CeO/sub 2/, and RE/sub 2/O/sub 3/ (RE = Gd, Y, Yb) using MOD method. The YBCO films were coated by the TFA-MOD on the CeO/sub 2/ (MOD) buffer layer. YBCO films were highly in-plane textured on CeO/sub 2/ (MOD)/cube-textured Ni tapes. The FWHM values of the CeO/sub 2/ and YBCO were 10.4 degrees and 11.0 degrees, respectively.         Crystal growth of YBa/sub 2/Cu/sub 3/O/sub 7-X/ thin films prepared by TFA-MOD method    T. Ono, K. Matsumoto, K. Osamura and I. Hirabayashi Summary: We have investigated an epitaxial growth of YBa/sub 2/Cu/sub 3/O/sub 7-X/ (YBCO) films on [001] SrTiO/sub 3/ substrates prepared by metal organic deposition (MOD) method using trifluoroacetate (TFA) solution. The YBCO films derived by this method have high J/sub C/ exceeding 5 MA/cm/sup 2/ at 77 K. We tried to clarify the growth mechanism of TFA-MOD YBCO films by X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) from viewpoint of both macro and micro scales. We prepared partially transformed films by quench during high temperature annealing under the conditions at 730, 740, 750 /spl deg/C, dew point = 20 /spl deg/C, P(O/sub 2/) = 130 ppm, and gas flow rate = 1000 cc/min. In the growth stage, the integrated intensities of /spl theta/-/sub /spl chi// scans for the films increased with annealing time, and after more annealing, the integrated intensities decreased. SEM and TEM images indicated an existing of the pores in the films. Avrami plot was performed on the growing YBCO films, and the Avrami exponents were 1 < n < 2.         Growth mechanism of YBCO films in metal organic deposition method using trifluoroacetates    T. Honjo, Y. Nakamura, R. Teranishi, H. Fuji, J. Shibata, T. Izumi and Y. Shiohara Summary: We report the theoretical analysis of YBCO growth during post annealing in the TFA-MOD process considering both the diffusion in the boundary layer and the growth kinetics at the precursor/YBCO interface. As a result, we could obtain the analytical solution of the growth rate of YBCO. Subsequently, the unknown parameters in this solution were evaluated by the experimental measurements of the growth rate. The experimental results of the growth rate showed that it was independent of the film thickness and proportional to the square root of the water vapor pressure. These results suggested that the mass transfer in the gas boundary layer limited the growth rate. This model reveals a basic idea of the mechanism to determine the steady state growth rate, and could explain the experimental results. In addition, it predicts that the growth rate can be estimated from the water vapor pressure of the inlet gas. Consequently, it was confirmed that this growth model is effective for understanding of the growth kinetics in the TFA-MOD process.         Microstructures of YBa/sub 2/Cu/sub 3/O/sub 7-x/ films prepared by low-pressure oxygen atmosphere post-annealing of precursor films using Y, BaF/sub 2/ and Cu    A. Ichinose, A. Kikuchi, K. Tachikawa, S. Akita and K. Inoue Summary: Transmission electron microscopy (TEM), reflection high-energy electron diffraction (RHEED) and X-ray diffraction (XRD) are used to characterize the microstructure and surface topography of YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) films. The YBCO films of approximately 0.2 and 0.8 /spl mu/m thickness are prepared by a post-annealing of precursor films of co-evaporated Y, BaF/sub 2/ and Cu. The annealing conditions are the same for all cases except for the temperature elevation rate. RHEED patterns corresponding to the YBCO structure are observed in both the samples after annealing at 700 /spl deg/C for 30 minutes. The XRD patterns show that both YBCO films have primarily c-axis orientation. According to TEM observation results, the YBCO film of 0.2 /spl mu/m thickness is epitaxially grown from a substrate surface. In the case of thicker films of 0.8 /spl mu/m, the bottom region of the film is epitaxial YBCO, while the top region is a mixture of a-axis orientation, other orientations and impurities.         Reel-to-reel MOCVD for YBCO coated conductor    S. Donet, F. Weiss, P. Chaudouet, S. Beauquis, A. Abrutis, H.C. Freyhardt, A. Usokin, D. Selbmann, J. Eickemeyer, C. Jimenez, C.E. Bruzek and J.M. Saugrain Summary: A reel-to reel MOCVD system has been developed for a fast and economic process to get high quality YBCO coated conductor tapes. Several oxides buffer layer sequences (based on YSZ, CeO/sub 2/, Y/sub 2/O/sub 3/...) were then grown epitaxially on two kinds of tape. Effective stacking for MOCVD reported here are YSZ/Y/sub 2/O/sub 3//YBCO and YSZ/CeO/sub 2//YBCO, respectively, on oxidized Ni RABiTS microalloys (0,1% W) and on SS/YSZ (IBAD) tapes. First, EBSD and AFM techniques have been used to characterize the substrates. Superconducting YBCO films were fully characterized by SEM, XRD and AC susceptibility measurements Epitaxial growth was depicted with a strong in-plane and out-of plane texture: FWHM of YBCO /spl phi/-scans were 8.5/spl deg/ on Ni tape and 9/spl deg/ on IBAD Hastelloy tapes. High performances were also measured by AC susceptibility, with J/sub c/ values of 0.6 MA/cm/sup 2/ at 77 K (0 T) on Ni tape and close to 1 MA/cm/sup 2/ on IBAD substrates, with a sharp transition (/spl Delta/T/sub c/ < 0.4 K) and a T/sub c/ onset at 90 K. Deposition of 2 meter buffered YSZ and CeO/sub 2//YBCO films have also been performed showing good in-plane alignment (/spl phi/-scan YSZ: FWHM = 11/spl deg/) with a tape velocity set at 4 m/h.         MOCVD techniques for the production of coated conductors    O. Stadel, J. Schmidt, M. Liekefett, G. Wahl, O.Yu. Gorbenko and A.R. Kaul Summary: New deposition techniques are used for MOCVD of YBCO-, buffer- and protective layers in a reel to reel system. This system consists of three tape reactors and evaporators. So it is possible to deposit the superconductor, the buffer layer and a protective layer in situ in one vacuum system. The operativeness of the reactors were tested separately. In the YBCO reactor superconducting films have been deposited with critical current densities over 1 MA/cm/sup 2/ at 77 K on moved textured Nickel tapes at a transport velocity of 4 m/h. Textured Ni substrates were coated in the buffer layer reactor with CeO/sub 2/ and in first experiments a Ag layer was deposited by MOCVD onto the YBCO film.         CeO/sub 2/ buffer layers deposited by pulsed laser deposition for TFA-MOD YBa/sub 2/Cu/sub 3/O/sub 7-x/ superconducting tape    T. Muroga, T. Araki, T. Niwa, Y. Iijima, T. Saito, I. Hirabayashi, Y. Yamada and Y. Shiohara Summary: A CeO/sub 2/ buffer layer was deposited by the pulsed laser deposition (PLD) method on a YSZ single crystal substrate and an IBAD-Gd/sub 2/Zr/sub 2/O/sub 7/ substrate. It was investigated in terms of the effect of the CeO/sub 2/ layer thickness for YBa/sub 2/Cu/sub 3/O/sub 7-X/ (YBCO) coated conductors by the metalorganic deposition method using trifluoroacetates (TFA-MOD). The grain alignment, delta phi, and surface roughness, R/sub a/, of CeO/sub 2/ layers were improved with increasing the thickness for both kinds of substrates of a YSZ single crystal and an IBAD-Gd/sub 2/Zr/sub 2/O/sub 7/ substrate. Especially the improvement of the qualities of the CeO/sub 2/ layer on the IBAD substrate was remarkable. The initial value of delta phi was 12 degree at the surface of the IBAD-Gd/sub 2/Zr/sub 2/O/sub 7/ layer without a CeO/sub 2/ layer while it decreased to 4 degree after 600 nm thick CeO/sub 2/ layer deposition by PLD. Consequently, the J/sub c/ value of the YBCO on the CeO2 buffered IBAD-Gd/sub 2/Zr/sub 2/O/sub 7/ metallic substrate exhibited the value as high as 2.9 MA/cm/sup 2/ at 77 K and 0 T. This result implies that a high rate deposition by PLD could be used for further texture evolution even after thin film IBAD deposition which could result in shortening of the overall production time for the buffer layers deposition.         High critical current density YBa/sub 2/Cu/sub 3/O/sub 7-x/ films grown on mechanically polished surface-oxidized NiO/Ni substrates    K. Matsumoto, A. Takechi, T. Ono, I. Hirabayashi and K. Osamura Summary: A NiO surface produced by surface-oxidation epitaxy (SOE) method was flattened by a mechanical polishing technique. The surface roughness of NiO was reduced in this manner to about 5 nm. In addition, thin perovskite films were deposited on the polished NiO as a new cap layer. Consequently, J/sub c/ of the YBCO films formed on BaSnO/sub 3//NiO/Ni substrate by pulsed laser deposition reached 0.45 MA/cm/sup 2/ (77 K, 0 T), and J/sub c/ of YBCO/BaZrO/sub 3//NiO/Ni increased up to 0.89 MA/cm/sup 2/ (77 K, 0 T). Development of J/sub c/ is due to the reduction of superconducting weak coupling by flattening of NiO surfaces and the improvement of crystal orientation of YBCO films by the use of perovskite cap layers.         Texture and surface analysis of NiO buffer deposited on biaxially textured Ni tapes by a MOCVD method    Jong-Won Sun, Hyung Seop Kim, Bong Ki Ji, Hai-Woong Park, Gye-Won Hong, Choong-Hwan Jung, Soon-Dong Park, Byung-Hyuk Jun and Chan-Joong Kim Summary: NiO buffer layers for YBCO coated conductors were deposited on textured Ni substrates by a metal-organic chemical vapor deposition(MOCVD) method. Processing variables were the oxygen partial pressure and substrate temperature. The degree of texture and the surface roughness of the deposited NiO surface were analyzed by X-ray pole figure, atomic force microscopy (AFM), and scanning electron microscope (SEM). The (200) textured NiO layer was formed at 450 /spl sim/ 470 /spl deg/C and oxygen partial pressure of 1.67 Torr. Out-of-plane(/spl omega/-scan) and in-plane(/spl Phi/-scan) texture were 10.34/spl deg/ and 10.00/spl deg/, respectively. The surface roughness estimated by atomic force microscopy was in the range of 3.1 /spl sim/ 4.6 nm which was much smoother than that prepared by an oxidation method. We discuss the development of the (200) texture in the MOCVD-NiO films in terms of processing variables.         High J/sub C/ YBCO films on biaxially textured Ni with oxide buffer layers deposited using evaporation and sputtering techniques    B. Moenter, M. Getta, S. Kreiskott, H. Piel, N. Pupeter and J. Pouryamout Summary: Epitaxial buffer layers of CeO/sub 2/ and Yttria-stabilized ZrO/sub 2/ (YSZ) have been deposited on biaxially textured nickel substrates using thermal reactive evaporation, electron beam evaporation and rf sputtering. The buffer layers were characterized by XRD, SEM and optical microscopy. YBCO films were deposited by high-pressure dc sputtering on CeO/sub 2//YSZ/CeO/sub 2/ buffered substrates and the resulting superconducting properties were measured inductively. On exclusively evaporated buffer architectures critical current densities of 0.6 MA/cm/sup 2/ (77 K, H = 0 T) were measured. The buffers showed some cracks after YBCO deposition, which we considered to be responsible for the relatively low J/sub c/. Buffer architectures with evaporated CeO/sub 2/ followed by rf sputtering of YSZ and CeO/sub 2/ in oxygen atmosphere remained completely crack free after YBCO deposition. Critical current densities between 1.5 and 2.3 MA/cm/sup 2/ (77 K, H = 0 T) in 460 nm thick YBCO films were obtained reproducibly. The critical temperatures T/sub c/ ranged between 88 and 92 K and the typical width /spl Delta/T/sub c/ of the transition was 1.5 K.         Orientation of Ce-Y-Zr-O films deposited by reactive sputtering onto oxidized NiCr-tapes and Ni films    U. Wozniak, G. Linker and J. Geerk Summary: The growth of Ce-Y-Zr-O (CYZ) buffer layers for YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// deposition on textured Ni-tapes was studied under idealized conditions on [100]-SrTiO/sub 3/ (STO) single crystals and epitaxial Ni films and under real conditions on textured NiCr-tapes. The metallic substrates were epitaxially surface oxidized prior to deposition. The subsequent CYZ-layer was produced by rf sputtering employing combined planar and cylindrical targets and was characterized by x-ray diffraction (XRD) and Rutherford Backscattering. Films sputtered on STO-single crystals were 100 nm thick, had lattice constants between 0.5191 and 0.5443 nm, and out-of-plane mosaic spreads between 0.6 and 3.2/spl deg/. Best films grown on epitaxially surface oxidized Ni films and NiCr-tapes had lattice constants of 0.5220 and 0.5226 nm, and out-of-plane mosaic spreads of 2.3/spl deg/ and 6.8/spl deg/, respectively and were highly [100]-orientated (> 95%).         Oxide buffer layer with perovskite structure for YBa/sub 2/Cu/sub 3/O/sub 7-x/ coated conductors prepared by metal-organic deposition method    A. Takechi, K. Matsumoto and K. Osamura Summary: For fabricating YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) coated conductors on metal substrates with high critical current density (J/sub c/), deposition of oxide buffer layers is very important. BaZrO/sub 3/ (BZO) and BaSnO/sub 3/ (BSO) with a perovskite structure have excellent chemical compatibility with YBCO and good lattice matching with oxide substrates, including NiO buffer by surface oxidation epitaxy process. We have fabricated BZO or BSO buffer layers on SrTiO/sub 3/ single-crystal substrates by metal-organic deposition (MOD) method, in order to investigate the effects of buffer layers on superconducting properties of YBCO films. J/sub c/ of YBCO films deposited by pulsed laser deposition on BZO reached 0.29 MA/cm/sup 2/ (77 K, 0 T).         Deposition of CeO/sub 2/ buffer layers for YBCO coated conductors on biaxially textured Ni substrates by MOCVD technique    Ho-Jin Kim, Jinho Joo, Bong Ki Ji, Byung-Hyuk Jun, Choong-Hwan Jung, Soon-Dong Park, Hai-Woong Park, Gye-Won Hong and Chan-Joong Kim Summary: CeO/sub 2/ buffer layers for YBa/sub 2/Cu/sub 3/O/sub 7/(YBCO) coated conductors were deposited on biaxially textured Ni substrates by metalorganic chemical vapor deposition (MOCVD) method. The variables were the oxygen partial pressure (P/sub O2/), deposition temperature and time. The [200] texture of CeO/sub 2/ was formed at T = 500 /spl deg/C - 520 /spl deg/C, t = 3 - 15 min and P/sub O2/ = 2.30 torr, while the [111] and [200] texture were competitively formed at other condition. The surface roughness of CeO/sub 2/ films was as good as 5 - 15 nm up to 500 /spl deg/C, while it rapidly increased as a result of grain growth of the CeO/sub 2/ at T /spl ges/ 520 /spl deg/C. The surface roughness of the CeO/sub 2/ films also increased as the deposition time increased. The growth rate of the CeO/sub 2/ films at T = 520 /spl deg/C and P/sub O2/ = 2.30 torr was 200 nm/min, which is much higher than those prepared by other physical deposition methods.         Study of a non-thermal/thermal formation of NiO on Ni5W-tapes    A.M. Heinrich, B. Woerz, H. Karl and B. Stritzker Summary: We enhanced the Surface Oxidation Epitaxy (SOE) for Ni-tapes containing 0.5% W. For that we applied a chemical oxidation of the tape (in HNO/sub 3/ or HNO/sub 3//acetic acid) previous to annealing (Chemical Enhanced Surface Oxidation Epitaxy/CE-SOE). During annealing in air an oriented [200] NiO growth took place. In the case of Ni5W this would not be possible with common SOE. We carried out the annealing experiments at low temperatures (typical deposition temperatures for buffer layers; e.g., 650 /spl deg/C) and at high temperatures (typical SOE temperatures; 1250 /spl deg/C). In both cases an oriented [200] NiO layer could be achieved. The obtained X-Ray Diffraction, Light-Microscope, SEM, AFM and SIMS data are reported.         Textured CeO/sub 2/ thin films on nickel tape by sol-gel process    Y. Akin, E. Celik, W. Sigmund and Y.S. Hascicek Summary: Cerium oxide (CeO/sub 2/) is one of the preferred buffer layer for fabrication of coated conductors, especially when e-beam evaporation technique is used for YBCO processing. Therefore, processing of CeO/sub 2/ buffer layers has been extensively studied by several vacuum deposition techniques. However, a nonvacuum process is desired for fabrication of coated conductors to make coated conductors widely available in the market. In order to develop a nonvacuum process for fabrication of coated conductors, we fabricated textured cerium oxide (CeO/sub 2/) buffer layers on biaxially textured-Ni [100] substrates by sol-gel process. The solution was prepared from metal-organic precursor, Cerium 2,4-pentanedionate, and was deposited on the Ni substrates using a reel-to-reel sol-gel dip coating system. The textured films were annealed at 1150 /spl deg/C for 10 min under 4% H/sub 2/-Ar gas flow. Extensive texture analysis has been done to characterize the texture of CeO/sub 2/ buffer layers. X-ray diffraction (XRD) of the buffer layer showed strong out-of-plane orientation on Ni tape. The CeO/sub 2/ [111] pole figure indicated a single cube-on-cube textured structure. The omega and phi scans revealed good out-of-plane and in-plane alignments. The full-width-at-half-maximum (FWHM) values of omega and phi scans of CeO/sub 2/ films were 6.47/spl deg/ and 7.26/spl deg/, respectively. ESEM micrographs of the CeO/sub 2/ films revealed pinhole free, crack-free and dense microstructures.         Unbalanced magnetron sputter deposition of biaxially aligned yttria stabilized zirconia and indium tin oxide thin films    G. De Winter, S. Mahieu, I. De Roeck, R. De Gryse and J. Denul Summary: Developing a fast and flexible deposition process for biaxially aligned buffer layers on polycrystalline or amorphous substrates is still an important step toward the development of a scalable process for REBa/sub 2/Cu/sub 3/O/sub 7-x/ (REBCO, RE(RareEarth) = Y, Nd,...) coated conductor. Biaxially aligned Yttria Stabilized Zirconia (YSZ) and Indium Tin Oxide (ITO) thin films were deposited using a specifically modified sputter magnetron. ITO could be an interesting alternative for YSZ as a buffer layer for REBCO, since it is an oxide materials with good electrical conductivity, the lattice matches with REBCO and it has more or less the same thermal expansion coefficient as REBCO. Conducting buffer layers are interesting for some applications. Some publications indicate that there is very little interaction between ITO and YBCO thin films. The layers were deposited in reactive DC sputter mode on glass and nonpolished Hastelloy substrates, at low pressure, with excellent adhesion and high deposition rate : deposition rates up to 75 nm/min were obtained for YSZ and up to 40 nm/min for ITO. The influence of some sputter parameters (e.g., pressure, target-to-substrate distance, ...) on the degree of biaxial alignment was investigated.         Microstructure of Nd-Ga-O/sub 3/ new seed layer for LPE growth of YBCO film    Seokbeom Kim, Sang-Im Yoo and Y. Yamada Summary: The microstructure and crystallization mechanism of NdGaO/sub 3/ (NGO) new seed layer for liquid phase epitaxy (LPE) growth of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) were revealed using high resolution SEM and TEM. NGO layer deposited by PLD at room temperature shows that very porous and columnar structure and this layer indicated amorphous by x-ray analysis. Amorphous NGO layer was crystallized with good in-plane and out of plane orientations keeping columnar structure by simple post annealing process. Biaxially aligned YBCO thick films were successfully fabricated on oriented novel porous NGO new seed layer. Although many cracks were observed for normally LPE grown YBCO films on NGO(110) single crystalline substrate, it was crack-free formed on porous NGO[100] film.         Fabrication of textured Ag substrate for YBCO coated conductor    Jun Hyung Lim, Bong Ki Ji, Ho-Jin Kim, Jinho Joo, Wansoo Nah, Gye-Won Hong, Chan-Joong Kim and P. Nash Summary: We fabricated textured Ag substrates for YBCO coated conductor and evaluated the effects of annealing temperature on microstructural evolution, texture formation, and surface morphology. An Ag ingot, prepared by melting in plasma arc and quenching, had a fine equiaxed microstructure. A strong {110} <110> textured Ag substrate was obtained by cold rolling and annealing at 800 /spl deg/C; the full-width at half-maximum (FWHM) value of {110} <110> poles was as sharp as 10/spl deg/. Atomic force microscopy (AFM) profiles show that the surface morphology was very smooth and root-mean-square (RMS) roughness of the substrate annealed at 800 /spl deg/C was 39.2 nm. However, it was found that the thermal grooving and faceting became remarkable as annealing temperature increased. The substrate of strong texture and smooth surface, fabricated in our study, is considered to be suitable for use as a substrate for the epitaxial deposition of superconductor films.         Fabrication and characterization of cube textured Ni substrate for YBCO coated conductors    Bong Ki Ji, Jun Hyung Lim, Dong-Wook Lee, Chang Che Shur, Jinho Joo, Wansoo Nah, Gye-Won Hong, Chan-Joong Kim, No-Jin Park and P. Nash Summary: We fabricated Ni-substrates for YBCO coated conductors applying by powder metallurgy technique and evaluated the effects of pressing and annealing time on the texture. Compacts were prepared applying uniaxial or isostatic pressure. The texture of the substrate, made by applying cold isostatic pressure (CIP), was stronger than that by uniaxial pressure. We attribute this to the fact that the CIP method provided higher density and more uniform density distribution. The texture of the substrate made by CIP had a strong 4-fold symmetry and [111]/spl par/ND texture after annealing at a temperature of 1000 /spl deg/C. It was noted that the degree of texture was almost independent of annealing time and the full-width at half-maximum (FWHM) of in-plane and out-of-plane were measured to be in the range of 9.55/spl deg/ - 10.53/spl deg/ and 8.57/spl deg/ - 9.85/spl deg/, respectively. The development of strong cube texture and high fraction of low angle grain boundaries of Ni-substrates made by powder metallurgy technique in our study was considered to be useful in the deposition of YBCO coated conductors.         Bi-axially textured Ni tapes fabricated by a cold rolling process of nickel powder compacts    Dong-Wook Lee, Bong Ki Ji, Jun Hyung Lim, Choong-Hwan Jung, Jinho Joo, Soon-Dong Park, Byung-Hyuk Jun, Gye-Won Hong and Chan-Joong Kim Summary: Powder metallurgy has been widely used to make high purity metals and alloys. We applied the powder metallurgy route to the fabrication of the bi-axially textured Ni and Ni-W alloy tapes for YBCO coated conductors. The Ni and Ni-W powder compacts were cold-rolled into tapes. The Ni powder used in this study was 5 /spl mu/m in size and 99.99% in purity. To densify them, the Ni and Ni-W rods were sintered at 1100 /spl deg/C for 6 h in 96% Ar-4% H/sub 2/ atmosphere, and cold-rolled into thin tapes of 80-100 /spl mu/m thickness. Heat-treatment condition for the development of cube texture were established for the tapes. The out-of plane and in-plane texture of the Ni and Ni-W tapes were about 8/spl deg/. In this paper, we discuss the effect of the processing variables on the texture development of the Ni and Ni-W tapes.         Long length {110}<110> textured Ag tapes for biaxially oriented YBa/sub 2/Cu/sub 3/O/sub 7/ coated conductors    T. Doi, Y. Mori, Y. Hakuraku, K. Onabe, M. Okada, N. Kashima and S. Nagaya Summary: A good {110}<110> texture was successfully obtained by the only 3 minutes post-roll annealing by the careful control of the cold-roll process. Such a short annealing time will enable to skip the final annealing process of the Ag tape for the recrystallization and to save the cost of the furnace, energy and the time. We could obtain 20 m long cold-rolled Ag tape with enough uniformity, which can be converted to the {110}<110> textured Ag tape by the only short time annealing. The 3 cm samples, cut from both end and from the middle part of the 20 m long cold-rolled tape and then annealed at 800 /spl deg/C for 5 minutes, were confirmed to have smooth surfaces and the shallow grooves at grain boundaries, as well as good {110}<110> textures from the X-ray {100} pole figures and the SEM photographs.         Influence of the substrate microstructure on the superconducting properties of YBCO coated conductors    G. Celentano, E. Varesi, T. Petrisor, V. Boffa, L. Ciontea, V. Galluzzi, U. Gambardella, A. Mancini, A. Rufoloni and A. Vannozzi Summary: The microstructure of Ni-5at%W (Ni-W) and Ni-11at%V (Ni-V) biaxially textured substrates has been investigated using X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). The correlation between the substrate microstructure and superconducting transport properties of YBa/sub 2/Cu/sub 3/O/sub 7-y/ (YBCO) film grown on it has been studied on the YBCO/CeO/sub 2//Ni-W and YBCO/CeO/sub 2//NiO/Ni-V architectures. Our study has ascertained that the in-plane texture of the substrates is one of the most important factors, limiting the critical current density. The Ni-V substrate has a lower percolation area due to the larger number of twinned grains and a broader in-plane angular distribution and, as a consequence, the YBa/sub 2/Cu/sub 3/O/sub 7-y/ (YBCO) film grown on it has a critical current density of 0.6 /spl times/ 10/sup 6/ A/cm/sup 2/, depressed by factor 2 with respect to YBCO grown on the Ni-W substrate. For the Ni-V substrate, another limiting factor is its low oxidation resistance. In contrast to Ni-V, the Ni-W substrate has a larger percolation area, mainly due to the absence of twinned grains, and a high oxidation resistance.         Critical currents of narrow YBCO rings on Ni and LaAlO/sub 3/ substrates    M. Polak, L. Krempasky, E. Demencik, D. Wehler, S. Kreiskott, B. Moenter, A. Polyanskii and D.C. Larbalestier Summary: Low loss YBCO based flexible conductors for AC operation must have a filamentary structure with filament width below 0.1 mm. MO images of structured YBCO films showed that the flux penetration is less homogeneous in YBCO filaments on Ni substrates than that in filaments on LaAlO, which indicates that the patterning may affect the critical current density in narrow filaments. To see the effect of patterning on the filament critical current we studied I-V curves and critical currents of YBCO rings with various widths ranging from 0.3 mm down to 0.02 mm. The rings were prepared by a standard lithographic process. To avoid problems with current contacts, the current in the rings was induced by external magnetic field and electric field-current characteristics were determined by a Hall probe method.         Inductive analysis of magnetic granularity effects in YBCO IBAD and RABiTS coated conductors    A. Palau, T. Puig, X. Obradors, A. Usoskin, H.C. Freyhardt, L. Fernandez and B. Holzapfel Summary: We present a noninvasive inductive analysis of YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) IBAD (ion beam assisted deposition) and RABiTS (rolling assisted biaxial textured substrates) coated conductors that enable us to analyze the electromagnetic granularity effects. We distinguish flux penetration through grain boundaries and grains and determine the inductive intergranular critical current density. The signature of reverse flux at low angle grain boundaries has been clearly identified by the appearance of a peak in the return branch of the irreversible magnetization. The present analysis evidence that IBAD and RABiTS coated conductors may exhibit comparable inter-grain critical current densities with the determining factor being the average in-plane grain misorientation.         Irreversible properties of coated conductors deposited by PLD on textured technical substrates    A. Vostner, Y.F. Sun, S. Tonies, H.W. Weber, R.I. Tomov, A. Kursumovic, B.A. Glowacki, J.E. Evetts, A. Tuissi and E. Villa Summary: Results on the angular and the field dependence of the critical transport current density as well as on the temperature dependence of the irreversibility fields in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// coated conductors are presented. The films were deposited by pulsed laser deposition on (Y/sub 2/O/sub 3//YSZ/CeO/sub 2/) triple buffer structures. Either textured magnetic Ni-Fe alloys or recently developed nonmagnetic Ni-Cr-W alloys with good biaxial texture (8.4/spl deg/ and 9.4/spl deg/ for /spl omega/ and /spl phi/ scans) were used as substrates. The influence of artificial pinning centers, introduced by fast neutron irradiation, on the irreversible properties of the YBCO films is discussed.         Percolative transition and scaling of transport E-J characteristics in YBCO coated IBAD tape    T. Kiss, M. Inoue, S. Egashira, T. Kuga, M. Ishimaru, M. Takeo, T. Matsushita, Y. Iijima, K. Kakimoto, T. Saitoh, S. Awaji, K. Watanabe and Y. Shiohara Summary: We have investigated extended electric field-vs.-current density E-J characteristics in YBCO coated IBAD tapes. The results of a Monte-Carlo study on the depinning in a random pin medium were compared with measurements. Using a low temperature scanning laser microscope, we examined the percolative behavior of the local resistive transition in the YBCO tape. It was also shown that the depinning probability, which is proportional to the dynamic resistance of the E-J curves, is scaled as a function of reduced current density with the aid of a power index. Consequently, the E-J characteristics in the tapes can be described by the combination of the two kinds of scaling laws: one is the scaling law of the depinning probability predicted in a random network and the other is the scaling law for the flux pinning force. These properties agree well with the percolation model of depinned clusters.         Variable temperature scanning laser microscopy of wider width high temperature superconducting films    L.B. Wang, M.B. Price, C. Kwon and Q.X. Jia Summary: We have investigated the spatial distribution of resistive properties in 2 mm wide and 10 mm long epitaxial superconducting films using a variable temperature scanning laser microscopy (VTSLM). This technique measures ac voltage of bolometric response created by a laser beam. We have observed the spatial nonuniformity of superconducting transition temperature in the resistive region, which has never been reported in samples wider than 300 /spl mu/m using scanning laser techniques. This result is a significant step toward developing VTSLM for coated conductor diagnosis.         Electro-deposition of Tl-1223 coated conductors using potential cycling and step methods    D.Y. Jeong, Y.B. Shim, K.G. Park, H.J. Seol, B.J. Kim, E.Y. Lee, T.O. Kim and K.C. Kim Summary: In the present study, cyclic and step potential were applied for the electro-deposition, and their effects on chemical composition and surface morphology of the electro-deposited Tl-1223 precursor film were investigated. Cyclic voltammetry resulted in more uniform morphology and homogeneous distribution of composition, provided that proper initiation voltage and potential sweep rate are chosen. Furthermore, the cyclic voltammetry was likely to much facilitate the control of the deposition parameters to obtain an aimed chemical composition.         Tl-1223 thick films-a competitor for Y-123 coated conductors?    S. Tonies, H.W. Weber, G. Gritzner, O. Heiml and M.H. Eder Summary: Tl-1223 thick films were grown on single crystalline LaAlO/sub 3/ substrates by a screen printing method and doped with small amounts of /sup 235/U. The critical current density was measured by dc transport measurements in fields up to 15 T and at temperatures between 30 K and 85 K. Furthermore, the angular dependence of the critical current density and of the irreversibility lines were studied. Excellent texture and very high critical current densities with a weak field dependence were found in the as grown samples. Substantial enhancements of the critical current density and enhanced irreversibility lines are observed after thermal and fast neutron irradiation. The weak field dependence of J/sub c/ is further reduced. The results are compared with YBaCuO coated conductors and Bi-2223 tapes.         Direct electrical heating of metal tape substrates for coated conductor deposition    H.Y. Zhai, H.M. Christen, P.M. Martin, L. Zhang and D.H. Lowndes Summary: A novel resistance heater, in which electrical current flowing directly through the metallic tape substrate induces the heating, was designed for the growth of high temperature superconductor tapes by pulsed laser deposition (PLD). YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) films grown on RABiTS (rolling assisted bi-axially textured substrates) show properties similar to those of PLD-grown films on substrates that were mounted on a heater block using silver paint. The advantages of this electrical heating method are presented, including the easily adjustable angle between the substrate surface and the plume direction. No physical contact to the back of the substrate is required in the deposition area, eliminating problems related to thermal conductivity, heater block roughness, or the use of silver paint.         Improving coated conductors    G. Hammerl, H. Bielefeldt, S. Leitenmeier, A. Schmehl, A. Weber, C.W. Schneider and J. Mannhart Summary: Today's coated conductor techniques are aimed to minimize by grain alignment the grain boundary problem of high-T/sub c/ superconductors. We present a new approach to enhance the critical current density of coated conductors, which is based on a modified microstructure of the substrate, to utilize grains with large aspect ratios. Calculations clearly show that by using such substrates critical current densities close to the intragrain J/sub c/ are possible.         Deposition and characterization of YBCO/CeO/sub 2/ thin films prepared by thermal co-evaporation on metallic tapes    M. Bindi, A. Botarelli, A. Gauzzi, L. Gianni, A. Baldini and S. Zannella Summary: A market penetration of HTS-based applications requires the development of a low-cost continuous production system for long HTS conductors. We report on deposition and characterization of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta///CeO/sub 2/ structures on metallic substrates prepared by a thermal co-evaporation technique. X-ray diffraction analysis reveals good biaxial orientation of both layers with inand out-of-plane FWHM = 8/spl deg/ and 9/spl deg/ respectively on biaxially textured Ni-Fe or Ni-W and on polycrystalline Hastelloy C276 substrates. YBCO films are metallic and superconducting with T/sub c,onset/ /spl sim/ 88 K. Work is in progress to scale up the process for long tapes.         Critical current of HoBa/sub 2/Cu/sub 3/O/sub y/ tape fabricated by inclined substrate deposition    N. Hobara, Y. Sato, S. Honjo, Y. Takahashi, K. Muranaka, K. Fujino, S. Hahakura, T. Taneda, K. Ohmatsu and H. Takei Summary: HoBa/sub 2/Cu/sub 3/O/sub y/ (HoBCO) films on the bi-axially textured buffer layer prepared by Inclined Substrate Deposition method are studied. The HoBCO and buffer layers are supported by Ni-based-alloy substrate to form superconducting tape. Critical current density (J/sub c/) of this tape exceeds about 1/spl times/10/sup 9/ A/m/sup 2/ at 77 K in the self-field. To investigate practical performance of this tape, various dependences of J/sub c/, such as the magnetic-field dependence is measured. For the measurement of J/sub c/ in the magnetic field, its dependence of the angle of the field and the tape's plane is taken into account. The result shows that J/sub c/ has a notable peak when the magnetic field is perpendicular to the angle of the field to the tape's plane. The J/sub c/ peak gradually diminishes as the field increases. Similar magnetic field dependence of J/sub c/ is observed in a YBa/sub 2/Cu/sub 3/O/sub y/ (YBCO) sample. This study confirms that data of the perpendicular and parallel field dependence of J/sub c/, as such, are not sufficient for evaluation of practical performance of HoBCO tape.         YBCO/YSZ/hastelloy superconducting tapes by IBAD magnetron deposition    S. Gnanarajan Summary: Superconducting YBCO/YSZ/hastelloy tapes were fabricated by depositing epitaxial YBCO films on biaxially aligned YSZ layers on polished hastelloy substrates. YSZ buffer layers were deposited by ion beam assisted magnetron deposition. The degree of biaxial alignment in YSZ and YBCO films was determined by x-ray pole figures and /spl phi/-scans. YSZ layers of different thicknesses reveal biaxial alignment develops at a thickness as small as 100 nm and enhanced biaxial alignment was observed in homoepitaxial YSZ layers. The best YBCO films had biaxial alignment phi scan full width half maximum (FWHM) of /spl sim/ 9/spl deg/. Tapes were fabricated up to 20 cm in length with critical current density of more than 0.5 MA/cm/sup 2/ at 77 K in most parts of the tape. Bending measurements on 3 cm length tapes indicate it retains 80% of the critical current for bending diameter up to 20 mm.         Electro-epitaxial buffer layers for REBCO tape architectures    R.M. Whiteley, R. Goodall, J.C. Moore, S.C. Speller and C.R.M. Grovenor Summary: The preparation of substrates for the deposition of highly aligned superconducting thin films is an area of active research for the fabrication of second generation HTS conductors, and it is especially important that the substrates are cheap and can easily and reliably be prepared in long lengths. We have developed a new technique for the preparation of epitaxial buffer layers by simple electrodeposition onto mechanically textured substrates. Ag/Ni, Ag/NiFe and Ag/Pd/NiFe samples have been fabricated with very high degrees of texture control, and highly aligned NdBa/sub 2/Cu/sub 3/O/sub 7/ and YBa/sub 2/Cu/sub 3/O/sub 7/ films have been deposited onto these substrates. We believe that this process offers substantial advantages in scalability, speed and cost-effectiveness over all other techniques currently being investigated for the preparation of technical substrates for second generation HTS conductors.         The progress made using the combustion chemical vapor deposition (CCVD) technique to fabricate YBa/sub 2/Cu/sub 3/O/sub 7-x/ coated conductors    A.C. King, S.S. Shoup, M.K. White, S.L. Krebs, D.M. Mattox, T. Polley, N. Darnell, K.R. Marken Jr., Seung Hong and B. Czabaj Summary: Combustion Chemical Vapor Deposition (CCVD) is a nonvacuum technique being investigated, in conjunction with the Rolling Assisted Biaxially Textured Substrates (RABiTS/spl trade/) process, as a method to fabricate low-cost, long-length Yttrium Barium Copper Oxide (YBCO) coated conductor tapes. This technique has been scaled to produce meter + lengths of buffer material with excellent epitaxial and microstructural uniformity along the length. Additional efforts focus on depositing YBCO on these lengths using several deposition techniques including CCVD. Pulsed laser deposition (PLD) YBCO with critical current densities >1 MA/cm/sup 2/ have been achieved on short coupons taken from meter lengths of CeO/sub 2//STO/Ni architectures. CCVD buffer layers on Ni-W are still being optimized as YBCO critical current densities are less than 50,000 A/cm/sup 2/. The critical current densities of coupons of YBCO deposited by CCVD onto CCVD buffered substrates is increasing up to 100,000 A/cm/sup 2/, but further optimization is needed to yield high performance samples.         Growth of oxide seed layers on Ni and other technologically interesting metal substrates: issues related to formation and control of sulfur superstructures for texture optimization    C. Cantoni, D.K. Christen, A. Goyal, L. Heatherly, F.A. List, G.W. Ownby, D.M. Zehner, H.M. Christen and C.M. Rouleau Summary: The current carrying capabilities of RABiTS are connected to the crystalline quality of the seed buffer layer and the stability of the metal/seed layer interface. Our study shows that the epitaxial growth of commonly used seed layers on textured Ni is mediated by a sulfur superstructure present on the metal surface. Many structural defects generated during seed layer growth (secondary orientations, in-plane rotation, incomplete cube texture) can be related to the S surface concentration and superstructure coverage. More generally, our results indicate that the epitaxial deposition of several classes of oxides (fluorite, perovskite, RE/sub 2/O/sub 3/) on several {100}<100> fcc metals depends, in addition to chemical stability and lattice match, on the existence and optimization of S superstructures on the metal surface. On these bases, we discuss issues related to the growth of different oxides on Ni, Ni-alloys, and Pd surfaces having different chemical and structural properties.         Improvement of IBAD MgO template layers on metallic substrates for YBCO HTS deposition    J.R. Groves, P.N. Arendt, S.R. Foltyn, Q.X. Jia, T.G. Holesinger, L.A. Emmert, R.F. DePaula, P.C. Dowden and L. Stan Summary: We present our results to improve ion beam assisted deposition (IBAD) of magnesia (MgO) templates for subsequent YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) deposition. The substrate surface roughness has a significant effect on the initial nucleation texture of IBAD MgO films. We have found that reduction in our substrate surface roughness to /spl sim/ 3.5 nm has resulted in better in-plane texture for IBAD MgO films than those deposited on rougher metal substrates. We have further improved the IBAD MgO deposition parameters by using an in situ reflected high-energy electron diffraction (RHEED) analysis tool that allows for monitoring of IBAD MgO growth. We have found a direct correlation between the RHEED generated intensity versus time curve and in-plane texture. Utilizing X-ray diffraction analysis, we have been able to determine the optimum deposition parameters to routinely grow films in batch mode that have a phi scan /spl Delta//spl phi/ from 6 - 7/spl deg/. Coupling the improvements in substrate preparation with optimization of IBAD MgO deposition has allowed for both batch and continuous deposition (termed c-IBAD MgO) on metallic substrates that result in superior superconducting properties. We have demonstrated that deposited meter lengths have had phi scan FWHM values from 8 - 9/spl deg/ with /spl plusmn/ 10% uniformity. Additionally, we have been able to widen the processing zone in our system and coat two, one-meter lengths simultaneously while preserving good texture quality (/spl Delta//spl phi//sub ave/ /spl sim/ 8/spl deg/) and uniformity (60 - 80% of tape length within /spl plusmn/ 5% of /spl Delta//spl phi//sub ave/) for both tapes.         Growth and characterization of SrRuO/sub 3/ buffer layer on MgO template for coated conductors    Q.X. Jia, S.R. Foltyn, P.N. Arendt, T. Holesinger, J.R. Groves and M. Hawley Summary: Recently, it has been shown that biaxially oriented MgO deposited by ion-beam-assisted-deposition (IBAD) is a significantly more cost-effective template for coated conductors. Nevertheless, the lack of good buffer layer materials for MgO has limited the accomplishment of high quality YBCO films. We, for the first time, have used SrRuO/sub 3/ as a single buffer layer directly on an MgO template (homo-epitaxial MgO/IBAD-MgO) for growth of thick YBCO films on polycrystalline metal substrates. By using SrRuO/sub 3/ as a buffer layer, we have routinely obtained YBCO films with an in-plane mosaic spread in the range of 3 - 6/spl deg/ full width at half maximum. A critical current density of 1.8 /spl times/ 10/sup 6/ A/cm/sup 2/ in self-field at 75 K for a film thickness of over 1.0 /spl mu/m has been achieved. We have further achieved a current per unit width of over 245 A/cm, which is the highest reported so far for a YBCO film on a polycrystalline metal substrate using MgO as a template.         Solution processing of lanthanum zirconate films as single buffer layers for high I/sub c/ YBCO coated conductors    S. Sathyamurthy, M.P. Paranthaman, Hong-Ying Zhai, Sukill Kang, H.M. Christen, C. Cantoni, A. Goyal and P.M. Martin Summary: Sol-gel processing of lanthanum zirconate (La/sub 2/Zr/sub 2/O/sub 7/ - referred to as LZO) buffer layers on biaxially textured nickel and Ni-3 at.% W alloy substrates using spin coating and a continuous reel-to-reel dip-coating unit has been studied. The epitaxial LZO films obtained have a strong cube texture and uniform microstructure. This coating and annealing process was repeated to get the desired buffer layer thickness. On these all-solution single buffer layer substrates, YBCO films were grown using pulsed laser deposition process. Critical current density about 2 MA/cm/sup 2/ at 77 K and self-field has been obtained on these samples. Continuous processing of these substrates and processing of high I/sub c/ YBCO films on them will be discussed.         LaMnO/sub 3/: a single oxide buffer layer for high-J/sub c/ YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// coated conductors    T. Aytug, M. Paranthaman, S. Kang, H.Y. Zhai, K.J. Leonard, C.E. Vallet, S. Sathyamurthy, H.M. Christen, A. Goyal and D.K. Christen Summary: Single buffer layer of LaMnO/sub 3/ (LMO) has been epitaxially grown on biaxially textured Ni and Ni-alloy substrates by sputter deposition. The property characterizations revealed that LMO buffers can serve both as a chemical as well as a structural buffer for YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) films. Epitaxial YBCO films grown on LMO buffers using pulsed laser deposition (PLD) have self-field critical current densities (J/sub c/) exceeding 1 /spl times/ 10/sup 6/ A/cm/sup 2/ at 77 K. The present results have demonstrated the strong prospect of LMO for the practical development of YBCO coated conductors.         Characteristics of Ce-Zr mixed oxide films as buffer layer by controlling composition    H.Y. Lee, S.I. Kim, Y.C. Lee, Y.P. Hong and K.H. Ko Summary: YSZ films have been widely used as buffer layers for high T/sub c/ superconductor. However, it is necessary to investigate and develop another buffer layer with suitable, simple, and neat processing. Films of Ce-Zr mixed oxide were deposited by rf and dc magnetron co-sputtering. In sputtering process, dc power of Zr was fixed in 200 W while rf power of Ce was varied with 30 W, 50 W, 100 W, respectively. As-deposited (Ce/sub x/Zr/sub 1-x/)O/sub 2/ films were crystallized without post annealing. It was confirmed that the composition of the films could be controlled with controlling rf power of Ce target. The /spl Phi/ scan of XRD showed that all (Ce/sub x/Zr/sub 1-x/)O/sub 2/ films were [200] c-axis oriented. Three consecutive magnetron sputtering procedure for seed, CZO and cap layer for HTSC films using Ce, Zr and CeO/sub 2/ target were carried out on the Si[100] and Ni substrate successfully. It is suggested that sputtered and c-axis oriented (Ce/sub x/Zr/sub 1-x/)O/sub 2/ films can be a potential candidate to replacing YSZ buffer layer.         Sol-gel Tb/sub 2/O/sub 3/ buffer layers on Ni tapes for YBCO coated conductors    E. Celik, Y. Akin, W. Sigmund and Y.S. Hascicek Summary: In this study, processing of Tb/sub 2/O/sub 3/ buffer layers on textured Ni tapes were evaluated for YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) coated conductor. A solution deposition process was used to grow textured Tb/sub 2/O/sub 3/ buffer layers on the Ni tapes. The solution was prepared using Tb-2, 4-pentanedionate precursor, methanol as solvent, chelating agents and a solution modifying chemical, triethanolamine (TEA). Biaxially textured Ni substrates were dipped into the solution by a reel-to-reel sol-gel dip coating system. The amorphous thin films were dried at 300 /spl deg/C for 30 sec and then heat-treated at 500 /spl deg/C for 2 min in air using an in-line three-zone furnace. The films were annealed at temperature range of 900 /spl deg/C and 1170 /spl deg/C for 10 to 20 min under 4%H/sub 2/ - Ar gas flow. The textured buffer layers were obtained using TEA onto the textured Ni tapes at 1150 /spl deg/C for 10 minutes. The Tb/sub 2/O/sub 3/ (222) pole figure revealed a single cube-on-cube texture. The omega and phi scans indicated good out-of-plane and in-plane orientations. DTA results pointed out that Tb based gel film transformed to oxide structure at temperature range of 350 /spl deg/C and 410 /spl deg/C. Microstructures of the Tb/sub 2/O/sub 3/ films were investigated by Environmental Scanning Electron Microscope (ESEM), and the films were dense, smooth and free from cracks and pinholes.         Textured growth of multi-layered buffer layers on Ni tape by sol-gel process    Y. Akin, Z. Aslanoglu, E. Celik, L. Arda, W. Sigmund and Y.S. Hascicek Summary: Textured Cerium Oxide (CeO/sub 2/)/Yttrium-Stabilized Zirconia (YSZ)/CeO/sub 2/ buffer layers structure were grown by sol-gel dip coating process on bi-axially textured Ni tapes for processing of YBCO coated conductors. CeO/sub 2//YSZ/CeO/sub 2/ buffer layer structure has been demonstrated by vacuum techniques, but first time textured CeO/sub 2//YSZ/CeO/sub 2/ structure were grown by sol-gel on biaxially textured Ni tape. The buffer layer structure promoted c-axis oriented sol-gel YBCO films and prevented oxidation of nickel during YBCO processing. After each layer was coated, the layer was annealed. CeO/sub 2/ layers were annealed at 950 /spl deg/C for 30 min. and YSZ layers were annealed at 1150 /spl deg/C for 10 min. under 4% H/sub 2/ - Ar gas flow. Texture analysis of Ni substrates and bottom CeO/sub 2/ were done by Philips diffractometer. Sol-gel YBCO layers were coated on CeO/sub 2//YSZ/CeO/sub 2/ structure and critical current density was about 0.5 /spl times/ 10/sup 5/ A/cm/sup 2/. Microstructure of the buffer layer was investigated by Environmental Scanning Electron Microscope (ESEM).         Y-and Yb-123 coated conductor development by PLD and sol-gel on (Gd/sub 1-x/Er/sub x/)/sub 2/O/sub 3/ buffered Ni tapes    H. Okuyucu, L. Arda, Z.K. Heiba, M.I. El-Kawni, J.C. Tolliver, P.N. Barnes, Z. Aslanoglu, Y. Akin and Y.S. Hascicek Summary: YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// and YbBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// layers were coated by sol-gel and PLD on Gd/sub 1.91/Er/sub 0.09/O/sub 3/ (100% lattice match with Y- and Yb-123) textured buffer layer on Ni substrates. Different thickness of buffer layers and superconducting layer were tried to see the thickness effect on superconducting properties. Buffer layers were prepared with different lattice parameters for Y-123 and Yb-123. Coated conductors were characterized by means of XRD, ESEM and T/sub c/ and J/sub c/ measurement. Since the perfect lattice match can be achieved between buffer layer and superconducting layer, texture of superconducting film was improved, and consequently critical current density of Y- and Yb-123 were improved.         Development of 100% lattice match buffer layers on RABiTS Ni tapes by sol-gel    H. Okuyucu, L. Arda, Y. Akin, Z.K. Heiba, Z. Aslanoglu and Y.S. Hascicek Summary: Gd/sub 2/O/sub 3/-Yb/sub 2/O/sub 3/ and Gd/sub 2/O/sub 3/-Ho/sub 2/O/sub 3/ mixed RE oxides were used to produce buffer layers with a perfect lattice match with superconducting layer. Since these RE oxides are 100% miscible in each other, pseudocubic lattice parameter of the buffer layers can be modified by changing the ratio of components to perfectly match with any superconducting RE-123. Texture and the microstructure of the buffer layers were studied by XRD, Pole Figure and ESEM.         Infinite-layer copper-oxide laser-ablated thin films: substrate, buffer-layer, and processing effects    J.T. Markert, T.C. Messina, B. Dam, J. Huijbregste, J.H. Rector and R. Griessen Summary: Laser-ablation studies of highly-oriented thin films of the electon-doped infinite-layer copper-oxide compounds Sr/sub 1-x/La/sub x/CuO/sub 2/ are reported. We observe significant variations in film properties with substrate or buffer layer material. X-ray diffraction, atomic force microscopy (AFM), Rutherford back-scattering (RBS), and electrical resistivity were used to characterize the films. Films were deposited on strontium titanate [001] or on buffer layers of T'-phase copper oxides (Ln/sub 2/CuO/sub 4/ with Ln = Pr, Nd, Sm), Sr/sub 3/FeNb/sub 2/O/sub 9/, and La/sub 1.8/Y/sub 0.2/CuO/sub 4/ on SrTiO/sub 3/ [001]. The in-plane lattice constants of such buffer layers (a = 0.390 - 0.400 nm) should provide the bond tension required for electron doping. Extremely flat, epitaxial buffer layers with X-ray rocking curves as narrow as 0.08/spl deg/ were obtained from stoichiometric targets of Ln/sub 2/CuO/sub 4/; the other buffer layers yielded poor epitaxy. A linear dependence of infinite-layer c-axis plane spacing on substrate or buffer-layer in-plane a-axis lattice constant is observed.         Preparation of double-sided CeO/sub 2/ buffer layers on MgO substrates for YBa/sub 2/Cu/sub 3/O/sub 7-x/ films    K. Taki, T. Araki, D. Yamashita, I. Hirabayashi, Y. Enomoto and K. Suzuki Summary: Double-sided CeO/sub 2/ buffer layers were fabricated by pulsed-laser deposition on 20 mm /spl times/ 20 mm MgO[100] substrates to apply YBCO films using the TFA-MOD (trifluoroacetate-metalorganic deposition) process for microwave devices. The double-sided CeO/sub 2/ films had the characteristics of a smooth surface (R/sub ms/ < 1 nm) and a highly [100] aligned orientation, which is almost independent of thickness. We successfully obtained a YBCO film deposited by the TFA-MOD process on CeO/sub 2//MgO[100], which had a critical current density (J/sub c/) of 6 MA/cm/sup 2/ (77 K, 0 T) with good reproducibility.         Texture development of MgO buffer layers grown by inclined substrate deposition    R.E. Koritala, Beihai Ma, D.J. Miller, Meiya Li, B.L. Fisher and U. Balachandran Summary: Biaxially textured magnesium oxide (MgO) films used as template layers for YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO)-coated conductors have been grown efficiently and consistently by inclined substrate deposition (ISD). Further improvement in texture and a decrease in surface roughness were obtained by depositing a homoepitaxial MgO layer on the ISD MgO layer at an elevated temperature and flat angle. The texture of the ISD layer was studied as a function of thickness by X-ray diffraction and scanning and transmission electron microscopy. Surface roughness of the ISD and homoepitaxial layers was investigated by atomic force microscopy. Based on the results, the optimal thickness of the ISD layer was determined.         Biaxially aligned template films fabricated by inclined-substrate deposition for YBCO-coated conductor applications    Beihai Ma, Meiya Li, R.E. Koritala, B.L. Fisher, A.R. Markowitz, R.A. Erck, S.E. Dorris, D.J. Miller and U. Balachandran Summary: Inclined substrate deposition (ISD) has the potential for rapid production of high-quality biaxially textured buffer layers, which are important for YBCO-coated conductor applications. We have grown biaxially textured MgO films by ISD at deposition rates of 20 - 100 /spl Aring//sec. Columnar grains with a roof-tile surface structure were observed in the ISD-MgO films. X-ray pole figure analysis revealed that the [002] planes of the ISD-MgO films are tilted at an angle from the substrate normal. A small /spl phi/-scan full-width at half maximum (FWHM) of /spl ap/ 9/spl deg/ was observed on MgO films deposited at an inclination angle of 55/spl deg/. In-plane texture in the ISD MgO films developed in the first 0.5 /spl mu/m from the interface, then stabilized with further increases in film thickness. YBCO films deposited by pulsed laser deposition on ISD-MgO-buffered Hastelloy C276 substrates were biaxially aligned with the c-axis parallel to the substrate normal. T/sub c/ of 91 K with a sharp transition and transport J/sub c/ of 5.5 /spl times/ 10/sup 5/ A/cm/sup 2/ at 77 K in self-field were measured on a YBCO film that was 0.46-/spl mu/m thick, 4-mm wide, 10-mm long.         Critical currents of Sm/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// films grown on various substrates    K. Chung, H. Kim, B. Lee, S. Lim, S. Choi, S. Oh and D. Youm Summary: We observed that a Sm/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// (SBCO) film grown on a YSZ substrate with arbitrarily oriented crystal was textured in a single crystalline orientation, while there seems to be no noticeable relation between the crystalline orientations of the film and the substrate. The SBCO[103] axis was close to the surface normal axis. On the other hand, we could not grow an YBCO film on the same substrate, which implies the growth of SBCO film is more stable than YBCO film on that substrate. The qualities of SBCO films grown at substrate temperatures across a wide range of 680 /spl deg/C $750 /spl deg/C were similar. The critical current density of this SBCO film was /spl sim/ 3 times smaller than that of SBCO film on a RABiTS-Ni tape, which is several times smaller than that of the YBCO film of coated conductor.         Growth of cube-textured nickel substrates for HTS coated conductors    Y.X. Zhou, T. Rizwan and K. Salama Summary: A critical step in the successful fabrication of coated conductors on metal substrates is to produce cube texture substrates using the RABiTS approach. Nickel has been used as a substrate for high-current coated YBa/sub 2/Cu/sub 3/O/sub x/ superconductors due to the relative ease in achieving sharp cube texture as well as chemical compatibility. High purity nickel (99.995%) samples were rolled to large deformation and annealed in 5% H/sub 2/ - 95% Ar atmosphere at 700 /spl deg/C - 1100 /spl deg/C for various times. The cube texture was promoted by recrystallization after cold rolling. The effects of deformation reduction per pass, amount of deformation, and annealing temperature and time on the recrystallization process were investigated using XRD and EBSD techniques. These parameters have been optimized to obtain the cube texture {100}<001>. The sharpest cube texture (> 80% of grains within 7/spl deg/ and > 97% within 10/spl deg/ cube textured) was obtained for nickel cold rolled by 2% reduction per pass and annealed at 1000 /spl deg/C for 90 minutes.         Characteristic of long nickel tape for YBCO coated conductor prepared by electrodeposition    Kyu Hwan Lee, Doyon Chang, Dongsoo Kim, Jaimoo Yoo, Jaewoong Ko, Haidoo Kim, Hyungsik Chung and Jai-Young Lee Summary: Electrodeposition method has been applied to reduce the thickness of biaxially textured Ni tape for YBCO coated conductor. The electrodeposition method can be an alternative way to the thermomechanical method, which is commonly used to fabricate a long biaxially textured substrate. This method not only has many advantages from the industrial point of view but also can improve the value of the J/sub e/ of coated conductor by reducing the thickness of Ni tape. In this work, a chemically stable cathode drum material was determined and Ti grade-2 is adequate for cathode drum materials. 20 cm long Ni tape with the thickness of 50 /spl mu/m has been prepared. X-ray /spl phi/-scan and /spl omega/-scan as a function of length were measured for Ni tape. The results showed that the average in-plane texture and out-of-plane texture are estimated to be 23.4 /spl plusmn/ 7.5/spl deg/ and 8.2 /spl plusmn/ 0.7/spl deg/ respectively.         119) oriented Bi-2223 thin films grown on [100] NdGaO/sub 3/ by MOCVD    K. Endo, P. Badica and K. Abe Summary: Orientation control of high T/sub c/ superconductors is essential for superior device performance, because the coherence length is longer along the non c-axis directions than along c-axis direction. In this study, we report on the first successful preparation of (119) oriented Bi-2223 films by MOCVD using [100] NdGaO/sub 3/ substrates. Atomic force microscopy observations of the (119) Bi-2223 films are also reported. Our films have an in-plane aligned mountain-range-shaped surface morphology. This morphology is resulting from the epitaxial relationship between the (119) Bi-2223 film and [100] NdGaO/sub 3/ substrate. Films exhibited a large in-plane anisotropy as revealed by resistivity measurements and surface morphology observations.         Buffer layers for Tl-2212 thin films on MgO and sapphire substrates    S.C. Speller, Houzheng Wu and C.R.M. Grovenor Summary: High quality Tl-2212 films can be readily grown on LaAlO/sub 3/ substrates, but the design of complex microwave devices in these films is made more difficult by the twinning of the substrate. CeO/sub 2/ buffer layers on sapphire have been previously demonstrated to offer excellent substrates for Tl-2212 films. We have been exploring alternative architectures for buffer layers on MgO and sapphire. Epitaxial Tl-2212 superconducting thin films have been successfully grown on Gd/sub 2/O/sub 3/-buffered MgO substrates by sputter deposition of a Tl-free precursor followed by an ex-situ thalliation anneal. The Tl-2212 films were aligned with the c-axis normal to the film surface, and also had excellent in-plane orientation with Tl-2212 [100] aligned with the Gd/sub 2/O/sub 3/ and MgO [110]. The critical temperatures of the films ranged from 100 - 103 K and transport and inductive critical current densities of 7.5 /spl times/ 10/sup 5/ A/cm/sup 2/ at 77 K have been achieved. We have also fabricated epitaxial GdAlO/sub 3/ buffer layers on sapphire substrates which support epitaxial growth of Tl-2212 but with relatively poor microstructure. High quality films have been prepared on the new (La,Sr)(Al,Ta)O/sub 3/ (LSAT) substrates.         Crystallinity and surface morphology of YBCO thin films using an amorphous buffer layer deposited at a low temperature    Y. Nakamura, T. Tsuchihata, S. Kudo, T. Kawamata, M. Mukaida and S. Ohshima Summary: We have investigated the crystallinity and surface morphology of main YBCO films and buffer layers deposited on an MgO substrate by a low temperature buffer layer deposition technique. A significant improvement in the crystalline quality of the YBCO film is achieved when an amorphous buffer layer of 100 [nm] in thickness on bare MgO substrate annealed at 930[/spl deg/C] is crystallized by annealing temperature 950[/spl deg/C] for 1 hour in an air atmosphere. The surface of main YBCO films has pyramid like large grains when YBCO films have good crystallinity. We confirmed that YBCO films grown on a well-crystallized buffer layer had better crystallinity than ones grown on bare MgO substrate.         MgO substrate surface optimization for YBaCuO thin film growth    A.F. Degardin, F. Houze and A.J. Kreisler Summary: To obtain high quality Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/ (YBaCuO) films grown on [001] MgO substrates, we have investigated the influence of high temperature substrate annealing prior to film deposition. In particular, we discuss the effect of annealing conditions (atmosphere, temperature and time) on MgO substrate morphology observed with atomic force microscopy. Thermal treatment under specific conditions resulted in the formation of [001]-oriented terraces bounded by [100]-oriented steps on the substrate surface. An improvement in the crystalline quality, as well as better DC electrical properties and microwave surface resistance values, has been observed for films sputtered onto substrate surfaces exhibiting such regular nanoscale step structures.         Preparation of perovskite type manganite on Al/sub 2/O/sub 3/ substrate as an excellent buffer layer for YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// growth    H. Nishikawa, S. Hontsu, M. Nakamori, H. Tabata and T. Kawai Summary: The perovskite type ferromagnetic manganite Pr/sub 0.8/Ca/sub 0.2/MnO/sub 3/ (PCMO) buffer layers for superconducting microwave devices were examined in order to allow Al/sub 2/O/sub 3/ single crystal to be used as a substrate for YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) growth and to provide functionality for microwave devices. The use of magnetic buffer layers with YBCO is effective to magnetically controllable superconducting microwave devices. The (0001) surface of the Al/sub 2/O/sub 3/ and [113]-oriented YBCO are used in this study due to the similarity of ion configurations at the interface. YBCO grown on the PCMO buffer shows a critical temperature of 87.5 K. The straight line of YBCO grown on the Al/sub 2/O/sub 3/ (0001) buffered by the PCMO shows relatively good transmission property with the insertion loss of less than 0.7 dB below 70 K measured at 2 GHz. These results indicate that PCMO is a suitable magnetic buffer layer for YBCO growth on Al/sub 2/O/sub 3/ (0001).         Epitaxial YBa/sub 2/Cu/sub 3/O/sub y/ thin films grown on silicon with a double buffer of Eu/sub 2/CuO/sub 4//YSZ    J. Gao, L. Kang, T.K. Li, Y.L. Cheung and J. Yang Summary: We report a double buffer of Eu/sub 2/CuO/sub 4/ (ECO)/YSZ to improve the growth of YBa/sub 2/Cu/sub 3/O/sub y/(YBCO) on Si wafer. The ECO buffer material possesses a very stable 214-T' structure. It has excellent structural and chemical compatibilities with YBCO and YSZ. Our study showed that the epitaxy and crystallinity of YBCO deposited on Si could be considerably enhanced by using such a double buffer of ECO/YSZ. The grown films were characterized by grazing incidence X-ray reflection, rocking curve, SEM, TEM, and surface profiler. It was also found that such a double buffer could lead to a very smooth surface in the YBCO layer.         Unexpected electronic properties of strained La/sub 1.85/Sr/sub 0.15/CuO/sub 4/ epitaxial films    D. Ariosa, M. Abrecht, D. Cloetta, D. Pavuna, M. Onellion and G. Margaritondo Summary: Surprising results on electronic properties of strained thin La/sub 1.85/Sr/sub 0.15/CuO/sub 4/ epitaxial films are reported. We report on the very first angle resolved photoemission (ARPES) measurements of the dispersion on in-situ grown, in-plane compressed T-phase LSCO films (showing T/sub C/ enhancement). The data show clear band crossing, implying that in-plane compressive strain at constant doping results in the suppression of the saddle point, changing the topology of the Fermi surface from hole-like to electron-like.         Orientation mechanism of REBa/sub 2/Cu/sub 3/O/sub y/ (RE = Nd, Sm, Gd, Y, Yb) thin films prepared by pulsed laser deposition    Y. Ichino, K. Sudoh, K. Miyachi, Y. Yoshida and Y. Takai Summary: The orientation behavior and mechanism of REBa/sub 2/Cu/sub 3/O/sub y/ (RE123) films have not been clarified yet. We prepared RE123 films by the pulsed laser deposition method and investigated the orientation behavior and mechanism. We argue that the orientation behavior strongly depends on thermodynamic parameters such as the heat of sublimation. The thickness and surface morphology dependences of the orientation suggest that c-axis oriented thicker films will be obtained in RE123 if the surface remains smooth up to objective thickness. Critical temperatures were around or higher than 90 K and critical current densities were larger than 1 MA/cm/sup 2/ for all RE123 films. From the viewpoint of the orientation, the Yb123 films were the easiest to grow with the c-axis normal to the substrate surface.         Formation of epitaxial YBCO thin films by ex-situ processing of a polymerized complex    A.J. Bubendorfer, T. Kemmitt, L.J. Campbell and N.J. Long Summary: High T/sub c/ and J/sub c/ YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) thin films have been formed by ex-situ processing of a spin coated organic sol-gel precursor based on a polymerized complex. To form the precursor we have reacted metal cations with a chelating organic acid, then formed polyesterified complexes through reaction with a polyhydroxy alcohol. This method permits a simple, cheap and reliable route to the fabrication of YBCO films. The value of J/sub c/ achieved for the film deposited onto a LaAlO/sub 3/ [100] substrate at 77 K under a zero field is routinely as high as 0.25 MA/cm/sup 2/ with T/sub c,zero/ of 90.6 K.         New chemical route for YBCO thin films    H.Y. Lee, S.I. Kim, Y.C. Lee, Y.P. Hong, Y.H. Park and K.H. Ko Summary: Sol-gel derived coating of YBCO film is very attractive for low cost as well as the ease of scalability. Among them, TFA-MOD using metal trifluoroacetates helps avoid the formation of BaCO/sub 3/ in the film. But this process has difficulties in optimizing the humid atmosphere to remove HF from the Y-Ba-Cu-O-F systems. So, in this work, another approach to chemical solution without fluorinated precursor was investigated. To make homogeneous stable solution, at first, YBCO powders were synthesized from organic solution containing Y/sub 2/O/sub 3/, BaCO/sub 3/, and CuO powders followed by calcination in air. Dip coatings were carried out from the solution of calcined YBCO powder dissolved into a mixture of methanol and propionic acid on LaAlO/sub 3/ [100] substrates. The coated film was annealed by reduced oxygen partial pressure. Dense, homogeneous and biepitaxially grown YBCO films were obtained from dip coating with /spl sim/5 mm/s of drawing speed.         Calcining conditions for YBa/sub 2/Cu/sub 3/O/sub 7-x/ films by metalorganic deposition using trifluoroacetates    T. Niwa, T. Araki, T. Muroga, Y. Iijima, Y. Yamada, T. Saitoh, I. Hirabayashi and Y. Shiohara Summary: We investigated calcining conditions for YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) films by metalorganic deposition using trifluoroacetates. We measured residual carbon content by secondary ion mass spectroscopy (SIMS) and critical current density J/sub c/ values of the films calcined with various heat treatments. Precursor films are decomposed in calcining duration at 200 to 250/spl deg/C, and simultaneously harmful residue such as carbon content is generated. SIMS results of carbon intensity show calcination is more effective than extension of the duration at 200 to 250/spl deg/C to reduce carbon content. J/sub c/ values of films with the calcination varied with the duration, reaching a maximum at about 10 hours. The J/sub c/ values of the films depend on decomposition of trifluoroacetates and CuO nanocrystallites growth, rather than the influence of carbon content. We have succeeded in fabricating the YBCO films of 217 to 241 nm thickness with high J/sub c/ values; 1.7 to 2.9 MA/cm/sup 2/ (77 K, 0 T) on CeO/sub 2//Gd/sub 2/Zr/sub 2/O/sub 7//hastelloy -C.         Chemical solution deposition (CSD) of YBa/sub 2/Cu/sub 3/O/sub 7-x/ films and oxide buffer layers by dip coating    M. Falter, K. Demmler, W. Hassler, B. Schlobach, B. Holzapfel and L. Schultz Summary: Superconducting YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) thin films were prepared via chemical solution deposition (CSD) in a trifluoroacetate (TFA) process. The dip coated substrates were treated in a two stage annealing process. We obtained epitaxially grown 190 nm thick films on single-crystalline strontium titanate with T/sub c/ of 89.9 K and a transition width of 0.7 K. Critical current densities up to 4 MA/cm/sup 2/ were reached. The interface between the substrate and the YBCO is sharp even on an atomic level. Biaxially textured strontium titanate films and ytterbium oxide films as buffer layers were also built in a TFA process on single-crystalline substrates. Biaxially textured CeO/sub 2/ buffer layers were deposited on nickel RABITS using a nonfluorine precursor.         Silver doped YBCO coated conductor development by sol-gel process    Z. Aslanoglu, Y. Akin, M.I. El-Kawni, L. Arda, W. Sigmund and Y.S. Hascicek Summary: The nonfluorinated YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) coated conductors with 1-3 wt%Ag have been fabricated by sol-gel process. Ag doped YBCO films were fabricated on CeO/sub 2//YSZ/CeO/sub 2/ buffer layered Ni tapes by continuous sol-gel dip coating process. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) analysis were used to characterize the YBCO coated conductor. The superconducting properties (T/sub c/ and J/sub c/) of Ag doped YBCO coated conductors were found to be higher than those of the un-doped conductors. The Ag doped YBCO has a T/sub c,zero/ of 88 K and J/sub c/ of 1.0/spl times/10/sup 5/ A/cm/sup 2/.         Texture development and superconducting properties of YBCO thick films deposited on buffered metal substrates at various deposition rates    Yijie Li, K. Zdun, L. Hope, J. Xie, S. Corcoran, Y. Qiao, J. Reeves, K. Lenseth and V. Selvamanickam Summary: YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) thick films have been grown on buffered metal substrates at different deposition rates by pulsed laser deposition (PLD). In-plane texture and superconducting properties of YBCO films have been systematically investigated. It was observed that the in-situ epitaxial growth of YBCO films on buffered metal substrates could be achieved at a very high deposition rate. Under the optimized deposition conditions, X-ray diffraction measurements showed that both in-plane and out-plane texture of YBCO films were mainly dependent on the texture quality of the buffer-layer not the deposition rate. As the deposition rate increased from 1 nm/s to 30 nm/s, the average phi-scan rocking curve of YBCO films was only increased from 10 degree to 12 degree. The omega scan rocking curves kept the same FWHM value of 2 degree. Critical current densities J/sub c/ of the order of 10/sup 6/ A/cm/sup 2/ at 77 K and self-field have been achieved at high deposition rate of 30 nm/s by optimizing deposition parameters. Our results demonstrate the practical possibility of YBCO thick film processing at very high deposition rate by PLD on buffered metal substrates.         Optimization of surface morphology and electrical parameters of Tl-Ba-Ca-Cu-O thin films for high frequency devices    H. Schneidewind and T. Stelzner Summary: We prepared double-sided Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ (Tl-2212) thin films on large area sapphire substrates (up to 3 inch) for high frequency filters, which are intended to be used in future communication systems. For high frequency operation one demands film thicknesses three or four times the penetration depth /spl lambda/, but the thin film preparation process has several limits for the film thickness. Beside the crack formation on sapphire substrates due to different thermal expansion coefficients the surface morphology with parameters as roughness or the formation of precipitates depend on the film thickness. We show results of an optimization process to achieve the best suitability of the films for high frequency devices. The investigations were done in terms of SEM and AFM surface inspections as well as the measurement of electrical film parameters as critical temperature T/sub c/, critical current density J/sub c/, or surface resistance R/sub s/.         Superconducting Hg-Ba-Ca-Cu-O thin films on lanthanum aluminate and sapphire substrates    T. Stelzner, H. Schneidewind and G. Bruchlos Summary: Epitaxial c-axis-oriented HgBa/sub 2/CaCu/sub 2/O/sub 6+/spl delta// (Hg-1212) thin films have been prepared on lanthanum aluminate as well as on CeO/sub 2/ buffered r-plane sapphire substrates using a Tl-Hg cation-exchange process. Films on LaAlO/sub 3/ exhibited superconducting transition temperatures (T/sub c/) up to 122 K and critical current densities in the range of 2.2-3.1 MA/cm/sup 2/ at 77 K and under self-field. For the microwave surface resistance (R/sub s/) values of /spl sim/4 m/spl Omega/ at 17.86 GHz and 77 K have been obtained. In comparison, films on sapphire substrates with T/sub c/ values up to 118 K showed critical current densities in the range of 0.7-1.0 MA/cm/sup 2/ and R/sub s/ values of /spl sim/7 m/spl Omega/. With further optimization of processing an improvement of superconducting properties of Hg-1212 films on sapphire substrates is expected.         Optical emission spectroscopy of the plasma during sputter deposition of YBCO films for microwave applications    V.N. Tsaneva, T.C. Nurgaliev, T.I. Donchev, M.E. Vickers, J.H. Durrell, A. Purnell, L.F. Cohen and Z.H. Barber Summary: YBCO thin films are currently used in several HTS-based electronics applications. The performance of devices, which may include microwave passive components (filters, resonators), grain boundary junctions or spintronic multilayer structures, is determined by film quality, which in turn depends on the deposition technology used and growth parameters. We report on results from nonintrusive Optical Emission Spectroscopy of the plasma during YBCO thin film deposition in a high-pressure on-axis sputtering system under different conditions, including small trace gas additions to the sputtering gas. We correlate these results with the compositional and structural changes which affect the DC and microwave properties of YBCO films. Film morphology, composition, structure and in- and out-of-plane orientation were assessed; T/sub c/ and microwave surface resistance measurements were made using inductive and resonator techniques. Comparison was made with films sputtered in an off-axis 2-opposing magnetron system.         Growth and characterization of NdBa/sub 2/Cu/sub 3/O/sub 7/ and Ca-doped NdBa/sub 2/Cu/sub 3/O/sub 7/ thin films    R. Palai, E.J. Romans, Y.C. Fan, G.B. Donaldson and C.M. Pegrum Summary: Thin films of off-stoichiometric NdBaCuO (NBCO) and Ca-doped NdBaCuO were grown on (10 mm)/sup 2/ strontium titanate substrates by pulsed laser deposition. The statistical methods of Experimental Design and regression analysis were used to correlate the electrical and morphological properties with the growth parameters. The surface morphology of the films was studied using atomic force microscopy and scanning tunnelling microscopy.         Influence of sequential etching on YBCO films deposited by PLD from a nanostructured target    H. Huhtinen, J. Raittila, P. Paturi, V.-P. Huhtala, S. Mattila and J. Salminen Summary: Thin YBa/sub 2/Cu/sub 3/O/sub 6+x/ (YBCO) films with T/sub c/ = 90 K and high critical current in the order of 10/sup 7/ A/cm/sup 2/ at 77 K are prepared with pulsed laser deposition from a nanostructured target. Changes in the superconducting and structural properties of the films are investigated after repeated thinning by Ar-ion sputtering or by electrochemical etching. As shown by Auger depth profiling, the chemical composition is preserved through the film during Ar-ion sputtering while electrochemical etching changes the atomic concentrations and surface structures. Investigations by SQUID magnetometry and by conventional resistivity measurements give evidence that the dependence of T/sub c/ on the film thickness is similar to as-prepared ultrathin films. The thickness dependence of J/sub c/ indicates an excess of pinning centers on the surface of the as-deposited film.         Fabrication of meander shaped RE123 LPE films for PCS materials    M. Kai, A. Inoue, S. Hoshi, T. Izumi, K. Murata and Y. Shiohara Summary: We have fabricated a meander shaped LPE film to realize a high electric resistance in the normal state as a persistent current switch material. A seed film on an MgO single crystalline substrate was shaped into a meander by a chemical etching method and dipped into solution for further LPE growth of RE123. The meander shaped RE123 LPE film with a long current path on the 2 inch diameter MgO substrate could be successfully grown. This phenomenon can be explained by the change of the growth mode from step growth to a nucleation limited growth on the a(b)-c plane of the crystal. This is further explained by the small step-advancing rate of the RE123 crystal on the MgO surface and above a partly dissolved MgO substrate. The film revealed a high resistance value of about 1.7 /spl Omega/ at 100 K and a high I/sub c/ value of 50 A at 77 K and 0 T which is estimated to about 175 A at 20 K and 3 T.         Growth mechanism and surface morphologies of Sm/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub 6+y/ thin films    Y. Yoshida, K. Sudoh, Y. Ichino, I. Hirabayashi and Y. Takai Summary: In order to obtain high quality multilayer Sm/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub 6+y/ (SmBCO) coated conductors, it is indispensable to understand the surface growth mechanism of the SmBCO system. Using AFM, the step-and-terrace features due to 3D island growth are observed that are polygonal-like from the surface images. Steps and terrace width are approximately 1.2 nm in height and 30 nm in width, respectively. Spiral steps accompanied by screw dislocations were observed on the surface films of Ca doped SmBCO films. The spiral shapes of Ca doped SmBCO films are polygonal-like with width of /spl sim/ 80 nm. Using Ca-doping, the surface morphology of the SmBCO films changes from 3D island growth mode to spiral growth, and contributes to the flat surface of the SmBCO-multilayers.         Transport properties of YBCO superconducting films at different oxygen concentration    R.P. Cogollo, A.C. Marino and H.M. Sanchez Summary: The magnetic properties of YBCO(123) highly oriented thin films with different oxygen-contents were analyzed in the low magnetic field region. A decreasing of the oxygen content shifted the irreversibility line to lower temperatures and decreased the activation energy. The T/sub irr/(H) data for all the samples fitted well to a de Almeida-Thoules (AT)-like power law.         Growth by MOMBE of c-axis superconducting YBCO thin films on different substrates: in situ RHEED monitoring of the growth    K. Endo, P. Badica, Y. Moriyasu and K. Abe Summary: Superconducting YBCO c-axis oriented thin films have been grown by MOMBE (metalorganic molecular-beam-epitaxy). Growth of the films on different substrates [100] (Y,Nd)AlO/sub 3/, [100] SrTiO/sub 3/ and [100] MgO has been investigated by in situ monitoring the reflection high energy electron diffraction (RHEED). The paper discusses our results suggesting significant differences in films growth on the three presented substrates. The highest quality (high uniformity, epitaxy and low roughness) has been attained for the films prepared on SrTiO/sub 3/. All films, regardless substrates, have shown values between 81 and 84 K for zero resistance critical temperature T/sub c0/.         Magnetic field dependence of critical current density in Sm/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub 6+/spl delta// films prepared by pulsed laser deposition    K. Sudoh, Y. Ichino, Y. Yoshida, Y. Takai and I. Hirabayashi Summary: We have investigated Sm/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub 6+/spl delta// (SmBCO) films deposited by pulsed laser deposition technique using stoichiometric and Sm-rich SmBCO (x = 0.08) laser targets. In the SmBCO films deposited using the target of x = 0.08, the critical current density (J/sub c/) at 77 K with zero applied field was obtained 4.3 MA/cm/sup 2/ at film thickness of 1.1 /spl mu/m. To study the pinning mechanism of SmBCO films, we investigated the magnetic field (0 /spl sim/ 9 T) dependence of J/sub c/ for x = 0 and x = 0.08 films. From this result, we found the different behavior of the J/sub c/ between x = 0 and x = 0.08 films. We examined the difference of pinning mechanism from the scaling law and the microstructure of film using transmission electron microscopy.         Equivalence of the strain and doping dependence of the superconductive T/sub c/ in LaSrCuO: influence of the metal-insulator transition    M.S. Osofsky, R.J. Soulen Jr., Weidong Si, Xianghui Zeng, A. Soukiassian and Xiaoxing Xi Summary: It has long been known that oxygen doping, cation doping and strain all strongly influence the superconducting transition temperature, T/sub c/, of high temperature superconductors (HTS). These factors become especially important when thin films are prepared for electronic devices where sample uniformity and reproducibility are crucial. To date, there has been no detailed understanding of the comparative roles that each parameter plays in determining T/sub c/ and thus predicting what T/sub c/ will result from a particular process is problematic. We have shown that the very different strain and doping dependencies in the prototypical HTS material, LSCO, can be reduced to a common dependence upon the conductivity. The shape of the common phase boundary is related to the metal-insulator transition in accordance with that recently discovered for many other superconducting systems. The implication for this and other high T/sub c/ systems is that only one, easily measured parameter, conductivity, need be determined or controlled.         Carbon expelling scheme and required conditions for obtaining high-J/sub c/ YBa/sub 2/Cu/sub 3/O/sub 7-x/ film by metalorganic deposition using trifluoroacetates    T. Araki, T. Kato, T. Muroga, T. Niwa, T. Yuasa, H. Kurosaki, Y. Iijima, Y. Yamada, T. Hirayama, T. Saitoh, Y. Shiohara and I. Hirabayashi Summary: High critical current density (J/sub c/) YBa/sub 2/Cu/sub 3/O/sub 7-x/ films were routinely prepared by metalorganic deposition using trifluoroacetates (TFA-MOD). Although the growth scheme of the YBa/sub 2/Cu/sub 3/O/sub 7-x/ films has been studied, we still have two or more unsolved problems during heat-treatments. The first problem is chemical reaction, including the carbon-expelling scheme during the calcining process. Considering Gibbs free energy changes in the related chemical reactions and electronegativity of atoms, we explain the expelling scheme. During the calcining process metal-oxygen bonds remain after the decomposition. The fluorine partially attacks and replaces oxygen linked to Y and Ba. Consequently, these metal compounds become an amorphous matrix of metal oxyfluorides. Only CuO grows to be nanocrystalline. These results are consistent with the present precursor films derived from highly purified coating solution by the Solvent-Into-Gel method. The second problem is clarification of the required conditions to obtain high J/sub c/ YBCO film by TFA-MOD. Transmission electron microscopy revealed the existence of isolated Ba and Y oxides besides CuO grains within the YBa/sub 2/Cu/sub 3/O/sub 7-x/ layer, which are derived from the normally purified coating solution. Optimal calcining processing, which certainly suppresses only the CuO grains, never improves the J/sub c/ of the films containing Ba and Y oxides. Thus the required condition for high J/sub c/ YBa/sub 2/Cu/sub 3/O/sub 7-x/ films is a combination of a highly purified coating solution and an optimized calcining process. With that combination, we prepared 210 - 230 nm thick YBa/sub 2/Cu/sub 3/O/sub 7-x/ films on CeO/sub 2/ buffered YSZ for which the J/sub c/'s were 10.5 - 11.4 MA/cm/sup 2/ (77 K, 0 T) by four-probe transport measurement.         Surface morphology of (Hg,Re)Ba/sub 2/CaCu/sub 2/O/sub y/ thin films prepared by pulsed laser deposition    J.H. Su, P.V.P.S.S. Sastry and J. Schwartz Summary: (Hg,Re)Ba/sub 2/CaCu/sub 2/O/sub y/ thin films have been fabricated on [100] LaAlO/sub 3/ by reacting laser deposited Re/sub 0.2/Ba/sub 2/CaCu/sub 2/O/sub y/ precursor films with CaHgO/sub 2/ in sealed quartz tubes at 780/spl deg/C for times ranging between 0 h -16 h. The films reacted for more than 2 h exhibit high phase purity (Hg,Re)-1212 and good c-axis texture. Scanning electron microscopy and x-ray diffraction studies showed the existence of small amounts of a-axis oriented grains in all the reacted films. The root-mean-square roughness, measured by atomic force microscopy (AFM), increases initially with increase in heat treatment duration and saturates at /spl sim/300 nm after 4 h. The evolution of the surface roughness can be partially explained with a high nucleation density and the appearance of a three-dimensional structure during the initial stages of film growth and crystal coalescence at further growth. Two-dimensional planar growth with a one-unit-cell growth unit in the c direction was observed by AFM.         Synthesis and characterization of single crystalline REBa/sub 2/Cu/sub 3/O/sub 7-y/ thin film grown by tri-phase epitaxy    Kyung Sung Yun, Y. Matsumoto, S. Arisawa, Y. Takano, A. Ishii, T. Hatano, K. Togano, M. Kawasaki and H. Koinuma Summary: We report on the successful fabrication of single crystalline thin films of REBa/sub 2/Cu/sub 3/O/sub 7-y/ (RE123, RE: rare earth elements) using a novel process of Tri-Phase Epitaxy. This method is based on the application of pulsed laser deposition (PLD) under appropriate compositions and conditions predetermined from the relevant thermodynamic phase diagram. Prior to the growth of the film, a liquid phase film (near-eutectic composition of BaO-CuO) is intentionally formed. The RE123 single crystalline thin film is grown at the liquid-solid interface. The consumed RE123 in the liquid layer is compensated by the laser-ablated vapor and the composition of the liquid phase is kept constant. Thermodynamic equilibrium can be maintained at the liquid-solid film boundary while preserving the benefit of intrinsic stoichiometry control offered by the PLD technique. Atomically smooth film surface and single crystalline nature of film was verified by combined characterization methods of x-ray diffraction, atomic force microscopy and transmission electron microscopy.         Thickness dependence of critical currents and depth profiling of transport properties in high rate in-situ grown YBa/sub 2/Cu/sub 3/O/sub 7-x/ films    W. Jo, T. Ohnishi, J.U. Huh, R.H. Hammond and M.R. Beasley Summary: YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) films are grown by in-situ electron beam evaporation at high deposition rates (100/spl sim/350 /spl Aring//sec). The YBCO films are found to consist of two regions as a function of thickness: a region on the bottom with defect-free microstructure reflecting layer-by-layer growth and at the top a defected type reflecting island-growth. We suggested a new phase stability to explain this growth behavior, with Ba-Cu-O liquid fluxes. The films show critical current density greater than 2 MA/cm/sup 2/ on crystal substrates. Depth profiling of the transport properties (critical current density and resistivity) has been performed by etching the layers, elucidating that it is the island-growth layer where high critical current density is being carried.         Nonlinear surface impedance Z(T,f,H/sub rf/) of Tl-Ba-Ca-Cu-O thin films    E. Gaganidze, R. Heidinger, J. Halbritter, A. Shevchun, M. Trunin and H. Schneidewind Summary: YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) film quality has reached a stage enabling rf applications at T/spl les/80 K. Higher operating temperatures or better power handling are very much desired. Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ (Tl-2212) is a perfect candidate with its higher transition temperature T/sub c/>100 K. We studied the rf field dependence of the impedance Z/sub s/ of epitaxial Tl-2212, which shows already surface resistances at low fields superior to YBCO and promising power handling with a nonlinearity onset above /spl mu//sub 0/H/sup *//spl sime/3 mT. Defective Tl-2212 films show anomalous nonlinear behavior for /spl mu//sub 0/H/sub rf//spl les//spl mu//sub 0/H/sup *//spl sim/0.3 to 1 mT, extremely pronounced at T<40 K, indicating the presence of very weak-links yielding flux-flow, followed at higher fields /spl mu//sub 0/H/sub rf//spl ges/0.5 mT by hysteresis losses with a linear field dependence /spl delta/R/sub s/(H/sub rf/)/spl infin/H/sub rf/. Better quality Tl-2212 films show /spl delta/R/sub s/(H/sub rf/)/spl infin/H/sub rf//sup 2/ up to fields of about 5 to 10 mT. The /spl delta/R/sub s/(H/sub rf/)/spl infin/H/sub rf//sup n/ (n=1,2) dependencies together with the ratios r(T)=/spl delta/X/sub s///spl delta/R/sub s//spl sim/1 to 10 hint to hysteresis losses of Josephson fluxons enhanced by slits or holes in the films.         Epitaxial growth of multilayered YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta///Y/sub 0.7/Ca/sub 0.3/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// films for high current application    Y. Lin, Z. Wu, X. Chen, D.X. Huang, X.H. Chen, P. Hor, S.W. Liu, A. Jacobson and C.L. Chen Summary: Multilayered YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO)/Y/sub 0.7/Ca/sub 0.3/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YCBCO) films were epitaxially grown on [001] LaAlO/sub 3/ and [001] SrTiO/sub 3/ by using pulsed laser ablation. Constant-high critical current density (J/sub c/) of 106 A/cm/sup 2/ at 77 K has been achieved with the combination of multilayered YBCO and YCBCO layers for films with various thickness. The critical current density exhibits a high constant value for the multilayered structures indicating that the J/sub c/ in the superconductor films no longer decreases with the increase of the film thickness. The result verifies the model that interfaces can limit the density of dislocations that form in the film during the film growth. The artificial multilayered structures terminate the dislocations and the superconductive films at the optimal J/sub c/ conditions maintain a constant high J/sub c/ at various film thickness.         Faceting and critical current densities of [001] high-angle tilt boundaries in YBCO films    Siu-Wai Chan, Q. Jin, J.W.H. Tsai, S.C. Tidrow and Q. Jiang Summary: The [001] high-angle tilt boundaries in YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) thin films deposited on SrTiO/sub 3/ (STO) bicrystal substrates have been studied by Scanning Squid Microscopy (SSM) and transmission electron microscopy (TEM). Generally critical current density across a boundary decreases with increasing misorientation. However, misorientation angle is found to be insufficient to predict the J/sub c/ behavior of a YBCO grain boundary. The two inclination angles of the adjacent grains are found to be important parameters. In two separate cases of same misorientation but different inclinations, the boundaries exhibit drastically different superconducting behaviors and this has been observed by SSM imaging of Josephson vortices. The YBCO film boundary is not an exact copy of the design boundary of the substrate bicrystal template. YBCO boundaries meander due to island formation during film growth. These microscopically wavy boundaries contain straight segments of atomistic facets. Three energetic criteria that affect faceting have been identified. The particular criterion that a facet plane cannot be too deviated from the design boundary plane (/spl phi/<28/spl deg/) explains the strong effect of the design inclination angles on J/sub c/ despite extensive faceting. The original scattered values of J/sub c/ each calculated from individual fluxes of the same design boundary are likely to be a bona fide effect corresponding to individual facet having its own J/sub c/ and /spl lambda//sub j/ values.         Transmission electron microscopy on interface engineered superconducting thin films    S. Bals, G. Van Tendeloo, G. Rijnders, M. Huijben, V. Leca and D.H.A. Blank Summary: Transmission electron microscopy is used to evaluate different deposition techniques, which optimize the microstructure and physical properties of superconducting thin films. High-resolution electron microscopy proves that the use of an YBa/sub 2/Cu/sub 2/O/sub x/ buffer layer can avoid a variable interface configuration in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films grown on SrTiO/sub 3/. The growth can also be controlled at an atomic level by using sub-unit cell layer epitaxy, which results in films with high quality and few structural defects. Epitaxial strain in Sr/sub 0.85/La/sub 0.15/CuO/sub 2/ infinite layer thin films influences the critical temperature of these films, as well as the microstructure. Compressive stress is released by a modulated or a twinned microstructure, which eliminates superconductivity. On the other hand, also tensile strain seems to lower the critical temperature of the infinite layer.         Characterization of the interface between a normal metal and a superconductor using magnetic screening    R.J. Soulen Jr., J.H. Claassen, M.S. Osofsky, G. Trotter, G.T. Woods, Yu.N. Ovchinnikov, V. Kresen and N. Tralshawala Summary: We have predicted the behavior of magnetic screening of N/I/S trilayers as a function of a single parameter W that parameterizes the discontinuity of the order parameter at the interface. We have compared these calculations with experimental measurements of the temperature (10 K to 1.5 K) dependence of the magnetic screening for several Nb/NbO/Al trilayers and excellent agreement between the predictions and measurements is observed. This agreement provides further understanding of the proximity effect when characterizing the N/S interface in many devices.         Cuprate based oxide superlattices showing simultaneously superconducting and ferromagnetic properties    H.-U. Habermeier and G. Cristiani Summary: Superconductivity and ferromagnetism are antagonistic ordering phenomena and their coexistence in a material requires a spatial separation of the electronic systems giving rise to each of them. All oxide superlattices are good candidates to study the electronic interaction of superconductivity and ferromagnetism. Several types of YBa/sub 2/Cu/sub 3/O/sub 7-x//La/sub 2/3/Ca/sub 1/3/MnO/sub 3/ as well as YBa/sub 2/Cu/sub 3/O/sub 7-x//SrRuO/sub 3/ superlattices have been prepared by pulsed laser deposition and a reduction of both ordering temperatures as a function of superlattice composition has been studied. For the explanation of the results several novel concepts have to be developed based on a long-range ferromagnetic interlayer coupling and a novel long-range superconducting proximity effect.         Modeling thermal destruction of superconducting state in non-homogeneous HTS bridge    E.I. Vernoslova, K.A. Titkov, M.F. Sitnikova and I.B. Vendik Summary: Thermal destruction of the superconducting state has been investigated in the HTS bridge with given discontinuity. Temperature distribution and current amplitude distribution have been modeled along the bridge. Modeling has been done taking into account the dependence of the critical current density on temperature. The temperature distribution and the current amplitude distribution in case of the thermal destruction have been obtained at different input power levels. Analysis of the results has shown the influence of the thermal destruction on the current distribution in the bridge and the transmission coefficient S/sub 21/.         Critical current control in a superconducting thin film with a ferromagnetic layer    M.D. Allsworth, R.A. Chakalov, P. Mikheenko, M.S. Colclough and C.M. Muirhead Summary: We report suppression of the critical current of thin film YBa/sub 2/Cu/sub 3/O/sub 7/ layers by altering the magnetization of a ferromagnetic La/sub 0.67/Ca/sub 0.33/MnO/sub 3/ overlayer. We provide evidence that the critical current suppression is related to the spin-polarized state of the magnetic layer, rather than a direct magnetic influence. We argue that the spin diffusion length in the superconducting layer is small compared with the typical domain size in the ferromagnetic layer in its demagnetized state.         Structural, transport and magnetic characterization of Nd/sub 1-x/Sr/sub x/MnO/sub 3//YBa/sub 2/Cu/sub 3/O/sub 7/ heterostructures    P. Przyslupski, I. Komissarov, E. Dynowska, M. Sawicki, J. Wosik and A. Szewczyk Summary: Heteroepitaxial growth of multilayer thin films of Nd/sub 1-x/Sr/sub x/MnO/sub 3//YBa/sub 2/Cu/sub 3/O/sub 7/ (NSMO/YBCO) by high pressure sputtering for two doping level of NSMO system is reported. Multilayers containing NSMO oxide layer with lower Curie temperature (with lower doping level) show higher superconducting transition temperatures for fixed YBCO layer thickness. Such observations indicate that the proximity effect in NSMO/YBCO interfaces has a significant influence on the superconducting transition temperature of YBCO layers. Magnetization loops shows the coexistence of superconducting and ferromagnetic order at nm length scale.         The effect of starting material composition on the growth of Bi-based ribbon-like thin films    Yanjing Su, Y. Satoh, S. Arisawa, T. Awane, Y. Takano, A. Ishii, T. Hatano and K. Togano Summary: The effect of Pb addition and Ca, Cu enrichment in starting material on the formation of Bi-2212 ribbon-like thin films on a flat Ag substrate was studied. It was found that the addition of Pb to the starting material improves the wettability of the molten phase to Ag substrate and facilitates the growth of ribbon-like thin films, and that the increase of amount of Ca and Cu in starting material suppresses the intergrowth of Bi-2201 phase in Bi-2212 ribbon-like thin films. Using (Bi, Pb)-2246 powders, with nominal composition of Bi/sub 1.6/Pb/sub 0.4/Sr/sub 1.6/Ca/sub 3.2/Cu/sub 4.8/O/sub y/, as starting material, the superconducting Bi-2212 ribbon-like thin films with an onset T/sub c/ at 74 K were successfully synthesized on a flat Ag substrate.         Characterization of Si-CeO/sub 2/-YBCO tri-layers grown by magnetron sputtering    A. Chiodoni, D. Andreone, D. Botta, C. Camerlingo, F. Fabbri, R. Gerbaldo, G. Ghigo, L. Gozzelino, F. Laviano, B. Minetti, C.F. Pirri, G. Tallarida, E. Tresso and E. Mezzetti Summary: Material aspects of heterostructural Si/CeO/sub 2/, fabricated by magnetron sputtering as buffered substrates for sputtered YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) films, are studied by means of X-ray diffraction, AFM, Raman and SIMS-ToF analysis. Different Si/CeO/sub 2/ layouts are chosen and tri-layers Si/CeO/sub 2//YBCO, grown on the respective bi-layer substrates, are preliminary analyzed. Outstanding material issues suggest that in the framework of sputtering technology, epitaxy is out of reach for Si/CeO/sub 2//YBCO multi-layers. However, the results point toward the scalability/integrability of the technology with silicon processing when the main target consists of networking for integrated electronics.         Sprayed Tl-1223 films: formation kinetics and superconducting properties    S. Phok, P. Galez, J.-L. Jorda, C. Peroz, C. Villard, D. De-Barros and F. Weiss Summary: TlBa/sub 2/Ca/sub 2/Cu/sub 3/O/sub 9/ superconducting films, 0.5 to 1 /spl mu/m in thickness, have been prepared in a two step process. Using a nitrate solution, a precursor layer with composition Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ is first sprayed on a LaAlO/sub 3/ heated substrate and then thallinated, following a procedure established for bulk samples. The critical temperature of the films ranges from 108 to 113 K, and the critical current density of the best samples reaches 0.7 MA/cm/sup 2/. The reaction kinetics for the formation of the Tl-1223 phase between 880 /spl deg/C and 910 /spl deg/C has been studied for a better control of the grain growth and texture. The effect of fluorine addition on both the microstructure and superconducting properties have been also analyzed.         PLD of large area films onto substrate undergoing translational motion by mask method    A.S. Kuzanyan Summary: The simple method of laser deposition of large area uniform-thickness films onto a moving ribbon of width up to 100 mm is proposed. The peculiarity of the method is the laser deposition of compound upon a substrate through a mask placed in immediate proximity of the substrate. Various configurations of mask slits that provide thickness uniformity of deposited films are considered. The precise sizes of slits in the masks are calculated using the data of an angular distribution of mass transfer of a deposited compound in a plasma plume. Given the advantage of laser deposition, the offered method should find practical uses, in particular, in the manufacture of superconducting ribbons.         Microstructure control in the growth of large area Tl-2212 thin films    Houzheng Wu, S.C. Speller, S. Pal, D.J. Edwards and C.R.M. Grovenor Summary: Large area high temperature superconducting thin films are needed for the implementation of a range of passive microwave devices. We have been investigating the critical processing issues that control the surface resistance values in 2 inch films grown on lanthanum aluminate substrates, including the possibility of batch processing wafers in a vertical geometry. We have shown that the microstructure of vertically-processed films shows a systematic variation in microstructure from top to bottom which can seriously degrade the uniformity of the superconducting properties. We have also used electron backscattered diffraction to analyze the fine-scale mosaic structure of thin films of varying thickness and processing conditions to show that the best surface resistance values are not found in films with the sharpest epitaxial relationship between the substrate and film. We propose an explanation for this counterintuitive observation based on how the films can relieve stresses generated during processing.         Microwave properties of large YBCO films on as-prepared and annealed MgO substrates    J.H. Lee, J. Lim, S.H. Moon, J.H. Yun, Y.H. Choi, B. Oh and Sang Young Lee Summary: We have studied the microwave surface impedance of large YBCO films on as-prepared MgO substrates and on annealed MgO substrates with 50 mm in diameter. YBCO films were prepared by pulsed laser deposition. The surface resistance (R/sub S/), homogeneity in the R/sub S/, and structural properties of YBCO on annealed MgO appeared improved compared with those of YBCO on as-prepared MgO. The reduced R/sub S/ of YBCO films on annealed MgO is attributed to improved in-plane orientation of the YBCO grains in the films with local variations in the in-plane orientation of YBCO grains correlated well with the R/sub S/ for both YBCO films on as-prepared MgO and those on annealed MgO.         YBa/sub 2/Cu/sub 3/O/sub 7-x/ deposition of large moving plates for continuous processing    C. Hoffmann, A. Lumkemann, U. Schmatz, M. Bauer, R. Metzger, P. Berberich and H. Kinder Summary: YBa/sub 2/Cu/sub 3/O/sub 7-x/ thin films can be deposited on substrates up to 20 cm /spl times/ 20 cm using thermal reactive co-evaporation with a linear reciprocating oxygen pocket. In order to coat larger area or in a continuous way, the substrate has to be moved through the deposition zone. Therefore, the substrate is fixed in a slide and shuttled by a transport system. On small samples critical current densities (J/sub c/) over 3 MA/cm/sup 2/ were achieved while on 10 cm /spl times/ 20 cm sapphire substrates a J/sub c/ of 2.2 MA/cm/sup 2/ could be reached. On ion-beam-assisted deposition (IBAD) buffered aluminum oxide ceramic we attain critical current densities of 1.4 MA/cm/sup 2/ and 1.5 MA/cm/sup 2/ on IBAD buffered metal tapes.         Electrical conductivity relaxation studies of oxygen transport in epitaxial YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films    Ling Chen, C.L. Chen and A.J. Jacobson Summary: The oxygen transport behavior in c-axis-oriented YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films has been investigated by means of electrical conductivity relaxation measurements. The oxygen surface exchange coefficients have been determined from the out- and in-diffusion when the oxygen partial pressure was switched between pO/sub 2/ = 0.01 atm and 0.02 atm at temperatures of 773 K to 873 K. The results are described by a model in which oxygen molecules dissociated at two different surface sites, diffuse rapidly along the grain boundaries which act as "chimneys." The bulk stoichiometry then adjusts by fast diffusion in the ab-planes. The overall transport kinetics are limited by the surface reactions. The activation energy for both surface exchange controlled processes are /spl sim/ 1.0 eV. An understanding of the effects of grain boundaries on the transport properties of thin YBCO films is important for the potential application of these materials.         Y-Ba-Cu-O grain boundary resistivity above and below the critical temperature    J.H.T. Ransley, S.H. Mennema, G. Burnell, U. Balasumbramaniam, E.J. Tarte, M.G. Blamire, J.E. Evetts, Jeong-Il Kye and Byungdu Oh Summary: The interface resistance of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// grain boundaries has been measured in the range 5-270 K by means of a Wheatstone bridge for 24/spl deg/, 30/spl deg/ and 36/spl deg/ symmetric and 45/spl deg/ degree asymmetric, [001] tilt, thin film grain boundaries. A number of preliminary experiments have demonstrated the validity of the technique employed. Above T/sub c/, the grain boundary resistance decreases as the temperature is increased, and the temperature variation is more pronounced for higher angle boundaries. A number of possibilities for interpreting the data are considered.         Enhancement of the transport properties in a-axis oriented YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films by calcium doping    M.-P. Delamare, S. Tonies, J.D. Pedarnig, A. Vostner, D. Bauerle and H.W. Weber Summary: High critical current densities (J/sub c/) are required for applications, but grain boundaries suppress the attainable J/sub c/ values. Because of the presence of 90/spl deg/ grain boundaries and because of poor structural and electrical properties, a-axis thin films are of great interest to investigate the role played by Y/sub 0.8/Ca/sub 0.2/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YCaBCO) cap layers in the transport properties. The transport critical current densities of the films under various magnetic fields and the angular dependence of J/sub c/ at fixed temperature were measured before and after irradiation. A thin YCaBCO cap layer deposited on top of a-axis oriented YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) films, is found to improve the electrical transport properties. Ca-doping decreases the resistivity and strongly increases J/sub c/ of a-axis oriented YBCO films. Furthermore, strong pinning by 90/spl deg/ grain boundaries was observed.         Spatial distribution analysis of critical temperature in epitaxial Y-Ba-Cu-O film using variable temperature scanning laser microscopy    C. Kwon, L.B. Wang, S. Seo, B.H. Park and Q.X. Jia Summary: We have investigated the spatial distribution of superconducting transition in an epitaxial YBa/sub 2/Cu/sub 3/O/sub 7/ film using variable temperature scanning laser microscope (VTSLM). VTSLM creates an image of the ac voltage response, /spl delta/V(x,y), due to an ac modulated laser beam, which is proportional to dRdT(x,y). In the resistive transition region, there is a strong correlation between the VTSLM images and the resistance of the sample. When the sample is making a poor thermal contact to the heat bath, the large /spl delta/V(x,y) region shifts toward the ends of the bridge while the sample resistance decreases. This result is due to the variation of surface temperature along the sample created by the heating at the contact resistance and/or the poor thermal contact between the sample and the heat bath. However, even after improving thermal contact, we still observe the distribution of superconducting transition. Since the local superconducting transition occurs within 1 K, we conclude that any samples with superconducting transition width larger than 1 K have local nonuniformity.         Current distribution in Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// disk-shaped thin film by scanning Hall probe measurements    H. Darhmaoui and J. Jung Summary: We have measured the shielding and trapped (remanent) magnetic field profiles both perpendicular (H/sub z/(r)) and parallel (H/sub r/(r)) to the planes of a zero-field-cooled disk-shaped YBCO thin film. H/sub z/(r) and H/sub r/(r) were obtained using transverse and radial scanning Hall probes at various temperatures ranging from 30 K to 70 K and at small magnetic fields up to 750 G. The current distributions in the samples were inferred from a direct comparison of our experimental profiles to the theoretical ones obtained using the critical state models by Mikheenko et al. (1993) and Zhu et al. (1993). The models are in good agreement with the experimental trapped field profiles; however field dependence of the current should be taken into account for the shielding profiles.         Spatially resolved characterization of the microwave properties of superconducting thin films by low temperature microwave scanning near-field microscopy    Y.J. Feng, L.Y. Wu, K.L. Wang, T. Jiang, L. Kang, S.Z. Yang and P.H. Wu Summary: In this paper, we established a microwave scanning near-field microscope to characterize the local microwave properties of high temperature superconducting thin film and devices. Using a coaxial cavity together with a niobium tip as the probe, the microwave surface resistance can be imaged nondestructively at 3 GHz for thin film samples with a spatial resolution of several micrometers. Temperature dependence of the local microwave property can also be obtained through a temperature controlled sample stage cooled by liquid nitrogen. With this technique, we have studied the local microwave characteristics, especially the microwave surface resistance of the high temperature superconducting thin film and device. We believe this technique would be quite helpful in evaluating and improving the performance of the superconducting microwave devices.         Influence of impedance mismatch effects on measurements of unloaded Q factors of transmission mode dielectric resonators    K.T. Leong, J.C. Booth and Sang Young Lee Summary: Precise measurements of the surface resistance of high temperature superconducting (HTS) thin films using transmission mode dielectric resonators requires accurate knowledge of the unloaded Q factor (Q/sub o/). So far, the most accurate method of Q/sub o/ determination for transmission mode resonators is the transmission mode Q factor (TMQF) technique based on the processing of S-parameters (S/sub 21/, S/sub 11/, S/sub 22/). The technique accounts for parasitic effects including noise, crosstalk, coupling reactance and coupling losses but does not yet take into account the impedance mismatch between the test ports of the vector network analyzer and the inputs to the resonator. Discrepancies between measured and ideal S-parameters due to the mismatch lead to inaccuracies in coupling coefficient computations. This causes undesirable error in the calculated Q/sub o/. We present measurements of Q/sub o/ obtained using the TMQF technique for mismatched and matched connections between the test ports of the vector network analyzer and the inputs to the dielectric resonator. These results are compared with values obtained using the traditional insertion loss method.         Surface resistance measurements of HTS thin films using SLAO dielectric resonator    M.V. Jacob, J. Mazierska, K. Leong, D. Ledenyov and J. Krupka Summary: Surface resistance of HTS films is typically measured using sapphire dielectric rod resonators enclosed in a copper cavity. In this paper we present surface resistance measurements of YBa/sub 2/Cu/sub 3/O/sub 7/ films using strontium lanthanum aluminate (SLAO) at a resonant frequency of 18.2 GHz. We have performed the error analysis of the cavity loaded with SLAO dielectric rod and also verification measurements using two sapphire (Al/sub 2/O/sub 3/) rod resonators operating at resonant frequencies of 24.6 GHz and 10 GHz respectively. Good agreement between the values of R/sub s/ of two sets of YBCO films measured using the SLAO and the sapphire dielectrics has been obtained after a frequency scaling of R/sub s/ was applied. Using different dielectric rods of the same size in the same cavity for measurements of R/sub s/ of HTS films it is feasible to do microwave characterization of the same films at differing frequencies.         Preparation of Tl-2212 and Tl-1223 superconductor thin films and their microwave surface resistance    A. Sundaresan, H. Asada, A. Crisan, J.C. Nie, H. Kito, A. Iyo, Y. Tanaka, M. Kusunoki and S. Ohshima Summary: Epitaxial Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub y/ and Tl(Ba,Sr)/sub 2/Ca/sub 2/Cu/sub 3/O/sub y/ thin films have been prepared on CeO/sub 2/ buffered sapphire substrate by an ex situ process with high reproducibility. Microstructure analysis of the surface of the Tl-2212 films showed well connected and smaller sized grains of 1 /spl mu/m or less. In the case of Tl-1223 film, plate-like crystals with pits and pin holes could be observed. The superconducting critical temperatures of both films are around 96 K. Critical current density measured by ac susceptibility technique is as high as 1 MA/cm/sup 2/ at 77 K. The microwave surface resistance of these films was measured over a wide range of temperatures by a HTS-sapphire-HTS resonator method at 38 GHz on films with area 10 mm /spl times/ 10 mm. The temperature dependence of surface resistance of Tl-2212 film follows very closely to that of the best YBCO films on MgO substrate, whereas the Tl-1223 exhibits slightly higher values resulting from an inferior surface morphology.         Nonlinear microwave properties of HTS thin film coplanar devices    P. Lahl and R. Wordenweber Summary: It is demonstrated that the combination of vortex matter and rf measurements yields new insight into the microwave properties of superconducting thin film devices, both in small magnetic fields and zero field. The comparison of field-cooled and different types of field sweep experiments on coplanar high-T/sub c/ thin film resonators shows that the microwave properties strongly depend on magnetization and vortex distribution in the superconducting film as well as on the way, the magnetic field is approached. Thus, using vortices as a kind of local probe for the microwave properties leads to a consistent explanation of the microwave power handling in nonzero and zero magnetic field. In a model that is derived from the experiments, the nonlinear microwave behavior is explained by the limitation of the total current density in the device considering contributions of the rf field and the screening of the magnetic field and vortices to the current. The limiting current value seems to be related to the dc critical current of the superconductor.         Microstructure and J/sub c/ improvements in overpressure processed Ag-sheathed Bi-2223 tapes    Y. Yuan, J. Jiang, X.Y. Cai, S. Patnaik, A.A. Polyanskii, E.E. Hellstrom, D.C. Larbalestier, R.K. Williams and Y. Huang Summary: Overpressure (OP) processing influences the microstructure and critical current density (J/sub c/) of Ag sheathed Bi-2223 tapes. SEM and mass density measurements show higher core density and fewer micro-cracks in OP tape than in 1 atm tape. The self-field critical current density, J/sub c/ (0 T, 77 K) in multifilamentary tapes was increased from 33.5 kA/cm/sup 2/ with 1 atm processing (1 atm IR) to 48 kA/cm/sup 2/ with OP processing (OP pressure = 148 atm) after the first heat treatment (OP HT1), and to 58.7 kA/cm/sup 2/ with OP processing after intermediate rolling (OP IR). The corresponding values for J/sub c/ (0.1 T, 77 K) are 12.3 kA/cm/sup 2/ (1 atm IR) to 18.2 kA/cm/sup 2/ for OP HT1 and to 22.4 kA/cm/sup 2/ for OP IR.         Characterization of individual filaments extracted from a Bi-2223/Ag tape    O. van der Meer, Xueyu Cai, Jianyi Jiang, R.D. Parella, Y.B. Huang, D.C. Larbalestier, Bt. Haken and H.H.J. Ten Kate Summary: Previous studies suggest that there is a significant variation in both shape and physical properties from filament to filament in a multifilament superconducting Bi-2223/Ag tape. We are investigating this variation for a tape with a high critical current density (J/sub c/). For this study, we extracted all the filaments from a specially prepared high-quality tape having J/sub c/ (0 T, 77 K) = 45 kA/cm/sup 2/ with 19 disconnected filaments. By attaching current leads and voltage taps to the filaments, we are able to measure electrical properties on a scale of 200-300 /spl mu/m. The experiments show a large variation in filament properties. The conductivity of a filament at room temperature is proportional to its critical current density J/sub c/ at 77 K (self-field) and filaments with a higher transition temperature T/sub c/ do also show a higher J/sub c/. There is also a variation in the magnetic field behavior of the filaments. SEM pictures of the filaments also show large variations. The filaments from the center of the tape, which are thinner and have a larger aspect ratio (and thus a larger silver-filament interface), show better grain alignment and fewer impurities than filaments from the edges.         Local measurement of current density by magneto-optical current reconstruction in normally and overpressure processed Bi-2223 tapes    S. Patnaik, D.M. Feldmann, A.A. Polyanskii, Y. Yuan, J. Jiang, X.Y. Cai, E.E. Hellstrom, D.C. Larbalestier and Y. Huang Summary: Magneto-optical current reconstruction has been used for detailed analysis of the local critical current density (J/sub c/) variation in monocore Bi-2223 tapes. We find, even in high quality tapes with bulk transport j/sub c//spl sim/40 kA/cm/sup 2/ (77 K, 0 T), that there exist local regions which possess current densities of more than 200 kA/cm/sup 2/. Overpressure processing at 148 bar significantly improved J/sub c/ to 48 kA/cm/sup 2/ by improving the connectivity. For the overpressure-processed sample we find that the current distribution is more uniform and that the maximum local current density at 77 K is increased almost to 300 kA/cm/sup 2/.         On the limiting mechanism of irradiation enhancement of I/sub c/    A. Gandini, R. Weinstein, D. Parks, R.P. Sawh and Shi Xue Dou Summary: Irradiation may significantly increase I/sub c/ in HTS. A systematic pattern occurs: R=I/sub c/(afterirr.)/I/sub c/(beforeirr.) increases at low defect density, d. It reaches a peak, and then it falls below 1 at high d. The pinning center mechanism, which causes R to increase, has been extensively studied. The falloff in R has not. It has been considered a secondary effect. Here, we will show that the fall-off plays an important role in determining the maximum I/sub c/ enhancement achievable. A phenomenological model to describe the R-vs.-d curve, over the entire d range, is proposed. The idea is that R is the product of two competing effects. (i) Irradiation damage acts as pinning centers, hence increases critical current density, J/sub c/. (ii) Damage reduces the flow-area. Hence, it decreases the net critical current. Data on U/n processed Bi-2223 tapes are fitted to this model. The fitting indicates: (1) the reduction of the flow-area accounts for the majority of the R falloff; and (2) It is sufficient to describe J/sub c/ enhancement as linear with d, and it depending on field and temperature only through the ratio b=B/B/sub irr/, where B/sub irr/ is the irreversible field before irradiation.         Kinetics of phase formation and transport properties of Bi-2223/Ag tapes fabricated by various calcined powders    Chunhai Jiang, Jaimoo Yoo, Jaewoong Ko, Hyungsik Chung and Guiwen Qiao Summary: The kinetics of phase formation and transport properties of Bi-2223/Ag tapes fabricated by precursor powders with different phase assemblages have been studied. Our results show that the formation process of 2223 phase is strongly related to the secondary phases in precursors. A variation of the reaction-order, n, deduced from the Avrami relation, was observed along with the whole sintering processing. Within a sintering period of 65 h, n keeps the value of 0.7 for the tape made from the powder calcined at 830/spl deg/C, while it changes from 0.3 or 0.4 to 1 for the tapes prepared with the powders calcined at 810/spl deg/C and 820/spl deg/C. Based on the analysis of phase formation and transport properties, the optimum calcination conditions for achieving high J/sub c/ tapes are discussed.         Reduction in secondary phases and increased transport I/sub c/ of (Bi,Pb)2223/Ag tapes sintered with rapid heating rates    E.A. Young, Y. Yang, M. Lehmann, R. Riddle and C. Beduz Summary: In a two-step heat treatment with one intermediate rolling the final transport critical current, (I/sub c/ at 77 K, self field, 1/spl inodot//spl grave/V/cm), of 37 filament (Bi,Pb)2223/Ag tapes increases linearly with the heating ramp rate: 20 A to 40 A, (/spl sim/20,000 Acm/sup -2/), for 20/spl deg/C/hour to 400/spl deg/C/hour. The principle benefit of the rapid ramp rate is likely to come from ramping fast though 800/spl deg/C to 832/spl deg/C in the 1st heat treatment. SEM and XRD analysis on the superconductor-Ag interface show a decrease in the amount of secondary phases, Cu/sub 2/O, Bi/sub 2/(Sr,Ca)/sub 2/Cu/sub 1/O/sub x/, Bi(Sr,Ca)O/sub x/, with increasing ramp rate and critical current.         Irreversibility fields of Bi-2223 at 30-77 K    J.G. Chandler, J. Jiang, X.Y. Cai, L.A. Schwartzkopf and D.C. Larbalestier Summary: Significant differences exist, of order a factor of two, in irreversibility field at 77 K of Ag-clad (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ (Bi-2223) composites from different sources. In the present case, we have studied the 30-77 K irreversibility field and J/sub c/ performance of post annealed Bi-2223 samples. Post annealing in the temperature range 800-750/spl deg/C significantly raises both J/sub c/ and the irreversibility field. At 77 K, the irreversibility field was characterized both by the decrement field, H/sub p/, defined by J/sub c/(H)/spl prop/exp(-H/H/sub p/) and by the glass transition field, H/sub g/, defined by the change in sign of the curvature of the voltage-current characteristics. At lower temperatures, where only magnetization measurements were made, H/sub p/ and the Kramer function extrapolation field, H/sub K/ were used. H/sub p/ (77 K) ranges from 0.143-0.170 T and H/sub g/ (77 K) from 0.082-0.164 T. Higher post annealing temperatures produced larger values of both H/sub K/ and H/sub p/ at 30-50 K. H/sub K/ (30 K) varied from 8-10 T. Two tapes from leading manufacturers had H/sub K/ (30 K) values of 7.3 and 10 T, bracketing the results obtained in our post-annealed tapes. We conclude that sample-to-sample variations of irreversibility field at 77 K carry over to lower temperatures too and that optimizing the irreversibility field properties at 77 K is very valuable for lower temperature Bi-2223 performance too.         Electrical degradation of a high-T/sub c/ superconductor by continuous current transport    Duck Kweon Bae, Sang-Jin Lee, Joon Han Bae, K.D. Sim, Kyong Yop Park and Tae Kuk Ko Summary: Several companies in the world are marketing superconducting products, such as wires, films, and bulk, and so on. High-T/sub c/ superconducting (HTS) systems have begun to be commercialized with these HTS products, and the demand for them is increasing. A database on the electrical degradation of high-T/sub c/ superconductors is an essential requirement to commercialize HTS systems. The electrical degradation of Bi-2223 wire has been investigated in this paper. To simulate the conditions of real systems, two types of specimens were prepared. One was named Ring Specimen with Bi-2223 wire on a bobbin of 400 mm diameter and the other was named Double-Pancake Specimen with Bi-2223 wire coiled on a bobbin of 100 mm diameter. The Bi-2223 wire of the Double -Pancake Specimen was coiled with several winding tensions. The continuous current transport method was used for the measurement of the electrical degradation. Various levels of transport current were applied to each conductor. The levels are 90, 95, 98, and 110% of the critical current (I/sub c/) in Ring Specimens and 95 and 150% in Double-Pancake Specimens. Although a difference of the I/sub c/ in the long Bi-2223 wire was found, there was not any severe degradation in the Ring Specimens. When the level of transport current was below the critical current, degradation did not appear in the Double-Pancake Specimens either. However, they degraded very quickly when the level of transport current was 150% of I/sub c/.         Observation of vortex distribution in samples of Bi-2223 Ag-sheathed tapes with and without uranium doping by means of the high-resolution Bitter method    S. Ohshima, K. Ujiie, T. Kawai, K. Moriai, H. Yamada, D.G. Marinaro and S.X. Dou Summary: We examined the distribution of vortices in both Bi-2223 Ag-sheathed tape and U-doped Bi-2223 Ag-sheathed tape applying the high-resolution Bitter method. In the low temperature region (T/spl Lt/T/sub c/), we found that the vortices in the undoped Bi-2223 Ag-sheathed tape developed into either a triangular arrangement or a heterogeneous arrangement along the grain boundaries of the Ag sheath, which form weak pinning centers. The vortex distribution for U-doped Bi-2223 samples was slightly different from the distribution for the undoped material. We observed some movement of the vortices in both the U-doped and the undoped Bi-2223 Ag-sheathed tapes at 50 K. At higher temperatures, T>75 K, the vortices in the Bi-2223 tapes moved even faster so that no deposition pattern, indicating the location for vortices, formed.         Characterization of thermal conductivity and mechanical properties of Ag-alloy sheathed Bi(Pb)-Sr-Ca-Cu-O superconductor tape    S.H. Jang, Jun Hyung Lim, Jung Ho Kim, Bong Ki Ji, Jinho Joo, W. Nah, J.S. Volf, Hua Kun Liu and M. Apperley Summary: We evaluated the effect of alloying additions to Ag on thermal conductivity and mechanical properties of Ag-alloy sheathed Bi-2223 (BSCCO) superconductor tape. The tapes were made with combinations of Ag alloys such as Ag-Mg, Ag-Sb, and Ag-Au for inner and outer sheath. Thermal conductivity of the tapes was evaluated by using thermal integral method at 10-120 K. It was observed that the addition of alloys reduced remarkably thermal conductivity and improved mechanical strength. The thermal conductivity for Ag-Mg, Ag-Sb, and Ag-Au at 40 K was measured to be 411.4, 142.3, and 109.7 W/(m/spl middot/K), respectively, which is approximately 2 to 9 times lower than that of Ag (1004.6 W/(m/spl middot/K)). In addition, the thermal conductivity of alloy-sheathed tape significantly depended on their thermal conductivity of sheath materials. For Ag-alloy sheathed tapes, the thermal conductivity was much lower (i.e., 5 -18 times lower) than that of the Ag sheathed tape The mechanical property of alloy-sheathed tape was also evaluated and correlated to the microstructural evolution.         Texture development of a multi-filamentary Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ HTS tape during thermo-mechanical treatment    S.S. Oh, J.K. Choi, H.S. Ha, D.W. Ha, C. Park, K.J. Song, Y.K. Kwon and K.S. Ryu Summary: In order to investigate texture development of superconducting grains, multi-filamentary Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ (Bi-2223)/Ag tapes were fabricated with different pass reduction ratios of rolling. The deformation-induced-texture and reaction-induced-texture for Bi-2212 and Bi-2223 were evaluated by X-ray diffraction including pole figure analysis. It was found that the texture of Bi-2223 develops by the progress of thermo-mechanical treatment. The texture for both Bi-2212 and Bi-2223 was found to develop better along the rolling direction than the transverse direction. By scanning electron microscopy observation, the highly textured region of Bi-2223 grain was found to expand by the intermediate rolling and additional heat treatment.         Measurements of the performance of BSCCO HTS tape under magnetic fields with a cryocooled test rig    M.A. Young, J.A. Demko, M.J. Gouge, M.O. Pace, J.W. Lue and R. Grabovickic Summary: The use of high-temperature superconducting (HTS) materials for electric power applications is being realized in prototype systems. A test rig was designed and fabricated that uses a 6-T cryocooled magnet with an 20.3 cm warm bore. Inserted in the bore is a stainless steel vacuum vessel that has a Cryomech GB37 cryocooler to conductively cool the sample. Critical current measurements were made on BSCCO-2223 tapes under externally applied perpendicular and parallel magnetic fields. A description of the test rig design and results from a series of measurements will be presented.         Quench characteristics of HTS tapes with alternating currents above their critical currents    Seong-Woo Yim, Hyo-Sang Choi, Ok-Bae Hyun, Si-Dole Hwang and Byoung-Sung Han Summary: In this study, the dependence of quench characteristics of HTS tapes on the amplitude of current and duration time was investigated by applying alternating current (AC) that is several times over the critical currents of HTS tapes. When the applied AC/sub peak/ was up to three times of critical current, the joule heat was not cooled down by LN/sub 2/ completely. However, when the over-current reached four times of critical current, the superconducting region began to decrease gradually and the total resistance of HTS tapes increased rapidly. Finally, we analyzed the quench development using voltage-current characteristics and examined the influence of pitch angles on resistance increase.         The angular dependence of AC transport losses for a BSCCO/Ag tapes in DC applied field    Guo Min Zhang, Liang Zhen Lin, Li Ye Xiao, Ming Qiu and Yun Jia Yu Summary: In the application of high temperature superconductors, the superconducting tapes are often exposed to magnetic fields with different orientations. Thus AC losses in such cases depend not only on the magnitude of the external magnetic field, but also on its orientation with respect to the tape surface. In this paper, AC transport losses of a BSCCO/Ag tape were measured at 77 K in 48 mT, 80 mT and 120 mT DC magnetic fields, respectively. The angle between the direction of the magnetic field and the wide side of the tape varied from 0 to 90 degrees with a step of 10 degrees. Using the theoretical model we had proposed for the angular dependence of critical current, we developed a theoretical model to describe the angular dependence of AC transport losses by modifying Norris formula. The comparison between the theoretical values and the measured data were presented and discussed.         Anisotropic AC behavior of multifilamentary Bi-2223/Ag tapes    J.-F. Fagnard, P. Vanderbemden, R. Cloots and M. Ausloos Summary: In this communication, we report on the anisotropy of the superconducting properties of multifilamentary Bi-based tapes experimentally investigated by AC magnetic susceptibility measurements. The susceptibility /spl chi/=/spl chi/'-j/spl chi/'' was measured using a commercial system and a couple of orthogonal pick-up coils. The /spl chi/'' vs. temperature curves were shown to exhibit two peaks. The smaller of the peaks, occurring near T=72 K, was only visible for particular field directions and within a given frequency window. Such results point out the role played by the phase difference between the applied magnetic field and the internal magnetic field seen by the filaments.         Characterizing superconducting BSSCO tapes and bulk joints    C. Vipulanandan and W. Lu Summary: For many potential applications, long lengths of superconducting tapes and bulk materials with high current capacities are needed. Producing long lengths of superconducting bulk and tapes by joining is considered a challenge. Superconducting monofilament Bi(2223) tapes were fabricated using the powder in tube method with groove and flat rolling. The tapes were rolled to a final thickness of 250 /spl mu/m. The tapes and bulk materials were processed using a combination of pressing and sintering. The average critical currents for the tapes and bulk materials were 70 and 180 A at 77 K and self field respectively. Superconducting tapes and bulk specimens were joined using lap and butt configurations and thermomechanically processed to make superconducting joints. The maximum joint efficiencies for the lap and butt joints were in the range of 30% to 100%. The phase changes and microstructural development in the joint region were investigated using hardness measurements, XRD and SEM.         Texture analysis in the thermo-mechanical processing of Bi-2223 tapes    D.M. Pooke, M.R. Presland, O.R. Mercier, Y.B. Huang, F. Li and A. Otto Summary: We have investigated c-axis texture development in Bi-2223/Ag tapes made by American Superconductor Corp. at various points in a thermo-mechanical process using three methods: XRD rocking curves, the anisotropic field dependence of critical current density J/sub c/, and the magnetization anisotropy. We assess the limitations of each technique, and uncover trends in texture development during the processing sequence. For the rocking curve measurement this involved establishing the uncertainty in measurement of the distribution width of misorientation angles, the variability in misalignment in successive adjacent sections of tape, and the impact of surface grinding on the measurement, while for the magnetic technique we have investigated methods to reduce the contribution from global transport currents, and also the effect of field sweep-rate on the derived texture. For a two-step heat treatment sequence, we find a large rise in texture after the first heating step, a drop after intermediate rolling, and almost complete recovery during the final heating step. The transport data does not show a strong correlation between texture and J/sub c/ across a variety of samples (J/sub c/ of 30 k-50 kA/cm/sup 2/, 77 K & self-field), within a limited range of texture.         Er/sub 2/O/sub 3/-ZrO/sub 2/ insulation coatings on Ag/AgMg sheathed Bi-2212 superconducting tapes by sol-gel process    E. Celik, Y. Akin, W. Sigmund and Y.S. Hascicek Summary: We have fabricated high temperature insulation coatings on long-length superconducting tapes and wires using a reel-to-reel sol-gel dip coating system for HTS/LTS coils at NHMFL. In this work, 8 mol% Er/sub 2/O/sub 3/-ZrO/sub 2/ coatings were deposited on Ag or AgMg sheathed Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub x/ (Bi-2212) superconducting tapes. The insulation solution was prepared with Zr and Er based organometallic compounds. The gel layers were transformed to amorphous layers at about 300/spl deg/C for 30 sec. in air. The ceramic oxide coatings were subsequently formed at 600/spl deg/C for 60 sec. in air. The coatings on Ag/AgMg sheathed Bi-2212 tapes were finally densified by annealing at 862/spl deg/C for 12 h under oxygen gas flow. These coatings were characterized by means of ESEM, DTA, and XRD. Dielectric constant, breakdown voltage and resistance values of the coatings were measured using a standard multimeter and power supply. ESEM revealed that surface morphology of the coatings is mosaic structure. XRD and DTA studies show that cubic phases formed at between 450/spl deg/C and 600/spl deg/C. Dielectric constant, high voltage breakdown and resistance values of the insulations were found to be 20, 1096 V at 1.5 mA and 14 M-Ohms, respectively.         Measurement of joint properties of Bi(Pb)-Sr-Ca-Cu-O (2223) tapes by field decay technique    Jung Ho Kim, Kyu Tae Kim, S.H. Jang, Jinho Joo, Seyong Choi, W. Nah, H. Kang, Tae Kuk Ko, Hong-Soo Ha, Sang-Soo Oh, Kang-Sik Ryu and P. Nash Summary: We joined 19-multifilamentary Bi-2223 superconductor tapes and fabricated double-pancake coils by using resistive- and superconducting-joint methods. The critical current ratio (CCR) of the jointed tape and the decay characteristics, joint resistance, and n-value of the pancake coils were evaluated. The joint resistance of the coils was characterized by the field decay technique. It was observed that the CCR was higher in the joined tape made by the resistive-joint method, compared to that by the superconducting-joint method. On the other hand, joint resistance was measured to be 4 orders of magnitude smaller in the superconducting-joint coil; approximately 40% of critical current was retained in the persistent current mode and the joint resistance was 0.18 n/spl Omega/. Better and longer retention of the magnetic field in the superconducting-joint coil is believed to be due to the direct connection between the superconducting cores.         Superconducting joint of multifilamentary Bi(Pb)-Sr-Ca-Cu-O tapes    Kyu Tae Kim, Jung Ho Kim, Jinho Joo and P. Nash Summary: We joined BSCCO(2223) multifilamentary tapes and evaluated their electrical and mechanical properties. In the process, two superconducting-joint methods were used; one is direct connection of two multifilamentary tapes (MM-joint), and the other is connection of them by using one or two single filamentary tape (MSM-) and double-MSM- joint. The critical current ratio (CCR) and n-value of the jointed tapes were evaluated as a function of uniaxial pressure. It was observed that the CCR and n-value were 24.8-29.0% and 2.5-2.8, respectively, for MM-jointed tape. On the other hand, the corresponding values were improved to 24.8-53.9% and 2.9-4.1 for MSM- and 63.4-76.0% and 3.5-5.1 for double-MSM-jointed tape, respectively. The highest electrical properties of double-MSM-joint are considered to be due to the presence of single core, resulting in better interconnections of multifilaments between the two tapes. The mechanical property of jointed tape was also evaluated and correlated to the microstructural evolution.         Pseudo-periodic nanostructuring of Ag-clad BSCCO-2223 multifilamentary tapes as a tool to tune in-field superconducting performance    R. Gerbaldo, D. Botta, A. Chiodoni, G. Ghigo, L. Gozzelino, F. Laviano, B. Minetti, E. Mezzetti, A. Rovelli, A. Amato, L. Martini and F. Curcio Summary: A technology has been developed to create nanostructures by heavy-ion irradiation on "large area" surfaces of superconductors. The in-vacuum apparatus consists of a moving sample-holder, automatically driven at a given velocity in order to obtain the exposure of collimated zones of the moving target to a programmed ion fluence. The irradiation facility has been employed to implant 4.2 GeV gold-ions into a 30 cm long multifilamentary Ag/BSCCO-2223 tape, at the dose equivalent field of 0.5 T. The paper is focused on the enhanced performance and on the matching effects between the pseudo-periodic array of ion-induced columnar defects and the vortex lattice. The enhancements exhibit a maximum near the dose equivalent field, clearly pointing out the tunability of the performance through the modulation of the distance between nanotracks.         A comparison of Ag and Ag-alloy sheathed Bi-2223 tapes    H.K. Liu, Z.M. Zhang, Rong Zeng, J. Horvat and M. Apperley Summary: Ag and Ag-alloy sheathed Bi-2223 tapes were fabricated by a powder-in-tube technique with different configurations of the precursor and restack sheath materials: Ag, AgAu7 wt%, AgSb0.6 wt%, AgMg0.2 wt%. Analysis of the I/sub c/ and volume fractions of the Bi-2223, Bi-2212, Bi-2201 and Bi-3221 phases indicated that volume fractions of Bi-2223>90%, Bi-2212/spl sim/5%, Bi-2201/spl sim/0% and Bi-3221<2%, normally result in tapes with the highest I/sub c/. The mechanical properties of the tapes revealed consistent results. Generally, the harder the sheath material, the higher tolerance to the bending strain and higher the tensile strength of the tape. The sequence of the alloys' hardness from highest to lowest was AgMg0.2 wt%, AgSb0.6 wt%, AgAu7 wt% or Ag.         Partial melting and HIP processing of Bi(2223): bulk and tapes    E. Giannini, V. Garnier, I. Savysyuk, R. Passerini, G. Witz, Xiao-dong Su, B. Seeber, Ling Hua and R. Flukiger Summary: A detailed investigation of the equilibrium between the Bi,Pb(2223) phase and the melt was carried out by in-situ high temperature neutron powder diffraction both on sintered bulk samples and Ag-clad tapes. Stability, decomposition and re-formation of Bi,Pb(2223), as well as the evolution of secondary phases, were studied and the effect of the oxygen partial pressure was investigated. Bi,Pb(2223) melts incongruently to (Sr,Ca)/sub 14/Cu/sub 24/O/sub 41/, (Sr,Ca)/sub 2/CuO/sub 3/, and a Bi,Pb-rich liquid, and no precipitation of Bi(2212) was observed at this stage. Direct formation of the Bi,Pb(2223) phase from the melt was observed, opening up the possibility of processing Ag-sheathed tapes from a partial melting route. The possibility of reforming the Bi,Pb(2223) phase from the melt proved to be extremely sensitive to temperature and strongly dependent on the Pb-losses. The study of the mass losses due to Pb-evaporation was complemented by thermogravimetric analysis which proved that the Pb-losses are responsible for moving away from the equilibrium and therefore hinder the Bi,Pb(2223) to reversibly form from the melt. Hot isostatic pressure has proved to be an effective remedy for preventing volatile elements from evaporating and for increasing the density of the tapes. The first annealing stage of the Ag-Bi,Pb(2223) processing was performed under isostatic pressure after making the Ag-sheath airtight. Positive effects of pressure on filament density, formation kinetics and critical current were observed at 10 MPa. We have extended our search for an alternative processing route to the Pb-free Bi(2223) phase. High purity Bi(2223) bulk samples and Ag-sheathed tapes were successfully prepared from pre-reacted powders. Very large Bi(2223) grains (up to /spl sim/500 /spl mu/m) were observed to grow at the Ag-ceramic interface.         The influence of starting precursors on grain growth, microstructure evolution and J/sub c/ property of Bi-2223/Ag tapes    Jaimoo Yoo, Chunhai Jiang, Jaewoong Ko, Youngkuk Kim, Haidoo Kim and Hyungsik Chung Summary: The grain growth, microstructure evolution and J/sub c/ properties of Bi-2223/Ag tapes, fabricated from precursor powders with different lead contents (Pb=0.2-0.4) and particle size distributions, were compared. The experimental results show that the variations of lead content and particle sizes extremely influence the reactivity of precursor powders, consequently, the formation rate of the 2223 phase, microstructure and J/sub c/ values of Bi-2223/Ag tapes. In addition, these variables also affect the formation and distribution of the nonsuperconducting secondary phases, hence the grain connectivity and texture, which are of vital importance to the current transport. By optimizing these powder parameters, J/sub c/ values above 60 kA/cm/sup 2/ (77 K, 0 T) in short tapes were achieved with high reproducibility.         Critical current limiting factors in post annealed (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ tapes    J. Jiang, X.Y. Cai, J.G. Chandler, S. Patnaik, A.A. Polyanskii, Y. Yuan, E.E. Hellstrom and D.C. Larbalestier Summary: Processing (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ (Bi-2223) tape by the oxide-powder-in-tube technique normally includes two heat treatments and one intermediate rolling. A three-step heat treatment was applied for the second heat treatment (HT2). Experimental procedures were designed for understanding the roles of each processing step in HT2 and the post anneal. It was found that post annealing improved the critical temperature T/sub c/, critical current density J/sub c/ and flux pinning characteristic field H/sub p/. The midpoint T/sub c/ was raised from 103 to 109 K by post anneal, while H/sub p/ was increased from 126 to 183 mT. Post anneal at about 790/spl deg/C precipitated Pb from Bi-2223 phase to form a Pb-rich phase, thus the microstructure looked worse but T/sub c/, J/sub c/ and H/sub p/ were raised. J/sub c/ was raised as the Bi-2212 phase signature in the T/sub c/ trace decreased. The most important observation is that raising T/sub c/ and minimizing residual Bi-2212 are decisive factors for increasing J/sub c/ at 77 K in Bi-2223 tapes.         Reduction in AC transport self-field losses for Ag-sheathed Bi2223 tapes by changing filament arrangements using two-axial rollers    A. Oota, R. Inada, N. Inagaki and P.X. Zhang Summary: Without introduction of resistive barriers, we succeeded in reducing AC transport self-field losses at 77 K for Ag-sheathed Bi2223 multifilamentary tapes with the m/spl times/n (m,n=3, 5) filament arrangements, fabricated by a rectangular deformation process using passive two-axial rollers. In spite of the main contribution of hysteresis loss of superconductor, the transport losses for the samples are reduced by approximately 50-70% compared with the values for Ag-sheathed Bi2223 tapes by a standard powder-in-tube process. Further change in filament arrangements using two-axial rollers leads to a further reduction in the loss values. From numerical calculations, the loss reduction is mainly ascribed to a division of field-free-core under AC current transmission.         Constitutive mechanical modeling of BSCCO powders    A. Allais, C.E. Bruzek, N. Lallouet, P. Montmitonnet, P. Herrmann, D. Pelissier and F. Toussaint Summary: In order to feed a new mechanical model of the Powder In Tube (PIT) processing BSCCO/Ag conductors, a plastically compressible constitutive model of the powder is proposed and its parameters measured. We use a simple compressible model of the CAM-CLAY type with work hardening and softening depending on density variation. The unknown parameters of the model, the plastic properties of ceramic filaments, were evaluated from experimental studies of the real BSCCO powder by estimating the yield surface at a given density.         Bi-2223 tapes - specific performance for different applications    T.J. Arndt, A. Aubele, H. Krauth, M. Munz, B. Sailer and A. Szulczyk Summary: In the past (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ Ag/Ag-alloy-sheathed High-Temperature Superconductor (HTS) tapes (Bi-2223 tapes) have been proven being suitable for building quite different system components for a variety of applications. Nevertheless it revealed that applications like Power Transmission Lines, Transformers, Motors/ Generators, SMES, very high field magnets and MRI put very special requirements on the tapes which differ from application to application. The most important point is that the tapes will provide cost-efficient performance for the special application. This means that it's not sufficient to analyze the price in $/kAm, but additionally it's necessary to consider e.g., AC-losses, geometry, mechanical strength and insulation properties and how they contribute to cost. We discuss a subset of the different requirements from the view of a tape supplier. We depict the current status of the tape production unit lengths >1000 m, overall current densities /spl ges/100 A/mm/sup 2/, steep E-I-characteristics n-value /spl ges/30 at standard conditions and even at low temperatures and/or high magnetic fields), low AC-losses combined with remarkable critical currents of 50 A/mm/sup 2/, reliable properties of mechanics and insulation.         Dynamic heat treatment of BSCCO-2212 tapes with homogeneous properties and high critical current density    E. Flahaut, D. Bourgault, C.E. Bruzek, M.O. Rikel, P. Herrmann, J.L. Soubeyroux and R. Tournier Summary: Melt-processed Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub 8+x//Ag tapes are now commercially available in long lengths. The melting step, which is mostly important for tape performance is difficult to control on the industrial scale. A dynamic approach is proposed. The melting step and subsequent annealing (2212-formation) step are separated. For the melting step, the reel-to-reel transfer system through a 140-cm long furnace was developed. The maximum processing temperature in the hot zone can be controlled to within 1/spl deg/C; heating rate from 3000/spl deg/C/h to 30000/spl deg/C/h and cooling rate between 60/spl deg/C/h to 30000/spl deg/C/h. The effect of heat treatment parameters characterizing the melting step on the transport critical current densities at 4.2 K was studied and correlated to microstructure characterized by SEM/EDS and X-ray diffraction analyzes.         Improving the critical current density in Bi-2223 wires via a reduction of the secondary phase content    Y.B. Huang, X.Y. Cai, T. Holesinger, V.A. Maroni, D. Yu, R. Parrella, M. Rupich, E. Hellstrom, M. Teplitsky, K. Venkataraman, A. Otto and D. Larbalestier Summary: Progress in the performance of multifilamentary composite Bi-2223 wire fabricated at American Superconductor is reviewed. Critical current (I/sub c/) performance of 175 A at 77 K and self-field and critical current density (J/sub c/) performance of 22.1 kA/cm/sup 2/ (77 K, 0.1 T perpendicular to the tape plane) have been measured for short samples of Bi-2223 wire (standard size is 0.21/spl times/4.0/spl times/100 mm). Microstructure analysis by SQUID magnetometry, transmission XRD and TEM shows a large amount of residual 2212 intergrowth remaining in Bi-2223 grains. Residual 2212 intergrowth is seen to correlate with self-field J/sub c/ at 77 K across a range of experimental samples, suggesting that higher levels of performance will be achieved by further reducing residual 2212.         Study of intermetallic compounds isostructural to MgB/sub 2/    R.L. Meng, B. Lorenz, J. Cmaidalka, Y.S. Wang, Y.Y. Sun, J. Lenzi, J.K. Meen, Y.Y. Xue and C.W. Chu Summary: The small intergrain effect of MgB/sub 2/ on supercurrent makes it one of the most promising candidates for superconducting conductors due to its easier processing and the associated lower manufacturing cost. Unfortunately, the superconducting transition temperature T/sub c/ is only 40 K. However, band-structure calculations predict that a higher T/sub c/ than that of MgB/sub 2/ is possible for isostructural and isovalent intermetallic compounds with greater lattice parameters or greater unit cell volumes. The prediction appears to be consistent with the negative pressure effect on T/sub c/ observed. The substitution of the larger Ca-ions for the smaller Mg-ions has thus been suggested to raise T/sub c/, but not yet realized. Alternatively, we have synthesized and studied a series of binary and pseudobinary intermetallic compounds, AGa/sub 2/, AGa/sub 2-x/Si/sub x/, and AAl/sub 2-x/Si/sub x/, where A=Ca, Sr, or Ba, which are isostructural to MgB/sub 2/ and have greater lattice parameters than MgB/sub 2/. In spite of the greater lattice parameters, AGa/sub 2/ are not superconducting. However, all pseudobinary compounds AGa/sub 2-x/Si/sub x/ and AAl/sub 2-x/Si/sub x/ for 0.6         Superconductivity at 10 K in (Ge, Ba)-based compounds    Yang Li and J.H. Ross Jr. Summary: This study focused on (Ge, Ba)-based compounds with Co-doping, and found superconductivity at 10 K for these (Ge, Ba)-based compounds. Materials with compositions Ba/sub 8/-Ge/sub 46-x/-Co/sub x/ (x = 0, 4 and 6) were prepared by directly melting at 950/spl deg/C and then by solid-state reaction at 700 /spl deg/C. X-ray diffraction shows that these materials are mixtures of several phases. The magnetic susceptibility of the x = 0 sample shows that there are two superconducting transitions, at about 10 K and 4 K. Electrical transport measurement also confirmed the existence of two superconducting transitions. The M-H curves show that the first critical field H/sub C1/ is about 170 Oe for the T/sub C/ = 4 K superconducting phase, and 500 Oe for the T/sub C/ = 10 K phase. In these compounds, Co-doping results in the suppression of T/sub C/, from 10 K to 7 K. The superconducting volume fraction also decreases with increasing Co-doping. For Co-doped samples, there is no 4 K superconducting transition.         Comparative studies of MgB/sub 2//Mg nano-composites and press-sintered MgB/sub 2/ pellets    Qiang Li, L. Wu, Y. Zhu, A.R. Moodenbaugh, G.D. Gu, M. Suenaga, Z.X. Ye and D.A. Fischer Summary: We present our studies of superconducting and microstructural properties of bulk MgB/sub 2//Mg nano-composites and press-sintered MgB/sub 2/. TEM investigation revealed that the composites are very dense, consisting of nano-sized MgB/sub 2/ grains connected by the well-defined clean grain boundaries (GB). Both amorphous and structural intact GB's were observed in the press-sintered samples. Magnetization and transport measurements showed that the composite carried over 1 MA/cm/sup 2/ critical current density (J/sub c/) at 5 K and self-field, while the pressed sintered MgB/sub 2/ has J/sub c/ /spl sim/ 0.25 MA/cm/sup 2/ at 5 K and self-field. The origin of substantially higher J/sub c/ found in the composites is mostly due to their nano-sized grains and clean grain boundaries.         Synthesis of MgB/sub 2/ by exposure of polycrystalline boron to magnesium vapor    H.N. Jones, C.R. Feng, M. Osofsky, E.E. Carpenter and K.P. Cooper Summary: Polycrystalline boron in lump form was reacted with magnesium vapor inside steel tubes at 900 C to produce MgB/sub 2/ using four to five times the stoichiometric requirement of Mg. The boron lumps were encased inside Ta foil folded over to form a boat to isolate them from the liquid Mg. These materials were sealed inside steel tubes by arc welding. Reactions were allowed to proceed for times ranging from 2.5 to 837 hours. Upon opening a tube after a 42-hour reaction time a gray powder was removed which X-ray diffraction indicated was MgB/sub 2/. SEM examination of the surfaces of the powder particles revealed a dense layer of 1-2 micron diameter crystallites which appear to be small plates with hexagonal symmetry. Metallographic examination of sections cut through the particles indicated the presence of a significant volume fraction of unreacted boron. The reaction appears to have proceeded initially along the grain boundaries in the polycrystalline lumps breaking them up into particles corresponding to the grain size. Magnetic susceptibility measurements on the powder and resistivity measurements on a cold pressed pellet show a sharp transition at 39 K despite the presence of unreacted boron. Even after reaction times up to 837 hours there was still a significant amount of unreacted boron.         MgB/sub 2/ reactive sintering from the elements    G. Giunchi, S. Ceresara, G. Ripamonti, S. Chiarelli and M. Spadoni Summary: High density MgB/sub 2/ compacts have been obtained without the need of high pressure apparatus. The key features of the sintering technique are based on the Mg liquid infiltration on powdered B preforms. Critical parameters, other than the thermal cycles, are the B powder granularity, the density of the preform and the type of the container. Centimeter-sized samples of different shapes have been obtained and the best transport critical current density, measured so far, is about 3 kA/cm/sup 2/ at T = 4.2 K and B = 9 Tesla for a sample having an overall density of 2.40 g/cm/sup 3/. Possible applications of the MgB/sub 2/ compacts are foreseeable in bulk superconducting magnets, magnetic screens and superconducting bars of variable resistance.         High density nanocrystalline MgB/sub 2/ bulk superconductors with improved pinning    A. Gumbel, O. Perner, J. Eckert, G. Fuchs, K. Nenkov, K.-H. Muller and L. Schultz Summary: We report on the synthesis of high density nanocrystalline MgB/sub 2/ bulk samples with improved pinning via mechanical alloying of elemental Mg and B powders at ambient temperatures and hot pressing. The samples exhibit high j/sub c/ at 20 K and 1 T, and an irreversibility line strongly shifted toward higher fields resulting in H/sub irr/ of about 0.8H/sub c2/(T) compared to H/sub irr/(T) of about 0.5H/sub c2/(T) as typically observed for untextured conventional bulk specimens. The improved pinning of this material is attributed to the large number of grain boundaries in the nanocrystalline state.         The influence of structural defects on intra-granular critical currents of bulk MgB/sub 2/    A. Serquis, X.Z. Liao, L. Civale, Y.T. Zhu, J.Y. Coulter, D.E. Peterson and F.M. Mueller Summary: Bulk MgB/sub 2/ samples were prepared under different synthesis conditions and analyzed by scanning and transmission electron microscopy. The critical current densities were determined from the magnetization versus magnetic field curves of bulk and powder-dispersed-in-epoxy samples. Results show that through a slow cooling process, the oxygen dissolved in bulk MgB/sub 2/ at high synthesis temperatures can segregate and form nanometer-sized coherent precipitates of Mg(B,O)/sub 2/ in the MgB/sub 2/ matrix. Magnetization measurements indicate that these precipitates act as effective flux pinning centers and therefore significantly improve the intra-grain critical current density and its field dependence.         Enhancement of superconducting properties of textured YBCO using double seeded technique    Y.X. Zhou, H. Fang, U. Balachandran and K. Salama Summary: Isothermal melt texturing is currently a well established technique for manufacturing superconducting bulk materials with high trapped magnetic fields and levitation forces. The technique involves the growth of RE-123 compounds in geometries such as discs and short rods using top seeding of high temperature material such as SmBCO. The technique is relatively simple, however it yields nonuniform microstructure and variable superconducting properties throughout the length of the sample. The top half of the sample is well oriented and possesses good properties, while the bottom half suffers from misorientation, porosity and poor superconducting properties. In this work, the effects of using top and bottom seeding on microstructure and crystal orientation were studied. We also measured trapped magnetic fields throughout the thickness of the sample. In this arrangement, we found that both top and bottom parts of the sample are well oriented and the trapped magnetic fields in both halves are almost the same. These results give promise to the use of this technique to improve the superconducting properties in bulk textured YBCO.         Neodymium oxide doped melt textured YBa/sub 2/Cu/sub 3/O/sub 7-x/ single crystals    F. Dogan, S.W. Sofie, W.C. Hicks, M. Strasik, K.E. McCrary and A.C. Day Summary: Processing, microstructure and property relationships in neodymium oxide doped high temperature superconducting YBa/sub 2/Cu/sub 3/O/sub 7-x/ (Y123) were investigated. It has been observed that a small amount (/spl sim/ 0.25 - 1 mol%) of Nd/sub 2/O/sub 3/ results in the formation of nanosized secondary phases which may have a significant effect on the superconducting properties of melt textured Y123 single crystals. It was further observed that addition of Nd/sub 2/O/sub 3/ greater than 1 mol% leads to multiple nucleation during solidification of Y123 and results in polycrystalline samples. Melt textured single crystals of Y123 with < 1 mol% were successfully grown and characterized with respect to microstructural development and superconducting properties.         Hot-seeding melt growth of large (Sm-Eu)123 single domains in air with controlled chemical substitutions    A. Hu, N. Sakai and M. Murakami Summary: Hot-seeding melt growth of large (Sm-Eu)123 single domains has been investigated in air with Nd123 seeds. A homogenization at the partial molten state, which was achieved by annealing at 1100 /spl deg/C for half an hour and at 1070 /spl deg/C for 2 to 4 hours before seeding, was the key to the growth of large single domains with a diameter more than 3 cm. After seeding one sample was grown in a slow cooling at 0.3 /spl deg/C/hour for 120 hours. The other sample was grown with a fast cooling at a rate of 2 /spl deg/C/hour for 15 hours followed by a 0.3 /spl deg/C/hour slow cooling for 100 hours. The measurements of local T/sub c/ and J/sub c/ values over the entire bulks evidenced that a large spatial variation in the superconducting properties was observed in the sample grown with the former thermal schedule, while the latter thermal profile favored the growth of near stoichiometric (Sm/sub x/Eu/sub 1-x/)Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// over the whole processing and thereby significantly enhanced the field trapping capacity.         Pinning property of Bi-2212 single crystals with columnar defects    E.S. Otabe, K. Okamura, H. Wada, M. Kiuchi, T. Yasuda, S. Okayasu and T. Matsushita Summary: The critical current density and the irreversibility field were measured before and after nickel ion irradiation for Bi-2212 single crystals in an optimally doped or an overdoped state in a magnetic field parallel to the direction of irradiation. The critical current density was theoretically calculated by using the summation theory and the flux creep-flow model. From the comparison with experimental results the condensation energy density was estimated for each specimen. These results are compared with a similar analysis on three-dimensional Y-123.         Pinning mechanism of the high critical current density Sm-Ba-Cu-O superconductors with Sm210/Pd/Pt/CeO/sub 2/ addition    Shih-Yun Chen, In-Gann Chen and Mow-Kuen Wu Summary: The superconducting properties and the pinning mechanisms of air-processed melt-textured grown Sm-Ba-Cu-O samples with the addition of small amounts of Pd (0.5wt%), Pt (0.5wt%) and CeO/sub 2/ (1.0wt%) were studied. The superconducting properties were enhanced by these additions, especially in co-doped samples. With co-doping of Pd/Pt or Pd/CeO/sub 2/, the samples exhibited a high T/sub c/ (/spl sim/91 K) and a high J/sub c/ (0 T,77 K)/spl sim/10/sup 4/ A/cm/sup 2/. Pinning forces vs magnetic field studies indicated that these samples have different pinning mechanisms from the un-doped sample. Observations of the microstructures showed that the Pt or CeO/sub 2/ addition reduced the sizes of the 211-particles significantly. EPMA results showed that the chemical distributions of these additions are different. Furthermore, TEM/EDS investigations found that the compositional fluctuation of the matrix in the sample co-doped with Pd/Pt is larger than in the sample co-doped with Pd/CeO/sub 2/.         Irreversibility field above 14 T at 77 K in (Nd--Eu--Gd)Ba/sub 2/Cu/sub 3/O/sub y/    M. Muralidhar, N. Sakai, M. Jirsa and M. Murakami Summary: In (Nd/sub 0.33/Eu/sub 0.38/Gd/sub 0.28/)Ba/sub 2/Cu/sub 3/O/sub y/, a new type of nanometer-scale pinning center was created by choosing an appropriate matrix chemical ratio. Such a pinning center could be controlled via externally added small quantity of 211 (NEG-211 or Gd-211) secondary phase. Microstructure analysis combined with magnetic characterization clarified that the sample with a high irreversibility field always exhibits chemical modulation and formation of a special nanometer-scale lamellar structure. High magnification STM observations revealed that the nano-lamellas consist of rows of aligned NEG-rich clusters 3 to 4 nm in size. This new material with the Nd:Eu:Gd ratio of 1:1.25:0.85 combined with 5 mol% 211 secondary phase exhibits the high secondary peak position at around 4.5 T and the irreversibility field over 14 T at 77 K for H/sub a//spl par/c-axis.         Improvement of the trapping capacity of bulk superconductor with resin impregnation    M. Tomita and M. Murakami Summary: We have characterized the mechanical properties of a large-grain Y-Ba-Cu-O 46 mm in diameter using the strain gauges. The electromagnetic stress was imposed on the bulk samples by reducing the external field from 7 T to 0 T at 65 K. The sample without resin was broken during the field-decreasing process with the maximum stress reaching 150 MPa. In contrast, the maximum stress was only 40 MPa for the resin-impregnated sample covered with the carbon fiber fabrics. In order to confirm the improvement of mechanical properties through resin impregnation combined with carbon fiber fabric wrapping, we measured trapped fields at lower temperatures. Resin-impregnated Y-Ba-Cu-O bulk 2.4 cm in diameter Sm-Ba-Cu-O bulk 2.4 cm in diameter wrapped with carbon fiber fabric could trap a field of 13.55 T at 36 K and 13.69 T at 47 K, respectively.         Magnetic behaviors of HTS bulk components in hybrid magnetic circuit    M. Qiu, L.Z. Lin and G.M. Zhang Summary: Melt texturing large-grain HTS material has evolved in the last few years into a technology capable of producing large quantities of high-performance superconducting bulk materials. Such materials are used for developing novel engineering devices. In order to clarify magnetic behaviors of HTS bulks in a magnetic circuit, magnetization, magnetic relaxation and the levitation force were measured for the HTS combined bulks with and without soft iron. Experimental observations and theoretical analyzes indicate that the induced proximity current would modify flux diffusion and the screening-current distribution inside, resulting in the change of magnetic behaviors such as the trapped field and the levitation force. Well-designed soft-iron layers would be helpful to enhance the magnetic stability and strengthen the HTS combined bulks. An alternative method is provided to optimize flux configurations in HTS electromagnetic devices.         Melt-textured YBCO superconducting tube for magnetic shielding    H. Fang, J.R. Claycomb, Y.X. Zhou, P.T. Putman, S. Padmanabhan, J.H. Miller Jr., K. Ravi-Chandar and K. Salama Summary: Melt-textured YBCO superconducting tube with a wall thickness of about 1 mm was prepared by infiltration and growth process; a method leads to the near-net shape fabrication and the refinement of Y-211 inclusions. The driving force for the liquid infiltration of this process is either capillary force or a chemical potential. Single Y-123 grains with the size of 5 mm were observed. The ambient noise measurements showed that the shielding factor of the melt-textured tube is one order of magnitude higher than that of comparable sintered tube within the frequency range from 1 to 200 Hz.         Magnetic suspension force of Ag/sub 2/O doped BiPbSrCaCuO superconductor    Sang Heon Lee Summary: Magnetic flux measurements of a toroidal magnet revealed a concave shaped field distribution with a single minimum value and a null field along the axis of the torus at the point where the field was reversed. The nonlinear magnetic field of the toroidal magnet perpendicular to the Ag/sub 2/O doped superconducting disk sample with the trapped magnetic flux distorted the field line distribution. As a result, the interaction force between the magnet and sample exhibited regions of repulsive, null, attractive, null, and finally repulsive force. The asymmetrical concave shaped force pattern along the axis with two null force points indicates that the magnetic force exerted form the sample changed direction which resulted in the transition from repulsive force to attractive force at the null force point, and the force becomes repulsive again beyond the second null force point as the distance along the axis increases. The lateral stability of the suspended sample under the toroidal magnet is provided by the characteristics of the symmetrical nature of the field line with respect to the axis of the magnet. The magnetic moment of an undoped and 2% Ag/sub 2/O doped sample was shown to be m=0.043 emu and 0.06 emu, respectively. The measured suspension force exerted form the doped sample agreed well with the suspension force calculated from magnetostatic force distribution.         E-J characteristics and n value of melt-textured REBa/sub 2/Cu/sub 3/O/sub x/ (RE: Nd, Y)    K. Inoue, N. Sakai and M. Murakami Summary: Melt-textured NdBa/sub 2/Cu/sub 3/O/sub x/ (Nd123) exhibits the secondary peak effect on the magnetic field dependence of the critical current density (J/sub c/), which is attributed to the field-induced pinning. The electric field (E)-the current density (J) characteristics will be affected by the field-induced pinning. With the aim of clarifying this effect, we have investigated the E-J characteristics for melt-textured Nd123 with the secondary peak and YBa/sub 2/Cu/sub 3/O/sub x/ (Y123) with smaller secondary peak through dc magnetization and ac susceptibility. The n value was estimated on the assumption that E follows the power law: E=E/sub c/(J/J/sub c/)/sup n/. The n value was about 30 at 77 K for Y123. In the case of Nd123, the peak structure was observed on the magnetic field dependence of the n value, which exceeded 60 at 77 K. This suggests that the n value is increased by the field-induced pinning.         Bulk, surface and shape contributions to critical current density in as-grown BSCCO-2212 single crystals. Part A-equilibrium behavior    T.B. Doyle and R. Labusch Summary: A theoretical treatment for the prediction of the magnetization behavior, and hence also the critical current density, in a Type II superconductor of arbitrary shape is briefly reviewed. The treatment, which allows for the inclusion of explicit expressions for the constitutive equilibrium B/sup rev/ (H) relation, bulk vortex pinning and surface surface-barrier effects, is self-consistently applied to magnetization isotherms for as-grown, single-crystal BSCCO-2212 specimens with platelet, disc, and 'prism' geometry. In this part of the work the treatment is used to obtain B/sup rev/ (H) and H/sub c1/ (T) for this material, with the applied field, H/sub o/, directed along the crystalline c-axis (specimen minor axis). In Part B (following paper) calculated normalized M(H/sub o//H/sub c1/)/H/sub c1/ curves are fitted to the normalized experimental magnetization isotherms for each specimen geometry to obtain the bulk critical current, J/sub c/ (B,T), behavior and the relative contributions to the magnetization isotherms from vortex pinning, specimen shape, and surface-barrier effects.         Bulk, surface and shape contributions to critical current density in as-grown BSCCO-2212 single crystals. Part B-non-equilibrium behavior    T.B. Doyle and R. Labusch Summary: In this work the treatment outlined in Part A (see ibid., p.3113-16) on the equilibrium behavior is extended to the nonequilibrium behavior in the as-grown BSCCO-2212 (c-axis) system. Calculated m(h) curves are fitted to normalized experimental M-H/sub o/ isotherms for single crystal specimens with platelet, disc and 'prism' geometry. Self-consistent results are obtained for the quasistatic bulk critical current, J/sub c/(B,T), which is in limited agreement with theoretical prediction, and also for the surface-barrier and anisotropy contributions to the magnetization behavior in these specimen geometries.         Correlation between vortex distribution and temperature in YBCO films and YBCO-QMG samples    H. Yamada, K. Moriai, S. Kanno, K. Aizawa, M. Kusunoki, M. Mukaida and S. Ohshima Summary: We observed vortices with a modified Bitter method by evaporating nickel as the medium of decoration, in film and QMG (which are made with the quench-and-melt-growth method) YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) samples. The temperature range of observation was from 25 K to 90 K, and the external magnetic field was 2 mT. Consequently, we found that the vortex structures of these samples were stable from 25 K to near the critical temperature (/spl sim/90 K). The vortex density was almost three times larger than that estimated from the external magnetic field. This suggests that the vortex motion may be hopping during nickel evaporation.         Temperature dependence of the trapped field and mechanical properties of neutron irradiated and reinforced YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// bulk superconductors    R. Gonzalez-Arrabal, M. Eisterer, H.W. Weber, G. Fuchs, P. Verges, G. Krabbes, M. Tomita, M. Murakami, D. Litzkendorf, T. Habisreuther and W. Gawalek Summary: We report on the temperature dependence of the trapped field in neutron irradiated YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// bulk melt-textured materials. The field trapping capability of these materials at low temperatures is limited by their mechanical properties. We observe that samples without reinforcement usually break during activation at temperatures of around 50 K. Two reinforcement techniques were tested. Resin impregnation is found to be less effective than stainless steel bandaging to compensate for the magnetic stress generated during activation. The resin impregnated samples crack during activation at temperatures of around 45 K. Stainless steel bandaging improves the mechanical properties of the YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// samples and trapped fields of up to 13.3 T were achieved at 33 K.         Fluctuation conductivity in NdBa/sub 2/Cu/sub 3/O/sub y/ superconductors with the different amounts of 422 phase    T. Sato, H. Nakane, N. Mori and S. Yoshizawa Summary: Fluctuation conductivity analysis was carried out to characterize NdBa/sub 2/Cu/sub 3/O/sub y/ superconductors with the different amounts of Nd/sub 4/Ba/sub 2/Cu/sub 2/O/sub y/ (Nd422) phase. Samples were prepared by melt-textured process from the mixtures in molar ratios of Nd123: Nd422 = 1:x (x = 0.2, 0.25, 0.3). The conduction dimensionality and the fluctuation amplitude were obtained by analyzing the fluctuation conductivity. The dimension of conduction on excess conductivity showed little variation by the addition of 422 phase. The coherence length and the correlation length obtained by this analysis became larger with increasing amount of 422 phase. The clear evidence was found that the pinning force in the sample was well correlated with the characteristic length of superconductivity.         Weak links in YBCO nanopowder    P. Paturi, J. Raittila and H. Huhtinen Summary: We have prepared YBCO nanopowder by the sol-gel route. The original powder contains weak links as observed by magnetization and microwave absorption measurements. Most of the weak links could be reduced by keeping the powder in ethanol for 30 min in an ultrasonic bath. It was also found that the ultrasonic bath does not affect the superconducting properties of the nanoparticles themselves. The modulation field applied in the microwave absorption measurements was found to have a large effect on the temperature dependence of the absorption. This phenomenon was explained with a phase diagram for the weak links.         In-field Hall probe mapping system for characterization of YBCO welds    S. Iliescu, S. Sena, X. Granados, E. Bartolome, T. Puig, X. Obradors, M. Carrera, J. Amoros, S. Krakunovska and T. Habisreuther Summary: Artificial welding of melt-textured YBCO blocks opens the door to the fabrication of large, complex-shaped pieces required for applications. In order to evaluate the superconducting quality of the welds, we have developed a Hall probe mapping system, able to record the local magnetization at 77 K under dynamic applied fields in the range of -1 to 1 T. The system was used to characterize welded samples prepared with a new Ag induced surface melting joining technique. The magnetization maps of unwelded and welded samples of various qualities are compared and discussed. The current distributions associated to the Hall maps were calculated using the Caragol software. The magnetization and current distribution maps over the joint show that good quality welds can be reached with this joining method.         Magnetic ion Fe and Ni doping in the Cu-O chain and the CuO/sub 2/ plane in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//: a positron study    Jincang Zhang, Pinglin Li, Dongmei Deng, Lihua Liu and Shixun Cao Summary: Fe and Ni substitutions in the Cu-O chain and the CuO/sub 2/ plane are studied by positron lifetime experiment. Change of lifetime parameters is given and local electron density is evaluated as a function of substitution content. The results show fantastic and opposite behaviors for Fe and Ni substitutions. A strengthen effect of the localized carriers in the CuO/sub 2/ planes for Ni substitution and electronic weak localization in the Cu-O chains for Fe substitution are found in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// superconducting systems. The positron distribution and the annihilation mechanism are also discussed.         Effect of Th substitution on the transition temperature of Y/sub 1-x/Th/sub x/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// superconducting system    M.A. El-Shahawy, M.M. El-Zaidia, A.A. Abd El-Kader and M. Badr Summary: High temperature superconducting samples of the system Y/sub 1-x/Th/sub x/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// with x value ranging from 0.02 and up to 0.2, were prepared using the solid state reaction technique. The magnetically determined transition temperatures reflect an enhanced superconductivity at low Th concentration followed by a depression with increasing Th content. The enhanced superconductivity at low Th concentrations may be due to the slightly larger ionic radius of Th and a suggested higher hole concentration on plane oxygen sites relative to plane copper sites. On the other hand, the depression of superconductivity at higher Th concentrations could be attributed to an increased hole filling by the extra Th electron.         Development of the microstructure of uranium-doped Nd-Ba-Cu-O    N. Hari Babu, M. Kambara, Y. Shi, D.A. Cardwell, C.D. Tarrant and K.R. Schneider Summary: Melt grown Nd-Ba-Cu-O (NdBCO) has been reported to exhibit higher values of critical current density, J/sub c/ and irreversibility field, H/sub irr/, than other (RE)BCO superconductors, such as YBCO. The microstructure of NdBCO typically contains 5-10 /spl mu/m sized inclusions of the Nd/sub 4/Ba/sub 2/Cu/sub 2/O/sub 10/ phase (Nd-422) in a superconducting NdBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// phase (Nd-123) matrix. The average size of these inclusions is characteristically larger than that of the Y/sub 2/BaCuO/sub 5/ (Y-211) inclusions in YBCO. As a result, there is scope to further refine the Nd-422 size to enhance J/sub c/ in NdBCO. Large grain samples of NdBCO superconductor doped with various amounts of depleted UO/sub 2/ and containing excess Nd-422 have been fabricated by top seeded melt growth under reduced oxygen partial pressure. The effect of the addition of depleted UO/sub 2/ on the NdBCO microstructure has been studied systematically in samples with and without added CeO/sub 2/. It is observed that the addition of UO/sub 2/ refines the NdBCO microstructure via the formation of uranium-containing phase particles in the superconducting matrix. These particles are of approximately spherical geometry with dimensions of around 1 /spl mu/m. The average size of the nonsuperconducting phase particles in the uranium-doped microstructure is an order of magnitude less than their size in un-doped Nd-123 prepared with excess Nd-422. The critical current density of uranium-doped NdBCO is observed to increase significantly compared to the undoped material.         U-Pt-Sm-Ba-O chemical pinning centers in Ag-doped Sm123 textured in reduced oxygen    R.-P. Sawh, R. Weinstein, D. Parks, N. Chikumoto and M. Murakami Summary: In the U/n process enriched uranium is admixed to HTS powders, textured and then irradiated with thermal neutrons. Neutrons must penetrate several centimeters for such processing to be successful in textured materials. Bulk Sm123 cannot be U/n processed because thermal neutrons penetrate <1 mm. However, textured Sm123 can still benefit from chemical pinning centers that are formed during U/n processing. Thin or thick films of Sm123 can still be successfully U/n processed. In the present work, powders containing Ag/sub 2/O + 20 mol% Sm211 + Sm123 + Pt are doped with depleted U, and textured in a 1% oxygen atmosphere. Microstructure studies indicate the presence of small deposits of (U/sub 0.5/Pt/sub 0.5/)SmBa/sub 2/O/sub 6/, which are double perovskites. Important characteristics of the U-Pt-Sm-Ba-O particles are: (a) average size is 500 nm, (b) distribution is fairly uniform within the Sm123, (c) the number of deposits is proportional to the mass of admixed U (i.e., size is constant for increasing doping levels) (d) U does not substitute into the background Sm123, (e) Ag does not interact with either U or Pt, and (f) there is less coarsening of the U-rich particles when the dwell time of the maximum temperature in the temperature versus time profile is <2 hours. The U-Pt-Sm-Ba-O deposits are strikingly similar to the U-Pt-Y-Ba-O deposits found earlier in U-doped Y123. Tungsten or molybdenum can be used as nonradioactive substitutes for uranium to produce similar double perovskites deposits.         Effect of 3d-metal sulfide doping on the superconducting properties of Bi-2212 superconductors    C.L.S. Lima, P.B. Silva, E. Montarroyos, Y.P. Yadava and J.A. Aguiar Summary: In the present work, we have studied the effect of 3d metal sulfide doping on the superconducting properties of the Bi-2212 superconductors with the nominal composition Bi/sub 2.1/Sr/sub 2.1/Ca/sub 0.8/[(CuO)/sub 1-x/(MS)/sub x/spl rceil/2/O/sub 6+/spl delta//, where M = Ni, Cu, Zn, Ti. The samples were synthesized by solid state reaction process. Structural and magnetic characterization was carried out using x-ray diffractometry and magnetic susceptibility measurements. All the samples exhibited stabilization of superconducting Bi-2212 phase and reduction of superconducting transition temperature T/sub c/. ZnS and TiS/sub 2/ substitution for CuO planes and modification of oxygen content due to S substitution on O places jointly produce strong localization of charge carriers and at the same time improve the hole concentration of the system. These combined phenomena are responsible for the deterioration of superconductivity of ZnS and TiS/sub 2/ doped Bi-2212 superconductors.         Effect of Li addition on the properties of Bi-based superconductors    S.E. Ogun, H. Ozkan and N.M. Gasanly Summary: The effect of Li addition on the formation and properties of Pb containing Bi-based superconductors has been studied. Three successive thermal sintering cycles have been applied to the oxides adjusted for the nominal composition, Bi/sub 1.6/Pb/sub 0.4/Sr/sub 2/CaCu/sub 2/O/sub 8+d/. Eight different samples having Li/sub 2/CO/sub 3/ from 0.0 up to 3.0 weight% have been synthesized. X-ray diffraction patterns, resistivity-temperature behaviors and differential thermal analysis of the samples have been examined. Li/sub 2/CO/sub 3/ addition at 650 /spl deg/C decreases the fraction of (Bi,Pb)-2212 and increases that of Ca/sub 2/PbO/sub 4/. The normal state resistances of the samples increase, the onset T/sub c/ values decrease and the lattice parameters almost remain same with Li/sub 2/CO/sub 3/ addition. Li/sub 2/CO/sub 3/ addition up to 3.0 wt% decreases the melting temperature of (Bi,Pb)-2212 phase by about 50/spl deg/C inducing a liquid phase at about 750 /spl deg/C. Our observations suggest that the high T/sub c/ phase, (Bi,Pb)-2223 may be formed at about 750-800 /spl deg/C using the precursors, (Bi,Pb)-2212 and Ca/sub 2/PbO/sub 4/ doped with Li/sub 2/CO/sub 3/.         Effect of resin impregnation on the mechanical properties of bulk-superconductors with holes    M. Tomita and M. Murakami Summary: We have measured the rupture strength of Y-Ba-Cu-O rods having an artificial hole filled with and without epoxy resins using a three point bending test. The rupture strength was reduced by introducing the hole. In contrast, the sample with the hole filled with resin exhibited higher rupture strength than that of virgin bulk materials. These results suggest that the improvement of mechanical properties through resin impregnation is ascribed to the prevention of crack propagation along the cleavage plane due to the presence of resin. The presence of internal defects was also confirmed with the observation of ultrasonic wave.         Effects of the platelet structures on the melt textured growth YBCO superconductors    Inki Hong, Hyunseok Hwang, Yung-Hee Han, Sang-Chul Han, Tae-Hyun Sung and Kwangsoo No Summary: Melt textured growth YBCO superconductors were fabricated by the top seeding method using Sm1.8 (Sm/sub 1.8/Ba/sub 2.4/Cu/sub 3.4/O/sub 7-x/) seed. The relationship between the Y211 particles and the platelet structures was investigated by micro-structural analysis using SEM. The microstructures of melt textured YBCO superconductors have been examined by TEM and HRTEM. The results of TEM studies clarified the direction of crystal growth and a variety of micro-defects such as twin structures and stacking faults that might behave as pinning centers. Our studies were focused on the stacking faults among those micro-defects by HRTEM and formation mechanism of the stacking faults was studied. The stacking faults formed during the tetragonal to orthorhombic transition that occurred at 450/spl deg/C in oxygen annealing. The platelet structures were clearly observed by SEM due to the chemical etching effects. The lengths of stacking faults were increased as the oxygen annealing time increased from 1 hr to 50 hr. The stacking faults were considered to relate to the oxygen contents, as the platelet structures were. The results suggested an oxygen diffusion model for the formation of the stacking faults.         Correlation between the formation of growth bands and Nd210 addition in Nd/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// bulk samples    M. Gombos, V. Gomis, A.E. Carrillo, A. Vecchione, S. Pace and X. Obradors Summary: 1 cm diameter single domain NdBaCuO pellets, obtained from powders of Nd/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// (Nd123) with Nd/sub 2/BaO/sub 4/ (Nd210) addition, have been successfully prepared by top seeding melt textured growth technique. Distribution of Nd/sub 4/Ba/sub 2/Cu/sub 2/O/sub 10/ (Nd422) precipitates in the Nd123 matrix has been analyzed by means of polarized light optical microscopy and scanning electron microscopy. Relevant distribution inhomogeneity in the peripheral region of pellets with a high Nd210 addition have been revealed, as well as in regions of dendritic growth and around pores. Increasing difficulties in obtaining a complete growth of the single domain samples, in dependence of increasing Nd210 addition has been observed too. A qualitative growth model for high Nd concentration samples has been proposed to explain both these behaviors.         Optimization results for the growth of Bi-2212 single crystals by a modified vertical Bridgman method    H. Tanaka, O. Nagashima and S. Kishida Summary: Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// (Bi-2212) superconducting single crystals were prepared using starting materials with the compositions of Bi:Sr:Ca:Cu=x:2:1:y (x,y=2-3) by a modified vertical Bridgman method. We could obtain large plate-like single crystal with x=2 and y=2, which had a size of 18/spl times/5 mm/sup 2/. In the single crystal, the FWHM value of the (0010) XRD peak which corresponds to Bi-2212 superconductor was small and about 0.05/spl deg/. We also found that the single crystal showed a sharp transition in resistance-temperature characteristic when it was prepared using the starting materials with the compositions of Bi:Sr:Ca:Cu=2:2:1:3.         Improving superconductivity and mechanical properties of Bi-2223/Ag-wire composite bulk by cold isostatic pressing    S. Yoshizawa, S. Hirano, R. Yamamoto, Y. Hishinuma, A. Nishimura, A. Matsumoto and H. Kumakura Summary: To improve superconductivity and mechanical properties of Bi-2223 sintered bulk, silver (Ag) wires of 0.4 mm in diameter were added to the bulk. The sample was sintered at 840/spl deg/C for 50 hours in air. After treatment with cold isostatic pressing (CIP), the sample was re-sintered. When twenty-four Ag wires were composed, the critical current density (J/sub c/) at 4.2 K and self-field increased from 1,200 A/cm/sup 2/ to 2,000 A/cm/sup 2/ with the CIP process. SEM observation results showed that high alignment and dense structures of Bi-2223 plate-like grains were formed around the interfacial region between the superconducting oxide and the metal Ag. The mechanical properties were measured by a three point bending test. The maximum bending stress of 60 MPa was obtained in the bulk without Ag wire, which was fractured separately. With the CIP process the maximum bending stress increased to 90 MPa for the composite. The composite did not fracture but only fine cracks were induced after the maximum bending stress.         The relationship between nano-scale Sm211/Sm123 interfaces and superconductivity of Sm-Ba-Cu-O materials    Shih-Yun Chen, In-Gann Chen, Chuan-Pu Liu, Ping-Chi Hsieh and Mow-Kuen Wu Summary: The distribution of dislocations at the interface between the Sm/sub 2/BaCuO/sub 5/ particles (Sm211-particles) and SmBa/sub 2/Cu/sub 3/O/sub 7/ (Sm123) matrix with different 211-particle size from /spl mu/m to nm was measured. It is found that the density of dislocations varies with the different curvatures of the 211-particles. There is a higher density of dislocations around small-sized 211-particles, especially those with sharp corners, which act as pinning centers and thus enhance the J/sub c/(H,T) values of the superconductors. A phenomenological model has been proposed to describe the relationship between the curvature of 211-particles, the dislocation density around 211/123 interface, as well as the J/sub c/(H,T).         Limits and descriptions of primary phase volumes in BSCCO    V.J. Styve, J.K. Meen and D. Elthon Summary: Our research group has conducted numerous phase equilibrium studies on the BSCCO system. BSCCO contains 6 binary edges and 4 ternary faces. Our earlier studies have focused on these subsystems. Sufficient information from our studies and the literature on these systems and sections through the quaternary is now available to develop a complete model of the quaternary system. Our current BSCCO model is based on projections from these known binary and ternary relations toward known quaternary relations. Theory, experiment, and published literature provided considerable constraints in developing this model. Most of the quaternary is occupied by primary phase volumes (ppvs) of (Sr,Ca)O and CuO, separated by ppvs of alkaline earth cuprates. Ppvs of bismuth rich phases generally do not extend far beyond the composition of the relevant crystalline phase. A limited volume containing ppvs of ternary and quaternary cuprates is situated between these ppvs. This volume has been chemographically located and neighboring ppvs determined. The (Sr,Ca)O and CuO saturated surfaces are documented in this study along with the extents of several ppvs emanating from primary phase fields on ternary faces.         Laser textured Bi-2212 in planar geometries    M. Mora, J.C. Diez, C.I. Lopez-Gascon, E. Martinez and G.F. de la Fuente Summary: A laser assisted zone melting process has been used to texture large Bi-2212 planar polycrystalline samples with approximate dimensions 100 mm/spl times/10 mm/spl times/1 mm. This technique opens the possibility of producing large bulk textured samples attractive for power devices. The effect of growth parameters on the microstructure has been studied by scanning electronic microscopy and EDX microanalysis. The microstructure that results from the solidification profile has been correlated with the transport properties at temperatures around 77 K. In order to deduce the dissipation mechanism that limits the transport critical current in these planar samples, the temperature dependence of the critical current for these samples has been compared with that exhibited for the well-developed laser floating zone Bi-2212 rods.         Raman-study of photoinduced chain-oxygen ordering in RBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//    S. Bahrs, A.R. Goni, B. Maiorov, G. Nieva, A. Fainstein and C. Thomsen Summary: We investigated Raman-forbidden signals in RBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// with R = Y or Pr, which lose intensity under illumination at low temperatures. These defect-induced peaks are only visible in oxygen-deficient material and for light polarized parallel to the copper-oxygen chains along the material's b-axis. In a first, two-laser based experiment we established that the bleaching effect of the light is polarization dependent as well. From this and other known properties we conclude that the signal is connected to the copper-oxygen chains, reflecting their state of disorder, and is thus closely related to aging and to the persistent photoconductivity effect in the material. In a second set of experiments we followed the temperature dependence of the Raman spectra and the intensity decrease.         Production and characterization of YBCO nanoparticles    F. Li and C. Vipulanandan Summary: In this study, nanoscale YBCO-123 was synthesized using the microemulsion method. The microemulsion system was characterized by measuring the conductivity and interfacial tension. The effect of microemulsion composition on the particle size was investigated. The particles were characterized using the X-ray diffraction, transmission electron microscope and dynamic light scattering devices. The average diameter of the synthesized YBCO-123 particles was 117 nm. These results showed that the microemulsion method could be used to produce 123 nanoparticles for YBCO applications.         Transport critical current density in Fe-sheathed nano-SiC doped MgB/sub 2/ wires    S.X. Dou, J. Horvat, S. Soltanian, X.L. Wang, M.J. Qin, S.H. Zhou, H.K. Liu and P.G. Munroe Summary: The nano-SiC doped MgB/sub 2//Fe wires were fabricated using a powder-in-tube method and an in-situ reaction process. The depression of T/sub c/ with increasing SiC doping level remained rather small due to the counterbalanced effect of Si and C co-doping. The high level SiC co-doping allowed creation of the intra-grain defects and nano-inclusions, which act as effective pinning centers, resulting in a substantial enhancement in the J/sub c/(H) performance. The transport J/sub c/ for all the wires is comparable to the magnetic J/sub c/ at higher fields despite the low density of the samples and percolative nature of current. The transport I/sub c/ for the 10wt% SiC doped MgB/sub 2//Fe reached 660A at 5K and 4.5T (J/sub c/=133000A/cm/sup 2/) and 540A at 20K and 2T (J/sub c/=108000A/cm/sup 2/). The transport J/sub c/ for the 10wt% SiC doped MgB/sub 2/ wire is more than an order of magnitude higher than for the state-the-art Fe-sheathed MgB/sub 2/ wire reported to date at 5K and 10T and 20K and 5T respectively. There is a plenty of room for further improvement in J/sub c/ as the density of the current samples is only 50%.         Influence of the preparation process on microstructure, critical current density and T/sub c/ of MgB/sub 2/ powder-in-tube wires    S.I. Schlachter, W. Goldacker, J. Reiner, S. Zimmer, Bing Liu and B. Obst Summary: MgB/sub 2/ wires and tapes suffer from a limitation of the transport current densities, especially at low field, due to an unsufficient thermal stabilization caused by hot spots from a nonhomogeneous microstructure, the presence of secondary phases and voids. For the preparation of MgB/sub 2/ wires and tapes two different precursor routes, using MgB/sub 2/ (ex-situ process) or Mg + B (in-situ process) are applied. The in-situ approach allows variation of many parameters in the wire preparation and the improvement of this approach is the central topic of this paper. We present an improved in-situ approach, the characterization of the filament microstructure, effects from stoichiometry and the corresponding superconducting properties. The transport current capability of such in-situ wires could be improved to the level of the reference ex-situ wires.         High I/sub c/ in iron-clad MgB/sub 2/ tape    H. Fang, S. Padmanabhan, Y.X. Zhou, P.T. Putman and K. Salama Summary: Recent studies on metal-clad superconducting MgB/sub 2/ wires indicates that iron is one of the best candidates as a cladding metal. Also it was found that grain refinement of MgB/sub 2/ leads to more compacted material which yields high transport critical current density. In this study, we prepared the iron-clad MgB/sub 2/ tapes by using the powder-in-tube technique. A modified rolling process was applied to cold work the powder-filled tubes into tapes. Very fine grains were observed on as-rolled tapes. Tapes manufactured using this process were found to carry 260 Ampere at 20 K under self-field and 180 Ampere under 1.5 Tesla. The transition temperature is 39.4 K and /spl Delta/T=0.6 K. The results indicate that grain refinement is very effective in improving the current carrying capability of the MgB/sub 2/ tapes.         Study of MgB/sub 2/ powders and Cu/MgB/sub 2/ powder-in-tube composite wires with Zn addition    E. Martinez, L.A. Angurel, R. Navarro, A. Millan, C. Rillo and M. Artigas Summary: In this paper, we investigate the effect of Zn addition in magnesium diboride. This study comprises free powders and Cu-sheathed wires. The powders were prepared by the solid-state reaction of the elements in a sealed silica tube and it has been observed that most of Zn remained unreacted. However, crystal cell parameters and superconducting transition temperatures varied slightly with the nominal ratio of Zn in the superconductor. Cu sheathed superconducting wires were fabricated by conventional powder-in-tube techniques followed by the in situ reaction of Mg, B and Zn powders inside the Cu tube at temperatures below 700/spl deg/C. The analysis of the X-Ray patterns and the magnetic and electrical properties of the materials obtained from different initial Zn concentration are presented.         Influence of Cu addition on microstructure and transport properties in MgB/sub 2/ tapes    Jae-Woong Ko, J. Yoo, Young-Kuk Kim, Hai-Doo Kim, Kae-Hee Oh, S.J. Choe, Hyungsik Chung, Soo Jin Chung, H. Kumakura, A. Matsumoto and K. Togano Summary: Stainless steel sheathed MgB/sub 2/ tapes with Cu addition were fabricated by PIT method. The influence of Cu content on microstructure and the critical-current density (J/sub c/) of the tapes has been studied. The J/sub c/ value of MgB/sub 2/ tapes was increased from 1500 A/cm/sup 2/ to 4500 A/cm/sup 2/ at 4.2 K and 5 T due to Cu addition. J/sub c/-B curves show enhancement in J/sub c/(B), which suggests that the microstructure and transport properties of MgB/sub 2/ have been improved with Cu addition.         Fabrication of MgB/sub 2/ tapes sheathed with carbon steels by ex situ and in situ methods    H. Fujii, K. Togano and H. Kumakura Summary: MgB/sub 2/ tapes sheathed with carbon steel (CS) were fabricated by a powder-in-tube technique with ex situ and in situ methods. The critical current density (J/sub c/) value of the former tape was about 2 kA/cm/sup 2/ at 4.2 K and 10 T by heat treatment at 900/spl deg/C, whereas the J/sub c/ value of the latter tape reached about 3 kA/cm/sup 2/ by heat treatment at temperature as low as 600/spl deg/C. The J/sub c/ anisotropy with respect to field direction of the tapes fabricated by the ex situ method was much larger than that of the tapes fabricated by the in situ method.         Fabrications and properties of MgB/sub 2//stainless-steel tapes by PIT process    K.J. Song, C. Park, N.J. Lee, H.M. Jang, H.S. Ha, D.W. Ha, S.S. Oh, M.H. Sohn, R.K. Ko, Y.K. Kwon and J.H. Joo Summary: We have successfully fabricated single-filament composite MgB/sub 2//Stainless-Steel (SS) tapes using powder-in-tube processes such as swaging and cold rolling. The transport critical currents, that were measured by a standard dc four-probe method, I/sub c//spl sim/316 A and /spl sim/105 A were observed at T=4.2 K with H=0 G for as-rolled and sintered MgB/sub 2//SS tapes, respectively. In addition, the isothermal magnetizations M(H) of sintered MgB/sub 2//SS tapes and commercial MgB/sub 2/ powder were measured at temperatures T between 5 and 50 K in fields up to 6 T, employing a PPMS. The critical current density (J/sub c/) values obtained from the M(H) data, using Bean model, were >5 /spl times/ 10/sup 5/ A/cm/sup 2/ and >5 /spl times/ 10/sup 7/ A/cm/sup 2/ at T=10 K with H=0 G for the sintered MgB/sub 2//SS tapes and the commercial MgB/sub 2/ powder, respectively. On the other hand, we investigated the cross sections of both the sintered and the as-rolled tapes, using SEM and EPMA. No evidence of significant diffusion between MgB/sub 2/ and SS tube was found in the SEM/EPMA. However, traces of reaction can be seen in the interface region between MgB/sub 2/ core and SS tube for the sintered MgB/sub 2//SS tapes, from the EPMA line profiles. In addition, impurity phases such as MgO or MgB/sub 4/, which can be generated inside the superconductor MgB/sub 2/ core during fabrication, were observed by XRD analyses.         The superconducting properties of MgB/sub 2//(stainless steel) tapes fabricated by the PIT process    A. Matsumoto, H. Hatakeyama, H. Kitaguchi, K. Togano and H. Kumakura Summary: We have investigated the superconducting properties of monofilament MgB/sub 2/ tapes and wires with a stainless steel (SUS316) sheath. MgB/sub 2/ powder was put into a SUS316 tube with a 6.5 mm diameter; the tube was cold-rolled into a wire with a 1.4 mm-1.0 mm diameter using groove-rolling and cassette roller dies and then cold-rolled into tapes. The stainless steel sheath is effective to increase the density of the MgB/sub 2/ core. The transport critical current density depends on the wire diameter and tape thickness. The J/sub C/ values increase with increasing the total cross-sectional area reduction of tapes. However, the J/sub C/ value of the tape with a thickness of less than 0.3 mm deteriorated because of cracks introduced by rolling. Post-annealing increased the J/sub C/ properties of these tapes. The low annealing temperature of /spl sim/600/spl deg/C was effective to increase the J/sub C/ values for MgB/sub 2//(stainless steel) tapes. This temperature was much lower than the optimum annealing temperature of MgB/sub 2/ tapes with other sheath materials, such as MgB/sub 2//Fe tapes. The post-annealing improved the linkage of grains and enhanced the J/sub C/ values.         Field dependence of transport J/sub c/ for MgB/sub 2/ superconducting wire by suspension spinning    T. Goto, H. Katoh and K. Watanabe Summary: The field dependence of transport J/sub c/ or MgB/sub 2/ superconducting wire by suspension spinning was examined at 4.2 K in magnetic field up to 10 T. The suspension spinning of commercially available MgB/sub 2/ powder was examined to fabricate a long superconducting MgB/sub 2/ wire. The as-drawn filaments were pressed and pyrolyzed to remove volatile components. The filamentary samples were then cold-pressed, enveloped by an iron sheet with a pellet of mixed powder of Mg and B or with Mg powder, and vacuum-sealed in a fused quartz tube and sintered. The J/sub c/ of the sample was strongly dependent on the starting materials and sintering condition. Although the transport J/sub c/ value was low such as 4500 A/cm/sup 2/ at 4.2 K and self-field, the J/sub c/ value of more than 200 A/cm/sup 2/ was maintained by applying the field of 10 T.         In situ growth of MgB/sub 2/ thin films by hybrid physical-chemical vapor deposition    X.X. Xi, X.H. Zeng, A.V. Pogrebnyakov, S.Y. Xu, Qi Li, Yu Zhong, C.O. Brubaker, Zi-Kui Liu, E.M. Lysczek, J.M. Redwing, J. Lettieri, D.G. Schlom, W. Tian and X.Q. Pan Summary: We have carried out thermodynamics studies of the Mg-B system with the calculation of phase diagrams (CALPHAD) modeling technique and found that the superconductor MgB/sub 2/ phase is thermodynamically stable only under fairly high Mg pressures at elevated temperatures. This has lead us to the investigation of chemical vapor deposition in which the pressure during the film deposition can be high. Although the initial effort on metal-organic chemical vapor deposition (MOCVD) was not successful due to carbon contamination, a unique hybrid physical-chemical vapor deposition (HPCVD) technique has successfully produced high quality in situ MgB/sub 2/ films. The epitaxially-grown MgB/sub 2/ films show high transition temperature and low resistivity comparable to the best bulk samples, and their surfaces are smooth. In this paper, the details of the technique and the results of the HPCVD films are presented.         Thermochemistry of MgB/sub 2/ thin film synthesis    Jihoon Kim, R.K. Singh, N. Newman and J.M. Rowell Summary: We have investigated the thermodynamic and kinetic barriers involved in the synthesis of MgB/sub 2/ films. This work refines our initial conjectures predicting optimal MgB/sub 2/ thin film growth conditions as a consequence of the unusually large kinetic barrier to MgB/sub 2/ decomposition. The small Mg sticking coefficient at temperatures greater than 300/spl deg/C prevents high temperature synthesis with traditional vacuum growth methods. However, as a result of the large kinetic barrier to MgB/sub 2/ decomposition, in-situ thermal processing can be used to enhance the crystallinity and the superconductivity of MgB/sub 2/ films. We used these methods to produce MgB/sub 2/ thin films with relatively high transition temperatures (/spl sim/37 K) by pulsed laser deposition (PLD).         MgB/sub 2/ superconducting films for bolometer applications    E. Monticone, M. Rajteri, C. Portesi, S. Bodoardo and R.S. Gonnelli Summary: Thin superconducting films of MgB/sub 2/ has been prepared on r-plane sapphire and silicon nitride (SiN) by ex-situ technique and co-deposition of B and Mg at several substrate temperatures with the aim to fabricate superconducting bolometers. MgB/sub 2/ films on r-plane sapphire, realized by annealing of a B film at 890/spl deg/C, show a T/sub c/=38 K and RRR=2 while no transition has been observed for MgB/sub 2/ films on SiN above 5 K treated in the same way. A reliable process of MgB/sub 2/ growth on SiN with T/sub c/ between 27 K and 30 K and transition width of 0.5 K has been performed by co-deposition Mg and B and following annealing to 600/spl deg/C.         MgB/sub 2/ thin films and Josephson devices    D. Mijatovic, A. Brinkman, I. Oomen, D. Veldhuis, G. Rijnders, H. Hilgenkamp, H. Rogalla and D.H.A. Blank Summary: Since the recent discovery of superconductivity in MgB/sub 2/, various groups worldwide have been actively studying the growth of thin films based on this material. Impressive progress has been made, but various materials science challenges are still left to be solved. Guided by our own activities in this field, and reports presented in the literature, we reflect here on those challenges and possible ways for further improvement. Being important ingredients for many electronic applications, fabrication of Josephson devices and nano-structures in MgB/sub 2/ thin films will furthermore be described.         Tunnel junctions on as-grown superconducting MgB/sub 2/ thin films    K. Ueda and M. Naito Summary: We demonstrate that good superconductor/insulator/normal-metal tunnel junctions can be fabricated on as-grown superconducting MgB/sub 2/ thin films. The as-grown films were prepared by coevaporation at low growth temperatures of around 280/spl deg/C. The insulating barrier was formed by an Mg overlayer, which is subsequently oxidized in air. The tunneling spectra for Au/MgO/sub x//MgB/sub 2/ junctions showed a reproducible and well-defined superconducting gap (/spl Delta/=/spl sim/2.5 meV). The resultant 2/spl Delta//k/sub B/T/sub c/ was significantly smaller than the predicted BCS value of 3.52.         Microwave properties of MgB/sub 2/ thin films    N. Klein, B.B. Jin, R. Wordenweber, P. Lahl, W.N. Kang, Hyeong-Jin Kim, Eun-Mi Choi, Sung-Ik Lee, T. Dahm and K. Maki Summary: The microwave surface impedance Z/sub s/=R/sub s/+j/spl omega//spl mu//sub 0//spl lambda/ of MgB/sub 2/ thin films was measured via advanced dielectric resonator (DR) techniques. First, the temperature dependence of the penetration depth /spl lambda/ measured with a sapphire puck at 17.9 GHz can be well fitted from 5 K close to T/sub c/ by the standard BCS integral expression assuming the reduced energy gap /spl Delta/(0)/kT/sub c/ to be as low as 1.0-1.1 assuming /spl lambda/(0)=100--110 nm. These results clearly indicate the s-wave nature of the order parameter. Similar good fits were achieved by an anisotropic one gap and an isotropic two-gap model. Second, the temperature dependence of surface resistance R/sub s/, as measured with a rutile puck, indicates an exponential behavior below about T/sub c//2 with a reduced energy gap being consistent with the one determined from the /spl lambda/ data. The R/sub s/ value at 4.2 K was found to be as low as 19 /spl mu//spl Omega/ at 7.2 GHz, which is comparable with that of a high-quality high temperature thin films of YBa/sub 2/Cu/sub 3/O/sub 7/. A higher-order mode at 17.9 GHz was employed to investigate the frequency f dependence of R/sub s//spl alpha/f/sup n(T)/. Our results revealed an decrease of n with increasing temperature ranging from n=2 below 8 K to n=1 close to T/sub c/. Finally, the microwave power handling of MgB/sub 2/ films was deduced and compared with values for YBa/sub 2/Cu/sub 3/O/sub 7/ films. We found that the power handling of MgB/sub 2/ is comparable or even better than that of YBa/sub 2/Cu/sub 3/O/sub 7/ films for temperature below 30 K.         Anisotropy and critical current density of MgB/sub 2/ thin films grown in-situ by molecular beam epitaxy    W. Jo, M.R. Beasley and R.H. Hammond Summary: We report transport properties of superconducting MgB/sub 2/ thin films in-situ grown by molecular beam epitaxy. The MgB/sub 2/ films show a superconducting transition at 34.5 K with /spl Delta/T/sub c/<1 K. We measure the in-plane electrical resistivity of the films in magnetic field to 8 T and estimate the upper critical field H/sub c2//sup /spl perp//(0)/spl sim/32 T for field oriented along the c-axis and H/sub c2//sup /spl par//(0)/spl sim/35 T in the plane of the film. We find the zero-temperature coherence lengths /spl xi//sub c/(0)/spl sim/31 /spl Aring/ and /spl xi//sub ab/(0)/spl sim/36 /spl Aring/, indicating the field anisotropy ratio is 1.2, comparable with reported in-situ epitaxial thin films, but less than single crystals. The calculated electronic mean free path l=25 /spl Aring/ is smaller than the coherence length, which places our films in the dirty limit. Estimates of the critical current density, J/sub c/, using magnetic field hysteresis loops and the Bean critical state model give nominal critical current densities on the order of 10/sup 6/ A/cm/sup 2/ at 15 K and self-field.         Mechanical properties of reinforced MgB/sub 2/ wires    W. Goldacker, S.I. Schlachter, J. Reiner, S. Zimmer, A. Nyilas and H. Kiesel Summary: For technical application in windings of coils, transformers or motors, a reinforcement of MgB/sub 2/ wires and tapes is necessary to withstand applied stresses and strains and to avoid cracks in the filaments. Therefore, the response of the superconducting transport currents on applied axial strain in different magnetic background fields was investigated for differently stainless steel reinforced MgB/sub 2/ wires, by means of an axial strain rig. Increased amounts of stainless steel in the sheath caused a stronger decrease of the critical currents in fields above 3 T as a consequence of a changed irreversibility field. Heat treated wires have a quite different mechanical behavior compared to as-cold-worked wires, but an about 10 times higher transport current level. Tape geometries, having generally higher current carrying capabilities than wires, showed much poorer mechanical properties with a less effective filament precompression from the matrix.         Transport critical current densities and n factors in mono- and multifilamentary MgB/sub 2//Fe tapes and wires using fine powders    H.L. Suo, P. Lezza, D. Uglietti, C. Beneduce, V. Abacherli and R. Flukiger Summary: Mono- and multifilamentary MgB/sub 2//Fe tapes and wires with high transport critical current densities have been prepared using the powder-in-tube (PIT) process. The fabrication details are described. The effect of powder grain sizes and recrystallization temperature on j/sub c/ has been investigated. At 25 K and 1 T, j/sub c/ values close to 10/sup 5/ A/cm/sup 2/ were measured, while j/sub c/ of 10/sup 6/ A/cm/sup 2/ were extrapolated for 4.2 K/0T in our monofilamentary tape. MgB/sub 2//Fe tapes exhibit high exponential n factors for the resistive transition: n/spl ap/80 and 40 were found at 5 T and 7 T, respectively. The highest transport j/sub c/ values obtained so far in MgB/sub 2//Fe wires with 7 filaments were 1.1/spl times/10/sup 5/ A/cm/sup 2/ at 4.2 K and in a field of E2 T, which is still lower than for monofilamentary tapes. The function F/sub p//spl prop/b/sup p//spl middot/(1-b)/sup q/ has been established over the whole field range, and exhibits a maximum at F/sub p//spl cong/0.18. Improved deformation and recovering processing is expected to lead to higher j/sub c/ values.         Effects of metal powder addition on the structure and critical current of Ni-sheathed PIT MgB/sub 2/ tapes    K. Tachikawa, Y. Yamada, M. Enomoto, M. Aodai and H. Kumakura Summary: MgB/sub 2/ commercial powder was encased in a Ni tube and rolled into a monocore tape of about 5 mm in width and 0.3 mm in thickness. Different kinds of metal powder, i.e., In, Sn, Ag, Cu and Ni, were added to the MgB/sub 2/ core. Addition of the low melting point metal powder, e.g., In and Sn, has been found to enhance significantly the J/sub c/ value in MgB/sub 2/ tapes. Annealing at a low temperature yields further increase in the J/sub c/ of tapes with In and Sn addition. The enhancement in J/sub c/ by the In addition and the low temperature annealing reaches a factor of 6-7. The J/sub c/ of the tapes with 10vol% In addition, annealed at 200/spl deg/C for 10 h is on the order of 10/sup 5/ A/cm/sup 2/ at 4.2 K and 0.5 T. The TEM observation shows that In fills up the gaps among MgB/sub 2/ grains. The additional annealing produces better impregnation of In in the core. The improvement in grain linkage seems to be the probable origin for the enhancement in J/sub c/ by the In addition. The optimum amount of In addition to the MgB/sub 2/ core is likely 10-15vol%. Ag, Cu and Ni powder addition yields no apparent effect on J/sub c/ of PIT MgB/sub 2/ tapes.         Effect of grain size and doping level of SiC on the superconductivity and critical current density in MgB/sub 2/ superconductor    S. Soltanian, Xiaolin Wang, J. Horvat, Mengjun Qin, Huakun Liu, P.R. Munroe and S.X. Dou Summary: SiC doped MgB/sub 2/ polycrystalline samples were fabricated by in-situ reaction using different grain sizes (20 nm, 100 nm, and 37 /spl mu/m) of SiC and different doping levels (0, 8, 10, 12, 15 wt%). Phases, microstructures, superconductivity, critical current density and flux pinning have been systematically investigated using XRD, SEM, TEM, and magnetic measurements. Results show that grain sizes of the starting precursors of SiC have a strong effect on the critical current density and its field dependence. The smaller the SiC grains are, the better the J/sub c/ field performance is. Significant enhancement of J/sub c/ and the irreversibility field H/sub irr/ were revealed for all the SiC doped MgB/sub 2/ with additions up to 15 wt%. A J/sub c/ as high as 20,000 A/cm/sup 2/ in 8 Tesla at 5 K was achieved for the sample doped with 10 wt% SiC with a grain size of 20 nm. Results indicate that the nano-inclusions and substitution inside MgB/sub 2/ are responsible for the enhancement of flux pinning.         Suitability of MgB/sub 2/ tapes with iron sheaths for multiturn superconducting coils    K. Sivasubramaniam, E.T. Laskaris and D. Ryan Summary: This paper investigates the suitability of MgB/sub 2/ tapes clad in a high magnetic permeability iron sheath for use in practical multi-turn superconducting coils. The flux-density in the MgB/sub 2/ portion of a single filamentary tape under various configurations is analyzed and its effect on the critical current capability is evaluated. The magnetic field is computed numerically using the finite element (FE) method. The FE model used for the analysis is described along with the assumptions made. The results indicate that the iron-clad MgB/sub 2/ tapes are undesirable for SC coils in many practical applications from a steady state performance stand point.         Improving flux pinning at high fields in intermetallic superconductors: clues from MgB/sub 2/ and MgCNi/sub 3/    L. Cooley, Xueyan Song and D. Larbalestier Summary: We discuss flux pinning and nanostructural analyzes of two intermetallic superconductors that exhibit substantial deviations from the usual flux-shear behavior. Kramer plots for a MgB/sub 2/ thin film, which contained a substantial fraction of MgO nanoprecipitates, show an additional component that is attributed to core pinning by the precipitates. Also, polycrystalline MgCNi/sub 3/ displays a crossover from flux-shear to core pinning behavior as the temperature is reduced. At the same time, the flux line core diameter becomes comparable to the length scales of nanoprecipitates found by high-resolution electron microscopy. Thus, both experiments suggest that flux shear, and its low-field pinning characteristic, can be exceeded by incorporating nanoprecipitates in an intermetallic superconductor. However, too many precipitates within the grain boundaries can block uniform current flow between grains.         Characterization of NbTiN thin films prepared by reactive DC-magnetron sputtering    T. Matsunaga, H. Maezawa and T. Noguchi Summary: Niobium-titanium-nitride (NbTiN) thin films were prepared on quartz substrates by reactive dc-magnetron sputtering with a NbTi alloy target, and their properties, were studied systematically. Properties of the thin films, such as superconducting transition temperature were strongly dependent on variation of cathode voltage, /spl Delta/U, which is induced when a small fraction of N/sub 2/ is added to Ar during sputter discharge. High quality thin films with transition temperature as high as 15 K and resistivity of /spl sim/100 /spl mu//spl Omega/cm have been obtained at around /spl Delta/U=28 V with a total gas pressure of 0.9 Pa. Since gap frequency calculated from the measured critical temperature of 15 K based on BCS theory is about 1.1 THz, these NbTiN thin films are good candidates for wiring layers of SIS mixers as well as SIS junctions in the 1 THz band.         Sputter deposition conditions and penetration depth in NbN thin films    R. Hu, G.L. Kerber, J. Luine, E. Ladizinsky and J. Bulman Summary: NbN films have been reactively sputter deposited from a 15.24 cm Nb target using a variety of deposition conditions. Film penetration depth has been measured using Taber's parallel plate resonator technique. These measurements have been compared with penetration depth measurements obtained from SQUID measurements. Penetration depth results have also been correlated with film superconducting transition temperature, resistivity, resistance ratio, and x-ray diffraction patterns. The films have been deposited over a variety of substrates and buffer layers including oxidized Si, sapphire, and a variety of metal and metal nitride "seed" layers.         Properties of bilayers based on Mo films for transition-edge sensors    M. Rajteri, E. Monticone, C. Gandini, C. Portesi, R. Rocci and S. Bodoardo Summary: Transition-edge sensors (TES) are promising devices for materials science and space applications due to their spectroscopic capabilities and good count rates. In this work, we report details on fabrication and characterization of Mo films and Mo/Ag bilayers that, being immiscible and nonreactive with each other, should have a long time stability. Both single superconducting films and bilayers of normal-superconducting materials have been deposited in UHV by e-gun. Structural and morphological properties have been investigated by x-ray diffraction and AFM. Bilayers with transition widths of 1 mK are achievable, adequate to realize high sensitivity thermometers.         Preparation and characterization of BSCCO 2212 thin films    M. Yavuz, K.K. Uprety, G. Subramanian and P. Paliwal Summary: In this paper, we attempt to grow films on a MgO substrate using Pulsed Laser Ablation, and report on the effect of deposition conditions and post-deposition annealing on the film properties.         Effects of substrate preparation on the stress of Nb thin films    R.B. Bass, L.T. Lichtenberger and A.W. Lichtenberger Summary: It is well known that intrinsic stress plays an important role in the superconducting material properties of niobium (Nb) thin films and in the resulting electrical characteristics of superconducting-insulating-superconducting (SIS) junctions made from these films. The role of sputtering pressure, gun operating parameters and substrate fixturing on Nb film stress has been investigated by a number of researchers. In this paper we discuss the role of wafer preparation on the stress of Nb thin films. We have found that ex-situ substrate cleaning and baking as well as in-situ cleaning and deposition sequencing have a significant effect on the resulting measured film stress.         Texture-related roughness of (Nb,Ti)N sputter-deposited films    N.N. Iosad, N.M. van der Pers, S. Grachev, M. Zuiddam, B.D. Jackson, P.N. Dmitriev and T.M. Klapwijk Summary: We study the properties of (Nb,Ti)N films deposited by reactive magnetron sputtering in an atmosphere of argon and nitrogen at ambient substrate temperature, focusing, in particular, on the technological factors determining film texture and roughness. We find that increasing the adatom energy, while keeping the film chemical composition constant, results in a change of texture from [111] to [100]. Similar changes in film texture are observed as the nitrogen injection decreases for a constant sputtering pressure, indicating that adatom energy is not the only one determining factor. Analyzing the experimental data, it is concluded that nitrogen concentration has a very strong influence on the process of the texture formation, since an increase in nitrogen injection results in an increase in adatom energy, while the film growth is driven toward [111] texturing. Film roughness is strongly related with texture in both experiments, i.e., decreases with an increase in the ratio of [200] and [111] XRD line intensities, indicating that film roughness is determined by crystal habit.         Properties of MgB/sub 2/ films grown by means of different vapor phase techniques    A. Mancini, V. Galluzzi, U.B. Vetrella, V. Boffa, G. Celentano, L. Ciontea, U. Gambardella, G. Grassano, T. Petrisor, A. Rufoloni, S. Sprio and M. Vadrucci Summary: The formation and characterization of MgB/sub 2/ thin films is explored, using room-temperature deposition of precursor layers and subsequent annealing in-situ. Precursors were deposited by means of pulsed laser deposition (PLD), electron beam (EB), and sputtering (SD) techniques. Best results were obtained for B/Mg multilayers deposited by EB and annealed at 630/spl deg/C for 10 minutes, showing typical T/sub Con/ and T/sub C0/ values of about 32-34 K and 31-32 K, respectively. Structural and morphological analyses were performed by x-ray diffraction and SEM. A comparison among the different growth techniques is presented. Results are explained taking into account the pressure-temperature phase diagram of the Mg-B system.         Preparation of as-grown MgB/sub 2/ thin films by co-evaporation method at low substrate temperature    H. Shimakage, A. Saito, A. Kawakami and Z. Wang Summary: MgB/sub 2/ thin film growth on sapphire (0001) and MgO substrates is reported. The thin films were deposited by using the co-evaporation method, in which the deposition rates were well controlled separately. The as-grown thin films demonstrated superconductivity without the use of any post-annealing process. The critical temperature dependence of the substrate temperature and the evaporation rates were investigated, and it was found that a high substrate temperature and high deposition rates are needed to produce high-quality films. Below a substrate temperature of 250/spl deg/C, the films exhibited no x-ray diffraction peaks, but above it, the films tended to grow epitaxially to c-axis on sapphire (0001) substrate. The critical temperature of MgB/sub 2/ film was over 30 K, and MgB/sub 2/ thin films made by co-evaporation method are expected to have excellent properties after further optimization.         MgB/sub 2/ thick films via screen printing    G. Gritzner, M. Kuhberger, S. Tonies and H.W. Weber Summary: We report the fabrication of MgB/sub 2/ thick films using a simple screen printing method. The substrates investigated were mono-crystalline Al/sub 2/O/sub 3/, LaAlO/sub 3/, MgO, ZrO, SrTiO/sub 3/, Si as well as steel. The dense, polycrystalline MgB/sub 2/ films consisted of crystallites with longest dimensions of about 100 nm. No texturing was observed. The transition temperatures T/sub c(0)/ varied between 34 and 36 K with transition widths smaller than 2 K. The critical current densities depended only modestly on the external field. At 6 T critical current densities of 1 /spl times/ 10/sup 8/ A/m/sup 2/ could be measured at 10 K.         Femtosecond optical characterization of MgB/sub 2/ superconducting thin films    Y. Xu, M. Khafizov, A. Plecenik, P. Kus, L. Satrapinsky and R. Sobolewski Summary: We present the fabrication and optical time-resolved photoresponse characterization of MgB/sub 2/ superconducting thin films. The films were prepared on crystalline and flexible substrates by vacuum co-deposition of B and Mg precursors and high-temperature annealing in an Ar atmosphere. The postannealed films exhibited very smooth surfaces and amorphous morphology with nanocrystal inclusions. Optical pump-probe measurements gave the first insight into the carrier dynamics in MgB/sub 2/ by time-resolved experimental studies of the Cooper-pair breaking and thermalization mechanisms.         Magnetic properties of neutron irradiated and doped MgB/sub 2/ superconductors    U.P. Trociewitz, P.V.P.S.S. Sastry, A. Wyda, K. Crockett and J. Schwartz Summary: Studies on the effect of neutron irradiation on MgB/sub 2/ superconductor showed a systematic lowering of T/sub c/ with increasing neutron fluence. The lower T/sub c/ made it difficult to observe the marginal enhancement of flux pinning properties in the neutron irradiated MgB/sub 2/ powders. Partial substitution of Mg in MgB/sub 2/ by Ti, V and Nb yielded pure samples up to 10 at.% doping level. These substitutions had no affect on T/sub c/, which remained constant at 39 K. The effect of doping Mg by Ti, V, and Nb on the flux pinning properties of MgB/sub 2/ was investigated by magnetization measurements. Comparison of the magnetization hysteresis loop widths of the undoped and doped samples showed that the V-doped powders had larger hysteresis loop widths compared to undoped samples indicating enhanced flux pinning in the V-doped samples compared to the undoped and Ti- and Nb-doped samples.         Magnetic shielding in MgB/sub 2//Fe superconducting wires    J. Horvat, S. Soltanian, X.L. Wang and S.X. Dou Summary: Transport critical current (I/sub c/) was measured for MgB/sub 2//Fe round wires, with the magnetic field oriented perpendicular to the wire and parallel to it. Measurements were made on a wire with a pure MgB/sub 2/ core and another wire where the MgB/sub 2/ core was doped with nano-size SiC. This doping strongly improved the vortex pinning in MgB/sub 2/. The field dependence of I/sub c/ was strongly improved due to the presence of the iron sheath. At 30 K, I/sub c/ did not depend on the field for fields between 0.09 and 0.7 T. At lower temperatures, I/sub c/ increased with the field, after an initial decrease, resembling a "peak effect." This effect was extended to higher fields as the temperature was decreased: at 10 K the peak appeared at 3.5 T. This improvement was not due to mere magnetic shielding by iron, but more likely to an interaction between the iron sheath and the superconductor. Improvement of vortex pinning did not affect the range of fields within which this effect was observed. J/sub c/ of SiC doped MgB/sub 2//Fe wires at elevated fields already satisfies the requirements for their use in production of superconducting magnets for particle accelerators.         Magnetic field dependence of the critical current in MgB/sub 2/ and Bi-2223 superconducting tapes fabricated by the powder-in-tube method    A. Malagoli, A. Tumino, V. Braccini, C. Ferdeghini, A.S. Siri, L. Martini, C. Vignola, V. Previtali, G. Volpini and G. Grasso Summary: The transport properties of powder-in-tube processed superconducting tapes based on the Bi-2223 and MgB/sub 2/ compounds were measured at liquid helium temperature as a function of the magnetic field amplitude and orientation with respect to the conductors. Critical current measurements on short samples were performed in a magnetic field up to 20 T. From this data, we found that commercial multifilamentary Bi-2223 tapes, in spite of the well-established processing route, show some differences over a standard common trend, if manufactured by different suppliers. Nevertheless they all carried remarkable transport currents up to the highest magnetic field of measurement. The transport properties of MgB/sub 2/ tapes presented very different features depending on the thermo-mechanical treatment they were subjected to during the fabrication process. A small critical current was measured at a field as high as 16 T on a multifilamentary MgB/sub 2/ tape. In the magnetic field domain below 1 T, MgB/sub 2/ tapes carried critical currents in excess of 1000 A at a critical current density of greater than 4/spl middot/10/sup 5/ A/cm/sup 2/.         A non-destructive, non-contact, quality test of critical current for Ag-BiSCCO tape    A. Gandini, R. Weinstein, D. Parks, R.-P. Sawh and Shi Xue Dou Summary: An accurate noncontact method of characterizing Ag-BiSCCO tape is reported, using the trapped field, B/sub t/, of a field-cooled tape. The dimensions of the tape make it possible to calculate in closed form a very simple expression, relating trapped field to transport current. Short lengths of tape, 4 cm, are used to experimentally confirm the model. The model applies to any length of tape for which length is greater than 5 times the tape width. A schematic of a proposed test apparatus is presented which should permit on-line testing for magnitude of the current, and for cracks, while the tape is in motion during production.         BSCCO-2212 conductor development at Oxford Superconducting Technology    K.R. Marken Jr., H. Miao, M. Meinesz, B. Czabaj and S. Hong Summary: Three types of BSCCO-2212 conductor are in development at Oxford Superconducting Technology (OST). Prototype size batches of multifilament tape continue to be manufactured for use in a 5 T high field insert magnet demonstration in collaboration with the National High Magnetic Field Lab. Progress will be reported in improving uniformity of microstructure and transport properties in these tapes. Development of multifilament wire has been renewed in response to interest from the high energy physics community. Issues of interest in these wires include the effects on J/sub c/ from filament size and distribution, as well as chemical composition and impurity content in the ceramic. Progress in J/sub c/ and J/sub E/ at 4.2 K in these wires will be discussed. Optimization of dip-coated 2212 tape for MRI magnet applications is also underway, as part of a Superconductivity Partnership Initiative. Various cost and performance tradeoffs will be considered, including the silver/ceramic ratio, the thickness of the ceramic, and the choice of batch or continuous heat treatment. The status of these optimization efforts will be reported.         Critical current density and microstructures of thick monocore Bi2212 tapes grown in high magnetic fields    H. Maeda, P.V.P.S.S. Sastry, U.P. Trociewitz, J. Schwartz, K. Ohya and M. Sato Summary: Ag-sheathed Bi2212 monocore tapes with core thickness between 80 and 700 /spl mu/m were heat-treated in flowing O/sub 2/ in magnetic fields up to 15 T. A uniform high-degree of texture is achieved throughout the thickness of the tapes when heat-treated in a magnetic field (H/sub a/) whereas a large portion of nontextured region exists without magnetic field. The critical current density J/sub c/ of the tapes increases with increasing H/sub a/ due to enhancement in texture. The self field critical I/sub c/>1000 A was achieved for tapes with a core thickness of 180 /spl mu/m. However, for tapes with larger core thicknesses, I/sub c/ decreases due to inhomogeneous melting. The magnetic field is more effective in enhancing texture in the early stages of crystal growth.         Biaxially textured superconductor Bi-oxide films via an electrodeposition process    R.N. Bhattacharya, Jun Chen and R.D. Blaugher Summary: An electrodeposition process was used to deposit Bi-2212 precursor films. Biaxially textured Bi-2212 superconductor films were prepared from electrodeposited precursor films by melt-quench/melt-growth processing on Ag-coated LAO substrates. Magnetization measurements for the electrodeposited, Bi-2212 superconductor films show critical current density values greater than 5 /spl times/ 10/sup 6/ A/cm/sup 2/ at 4 K in zero field.         High critical currents in powder in tube MgB/sub 2/ wires: influence of microstructure and heat treatments    L. Civale, A. Serquis, D.L. Hammon, X.Z. Liao, J.Y. Coulter, Y.T. Zhu, T. Holesinger, D.E. Peterson and F.M. Mueller Summary: MgB/sub 2/ wires were produced by the powder-in-tube method, using commercial MgB/sub 2/ powder with 5%at Mg powder added as an additional source of magnesium, and stainless steel as sheath material. Depending on the parameters of the heat treatments, the dc transport critical current can be increased or decreased by more than one order of magnitude as compared with the as-drawn wire. Analysis of the zero-field-cooling dc magnetization demonstrates that these large variations are due to changes in the connectivity of the wires. We discuss the optimization of the annealing conditions in terms of the changes in the microstructure, as determined from TEM and SEM analysis. We show that annealing can strongly improve the connectivity by eliminating most of the micro-cracks present in the un-annealed wires. In contrast, inappropriate annealing conditions result in a deterioration of the connectivity due to the loss of Mg.         The pinning strength and upper critical fields of magnetic and nonmagnetic artificial pinning centers in Nb47/sup w//oTi wires    L.R. Motowidlo, M.K. Rudziak and T. Wong Summary: Nb47/sup w//oTi wire samples were fabricated with copper 12Vol%, 6Ni/6Cu, and 8Ni/4Cu artificial pinning centers (APC). The optimum diameter of the "island" pins was 10 to 12 nm at final wire size. Low temperature heat treatment of sample wires was performed at final diameters to form alloy pins. The upper critical field, Hc/sub 2/, irreversibility field, H/sup */, and the critical current density, J/sub c/, were measured at 4.2 K. Magnetization measurements showed highest Hc/sub 2/ of 11 T and H/sup */ of 9.8 T in the best APC wire. In addition, significant improvement in J/sub c/ was obtained at all fields above 5 T compared to past APC designs. At 5 T, J/sub c/s up to 5034 A/mm/sup 2/ were obtained by transport measurements. Field emission scanning electron microscopy (FESEM) of the pins at near final wire diameters suggest a new feature. The possible presence of voids formed on the outside of each pin as a result of nickel and copper inter-diffusion (Kirkendall effect) from low temperature heat treatment.         Irreversibility fields and upper critical fields in multifilamentary Nb-Ti composites having artificial pins with anisotropic microstructure    Yun Zhu, O. Miura and D. Ito Summary: Anisotropy of upper critical fields B/sub C2/ and irreversibility fields B/sub i/ was investigated for multifilamentary Nb-Ti composites having artificial pinning centers in perpendicular and parallel magnetic fields to the filament axis. It was observed that the B/sub C2/spl par// exceeded the B/sub C2/spl perp// below a certain temperature T/sup */ and the temperature dependence of B/sub C2/spl par// was close to (1-T/T/sub c/)/sup 0.5/. These results suggest that dimensional crossover occurs at T/sup */, i.e., the magnetic flux system in the parallel field changes from 3D to 2D state as predicted by the Takahashi-Tachiki theory for multilayer superconductors. B/sub i/spl par// is also enhanced due to no restriction of the superconductor size, as explained by the flux creep theory. Consequently, the flux pinning strength in the parallel magnetic field to the filament axis increased at high fields. Furthermore, tape specimens with arranged plate-like pins fabricated by rolling process indicated expected enhancement of flux pinning.         A monolithic artificial pinning center Nb-Ti conductor for high current applications    M.K. Rudziak, C.V. Renaud Jr. and T. Wong Summary: Supercon's artificial pinning center (APC) process has been used to produce a large, aspected Nb-Ti conductor for a high current application. The 1.0 mm by 4.05 mm conductor was manufactured for the Lawrence Livermore National Laboratory for use in a prototype quadrupole magnet for a heavy ion driver. The size of the conductor made it suitable as a replacement for Rutherford-type cable. A monolithic conductor of this type cannot be fabricated economically by conventional means due to a lack of available strain space for the necessary thermo-mechanical treatments. Fabrication of the conductor is described and performance characteristics are given.         Effect of layout on magnetization of NbTi strands    G.P. Vedernikov, A.K. Shikov, L.V. Potanina, I.N. Gubkin, A.D. Nikulin, S.I. Novikov and M.S. Novikov Summary: Magnetization measurements at background fields up to 3 T were performed for 4 NbTi strands of various layouts both at a superposition of a sinusoidal varying field with a frequency of 0.5-3 Hz and at fast exponential sweep of external field. Strand layouts are distinguished by filament diameter, Cu/non-Cu ratio and filament zone location in the cross section of the wires. One of the strands contains resistive barriers of CuNi alloy, which surround a filament zone on the both sides. Using magnetization loops, the total and coupling losses for each strand have been calculated along with time constant values. The results showed that no matter how the field variation was performed, minimum losses as well as minimum time constant values were obtained for the sample with smallest filament diameter, having rather small copper core area (4.5%) and resistive CuNi barriers. For the sample with the same filament size but copper core area of 25% both losses and time constant were maximum.         Influence of heat treatment strain parameters on the structure and J/sub c/ of Nb-48.5 wt.% Ti superconductor    O.V. Chernyi, G.E. Storozhilov, N.F. Andrievskaya and V.O. Ilicheva Summary: A multistage heat treatment has been used to form a homogeneous heterophase structure in the Nb-48.5wt.% Ti alloy. The fixed parameters of this treatment were the following: the number of annealings was 4, the temperature and total duration were 390/spl deg/C and /spl sim/400 hours respectively. The degree of plastic strain between consecutive annealings changed across a wide range (/spl epsiv//sub int/= 0.1-1.22). The wire drawing schedule was chosen with both equal and unequal values of /spl epsiv//sub int/. The values for the final strain, /spl epsiv//sub fin/, ranged from 2.3 to 5.6. When equal values of /spl epsiv//sub int/ were used, the level of J/sub c/ obtained in the superconductor was 3640 A/mm/sup 2/ (at 5 T, 4.2 K). When unequal values of /spl epsiv//sub int/ where used in the deformation schedule the J/sub c/ achieved 3840 A/mm/sup 2/. TEM was used to quantitatively evaluate the degree of diffusional decomposition in a supersaturated solid solution at different stages of alloy treatment.         Design of new hollow superconducting NbTi cables for fast cycling synchrotron magnets    H. Khodzhibagiyan, V. Alexeev, S. Averichev, V. Drobin, A. Kovalenko, A. Smirnov, A. Starikov, N. Vladimirova, G. Moritz, E. Fischer, L. Potanina, A. Shikov and G. Vedernikov Summary: Two new options for a hollow NbTi superconducting cable were considered. The first one is based on keystoned wires wrapped around a copper-nickel tube 5 mm in diameter. The second one is a hollow cable of rectangular cross section. The data from cable short sample tests are presented. Some problems with the production technology are discussed. This work is part of the R&D for the Future Accelerator Facility, at GSI in Darmstadt.         Self-field effects on critical current measurements of large multi-strand conductors    M. Greco, P. Fabbricatore, R. Musenich, C. Priano and F. Kircher Summary: We have studied the methods for comparing the values of the critical current measured on superconducting strands with the ones obtained on a complex Rutherford cable made of the same strands. This problem is related to the definition of critical magnetic field for strands and cables carrying a given current, which generates a not negligible and inhomogeneous self-field. The method is based on the evaluation of the electrical field along the conductors carrying currents around the critical value. The developed criteria are adopted for comparing the critical currents measured on short samples of strands and Rutherford cables made of 32 strands embedded in pure aluminum matrix.         Influence of Ta-reinforcement geometry in Nb/sub 3/Sn wires    J. Kondoh, M. Umeda, K. Arai, H. Tateishi, K. Agatsuma and G. Iwaki Summary: We have been developing tantalum-fiber-reinforced bronze process niobium-tin wires for use in large-scale high field magnets. They are fabricated by conventional drawing. We manufactured two kinds of the wires with different geometries but similar volume ratios. We have investigated their characteristics and have clarified that there are some differences in their superconducting critical current, critical magnetic field, critical temperature, and the influence of their heat-treatment conditions.         Compressive strain and critical current properties of Nb/sub 3/Sn conductors reinforced by center-arranged and distributed Ta    T. Takao, Y. Takahashi, T. Ito, M. Yamaguchi, K. Umekawa, J. Kondo and M. Umeda Summary: We have fabricated two kinds of Nb/sub 3/Sn superconductors having the same diameter; one superconductor is reinforced by center-gathered tantalum (Ta) in a cross-section of the conductor, and the other is reinforced by distributed Ta in the cross-section. We applied compressive force to the conductors, and measured degradation of the conductors. When the conductor's strain due to the compressive force to the conductors was zero, a critical current (I/sub c/) of the distributed Ta conductor was larger than that of the center-gathered Ta conductor. However, an I/sub c/ of the distributed-Ta type conductor rapidly decreased, and when the compressive strain became approximately 5 or 6%, the I/sub c/ of the center-gathered Ta conductor exceeded that of the distributed-Ta type. It was experimentally shown that the center-gathered Ta conductor was more tolerant than the distributed Ta conductor about the compressive strain to the conductor.         Three-directional analysis of thermally-induced strains for Nb/sub 3/Sn and oxide composite superconductors    S. Murase, H. Okamoto, T. Wakasa, T. Tsukii and S. Shimamoto Summary: Composite superconductors like Cu/Nb/sub 3/Sn and Ag/Bi-oxides are subjected to thermally-induced residual strain by other component materials due to the around 1000 K temperature difference between the high temperatures where the superconductor is formed and the cryogenic temperatures where they are operated. To clarify especially the radial (r) and (/spl theta/) tangential strain behaviors, we analyzed elastic-plastically two models, the concentric core model (single-core model) and multi-core model and used two analysis methods, calculation of the force balance equation for the former model and computing of FEM for the former and the latter models. Strains in r and /spl theta/ directions varied with combination of component materials having large and small thermal expansion coefficients; the superconductor sandwiched by high thermal expansion materials is subjected to larger tensile r-strain and larger compressive /spl theta/-strain, as compared with superconducting core only embedded in the matrix. Furthermore it was found that there was a strain distribution by the core location at the inner or the outer. Finally, a better combination of the superconductor with other materials was obtained.         The study on the I/sub c/(T, B) dependencies of Nb/sub 3/Sn strands for TF coil-insert of the ITER CS    A.E. Vorobieva, A.K. Shikov, V.I. Pantsyrnyi, N.I. Kozlenkova and K.A. Mareev Summary: The study on the critical current dependencies on magnetic field values in the range 3-12 T and on temperature in the range 4.2-15 K of Nb/sub 3/ Sn strands samples is presented. It is shown that experimental values of I/sub c/(T, B) are well described by relation of Summers with the deformation of -0.25%. The results of volt-temperature characteristics measurements taken in magnetic fields at different currents of a sample are given. The analysis of the dependencies has been done.         Stability and flux jumping of internal-Sn, Nb/sub 3/Sn conductors (and a model system MgB/sub 2/)    M.D. Sumption and E.W. Collings Summary: The flux jump stability of Nb/sub 3/ Sn, internal-Sn strands was investigated using both experiment and calculation. An MgB/sub 2/ bulk sample was also used as a model system. M-H loops were measured in the temperature range of 4.2 K to 15 K for fields up to 1.7 T using a small vibrating sample magnetometer (VSM) system, while /spl plusmn/9 T loops were taken with a larger VSM. Measurement were made on samples up to 3 cm long in transverse fields, and in the form of spiral samples (in axial fields) containing up to 37 cm of sample length. Some strands displayed larger flux jumps at higher fields, and numerous small flux jumps at low fields. In one case, the outer Cu stabilizer was removed from the strand, and as a result the strand became less stable, with flux jumping occurring at higher fields (where the magnetization is lower). Additionally, the influence of ramp rate on flux jumping was investigated. This was done by direct experiment, the use of a model system (MgB/sub 2/), and the extension of existing theory. It was found that the maximum instability, which is related to the maxima in dJ/dT, could occur off-axis. Additionally, higher ramp rates led to decreased stability. This was seen to lead in some cases to a ramp rate dependence in the field position of the flux jump.         Microchemical and microstructural comparison of high performance Nb/sub 3/Al composites    P.J. Lee, A.A. Squitieri, D.C. Larbalestier, T. Takeuchi, N. Banno, T. Fukuzaki and H. Wada Summary: We have performed a comparison of the microstructures of state of the art Nb/sub 3/Al composites processed using both ordinary RHQT (rapid-heating, quenching and transformation) and TRUQ (transformation-heat-based up-quenching) routes. Cross-sections were examined in the as-quenched, untransformed, and final size strands including Cu-clad strand. Both grain size and microchemistry were examined using a high resolution FESEM in BEI mode, using low accelerating voltage for grain orientation contrast and high voltage for atomic number contrast. The grain size is relatively large in these composites with a Feret diameter of 1300 nm for the TRUQ processed strand (compared with 70 to 160 nm for Nb/sub 3/Sn composites). In the untransformed strand electron backscatter indicated residual chemical inhomogeneity associated with the jelly-roll precursor. In the final strands the variations were much less but longitudinal cross-sections revealed the residual chemical inhomogeneity extending along the strand length. In both the ordinary and TRUQ (Cu and Cu-clad) processed strands a 1 /spl mu/m thick 2-phase reaction layer was revealed on the outside surface of the outer filaments that had an average composition of 10% Al and 90% Nb. D.C. Magnetization measurements at 12 K indicated a 1 T improvement in irreversibility field, H/sup */, for the TRUQ strand compared with ordinary RHQT strands.         Cu-added jelly-roll Nb/sub 3/Al superconductor with various Nb/Al spacings and compositions    N. Tatsumi, T. Takeuchi, Y. Iijima, N. Banno, F. Matsumoto, T. Kiyoshi, K. Inoue, H. Wada, T. Fukuzaki, K. Tagawa and G. Iwaki Summary: Rapid-heating, quenching, and transformation (RHQT)-processed Nb/sub 3/Al was found to provide high critical current density in high field by Cu addition. There seems to be a difference in the reaction path to A15 between binary Nb/Al (non-Cu-addition) and the Cu added ternary. In the binary case, a Nb/Al composite reacted to form a bcc phase through rapid-heating and quenching (RHQ) treatment and then it was transformed into A15 phase including stacking faults by an 800 /spl deg/C heat treatment. On the other hand, when Cu was added, the composite reacted to form A15 phase including stacking faults through RHQ treatment directly. We fabricated Cu added jelly-roll (JR) Nb/Al wire with various Nb/Al layer thicknesses and compositions and investigated their effect on RHQ process. The Cu added JR wire of Al poor composition for Nb/sub 3/Al stoichiometry showed a behavior similar to the binary. Al rich composition showed a behavior similar to the Cu-addition case. In this work we discussed the Cu addition effect by considering these results.         Optical microstructure and superconducting properties in jelly-roll Nb/sub 3/Al multifilamentary wire by rapid heating    N. Harada, H. Yamada, M. Tsuda, T. Hamajima, T. Takeuchi and H. Wada Summary: To form the stoichiometric composition in the A15-phase, a rapid quench from the stable region at high temperatures is needed. Jelly-roll Nb/sub 3/Al wire with a Nb matrix is ohmically-heated up to 2000 /spl deg/C during 0.1 sec in a vacuum. An optimization of rapid heating conditions is needed to an improve critical current density at high field because very short heating times and high temperature close to melting points of the Nb/sub 3/Al filaments and Nb matrix are used. The magnetic field dependence of critical current density, J/sub c/, and the critical temperature, T/sub c/, were studied as a function of the maximum temperature, T/sub m/, using short samples that were heat-treated systematically. The cross-sections of these typical samples are analyzed by optical microscopy on various rapid heating conditions. In the short heating time of a range of 0.32-0.46 sec, the filament regions heated up to 2000 /spl deg/C would be uniform and have relatively homogeneous superconducting properties. In the samples with long heating time, the filaments reacted with around matrix. The filament regions heated up to 2300 /spl deg/C are inhomogeneous and some filaments melted.         Direct formation of A15 phase through RHQ treatment in RIT processed Nb/Al-Cu precursor wire    Y. Iijima, A. Kikuchi, N. Banno, T. Takeuchi and K. Inoue Summary: In Nb/sub 3/Al wire with 2.5at% added copper, the Nb/sub 3/Al filaments form directly during a RHQ (rapid heating and quenching) treatment and show excellent superconducting properties. The Nb/sub 3/Al filaments appear to form rapidly during the quenching, because many stacking faults are observed. We found that two different transformation conditions yielded excellent superconducting properties. At high temperature, the Cu-added Nb/sub 3/Al wire showed T/sub c/ of 18.3 K, B/sub irr/ (4.2 K) of 29.3 T, and J/sub c/ (4.2 K, 20 T) of 800 A/mm/sup 2/, while at lower temperature these values were 18.2 K, 29.4 T, and 710 A/mm/sup 2/. Although the resultant properties are similar, the latter processing conditions produced a significant quantity of /spl sigma/-phase particles. The net J/sub c/ (4.2 K) of Nb/sub 3/Al phase in this latter wire is very high, e.g., 1760, 1180, and 700 A/mm/sup 2/ at 18, 20 and 22 T respectively.         Nb/sub 3/Sn phase growth and superconducting properties during heat treatment    E. Barzi and S. Mattafirri Summary: The layer growth and superconducting properties of Nb/sub 3/Sn are investigated as a function of the heat treatment (HT) duration and temperature for internal tin and powder-in-tube strands at 650 /spl deg/C, 700 /spl deg/C and 750 /spl deg/C. For all times and temperatures, the Nb/sub 3/Sn layer thickness is measured, the critical current at 4.2 K is tested as a function of magnetic field, and the upper critical field is obtained through parameterization. Results of the layer critical current density are also shown as a function of HT duration and temperature.         Kinetics of phase growth in the Cu-Sn system and application to composite Nb/sub 3/Sn strands    S. Mattafirri, E. Barzi, F. Fineschi and J.-M. Rey Summary: Nb/sub 3/Sn is the superconductor most used in the R&D of high field accelerator magnets by either the wind&react or the react&wind technique. In order to program the low temperature steps of the heat treatment, the growth kinetics of Cu-Sn intermetallics was investigated as a function of duration and temperature. The diffusion constants of /spl eta/, /spl epsiv/ and /spl delta/ phases between 150 /spl deg/C and 550 /spl deg/C were evaluated using Cu-Sn model samples. For an accurate data analysis, statistical and systematic errors were determined. Next the behavior of Internal Tin and Modified Jelly Roll Nb/sub 3/Sn composites was compared with the model predictions.         The microstructure and microchemistry of high critical current Nb/sub 3/Sn strands manufactured by the bronze, internal-Sn and PIT techniques    P.J. Lee, C.M. Fischer, M.T. Naus, A.A. Squitieri and D.C. Larbalestier Summary: Recent advances in Nb/sub 3/Sn conductor development have advanced the non-Cu critical current density, J/sub c/, from 2000 A/mm/sup 2/ to almost 3000 A/mm/sup 2/ (12 T, 4.2 K). We have quantified a variety of state of the art composites for their microstructures using the fracture/field emission scanning electron microscope, FESEM, technique and their microchemistry using energy dispersive X-ray spectroscopy (EDS)/FESEM. The results of the measurements increasingly point to the importance of A15 composition in determining the critical current density as well as grain size. The highest critical current densities, however, are being attained by the internal Sn process which has yet to achieve as high a level of Sn (23-24.5 at.% Sn) in the A15 as for powder-in-tube (PIT) in which we measure as high as 25-26 at.% Sn. When Sn diffuses into the Cu stabilizer, it is found to have a great affinity for Nb/sub 3/Sn formation than dissolution into the Cu. A15 forms at the Nb-stabilizer surface with local Cu concentrations within the grains of the stabilizer of less than 0.1 at.% Cu. Elevated levels of Sn, however, were observed at the Cu grain boundaries. Both the quantified variations in composition and the peak levels of Sn indicate that further increases in performance should be expected.         Development, heat treatment optimization and microstructural characterization of Nb/sub 3/Sn superconductor wire    C.A. Rodrigues, J.P.B. Machado and D. Rodrigues Jr. Summary: The optimization of the heat treatment profile for Nb/sub 3/Sn superconductor wires is one of the most difficult steps to process this material. The present work had the objective to optimize the heat treatment profile to form the Nb/sub 3/Sn phase. It was developed an internal-tin Nb/sub 3/Sn strand with 1.0 mm in diameter, 12 065 Nb filaments with average diameter of 3.4 /spl mu/m, 26 cores of Sn and internal stabilization of Cu surrounded by Ta diffusion barrier. Samples were removed for heat treatment optimization using different profiles to analyze the Sn diffusion and CuSn formation at temperatures up to 575 /spl deg/C. A final treatment at 700 /spl deg/C was used to form the Nb/sub 3/Sn phase. After the heat treatments, samples were removed for microstructural characterization. Measurements of T/sub c/ and J/sub c/ were performed to analyze the influence of the heat treatments on the superconducting phase and on the transport properties. It was concluded that the use of a two step heat treatment of 575 /spl deg/C/100 h + 700 /spl deg/C/100 h is as efficient as the use of a heat treatment with more low temperature steps.         Nb/sub 3/Sn wires synthesized by rapid-heating/quenching process of rod-in-tube wire precursors    A. Kikuchi, Y. Iijima, K. Inoue, F. Buta, M.D. Sumption and E.W. Collings Summary: A rod-in-tube technique (RIT) for the fabrication of Nb/sub 3/Sn precursor wire has been developed. Through this process we expect to increase the volume fraction of A15 phase in the wire, since no bronze remains unlike commercial Nb/sub 3/Sn wires. However, it is very difficult to cold-work a Nb/Sn composite, because pure Sn is too soft compared with Nb, as well known. We found that the hardness of Sn increases with the addition of small amount of Bi, and resulting Nb/Sn-Bi composite wires with 50 m length could be fabricated by the RIT technique. The RHQ (rapid-heating/quenching) process was applied to these strands as the heat treatment technique. The Nb/sub 3/Sn precursor wire has a Ta sheath in order to bear the high temperature RHQ treatment. Although the Nb-Sn supersaturated bcc solid solution was not synthesized, unlike the case of Nb/Al micro composites, the A15 phases formed directly by the RHQ treatment. The maximum T/sub c/ of 18.3 K was obtained, which is slightly higher than that of the bronze-processed Nb/sub 3/Sn. T/sub c/, J/sub c/ (4.2 K) and B/sub c2/ were increased with decreasing peak heating temperature. The addition of Bi seems not to have negative influences on the superconducting properties of Nb/sub 3/Sn.         Finite element modeling of hydrostatic extrusion for mono-core superconductor billets    X. Peng, M.D. Sumption and E.W. Collings Summary: This paper is concerned with the hydrostatic extrusion of mono-core, bronze-process superconductor billets. The thermo-mechanical, elasto-plastic finite-element method is used to analyze the extrusion process of Nb/bronze mono-core rods. Simulations were performed to determine the distributions of stress, strain and temperature for several extrusion ratios, die angles and core/sleeve interfacial friction coefficients. In addition, the normal pressure at the core/sleeve interface was recorded as a function of die angle and extrusion ratio, which will be useful for the investigations of the bonding process during hydrostatic extrusion.         Fabrication of high-field Nb/sub 3/Sn conductors from Sn-Ta/Nb composites    K. Tachikawa, R. Kato, M. Aodai, H. Izawa and T. Takeuchi Summary: The mechanism of thick (Nb,Ta)/sub 3/Sn layer synthesis in the Ta-Sn core/Nb (Nb-Ta) sheath composite is studied. The diffusion of Nb from the sheath to the core seems to play a key roll to enhance that of Sn from the core to the sheath synthesizing (Nb,Ta)/sub 3/Sn layer. A simplified powder core process, in which Ta + Sn mixed powder is used instead of Ta-Sn reacted powder as the core, does not degrade the high-field performance of the (Nb,Ta)/sub 3/Sn conductor. A finer dispersion of Ta in the core is found to improve the J/sub c/ of the conductor below 23 T. New Jelly Roll processed (Nb,Ta)/sub 3/Sn wires are fabricated using Sn-Ta sheets richer in Sn. The JR wires exhibit attractive high-field performance, and a small amount of Cu addition to the Sn-Ta sheet effectively decreases the reaction temperature.         Superconducting properties of rapidly heated and quenched Nb/sub 3/Ga wires    K. Inoue, A. Kikuchi, Y. Iijima and Y. Yoshida Summary: Stoichiometric Nb/sub 3/Ga with good long range ordering shows a high T/sub c/ above 20 K and a high H/sub c2/(4.2 K) above 30 T. However, high J/sub c/ had not yet been reported for any Nb/sub 3/Ga fabricated through various methods, which was preventing the development of practical Nb/sub 3/Ga conductors in the last 30 years. Recently we could overcome the problem through a promising combination of RHQ (rapid heating and quenching) treatment and microcomposite precursor wire of Nb and NbGa/sub 3/. Nb/sub 3/Ga layers were formed directly through the RHQ treatment. Post annealing at 600-800/spl deg/C was very effective in improving the superconducting properties of the Nb/sub 3/Ga wire. The best values of T/sub c/ and B/sub c2/(4.2 K) of 19.7 K and 32 T were obtained, respectively. In addition the J/sub c/(4.2 K) values of Nb/sub 3/Ga layer at 20 T, 23 T, and 25 T were 370 A/mm/sup 2/, 250 A/mm/sup 2/ and 160 A/mm/sup 2/, respectively. These critical values are much higher than those of the commercialized (Nb,Ti)/sub 3/ Sn wire made through a bronze route.         Fabrication of Nb/sub 3/(Al,Ge) wires by using Al-Ge gas-atomized powder    A. Kikuchi, Y. Iijima, K. Inoue, M. Kosuge, M. Yuyama, N. Banno, T. Takeuchi, S. Nimori and J. Kusui Summary: As the starting material of Nb/sub 3/(Al,Ge) precursor wires, gas-atomized Al-Ge alloy powder is very promising because of the fine Ge particle dispersion in the alloy powder. The hardness of Al-Ge alloy is relatively small and well-balanced with that of the pure Nb. Therefore, no intermediate annealing is technically required for drawing a 7 /spl times/ 220 /spl times/ 233-core Nb/Al-Ge multifilamentary wire. Furthermore, excellent J/sub c/-B performance without peak effects was obtained in the Nb/sub 3/(Al,Ge) tape specimens through the RHQ (rapid-heating/quenching) treatment. It may be caused by the synthesizing of A15 phases transformed from Nb-Al-Ge ternary supersaturated bcc phase. The present Nb/sub 3/(Al,Ge) tapes show a good agreement with Kramer's scaling law described as F/sub p/=A(B/sub c2/)/sup 2.14/b/sup 0.5/(1-b)/sup 1.46/, where A is temperature and field independent, and b=B/B/sub c2/.         New fabrication approach to fine multifilamentary Nb/sub 3/(Al,Ge) superconductors using an intermediate rapid quenching technique    N. Banno, T. Takeuchi, M. Kosuge, M. Yuyama and H. Wada Summary: Drawability of Nb/Al-Ge composite has been improved by a reel-to-reel intermediate rapid quenching technique. The intermediate rapid quenching is performed at an early stage of the fabrication process of multifilamentary wires to convert the coarse Al-Ge core structure into very fine microstructure. Depending on the heat treatment condition, an Al-Ge nano-structure can be obtained in the core. The hardness of the Al-Ge core is balanced with that of the Nb matrix. This technique thus allows construction of multifilamentary structure easily. In addition, it also allows an easy increase of Ge content to 25 at% in the Al-Ge core and reduction of the nonsuperconducting matrix ratio to less than 1. By a diffusion reaction heat treatment at 1400/spl deg/C for the developed multifilamentary Nb/Al-Ge wire, non-Cu J/sub c/=75 A/mm/sup 2/ at 21 T, 4.2 K has been obtained so far.         Transport properties of long-lengths of RHQT processed Nb/sub 3/Al conductor    T. Takeuchi, K. Tagawa, T. Fukuzaki, N. Banno, K. Aihara, K. Fukushima, M. Kosuge, M. Yuyama, F. Matsumoto, T. Kiyoshi, N. Tatsumi, S. Matsumoto and H. Wada Summary: A rapid heating and quenching (RHQ) operation along a long-length of jellyroll Nb/Al precursor over 300 m has been established. The J/sub c/ varies sensitively with the joule-heating current (I/sub RHQ/) that determines the temperature from which a precursor wire is quenched, excluding the "plateau" region where the bcc supersaturated-solid solution (Nb(Al)/sub ss/) only forms. The RHQ operation using such a plateau condition can suppress a scatter of J/sub c/ from point to tail of a long-length of wire. The standard deviation of J/sub c/ (4.2 K) at 21 T along a long-length of wire was about 5%, which was less than the variation of J/sub c/ with I/sub RHQ/ in the plateau region (/spl plusmn/7%). The mechanical deformation process needed when incorporating the Cu stabilizer also plays an important role in ensuring uniform heat treatment of the coil that is wound with a long-length of wire and, hence, large heat capacity. Although a temperature ramp-up rate might differ from place to place in the coil, the deformation processing makes such a ramp-up rate insensitive to these critical parameters. The coils using 300.5 m and 254 m lengths of Cu-clad RHQT JR Nb/sub 3/Al conductor generated additional 2.3 T and 3.2 T in bores of 90.2 mm/spl phi/ and 64.6 mm/spl phi/, respectively, indicating that a long-length of RHQT JR Nb/sub 3/Al conductor can be trustworthy for practical coil applications.         Influence of transformation heat treatment on microstructure and defects in RHQT-processed Nb/sub 3/Al    F. Buta, M.D. Sumption and E.W. Collings Summary: Nb-Al jelly-roll composite wires of stoichiometric composition (25 at% Al) have been processed by Rapid Heating-Quenching (RHQ) to temperatures just above the bcc formation reaction. Transformation heat treatments going to 800/spl deg/C and 1000/spl deg/C with various initial heating ramp-up times (from 30 sec to 30 min) and followed by 800/spl deg/C/10 hrs were applied to samples so obtained. The microstructure and planar defect distribution were investigated by transmission electron microscopy; the concentration of planar defects was found to decrease as the initial heating rate is increased. In situ high temperature X-ray diffraction studies were used to investigate the transformation heat treatment. It is proven that less ordering of the bcc solid solution prior to conversion to A15 occurs at high heating rates.         Phase stability at high temperatures in the Nb-Al system    F. Buta, M.D. Sumption and E.W. Collings Summary: The phases present in the Niobium-Aluminum system were investigated by X-ray diffraction and scanning electron microscopy on jelly-roll composites of 23.5, 27.5 and 35.0 at% Al, quenched after being heated in various time intervals (0.3 sec-5 min) to temperatures in the vicinity of the bcc formation temperature. In the present configuration, at concentrations around 27.5 at% Al the bcc phase is the product of an eutectoidal reaction between A15-structure Nb/sub 3/Al and sigma-phase Nb/sub 2/Al. This eutectoid has not been found in any of the published equilibrium phase diagrams, a revised equilibrium phase diagram is proposed.         Nb/sub 3/Al strand processing, transport properties, and cabling    M.D. Sumption, F. Buta, M. Tomsic, A. Austen, E. Gregory, M. Rudziak, T. Wong, L. Motowidlo, Y. Hascicek, R.M. Scanlan, H. Higley and E.W. Collings Summary: Nb/sub 3/Al strands with four different designs have been processed and tested. Strand specifications and some generic aspects of strand fabrication, processing, and testing are described. One strand type was long-length RHQT processed and transport tested at various lengths. Transport J/sub c/ results for short samples and small solenoid coils are presented and discussed for various RHQT protocols. Critical current measurements on various strands have been performed in fields from 18 to 26 T. Various strand stabilization techniques have been investigated including electroplating, plasma spray coating, and direct Nb-Cu high temperature diffusion bonding; these results are described. Fifty meters of strand was RHQ processed and then cabled into a short length of experimental 12-strand Nb/sub 3/Al Rutherford cable in preparation for transformation (T) and testing. Cabling properties are described.         High field Nb/sub 3/Sn conductor development at Oxford Superconducting Technology    J.A. Parrell, Youzhu Zhang, M.B. Field, P. Cisek and Seung Hong Summary: Oxford Instruments, Superconducting Technology (OI-ST) produces Nb/sub 3/Sn wire via several "internal Sn" routes. Recently, 12 T, 4.2 K non-Cu critical current density (J/sub c/) values of /spl sim/2900 A/mm/sup 2/ have been achieved by increasing the Nb and Sn fractions of the filament subelements. Similar conductors for high field use have shown engineering current density (J/sub e/) values of 170 A/mm/sup 2/ at 23.5 T, 1.8 K. OI-ST is also involved with research for the High Energy Physics (HEP) National Conductor Program. Results on composites made entirely by hot extrusion are described. Finally, the present status of Ta-Sn powder-in-tube (PIT) and Nb/sub 3/Al precursor strand development are presented. PIT strands have irreversibility fields over 26 T at 4.2 K, while Nb/sub 3/Al precursor strand has been produced by a route that promotes bonding of the billet components.         Development of Nb/sub 3/Sn conductors for fusion and high energy physics    T. Pyon and H. Kanithi Summary: In the recent years internal-tin Nb/sub 3/Sn conductors have been developed to a stage where the critical current densities obtainable are triple those exhibited by the bronze processed material. Outokumpu Advanced Superconductors has been producing a commercial quantity of Nb/sub 3/Sn wires mainly by using the internal-tin process. Nb/sub 3/Sn conductors, regardless of the method used in their fabrication, have to be made of different designs depending on their specific application. This paper describes design parameters of internal-tin Nb/sub 3/Sn conductors, which have been developed and made recently for use in fusion and high energy physics magnets, in particular. Their properties including the current carrying capacity and magnetization are given. The trade-offs between the critical current densities, AC losses, and how the design parameters affect these properties are also discussed.         Fabrication and performance of multifilamentary Nb/sub 3/Sn wires by the cable-in-tube approach    S. Pourrahimi, E.J. McNiff and N. Pourrahimi Summary: A newly developed method of fabricating multifilamentary composite wires, referred to as the cable-in-tube (CIT), is described. CIT eliminates a number of the conventional processing steps including straightening, hexing, bundling, extruding, HIP etc. CIT processing is particularly advantageous in the fabrication of economical and high performance internal-tin Nb/sub 3/Sn wires. Recent successes in fabricating internal-tin wires with high Nb filament content, and tin diffusion distances of 10-20 /spl mu/m are discussed. Microstructure and superconducting properties of these wires are presented.         Continued progress on a low cost high current density mono element internal tin conductor (MEIT) with integral barriers    B.A. Zeitlin, E. Gregory, T. Pyon and R.M. Scanlan Summary: Progress on Mono Element Internal Tin superconductor is presented for four designs with two incorporating integral Nb barriers as opposed to NbTa barriers added later in the fabrication. Processing information is also presented covering the fabrication of these conductors. Sample testing techniques are discussed that gave stable reproducible results to 10 T at current densities of 3767 A/mm/sup 2/ (noncopper). Current density as a function of magnetic field from 10 to 17 T is measured and analyzed with respect to heat treatment and configuration. A value of 2700 A/mm/sup 2/ in the noncopper at 12 T was achieved in the best though nonoptimized samples. Kramer plots are also presented that show H/sup */ of up to 26 T. Reported "n" values are 33 at 17 T for the highest current density sample.         Fabrication and properties of PIT Nb-Al and Nb-Sn based superconductors    M.D. Sumption, X. Peng, E. Lee, F. Buta, M. Tomsic and E.W. Collings Summary: Multifilamentary PIT Nb-Al and Nb-Sn strands have been fabricated and tested. Three main conductor variants were investigated; Nb/sub 3/Al, Tube-Wall-Reaction (TWR) Nb/sub 3/Sn, and Internal Reaction (IR) Nb/sub 3/Sn. Multifilament restacks of 7, 19, 30, and 37 filaments were fabricated and tested. The powders were formed by mechanical alloying in a planetary mill with subsequent jet milling for particle refinement. In the case of Nb/sub 3/Al, ductile Al was added to the intermetallic compound before filling; while for Nb/sub 3/Sn based conductors, Cu was added. All Nb/sub 3/Sn strands were alloyed with Ta. Phase formation and transport properties are described. In the case of TWR Nb/sub 3/Sn strands, the nature and thickness of the reaction layer was investigated. For monofilaments, the reaction layer was roughly 50 /spl mu/m thick, for 37 filament strands it was only 5 /spl mu/m. SC layer J/sub c/ values of 2680 A/mm/sup 2/ at 12 T were obtained, but quench limited because of the short samples used in the present work.         Status of powder-in-tube Nb/sub 3/Sn conductor development at Supercon    C.V. Renaud Jr., L.R. Motowidlo and T. Wong Summary: Multifilament Nb/sub 3/Sn superconductor has been produced by the powder-in-tube approach. The conductor possesses filament diameters below 60 micrometers with layer J/sub c/ of 4158 A/mm/sup 2/ at 12 T and 4.2 K. Niobium tube fabrication, wire processing, filament uniformity, and Nb/sub 3/Sn microstructure are discussed, and the superconducting properties are presented. A process for producing phase pure NbSn/sub 2/ powder of 1-5 micrometer particle size has been developed and is discussed along with plans for further conductor improvements.         New size sorting technology for superconducting powders    X.K. Fu, A. Gupta, P.M. McIntyre and D.J. Phares Summary: A new technique is being developed to make it possible to achieve defect-free particle size sorting of the precursor powders for multi-filament superconductors, Nb/sub 3/Sn, Bi-2212 and Bi-2223. Sharp cutoff is critical in the effort to achieve small filament size in multi-filament composites of Nb/sub 3/Sn, Bi-2212 and Bi-2223. Accelerator Technology Corp. (ATC) has developed an approach using a slot-geometry virtual impactor to critically remove the coarse particles. Representative Fe/sub 2/O/sub 3/ and Bi-2212 powders were chosen to evaluate its performance. The results show that a sharp cutoff /spl sim/3 microns separation has achieved in both two powders.         Phase equilibria in the quinary BSCCO    J.K. Meen, V.J. Styve, K. Muller and C.L. Nguyen Summary: Melting relations of Bi-2212 and Bi-2201 as a function of oxygen pressure are explicable in terms of increasing amounts of univalent copper in the liquids under more reducing conditions. The effects of the change of copper valence are manifold and not easily predicted. The melting temperatures of cuprates in the Bi-2212 composition results in rotation of the phase relations so Bi-2212 melts along five different liquid lines of descent. Furthermore, Bi-2212 melts at different isobaric invariant points and, in one narrow range of oxygen pressure, on an isobaric univariant line. In this pressure range the amount of liquid produced at the solidus is maximized and only two crystalline phases exist in the supersolidus. As these are both alkaline earth cuprates, all Bi is in the liquid in this region. The maximum Cu content of Bi-2201 is strongly influenced by temperature - only in a narrow temperature range near the solidus does stoichiometric Bi-2201 exist. Lowering oxygen pressure results in a depression of the melting temperature so that if the partial pressure of oxygen is less than 0.5 bars, stoichiometric Bi-2201 does not form. In addition to the limitation of this phase to Cu-deficient compositions, the lowering of oxygen pressure causes a decrease in size of the CuO primary phase field. The Bi-2201-CuO join is a thermal divide at higher oxygen pressures but is pierced at lower values.         Twin spacing and its correlation with critical current density in melt-textured YBCO with yttria nanoparticle addition    O. Jongprateep and Siu-Wai Chan Summary: Twin boundaries have been proved to be effective flux pinning centers in YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO). Increases in twin density yield higher values of critical current density. Twin spacings in melt-textured grown (MTG) YBCO with different amounts of yttria nanoparticles were investigated with a new x-ray method. Twin spacings from the x-ray method were compared with those from transmission electron microscopy to show applicability. From investigation, MTG-YBCO with 11.9 weight percent yttria and oxygenation temperature at 680/spl deg/C showed a colony size of 3.65 microns. This particular sample had a small twin spacing of 33 nm with a corresponding high value of critical current density (J/sub c/) of 1.2 /spl times/ 10/sup 4/ A/cm/sup 2/.         High pressure synthesis and sintering of MgB/sub 2/    T.A. Prikhna, W. Gawalek, Ya.M. Savchuk, A.B. Surzhenko, M. Zeisberger, V.E. Moshchil, S.N. Dub, V.S. Melnikov, N.V. Sergienko, T. Habisreuther, D. Litzkendorf, S. Abell and P.A. Nagorny Summary: High pressure (HP) synthesized MgB/sub 2/ (from Mg scobs and amorphous B with Ta addition in the form of powder of about 2-10 wt%) exhibits critical current density j/sub c//spl ges/10/sup 5/ A/cm/sup 2/ up to 4 T field at 10 K, 2.5 T at 20 K and 0.5 T at 30 K; j/sub c//spl ges/10/sup 4/ A/cm/sup 2/ up to 7.3 T at 10 K, 4.5 T at 20 K and 1.5 T at 30 K; j/sub c//spl ges/10/sup 3/ A/cm/sup 2/ up to 10 T at 10 K and 6 T at 20 K. In our high-pressure apparatuses we can produce samples about 60 mm in diameter and 20-30 mm in height that might be used for superconductive devices such as electromotors, generators, flying wheels, current limiters, noncontact bearings, etc. In synthesis and sintering process Ta plays the role of an absorbent of impurity gases (hydrogen, nitrogen, etc.) and forms Ta/sub 2/H, TaH, TaN/sub 0.1/, etc., thus promotes the reduction of MgH/sub 2/ in samples, as well as, the impurity nitrogen and oxygen in Mg-B grains (black MgB/sub 2/ single crystals distributed over the matrix). In the materials with better superconductive characteristics, we observed some amount of unreacted Mg and higher density of MgB/sub 2/ single crystal inclusions. We have got some evidence that the amount of oxygen in the matrix Mg-B-O and the microdeformation of MgB/sub 2/ lattice influence the critical current density of the material. The HP-synthesized samples have exhibited a microhardness of H/sub v/=12.54 /spl plusmn/ 0.86 GPa at 0.496-N load and a fracture toughness of 4.24 MN /spl times/ m/sup -3/2/ at 4, 96-N load. The HP-sintered MgB/sub 2/ has a microhardness of H/sub v/=17.1/spl plusmn/1.11 GPa at 4.96 N-load, H/sub v/=10.12 /spl plusmn/ 0.2 GPa and fracture toughness of K/sub 1C/=7.6 /spl plusmn/ 2.0 MN /spl times/ m/sup -3/2/ at 147.2 N-load and the Young modulus of 213 /spl plusmn/ 18 GPa. The hardness (at 60-mN load) of MgB/sub 2/ single crystals located in a sample matrix is 35.6 /spl plusmn/ 0.9 GPa that is higher than the hardness of sapphire (31.1 /spl plusmn/ 2.0 GPa) and their Young modulus is 385 /spl plusmn/ 14 GPa (sapphire has 416 /spl plusmn/ 22 GPa) and that gives us grounds to assign MgB/sub 2/ to superhard materials as well.         Equilibrium behavior and critical current density in polycrystalline MgB/sub 2/    T.B. Doyle, A. Wisniewski, M. Eisterer and H.W. Weber Summary: A simple "effective media" approach is used to calculate the constitutive equilibrium field B/sup e/(H), and hence also the equilibrium magnetization M/sup e/(H), relations for a polycrystalline, anisotropic Type II superconductor with random grain orientation. Mutually-consistent scaling of experimental M versus H isotherms to the calculated M/sup e/(H) relation, for an as-prepared polycrystalline MgB/sub 2/ specimen, allows for the determination of a self-consistent set of values for the anisotropic G-L parameters and for the critical fields H/sub c1/(T), H/sub c/(T), and H/sub c2/(T) for the material. The calculated B/sup e/(H) relation, together with explicit critical current density, J/sub c/(B), trial functions, allows for the determination of flux density profiles [B(r)]/sub H/ and also the nonequilibrium magnetization M(H) behavior, which is compared with the experimental M versus H isotherms. Optimum fits are obtained with a Kramer-like relation of the form: J/sub c/(B,T)/spl prop/H/sub c1//sup n/(T)(1-B/B/sub 0/)/sup 2/B/sup -1/2/, where B/sub 0/(T)/spl ap//spl mu//sub 0/H/sub irr/(T) is the irreversibility field, and n=0.75 and 2.25 for T below and above 28 K, respectively. The general form of this relation suggests that J/sub c/ in polycrystalline MgB/sub 2/ is determined by vortex pinning at grain boundaries.         Investigations of even-order harmonic susceptibilities of MgB/sub 2/ superconductors using critical state approach    A. Gencer, N. Guclu, H. Yilmaz, A. Kilic, I.N. Askerzade, E. Aksu and Y.S. Hascicek Summary: Even-order harmonic susceptibilities /spl chi//sub n/=/spl chi//sub n/'+i/spl chi//sub n/'' (n is even) of MgB/sub 2/ were measured at temperatures between 15 and 45 K with small ac and dc field combinations. The simplified Kim model was employed to account for the main features of the experiments by use of a fitting equation H/sub p/=H/sub /spl alpha//(1-t)/sup /spl beta// for temperature scaling. The experiments are in qualitative agreement with theory.         Thermally activated creep and radiation hardness of MgB/sub 2/ bulk material    G. Ghigo, D. Andreone, D. Botta, A. Chiodoni, R. Gerbaldo, L. Gozzelino, F. Laviano, M. Negro, E. Mezzetti and B. Minetti Summary: In this paper we investigate the effects of ion irradiation on the superconducting properties of polycrystalline high-density MgB/sub 2/. We show that the investigated samples are quite radiation hard, both for what concerns the main reference superconducting parameters and, more important, for what concerns the details of the basic vortex dynamics. This property makes magnesium diboride a good candidate for applications in outspace and in harsh environments. The focus of the analysis is on the flux creep phenomena, studied by ac susceptibility measurements at different frequencies and applied fields. The employed analysis method allows obtaining the activation energy as a function of temperature, field and current density, in their full ranges. As a result, vortex-phase diagrams for the unirradiated and the irradiated samples can be compared and discussed.         Effect of processing defects on stress-strain-I/sub c/ for AgMg sheathed Bi-2212 tapes    A.L. Mbaruku, K.R. Marken Jr., M. Meinesz, H. Miao, P.V.P.S.S. Sastry and J. Schwartz Summary: Manufacture of multifilamentary BSCCO tapes involves rolling of billets to final form. In BSCCO-2212 tapes, one method used to control the microstructure and increase J/sub c/ is intermediate annealing during the deformation process. At times, small bubbles have been observed on the tapes after annealing. Although such bubbles do not remain at the end of fabrication, the question of possible effect on superconducting performance has been studied. The sections that had bubbles after annealing were marked and the fabrication process completed on the tape. After final reaction of the tape, comparisons of stress-strain-I/sub c/ for bubbled and nonbubbled sections were performed. Here we present electrical, mechanical and microstructural studies on bubbled and bubble-free sections of tape. It was found that sections with bubbles had lower I/sub c/ than sections with no bubbles, though both had similar onset of I/sub c/ degradation at /spl sim/0.40%.         A comparison of strain effect on critical current in Bi-2223 superconducting tapes in different bending modes    Hyung-Seop Shin, Su-Yong Choi, Dong-Kyun Ko, Hong-Soo Ha, Dong-Woo Ha and Sang-Soo Oh Summary: The influence of the bending strain on the critical current (I/sub c/) in Ag alloy/Bi-2223 superconducting tapes was investigated at 77 K. The strain effect on I/sub c/ degradation in the different bending modes is discussed in terms of sample geometry and n-value. The I/sub c/ degradation behavior with bending occurring across the tape's width direction called 'hard bending' is discussed in particular, and compared with results under conventional bending tests known as 'easy bending'. It was found that I/sub c/ degraded with increases in the bending strain. In the case of hard bending, greater degradation in I/sub c/ occurred than under easy bending. This might be a result of the difference in the filaments cross-section of the tape and the generation of a new type of damage, such as local buckling, expected during hard bending. The n-value also decreased as the bending strain increased and its behavior was similar to the I/sub c/-bending strain relationship.         Transverse compressive stress effect in Y-Ba-Cu-O coatings on biaxially textured Ni and Ni-W substrates    N. Cheggour, J.W. Ekin, C.C. Clickner, D.T. Verebelyi, C.L.H. Thieme, R. Feenstra, A. Goyal and M. Paranthaman Summary: Electromechanical properties of yttrium-barium-copper-oxide (YBCO) coatings on both pure Ni and Ni-5at.%W alloy rolling-assisted, biaxially-textured substrates (RABiTS) were investigated. The effect of transverse compressive stress on transport critical-current densities (J/sub c/) was measured on samples at 76 K and self magnetic field. Transverse compressive stress can significantly degrade J/sub c/ in YBCO deposited on pure Ni RABiTS unless sufficient frictional support is provided to the sample or the substrate is given a work-hardening treatment. On the other hand, results obtained for YBCO on Ni-5at.%W alloy RABiTS show that the tolerance to transverse stress of these conductors is significantly improved. These electromechanical properties are interpreted with scanning-electron micrographs of the microstructure of the samples after electromechanical testing, as well as stress-strain characteristics measured on RABiTS substrates at 76 K. The tensile yield strength, Young's modulus, and proportional limit of elasticity of candidate RABiTS substrate materials are tabulated and compared.         Strain effects in high temperature superconductors investigated with magneto-optical imaging    D.C. van der Laan, H.J.N. van Eck, Bt. Haken, H.H.Jt. Kate and J. Schwartz Summary: In order to determine the influence of intermediate deformation steps on the mechanical behavior of Bi-based tapes, the effect of longitudinal applied strain is investigated by means of magneto-optical imaging. The strain is applied in a helium flow-cryostat. Cracks appear soon after the critical current in Bi-based tapes is degraded. All filaments form multiple cracks that grow into tape-wide cracks, running from one filament to the next. The crack location is not caused by stress concentrations in the matrix, but by the mechanically weak colony boundaries. Because of the absence of intermediate rolling steps in the production of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ tapes, a different crack structure is observed compared to Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ tapes. The relation between the critical current and the formation of cracks is studied. The degradation in critical current before the critical strain is reached may be caused by microcracks that remain undetected by magneto-optical imaging. The influence of strain on the microstructure of YBa/sub 2/Cu/sub 3/O/sub x/ coated conductors is also investigated with magneto-optical imaging. The formation of cracks is believed to be determined by the nickel substrate and related to the Ni-grain size.         Mechanical properties and their influence to transport property of multifilamentary Bi2223 tape    K. Osamura, M. Sugano and K. Matsumoto Summary: In order to investigate mechano-electromagnetic property, a structure model is proposed based on the rule of mixture. A comparison with experiments made clear that the present tapes show a three stage behavior. The first elastic region (stage I') is very narrow and followed by stage II', where the slope of stress - elongation curve decreased gradually. Then the macroscopic yield and the plastic deformation region (stage III) appeared. A discernible degradation of critical current was observed at stages I' and II'. This degradation is nearly reversible and vanishes when the external tensile load was reduced to zero. At stage III, the critical current decreased abruptly and largely due to generation of macroscopic cracks.         Critical current vs. strain measurements of long length Nb/sub 3/Sn wires up to 1000 A and 17 T using a modified Walters spring    D. Uglietti, B. Seeber, V. Abacherli, M. Thoner and R. Flukiger Summary: We report on a new device for measuring the variation of the critical current as a function of the uniaxial strain in Nb/sub 3/Sn industrial wires. This device offers the possibility of measuring large critical currents (up to 1000 A) on long superconducting wires (about 0.8 m), thus allowing to use the 0.1 /spl mu/V/cm criterion. The WASP is built out of a titanium alloy, enabling strains up to 1.4% at 4.2 K to be applied. In our design, and in contrast to the original Walters spiral, the superconducting wire lies in a machined groove and is only soldered to Cu contacts at both ends. The strain applied on the wire is directly measured by means of strain gauges. With this new device, the variation of I/sub c/(/spl epsiv/) for Nb/sub 3/Sn wires with rectangular cross section as large as 1.56/spl times/1.02 mm/sup 2/(I/sub cmax/=708 A at 13 T) have been successfully measured for the first time.         Novel particulate reinforced tin for tubular Nb/sub 3/Sn multifilamentary superconductors    K.T. Hartwig, G. Chase and J. Belan Summary: A novel technique is under development for the production of a tubular core Nb/sub 3/Sn composite superconductor using an inexpensive, easily fabricated core material. Initial experiments on the tin rich core material have included several different combinations of pure Sn, pure Cu, Sn4 wt%Cu, Sn8 wt%Cu, SiO/sub 2/, and Al/sub 2/O/sub 3/ blended powders, which were hydrostatically compacted, and then consolidated by room temperature angular extrusion. The resulting consolidates are characterized by density, hardness, metallography, and compression testing. Of the mixtures tested, the best core material is a blend of rapidly solidified Sn8 wt%Cu powder plus 6.9 weight percent nanosized SiO/sub 2/ particles. This particulate reinforced tin has a flow stress of (124 MPa)18 ksi and sufficient ductility to be conventionally extruded through a reduction ratio of four. A stronger tin alloy core material should be possible by powder metallurgy processing improvements.         Hysteretic loss vs. filament width in thin YBCO films near the penetration field    M.D. Sumption, E. Lee, C.B. Cobb, P.N. Barnes, T.J. Haugan, J. Tolliver, C.E. Oberly and E.W. Collings Summary: Magnetization vs. applied field measurements (M-H loops) were taken on YBCO thin films with filaments patterned into them. The YBCO was deposited onto LaAlO/sub 3/ substrates using PLD, and the filaments were formed by laser ablation. M-H loops were taken at 4.2 K in fields up to /spl plusmn/9 T using a vibrating sample magnetometer technique, the field applied perpendicular to the film width, d. The losses were seen to be greatly reduced by filament width reductions following the standard expression Q/sub h//H/sub m/ /spl prop/ dJ/sub c//10. The penetration field was also well described by the standard "high field" expression H/sub p/ = (0.4J/sub c/t)ln(d/t + 1), where t is the film thickness. The regimes of applicability of the loss expression were investigated, in particular near H/sub m/ /spl ap/ H/sub p/. A more general form of the loss equation was obtained and compared with the high-field approximation. The result was that although Q/sub h//H/sub m/ still increased in proportion to d, the rate of increase decreased as H/sub m/ approached H/sub p/.         AC loss measurements of twisted and non-twisted BSCCO tapes in transverse magnetic field with various directions    Zhenan Jiang, N. Amemiya, N. Ayai and K. Hayashi Summary: In practical electrical power apparatuses, high T/sub c/ superconducting tapes must carry their transport current in the external magnetic field with various directions. The direction of the transverse magnetic field was varied to study the total AC loss characteristics of a twisted and non-twisted BSCCO tape carrying the AC transport current in the AC magnetic field. In non-twisted tapes, the magnetization loss dominates the total AC loss mostly. In twisted tapes, the magnetization loss dominates the total AC loss at large field angle that is the angle between the magnetic field and the tape wide-face, but its contribution to the total AC loss decreases with decreasing field angle. Therefore, in small field angle regime, the total AC can be reduced by twisting. For the total AC loss reduction in the transverse magnetic field with large field angle, increase in the transverse resistivity is required essentially.         AC losses of multifilamentary Bi-2223/Ag conductors with different geometry and filament arrangement    S. Stavrev, B. Dutoit and P. Lombard Summary: This paper presents results from numerical modeling of nontwisted multifilamentary Bi-2223/Ag conductors with various geometry and filament arrangement. Anisotropic models of J/sub c/(B) and n(B) have been employed in finite element method simulations under different operating conditions - with applied ac transport current, in external parallel and perpendicular ac magnetic field, and with combined current and field of varying orientation. AC losses and current distributions in square and round Bi-2223/Ag wires with different filament arrangement have been calculated and compared to those of a 7-filamentary tape. It is demonstrated that the shape factor of the conductors and the orientation of the local magnetic field with respect to the individual filaments are of primary importance for the ac loss magnitude in different applications. Outlined are the advantages of using conductors with specific filament configuration for a given application.         Theoretical AC susceptibility of superconducting multifilamentary tapes in a perpendicular field    E. Pardo, A. Sanchez and C. Navau Summary: We study theoretically the AC susceptibility of hard type-II superconducting multifilamentary tape when placed in a perpendicular AC magnetic field. We focus on three different arrangements of identical filaments of rectangular cross-section: three filaments stacked in the applied field direction (vertical array), three filaments aligned in the field perpendicular direction (horizontal array), and the case of a 3 /spl times/ 3 filament matrix. Real and imaginary AC susceptibility are calculated within the critical state framework. For the geometries of horizontal array and matrix are studied the cases whether the critical current returns inside each filament or it returns to the other filament placed symmetrically in the horizontal direction.         Accurate microwave technique of surface resistance measurement of large-area HTS films using sapphire quasi-optical resonator    N. Cherpak, A. Barannik, Yu. Filipov, Yu. Prokopenko and S. Vitusevich Summary: We have developed a surface resistance (R/sub s/) measurement technique for large-area high-temperature superconducting (HTS) films using quasioptical dielectric resonators (QDR) with HTS endplates (quasioptical Hakki-Coleman resonators). In this technique, the highest Q modes, namely whispering-gallery modes, in sapphire disk sandwiched between HTS films or between one HTS film and one Cu endplate are excited at K-band frequencies. The authors report on measurement results of surface resistance of 52 mm diameter high-quality YBCO thin films. The measurement results revealed that the technique is feasible for accurate R/sub s/-measurements of large-area thin films. The method is appropriate for standard measurement of R/sub s/ at millimeter wave frequencies by analogy with classic DR-based microwave technique, although QDR-based technique has some fundamental differences.         Complicated shape of the superconductive transition curve revealed by a sensitive OFC-magnetometer    S. Gevorgyan, T. Kiss, H. Shirinyan, A. Movsisyan, V. Gevorgyan, S. Egashira, Yu. Eltsev, T. Matsushita, T. Mito and M. Takeo Summary: Because of pick-up coil's flat design, relatively low operation frequency (/spl sim/ 23 MHz) and high relative resolution (10/sup -6/) a single-layer Open-Flat Coil-based tunnel diode oscillator (OFC-magnetometer) has advantages, compared to other test methods. They become crucial at nondestructive studies with thin flat HTS materials (with small signals), especially near T/sub c/ (at start of the 'Cooper' pairs' formation). Due to these a new 'Para-Magnetic' peculiarity of the normal-to-superconductive (N/S) transition was detected recently in YBaCuO films. It precedes the 'Meissner' ejection and specifies details of an actually complicated shape of the N/S transition curve. We discuss influence of the currents and magnetic field on the PM effect and relationship between the quality of HTS material and amplitude of the effect. Differences between PM effect and externally close 'paramagnetic Meissner' and resistive 'peak' effects are discussed too.         Relationship between the surface resistance and depairing current density of superconductors    S. Ohshima, M. Kusunoki, M. Inadomaru, M. Mukaida, Y. Tanaka and H. Ihara Summary: We have examined the relationship between the surface resistance and the depairing current density of superconductors. From the two-fluid model and the relationship between the depairing current density and the thermodynamic critical field, we can show that the surface resistance is in inverse proportion to the depairing current density. We also experimentally examined the correlation between the surface resistance and the critical current density of YBCO thin films, and found that the surface resistance is in inverse proportion to the critical current density. The results mean that our theoretical analysis is suitable for predicting the correlation between the surface resistance and the critical current density.         Temperature and magnetic field effects on microwave intermodulation in YBCO films    M. Abu Bakar, A.V. Velichko, M.J. Lancaster, X. Xiong and A. Porch Summary: The effects of temperature and dc field on third order microwave intermodulation distortion (IMD) measurements of three YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thin films grown on LaAlO/sub 3/ substrates are discussed. These films were patterned into coplanar resonators with a fundamental resonant frequency of around 5 GHz. The measurements were performed at temperatures of 15 K and 60 K, in zero dc magnetic field and also in an applied dc field of /spl sim/ 10 mT. Good quality films exhibit 3:1 IMD scalings at low temperatures and low powers, decreasing to a 2:1 scaling at higher powers and temperatures. A dc magnetic field applied perpendicularly to good quality samples results in a 2:1 scaling across the whole range of power and temperature, though without any significant change in the IMD output power within the 2:1 scaling regime; this differs for poor quality samples, where the IMD output power can be increased by up to 20 dB by the application of a dc field.         Effects of ion milling on the microwave properties of MgB/sub 2/ films    Sang Young Lee, J.H. Lee, J. Lim, H.N. Lee, S.H. Moon, B. Oh and M.A. Hein Summary: The new superconductor MgB/sub 2/ may prove useful for microwave applications at intermediate temperatures. MgB/sub 2/ films with the thickness of 300 - 400 nm have surface resistance R/sub S/ less than 10 /spl mu//spl Omega/ at a frequency (/spl omega//2/spl pi/) of 8.5 GHz and 7 K, and /spl sim/ 1.5 m/spl Omega/ at 87 GHz and 4.2 K. The critical temperature (T/sub C/) of these films is /spl sim/ 39 K when they are prepared under optimum conditions. The R/sub S/ appears to scale as /spl omega//sup 2/ up to 30 K. After surface ion-milling, a reduction of the T/sub C/ and an enhanced resistivity /spl rho/(T/sub C/) are observed consistently at 8.5 GHz and 87 GHz along with a reduced R/sub S/ at low temperatures. The observed /spl rho/(T/sub C/) - T/sub C/ relation and the uncorrelated behavior between /spl rho/(T/sub C/) and R/sub S/ values measured at low temperatures are well explained in terms of the two-gap model, with the observed /spl rho/(T/sub C/) - T/sub C/ relation attributed to the properties of the large gap, and the R/sub S/ at lower temperatures reflecting the properties of the small gap, with an enhanced gap energy due to increased interband scattering. This study suggests that the interband scattering should be enhanced to improve the low temperature microwave properties of MgB/sub 2/ films and that the ion-milling process must be performed with great care to preserve the high quality of MgB/sub 2/ films.         Microwave surface impedance and nonlinear properties of MgB/sub 2/ films    J.C. Booth, Sang Young Lee, K.T. Leong, J.H. Lee, J. Lim, H.N. Lee, S.H. Moon and B. Oh Summary: We have measured the temperature dependence of the microwave surface impedance and the nonlinear response of high-quality MgB/sub 2/ films on c-cut sapphire at temperatures below 40 K. MgB/sub 2/ films with surface resistance (R/sub s/) as low as 0.02 m/spl Omega/ at 8 K and 8.5 GHz were prepared in an ex-situ process by annealing a boron layer in magnesium-rich environment. The nonlinear properties of the MgB/sub 2/ films were investigated as a function of temperature by means of higher-order harmonic-generation measurements in patterned coplanar waveguide devices. We find that the nonlinear responses of devices fabricated from MgB/sub 2/ films were substantially higher than the nonlinear responses of similar devices fabricated from YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films at the same reduced temperature. We also compared the nonlinear responses of surface ion-milled MgB/sub 2/ films with as-grown films and found that the ion-milled films gave lower nonlinear responses at temperatures below 24 K. The consequences of these measurements for passive microwave device applications of MgB/sub 2/ films are also discussed.         Study of local nonlinear properties using a near-field microwave microscope    Sheng-Chiang Lee and S.M. Anlage Summary: We have developed a near-field microwave microscope to locally apply microwave frequency currents and fields to superconductors, and dielectric substrates, and measure the locally generated 2nd and 3rd harmonic responses. We measure the local nonlinear response of a Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub y/ film grown on an MgO substrate, and observe a large response due to the enhanced current density near the edge. We also study the local nonlinear response of a YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin film grown on a bi-crystal SrTiO/sub 3/ (STO) substrate, and spatially identify the grain boundary through higher harmonic measurements. The spatial resolution is determined by the magnetic loop probe size. A scaling current density J/sub NL/ is extracted to quantify the magnitude of the nonlinearity of the superconductor. Preliminary results on the nonlinear properties of some commonly used substrates, e.g., MgO and STO, have also been obtained.         Anomalies in nonlinear microwave surface impedance of YBCO thin films on MgO: superconductor versus substrate effects    A.V. Velichko, D.W. Huish, M.J. Lancaster and A. Porch Summary: The nonlinear microwave surface impedances Z/sub s/ = R/sub s/ + jX/sub s/ of three epitaxial YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thin films deposited by thermal co-evaporation on MgO substrates have been studied by the coplanar resonator technique at 8 GHz in the temperature T range 12 to 60 K in both zero and finite (/spl sim/ 10 mT) DC magnetic fields. All the films exhibited an anomalous decrease in the surface resistance R/sub s/ as a function of microwave magnetic field H/sub rf/ below 20 K. In one of the films, the application of a DC field of 10 mT has also induced an anomalous decrease in the penetration depth /spl lambda/(H/sub rf/). Analysis of the results suggests that the anomalies may be originating both in the film and in the substrate, and ways to distinguish between the two contributions are proposed. The consequences of the observed phenomena for application of YBCO films in microwave devices are discussed.         In situ sputtering growth and characterization of MgB/sub 2/ films for microwave applications    A. Andreone, A. Cassinese, F. Chiarella, R. Di Capua, E. Di Gennaro, G. Lamura, M.G. Maglione, M. Salluzzo and R. Vaglio Summary: High-quality c-axis oriented MgB/sub 2/ superconducting thin films were grown on MgO and Al/sub 2/O/sub 3/ single crystal substrates by a d.c. planar magnetron sputtering technique. The films were obtained starting by Mg rich Mg-B precursor films, subsequently annealed in situ at 800 /spl deg/C for 10 min in a In sealed Nb box in the presence of saturated Mg vapor. The process is highly reproducible and can be easily scaled to produce large area films. Resistive transition of the 1 /spl mu/m thick resulting films showed a maximum critical temperature T/sub c/ of 35 K and a transition width lower than 0.5 K. The residual resistivity ratio was 1.6 for the best samples. The films were characterized by a variety of structural and electronic techniques including profilometry, XRD, EDS, and STM-AFM analyses, critical current, upper critical field and penetration depth measurements. In view of possible device applications, the microwave response has been studied in detail. The measured dependence of the surface impedance from temperature and r.f. field amplitude at 20 GHz via a dielectric resonator technique is reported and discussed.         Significant reduction of AC losses in Ag sheathed square Bi,Pb(2223) wires with twisted filaments    Yifeng Yang, E.A. Young, C. Beduz, X.D. Su and R. Flukiger Summary: The large aspect ratio of standard Bi,Pb(2223) tapes results in high losses in perpendicular ac field, at least an order of magnitude higher than the loss level acceptable for practical application. Previous investigations, including oxide barriers, resulted in a more than 10 fold increase in matrix resistivity, have resulted only moderate reduction of ac losses. In the present work, we seek to explore an alternative approach of loss reduction by reducing conductor aspect ratios, with unchanged sheath, and without barriers. Square wires, packed with 36 Bi,Pb(2223) filaments were deformed by 2-axis rolling to a final width of 1 mm and then twisted at different pitch lengths. After thermal processing, J/sub c/ values above 10/sup 8/ A/spl middot/m/sup -2/ were obtained. AC loss measurements showed that the overall loss per Ampere-meter is reduced to less than a fifth compared to that of standard tapes in perpendicular field. In addition, it was also found that for a moderate twist pitch of 20 mm, the coupling field of the present wires at 50 Hz was more that 50 mT, while the peak frequency for the coupling current losses was markedly higher than 100 Hz, a remarkable result obtained without barriers.         Field angle dependence of AC losses in stacked Bi-2223 Ag-sheathed tapes    Y. Fukuda, K. Toyota, K. Kajikawa, M. Iwakuma and K. Funaki Summary: In case of applying oxide superconducting tapes to power devices, they are usually stacked face-to-face to form a parallel conductor for the enlargement of current capacity. The accurate estimation of ac losses in the stacked tapes is very important for the basic design of the superconducting devices. In this study, we discuss the angular dependence of the ac losses in the stacked Bi-2223 Ag-sheathed tapes exposed to an external ac magnetic field. First we measure the ac losses in the nontwisted Bi-2223 tapes using a saddle-shaped pickup coil. The experimental results show that the ac losses observed in the transverse magnetic field, whose direction has any angle with respect to the wide face of the tapes, can be well reproduced by a simple summation of the parallel- and perpendicular-field losses. Next we compare the measured ac losses with theoretical ones, which were predicted from the critical current characteristics of a short sample observed in dc magnetic fields.         Temperature and field dependence of the effective matrix resistivity of Bi:2223/Ag composites    E. Lee, M.D. Sumption and E.W. Collings Summary: The effective matrix resistivities of several Bi:2223/Ag superconducting composites were calculated from measurements made with a vibrating sample magnetometer at temperatures ranging from 4.2 K to 70 K with a ramping magnetic field amplitude up to 1.7 T applied perpendicular to the wide side of the sample. The samples were untwisted 19- and 7-filament tapes with width to thickness ratios of about 6 and lengths of 1.3 - 1.5 cm. The measured resistivity values were compared to those derived using Block-Gruneisen theory. As the temperature and/or the magnetic field increased, the effective resistivity increased more rapidly than predicted by the Block-Gruneisen function. This is attributed to an increase in the effective resistivity of the Bi:2223 superconducting filaments due to flux creep.         AC transport losses for Ag-sheathed (Bi,Pb)-2223 tapes prepared by rectangular deformation process    R. Inada, N. Inagaki, Y. Ogawa, A. Oota and P.X. Zhang Summary: We studied the alternating-current (AC) transport self-field losses at 77 K for Ag-sheathed (Bi,Pb)-2223 tapes prepared by a rectangular deformation process. The rectangular multifilamentary wires with different filament arrangements were fabricated by a two-axial roller (TAR) machine, and subsequently they were converted to the multifilamentary tapes by the standard one-axial flat rolling and heat treatments. Although the losses of investigated tapes are mainly dominated by the hysteresis loss of the superconductor in the frequency range between 40 and 200 Hz, the loss behaviors strongly depend on their cross sectional geometry. The effect of filament arrangements on both the magnetic flux penetration and the loss generations in the multifilamentary tapes under AC current transmission is discussed through numerical analysis.         Generation of higher harmonics in voltage on superconducting wire carrying cosine-like AC current    F. Gomory, R. Tebano, J. Souc and S. Farinon Summary: Hard superconductors are known to exhibit nonlinear and hysteretic magnetic properties. Then, the electrical field on the surface of a wire made from such material carrying AC current, will be nonharmonic also in the case when the excitation current is purely cosine-like. We show the harmonic spectra of this signal computed in both numerical and analytical way, following the critical state model with constant j/sub c/. Odd harmonics only are present in the signal. Assuming the cosine-like transport current, the sine components are negligible in wide range of current amplitudes, except the fundamental sine component. The ratio between harmonic components remains constant up to the current amplitudes close to the critical current. Theoretical results are compared with experiments carried out on two samples: multifilamentary tape from HTS Bi-2223 in metallic matrix, and sintered tubes of Bi-2223. Measured content of higher harmonics laid below theoretical results for both the samples, indicating that the simple model with constant j/sub c/ does not sufficiently describe the flux pinning in these materials.         Hysteresis losses in YBCO coated conductors on textured metallic substrates    M. Majoros, R.I. Tomov, B.A. Glowacki, A.M. Campbell and C.E. Oberly Summary: Hysteresis losses of YBCO coated conductors on two different textured metallic substrates - (NiFe and NiCrW)- were measured. The measurements were performed in a dc SQUID magnetometer at 5 K in applied magnetic fields up to 6 T. An YBCO layer of the sample on NiCrW substrate was cut to form 2 filaments and measured again in a perpendicular magnetic field as well as in a field at an angle of 45/spl deg/ with respect to the tape face. In a perpendicular magnetic field the hysteresis losses of the 2 filaments were a factor of about 0.6 lower than the losses of the original single filament. The influence on the magnetization of dividing a monocore tape into 2 and 4 filaments was numerically modeled using the critical state model. For full penetration and a perpendicular magnetic field the magnetization decreases proportionally with increasing number of filaments. Hysteresis losses in metallic substrates were substantially lower than the total losses of the composite tapes.         Numerical evaluation of AC losses in HTS wires with 2D FEM formulated by self magnetic field    K. Kajikawa, T. Hayashi, R. Yoshida, M. Iwakuma and K. Funaki Summary: The ac losses of high critical-temperature superconducting (HTS) wires are numerically calculated by means of a finite element method (FEM), which is formulated with a self magnetic field due to an induced current as unknown. The numerical model is straight HTS wires carrying an alternating transport current in an external ac magnetic field perpendicular to the wire axis. In this situation, the electromagnetic field around the wires is given by two-dimensional (2D) Maxwell's equations. It is also assumed that the transport property is represented by either the critical state model or the power-law model, in which the electric field is proportional to the power of the current density. The obtained losses are compared with conventional theoretical curves in several simple geometries.         3D modeling of coupling between superconducting filaments via resistive matrix in AC magnetic field    M. Costa, E. Martinez, C. Beduz, Y. Yang, F. Grilli, B. Dutoit, E. Vinot and P. Tixador Summary: The ac loss of superconducting composite depends strongly on coupling between superconducting filaments via the resistive matrix. The established technique for loss reduction using twisted filaments relies on the decoupling of the filaments below a critical coupling field Bc, which increases with the reduction of the twist pitch and the matrix conductivity. Although the concept of Bc may be clearly demonstrated using two infinite slabs of finite length, further details on its correlation with the filament/conductor geometry are not yet available. The main obstacle is due to the fact that any accurate analysis of such a problem must be carried out in 3d. In this paper, we describe the initial results from 3d modeling using Cedrat's Flux3D, for which a superconductor module for handling power-law E-J characteristics was developed. Using a simple model of two rectangular superconductors connected through a normal metal, we demonstrate the feasibility for quantitative modeling of their coupling behavior over a wide range of field sweep rates for different conductor geometries. Typical examples were given for cases not addressed by the existing approximate theory, as well as for the evolution of field profile for varying field sweep rate.         Microwave and modulated optical reflectance studies of YBCO thin films    D.W. Huish, A.V. Velichko, M.J. Lancaster, J.S. Abell, Xuming Xiong, D.P. Almond, D. Hyland, A. Perry and A. Porch Summary: Planar HTS microwave devices require high quality, homogeneous samples. In this paper, sensitive measurements of the microwave surface impedance of YBCO thin films using coplanar resonators are collated with modulated optical reflectance (MOR) measurements. MOR provides a powerful noncontact, nondestructive and high resolution means of probing local variations in the quality of thin films at room temperature, and consequently has great potential for diagnostic testing of HTS films prior to microwave device patterning. Microwave and MOR inter-comparisons of four YBCO films patterned into 5.2 and 8 GHz coplanar resonators are presented. Superior global microwave response in the superconducting state, such as low surface impedance and low levels of nonlinearity at enhanced powers, correlate with the magnitude and spatial homogeneity of the room temperature MOR signals. The presence of defects in films is investigated using both techniques. Both large scale single defects and film inhomogeneity can be detected using MOR; however, the spatial resolution of the technique is not sufficient to detect single weak links on a sub-micron scale, whose presence can result in severely degraded microwave resonator performance.         Correlation between the XPS peak shapes of Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/ and film quality    P.N. Barnes, S.M. Mukhopadhyay, T.J. Haugan, S. Krishnaswami, J.C. Tolliver and I. Maartense Summary: X-ray photoelectron spectroscopy (XPS) depth profiling was used to investigate the compositional and chemical profile of a typical YBCO coated conductor architecture. Results of the process revealed that the Y(3d) photoelectronic peak shape in these films is very different from bulk YBCO. To investigate this, several samples of Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/ thin films were intentionally created of varying quality. The films were deposited on LaAlO/sub 3/ by pulsed laser deposition with J/sub c/ values ranging from poorly conducting up to several MA/cm/sup 2/. Initial results indicated a potential correlation between the Y(3d) XPS peak shape (full-width-half-maximum) of the YBCO and the film quality. A potential correlation may also exist with the Cu(2p)/Ba(3d) ratio indicating an interrelationship to the FWHM of the Y(3d) peak. Film quality was determined by current transport, resistive T/sub c/, and AC magnetic susceptibility measurements.         Direct method of measuring ac losses in superconducting tapes, simultaneously subjected to ac current and ac magnetic field    Y. Bugoslavsky, M. Polichetti and A.D. Caplin Summary: A novel technique for measuring ac losses in short lengths of high-temperature-superconductor tapes is presented. The principle of operation is based on the direct detection of the heating produced by the losses. In the presented system a tape can be subjected to current up to 40 A rms and ac magnetic field up to 600 mT rms, with an arbitrary phase between them; the measurements are made at 77 K. The noise floor is of the order of 1 /spl mu/W/cm. A number of test experiments are presented, which prove the validity of the technique.         Measurements of magnetic fields and levitation forces of bulk superconductors    N. Yamachi, T. Nishikawa, K. Sawa and M. Murakami Summary: We have measured the magnetic field and the levitation force of a bulk Y-Ba-Cu-O superconductor in varying the external field with a Bi-Sr-Ca-Cu-O superconducting magnet. The height dependence of the levitation force could well be explained in terms of the field gradient in the sample and the radial component of the external magnetic field. The field gradient also induces the trapped field and decreases the levitation force. The experimental data showed a deviation from the theoretical value when the levitation process was repeated.         Measurement of AC current distributions in HTS tapes exposed to an external AC magnetic field by a compensated pickup coil array    S. Kawabata and K. Matsushita Summary: A new system was developed for measuring AC current distributions in high T/sub c/ superconducting tapes under an external AC magnetic field. In our measurement the current distributions are indirectly found from the results of the self-field distributions measured by an array of pickup coils located around the tape. For improved measurement accuracy under the external magnetic field, a compensation coil was used to cancel the component of the external magnetic field from the signal of pickup coil. In order to confirm the validity of this system, measurement of current distributions in a test conductor composed of insulated copper wires was carried out under an external AC magnetic field. Using this system, we measured the current distributions in multifilamentary Ag alloy sheathed Bi-2223 tape as a function of the angle of the external AC magnetic field at 77 K. Further, we investigated the characteristics of the current distributions for the case of a simultaneous application of AC transport current and transverse AC magnetic field. On the basis of the obtained results the practicality of our measurement system is discussed.         Modulation of the resonance frequency of superconducting microwave resonators    Shinho Cho and Chang-Sik Son Summary: The microwave transmission characteristics of superconducting YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) meander line resonators have been investigated as a function of temperature, optical pulse energy, and input power. The measurements are performed in a temperature range from 20 K to 80 K. The optical excitation consists of a 70 psec laser pulse train at 532 nm from an actively mode-locked Nd:YAG laser. The optical pulse energy is mapped out from zero to the critical optical pulse energy at which the resonance can no longer be distinguished. The measured resonance frequency shows a squared dependence on both the temperature and the optical pulse energy. As for the dependence on input power, the resonant frequency linearly decreases at a rate of 148 kHz/dBm at 50 K.         Poynting vector method: AC loss measurement of long HTS tapes or wires wound into a solenoidal-coil    F. Sumiyoshi, H. Kasahara, A. Kawagoe, K. Kubota and S. Akita Summary: A new electrical system was developed for measuring ac losses of long HTS tapes or wires wound into a solenoidal-coil. This coil-loss measuring-system is an extension of our original ac-loss measuring system that is applicable to short, straight HTS tapes under various external conditions of transport currents and transverse magnetic fields, and is useful for fundamental studies of various windings of practical multi-layered coils. In this new system, the Poynting vectors at the outer and the inner surfaces of the coil were measured to get ac loss values by using two movable sets consisting of both a potential lead pair and a pick-up coil on each surface of the coil. The moving direction is the coil axis and its distance is one pitch of coil windings. The value of ac losses can be obtained by summation of the Poynting vector at many positions during the movement. The applicability of this system was confirmed by ac loss measurements on a solenoidal-coil wound loosely with Ag-sheathed, multifilamentary Bi-2223 tapes.         Characterization of superconducting rings using an in-field Hall probe magnetic mapping system    X. Granados, S. Sena, E. Bartolome, A. Palau, T. Puig, X. Obradors, M. Carrera, J. Amoros and H. Claus Summary: A Hall probe magnetic imaging system that works in magnetic fields in the range -1 T to 1 T has been implemented, and it has been used to characterize the superconducting behavior of single domain melt textured YBa/sub 2/Cu/sub 3/O/sub 7/ rings. We show that in addition to the analysis of the evolution of the local magnetic field distribution when the external magnetic field is cycled, the hysteretic behavior of the magnetic moment can also be investigated after integration of the local magnetic field. The critical current density has been determined through the critical state model and it has been compared to that calculated by inversion of the Biot-Savart law. A remarkable agreement is achieved with both methods.         Accuracy of numerical analysis for Hall sensor magnetometer measurements    M. Masti, J. Lehtonen, R. Mikkonen and L. Rostila Summary: The Hall sensor magnetometer is a widely used tool to characterize the homogeneity of high temperature superconducting tapes. However, it is well known that the current density distribution inside the sample, J, cannot be uniquely solved from the measured magnetic flux density, B. By discretising the Biot-Savart law the problem can be reduced to a solvable set of linear equations. Inaccurate assumptions about the sample geometry, noise in the measured data, and numerical errors can cause considerable error in the computed J. In this paper, a statistical approach to compare different inversion methods is presented. Example runs are carried out in order to find optimal locations for the measurement points. The results show that the relative error can be reduced by several orders of magnitude with the proper choice of measurement points, but the problem always remains ill-conditioned.         Backscattered terahertz radiation imaging system to visualize supercurrent distributions    T. Kiwa, Y. Kamata, M. Misra, H. Murakami and M. Tonouchi Summary: A new type of terahertz (THz) radiation imaging has been proposed and demonstrated. The supercurrent distributions were visualized by detecting the backscattered THz radiation from optically excited high-temperature superconductors. The supercurrent distributions were clearly observed in 100and 500-nm-thick YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films in the remanent state. Our system has performance similar to the system with transmission configuration.         Soft X-ray spectra by wavelength dispersive spectrometry as a micron scale tool to determine copper valence    K. Muller, J.K. Meen and D. Elthon Summary: Copper in liquids in many cuprate systems occurs in both univalent and divalent states. The determination of Cu valence in experimental charges is necessary for full understanding of phase relations of superconducting cuprates. Ideally, the valence state should be determined essentially simultaneously with determination of elemental contents and crystal structure so that specific phases can be fully characterized. No currently available technique can do that so we have attempted to develop a technique based on the L x-ray spectrum of Cu that can be used by conventional electron microbeam instrumentation. The Cu L spectrum has distinct differences between CuO and Cu/sub 2/O that may be quantified by the ratio of peak heights in the spectra. The standard deviation of this ratio is very small compared with the difference in values. The spectra of divalent Cu in the oxide and in an alkaline earth cuprate are similar but not identical, reflecting the differences in the Cu-O polyhedra in these species. Change in the alkaline earth in the cuprate does not influence the L spectrum. The technique is potentially useful in determining valence state of Cu in more complex cuprate systems but requires use of standards in which the Cu-O polyhedra are similar to those in the unknowns.         Prediction of E-J characteristics in Bi-2223/Ag tapes at low temperature and high magnetic field    H. Okamoto, T. Kiss, S. Nishimura, M. Inoue, K. Imamura, M. Takeo and M. Kanazawa Summary: Using limited data measurements, the electric field vs. current density (E-J) characteristics of practical Bi-2223/Ag tapes were predicted in a low-temperature and high-magnetic field. This method is based on findings shown in our papers, which describe E-J characteristics according to the percolation model, as a function of temperature, magnetic field and angle of the magnetic field. This method can also estimate critical current density and n-value, given any electric field criterion.         Numerical simulation on contactless measurement of critical current density in HTS    K. Hasegawa, M. Natori, T. Yokono and A. Kamitani Summary: According to the experiments by Claassen et al., (1991), the odd harmonics of the magnetic field are excited with an increase in the amplitude of the applied ac magnetic field. Especially, the third harmonic is suddenly excited after the amplitude exceeds a certain limit. This onset of the third harmonics indicates that the critical current density is following in all over the HTS. On the basis of the experimental results, Claassen developed the contactless method for measuring the critical current density. The purpose of this study is to reproduce Claassen's results by means of the numerical simulation. To this end, the governing equation of the shielding current density has been formulated and the numerical code for solving the initial-boundary-value problem of the equation has been developed. After the shielding current density is evaluated by using the code, the magnetic field generated by the shielding current density is calculated as a function of time. Spectral analysis of the field is performed. The results of computations show that the flux-flow region covers the whole volume of the HTS above a certain limit of the amplitude of the applied magnetic field.         Properties of Bi-2223 thick films on a MgO substrate prepared by a coating method    M. Ichikawa, H. Kado, M. Shibuya, M. Kojima, M. Kawahara and T. Matsumura Summary: Fault current limiters for electric power systems have been researched. We have been studying on a inductive type superconducting fault current limiter. The limiter has superconducting cylinder as active element. It is necessary for practical use of the superconducting fault current limiter that superconductor has high critical current density (Jc). So as to get high Jc, we tried Bi-2223 as a material for the superconductor, and prepared Bi-2223 thick film. Raw paste of Bi system was coated on a polycrystalline MgO substrate and then was sintered in the air with intermediate pressing by a cold-isostatic-pressing (CIP) technique. The sintered Bi-2223 thick film had good crystal orientation. The Jc of the 500 /spl mu/m thick film was over 6000 A/cm/sup 2/ at 77 K.         Enhancement of critical current density and flux pinning in Bi-2212 thick films due to MgO addition    Baorong Ni, M. Kiuchi and E.S. Otabe Summary: In order to substitute cheaper sheath materials for Ag, Bi-2212 superconducting thick films grown on oxidized Ni substrates were prepared by using a normal partial melt process. 0-5 vol% of fine MgO particles were doped in Bi-2212 phase during the fabrication for the purpose of enhancement of the critical current density (J/sub c/) in Bi-2212. The samples were analyzed with the assistances of X-ray diffractometer (XRD) and electron probe microanalyzer (EPMA). The critical temperature and J/sub c/ were measured by using the conventional resistive method (4-probe method). An apparent improvement in J/sub c/ characteristic was observed in the samples with fine MgO particles doped. The J/sub c/ value in the 5 vol% MgO doped sample reached to the level comparable with that in other Ag-sheathed samples. Furthermore, the irreversibility field was confirmed to be largely enhanced by the addition of MgO particles. The pin parameters derived from the scaling behavior of pinning force density turned out to be similar to those predicted in the case of normal precipitate flux pinning, indicating that MgO particles in Bi-2212 act as effective pinning centers.         Effects of small magnetic fields on the critical current of thin films    W.A.C. Passos, P.N. Lisboa-Filho, W.N. Kang, Eun-Mi Choi, Hyeong-Jin Kim, Sung-Ik Lee and W.A. Ortiz Summary: Magnetic fields applied perpendicularly to superconducting thin films may produce dendritic patterns, where penetrated and Meissner regions coexist, as observed in Nb, YBCO and MgB/sub 2/. Due to large demagnetizing factors in the perpendicular geometry, small fields may be enough to drive portions of the sample into the mixed state. Lack of symmetry and local defects might then permeate the dendritic mode. This mode, in turn, can be detected by AC-susceptibility measurements, since penetrated fingers act as intergranular material, which reveals itself in a characteristic manner. Films of a few hundred nanometers thick and millimeter lateral sizes, develop dendrites even when submitted to Earth's field, what drastically limits the critical current, J/sub c/. This contribution studies how this field-induced granularity is further affected by the action of excitation AC-fields of small magnitudes and audio-frequencies.         Comparing powder magnetization and transport critical current of Bi,Pb(2223) tapes    M. Dhalle, D.C. van der Laan, H.J.N. van Eck, L. Vargas, B. ten Haken, H.H.J. Ten Kate, U.P. Trociewitz and J. Schwartz Summary: The magnetic field dependence of the critical current in (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10+x/ tapes is compared with the magnetization response of isolated grains extracted from the tapes. Special attention is paid to the low-field behavior. The goal of the experiment is to test the widely-used hypothesis that current paths in these tapes contain both weak- and strong- linked branches, which in low field act in parallel. The data agree with this hypothesis; at temperatures above 50 K the powder magnetization drops off exponentially from the self-field to the irreversibility field, while the transport and magnetization currents in the intact tapes show an extra low-field component. Below 50 K the powder behavior becomes less straightforward, but the parallel-path picture in the tapes still holds.         A fast method of characterizing HTSC bulk material    M. Zeisberger, T. Habisreuther, D. Litzkendorf, O. Surzhenko, R. Muller and W. Gawalek Summary: HTSC bulk material which has been developed during the last ten years is now prepared in increasing quantities and used in demonstrators or prototypes of several applications, e.g., flywheels and motors. The quality control of large amounts of samples requires a method which is fast and provides essential information about the sample quality. In particular, the critical current density and its inhomogeneity should be determined. In this contribution we report about a trapped field measurement technique using pulsed field magnetization and field detection by a Hall-array. With this arrangement the required time of measurement is in the order of a few minutes per sample. The software which controls the devices contains also an analyzing procedure for the calculation of an effective critical current density as well as parameters describing the homogeneity of the samples.         Theoretical investigation on 3rd harmonic voltage in inductive measurements of critical current density in superconducting films    Y. Mawatari, H. Yamasaki and Y. Nakagawa Summary: We have theoretically investigated third-harmonic voltage detected in a widely-used inductive measurement of critical current density J/sub c/ in superconducting films. In the inductive measurement, an ac drive current I/sub 0/ cos /spl omega/t flows in a small coil close to the surface of a superconducting film, and third-harmonic voltage V/sub 3/ cos(3/spl omega/t + /spl theta//sub 3/) induced in the coil is detected. The relationships among the ac drive current I/sub 0/, the amplitude V/sub 3/, and the phase /spl theta//sub 3/ of the third-harmonic voltage are derived on the bases of the critical state model. When the drive current is smaller than a threshold value I/sub c0/, the third-harmonic voltage is near zero, V/sub 3/ /spl ap/ 0 for I/sub 0/ < I/sub c0/. For I/sub 0/ > I/sub c0/, on the other hand, the third-harmonic voltage is expressed as V/sub 3/ exp(-i/spl theta//sub 3/) = /spl omega/I/sub c0/ G/sub 3/(I/sub 0//I/sub c0/), where G/sub 3/(/spl gamma/) is a scaling function determined by the configuration of the coil. The predicted scaling law of V/sub 3//I/sub c0/ and /spl theta//sub 3/ as functions of I/sub 0//I/sub c0/ is clearly observed in an YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// film.         Mechanisms of limitation and nature of field dependence of critical current in HTS epitaxial YBaCuO films    V.M. Pan, E.A. Pashitskii, S.M. Ryabchenko, V.A. Komashko, A.V. Pan, S.X. Dou, A.V. Semenov, C.G. Tretiatchenko and Yu.V. Fedotov Summary: Magnetic field and temperature dependencies of the critical current density, J/sub c/(H/spl par/c, T) were measured by SQUID-magnetometry, ac magnetic susceptibility, and dc transport current techniques in the single-crystalline epitaxially-grown by off-axis dc magnetron sputtering YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) films with J/sub c/(H/spl par/c, 77 K) /spl ges/ 2 /spl middot/ 10/sup 6/ A/cm/sup 2/. The mechanism of vortex depinning from growth-induced linear defects, i.e., out-of-plane edge dislocations in low-angle tilt domain boundaries, is shown to describe quantitatively measured J/sub c/(H/spl par/c, T). The developed model takes into account a statistical distribution of the dislocation domain boundaries ordered in a network as well as the interdislocation spacing within boundaries. Actual structural features of YBCO film known from HREM data turn out to be extracted from J/sub c/(H/spl par/c, T)-curves by a fitting procedure within the proposed model.         Nondestructive, inductive measurement of critical current densities of superconducting films in magnetic fields    H. Yamasaki, Y. Mawatari, Y. Nakagawa and H. Yamada Summary: An inductive method to detect a third harmonic voltage V/sub 3/ is widely used to measure critical current densities J/sub c/ of large-area superconducting films. Very recently Mawatari et al. have elucidated the generation mechanism of V/sub 3/ and derived the relationship between the coil ac current and V/sub 3/. We have supported this theory by experiment, and then used this method to measure J/sub c/ of YBCO films in dc magnetic fields at various temperatures (0-5 T, 66-77.3 K). The temperature and the field dependence of J/sub c/ was in good agreement with those measured by dc magnetization and transport measurement. It is demonstrated that this method can also be applicable to measure J/sub c/ in applied dc magnetic fields.         Magneto-optical studies of the critical states in c-axis oriented MgB/sub 2/ thin film and bulk MgB/sub 2//Mg nano-composites    Zuxin Ye, Qiang Li, G.D. Gu, J.J. Tu, W.N. Kang, Eun-Mi Choi, Hyeong-Jin Kim and Sung-Ik Lee Summary: We present magneto optical (MO) studies of the critical states in a c-axis oriented MgB/sub 2/ thin film with a critical current density (J/sub c/) of 6 MA/cm/sup 2/ at 5 K, and bulk MgB/sub 2//Mg nano-composites with J/sub c/ over 1 MA/cm/sup 2/ at 5 K. The magnetic flux penetration and trapping in the thin film are found remarkably different from that in the bulk samples. A tree-like magnetic flux pattern was observed entering the superconducting film, as well as various complex dendritic flux jumps due to the thermo-magnetic instability. These behaviors indicate the collapse of the critical state of a type II superconductor at local level. In contrast, a regular flux penetration into the critical state was observed in the bulk nano-composites, which indicates that the addition of pure Mg helps to stabilize the critical state.         Nanodots-induced pinning centers in thin films: effects on critical current density, activation energy and flux jump rate    A. Crisan, P. Badica, S. Fujiwara, Jia-Cai Nie, A. Sundaresan, A. Iyo and Y. Tanaka Summary: By very short time rf sputtering in certain deposition conditions we have grown three-dimensional Ag nanodots on the substrate prior to the growth of Tl-based superconducting films. These nanodots create pinning centers, leading to an increase in the critical current density about 10 times. From the frequency dependence of the critical current density we estimated also the activation energy for the flux jumps, which resulted to be several times higher. The rate of the thermally-activated flux jumps decreases several orders of magnitude. We suggest that our method can be used for the reduction of thermal noise in high-T/sub c/ dc SQUID's.         THz radiation properties of Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8+/spl delta// thin films excited by femtosecond laser pulses    Y. Tominari, T. Kiwa, H. Murakami, M. Tonouchi, H. Schneidewind, H. Wald and P. Seidel Summary: Previously, we found the resonant THz wave radiation from c-axis oriented underdoped Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8+/spl delta// (Tl-2212) thin films by femtosecond laser pulse illumination under magnetic field. The properties of the resonant THz wave were well explained by the Josephson plasma resonance phenomenon. In the present study, the THz radiation properties were investigated for an overdoped Tl-2212 thin films. The amplitudes of THz waveform radiated under a bias current condition is much smaller than those of previous sample, while any trace of resonant THz signals could not be observed under magnetic field. These experimental results indicate the possibility that the initial THz wave radiated by ultrafast modulation in eddy-current around the vortices has an important role to excite the collective mode oscillation.         Nonlinear electrodynamic response of superconducting materials near transition    Zhi Qi, Hengyi Xu, Wei Wang, Daole Yin, Furen Wang and Chuanyi Li Summary: One of the important problems of applied superconductivity is to understand, well describe and control the electromagnetic response due to flux motion. We show that the transport properties of type-II superconductors can be well described by a nonlinear response function. In connection with the superconducting- normal state (S-N) resistive transition we find further a model R(T, H) equation which fairly agrees with the experimental data of MgB/sub 2/ as well as the untwined high critical temperature YBCO crystals. Instead of the constant R in the Ohm's law of normal metals, combining with Maxwell equations, this nonlinear resistance function over wide range of temperature, field and current provides a useful basis for engineering design and analysis.         Transport and noise properties of ramp-edge junction    D.H. Kim, C.W. Lee, T.W. Lee, J.S. Hwang, T.S. Hahn, G.Y. Sung, S.H. Kim and J.H. Kim Summary: We measured transport and noise properties of YBa/sub 2/Cu/sub 3/O/sub x/ ramp-edge junctions fabricated with interface-engineered barrier. The current-voltage characteristics show a typical resistively-shunted junction like behavior. Voltage noise measurement revealed that the main source of the 1/f noise is the critical current and resistance fluctuations. The analysis of the noise data showed that the critical current fluctuations increase with temperature, whereas the resistance fluctuations are almost constant, and both fluctuations are anti-phase correlated. The magnitudes and the temperature dependence of both fluctuations are found to be sensitive to the junction resistance, which in turn is controllable by the process parameters during the barrier growth.         Calculation of the temperature dependent AC susceptibility of superconducting disks    M.J. Qin, G. Li, H.K. Liu and S.X. Dou Summary: The temperature dependent complex AC susceptibilities of high temperature superconducting disks in perpendicular AC magnetic fields (in absence of DC magnetic field) have been calculated from first principles. The temperature dependent AC susceptibilities for different AC field amplitudes, AC field frequencies, reduced pinning potential, and sample thickness have been derived, which demonstrate many features different from what has been observed in the configuration of infinite long slab or cylinder under a parallel-applied AC field. The results of such a realistic configuration of finite-thickness samples in perpendicular fields can be compared directly to the experimental results.         Behavior of bulk melt-textured YBCO single domains subjected to crossed magnetic fields    P. Vanderbemden, S. Dorbolo, N. Hari-Babu, A. Ntatsis, D.A. Cardwell and A.M. Campbell Summary: We have experimentally investigated the crossed magnetic field effects on bulk melt-processed YBCO single domains. The samples were first permanently magnetized along their c-axis and then subjected to several cycles of a transverse magnetic field parallel to the ab planes. The magnetic properties along the c and ab directions were simultaneously measured using a couple of orthogonal pick-up coils as well as a Hall probe placed against the sample surface. The effects of both sweep amplitude and polarity were investigated. Field sweeps of alternate polarities are shown to affect the decay of the c-axis magnetization much more strongly than field sweeps of unique polarity do. However, the c-axis magnetization does not show any saturation even after a large number of field sweeps. Next, a micro-Hall probe scanning system was used to measure the distribution of magnetic induction over the top surface of the single domain subjected to the same combination of magnetic fields. The results are shown to be consistent with those determined with the sensing coils and bring out the role played by geometric effects.         Transient response of single-domain Y-Ba-Cu-O rings to pulsed magnetic fields    T.R. Askew, J.M. Weber, Y.S. Cha, H. Claus and B.W. Veal Summary: Shielding current limits and magnetic diffusion characteristics have been measured at 77 K for a set of YBCO single-domain rings. These were fabricated from melt-textured cylindrical YBCO monoliths that were densified to nearly 100%, and then oriented from a single seed. The rings were surrounded by a drive coil that can, under pulse conditions, achieve applied magnetic fields in excess of 1 T and induce currents in excess of 50 kA. Simultaneous magnetic characterization with a Rogowski coil and Hall probe was used to determine the induced current in the sample and the magnetic field in the center of the sample. Magnetic fields trapped in the samples were mapped with a scanning Hall probe. When compared with similar measurements on multidomain c-axis-oriented YBCO rings, the flux penetration is faster and more uniform around the circumference of the ring. The observed critical current density, /spl ap/ 15,000 A/cm/sup 2/ at 77 K, is suitable for application in penetration-type fault current limiters. Separate measurements of the trapped magnetic field and critical current density in the rings are compared with results obtained by analysis of magnetic diffusion characteristics.         The modulation of the peak effect in melt-processed (Sm-Eu)123 superconductors with compositional fluctuations    A. Hu, H. Zhou, D.X. Huang, N. Chikumoto, N. Sakai and M. Murakami Summary: The peak effect in magnetization loops of melt-processed (Sm/sub x/Eu/sub 1-x/)Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// superconductors is manipulated by varying the Sm/Eu ratio in the initial composition. In all the samples the peak field B/sub p/(T), at which the magnetization moment reaches the maximum, was linearly temperature dependent. The fitting to such a relationship unveils a slightly lower critical temperature T/sub cp/ than the bulk T/sub c/ at zero field. A kink appears in the reversible magnetization moment of the field dependence of superconducting transition. This kink temperature T/sub ck/(B) is also a linear function of applied field. Transmission electron microscopy (TEM) observation confirms the presence of nano-scale regular compositional modulation arising from local RE-Ba substitution, which is weakened with increasing Eu concentration. The peak effect is thus attributed to the scattering of local T/sub c/ due to compositional fluctuation.         Characteristic properties of doped Bi2212 single crystals studied by magneto optical measurement    T. Okabe, J. Shimoyama, M. Shigemori, S. Horii and K. Kishio Summary: Local J/sub c/ distribution under H /spl par/ c was carefully investigated for lightly Pb-doped Bi2212 single crystals having uniform microstructure in order to clarify essential effect of Pb-doping on intra-grain J/sub c/ properties. An abrupt change of internal field gradient was observed at a constant field, H/sup */, for each Bi(Pb)2212 single crystal below 25 K. J/sub c/ is apparently higher above H/sup */. The H/sup */ was observed at several hundred Oe which was much lower than the second peak field, H/sub pk/, in the magnetization hysteresis loops. This suggested that dimensionality of vortex changed at H/sup */ from 3D to quasi-2D state with an increase of internal magnetic field, possibly due to an inhomogeneous distribution of lead ions in the crystal. Higher J/sub c/ above H/sup */ and temperature dependent H/sub pk/ indicated generation of field-induced pinning sites in the present system. Doping effects of cobalt for heavily Pb-doped Bi2212 single crystals on the flux pinning properties were also studied. In-plane J/sub c/ was found to become isotropic with increasing the Co-doping level.         Dynamical behavior of Josephson vortices in Bi-2212    K. Hirata, S. Ooi, E.H. Sadki and T. Mochiku Summary: We have found periodic oscillations in the flux flow resistance of Josephson vortices along the c-axis of Bi-2212 single crystals. The resistance oscillates periodically with increasing parallel magnetic fields above about 6 kOe, independent of the magnitude of the field and temperature. The constant period of the oscillations and the dynamical behaviors of Josephson vortices suggest vortex states and a new application to the precise magnetic field sensors in Tesla order.         Frequency dependence of the depinning and irreversibility lines in BSCCO    H. Bocuk, L. Dorosinskii and U. Topal Summary: Penetration of AC magnetic field in Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub /spl delta// single crystals was studied using the magnetooptic technique. It was found that the apparent depinning line shifts toward higher (H, T) values with increasing field frequency. At higher frequencies irreversibility in magnetization is controlled by pinning but not by the geometrical or surface barrier. Comparison with the melting line has shown that the depinning line lies completely in the vortex liquid region. Moreover, at least in low DC fields, the vortex liquid does not become unpinned up to the critical temperature of superconductor.         Magnetic hysteresis and relaxation in Bi2212 single crystals doped with Fe and Pb    K.K. Uprety, J. Horvat, X.L. Wang, G.D. Gu, M. Ionescu, H.K. Liu, S.X. Dou and E.H. Brandt Summary: Magnetic hysteresis and magnetic relaxation measurements have been performed to study vortex pinning behaviors for pure, Fe doped and heavily Pb doped Bi2212 single crystals. Unlike pure and Fe doped Bi2212 crystals, heavily Pb doped crystal showed strong vortex pinning behavior. We interpret the strong pinning in heavily Pb doped Bi2212 single crystals as arising from the improved Josephson coupling in Bi2212 single crystal after heavy Pb doping. In heavily Pb doped single Bi2212 crystals, H/sub dis/(T) was observed to decrease with increasing T. Here, H/sub dis/(T) is an order-disorder field that separates a weakly elastically disordered vortex lattice from a plastically disordered vortex solid. However, in pure and Fe doped Bi2212 single crystals, H/sub dis/(T) was observed to be temperature independent. We also report a significant shift of T/sub CR/, a crossover temperature separating two pinning regimes, toward higher temperatures with heavy Pb doping of Bi2212 single crystals. On the other hand T/sub CR/ did not shift with Fe doping of Bi2212 single crystals. It is argued that the temperature dependence of H/sub dis/(T) and the shift of T/sub CR/ in heavily Pb doped Bi2212 crystals was related to the enhanced c-axis conductivity caused by the Pb situated between the CuO/sub 2/ layers and imposing a 3D characteristic on the vortex lattice.         Author Index (2002 - Part 3)    No author information available Summary: Not available

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