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1998 Part 2     Front Cover (1998 - Part 2)    No author information available Summary: Not available         Table of Contents (1998 - Part 2)    No author information available Summary: Not available         Microstructures and flux pinning properties in Nb/sub 3/Al tapes by ohmic-heating method    N. Harada, H. Taira, K. Osaki, N. Tada, G. Iwaki and K. Watanabe Summary: Two kinds of Nb/sub 3/Al superconducting tapes with monocores in Nb sheaths have been fabricated from either Nb/Nb/sub 2/Al(sigma-phase) powders or Nb/Al powders. Tape samples 3 mm wide, 0.3 mm thick, and 40-50 mm long are ohmically-heated at maximum temperatures which range from 1650 to 2000/spl deg/C in vacuum, to obtain the stoichiometric composition of the A15 phase. Critical currents up to 23 T were measured by a four probe method. Microstructures were studied using an X-ray diffractometer, TEM, and EDX. The Nb/sigma powder sample showed a maximum T/sub c/ at an ohmically-heated temperature 200/spl deg/C lower than the Nb/Al powder sample. Production of A15 is influenced by the differences in diffusion length related to different starting materials. Nb/sub 3/Al grain sizes were 1-2 /spl mu/m in both the Nb/Al sample and the Nb/sigma sample. Also, /spl sigma/-phase was observed only in Nb/Al sample. The pinning force densities in the Nb/Al sample and the Nb/sigma sample showed a large peak at high magnetic field (above 20 T), and a peak at low magnetic field, respectively. From the relation between microstructure and flux pinning properties, it is supposed that the /spl sigma/-phase acts as an effective pinning center at high magnetic fields in Nb/sub 3/Al.         Short-sample quenching of Nb/sub 3/Al precursor strand in support of reel-to-reel process development    F. Buta, M.D. Sumption, E.W. Collings, N. Harada, E. Gregory and M. Tomsic Summary: Niobium-aluminum precursor strands were fabricated using the conventional jelly roll method with two Nb:Al volume ratios, 3:1, and 5:1. These mono-elements were restacked in 7-, 19- and 36-core arrangements and drawn down to wires approximately 0.8 mm and 0.4 mm in diameter. Short lengths of wire were resistively heated under high vacuum to temperatures as high as 2200/spl deg/C for various times, and either allowed to cool by radiation plus lead conduction or quenched into liquid gallium. Vacuum cooling led to a disordered A15 phase, which was then ordered by annealing at 800/spl deg/C; gallium quenching tended to produce the bcc phase, which could be transformed into A15 also by annealing for various times at 800/spl deg/C. The superconducting properties of the final wires were examined by vibrating-sample magnetometry (/spl chi//sub dc/ and T/sub c/) as well as transport J/sub c/ measurement. Best results so far are for a 5:1 Nb:AI volume ratio sample Ga quenched from 2000/spl deg/C with a secondary reaction of 800/spl deg/C/3 h, giving J/sub c/=4.5/spl times/10/sup 8/ A/m/sup 2/ at 12 T, with a T/sub c/=18-18.5 K.         Properties of fiber-reinforced niobium-tin superconductor fabricated by bronze process    H. Tateishi, K. Agatsuma, K. Arai, M. Umeda, K. Gotoh, N. Sadakata and T. Saitoh Summary: We are developing a fiber reinforced type of superconductor for large scale, high-field magnets. Formerly we used the sputtering process to develop a niobium-tin conductor reinforced with a tungsten fiber and showed that this type of conductor has excellent stress tolerance. For practical applications however, a conventional fabrication process like bronze process is desirable. Hence we have tried to fabricate a fiber-reinforced type niobium-tin conductor utilizing tantalum fiber as the reinforcing member, In this conductor, each niobium-tin filament has a tantalum core of about 20-/spl mu/m diameter, We adopted tantalum as the core material since it has both good ductility and mechanical strength comparable to stainless steel, This conductor showed a reasonable critical field of about 22 T and good mechanical strength compared to a niobium-tin conductor fabricated by the conventional bronze process.         Improvements of (NbTi)/sub 3/Sn bronze processed superconductor performance    A.K. Shikov, E.V. Nikulenkov, N.I. Salunin, G.P. Vedernikov, E.I. Plashkin, A.E. Vorobieva, A.G. Silaev, V.I. Pantsyrnyi, O.V. Malafeeva and E.A. Dergunova Summary: Research results are given for stabilized (NbTi)/sub 3/Sn strand with titanium artificial doped filaments. This work has been performed with the aim to improve the critical current density of the bronze processed strands designed for ITER. Strands with diameters in range 0.4 mm to 1.7 mm with composite filaments containing one or four cores made of Nb-Ti alloy as sources of doping element have been investigated. Critical current densities for some strands were investigated in the range of magnetic fields 8-22 T. It was shown that the strand containing 12684 filaments with 4 cores of Nb-Ti alloy in each filament had the best superconducting properties. J/sub c/ (non Cu) of this type of the strand with diameter of 0.81 mm was equal to 750 A/mm/sup 2/ at 12 T and had hysteresis losses /spl sim/100 mJ/cm/sup 3/ (/spl plusmn/3 T). This value was 1.3 times larger than the J/sub c/ value of the strand, which contained 1 core of Nb-Ti alloy. The maximum J/sub c/ (non Cu) attained for the strand 0.5 mm in dia with 12684 filaments was equal to 900 A/mm/sup 2/ at 12 T. Hysteresis losses for this strand were also less than 100 mJ/cm/sup 3/ (/spl plusmn/3T). It was shown that the developed strand with four cores of Nb-Ti alloy met both ITER Specifications HP-I and HP-II simultaneously. Also it is a perspective material for high field applications.         Recent development of niobium-tin superconducting wire at OST    Y. Zhang, J.C. McKinnell, R.W. Hentges and S. Hong Summary: Oxford Superconducting Technology (OST) produces Nb/sub 3/Sn superconductive composites via several different fabrication methods. We report here some aspect of improvements made in these products. Enhancement in very high field properties have been introduced for bronze processed composite using Nb filaments with Ta addition and bronze matrix with Ti addition. In modified jelly roll (MJR) composite non-copper critical current density has been improved to over 3000 A/mm/sup 2/ at 10T by modifying design. This performance is reproduced routinely in production.         The effect of hot isostatic pressing on the strain tolerance of the critical current density found in modified jelly roll Nb/sub 3/Sn wires    S.A. Keys, N. Cheggour and D.P. Hampshire Summary: The critical current density of Hot Isostatic Pressed (HIP'ed) and unHIP'ed Nb/sub 3/Sn Modified Jelly Roll wires has been measured as a function of magnetic field and of strain at 4.2 K. The reversibility of critical current density was investigated for both wires. The critical current and upper critical field were decreased for the HIP'ed sample. The reduced upper critical field of the HIP'ed wire was found to be less sensitive to strain than the unHIP'ed wire. The index (m) of the flux pinning scaling law is found to have increased from 0.86 to 2.14 as a result of the HIP processing.         Progress in the development of Nb/sub 3/Sn conductors based on the "Powder in tube" method with finer filaments    J.H. Londenhovius, E.M. Hornveld, A. den Ouden, W.A.J. Wessel and H.H.J. Ten Kate Summary: Inspired by the successful operation of the 11 T Nb/sub 3/Sn experimental dipole magnet MSUT, a new large bore 10 T@4.5 K Nb/sub 3/Sn model dipole magnet is under development in The Netherlands. For application in this system, Shape Metal Innovation (SMI) has developed a new "Powder in Tube" type of Nb/sub 3/Sn conductor with an increased number of filaments. At a strand diameter of 0.9 mm, the diameter of the filaments after reaction for only 33 hours at 675/spl deg/C has been reduced to about 20 microns. The non-copper critical current density has been measured to be as high as 1890 A/mm/sup 2/ at 10 T@4.25 K.         Low field flux jumping in high performance multifilamentary Nb/sub 3/Al and Nb/sub 3/Sn composite strands    M.D. Sumption, E.W. Collings and E. Gregory Summary: The problem of flux jumping in NbTi superconducting strands was solved 30 years ago by the introduction of suitably fine multifilamentary subdivision accompanied by twisting. But with recent advances in A15 superconductors we are entering a regime in which J/sub c/ may be increasing at a rate faster than effective filament diameter, d/sub eff/, can be reduced. This is particularly true for Nb-clad melt-processed Nb/sub 3/Al strands which at fields below H/sub c2,Nb/ have subelements which are superconductively coupled via the Nb matrix. Control of d/sub eff/, while still requiring attention, is less of a problem for the new very high J/sub c/ Nb/sub 3/Sn strands whose sub-elements, although fully bridged, are still able to be reduced in size. The results of some low field magnetization experiments are presented and interpreted in terms of a simple model.         Film orientation of RE123 prepared by chemical solution deposition    K. Yamagiwa, I. Hirabayashi, Xiuliang Ma, J. Shibata and T. Hirayama Summary: We investigated processing temperature dependencies of the preferred orientation axis of REBa/sub 2/Cu/sub 3/O/sub 7-y/ (RE123; RE=Yb, Er, Y, Gd, Sm, Nd, Pr and La) films prepared on various substrates by chemical solution deposition (CSD) using metal naphthenates. In the case of RE=Er, Y, Gd and Sm prepared on SrTiO/sub 3/, a/b-axis oriented films were obtained in a region of low temperatures, whereas there is no such temperature region for RE=Yb, Nd, Pr and La films. On the other hand, RE123 films prepared on LaAlO/sub 3/ gives a/b-axis orientation in a region of low temperatures except for Yb123 film. The (102) pole figures of these films give four high density points with four-fold symmetry, indicating that their axes are in-plane aligned. In order to confirm relationship between a/b-axis oriented growth and ionic radius of RE elements (R/sub i,RE/), we prepared rare-earth mixed Yb/sub 1-x/Er/sub x/Ba/sub 2/Cu/sub 3/O/sub 7-y/ and Sm/sub 1-x/Nd/sub x/Ba/sub 2/Cu/sub 3/O/sub 7-y/ films. Orientation of these films changed critically at certain average R/sub i,RE/'s.         Bulk texture and transport properties of magnetic field/liquid assisted textured YBa/sub 2/Cu/sub 3/O/sub 7-x/ tape-cast films    J.A. Lewis and A.C. Read Summary: Textured YBa/sub 2/Cu/sub 3/O/sub 7-x/ films (thickness=250 /spl mu/m) were fabricated by tape casting in an applied magnetic field (H=6 T). Platinum (1 wt.%) was incorporated to induce liquid phase-assisted densification in films fired on silver (Ag) foil to 935-942/spl deg/C under reduced pO/sub 2/(g) conditions. The transport critical current densities (J/sub ct/) of such films exhibited nearly field insensitive behavior between H=0-3 T (H/spl par/c-axis) at 77 K, with J/sub ct/>1000 A/cm/sup 2/ at H=0 T.         High rate deposition of 5 /spl mu/m thick YBa/sub 2/Cu/sub 3/O/sub 7/ films using the BaF/sub 2/ ex-situ post annealing process    V.F. Solovpov, H.J. Wiesmann, Li-Jun Wu, M. Suenaga and R. Feenstra Summary: We have investigated the crystallization of thick YBCO films under various annealing conditions. The films were deposited by high-rate co-evaporation of Y, Cu and BaF/sub 2/ onto room-temperature SrTiO/sub 3/ substrates at rates exceeding 10 nm/s. TEM microscopy was performed to establish the microscopic structure of partially processed films and help elucidate the growth mechanism. In-situ resistivity measurements were used to monitor the crystallization of the YBCO films during the annealing process. Resistivity measurements and TEM microscopy of samples at different stages of the film growth are compared. Our results indicate that, in addition to oxygen partial pressure, water vapor pressure is an important parameter which defines the dynamics of film growth and crystallization. 5 /spl mu/m thick films with J/sub c/>2/spl times/10/sup 5/ A/cm/sup 2/ (1 T H/spl par/c) have been fabricated.         Fabrication of YBCO thick films on cube textured Ni substrate with NiO intermediate layer    C.F. Liu, X. Wu, F.Y. Wang, Z.J. Yang, Y. Feng, P.X. Zhang, X.Z. Wu and L. Zhou Summary: High quality, sharp cube textured Ni substrates have been fabricated by a cold rolling and a recrystallization annealing process. X ray results show that there are some problems to be noted in the prevalent quality evaluation for a cube textured Ni substrate. In-plane-aligned, c axis-oriented YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) thick films were grown on the textured Ni substrate with self-oxidized NiO intermediate layer by an ink-printed and floating zone heating method. The values of the resistively measured T/sub c/ (onset) were 86 K. This is a very useful and promising method for producing the long YBCO tapes with high J/sub c/, although J/sub c/ is lower at present.         Filamentary YBCO conductors for AC applications    W.J. Carr Jr. and C.E. Oberly Summary: High current density YBCO conductors as they are presently conceived for use at liquid nitrogen temperatures are in the form of tapes, usually the order of a centimeter in width and suitable only for dc use. Possibilities for developing similar YBCO conductors for ac applications are discussed, and the ac loss expected from such conductors is computed. The conversion from a dc to an ac conductor requires breaking up a wide-tape dc conductor into narrow strip-like filaments which spiral about the conductor axis. Various ways of producing this pattern are proposed.         Microstructure and texture evolution in oxide films prepared by ion-beam assisted laser deposition    B. Holzapfel, V. Betz, D. Schlafer, H.-D. Bauer and L. Schultz Summary: Using Ion-Beam Assisted Laser Deposition (IBALD), biaxially oriented films of Yttria stabilized Zirconia were deposited on polycrystalline and amorphous substrates. The film texture in dependence of deposition parameters was examined with X-ray texture analysis. As deposited films were analyzed by transmission electron microscopy and atomic force microscopy. All films showed a columnar film growth structure. The diameter of the columns increased with film thickness and could be related to the film in-plane orientation. The nucleation process was found to be polycrystalline and independent of the ion-beam assistance. At an early growth stage, a growth structure of [001] oriented columns emerges from the randomly oriented crystallites. The film in-plane texture forms in a competition of [001] oriented columns, where columns oriented with their [111] axis parallel to the impinging ion-beam dominate the film texture. The out-of plane growth orientation was found to depend on substrate temperature and laser energy density, while the ion-beam affects mainly the in-plane orientation.         Melt growth and superconducting properties of textured Ag-YBa/sub 2/Cu/sub 3/O/sub 7/ conductors    S. Pinol, T. Puig, B. Martinez, X. Obradors and J.M. Chimenos Summary: Textured Ag foils 200 /spl mu/m thick have been obtained after cold rolling and recrystallization at 800/spl deg/C with a reduction ratio of up to 95%. Subsequently, a thick layer of YBa/sub 2/Cu/sub 3/O/sub 7/ (20 /spl mu/m) has been deposited by screen printing, A directional solidification process under a temperature gradient with displacement velocity between 1 mm/h and 10 mm/h has been performed to induce a biaxial texture to the superconducting layer. This last treatment has been performed at low P(O/sub 2/) atmosphere and at maximum temperatures below 945/spl deg/C. The texture of the layers has been studied by X-ray diffraction, rocking curves and pole figures, whilst the critical currents have been measured inductively by SQUID magnetometry. The relationship between the in-plane crystalline orientation and the observed critical currents has been discussed.         Magnetic field anisotropy of high critical current YBCO coated conductors    J.Y. Coulter, J.O. Willis, M.M. Mann, P.C. Dowden, S.R. Foltyn, P.N. Arendt, J.R. Groves, R.F. DePaula, M.P. Maley and D.E. Peterson Summary: High critical current (>100 A) YBCO thick films, or coated conductors, are being developed for superconductor applications. The critical current I/sub c/ of these materials exhibits a magnetic field dependence that depends on the angle of the applied field. Measurement of this anisotropy is critical to the development of high temperature superconductor applications. We have developed the capability to characterize the magnetic field anisotropy of large, high critical current YBCO superconductors as a function of angle. We have measured the magnetic field anisotropy of the critical current in the H/spl perp/I orientation of three samples in fields from 0 to 7 T and at temperatures from 75 K to 64 K. The results of these measurements characterize the field dependence of these materials and reveal performance issues of importance to applications. In contrast to previous measurements on thin films, which show that I/sub c/ for the H/spl par/c orientation has the strongest field dependence, we demonstrate that the intermediate angle of /spl sim/45/spl deg/ to the normal to the tape plane shows the greatest field dependence for these coated conductors on technical substrates. The field performance, anisotropy, and temperature dependence are discussed in relation to sample quality.         Processing dependence of biaxial texture in yttria-stabilized zirconia by ion-beam-assisted deposition    M.P. Chudzik, M.T. Lanagan and C.R. Kannewurf Summary: Biaxially textured yttria (8 mol%)-stabilized zirconia (YSZ) thin films were deposited on randomly oriented Hastelloy C and Stainless Steel 304 at room temperature as a buffer layer for subsequent deposition of oriented YBa/sub 2/Cu/sub 3/O/sub x/ films. The 0.16-1.3 /spl mu/m thick YSZ films were deposited by e-beam evaporation at rates of 1.2-3.2 /spl Aring//sec. Biaxially textured films were produced with an Ar/O/sub 2/ ion beam directed at the substrate during film growth. X-ray diffraction was used to study in-plane and out-of-plane orientation as a function of ion bombardment angle, film thickness, ion-to-atom flux ratio, and substrate material. In-plane and out-of-plane average-misorientation angles on these YSZ films that were deposited by ion-beam-assisted deposition were as low as 17 and 5.4/spl deg/, respectively, on as-received substrates.         Axial strain dependence at 77 K of the critical current of thick YBaCuO films on Ni-alloy substrates with IBAD buffer layers    C.L.H. Thieme, E. Fleshler, D.M. Buczek, M. Jowett, L.G. Fritzemeier, P.N. Arendt, S.R. Foltyn, J.Y. Coulter and J.O. Willis Summary: The strain sensitivity of YBCO coated conductors has been investigated by measuring the critical current density J/sub c/ in self field at 77K, as a function of applied tensile strain. The YBCO coated conductor used an Inconel substrate. One side was coated with a biaxially textured YSZ buffer layer, using ion-beam-assisted-deposition (IBAD), and was subsequently coated with a 2.5 micron thick YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// layer by pulsed laser deposition (PLD). The superconductor was then coated with a silver cap layer. For the I/sub c/-strain measurements 78 mm long sections were cut from a 115 cm long length. This was previously produced to demonstrate the feasibility of long YBCO coated conductors using the IBAD process. At 77K up to 0.5% strain does not change J/sub c/ by more than 3% This strain dependence is better than the tensile stress dependence of J/sub c/ when samples are bent at room temperature.         The microstructure of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films and yttria stabilised zirconia buffer layers deposited on inclined Hastelloy substrates    W.A.J. Quinton, W.Y. Liang, F. Baudenbacher, D.T. Foord, A.P. Bramley and S.B. Newcomb Summary: YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films have been grown on polycrystalline metallic substrates using intermediate yttria stabilised zirconia (YSZ) buffer layers. The buffer layers were grown by pulsed laser deposition using the inclined substrate deposition technique, whereby the substrate is tilted so that the ablated species arrive under an oblique incidence angle. One of the consequences of the inclined geometry is the alignment of the buffer layer crystal grains within the plane of the film which enables the subsequent deposition of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films With J/sub c/s of up to 10/sup 5/ A/cm/sup 2/. We present results showing that the optimum substrate inclination angle for the YSZ buffer layer deposition is around 55/spl deg/, and that the in-plane alignment improves linearly with film thickness. We also show transmission electron micrographs which demonstrate that grain sizes get larger and appear to be better aligned towards the buffer layer surface. We use these results to propose a mechanism by which texture occurs during inclined substrate deposition. The mechanism is based on three requirements inferred from our microstructural data: columnar growth, tilting of grains towards the incoming ablated species, and a preferred growth orientation normal to the substrate surface.         YBCO films on metal substrates with biaxially aligned MgO buffer layers    M. Bauer, R. Semerad and H. Kinder Summary: We successfully deposited high quality YBCO films on metal tapes with biaxially aligned MgO buffer layers. e-gun evaporation on inclined substrates with a very high deposition rate of up to 250 nm/min was used for the deposition of the buffer layers. The MgO layers are biaxially textured with an in-plane full width at half maximum of 80. The MgO [001]-axis is not parallel to the substrate normal but tilted significantly towards the deposition direction. YBCO films were deposited on ISD buffer layers by reactive thermal co-evaporation. The critical current density of the films was found to be anisotropic due to the tilt of the [001]-axis. Critical current densities up to 7.9/spl times/10/sup 5/ A/cm/sup 2/ at 77 K were achieved.         Direct deposition of c-axis textured MBCO thick film on unoriented metallic substrate for the development of long superconducting tapes    Xuejun Wen, Dehui Qu, B.A. Tent, Donglu Shi, M. Tomsic, L. Cowey and M. White Summary: Direct peritectic growth (DPG) is a novel process in which textured YBCO thick films are deposited directly onto an unoriented silver alloy. No buffer layer is employed between the YBCO superconducting film and the silver alloy substrate. The textured YBCO grains have been obtained through peritectic solidification over a wide range of temperature and time. No observable reaction of the substrate was found with the YBCO melt at the maximum processing temperatures near the peritectic point (from 950/spl deg/C to 1030/spl deg/C). The transport J/sub c/ has reached a respectable value of 8/spl times/10/sup 4/ A/cm/sup 2/ at 77 K and in zero magnetic field. In this paper, we show that the DPG method is capable of producing highly textured YBCO thick films, which are scalable to long lengths with low cost.         Cracking of rare earth barium cuprate films prepared by liquid phase epitaxy    T. Aichele, P. Gornert, R. Uecker and M. Muhlberg Summary: A high growth rate of REBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (RE=rare earth elements) superconducting films is achieved with liquid phase epitaxy. The occurrence of cracks is one of the major problems for applications of these thick films. To achieve crack free films, it is necessary to understand the formation of cracks in REBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films. Investigations were carried out on YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// and (Y,Pr)Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// films on NdGaO/sub 3/ substrates and on new SrPrGaO/sub 4/ substrates with tetragonal K/sub 2/NiF/sub 4/ structure (space group I4/mmm). A thermodynamic model for understanding the crack spacing together with mechanical properties determined in melt textured YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// bulk samples was applied.         Bench scale evaluation of batch mode dip-coating of sol-gel LaAlO/sub 3/ buffer material    A. Sheth, V. Lasrado, M. White and M. Paranthaman Summary: In a joint program between the University of Tennessee Space Institute (UTSI) and Oak Ridge National Laboratory (ORNL), thin films of lanthanum aluminate (LAO) were formed on [100] strontium titanate (STO) single crystals and on biaxially textured nickel by dip-coating from sol-gel precursors and then annealing. XRD texture measurements were used to evaluate coating parameters including substrate withdrawal speed, degree of hydrolysis, and thermal processing temperature, duration, and atmosphere. LAO films on the order of 1000 thick showed 100% biaxial epitaxy on STO single crystals but only about 50% in-plane epitaxy on nickel. An increase in substrate withdrawal velocity resulted in thicker films. On STO film texture degraded with increased film thickness, but on nickel this effect was not noted, being obscured as a result of the rather poor and variable texture of the nickel substrate used. LAO on STO texture was improved by increases, within the ranges investigated, in the degree of hydrolysis, and in the thermal processing time, temperature, and oxygen concentration. No impediments to production scale-up were found.         High-T/sub c/ coated conductors-performance of meter-long YBCO/IBAD flexible tapes    S.R. Foltyn, P.N. Arendt, P.C. Dowden, R.F. DePaula, J.R. Groves, J.Y. Coulter, Quanxi Jia, M.P. Maley and D.E. Peterson Summary: One meter long tapes based on 50-100 /spl mu/m thick by 1 cm wide nickel alloy substrates have been coated in a continuous process with a textured yttria-stabilized zirconia layer by ion beam-assisted deposition, followed by a 1-2 /spl mu/m thick layer of YBCO by pulsed laser deposition. The best result to date is a tape with a critical current (I/sub c/) at 75 K of 96 A over an 87 cm measurement length. The overall critical current density and engineering current density are 1 MA/cm/sup 2/ and 10 kA/cm/sup 2/, respectively. Using a special probe, individual I-V curves were generated for each centimeter of tape length in order to investigate longitudinal uniformity of the transport properties: the highest and lowest I/sub c/ values fall within a range of /spl plusmn/25%.         Y-Ba-Cu-O film deposition by metal organic chemical vapor deposition on buffered metal substrates    V. Selvamanickam, G. Galinski, J. DeFrank, C. Trautwein, P. Haldar, U. Balachandran, M. Lanagan and M. Chudzik Summary: YBa/sub 2/Cu/sub 3/O/sub x/ (YBCO) films have been deposited on buffered metal substrates by metal organic chemical vapor deposition (MOCVD). Cube-textured nickel substrates were fabricated by a thermomechanical process, epitaxial CeO/sub 2/ films were deposited on these substrates by thermal evaporation. Nickel alloy substrates with biaxially-textured Yttria-Stabilized Zirconia (YSZ) buffer layers deposited by ion beam assisted deposition were also prepared. Highly biaxially textured YBCO films were deposited by MOCVD on both types of metal substrates. A critical current density greater than 105 A/cm/sup 2/ at 77 K has been achieved in YBCO films on metal substrates.         Growth and characterization of oxide buffer layers for YBCO coated conductors    M.W. Rupich, W. Palm, W. Zhang, E. Siegal, S. Annavarapu, L. Fritzemeier, M.D. Teplitsky, C. Thieme and M. Paranthaman Summary: Metal oxide films were grown on single crystal oxide substrates and deformation textured metal substrates by a metal organic deposition technique using metal alkoxides as the starting precursor materials. The crystallinity, grain alignment, and morphology of the oxide films depend on the process conditions and the substrate properties. Epitaxial oxide films were grown under a range of oxygen partial pressures and temperatures required for film formation on technologically important metal substrates. YBCO films grown on epitaxial LaAlO/sub 3/ buffer layers on single crystal SrTiO/sub 3/ had J/sub c/'s of 2.2 MA/cm/sup 2/ (77 K, self-field) demonstrating the quality of the MOD derived oxide films.         High critical current density thick MOD-derived YBCO films    J.A. Smith, M.J. Cima and N. Sonnenberg Summary: High critical current density thick MOD (metal-organic-deposition)-derived Ba/sub 2/YCu/sub 3/O/sub 7-x/ (BYC) films have been prepared on latticed matched single crystal lanthanum aluminate substrates. Critical current densities of approximately one million amps per square centimeter (at 77 K) have been obtained from one micron thick BYC films. These superconducting films were prepared from a single MOD coating. Substrate coatings of a mixed metal trifluoroacetate precursor were first converted into high quality mixed metal oxyfluoride films by heat treating under controlled conditions. These films were then patterned and subsequently converted into epitaxial BYC by exposure to water vapor at higher temperatures, High critical current density films were obtained by controlling the conversion kinetics of the mixed metal oxyfluoride films into BYC.         Critical current density in highly biaxially-oriented YBCO films: Can we control J/sub c/(77 K) and optimize up to more than 10/sup 6/ amp/cm/sup 2/?    V.M. Pan, A.L. Kasatkin, V.L. Svetchnikov, V.A. Komashko, A.G. Popov, A.Yu. Galkin, H.C. Freyhardt and H.W. Zandbergen Summary: High-J/sub c/ YBCO conductors of the second generation are based on processing of YBCO highly-textured film, It is important to develop deposition techniques to control and optimize flux pinning in such films. The dominant contribution to net pinning force in YBCO films is from the growth-induced dislocations. The average density of such dislocations in low-angle tilt domain boundaries can exceed 10/sup 11//cm/sup 2/. For 2D fluxline lattice (FLL) correlated disorder induced by linear defects, a simplified approach is proposed to get some optimization criteria for the critical current density as a function of domain size, misorientation angle, etc. During YBCO films deposition onto highly-textured buffer layers growth dislocation structures can be varied, Comparison of the high-resolution transmission electron microscopy (HREM) data and J/sub c/(H) angular dependencies for CeO/sub 2/-buffered YBCO films exhibit how the dislocation distribution can affect the angular J/sub c/(H) behavior.         Fabrication of in-plane aligned YBCO films on polycrystalline Ni tapes buffered with surface-oxidized NiO layers    K. Matsumoto, Seokbeom Kim, Jian-Guo Wen, I. Hirabayashi, T. Watanabe, N. Uno and M. Ikeda Summary: Strongly in-plane aligned, c-axis oriented YBCO films were successfully grown on polycrystalline nickel tapes buffered with [100]-oriented NiO layers. The in-plane and out-of-plane alignments of the NiO layer were achieved by a surface-oxidation epitaxy (SOE) technique using a [100]<001> cube-textured nickel tape. The in-plane textures of NiO layers fabricated so far with the full width half maximum (FWHM) values of 11-13 degrees are sufficient for the epitaxial growth of high-J/sub c/ YBCO films. Pulsed laser deposited YBCO layers on the NiO/Ni tapes were not only c-axis oriented with respect to the type surface, but also strongly in-plane aligned. The YBCO films on NiO/Ni tapes have a zero resistance T/sub c/=87 K and J/sub c/=10/sup 4/-10/sup 5/ A/cm/sup 2/ at 77 K.         Simultaneous double-sided deposition of HTS films on 3-inch wafers by ICM-sputtering    J. Geerk, F. Ratzel, H. Rietschel, G. Linker, R. Heidinger and R. Schwab Summary: The construction of a system which allows simultaneous deposition of HTS films on both sides of 3-inch wafers is described. The wafers are placed in a heating cavity which can be heated to 1000/spl deg/C. Deposition is accomplished through two opposite holes in the cavity by inverted cylindrical magnetron (ICM) sputtering guns. YBaCuO films deposited on 3 inch CeO/sub 2/ buffered sapphire substrates revealed a growth quality and T/sub c/ and j/sub c/ values comparable to standard films with sufficient uniformity on both sides of the wafer. The surface resistance of the films measured in the frequency range of 2.68 to 145 GHz is 20 m/spl Omega/ at the highest frequency.         In-situ monitoring during PLD of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// using RHEED at high oxygen pressure    G.J.H.M. Rijnders, G. Koster, D.H.A. Blank and H. Rogalla Summary: The surface morphology and initial growth of YBa/sub 2/Cu/sub 3/O/sub u-/spl delta//, using Pulsed Laser Deposition (PLD), have been subject to in many studies. Both, Scanning Probe Microscopy (SPM) as well as Reflection High Energy Electron Diffraction (RHEED) have been applied. The latter is mostly operated using modified deposition parameters, like a reduced oxygen pressure. Here, we have studied the initial growth using a PLD-RHEED system at standard PLD pressures. In this system, in-situ RHEED can be applied in a background pressure of oxygen up to 50 Pa. The initial growth of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// on SrTiO/sub 3/ substrates is studied. The influence of the substrate termination, i.e., SrO or TiO/sub 2/, on the growth will be discussed.         Superconducting properties of Cu/sub 1-x/Tl/sub x/-1223 [Cu/sub 1-x/Tl/sub x/(Ba,Sr)/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10-y/] thin films    H. Ihara, Y. Sekita, H. Tateai, N.A. Khan, K. Ishida, E. Harashima, T. Kojima, H. Yamamoto, K. Tanaka, Y. Tanaka, N. Terada and H. Obara Summary: The bi-axially-oriented thin films of Cu/sub 1-x/Tl/sub x/(Ba,Sr)/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10-y/(Cu/sub 1-x/Tl/sub x/-1223: x=0.2-1.0) were prepared by an amorphous phase epitaxy (APE) technique on SrTiO/sub 3/ substrates. The amorphous phase was deposited by sputtering on the substrate and annealed in a thallium atmosphere at /spl sim/885/spl deg/C for /spl sim/50 min. Their T/sub c/ values were 100-113 K and higher than those of the YBa/sub 2/Cu/sub 3/O/sub 7-y/ (Y-123, that is, Cu-1212) system. Their J/sub c/ values were 2/spl times/10/sup 7/ A/cm/sup 2/ (77 K, 0 T) and 4/spl times/10/sup 5/ A/cm/sup 2/ (77 K, 10 T) at their maximum for x/spl sim/0.5. The J/sub c/ values were higher than the maximum values of Y-123 thin films by a factor of 2. The high J/sub c/ values are consistent with the low superconducting anisotropy (/spl gamma/=/spl xi//sub ab///spl xi//sub c/=2.5-4) of Cu/sub 1-x/Tl/sub x/-1223 and its high T/sub c/.         Remarkable properties of Tl-Ba-Ca-Cu-O thin films following post-growth high-temperature annealing    M.P. Siegal, D.L. Overmyer, E.L. Venturini, R.R. Padilla and P.N. Provencio Summary: Tl-2212 and Tl-1212 are the two easiest unsubstituted Tl-Ba-Ca-Cu-O superconducting thin films to grow. Both phases exhibit T/sub c//spl ges/95 K, J/sub c/(5 K)>10 MA/cm/sup 2/ and smooth morphologies. We report on the properties of both materials following one hour furnace anneals in dry ambients of pure oxygen or nitrogen at temperatures ranging from 50-700/spl deg/C. The stability of these films to high temperatures in each ambient is important for device processing. Of equal interest is the controlled partial volatilization of Tl-oxide at modest temperatures from nano-site regions within Tl-1212 films. We correlate such modifications with increases in flux pinning strength in Tl-1212 films. Tl-2212 films maintain their superconducting properties to even higher temperatures than Tl-1212 films. Optimum annealing appears to also increase flux pinning, although not to the same degree as for Tl-1212 films.         Development of high performance Nb-Ti(Fe) multifilamentary superconductor for the LHC insertion quadrupoles    P.J. Lee, C.M. Fischer, W. Gabr-Rayan, D.C. Larbalestier, M.T. Naus, A.A. Squitieri, W.L. Starch, E.Z.A. Barzi, P.J. Limon, G. Sabbi, A. Zlobin, H. Kanithi, S. Hong, J.C. McKinnell and D. Neff Summary: A development program was initiated in order to develop strand with improved current density at 10.5 T and 1.9 K over existing SSCL designs. The two successful strand designs reported on here both utilized high Fe content Nb-47 wt%Ti alloys to improve the critical current density at high field by 7 %. At 10.5 T and 1.9 K, critical current densities exceeding 1450 A/mm/sup 2/ were obtained. In this paper we report detailed quantification of the macro- and micro-structures of these strands and correlate these with critical current density measurements at 1.9 K and 4.2 K. The high Fe content significantly reduced the /spl alpha/-Ti precipitate size. The linear relationship between critical current density and precipitate volume found is in agreement with earlier studies. High resolution FESEM electron backscatter contrast suggests a thin layer of high atomic number at grain boundaries.         Evaluations of Nb-25 wt.%Ti alloy wires    K. Tachikawa, N. Abe and Y. Yamada Summary: An arc-melted Nb-25 wt.%Ti alloy was fabricated into monocore wires with Cu matrix. The structure and superconducting properties of the wires were compared with those of Nb-46.5 wt.%Ti and Nb-36 wt.%Ti wires prepared by similar process. The formation of a thick Cu-Ti-Nb compound layer is observed at the Cu/Nb-46.5Ti interface after heat treatment at above 600/spl deg/C. A thin compound layer is also formed at the Cu/Nb-36Ti interface after heat treatment. Meanwhile, no compound layer is observed at the Cu/Nb-25Ti interface. This is a major advantage of Nb-25Ti wire, which may save the wrapping of Nb foil around the cores to prevent the reaction with the Cu matrix, when they are fabricated into fine filaments. The T/sub c/ of Nb-25Ti wire is about 0.7 K higher than that of Nb-46.5Ti wire. The T/sub c/ and B/sub c2/ of Nb-25Ti wire are less sensitive to the reduction in diameter and the heat treatment compared to the Nb-46.5Ti wire. The B/sub c2/(4.2 K) of Nb-25Ti as wire seems to be high enough for AC applications. The addition of boron enhances the T/sub c/ and B/sub c2/ of Nb-25Ti alloy.         Some properties of NbTiTa ternary alloys    E. Gregory and T. Pyon Summary: There is a need for a relatively low cost, trouble free material for use in intermediate field (10.5T to 11.0T) accelerator magnets. These would operate at 1.9 K and the aim is to produce ductile material with properties superior, at that temperature, to those of the 46.5 wt.% Ti 53.5 wt.% Nb binary alloy. Three alloys were plasma melted to ensure high homogeneity. The compositions were, in weight percentage, Ta17Ti44Nb39 Ta28Ti41Nb31, Ta12Ti46Nb42. These three alloys were processed as monofilamentary material and tested after a series of different heat treatments. Attempts were made to optimize J/sub c/ for each of the compositions at 4.2 K and these samples were then tested at 1.9 K and the shift in the field for a constant J/sub c/ determined. A similar investigation on multifilamentary materials of these compositions is now being carried out.         Development of high performance multifilamentary Nb-Ti-Ta superconductor for LHC insertion quadrupoles    P.J. Lee, C.M. Fischer, D.C. Larbalestier, M.T. Naus, A.A. Squitieri, W.L. Starch, J. Werner, P.J. Limon, C. Sabbi, A. Zlobin and E. Gregory Summary: A preliminary investigation of a new Nb-Ti-Ta (39 wt.%Nb, 44 wt.%Ti, 17 wt.%Ta) alloy has been investigated as a possible material for application at 1.9 K and 10.5 T in the insertion quadrupoles of LHC, 1550 A/mm/sup 2/, the highest yet reported critical current density at 10.5 T (1.9 K), was achieved in a monofilament of this material. The initial multifilamentary production strand produced a lower 10.5 T (1.9 K) critical current density of 1370 A/mm/sup 2/. Large variations in precipitate size were produced in the microstructures, which have yet to be fully optimized. Quantitative analysis of the microstructures in a Nb-44 wt.%Ti-15 wt.%Ta alloy reveals a linear relationship between volume % of /spl alpha/-Ti precipitate and critical current density at 5 T and 8 T (4.2 K). The increase in critical current with precipitate volume is less than for Nb-47 wt.%Ti. High resolution FESEM electron backscatter images suggest a high atomic number region adjacent to the grain boundaries after heat treatment.         Fabrication and characterization of (rare-earth)-barium-copper-oxide (RE123 with RE=Y, Er, and Sm) films    C. Kwon, L.R. Kinder, Y. Gim, Y. Fan, J.Y. Coulter, M.P. Maley, S.R. Foltyn, D.E. Peterson and Q.X. Jia Summary: Epitaxial (rare-earth)Ba/sub 2/Cu/sub 3/O/sub 7/ films, RE123, with RE=Y, Er, and Sm have been fabricated using pulsed laser deposition on various single crystal substrates. Deposition of each material is optimized for T/sub c/. T/sub c/ values of 89.9 K, 91.0 K, and 93.0 K are obtained for Er123, Y123, and Sm123, respectively. T/sub c/ in RE123 films increases with increasing the ionic size of the rare-earth element as observed in bulk. Study of field- and angle-dependent J/sub c/ shows that the vortex pinning anisotropy is also affected by the rare-earth element. The Sm123 film has the best pinning characteristics in high magnetic fields among the investigated materials. The results will be discussed in relation to the crystal chemistry and internal stress due to the ionic size of rare-earth element.         Doping study of superconductivity in YBCO films by ion implantation    S.H. Hong, H. Xu, E. Gao, S. Sahba and Q.Y. Ma Summary: We present the results of doping by ion implantation in YBCO films with 5 different ions (Ca, Na, Mg, Be, Li). Ion selection is based on the difference of ionic radii and heat of formation value. Ionic radii plays a critical role to crystal damage in the implantation process. Ni ions were implanted to YBCO films with different doses so that the resistance of the implanted film was varied. Different values of resistance of the Ni implanted structures were applied to the fabrication of chip resistors.         Analysis of growth conditions of SmBaCuO thin films    A. Di Trolio, A. Morone, S. Orlando, U. Gambardella and S. Pace Summary: In this paper we analyze the critical temperature of SmBaCuO thin film grown by means of pulsed laser deposition as a function of the relevant deposition parameters, i.e., the pressure of the reactive oxygen atmosphere and the substrate temperature. We used a Nd-YAG radiation at 532 nm. The films have been deposited either on oriented magnesium oxide [100] or on strontium titanate [100] single crystals. The substrate temperature range spans from 650/spl deg/C to 800/spl deg/C, and the oxygen pressure is in the range (10/sup -5/-4/spl times/10/sup -1/) mbar. In these ranges of parameters we get metallic behavior of the resistance vs. temperature, with an onset of the critical temperature up to 91 K. XRD characterizations showed the orientation of c axis normal to the substrate surface.         Influence of target processing on properties of NdBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films grown by PLD: comparison of sintered ceramic and single crystal targets    Y. Le and K. Tanabe Summary: The influence of target processing on properties of deposited NBCO films, including superconductivity, epitaxial structure, and surface morphology has been systematically investigated between a large Nd123 single crystal and slightly Ba-rich Nd/sub 1-x/Ba/sub 2+x/Cu/sub 3/O/sub 7-/spl delta// (x=0.00, 0.03, 0.05, and 0.10) sintered ceramic targets. The films with excellent superconductivity and good crystallinity were grown on SrTiO/sub 3/ [100], LaAlO/sub 3/ [100], and NdGaO/sub 3/ [110] substrates by pulsed laser deposition (PLD). At optimized deposition conditions, T/sub c0/ of 90-94 K is routinely achieved. The critical current density J/sub c/ is >3/spl times/10/sup 6/ A/cm/sup 2/ at 77 K. The films deposited from sintered targets exhibit a typical droplet density of 10/sup 6/-10/sup 7//cm/sup 2/ on the film surface. However, the films deposited from the single crystal target show smooth nearly droplet-free surface morphology. Our results indicate that single crystal targets are more suitable for the growth of smooth high-T/sub c/ superconducting films by PLD.         Preparation and characterization of NdBa/sub 2/Cu/sub 3/O/sub y/ thin films    W.H. Tang and J. Gao Summary: C-axis oriented epitaxial NdBa/sub 2/Cu/sub 3/O/sub y/ thin films on [100] SrTiO/sub 3/ substrates were prepared by off-axis rf sputtering. Thin films with T/sub c0/=90 K in a deviation of 0.5 K were prepared reproducibly under the optimal depositing conditions. A parabolic relation of T/sub c0/ to c-axis lattice parameter corresponding to a typical electronic phase diagram for high-T/sub c/ superconductors was observed, indicating an optimal oxygen content for the best superconductivity. The oxygen out-diffusion and thermal expansion of the films were studied by an in-situ high temperature x-ray diffraction.         Critical current measurements on long BSCCO tapes using a contact-free method    M.D. Bentzon and P. Vase Summary: Experimental results showing I/sub c/ versus length for long Ag/Bi(Pb)-2223 multifilament tapes are presented. The results are obtained using a contact-free method (Hall probe) measuring the shielding and remanent magnetic fields created by tapes when exposed to an external magnetic field. The main goal of this paper is to study the potentials of the applied method and the study includes reproducibility, resolution, non-destructiveness and usefulness in the production of tapes. The results show that the reproducibility is so high that the method can be used to identify individual tapes by their signal pattern and the spatial resolution is demonstrated to be as good as a few mm. The non-destructiveness is generally good. The first cycle/re-coiling of a tape may decrease the critical current by less than 2%, and each following cycle is observed to have an effect of less than 0.5%. This contact-free method offers the tape manufacturer a detailed picture of the superconductive properties of the final product and is therefore a good tool for product development and quality control.         Homogeneity studies of multifilamentary BSCCO tapes by three-axis Hall sensor magnetometry    J. Paasi, T. Kalliohaka, A. Korpela, L. Soderlund, P.F. Hermann, J. Kvitkovic and M. Majoros Summary: A new generation of Hall sensor magnetometer for non-destructive studies of superconductor homogeneity is proposed and tested. The magnetometer allows us to measure the three-dimensional spatial dependence of all three components of magnetic field produced by applied or induced currents in the conductor. This new technique is more sensitive to detect small obstacles in the current path than the old Hall sensor techniques measuring only the field component perpendicular to the flat surface of the conductor. Having presented the measurement system, the method is demonstrated by experiments on multifilamentary BSCCO tapes.         Experimental investigation of a local mixed state induced by a small ferroparticle in YBaCuO films    Yu.N. Nozdrin, A.S. Mel'nikov, I.D. Tokman, P.P. Vysheslavtsev, A.Yu. Aladyshkin, E.B. Kluenkov and A.K. Vorobiev Summary: Direct local measurements of the characteristics of a mixed state induced by a magnetic field of a small ferromagnetic particle have been carried out in thin film YBaCuO samples, using a scanning Hall probe. The results provide evidence for an extremely low energy barrier for entry of vortex half-loops into high quality films and further breaking of these half-loops into vortex-antivortex pairs. The observed phenomena are consistent with the Josephson medium model. We obtained the temperature dependence of the intergrain critical current density, which points to strong pair breaking effects at the grain boundaries.         Continuous recording of the transport properties of a superconducting tape using an AC magnetic field technique    B. ten Haken, R.A.M. Budde, H.H.J. ten Kae, M.D. Bentzon and P. Vase Summary: The transport properties of superconductors are commonly characterized by means of a 4-probe measuring technique and the critical current is determined on a certain criterion for the electrical field. An alternative method to investigate the transport properties is to measure the magnetic response of a superconductor in a changing magnetic field. This magnetic technique has the interesting advantage that it can be used to investigate long lengths of (insulated) conductor. A detailed analysis is made to develop a reliable measuring procedure for this new test facility. The magnetic response of a superconductor is modeled in a description for an infinitely long tape with a rectangular cross-section and an arbitrary voltage-current relation. The calculated magnetic profiles, in space and time, are compared with experimental results at 77 K. It is demonstrated that the magnetic signal can be used to monitor the quality of a long length of tape (>500 m) with a high accuracy. Additionally it is shown that the shape of the voltage-current relation can be reconstructed based on the frequency dependence of the magnetic response.         Current and field penetration in a superconductor in the field of a permanent magnet    C. Navau and A. Sanchez Summary: We calculate the current and field profiles in a finite cylindrical type-II superconducting sample which result from displacing it within the magnetic field created by a coaxial permanent magnet. The method of calculation is based on minimizing the magnetic energy in the superconductor, by introducing currents with a maximum density, following the critical-state model. The effects of the superconductor finite size are fully incorporated in the calculations. The levitation force of such a system is calculated from the previous results.         Implications of low angle YBa/sub 2/Cu/sub 3/O/sub 7-x/ bicrystal transport characteristics for coated conductor applications    N.F. Heinig, G.A. Daniels, M. Feldmann, A. Polyanskii, D.C. Larbelestier, P. Arendt and S. Foltyn Summary: Coated conductor (CC) YBa/sub 2/Cu/sub 3/O/sub 7-x/ prototypes can now be made with critical current density, J/sub c/ (77 K, 0 T), values of 1-2 MA/cm/sup 2/ and full width half maximum (FWHM) in-plane misalignments of 7/spl deg/-15/spl deg/. In order to understand better the current paths in such conductors, we have measured extended electric field-current density (E-J) characteristics in fields of 0-9 T at 77 K, comparing the data to that obtained on thin film bicrystals. We find that the E-J curves of the CC show little sign of weak coupling. We also investigate the role sample thickness plays in intergranular high field transport by measuring E-J curves up to 8 Tesla on 7/spl deg/[001] tilt bicrystal films with thickness between 75 and 300 nm. We see that the intergrain irreversibility field increases with thickness, much as has been seen in single crystal samples. Magneto-optic imaging and scanning electron microscopy show that porosity in the YBa/sub 2/Cu/sub 3/O/sub 7-x/ layer and scratches in the ceramic buffer layers can also control J/sub c/. These results show that the critical current density of coated conductors is limited on several length scales and by several different defect types.         The use of cubic Nd-Ba-Cu-O seeds to create /spl theta/[100], 90/spl deg/-/spl theta/[100], and /spl theta/[001] tilt Y-Ba-Cu-O grain boundaries    M.B. Field, T.A. Byrne and D.J. Miller Summary: Using seeding techniques to control the orientation of grains, we have been able to create a wide variety of YBa/sub 2/Cu/sub 3/O/sub 6+x/ grain boundaries. In addition to five domain samples with 90/spl deg/[100] twist and tilt grain boundaries, we have now developed a method to produce grain boundaries in the same sample that have the misorientations /spl theta/[001] tilt, /spl theta/[100] tilt, and 90/spl deg/-/spl theta/[100], where the misorientation angle /spl theta/ is fully controllable. We will demonstrate how these boundaries can be synthesized, give experimental evidence via polarized light microscopy and electron backscatter patterns (EBSP) that the intended grain boundaries were indeed formed, and discuss the importance of these boundaries in future grain boundary studies.         Transport properties of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// bicrystals with [100] tilt grain boundaries    Y.N. Tsay, Q. Li, Y. Zhu, M. Suenaga, K. Shibutani, I. Shigaki and R. Ogawa Summary: We have successfully isolated more than a dozen of naturally-grown [100] tilt Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// (Bi-2212) bicrystals for the study of the transport properties of the grain boundary. These bicrystals contain a single clean [100] non-basal-plane-faced tilt grain boundary with various degrees of misorientation. Systematic transport measurements of these grain boundaries were performed in a wide range of temperature and magnetic field by measuring the resistance and the current-voltage characteristics for both single crystals and grain boundaries simultaneously. In addition, the microstructures of the grain boundaries in some of these bicrystals were studied by both conventional TEM and high-resolution electron microscopy (HREM).         Contribution of grain boundary planes to superconducting coupling in YBCO    M. Mironova, S. Stolbov, Guoping Du and K. Salama Summary: High-angle grain boundaries are considered to be the main obstacle for current flow in polycrystalline bulk superconductors. In bicrystal YBCO thin films, it has been shown that the current carrying behavior of grain boundaries is strongly dependent on misorientation angles. However, grain boundaries formed by the liquid phase removal method in bulk YBCO do not show such dependence, where high-angle grain boundaries are found to be capable of carrying high currents. To understand the mechanism by which current is carried by these high-angle grain boundaries, we performed TEM studies on two high-angle boundaries whose J/sub c/ varied considerably. The misorientation characteristics and grain boundary planes for these grain boundaries were determined.         Measurements of misorientation angles over a large distance in strongly coupled grain boundaries    M. Mironova, Guoping Du and K. Salama Summary: Grain boundaries in polycrystalline melt-textured YBCO samples fabricated by the liquid phase removal method have been analyzed by transmission electron microscopy (TEM). These samples contain a number of grains separated by high-angle grain boundaries with lengths up to several millimeters and J/sub c/ values up to 18000 A/cm/sup 2/ at 77 K. The results of TEM studies show that the high misorientation angles of these boundaries are maintained over a large distance by certain intra-grain features such as platelet boundaries and low-angle grain boundaries. Measurements on adjacent platelets as well as at locations inside single grains show that the presence of these boundaries maintains the misorientation of the high-angle grain boundary in these samples within 6 degrees. This indicates that high-angle grain boundaries in these samples do not dissociate into low-angle grain boundaries and the high superconducting current is carried by the entire length of the boundary.         Characterization of liquid phase epitaxy grown YBa/sub 2/Cu/sub 3/O/sub 7-x/ thick films as superconductive substrates    N. Tanaka, K. Hashimoto, H. Zama, S. Miura, T. Morishita and H. Yamamoto Summary: The liquid phase epitaxy (LPE) grown YBa/sub 2/Cu/sub 3/O/sub x/ (YBCO) thick films are characterized as a superconductive substrate in comparison with bulk YBCO single crystal substrates. We have focused on the study of the chemical treatments improving the [001] YBCO surface which is mechanically polished. The reaction of the YBCO surface with the HCl/absolute methanol solution is effective for removing damaged remnants on the surface without roughening. Resulting surfaces are precisely examined by observations of atomic force microscopy. The topographical image and its line profile have confirmed that [001] YBCO surfaces are terminated by a unique atomic layer. The chemical stability is also examined under the conditions that additional depositions are followed to form a multilayer structure for devices.         The effect of substrate vicinal offcut on the morphology and physical properties of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films    D. Vassiloyannis Summary: In this work we present a simple and reliable new method for producing YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films with an exceptionally high J/sub c/ value, one order of magnitude higher than the value usually reported for this phase and a low surface roughness/spl sim/1 nm. Using SrTiO/sub 3/ substrates polished at low angles off the [001] towards the [010] plane provides control over both the physical properties and surface roughness of the films grown, with the 1.7/spl deg/ misorientation angle leading to films with the best properties.         Superconducting YBa/sub 2/Cu/sub 3/O/sub 7/ on MgO buffered [100] Si for high frequency applications-buffer layer deposition techniques and processing considerations    Yu. Vlasov, A. Lacambra, R. Soto, G.L. Larkins Jr., P. Stampe and R. Kennedy Summary: The use of MgO as a buffer layer between YBa/sub 2/Cu/sub 3/O/sub 7/ and Si has advantages for microwave applications. MgO has a low dielectric constant, small loss tangent and is relatively stable. Silicon as a substrate material is relatively inexpensive and, more importantly, active semiconductive devices can be imbedded in it. This presents certain challenges from a processing point of view in terms of materials compatibility and growth. We have discovered that maintaining a silicon surface free of any native oxide is critical to obtaining acceptable results. As of this writing we are producing 1.5 cm/spl times/1.5 cm films using both PLD and feedback controlled reactive RF sputtering for the MgO followed by PLD deposited YBa/sub 2/Cu/sub 3/O/sub 7/. The resulting films are c-axis oriented and randomly oriented in-plane according to X-ray diffraction data. T/sub C(R=0)/'s of the films are 70-80 K with transition onsets ranging from 82 to 92 K depending on the method of substrate preparation and the deposition parameters. The most recent processing details, full X-ray characterization of the film structures, and some microwave characteristics will be presented and discussed.         Deposition of YBCO thin films on MgO buffer layer fabricated on Si substrates    H. Shimakage, A. Kawakami and Z. Wang Summary: Epitaxial growth of YBCO thin films with a MgO buffer layer on Si[100] substrate is reported. The MgO thin film was deposited by RF magnetron sputtering, using a single crystal MgO target. The crystallization of the MgO thin films was found to be dependent on the substrate temperature and the sputtering gas mixture. The x-ray diffraction pattern showed that the MgO thin film grew epitaxially in the [200] orientation on the Si substrates in atmosphere containing nitrogen gas. YBCO thin films deposited by laser ablation on Si substrate buffered with MgO thin films had a c-axis orientation with a critical temperature of 82 K. The critical temperature was found to be dependent on the substrate temperature in depositing the MgO buffer layer. Also the surface morphology of MgO and YBCO thin films is discussed.         Epitaxial growth of YBCO thin films on Al/sub 2/O/sub 3/ substrates by pulsed laser deposition    In-Seon Kim, Hae-Ryong Lim and Yong Ki Park Summary: Superconducting YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thin films were deposited on CeO/sub 2/ buffered Al/sub 2/O/sub 3/ (alumina and sapphire) substrates by pulsed laser deposition. Superconducting properties of the c-axis YBCO films on these substrates were greatly affected by the growth orientation of CeO/sub 2/ buffer layer. The critical temperature of YBCO film on alumina substrate was /spl sim/83 K. In the case of single crystal substrates, the critical temperature of YBCO thin film was /spl sim/89.5 K, and the critical current density was 1.5/spl times/10/sup 6/ A/cm/sup 2/ at 77 K.         Preparation of YBCO films on sapphire with CeO/sub 2/ deposited by ion beam sputtering    T. Goto, T. Kuji, You-Song Jiang, M. Moriya, K. Usami and T. Kobayashi Summary: Although sapphire has superior high frequency properties, an adequate buffer layer is required to form a high-Tc film. We deposited a CeO/sub 2/ buffer layer by ion beam sputtering in high oxygen pressure, and investigated the influence of the deposition conditions on the superconducting properties of YBa/sub 2/Cu/sub 3/O/sub 7-y/ (YBCO) films. CeO/sub 2/ films deposited at higher than 600/spl deg/C were c-axis oriented and YBCO films deposited on the top at 700/spl deg/C were also c-axis oriented. T/sub /spl alpha//(R=0)=89 K and J/sub c/>10/sup 6/A/cm/sup 2/ were obtained for a 120 nm thick YBCO film deposited on 50 nm thick CeO/sub 2/ layer. High oxygen pressure /spl sim/1 Pa is desirable. Grain boundary Josephson junctions were also successfully fabricated on bicrystal sapphire substrate. It was found that high pressure ion beam sputtering is a promising method for superconductive electron devices.         Preparation of a-axis oriented YBCO film on CeO/sub 2/ buffered sapphire substrate    You-Song Jiang, T. Kobayashi and T. Goto Summary: The purpose of this research is to control the orientations of the YBCO thin films which were deposited on the sapphire substrate with CeO/sub 2/ buffer layer that was fabricated using ion beam sputtering (IBS) method. The orientations of YBCO thin films were investigated using X-ray diffraction, and the dependence of the degree of a-axis orientation upon the substrate temperature and deposition rate was found. The a-axis oriented YBCO thin films were obtained at substrate temperature below 610/spl deg/C and deposition rate of more than 10 /spl Aring//min. High Tc of 85 K was realized by "temperature gradient" method. The surface of YBCO thin film is characterized by atomic force microscopy (AFM).         Ultrathin films of YBaCuO grown on YSZ substrates with a new buffer layer Nd-Cu-O    J. Gao, T.C. Chui and W.H. Tang Summary: YSZ is one of the most widely used substrates to grow oxide superconducting thin films. However, the large lattice mismatch and occurrence of intermediate layer often degrade the quality of grown films. We used a new buffer material, neodymium copper oxide (Nd/sub 2/CuO/sub 4/), to improve the quality of YBCO ultrathin films grown on YSZ. Good superconducting transitions have been obtained on these films with thickness 10-12 nanometers. Such a Nd/sub 2/CuO/sub 4/ layer has a stable crystal structure and behaves as an oxide semiconductor. At 77 K, its resistivity is /spl sim/40 times higher than that of PrBaCuO, which has been commonly used as buffer layer and barrier material. The lattice mismatch between Nd/sub 2/CuO/sub 4/ and YBCO is much smaller than that between YSZ and YBCO. It allows highly epitaxial growth of YBCO without forming big defects and the intermediate layer. Measurements by using XRD, rocking curve, and cross-sectional TEM indicated that the crystallinity of YBCO films grown on Nd/sub 2/CuO/sub 4/ buffer layer had been significantly improved. Besides, the smooth surface of Nd/sub 2/CuO/sub 4/ layer and buffered YBCO films are observed by SEM.         SrTiO/sub 3/ buffer layers on MgO and Si substrates for high-T/sub c/ technology    L. Mechin, Q. Meng, A.H. Sonnenberg and G.J. Gerritsma Summary: SrTiO/sub 3/ (STO) thin films have been sputtered on MgO [100] and on Si [100] substrates. On MgO the [100]-oriented STO buffer layers enabled the fabrication of high quality DyBa/sub 2/Cu/sub 3/O/sub 7-x/ (DBCO) films and ramp-type junctions (with I/sub c//spl times/R/sub n/ products in the order of 1 mV at 4 K) using exactly the same process as for single crystal STO substrates. On Si the fraction of [110]-oriented material in the STO films have been minimized to 2.5% by the optimization of the deposition conditions. Grain boundaries crossing the whole STO film and an amorphous layer between Si and STO could be observed. An Auger analysis revealed the presence of barium at the Si/STO interface that presumably diffused along the grain boundaries through STO to form barium silicate. By reducing both the DBCO deposition temperature and the STO thickness we could prevent this diffusion and improve the electrical properties. However rather poor crystalline quality and still non-satisfactory electrical characteristics were obtained (R/sub 300//R/sub 100//spl sim/1 and T/sub c/ (R=0) in the 40 60 K range). Overall these results suggest that, on MgO STO is a reliable buffer layer that enables the use of the technological processes handled on single crystal STO substrates. On Si the crystalline quality of the STO layers has to be improved in order to form an efficient diffusion barrier.         Al films as buffer layers for high-temperature superconducting thin films on amorphous substrates    S. Hontsu, M. Nakamori, A. Fujimaki, H. Tabata, J. Ishii and T. Kawai Summary: We have prepared c-axis oriented YBa/sub 2/Cu/sub 3/O/sub 7-y/ (YBCO) thin films on amorphous substrates, such as SiO/sub 2/ and soda potassium glass, by using Al(111) buffer layer. Before preparation of YBCO film, Al surface was oxidized at a substrate temperature of 590/spl deg/C under (O/sub 2/+O/sub 3/;8%) atmosphere of 1 mTorr. This AlO/sub x/ was in an amorphous state according to X-ray diffraction (XRD) and reflection high-energy electron diffraction (RHEED) measurements. YBCO films were formed on amorphous substrates with the AlO/sub x//Al layer using an ArF excimer laser deposition technique. The vacuum pressure and substrate temperature during deposition were typically 1 mTorr and 590/spl deg/C, respectively. XRD measurements indicate that all the YBCO films were predominantly oriented with the c-axis normal to the substrate surface. These results show that the AlO/sub x/ plays a role of buffer and seed layer which has periodic potential of atomic order corresponding to Al(111) plane. Critical temperature T/sub c(zero)/ of the c-axis oriented YBCO film on AlO/sub x//Al/glass substrate was 75 K. This technique can be applied to other oxide material such as ferroelectric and ferromagnetic materials and is very useful for applications.         Buffer layers and thallination of Tl-based superconductors on flexible metal substrates    P.A. Parilla, C.M. Carlson, Y.-T. Wang, R.N. Bhattacharya, R.D. Blaugher, D.S. Ginley, M. Paranthaman, A. Goyal, D.K. Christen and D.M. Kroeger Summary: Reported here is the development of textured buffer layers that are compatible with Tl-based superconductor (SC) films on metallic substrates. Crucial properties for the successful development of a suitable buffer layer are appropriate lattice match, chemical stability, and a high degree of texture. Buffer layer materials investigated include cerium oxide, strontium titanate (STO), lanthanum aluminate (LAO), and lanthanum nickel oxide (LNO) which were grown using a pulsed excimer 248 nm laser deposition system equipped with multitarget and controlled ambient capabilities. The influences of substrate temperature and ambient pressure and flow on buffer layer growth are analyzed via XRD and AFM characterization. Highly textured buffer layers have been fabricated including epitaxial LAO/LNO/CeO/sub 2//Ni RABiTS configurations. Also reported are the results of thallination of Ba-Ca-Cu-O precursors on single crystal and buffered substrates using a hybrid 2-zone furnace. The hybrid 2-zone combines the advantages of crucible and standard 2-zone thallination processes. High quality Tl-1223 films with J/sub cm//spl sim/6.0 MA/cm/sup 2/ (0 T, 5 K) and 4.6 MA/cm/sup 2/ (0 T, 76 K) have been produced using the hybrid method.         High J/sub c/'s in just-rolled Tl-1223/Ag tapes prepared using (Tl,Pb,Bi)-(Sr,Ba)-Ca-Cu-O compositions    D.Y. Jeong, H.K. Kim and M.H. Sohn Summary: The grain morphology, the changes in microstructure and J/sub c/ during the thermo-mechanical treatment, and the field dependence of J/sub c/ in Tl-1223/Ag tapes of Tl/sub 0.8/Pb/sub 0.2/Bi/sub 0.2/Sr/sub 1.6/Ba/sub 0.4/Ca/sub 2/Cu/sub 3/O/sub z/ and Tl/sub 0.8/Pb/sub 0.2/Bi/sub 0.2/Sr/sub 1.8/Ba/sub 0.2/Ca/sub 2.2/Cu/sub 3/O/sub z/ compositions were investigated, and then compared with each other. As a result, high J/sub c/'s near 25000 A/cm/sup 2/ at 77 K and 0 T were obtained in the latter composition, in which plate-like Tl-1223 grains are directionally aligned, at least in local regions. The high J/sub c/'s are attributed to enhanced grain-contact areas resulting from enhanced densification by a repetition of the TMT and the retarded decomposition of Tl-1223 phase in the latter composition. The strong field dependence of J/sub c/ indicates, however, that there still exist significant weak-links.         Superconducting (TlBi)/sub 0.9/Sr/sub 1.6/Ba/sub 0.4/Ca/sub 2/Cu/sub 3/Ag/sub 0.2/O/sub x/ films from electrodeposited precursors    R.N. Bhattacharya, P.A. Parilla, R.D. Blaugher, Z.F. Ren, W. Li, J.H. Wang, Y.T. Wang, A.M. Hermann, M. Paranthaman, A. Goyal, D.T. Verebelyi and D.K. Christen Summary: A low-cost electrodeposition (ED) method is reported for fabrication of high-temperature Tl-oxide-based superconductors. Recent studies on the development of biaxially textured ED films on single-crystal and rolling-assisted biaxially textured Ni substrates are presented. Pole-figure measurements of electrodeposited (Tl,Bi)-(Sr,Ba)-Ca-Cu-Ag-O (TBSBCCO) films, with thicknesses between 1-5 /spl mu/m, clearly show strong biaxial texturing. The rocking curve and phi scan of TBSBCCO on 300 /spl Aring/ Ag/LaAlO/sub 3/, show a full width half maximum (FWHM) of only 0.9/spl deg/ and 1.2/spl deg/, respectively, consistent with a very high-quality. Transport measurements for the ED films show J/sub c/ values up to 7.84/spl times/10/sup 5/ A/cm/sup 2/ at 77 K in zero magnetic field. The preliminary results of electrodeposited TBSBCCO film on CeO/sub 2//YSZ/CeO/sub 2/ on textured Ni showed primarily 1212 phase with a transport critical current density of 1.36/spl times/10/sup 5/ A/cm/sup 2/ at 77 K in zero field.         Synthesis and stability of HgRe1212 and HgRe1223 superconductors    P.V.P.S.S. Sastry and J. Schwartz Summary: Synthesis, phase stability, and superconducting properties of Re-doped Hg1212 and 1223 superconductors are reported. HgRe1212 and HgRe1223 were synthesized using a common synthesis protocol, using commercial BaCaCuO precursor powders with CaHgO/sub 2/ as the external Hg-source. Both starting composition and reaction temperature affect the phase stability and microstructure of the final product. The resulting superconducting phase in both Hg/sub 0.8/Re/sub 0.2/Ba/sub 2/Ca/sub 1/Cu/sub 2/O/sub y/ and Hg/sub 0.8/Re/sub 0.2/Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub y/ compositions was either HgRe1212 or HgRe1223, depending on the reaction temperature. The microstructure and superconducting properties of HgRe1212 and HgRe1223 samples, however, depended to a large extent on the starting composition. Both the HgRe1212 and HgRe1223 samples synthesized from a nominal composition of Hg/sub 0.8/Re/sub 0.2/Ba/sub 2/Ca/sub 1/Cu/sub 2/O/sub y/ had larger and aligned colonies of grains whereas the samples synthesized a nominal composition Hg/sub 0.8/Re/sub 0.2/Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub y/ had smaller and randomly oriented grains. Measured T/sub c/ values for HgRe1212 and Hg1223 phases were 124 K and 134 K, respectively. Both microstructure and magnetization hysteresis measurements suggest that HgRe1212 is a better candidate for applications.         Properties of (Hg,X)-1223 superconductors synthesized without using a glove box    H. Fujii, H. Kumakura and K. Togano Summary: We tried to synthesize (Hg,X)Ba/sub 2/Ca/sub n-1/Ca/sub n/O/sub y/ (MgX-12(n-1)n) superconductors for the substitution of various elements X without using a glove box. For X=V, Cr, Mn, Ge, Mo, Ru and Re, we succeeded in the formation of the phases of n=2, 1, 2, 1, 3, 3 and 3, respectively. It is suggested that the substitution of X for Hg is effective to stabilize the structures of HgX-12(n-1)n phases. Studies of microstructure and superconducting properties on HgMo- and HgRe-1223 revealed that the melt texturing was observed only for HgMo-1223 and that the T/sub c/'s of both samples were above 130 K, almost equal to that of Hg-1223. The irreversibility fields of HgMo- and HgRe-1223 were roughly estimated to be about 1.6 and 3 T at 90 K, respectively. These values are higher than that of Hg-1223. It is speculated that this enhancement is due to the improved coupling of Cu-O planes by the contraction of c-axis or the carrier doping by oxygen atoms introduced in the Hg-(O) layer.         Effect of deposition method on the uniformity of Hg-1212 thick films    J.C. Moore, M.I. Bisset, D.C. Knoll, J. Marin, S. Peterson, A.B. Roney, P.V.P.S.S. Sastry and J. Schwartz Summary: Hg-1212 thick films were fabricated using three methods to deposit the precursor film. It was found that the uniformity of the superconducting film is directly related to the uniformity of the precursor film. Significant thickness variations in the precursor film could, not be entirely eliminated by the subsequent melting and densification occurring during Hg-1212 phase formation. We conclude that deposition of a high quality precursor film is essential to produce a textured superconducting film with good coverage.         Coexisting ferromagnetism and superconductivity in hybrid rutheno-cuprate superconductors    J. Tallon, C. Bernhard, M. Bowden, P. Gilberd, T. Stoto and D. Pringle Summary: We report the observation of microscopically coexisting ferromagnetism and superconductivity in a hybrid ruthenocuprate RuSr/sub 2/GdCu/sub 2/O/sub 8/, with T/sub c//spl les/40 K. By means of various substituents it is established that the superconductivity originates in the CuO/sub 2/ planes and the ferromagnetism in the RuO/sub 2/ planes, as expected. Muon spin relaxation measurements show that the ferromagnetism, with Curie temperature T/sub M/=132 K, is microscopically uniform and originates from the entire sample bulk. This is probably the first confirmed example of uniform microscopic coexistence of superconductivity and atomic ferromagnetism. The material is determined from thermopower measurements to be an underdoped cuprate with a projected T/sub c,max/=90-100 K, typical of a two-layer cuprate. The oxygen isotope effect exponent of /spl alpha//sub Tc/=1.7 is the largest observed in the high-T/sub c/ cuprates. These materials are expected to provide a rich source of new physics and applications.         Oxide epitaxial lift-off of superconducting thin film devices    R.K. Hanson and M.M. Eddy Summary: Oxide epitaxial lift-off (OELO) has been successfully accomplished for thin single layer films of strontium titanate and multilayer films of strontium titanate and superconducting yttrium barium copper oxide (YBCO). The technique employs a YBCO release layer to separate the films from the growth substrate. The critical development was the use of a polymer support layer which retains sufficient compliance after curing to permit stress relaxation of the oxide film in such a way as to prevent cracking. Multilayer lift-off had the additional necessity of encapsulating the YBCO device layer. This was accomplished by alternately depositing layers of strontium titanate and YBCO. Layer thicknesses were optimized to compensate for the resulting through-thickness stress gradient which developed due to thermal expansion differences.         Control of surface electronic structure of high T/sub c/ superconducting films for Josephson junctions and electron spectroscopy    N. Terada, S. Kashiwaya, H. Takashima, S. Ueno, M. Koyanagi and H. Ihara Summary: A high-density atomic oxygen beam generated by thermal nonequilibrium high-temperature plasma has been used to control the surface nature of high-T/sub c/ superconducting YBCO epitaxial films and Cu-1234 ceramics. We report characterization of the electronic structure of the cleaned surfaces by in-situ ultraviolet and X-ray photoemission spectroscopy (UPS,XPS) and study of the relationship between the surface natures controlled and transport properties of multilayer structures fabricated over them. For both kinds of materials, exposure of the surface at a temperature of 300/spl sim/500/spl deg/C to the atomic oxygen beam yields highly ordered surface structures and a metallic feature with high electron density of states at the Fermi level. Owing to the improvement, the contact resistance between a cleaned YBCO[100] film and in-situ deposited gold, and a cleaned Cu-1234 and gold were found to be in the range of 10/sup -10//spl sim/10/sup -9/ and /spl sim/10/sup -8/ /spl Omega/.cm/sup 2/, respectively. The realization of an intrinsic Au/YBCO interface resulted in direct observation of the superconducting proximity effect in the gold layer from the YBCO. The control of the electrical connection also led to an enhancement of interlayer superconducting coupling in Pb/Ag/Au/YBCO[100] junctions. A positive correlation was found between the critical current density of the junction J/sub c/ and the height of photoelectron Fermi edge of YBCO, which corresponds to the electron density of states at the surface. A high J/sub c/, of the order of 10/sup 4/ A/cm/sup 2/, was achieved on the junctions fabricated on the YBCO surface with a Fermi edge height of 10% relative to that of Cu 3d UPS-signal.         Influence of the deposition rate on crystalline structure and cation disordering of YBCO thin films    Jeong Dae Suh, Gun Yong Sung and Kwang Yong Kang Summary: We have systematically investigated the superconducting properties of in-situ deposited YBCO thin films as a function of the substrate temperature in the range 650-800/spl deg/C and the deposition rate in the range 0.1-12.2 nm/s. It was found that the cubic structure of YBCO grows at low substrate temperatures and high deposition rates. Also, expansion of the c-lattice parameter and decrease of the critical temperature of YBCO thin films were observed with decreasing substrate temperature and increasing deposition rate, suggestive of cation disordering in the YBCO thin films. These results are explained by cation kinetics.         Dependence of critical temperature and resistivity of thin film Nb47wt%Ti on magnetron sputtering conditions    C.D. Hawes, L.D. Cooley and D.C. Larbalestier Summary: Niobium-titanium multilayers generally have depressed critical temperature, T/sub c/. In this paper the variation of T/sub c/ and resistivity of magnetron sputtered Nb47wt%Ti thin films is studied as a function of the cathode power and target usage. The data are compared with analyses by Auger and scanning electron microscopy. Films made using a new target have properties which are similar to those of bulk Nb47wt%Ti when high cathode power is used. The data indicate a transition in the morphology of the film as power increases, which affects the rate at which interstitial atoms are incorporated into the growing film. After the target lost /spl sim/50% of its mass and acquired strong surface relief, bulk properties could not be obtained, because deposition rates for a given cathode power were lower than before. A small Ti enrichment (3-5%) between the films and the target was found for both sets of films.         Optimization of RF- and DC-sputtered NbTiN films for integration with Nb-based SIS junctions    N.N. Iosad, B.D. Jackson, T.M. Klapwijk, S.N. Polyakov, P.N. Dmitirev and J.R. Gao Summary: NbTiN is one of the most promising materials for use in the tuning circuits of Nb-based SIS mixers for operating frequencies above the gap frequency of Nb (/spl ap/700 GHz). We examine the properties of NbTiN films obtained using an unbalanced sputtering source in both RF and DC operating regimes. It is found that the properties of NbTiN films are strongly affected by the total pressure of the sputtering process. Films obtained under lower pressures have higher compressive stresses and lower resistivities. The best NbTiN films are obtained by DC sputtering and have a transition temperature of 14.4 K, a resistivity of 90 /spl mu//spl Omega//spl middot/cm at 20 K, and a compressive stress of -1 GPa. Films with a resistivity of 110 /spl mu//spl Omega//spl middot/cm at 20 K and a compressive stress of -0.5 GPa have been successfully used as a stripline material for Nb/Al-AlO/sub x//Nb SIS junctions on fused quartz substrates.         Properties of DC magnetron sputtered Nb and NbN films for different source conditions    N.N. Iosad, T.M. Klapwijk, S.N. Polyakov, V.V. Roddatis, E.K. Kov'ev and P.N. Dmitriev Summary: We have compared the quality of Nb and NbN films obtained by DC magnetron sputtering from a new and a fully eroded Nb target. Since current superconducting electronic devices such as SIS mixers, RSFQ digital circuits and hot electron bolometers are produced by reactive sputtering, we are interested in optimum source operating conditions over the target lifetime. We find that stress-free Nb films can, at any state of the target, be obtained under the same Ar pressure and DC power applied to the sputtering source. We show that this approach also works for NbN reactive sputtering if the nitrogen flow rate is maintained proportional to the deposition rate of Nb. In both cases the zero-stress point shifts to lower cathode DC voltage as the target erodes. Additionally we find that the effectiveness of the magnetic trap of the magnetron influences the normal state resistivity of the NbN films.         Nb oxide thin film resistors    C.I. Wilson, C.R. Ellis, L.S. Salinas and A.W. Lichtenberger Summary: Recently Kerr and Pan have proposed development of integrated image separating mixer circuits. To realize the 50 and 100 ohm terminations required by these circuits, a 4.2 K thin film resistor technology is required. It is also desirable to implement each resistor with one or two "squares" of material so that they are electrically short. Existing commonly used Ti-Au based resistor technologies are limited to values well below 50 /spl Omega///spl square/. We are investigating a new Nb-oxide technology where the resistivity is controlled by varying the oxygen content of the sputtered films. Initial experiments using a DC magnetron gun with a Nb target proved difficult to control due to the changing deposition rate and electrical characteristics of the gun with target erosion. Greatly improved control was obtained with the use of a RF diode sputter arrangement and a 5" diameter target. As target voltage is decreased or oxygen partial pressure is increased, the deposited films become less metallic and more resistive. Films with ohms//spl square/ values ranging from five to 1,000 have been obtained with this technique while a partial pressure of oxygen on the order of 10/sup -3/ Pa is needed for 50 /spl Omega///spl square/ material. A valuable attribute of these resistive films is that the measured room and liquid He temperature resistivities are the same.         Deposition of c-oriented borocarbide thin films by laser ablation technique    M.R. Cimberle, C. Ferdeghini, G. Grassano, D. Marre, I. Pallecchi, M. Putti, A.S. Siri and F. Canepa Summary: Despite the long period of time elapsed since their discovery, intermetallic superconducting borocarbides in the form of thin films are rarely reported in the literature. In this paper we present our results on the growth of ErNi/sub 2/B/sub 2/C thin films by an ultra high vacuum laser ablation technique. The dependence of the film structure and properties on the deposition parameters has been studied and optimized. Strongly c-oriented superconducting films (rocking angle of 1/spl deg/) with a rather smooth surface have been obtained. Here we present the details of the deposition procedure as well as those of the structural, morphological, and electrical characterization. The feasibility of superconducting films with a tungsten buffer layer on MgO substrate has been studied successfully. Both buffer layers and bilayers have been characterized by X-ray reflectivity and atomic force microscopy.         Development of Nb-Ti-Ta ternary alloy multifilamentary superconducting wire    T. Shimada, K. Wada, S. Meguro, S. Murase, S. Nakayama, T. Orikasa, K. Makishima, K. Watanabe, K. Tsuchiya, A. Yamamoto, T. Nakamoto and T. Shintomi Summary: The superconducting wire with approximately 10 /spl mu/m diameter filaments of Nb-41 wt%Ti-28 wt%Ta alloy was fabricated from our standard production billet. Critical current densities and upper critical fields after various heat treatments were measured in the temperature range of 4.2 K to 1.6 K. Thermo-mechanical treatments for /spl alpha/-Ti precipitates were optimized to improve critical current densities. A 27-strand Rutherford type cable having a large keystone angle was trial-fabricated using the optimized-processed wires. The achieved J/sub c/s were 1383 A/mm/sup 2/ (10 T and 1.9 K) and 602 A/mm/sup 2/ (12 T and 1.9 K). The fabricated wire was proved to have high homogeneity and good workability.         Critical currents and pinning mechanisms in Chevrel-phase superconductors: materials science issues    M.O. Rikel Summary: Critical current densities and pinning mechanisms in lead (PMS) and tin (SMS) molybdenum sulfides are reviewed with the emphasis on materials science problems. In both compounds, pinning at grain boundaries is dominant only in fine-grained materials and in the low-field regime. In coarser grained materials, additional pinning behaviors (the maximum pinning force density F/sub p/ at the reduced field b/sub m/=0.4-0.55 and 0.7) are reproducibly observed and can be related to pinning at intragrain defects (planar defects, oxide precipitates, and point-like defects). The difference in the critical currents in PMS and SMS is discussed and related to the difference in the extent of stress-induced structural transformation at grain boundaries.         The upper critical field of the Chevrel phase superconductor lead-molybdenum-sulphide doped with gadolinium    N.R. Leigh, D.N. Zheng and D.P. Hampshire Summary: Chevrel phase superconductors with upper critical field values of up to 50 T, are candidate materials for the next generation of high field magnets. We have investigated the effect of doping lead-molybdenum-sulphide with the magnetic ion gadolinium to improve the critical parameters and the flux pinning in this material. Samples were prepared at 1500/spl deg/C to ensure the gadolinium was uniformly distributed throughout the material and then sintered using a hot isostatic press operating at a pressure of 2000 atmospheres. Calorimetric measurements have been completed In magnetic fields up to 15 T as a function of temperature. The temperature dependence of the upper critical field of these isotropic Chevrel phase materials are presented. Upper critical field values of more than 60 T have been determined for both doped and undoped samples. The calorimetric data reported here show that material with low levels of gadolinium doping offers the possibility of strong flux pinning and high critical current densities in high magnetic fields. In highly doped materials, the low critical current density and irreversibility fields found are probably due to a reduction in the fundamental properties and not poor grain boundaries.         Superconducting properties and critical current density of Nb-Ti/Ti multilayers    L.D. Cooley, C.D. Hawes, P.J. Lee and D.C. Larbalestier Summary: Multilayers of Nb47Ti superconductor (S) and titanium pins (N) have been made with a critical temperature T/sub c/ and an upper critical field H/sub c2/ approaching bulk values. There is no proximity effect suppression of T/sub c/ and H/sub c2/ for layer thickness d/sub S/=d/sub N/=10 nm, in contrast to the strong suppression for comparable multilayers made with Cu, Cu-alloy, or Nb pins. This may be because the proximity length of the Ti layers, /spl sim/10 nm, is less than or equal to their thickness. The critical current density J/sub c/ exhibits, multiple peaks in J/sub c/(H), which suggests that matching effects contribute to the overall pinning. J/sub c/ for 20 nm bilayers is comparable to that of Nb47Ti tapes, which have a higher number density of pins but a lower pin volume fraction. The weak proximity coupling suggests that much higher J/sub c/ can be obtained if smaller bilayer periods can be made with good adhesion. The results are compared to other Nb-Ti/Ti multilayer experiments, and stability limitations are also discussed.         Analysis and optimization of superconducting materials using the modified collective pinning theory    D. Rodrigues Jr. Summary: The experimental pinning forces of LTS materials were analyzed using the Modified Collective Pinning Theory (MCPT). This modified theory accounts for the elastic and plastic energies and deformations of the flux line lattice in the superconductors. Usually, collective pinning theories only account for the elastic deformation of the lattice. The analysis by MCPT enabled one to determine the amounts of elastic and plastic deformations of the flux line lattice in Nb/sub 3/Sn and Nb/sub 3/Al superconductors. The theoretical values for the coherence lengths were compared to the measured dimensions of the microstructures of defects in the materials. This analysis brought the possibilities to a better understanding of the transport behavior of these materials.         Flux pinning characteristics in ultrafine multifilamentary NbTi superconductors with different artificial pin materials    O. Miura, Y. Zhu, T. Okubo, D. Ito and S. Endo Summary: In order to improve and design critical current densities in commercial superconductors, the establishment of an artificial pinning center composite technique based on the flux pinning mechanism is desired. For that purpose, we studied the influence of different kinds of artificial pin materials (Nb, Nb-7.5wt.%Ta, Ta) on the flux pinning in multifilamentary NbTi superconductors. It was found that Nb pins act as the strongest pinners among them as predicted by difference of free energy between different kinds of superconductors estimated from the Ginzburg-Landau theory. As a result, the pinning scaling law holds true in a wide range of temperatures and magnetic fields. However, the contribution of artificial pins gradually decreased with reducing pin size. This is thought to be mainly caused by the degradation of upper critical field due to the proximity effect as well as the reduction in pin size.         Current sharing in the resistive region of composite superconductors    A. Rimikis, R. Kimmich and T. Schneider Summary: The current sharing region is an important factor in the specification of a superconducting composite. Therefore, the voltage-current characteristic of NbTi and Nb/sub 3/Sn superconductors with copper stabilizing matrix, as well as silver sheathed BSSCO-2223 are discussed under the aspect of current sharing and temperature effects.         Investigation of critical current distribution in composite superconductors    R. Kimmich, A. Rimikis and T. Schneider Summary: For the design of superconducting magnets, the E-field vs. current curve (E(I)-curve) of the composite superconductor is an important property. We studied a model which describes the E(I)-curve by means of a Gaussian distribution of local critical currents. Therefore, resistive measurements in magnetic fields up to B=15 T were performed on several niobium-titanium, niobium-tin conductors and Bi-2223-conductors. We calculated the critical current distribution by differentiating E(I) twice with respect to the current. For metallic superconductors we got only the lower portion of the distribution because of sample quenches. That means, no complete distribution could be seen, but only a fraction of the curve. We developed a new numerical method to estimate the parameters of these fragmented critical current distributions. The knowledge of the parameters enabled us to calculate the whole curves and to compare them with the results of the measurements. This comparison clearly showed that for NbTi and Nb/sub 3/Sn composite superconductors, which are not additionally stabilised, the quench of the sample occurs far below the mean critical current.         Magnetization measurements on LHC superconducting strands    S. Le Naour, L. Oberli, R. Wolf, R. Puzniak, A. Szewczyk, A. Wisniewski, H. Fikis, M. Foitl and H. Kirchmayr Summary: When using superconducting magnets in particle accelerators like the LHC, persistent currents in the superconductor often determine the field quality at injection, where the magnetic field is low. This paper describes magnetization measurements made on LHC cable strands at the Technical University of Vienna and the Institute of Physics of the Polish Academy of Sciences in collaboration with CERN. Measurements were performed at T=2 K and T=4.2 K on more than 50 strands of 7 different manufacturers with NbTi filament diameter between 5 and 7 micrometer. Two different measurement set-ups were used: vibrating sample magnetometer, with a sample length of about 8 mm, and an integrating coil magnetometer, with sample length of about 1 m. The two methods were compared by measuring the same sample. Low field evidence of proximity effect is discussed. Statistics like ratio of the width of the magnetization loop at 4.2 K and 2 K, and the initial slope dM/dB after cooldown are presented. Decrease of the magnetization with time, of the order of 2% per hour, was observed in some samples.         Synthesis of HgPb1223 superconductor    Y. Li, P.V.P.S.S. Sastry, D.C. Knoll, S.C. Peterson and J. Schwartz Summary: The synthesis and processing parameters that affect the phase purity and grain growth of Pb-doped Hg1223 were optimized. Samples were prepared from commercial BaCaCuO precursors using CaHgO/sub 2/ as the external Hg-source. Samples were quenched from high temperature at different stages of the reaction and their microstructures were investigated. The reaction and annealing conditions were optimized to improve the phase purity and microstructural homogeneity. The as-synthesized HgPb1223 samples were shown to be optimally doped and to exhibit T/sub c/ values in the range of 130-134 K. Post-annealing of the samples in flowing oxygen or argon at 300-400/spl deg/C did not improve T/sub c/ and deteriorated the magnetic hysteresis.         The magnetic field and temperature dependent transport critical current density of Hg-Pb-Bi-Ca-Cu-O ceramic compounds    T.L. Francavilla, H.R. Khan and V.M. Browning Summary: Mercury-based ceramic superconductors have been prepared by powder metallurgy, utilizing a technique of direct synthesis from the oxide powders. The tetragonal Hg-1223 phase was prepared and stabilized over a range of Pb and BiPb compositions. The most interesting material had an onset superconducting transition temperature of approximately 133 K. Critical current densities were obtained directly from transport measurements and indirectly from magnetization measurements, The transport critical current densities were orders of magnitude smaller than the intra-grain critical current densities. The data suggest that the transport critical current is limited by weak coupling between the grains, and that the intra-grain critical current densities deteriorate rapidly above 20 K.         Critical current density of both F and Cl doped filamentary Hg1223 superconductors    T. Goto, T. Shimizu and K. Watanabe Summary: The effect of both F and Cl doping on the transport critical current density (J/sub c/) of the filamentary Hg1223 superconductors was examined to enhance the reproducibility of high J/sub c/. A filamentary precursor Ba/sub 2/Ca/sub 2/Cu/sub 3/Re/sub 0.2/O/sub x/ was fabricated using a solution spinning method and partially melted in an evacuated quartz tube with a pellet of Hg/sub 0.8/Ba/sub 1.8/Ca/sub 2/Cu/sub 3/Re/sub 0.2/(BaF/sub 2/)/sub 0.2/(CuCl)/sub 0.03/. The addition of BaF/sub 2/ and CuCl as a doping vapor source enhanced the reproducibility and stability of the high J/sub c/ value at 77 K and 0 T for the filamentary sample owing to the homogeneous fine grain texture. Field dependence of the J/sub c/ for the filamentary sample was strongly dependent on the post-annealing condition. Although the J/sub c/ value for the as-reacted sample and the sample post-annealed in flowing O/sub 2/ decreased rapidly by applying the field less than 0.5 T, high J/sub c/ value exceeding 10/sup 3/ A/cm/sup 2/ was maintained at 77 K in a field of 10 T by post-annealing in flowing Ar.         Application of hot isostatic pressing in the synthesis of Hg-based superconductors    G. Celotti, A. Tampieri and D. Rinaldi Summary: The preparation of Hg(Pb)BCCO (1201) and (1223) phases was performed by hot-isostatic-pressing (HIP) using simple oxides as precursors canned in silver tube. In the case of Hg/sub 0.8/Pb/sub 0.2/Ba/sub 2/CuO/sub 4+/spl delta// the preparation, carried out at 800/spl deg/C and 0.15 GPa for 5 hrs, yielded a single phase bulk sample. On the other hand the preparation of Hg/sub 0.8/Pb/sub 0.2/Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub 8+/spl delta// at 820/spl deg/C and 0.15 GPa for 5 hrs allowed the attainment of a high volume fraction of 1223 phase. Magnetic susceptibility of 1201 phase showed an intragranular transition around 90 K; in the case of 1223 the value was /spl ap/128 K followed by a broadened intergranular transition. These results show the feasibility of 1201 phase synthesis with high purity and of 1223 phase in large amount (>80%). The possibility to obtain the samples directly in form of dense bulks (with density /spl ges/85%) stresses the importance of this technique in relation to the intrinsic low thermal stability of the superconducting phases.         Preparation of highly textured Tl(1223)/Ag superconducting tapes    E. Bellingeri, R.E. Gladyshevskii, F. Marti and R. Flukiger Summary: High-purity Tl(1223) ceramics have been produced by a reaction under high isostatic gas pressure (50 bar). A new method of synthesis consisting in a two-step reaction involving substantial melting at very high temperature (up to 1100/spl deg/C) produced well-shaped plate-like grains. An electrophoretic deposition (ED) technique then was used to produce uniform layers of controlled thickness on Ag ribbons. By alternating ED and uniaxial pressing, a high degree of c-axis texture, comparable with the one generally observed for Bi-based tapes, was obtained thanks to the appropriate grain morphology of the ceramic that had been synthesized by the two-step reaction. After annealing, critical current densities up to 11,000 A/cm/sup 2/ were reached. Despite the fact that the transport properties are still dominated by weak links, some important obstacles-in particular difficulties in phase formation and in texturing-have been overcome, indicating that Tl(1223) remains a promising material for large scale high-T/sub c/ superconductor applications.         Optimization of phase formation and microstructure in Tl-1223 thick films    J.C. Moore, M.J. Naylor and C.R.M. Grovenor Summary: Tl-1223 films have been fabricated using spray pyrolysis on silver and zirconia substrates. We have investigated the effect of a Tl-2212/TlF source powder and observed a significant increase in melting and, consequently, a reduction of around 20/spl deg/C in the optimum reaction temperature and increased grain growth. We have found that the effect of the fluorine is greatest in the presence of silver. We have also observed that films grown on polycrystalline silver tape have several preferred in-plane orientations.         Tl-based films grown on silver tape substrates    C. Falcony, M. Jergel, A. Morales, M. Garcia, R.T. Hernandez, A. De Ita, J.G. Cabanas-Moreno, J. Palacios G. and R. Martinez Summary: The Tl-based superconductors belong to potential candidates for high-current and high-field applications. It is therefore of importance to prepare them in the shape of tapes and wires. It seems that silver tape is a very convenient material having suitable mechanical properties as well as chemical compatibility with superconducting films deposited and grown on top of them. In our case, Tl-based films were grown using a two-step procedure. First, the Ba-Ca-Cu precursors were deposited on a commercial silver tape from an aerosol, and then the precursors were thallinated in a closed crucible with a source of Tl-oxide in the form of a crude pellet. Results are reported on superconducting samples consisting so far of 2212, 2223 and 1223 phase mixtures. SEM observations reveal the growth of plate-like grains. Metallurgical processing of silver tape is underway to obtain a cubic texturized substrate which should help to improve transport properties of the grown films.         Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x//Ag multilayer tapes with J/sub c/ (4.2 K, 10 T) of 500,000 A/cm/sup 2/ by using PAIR process    H. Kitaguchi, H. Kumakura, K. Togano, H. Miao, T. Hasegawa and T. Koizumi Summary: We developed PAIR (pre-annealing and intermediate rolling) process, which is a fabrication procedure for Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/(Bi-2212)/Ag composite tapes, in order to improve their superconducting properties. PAIR process is the combination of pre-annealing (PA) and subsequent intermediate rolling (IR) processes and is performed prior to a melt-solidification process. By performing the PAIR process, Bi-2212 grain alignment and intergrain connectivity are much improved and a large J/sub c/ enhancement can be expected for Bi-2212/Ag conductors. We study the effects of pre-annealing and intermediate rolling processes on microstructure and superconducting properties of the Bi-2212/Ag multilayer tapes fabricated by the oxide-painting and lamination method. The results show that J/sub c/ has been increased strongly by performing pre-annealing at 1133 K in oxygen (1 atm) and intermediate rolling with 25% deformation. PAIR processed samples have transport J/sub c/-oxide (4.2 K, 10 T) exceeding 5.0/spl times/10/sup 5/ A/cm/sup 2/. Whereas J/sub c/-oxide for the samples melt-solidified without PAIR process remains 3.0/spl times/10/sup 5/ A/cm/sup 2/. The enhancement of J/sub c/ is assigned to the microstructure with high grain alignment and uniformity, as well as the improvement in grain connectivity achieved by the PAIR process.         Isothermal melt processing of Bi-2212 tapes    T.C. Holesinger, P.S. Baldonado, Nghia Van Vo, Weiming Dai, K.R. Marken Jr. and Seungok Hong Summary: Isothermal melt processing (IMP) has been used to produce phase-pure, high critical current density (J/sub c/) Bi-2212 tapes at temperatures as low as 780/spl deg/C, Bi-2212 tapes processed by IMP have yielded J/sub c/ values up to 250 kA/cm/sup 2/ (I/sub c/=345 A) at liquid helium temperatures. Small test coils have been produced with J/sub c/ values up to 150 kA/cm/sup 2/. The effects of the oxidation rate, processing temperature, and time spent in the partial melt on the superconducting properties and microstructure were investigated. Optimal superconducting properties result from the interplay of these parameters such that the grain size of the Bi-2212 phase in the polycrystalline core is allowed to coarsen and align itself with the silver sheath to form a well connected superconductor. Deviations from optimal conditions result in either too little coarsening to form a well aligned structure or instabilities in the coarsening process that lead to the formation of large secondary phases which disrupt connectivity.         Influence of Ag substrates on grain alignment and critical current density of Bi-2212 tape conductors    H. Kumakura, H. Kitaguchi, K. Togano, T. Muroga, J. Sato and M. Okada Summary: We investigated the influence of Ag substrate on the microstructure and J/sub c/ values of dip-coated Bi-2212/Ag tapes. The grain alignment of Bi-2212 in the oxide/Ag interface was much higher than that in the free surface of oxide. J/sub c/ increases with increasing oxide/Ag interface area and with decreasing oxide layer thickness, while J/sub c/ was almost independent of the free surface area. The smoothness of the Ag substrate is also an important factor. Micrometer-size roughness of the Ag substrate results in a decrease of Bi-2212 grain alignment and therefore J/sub c/. Addition of alloying elements to the Ag also degrades the grain alignment of Bi-2212 and decreased J/sub c/. Cold rolling before the heat treatment improved the grain alignment and enhanced J/sub c/.         Continuous processing of AgMg-sheathed Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/ tapes    Q.Y. Hu, Y. Viouchkov, H.W. Weijers and J. Schwartz Summary: The critical current of the tapes prepared using continuous processing is significantly enhanced and processing time reduced, compared with that of traditional processing. The effect of conductor pulling speed on the microstructure, phase purity and therefore critical current of the tape is investigated using ESEM, XRD and DC transport measurements.         Microstructural and magneto-optical characterization of high J/sub c/ BSCCO-2223/Ag tapes    J. Jiang, T.C. Shields, J.S. Abell, A. Polyanskii, D.M. Feldmann and D.C. Larbalestier Summary: The phase and microstructural evolution, and critical current density of (Bi,Pb)-2223/Ag tapes prepared from a variety of precursor powders have been investigated. Correlations between the reaction kinetics, the microstructure and the critical current density are developed. A mechanism for the BSCCO-2223 phase formation depending on the precursor phase assemblage is presented. Magneto-optical imaging shows that high J/sub c/ samples (J/sub c/ (77 K, 0 T) /spl sim/35 kA/cm/sup 2/) are well connected longitudinally but strongly sub-divided by longitudinal cracks. The performance of BSCCO-2223 tapes should be further improved by controlling the liquid phase to better heal the cracks.         Materials analysis of yttrium-barium-copper-oxide by micro-Raman spectroscopy and optical microscopy    J.M. Long, T.R. Finlayson and T.P. Mernagh Summary: Optical microscopy has proven to be a useful technique for obtaining general, qualitative information from the entire surface of YBa/sub 2/Cu/sub 3/O/sub 7-x/ samples. Micro-Raman spectroscopy is well suited for routine microstructural analysis of YBCO superconductors. We demonstrate the complementary use of both techniques for the analysis of polycrystalline YBCO. Observed colors of polarisation on YBCO were correlated with information provided by Raman spectroscopy on individual grains to deduce microstructural characteristics across the whole surface of a sample.         Direct observation of vortex lattice melting in Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// single crystals    S.J. Bending, A. Oral, J.R. Clem, I.I. Kaya, S. Ooi, T. Tamegai and M. Henini Summary: Scanning Hall probe microscopy has been used to investigate the melting of the vortex solid in Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// single crystals. After waiting several minutes for fluctuations to die away, a flux solid with good six-fold order is observed below the melting line. Incommensurability effects lead to pronounced rotations of the solid as the field is varied. The peak-to-valley corrugation of the vortex lattice drops abruptly and discontinuously to zero at the melting line, consistent with a first order transition. Fits of a pancake vortex model to the data yield a Lindemann parameter C/sub L//spl sim/0.19 in fair agreement with other estimates. There is also a clear indication of softening of the solid at very low fields, though we find no direct evidence for re-entrant melting.         Transport current distribution in (Bi,Pb)-2223/Ag tapes    J. Herrmann, N. Savvides, K.-H. Muller, R. Zhao, G.D. McCaughey, F.A. Darmann and M.H. Apperley Summary: We have measured the local distribution of the magnetic field component H/sub x/(x) perpendicular to the plane of (Bi,Pb)-2223/Ag tape conductors carrying transport currents at T=77 K using scanning Hall probe magnetometry. The sheet current density distribution J/sub y/(x) across the tape width was determined via a magnetic inversion scheme based on a Fourier transform/spatial filtering method. With increasing current, dramatic changes in J/sub y/(x) clearly define a characteristic current I* which marks the onset of homogeneous distribution of additional current over the entire cross section of the superconductor and corresponds to the intrinsic critical current in the context of the critical state model. The behaviour of a single-filament tape with a slowly varying ac transport current flowing in it is found to follow closely the predictions of the critical state model. For multifilament tapes, magnetic coupling between neighboring filaments results in a current distribution corresponding to an "effective" large individual filament.         Flux pinning enhancement in Ag-clad Bi-2212 wires by reactive doping with barium peroxide    U.P. Trociewitz, P.V.P.S.S. Sastry, P.R. Sahm and J. Schwartz Summary: Reactive additions of barium peroxide to Bi-2212 are shown to create homogeneously distributed second phases and enhance flux pinning properties. Changes in the melting characteristics caused by the addition also influence the texture of melt-processed Bi-2212 tapes. Heat treatment processes were adjusted corresponding to the Ba content to optimize the critical current densities in high magnetic fields. Results of investigations on microstructural, magnetization, and transport properties were correlated with flux pinning characteristics. Significant improvements in the field dependence of the superconducting properties of Bi-2212 at temperatures between 4.2-10 K were demonstrated.         The influence of high Pb doping on flux pinning and phase formation in bulk and tapes of Bi/sub 2.2-x/Pb/sub x/Sr/sub 1.8/CaCu/sub 2/O/sub 8+/spl delta//    A. Crossley, Y.H. Li, A.D. Caplin and J.L. MacManus-Driscoll Summary: The effect of oxygen partial pressure on Pb doping in Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// (Bi-2212) and its influence on flux pinning in bulk and tape materials has been investigated. Oxygen partial pressure was controlled precisely using a coulometric titration system. Bulk Bi/sub 2.2-x/Pb/sub x/SrCaCu/sub 2/O/sub 8+/spl delta// ((Bi,Pb)-2212) was annealed just above the (Bi,Pb)-2212 stability line in order to maximise the level of Pb doping. Screen-printed (Bi,Pb)-2212 tapes were melt-processed using a combination of isothermal and isobaric steps. In the bulk material the effect of Pb-doping on defect formation and intra-granular critical current density (J/sub c/) was investigated, and in the tapes the influence of Pb on (Bi,Pb)-2212 grain formation and J/sub c/ was studied. Pb solubility was found to increase with decreasing oxygen partial pressure (pO/sub 2/) and Pb levels of up to x=0.6 for Bi/sub 2.2-x/Pb/sub x/Sr/sub 1.8/CaCu/sub 2/O/sub 8+/spl delta// were incorporated at low pO/sub 2/ in both bulk and tape samples. The bulk samples showed nanoscale precipitates of (Bi,Pb)-2212 embedded in the (Bi,Pb)-2212 matrix. In the melt processed tapes, the high Pb levels led to reduced grain sizes and poorer texture. J/sub c/ values were not enhanced through incorporation of high levels of Pb.         Effects of overpressure processing on porosity in Ag-sheathed Bi-2212 multifilamentary tapes with various geometries    J.L. Reeves, E.E. Hellstrom, V. Irizarry and B. Lehndorff Summary: In long lengths of Bi-2212 tapes and wires, gases such as CO/sub 2/ and H/sub 2/O can cause bubbling of the Ag-sheath and porosity in the superconducting core. Applying a pre-processing step, which consists of vacuum annealing and annealing at 835/spl deg/C in 100% O/sub 2/ (VA+835), eliminates H/sub 2/O and reduces CO/sub 2/ that evolves during heating. To also counteract porosity, an overpressure heat treatment was utilized. Air was compressed to 5 atm total pressure (P/sub total/) while keeping pO/sub 2/ fixed at 1 atm. Thickness variations were measured for a number of variables: with and without VA+835; P/sub total/ 1 or 5 atm; and sample geometry such as round wires and rectangular tapes with different silver wall thickness. Light micrographs and SEM images show thin-walled monocore and multifilamentary tapes bubble unless they are pre-processed. The size and shape of pores in thick and thin multifilaments changes with overpressure processing. Microstructures with smaller and more uniformly distributed pores correlate with higher critical current values.         Nondestructive magneto-optical characterization of natural and artificial defects on 3" HTSC wafers at liquid nitrogen temperature    J. Eisenmenger, J. Schiessling, U. Bolz, B.-U. Runge, P. Leiderer, M. Lorenz, H. Hochmuth, M. Wallenhorst and H. Dotsch Summary: Double-sided 3" HTSC wafers were characterized by the magneto-optic technique. The presented apparatus allows a nondestructive and fast detection of local and extended inhomogeneities in the critical current density with high lateral resolution in the micrometer range. Additional gold-layers on the HTSC wafers, as they are sometimes used for the device production, do not influence the characterization result. The high sensitivity of the presented apparatus allows even the detection of local defects at higher temperature (77 K) where contrasts in the critical current are weaker and the magneto-optical characterization of HTSC thin films is much more difficult than at lower temperatures. So the apparatus can be used even under conditions where cooling with liquid helium or closed-cycle refrigerators is not available. The sensitivity was tested on natural and artificial defects, the latter being prepared by means of a focused laser beam.         Defect visualization in large area YBCO thin films by magneto-optical scanning technique    M. Kuhn, B. Schey, W. Biegel, B. Stritzker, J. Eisenmenger, P. Leiderer, B. Heismann, H.-P. Kramer and H.-W. Neumuller Summary: Flux penetration in large area YBCO thin films has been studied by a magneto-optical scanning technique. With a new apparatus HTS films as large as 20 cm/spl times/20 cm can be investigated by scanning the films through an inhomogeneous magnetic field. The apparatus has been built to realize an effective homogeneity control of the electrical properties of large area HTS thin films used for device fabrication. Magnetic flux penetration into YBCO thin films of different sizes and with intrinsic defects as well as artificial ones have been studied at 50 K. Magneto-optical measurements are compared with optical microscopy (OM) and inductive j/sub c/-characterizations. A correlation between the kind of defect and its influence on the electrical properties has been studied with regard to device applications, YBCO films structured especially for high current applications were investigated magneto-optically. These results will be compared to optical photographs of the quenching process caused by currents I>I/sub c/.         Influence of growth temperature and composition on structural disorder in YBCO thin films    G. Gibson, R.G. Humphreys, L.F. Cohen and J.L. MacManus-Driscoll Summary: Structural disorder has been measured using Raman spectroscopy for a series of films, which were grown by e-beam co-evaporation. The growth temperature and the cation stoichiometry of YBCO are essential parameters controlling the formation of structural disorder. Higher growth temperatures and higher Y fluxes produced more perfectly ordered films. Less spatial variation occurs in films with lower amounts of structural disorder.         Synchrotron X-ray studies of ultra-high-quality crystalline YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// in submicron thick films    W.J. Lin, D. Hatton, F. Baudenbacher and J. Santiso Summary: The crystal structure of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin film grown on SrTiO/sub 3/ substrate was studied by high-resolution X-ray scattering using synchrotron radiation. The films were found to consist of two major components: mosaic aligned grains and an ultra-high-quality single-crystal film. The scattering of the former component gave the normal diffraction pattern and its coherent grain size was determined, by fitting the Bragg reflection profiles, to be 2500 /spl Aring/ (horizontal) and 100 /spl Aring/ (vertical). The signature of the ultra-high-quality film was only observed in low index Bragg reflections. From analysis of the peak profiles, the coherent length of this component was found to be tens of microns (horizontal) and 1800 /spl Aring/ (vertical, the entire film thickness). An exponential strain field was found close to the interface which causes asymmetry in the /spl theta/-2/spl theta/ direction. We also found that the scattering intensity of this single crystal film was affected by the correlated roughnesses on the lattice planes, which replicate from the roughness of the substrate surface during growth. The Debye-Waller like roughness factor quickly diminishes the reflectivity as the diffraction angle (2/spl theta/) increases, which prevents the observation of the ultra-high-quality film at high angle Bragg reflections. Furthermore, our results indicate that 95% of the film volume is occupied by this excellent single-crystal film. It is clear that the superconducting properties of the sample will reflect this high quality film, rather than the 5% mosaic grains. These observations may help to account for the enhanced transport properties of thin film compared to their bulk counterparts.         Improved structural properties and surface morphology of Nd/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub 7-/spl delta// thin films deposited by d.c. magnetron sputtering    M. Salluzzo, I. Maggio-Aprile and O. Fischer Summary: We report the fabrication of very smooth NdBCO thin films deposited by d.c. magnetron sputtering using Nd rich target (EDX composition Nd/sub 1.12/Ba/sub 1.88/Cu/sub 3/O/sub 7-/spl delta//). Films characterized by critical temperature (R=0) higher than 90 K and maximum roughness lower than 2-3 nm on large areas are routinely obtained on SrTiO/sub 3/ non-vicinal substrates. STM studies performed in situ in UHV environment, show a 2D nucleation mechanism of the growth preserved up to a thickness higher than 100 nm. This is in contrast to the common observation of screw dislocations starting from 10-12 nm in c-axis ReBCO thin films, that gives rise to an increase of the roughness with thickness. We compare the growth modes, the superconducting, and the structural properties of our NdBCO thin films deposited by d.c. magnetron sputtering from stoichiometric and Nd-rich targets, on different kind of substrates. The experimental results are discussed in the framework of the role of Nd/Ba substitution in the properties of Nd/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub 7-/spl delta// thin films.         Melt processing of Bi-2212 on MgO and MgO-buffered substrates    M.J. Naylor and C.R.M. Grovenor Summary: Bi-2212 thick films have been prepared by full and partial melt processing to investigate the suitability of MgO substrates in polycrystalline, single crystal and buffer layer formats. There is a marked difference in microstructural and electrical properties between thick films on polycrystalline and single crystal MgO substrates. This is attributed to the degree of interaction between the liquid phase and substrate during melting. The thickness of films on single crystal MgO substrates is an important consideration in the optimization of the superconducting transport properties.         Effects of Pb doping on the microstructure and superconductivity of bulk BSCCO 2212    A.K.M. Alamgir, H. Yamada, N. Harada, K. Osaki and N. Tada Summary: BSCCO 2212 suffers from intrinsic weak flux pinning above /spl sim/20 K. From the view point of practical applications, it is particularly important to expand the irreversible regime up to considerably higher temperatures. BSCCO 2212 (molar ratio Bi:Pb:Sr:Ca:Cu:O=2-x:x:2:1:2) bulk samples have been synthesized using partial-melt processing in air with Pb contents x up to 0.8. Pb doping has been shown to reduce the melting temperature as well as improve the irreversibility field, X-ray diffraction and scanning electron microscopy along with superconducting property measurement were carried out to investigate the phase evolution and microstructure. Melt texturing showed considerably large plate-like grains with enhanced 001 reflection peaks. Effects of the Pb doping on the melt processing and superconductivity as a function of temperature and magnetic field will be discussed.         Structures and superconducting properties of Bi-2212 oxide cylinders prepared by the dip-coating and subsequent diffusion reaction    Y. Yamada, K. Itoh, K. Wada and K. Tachikawa Summary: Bi-2212 oxide superconductors have been synthesized by the diffusion reaction between a high melting point Bi-free oxide substrate and a low melting point Bi-based oxide coating layer. The substrate is composed of Sr-Ca-Cu oxides with atom I/sub c/ ratio of 2:1:2-3.5, and sintered into cylindrical rods and tubes. The coating layer is composed of the Bi-Cu eutectic oxide with a small amount of Ag addition, and coated around the substrate by dipping into the molten Bi-Cu oxide at 790/spl deg/C. The heat treatment is performed to produce Bi-2212 diffusion layer at 810-870/spl deg/C in air. The Bi-2212 diffusion layer, 100-150 /spl mu/m in thickness, shows a high density and oriented structure with plate-like grains. The maximum transport I/sub c/ and J/sub c/ of the diffusion layer exceed 300 A and 25000 A/cm/sup 2/ at 4.2 K under self-field, respectively. Post annealing in argon gas atmosphere improves T/sub c/ and J/sub c/ at higher temperature of the specimen. Present Bi-2212 oxide cylinders with large transport I/sub c/ and J/sub c/ seem to be promising as current leads and magnetic shields. The dip-coating process is more convenient for the practical fabrication of Bi-2212 oxide cylinders in comparison with the conventional slurry-coating process.         Modification of bulk properties of Bi/sub 1.8/Pb/sub 0.33/Sr/sub 1.87/Ca/sub 2/Cu/sub 3/O/sub y/ tapes by means of ion induced surface trenches    E. Mezzetti, E. Crescio, R. Gerbaldo, G. Ghigo, L. Gozzelino, B. Minetti, L. Gherardi, L. Martini, G. Cuttone and A. Rovelli Summary: This paper demonstrates the possibility to enhance predictably the behavior of the superconducting properties in a bulk material, by introducing linearly correlated defects within a surface layer. Columnar defects, having a depth of about 5% of the total thickness of the sample, were created on Ag/BSCCO-2223 tapes by means of 0.25 GeV Au ions at different fluences, with a dose equivalent field B/sub /spl phi// ranging from 1 T to 5 T. The implantation depth was about 15% of the total thickness of the sample. The shape and position of the irreversibility lines were deeply modified. The vortex dynamics, as investigated by a.c. susceptometry in d.c. magnetic field, exhibits features characteristics of Bose-glass like localization in a range of field between the onset of the localized phase and the dose equivalent field. From all the experimental data it emerges that the strategy of creating surface trenches for vortices is always largely effective in this range of magnetic fields.         Microstructure and critical currents in AgMg-sheathed multifilamentary Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/ tapes    Q.Y. Hu, P.V.P.S.S. Sastry, U.P. Trociewitz and J. Schwartz Summary: For the Ag-sheathed Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/ tapes, the high Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/ phase purity with an appropriate oxygen concentration and excellent grain alignment are responsible for high critical currents. Many fabrication parameters influence the Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/ phase content and microstructure of the tapes, which have been investigated by many researchers. In this paper, we present results of AgMg-sheathed Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/ heat treatment optimization and characterization. With the help of physical analytical methods such as ESEM, and XRD, the melt temperature is related to the transport measurements.         Study of superconducting to normal transition propagation in BSCCO2212 fibers    L. Garcia-Tabares, J. Calero, P. Abramian, F. Toral, A. Grau, L.A. Angurel and J.C. Diez Summary: This paper describes and analyzes the transition process to the normal state in BSCCO 2212 fibers grown using a LFZ process. To study this transition a specific installation was developed allowing to test and measure fibers under pulsed operation. The origin and the propagation mechanism of the transition have been analyzed, and models to predict the evolution of magnitudes such as the resistance or the temperature are proposed and verified with experimental measurements.         Reaction mechanism and microstructure of PAIR (per-annealing and intermediate rolling) processed Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x//Ag tapes    T. Hasegawa, T. Koizumi, Y. Aoki, H. Kitaguchi, H. Miao, H. Kumakura and K. Togano Summary: The effects of the PAIR process on the chemical reaction during partial melting and solidification were analyzed. There was no significant difference in the partial melting behavior detected by thermal analysis between PAIR processed and control samples. However, the HT-XRD and SEM analyses indicated that, in the samples processed by the PAIR technique, the (CaSr)CuO/sub 2/ crystals did not grow at the surface of the liquid phase but segregated as small particles in the well aligned superconducting layers. This can be explained by the high packing density in the PAIR processed tapes, which resulted in the formation of a uniform liquid phase and ideal solidification.         Stoichiometric variations of Bi 2212 electrophoretically deposited thick films    B.R. Balmer, C.R.M. Grovenor and R. Riddle Summary: Thick films of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ have been manufactured from a variety of starting powders. The prime objective of this study is to keep the density of large secondary phases to a minimum whilst not disturbing the processability of the superconductor. This work focuses on changes in source powder composition. We have found that very small changes in stoichiometry can affect the melting behaviour and J/sub c/ of the films, and the density of alkaline earth cuprate phases. It was found that powder sold as "partially reacted" (annealed at 800/spl deg/C) was best, and that using this production route, powder with a slight deficiency in either Ca or Cu gave the highest J/sub c/ values, exceeding 8000 A cm/sup -2/, in self-field at 77 K.         Inhomogeneous distribution of flux pinning strength and its effect on irreversibility line and vortex glass-liquid transition line in Bi-2212 tapes    M. Kiuchi, T. Matsushita, Y. Nakayama and N. Takase Summary: The irreversibility line and the vortex glass-liquid transition line under a magnetic field parallel to the c-axis are investigated for silver-sheathed and dip-coated Bi-2212 tape wires. It is found that the two characteristic lines for silver-sheathed tape is well explained by the flux creep-flow model assuming the distribution of pinning strength with a single peak. On the other hand, general agreements are obtained for these characteristic lines and the critical current density between experiments and theory only when two peaks are assumed in the distribution of flux pinning strength for the dip-coated tape. The causative structure in the dip-coated tape for the peak at small strength in the distribution is discussed.         Microstructure and properties of Bi-Sr-Ca-Cu-O with additions of nanometer-scale alumina    K.C. Goretta, M.M. Cuber, L.R. Feng, B.L. Fisher, M. Jiang, M.T. Lanagan, U. Balachandran, Y. Xu and M. Xu Summary: Al/sub 2/O/sub 3/ particles /spl ap/30 nm in size were added to Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ in a 1:4 molar ratio. For comparison, 0.3- and /spl ap/3-/spl mu/m Al/sub 2/O/sub 3/ particles were added to separate batches. All of the materials were partial-melt processed. The Al/sub 2/O/sub 3/ reacted during melting to form stable compounds, primarily of approximate composition (Sr,Ca)/sub 2/AlO/sub 4/. All additions caused slight decreases in the T/sub c/ and melting point of the Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/. The submicrometer Al/sub 2/O/sub 3/ additions induced large expansions in magnetic-hysteresis width at 6 K. Electron microscopy examination strongly suggested that the hysteresis expansion was related to alloying of the Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ matrix rather than to pinning by volume defects.         Near-net-shape fabrication of continuous Ag-clad Bi-based superconductors    M.T. Lanagan, K.C. Goretta, D.K. Walter, R.B. Poeppel, R. Troendly, M.J. McNallan and S. Danyluk Summary: We have developed a near-net-shape process for Ag-clad Bi-2212 superconductors. This alternative to the powder-in-tube process offers the advantages of nearly continuous processing, minimization of processing steps, reasonable ability to control the Bi-2212/Ag ratio, and early development of favorable texture of the Bi-2212 grains. The powder is rolled into an Ag channel, a cap is applied, and the assembly is lightly rolled. To minimize distortion during heat treatment, it is especially important that the Bi-2212 powder be nearly free of volatile species such as carbon. A vacuum-calcination process was developed to control CO/sub 2/ evolution during heating. Superconducting properties are discussed.         A new symmetrical arrangement of tape-shaped multifilaments for Bi-2212/Ag round-shaped wire    M. Okada, K. Tanaka, T. Wakuda, K. Ohata, J. Sato, H. Kumakura, T. Kiyoshi, H. Kitaguchi, K. Togano and H. Wada Summary: A new Bi-2212/Ag round-shaped wire with tape-shaped multifilaments has been successfully developed. The wire includes 126-960 tape-shaped filaments with triple rotation symmetry, having a good crystal alignment in each filament. We refer to the new wire as ROSATwire, (ROtation-Symmetric Arranged Tape-in-tube wire). Since the ROSATwire structure yields complete symmetrical arrangement of the tape-shaped filaments, it eliminates the need for a rolling machine, but allows us to use a drawing or extrusion machine. We found that the present wire fabrication process markedly improves not only productivity and lowers cost, but also enhances the transport J/sub c/ of the Bi-21212/Ag wire. The I/sub c/ and J/sub c/ reached >340 A and 1000 A/mm/sup 2/ at 28 T and 4 K.         Local J/sub c/ distribution in superconducting oxide layer of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x//Ag tapes    Y. Hishinuma, H. Kitaguchi, H. Kumakura, K. Itoh, K. Togano, H. Miao and B. Chenevier Summary: The relationship between critical current (I/sub c/) and the thickness of oxide layer of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/(Bi-2212)/Ag composite superconductor has been studied to clarify local critical current density (J/sub c/) distribution in the oxide layer. The comparison of local J/sub c/ (J/sub c//sup local/) distribution of the samples prepared with and without PAIR (P_re-A_nnealing and I_ntermediate R_olling) process gives an explanation for the large J/sub c/ enhancement by PAIR process. J/sub c/ of oxide layer within 2 /spl mu/m from the Bi-2212/Ag interface exceeds 3.8/spl times/10/sup 5/ A cm/sup -2/ at 4.2 K, 10 T. No significant increase of J/sub c//sup local/ is confirmed in the Bi-2212 layer below 2 /spl mu/m from the interface. However, J/sub c//sup local/ increases by performing PAIR process in the middle part of the Bi-2212 layer of 2-15 /spl mu/m from the interface. J/sub c//sup local/ is 2.4/spl times/10/sup 5/ A cm/sup -2/ and 1.0/spl times/10/sup 5/ A cm/sup -2/ at a distance of 5 pm and 10 /spl mu/m from the interface, respectively. The results indicate that the large J/sub c/ enhancement by PAIR process is assigned to higher J/sub c//sup local/ in this middle part. J/sub c/ improvement in the part near the free surface is also achieved by PAIR process and contributes to high J/sub c/.         Continuous production of Bi-2212 thick film on silver tape    A.Y. Ilyushechkin, B. Williams, F. Lo, T. Yamashita and P. Talbot Summary: Bi-2212 thick film on silver tapes are seen as a simple and low cost alternative to high temperature superconducting wires produced by the Powder In Tube (PIT) technique, particularly in react and wind applications. A rig for the continuous production of Bi-2212 tapes for use in react and wind component manufacture has been developed and commissioned. The rig consists of several sections, each fully automatic, for task specific duties in the production of HTS tape. The major sections are: tape coating, sintering and annealing. High temperature superconducting tapes with engineering critical current densities of 10 kA/cm/sup 2/ (77 K, self field), and lengths of up to 100 m have been produced using the rig. Properties of the finished tape are discussed and results are presented for current density versus bend radius and applied strain. Depending on tape content and thickness, irreversible strain /spl epsi//sub irrev/, varies between 0.03 and 0.1%. Cyclic bending tests when applied strain does not exceed /spl epsi//sub irrev/, showed negligible reduction in J/sub c/ along the length of the tape.         Evaluation of adhesion strength of sol-gel ceramic insulation for HTS magnets    E. Celik, J. Schwartz, E. Avci and Y.S. Hascicek Summary: Adhesion strength of high temperature insulation materials deposited on silver was investigated. CeO/sub 2/ and ZrO/sub 2/ based coatings on Ag substrates were prepared by the sol-gel technique. Experiments for determining the adhesion strength between insulations and silver were performed using a mini tensile testing machine. The microstructures of coatings and their interfaces were determined by means of SEM, EDS, and X-ray diffraction. The results indicated that the failure was in the form of a mixed type as interfacial/cohesive defect. The average adhesive strength of ZrO/sub 2/, CeO/sub 2/, ZrO/sub 2/+20 wt%MgO, Zr/sub O/2+8 wt%Y/sub 2/O/sub 3/, ZrO/sub 2/+8 wt%CeO/sub 2/, ZrO/sub 2/+15 wt%In/sub 2/O/sub 3/ and ZrO/sub 2/+15 wt%SnO/sub 2/ were found to be 0.763, 0.913, 1.045, 1.150, 0.915 0.833 and 0.797 MPa, respectively. Y/sub 2/O/sub 3/, MgO, and CeO/sub 2/ doped ZrO/sub 2/ showed the best adhesive properties.         Microwave properties of YBa/sub 2/Cu/sub 3/O/sub x/ films grown by liquid phase epitaxy    S. Miura, Jian-Guo Wen, K. Suzuki, T. Morishita, T. Yoshitake, G. Fujii and S. Suzuki Summary: Microstrip resonators and filters have been fabricated, using liquid phase epitaxially grown YBa/sub 2/Cu/sub 3/O/sub x/ films on MgO[100] substrates. A microstrip resonator at 10.8 GHz with a YBCO ground plane shows unloaded Q values of 14200 at 77 K and 23300 at 40 K. A microstrip four-pole band-pass filter, with a midband frequency of 10 GHz and a fractional bandwidth of 2% shows an insertion loss less than 0.2 dB and a return loss better than 15 dB at 77 K. The nonlinear behavior of this filter was studied by inter-modulation distortion measurements. This filter shows relatively high power handling capabilities with a third-order intercept point of +65 dBm at 77 K.         Analyses of the electromagnetic properties of oxide superconductors by the SRPM method    H. Miyairi, T. Kodaira, S. Yamazaki, H. Nakane, S. Haseyama and S. Kohayashi Summary: /spl Delta/Z (the difference in the impedance of a solenoid coil with and without a superconductive sample) of 0, 10, 20 and 30 wt% Ag-doped YBaCuO (c-axis oriented) and a Bi-based sintered sample were measured by the SRPM method between 200 Hz and 1 MHz at room temperature and liquid N/sub 2/ temperatures. At room temperature, frequency dependence of /spl Delta/Z was observed in both samples. These dependencies were analyzed using a serial circuit having the same resistance and inductance as the samples by which the existence of /spl Delta/Z was confirmed. Below T/sub c/, only /spl Delta/Z of a Bi-based sample was measured between 200 Hz and 1 MHz. /spl Delta/R (the real part of /spl Delta/Z) was evaluated as a function of frequency(f). /spl Delta/R from 0.25 to 1 kHz is assumed to be proportional to f/sup 2/ (normal skin effect). /spl Delta/R from 1 kHz to 50 kHz is proportional to f/sup 5/3/ (anomalous skin effect). /spl Delta/R from 50 kHz to 700 kHz is proportional to f/sup 2/3/ (anomalous skin effect). It was found that /spl Delta/R between 1 kHz and 700 kHz agrees with the property obtained by the equation confirming that it is in the region of anomalous skin effect.         Measurements and modeling of HTS shielded dielectric resonators    N.J. Parker, A.P. Kharel, J.R. Powell, P.A. Smith, P.D. Evans and A. Porch Summary: We have performed accurate, reproducible and nondestructive measurements of the surface resistance of high quality YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) thin films in the temperature range 12 K to T/sub c/ using a compact rutile dielectric resonator method at 9.6 GHz. The absolute values of the HTS surface resistance have been measured to systematic errors of less than 10 /spl mu//spl Omega/ at this frequency using this technique, which employs two resonator configurations with carefully chosen geometries. The resonators have unloaded Q factors of around 10/sup 5/ at 77 K, increasing to above 5.10/sup 5/ below 15 K. We have used three dimensional electromagnetic software ("Superfish") to study the effects of the copper shield on these rutile (TiO/sub 2/) measurements, and others using lanthanum aluminate (LaAlO/sub 3/) as the dielectric material. In the latter case, there are significant uncertainties (as large as 100%) in the measurements of the surface resistance of the YBCO films owing to the smaller field energy filling factor for LaAlO/sub 3/ since it has a lower relative permittivity than rutile.         Microwave surface resistance of YBCO thin films on cerium oxide buffer    M. Kusunoki, T. Suto, D. Okai, Y. Tanako, M. Mukaida and S. Ohshima Summary: The effects of the crystallinity and surface roughness of CeO/sub 2/ buffer on R-plane Al/sub 2/O/sub 3/ substrate on the microwave surface resistance (R/sub s/) of YBa/sub 2/Cu/sub 3/O/sub y/(YBCO) thin films are discussed. We estimated R/sub s/ from the transmission characteristics of the microstrip line resonator at 25 K and 6.7 GHz. X-ray diffraction (XRD) of /spl theta/-2/spl theta/ and /spl phi/-scan showed that CeO/sub 2/ was completely [001]-oriented and in-plane aligned crystal. Four CeO/sub 2/ samples with different thicknesses were prepared using identical conditions except for the deposition time. The dependence of R/sub s/ on CeO/sub 2/ thickness was measured in the range from 10 nm to 200 nm. The value of R/sub s/ was minimum at CeO/sub 2/ thickness of 100 nm. The dependence of R/sub s/ vs CeO/sub 2/ thickness was similar to that of the amount of a-axis domains against the thickness. The crystallinity of thin CeO/sub 2/ was poor because the lattice was strongly strained by Al/sub 2/O/sub 3/. This affected the quality of the upper YBCO layer. In contrast, thick CeO/sub 2/ had excellent crystallinity. However, for the thickness of more than 100 nm a drastic change in surface morphology was observed by atomic force microscopy (AFM). A number of projections appeared on the CeO/sub 2/ surface. These projections act as nucleation centers for the a-axis domains.         Ag-doped double-sided PLD-YBCO thin films for passive microwave devices in future communication systems    M. Lorenz, H. Hochmuth, D. Natusch, G. Lippold, V.L. Svetchnikov, T. Kaiser, M.A. Hein, R. Schwab and R. Heidinger Summary: Pulsed laser deposited (PLD) Ag-doped YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) thin films on both sides of 3-inch diameter sapphire wafers are used routinely for development of microwave filters for future communication systems. The reproducibly deposited YBCO:Ag films of about 250 nm thickness show critical current densities of 4 MA/cm/sup 2/ at 77 K and laterally homogeneous maps of microwave surface resistance R/sub s/ of about 45 m/spl Omega/ at 145 GHz and 77 K measured by an open resonator technique. The R/sub s/ at 8.4 GHz and 77 K determined in the center position of the YBCO:Ag films with a sapphire resonator technique remains constant at about 380 /spl mu//spl Omega/ up to a microwave surface magnetic field of 7-10 mT. Correlations of transport and microwave properties to the film microstructure are shown in terms of in-plane epitaxy, size of particulates on the films, and composition ratios Cu/O and Y/O, and growth defects like stacking faults as shown by Raman spectroscopy, SEM, and SNMS depth profiling, and TEM cross sections, respectively. The optimum Ag-content of the PLD-YBCO target was determined to be about 4 weight -%. The results demonstrate that Ag-doping supports the PLD process for YBCO in terms of reliability and cost effectiveness.         Surface resistance of screen-printed Bi2223 thick films on Ag and dielectric ceramic substrates    T. Tatekawa, N. Matsui, Y. Kintaka, Y. Ishikawa, K. Fujikawa, M. Tanaka and A. Oota Summary: Surface resistance R/sub s/ of screen-printed (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ thick films on Ag, MgO, and Ba(Sn,Mg,Ta)O/sub 3/ substrates was measured at 10.7 GHz in the temperature range between 20 and 130 K using a dielectric resonator method. For thick films on Ag substrates, it becomes lower than that for a Cu plate as temperature decreases below 100 K, and reaches 1.7 m/spl Omega/ at 77 K and 0.3 m/spl Omega/ at 30 K. The use of MgO or Ba(Sn,Mg,Ta)O/sub 3/ dielectric substrate for film fabrication causes some degradation in the value of R/sub s/, while still being superior to that for a Cu plate below 80 K. From a practical point of view, the (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ thick films were screen-printed on both sides of Ba(Sn,Mg,Ta)O/sub 3/ disk to serve as superconducting electrodes for the dielectric resonator. The unloaded quality factor Q/sub n/ for the resonator at 2.1 GHz on a TM/sub 010/ mode is superior to the same dielectric resonator with Cu electrodes below 90 K. It is 3 times higher than the value for the resonator with Cu electrodes at 70 K and also 5 times higher at 30 K.         Spatially resolved measurements of HTS microwave surface impedance    L. Hao and J.C. Gallop Summary: We describe further development of a novel technique for the characterization of microwave properties of HTS films which allows the spatial variation of this important physical parameter to be measured. The method employs a dielectric puck system that can be moved over the surface of a large HTS wafer, sampling the surface impedance at a number of discrete frequencies between 5 and 15 GHz. The surface impedance can also be rapidly measured as a function of microwave magnetic field strength. Spatial resolution for the prototype system is as small as 1-2 mm. The surface resistance and the shift in surface reactance can be measured by using a loop oscillator which can be interrupted by a fast microwave switch. The decay of microwave power in the resonator is then monitored as a function of time to determine the power dependent surface impedance parameters. This process is extremely fast and straightforward and the loop oscillator configuration permits only relatively inexpensive components to be used. We describe measurements made at 11.5 GHz of the spatial variation of the non-linear surface impedance of a number of HTS films at 77 K.         Microwave surface resistance of YBCO bulk samples prepared by addition of HgO to YBCO system    M. Misra, A. Pandey, N.D. Kataria, R.G. Sharma and G.P. Srivastava Summary: The paper reports microwave surface resistance (R/sub s/) measurement on yttrium barium copper oxide (YBCO) bulk samples, prepared by an alternate route, namely by addition of mercury oxide (HgO) to YBCO system. R/sub s/ is measured using a TE/sub 011/ mode cylindrical cavity, at 20 GHz, by the end plate substitution technique. HgO added to the YBCO system has the advantage that oxygen in HgO acts as a copious source of oxygen and therefore does not require sintering in oxygen flow. Powder X-ray diffraction studies confirm the formation of pure orthorhombic 123 phase without any indication of Hg or known Hg compounds. The specimen with 0.5 wt.% of HgO added to the YBCO system showed superior superconducting properties including microwave surface resistance (22.5 m/spl Omega/ at 77 K and 20.0014 GHz). The R/sub s/ has also been measured as a function of the area of the sample that yields consistent value confirming surface homogeneity. This is believed due to stoichiometric oxygenation and large number of well connected grains.         Ion-beam milling of YBCO thin films and their characterization by time-resolved pump-probe method    M. Hangyo, S. Nashima, M. Kawamura, S. Shikii and M. Tonouchi Summary: YBCO films are exposed to Ar ion beams in order to obtain flat surfaces and they are characterized by the time-resolved reflection pump-probe method excited with femtosecond optical pulses. The amplitudes of the reflectivity change of the ion-beam processed films are smaller than that of the as-grown ones and the decay time decreases by the ion-beam etching. These results are discussed in relation to the changes of the supercarrier density and the relaxation time of quasiparticles by the ion-beam milling.         Numerical optimization of hybrid dielectric/HTS resonators for surface impedance evaluation of HTS films    C. Collado, D. Gonzalo, E. Rozan, J.M. O'Callaghan and C. Sans Summary: This work describes an alternative to the traditional dielectric resonator topology used for measuring surface impedance in high temperature superconducting (HTS) films. A gap is introduced above the dielectric so that only the lower film is in direct contact with it. This arrangement has been used extensively for mechanical tuning of dielectric resonators and, when used for surface impedance measurement, it can be designed to make the losses in the upper film small relative to the overall resonator losses. Then, measured results are mostly due to one of the films and not the average of two. The specifics of a resonator design for measuring 2-inch wafers are presented. An analysis and optimization of the resonator is done using a numerically efficient mode-matching algorithm.         Scanning Hall probe measurements on single- and double-sided sputtered YBCO films for microwave applications    A. Cassinese, M. Getta, M. Hein, T. Kaiser, H.G. Kurschner, B. Lehndorff, G. Muller, H. Piel and B. Skriba Summary: We have investigated the quality and the homogeneity of YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) films up to /spl phi/=2" diameter and t=360 nm in thickness with a scanning Hall probe. The YBCO films were grown by high oxygen pressure sputtering with heater temperature compensation up to T=1020/spl deg/C, resulting in a constant growth temperature for both film sides. Typical /spl phi/=1" double-sided films on LaAlO/sub 3/ substrates revealed inductively T/sub c/=87.8(88.2) K and J/sub c/=4(4.5) MA/cm/sup 2/ for the first (second) deposited side. Surface resistance measurements at 87 GHz resulted in R/sub s/(4.2 K)=2.6 (1.6) m/spl Omega/. At 19 GHz, R/sub s/(4.2 K)=0.2 m/spl Omega/ with moderate field dependence up to B/sub s/=15 mT was obtained for both sides. The scanning Hall probe measurements have been carried out after cooling the film in an external magnetic field and then switching it off. The local J/sub c/ values deduced from the measured remanent induction B were in good agreement with inductive data taken at corresponding positions. Different kinds of defects and inhomogeneities were investigated with a spatial resolution of 1 mm.         Ion-beam assisted deposition of bi-axially aligned MgO template films for YBCO coated conductors    J.R. Groves, P.N. Arendt, S.R. Foltyn, R.F. DePaula, E.J. Peterson, T.G. Holesinger, J.Y. Coulter, R.W. Springer, C.P. Wang and R.H. Hammond Summary: We report the results of experiments with ion-beam-assisted deposition (IBAD) of MgO using in-situ monitoring with Reflected High-Energy Electron Diffraction (RHEED). Strips of polished Haynes 242 and Inconel 625 nickel-based super-alloys have been used as substrates for these experiments. The in-plane texture of the MgO, as measured by X-ray /spl phi/ scan, resulted in FWHM values between 11 and 15/spl deg/. Using pulsed-laser deposition, the IBAD MgO template films were then overcoated with buffer layer films and a final superconducting film of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//. The best superconducting transport properties measured on these YBCO films were: an Ic (75 K, self-field, 1 cm wide) of 41.6 A, and a narrow-bridge J/sub c/ (1.35 /spl mu/m thick film) of 0.46 MA/cm/sup 2/.         Reel-to-reel continuous deposition of epitaxial CeO/sub 2/ buffer layers on biaxially textured Ni tapes by electron beam evaporation    X. Cui, F.A. List, D.M. Kroeger, A. Goyal, D.F. Lee, J. Mathis, E.D. Specht, P.M. Martin, R. Feenstra, D.T. Verebelyi, D.K. Christen and M. Paranthaman Summary: A reel-to-reel, electron beam evaporation system has been developed to continuously deposit epitaxial CeO/sub 2/ and other oxide buffer layers on meter-long lengths of biaxially textured Ni tapes. The deposition system includes two interconnected electron beam evaporation chambers and a chamber in which as-rolled Ni tape is in situ annealed to develop biaxial texture. An integral reel-to-reel system with tension control enables motion of the tape with little or no plastic deformation. When depositing epitaxial oxides on Ni, the formation of unfavorably oriented NiO is difficult to avoid. Oxide free, {100}<100> oriented Ni tapes are prepared by control of the partial pressures of H/sub 2/, H/sub 2/O and O/sub 2/ during Ni annealing. X-ray /spl phi/-scans have been performed as a function of length to determine the crystallographic consistency of the epitaxial CeO/sub 2/ over length. Results of SEM examinations of the CeO/sub 2/ buffer layer microstructure are presented. Results for YBCO films deposited on short segments of these buffered substrates are summarized.         Processing of Y123 coated conductors using metal organic decomposition    S. Sathyamurthy and K. Salama Summary: Processing of Y123 and barium zirconate films using scalable metal organic decomposition (MOD) techniques and their application to the development of coated conductors is investigated. Thick films of Y123 have been processed on single crystal substrates using the decomposition of metal trifluoroacetates. X-ray diffraction and pole figure analysis of films deposited on [100] strontium titanate and lanthanum aluminate single crystal substrates show that these films have good phase purity and a very high degree of alignment with the substrate both out-of-plane (<0.5/spl deg/) and in-plane (<1.5/spl deg/). These chemically derived films were also found to have critical current densities greater than 0.5 MA/cm/sup 2/ at 77 K for 0.5 /spl mu/m thick films. Barium zirconate films have been processed on single crystal substrates using the decomposition of a stoichiometric mixture of barium acetate and zirconium pentanedionate. X-ray characterization of these films shows a strong tendency to texture, and scanning electron micrographs of these films shows that they have an extremely smooth and uniform surface. Y123 films processed on these buffered single crystals have a dense microstructure with a strong tendency to texture. Thus, the possibility of application of these processing techniques on flexible substrates offers promise to the fabrication of long length coated conductors.         Thermal cycling behavior of YBCO high temperature superconductor thick films    F. Yang, Y. Liu, K.H. Wu and G. Larkins Summary: Thermal cycling behavior of YBCO high temperature superconductor thick films coated on different ceramic substrates was studied. It was found that the YBCO superconductor thick film coated on MgO substrate has a better thermal cycle resistance than Al/sub 2/O/sub 3/ substrate; the cycle number for initiating thermal fatigue crack significantly decreases as the thermal cycling temperature range increases. Film thickness was found to have an influence on thermal cycling resistance for thicknesses in the range of 70 to 100 /spl mu/m. A simple thermal mechanical model is employed to describe the thermal stress, and the thermal cycles of failure of YBCO thick films.         High growth rate deposition techniques for coated conductors: liquid phase epitaxy and vapor-liquid-solid growth    I. Hirabayashi, Y. Yoshida, Y. Yamada, Y. Koike and K. Matsumoto Summary: High growth rate deposition techniques for coated conductors are developed via liquid phase epitaxy (LPE) and vapor-liquid-solid (VLS) growth. By adding fluorine and silver under low oxygen partial pressure, the processing temperature of LPE decreased down to 850/spl deg/C and it enabled us to grow YBCO on metallic substrates such as cube-textured silver tapes. On the other hand, VLS growth is a combinatorial deposition technique between vapor growth and LPE. It is essentially a LPE growth supplied from the vapor phase. Here, we discuss the utilization of VLS growth as a rapid vapor growth for production of YBCO coated conductor.         In-plane aligned YBCO thick films on {110} rolled and single crystal silver by ultrasonic mist pyrolysis    J.J. Wells, A. Crossley, R. Sweeney and J.L. MacManus-Driscoll Summary: An ultrasonic mist pyrolysis system has been used to fabricate thick films of YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) on rolled and single crystal silver substrates. The substrates were heated to 900/spl deg/C and nitrate solutions of the constituent cations were sprayed using a nitrogen carrier gas. Highly c-axis aligned YBCO films were obtained by deposition at a rate of /spl sim/1 /spl mu/m per minute. Phase pure YBCO formed up to a limit of /spl sim/6 /spl mu/m. For thicker films, BaCuO/sub 2/ and Y/sub 2/BaCuO/sub 5/ also formed. On {110} oriented single crystal silver, the films showed in-plane alignment with a four fold symmetry, and the FWHM in the azimuthal direction of the main peaks was /spl sim/3/spl deg/. On the polycrystalline substrate the in-plane texture showed a /spl sim/20/spl deg/ FWHM, equivalent to that of {110}<110> textured silver substrate. The onset of superconducting transition was measured as /spl sim/90.2K for sample with a film thickness of /spl sim/5 /spl mu/m.         In-plane magnetization and hysteresis losses in YBCO thick films    A. Rastogi, H. Yamasaki and A. Sawa Summary: We present our observations of hysteretic magnetization of c-axis oriented thick (1-2 /spl mu/m) YBCO films in parallel fields. For other orientations of the field, the magnetization is reported to be mainly due to the c-axis component (M/sub c/sin/spl theta/) because of a large aspect ratio of the film. But our observations at low fields (/spl les/100 mT) did not follow such behavior. Moreover, the in-plane magnetization is affected by an artifact introduced during the deposition of such thick films. We discuss our results in the framework of Bean's model after removing the artifact.         Oxidation of multilayer HTS digital circuits    J. Talvacchio, R.M. Young, M.G. Forrester and B.D. Hunt Summary: The issue of oxygen diffusion through insulating layers to buried superconductor films is common to any multilayer structure based on YBCO. Our earliest technique for obtaining fully oxidized underlayers on a practical time scale used reduced growth temperatures for strontium titanate insulating films to introduce defects which enabled oxygen diffusion while maintaining the integrity of electrical isolation. Since this approach did not work well with Sr-Al-Ta-O (SAT) and Sr-Al-Nb-O (SAN) insulators which have more desirable dielectric properties, a plasma oxidation process was introduced. For digital circuits based on HTS Josephson junctions where buried groundplanes must be fully oxidized, plasma oxidation had profound effects on the properties of cobalt or calcium-doped YBCO films used for N-layers in SNS edge junctions, increasing function critical currents by a factor of five. These experiments offer some insight into the role of oxygen in determining both individual junction properties and junction reproducibility. A third approach to oxidation of buried films relies on "oxygen vias" patterned in the insulating layer to permit oxygen to diffuse in the a-b plane of YBCO films instead of diffusing through the insulating layer. We designed and measured test structures which set a practical limit of 20-30 micrometers for via sparing.         Effect of ozone anneals on YBa/sub 2/Cu/sub 3-x/Co/sub x/O/sub 2/ thin films    J.P. Sydow and R.A. Buhrman Summary: We report on the effect of 200-500C ozone anneals on the resistivity versus temperature (RT) and Raman spectra characteristics of YBa/sub 2/Cu/sub 3-x/Co/sub x/O/sub 2/ (Co-YBCO) thin films, with x=0.3, 0.5, 0.75, and 1.0. Cold wall anneals are conducted at /spl sim/1 aim. of a flowing O/sub 2//O/sub 3/ mixture with /spl sim/2% O/sub 3/ by weight. The enhanced partial pressure of atomic oxygen, relative to canonical O/sub 2/ anneals, provided by ozone to the surface of Co-YBCO films, leads to enhanced oxygenation. This is demonstrated by the observation of an increase in T/sub c/ (25 K to 75 K for x=0.3, 0 to 38 K for x=0.5, and 0 to a T/sub c/(onset) of 19 K for x=0.75) and improvement in Raman spectra data following ozone anneals. This high degree of oxygenation is unstable under O/sub 2/ anneals at temperatures as low as 200C. We attribute this to the fact that the partial pressure of oxygen above well oxygenated Co-YBCO is greater than 1 atm. at /spl sim/200C. We will discuss the implication of these results for the stability and uniformity of SNS ramp edge Josephson junctions which employ Co-YBCO N-layers.         Electrical and materials characterization of a robust YBCO multilayer film process for HTS circuit applications    C.L. Pettiette-Hall, J. Murduck, J.F. Burch, M. Sergant, R. Hu, J. Cordromp and H. Aquilino Summary: We have developed a 2" multilayer HTS process that contains four epitaxial layers (3 superconducting and one dielectric) and up to 4 additional non-epitaxial layers. Employing n-factorial and Taguchi designed experiments, we have improved crossover critical currents by 45/spl times/ and via critical currents by 60/spl times/. We use the DOE approach to quantitatively compare processing factors and identify those which are electrically significant. Transmission Electron Microscopy confirms the morphological changes which cause the electrical response. This article highlights the history of our multilayer process, using both TEM and electrical results to show how process modifications have led to a robust multilayer process for HTS circuit applications.         Improved J/sub c/ of bilayer YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin film structures    J.P. Zhou, C.E. Jones, J.T. McDevitt, Y. Gim, J.B. Goodenough, C. Kwon and Q.X. Jia Summary: Critical-current (J/sub c/) measurements for YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO), Gd/sub 0.6/Ca/sub 0.4/Ba/sub 1.6/La/sub 0.4/Cu/sub 3/O/sub 7-/spl delta// (TX-GBCO) and TX-GBCO/YBCO bilayers were performed with transport measurements at different applied magnetic fields. The film samples were prepared by pulsed laser deposition and patterned as microbridges. The highest J/sub c/ (1.5/spl times/10/sup 6/ A/cm/sup 2/) at 75 K in 5 Tesla (Hllab) was observed for TX-GBCO/YBCO bilayers, which showed a 40% increase in J/sub c/ over YBCO under the same conditions. The bilayer samples possess a T/sub c/ at 90 K and display superconducting properties similar to YBCO. A possible mechanisms for the high J/sub c/ of bilayer YBCO films is discussed. Development of these bilayer and multilayer structures represents a promising new direction to improve the superconducting properties of YBCO since the TX-GBCO layer provide both protection against corrosion and a significant improvement in J/sub c/.         Superconductivity in Bi/sub 2/Sr/sub 2/CuO/sub 6+/spl delta///(Sr,Ca)CuO/sub 2/ multilayers obtained by molecular beam epitaxy    M. Salvato, C. Attanasio, G. Carbone, T. Di Luccio, S.L. Prischepa, R. Russo and L. Maritato Summary: Bi-based high temperature superconducting multilayers have been obtained by Molecular Beam Epitaxy (MBE) using a deposition method which consists of both co-deposition and growth interruption techniques. We have studied two kinds of structures in which a layer of Bi/sub 2/Sr/sub 2/CuO/sub 6+/spl delta// (2201) is alternately stacked by an insulating layer of CaCuO/sub 2/ or SrCuO/sub 2/ in order to obtain 2201/CaCuO/sub 2/ or 2201/SrCuO/sub 2/ multilayers. Reflection High Energy Electron Diffraction (RHEED), used to control the quality of the interfaces and the two-dimensional growth mode, gives evidence of an increase in the surface roughness increasing the number of periods. The layered structure has been confirmed comparing experimental and simulated X-ray spectra. The R vs. T curves of the 2201/SrCuO/sub 2/ multilayers present an onset and behave differently from those of the single phase samples with the same stoichiometry but they are not superconducting down to T=4.2 K. On the contrary, the 2201/CaCuO/sub 2/ samples are superconducting with critical temperatures strongly depending on the CaCuO/sub 2/ thickness.         A multi-step process to improve texturing and transport current in BSCCO (2223) superconductors    A. Tampieri, G. Celotti and G. Calestani Summary: Bulk BSCCO(2223) was prepared by a multi-step process (high cold pressing+pressureless sintering+hot-forging): the final density of the samples exceeds 95% and the orientation factor increases up to /spl ap/86%. It was found that the process phenomenology is strictly linked to the starting powder stoichiometry and characteristics: when composition is very near to the theoretical (2223), effects of secondary phase extrusion are observed during hot-forging, yielding a purification and inhibition of (2212) formation, accompanied by an appreciable increase of J/sub c/ with respect to hot-pressed samples. When the Ca/Sr ratio is considerably >1, recrystallisation of (2223) from the liquid takes place, with a remarkable improvement of critical current density (J/sub c/>10/sup 4/ A/cm/sup 2/). In this case, the non-superconducting secondary phases act as an intrinsic oxygen reservoir. Finally, when composition diverges even more from (2223) (Ca/Sr/spl Gt/1 and Cu excess), the formation of too many precipitates of non-superconducting phases hinders the texturing process and more in general deteriorates the intergranular properties.         Melt textured process for YBCO in high magnetic fields    S. Awaji, K. Watanabe, M. Motokawa, A. Kuramochi, T. Fukase and K. Kimura Summary: YBa/sub 2/Cu/sub 3/O/sub 7/ bulk samples were synthesized by the melt textured seeding process in high magnetic fields, using high field heat treatment equipment installed with an 11 T cryocooled superconducting magnet. The X-ray rocking curves of [005] and [006] indicate that the texture in grain of the YBa/sub 2/Cu/sub 3/O/sub 7/ matrix was improved by applying a magnetic field of only a few tesla. Moreover, it is found that the distribution of Y/sub 2/BaCuO/sub x/ particles was changed by applying a magnetic field of /spl ap/10 T. The critical current properties are remarkably influenced by applying a magnetic field during melt growth processing.         A large scale approach of bulk HTS to the electric utility area    F.N. Werfel, U. Flogel-Delor, D. Wippich and R. Rothfeld Summary: On the basis of a novel industrial-like YBCO seedless functional melt texture grain alignment process, various HTS devices for superconducting magnetic bearings (SMB) and high-current leads for transport and limiting purposes are fabricated. Critical shielding currents of 30 kA/cm/sup 2/ at 77 K are utilized to construct radial-passive magnetic bearings for 20 kg loads or to suspend and spin a O 4 cm rotor safely to 120000 rpm. Stiffnesses between 40 to 140 N/mm are measured. Multi-grain YBCO rods up to 20 cm length are tested for more than 6 kA/cm/sup 2/ transport currents. The connections to the copper braids are improved to less than 0.4 micro-ohm at 1000 Amperes and 77 K. The experiments show the practical potential of melt textured YBCO with macroscopic orientation of the grain structure for electric power purposes.         YBCO/Ag bulk material by melt crystalization for cryomagnetic applications    P. Schatzle, G. Krabbes, S. Gruss and G. Fuchs Summary: Based on thermoanalytic investigations a melt crystallization process was developed with reduced process temperatures and process times to produce YBCO/Ag monoliths (d=26 mm) achieving the homogenous distribution of small sized Ag inclusions. The mechanical properties are improved, but the superconducting properties at 77 K, B/sub 0/ (480 mT) and F/sub N/ (40 N) are slightly reduced compared with YBCO monoliths without an addition of Ag (750 mT and 65 N). The maximum trapped flux was increased to the value B/sub 0/ 9.4 T at 26.5 K, instead of 8.4 T in the Ag-free bulk monolith.         Comparative studies of irreversibility lines and critical current in heavy ion irradiated Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// bicrystals with [001] twist grain boundaries    Qiang Li, Y.N. Tsay, M. Suenaga, G. Wirth, G.D. Gu and N. Koshizuka Summary: Columnar defects, through 2.2 GeV Au-ions irradiation, were introduced into Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// (Bi-2212) bicrystals with [001] twist grain boundaries. Studies of the effect of heavy ion irradiation on the transport properties of the bicrystals were performed by measuring the irreversibility line and critical current within the constituent single crystals and across the [001] twist grain boundaries before and after irradiation. We found that the columnar defects greatly increased the irreversible temperature determined both within the single crystals and across the grain boundaries. However, the enhancement on critical current by the columnar defects measured across the grain boundaries is not significant, while more than an order of magnitude increase in the single crystal critical current was observed.         The influence of vortex pinning and grain boundary structure on critical currents across grain boundaries in YBa/sub 2/Cu/sub 3/O/sub x/    D.J. Miller, K.E. Gray, M.B. Field and DongHo Kim Summary: We have used studies of single grain boundaries in YBCO thin films and bulk bicrystals to study the influence of vortex pinning along a grain boundary on dissipation. The critical current density for transport across grain boundaries in thin films is typically more than an order of magnitude larger than that measured for transport across grain boundaries in bulk samples. For low misorientation angles, the difference in critical current density within the grains that form the boundary can contribute to the substantial differences in current density measured across the boundary. However, substantial differences exist in the critical current density across boundaries in thin film compared to bulk bicrystals even in the higher angle regime in which grain boundary dissipation dominates. The differences in critical current density in this regime can be understood on the basis of vortex pinning along the boundary.         Characterization of the structure of Y-Ba-Cu-O coated conductors    H. Kung, S.R. Foltyn, P.N. Arendt and M.P. Maley Summary: Transmission electron microscopy (TEM) has been applied to the microstructural investigation of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thick films deposited on polycrystalline Ni-based metal substrates by pulsed laser deposition. The films were found to be strongly textured with c-axis oriented grains aligned perpendicular to the substrates. Despite the large average in-plane misorientation (/spl theta//spl sim/14/spl deg/), as was estimated from selected area electron diffraction and X-ray diffraction, TEM inspection reveals colonies of submicron-sized grains with low angle (/spl theta//spl les/7/spl deg/) tilt grain boundaries. The linkage of the colony structures may provide a continuous percolation pathway for the supercurrent transport in YBCO, which may provide the mechanism for the higher than expected critical current density J/sub c/. Periodic arrays of grain boundary dislocations were observed, which may serve as effective flux pinners.         Transport properties of bulk-bicrystal grain boundaries in artificially joined large-grain YBCO    A.D. Bradley, R.A. Doyle, D. Charalambous, W. Lo, D.A. Cardwell, A.M. Campbell and P. Vanderbenden Summary: A technique for joining large-grain YBCO has been used to produce bulk-bicrystal grain boundaries of different orientations. The behaviour of boundaries nominally of 0/spl deg/[100], 0/spl deg/[001] and asymmetric 15/spl deg/[100]-tilt misorientation have been investigated using low frequency transport measurements in fields up to 7 T. The boundaries exhibit a metallic normal state and a superconducting transition which broadens with increasing field having an irreversibility line which closely matches that of the adjoining grains. This same qualitative behaviour is seen in all the samples measured for field applied parallel and perpendicular to the c-axis and up to the highest current densities employed (20 Acm/sup -2/). Variation between the different samples due to microstructural differences are discussed. We interpret these results as strong suggestive evidence that this joining technique can be used to produce strongly-coupled large-grains for bulk-scale engineering applications.         Development of non-weak link bulk YBCO grain boundaries for high magnetic field engineering applications    Wai Lo, D.A. Cardwell, A.D. Bradley, R.A. Doyle, Y.H. Shi and S. Lloyd Summary: A non-weak link joining technique has been developed for YBCO pseudo-crystals fabricated by seeded peritectic solidification based on the formation of a liquid phase which segregates from the platelet boundaries at temperatures above /spl ap/920/spl deg/C. Electrical and magnetic measurements on these boundaries suggest that their irreversibility field can be as high as 7 T at 77 K in fully oxygenated pseudo-crystals joined along their crystallographic ab-planes which is comparable to the irreversibility behaviour of the adjacent YBCO grains.         Microstructural studies of high-T/sub c/ superconducting Josephson junctions to understand junction properties    J.G. Wen, T. Usagawa, T. Takagi, Y. Ishimaru, Y. Enoloto and N. Koshizuka Summary: Transmission electron microscopy (TEM) is applied to the study of the relationship between the microstructures and the electrical properties of Josephson junctions. Typical microstructures for several artificial barrier junctions and grain boundary (GB) junctions are reviewed. In the case of artificial barrier junctions, it was found that the barrier layer coverage can be enhanced by using a-axis oriented bottom electrodes and homoepitaxy growth. TEM observations of multi-layer junctions with PrBa/sub 2/Cu/sub 3/O/sub y/ (PrBCO) or YBa/sub 2/Fe/sub 3/O/sub y/ (YBFeO) barrier layers grown by quasi-homoepitaxy showed prefect coverage and good crystallinity. Liquid phase-epitaxy was successfully used to obtain large single facet GBs over 50 pin by growing YBa/sub 2/Cu/sub 3/O/sub y/ (YBCO) films on bicrystal substrates. Microstructures and atomic arrangements of these straight bicrystal GBs are presented.         Change of the HTSC harmonic susceptibility properties with electrolytic hydrogen loading using different aqueous solution as LiOH and NaOH    P. Tripodi, D. Di Gioacchino, F. Celani, A. Spallone and D. Vinko Summary: The higher harmonics magnetic susceptibilities (/spl chi/=/spl chi//sub i/'+i/spl chi//sub i/'') of HTSC hydrogen loaded as function of the temperature at 6 G of ac magnetic field amplitude at 107 Hz of frequency have been measured. The samples have been loaded by electrolysis in an aqueous solution using /spl mu/s current pulses at room temperature. The HTSC electrodes have been polarized by short pulse width (1 /spl mu/s) and high peak current (/spl ges/4 A) with a low duty-cycle (10/sup -3/) and a variable repetition rate (1-5 kHz). The hydrogen influence on HTSC (T/sub c/, ac losses) has been measured and the increasing of the superconducting properties, particularly T/sub c/ and J/sub c/, have been found. These effects appear strongly dependent to the loading process and to the stoichiometric ratio H/YBCO. It has been demonstrated that the electrolyte (Li, Na) does not affect the YBCO superconducting properties.         High pressure oxygenation in melt textured NdBa/sub 2/Cu/sub 3/O/sub 7/: identification of pinning mechanisms    T. Puiog, X. Obradors, B. Martinez, F. Sandiumenge, V. Gomis and J.A. Alonso Summary: A competing effect inducing both an enhancement of interface pinning and aging of the critical currents has been established in NdBa/sub 2/Cu/sub 3/O/sub 7-/spl delta///Nd/sub 4/Ba/sub 2/Cu/sub 2/O/sub 10/ (Nd123/422) melt-textured ceramic composites upon high oxygen pressure annealing. It is suggested that Nd123/422 interfaces are enriched in antisite defects, which are properly oxygenated only upon high PO/sub 2/ annealing. Additional evidence for the enhanced oxygenation is gained from the observation of a consequent decrease of the field induced anomaly at intermediate fields.         Small cyclic fatigue and properties of melt-processed YBCO    I.A. Parinov and E.V. Rozhkov Summary: The fatigue fracture of melt-processed YBCO is considered based on the earlier developed computational approach. The occurrence of microstructures is modeled using heat treatment and Monte Carlo simulations. The results are applied to the investigation of microstructural dissimilitude in the problem of small cyclic loading. Some effective properties of modelled structures are estimated.         The effect of platinum and excess 211 phase on the loss of the liquid phase in melt textured YBa/sub 2/Cu/sub 3/O/sub 7-x/    W.C. Hicks, F. Dogan, M. Strasik, A.C. Day and K.E. McCrary Summary: Platinum is an important additive in YBa/sub 2/Cu/sub 3/O/sub 7-x/ [123] powders for melt processing and growth of large oriented crystals, but its role in liquid loss during the growth cycle is poorly understood. A series of experiments were conducted to determine how platinum effects liquid loss, and to study the solubility limit of platinum in 123. Both atomically mixed and solid state platinum sources were compared. Crystals were grown on a nonreactive setter so that liquid loss could be clearly distinguished by weight from reaction products with the setter. Based on weight loss studies there was little difference between atomically added platinum and by adding platinum powder to the 123 powder. In samples with no excess Y/sub 2/BaCuO/sub 5/ (211), weight loss due to liquid loss was at a minimum of 3.8 percent with 0.3 weight percent platinum content. Examination with an electron microprobe reveals different microstructures for the two different methods of platinum additions.         Effect of Ag addition on the mechanical properties of bulk superconductors    T. Miyamoto, J. Katagiri, K. Nagashima and M. Murakami Summary: Bulk superconductors can function as quasi-permanents with generating magnetic fields much higher than those of conventional permanent magnets. However, a large electromagnetic force acts on such bulk superconductors, which sometimes leads to fracture. It is known that Ag addition is effective in improving the fracture toughness of bulk Y-Ba-Cu-O superconductors. Therefore, in this paper, we have studied the effects of Ag addition both on trapped field capability and mechanical properties of bulk RE-Ba-Cu-O (RE: Y, Sm) and have found that Ag addition is indeed effective in improving the mechanical properties of a large single-grain RE-Ba-Cu-O.         High trapped fields in melt-textured YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//    S. Gruss, G. Fuchs, G. Krabbes, P. Schatzle, J. Fink, K.H. Muller and L. Schultz Summary: Bulk melt textured YBCO material with single-domain grains up to 35 mm in diameter was prepared by a modified melt-texture process. The maximum trapped field B/sub o/ measured in the 1 mm gap between two single-grain disks was found to increase from 1.2 T at 75 K up to 9.6 T at 46 K, which is the highest trapped field achieved in nonirradiated samples. A strong exponential decrease of the trapped field with increasing temperature found in most of the cases can be explained by flux creep within the framework of collective pinning assuming weak pinning. A weaker B/sub o/(T) dependence and higher B/sub o/ values at temperatures between 55 and 75 K were observed in newly processed YBCO material. A pronounced peak effect found in the field dependence of the critical current density suggests strong pinning in this material. For applications of YBCO samples in superconducting magnetic bearings, an effective method for magnetizing the superconductor is required. Results of magnetizing YBCO samples by applying pulsed magnetic fields are presented.         Mechanical properties of TSMG-YBCO    A. Leenders, M. Ullrich and H.C. Freyhardt Summary: The fracture toughness, K/sub c/, of YBCO prepared by the top-seeded-melt-growth (TSMG) method can be improved by increasing the yttrium content. K/sub c/ increases from 1.01 MPa/spl radic/m for samples with 30 mol % Y/sub 2/Ba/sub 1/Cu/sub 1/O/sub 5/ (Y-211) addition to a value of 1.44(22) MPa/spl radic/m for samples with 60 mol % Y-211 addition. Substituting CeO/sub 2/ for PtO/sub 2/ results in a further enhancement of K/sub c/. In both cases the improvement can be explained by a refinement and homogenization of the distribution of Y-211 particles. The incorporation of ductile particles also contributes to an enhanced fracture toughness of the melt-textured monoliths.         Development of YBCO levitators for simple applications    V. Plechacek Summary: Levitation and suspension of a superconductor above and under a rare earth magnet is one of the promising applications of high temperature superconductors, e.g. in frictionless self-stabilized magnetic bearings. This paper describes a development of the seeded melt growth (SMC) method for Y-Ba-Cu-O (YBCO) levitators with regard to simplicity and to the limitation of the usually long preparation period. Attention was paid to a correct selection of the precursor powder as well as to the SMG process parameters and above all with respect to the resulting levitation force. Typical and highest levitation forces of about 16 N and 24 N, respectively, between the 21 mm diameter YBCO levitators and the neodymium-iron-boron permanent magnet at 77 K were obtained. In addition, a simple application of YBCO levitators, the superconducting magnetic top, is presented for demonstration.         Annealing and mechanical properties of bulk Y-Ba-Cu-O    K.C. Goretta, P. Diko, Ming Jiang, M.M. Cuber, Ming Xu, J.E. Ostenson and S. Sengupta Summary: Melt-processed YBa/sub 2/Cu/sub 3/O/sub x//Y/sub 2/BaCuO/sub 5/ and conventional polycrystalline sintered YBa/sub 2/Cu/sub 3/O/sub x/ pellets were prepared. Elastic modulus, hardness, and fracture strength were measured on selected sections cut from the pellets. Strength in the melt-processed pellets ranged from 32 to 94 MPa and was highest in the center. Variations in strength were related to microstructural features, especially Y/sub 2/BaCuO/sub 5/ distribution. To improve strength, we attempted to minimize microcracking by manipulating cooling rates and annealing times. We found that control of annealing reduced microcracking of the polycrystalline sintered pellets, but had little effect on the single-domain melt-processed pellets.         Spatial distribution of structural and superconducting properties in high processing rate melt textured YBCO    A. Vecchione, M. Gombos, S. Pace and M. Polichetti Summary: In this work, we report on directionally solidified YBCO bars fabricated by the horizontal Bridgman technique based on sample transport in a thermal gradient. We employ a pulling rate in the furnace three orders of magnitude higher than the value of 0.5 mm/h generally used to maximize the critical current densities. We cut the produced sample in several slices perpendicularly to the pulling direction with the purpose of analysing the spatial distribution of superconducting, morphological and structural properties as a function of their position along the pulling direction. X-ray diffraction and SEM analyses show that partial texturing occurs even at very high pulling rates. Each slice has an onset of the critical temperature at /spl sim/90 K Moreover, the critical current densities at 77 K and at 1 Tesla are estimated from dc magnetisation curves in hundreds of A/cm/sup 2/.         Rejoining of single grain melt textured bulk YBa/sub 2/Cu/sub 3/O/sub 7-x/    S.J. Manton, C. Beduz and Yifeng Yang Summary: The possibility of joining single grains of RE123 materials considerably enhances the applicability of bulk materials with respect to large scale applications. High quality superconducting joints produced via an infiltration method have been fabricated and studied. Using a wafering diamond saw, individual 200 /spl mu/m wide slots were cut into single grains of melt textured Y123 and the gaps were then filled with a mixture of Y/sub 2/O/sub 3/ and BaCO powders. A pressed pellet consisting of mixed Er123, Ba-CuO and CuO powders is then placed over the slots. The two regions were then rejoined by allowing molten phases to be absorbed into the powder. This process takes place at a temperature below the peritectic of Y123 and thus the crystal structure of the original bulk remains relatively unchanged. The newly formed Er/Y123 material displays the same orientation as the original grain. Also we have shown that in general the Y211 inclusions are smaller in the rejoined region than in the surrounding bulk. Microstructural and compositional data are presented and discussed.         Control of growth rate and texture formation of YBa/sub 2/Cu/sub 3/O/sub 7-y/ single-domain crystal by applying two-step undercooling in TSMG    Y.A. Jee, Gye-Won Hong, Chan-Joong Kim and Tae-Hyun Sung Summary: A fabrication technique for a single-domain Y123 crystal by top-seeded melt processing was developed using two step undercooling. At the first undercooling step, the Y123 nucleus was stabilized, and increased growth rate was intended at the second undercooling step. By the two step undercooling method, the processing time required for the growth of Y123 single-domain crystal was significantly reduced without degradation of the superconducting properties. The microstructures and textures of Y123 samples prepared by two step undercooling were also investigated.         Dissolution and resolidification of SmBa/sub 2/Cu/sub 3/O/sub 7-y/ seed during top seeded melt texturing of YBa/sub 2/Cu/sub 3/O/sub 7-y/    Y.A. Jee, Gye-Won Hong, Chan-Joong Kim and Tae-Hyun Sung Summary: During top-seeded melt growth of a YBa/sub 2/Cu/sub 3/O/sub 7-y/ (Y123) single-domain crystal, seed dissolution occurred while the seed was in contact with Ba-Cu-O liquid, and then the dissolved parts were resolidified during cooling. The growth mode of the Y123 crystal was directly affected by the resolidification process of the dissolved part. When the melted part of the seed was resolidified to a polycrystal, Y123 grew also as a polycrystalline form. In contrast, when the dissolved part of the seed completely recovered its mother orientation during cooling, a single-domain Y123 crystal could be obtained. The dissolution behavior of the SmBa/sub 2/Cu/sub 3/O/sub 7-y/ (Sm123) seed is explained in terms of the solubility of samarium in Ba-Cu-O liquid. The resolidification mode of the melted part is discussed in terms of the Sm content within the interdiffusion layer of Sm and Y.         Critical current density of filamentary Nd123 superconductor by solution spinning method    T. Kimura, T. Goto and K. Watanabe Summary: We have studied the fabrication of filamentary Nd123 superconductor with high superconducting properties. The filamentary Nd123 precursor was prepared by the solution spinning method, through a homogeneous aqueous solution containing mixed acetates of Nd, Be, Cu, poly (vinyl alcohol) and organic acids. The filamentary sample was partially melted at 990/spl deg/C in flowing 0.1%O/sub 2/+Ar and oxygenated under various conditions. The transport critical current density (J/sub c/) for the samples was examined in magnetic fields up to 9.5 T at 77 K. The highest J/sub c/ value of 3.5/spl times/10/sup 4/ A/cm/sup 2/ at 77 K and 0 T and more than 10/sup 4/ A/cm/sup 2/ at 77 K and at 2 T was achieved for the filamentary Nd/sub 1.18/Ba/sub 2.12/Cu/sub 3.09/O/sub x/ superconductor by controlling the oxygenation conditions.         Thermal cycling of thick-film and thin-film electrical contacts on melt-processed YBCO    M.W. Hosking, J. Byrne, S.R. Ashton, A. Pijanowski and B.A. Tonkin Summary: Results are presented from thermal cycling experiments of electrical contacts, carried out to investigate possible failure mechanisms. The contacts were of thick-film silver and thin-film gold on thick-film yttrium barium copper oxide, the latter having been previously fired onto yttria-stabilised zirconia substrates. Continuous observation was made of a dc current passing through the samples, via thin copper wires and the cycling itself was a series of thermal shocks, produced by immersion of the samples in liquid nitrogen, followed by rapid warm-up over a temperature increment of 100 K. It was found that the method of attachment of the copper wires had the greatest effect on the reliability of the deposited contacts.         Preparation of unleaded BSCCO superconductor with critical temperatures of 110 K    N.A. Pryrkova and Z.M. Tomilo Summary: The results of the unleaded synthesis, and superconducting properties, and phase composition investigation of high-T/sub c/ superconductors obtained in the BiSrCaCuO (BSCCO system), when partially substituting copper oxide for copper are presented. Synthesized under special conditions, samples of BiSrCa((1-x)CuO+xCu))/sub 2/Oy with x=(0.2-0.3) revealed T/sub c/(R=0)=(102-107)K and consisted of the single superconducting phase Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/. The other impurity phases were not superconductors.         Compatibility of Nd and Ba in YBa/sub 2/Cu/sub 3/O/sub y/ superconductor    W.H. Tang and J. Gao Summary: A series of samples with nominal compositions of YBa/sub 2-x/Nd/sub x/Cu/sub 3/O/sub y/ were prepared by solid state reactions and investigated by X-ray diffraction, magnetic and electrical measurements. The solubility, x, was determined to be x<0.25. It is found that the solubility of rare earth Re ions at the Ba-sites in Re/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub y/ is strongly related to a geometric parameter, the tolerance factor t. For x<0.25, T/sub c0/ are all above 92 K. For x>0.3 T/sub c0/ drops sharply to about 84 K, and finally for x=0.5 T/sub c//sup on/ falls to 30 K and T/sub c0/ is below 10 K. Our results suggest that the small compatibility of Nd and Ba in YBa/sub 2/Cu/sub 3/O/sub y/ system does not seriously suppress the superconductivity.         Coupled-grain/RSJ series array for modeling of nonlinear microwave surface impedance of YBCO thin films    J.S. Herd, D.E. Oates, Hao Xin and S.J. Berkowitz Summary: The nonlinear microwave impedance of YBCO thin films may be due to Josephson-junction-like defects. In this work, high-T/sub c/ thin films are modeled as a series of ideal superconducting grains coupled by resistively shunted Josephson junctions that simulate the defects. The model calculates the surface resistance and reactance as a function of microwave current. Comparisons with experimental results from YBCO thin-film stripline resonators show good quantitative agreement for resistance at frequencies in the range 1-6 GHz and at several temperatures. Long junction effects are proposed to explain deviations between measured and computed results above 6 GHz. We have also modeled a phase-shifting device consisting of 300 high-T/sub c/ Josephson junctions in series along a microstrip transmission line. Computed results are in good quantitative agreement with the measured device phase shift versus microwave input power. Similarities in the power dependencies of the series array of junctions and the patterned film resonators are discussed.         Non-linear microwave surface impedance of epitaxial HTS thin films in low DC magnetic fields    A.P. Kharel, K.H. Soon, J.R. Powell, A. Porch, M.J. Lancaster, A.V. Velichko and R.G. Humphreys Summary: We have carried out non-linear microwave (8 GHz) surface impedance measurements of three YBaCuO thin films in dc magnetic fields H/sub dc/ (parallel to c axis) up to 12 mT using a coplanar resonator technique. In zero dc field the three films, deposited by the same method, show a spread of low-power residual surface resistance, R/sub res/ and penetration depth, /spl lambda/(T=15 K) within a factor of 1.9. However, they exhibit dramatically different microwave field, H/sub rf/ dependences of the surface resistance, R/sub s/, but universal X/sub s/(H/sub rf/) dependence. Application of a dc field was found to affect not only absolute values of R/sub s/ and X/sub s/, but the functional dependences R/sub s/(H/sub rf/) and X/sub s/(H/sub rf/) as well. For some of the samples the dc field was found to decrease R/sub s/ below its zero-field low-power value.         A technique for high-power microwave diagnostics of large-area homogeneous HTS films    A.N. Reznik, A.K. Vorobiev, S.A. Pavlov, A.E. Parafin, V.A. Isaev and K.P. Gaikovich Summary: A new technique and measuring equipment for determination of the dependence of HTS surface resistance on a microwave magnetic field amplitude, R/sub s/(H), were developed. The measuring system was an open 36 GHz resonator formed between a spherical metal surface and a flat HTS film. The microwave scheme included a high-power pumping wave circuit and a spectrally separated low-power diagnostic signal circuit. The H structure inhomogeneity on the HTS surface was taken into account. Measurements of the averaged surface resistance have shown it to be related with R/sub s/(H) by the integral equation. The technique for solution of the integral equation based on the Tikhonov method extended from the theory of incorrect inverse problems was applied. Some results of R/sub s/(H) measurements for large-area (>35 mm) YBCO films deposited onto NdGaO/sub 3/, LaAlO/sub 3/ substrates are presented and discussed.         Evaluation of microwave complex conductivities of YBCO thin films by weakly coupled grain model    K. Yoshida, S. Nishioka, H. Morita, Y. Kanda, H. Shimakage and Z. Wang Summary: A self consistent method for evaluating the complex conductivities of high Tc superconducting Y-Ba-Cu-O(YBCO) thin films has been studied using the coplanar waveguide resonator technique. In order to evaluate the magnetic penetration depth precisely, we measured the temperature dependence of the resonant frequency and compared it with the numerical results self consistently. In the present experiments the observed temperature dependence of the complex conductivities is shown to be able to distinguish the effects of the weaklink from the intrinsic property of the grain of an epitaxial thin film and demonstrate the weakly coupled grain model of YBCO thin films.         Modelling the nonlinear high-frequency response of a short Josephson junction under two-frequency irradiation    A.V. Velichko and A. Porch Summary: The nonlinear response of a short Josephson Junction (JJ), being irradiated simultaneously with two high-frequency signals, has been studied in the framework of the nonlinear Resistively-Shunted Junction (RSJ) Model. One of the signals, hereafter referred to as "probe signal", has a small amplitude I/sub pr/         Fields and losses in high T/sub c/ conductors    A.M. Campbell Summary: The hysteresis losses in simple shapes and wires are reasonably well understood. Transport losses in tapes follow the Norris equation well. However it is not clear how cables should be treated since agreement with both a cylindrical model and an isolated tape model have been reported. Coupling losses depend on whether the tapes are insulated. If the layers are in contact current distributes itself over a few centimetres length to minimise the central field. For currents close to I/sub c/ the resistance must be taken into account. Changes in spacing between layers lead to significant redistribution, and losses due to the field from other phases could be large. A continuous change of pitch allows current to penetrate to the centre without cutting filaments.         Angular dependence of AC losses at power frequencies for a stack of Bi2223/Ag tapes    T. Chiba, Q. Li, S.P. Ashworth, M. Suenaga and P. Haldar Summary: AC losses for a stack of Bi2223/Ag mere determined as a function of the angle between the applied AC magnetic field and the tape face. The results were compared with the AC losses calculated using the Bean critical-state model. Although general qualitative behavior of the calculated as a function of the angle was in accord with measured values, the model failed significantly quantitative predictions of the losses.         The analysis of current distributions in filamentary conductors: the influence of intergrowths    A.V. Volkozub, J. Everett, G. Perkins, P. Buscemi, A.D. Caplin, M. Dhalle, F. Marti, G. Grasso, Y.B. Huang and R. Flukiger Summary: Filament isolation is an extremely important factor in multi-filament conductors. However, filament-bridging superconducting intergrowths have often been observed. We show from magnetisation, transport and Hall probe experiments on a range of BSCCO-2223 conductors that the effects of filament bridging are substantial. We infer that the critical current densities within the intergrowths, and also across their grain boundaries, are extremely high.         Filament bridging and critical current density variation in the cross-section of multifilamentary Bi-2223/Ag tapes    M. Polak, M. Majoros, A. Kasztler and H. Kirchmayr Summary: We calculated magnetic fields in the vicinity of model multifilamentary Bi-2223/Ag tapes carrying magnetisation currents with a constant critical current density. The profiles of the perpendicular component of the magnetic field, B/sub mz/, in the lateral direction for the model tape without superconducting interconnections (bridging) and those for the model tape with filament bridging are very different. Experimental results on real tapes qualitatively agree with the calculations. Direct measurements of the filament critical current distribution in 2 of 3 measured tapes showed that the filament critical current, J/sub fc/, was the highest in the tape centre.         Novel resistive interfilamentary carbonate barriers in multifilamentary low AC loss Bi(2223)-tapes    W. Goldacker, M. Quilitz, B. Obst and H. Eckelmann Summary: Reducing the coupling losses, one component of the AC losses in BSCCO tapes, a novel idea for a conductor geometry was developed introducing resistive layers of strontium carbonate in the matrix. Two different preparation methods were applied to introduce the layers in the interfilamentary section, a dip coating technique and a double tube method. Additionally a new ring bundle technique for multifilamentary Bi(2223)-tapes was developed based on a tape composite structure similar to a Rutherford cable with the possibility of realizing practically fully transposed filaments and with a central resistive strontium carbonate core. The achieved current densities of 10 kAcm/sup -2/ with a twist pitch of 10 mm qualifies this new conductor as a very promising alternative concept. We report on the preparation method and the superconducting properties of those tapes.         The effect of self-field on current capacity in Bi-2223 composite strands    S. Spreafico, L. Gherardi, S. Fleshier, D. Tatelbaum, J. Leone, D. Yu and G. Snitchler Summary: We have investigated the effect of aspect ratio and current on the self-field critical current of Ag-sheathed Bi-2223 composite tapes. We have fabricated assemblies of monofilament tapes with different aspect ratio and current capacity. In such a manner, we could study the effect of the composite geometry on the self-field suppression of the critical current while maintaining the quality of the superconducting filaments constant. We find that a large aspect ratio is favorable for achieving higher self-field critical currents which is consistent with a reduction of the self-field. We have also used a modified configuration of several tapes with opposing currents to reduce the perpendicular component of the self field. As a consequence, we have observed large enhancements of the critical current at zero applied magnetic field, and have also been able to reveal the magnetic field dependence of the critical current at low magnitudes of the external field where the self-field usually dominates the externally applied field. We have studied these effects in several tapes with different levels of current capacity.         Fabrication of twisted multifilamentary BSCCO 2223 tapes by using high resistive sheath for AC application    Jaimoo Yoo, Jaewoong Ko, Haidoo Kim and Hyungsik Chung Summary: For the application of high Tc superconductor to electric power systems, it is essential to reduce AC losses of BSCCO 2223 tapes. Different twist pitches of multifilamentary BSCCO 2223 tapes using high resistivity sheath were fabricated to investigate the effect of twist pitches on the microstructure and critical current property, as well as to study the possible use of these conductors for AC application. The J/sub cr/ values of 10 mm and 5 mm twisted tapes drop faster than that of untwisted and 20 mm twisted tapes under increasing magnetic field, especially in low field regime (0/spl sim/0.03 T). It suggests that weak links in the former are more serious than in the latter, which is in accordance with the microstructure analysis.         Sensor-based MOCVD for the growth of low surface resistance YBCO on MgO enabling Q's in excess of 100000    J. Musolf and E.J. Smith Summary: Today MOCVD, due to its inherent advantages such as scaleability and throughput, is the growth technique of choice for many compound semiconductors as a production method. However, the use of MOCVD to deposit high quality HTS material has been impeded by the lack of stable precursors. To overcome the problems of limited process reproducibility caused by these shortcomings, real time control of the gas phase composition by ultraviolet absorption sensors has been utilized. This technique allows for a very tight control of the composition of the deposited material. A surface resistance R/sub s/ lower than 250 /spl mu//spl Omega/ (77 K, scaled to 10 GHz) could be measured on 700 nm thick MOCVD YBCO films. This value correlates very well with the surface resistance extracted from measurements of the quality factor Q/sub 0/ of a simple microstrip resonator used as a process control monitor. Consistent surface resistance values below 350 /spl mu//spl Omega/ prove the reproducibility of the sensor based MOCVD approach. For cellular telecommunication devices at 845 MHz quality factors Q/sub 0/ in excess of 100,000 at 77 K are indicative of the excellent material quality.         Microstructure and microwave surface resistance of YBaCuO thin films    G. Kastner, C. Schafer, S. Senz, D. Hesse, M. Lorenz, H. Hochmuth, M. Getta, M.A. Hein, T. Kaiser and G. Muller Summary: Epitaxial YBaCuO thin films on 73 mm diam. sapphire and 50 mm LaAlO/sub 3/ wafers prepared for microwave applications were characterized by optical and electron microscopy as well as by X-ray diffraction in order to guide optimizing the film properties. The surface resistance R/sub s/, measured at 8.5, 19 or 145 GHz, partially as a function of microwave field amplitude B/sub s/, was taken as the key parameter. Typical results scaled quadratically in frequency to 0.25-0.75 m/spl Omega/ at 10 GHz, 77 K, and low field levels. In case of sapphire substrates, a challenge for applications is microcracking of the films. However, cracks are less deleterious if "dispersed" by other heterogeneities such as a-oriented grains. Narrow microcracks should allow for tunnel currents and flux pinning. In case of LaAlO/sub 3/, films sensitive to high microwave power exhibited some in-plane rotational misorientation and a-oriented grains as well as inhomogeneous layering of these grains and of additional Cu-O planes within the film thickness, with possible influence on R/sub s/.         Microstructure and RF property correlation in HTS films    P.A. Smith, M.A. Bakar, A. Porch and T.W. Button Summary: In this paper we report on the assessment of a range of HTS thick and thin films using a small dielectric resonator, operating near 10 GHz, capable of measuring film areas approximately 3 mm in diameter. This is achieved with the utilisation of high permittivity rutile dielectric resonators operating in the TE/sub 01/spl delta// mode which have a permittivity of approximately 105 at 77 K. Some HTS thick films have well-defined grains which are larger than the measurement area, and thus the influence of grain boundaries and other microstructural features on the RF properties of the films can be quantified directly. The dielectric loss of the rutile at 8 GHz was measured and the housing losses due to the normal copper enclosure were calculated by Superfish, a finite difference programme for the solution of modes with cylindrical symmetry.         Measurement of the absolute penetration depth and surface resistance of superconductors using the variable spacing parallel plate resonator    V.V. Talanov, L.V. Mercaldo and S.M. Anlage Summary: We have developed a modified Parallel Plate Transmission Line Resonator with a smoothly variable thickness of the dielectric spacer filled by liquid nitrogen. A cryogenic linear stage is made to vary the spacer from 200 /spl mu/m down to contact with 0.1 /spl mu/m resolution. Estimates of the absolute penetration depth and the surface resistance are based on the analysis of the spacer thickness dependencies of the resonator frequency and Q-factor. The measurements are performed at fixed temperature (77 K), so the result does not depend on an a priori model for the temperature dependence of the penetration depth. The ability of this technique to be employed as a standard for characterization of HTS films for microwave applications is pointed out.         Surface resistance of Bi-2212 films fabricated by multitarget sputtering    J. Otsuka, K. Ohbayashi, Y. Sugihara, T. Senzaki, M. Yoshida, M. Inoue, A. Fujimaki and H. Hayakawa Summary: We investigated the surface resistance of Bi-2212 films fabricated by the multitarget sputtering method. The surface resistance was not dependent on the product of the grain size and the critical current density, although many high temperature superconductors such as Y-Ba-Cu-O agree with such a weak-link model. Therefore, it is possible that the conduction losses are relatively low at grain boundaries in Bi-Sr-Ca-Cu-O. On the other hand, it was found that the intergrowth of Bi-2212 with Bi-2201 or Bi-2223 influenced the surface resistance badly. This is very interesting, although it has never been clarified as to why the surface resistance is dependent on the intergrowth. Further study will be required in order to interpret the behavior of the surface resistance of BSCCO.         Observation of vortex movement in oxide superconductors by means of the Bitter pattern technique    S. Ohshima, A. Kamimura and M. Kusunoki Summary: The high-resolution Bitter pattern technique has been used to observe vortex movement of oxide superconductors, Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 2/ (Bi2212). The Bitter pattern was observed in field-cooled (FC) and zero-field cooled (ZFC) experiments. We also examined vortex movement of the Bi2212 single crystal in which transport current was applied parallel to the c plane, and a dc magnetic field applied normal to the c plane at the Ni decoration. The Ni decoration pattern was observed using a scanning electron microscope (SEM) and an atomic force microscope (AFM). Through observation of the Ni decoration pattern, we can identify vortex movement. The vortices moved into the sample on FC experiment, and the direction of vortex movement was approximately normal to the edge of the sample. We also found the vortex movement in a line under application of transport currents. They moved hopping among pinning centers due to Lorentz force.         Flux flow of La-Sr-Cu-O single crystals    T. Tachiki, K. Nakajima, T. Yamashita, I. Tanaka and H. Kojima Summary: We measured voltages across micro-bridges fabricated along the c-axis of La/sub 2-x/Sr/sub x/CuO/sub 4/ single crystals under an external magnetic field. A sharp voltage peak appears when the magnetic field was aligned to the ab plane within a few degrees. The vortex velocity estimated from the maximum voltage is much lower than the velocity that was measured in Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ single crystals. If many weak point-like pinning centers are assumed to be in the sample, the angular dependence of the voltage is explained by the collective flux creep model.         Influence of demagnetizing effects in superconducting cylinders    A. Sanchez and C. Navau Summary: We present a model that allows one to calculate magnetization curves for superconducting cylinders with an arbitrary aspect ratio. The model is based on magnetic energy minimization and can be applied to superconducting cylinders in any axially symmetric applied magnetic field. The dependence of current and field profiles and magnetization curves upon the sample aspect ratio is studied. Results are in agreement with the existing theories for the two limiting cases that can be calculated analytically: infinitely long cylinders and thin disks.         Flux creep and irreversibility line in superconducting Pb-Bi alloys    A. Matsuda, T. Muranaka, T. Akune and N. Sakamoto Summary: The critical current density, J/sub c/, in high-temperature superconductors becomes zero at irreversibility field, B/sub irr/, appreciably lower than the upper critical fields, B/sub c2/. The enhancement of J/sub c/ and B/sub irr/ is one of the crucial subjects to be attained. In high-temperature superconductors, conclusive result has not yet been presented because of the complexity of the material structure and in low-temperature superconductors scientific interest has not been paid because of the vanishingly small deviation of B/sub irr/ from B/sub c2/. In this study, we'll apply a simple system of low-temperature superconductor Pb-Bi, whose pinning characteristics were fully examined and controllable, to understand the relation of B/sub irr/ and the pinning mechanism. Observed irreversibility field, B/sub irr/, is discussed using the pinning characteristics and numerical calculation based on the flux creep theory. Magnetic relaxation caused by the flux creep was also observed by SQUID magnetometer. The relation of the apparent pinning potentials, U*/sub 0/, estimated from the flux creep rate and the irreversibility field, B/sub irr/, are studied.         Anisotropic transport property in Type-II superconductors with planar pinning centers and anisotropic viscosity of vortex motion    Y. Mawatari Summary: We investigate anisotropic resistivity due to planar pinning centers and to anisotropic viscosity of vortex motion, taking account of Hall effects. Because of the anisotropy of pinning and viscosity, both longitudinal resistivity /spl rho//sub /spl par// (induced parallel to a transport current J) and transverse resistivity /spl rho//sub /spl perp// (perpendicular to J) depend on an angle /spl theta/ between the direction of J and the pinning planes. The /spl theta/ dependence of the resistivities is affected by the anisotropy of viscosity, pinning strength, and Hall effects. It is found that /spl rho//sub /spl par// and /spl rho//sub /spl perp// can be enhanced by the pinning effects.         Nonlinear flux diffusion in superimposed weak AC magnetic field    A.L. Kasatkin, V.V. Vysotskii, V.M. Pan and H.C. Freyhardt Summary: The influence of superimposed weak ac magnetic field on flux creep and relaxation phenomena is studied theoretically for a superconducting slab in superimposed dc and weak ac magnetic fields parallel to the slab surface. Nonlinear flux diffusion equations are solved with appropriate periodical boundary conditions, which describe the influence of the ac field component. The flux creep rate and magnetization decay are enhanced by the ac field as a result of rather strong nonlinearity of flux diffusion. The long-time relaxation profiles of electric field and shielding current change significantly as compared to the well-known stationary solutions in the absence of ac field. These results reflect rather general properties of nonlinear systems, namely the possibility of the large effect of small perturbations on the long-time behavior of a nonlinear system.         Flux pinning mechanism for Nd-Ba-Cu-O superconductor    H. Wu and S.S. Wang Summary: Unlike YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (Y123) which is a line compound for the cations, the Nd-Ba-Cu-O superconductor forms a solid solution Nd/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub 7-/spl delta// (Nd123ss) between Nd and Ba. The presence of such a solid solution tends to cause a depression of the superconducting transition temperature (T/sub c/) and a broad transition. Processing in a low oxygen partial pressure (Po/sub 2/) can produce a high T/sub c/ and enhanced critical current density (J/sub c/). However, there are controversies on flux pinning mechanisms for this material, In this paper, we investigated the upper solubility limit of Nd123ss in industrial argon and critically reviewed these flux pinning mechanisms on the basis of a phase transformation theory. We believe that precipitation mechanism based on the change of the solubility limits of Nd123ss with Po/sub 2/ offers a consistent explanation to the enhanced flux pinning in the system. This may provide guidelines for further improvement in superconducting properties of bulk 123 materials.         Influence of microcracks and anisotropic conductivity on critical current and exponent n in silver-sheathed HTS tapes    J. Paasi and A. Korpela Summary: The influence of filament non-uniformities (microcracks) and anisotropic conductivity on critical current and exponent n of the current-voltage characteristic of HTS/Ag tape conductors was studied numerically by the means of the finite element method. According to the results, non-uniformities reduce the critical current of the conductor, the reduction by a crack being higher in the cases of anisotropic than isotropic conductivity, but their influence on exponent n is negligible. The result suggests that the low n-values of HTS/Ag conductors are due to intrinsic effects such as thermally activated flux creep.         Very high trapped field in melt-processed Sm-Ba-Cu-O    H. Ikuta, A. Mase, U. Mizutani, Y. Yanagi, M. Yoshikawa, Y. Itoh and T. Oka Summary: We prepared c-axis oriented Sm-Ba-Cu-O bulk-superconductors by the melt-process technique in a reduced oxygen atmosphere. We particularly studied the effect of Ag addition to the composite in the present work, because Ag was found to greatly suppress the formation of macro-sized cracks in our earlier works. The samples were evaluated by measuring the residual magnetic flux density after field-cooling the samples. The trapped-field distributions mapped at 77 K show that samples with 10 or more wt.% Ag/sub 2/O consist of a single domain with no severe weak-links. The trapped magnetic flux density at the open surface of a sample with 20 wt.% Ag/sub 2/O and 30 mm in diameter was 8.0 T at 40 K. It was also found that the addition of Ag affects the microstructure of the sample and the distribution of the Sm/sub 2/BaCuO/sub 5/ phase was more homogeneous in samples with larger amount of Ag.         Numerical study of the frequency and temperature dependence of the ac magnetic susceptibility in presence of a static magnetic field in HTS    D. Di Gioacchino, P. Tripodi, F. Celani, A.M. Testa and S. Pace Summary: The temperature dependence of the harmonics (/spl chi//sub n/) of the ac magnetic susceptibility in HTS have been investigated by numerical solutions of the non linear diffusion equation for the magnetic flux. Within the framework of the collective pinning model, we show that the transition between different regimes for the flux dynamics (taff, creep, flow) is determined by the field frequency for a fixed dc field, or by the dc field for a fixed frequency. As a consequence, a non universal behavior arises for the temperature dependence of /spl chi//sub n/. In particular, in this approach the frequency dependencies of both amplitude and temperature of the peak of the imaginary part of the first harmonic and of the modulus of the third harmonic are discussed.         Hidden network of long Josephson junctions as a source of strong pinning mechanisms in high temperature superconducting films    E. Mezzetti, E. Crescio, R. Gerbaldo, G. Ghigo, L. Gozzelino and B. Minetti Summary: In the hypothesis that good quality high temperature superconducting (HTS) films can be modeled as an agglomeration of islands coupled via Josephson contacts, we calculate the critical current density J/sub c/ vs. field in a long Josephson junction (LJJ). The coupling energies in the junction are modulated by defects with given distribution and size. The superconductor is then considered as a network of LJJ between superconducting islands. Each LJJ has a different defect distribution. The model accounts for all main trends of the experimental electromagnetic behavior. The most important issue is that a "hidden" network of LJJ with a suitable distribution of optimized defects is the source of high critical current density in "good quality" films. Therefore any needed response of the film in a given range of field can be designed in advance.         Magnetic field induced texture in high-Tc superconductors    P.J. Ferreira, H.B. Liu and J.B. Vander Sande Summary: Bi-2212 superconductor thick films and tapes were melt-grown under a zero and 10 T magnetic field. In the latter case the degree of alignment and consequent transport critical current densities were enhanced. Melt-processing tapes or thick films in a 10 T magnetic field seems to produce uniformly textured grains throughout a large thickness. A theoretical model developed to quantify the degree of texture achieved during various processing conditions suggests that the degree of alignment is obtained through grain rotation during the early stages of grain growth from the liquid.         Interaction between a permanent magnet and an HTS trapped field magnet    Y. Postrekhin, K.B. Ma, J.-H. Yu and W.-K. Chu Summary: High temperature superconductor trapped field magnets were made out of disks of melt-textured YBa/sub 2/Cu/sub 3/O/sub 7/ prepared by the seeded directional solidification method. It is shown that the force between the magnet and the HTS trapped field magnet depends on the polarity of the frozen magnetic field and can be positive or negative. The levitation force between a magnet and a trapped field magnet is compared with that between the same magnet and a high temperature superconductor without trapped flux under zero field cooled condition. The stability of a levitation system based on the trapped field magnets has been investigated by studying the amplitude-frequency characteristics of the system where a permanent magnet is attached to a soft cantilever beam and placed above the trapped field magnet.         YBCO-coated conductor on buffered textured metallic tape by hot-wall type MOCVD    M. Hasegawa, Y. Yoshida, K. Matsumoto, I. Hirabayashi, M. Iwata, Y. Takai, H. Akata and K. Higashiyama Summary: We have prepared YBa/sub 2/Cu/sub 3/O/sub 7-y/ thin films on {100}<001> cube textured Ag tape (CUTE-Ag tape) by metal organic chemical vapor deposition (MOCVD). The obtained films are highly c axis oriented, and the surfaces of the films were smooth. However, the in-plane alignment of the films was not pure four-fold symmetric. Then we examined preparation of YBCO films on Y/sub 2/O/sub 3/ buffered CUTE-Ag tapes. The Y/sub 2/O/sub 3/ layer was deposited by MOCVD and the YBCO films on that layer was c axis oriented with good in-plane alignment. Furthermore after the YBCO films growth was terminated, the peak of Y/sub 2/O/sub 3/ almost disappeared. We considered that the Y/sub 2/O/sub 3/ layer was incorporated into the YBCO film during deposition. We also deposited YBCO films on {110}<001> textured Ag tape for which good in-plane alignment of YBCO film was expected from the near-coincidence site lattice (NCSL) model. The critical temperature of both YBCO films on the CUTE-Ag tape and on the {110}<001> textured Ag tape were T/sub c(zero)/=80 K.         Large area YBCO films on polycrystalline substrates with very high critical current densities    M. Bauer, R. Semerad, H. Kinder, J. Wiesmann, J. Dzick and H.C. Freyhardt Summary: We deposited large-area YBCO films by reactive thermal co-evaporation on biaxially textured, Y/sub 2/O/sub 3/ stabilized ZrO/sub 2/ (YSZ) buffer layers fabricated by an IBAD technique (ion beam assisted deposition). Polycrystalline, partially stabilized ZrO/sub 2/ (PSZ) with a size of 10/spl times/10 cm was used as a substrate. Homogeneous, biaxially aligned IBAD buffer layers were prepared by using large ion guns and substrate rotation during the IBAD process. YBCO films with thicknesses of up to 1400 nm were deposited. The biaxial alignment of the buffer layer and of the YBCO film was characterized by X-ray diffraction. The FWHM of YSZ [111] /spl phi/-scans varied laterally within a range of 15/spl deg/ to 20/spl deg/. The FWHM of the YBCO [103] was always several degrees better with value of only 7/spl deg/ to 9/spl deg/. The YSZ thickness dependence of this improvement was analyzed. We achieved a mean critical current density of 1.9 MA/cm/sup 2/ and a maximum critical current density of 2.1 MA/cm/sup 2/ on a substrate area of 10/spl times/10 cm.         YSZ buffer layers on large technical substrates    J. Dzick, J. Wiesmann, J. Hoffmann, K. Heinemann, F. Garcia-Moreno, A. Isaev, H.C. Freyhardt and W. Lechner Summary: The ion-beam-assisted deposition (IBAD) of yttria-stabilized zirconia (YSZ) films was extended to large technical substrates such as ceramic plates, metallic tapes and metallic tubes to serve as templates for high-current carrying Y-Ba-Cu-O films. These YSZ films are deposited with dual-Kaufman-ion-source equipment. The coating of technical substrates large in comparison to the ion sources requires special measures to provide YSZ films of homogeneous texture quality. With respect to the special growth mechanism of YSZ, a homogenization of the in-plane texture can be achieved by simple movement of the substrate. Up to now we have been able to produce YSZ films on ceramic substrates (10 cm/spl times/10 cm) with a homogeneous in-plane texture of 17/spl deg/ FWHM and on a Ni-tape (1 cm/spl times/50 cm) with a FWHM of 21/spl deg/. The main aspects of the growth mechanism-the influence of the nucleation, the improvement of texture with increasing film thickness and homoepitaxial effects-and the surface morphology are investigated in detail with transmission electron microscopy (TEM) and atomic force microscopy (AFM).         Fabrication of biaxially textured Ni substrates and LaNiO/sub 3/ buffer layers for Tl-1223 thick films    T.A. Gladstone, J.C. Moore, A.J. Wilkinson and C.R.M. Grovenor Summary: We have fabricated cube texture nickel substrates and examined the relationship between percentage rolling deformation and annealing conditions on the degree of texture obtained using XRD and EBSD techniques. We have found that unaligned grains may be avoided by rolling to 95% reduction and annealing at 800/spl deg/C for 4 hours. We have fabricated LaNiO/sub 3/ films on YSZ and lanthanum aluminate by spray pyrolysis and achieved cube texture in thin coatings.         Development of biaxially aligned buffer layers on Ni and Ni-based alloy substrates for YBCO tapes fabrication    T. Petrisor, V. Boffa, G. Celentano, L. Ciontea, F. Fabbri, U. Gambardella, S. Ceresara and P. Scardi Summary: This paper presents the development of the CeO/sub 2/ buffer layers on both the non magnetic Ni-V and the Pd-buffered Ni substrates by pulsed laser ablation (PLD). The CeO/sub 2/ films show strong in-plane and out-of-plane orientations. The SEM studies showed that the CeO/sub 2/ films are both smooth and continuous. The magnetic and structural properties of the new Ni-V substrate are also presented. The results demonstrate that Ni-V is an alternative substrate for the fabrication of textured YBCO conductors.         Laser deposition of YBCO on long-length technical substrates    F. Garcia-Moreno, A. Usoskin, H.C. Freyhardt, A. Issaev, J. Wiesmann, J. Hoffmann, K. Heinemann, S. Sievers and J. Dzick Summary: YBCO films with a high-quality in-plane texture have been grown on different Ni, yttria-stabilized zirconia (YSZ) and stainless steel (SS) substrates using a modified pulsed-laser deposition technique. A biaxially textured buffer of YSZ grown by ion-beam-assisted deposition was employed as a template for the YBCO film as well as a diffusion barrier. X-ray and TEM analyses were employed to understand the growth mechanisms. For short Ni substrates (10/spl times/10 mm), critical current densities J/sub c/ up to 2 MA/cm/sup 2/ (at 77 K, 0 T) were observed. Long YBCO coated samples with lengths up to 0.5 m were manufactured on Ni tapes (10 mm wide) and tubes (r=4-7 mm). Contactless measurements of the critical parameters were provided by a third-harmonic method. By bending experiments of YBCO films with external strain loading, J/sub c/ was found to be reversible in the range of strains between -0.5% and +0.5% under tension and compression, with a pronounced maximum under compressive strains.         CeO/sub 2/ buffer layers for YBCO: growth and processing via sol-gel technique    E. Celik, J. Schwartz, E. Avci, H.J. Schneider-Muntau and Y.S. Hascicek Summary: In this study, the processing and growth mechanisms of CeO/sub 2/ buffer layers were evaluated on Ni substrates for YBCO superconductor. The sol-gel technique was utilized to produce buffer layers from six different Ce based precursor materials. The microstructure, phase composition and formation of buffer layers were characterized by means of ESEM, SEM, EDS, XRD, pole figure XRD and DTA techniques. The results indicated that the CeO/sub 2/ formation starts at temperature of 420/spl deg/C. It was found that the best crack free CeO/sub 2/ thin films were obtained by using Ce(NO/sub 3/)/sub 3//spl middot/6H/sub 2/O and colloidal CeO/sub 2/ based precursor materials. Different anions and their concentrations also influenced the structure of thin films.         Optimization of buffer layers on rolled-Ni substrates for high current YBCO and Tl,Bi-1223 coated conductors using ex-situ precursor approaches    M. Paranthaman, D.F. Lee, R. Feenstra, A. Goyal, D.T. Verebelyi, D.K. Christen, E.D. Specht, F.A. List, P.M. Martin, D.M. Kroeger, Z.F. Ren, W. Li, D.Z. Wang, J.Y. Lao and J.H. Wang Summary: High current YBa/sub 2/Cu/sub 3/O/sub 7-y/ (YBCO) and Tl/sub 0.78/Bi/sub 0.22/Sr/sub 1.6/Ba/sub 0.4/Ca/sub 2/Cu/sub 3/O/sub 9-y/ (Tl,Bi-1223) coated conductors were fabricated on Rolling-Assisted Biaxially Textured Substrates (RABiTS) with a layer sequence of CeO/sub 2//YSZ/CeO/sub 2//Ni. The top and bottom CeO/sub 2/ (Cerium oxide) layers were deposited epitaxially on textured-Ni [100] substrates using reactive evaporation of Ce metal. The thickness of the CeO/sub 2/ films was 200-400 /spl Aring/. The YSZ (Yttria Stabilized Zirconia) layers were also deposited epitaxially on CeO/sub 2/-buffered Ni substrates either by rf magnetron sputtering or e-beam evaporation. The thickness of the YSZ films was typically 3000-9000 /spl Aring/. The e-beam CeO/sub 2/ films were dense, crack-free and columnar. The microstructure of sputtered YSZ was dense and the e-beam deposited YSZ was porous. To understand the stability of these buffer layers, the as-grown CeO/sub 2/-buffered YSZ (both sputtered and e-beam)/CeO/sub 2//Ni substrates were annealed in a controlled oxygen furnace at various temperatures. RBS studies indicate that the YSZ sputtered films were quite stable up to 780/spl deg/C and 200-mTorr oxygen. For e-beam YSZ films, there was an indication of diffusion of oxygen through these buffers into the Ni substrate. The Tl,Bi-1223 films were grown on all e-beam buffers using pulsed laser ablation of precursor films followed by post-annealing. The YBCO films were grown on e-beam/sputtered buffers using e-beam co-evaporated Y-BaF/sub 2/-Cu precursors followed by post-annealing.         In-plane alignment of YBa/sub 2/Cu/sub 3/O/sub 7-y/ films realized by CeO/sub 2/ buffer layer on textured Ag{100}<001> tapes    Y. Takahashi, K. Matsumoto, S.-B. Kim, I. Hirabayashi, H. Akata and K. Higashiyama Summary: Homogeneous in-plane aligned YBa/sub 2/Cu/sub 3/O/sub 7-y/ (YBCO) films on long metallic substrates are required for power applications. In order to establish in-plane aligned YBCO films, we have been studying Ag{100}<001> textured tapes buffered with a [001]-oriented CeO/sub 2/ layer. The YBCO and CeO/sub 2/ films were deposited by pulsed laser deposition (PLD). The CeO/sub 2/ deposition rate was 900 /spl Aring//min. The CeO/sub 2/ films on Ag{100}<001> textured substrates mere [100]-oriented and highly in-plane aligned. The YBCO films deposited by PLD on CeO/sub 2/ buffered Ag substrates also have c-axis oriented and good in-plane alignment. T/sub c/ and J/sub c/ values of the YBCO films were 81 K and 1/spl times/10/sup 4/ A/cm/sup 2/ at 77 K, respectively.         Long length fabrication of YBCO on rolling assisted biaxially textured substrates (RABiTS) using pulsed laser deposition    C. Park, D.P. Norton, D.K. Christen, D.T. Verebelyi, R. Feenstra, J.D. Budai, A. Goyal, D.F. Lee, E.D. Specht, D.M. Kroeger and M. Paranthaman Summary: The continuous deposition of multi-layer oxide films on moving long-length metallic substrates using pulsed laser deposition (PLD) is reported. Epitaxial YBCO/CeO/sub 2//yttria-stabilized zirconia (YSZ)/CeO/sub 2/ layers were grown on 1 cm/spl times/10 cm rolled-Ni tape substrates. The Ni tape was heated radiatively and translated while oxide layers were continuously deposited. The thickness and composition along the moving direction were uniform to within /spl plusmn/7% and /spl plusmn/5%, respectively. The biaxial texture of the 10 cm Ni tape was transferred through the buffer layers to the topmost YBCO during the continuous deposition. The in-plane and out-of-plane texturing of YBCO and buffer layers were uniform along the scanning direction with variations less than /spl plusmn/10% and /spl plusmn/5%, respectively. The average transport zero field J/sub c/ (77 K) for numerous 10 cm samples was about 200,000 A/cm/sup 2/, with the highest J/sub c/ and I/sub c/ values at 77 K, 0 T of 270,000 A/cm/sup 2/ and 16.7 A respectively. This study demonstrates the feasibility of continuous multilayer, multi-component oxide film deposition on rolled-textured metal with uniform thickness, composition, and crystallographic orientation using PLD.         Preparation and characterization of Y/sub 2/O/sub 3/ buffer layers and YBCO films on textured Ni tape    A. Ichinose, G. Daniels, C.-Y. Yang, D.C. Larbalestier, A. Kikuchi, K. Tachikawa and S. Akita Summary: The direct deposition of Y/sub 2/O/sub 3/ buffer layers on cube-textured nickel tape was successfully performed by electron beam deposition using Y metal which oxidized during deposition. The Y/sub 2/O/sub 3/ layer exhibited excellent out-of-plane alignment of FWHM of 2.3/spl sim/4/spl deg/ and good in-plane alignment with /spl sim/11/spl deg/ FWHM. Surface morphology, crystal orientation and grain size proved to be quite sensitive to the deposition pressure. The surface roughness and the grain size increased with increasing deposition pressure, and the crystal orientation changed from [111]Y/sub 2/O/sub 3/ to [100]Y/sub 2/O/sub 3/. Subsequently, YBCO superconducting films were deposited on [100]Y/sub 2/O/sub 3/ buffer layers by co-evaporation deposition and pulsed-laser deposition (PLD). Though a good in-plane alignment, as measured by X-ray /spl phi/-scan, was achieved in the YBCO films, their superconducting characteristics were not so good. The T/sub c/ onset was about 84 K for the [001]YBCO by PLD. The crystal alignment and the microstructure of YBCO superconducting films deposited by the two deposition techniques on cube-textured Ni tapes with Y/sub 2/O/sub 3/ buffer layers are compared.         Thick film biaxially textured YBCO coated tape conductors prepared using magnetic grain alignment    M. Staines, J.-Y. Genoud, A. Mawdsley and V. Manojlovic Summary: We report a new approach to the preparation of biaxially textured YBCO coated tape conductors. Using a dynamic magnetic grain alignment technique, a biaxially aligned dispersion of orthorhombic Y-247 powder is settled on untextured silver substrates. In subsequent heat treatment the Y-247 is transformed to Y-123 and CuO involving a partial melt. Critical current densities at 77 K in self-field of up to 5000 A/cm/sup 2/ have been obtained in films from 10 to 30 /spl mu/m thick. There is a clear enhancement of J/sub c/ relative to identically prepared untextured or uniaxially textured samples. J/sub c/ appears to be limited at present by the difficulty of achieving fully densified films while retaining biaxial texture. Provided significant improvements in J/sub c/ can be obtained this method offers an alternative to coated tape processes based on epitaxial growth which does not demand textured substrates and can give much higher fill factors. The grain alignment technique is quite general for materials with anisotropic magnetic or electric susceptibility and can therefore be utilised in a wide range of applications.         HTS wire irradiation test with 8 GeV protons    S. Feher, H. Glass, Y. Huang, P.J. Limon, D.F. Orris, J. Ozelis, P. Schlabach, M.A. Tartaglia and J.C. Tompkins Summary: The radiation level at High Energy Particle Accelerators (HEPA) can be high enough to damage electronic devices. Any active component near the accelerator must be radiation resistant. Since High Temperature Superconductors (HTS) have great potential to be used in HEPAs (e.g., in superconducting magnets, current leads, RF cavities), it is important to understand the radiation hardness of these materials. A radiation test of HTS wire (BSCCO-2223) was performed at Fermilab. The HTS sample was irradiated with 8 GeV protons and the critical current, I/sub c/, was measured during the irradiation. The total radiation dose was 10.8/spl plusmn/1.0 Mrad. No change in I/sub c/ was observed.         Strong vortex pinning by elongated, discontinuous defects in Tl-Ba-Ca-Cu-O films    E.L. Venturini, P. Newcomer Provencio, B.L. Doyle and D.K. Brice Summary: Elongated, discontinuous defects provide strong vortex pinning and a corresponding large increase in critical current density in highly anisotropic Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub x/ (Tl-2212) thin films. We generate controlled, amorphous damage regions in Tl-2212 thin films ranging from short, discontinuous defects to continuous linear tracks using Au ion irradiation with incident energies of 30, 60 and 88 MeV. High-resolution TEM images and magnetization data allow correlation of microstructural damage with changes in the superconducting properties. Furnace annealing of an irradiated film shows that the enhanced pinning is stable to above 600/spl deg/C.         Pinning effect on critical dynamics in Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ films before and after introducing columnar defects    Jin-Tae Kim, Y.K. Park, J.-C. Park, W.N. Kang, C.W. Chu, H.R. Lim, D.H. Kim, J.U. Lee and K.E. Gray Summary: The effect of columnar defects on the critical dynamics of superconducting Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ (Tl-2212) film has been investigated. The Tl-2212 film was irradiated at 0/spl deg/C by 1.3 GeV U-ions along the normal of the film surface. The dose of 6.0/spl times/10/sup 10/ ions/cm/sup 2/ of the U-ion irradiation corresponds to a matching field of 1.2 T. The in-plane longitudinal resistivity of the irradiated Tl-2212 has been measured as a function of magnetic field H and temperature T. The extracted fluctuation part of the conductivity /spl sigma//sub xx/(T, H) of the unirradiated sample exhibits 3D-XY scaling behavior that reveals dynamic critical exponent z=1.8/spl plusmn/0.1 and static critical exponent /spl nu//spl ap/1.338. The results indicate that the weak interlayer coupling along the c-axis of Tl-2212 significantly influences static critical exponent /spl nu/ and does not change dynamical critical exponent. After the irradiation, the fluctuation conductivities are enhanced by the strong pinnings and do not exhibit the same 3D-XY scaling behavior as for the unirradiated Tl-2212. Particularly at the low magnetic field values near the matching field of 1.2 T, the fluctuation conductivities show a clear deviation from the critical dynamics, suggesting that the pinning effect on the critical dynamics is significant.         Neutron irradiation effect on magnetization and thermal conductivity of (Hg/sub 1-x/Bi/sub x/)Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub y/ superconductor    S. Nakamae, J. Crow and J. Schwartz Summary: We have investigated the neutron irradiation effect on a phase-pure (Hg/sub 1-x/Bi/sub x/)Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub y/ superconductor through magnetization and thermal conductivity measurements. It has been found that the inclusion of point-defects from the irradiation lowers the transition temperature and destroys the coupling between neighboring superconducting grains. Such point-defects act as strong flux pinning sites in the mixed state, resulting in the critical current density increase. The thermal conductivity data are used to study the scattering mechanisms between the heat carriers and the point defects in the absence and the presence of magnetic fields.         Pinning of magnetic flux lines in Y-Ba-Cu-O superconductors by neutron irradiation and chemical route    J.K.S. Christiansen, N.H. Andersen and T. Frello Summary: The increase of critical magnetization current due to pinning of magnetic flux lines in Y-Ba-Cu-O superconductors has been investigated. The methods utilized were either irradiation by fast neutrons or addition of yttria inclusions prior to processing. The Y-Ba-Cu-O superconductors were prepared as plates (20 to 40 cm in length) using melt texturing method. Samples were irradiated using doses of 2/spl times/10/sup 21/ to 5/spl times/10/sup 22/ neutrons pr. sq. m. According to magnetization measurements, the critical current density is improved /spl sim/3 and /spl sim/12 times at magnetic fields of 0.07 and 1 tesla respectively. Thus, at 1 tesla the critical current density was improved from 290 to 3500 A/cm/sup 2/ by an irradiation of 1/spl times/10/sup 22/ neutrons/spl middot/m/sup -2/. Addition of yttria results in formation of 1 to 20 /spl mu/m large inclusion of Y/sub 2/BaCuO/sub 5/ in the superconducting material. The critical current characteristics show a peak-effect at 1 to 2 tesla, with critical currents comparable to irradiated samples. Melt textured single crystals have equal high critical current densities at these applied magnetic fields.         Intragranular and intergranular superconducting properties of bulk melt-textured YBCO    Ph. Vanderbemden, R. Cloots, M. Ausloos, R.A. Doyle, A.D. Bradley, W. Lo, D.A. Cardwell and A.M. Campbell Summary: We have investigated the superconducting properties of bulk melt-processed YBCO using different experimental techniques. First, single domain materials (i.e. containing no grain boundaries) have been studied. Electrical resistivity, current-voltage characteristics, M-H loops, and A.C. susceptibility have been measured for different field and current directions. The intragranular properties are characteristic of high-quality melt-processed YBCO material, with a critical current density J/sub c/(T=77 K, B=1 T//c)>10/sup 4/ A/cm/sup 2/. The anisotropy ratio J/sub c/(ab)/J/sub c/(c) is found to be close to 3. Both magnetic and transport measurements show that defects in the microstructure do not significantly impede the current flow inside the single domain. These results were compared to those measured on samples containing one "natural" single grain boundary which sometimes appears during the grain growth process. The intergranular properties show a much stronger current and magnetic field dependence than that measured within the grain and these differences are discussed.         Magnetic field dependence of transport properties of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films on hastelloy substrates with YSZ buffer layers    W.A.J. Quinton, R.A. Doyle, J.D. Johnson, W.Y. Liang and F. Baudenbacher Summary: Biaxially aligned yttria stabilised zirconia (YSZ) buffer layers were deposited on polycrystalline Hastelloy-C substrates using the inclined substrate deposition technique. In-plane aligned, c-axis oriented, YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films were then grown onto these buffer layers. Resistively determined irreversibility lines of these films are presented, as well as critical current densities which have been extracted from measurements of E-J characteristics taken at 77.7 K for fields of up to 7 Tesla aligned either parallel or perpendicular to the ab-plane. Data are also presented showing the resistance as a function of the angle between the field and the c-axis. Strong pinning is observed both for fields parallel to the ab-plane (intrinsic pinning), and for fields parallel to the c-axis; the latter being due to either twin or grain boundaries.         Critical magnetization current density and repulsive force determined by repulsive method    J.K.S. Christiansen, L.G. Andersen, S.L. Frederiksen and J. Mygind Summary: Determination of the critical magnetization current density of large superconducting samples was performed using a levitation force method. It is based on measurement of the force between the superconductor and a permanent Nd-Fe-B magnet, thus the applied magnetic field may be up to /spl sim/0.4 tesla. At this field, levitation forces up to 6.6 N (5.5 MN/m/sup 3/) were measured on melt processed tablets of Y-Ba-Cu-O material with dimensions of /spl sim/2 cm/spl times/2 cm/spl times/0.3 cm.         Magnetic response of Y/Pb doped single-crystal Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+d/ superconductors    S. Tochihara, A. Goto, H. Yasuoka, H. Mazaki, M. Osada and M. Kakihana Summary: The magnetic properties of Y/Pb doped single-crystal Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+d/ have been investigated in terms of the magnetization curves measured using a SQUID magnetometer. The observed results were analyzed within the construct of the modified Kim-Anderson critical-state model, where lower critical fields H/sub cl/ and surface barriers /spl Delta/H were explicitly taken into consideration. Analyses have revealed that the magnetic response is closely correlated to the carrier concentration, and both the lower critical field and the pinning force increase with the increase of the carrier concentration in the CuO/sub 2/ plane.         Harmonic AC susceptibilities on directionally solidified YBaCuO samples    M. Polichetti, S. Pace, A. Vecchione and F. Celani Summary: In order to study the flux lines dynamics on melt textured YBaCuO, the AC magnetic susceptibility harmonics were measured with different frequencies and amplitudes of the AC magnetic field. In particular, we focus attention on the frequency effects on the higher harmonics measured at various AC fields. The analysis of the experimental data was performed by comparing them with the results obtained by a critical state picture and by numerical simulations of the diffusion processes of the magnetic field which determine the AC response in the presence of different regimes of flux dynamics. As the frequency changes, a clear nonuniversal temperature dependence appears in the experimental curves. In qualitative agreement with the numerical results obtained by assuming the existence of dissipation processes as a sequence of independent flux creep and flux flow events within a collective pinning framework.         Intergrain critical current density of Y123 bicrystal films grown by LPE method    T. Takagi, J.G. Wen, T. Machi, K. Hashimoto, Y. Takahashi, T. Morishita, I. Hirabayashi and N. Kosyhizuka Summary: We succeeded in producing Y123 bicrystal films with straight grain boundaries by the LPE method. The Y123 bicrystal films were grown on MgO bicrystal substrates with 24/spl deg/ misorientation angle. TEM images show that the grain boundary consists of straight single facets of about 50 /spl mu/m length. J/sub c/ across the grain boundary at 77 K in zero magnetic field, 1.4/spl times/10/sup 4/ A/cm/sup 2/, was one order lower than that of the intragrain, /spl sim/10/sup 5/ A/ cm/sup 2/. This suppression rate of J/sub c/ in bicrystal films with tilt angle 24/spl deg/ is lower than that in films grown by PVD methods such as PLD. The normal resistance of the intergrain boundary is small, which indicates that the effective width of the straight interface is very narrow.         Flux pinning properties in Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/ single crystals and the effect of introducing nano-size MgO particles    H. Sasakura, O. Miura and D. Ito Summary: The pinning properties in Bi(2212) single crystals prepared by the large temperature-gradient technique are reported in comparison with that of 5% MgO nano-size particle-added Bi(2212) crystals. We studied the scaling of volume pinning force density F/sub p/ to the irreversibility field B/sub irr/ as the scaling field parallel to the c-axis for these Bi(2212) crystals at low temperature from 18 K to 30 K. It was found that for the MgO added-crystals the normalized F/sub p/ was scaled to temperature but for a single crystal no scaling was observed for the irreversible field B/sub irr/ obtained from the field dependence of the irreversibility temperature. When a field B* which gives one percent of the maximum pinning force density F/sub pmax/ was substituted for B/sub irr/, F/sub p//F/sub pmax/ in single crystal scaled with B/B*. We discussed the origin of disagreement between the irreversibility field B/sub irr/ and field B* in a single crystal and the effect of the MgO addition to the Bi(2212) crystal. Critical current of the Bi(2212) crystal in low temperature region could be improved by the 5% addition of the MgO nano-size particles.         Vortex-induced voltage instabilities in a superconducting BSCCO thin film    B. Savo and C. Coccorese Summary: Flux-induced voltage switching events assuming the form of random telegraph signals have been investigated in a current biased Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub 8+x/ (BSCCO) thin film, at weak magnetic fields (<10 G) and at temperatures ranging below 7 K. The observed phenomena cannot be framed within traditional theoretical models. Rather, they strongly indicate two distinct vortex dynamical states at the basis of the switching events. A novel interpretation is proposed, relying on the random decay of a flux-creep process in the superconductor.         Critical current variation and current transfer length in multifilamentary Bi-2223/Ag tapes    A. Kasztler, M. Foiti, H. Kirchmayr, M. Polak and M. Majoros Summary: In this work we compare V-I curves and critical currents of a Bi-2223/Ag tape with 55 filaments in an Ag matrix measured at 77 K with test sections of various lengths. The distance between the potential taps on the sample was reduced from 800 mm over 100 mm to 10 mm and 1 mm. Furthermore it is shown how the shape of E-I curves varies with the length of the measured section. We also observed that many of the measured V-I curves have one or more linear sections. They are supposed to be caused by current transfer voltages in the vicinity of filament defects. We also studied the current transfer length in order to see how far from a defect voltages due to the current redistribution between a filament and the matrix can be observed. These results show that the critical currents of multifilamentary tapes could be increased strongly by improving their homogeneity.         Electrical DC characteristics of textured BSCCO-2212 thin rods developed for current leads    M. Mora, E. Martinez, L.A. Angurel and R. Navarro Summary: Textured Bi-2212 thin rods have been fabricated using a laser floating zone melting technique. Very high critical current densities, J/sub c/(77 K) >5000 A/cm/sup 2/, have been obtained in samples of 1 mm in diameter. Transport properties of these samples at temperatures between 65 and 77 K are reported. The results has been analysed assuming a flux flow mechanism for the appearance of the self field energy losses. A leading pinning mechanism associated with the planar junctions between grains have been considered.         Flux pinning due to MgO particle additions in partial-melt processed Bi-2212 bulk    B. Ni, Y. Tomishige, Jiwu Xiong and Zhong Xian Zhao Summary: In order to introduce effective pinning centers into Bi-2212 superconducting bulk, the addition of small MgO particles to Bi-2212 bulk and its effect on flux pinning were studied. Bi-2212 bulk samples were prepared by employing a normal partial-melting process, with a 0-8 vol.% of MgO particles addition. The morphology of Bi-2212 with MgO doping was investigated by means of XRD and EPMA. The magnetization and critical current densities (J/sub c/'s) in various magnetic fields and temperatures were measured by using a SQUID magnetometer. It was found that J/sub c/ in samples with relatively large MgO particles introduced shows a larger value than that in MgO-free sample, which implies that the MgO particles act as effective pinning centers and enhance the flux pinning characteristic in Bi-2212 bulk. A qualitative agreement between the experimental results and theoretical estimation was obtained.         Evaluation of E-J characteristics for Bi-2223 wires    H. Okamoto, F. Irie, T. Kiss, K. Hasegawa, M. Inoue and M. Kanazawa Summary: We have studied a method to evaluate electric field (E) vs. current density (J) characteristics of high temperature superconductors as a basis for their power device application. The E-J characteristics of Bi-2223 wires were measured in a wide range of magnetic field and temperature. Those characteristics are discussed by the theory of critical-current-density distribution and by the scaling law of the pinning force.         Fabrication of large area superconducting thin film by pulsed laser scanning    Q.L. Wang, C.W. An, W.D. Song, S.S. Oh, K.S. Ryu and D.Y. Jeong Summary: In order to deposit high quality high temperature superconducting (HTS) YBCO thin films with a large area, the pulsed laser scanning (PLS) method was tried and the thickness distribution of the film was investigated. Large area YBa/sub 2/Cu/sub 3/O/sub 7-x/ thin films on /spl phi/ 36 mm diameter LaAlO/sub 3/ and /spl phi/ 42 mm diameter Y-ZrO/sub 2/ (YSZ) single crystal substrates were obtained by rotating lenses with radii of 9 and 12.9 mm. The critical temperatures T/sub c/ of the films at the center and edge were all 90 K. The critical current density J/sub c/ at 77 K and zero magnetic field is over 10/sup 6/ A/cm/sup 2/. X-ray diffraction showed that the thin films are completely c-axis oriented. The V-I characteristics of the thin films were also investigated.         Large area pulsed laser deposition of YBCO thin films    B. Schey, W. Bieel, M. Kuhn and B. Stritzker Summary: A special PLD-setup for large area deposition of homogeneous YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) thin films and buffer layers as large as 7 cm/spl times/20 cm is presented. A new concept for homogeneous large area substrate heating and the influence of the deposition rate on the film properties is discussed. YBCO is deposited on r-plane sapphire substrates (10 cm/spl times/10 cm) as well as on smaller (2 inch O, 1 cm/spl times/1 cm) SrTiO/sub 3/, MgO, LaAlO/sub 3/, and on yttria stabilized ZrO/sub 2/ substrates distributed over the deposition area. The homogeneity of the deposited YBCO films concerning structural and electrical properties is investigated by XRD, RBS/channeling, and spatially resolved inductive measurements of T/sub c/ and J/sub c/. The variation of J/sub c/ on a 2 inch MgO wafer is less than /spl plusmn/9%, the mean c-axis length is 11.681 /spl Aring/, the FWHMs of the [005] rocking curves are 0.40 and the channeling minimum yield /spl chi//sub min/ varies between 3.7% and 4.9% over the 2 inch wafer. The J/sub c/ values of YBCO on 7 cm x 20 cm in situ buffered sapphire substrates are (2.0/spl plusmn/0.4 MA/cm/sup 2/) at T=77 K and B=0 T.         Double-sided sputtering deposition of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films on 2" LaAlO/sub 3/ wafers for microwave applications    Y. Lemaitre, D. Mansart, B. Marcilhac, J.C. Mage and J. Siejka Summary: Superconducting yttrium barium copper oxide films were prepared on 2" lanthanum aluminate substrates by sputtering from a cylindrical and stoichiometric target. The deposition parameters were studied in order to obtain in a reproducible manner a sufficiently low value of the surface resistance for microwave applications. The typical value at 10 GHz and 77 K was 0.35 m/spl Omega/ down to 0.2 m/spl Omega/. The purpose of this work was the subsequent deposition of YBa/sub 2/Cu/sub 3/O/sub 7-z/ on the LaAlO/sub 3/ backside without degradation of the first deposit. The fabrication of the subsequent deposit was made with the same deposition parameters as the first film after turning over the substrate at room temperature. The physical and structural properties of both side deposits were analyzed (RBS, ion channeling, MEB, XRD, Rs and electrical resistivity). Although the first film underwent a second thermal process during the subsequent deposition, the surface resistance value was not degraded. This unexpected result is discussed in the frame of the mechanism of oxygenation in YBa/sub 2/Cu/sub 3/O/sub 7-x/ film by changing the conditions of sample cooling. An example of a microwave filter using this double-sided structure is presented.         Preparation of YBCO thin film by MOCVD method using new liquid metal organic precursors    Y. Tasaki, S. Yoshizawa, K. Koyama and Y. Fujino Summary: New low melting point yttrium, barium, and copper complexes were synthesized for metalorganic chemical vapor deposition (MOCVD), tris(2,2,6,6-tetramethyl-3,5-octandionato)yttrium (Y(TMOD)/sub 3/), Ba(TMOD)/sub 2/, and bis(6-ethyl-2,2-dimethyl-3,5-octanedionato)copper (Cu(EDMOD)/sub 2/). The melting point of Y(TMOD)/sub 3/, 95/spl deg/C, is 80/spl deg/C lower than that of the conventional tris(dipivalaylmethanato)yttrium (Y(DPM)/sub 3/). The melting point of Cu(EDMOD)/sub 2/ is 78/spl deg/C, which is 120/spl deg/C lower than that of Cu(DPM)/sub 2/. For fabrication of YBa/sub 2/Cu/sub 3/O/sub y-/spl delta// thin films, these complexes were used in the liquid state where a stable deposition rate could be obtained; the Y(TMOD)/sub 3/ and the Cu(EDMOD)/sub 2/ were heated at 105/spl deg/C and 90/spl deg/C, respectively, and the mixture of Ba(DPM)/sub 2/ and Ba(TIMOD)/sub 2/ in the ratio of 4 to 1 was used at 215/spl deg/C. Single crystal STO(100) was used as a substrate. Substrate temperature was 800/spl deg/C. Thin films, of thickness 200 nm, were obtained. The XRD patterns of all the samples showed the preferred orientation of the c-axis normal to the substrate surface. The superconductivity was confirmed at 78 K.         Y-Ba-Cu-O thin films composition formation during magnetron sputtering    M.N. Drozdov, S.V. Gaponov, S.A. Gusev, E.B. Kluenkov, V.I. Luchin, D.V. Masterov, S.K. Saykov and A.K. Vorobiev Summary: The presence of various precipitations of secondary phases in Y-Ba-Cu-O films is extremely undesirable for many applications. Occurrence of yttrium-rich and copper-rich secondary phases in our films prepared by inverted magnetron sputtering is the result of the film composition deviations from "123" stoichiometry during in-situ growth. We have simulated and investigated in detail the processes causing the film composition deviations from stoichiometry. First, long-term changes (up to 50%) in the target composition due to the diffusion mass transfer inside the target are possible. Second, the distinctions in the modes of scattering by the background gas and in diffusive travelling of sputtered atoms to the substrate can lead to deviations (up to 15%) of film composition from the target composition. Third, the deviations (up to 30%) may be caused by significant nonstoichiometric currents of desorbed YBCO components from coated elements of the sputtering system to the substrate and from the growing film on substrate. These currents are a result of selective redeposition of the growing film by bombardment of positive plasma ions accelerated (up to 1 eV) through the floating potential voltage. The films with optimized properties show a zero resistance temperature of 92 K and a critical current density of 3/spl middot/10/sup 6/ A/cm/sup 2/ (at 77 K).         Corrosion of superconductors-especially of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// cuprate    M. Regier, E. Keskin and J. Halbritter Summary: Electronic properties of superconductors deteriorate with time by oxidation or other chemical attack enforced by thermal cycling. Despite being oxides, cuprate superconductors deteriorate in lab atmosphere. The corrosion of, e.g., YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) is mainly caused by H/sub 2/O and CO/sub 2/, which react to Ba-hydroxide and to Ba-carbonate. As reaction paths the CuO-chain-BaO-layers are the fastest ones, whereas the out-of-plane paths are slower. Grain and twin boundaries or strain have been identified as paths for O-diffusion or reaction with H/sub 2/O and CO/sub 2/.         Properties of Bi-Sr-Ca-Cu-O (2212) films deposited by sputtering on tilted substrates    M. Moriya, T. Okamoto, K. Usami, T. Kobayashi and T. Goto Summary: Bi-Sr-Ca-Cu-O (2212) thin films have been deposited on tilted SrTiO/sub 3/ substrates using a dc sputtering system. These films have been deposited at 710-790/spl deg/C. The thickness of these films is about 170 nm. The films deposited at 730, 750 and 770/spl deg/C exhibit superconductivity, and the highest value of critical temperature is about 70 K for the film deposited at 750/spl deg/C. The crystal structure of this film has also been investigated by X-ray diffraction with c-axis oriented 2212 phase.         Submicron-size fabrication of BSCCO thin films by using patterned substrates    T. Ishibashi, T. Kawahara, H. Kaneko and K. Sato Summary: Submicron-size Bi/sub 2/Sr/sub 2/CaCu/sub 2/O, (BSCC0) structures of mesa patterns with dimensions of 0.3/spl mu/m x 0.3/spl mu/m and line patterns of 0.3/spl mu/m width were fabricated on patterned SrTiO/sub 3/ (001) substrates. These submicron-sized BSCCO structures were grown on patterned structures directly drawn by an focused ion beam (FIB) apparatus with a Ga ion beam accelerated at 30 kV. The c-axis oriented epitaxial BSCCO thin films were prepared by the molecular beam epitaxy (MBE) method on the patterned substrates with a thickness of 70nm. The fine submicron-size BSCCO structures were obtained from the growth properties of the crystal, which favor the formation of (100), (010), (110) and (110) facets. These patterns are free from damages from various etching processes.         Growth of superconducting Hg-1212 very-thin films    L. Fang, S.L. Yan, T. Aytug, A.A. Gapud, B.W. Kang, Y.Y. Xie and J.Z. Wu Summary: High quality epitaxial HgBa/sub 2/CaCu/sub 2/O/sub 6+/spl delta// (Hg-High 1212) films with thickness less than 100 nm have been successfully synthesized using a cation-exchange process. The films show the superconducting transition up to /spl sim/118 K which is close to the intrinsic value of 124 K for the Hg-1212 phase, and critical current densities up to 1.1/spl times/10/sup 7/A/cm/sup 2/ at 5 K, 1.14/spl times/10/sup 6/A/cm/sup 2/ at 77 K and 2.59/spl times/10/sup 5/A/Vcm/sup 2/ at 100 K in zero field.         Transport properties of (Hg,M)-12(n-1)n (M=Re,Mo; n=2,3) superconducting thin films    Y. Moriwaki, T. Sugano, S. Adachi, K. Tanabe and A. Tsukamoto Summary: We have successfully fabricated 200-500 nm thick highly c-axis oriented (Hg,Re)-1223 and (Hg,M)-1212 (M=Re,Mo) thin films on SrTiO/sub 3/(100) substrates by using HgO/M-Ba-Ca-Cu-O multilayer precursor films prepared by pulsed laser deposition. Their electrical transport properties in magnetic fields less than 7 T are investigated using 5-50 /spl mu/m wide bridges patterned by means of electron-beam lithography and ion milling without using water. The (Hg,Re)-1223 film exhibits a T/sub c/(zero) of 127.5 K and a J/sub c/ value at 77 K of 1.5 and 0.2/spl times/10/sup 6/ A/cm/sup 2/ in a self-field and 1 T field, respectively. Higher J/sub c/ values below 100 K are observed for (Hg,M)-1212 (M=Re,Mo) films with better crystallinity and surface morphology than the 1223 film in spite of their lower T/sub c/ (zero) of 115-122 K. The (Hg,Re)-1212 film exhibits the highest J/sub c/ values of 5, 1.5, and 0.4/spl times/10/sup 6/ A/cm/sup 2/ at 77 and 100 K in a self-field and at 77 K in 1 T field, respectively. The irreversibility field above 77 K evaluated from the resistive transitions of these films is found to be substantially higher than those for undoped Hg-1212 and Tl-1223 thin films.         Synthesis and microwave properties of thin films of the 1:2:2:1 borocarbide superconductors YNiBC and ErNiBC    A. Andreone, C. Aruta, M. Iavarone, F. Palomba, M.L. Russo, M. Salluzzo, R. Vaglio, A. Cassinese, M.A. Hein, T. Kaiser, G. Mueller and M. Perpeet Summary: High-quality c-axis oriented YNi/sub 2/B/sub 2/C (transition temperature T/sub c/=15 K) and ErNi/sub 2/B/sub 2/C (T/sub c/=9.5 K) borocarbide superconducting thin films were grown "in-situ" on MgO and sapphire substrates by planar magnetron sputtering. Here we report data on the temperature, DC and RF magnetic field dependent surface impedance of the films and discuss them in view of possible applications. The YNi/sub 2/B/sub 2/C films displayed the behavior expected for BCS-like superconductors, while the microwave response of the antiferromagnetically ordering compound ErNi/sub 2/B/sub 2/C was distinctly different. The field dependent surface resistance of both types of films displayed granular effects.         Variation of LaSrCuO film temperature during pulsed laser deposition on LaSrGaO substrate    C. Buzea, H. Myoren, H.B. Wang, K. Nakajima and T. Yamashita Summary: By using a conventional laser ablation system, LSCO thin films were deposited on LaSrGaO/sub 4/(100) substrates in an oxygen environment. During deposition the temperature of the film surface was measured with an infrared pyrometer. The measured temperature decreases following the exponential law of radiation absorption in a material. The experimental results indicate an increase of the deviation from the exponential law with decreasing oxygen pressure in the chamber. The conclusion of this experiment reveals the fact that either the refraction index of the deposited material may vary nonuniformly or the deposition velocity is not a constant during laser ablation.         Pulsed laser deposition of YBCO and NBCO using experimental design    A. Eulenburg, E.J. Romans and C.M. Pegrum Summary: Thin films of YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) and NdBa/sub 2/Cu/sub 3/O/sub 7-x/ (NBCO) were grown by pulsed laser deposition (PLD). The experiment was planned using experimental design to investigate the relative importance of the individual growth parameters for the properties of the films. For both materials critical temperatures close to 90 K were obtained. The electrical and morphological properties of the films were correlated to the growth conditions using regression analysis. For NBCO, regions where both electrical and morphological properties were optimised could be found, while for YBCO we found that the main factors that lead to high critical temperatures also lead to a substantial increase in the surface roughness.         Growth and properties of pulsed laser deposited superconducting La/sub 1.85/Sr/sub 0.15/CuO/sub 4/ thin films    Weidong Si and X.X. Xi Summary: High quality thin films of high temperature superconducting La/sub 1.85/Sr/sub 0.15/CuO/sub 4/ have been grown using pulsed laser deposition on LaSrAlO/sub 4/ buffer layers on [100] SrTiO/sub 3/ substrates. An ozone/oxygen mixture was used during the cooling of the films from the deposition temperature. The zero-resistance superconducting transition temperature T/sub c/ was 39 K and the critical current density J/sub c/ was over 10/sup 6/ A/cm/sup 2/ at 4.2 K for 800 /spl Aring/ thin films. The resistivity was found to depend linearly on temperature with a resistivity ratio /spl rho/(300 K)//spl rho/p(50 K) of 4.5 and an intercept at T=0 of /spl sim/30 /spl mu//spl Omega/cm.         Transport properties and anisotropy measurements on [(BaCuO/sub 2/)/(CaCuO/sub 2/)] superconducting superlattices    A. Canesi, S. Gariglio, D. Marre, I. Pallecchi, M. Putti, G. Balestrino, P.G. Medaglia and G. Petrocelli Summary: Infinite layer based superlattices [(BaCuO/sub 2/)/sub m//(CaCuO/sub 2/)/sub n/] are a new kind of artificial superconductors with interesting properties both for fundamental comprehension purposes and for future possible applications. The artificial nature of these compounds offers the possibility of analyzing the influence of the structural properties on the superconducting behavior. For example we can study the correlation between the number of CuO/sub 2/ planes contained in the infinite layer block (CaCuO/sub 2/) and the transport properties. In this paper, we present transport properties characterization of some thin films of this family containing different numbers of CuO/sub 2/ planes. Such films have been grown by the pulsed laser deposition (PLD) technique. In order to investigate the influence of the number of CuO/sub 2/ planes and of the distance between them on critical temperature, charge concentration, and anisotropy, we perform measurements of resistivity, magnetoresistivity and Hall coefficient as functions of temperature and applied magnetic field.         New artificial superlattices: correlation between structural disorder and transport properties    D. Marre, S. Gariglio, I. Pallecchi and A.S. Siri Summary: The development of thin film deposition techniques allowed the growth of new artificial materials leading to the discovery of new high T/sub c/ superconducting compounds as infinite layer based superlattices [(BaCuO/sub 2/)/sub m//(CaCuO/sub 2/)/sub n/]. The order of the superlattice structure seems to be one of the crucial parameters to be improved so as to induce a superconductivity onset in these materials and to make them suitable for technological applications. In this paper we present a study on the correlation between structural disorder and transport properties of several artificial superlattices grown by pulsed laser ablation technique. Our goal was to simulate the layered structure of copper oxide superconductors, so as to create new artificial superconducting materials and study the charge transfer mechanism. We chose infinite layer phases (SrCuO/sub 2/, CaCuO/sub 2/, BaCuO/sub 3/) for the blocks containing CuO/sub 2/ planes and doped infinite layer phases (CaCu/sub 1-x/Sc/sub x/O/sub y/, SrCu/sub 1-x/Sc/sub x/O/sub y/, CaCu/sub 1-x/Ag/sub x/O/sub y/ and SrCu/sub 1-x/Ag/sub x/O/sub y/, with x ranging from 0.1 to 0.2) for the charge reservoir blocks. By means of reflection high energy electron diffraction (RHEED) and X-ray structural characterization as well as resistivity and Hall effect measurements, we perform a comparative analysis of structural and transport properties of these samples and we tried to explain them in terms of Anderson's theory of disorder.         Effect of planarization of the bottom superconducting yttrium-barium-copper-oxide layer in the multilayer structure    W.A. Luo, H.J. Yao, S. Afonso, S.J. Qin, S.H. Yoo, S. Ang, W.D. Brown, G.J. Salamo and F.T. Chan Summary: YBCO/YSZ/SiO/sub 2//YSZ/YBCO multilayer structures have been successfully grown on single crystal YSZ substrates. The YBCO superconducting layers (300 nm thick) were deposited using pulsed laser deposition (PLD). The YSZ layers (300 nm thick) which are biaxially aligned were deposited using PLD and ion beam assisted deposition (IBAD). A thick silicon dioxide layer (2-4 microns) was sandwiched between the YSZ layers to meet the low dielectric constant requirement for multichip module applications. However, if the bottom superconducting layer was patterned into interconnecting lines as required in device applications, the surface of the YSZ/SiO/sub 2//YSZ on top of the patterned bottom superconducting layer had a roughness of about 500 nm. As a result, the top YBCO was no longer superconducting. Thus, planarization of the patterned bottom superconducting layer becomes a key issue. We have developed a "fill-in and lift-off" process to fill the gap between the patterned bottom superconducting lines with YSZ, As a result, we were able to reduce the surface roughness of the bottom YBCO layer to about 10 nm so the top layer was superconducting with a critical temperature of 87 K.         Stress induced change in hole concentration in superlattice films of bismuth-based oxide superconductors    T. Hatano, S. Labat, A. Ishii, S. Arisawa and K. Togano Summary: Superlattice films of bismuth-based oxide superconductors, for instance (2234)/sub 1/(2212)/sub 1/ and (2245)/sub 1/(2201)/sub 1/, have been synthesized by sequential sputter deposition of bismuth oxide, strontium-copper-oxide and calcium-copper-oxide monolayers. Crystal structures, superconducting transition temperatures and hole concentration of the films were studied by X-ray diffraction, Meissner effect and Hall effect measurements. It was observed that the superconducting transition temperatures were enhanced by forming superlattice films of overdoped (2212, 2201) and underdoped (2234, 2245) phases. The results can be understood by stress induced changes in the hole concentration between the overdoped and the underdoped phases originating from the epitaxial (lattice matching) formation of the superlattice films.         Low-cost combustion chemical vapor deposition of epitaxial buffer layers and superconductors    S.S. Shoup, S. Shanmugham, D. Cousins, A.T. Hunt, M. Paranthaman, A. Goyal, P. Martin and D.M. Kroeger Summary: A new low-cost, open-atmosphere deposition technique, combustion chemical vapor deposition (CCVD) is used to deposit epitaxial buffer layers and high-temperature superconductors on oxide single-crystal substrates. The CCVD process has the potential for manufacturing buffer layers and superconductors onto textured metal substrates in a continuous reel-to-reel production. CCVD does not use vacuum equipment or reaction chambers required by conventional techniques, while its coating quality rivals and even exceeds that of conventional methods. Compounds being studied with the CCVD process include the buffer layers cerium oxide (CeO/sub 2/), yttria stabilized zirconia (YSZ), strontium titanate (SrTiO/sub 3/), lanthanum aluminate (LaAlO/sub 3/), yttria (Y/sub 2/O/sub 3/), and ytterbium oxide (Yb/sub 2/O/sub 3/) and two rare earth superconductors, YBa/sub 2/Cu/sub 3/O/sub 7-x/, (YBCO) and YbBa/sub 2/Cu/sub 3/O/sub 7-x/ (YbBCO).         Observation of the Bi,Pb(2223) reaction mechanism and alternative ways of producing tapes with new filament configurations    R. Flukiger, Y. Huang, F. Marti, M. Dhalle, E. Giannini, R. Passerini, E. Bellingeri, G. Grasso and J.-C. Grivel Summary: Investigations on the Bi,Pb(2223) phase formation confirm a mechanism based on nucleation and growth. The same mechanism was found to hold under various external conditions: a) in pressed samples, b) in Ag sheathed tapes, c) in air or in reduced oxygen partial pressure and d) with or without the presence of Pb. A high temperature neutron diffraction investigation on monofilamentary Bi,Pb(2223) tapes shows that this phase remains stable during the cooling process after reaction. On cooling, an enhancement of the Bi(2212) phase is observed, which occurs at the expense of the other phases, (Sr,Ca)/sub 14/Cu/sub 24/O/sub 41/ and Bi(2201). New tape configurations are presented, in view of a) the reduction of anisotropy (on both, tapes or wires) and b) the reduction of AC losses. These configurations require the use of nonconventional techniques, e.g. two-axis rolling and/or periodic pressing. Using periodic pressing, j/sub c/(77K,0T) values of 35,000 A/cm/sup 2/ have been obtained in Bi,Pb(2223) multifilamentary tapes of lengths >2 m.         Critical role of phase transformation during processing of Ag/Bi:2223 tapes    S.X. Dou, R. Zeng, X.K. Fu, Y.C. Guo, J. Horvat, H.K. Liu, T. Beales and M. Apperley Summary: Phase transformation during the final stage of Ag/2223 tape processing has been investigated through quenching and normal cooling in a specially-designed two-step sintering process. It was found that the phase assemblage in the final tape was determined by the equilibrium composition at the sintering temperature and also from any phase transformation which occurred on cooling. A two-stage sintering procedure in the final thermal cycle was found to be effective in transforming the liquid (or amorphous phase) and residual 2201 into 2212 and 2223. However, the annealing temperature during the final step was critical to the final phase assemblage. The optimal annealing temperature of the second step in the two-step process was around 825/spl deg/C, where all the low T/sub c/ phases and impurities were at a minimum. Annealing at temperatures below 810/spl deg/C, resulted in a substantial increase in 3221, and a lower J/sub c/. Annealing above 825/spl deg/C led to a large 2212 fraction with a small amount of 2201 because of insufficient time needed to convert these phases into 2223 on normal cooling.         Structural and compositional defects in high-J/sub c/ Bi-2223 tapes    T.G. Holesinger, J.F. Bingert, J.O. Willis, Qi Li, R.D. Parrella, M.D. Teplitsky, M.W. Rupich and G.N. Riley Jr. Summary: High critical current density (J/sub c/) Bi-2223 multifilamentary tapes (55 kA/cm/sup 2//spl les/J/sub c//spl les/70 kA/cm/sup 2/, 77 K and self-field) have been examined by transmission electron microscopy. Filament microstructures within the tapes consist of two distinct regions: a highly aligned, dense colony structure (brick-wall) near the silver interface and a porous, poorly-textured interior region (impurity channel) that contains significantly more secondary phases. Quantitative compositional analysis clearly showed a heterogeneity in the Bi-2223 composition throughout the tapes. Spatial variations in composition were especially prevalent in the vicinity of secondary phases. Potential current limiting microstructures or defects were categorized depending upon the length scale at which they would operate. Macroscale defects were defined as potentially limiting current flow between regions of a filament. Mesoscale defects affect current flow between adjoining colonies. And finally, microscale defects were classified as potentially limiting current flow within a colony structure.         Measurements and modeling of microwave impedance of high-T/sub c/ grain boundaries    D.E. Oates, Y.M. Habib, C.J. Lehner, L.R. Vale, R.H. Ono, G. Dresselhaus and M.S. Dresselhaus Summary: We present measurements and modeling of the microwave frequency (RF) power-dependent impedance of YBCO thin film grain boundaries. The measurements were performed using a stripline resonator technique that separates the characteristics of the grain boundary from the rest of the film. The devices were fabricated on sapphire bicrystal substrates with misorientation angles varying from 2 to 24/spl deg/ and on single crystals. Measurements of the DC I-V characteristics were also performed. The RF measurements are presented as a function of RF current (0.1 mA to 1 A) and temperature (6 to 70 K), Grain boundary angles of 10 and 24/spl deg/ show Josephson junction behavior in the RF measurements, but at angles of 5/spl deg/ or less the RF impedance is indistinguishable from films grown on single crystal substrates in contrast to DC measurements that show reduced critical current for the 5/spl deg/ grain boundary. The measured impedance of the large angles is compared with a long junction model which fits the measured data qualitatively. The measurements and modeling show the creation, annihilation, and motion of Josephson vortices by RF currents which produce the observed nonlinearities in the impedance. We also present measurements of second harmonic generation.         Defects in YBCO relevant for RF superconductivity: T-, f- and H-dependencies    E. Keskin, K. Numssen and J. Halbritter Summary: The present understanding of intrinsic and extrinsic HTS properties gained in the last years is applied to sintered and epitaxially grown YBCO. As results, the mean free path l increases rapidly below T/sub c/, whereas the weak links with critical Josephson current j/sub CJ/(T) and leakage current resistance R/sub bl/ describe R(T<0.8 T/sub c/, f, H) /spl cong/R/sub res/(T, f, H) over seven orders of magnitude in j/sub CJ/ with j/sub CJ/R/sub bl//sup 2//spl cong/10/sup -12/ A/spl Omega//sup 2/ cm/sup 2/.         Microwave power handling capability of HTS superconducting thin films: weak links and thermal effects induced limitation    J. Wosik, L.-M. Xie, R. Grabovickic, T. Hogan and S.A. Long Summary: Microwave power-handling capabilities of YBCO thin superconducting films, up to 150 W of the input power, have been investigated using a 14 GHz shielded dielectric cavity. The YBCO films were deposited by the thermal reactive co-evaporation and the dc sputtering method on LaAlO/sub 3/, NdGaO/sub 3/, and Al/sub 2/O/sub 3/ substrates. A simple nonlinear R(P)-L(P)-equivalent circuit model was used to simulate a nonlinear cavity response. The correlation of nonlinearity with global and local heating is discussed. The analysis of experimental data confirms, that for all films, the heating of weak links switched to normal state is one of the rf power handling capability major limitations.         Role of oxygen pressure during deposition on the microwave properties of YBCO films    D.A. Rudman, F.J.B. Stork, J.C. Booth, J.Y. Juang, L.R. Vale, G.J. Beatty, C.I. Williams, J.A. Beall, R.H. Ono, S.B. Qadri, M.S. Osofsky, E.F. Skelton, J.H. Claassen, G. Gibson, J.L. MacManus-Driscoll, N. Maide and L.F. Cohen Summary: We have studied the effect of oxygen pressure (PO/sub 2/) during pulsed laser deposition on the properties of YBCO films, with particular attention power microwave surface resistance R/sub s/. Above a threshold oxygen pressure the properties of the films are nearly independent of PO/sub 2/ during deposition and are typical of high quality YBCO films. The films made below this threshold pressure have increased disorder which produces a reduced T/sub c/ and an expanded c-axis lattice parameter. However, these films also have significantly reduced low temperature R/sub s/, which is likely a direct result of the increased scattering in these films. Preliminary Raman measurements show no increase in the Y-Ba cation disorder in these low PO/sub 2/ films, so that different disorder mechanism must be present.         Status of Bi-2223 tapes performance and development    T. Kaneko, T. Hikata, M. Ueyama, A. Mikumo, N. Ayai, S. Kobayashi, N. Saga, K. Hayashi, K. Ohmatsu and K. Sato Summary: We are developing Bi-2223 superconducting tapes on a wide viewpoint from fundamental superconducting property to application usage. In basic characterization of superconductivity, the behavior of critical current density (J/sub c/) in terms of both temperature and magnetic field was studied in detail and a new scaling law which can estimate the value of J/sub c/ in multiple conditions is defined. There were significant improvements in the long length fabricating process. The 1 km order length tape having J/sub c/ at 77 K over 20 kA/cm/sup 2/ can be produced reproducibly. The distribution of J/sub c/ through the whole length is very uniform. These results in both basic characterization and production progress made it possible and easy to design a high field magnet. Then, we have successfully developed a magnet using a refrigerator.         HTS wire at commercial performance levels    A.P. Malozemoff, W. Carter, S. Fleshler, L. Fritzemeier, Q. Li, L. Masur, P. Miles, D. Parker, R. Parrella, E. Podtburg, G.N. Riley Jr., M. Rupich, J. Scudiere and W. Zhang Summary: Short rolled multifilamentary BSCCO-2223 oxide-powder-in-tube (OPIT) wire has reached a core critical current density J/sub c/ over 73,000 A/cm/sup 2/ (77 K, self-field, 1 /spl mu/V/cm) in multiple samples, with engineering (full-cross-section) current density J/sub c/ of 22,800 A/cm/sup 2/ (77 K, self-field, 1 /spl mu/V/cm). Regular production wires several hundred meters long show average engineering current density over 10,000 A/cm/sup 2/ (77 K, self-field, 1 /spl mu/V/cm), a benchmark for commercial electric power applications such as cables and motors. Cost studies indicate that cost-performance below $10/kA-m is attainable for full-scale production levels, Next-generation YBCO-123 coated conductor technology offers further potential cost-performance improvements.         Advances in fabrication of Ag-clad Bi-2223 superconductors    U. Balachandran, M. Lelovic, B.C. Prorok, N.G. Eror, V. Selvamanickam and P. Haldar Summary: Powder-in-tube (PIT) processing was used to fabricate multifilamentary Ag-clad Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub y/ (Bi-2223) superconductors for various electric power applications. The transport current properties of long lengths of multifilament tapes were enhanced by increasing the packing density of the precursor powder, improving the mechanical deformation, and adjusting the cooling rate. The dependence of the critical current density on magnetic field and temperature for the optimally processed tapes was measured. J/sub c/ was >10/sup 4/ A/cm/sup 2/ at 20 K in magnetic fields up to 3 T and parallel to the c-axis, which is of interest for use in refrigerator-cooled magnets.         Fabrication and properties of Bi-2223 tapes    B. Fischer, S. Kautz, M. Leghissa, H.-W. Neumuller and T. Arndt Summary: Bi-2223 tapes in different variations represent a good basis to build up prototypes for power applications. With respect to these applications we produce 55 filament tapes of lengths up to 600 m carrying currents of 57 A. A statistical analysis confirms reproducibility and quality. In 1 m samples the critical current density reaches 40 kA/cm/sup 2/. An overview of the fabrication process of the tapes is given. Besides the mechanical and microstructural properties of different Ag/Ag-alloy tapes we present the current carrying capability in different magnetic fields and at different temperatures. Additionally the tapes are characterized regarding to their AC losses. These tapes of long lengths are used to fabricate power transmission cables, transformers and motors.         Large-area YBCO films on sapphire for microwave applications    R. Wordenweber, J. Einfeld, R. Kutzner, A.G. Zaitsev, M.A. Hein, T. Kaiser and G. Muller Summary: Crack-free thick YBa/sub 2/Cu/sub 3/O/sub 7-x/ films are prepared on CeO/sub 2/ buffered r-cut sapphire (2 inch in diameter) with thickness up to 700 nm, smooth surfaces ('peak-to-valley' roughness <10 nm), high critical currents (J/sub c/>2 MA/cm/sup 2/ at 77 K and 0 T) and low microwave surface resistance (R/sub s/(77 K)/spl ap/1.4 m/spl Omega/ and R/sub s/(4.2 K)/spl ap/110 /spl mu//spl Omega/ at 19 GHz), comparable to the best values reported for YBCO films on structurally better matched substrates. The improvement of the critical thickness of YBa/sub 2/Cu/sub 3/O/sub 7-x/ on structurally poorly matched sapphire from typically d/sub c//spl ap/250-300 nm to d/sub c/>700 nm is achieved by introducing defects which do not hamper the superconducting properties of the films. The modified film growth was reflected by slightly broadened rocking curves and an altered temperature dependence of R/sub s/. The thick YBCO films were able to handle high microwave power corresponding to magnetic field amplitudes (B/sub HF/) of at least 54 and 37 mT at 4.2 and 50 K (limited by the available power), and 17 mT at 77 K (often limited by quenches). The excellent high-power performance was achieved without any degradation of the samples despite frequent thermal cycling.         Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ and YBa/sub 2/Cu/sub 3/O/sub 7/ films on large area MgO and sapphire substrates for high power microwave and rf applications    D.W. Face, F.M. Pellicone, R.J. Small, L. Bao, M.S. Warrington and C. Wilker Summary: This paper describes recent work at DuPont to extend the high power microwave performance of YBa/sub 2/Cu/sub 3/O/sub 7/ and Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ high T/sub c/ superconducting (HTS) films on 2 inch diameter MgO and sapphire substrates. The YBa/sub 2/Cu/sub 3/O/sub 7/ films were produced by in-situ off-axis sputtering with radiant substrate heating. The Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ films were produced by off-axis sputtering followed by annealing in oxygen and Tl/sub 2/O vapor. The microwave surface resistance and power handling of these films was measured over a wide range of temperature (20 K to 85 K) using an HTS-sapphire resonator technique. At 70 K, the surface resistance of YBa/sub 2/Cu/sub 3/O/sub 7/ films on sapphire remained below 250 /spl mu//spl Omega/ (@8.1 GHz) for microwave surface current densities up to 1.7/spl times/10/sup 6/ A/cm/sup 2/. At 70 K, the surface resistance of Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ films on MgO remained below 230 /spl mu//spl Omega/ (@8.1 GHz) with microwave current densities up to 2/spl times/10/sup 6/ A/cm/sup 2/.         Nb/sub 3/Sn films on sapphire. A promising alternative for superconductive microwave technology    M. Perpeet, A. Cassinese, M.A. Hein, T. Kaiser, G. Muller, H. Piel and J. Pouryamout Summary: Phase-pure, large grained Nb/sub 3/Sn films on sapphire substrates have been prepared by a two-step process. The average grain size increased with the film thickness. Transport properties like the penetration depth, mean free path, and critical current density have been investigated in relation to the microstructure of the films. Measurements of the DC- and HF-magnetic field dependent surface impedance were performed. Nonlinear surface resistance occurred at field levels above B/sub s/=25 mT, and was related to extrinsic mechanisms. The relevance of weak coupling at grain boundaries decreased with increasing grain size. Thus heating at local defects was concluded to be the dominant limiting mechanism in large grained films. An intrinsic field limit of B/sub cl/=140 mT was found. The polycrystalline films showed a much lower residual resistance and comparable power handling compared to high-quality epitaxial YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//-films.         New high-field Nb/sub 3/Sn conductors prepared from Ta-Sn compound powder    K. Tachikawa, S. Yamamoto, T. Yokoyama and T. Kato Summary: New Nb/sub 3/Sn conductors with excellent high-field performance have been fabricated using Ta-Sn powder as a core material. The powder was easily synthesized by the melt diffusion reaction between Ta and Sn powders. The Ta-Sn powder was encased in a Nb or Nb-Ta alloy sheath to form a composite. The composite was fabricated into tape and wire specimens without intermediate annealing. The specimens were then reacted at 800-925/spl deg/C in vacuum. After the reaction a thick Nb/sub 3/Sn layer, several tens of micrometers in thickness, is formed between the sheath and the core. No void is formed in the core after the reaction. Ta is incorporated into the Nb/sub 3/Sn layer from both the core and the Nb-Ta sheath. The J/sub c/ of the Nb/sub 3/Sn layer reaches 5 /spl times/10/sup 4/ A/cm/sup 2/ at 23 T and 4.2 K. The tape specimens show large critical current at 23 T due to the large thickness of the Nb/sub 3/Sn layer. The optimum reaction temperature can be decreased by the small amount of Cu addition.         Development of Nb/sub 3/Sn superconductors for a 1 GHz NMR magnet. Dependence of high-field characteristics on tin content in bronze matrix    T. Miyazaki, Y. Murakami, T. Hase, M. Shimada, K. Itoh, T. Kiyoshi, T. Takeuchi, K. Inoue and H. Wada Summary: To realize a 1 GHz NMR magnet, superconducting properties such as critical current density (J/sub c/) and n-value are fundamental for conductors. J/sub c/ improvements of 15% to 27% have been observed in the conductor with Cu-15wt.%Sn-0.3wt.%Ti matrix compared with J/sub c/ in a conductor with Cu-13.wt%Sn-0.3wt.%Ti matrix. In contrast to J/sub c/, differences in n-values between conductors have not appeared. In this study, systematic analysis for dependence of J/sub c/ and n-value in the high field region on Sn content over 13wt.% in bronze was examined based on the microstructures, i.e. the amount of reacted layer, grain size of Nb/sub 3/Sn, and upper critical field (H/sub c2/) supported with stoichiometric analyses.         Niobium-tin for fusion, high energy physics and other applications    T. Pyon and E. Gregory Summary: If internal-tin conductors are to be used to their best advantage they should be designed for a specific application. Some applications emphasize the current density almost exclusively while others require a combination of properties where hysteresis losses are low while the J/sub c/ is maintained at as high a level as possible. Absence of flux jumps and instabilities is always desirable but more difficult to maintain as the J/sub c/ is raised. The progress made by the authors recently in the production of material for fusion, high energy physics (HEP) and other applications is described. Materials with J/sub c/s above 900 A/mm/sup 2/ at 12 T and losses below 200 mJ/cm/sup 3/ (/spl plusmn/3 T cycle) in the non-Cu area, have been made for fusion applications. Instabilities previously reported in material with higher J/sub c/s have been reduced so that more stable materials with high J/sub c/s over 2,000 A/mm/sup 2/ at 12 T have been manufactured. Recent properties in this higher J/sub c/ area are reported.         Critical current and n-value of Nb/sub 3/Sn conductors for the wide bore 900 MHz NMR magnet    I.R. Dixon, W.D. Markiewicz, K.W. Pickard and C.A. Swenson Summary: Electrical characterization of Nb/sub 3/Sn superconductor for application in a 900 MHz wide bore NMR magnet is performed. The magnet has five coils containing bronze process niobium-tin superconductor. Short samples of each of the five conductor types are reacted in a similar manner as the coils and the critical currents are measured. The samples are mounted across a Ti-6Al-4V shunt and the tests are conducted in background fields up to 19.45 T and at temperatures of 4.2 K and 1.8 K. Descriptions of the superconductor configurations and experimental procedure are given. The measured critical current and the current-voltage relationship of each conductor as expressed by the index number (n-value) are presented.         Variable-temperature transport critical currents of niobium-tin wires under strain in high magnetic fields    N. Cheggour and D.P. Hampshire Summary: A new probe has been developed to investigate the effect of strain and temperature on the transport critical current density of superconducting wires and tapes in high magnetic fields. The critical current of a multifilamentary niobium-tin wire has been measured as a function of magnetic field at 12 K, for both compressive and tensile strain. The ability to simultaneously vary strain, temperature and field facilitates a better understanding of how these parameters affect flux pinning mechanisms. From a technological point of view, these measurements provide essential design data for developing cryocooled high magnetic field systems.         Improved J/sub c/ of multifilamentary Bi,Pb(2223)/Ag tapes by periodic pressing    F. Marti, Y.B. Huang, G. Witz, R. Passerini, M. Dhalle, E. Giannini, E. Bellingeri, E. Walker, R. Flukiger and G. Grasso Summary: Critical current densities of multifilamentary Ag-sheathed Bi(2223) tapes up to about 35 000 A/cm/sup 2/ have been achieved at 77 K and self field for lengths of several meters using an improved route: periodic pressing. This corresponds to an increase by 30-40% compared to the values obtained for conventionally rolled tapes starting from the same powders. Several pressing steps have been introduced during the anneal instead of the only standard rolling step (based on previous studies performed on both mono- and multifilamentary tapes). In contrast to earlier attempts by pressing techniques, periodic pressing is a practical and scaleable process for the fabrication of long lengths of Bi(2223) conductor as the standard intermediate rolling step. Engineering critical current densities of 8 000 A/cm/sup 2/ have successfully been obtained for tapes with high filling factor (35%).         Processing and characterisation of long-length silver/bismuth-2223 tape for electric power applications    M.H. Apperley, F. Darmann, G. McCaughey, R. Zhao and T.P. Beales Summary: The potential of high temperature superconductivity (HTS) to raise efficiencies in electric power utilisation is dependent on the availability of HTS materials in a form which can be engineered into devices. This paper reviews a program of continuous process and product improvement which has enabled tape with lengths up to 1000 m and appropriate engineering properties to be reproducibly processed using the powder-in-tube technique. Underpinning this development of a large scale process capability, tape development on a small scale was necessary in the areas of innovative tape design, metal forming optimisation and heat treatment. In addition, techniques for the characterisation of long lengths of tape were developed. These techniques included the modelling of the effect of the self-field generated by the tape under test at 77 K to enable zero field Ic data to be determined.         Influence of rolling pressure on microstructures and current path evolution in Ag-sheathed Bi2223 monocore tapes    A. Oota and K. Kawano Summary: The influence of rolling pressure on microstructures and current transports has been investigated on Ag-sheathed Bi2223 monocore tapes, fabricated by a rolling process while changing mechanical load (i.e., rolling pressure). In combination with metallurgical studies, analyses on trapped-magnetic fields in a remanent state by a scanning Hall sensor show the evolution in transport current paths in the superconductor core, and also reveal critical current distributions therein. Enhancement of transport critical current density J/sub c/ at 77 K and 0 T with an increase in rolling pressure P up to /spl sim/0.3 GPa is ascribed to the evolution in transport current paths due to strengthening grain connectivity. Degradation in J/sub c/ with a further increase in P exceeding 0.3 GPa is caused by the occurrence of a sausaging effect. An optimum value of P is determined by a competition between strengthening grain connectivity and the occurrence of the sausaging effect. Numerical calculations on magnetic profiles give a variation of current capacity along a width direction in the core, so the local J/sub c/ value at the edge is 4-5 times greater than the value at the center.         The influence of heating temperature on the superconducting properties of silver-gold sheathed Bi-2223 tapes destined for power applications    W. Zhu, D. Willen, D.R. Watson and J. Cave Summary: For power engineering applications using HTS conductors, long-length Ag-Au sheathed Bi-2223 tapes are being developed. By a continuous fabrication process (rolling), tapes with J/sub c/ up to 20 000 A cm/sup -2/ (77 K, 0 T) have fabricated using the powder in tube method. The tapes were heat treated in the temperature range of 805-835/spl deg/C in an atmosphere of 8% oxygen in nitrogen. The influence of temperature and time on the evolution of the superconducting properties is investigated by means of electric transport current measurements (I/sub c/ and its distribution). Phase development at different processing stages is examined by XRD. The microstructure and phase assemblage at different heating temperatures are characterized with SEM/EDX. The critical current distribution in the tapes is studied by analyzing the second differential of the V-I curves and the effects of cracks and secondary phases are discussed.         Fabrication and characterisation of superconducting Bi-2223/Ag tapes with high critical current densities in km lengths    Z. Han, P. Bodin, W.G. Wang, M.D. Bentzon, P. Skov-Hansen, J. Goul and P. Vase Summary: Long length Bi-2223/Ag tapes with high critical current densities are needed for large-scale applications. In this paper, recent results from NST are being presented, describing recent results reaching critical current densities of 23 kA/cm/sup 2/ and engineering critical current densities of 5.2 kA/cm/sup 2/ at 77 K over the whole length of a 1250 metre long Bi-2223/Ag tape. To our knowledge this is the highest critical current density reported for Bi-2223/Ag tapes longer than 1 km. The approach for improving the homogeneity and the considerations of processing and handling the long length tape are presented. Various Ag alloy sheathed Bi-2223 tapes have been made by our standard production line. The properties of these tapes are compared.         Effect of V, Ir-doping on the J/sub c/ properties of Bi2223 tapes    H. Maeda, K. Kakimoto, M. Kikuchi, K. Watanabe, Y. Tanaka and H. Kumakura Summary: We prepared Ag-sheathed mono-core tapes and multifilamentary tapes with 19 filaments by the powder-in-tube method, using V- and Ir-doped Bi2223 powder with a doping amount x less than 0.15. In the doped tapes two effects are overlapped: One is the decrease in J/sub c/ due to some weak links caused by precipitates such as Sr-V-O oxides, and the other is the increase in J/sub c/ with the doping content due to the enhancement of Bi2223 phase formation. This results in a minimum in J/sub c/ at x=0.05. The second effect becomes stronger in the V-doping, because of the great enhancement of Bi2223 phase formation. In the Ir-doped tapes the J/sub c/ values decrease monotonically with the doping content. For the multifilamentary tapes the V-doping is very effective to obtain high I/sub c/ values.         Phase stability and grain growth in an Ag/Bi-2223 composite conductor prepared using fine-grained Bi-2223 as a precursor    N.N. Merchant, D.J. Miller, V.A. Maroni, R.D. Parrella, Q. Li, M.W. Rupich, W.L. Carter and G.N. Riley Jr. Summary: We have investigated the stability and microstructural transformability of the Bi-2223 phase in a silver-sheathed monofilament composite tape fabricated using fine grained Bi/sub 1.7/Pb/sub 0.3/Sr/sub 1.9/Ca/sub 2.0/Cu/sub 3.0/O/sub y/ (Bi-2223) as the precursor powder. The fully formed Bi-2223 precursor was prepared using established procedures. The purpose of this study was to explore the prospects for growing textured, large-grain-size Bi-2223 from the fine-grained precursor by process parameter perturbations. These perturbations included thermal ramp up variations, programmed heat treatment temperature and oxygen pressure fluctuations, and parameter manipulations during cool-down. Our results show that the types of heat treatments used in conventional oxide-powder-in-tube (OPIT) processing do not facilitate Bi-2223 grain growth when the precursor powder is preconverted Bi-2223. We also observed that the Bi-2223 partially decomposed during conventional thermal ramp-up in 0.075 atm O/sub 2/, but that this decomposition can be inhibited by ramping up in a reduced oxygen pressure. A pathway was found for back-reacting the fine-grained Bi-2223 (to Bi-2212, Bi-2201 and nonsuperconducting secondary phases), then reforming large-grained Bi-2223 in a colony microstructure having some distinct differences from that produced during conventional OPIT processing.         Proposal of new type Ag-BSCCO tapes and wires with low losses    F. Sumiyoshi, R. Kinoshita, Y. Miyazono, A.M. Campbell and K. Ohmatsu Summary: In order to get Ag-BSCCO tapes or wires with small losses, we propose a new fabrication technique named the 'wrapping method.' This is not only an alternative technique for fabrication of tapes and wires with very small twist pitches and well-aligned filaments instead of the conventional twisting process but also a new method of producing tapes and wires with transposed filaments. Especially for the latter, it Is theoretically confirmed that a uniform distribution of transport currents in the new two-layered multifilamentary wire can be easily obtained by optimizing wire parameters. As a result transport current produced hysteresis losses can be reduced to the desired level in the multi-layered wire with transposed filaments.         Development of Ag sheathed Bi-2223 multifilamentary tapes with MgO coated filaments    V. Lennikov, H. Caudevilla, L.A. Angurel, G.F. de la Fuente and R. Navarro Summary: A dip-coating process to obtain controlled, uniform coatings on silver sheathed Bi-2223 wires suitable for the fabrication of multifilamentary tapes is reported. Tapes with continuous fully connected MgO resistive barrier layers 1 to 17 /spl mu/m thick have been produced and characterized. The correlation between their microstructure, electric transport and magnetic properties has been analyzed. An effective reduction of the interfilamentary coupling with a minimum degradation of the tape performance has been obtained for 1 to 3 /spl mu/m thick barrier layers.         Comparison of magnetic field profiles of Ag/BSCCO-2223 tapes carrying AC and DC currents    E.C.L. Chesneau, B.A. Glowacki, J. Kvitkovic, M. Majoros, K. van Beek and M. Konczykowski Summary: The magnetic field profiles above Ag/BSCCO-2223 tapes of multifilamentary and multilayer configurations, whilst carrying transport currents, are compared with those predicted from their AC losses. These tapes show AC losses which follow the critical state equation for losses in a conductor of elliptical cross-section and therefore the magnetic field above the tapes during a current cycle can be predicted. We compare these predicted profiles with Hall probe measurements made when the tapes are carrying both AC and DC transport currents and with magneto-optical images.         Numerical analysis of AC loss in high T/sub c/ twisted tape carrying AC transport current in external AC magnetic field. Effect of twisting on loss reduction    N. Banno and N. Amemiya Summary: The effect of twisting in BSCCO tapes on the loss reduction is discussed by a numerical analysis using the finite element method. The optimal twist pitch giving the lowest loss for the tape carrying the AC current under the AC magnetic field is presented. The numerical analysis takes the smooth E-j characteristics, the twisted structure and the dynamic resistivity into account, which allows more accurate loss estimations. For the BSCCO tape with a typical dimension of 3 mm/spl times/0.2 mm, the optimal twist pitch is around 10 mm, when it is carrying the AC transport current with normalized amplitude I/sub t//I/sub c/=0.8, under the parallel magnetic field to the tape face.         Penetration loss in BSCCO tape without transport current    N. Banno, N. Amemiya, A. Mihoichi, M. Ciszek, H. Mukai and K. Ohmatsu Summary: A penetration loss formula for superconducting tapes has been derived in our previous work. In this paper, the orientation of the magnetic field is considered in the formula. This formula includes the E-j characteristics represented with a power law and the magnetic field dependence of the critical current density. The analytical estimations with the formula are compared with experimental results on the magnetization loss for a BSCCO tape with no transport current for several field orientations. The losses estimated by this formula agree well with the experimental results, when the magnetic field is applied parallel or perpendicular to the tape face. For the magnetic field with another field orientation, the experimental results are smaller than the analytical predications, because of the demagnetizing effect.         Hysteresis loss in a superconducting Bi-2223 tape with fine filaments    E.S. Otabe, T. Matsushita, J. Fujikami and K. Ohmatsu Summary: The energy loss density was measured for a Bi-2223 tape wire with superconducting filaments of average thickness 2.5 /spl mu/m to confirm the reduction of energy loss density due to the reversible fluxoid motion. The energy loss density is compared with the prediction by the modified Kim model. It is lower than the prediction at AC field amplitudes below the penetration field at temperatures above 77 K. The slope of the minor magnetization curve is less than unity and the estimated AC penetration depth is longer than the filament thickness in the same regime. This result supports the speculation that the reduction of the energy loss density is due to the reversible fluxoid motion.         The influence of precursor preparation on the superconducting properties of Bi(2223) tapes    A. Polasek, S.K. Xia, M.B. Lisboa, M.A. Sens, E.T. Serra, F. Rizzo and H. Borges Summary: The effect of preparation of precursor powders on the formation of Bi-2223 phase and critical current density (J/sub c/) of OPIT tapes, was studied. The precursors were prepared by "one-powder" and "two-powder" methods. The results indicate that a sufficiently large fraction of second phases in the precursors is crucial for obtaining pure 2223 phase and high J/sub c/ values. It is also revealed that the (Sr,Ca)/sub 2/CuO/sub 3/ second phase promotes a faster phase transformation of 2212 to 2223 than other second phases in the precursors. Tapes prepared with "one-powder" precursor achieved J/sub c/ of 25.5 kA/cm/sup 2/, while the J/sub c/ for the tapes made from "two-powder" precursors had values of about 12 kA/cm/sup 2/.         Influence of process parameters in drawing of superconducting wire    M. Malberg, J. Bech, N. Bay, P. Skov-Hansen and G. Cualbu Summary: Superconducting wire is often produced by the powder-in-tube method involving a number of different mechanical processes, among these is multi-step drawing operations of single filament wire. A silver tube is filled with ceramic powder (BiSrCaCuO). This composite is drawn in up to 100 steps, from an initial diameter of 20 mm to the final one of 1 mm. The present paper shows how two of the main parameters, the reduction and the semi-die angle, influences the drawing stress and the powder compaction of the single filament wire during drawing. The optimum die angle and the largest acceptable reduction per drawing step are determined. In powder compaction tests a linear relationship between microhardness and powder density is determined. This relationship is applied for determination of the density distribution in the cross section of drawn single filament wire. It is found that the drawing process causes an increase of the powder compaction near the interface between the silver and powder, whereas the density increase near the centre axis of the tube is smaller. The average density determined in this way corresponds well with the one determined by geometrical measurements.         Bi-2223 precursor billets for PIT wire production    T. Yamashita, J.A. Alarco, A.J. Ilyushechkin, K. Tomlins and P. Talbot Summary: High temperature superconductor precursor billets (feed rods) have been developed for loading into silver tubes. The billets are loaded prior to rolling or drawing operations in PIT wire manufacture. Investigations have shown that wires and tapes prepared from feed rod loaded tubes show enhanced uniformity of electrical transport properties when compared with conventional powder packing, especially in wires drawn to long lengths. Analysis on production feed rods have shown carbon content to be as low as 110 ppm.         Critical current density of Bi-2223/Ag multifilamentary tapes from 4.2 K up to 90 K in magnetic fields up to 23 T    A.B. Sneary, C.M. Friend, J.C. Vallier and D.P. Hampshire Summary: The transport critical current density of a 37 filament Bi-2223/Ag tape has been measured as a function of field at temperatures from 4.2 K up to 90 K. Measurements have been made with the tape in three orientations with respect to field. Data have been obtained over a large range of current from 10 mA to 100 A (i.e. four orders of magnitude) and a large range of applied fields up to 23 T. The J/sub c/ values have been fitted to the exponential form J/sub c/=/spl alpha/(T)exp[-B//spl beta/(T)] and compared to data in the literature. The comprehensive measurements presented in this paper can be used to test the predictions from the many mechanisms that have been proposed to explain J/sub c/ in Bi-2223/Ag tapes.         Preparation of Ag-sheathed Bi(2223) tapes for magnet applications    G. Grasso, A.S. Siri, F. Marti and R. Flukiger Summary: Ag-sheathed (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ tapes have been developed with a special filament configuration that could be of great interest when a magnetic field is applied to the tape at a significant angle with respect to the a-b planes of the superconductor. The fabrication process we propose allows the preparation of multifilamentary samples in which the filaments are inclined with respect to the tape plane. Such tapes could be used in the outer parts of high field superconducting magnets, where the flux lines present large angles with respect to the plane of the conductor.         Effects of intermediate deformation and thermal processing in the OPIT process upon critical current density of Ag/BiSSCO tapes    V. Beilin, A. Goldgirsh, E. Yashchin, M. Roth and M. Schieber Summary: Critical current density, J/sub c/, of Ag/Bi(Pb)SCCO tapes in as-deformed and as-sintered states were studied at different stages of tape processing. Intermediate pressing and rolling result in significant I/sub c/ degradation. Non-zero I/sub c/ remains after the applications of pressing load up to 11 and 8 GPa following the third and first sintering, respectively. Under rolling conditions I/sub c/ remains non-zero up to maximum tape thickness reduction of 20%. Bending tests show that I/sub c/ reduction is the result of deformation-induced micro-crack formation which are easily healed during the first hour of the next sintering. Intermediate deformation after the first sintering cycle has been shown to accelerate significantly the 2212 to 2223 phase transformation during the first hours of the second sintering step. I/sub c/ growth during the first hour of the second sintering cycle is not connected with that phase transformation and is presumed to be the result of pinning ability and structure connectivity enhancement.         Development of Bi-2223/Ag-alloy tapes    L. Bigoni, F. Barberis, R. Berti, F. Curcio, M. Donati, P. La Cascia, L. Martini and V. Ottoboni Summary: The reliable fabrication of robust, uniform, long length silver-sheathed Bi-2223 superconductor tapes capable of carrying high current densities represents a key factor towards the development of windings to be integrated in electric power devices. Bi-2223 tapes to be used for the fabrication of coils with a silver alloy sheath having 19 and 55 filaments in unit length of 100 meters have been fabricated by the Powder-In-Tube method. The critical current density enhancement of Bi-2223 tapes by means of the optimisation of mechanical deformation and thermal treatment parameters is here presented. The realised Bi-2223 tapes have been deeply characterised by DC and AC measurements at different temperatures. To evaluate the capabilities of the multifilamentary tapes in the realisation of coils their electrical behaviour as a function of magnetic field and bending strain has been investigated.         Synthesis of bismuth-strontium-calcium-copper oxide powders for silver composite wires with uniform micron sized filaments    S. Sengupta, E. Caprino, K. Card, J.R. Gaines Jr., L.R. Motowidlo, R.S. Sokolowski, R.R. Garcia and S.M. Mukhopadyay Summary: A chemical precipitation method is utilized to synthesize bismuth-strontium-calcium-copper oxide powder. Tetra-methyl ammonium hydroxide and tetra-methyl ammonium carbonate are used as a precipitant and for pH adjustment. Effect of processing parameters like carbonization time, and cation solution concentration on Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/ (Bi-2212) powders is reported. Powders with different particle size and distribution are used to fabricate Ag sheathed multifilamentary Bi-2212 round wires with diameter about 0.06 cm (corresponding to filament diameter about 3 /spl mu/m). Significant sausaging was observed for wires processed with larger particle size powders. Good filament uniformity was observed for wires produced from finer powders.         Development of long length Bi-based/Ag tapes and experimental magnets    R. Zeng, H.K. Liu, T.P. Beales and S.X. Dou Summary: Long lengths of multifilamentary superconducting (BiPb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ (Bi-2223)/Ag tapes up to 250 m made with "powder-in-tube" (PIT) process have been successfully prepared on a laboratory scale. Reproducible critical current density of between 12,000-18,000 A/cm/sup 2/ in the long length tapes have been achieved using the optimal reduction in flat-rolling procedure and standard flat-rolling method as the intermediate deformation between sintering periods. Several coils have been fabricated from sections of the long length tape, using the co-wound react-and-wind (R&W) procedure for double pancake-shaped coils and wind-and-react (W&R) procedure for solenoidal pancake shaped coils. Each coil was fabricated by co-wounding three tapes on 30 mm-diameter mandrel. An experimental magnet was designed and constructed by stacking together coils. Dimensions and parameters of this magnet are as follows: height, 105 mm; winding ID, 32 mm; OD, 120 mm; total number of turns, 1068. Total conductor length in the magnet was /spl sim/870 m. The coils were connected in series and then tested at 77 K. The field constant at mid-plane of the magnet, determined by introducing a Hall probe in the bore of the magnet, was /spl sim/105 Gs/A and it generated 0.24 T magnetic field at 77 K. A detailed investigation of the J/sub c/-B properties and J/sub c/-strain characteristic of the Bi-2223 tapes as designing parameters and properties of the test magnet have been carried out.         Critical current and magnetic field performance of Bi-2223/Ag composite superconducting tapes    N. Savvides, A. Katsaros, A. Thorley, J. Herrmann, G. McCaughey, R. Zhao, F. Darmann and M. Apperley Summary: We report measurements of the electrical transport properties of ((BiPb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/-Ag) Bi-2223/Ag composite conductors produced as part of the long-length product development in an industrial plant. The powder-in-tube (PIT) process was used to manufacture conductors containing various filament configurations including monofilament and multifilament tapes with untwisted and twisted filaments, and round wires. The transport critical current I/sub c/ was measured at various temperatures (T=4-80 K) and magnetic fields (B=0-9 T) for different orientations of the tapes with respect to the field. Self-field transport ac losses were determined at 77 K and 60 Hz as a function of ac current amplitude (0-100 A rms). The strain performance was evaluated at 77 K for applied bend strains from zero to 1.5%.         High critical current Ag and Ag alloy sheathed multifilament Bi-2223 tapes    W.G. Wang, Z. Han, P. Skov-Hansen, J. Goul, M.D. Bentzon, P. Vase and Y.-L. Liu Summary: Ag sheathed (BiPb/sub 2/)Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ (Bi-2223) multifilament tapes with filament numbers of 19, 37, 55, and 85 were produced by the powder-in-tube method. Enhanced tape performance has been achieved by optimisation of the processing conditions. Key factors are addressed that include elimination of the 2212 phase, improving grain connectivity through reducing the 2201 phase and alkaline earth cuprate phases, increasing superconductor core density as well as enhancing current contribution from edge filaments. A high J/sub c/ of 50 kA/cm/sup 2/ with an I/sub c/ of 42 A has been achieved reproducibly in 19 filament tapes with dimensions of 0.16/spl times/2.8 mm/sup 2/ and silver/superconductor ratios of 4.4:1. By reducing the silver ratio, a J/sub e/ of 14 kA/cm/sup 2/ with an I/sub c/ of 48 A has been obtained in 55 filament tapes and an I/sub c/ of 84 A has been obtained in a tape with dimensions of 4/spl times/0.23 mm/sup 2/. A record J/sub c/ of more than 30 kA/cm/sup 2/ with an I/sub c/ of 32 A was achieved in 250 metres long standard tapes. A 1250 m long pure Ag sheathed tape and an 1100 m long Ag alloyed tape have been produced with a J/sub c/ of higher than 25 kA/cm/sup 2/ by using optimised process parameters.         Stresses and strains in multi-filament HTS tapes    P. Skov-Hansen, Z. Han and J.I. Bech Summary: High temperature superconducting tapes are now commercially available for practical applications such as magnets and cables. However, still today the published data on strength and allowable deformation limits of these tapes are not altogether in agreement. Definitions and concepts with regards to the stresses and strains in HTS tapes under deformation are discussed in this paper and criterions for use by the industry are presented. When handling HTS tapes it is necessary to know the limiting values of loading, bending and twisting to avoid damage. Damage is commonly defined as degradation of the current carrying capabilities. Most serious is crack formation in the BSCCO material, this will take place when stress concentrations exceed a certain value. Values from 0.2% to 0.5% total tensile strain in the ceramic core is quoted as the deformation limit for HTS tapes where cracks are appearing. The stress/strain situation in a HTS tape with BSCCO cores in a metallic matrix is discussed and experimental results are presented. Damaging strains are found and compared with results from literature. Curves of the limiting values for bending, tension and torsion are shown as well as the influence of these deformations on I/sub c/ values.         Thermal cycling, critical current vs. strain, and finite element modelling of 1, 7, 19 and 37 filament Ag/Bi-Sr-Ca-Cu-O (BSCCO) tapes    O.O. Oduleye, S.J. Penn, N.McN. Alford, L.L. Lay and T. Beales Summary: Transport critical current, I/sub c/, distribution measurements, thermal cycling experiments and critical current vs. strain (I/sub c/ vs. /spl epsiv/) experiments were carried out on silver clad 1, 7, 19 and 37 filament Bi-Sr-Ca-Cu-O (BSCCO) tapes. The transport critical current distribution of silver clad Bi-Sr-Ca-Cu-O tapes are measured using a measurement system capable of making 10 /spl mu/m steps along 120 mm long tapes. The tapes are subjected to thermal cycling and repeat measurements of the I/sub c/ are made. The critical current vs. strain experiments are carried out by centre point loading of the tapes. Elastic-Plastic Finite Element Modelling (FEM) of a monocore tape is carried out. Our analyses show the variation of the transverse stress, /spl sigma//sub yy/, across the width of the tape.         The influence of processing parameters and tensile stresses on the properties of Bi-2223 tapes with Ag and AgMn sheaths    K. Fischer, T. Fahr, U. Schlafer, C. Rodig, P. Trinks, M. Schubert, P. Verges and H. Klauss Summary: Multifilamentary Bi-2223 tapes with an inner Ag sheath immediately surrounding the filaments and an outer AgMn sheath containing 0.06-0.4 wt.% Mn have been fabricated by using the oxide-powder-in-tube technique. In some cases the filaments were additionally surrounded by a second AgPdAu sheath. The forming parameters employed to the rolling of the tapes and consequently the density evolution of the filaments during rolling were optimized aiming to avoid filament sausaging and at the same time to provide a high filament density in tapes of the final dimensions. After the parameters of the thermomechanical treatment were optimized too, similar values of the critical current densities could be achieved for tapes with a Ag/Ag-alloy sheath as for those with a pure Ag sheath. J/sub c/ values above 20 kA/cm/sup 2/ (77 K, 0 T) were measured on tapes over the whole length of 300 m. The tolerable tensile stresses and strains employable to conductors at room temperature without causing essential J/sub c/ degradation at 77 K were determined to /spl sigma//spl ap/90-110 MPa and /spl epsiv/=0.2% for tapes with an outer Ag-0.15 wt.% Mn sheath.         Theoretical study on vortex glass-liquid transition in pinned superconductors    T. Matsushita and T. Kiss Summary: The vortex glass-liquid transition in pinned superconductors is studied theoretically from the viewpoint of thermal depinning of flux lines. It is clarified that this depinning phenomenon is a transition of the second order. This result is consistent with the fact that the scaling of the current-voltage curves is well explained by the theoretical model of flux creep and flow. It is also found that the degree of disorder of the flux line lattice decreases abruptly with elevating temperature above the transition temperature. This agrees qualitatively with the observation of flux lines using a Lorentz microscope.         Determination of vortex motion characteristics, effective thickness and dynamic resistance in very thin YBaCuO bilayer structures    M. Pannetier, P. Bernstein, P. Lecoeur, O. Riou, T.D. Doan and J.F. Hamet Summary: In order to develop superconducting flux flow devices, we have measured the electrical characteristics of microbridges made from bilayers comprised of a conductive capping layer deposited on a very thin YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// film. In the flux creep regime, these structures show a low and quasi-constant depinning-to-critical current ratio and a high maximum vortex velocity. As expected from these features, the microbridges can be driven in the flux flow regime in the vicinity of T/sub c/. In the flux flow regime, surprisingly, the dynamic resistance is not an increasing function of temperature and shows a value which is in the range of the normal-state resistance at the onset of the superconductive transition.         An efficient AC susceptibility technique to study flux creep in HTS thin films    B.J. Jonsson and K.V. Rao Summary: The temperature and field dependent dynamical relaxation rate Q(T,H) has been determined for epitaxial c-axis oriented YBa/sub 2/Cu/sub 3/O/sub 7/ (Y-123) and HgBa/sub 2/CaCu/sub 2/O/sub x/ (Hg-1212) thin films using an efficient ac susceptibility technique. From a single temperature scan, in which consecutive measurements of /spl chi/' are performed at a number of frequencies in a relatively large ac field H/sub ac/, the frequency dependence of the critical current density J/sub c/(T,H/sub ac/,f) is determined as a function of temperature and ac field and Q(T,H/sub ac/) is subsequently extracted. From measurements of /spl chi/'(H/sub ac/,f) in a slowly ramped dc bias field, both the ac and dc field dependence of Q(T,H) can be studied. Q(T,H) for a Hg-1212 thin film is found to be independent of the ac field when the dc bias field fulfils H/sub dc/>2H/sub ac/. Compared to conventional magnetic relaxation, M-H loop recording and traditional ac susceptibility techniques, our ac susceptibility method is found to yield a considerably larger amount of information for a given measuring time. The ac susceptibility technique is found to reproduce the characteristic plateau-like temperature dependence of the relaxation rate for the Y-123 system. The relaxation rate for the Hg-1212 thin film shows a monotonic increase with temperature up to a maximum at about 95 K. Both films exhibit quantum creep of about Q(0)=0.01 in the field range studied.         Anderson theory of flux-creep in the presence of a pinning strength distribution for the washboard-type potential    A.N. Lykov Summary: Anderson theory is modified to explain the scaling behavior of the E-J curves, the logarithmic dependence of the potential barrier as a function of the transport current, the decrease of the barrier as the temperature goes to zero, and other results of the studies of flux creep in high-T/sub c/ superconductors. Moreover, the method provides the possibility of estimating the main pinning parameters of superconductors by fitting the calculated and experimental data.         Nonlinear I/spl sim/V characteristic and magnetic relaxation in high-T/sub c/ superconductors    W. Bai, G. Li, H. Chen, D. Yin, G. Lu, K. Chen and C. Li Summary: Large-scale applications of high-temperature superconductors require large critical current density J/sub c/. The limit of utilization is determined by the practical resistivity criterion and the current voltage characteristic of a superconductor which is highly nonlinear in these materials. Various models with different barrier-current dependencies U(J) have been developed to describe the flux motion in them but questions still remain. We show that these models may be unified to a general materials equation which gives a consistent description of different regimes of flux motion. We compare this equation with recent pertinent experiments and find fair agreements.         Current-voltage characteristics of melt-textured YBCO obtained from the field-sweep rate dependence of magnetization    H. Yamasaki and Y. Mawatari Summary: We investigated current-voltage (I-V) characteristics in melt-textured YBCO sheets by measuring the field-sweep rate /spl beta/ dependence of magnetization M. We used a previously developed method that corrects for the current density distribution in the specimen [Y. Mawatari et al., Appl. Phys. Lett., vol. 70, 2300 (1997)]. For a wide temperature and field range (60-80 K, 0.2-5.0 T) the I-V curves followed a power-law behavior that often has been observed in high-T/sub c/ superconductors. We also investigated the relaxation of magnetization, flux creep. The time dependence of M also followed a power-law behavior, which was as expected because of the power-law I-V characteristics.         Critical current of YBCO grain boundaries in large magnetic fields    D.T. Verebelyi, C. Prouteau, R. Feenstra and D.K. Christen Summary: Superconducting electrical transport across single grain boundaries (GBs) in YBCO shows interesting behavior in substantial magnetic fields. Measurements on [001] tilt bicrystal YBCO thin films in strong magnetic fields are consistent with the following: Low-angle GBs (<10/spl deg/) are composed of well-ordered bridges that act as strong superconducting inter-granular links; large-angle GBs exhibit weak coupling behavior that retains a well defined critical current even at high field.         Temperature dependence of the intragrain critical current density in polycrystalline Ag-sheathed Bi(2223) tapes (p2667)    G. Grasso, M.R. Cimberle, C. Ferdeghini, A.S. Siri, F. Marti and R. Flukiger Summary: The temperature dependence of the intrinsic (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ current density has been evaluated inside Ag sheathed tapes. By comparing transport and magnetic measurements performed on multifilamentary (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ tapes, we individuate a domain of the H-T plane where the current density is limited by the quality of the boundaries between neighboring grains and the tape behaves as a granular superconductor and, on the contrary, the domain where it behaves like a single crystal. At temperatures below 30 K in absence of applied fields, we find that the intragrain current density is about an order of magnitude larger than the transport current density.         Direct identification of extended defects as vortex pinning centers in melt textured YBa/sub 2/Cu/sub 3/O/sub 7/-Y/sub 2/BaCuO/sub 5/ composites    T. Puig, X. Obradors, B. Martinez, F. Sandiumenge, J. O'Callaghan and J. Rabier Summary: Single domain YBa/sub 2/Cu/sub 3/O/sub 7/-Y/sub 2/BaCuO/sub 5/ melt textured ceramic composites have revealed a very rich microstructure, which has usually impeded, by using standard measurements, to evaluate the contribution of each defect to the enhancement of the critical current. We have measured the in-plane magnetoresistance anisotropy and the anisotropic in-plane inductive critical currents and we show that together with the microstructural TEM analysis, the contribution of the different extended pinning centers can be separated. These results have allowed us to infer the kind of microstructure modifications required to improve the critical current. In particular, we present an isostatic pressing deformation technique as a very promising post-processing treatment to strongly increase the critical currents of these composites.         Temperature dependence of the intragrain critical current density in polycrystalline Ag-sheathed Bi(2223) tapes (p2659)    G. Grasso, M.R. Cimberle, C. Ferdeghini, A.S. Siri, F. Marti and R. Flukiger Summary: The temperature dependence of the intrinsic (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ current density has been evaluated inside Ag sheathed tapes. By comparing transport and magnetic measurements performed on multifilamentary (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ tapes, we individuate a domain of the H-T plane where the current density is limited by the quality of the boundaries between neighboring grains and the tape behaves as a granular superconductor and, on the contrary, the domain where it behaves like a single crystal. At temperatures below 30 K in absence of applied fields, we find that the intragrain current density is about an order of magnitude larger than the transport current density.         Influence of surface barriers on vortex dynamics in Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// whiskers    M.S. James, S.J. Bending, S.T. Stoddart, S. Aukkaravittayapun, P.J. King and M. Henini Summary: Bi/sub 2/Sr/sub 2/CaCa/sub 2/O/sub 8+/spl delta// whiskers are single crystals with highly regular surfaces and few extended defects, making them excellent model systems for studying the role of surfaces in magnetization. Furthermore, they can be elastically bent without losing their superconducting properties, making them potentially important technological materials. We have made a detailed investigation of their magnetic properties using micron-sized Hall probe arrays and show that surface effects play a dominant role in controlling the vortex dynamics, particularly in the moderate to high temperature regime. Local magnetic induction cycles exhibit the asymmetric behaviour characteristic of surface barriers and when the whiskers are slowly field cooled, sharp jumps are observed. The systematic behaviour of these jumps leads us to speculate that they represent sudden configurational rearrangements as a result of the interplay between vortex-surface barrier and vortex-vortex interactions.         Numerical simulations of elastic properties of flux-line lattices in high-T/sub c/ superconductors    Zhi-Xiong Cai, D.O. Welch and G.S. Dubey Summary: We propose a quantitative model of the effective interaction between the magnetic flux-lines in a layered superconductor. It is derived from the Lawrence-Doniach model with all of its parameters derivable from experiments. Numerical simulations are performed using the Langevin dynamics technique for parameters suitable for Bi-2212. We studied the elastic properties of flux line lattices with various values of interlayer coupling strength and pinning strengths. We show that the "softening" of the flux-line lattices with increasing temperature is mainly due to the increase of configurational entropy of the lattice. The calculated results show good agreement with experimental observations and provide a unique way to study the properties of flux-line lattices with random pinning.         Inhomogeneous magnetic flux distribution in Ag/Bi2223 tapes    K. Osamura, K. Matsuno, H. Itoh, T. Horita, H. Tsurumaru and A. Sakai Summary: The self magnetic field when applying transport current and the residual magnetic flux density after removing the external field were measured by means of scanning Hall probe technique and converted to the local current density distribution. The transport current density as well as the shield current density became highest at the edge part of the oxide core in Ag sheathed Bi2223 tape, which are larger than the transport critical current density measured by four terminal method. Inhomogeneity of magnetic field distribution along the current flow direction was attributed to the positional change of oxide layer thickness. The degree of inhomogeneity decreased for the tape with the higher transport critical current density.         Enhanced current capacity of jelly-roll processed and transformed Nb/sub 3/Al multifilamentary conductors    T. Takeuchi, K. Tagawa, T. Kiyoshi, K. Itoh, M. Kosuge, M. Yuyama, H. Wada, Y. Iijima, K. Inoue, K. Nakagawa, G. Iwaki and H. Moriai Summary: In order to enhance the current carrying capacity, we have developed an improved fabrication process where the wire diameter can be increased from 0.5 to 1.25 mm and the Nb-matrix ratio decreased from 1.5 to 0.52, without degrading the critical current density, J/sub c/, of Nb/sub 3/Al phase. The critical current for a monolithic conductor at 21 T and 4.2 K has now been enhanced to 166 A which used to be 15 A. The compacted-strand-cables were fabricated to investigate feasibility for large-scale application uses. We have found that stranding and flat-rolling the as-quenched Nb/Nb(Al)/sub ss/ composite cause no degradation in J/sub c/. Attempts were made to stabilize the resulting high current conductors.         Development of Nb/sub 3/Al superconductors for ITER    N. Ayai, Y. Yamada, A. Mikumo, M. Ito, K. Ohmatsu, K. Sato, N. Koizumi, T. Ando, K. Matsui, M. Sugimoto, H. Tsuji and K. Okuno Summary: In the International Thermonuclear Experimental Reactor project, the Nb/sub 3/Al superconductor has been recognized as one of the candidates for the Toroidal Field Coil superconductor. An Nb/sub 3/Al Insert will be tested in the bore of the Central Solenoid Model Coil under ITER Engineering Design Activities. The authors developed the copper stabilized multifilamentary strand using the jelly-roll process for the Nb/sub 3/Al Insert. The strand had Jc above 600 A/mm/sup 2/ at 12 T under the bending strain of 0.4%, the hysteresis loss density lower than the 410 mJ/cc in the alternative magnetic field of +/- 3 T parallel to the wire axial direction and the residual resistivity lower than 1.6/spl times/10/sup -10/ /spl Omega/m. We have developed a large scale multifilamentary billet from which a 16 km wire could be obtained. Total 230 km strands were manufactured from the large scale billet. A yield of 90% was obtained for the wire longer than 500 m and 70% for the wire longer than 1500 m. The maximum unit length reached 4600 m.         Process development and microstructures of Nb/sub 3/Al precursor strand for reel-to-reel production    E. Gregory, M. Tomsic, F. Buta, M.D. Sumption and E.W. Collings Summary: Niobium-aluminum precursor strands were fabricated using a modified form of the rod-in-tube method (MRT) and also the conventional jelly-roll (JR) method. Monoelements with Nb/Al volume ratios of 2.3, 2.7, 3, and 5 were drawn down and restacked into groups of 7/spl times/37 and 37/spl times/37 (MRT), also 7, 19, and 36 (JR) elements. Suitably clad, these were reduced to final strand sizes of 1.6, 1.2, and 0.8 mm (MRT) also 0.8 and 0.4 mm (JR). In this way, the thickness of the Al component of the Nb/Al composite was reduced to sizes in the range of 2.5 to 0.1 /spl mu/m. Although most of the material produced to date has been fully cold drawn, warm hydrostatic extrusion has been explored for use in the next phase of strand production. The MRT and JR strands, in short-sample form, have been subjected to pulsed resistive heating to temperatures of typically 1800 to 2100/spl deg/C followed by either radiative cooling or liquid-Ga quenching. Studies of the relationship between Al-element thickness and final properties have been made.         Effects of additional elements to Nb/sub 3/Al multifilamentary wire fabricated by rapid-heating/quenching process    Y. Iijima, A. Kikuchi, K. Inoue and T. Takeuchi Summary: We have developed an RHQT process (Rapid-Heat, Quench, and Transformation), for fabricating Nb/sub 3/Al multifilamentary wires, which showed 2 to 5 times larger J/sub c/ (4.2 K) than those of commercially available Nb/sub 3/Sn multifilamentary superconducting wires. We studied the effects of Mg and Ge additions to the RHQT-processed Nb/sub 3/Al multifilamentary wire. In order to add Mg and Ge, Al-5at%Mg alloy and Al-20at%Ge alloy were used instead of pure Al for making the precursors of Nb/sub 3/Al multifilamentary wire, respectively. The Mg addition reduced T/sub c/ of the Nb/sub 3/Al multifilamentary wire a little from 17.6-17.9 K to 17.1-17.4 K, but had no apparent influence on H/sub c2/ (4.2 K) of 25-27 T. The large J/sub c/ (4.2 K, 20 T) of 200-450 A/mm/sup 2/ were obtained for the Nb/sub 3/Al multifilamentary wire independently of the Mg addition. On the other hand the Ge addition increased not only T/sub c/ of Nb/sub 3/Al multifilamentary wire from 17.6 K to 19.4 K, but also H/sub c2/ (4.2 K) from 25.4-27.2 T to 34.0-39.4 T. The Ge addition improved drastically the J/sub c/ (4.2 K) in fields above 22 T, but reduced the J/sub c/ (4.2 K) in low fields.         Strain and grain connectivity in Bi2223/Ag superconducting tapes    Ying Kai Huang, B. ten Haken and H.H.J. Ten Kate Summary: The critical current reduction in silver-sheathed (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ superconducting tapes (Bi2223/Ag) is investigated when loaded with uni-axial strains in combination with a magnetic field perpendicular to the tape surface. The number and quality of the grain-to-grain connections and the alignment of the superconducting cores mainly determine the critical current in Bi2223/Ag tapes. It is assumed that the transport current flows simultaneously through two current carrying paths in the tape: one through the network of Josephson junctions and the other is through the well-connected grains. The model describes well the magnetic field dependence of the critical current at various strains. A detailed analysis has shown that strain deteriorates grain connectivity, induces cracking and hence changes the current carrying path. Furthermore, strain may introduce new defects inside the grains along the strong-link current path and increase intra-granular pinning strength.         Development of reinforced Ag alloy sheathed Bi2223 tapes    Y. Hikichi, T. Koizumi, T. Hirota, A. Imai and T. Hasegawa Summary: We developed the Ag-Mg-Sb alloy which had a tensile strength of about 500 MPa and elongation of 5.5%. The tensile strength of 150 MPa was obtained at room temperature in the Bi-2223 tape using this Ag-Mg alloy for the outer sheath. The J/sub c/ value of the Ag-Mg alloy sheathed Bi-2223 tape has come to be above 10/sup 4/ A/cm/sup 2/ at 77 K in self field. And the J/sub c/ value was kept until a tensile stress of 120 MPa was applied. The critical bending strain of the tape was the same as that of the pure Ag sheathed tape. These results indicated that this tape was tolerant of the mechanical stress in the manufacturing process and hoop stress during the magnet operation.         Fabrication and properties of some Ag-alloy sheathed Bi-2223 tapes    R. Zeng, Y.C. Guo, Y. Tanaka, J. Horvat, M. Ionescu, T.P. Beales, M. Apperley, H.K. Liu and S.X. Dou Summary: Mono and multifilamentary powder-in-tube tapes with sheaths of Ag, AgCu/sub 0.02/, Ag(AgCu/sub 0.02/), AgAl/sub 0.25/, Ag(AgAl/sub 0.25/), AgNi/sub 0.25/Mg/sub 0.25/, AgTi/sub 0.25/Mg/sub 0.25/, and AgTi/sub 0.25/ alloys have been fabricated and their physio-chemical properties and effect on the phase formation of Bi-2223 determined. Alloying was found to have a significant effect on phase formation of the Bi-2223 phase formation linked to the alloying elements reactive to oxygen, Cu         Dislocation-assisted-diffusion model for the kinetics of bismuth cuprate 2212-to-2223 transformation    Zhi-Xiong Cai and Yimei Zhu Summary: Recent transmission electron microscopy (TEM) experiments have shown that the transformation of the Bi cuprate 2212 phase to 2223 phase consists of random intercalation and fast growth of Ca/CuO/sub 2/ planes in the Bi-2212 matrix. This contradicts the prediction of the conventional nucleation and growth theory. A model is proposed which considers the cylindrical void created by the edge dislocation due to the insertion of a Ca/CuO/sub 2/ plane to be a channel for fast ion diffusion. The experimentally observed time dependence of the volume fraction of Bi-2223 during the transformation is found to be consistent with a one-dimensional diffusion-controlled transformation mechanism, as predicted by our model. The formation energy of Bi-2223 is estimated and is consistent with the results of atomistic simulations.         Heat transfer and oxygen diffusion in Ag-clad BSCCO superconducting tapes    P.E. Phelan, R.N. Samant and S. Paluru Summary: The quality of Ag-clad BSCCO superconducting tapes is a function of their processing conditions. Two important processing parameters are the cooling rate from the annealing condition, and the oxygen partial pressure in the furnace. Although a link between oxygen content and critical current density has been established, apparently no attempts have been made to predict the temperature and oxygen content distributions within a Ag-clad BSSCO tape. This study presents a combined thermal and mass transfer model which enables the calculation of the oxygen content distribution, and the results indicate a slow cooling rate, and relatively high oxygen partial pressure, leading to a greater and more uniform oxygen concentration within the tape, and thus potentially superior superconducting properties.         Enhancing the engineering J/sub c/ of Bi-2223 multifilamentary tapes by two-axial rolling and periodic pressing    Y.B. Huang, F. Marti, G. Witz, R. Passerini, R. Flukiger and G. Grasso Summary: Bi-2223 multifilamentary tapes with a filling factor from 20 to 51% have been produced by a modified Powder-In-Tube method, where a two-axial rolling method is used to replace the standard drawing process. Because the two-axial rolling process does not apply tensile force during wire fabrication and every filament receives a very similar reduction during the deformation processing of the wire into a tape, the size homogeneity of filaments can be significantly improved for tapes with high filling factor. Combining this with a periodic pressing process, the engineering critical current density has been increased from 4 to 8 kA/cm/sup 2/ (77 K, 0 T) for tapes with a filling factor of 35%. The effect of deformation and heat-treatment conditions on the microstructure and transport properties has been found to be quite different in tapes with high filling factor.         Effect of cryogenic deformation on microstructure and critical current density in Ag/Bi-2223 tapes    H.K. Liu, Q.Y. Hu, X.Z. Liao, Y.C. Guo, J. Horvat and S.X. Dou Summary: The effect of deformation rate and silver hardness on J/sub c/ and microstructure of Ag/Bi-2223 tapes was studied under cryogenic processing conditions. It was found that cryogenic deformation improved the grain connectivity, alignment, Ag/core interface and critical current density. These benefits may be attributable to the increased extent of mechanical deformation. The hardness of the silver sheath during cryogenic mechanical deformation was significantly increased, allowing for a much larger load to be applied during the deformation process comparing to the mechanical deformation at room temperature. The maximum J/sub c/ appeared at a 20% reduction rate of the tape thickness for cryogenically processed Ag/Bi-2223 tape. Higher deformation rate decreases J/sub c/ for cryogenically processed Ag/Bi-2223 tape which can be explained by the results of TEM examination. TEM images show that the sample having low J/sub c/ had many small grains with large angle grain boundaries after recrystallisation when a high rate of thickness reduction (58%) was applied during the process, while the sample having high J/sub c/ had large grains with many small angle c-axis twist grain boundaries and small angle tilt grain boundaries when 19% of thickness reduction was applied during the process.         High electrical performance Ag-sheathed Bi-2223 multifilamentary tapes prepared by an optimised PIT processing route    R. Zeng, P. Yao, B. Zeimetz, T.P. Beales, H.K. Liu and S.X. Dou Summary: An optimised PIT processing route is introduced and discussed, using results from experiments investigating the effect of processing on microstructure, and subsequently on J/sub c/ in PIT tapes. At 77 K and self-field, the highest J/sub c/ performance of 51000A/cm/sup 2/ has been obtained for 69-filament tapes. High critical current samples with I/sub c/=108A and J/sub c/=36000A/cm/sup 2/ have been measured at 77 K and self-field for 361-filament tapes. Our results indicated that J/sub c/ is influenced by the Pb distribution of Pb-2212, phase composition for the precursor powder, the deformation reduction rate, and the core thickness. Intermediate processing (cooling, deformation and heating) between thermal-mechanical cycles and finally cooling procedures also play an important role on Bi-2223 phase purity and achievement of such high electrical performance in the tapes.         Effect of short processing time on Bi-2223 phase formation kinetics and critical current in Bi-2223/Ag tapes    R. Zeng, H.K. Liu, T.P. Beales and S.X. Dou Summary: Bi-2223 volume fraction and the critical current (I/sub C/) in Bi-2223/Ag tapes exhibited maximum values (f/sub 2223 max/ and I/sub Cmax/) versus sintering time; on further heating the Bi-2223 phase decomposed and the I/sub C/ decreased. The total time to reach I/sub Cmax/ is defined as t/sub c/. Based on the investigation of the effect of processing on Bi-2223 phase formation kinetics, an optimal processing to substantially reduce the processing time in Ag-sheathed Bi-2223 tapes was introduced in this paper. It was found that, after 10-15 h sintering, the Bi-2223 phase formation rate decreased. An intermediate procedure using quench, pressing or rolling and then rapid heating can avoid unnecessary Bi-2223 phase decomposition and recovery, decrease the diffusion distance and substantially reduce the sintering time in Bi-2223/Ag tapes. The t/sub c/ was reduced to 30 h or even 20 h and J/sub c/ reached 40-50 kA/cm/sup 2/ for multifilamentary tapes. Our results indicated that Pb distribution in precursor powder plays an important role on fast phase formation. Fabrication of high J/sub c/ tapes in a short time is desirable to scale-up production of Ag/Bi2223 tapes.         Pre-industrial PIT conductor and coil development at Alcatel    P.F. Herrmann, E. Beghin, G. Duperray, F. Grivon, D. Legat, A. Leriche, J.P. Tavergnier, P. Marlin and Y. Parasie Summary: In 1995 the PIT conductor development was strengthened at Alcatel and important progress has been achieved since. During 1997 the patented rectangular Alcatel route was upscaled and pre-industrial conductors have been fabricated in a wire drawing mill. After the successful transfer the first high performance conductors have been realized in kilometer lengths. The conductors are realized in cooperation with Aventis Research and Technologies using precursor powders optimized for the Alcatel conductor route. The simpler Bi-2212/AgPd matrix conductor is used as a working horse where engineering current densities of J/sub e/=65 kA/cm/sup 2/ have been reached at 4 K, 0 T. Significant progress has also been achieved on Bi-2223 conductors where critical current densities of J/sub c/=30 kA/cm/sup 2/ at 77 K, 0 T are reached. First solenoids generating a field up to 2.3 Tesla have been realized using Bi-2212 conductors. In a background field of 3 Tesla this magnet still generates a field of 2 Tesla. The results on test coils are consistent with J/sub c/(H) measurements on short samples showing that an important step towards high homogeneity conductors has been achieved.         Significantly enhanced critical current density in Bi-2223/Ag multifilamentary tapes by hot pressing    R. Zeng, B. Ye, J. Horvat, Y.C. Guo, B. Zeimetz, X.F. Yang, T.P. Beales, H.K. Liu and S.X. Dou Summary: Bi-2223/Ag multifilamentary tapes were fabricated using a hot-pressing technique to investigate its effect on grain connectivity and flux pinning. The critical current density in tapes after hot-pressing was doubled. J/sub c/ increased from 26000A/cm/sup 2/ to 56100A/cm/sup 2/ in a 19-filament tape. However, the critical current density in an applied magnetic field was not improved by hot-pressing. The fraction of strong links (I/sub C0//sup s//I/sub C0/) was improved from 47% to 68% in a 19-filament tape due to hot pressing. Microstructural analysis showed that hot-pressing improved grain connectivity, increased core density and reduced secondary phases.         Correlation of critical current density and phase conversion at different final cooling rate in Ag-sheathed PbBi2223 tapes    S.P. Feltham, L.N. Law, T.J. Hughes, Y. Yang, C. Beduz and R. Riddle Summary: As shown by Parrell et al., a final reduced cooling rate can produce an improvement of the optimum critical current in field. In this paper we present results on the critical current density and magnetic field dependence of Ag-sheathed (Pb,Bi)-2223 multifilamentary tapes as a function of the final sintering time for different cooling. Correlation between 2223 phase conversion, as determined by XRD, and the critical current density is also examined. For samples slow cooled to 800/spl deg/C at 1/spl deg/C/h followed by furnace cooling to room temperature, the critical current density remained almost constant at 20 KAcm/sup -2/ with different final sintering times between 10 to 150 hours. In contrast samples slow-cooled to 730/spl deg/C at 1/spl deg/C/h showed a decreased J/sub c/ of 7 KAcm/sup -2/ for a short final sintering time of 10 hours, rising gradually to 22 KAcm/sup -2/ at 200 hours. Corresponding to this, the samples cooled to 800/spl deg/C show a phase composition of 90% apparent (Pb,Bi)-2223 for all times, as opposed to a gradual increase of the (Pb,Bi)-2223 phase from 65% to 90% with increasing sintering time for samples slow cooled to 730/spl deg/C. As the conditions are exactly the same prior to the cooling below 800/spl deg/C, the reduced conversion for the samples slow cooled to 730/spl deg/C must be the result of 2212 precipitation from the apparent (Pb,Bi)-2223 phase present at 800/spl deg/C.         The effects of adding fully reacted Bi-2223 seed particles on the phase transformation and microstructure of Ag/Bi-2223 tapes    Weon-Ju Kim, Hee-Gyoun Lee, Sun-Chil Kwon, Ki-Baik Kim, Ho Jin Lee and Gye-Won Hong Summary: The effect of adding fully reacted (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/ Cu/sub 3/O/sub y/ (Bi-2223) particles to the precursor powder on the final property of Ag/Bi-2223 tapes has been investigated. Different amounts of fully reacted Bi-2223 particles ranging from 0 to 10 wt% were added to the precursor powder consisting of mostly Bi-2212 and calcium plumbate phases. The tapes seeded with Bi-2223 particles showed a relatively high J/sub c/ in a short annealing time without mechanical deformation steps. The existence of Bi-2223 particles in the precursor powder resulted in a smaller grain size, showed no appreciable incubation period and a faster transformation rate in an isothermal annealing experiment compared to the tape containing no seed particles. A detailed analysis of the microstructure and phase transformation kinetics indicates that a two dimensional nucleation and growth process is the most plausible mechanism for Bi-2223 phase formation. For the tapes containing seed particles, the formation rate of Bi-2223 phase was found to be controlled by the diffusion of material, while the formation of nuclei controlled the Bi-2223 formation for the tape containing no seed particles.         Properties of Bi(Pb)-2223 precursor powders calcined in reduced oxygen partial pressure    Weon-Ju Kim, Hee-Gyoun Lee, Sun-Chil Kwon, Ki-Baik Kim, Ho Jin Lee and Gye-Won Hong Summary: The performance of Ag/Bi-2223 superconducting tapes is affected by complex processing parameters, especially by the characteristics of the precursor powder, i.e., the nominal stoichiometry, phase assemblage, purity, particle size and distribution, etc. Calcination in a low oxygen partial pressure (3 torr oxygen) resulted in a reactive precursor powder by the accelerated decomposition of the carbonates. In addition, the type of second phase and the distribution of lead in this precursor powder are different compared to those of the powder calcined in atmospheric air. Ag/Bi-2223 tapes have been fabricated and the phase evolution, critical current density, and microstructure of the two tapes have been compared.         Cooling behavior of BSCCO/Ag tapes    L.G. Andersen, H.F. Poulsen, T. Frello, N.H. Andersen and M. von Zimmermann Summary: The phase transformations taking place during cooling of BSCCO/Ag tapes have been investigated by means of high energy X-ray diffraction at a synchrotron source. This technique allows in-situ measurements of the concentration changes of the major structural phases, including liquids. In addition, information is obtained on stoichiometry and texture variations. Two mono-filament tapes were studied in air. The first tape was cooled at a constant rate of 50/spl deg/C/h. At temperatures above 730/spl deg/C the (Ca,Sr)/sub 2/CuO/sub 3/ and liquid phases are almost completely converted to 2212 and 2223. Below 780/spl deg/C a Pb-rich phase appears, either 3221 or (Ca,Sr)/sub 2/PbO/sub 4/. Simultaneously, shifts of X-ray lines indicate that 2223 is deprived of Pb, and from 730/spl deg/C onwards the concentration of 2223 drops. The second tape was cooled in steps to sequentially lower temperatures: 845/spl deg/C, 820/spl deg/C and 660/spl deg/C. At the former two steps (Ca,Sr)/sub 2/CuO/sub 3/ and liquid phases are again converted to 2212 and 2223, while at 660/spl deg/C they are rapidly converted to 2212 and-primarily-2201. Also at 660/spl deg/C, 2223 decomposes to 3221 or (Ca,Sr)/sub 2/PbO/sub 4/ at a rate of 40% per hour.         Continuous multistrand assembly techniques for Ag clad superconducting wire    K. DeMoranville, P. Antaya, C. Martin, Q. Li, G.N. Riley Jr., S. Hancock, M. Simpson, J. Marquardt and D. Tatelbaum Summary: A method to continuously combine and deform silver clad superconducting strands has been developed. This technique has been used to fabricate multifilament superconducting tapes consisting of Bi-2223, high temperature superconducting precursors. Results show that silver has the unique ability to be bonded together in a continuous strand process without requiring a protective atmosphere. The approach uses a continuous process to combine relatively fine wires that are aligned in the desired configuration, held in intimate contact and heat-treated to promote metallurgical bonding. Silver grain growth across strand interfaces has been documented in processed tapes and lengths approaching 100 meters have been fabricated. Engineering critical current densities (J/sub c/) as high as 19000 amps/cm/sup 2/ (77 K, self-field, 1 /spl mu/V/cm) have been recorded in short samples.         The influence of long reaction time on various properties of monocore Bi-2223/Ag tapes    F. Marti, M. Dhalle, R. Flukiger, G. Grasso and J.-C. Grivel Summary: The mechanisms leading to a maximum of j/sub c/ as a function of reaction time in (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ monofilamentary tapes are investigated. Various properties of tapes previously reacted 40 hours in air at 837/spl deg/C, rolled, and submitted to additional reaction during times varying from 40 to 240 hours were measured. The evolution of morphology, phase assembly, stoichiometry, weight, critical temperature, critical current and irreversibility line is described. XRD and SEM analysis reveal no decomposition of the Bi(2223) phase and no noticeable grain growth in the time window under investigation. Pb losses as function of reaction time up to 40% were detected by means of thermogravimetry and EDX, while an increase of T/sub c/ from 107.25 to 109.1 K was observed. Transport and magnetic measurements show that the observed maximum of j/sub c/ at about 180 hours is the result of two competing effects: a) an improvement of the quality of grain boundaries and b) a decrease of the pinning efficiency in the grains.         Fabrication and properties of high J/sub c/ multifilamentary (Bi,Pb)-2223 tapes with Ag-alloy sheath    P.X. Zhang, H. Maeda, L. Zhou, C.S. Li, Z.Z. Duan and H.L. Zheng Summary: (Bi,Pb)-2223 tapes with 37 filaments have been fabricated by powder in tube (PIT) method. Silver was used for the sheath of filaments and the Ag-Mn-Ni alloy was used for the outer sheath of the tapes. A high critical current density of 29000A/cm/sup 2/ (77 K, 0 T) has been achieved in rolled tape with Ag-alloy sheath, in this case the critical current of the tapes is 81.5A, which is higher than that of multifilamentary tapes with pure Ag sheath prepared by the same process. The precursor powders prepared by mixing the (Bi,Pb)-2212 and CaCuO/sub 2/ has been considered to be beneficial for fabricating high J/sub c/ multifilamentary tapes with Ag-alloy sheath. The superconducting properties and microstructural characteristics of the multifilamentary tapes have been investigated in this work.         Author Index (1998 - Part 2)    No author information available Summary: Not available

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