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1994 Part 2     Front Cover (1994 - Part 2)    No author information available Summary: Not available         Table of Contents (1994 - Part 2)    No author information available Summary: Not available         Advances in the development of silver sheathed (Bi,Pb)2223 composite conductors    W.L. Carter, G.N. Riley Jr., A. Otto, D.R. Parker, C.J. Christopherson, L.J. Masur and D. Buczek Summary: Significant advances have been made in the critical current density of the technologically interesting (Bi,Pb)2223 composite conductors. Engineering current density, J/sub e/, of 9100 A/cm/sup 2/, corresponding to a filament current density, J/sub c/, of 32600 A/cm/sup 2/ (77 K, self-field) has been achieved by increasing the fraction of oxide in the conductor and improving the thermomechanical processing of the conductor. The filament microstructure may be further optimized by decreasing the volume fraction of secondary phases and porosity. The strain tolerance of the higher oxide fraction conductors remains adequate for applications by increasing the number of filaments in the conductors. Composite tapes with twisted filaments have been produced that have promising electrical properties in applied magnetic fields.         Critical current densities at 77 K and 4.2 K of Bi(2223) tapes prepared by cold and hot deformation    R. Flukiger, G. Grasso, B. Hensel, M. Daumling, A. Jeremie, A. Perin, J.C. Grivel and R. Gladyshevskii Summary: Monofilamentary Bi(2223) tapes have been prepared by the Powder-In-Tube technique using various alternatives for the final thermomechanical processing. In particular, both cold and hot deformation processes were investigated and their critical current densities at 77 K and 4.2 K were measured. For long cold rolled Bi(2223) tapes, transport j/sub c/ values up to 30000 A/cm/sup 2/ were obtained at 77 K and 0T. The value of j/sub c/ was found to increase from 17000 A/cm/sup 2/ at the oxide center to 46000 A/cm/sup 2/ at the borders of the oxide layer. At 4.2 K and 28 T, j/sub c/ values of 45000 and 30000 A/cm/sup 2/ were measured for B parallel and perpendicular to the tape surface, respectively. The j/sub c/ (B) hysteresis was found to disappear at higher fields. The present state of hot deformed Bi(2223) tapes is presented. For rolling temperatures up to 850/spl deg/C, a maximum of j/sub c/ (77 K, 0T)=18000 A/cm/sup 2/ was observed at 800/spl deg/C, j/sub c/ being considerably lower for higher rolling temperatures. The results obtained so far show generally lower j/sub c/ values than for cold rolled tapes. This is essentially due to microcracks and to sausaging effects, which are more pronounced than for cold rolled tapes. For static hot deformation at 800/spl deg/C of short, pressed Bi(2223) tapes an enhancement of j/sub c/ (77 K, 0T) by 20% up to >40000 A/cm/sup 2/ was observed. In addition, the decrease of j/sub c/ for B perpendicular to the tape surface is less pronounced compared to cold deformed tapes.         Progress towards a long length metallic precursor process for multifilament Bi-2223 composite superconductors    A. Otto, L.J. Masur, C. Craven, D. Daly, E.R. Podtburg and J. Schreiber Summary: A process based on metal precursors has been developed for fabricating 361-filament Bi-2223 oxide superconductor-silver composite tapes with oxide and whole wire critical current densities of 20.8 kA/cm/sup 2/ and 3.74 kA/cm/sup 2/ at 77 K over 85 m (1 /spl mu/V/cm criterion). Fabrication of approximately 50 m lengths for a cumulative 1 km yielded average oxide critical current densities of 15.2 kA/cm/sup 2/ and 11.9 kA/cm/sup 2/ using 1 /spl mu/V/cm and 10/sup -11/ /spl Omega/ cm criteria. Within tape I/sub c/ variability was less than 5% except for I/sub c/ drop-offs near the tape ends. The oxide superconductor exhibited a high degree of the required texture. A 1.12 T (at 4.2 K) instrumented magnet with a 2.5 cm bore was fabricated by a react- and-wind approach from the tapes and delivered to Oak Ridge National Laboratory for quench studies.         Improved J/sub c/ property of Bi2223 tapes made using AgCu alloy-sheath doped with Ti, Zr, Hf or Au    Y. Tanaka, F. Matsumoto, H. Maeda and M. Ishizuka Summary: Bi2223 superconducting tapes have been prepared by the powder-in-tube technique using Ag-10at%Cu-xat%M (x=0-1.0, M=Ti, Zr, Hf or Au) alloy sheaths. The alloy-sheathed tape samples, prepared by repeating 2 or 3 times of sintering and cold pressing, showed high J/sub c/ values. The higher critical current densities, J/sub c/'s, 5-6/spl times/10/sup 4/A/cm/sup 2/, at 4.2 K, 14 T were obtained for the Ag-10at%Cu-(0.03-0.1at%Ti, 0.1at%Zr, 0.1at%Hf and 0.3at%Au) tape samples. Microstructural examinations of these samples revealed a modified Bi2223 grain structure at the sheath/core interface and also a denser and more aligned microstructure. X-ray diffraction analysis, vibrating sample magnetometer measurement and ac susceptibility studies seem to suggest an enhancement of the Bi2223 phase formation with high T/sub c/ and improved texture, resulting in higher J/sub c/.         The influence of filament size and atmosphere on the microstructure and J/sub c/ of round multifilament Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub x/ wires    L.R. Motowidlo, G. Galinski, G. Ozeryansky, W. Zhang, E.E. Hellstrom, M. Sumption and T. Collings Summary: Round multifilament Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub x/ wires having 37 and 259 filaments fabricated by the oxide-powder-in-tube method were given a step solidification partial melt heat treatment in air and oxygen atmospheres. Significant improvement in the critical current density (J/sub c/), as high as 1.65/spl times/10/sup 5/ A/cm/sup 2/ at 4.2 K zero field, was obtained for samples treated in pure oxygen versus air anneals. Moreover, as the filament size decreased the J/sub c/ increased. We discuss the development of 2212 microstructure and its dependence on filament size and heat treatment atmosphere in round multifilament 2212 wires.         Effect of composition and oxygen content on the microwave properties of evaporated Y-Ba-Cu-O thin films    N.G. Chew, J.A. Edwards, R.G. Humphreys, J.S. Satchell, S.W. Goodyear, B. Dew, N.J. Exon, S. Hensen, M. Lenkens, G. Muller and S. Orbach-Werbig Summary: Thin films of YBa/sub 2/Cu/sub 3/O/sub 7-x/ have been grown by electron beam evaporation of the metals in the presence of atomic oxygen, with small systematic variations in cation composition. Films grown close to the stoichiometric composition or with excess yttrium are smooth while those with excess barium are substantially rougher. The effect of these differences in cation composition on both microwave and dc properties is dominated by the associated large changes in film morphology. This determines the oxygenation state, and hence the electrical properties, of the superconductor both in the as-grown state and after annealing in a furnace or with atomic oxygen. For all films a strong correlation is found between penetration depth, resistivity and c-lattice parameter which all decrease with increasing oxygen content. In our standard growth regime and at higher oxygen contents the films are overdoped and T/sub c/ falls with increasing oxygen content.         Effect of oxygen over-doping on T/sub c/ and R/sub s/ of YBCO films    J.R. Gavaler, J. Talvacchio and R.W. Weinert Summary: Data on bulk YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) have shown that optimum critical temperatures are obtained in material that has less than the maximum (stoichiometric) oxygen content, x=0. We have prepared films of YBCO that were over doped with oxygen and have measured their properties. In some of these films, T/sub c/'s were degraded to as low as 85 K and R/sub s/'s to >10 m/spl Omega/ (at 77 K and 10 GHz). Re-annealing at 450/spl deg/C at experimentally optimized oxygen pressures raised T/sub c/'s significantly in all cases but had only a marginal effect on R/sub s/ values. Large improvements in R/sub s/ were obtained in the films which initially had very high surface resistances only by annealing them at higher temperatures. Growth and annealing conditions are described by which YBCO films with T/sub c/'s of >90 K and R/sub s/'s of /spl les/0.5 m/spl Omega/ (at 77 K and 10 GHz) were prepared.         Laser patterning of YBa/sub 2/Cu/sub 3/O/sub x/ thin films protected by in-situ grown SrTiO/sub 3/ cap layer    W. Kula, Wei Xiong, R. Sobolewski and J. Talvacchio Summary: We report our studies on laser processing techniques suitable for patterning of YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) thin films, as well as YBCO/SrTiO/sub 3/ bilayers, consisting of in-situ grown YBCO films with 100-nm-thick single-crystalline SrTiO/sub 3/ cap layers. The patterning is achieved through both laser inhibition, in which an intense, focused laser beam locally melts YBCO transferring it into an insulating glass-like material, and laser writing, based on a laser-controlled diffusion of oxygen in or out of the YBCO film. We have found that oxygen easily migrates through the SrTiO/sub 3/ layer, allowing to reversibly convert the underlying YBCO film between the superconducting and semiconducting (virtually insulating at low temperatures) phases. Using laser inhibition and writing, we were able to form in a single YBCO/SrTiO/sub 3/ sample well-defined regions of various electrical properties, showing that laser processing can be successfully used in patterning and/or electrical trimming of multilayered YBCO circuits. Aging studies, performed on an almost 2-years-old laser-written YBCO film, showed a very good, both structural and electrical stability of our laser-processed structures.         Ion implantation in high temperature superconducting films    Q.Y. Ma, A. Wong, J.F. Carolan, W.N. Hardy, H. Kato, D. Hui and N.A.F. Jaeger Summary: Reactive ion implantation (RII) has been used to inhibit superconductivity in oxide superconductor materials. By introducing ions which are chemically reactive with oxygen into a high temperature superconductor (HTS) oxide film, the conductivity of the material may be inhibited by the interaction of the implanted ions with the oxygen in the oxide. Both Si and B ions, with doses ranging from 1/spl times/10/sup 15/-1/spl times/10/sup 17//cm/sup 2/, were implanted into epitaxial YBCO films with injection energies ranging from 20-180 keV, depending on the film thickness. The implanted ions do not alter the overall crystal structure of the HTS film, but do inhibit the electrical conductivity and diamagnetism. Multiple ion implantations have also been employed to achieve uniform ion distributions.         High energy physics conductor scale-up progress of the Supercon artificial pinning center process    J.M. Seuntjens, M.K. Rudziak, C. Renaud, T. Wong and J. Wong Summary: The Supercon APC process is briefly reviewed. Process parameters requiring optimization for commercial production are discussed. Issues involved in successful monofilament and multifilament billet size scale-up the APC process for HEP composites, nominally 6 /spl mu/m filaments and composite diameters <1 mm, are presented. The Supercon APC composite piece length and mechanical properties are excellent. The present best composite J/sub c/ results are presented.         First commercial application of NbTi superconductor employing artificial pinning centers    C. Renaud, M. Rudziak, J. Seuntjens, T. Wong, J. Wong, P. Eckels, C. King, T. Havens, D. Mantone, B. Myers and S. Wong Summary: Supercon has applied its artificial pinning center (APC) technology to develop a multifilamentary NbTi superconductor for MRI application. This technology is particularly well suited to large filament, low field use. The conductor microstructure and performance (e.g., critical current) are presented. The influence of conductor geometry (e.g., filament placement, spacing to diameter ratio) on filament quality is discussed. The conductor has been incorporated into Magnetic Resonance Imaging (MRI) magnets by GE Medical Systems, and the magnets performance is discussed.         Some more experimental results on fine filamentary NbTi wires with Cu matrices alloyed with Mn, and Mn-Si    He Liu and E. Gregory Summary: In order to produce fine (1-10 /spl mu/m) NbTi multifilamentary superconducting strands, i.e. conductors used in AC applications, Cu alloys containing Mn and MnSi are used as interfilamentary matrix materials. Hardness of these alloys as a function of strain, filamentary spacing at which proximity coupling occurs, critical current density and filament-matrix interface reaction, have been studied. The information obtained will be useful in the determination of the design of fine NbTi multifilamentary superconducting wires and the thermomechanical processes to be used in their manufacture.         Microstructural and compositional gradients in the filament-matrix region of Nb-Ti wire composites    K.J. Faase, W.H. Warnes, P.J. Lee and D.C. Larbalestier Summary: Transverse cross-sections of Nb-Ti wire composites after final /spl alpha/-Ti precipitation heat treatment (10-480hr/420/spl deg/C) were examined and analyzed in the filament-matrix region with scanning electron microscope-backscatter electron imaging (SEM-BEI) and electron micro probe analysis (EMPA). SEM-BEI micrographs were image analyzed to quantify the average effective /spl alpha/-Ti precipitate diameter, d*, and volume fraction of /spl alpha/-Ti as a function of distance into the filament. Cu concentration profiles were found in the same regions by EMPA. The compositional results show trace amounts of Cu (>0.1 at%) interdiffused up to 50 /spl mu/m into the Nb-Ti filaments. The interdiffused Cu at the interface increased /spl alpha/-Ti nucleation and thus increased /spl alpha/-Ti volume fractions by 50% relative to the nominally pure Nb-Ti at the center of the filament for short heat treatment times (30 hours of total heat treatment time).         Critical current density and n-value of NbTi wires at low field    Y. Inoue, H. Kurahashi, Y. Fukumoto and M. Shimada Summary: The manufacturing process of NbTi wires for lower field applications is optimized concerning both the number of heat treatments and the final true strain, the strain of a wire from the wire diameter at the last heat treatment to the final diameter. The sample wires were made from Nb 54wt%Ti alloy and were manufactured to vary the number of heat treatments (0, 1, 2, and 3) and the final true strain (0 to 3). One of these samples, which had one heat treatment and drew with the final true strain of 0.33, achieved J/sub c/ of 3360 A/mm/sup 2/ and n-value of 111 at 3 T. This J/sub c/ is as good as a J/sub c/ of the wires made from conventional materials and this n-value is 3 times as large as the n-value of wires mentioned above. Furthermore, the n-value at 3 T and the minimum value of the cross-sectional area of each filament show a correlation coefficient of 0.73.         Critical current limiting factors of hot isostatically pressed (HIPed) PbMo/sub 6/S/sub 8/ wires    B. Seeber, L. Erbuke, V. Schroeter, J.A.A. Perenboom and R. Grill Summary: PbMo/sub 6/S/sub 8/ wires with a molybdenum barrier and a stainless steel matrix were hot isostatically pressed (HIP) at 990/spl deg/C and 1225/spl deg/C for 4 hours at 110 MPa. The critical current density, its distribution, as well as the ac-susceptibility were investigated. The higher the applied HIP temperature, the better the critical current density becomes. A comparison of inductive T/sub c/ transitions suggests that HIPing is able to considerably reduce the width of the transition. In addition, at 1225/spl deg/C, the T/sub c/ onset is shifted from 12.4 K to 14.2 K. The high field behavior of J/sub c/ strongly depends on the effective upper critical field which is essentially determined by grain boundaries. In a degraded wire sample, a qualitative correlation between effective upper critical field and the width of the inductive transition was found. This knowledge should allow to overcome the apparent limitation of J/sub c/ at high fields (2/spl times/10/sup 8/ Am/sup -2/ and 3/spl times/10/sup 8/ Am/sup -2/ at 20 T, 4.2 K and 1.8 K, respectively).         Hot isostatic pressing of Chevrel phase bulk and hydrostatically extruded wire samples    T.C. Willis, P.D. Jablonski, D.C. Larbalestier, S. Even-Boudjada, R. Chevrel and M. Sergent Summary: In order to lower final sintering temperatures for Chevrel phase (CP) wires, we have investigated low-temperature hot isostatic pressing (HIP'ing) of both bulk and wire samples. We have fabricated (Pb,Sn)-based Chevrel phase (CP) monofilament and 61 filament wires by hydrostatic extrusion of (Cu or Cu-Ni)/(Nb or V)/CP composites, followed by cold drawing. We have investigated the CP/barrier reaction during heat treatment, finding V is unsuitable, but Nb is suitable at these lower temperatures for prereacted Pb/sub 1-x/Sn/sub x/Mo/sub 6/S/sub 8/ cores. We prepared powders of the binary Chevrel phase Mo/sub 6/S/sub 8/ by acid leaching of Li/sub x/Mo/sub 6/S/sub 8/ and Ni/sub x/Mo/sub 6/S/sub 8/. We prepared bulk samples of PbMo/sub 6/S/sub 8/ and Pb/sub 1-x/Sn/sub x/Mo/sub 6/S/sub 8/ by HIP'ing mixtures of "Pb+Mo/sub 6/S/sub 8/" powders (in situ route) or by prereacting Pb, Sn and Mo/sub 6/S/sub 8/ powders before HIP'ing (prereacted route). The in situ powders were HIP'ed under different time-temperature-pressure conditions up to 12 h/600/spl deg/C/200 MPa, producing partially consolidated PbMo/sub 6/S/sub 8/ samples. Further HIP'ing of all samples at temperatures of 700, 800 and 1000/spl deg/C, 200 MPa pressure and times of 8 and 80 hours produced additional consolidation, up to 95% of full density. As the aggressiveness (temperature and time under pressure) of the HIP process increased, the density, hardness, critical temperature, and magnetization critical current density increased.         Microstructures and properties of laser-ablated epitaxial Y-Ba-Cu-O thin films for electronic device applications    M. Yeadon, M. Aindow, F. Wellhofer, J.S. Abell, B. Avenhaus, M.J. Lancaster and P. Woodall Summary: A study of the microstructures and properties of a series of laser-ablated films of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// on [001] MgO with thicknesses of between 800 and 1900 nm is presented. Transmission electron microscopy has been used to reveal the orientation and defect microstructures of the films and it is shown that both the orientation and threading dislocation content change with deposit thickness. Measurements of surface resistance show no clear correlation with thickness whereas critical current density appears to decrease with increasing thickness. Possible relationships between the microstructures and properties are discussed.         Thin film composites of Au and YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//    L.H. Allen, E.J. Cukauskas and M.A. Fisher Summary: We are using a novel bilayer deposition process to grow composite films of Au with YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//. The composites have well-separated regions of Au and YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//, and we see no evidence for structural or chemical degradation of the grains and grain boundaries. For composite films on MgO substrates, the transport properties indicate the presence of weakened superconductivity in the films. Composites on SrTiO/sub 3/ and LaAlO/sub 3/ do not show this as strongly. The MgO composites behave like arrays of Josephson junctions and show promise as materials for flux flow devices.         Characterization of thin film composite mixtures of Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// and Y/sub 2/O/sub 3/    P.R. Broussard, V.C. Cestone and L.H. Allen Summary: In our studies of the behavior of materials forming thin film composites with Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO), we have characterized thin film composite mixtures of YBCO and Y/sub 2/O/sub 3/ (yttria) grown onto (100) MgO and (100) SrTiO/sub 3/ substrates by off-axis sputtering. We have examined the transport properties of the films, in particular the critical current density, J/sub c/. The temperature dependence of J/sub c/ for composites on SrTiO/sub 3/ is identical to that of our pure YBCO films, while for composites on MgO the J/sub c/ is similar to measurements on our earlier composites of YBCO and Y/sub 2/Ba/sub 1/Cu/sub 1/O/sub 5/ ("211"). The field dependence of J/sub c/ for the YBCO/yttria composites is different from our pure YBCO films, and from our earlier composites, but the magnitude of the flux pinning is similar.         YBa/sub 2/Cu/sub 3/O/sub 7-x/ 45/spl deg/ [001] tilt grain boundaries induced by controlled low-energy sputtering of MgO substrates: transport properties and atomic-scale structure    B.V. Vuchic, K.L. Merkle, J.W. Funkhouser, D.B. Buchholz, K.A. Dean, R.P.H. Chang and L.D. Marks Summary: Grain boundaries can act as weak links in the high T/sub c/ materials. If properly controlled, these grain boundaries can be used in various device applications. We have been able to reproducibly form 45/spl deg/ [001] tilt grain boundary junctions in YBa/sub 2/Cu/sub 3/O/sub 7-x/ thin films. The films were grown-on MgO substrates using a pre-growth substrate treatment. A low energy broad beam argon ion source was used to irradiate a select region of (100) MgO substrates. The film on the milled portion of the substrate grows predominantly with a grain orientation rotated 45 degrees about the c-axis with respect to the grain on the unmilled portion. Backscattered electron Kikuchi patterns have been used to confirm that the rotation occurs across the entire milled portion of the substrate. Transport properties of these films are discussed and related to high resolution electron microstructural and microchemical analyses of the grain boundaries. This technique has potential use in device applications as a method for controlled grain boundary engineering.         Homoepitaxial growth of YBCO thin films an YBCO single crystals    M. Konishi, J.G. Wen, H. Fuke, Y. Matsunaga, K. Hayashi, A. Odagawa, Y. Enomoto, H. Sakai, Y. Yamada, S. Koyama and Y. Shiohara Summary: YBCO films were grown on [001] YBCO single crystal substrates using the off-axis RF magnetron sputtering method. The interface between the substrate and the film was observed using TEM. The crystal orientation of the film was found to be dependent on the growth temperature. C-axis oriented films with smooth interfaces and holes on their surfaces were obtained at 760/spl deg/C. A-axis oriented films grown at 580/spl deg/C had smooth surfaces, but the interface was rather poor. Lattice mismatches occurred at the interface due to deoxidization and oxidization of the substrate during the film growth-process.         Effects of surface treatment of single-crystal MgO substrates on the growth and properties of YBa/sub 2/Cu3O/sub 7-y/ films    M. Suzuki, H. Sakurai and K. Takahashi Summary: The preferred orientation and the inplane alignment of YBa/sub 2/Cu/sub 3/O/sub 7-y/ (YBCO) thin films deposited on MgO [100] substrates by on-axis DC magnetron sputtering have been investigated. The deposition temperature highly influences the preferred orientation of films. Films were oriented with the a-axis perpendicular to the substrates for low temperature depositions and with the c-axis for high temperature depositions. In the c-axis oriented films, there exist YBCO grains with the a(or b)-axis parallel to MgO [100] and 4-5/spl deg/ -rotated ones. 45/spl deg/ -rotated grains exclusively grow under the conditions of higher temperatures and on the substrates treated by acid-etching. The volume ratio between both types of YBCO grains is strongly connected with critical current density, even in the c-axis oriented films.         Growth optimization and characterization of a-axis oriented Y-Ba-Cu-O thin films on [100] LaSrGaO/sub 4/ substrates    Z. Trajanovic, I. Takeuchi, P.A. Warburton, C.J. Lobb, T. Venkatesan and S. Ogale Summary: We have grown high quality a-axis oriented YBa/sub 2/Cu/sub 3/O/sub 7-x//PrBa/sub 2/Cu/sub 3/O/sub 7-y/ films on [100] LaSrGaO/sub 4/ substrates. We have optimized the crystalline orientation and the superconducting properties of our films. We have performed annealing studies on a- and c-axis films in vacuum and oxygen to compare the oxygen depletion of the films and found that T/sub c/ degradation of a-axis films is comparable to that of c-axis films. To further optimize the a-axis films for trilayer junction fabrication, we significantly reduced the surface roughness of the films by a gradual lowering of oxygen pressure during the deposition.         Microstructure and properties of YBa/sub 2/Cu/sub 3/O/sub 7/ thin films grown on vicinal LaAlO/sub 3/ substrates    R.R. Biggers, M.G. Norton, I. Maartense, T.L. Peterson, E.K. Moser, D. Dempsey, M.A. Capano, J. Talvacchio, J.L. Brown and J.D. Wolf Summary: Thin films of YBa/sub 2/Cu/sub 3/O/sub 7/ have been grown on vicinal LaAlO/sub 3/ substrates by pulsed-laser deposition. In most cases, the substrate surface, nominally [001], has been rotated /spl sim/6/spl deg/ about an axis parallel to the <110> direction. Films grown on these surfaces were found to have substantially improved properties compared to those obtained for films deposited on [001]-oriented substrates under equivalent conditions at our facility. The surface morphology of the films exhibited an elongated granular structure which differed markedly from the more equiaxed grain structure found in films grown on [001]-oriented substrates. Furthermore, this particular elongated morphology and improvement in properties seems to occur only for films deposited at higher laser energies (/spl sim/30J/cm/sup 2/).         Recent advances in long length Bi-2223 HTS multifilamentary composite wire development    M.J. Minot, D. Buczek, J.J. Gannon, P.K. Miles, D.R. Parker and P. Metra Summary: Developing applications for HTS technology are now enabled by a new generation of superconducting wires that bring together the required electrical and mechanical properties in long lengths that are durable when exposed to practical application environments. Advances in the development and scale-up of long-length Bi-2223 HTS composite wire are reviewed. Powder-in-tube processing was used to produce multifilamentary tapes in continuous lengths up to 1 kilometer. Electrical performance and uniformity results are reported for the wire in 300 meter and 1 kilometer lengths. Mechanical and environmental durability performance results are reported for multifilament wire tapes being developed for react-and-wind cable application as well as for wind-and-react coil and magnet applications. The use of these wires in practical demonstration applications is also reported.         Preparation and characterization of silver sheathed BSCCO-2223 tapes    B. Lehndorff, D. Busch, R. Eujen, B. Fischer, H. Piel and R. Theisejans Summary: Critical current densities of 17000 A/cm/sup 2/ were achieved in short samples of Bi-2223/Ag tapes prepared by a conventional powder in tube technique. The preparation was varied to get an optimum grain size and texture of the microstructure. Microstructural examinations and inductive measurements of the transition temperature have been performed. The critical current and current-voltage characteristics have been studied in applied magnetic field up to 8 T and at temperatures between 4.2 K and 77 K. At temperatures close to 77 K and in fields up to 1 T the critical current density is strongly field dependent and obeys a potential law. At lower temperatures a quite different behavior is observed. In addition a small pancake-coil has been built by the wind & react method and tested at 77 K.         Transport properties of long monofilamentary Bi(2223) tapes    G. Grasso, B. Hensel, A. Jeremie and R. Flukiger Summary: Long monofilamentary Bi(2223) tapes with j/sub c/ (77 K, 0 Tesla) up to 30000 A/cm/sup 2/ and lengths >1 m have been prepared by cold rolling using the powder in tube method. An optimization of the precursor powders has led to a higher phase purity after the reaction heat treatment. The deformation process has been optimized in order to increase the oxide density and to reduce sausaging effects on the oxide thickness. The transport properties of these tapes have been studied in a wide range of temperatures and magnetic fields. The critical current density values at 77 K and fields of 0.5 T and 1 T parallel to the tape surface are 10000 A/cm/sup 2/ and 5500 A/cm/sup 2/ respectively. At 4.2 K the j/sub c/ value decreases from 1.8/spl middot/10/sup 5/ A/cm/sup 2/ at 0 T to 7/spl middot/10/sup 4/ A/cm/sup 2/ at 15 T. The history dependence of j/sub c/ have also been measured. Several discrepancies have been found between the experimental data and the behavior predicted for a 'weak linked' sample. Transport properties have been studied on small sections cut from the tape in order to investigate the homogeneity of the current distribution.         Processing, microstructure and critical current density of 2223 BPSCCO/Ag tapes    K. Fischer, M. Schubert, C. Rodig, P. Verges, H.-W. Neumuller, M. Wilhelm, B. Roas and A. Jenovelis Summary: Progress has been made in the development of long 2233 phase multifilamentary wire tapes using the powder-in-tube technique. Ramless extrusion was successfully used to deform multifilamentary precursor/Ag-composites of large diameter. After extrusion and wire drawing the mean variation coefficient of filament cross sections along the wire length was determined to be about 10%. Studies of 2223 phase formation in the wire cores have shown, that the conversion of the precursor to 2223 has been accelerated by annealing under reduced O/sub 2/ pressure compared with air. Critical current densities of 12 kA/cm/sup 2/ and about 5 kA/cm/sup 2/ (77 K; 0 T) were achieved for the 19 filament wire tapes of 17 m and 100 m length, respectively. J/sub c/ of tapes of 0.12 mm thickness has been suppressed around a strain value of 0.1%.         Fabrication and characterization of HTSC Bi(Pb)SrCaCuO 2223 precursor powders, wires and tapes    V. Beilin, M. Schieber, Y. Yaroslavsky, I. Sosonkin, H. Hermon, L. Ben-Dor and J. Greenberg Summary: Two sol-gel (citrates and acetates- derived) methods for the 2223 BiSCCO precursor powders and film preparation were studied. The acceleration of diffusion processes due to intimate cation mixing and homogeneity on atomic scale provides the effective shortening of the sintering time for the 2223-phase formation. In the case of fluorine-doped Bi(Pb)SCCO, single phase 2223 sample is formed after 48 h sintering at 840/spl deg/C. The multi-core composite Ag/BiSCCO highly c-axis textured tapes and multifilament wires were fabricated by slurry casting and powder-in-tube methods, respectively.         Fabrication of Ag-sheathed Bi-superconducting tapes and coils    H.K. Liu, M. Ionescu, Y.C. Guo, R. Bhasale, Q.Y. Hu, S.X. Dou, N. Savvides, M. Apperley, G. Secrett and E.W. Collings Summary: Ag-clad (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10+z/(2223) multifilament tapes up to 46 meters have been fabricated using powder-in-tube technique. A I/sub c/ of 15 A at 77 K over the entire length has been achieved with a fluctuation along the length less than 10%. Coils up to 306 turns with a I/sub c/ of 45.6 A at 4.2 K were produced through reaction and winding procedure using multifilament tapes. J/sub c/ versus phase formation, degree of texture and grain growth of Ag-sheathed Bi-based superconducting tapes have been investigated during thermomechanical processes. The initial modest increase in J/sub c/ is attributable to the increase of 2223 phase and grain alignment, while in second stage grain growth is mainly responsible for a rapid increase of J/sub c/. Prolonged annealing in the third stage results in recrystallisation of the large grains, and hence a decrease in J/sub c/. A I/sub c/ of 8 A at 77 K and 67 A at 4 K and zero field has been achieved for Ag-clad Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+z/(2212) tape using a partial melting and atmosphere-controlled process.         Microstructure and superconducting properties of silver clad Bi-2223 tape produced by sequential pressing    S.P. Ashworth, B.A. Glowacki, M.P. James, R. Garre and S. Conti Summary: It is well known in the processing of silver clad Bi-2223 tapes that tapes whose manufacture route includes a cold pressing step have significantly higher critical current densities than tapes produced by cold rolling only. It has been widely assumed that tapes produced with uniaxial pressing are limited to lengths of a few centimetres, and are consequently of little technical value. In this paper we present data showing that by utilising "sequential pressing" (SP, pressing adjacent sections along a tape) it is possible to produce longer lengths of tape with the characteristics of pressed rather than rolled tape. Central to this novel processing technique are shaped pressing platens designed to deform under load, generating the high local pressures required for high J/sub c/'s. The data shows no significant degradation of the local J/sub c/ in the region of overlap of adjacent pressings. In the light of our results we comment on the implications of the SP process on the economics of tape production.         Cooling rate effects on the microstructure, critical current density, and T/sub c/ transition of one- and two-powder BSCCO-2223 Ag-sheathed tapes    J.A. Parrell, D.C. Larbalestier and S.E. Dorris Summary: An important variable controlling the critical current density (J/sub c/) of Ag-sheathed BSCCO-2223 tapes is the degree of phase purity of the reacted tapes. Most correlations between J/sub c/ and microstructure show that it is highly desirable to reduce the amount of non-superconducting second phases to as low a level as practical. In recent studies of the influence of cooling rate after the final reaction, we find contradictions to this general rule. The J/sub c/ (77 K, 0 T) of so-called "one-powder" tapes can be raised by as much as 50% (from /spl sim/8000 A/cm/sup 2/ to 12000 A/cm/sup 2/) by slow cooling in 7.5%O/sub 2/ at 0.05/spl deg/C/min, even though large 2212 grains are usually seen in the slowly cooled microstructure. However, the higher J/sub c/ of the slow-cooled state does correlate with a sharper T/sub c/ transition. Experiments with "two-powder" tapes have produced similar results. These apparently anomalous results emphasize the important role played by the connectivity of the polycrystalline core in determining J/sub c/.         Study of powder density, Ag:superconductor ratio, and microhardness of BSCCO-2212 Ag-sheathed wires and tapes during wire drawing and rolling    M. Karuna, J.A. Parrell and D.C. Larbalestier Summary: Densification of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ (BSCCO-2212) powder cores in Ag-clad wires and tapes has been studied as a function of strain and initial packing density. Density was measured directly by etching away the silver and weighing the remaining core. A universal feature in both wires and tapes was the attainment of maximum densities (/spl sim/80%) at intermediate strains of /spl sim/4. The linear correlation between microhardness and density found for round wires breaks down for rolled tapes, apparently because the core separates into dense locks separated by cracks.         Phase formation in Ag-sheathed (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ tapes using a one- and two-powder process with and without Ag additions    R.D. Parrella, Y.S. Sung and E.E. Hellstrom Summary: The formation of (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ ((Bi,Pb)2223) in Ag-sheathed tapes was compared for two different powder processing techniques. In one technique, a phase assemblage of (Bi,Pb)/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/ ((Bi,Pb)2212), (Ca,Sr)/sub 2/CuO/sub 3/, and CuO was produced in a single powder processed by Aerosol Spray Pyrolysis (ASP). This is called a 1-powder process. In the other technique, the same phase assemblage was produced by mixing a precursor powder composed of (Bi,Pb)2212 with a second precursor powder composed of Ca/sub 2/CuO/sub 3/ and CuO. (Both of the precursor powders were also processed by ASP.) This is called a 2-powder process. A set of tapes were made by the 1-powder process that contained 1, 5, and 10 wt.% Ag. The tape with 1 wt.% Ag yielded a microstructure of nearly phase pure (Bi,Pb)2223.         Fabrication of long length Bi-2223 superconductor tape using a continuous electrophoretic coating process    L.D. Woolf, T.L. Figueroa, R.A. Olstad, F.E. Elsner and T. Ohkawa Summary: We have developed a unique fabrication process for producing long lengths of Bi-2223 superconductor tapes. The process uses a continuous electrophoretic coating technique for sequentially depositing superconductor and silver layers on a substrate, by heat treating and rolling steps. The process offers a number of advantages over competing techniques.         Anisotropy of transport properties normal and parallel to the tape plane in Bi-2223/Ag tapes    M.P. Maley, J.H. Cho, J.Y. Coulter, J.O. Willis, L.N. Bulaevskii, L.R. Motowidlo and P. Haldar Summary: We have performed transport, resistivity and critical current measurements on Bi-2223/Ag tapes with current directions both parallel and perpendicular to the tape plane in magnetic fields up to 7 T and 50         Static electric potential measurements on the surface of Ag/Bi-2223 high temperature superconducting tapes    J.R. Cave, D.W.A. Willen, R. Nadi, D. Cameron and W. Zhu Summary: By using a fine sliding contact it is possible to measure the surface potential on a superconductor in the flux flow state as a continuous function of position. This method has been applied to the investigation of the current flow distribution in silver-clad Bi-2223 tapes at 77 K. A four point sliding contact has been constructed (gauge lengths 1-2 mm) which can slide over several cms length of a sample. The probes are arranged in a diamond or square configuration so that the local potential difference can be sampled both along and across the tape sample. Several modes of operation are possible: V-I curves can be measured at several locations along the tape and continuous traces of the transverse and longitudinal surface potential difference can be obtained for fixed values of current and applied field. Deliberately induced defects such as cracks produce characteristic correlating transverse and longitudinal potential signatures from which the local current flow direction can be deduced. Correlations between different local J/sub c/ values and microstructures are discussed.         Compressive and tensile axial strain reduced critical currents in Bi-2212 conductors    B. ten Haken, H.H.J. ten Kate and J. Tenbrink Summary: Mono and multifilamentary wires of BSCCO-2212 in Ag matrix are investigated in an axial strain experiment. The superconducting samples are soldered to a substrate that is bend in order to achieve a compressive or tensile axial strain. The I/sub c/-strain dependence is measured in magnetic fields up to 16 T at 4.2 K and the strain is varied from -2% to +1.2%. In these Bi-2122 samples any strain-induced I/sub c/ reduction is irreversible. Moreover a significant rise in I/sub c/ was never observed after changing the strain. Special attention is paid to the tensile axial strain regime (0 to 0.4%). A small but significant reduction in I/sub c/ is found in this case. The strain behaviour of these wires indicates that the I/sub c/ reduction is due to fractures in the superconducting filaments.         I-V characteristics of superconducting Ag/Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ tapes    D.U. Gubser, R.J. Soulen Jr., T. Datta and D. Kirven Summary: We have measured the current-voltage (I-V) characteristics of Ag-clad BiSrCaCuO tapes as a function of magnetic field (0-20 T) and temperature (4, 65, and 77 K). The magnetic field was applied parallel and perpendicular to the face of the tape. Samples were commercially prepared by the OPIT process. The I-V curves were analyzed by conventional means to extract J/sub c/ as a function of the applied magnetic field. Some of the curves were also fitted by an adaptation of the Ambegaokar-Halperin model from which were obtained J/sub c/ and the pinning potential. We found that, at 4 K, J/sub c/ from both sources were generally comparable with J/sub c/ /spl sim/10/sup 4/ A/cm/sup 2/ from 5 T to 20 T.         Critical current densities and voltage-current characteristics in Ag-sheathed Bi-2223 tapes    Y. Mawatari, H. Yamasaki and S. Kosaka Summary: Magnetic field and temperature dependence of the critical current density and voltage-current characteristics of Bi-2223 tapes in the magnetic field parallel to the c-axis are studied. The power-law dependence of the critical current density on the magnetic field at low fields suggests the brickwall model, and the magnetic field dependence of the macroscopic pinning force density shows clear scaling behavior at high temperatures. Furthermore, we performed the critical scaling analysis for voltage-current characteristics based on the vortex-glass-liquid transition theory.         Reactive nanophase oxide additions to melt-processed high-T/sub c/ superconductors    K.C. Goretta, B.P. Brandel, M.T. Lanagan, J.G. Hu, D.J. Miller, S. Sengupta, J.C. Parker, M.N. Ali and Nan Chen Summary: Nanophase TiO/sub 2/ and Al/sub 2/O/sub 3/ powders were synthesized by a vapor-phase process and mechanically mixed with stoichiometric YBa/sub 2/Cu/sub 3/O/sub x/ and TlBa/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ powders in 20 mole% concentrations. Pellets produced from powders with and without nanophase oxides were heated in air or O/sub 2/ above the peritectic melt temperature and then slowly cooled. At 4.2 K, the intragranular critical current density (J/sub c/) increased dramatically with the oxide additions. At 35-50 K, effects of the oxide additions were positive, but less pronounced. At 77 K, the additions decreased J/sub c/, probably because they depressed the transition temperature.         DC transport current measurements on prototype high Tc superconducting wires in pulsed magnetic fields up to 41 Telsa    C.R.J. Hole, H. Jones, J.W. Burgoyne, D. Dew-Hughes, C.R.M. Grovenor and M.J. Goringe Summary: DC transport current measurements on prototype superconducting wire artefacts have been made in pulsed magnetic fields up to 41 T. The measurements were made over 9 cm lengths of wire wound helically round a 1 cm diameter former. Both powder in tube and open tape wire have been tested and it was found that the open tape performed significantly better under the action of the pulsed field than the powder in tube material. Significant differences in determined critical currents measured by this and conventional techniques are seen. It is believed that this is the result of eddy current heating in the silver substrate since such differences are not present in samples with electrically insulating substrates.         Dissipation in BSCCO/Ag 2212 ribbons    M. Dhalle, M.N. Cuthbert, J. Thomas, G.K. Perkins, A.D. Caplin, M. Yang and M. Gorringe Summary: The low field DC irreversible magnetisation of BSCCO/Ag 2212 ribbons is shown to scale with the ribbon size. This indicates that the screening currents flow coherently throughout the sample, unhampered by the grain boundaries. At higher fields the samples 'fragment' into macroscopic islands. Within these islands no weak link behaviour is evident and dissipation is dominated by intragranular flux motion. This is demonstrated by comparing the ribbon's magnetisation loops with loops taken from the 2212 powder after it has been extracted from the ribbon. Transport measurements in magnetic fields at different angles with respect to the sample surface show how the j/sub c/(B) anisotropy is determined by the 'effective' orientational distribution of the well-connected grains, underpinning the observation of intragranular flux motion being the dominant dissipation process at higher fields.         AC magnetization measurements on hot isostatically pressed bulk PbMo/sub 6/S/sub 8/ from 4.2 Kelvin up to T/sub c/ in high magnetic fields    H.D. Ramsbottom, D.N. Zheng and D.P. Hampshire Summary: A series of variable temperature AC magnetization measurements have been completed from 4.2 K up to T/sub c/ in magnetic fields up to 10 T on bulk PbMo/sub 6/S/sub 8/ (PMS). The properties of hot isostatically pressed (HIP'ed) PMS fabricated at a pressure of 2/spl times/10/sup 8/ N.m/sup -2/ (2000 bar) are compared with those of PMS fabricated at ambient pressure. After HIP'ing the PMS, the critical current density increased by more than a factor of 20 and T/sub c/ increased by 0.5 K. Using Bean's critical state model, the magnetic measurements suggest that the HIP'ed sample has a critical current density of greater than 3/spl times/10/sup 8/ A.m/sup -2/ at 6 K, and 5 T.         The growth of Ba/sub 1-x/K/sub x/BiO/sub 3/ superconducting single crystals with the large Meissner effect    N.V. Anshukova, A.I. Golovashkin, L.I. Ivanova, O.T. Maljuchkov and A.P. Rusakov Summary: The growth of Ba/sub 1-x/K/sub x/BiO/sub 3/ single crystals with a large (50-70%) volume of superconducting phase measured by the Meissner effect is described. A narrow range of temperatures and solution concentrations exists to grow single crystals with a large volume of the Meissner state and a sharp diamagnetic transition at T/spl ap/30 K. In addition the powder synthesis of Ba/sub 1-x/K/sub x/BiO/sub 3/ polycrystals with large (/spl gsim/50%) Meissner effect is described. Some of theses experimental results contradict the traditional BCS model of superconductivity.         Re-entrant critical current behavior as a common feature of single grain boundary Josephson junctions in bicrystals of copperless oxide superconductors    I.V. Roshchin, V.N. Stepankin and A.V. Kuznetsov Summary: Critical current and electrical transport properties of single grain boundaries in bulk bicrystals of the copperless oxide superconductors BaPb/sub 1-x/Bi/sub x/O/sub 3/ and Ba/sub 1-x/K/sub x/BiO/sub 3/ were measured in order to investigate quasiparticle tunneling and Josephson properties of these materials, which hold promise for the creation of low temperature microwave electronics and cryogenic particle detectors. An unusual and remarkable feature of the temperature dependencies of critical current is the non-monotonous behavior with sharp maximum at temperatures well below the critical temperature. This anomalous low temperature re-entrant behavior appears to be a new universal feature of single grain boundaries in copperless oxide superconductors. Our studies of grain boundary transport properties in BaPb/sub 1-x/Bi/sub x/O/sub 3/ and Ba/sub 1-x/K/sub x/BiO/sub 3/ bicrystals lead us to the conclusion that re-entrant behavior of critical current originates from changes in oxygen electronic states due to heterovalent substitution in copperless materials.         Preparation of Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O thin films    J. Auge, H.G. Roskos and H. Kurz Summary: Since the discovery of the high-T/sub c/ superconductors, the main technical interest focuses on Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) and Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub 8+/spl delta// (BSCCO-2212) because of their high transition temperature and their reproducible fabrication. YBCO is mainly used today because of the relative ease of preparation. Thin BSCCO films can be deposited with nearly the right stoichiometry, but there are very few publications which report a transition temperature near the optimum value of 94 K. We report the optimization of the surface of YBCO thin films. The optimization of BSCCO-2212 films with respect to the right oxygen content is presented as well as preliminary results for Y-doped BSCCO films.         Properties of BSCCO thin films prepared by single-source MOCVD on different substrates    V.N. Fuflyigin, A.R. Kaul, S.A. Pozigun, L. Klippe and G. Wahl Summary: Films of Bi2212 were prepared on single crystalline MgO, YSZ, SrTiO/sub 3/, LaAlO/sub 3/, and NdGaO/sub 3/ substrates by MOCVD with an aerosol source. Epitaxial thin films were grown on perovskite substrates. Post-annealing under reducing conditions resulted in an increase of T/sub c/ and j/sub c/ values.         Superconducting Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ thin films prepared by post-annealing in a flow-through multiple-zone furnace    T. Pluym, R.E. Muenchausen, P.N. Arendt, X.D. Wu, F.M. Mueller, I.H. Campbell, Q.X. Jia, M.W. Hawley, E.J. Peterson, P. Tiwari and W.L. Holstein Summary: Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ thin films mere prepared first time by use of a multiple-zone flow-through thallination process. Thallous oxide was volatilized from condensed thallium oxide in a low temperature source zone and convectively transported to a higher temperature thallination zone in which initially amorphous Ba/sub 2/CaCu/sub 2/O/sub 5/ precursor films were located. By careful control of the source temperature, film temperature, flow rate, anneal time, and rates of heat up and cool down, smooth Tl/sub 2/Ba/sub 2/CaCuO/sub 8/ thin films ware prepared on [100] LaAlO/sub 3/ with the following properties: inductive T/sub c/ of 107.6 K and 80% transition width of 1.3 K, transport J/sub c/ at 75 K of 1.3/spl times/10/sup 5/ A/cm/sup 2/, and R/sub s/ at 10 GHz and 80 K of 1.3 m/spl Omega/. The scalability of the process to large area film processing was demonstrated by the preparation of Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ thin films on LaAlO/sub 3/ three-inch diameter wafers.         Growth of TlBa/sub 2/CaCu/sub 2/O/sub 7/ thin films using a controlled Tl-oxide source during processing    M.P. Siegal, N. Missert, E.L. Venturini, P.P. Newcomer, F. Dominguez and R. Dunn Summary: TlBa/sub 2/CaCu/sub 2/O/sub 7/ superconducting films 5000-6000 /spl Aring/ thick have been grown on LaAlO/sub 3/(100) substrates using oxide precursors in a two-zone thallination furnace. Smooth, nearly phase-pure 1212 films are reported, with transition temperature (T/sub c/)/spl sim/87 K, and low-magnetic field critical current densities J/sub c/(5 K)/spl sim/1/spl times/10/sup 7/ and J/sub c/(40 K)/spl sim/2-10/sup 6/ A/cm/sup 2/.         Superconducting Nd/sub 1.85/Ce/sub 0.15/CuO/sub 4-y/ thin films and heterostructures on sapphire    S.N. Mao, Jian Mao, X.X. Xi, D.H. Wu, Qi Li, S.M. Anlage, T. Venkatesan and X.D. Wu Summary: Superconducting Nd/sub 1.85/Ce/sub 0.15/CuO/sub 4-y/ (NCCO) thin films have been made on yttria-stabilized zirconia (YSZ) buffered sapphire. The films are epitaxially grown and highly in-plane oriented. X-ray diffraction shows the c-axis of the film normal to the surface of the substrate. The width of rocking curve is 0.2/spl deg/ and the RBS channeling yield is 9%, indicating high crystallinity of the film. Cross-sectional transmission electron microscopy images reveal a sharp interface between NCCO and YSZ. The microwave surface resistance of NCCO films on YSZ buffered sapphire at 9.6 GHz was measured and a value of 80 /spl mu//spl Omega/ (at 4.2 K in zero DC magnetic field) was obtained, which is comparable to Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-y/ (YBCO) films at the same reduced temperature. A trilayer structure of YBCO/SrTiO/sub 3//NCCO on YSZ buffered sapphire has been fabricated with all layers oriented, in which both the YBCO and NCCO layers are superconducting.         Ba/sub 1-x/K/sub x/BiO/sub 3/ epitaxy on various substrate materials    B. Utz, F. Wiest, W. Prusseit, P. Berberich and H. Kinder Summary: We have fabricated Ba/sub 1-x/K/sub x/BiO/sub 3/ (BKBO) films by thermal co-evaporation of the metals K, Ba and Bi. To improve the epitaxy a high temperature BaBiO/sub 3/ seed layer is deposited prior to the BKBO film which results in T/sub c/ values up to 24 K on standard substrates. As BKBO grows well on perovskites we deposited thin PrBa/sub 2/Cu/sub 3/O/sub 7/ (PBCO) layers by thermal co-evaporation on MgO, CeO/sub 2/ buffered sapphire, YSZ buffered Si and YSZ substrates. BKBO films on these systems are epitaxial and show the same T/sub c/ values as on standard substrates. Thus, by using a PBCO buffer layer technical substrates are available for BKBO thin films.         Dependence of thermal activation energy on thickness and magnetic field in (Pr/sub 0.6/Y/sub 0.4/)Ba/sub 2/Cu/sub 3/O/sub 7//YBa/sub 2/Cu/sub 3/O/sub 7//(Pr/sub 0.6/Y/sub 0.4/)Ba /sub 2/Cu/sub 3/O/sub    C. Kwon, M. Damaske, Qi Li, L. Senapati, P.A. Warburton and T. Venkatesan Summary: We have studied the activation energy of thermally activated vortex motion using (Pr/sub 0.6/Y/sub 0.4/)Ba/sub 2/Cu/sub 3/O/sub 7//YBa/sub 2/Cu/sub 3/O/sub 7//(Pr/sub 0.6/Y/sub 0.4/)Ba /sub 2/Cu/sub 3/O/sub 7/ trilayer structures. The dependence of the activation energy on the thickness of the YBa/sub 2/Cu/sub 3/O/sub 7/ layer and magnetic field was studied for YBa/sub 2/Cu/sub 3/O/sub 7/ layer thicknesses or 1.2/spl sim/120 nm and fields up to 7 T. We obtain a longitudinal vortex correlation length of 15/spl sim/20 mm in YBa/sub 2/Cu/sub 3/O/sub 7/. When the YBa/sub 2/Cu/sub 3/O/sub 7/ layer is a few unit-cells thick, the activation energy shows a logarithmic field dependence. In the thickness range between 10 to 30 nm, the dependence of the activation energy on magnetic field shows a crossover behavior from logarithmic dependence at low fields to one of power law, U/sub o//spl sim/H/sup -/spl alpha// (with /spl alpha//spl sim/0.5), at high fields. This crossover field does not depend on the thickness of the YBa/sub 2/Cu/sub 3/O/sub 7/ layer.         Experimental investigation of pinning potential shape in Bi-Sr-Ca-Cu-O films    C. Attanasio, L. Maritato, C. Coccorese, S.L. Prichepa, A.N. Lykov and M. Salvato Summary: Transport measurements of the pinning potential for microbridges of polytextured thin films of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ (BSCCO) without externally applied magnetic field have been made. Experimental data have been analysed in the framework of classical Anderson-Kim flux creep model in the case of single isolated vortex. The obtained temperature dependence of the apparent pinning potential barrier has an anomalous behavior at T<0.7 T/sub c/. Such unusual temperature dependence of U/sub app/ can be explained both in terms of pinning energies distribution and spatially nonlinear pinning potential. The results of numerical simulations strongly prove the existence of washboard-type pinning potential with a distribution of critical current densities and shape potential.         Flux creep characteristics in the presence of a pinning distribution for Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// superconducting thin films    T. Kiss, T. Nakamura, H. Takeo, K. Kuroda, Y. Matsumoto and F. Irie Summary: Nonlinear current-voltage I-V characteristics in Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films have been studied for flux creep taking into account the inhomogeneous pinning strength. By measuring the frequency dependence of the I-V characteristics, we separated the flux creep and flux flow properties. I-V curves split in the low electric-field region depending on the measurement frequency. From the frequency dependant I-V curves, we obtained the maximum creep field, at which flux creep crossed over to flux flow. By use of the Weibull function, which describes the depinning probability of flux lines in pinning sites, we determined the pinning distribution from the flow nonlinearity obtained from AC measurements. The flux creep electric-field was calculated by integrating the Arrhenius equation according to the pinning distribution. The obtained expressions agreed will with the measurement over more than six decades of electric field.         Magnetisation and flux dynamics in oxygen deficient TmBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//    G.K. Perkins, L.F. Cohen, A.D. Caplin, A.A. Zhukov, S.A. Kestlov and V. Voronkova Summary: A series of TmBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// crystals has been used to examine the influence of oxygen content on the irreversible magnetisation and the flux creep rate as a function of temperature T and applied magnetic field B. For 0.1         Transient flux dynamics in optically irradiated YBCO thin-film switches    D. Gupta, W.R. Donaldson and A.M. Kadin Summary: A high-current-density, superconducting thin film will exclude a perpendicular magnetic field, produced either by a coil or a magnet. When the film is driven into the normal state by a fast optical pulse, the screening currents decay, allowing flux to enter. The process of flux entry can be observed by measuring the induced voltage across a coil closely coupled to the film. This is equivalent to the operation of an opening switch and can be used to generate fast current pulses. This concept has been experimentally demonstrated in low and high magnetic fields, corresponding to the reversible and irreversible regimes, using 500-nm-thick YBCO films and a 1.064-/spl mu/m, 150-ps pulsed laser. Theoretical analyses of current redistribution in the film associated with the transient flux motion are compared with experimental results. Prospects for applications of this concept are discussed.         Determination of the critical state response of high T/sub c/ superconductors including demagnetization    K.L. Telschow and L.S. Koo Summary: This paper describes an integral equation approach to solving for the flux front profile in the critical state model. Both nonuniform external fields and demagnetizing geometries can be accommodated as long as cylindrical symmetry is preserved. The solution and measurement results for a tape in the field of an external coil parallel to the tape surface are presented.         Critical current density limited by the surface barrier in thin films with the magnetic field-parallel to the surface    E. Mawatari, A. Sawa and K. Yamafuji Summary: The vortex pinning due to the Bean-Livingston surface barrier in the superconducting slabs is considered within the framework of the London theory, and a simple expression of the critical current density is derived. The surface barrier is effective especially in thin films which has the thickness less than the penetration depth and high critical current density no less than those due to the bulk pinning, when an external magnetic field is applied parallel to the film surface. The resulting critical current density has the logarithmic field dependence, and is inversely proportional to the thickness of the slab. These results show good agreement with the existing observed data for NbTi films, and are applied to the data for YBaCuO films.         Third harmonic AC susceptibility in superconducting powder    E.S. Otabe, T. Matsushita, M. Heinze, M. Baenitz and K. Luders Summary: The third harmonic AC susceptibility is theoretically investigated by numerically solving Campbell's model in which the effect of the reversible fluxoid motion is taken into account. According to the calculated result of the AC field amplitude dependence of real and imaginary parts, their peak values decrease and the peak AC field amplitude shifts to higher values when the fluxoid motion changes from irreversible to reversible. This is quite different from the prediction of Bean's critical state model in which the peak value and the peak AC magnetic field are predicted to be constant. Since the reversible phenomenon is expected to be remarkable in superconductors with small sizes, the third harmonic AC susceptibility measurement was carried out for a superconducting powder of alkali metal doped fullerene. Experimental results can be qualitatively explained by the theoretical results.         Coherent vortex motion in superconducting nanobridges based on YBaCuO thin films    M.V. Pedyash, G.J. Gerritsma, D.M.A. Blank and H. Rogalla Summary: Submicron bridges in superconducting YBaCuO thin films with typical linear dimensions of about 100 nm have been fabricated. Experimental current-voltage characteristics of these structures are in reasonable agreement with numerical simulations based on true two dimensional viscous vortex motion and indicate the effect of switching from a single path motion at low transport currents to multiple paths at higher currents. The value of the viscous drag coefficient of this vortex motion is found to be about 10/sup -9/ kg/m.sec, which is about two orders of magnitude lower than one estimated from the Bardeen-Stephen model. Critical current densities in the investigated nanobridges are up to 5.10/sup 10/ A/m/sup 2/ at T=4.2 K. The critical current as a function of the width of the bridges indicates the dominating role of edge pinning.         Transport and magnetisation measurements of Bi2223/Ag tapes and the role of granularity on critical current limitation    M.N. Cuthbert, M. Dhalle, J. Thomas, A.D. Caplin, S.X. Dou, Y.C. Guo, H.K. Liu, R. Flukiger, G. Grasso, W. Goldacker and J. Kessler Summary: An understanding of the mechanisms that limit the critical current density in the Bi2223/Ag tapes is crucial to their viability in technological and commercial applications. Careful analysis of both transport and magnetisation measurements in an applied magnetic field, taken on the same samples, allow us to explore the regions of the H-T plane where either inter- or intra- granular properties dominate.         Temperature and magnetic field dependence of critical currents in granular superconductors    G. Costabile, R. De Luca, S. Pace, A. Saggese and A.M. Testa Summary: We analyze the critical current density J/sub c/ of a two-dimensional granular superconductor by a Josephson junction network approach, taking into account shielding current effects. We show that the temperature and field dependence of J/sub c/ is not directly given by the corresponding dependences of the maximum Josephson current of a single junction. By a critical state picture we discuss the temperature and magnetic field dependence of the effective energy barrier U/sub /spl gamma// for flux motion in the array. From the knowledge of U/sub /spl gamma//, calculated in the presence of currents flowing through the junctions, the magnetic field and temperature dependence of the critical current is derived.         Flux pinning and irreversibility lines of new oxycarbonate superconductors    H. Kumakura, H. Kitaguchi, K. Togano, T. Kawashima, E. Takayama-Muromachi, S. Okayasu and Y. Kazumata Summary: We estimated critical current densities J/sub c/'s and irreversibility fields B/sub irr/'s of new oxycarbonate superconductors, (Cu/sub 0.5/C/sub 0.5/)Ba/sub 2/Ca/sub n-1/Cu/sub n/O/sub 2n+3/(n=3,4) and (Cu/sub 0.5/C/sub 0.5/)/sub 2/Ba/sub 3/Ca/sub n-1/Cu/sub n/O/sub 2n+3/(n=3,4). (Cu,C)-based oxides, especially single (Cu,C)-layer oxides, showed less excellent flux pinning properties than other high-T/sub c/ oxide superconductors at low temperatures. The slopes of irreversibility lines for the single (Cu,C)-layer oxides were steeper than those of the double (Cu,C)-layer oxides. This result can be understood by the difference of the distance between CuO/sub 2/ superconducting blocks. At 77K, B/sub irr/ of the (Cu,C)-1234 was 3.8 T which was higher than that of Hg-1223 in spite of lower T/sub c/ of (Cu, C)-1234. Neutron irradiation to (Cu,C)-1234 significantly enhanced both J/sub c/ and B/sub irr/. About 6/spl times/10/sup 5/ A/cm/sup 2/ at 77 K in 1 T was obtained after the irradiation, which was one of the highest J/sub c/ ever reported for bulk superconductors.         Fabrication, processing and properties of Tl-1223 conductors    A. Goyal, M. Paranthaman, Qing He, F.A. List, E.D. Specht, D.K. Christen, D.M. Kroeger, J.E. Tkacyzk and P. Haldar Summary: Fabrication of Tl-1223 conductors in two geometries is reported. Powder-in-tube (PIT) tapes were fabricated using aerosol generated precursor powders mixed with Tl/sub 2/O/sub 3/. Effect of processing variables such as temperature, time and uniaxial pressure were studied. Under optimum processing conditions the tapes have sharp transitions (widths /spl sim/1 K) and zero-field J/sub c//spl sim/0.9/spl times/10/sup 4/ A/cm/sup 2/ at 77 K, However the tapes lack any detectable grain orientation texture and are severely weak-linked. On the other hand, thick films (3-30 /spl mu/m) of Tl-1223 on Ag made using a variety of precursor deposition techniques followed by thallination in a two-zone flow reactor, show significantly reduced weak-link behavior and high zero-field J/sub c/'s (>10/sup 4/ A/cm/sup 2/). It is found that these films are c-axis aligned (rocking curve FWHM/spl sim/3-11/spl deg/) and also possess varying degrees of local in-plane texture. Microstructural development in these thick films is found to be similar to that observed previously for films on polycrystalline YSZ. Such thick films present a working model of a practical Tl-1223 conductor.         Melt cast processed (MCP)-BSCCO 2212 tubes for power applications up to 10 kA    J. Bock, S. Elschner and P. Herrmann Summary: The Melt Cast process (MCP) is highly flexible to manufacture BSCCO 2212 bulk parts in a large variety of shapes and dimensions. MCP also allows the integration of current contacts during the fabrication process thus leading to HTS parts which can directly be integrated into electrotechnical devices, The ease of mechanical treatment of the material by machining methods offers additional options for the MCP bulk parts. Critical current densities of 2.5-4 kA/cm/sup 2/ are obtained in selffield, about 1 kA/cm/sup 2/ are measured in full rods. High DC (6.4 kA) and AC (10 kA) transport currents are obtained in large tubes (O 70 mm, L 200 mm) at 77 K. Different prototypes and a first application, each of low loss hybrid current leads, have been produced as well as functional models for current limiting and for shielding.         Spatially-resolved measurements of critical current density of superconducting films on 2 inch substrates    J.H. Claassen Summary: An apparatus is described that makes non-invasive measurements of the critical current density at an array of 32 locations across a 2 inch diameter wafer. It operates at 77 K, and can resolve variations of a few percent. Measurements of the critical temperature of a single location on the film are also possible.         Low-frequency noise and Hall effect measurements on YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films    A. Jahanzeb and Z. Celik-Butler Summary: We report 1/f noise and Hall effect measurements performed on c-axis oriented YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films at superconducting transition and in normal state. Magnetic fields up to 6 kG were applied parallel to c-axis. The voltage noise spectral density was normalized using Hall carrier density as well as atomic concentration. Close to the superconductive state, normalized voltage noise spectral density had a sharp rise. The noise did not seem to originate from local thermal fluctuations. We interpreted the data in terms of the classic percolation model near superconductive transition, according to which normalized noise is proportional to R/sup -k'/s/, where R is the macroscopic sample resistance and k' and s are critical exponents. The ratio k'/s, which can be regarded as an index of the rise of normalized noise, steadily increased with higher magnetic field. The zero-Gauss value of k'/s was calculated as 1.06; a result that agrees with the prediction of the classical percolation theory for a 2-D network.         AC susceptibility investigation of YBa/sub 2/Cu/sub 3/O/sub 7/ thin films    W. Xing, B. Heinrich, Hu Zhou, A.A. Fife and R.A. Cragg Summary: Temperature dependence of ac susceptibilities, /spl chi/=/spl chi/'-i/spl chi/", were studied on YBa/sub 2/Cu/sub 3/O/sub 7/ thin films as a function of ac frequency and driving field. The data were compared with theoretical calculations. Critical current densities were estimated by using the peak positions of /spl chi/". The critical current densities were found in good agreement with those obtained by the screening and the scanning Hall-probe techniques. The thermally activated flux creep model describes well the observed frequency dependent /spl chi/" peak temperature.         A laser-magnetic tomography for HTSC film    Yu.N. Nozdrin, P.P. Visheslavtzev, I.D. Tokman and I.M. Gordion Summary: The experimental results of the film parameter evaluation based on recording detective coil signal produced by the film in external or remanent magnetic field subject to a laser pulse at any specific spot in the film are presented. The mechanisms of the film response to the laser irradiation based on Bean-like model for the inhomogeneous superconductive film are discussed.         Microwave absorption of YBa/sub 2/Cu/sub 3/O/sub 7/ thin films with columnar defects    S.E. Lofland, M.X. Huang, S.M. Bhagat, M. Rajeswari, T. Venkatesan, D. Kanjilal, L. Senapati and G.K. Mehta Summary: We have measured the microwave magnetoabsorption of both pristine and irradiated c-axis-oriented YBa/sub 2/Cu/sub 3/O/sub 7/ thin films. The irradiation was done using 270-MeV Ag ions and produces columnar defects along the film normal. The angular dependence of the absorption for pristine films can be described by sin/spl theta/; where /spl theta/ is the inclination of the field from the film plane. However, there is a minimum in the magnetoabsorption of the irradiated films when the applied field is parallel to the columns. This minimum is indicative of vortex localization as predicted by Nelson and Vinokur. We believe that this is the first high-frequency measurement of this phenomenon.         Inductive measurements of /spl lambda/(T) of bare YBCO films and the proximity effect in YBCO/normal metal bilayers    C.W. Schneider, R.E. Somekh, J.E. Evetts, D.J.C. Walker, I.M. Watson, F. Baudenbacher, S.N. Mao, X.X. Xi, Q. Li, Chuhee Kwon, T. Venkatesan, R.G. Humphreys, N.G. Chew, R. Gross and A. Beck Summary: Inductive measurements were performed on YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) films and superconducting/normal metal bilayers using Au, PrBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// and (Y/sub 0.4/Pr/sub 0.6/)Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// as normal material in order to investigate their screening properties between T/sub c/ and 2.2 K. YBCO films were prepared using high pressure dc and hollow cathode sputtering, laser ablation, MOCVD and reactive thermal coevaporation and the penetration depth, /spl lambda/, and the c-axis lattice parameter measured. Comparison of the temperature dependence of the superfluid density, n/sub s/(T), for the YBCO films showed a significant difference in the shape of n/sub s/(T) depending on the deposition method used. This could have implications for preparing stable passive microwave devices. We have also demonstrate that SN-bilayers, using YBCO as the superconductor, exhibit an enhanced screening over the entire temperature range compared with bare YBCO films.         Self-heating hotspot effects in HTS thin films    T.L. Peterson, I. Maartense and R.R. Biggers Summary: The current-voltage (I-V) characteristics associated with self-heating hotspots in HTS thin films patterned into several different geometries have been investigated under both current-biased and voltage-biased conditions. The hysteretic behavior of the I-V characteristics as a function of sample temperature are in agreement with behavior predicted by resistive hotspot models for superconducting bridges. Additionally, the effect of magnetic fields on the current required to generate, as well as maintain, a normal hotspot has been investigated. Finally, the characteristics of voltage pulses resulting from a step increase in current have been examined to study the propagation of hot spots in HTS films.         Critical current dependence on line width and long term stability of epitaxial YBa/sub 2/Cu/sub 3/O/sub 7-x/ thin film lines    R. Hahn, G. Fotheringham and J. Klockau Summary: We have investigated the line width dependence of the critical current density of epitaxial, ion beam etched YBCO lines of 1...20 /spl mu/m width and 10 /spl mu/m...10 cm length. The long term stability of superconducting parameters was studied over a period of several months. YBCO films with J/sub c/>1*10/sup 7/ A/cm/sup 2/ at 77 K can be fabricated using a variety of existing technologies. An increase of the critical current density of up to 40% has been observed if the line width decreases from w=20 /spl mu/m to w=1 /spl mu/m which corresponds to the width dependence of the current density distribution as is shown by FEM simulations. The J/sub c/ increase of narrower lines can be compromised by the degradation of the conductor edges. Based on values of the penetration depth obtained from phase velocity measurements, the simulation was used to extract values of the intrinsic critical current density and of the width of the degraded zone by fitting the J/sub c/(w) curves. Our measurements suggest the increase of the effective penetration depth of degraded lines. At present lines of width >=5 /spl mu/m can be fabricated which maintain at 77 K critical currents of about 5*10/sup 6/ A/cm/sup 2/. Over tens of centimeters line length. Degradation of the superconducting properties occurs during storage. It is accompanied by the disappearance of the J/sub c/ increase of narrower lines. Degradation is pronounced at narrow and long lines which points to defect and edge related oxygen.         Controlled reduction of critical current densities in YBCO thin films    J.E. Nunez-Regueiro and A.M. Kadin Summary: The reduction of critical currents in HTS films has proven to be of primary importance for the fabrication of devices sensitive to small applied magnetic fields (<100 Gauss). In this work, we report on a process we have developed for the controlled reduction of critical current densities (J/sub c/'s) on thin films of YBCO. By diffusing SiO in photolithographically defined microbridges of YBCO, we have been able to obtain a reduction of up to three orders of magnitude of the J/sub c/'s of our samples in a reproducible way, without significantly lowering their transition temperatures. The microbridges treated in this way show an increased sensitivity to externally applied magnetic fields. This indicates that our method for reducing the J/sub c/'s of HTS films is a good candidate for the fabrication of flux flow devices. Preliminary experimental results on flux flow devices are discussed.         Deep-submicron structures in YBCO: fabrication and measurements    A.J.M. van der Harg, E. van der Drift and P. Hadley Summary: We present a fabrication method that consistently produces superconducting structures with lateral dimensions down to 100 nm. The etching is done in a Distributed Electron Cyclotron (ECR-) etcher using a plasma of argon and oxygen. The sample is water cooled. Degradation of the etched structures is very limited. We discuss electrical measurements on long, narrow lines and constrictions.         Studies on superplastically deformed 123/Ag composites    A. Goyal, Z.L. Wang, Y.R. Sun, D.M. Kroeger, J.R. Thompson, Y.T. Chou, J. Yun and M.P. Harmer Summary: Composites containing 25 vol% Ag were compressed at room temperature to over 110% at 850/spl deg/C in air. Measurement of the strain rate sensitivity yielded a value of 0.5, characteristic of superplastic deformation. As deformed materials had sub-micron grain size and significant c-axis texture parallel to the pressing direction. TEM examination showed that the grains were highly defected and that the grain boundaries were clean. The T/sub c/ was however low with an onset of 50 K and a width of /spl sim/10 K. Annealing studies were carried out with an aim to "fully oxygenate" the material and anneal out a minimal number of defects to obtain higher transition temperatures, at the same time retaining a significant defect density for enhanced flux-pinning. Magnetization measurements were performed after most anneals in order to evaluate intragranular and intergranular properties. Results indicate the presence of unusually high J/sub c/'s at low temperatures after the final anneal (T/sub c/ onset /spl sim/90/spl deg/K). The observations may be explained by highly superior intragranular properties coupled with increased local current loop size.         Structure and superconducting parameters of composites YBaCuO-Ag prepared by static, dynamic and hot pressing    V.I. Dotsenko, I.S. Braude, L.G. Ivanchenko, I.F. Kislyak and A.D. Puzanova Summary: To investigate effect of a technological scheme on the structure and superconducting parameters of powder composites YBaCuO-Ag, three types of pressing of powder mixtures were used, i.e. static, hot, and dynamic pressing. Silver content changed in the range c=0-50 vol.%. Orthorhombicity degree, b/a, of the YBaCuO-ceramics proved to be practically independent on c up to c=30 vol.% for static and hot pressing, and it decreased appreciably even at small c values in the case of dynamically pressed samples. Critical temperature T/sub c/ and transport critical current density j/sub c/ show similar behaviour with maximum about c=10 vol.% for static and hot pressing. Dynamic pressing results in significant deterioration of these parameters.         Niobium induced metal-superconductor to metal-insulator transition in the YBCO system    O.K. Semchinova, I.V. Grekchov, L.A. Delimova and I.A. Linijchuck Summary: In this work a novel high-T/sub c/ compound of the form YBa/sub 2/Cu/sub 3(1-x)/Nb/sub x/O/sub 7/ as been synthesized and investigated for a broad range of Nb contents O0.21 corresponding to a no-superconducting state, the conduction mechanism is adequately described through the variable-range-hopping (VRH) model. Comparison of experimental data with theory provides an estimation of both, carrier localization length and density of states at the Fermi energy.         Textured joints for conductors and complex shaped components using the composite reaction texturing method    B. Soylu, N. Adamopoulos, M. Chen, D.R. Watson, B.A. Glowacki and J.E. Evetts Summary: A new technique for forming textured high critical current joints between superconducting ceramic artefacts is presented. The method uses composite reaction texturing (CRT). For the Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub x/ (Bi-2212) system, a Bi-2212 preform is seeded with specifically aligned MgO whiskers which determine the texture in the joint region during a subsequent reaction treatment that involves partial melting. The technique can be used to join green or previously reacted components and if binders are used polymer joining techniques can be exploited. Samples retain their shape for repeated partial melting. Although it is also possible to join previously reacted components by use of a lower melting point Bi-2212 compound (e.g. Li doped). The quality of joints was assessed by transport measurements on joined bars and magnetisation measurements on cylinders formed from polymer processed sheet. It was found that the joint region carried as large a critical current as non-joint sections. For the rare earth system, RBa/sub 2/Cu/sub 3/O/sub x/ (R-123), a variation of the above technique can be used to form joints.         Texture and critical current anisotropy in composite reaction textured MgO whisker/Bi-2212 multilayer structures    M. Chen, D. Glowacka, B. Soylu, D.R. Watson, J.K.S. Christiansen, R.P. Baranowski, B.A. Glowacki and J.E. Evetts Summary: Highly textured bulk Bi-2212/MgO whisker superconducting composites have been synthesised by four processing techniques followed by a partial melting treatment termed composite reaction texturing (CRT) and post-annealing. Composites with different characteristic whisker alignment resulted in different types of textured microstructure which enabled detailed study of the critical current density, J/sub c/, as a function of texture. Highest J/sub c/ values were achieved in samples with 10 wt% MgO whiskers aligned in a planar 2D arrangement, which led to string c-axis texture. High J/sub c/ anisotropy along different sample directions and for different field directions was observed in the highly textured samples, a similarity to the behaviour of Bi-2212 single crystals was seen in the most highly textured materials. The J/sub c/ of the c-axis textured samples was self-field limited and could reach 3200 A/cm/sup 2/ at 77 K and 4 mT. Magnetisation measurements indicated a J/sub c/ in excess of 5.10/sup 4/ A/cm/sup 2/ at 5 K and 12 T.         Thermal conductivity and contact conductance of BSCCO-2212 material    Suntao Yang, Binjiang Chen, E.E. Hellstrom, E. Stiers and J.M. Pfotenhauer Summary: Thermal conductivity of bulk high temperature superconducting materials is a very important property in the current lead applications because it determines the heat load of the lead at the low temperature end. The thermal conductivity of BSCCO-2212 superconducting material has been measured between 10 and 130 K. Our results compare favorably with other published results. The thermal contact conductance between a joint of BSCCO-2212 and copper has also been measured. Our results indicate that although this kind of joint provides a relatively poor thermal interface, the electrical resistance is small. This joint is still a good choice for making a easy joint which requires both thermal and electrical interfacing.         High-temperature ultrasonic characterization of Ag-clad superconductor tapes    M.T. Lanagan, D.S. Kupperman, G.A. Yaconi, S.H. Kilgore and A. Saigal Summary: An ultrasonic nondestructive evaluation technique was developed to monitor liquid-phase evolution during heat treatment of high-T/sub c/ superconductors. The liquid phase is essential for microstructural and phase development of superconductors and is important in fabricating conductors with high critical current density, J/sub c/. Tapes were fabricated by a powder-in-tube process and then placed in a controlled-atmosphere furnace. During heat treatment, a magnetostrictive transducer launches a 140-kHz wave into the sample, and the relative change in acoustic velocity is then measured. A significant decrease in velocity was seen at the incongruent melting temperatures of Bi-based superconductors. In addition, Ag-clad tapes with Al/sub 2/O/sub 3/ and NaCl cores were used to validate the measurement technique. Advantages of this approach over other thermal analysis methods include in-situ analysis of final tape form, monitoring of isothermal liquid evolution, control of volatile species such as Tl and Pb.         Effect of MgO particles on microstructural development and superconducting properties of Bi-2223 phase    Jaimoo Yoo, Jae-Woong Ko, Jian Sha, Hai-Doo Kim and Hyungsik Chung Summary: The effect of an inert second phase on microstructural development and superconducting properties has been studied in order to improve the J/sub c/ value under magnetic field. 100 /spl Aring/ MgO particles were homogeneously mixed with the Bi-2223 phase using planetary ball milling and ultrasonification. The reaction sequence has been traced using X-ray diffraction technique and microstructural development has been studied using SEM and EPMA. Homogeneous distribution MgO grains in Bi-2223 phase led to the increase in J/sub c/ under magnetic field possibly due to the introduction of flux pinning sites.         Influence of the mould temperature on the properties of melt-cast Bi-Sr-Ca-Cu-O precursors    J. Bhakta, I.R. Harris and J.S. Abell Summary: The melt casting route has been shown to be a promising synthesis technique for the fabrication of bulk Bi-Sr-Ca-Cu-O superconductor. Precursors produced via this technique may be converted into superconducting material through conventional radiative heating or, as has been shown, through direct electrical resistance heating. For processing via the latter technique, a precursor with homogeneous electrical properties is preferred. In this paper melt cast precursor rods of composition Bi/sub 1.6/Pb/sub 0.4/Sr/sub 2/Ca/sub 3/Cu/sub 4/O/sub y/ have been prepared through casting a melt into a preheated copper mould and the influence of the temperature to which the mould was preheated on the electrical resistance and homogeneity of the precursor was studied.         Effects of Ag addition in Bi-2223 bulk using current leads    T. Honjo, S. Miyake and T. Kasegawa Summary: To apply a high-Tc superconductor for a current lead, improvements of critical current density(Jc) and contact resistance(Rc) are very important. We have been studying the effect of Ag addition on Bi-2223 bulk fabricated by the cold isostatic pressing and sintering process. Addition of 5 wt.%, Ag resulted in an increase in Jc value from 500 to 800 A/cm/sup 2/ and in a decrease in Rc value from 10/sup -6/ to 10/sup -7/ /spl Omega/cm/sup 2/ at 77 K, 0 T. These improvements were due to both an increase in size of Bi-2223 grains and increased density of the sintered bulk. We also measured the integral of heat conduction between 77 K and 4.2 K. The integral of heat conduction in a 5 wt.% Ag added specimen was estimated to be 80 W/m on an equality with that of a specimen without Ag. These results indicate that Ag addition did not affect the thermal conductivity since the Ag particles dispersed homogeneously in the sintered Bi-2223 hulk. Furthermore, as a result of improvement in the process, we obtained a maximum Jc value of 2500 A/cm/sup 2/ and Ic value of 1150 A at 77 K, 0 T in a 5 wt.% Ag added pipe-shaped specimen.         Formation of anisotropic Tl-1212, Tl-2212, Tl-1223 and Tl-2223 particles using aerosol flow reacted powders    M. Paranthaman, A. Goyal, D.E. Heatherly and D.M. Kroeger Summary: Highly anisotropic particles of Tl-1212, Tl-2212, Tl-1223 and T1-2223 superconductors were grown. The Tl-free precursor powders with the compositions Ba/sub 1/Ca/sub 2/Cu/sub 3/Ag/sub 0.37/O/sub 6/ and Ba/sub 2/Ca/sub 2/Cu/sub 3/Ag/sub 0.37/O/sub 7/ were prepared using an aerosol flow reactor. These precursor powders were then post-annealed in 0.1 atm oxygen at 700/spl deg/C for 4 h to reduce the carbon present and mixed with Tl/sub 2/O/sub 3/ (typical composition of Tl/sub x/; x=0.6-1.0). The Tl-containing powders were heated, in sealed gold tubes between 650-890/spl deg/C for various times. X-ray diffraction showed that the Tl-2212 and Tl-2223 phases were stable over a wide range of temperatures. Scanning electron microscopy showed evidence for the presence of high aspect-ratio particles. These highly anisotropic particles may of interest for the preparation of powder-in-tube and other powder deposited conductors, for current leads, and for grain alignment studies.         Effects of oxygen partial pressure and mechanical deformation on (Tl,Pb)(Ba,Sr)/sub 2/Ca/sub 2/Cu/sub 3/O/sub y/ Ag-sheathed tapes    K.V. Salazar, E.J. Peterson, T.G. Holesinger, B. Bingham, J.Y. Coulter, R.J. Sebring, J.A. Voigt, E.P. Roth and P. Haldar Summary: The powder in tube method was used to produce silver sheathed tapes of Tl/sub 0.78/Pb/sub 0.5/Ba/sub 0.4/Sr/sub 1.6/Ca/sub 2/Cu/sub 3/O/sub y/. A precursor powder of Pb/sub 0.5/Ba/sub 0.4/Sr/sub 1.6/Ca/sub 2/Ca/sub 3/O/sub y/ (prepared via the hydroxycarbonate coprecipitation of the metal ions from a stoichiometric nitrate solution) was thallinated and packed into a silver tube and processed into tape. The tape was then heated (in 100% oxygen or air) from 840/spl deg/C by 870/spl deg/C for various anneal times. The effects of different intermediate pressing stresses during tape processing had dramatic effects on both the current-carrying capacity and the tape microstructure. Variation of pO/sub 2/ also led to differences in current-carrying capacity I/sub c/ as did a roll substituted for a press during tape processing.         Synthesis and properties of thallium based superconducting wire and tape    S.K. Wivell, S. Fox, J.C. Moore and C.R.M. Grovenor Summary: We are investigating the potential for wire fabrication in the one-layer thallium superconducting systems by comparing the properties of wires and tapes prepared with the Tl-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O phases doped with a variety of elements; in particular the (Tl/Pb)-(Sr/Ba)-Ca-Cu-O and (Tl/Bi)-(Sr/Ba)-Ca-Cu-O phases. The purpose of this investigation is to identify the one layer thallium phase which is most appropriate for the fabrication of demonstrator magnet operating at 77 K. This paper will report on the combination of drawing and rolling operations which produces the best core uniformity, and the heat treatment processes that give the most reliable high J/sub c/ values. Short length J/sub c/ values as high as 9 kA cm/sup -2/ have been achieved, and some progress made in the fabrication and testing of longer lengths.         BCS-like gap structure of HgBa/sub 2/CuO/sub 4+/spl delta// tunnel junctions    Jun Chen, J.F. Zasadzinski, K.E. Gray, J.L. Wagner, D.G. Hinks, K. Kouznetsov and L. Coffey Summary: We report point-contact tunneling into polycrystalline HgBa/sub 2/CuO/sub 4+/spl delta// superconductors with a T/sub c/ onset of 97 K using a superconducting Nb counterelectrode. These SIS' tunnel junctions are of unusually high quality for cuprate superconductors, exhibiting low and flat sub-gap conductances and sharp conductance peaks as expected from a BCS density of states. These features are obtained reproducibly and are consistent with earlier published SIN results using a Au counterelectrode. Use of experimental data to simulate performance of a quasiparticle mixer indicates HgBa/sub 2/CuO/sub 4+/spl delta// may be suitable for use in low noise heterodyne receivers operating at a few THz.         Bulk processing of HgBaCuO high T/sub c/ superconductors by a two-zone technique    C. Wolters, K.M. Amm, Y.R. Sun and J. Schwartz Summary: Hg1201 superconductors have been synthesized from Ba-Cu-O precursors in a two zone assembly. Critical temperatures of 92 K as prepared and 95 K after oxygen annealing resulted. The Hg1201 phase forms at mercury pressures above 6 bar (800/spl deg/C) and at temperatures between 750/spl deg/C and 850/spl deg/C. The effect of dopants on melting and annealing temperatures of the precursor materials has also been studied. After Li doping of up to 20%, melting peaks shift to lower temperatures and broaden significantly.         Superconducting YBaCuO thin films on silicon with barium silicate buffer layers    I.V. Belousov, A.I. Ruban, V.V. Il'Chenko, G.V. Kuznetsov and V.I. Strikha Summary: The diffusion barrier capabilities of thin layers of barium silicate, which are determined by the interaction between the YBaCuO compound and Si substrate, have been investigated. Analysis of the films' elemental depth distributions show that their interaction with the substrates result in the formation of a Ba/sub 2/SiO/sub 4/ layer. The superconducting characteristic of YBaCuO films obtained on barium silicate, in terms of transition width and T/sub c0/, are significantly improved compared to those without buffering.         In-situ optical diagnosis during pulsed laser deposition of high-T/sub c/ superconductor thin films    Q. Li, S. Liu, D.B. Fenner, J. Luo, W.D. Hamblen and J. Haigis Summary: A new concept to achieve real-time optical diagnosis during pulsed laser deposition (PLD) of multilayered high temperature superconductor (HTS) thin films was developed. We have constructed a prototype instrument, which combines ultraviolet (UV) and visible (VIS) emission spectroscopy of the substrate and thin-film structure. The UV/VIS emission spectroscopy offers a convenient tool for monitoring the excited atoms, molecules, and ions in the ablation plume, providing in-situ data related to the metal (e.g. Y:Ba:Cu) composition of the plasma. The FT-IR monitoring provides in-situ data on the growing film, including layer thickness, deposition rate, dielectric constant, substrate temperature, free-carrier concentration, carrier scattering time, and DC conductivity, all related to the film quality.         The role of magnet arrangement in synthesis of YBCO thin films by on-axis DC magnetron sputtering    Y.Z. Zhang and W.J. Yeh Summary: We have investigated various processes of DC magnetron sputtering films with on-axis geometry. The study shelved that the quality of YBCO thin films not only depended on the sputtering parameters such as gas pressure, DC voltage, and substrate temperature, but also depended on the structure of the magnetron sputtering gun. A variety of magnet configurations have been tested. We have identified several magnet arrangements with which high quality YBCO thin films could be obtained. With suitable magnet arrangements and optimal sputtering parameters, large area and high quality YBCO thin films could be fabricated with T/sub c/s about 90 K, J/sub c/s of 10/sup 6/ A/cm/sup 2/ at 77 K and zero field, and the transition width less than 1 K.         YBa/sub 2/Cu/sub 3/O/sub x/ films prepared in a partial pressure of air using pulsed laser deposition    H. Jiang, A.J. Drehman, R.J. Andrews, J.A. Horrigan and C. Vittoria Summary: YBa/sub 2/Cu/sub 3/O/sub x/ superconducting films have been deposited by laser deposition on yttrium stabilized cubic zirconia (YSZ) substrates using a partial pressure of air instead of oxygen. The T/sub c/ of these films was over 2 degrees higher than films made In the same deposition system using oxygen. The films made using air had an on-set temperature higher than 93 K and an off-set temperature around 90 K, with typical transition temperature widths less than 1 degree; while the films made using oxygen had typical on-set temperatures around 90 K and off-set temperatures around 87 K. X-ray diffraction indicated that the films were oriented with the c-axis normal to the substrate surface. The critical current densities of the films, as obtained by DC transport measurements, were found to be on the order of 10/sup 6/ A/cm/sup 2/ at 77 K and self magnetic field, and the room temperature resistivities were about 245 /spl mu//spl Omega/-cm. A unique aspect of these films was that the normal state resistivities showed nonlinear behavior with respect to temperatures. However, no secondary phase was detected by X-ray diffraction and SQUID magnetometry.         Room temperature oxidation of YBCO thin-film by /spl mu/s pulsed electrolysis in aqueous solution    M. Boutet, D. Di Gioacchino, F. Celani, A. Spallone, P. Tripodi, M. Polichetti, P. Cocciolo and N. Sparvieri Summary: In this paper the oxygen deficiency of YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) films has been decreased at room temperature by the anode oxidation in an aqueous solution of LiOH (0.3 N). The anode oxidation of the films has been performed by /spl mu/s pulsed electrolysis by means of short (1.3 /spl mu/s) and high current peak (up to 15.2 A) with a low duty cycle at 5 KHz. The very high oxygen equivalent pressure on the electrode surface allows one to increase the oxygen stoichiometry with a simple experimental set-up. The films have been characterized by the X-ray diffraction (XRD) and the temperature dependence of the dc resistivity. It appears that the pulsed electrolysis allows one to enhance the critical temperature with a corresponding transition from the "semiconducting" to the "metallic" behavior of the temperature dependence of the resistivity.         Transport properties of YBCO films on ultra-thin Ag layers    C. Zhong, S.T. Ruggiero, R. Fletcher and E. Moser Summary: We discuss our results on the transport properties of YBCO thin films deposited on ultra-thin (1-11 nm) Ag underlayers. Samples were of the form: YBCO/Ag/LaAlO/sub 3/. It was seen that T/sub c/ remained relatively unaffected by the Ag underlayers, ranging from 86-89 K. Critical currents generally decreased with increasing Ag underlayer thickness, but showed an apparent significant enhancement for 8 nm of underlayer thickness. Film resistivity was found to be consistently higher for all underlayer thicknesses.         Effects of the flux creep and pinning energies on the critical current density of high quality Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub x/ epitaxial films    G.A. Alvarez, M. Koyanagi, H. Yamasaki and M. Matsuda Summary: Epitaxial Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub x/ (YBCO) films with very smooth surface morphology and excellent electrical properties (T/sub c/=92 K, J/sub c/=10/sup 7/ A/cm/sup 2/) were grown on.         Critical currents and thermal activation in a-axis oriented EuBa/sub 2/Cu/sub 3/O/sub 7/ thin films    M. Velez, J.I. Martin and J.L. Vicent Summary: a-axis oriented EuBa/sub 2/Cu/sub 3/O/sub 7//SrTiO/sub 3/(100) thin films have been grown by DC magnetron sputtering. Critical current and resistivity have been measured as a function of temperature, down to 15 K, and field, up to 9 T. In spite of the existence of 90/spl deg/ grain boundaries, the critical current is not limited by weak links. The lower part of the resistivity transition and the field dependence of the pinning force may be understood in terms of thermally activated flux creep with activation energy U(T,H)=U/sub 0/(T)/H and U/sub 0/ values of several hundreds of meV.         Transport properties of Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ meander lines    S. Fleshler, M.P. Maley, Quanxi Jia, Xindi Wu and A. Lacerda Summary: We have measured the electrical transport properties of 10 cm long Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ thin film meander lines in magnetic fields up to 18 T. The large resistance of the meander line effectively increased the electric field, or equivalently, resistivity sensitivity by two orders of magnitude. In moderate magnetic fields the critical current density is found to depend only on the component of the magnetic field normal to the ab planes owing to the highly anisotropic nature of the system. The resistivity versus temperature was measured as a function of magnetic field up to 18 T. The linear resistivity is found to vanish in a manner consistent with the occurrence of a second order phase transition. The critical exponent v(z-1) is virtually field independent with a value 5.3/spl plusmn/1 consistent with previous measurements of a three dimensional vortex glass transition in YBa/sub 2/CaCu/sub 3/O/sub 7/ and Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/. The critical regime is 10-15 K wide in agreement with values for Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/ at high magnetic field.         Design and testing of the MIDAS spaceflight instrument    S.A. Wise, R.M. Amundsen, P. Hopson Jr., J.W. High, N.M.H. Kruse, E.H. Kist and M.W. Hooker Summary: Several applications of high temperature superconductor technology have been identified for the National Aeronautics and Space Administration's (NASA) aerospace systems. However, validation of critical superconductive properties in the space environment is necessary before this technology can be inserted into satellite systems. Researchers at NASA's Langley Research Center have designed the Materials In Devices As Superconductors (MIDAS) experiment to evaluate the electrical characteristics of high temperature superconductive materials during extended spaceflight. The MIDAS experiment will evaluate four superconductive test circuits over a temperature range of 300 to 75 K. The MIDAS test circuit is produced by thick film printing and combines both superconductive and conventional electronics into a single, active microelectronics package designed to operate at cryogenic temperatures. All electrical measurements are performed directly on the test circuit, eliminating the need for intricate wiring and reducing thermal losses. This paper describes the design, fabrication, and testing of the primary subsystems of the MIDAS instrument.         Modified growth mechanism in directionally solidified YBa/sub 2/Cu/sub 3/O/sub 7/    S. Pinol, F. Sandiumenge, B. Martinez, N. Vilalta, X. Granados, V. Gomis, F. Galante, J. Fontcuberta and X. Obradors Summary: Minute amounts of CeO/sub 2/ additions have a strong effect on the solidification path, physicochemical parameters and final size distribution of Y/sub 2/BaCuO/sub 5/ (211) precipitates of directionally solidified YBa/sub 2/Cu/sub 3/O/sub 7/ (123). Inductive and transport critical currents density (J/sub c/) measurements indicate a clear increase with CeO/sub 2/ addition.         Effect of Y/sub 2/BaCuO/sub 5/ and PtO/sub 2//spl middot/H/sub 2/O additions on the microstructural development in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// superconductors    J.G. Fagan, K.D. Vuong, C.Q. Shen, J.A. Williams, T. Leone, E. Tenpas, X.W. Wang, V.R.W. Amarakoon and R.L. Snyder Summary: Results are presented concerning the formation kinetics of Y/sub 2/BaCuO/sub 5/ (211) and YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (123) phases during melt processing of melt quench (MQ) precursors and phase pure 123. The influence of Pt and 211 additions on microstructural development within YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// system are examined quantitatively via XRD analysis and DTA. Real time dynamic XRD analysis showed the phase reaction sequences for the MQ and phase pure 123 (SSC) precursor systems, and revealed the activation energy (E/sub a/) for 211 formation to be lower for MQ powders upon peritectic decomposition. The SSC precursors developed greater amounts of 211 at 1100/spl deg/C when compared to MQ precursors, (/spl sim/28 wgt% vs. 10 wgt% respectively). The addition of 0.5 m/o 211 additions in SSC resulted in lower 123 temperatures and E/sub a/ than that without 211 addition. Pt additions did alter the residual 211 content upon texturing. The presence of Pt with excess 211 additions was seen to inhibit 211 formation upon texturing.         The role of platinum in partial melt textured growth of bulk YBCO    M.R. Wegmann and J.A. Lewis Summary: Previous research has shown that vacuum filtration of particulate YBa/sub 2/Cu/sub 3/O/sub 7-x/ (Y123) suspensions in an applied magnetic field under ambient conditions, followed by partial melt processing can produce well textured Y123 thick films. In addition, the microstructural development and magnetic properties were shown to be enhanced in the presence of platinum during heat treatment. Thermal analysis revealed that platinum reduces the decomposition temperature of pure Y123 (1030/spl deg/C in O/sub 2/) by 70/spl deg/C. The current focus of this research is to further exploit this effect and develop a better understanding of the role of platinum during heat treatment. We have successfully duplicated the magnetic and microstructural enhancements observed in earlier work by adding Pt powder directly to the Y123 suspensions and heat treating the films on inert MgO substrates. The enhancement in the magnetic properties was shown to persist independent of any grain size effects resulting from improved microstructural development.         Ag doping effects on the microstructure and properties of unidirectional grown Y-Ba-Cu-O superconductors    N. Hirano and S. Nagaya Summary: The Ag doping effects on the unidirectional solidification of YBCO superconductors have been studied. The unidirectional solidification was realized by the zone melting process using an infrared radiation convergence furnace. The continuous crystals were obtained by the process. Ag distributed independently in the intergrain and grain boundary at nearly the same size. Increasing the Ag content, the a-b plane of the 123 superconducting phase aligned to the solidified direction and the (110) textured sample has been obtained by the addition of the 20 wt.%. By the addition of Ag, the I/sub c/ characteristics were improved drastically and the obtained sample (approximately 4 mm in diameter) shows a high critical current value of over 2000 A.         Melt processing for obtaining REBa/sub 2/Cu/sub 3/O/sub y/ superconductors (RE=Nd, Sm) with high T/sub c/ and large J/sub c/    S.I. Yoo, N. Sakai, T. Higuchi and M. Murakami Summary: An oxygen-controlled melt growth (OCMG) process has been employed for NdBa/sub 2/Cu/sub 3/O/sub y/ (Nd123) and SmBa/sub 2/Cu/sub 3/O/sub y/ (Sm123) superconductors for a comparative study. Both Nd123 and Sm123 samples melt-grown in reduced oxygen atmospheres exhibited an enhanced superconducting transition temperature (T/sub c/) with a sharp transition and large critical current density (J/sub c/) in a high field region at 77 K and for the applied field parallel to the c-axis of samples (H/c). For Nd123, a preferential formation of high T/sub c/ phase in a low oxygen partial pressure (P(O/sub 2/)) could be qualitatively described considering the thermodynamic stability boundaries of the Nd/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub y/ solid solutions on the LOG[P(O/sub 2/)] vs. 1/T (K/sup 9/-1) phase diagram. A long-term oxygen annealing study for an OCMG-processed Nd123 sample revealed that the annealing temperature should be as low as 300/spl deg/C.         Melt-textured YBa/sub 2/Cu/sub 3/O/sub 7/ for low-field applications in microwave devices    V.S. Bai, S.M. Bhagat and T. Rajasekharan Summary: We report the results of an investigation of microwave power loss at 10 GHz in YBCO at 77 K. The samples are melt-textured YBa/sub 2/Cu/sub 3/O/sub 7/ (123) with 28 mole % Y/sub 2/BaCuO/sub 5/ (211) inclusions and x% of Ag added to bridge the gaps at the grain boundaries. The sample with 10% Ag shows critical currents >10/sup 8/ amp/m/sup 2/ at 77 K. Measurements down to 77 K show that microwave power loss drops more sharply (through T/sub c/ of 89 K) with higher Ag content. DC magnetic-field-induced microwave absorption (MWMA) recorded at 77 K shows that in these samples the low (/spl sim/10 mT) field loss is drastically reduced with respect to that in typical YBCO ceramics.         Double sided YBCO films on 4" substrates by thermal reactive evaporation    H. Kinder, P. Berberich, B. Utz and W. Prusseit Summary: Homogenous high quality YBa/sub 2/Cu/sub 3/O/sub 7/ films on large substrates are first essentials of the commercialization of HTSC devices. We have employed thermal co-evaporation to deposit YBa/sub 2/Cu/sub 3/O/sub 7/ films up to 4" diameter. The heater design allows intermittent metal deposition and oxidation in spatially separated zones, with the metal deposition in vacuum and the oxidation at 10/sup -2/ mbar. On all substrates from MgO, LaAlO/sub 3/, YSZ, sapphire to Si and GaAs we typically achieved T/sub c/>86 K and j/sub c/>2/spl middot/10/sup 6/. A/cm/sup 2/ over the entire area. The radiation heating allows us to turn the substrates over for double sided coating, On 2" and 3" LaAlO, and on 4" YSZ, both sides meet the above specifications even for thicknesses up to 400 nm.         Large area YBa/sub 2/Cu/sub 3/O/sub 7/ films for high power microwave applications    D.W. Face, C. Wilker, Zhi-Yuan Shen, P. Pang and R.J. Small Summary: We have developed large area YBa/sub 2/Cu/sub 3/O/sub 7/ films (/spl ges/2 inch diameter) which have low microwave surface resistance at high microwave power levels. The films are produced by off-axis sputtering using a noncontact direct radiant heating technique. Thickness and composition are uniform to within /spl plusmn/3% and T/sub c/ is uniform to within /spl plusmn/1 K across 3 inch diameter wafers. The microwave surface resistance of these films has been measured over a wide range of temperature (20 K to 80 K) and microwave power. At 20 K, the surface resistance remains below 100 /spl mu//spl Omega/ (at 10 GHz) for microwave surface current densities up to 4.6/spl times/10/sup 6/ A/cm/sup 2/. At 70 K, the surface resistance remains below 350 /spl mu//spl Omega/ (@ 10 GHz) for microwave curent densities up to 1.3/spl times/10/sup 6/ A/cm/sup 2/. High power microwave transmission lines (14 /spl mu/m produced with these films are capable of transmitting microwave power up to +25 dBm (>2.3/spl times/10/sup 6/ A/cm/sup 2/ average current density) at 70 K.         Properties of multifilamentary Nb/sub 3/Sn fiber-reinforced superconductors for high field pulsed magnets    H. Tateishi, K. Arai and K. Agatsuma Summary: We are developing Nb/sub 3/Sn fiber-reinforced superconductors (FRS) for high field pulsed magnets. Multifilamentary FRS are fabricated by sputtering niobium and bronze around 22 tungsten fibers of 20-/spl mu/m diameter. The conductors are then heat-treated in an electric furnace and are solder-filled after plating copper chemically. Critical current densities of FRS have been measured up to 14.5 T. We have investigated the effect of heat-treatment conditions, tin concentration of bronze and titanium addition into niobium. Tensile stress-strain measurement showed that FRS has excellent stress toughness.         Titanium or tantalum additions to Nb/sub 3/Sn layers from reinforcement fibers in fiber-reinforced-superconductors    K. Arai, H. Tateishi, M. Umeda and K. Agatsuma Summary: Fiber-reinforced-superconductors (FRS) of Nb/sub 3/Sn were prepared using titanium and tantalum fibers. Their superconducting characteristics were estimated by separating the effects of prestrain from them. The results have shown that the tantalum fiber functions both as a reinforcement for FRS and as a source that supplies tantalum elements to improve the high-field properties of Nb/sub 3/Sn. The characteristics were degraded inversely when a titanium fiber was used. In the case of preparing a FRS using a titanium-added niobium target, the characteristics improved. The discrepancy in global pinning force between monofilamentary FRS and multifilamentary FRS is also shown.         Investigation of the magnetization and the twist pitch effect on critical current density in Nb/sub 3/Sn wires of different designs    A. Nikulin, A. Shikov, A. Uorobjova, A. Chukin and A. Silaev Summary: The effect of the twist pitch on the current carrying capacity in magnetic fields of 1-12T on multifilamentary superconductors of different designs based on Nb/sub 3/Sn, that had been made by means of the bronze technique and have different parameters: volume fraction of Nb in bronze matrix (VFNb), number of filaments, wire and filaments diameters, presence of stabilization, has been studied. It has been stated that after twist pitch reaching 6d-9d mm, where d is the wire diameter, a considerable decrease of current carrying capacity in conductors of all the types (except for wires with low VFNb, less than 0.1) is observed. The application of twisting modes with the intermediate heat treatment that restores the twisted conductors plasticity, made it possible to eliminate the current carrying capacity degradation. Also, we present magnetization data and hysteresis losses in conductors of different designs.         Reduced filament bundle diameters for improved hysteresis loss in modified jelly roll Nb/sub 3/Sn wires    J.C. McKinnell, P.M. O'Larey and M.B. Siddall Summary: Fusion applications require moderate superconducting critical current densities with low AC loss. We have investigated the possibility of reduced hysteresis loss by reducing the filament bundle diameter. For a coupled filament bundle, this reduces the volume screened by supercurrents thus reducing the hysteresis loss. We present results which show the method is effective albeit the present goal has not yet been reached.         Powder metallurgy processed Nb/sub 3/Sn(Ta) wire for high field NMR magnets    S. Pourrahimi, J. Williams, K. Demoranville and D. Rodrigues Jr. Summary: Powder metallurgy together with a multi-tin core approach was used to fabricate industrial scale lengths of Ta alloyed Nb/sub 3/Sn wire. The wire produced high critical currents (I/sub c/) along with high critical current densities (J/sub c/) at fields up to 20 tesla and 4.2 K. The wire was produced for a program funded by Battelle Pacific Northwest. One objective of the program was to compare various commercially available wires for applications in high field NMR magnets. The 1.5 mm diameter PM wire compares well with other wires tested in the program. More than 250 m of the 1.5 mm diameter wire was used to fabricate a superconducting model coil. The coil exhibited an I/sub c/ equal to that of a short sample. The performance of the Ta doped wire examined here was lower than those of similar PM wires which were produced earlier using Ti doping. Diffusion dynamics of the tin inside the wire was studied at various stages of heat treatment and was correlated to the properties of the wire.         Grain boundary compositions, transport and flux pinning of multifilamentary Nb/sub 3/Sn wires    D. Rodrigues Jr., C.L.H. Thieme, D.G. Pinatti and S. Foner Summary: The concentrations of elements at the grain boundaries and inside the grains of the A15 phase were measured in a variety of commercial and laboratory Nb/sub 3/Sn, (Nb,Ta)/sub 3/Sn and (Nb,Ti)/sub 3/Sn multifilamentary wires. Scanning Transmission Electron Microscopy (STEM) was used to determine the concentrations with high spatial resolution. The concentrations of Sn and Cu near the grain boundaries increased rapidly from their values inside the grains, while the Nb showed the opposite behavior. Ta substitutes Nb even near the grain boundary and Ti substitutes Nb and Sn. The results are compared with the EPMA analysis. Critical current densities in background fields of 2 to 23 tesla, B/sub c2/ versus temperature and T/sub c/ were measured for each sample.         Influence of the oxygenation process in the critical currents of bulk melt textured YBa/sub 2/Cu/sub 3/O/sub 7/    B. Martinez, S. Pinol, V. Gomis, F. Sandiumenge, N. Vilalta, J. Fontcuberta and X. Obradors Summary: Bulk superconducting YBa/sub 2/Cu/sub 3/O/sub 7/-Y/sub 2/BaCuO/sub 5/ composites have been prepared through a directional solidification process allowing to obtain quasi-single crystals up to 10-12 cm in length with critical currents well above 10/sup 5/ A/cm/sup 2/ at 77 K and zero field. Low temperature oxygenation processes have been required to reach the optimal superconducting performances of the samples. For short oxygenation times, oxygen deficient bands parallel to the a-b planes have been observed while, on the other hand, an aging process has also been detected at long oxygenation times. We show that the critical currents and irreversibility lines are strongly influenced by these effects, as well as the microstructure of the samples, made evident through a careful transmission electron microscopy (TEM) investigation.         Phase transformations in melt-spun Y-Ba-Cu-O bulk superconductor    H. Wu, M.J. Kramer, K.W. Dennis and R.W. McCallum Summary: Powders of YBa/sub 2/Cu/sub 3/O/sub 7/ (Y123) and compositions around Y123 were heated by a containerless process and melt-spun in 21% oxygen atmosphere at temperatures of 1400/spl deg/C to 1650/spl deg/C. Homogeneous materials were obtained with micron and submicron crystalline phases uniformly dispersed in an amorphous matrix. For Y123, the crystalline phases are identified by XRD as BaCu/sub 2/O/sub 2/ and Y/sub 2/O/sub 3/ when the melt-spinning temperature is below 1600/spl deg/C. At 1650/spl deg/C, the crystalline phases are Y/sub 4/Ba/sub 3/O/sub 9/, BaCu/sub 2/O/sub 2/ and Y/sub 2/O/sub 3/. The phase composition of the solidified melt is directly related to the oxygen content of the melt and can be related to the equilibrium phase diagrams at lower oxygen partial pressures. Isothermal annealing in oxygen at temperatures 500/spl deg/C to 950/spl deg/C reveals that the crystallization sequence is: Y123 begins to form at 500/spl deg/C, Y123 with minor amount of Y/sub 2/BaCuO/sub 5/ at 800/spl deg/C, Y123 with very minor amount of CuO at 900/spl deg/C, and single phase Y123 at 950/spl deg/C.         Chemically prepared precursor powder for the fabrication of melt processed YBCO    Wai Lo, D.A. Cardwell, Shiang-Lung Dung and R.G. Barter Summary: YBaCuO precursor powder specifically for the fabrication of melt processed ceramic has been prepared by spray drying and subsequent calcination. The formation processes of YBa/sub 2/Cu/sub 3/O/sub 7/(-/spl delta/) and Y/sub 2/BaCuO/sub 5/ have been studied in detail using thermal analysis and powder X-ray diffractometry. The morphology, microstructure and size distribution of the particles in the calcined powder have been investigated using high resolution SEM and particle size analysis and found to contain a significant proportion of sub-micron sized particles of Y/sub 2/BaCuO/sub 5/. Melt processed samples prepared using spray dried powder have been observed to exhibit a fine distribution of 211 particles which is desirable for high J/sub c/ applications.         Melt-processing of YBa/sub 2/Cu/sub 3/O/sub x/ and Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/: influence of processing parameters on microstructure and magnetization behavior    V.R. Todt, S. Sengupta, K.E. Goretta, Yan-Ling Chen, D.J. Miller and Jiyou Guo Summary: An investigation of the flux-pinning behavior of melt-processed YBa/sub 2/Cu/sub 3/O/sub x/ and Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/ has been carried out by means of microstructural investigations and magnetization measurements. It was found that both microstructure and magnetization behavior strongly depend on the chemistry and the grain size of the starting material. The carbon content and the melting behavior of the YBa/sub 2/Cu/sub 3/O/sub x/ powders seem to play an important role in the development of microstructure and flux-pinning behavior during melt-texturing. Carbon, which is existing in different amounts in all commercially available YBa/sub 2/Cu/sub 3/O/sub x/ powders and is also easily introduced during processing, was found to have the same detrimental influence on the grain boundaries of melt-processed materials as on the grain boundaries of sintered pellets. On the other hand an increase in the flux-pinning behavior could be found when carbon was present during the melting and resolidification process. Our results indicate that the presence of carbon during the resolidification process results in the incorporation of precipitates and defects not only into the grain boundaries, but also into the bulk of YBa/sub 2/Cu/sub 3/O/sub x/ leading to an increased intragrain critical current density. Initial experiments indicate that a similar effect might also be possible for Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/.         Initial crystallization and growth in melt processing of large-domain YBa/sub 2/Cu/sub 3/O/sub x/ for magnetic levitation    Donglu Shi, W. Zhong, S.E. Dorris, V. Balachandran, U. Welp, S. Sengupta, V.R. Todt and G.W. Crabtree Summary: The crystallization temperature in YBa/sub 2/Cu/sub 3/O/sub x/ (123) during peritectic reaction has been studied by differential thermal analysis and optical microscopy. It has been found that 123 experiences partial melting near 1010/spl deg/C during heating, and that crystallization takes place at a much lower temperature upon cooling, indicating a delayed nucleation process. A series of experiments has been conducted to search for the initial crystallization temperature in the YBa/sub 2/Cu/sub 3/O/sub x/+ liquid phase field. We have found that for slow cooling (1/spl deg/C/h), grain texturing for 123 can start as low as 960/spl deg/C. Low-temperature processing has resulted in high-quality, large-domain, strongly pinned 123 specimens.         Experimental evidence for electromagnetic coupling inhomogeneity along the grain boundary plane in high angle melt-textured YBa/sub 2/Cu/sub 3/O/sub 6+x/ bicrystals    M.B. Field, A. Pashitski, A. Polyanskii, D.C. Larbalestier, A.S. Parikh and K. Salama Summary: Detailed characterization of two high angle general misorientation YBa/sub 2/Cu/sub 3/O/sub 6+x/ bicrystals produced by the melt-texture-liquid-phase-removal method shows that the boundaries contain regions of both strong and weak coupling. In one bicrystal the strongly coupled component was inferred from analysis of the magnetic-field-dependent voltage-current characteristics and confirmed with magneto-optical images of the boundary. Several sections of the second sample having macroscopically different grain boundary facets were tested after sectioning with a laser. The properties were not dependent on the grain boundary plane orientation. High-field, high-sensitivity voltage-current characteristics of the inter and intra-grain regions had qualitatively identical properties and confirmed that there was a substantial strong coupled component to the boundary. The data confirm that the melt-texture-liquid-phase-removal method of YBa/sub 2/Cu/sub 3/O/sub 6+x/ formation is beneficial to the formation of strong-coupling regions in high angle grain boundaries and that some high angle grain boundaries contain strongly coupled components.         Pulsed laser deposition of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta///BaTiO/sub 3//YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// multilayer structure on Si(100) substrates    J. Luo, Q. Li, D.B. Fenner, S. Liu, W.D. Hamblen and X.D. Wu Summary: We have studied materials issues relevant to the applications of YBCO/BTO/YBCO multilayer structures, including multilayer HTS circuits and crossovers, nonvolatile memories, and on-chip energy storage for Si solar cells. Due to the good lattice match between BTO and YBCO, epitaxial YBCO/BTO multilayer device structures are possible. We have deposited YBCO/BTO/YBCO capacitors onto YSZ buffered Si substrates by using pulsed laser deposition technique. All four oxide layers are grown in situ without breaking the vacuum, and without lowering the substrate temperature to below 600/spl deg/C. We have achieved sharp resistive transitions for both the top and the bottom YBCO layers with onset at 90 K, zero resistance at 89 K for the bottom layer and 88 K for the top layer. X-ray diffraction data indicate that all four deposited oxide layers have their c-axis perpendicular to the substrate, and have less that 10% in-plane misorientation. The BTO layer shows a dielectric constant of 210, a leakage constant of 5/spl times/10/sup -7/ A/cm/sup 2/ at 10 Volts, and a remanent polarization of 26 /spl mu/C/cm/sup 2/.         Development of materials for high temperature superconductor Josephson junctions    R.J. Houlton, D.W. Reagor, M.E. Hawley, K.N. Springer, Q.X. Jia, C.B. Mombourquette, F.H. Garzon and X.D. Wu Summary: We have conducted a systematic optimization of deposition parameters for fabrication of multilayered oxide films to be used in the development of high temperature superconducting YBa/sub 2/Cu/sub 3/O/sub 7-x/ Superconducting Normal Superconducting junctions. These films were deposited onto <100> MgO substrates by off-axis sputtering using a custom fabricated multi-gun planar magnetron system. Each layer and the various combinations of materials were optimized for: epitaxial lattice match, crystal quality, film uniformity, electrical properties, and surface microstructure. In addition to the standard procedures commonly used to sputter deposit epitaxial oxide films, a variety of unique insitu and exsitu procedures were used to produce high quality multilayer devices, including: using a film nucleation temperature lower than the final film growth temperature, establishing the optimum substrate to target relationship, and timing of the oxygen anneal. Using a lower nucleation temperature when depositing the YBa/sub 2/Cu/sub 3/O/sub 7-x/ allowed us to dramatically improve the crystallinity and orientation of the superconductor on both unprocessed and ion-milled substrates. Completed multilayer devices consistently exhibited resistively shunted Josephson junction behavior in patterned bridges and SQUIDs.         Preparation and properties of high T/sub c/ superconducting YBa/sub 2/Cu/sub 3/O/sub 7/ and ferromagnetic oxide La/sub 0.67/Ba/sub 0.33/MnO/sub 3/ multilayers    G.C. Xiong, Q. Li, H. Ju, R.L. Greene and T. Venkatesan Summary: We have prepared superconducting YBa/sub 2/Cu/sub 3/O/sub 7/ and ferromagnetic oxide La/sub 0.67/Ba/sub 0.33/MnO/sub 3/ hetero-epitaxial multilayer samples by pulsed laser deposition. X-ray diffraction and ion channeling results indicate that epitaxial growth of ferromagnetic La/sub 0.67/Ba/sub 0.33/MnO/sub 3/ films has been achieved on (100) LaAlO/sub 3/ substrates. In situ epitaxial La/sub 0.67/Ba/sub 0.33/MnO/sub 3/ thin films show giant negative magnetoresistance around 150 K and a magnetoresistance ratio, -(R/sub H/-R/sub 0/)/R/sub 0/, of more than 90%. A superconducting transition and the magnetoresistance effect were observed in YBa/sub 2/Cu/sub 3/O/sub 7//La/sub 0.67/Ba/sub 0.33/MnO/sub 3/ multilayers simultaneously. The results suggest the possibility of an interface effect, which affects the resistivity and the superconductivity of the multilayers.         Magnetic noise properties of YBCO/PBCO superlattices    M. Drouet, S.A. Foulds, U. Klein, C.M. Muirhead, J. Smithyman, F. Wellhofer and P. Woodall Summary: We have measured the magnetic flux noise of two discs of YBCO/PBCO. The specimens were grown by pulsed laser ablation, had 10 alternating layers of YBCO and PBCO but with different thicknesses of PBCO. Each specimen was characterised by X-ray diffraction and a/c susceptibility measurement. We find that the noise peaks sharply at around Tc for each sample and with a noise power which is Tc dependent. We compare the results with a single layer YBCO film grown by co-evaporation.         Superconducting and normal conducting characteristics of (Y/sub x/Pr/sub 1-x/)Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films    R. Miyazaki and Y. Okabe Summary: The ratio of Yttrium (Y) to Praseodymium (Pr) is varied in (Y/sub x/Pr/sub 1-x/)Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YPBCO) thin films to consider the relation between superconducting YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) and insulating PrBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (PBCO) thin films. The critical temperature (T/sub c/) of the superconducting YPBCO thin film is decreased by substituting more Pr in place of Y, because Pr reduces the carrier density on the CuO/sub 2/ plane in YPBCO. The electrical characteristic of the YBCO film can be explained by the weakly coupled chain model. The addition of Pr reinforces the superconducting links among the grains in the YPBCO thin film. The normal state YPBCO film-shows two types of transport systems. Behavior similar to impurity semiconductors appears at high temperatures and the variable range hopping mechanism governs their conductance at low temperatures.         Planarized patterning of Y-Ba-Cu-O thin films for multilayer technology    P.A. Nilsson, G. Brorsson, J.M. Orliaguet, E. Olsson, H. Olin, M. Gustafsson and T. Claeson Summary: Planarized layers of YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) were made by etching trenches in SrTiO/sub 3/ (STO) substrates, laser depositing a YBCO film and mechanically polishing the film down to the substrate surface. These structures exhibited critical temperatures (T/sub c/) of 88 K and a critical-current density (J/sub c/) of 10/sup 6/ A/cm/sup 2/ at 77 K. The planarized surface was smooth, with a maximum height difference between the YBCO and STO of 20 nm. The surfaces were used as templates for epitaxial growth of multilayer insulators of STO and PrBa/sub 2/Cu/sub 3/O/sub 7/ (PBCO) and top YBCO layers. Complete crossovers, free of superconducting shorts, with T/sub c/ of 86 K and critical current density (J/sub c/) of 2/spl times/10/sup 5/ A/cm/sup 2/ were made.         The sputter deposition of cerium oxide thin films for superconducting electronics    J.M. Owens, E.J. Tarte, P. Berghuis and R.E. Somekh Summary: Thin films of cerium oxide (CeO/sub 2/) have been deposited by r.f. reactive sputter deposition on yttria-stabilised zirconia (YSZ) and on YBCO thin films on lanthanum aluminate (LaAlO/sub 3/) substrates. Subsequent growth of YBa/sub 2/Cu/sub 3/O/sub (7-x/) (YBCO) by high pressure d.c. sputtering has yielded superconducting transition temperatures (T/sub c/s) of 89-91 K for unpatterned YBCO films. CeO/sub 2/ thin films have been patterned and subsequent YBCO growth has been examined. Oxygenation levels were monitored between growth and patterning stages by X-ray diffraction (XRD). A YBCO track has been fabricated crossing steps in a CeO/sub 2/ buffer layer. A critical current density (J/sub c/) of 0.8/spl times/10 /sup 10/Am/sup -2/ at 77 K as compared with 1/spl times/10 /sup 10/Am/sup -2/ for a flat YBCO track on flat CeO/sub 2/ was measured. Crossover test structures were made, having T/sub c/s of 89-91 K for top and 80-90 K for the bottom YBCO electrodes. A 400 nm thickness of CeO/sub 2/ was sufficient to insulate two superconducting layers and found to have a resistivity of 2/spl times/10/sup 7/ /spl Omega/m at 77 K.         A fully automated pulsed laser deposition system for HTS multilayer devices    J.H. Clark, G.B. Donaldson and R.M. Bowman Summary: For the fabrication and development of high-temperature superconducting (HTS) thin film devices, which often require multiple layers, it is essential to have control over all parameters during growth. Until recently the overwhelming majority of film growth was controlled manually. We have found this can often lead to error and irreproducibility. To overcome these problems we have designed and constructed an automated multitarget excimer pulsed laser deposition (PLD) system. We identify key elements of the system that can be utilised to address many of the problems currently encountered in HTS film growth. Optimisation using Robust Design techniques has also been used in the identification of principal parameters in growth of films and multilayers.         Nonlinear effects in high temperature superconductors: 3rd order intercept from harmonic generation    C. Wilker, Zhi-Yuan Shen, P. Pang, W.L. Holstein and D.W. Face Summary: The nonlinearity or microwave surface resistance of high temperature superconductors (HTS) is of considerable interest. We report the first measurement of the 3rd order intercept (TOI) from harmonic generation for HTS. The nonlinearities were measured for a series of coplanar transmission lines composed of Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ or YBa/sub 2/Cu/sub 3/O/sub 7/. At a fundamental frequency of 1.4 GHz, the TOI for a 28 /spl mu/m wide by 5 mm long Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ transmission line was: +52 dBm at 100 K; +68 dBm at 90 K; +72 dBm at 80 K; and +80 dBm at 50 K. This narrow transmission line handled up to 4 Watts of cw power at 80 K which corresponds to an average rf current density of 2.2/spl times/10/sup 6/ A/cm/sup 2/. The 3rd harmonic exhibited the expected slope 3 on a log log scale at both low and high powers and a shift of the TOI was observed at some intermediate power. The scaling rules for power handling from changes of a Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ coplanar transmission line width, length and temperature were also derived. These data suggest a redistribution of the rf current within the transmission line across its width at high powers. A pronounced TOI shift was not observed for YBa/sub 2/Cu/sub 3/O/sub 7/ coplanar transmission lines.         Microwave dissipation due to vortices in YBa/sub 2/Cu/sub 3/O/sub 7-x/ thin films for magnetic fields applied at small angles from the ab-planes    N. Anand, M.A. Itzler and M. Tinkham Summary: YBa/sub 2/Cu/sub 3/O/sub 7-x/ thin films patterned in a meander line resonant structure are used to probe vortex dynamics at microwave frequencies. We perform highly sensitive measurements of the changes in surface resistance /spl Delta/R/sub s/(H,T,/spl theta/) of YBa/sub 2/Cu/sub 3/O/sub 7-x/ thin films as a function of applied dc field, temperature, and angle of the applied field relative to the ab-planes. We observe that the component of the magnetic field normal to the planes produces substantially more dissipation than the component parallel to the planes. Also, the surface resistance R/sub s/ vs. H data for magnetic fields applied at small angles from the ab-planes shows two regions of markedly different field dependence separated by a crossover field H*. For applied fields H>H* we have linear dependence of R/sub s/ on applied field with a steep slope. For applied fields H         AFM and TEM studies on high-quality Bi-2223 thin films grown by MOCVD    K. Endo, T. Shimizu, H. Matsuhata, F.H. Teherani, S. Yoshida, H. Tokumoto, K. Kajimura, K. Nakamura and K. Fueki Summary: AFM and TEM observations of high- quality Bi-2223 thin films grown by MOCVD have been carried out to elucidate the crystal growth mechanism and the effect of surface structures on superconducting properties. AFM images of the film surfaces grown on flat planes (off-angle <0.3 deg.) of LaAlO/sub 3/, SrTiO/sub 3/ and MgO [001] substrates clearly showed a 2-dimensional nucleation growth. In contrast, those on vicinal planes (off-angle-3 deg.) of LaAlO/sub 3/, SrTiO/sub 3/ and Nd:YAlO/sub 3/ [001] substrates showed a step flow growth. The films grown on LaAlO/sub 3/, SrTiO/sub 3/ and Nd:AlO/sub 3/ showed the highest T/sub c(0/) of 97 K reported for as-grown BSCCO films. In addition, a TEM plan-view image of the film grown on [001] LaAlO/sub 3/ showed clearly the misfit dislocation network running along the orthogonal [110] directions at the heterointerface and having Burger's vectors b=1/2[110]. The clear AFM images of regularly-shaped terraces or step-edges and the distinct TEM image of the misfit dislocation network are evidence of high-quality MOCVD grown Bi-2223 films.         Cuprate trilayer c-axis tunnelling heterostructures    J.N. Eckstein, G.F. Virshup and I. Bozovic Summary: Trilayer tunneling structures consisting of cuprate electrodes and titanate barriers were grown by atomic layer-by-layer molecular beam epitaxy and processed into c-axis transport samples. Barriers of SrTiO/sub 3/ and related titanates with thicknesses ranging from 4 /spl Aring/ to 28 /spl Aring/ (one to seven unit cells of the titanate) were grown. While no supercurrent was observed for even the thinnest barrier, the zero bias resistance was an exponential function of barrier thickness for samples with five or fewer titanate unit cell barriers, indicating tunneling transport. Each additional titanate unit cell caused the zero bias resistance to increase by one order of magnitude. A detailed investigation of the properties of the cuprate layers immediately adjacent to the titanate layers revealed that they were depleted of charge carriers and exhibited variable range hopping transport. Thus the electron states in these layers were localized. The trilayer transport process is modeled as one phonon assisted tunneling between localized states.         Superconducting and normal metal multilayers of thallium-lead cuprates    K.E. Myers, D.W. Face, J. Kountz, J.P. Nestlerode and C.F. Carter Summary: We report the growth of c-axis oriented, epitaxial thin films of (Tl,Pb)Sr/sub 2/CuO/sub 5/ on (100) oriented LaAlO/sub 3/ substrates by off-axis sputter deposition in the presence of thallium oxide vapor. These films display a resistivity which crosses over from metallic to semiconducting behavior at low temperature. In addition, we have shown that multiple layers of superconducting (Tl,Pb)Sr/sub 2/Ca/sub 0.8/Y/sub 0.2/Cu/sub 2/O/sub 7/ (1212) and nonsuperconducting (Tl,Pb)Sr/sub 2/CuO/sub 5/ (1201) can be deposited sequentially without compromise of the superconducting properties of the 1212 layer. Bilayers of both 1212 on 1201 and of 1201 on 1212 have been fabricated. In either case, both materials grow with their c-axis normal to the substrate surface and with their a-axes aligned to each other and to the major axes of the substrate. Technologically interesting trilayer structures of 1212/1201/1212 have also been fabricated. Both 1212 layers are superconducting with transition temperatures of up to 94 and 93 K for the upper and lower layers respectively. We believe that this is an important step towards the development of thallium cuprate-based multilayer technology.         Fabrication and properties of DC-sputtered Tl-1223 superconducting thin films    J.Y. Juang, J.H. Horng, H.C. Lin, S.J. Wang, K.H. Wu, T.M. Uen, Y.S. Gou and C.M. Fu Summary: A multi-step deposition and post annealing scheme has been developed for preparing nearly single phase, c-axis oriented TlBa/sub 2/Ca/sub 2/Cu/sub 3/O/sub 9/ (Tl-1223) superconducting thin films by dc-sputtering. The effects of the compensates used during post annealing on final phase formation suggest the crucial role played by thermodynamic conditions and further validates the viability of the present process scheme. In particular, films obtained by the present process have shown, for the first time in this system, a critical current density (J/sub c/) above 10/sup 6/ A/cm/sup 2/ at 77 K with a zero-resistance transition temperature (T/sub c0/) above 110 K. The results are attributed to the improvement of film morphology, specifically a decreased density of weak-links.         High current densities and associated failure mechanisms in long narrow Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ lines    W.L. Holstein, C. Wilker, P.S.W. Pang, D.B. Laubacher, S.P. McKenna and D.W. Face Summary: The use of high temperature superconducting thin films in chip-to-chip interconnects requires the fabrication of long, narrow lines capable of carrying high current density on large area films. The capability of Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ thin films and patterning technology were studied for 0.65 /spl mu/m-thick films prepared on 2-and 3-inch diameter LaAlO/sub 3/ wafers. For 15, 12, and 10 /spl mu/m wide lines 1.8-2.0 m in length, critical current density J/sub c/ at 80 K in excess of 1.4 MA/cm/sup 2/ was achieved. Lines of length 70 cm and widths of 4 and 7 /spl mu/m yielded J/sub c/ at 80 K of 1.10 and 0.94 MA/cm/sup 2/ respectively. Patterning of long, continuous lines 2 /spl mu/m in width was difficult, but one such line 33.8 cm in length achieved a J/sub c/ of 1.2 MA/cm/sup 2/ at 70 K and another a J/sub c/ of 0.42 MA/cm/sup 2/ at 80 K. Line failure at high current density occurred through two mechanisms. Localized melting at high current density resulted in small localized line discontinuities. A second mechanism, postulated to be arcing, was characterized by melting and disfiguration over line lengths of up to several centimeters.         Flux pinning in NbTi/Nb multilayers    J.D. McCambridge, N.D. Rizzo, X.S. Ling, J.Q. Wang, D.E. Prober, L.R. Motowidlo and B.A. Zeitlin Summary: We made thin film multilayers of NbTi and Nb (d/sub NbTi/=20 nm and d/sub Nb//spl ap/3-9 nm). Samples were characterized by electrical transport measurements between 4.2 K and T/sub c/, in magnetic fields up to 6 T. We present J/sub c/ as a function of the device geometry and orientation of the field. For some multilayers, J/sub c/ had a large peak whose onset occurs near /spl sim/0.2 H/sub c2/. We suggest this peak effect is caused by a softening of the tilt modulus. Measured critical current densities at 4.2 K of 16 kA/mm/sup 2/ at 3 T and 8 kA/mm/sup 2/ at 5 T are among the highest achieved in the NbTi system.         Quantification of pinning center thickness in conventionally processed and powder processed artificial pinning center microstructures    P.J. Lee, D.C. Larbalestier and P.D. Jablonski Summary: The quantity, size and distribution of pinning centers are key factors in determining the J/sub c/ of Nb-Ti-based superconductors. In Artificial Pinning Center APC composites large strains must be applied between the assembly of the pinning structure and the final strand, which can result in large changes and variations in pinning center size and shape. In order to correctly interpret the properties of artificial pinning structures, we need an accurate description of their geometry. In this paper we discuss the various techniques available for quantifying near optimum size microstructures and compare the results. We also contrast the distributions found in APC style microstructures with those produced by conventional processing.         Properties of rod-based artificial pinning center Nb-Ti superconductors    R.W. Heussner, P.D. Jablonski, P.J. Lee and D.C. Larbalestier Summary: We have fabricated rod based artificial pinning center (APC) composites from rods of Nb-Ti and Nb as matrix and pinning center respectively. Critical current densities of 19000 A/mm/sup 2/ at 1 T, 12500 A/mm/sup 2/ at 2 T and 3000 A/mm/sub 2/ at 5 T were achieved in a conductor containing Nb 47 wt.% Ti with 24 vol% Nb pins. Microscopy revealed a progressive degradation of the original hexagonal pinning centers from an ordered array towards a more random ribbon-type microstructure as the composites were drawn towards their peak J/sub c/. We review the impact of this deformation on the physical properties.         Development of APC Nb-Ti composite conductors at Supercon, Inc    M.K. Rudziak, J.M. Seuntjens, C.V. Renaud, T. Wong and J. Wong Summary: Supercon has developed a unique method for the fabrication of artificial pinning center (APC) NbTi superconductors. In this process, pure niobium and titanium layers are partially diffused so as to produce a superconductor/normal structure that will provide flux pinning at final conductor size. No precipitation heat treatments are required. Process development has resulted in Conductors with filament diameters as small as 6 and as large as 90 microns. Excellent conductor ductility and J/sub c/ performance have been demonstrated. Supercon APC conductor has been utilized in solenoid, model dipole, and MRI magnets. An overview of the development program mill be presented along with a status report on conductor scale-up efforts.         Vortex solid-liquid phase transition, J/sub c/ limiting factor, and vortex pinning force in superconducting Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10//Ag tape    Qiang Li, H.J. Wiesmann, M. Suenaga, L. Motowidlo and P. Haldar Summary: We present our study of the vortex solid-liquid phase transition of superconducting Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ in the mixed state, based on our detailed transport measurements of a Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10//Ag tape (J/sub c//spl cong/2/spl times/10/sup 4/ A/cm/sup 2/ at 77 K and zero field) immersed in liquid neon (27 K) and in liquid oxygen (54 K-90 K) as a function of applied magnetic field up to 17 T. A comprehensive vortex phase diagram is obtained. We show that the vortex. Solid-liquid transition is the fundamental limiting factor for J/sub c/ in this tape at T/spl ges/27 K in magnetic field (except at very low field). In addition, the field-dependence of the flux pinning force in both solid and liquid regime is discussed.         Observation of a transverse voltage in the mixed state of YBCO thin films    T.L. Francavilla, E.J. Cukauskas, L.H. Allen and P.R. Broussard Summary: The occurrence of a transverse voltage peak has been observed in YBCO thin films. This phenomenon occurs under conditions of temperature and current in the earth's magnetic field such that the films are in the mixed state. The magnitude of the peak was found to scale with both temperature and current, and exhibited a Sin(/spl theta/) orientational dependence measured between the film-substrate and the position of the measurement electrodes on the film surface. These observations are similar to observations made in conventional superconducting thin films such as Nb, NbN, NbCN, and PbBi.         Avalanche flux dynamics in the vortex state of type-II superconductors    Donglu Shi and Zunining Wang Summary: We show that flux motion behavior in type II superconductors cab well be interpreted by the self-organized criticality theory. Based on a previous model developed by Tang, we derive various important relations for the dynamics of the vortex state including the time dependence of current density, j. We also experimentally demonstrate that flux entry at the initial stage in a zero-field -cooled relaxation experiment involves avalanches. The classical creep behavior, as treated by Anderson and Kim, is observed only in the small j regime.         Flux motion dynamics and self-organized criticality in YBCO thin films    L.K. Yu, W.J. Yeh and Y.H. Kao Summary: The analytical approximated result of the flux noise in mixed state under the current driving force is derived. The Anderson-Kim flux creep model is used to relate this noise to the current density. The numerical result is then compared with the flux noise data obtained from YBCO thin films measured with a DC SQUID. Using this method, we can estimate the free energy U/sub 0/ and the bundle size. The invariance of the noise peak position with the detecting coil distance indicates that the configurations of the moving bundles are space invariant so the system is in a self-organized criticality state.         On-axis DC sputtered YBa/sub 2/Cu/sub 3/O/sub 7/(-x) films up to 2" in diameter for microwave antenna arrays    G. Muller, B. Aschermann, H. Chaloupka, W. Diete, M. Getta, M. Hein, S. Hensen, F. Hill, M. Lenkens, S. Orbach-Werbig, T. Patzelt, H. Piel, J. Rembesa, H. Schlick, T. Unshelm and R. Wagner Summary: We have extended the planar on-axis DC sputtering process under high oxygen pressure (1-4 mbar) to the epitaxial growth of YBa/sub 2/Cu/sub 3/O/sub 7-x/ films on LaAlO/sub 3/ substrates up to 2" in diameter without scanning. The stability of the accordingly large plasma turned out to depend critically on the homogeneity of the stoichiometric target and its bonding to the water-cooled sputtering cathode. The radiation-shielded heater plate provided temperature uniformity of /spl plusmn/4K at 890/spl deg/C to the 2" substrates. The quality of the large unpatterned films was controlled by inductive as well as by new microwave test systems based on niobium choke-flange or sapphire-loaded cavities. These have been designed for highly sensitive scanning measurements of the surface resistance R/sub s/ at 87 GHz and high power microwave tests at 20 GHz, respectively. Homogeneous low R/sub s/ values have been achieved on the large films up to surface fields of 5 mT at 77 K. A frequency diplexer at 5 GHz for antenna arrays was designed with lumped elements and patterned from a 1" film by means of photolithography, ion milling and wet etching. Its measured performance agrees well with numerical simulations.         Effects of etching on the morphology and surface resistance of YBa/sub 2/Cu/sub 3/O/sub 7/(-/spl delta/) films    A. Roshko, S.E. Russek, K.A. Trott, S.C. Sanders, M.E. Johansson, J.S. Martens and D. Zhang Summary: The changes in surface morphology and surface resistance of sputtered and laser ablated YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films both before and after etching have been examined. Six different etchants were used: citric acid, nitric acid, Br-methanol, EDTA, disodium EDTA, and ion milling. The surface morphologies of the films were examined by reflection high energy electron diffraction (RHEED) and atomic force microscopy (AFM), both before and after etching. The surface resistance (R/sub s/) was measured at 94 GHz using a confocal resonator. An amorphous layer was found on the film surfaces after exposure to air. A few of the etches restored some of the surface crystallinity, but most caused increases in the overall surface roughness. Several of the wet etches attacked dislocations. Ion milling caused the largest degradation of surface crystallinity and a corresponding increase in R/sub s/. Some of the chemical etches increased R/sub s/ by less than 15%.         Microwave properties of YBCO thin films    B. Avenhaus, A. Porch, M.J. Lancaster, S. Hensen, M. Lenkens, S. Orbach-Werbig, E. Muller, U. Dahne, N. Tellmann, N. Klein, C. Dubourdieu, J.P. Senateur, O. Thomas, H. Karl, B. Stritzker, J.A. Edwards and R. Humphreys Summary: We have measured the microwave properties of high quality YBCO thin films using a copper cavity (87 GHz) and a dielectric resonator (19 GHz) for unpatterned films as well as a coplanar resonator (5, 8, 10, 15 and 16 GHz) for patterned films. For the patterned films the surface resistance (R/sub S/) and non-linear effects were studied as a function of temperature below T/sub C/. For practical applications, the assessment of non-linear effects in the surface resistance are of great importance. The best films showed R/sub S/ approximately constant up to microwave peak current densities of the order of the dc critical current density. The measurements were performed on samples fabricated by a number of different techniques.         Microwave absorption of Fe-doped YBCO films    S.E. Lofland, S.B. Ogale, M. Rajeswari, D.D. Chougule, S.M. Bhagat and T. Venkatesan Summary: Thin films of YBa/sub 2/Cu/sub 3-x/Fe/sub x/O/sub 7-y/ (0/spl les/x/spl les/0.2) were made by pulsed laser deposition using different O/sub 2/ pressures and annealing times. Their microwave absorption was measured and shows that the preparation conditions have a profound effect on the surface resistance. That is, if the Fe incorporation was successful, the microwave absorption had a large peak near T/sub c/. Various other diagnostics such as X-ray, ac susceptibility and atomic-force microscopy have also been performed.         Microwave surface resistance of nickel and zinc doped YBCO single crystals in the a-b plane    Kuan Zhang, D.A. Bonn, Ruixing Liang and W.N. Hardy Summary: The microwave surface resistance of crystals of YBa/sub 2/(Cu/sub 1-x/M/sub x/)/sub 3/O/sub 7-/spl delta//, with M being Ni or Zn, has been systematically studied at 34.8 GHz. Both Zn (x=0.0015 and 0.0031) and Ni (x=0.0075 and 0.0140) impurities were found to be capable of lowering the surface resistance, and also substantially altering its temperature dependence. The results suggest that the microwave loss of high temperature superconducting thin films might be improved by slightly doping the material with impurities.         The surface resistance of bulk polycrystalline YBa/sub 2/Cu/sub 3/O/sub 7/(-X)    B.A. Tonkin and Y.G. Proykova Summary: The surface resistance of viscous processed and powder processed bulk polycrystalline YBa/sub 2/Cu/sub 3/O/sub 7-X/ specimens have been measured as a function of frequency (27-38 GHz) and temperature (10-150 K) using an endwall replacement technique. The surface resistance of the viscous processed material within the 9-38 GHz frequency region gives a crossover frequency of 7.6 GHz. The temperature dependence of the superconducting state of material from both processing methods can be described by a two-gap BCS model which treats the sample as a network of weakly coupled superconducting grains.         Nonlinear response of suspended high temperature superconducting thin film microwave resonators    B.A. Willemsen, J.S. Derov, J.H. Silva and S. Sridhar Summary: The nonlinear microwave surface impedance, Z/sub s/(H/sub rf/) of Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7/(-/spl delta/) thin films is measured using suspended patterned resonators. We find that the nonlinear response is well described in terms of a single mechanism, namely the hysteretic ac response of the current-induced critical state.         Microwave losses of YBCO thin films in high magnetic fields    I.S. Ghosh, L.F. Cohen, V. Fry, T. Tate, A.D. Caplin, J.C. Gallop, S. Sievers, R. Somekh, S. Hensen and M. Lenkens Summary: A parallel plate resonator technique was employed to investigate changes in the microwave surface impedance between 20 K and 60 K, when d.c. magnetic fields up to 4 T were applied parallel to the YBCO film surface. By using a simple model to describe the observed behaviour, we can extract values for the vortex viscosity /spl eta/ and pinning constant /spl kappa//sub p/, as a function of temperature in three sets of films. As a result of low energy deuterium ion implantation in one of the films, the low field behaviour was degraded but at high fields the pinning properties improved quite drastically. A much smaller effect was observed in field dependence of the dc screening current as measured using vibrating sample magnetometry.         Some effects of matrix additions to internal tin processed multifilamentary Nb/sub 3/Sn superconductors    T. Pyon and E. Gregory Summary: Internal tin processed Nb/sub 3/Sn multifilamentary wires were fabricated with matrices containing either Ti or Ge. Some effects of these matrix additions on the formation rate of Nb/sub 3/Sn and on the J/sub c/'s obtained, have been determined. The effect of a 0.7 wt.% Ge addition on material with Nb 1 wt.% Ta, Nb 7.5 wt.% Ta and pure Nb filaments has been examined as has that of three different levels of Ti in the Cu matrix with the filament compositions. The tubular-tin-source (TTS) process was chosen for this work, because this process was believed to be less sensitive to the hardness of the matrix than the tin-core process. In this study, three different reaction heat treatments were carried out to explore the variation of J/sub c/ of these materials. A discussion of the results and significant effects of the addition elements is given.         Characterization of multifilamentary Nb/sub 3/Sn superconducting wires for use in the 45-T hybrid magnet    L.T. Summers, J.C. McKinnell, S.L. Bray and J.W. Ekin Summary: The National High Magnetic Field Laboratory (NHMFL), in collaboration with the Francis Bitter National Magnet Laboratory, is constructing a 45-T hybrid magnet system. Here we report the results of studies to characterize candidate Nb/sub 3/Sn superconductor for use in the superconducting outsert coils. We have determined the effects of strain and magnetic field on the critical current, measured ac losses, and measured residual resistivity ratios (RRR). Critical currents in excess of 1000 A mm/sup -2/ non-Cu have been measured in sample wires at 12 T and 4.2 K combined with a hysteresis loss of less than 500 mJ cm/sup -3/ We also present predicted 1.8 K performance, based on empirical models, and present a methodology for calculating sample holder prestrain.         Improved superconducting critical current density in modified jelly roll Nb/sub 3/Sn by the application of niobium (Nb) diffusion barriers    J.C. McKinnell, D.B. Smathers, M.B. Siddall and P.M. O'Larey Summary: One of the limiting factors of high field magnets is the overall current density available in the high field region. We report a 40% increase in the critical current density of the non-Cu of Modified Jelly Roll (MJR) Nb/sub 3/Sn wires. The increase occurs when niobium diffusion barriers are substituted for the standard vanadium diffusion barriers. The Nb/sub 3/Sn J/sub C/ is also shown to increase when vanadium is removed from the wire. The effective filament diameter of the wire increases only slightly and depends linearly on the MJR diameter. Niobium diffusion barriers are found to improve the RRR of the wire relative to vanadium diffusion barriers.         The effect of powder metallurgy Cu(Sn) APCs on grain size reduction and flux pinning in Nb/sub 3/Sn wire    C.L.H. Thieme, E. Rodrigues Jr. and S. Foner Summary: Cu artificial pinning centers (APCs) measuring 20 or 5 nm across were introduced to Nb/sub 3/Sn and Nb/sub 3/Sn(Ta) wire by means of powder metallurgy. The APCs increased the filament hardness by less than 10%. Stress anneals could be applied without affecting the Cu APC content or morphology. The Cu APCs led to a fine grained Nb/sub 3/Sn, with an average grain size of 18 nm. The critical current over the filament area was 2250-2600 A/mm/sup 2/ at 12 T, virtually similar for the 20 and 5 nm APC wires. The Cu APCs improved reaction kinetics.         Characterization of superconductors with artificial pinning microstructures    D.R. Dietderich and R.M. Scanlan Summary: Extension of the APC approach to Nb/sub 3/Sn requires that a second phase be introduced into the Nb/sub 3/Sn reaction layer with the intent of increasing the volume pinning strength. This can be achieved by either the refinement of the Nb/sub 3/Sn grains due to the presence of a second phase or by the second phase itself pinning flux. If a bronze-type process is to be used a different addition than Zr is required since internal oxidation of Nb is not possible. The criteria for elements to be candidates for the APC approach are discussed. The results for one of the candidates (Ag) show that it is not incorporated into the Nb/sub 3/Sn, however, its addition did increase the growth rate.         Effect of heat treatment on critical current density and n-value of (Nb,Ti)/sub 3/Sn multifilamentary superconducting wire    T. Miyazaki, Y. Inoue, T. Miyatake, Y. Fukumoto and M. Shimada Summary: Studies on the relationship between n-value and heat treatment conditions of Nb/sub 3/Sn multifilamentary wires in addition to those on be are presented. The wire was manufactured in bronze process. It was heated in various conditions, then voltage-current (V-I) characteristics of each specimen were measured. In the range of the heat treatment temperature, n-value increases with temperature but J/sub c/ decreases. The properties were discussed based on the results of microscopic observation and were investigated with upper critical field (Bc/sub 2/). The results from these investigations suggest the dependence of n-value on Bc/sub 2/.         Magnetic properties and microstructure of V/sub 3/Si multifilamentary superconductors    T. Takeuchi, Y.B. Kim, K. Itoh, Y. Nemoto, Y. Iijima, M. Kosuge, K. Inoue and H. Maeda Summary: Magnetic properties, in correlation with cross-sectional microstructures, were studied in order to check the potentiality of V/sub 3/Si multifilamentary superconductors for AC use. Irregularity of V filaments brings about the bridging between filaments during heat treatments. The effective filament diameter D/sub eff/ of 2.3 /spl mu/m is, however, comparable to that of bronze processed Nb/sub 3/Sn conductors. At long heat treatments, the V/sub 5/Si/sub 3/ layer initially forming around V/sub 3/Si filaments disappears, and then proximity coupling occurs additionally to the bridging. The proximity coupling causes the two peaks to appear in the magnetization curves and D/sub eff/ to increase at low fields. The existence of V/sub 5/Si/sub 3/ is quite effective in reducing D/sub eff/ and hence hysteresis loss.         Large-area growth of superconducting Y-Ba-Cu-O films by hot-wall sputtering method    R.J. Lin, L.I. Chen, C.C. Chin and Y.C. Chen Summary: Superconducting Y-Ba-Cu-O films have been deposited on [001]MgO substrates with a diameter of two inches using a simple, economic hot-wall DC sputtering system. The deposition chamber was made of a quartz tube and heated by a tube-furnace outside the chamber. The deposited films are highly oriented with perpendicular to the surface of the The superconducting properties of the films across the 2-inch-diameter area are zero resistance temperatures T/sub c/(R=0) of 88-90 K and critical current densities J/sub c/(77 K) of 1.6-3.5/spl times/10/sup 6/ A/cm/sup 2/.         Heating of large-area substrates for in situ deposition of YBCO    A.J. Drehman, J.S. Derov, J.A. Horrigan, R.J. Andrews and D.S. Linden Summary: We have developed a radiant technique for substrate heating which we found particularly useful for the in situ deposition of high temperature superconducting films. Using this technique, large area YBa/sub 2/Cu/sub 3/O/sub x/ films were deposited, using off-axis sputter deposition, onto lanthanum aluminate and sapphire substrates, the latter using an yttria-stabilized zirconia buffer layer. For both types of substrates we were able to obtain c-axis oriented films. The DC and microwave properties of the films deposited on lanthanum aluminate are presented along with the DC measurements of the films deposited on sapphire. The motivation for employing this method of heating are discussed, along with our current plans for scaling up the process to produce even larger area films.         YBaCuO thin films on sapphire up to 2-inch-diameter for microwave applications    R.K. Belov, Y.N. Drozdov, S.V. Gaponov, S.A. Gusev, A.Yu. Klimov, E. Kluenkov, K.V. Morozov, Y.N. Nozdrin, A.E. Parafin, S.A. Pavlov, A.N. Reznik, V.V. Talanov, A.V. Varganov, B.A. Volodin, A.K. Vorobyev, P.P. Vysheslavtzev, V.I. Abramov, B.B. Tagunov, I.B. Vendik, V.N. Osadchiy, V.O. Sherman and A.A. Svishev Summary: YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCo) thin films on R-plane sapphire up to 5-cm-diam with ZrO/sub 2/:Y (YSZ) buffer layers were fabricated by in-situ off-axis DC magnetron sputtering-and laser ablation. The film DC properties, critical current density (J/sub c/), effective microwave surface resistance (R/sub s/), X-ray data and surface morphology as functions of deposition temperature (T/sub d/) from 600 to 750/spl deg/C were studied. We have found out that the two processes simultaneously and in different ways affect the YBCO layers superconducting properties versus T/sub d/. The results show that films deposited at both ends of T/sub d/ range have equal critical temperatures but their J/sub c/ and R/sub s/ differ up to an order of magnitude. High-homogeneity 5-cm-diam films with J/sub c/>4 MA/cm/sup 2/ and R/sub s/<0.8, m/spl Omega/ at 10 GHz, and 77 K were routinely fabricated under optimum growth conditions. The effective 2 GHz short-dipole antenna and Wilkinson divider were developed and fabricated from the films.         Superconductivity and surface morphology of YBCO thin films prepared by metalorganic chemical vapor deposition    S. Oda, H. Zama and S. Yamamoto Summary: Device quality superconducting thin films of YBCO have been prepared by metalorganic chemical vapor deposition (MOCVD). Superconducting films with T/sub co/ higher than 80 K have been deposited at low temperatures, 500-550/spl deg/C, essential for heteroepitaxial device structure,on MgO substrates. Superconductivity of ultrathin (less than 10 nm) films of YBCO have been investigated together with surface morphology measured by atomic force microscopy. Atomic layer-by-layer growth has also been investigated. Tco=85 K has been obtained for a 24 nm-thick YBCO deposits for 20 cycle on SrTiO3 substrates at 650/spl deg/C. A very smooth surface with roughness of less than monomolecular layer and free of precipitates has been obtained over 10 /spl mu/m/spl times/10 /spl mu/m. Critical current density of 3/spl times/10/sup 7/ A/cm/sup 2/ has been obtained at 4.2 K and 3/spl times/10/sup 6/ A/cm/sup 2/ at 77 K for a 40 nm-thick film.         Surface diffusion in molecular beam epitaxy of Bi/sub 2/Sr/sub 2/Ca/sub n-1/Cu/sub n/O/sub x/    T. Ishibashi, H. Soutome, Y. Okada and M. Kawabe Summary: Thin films of Bi/sub 2/Sr/sub 2/CuO/sub 6+x/ (2201) phase have been tilted SrTiO/sub 3/ [001] substrates by co-deposition method, and Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+x/ (2212) phase by interruption technique. The surface diffusion characteristics the molecular beam epitaxy (MBE) of both phases have also been investigated by using in-situ reflection high energy electron diffraction (RHEED). The periodic RHEED intensity oscillations and recovery process been analyzed for 2201 and 2212 phases.         Study on local magnetic flux distribution in type II superconductors by means of small-angle neutron scattering    K. Osamura, H. Okuda, M. Furusaka, Y. Itoh, M. Imai, T. Matsushita and E.S. Otabe Summary: In order to assess the magnetic flux distribution in type II superconductors, the correlation function was derived from SANS intensities. The distribution in Nb single crystal was consistent with the result of magnetization measurements. An existence of short range ordering in the magnetic flux arrangement in Bi2212 crystal was suggested at 7.7 K under magnetic field of 0.25 T, which is a sufficiently high field larger than the critical field.         Mapping of magnetic force and field distribution of melt-textured Y-Ba-Cu-O    B. Lehndorff, H.-G. Kurschner and H. Piel Summary: Melt-textured YBa/sub 2/Cu/sub 3/O/sub 7-x/-bulk material has been prepared by a modified LPP-process. The samples have been characterized by optical microscopy, electron microscopy (SEM) and energy dispersive X-ray diffraction (EDX). An inductive method was used to determine critical current density J/sub c/ and transition temperature T/sub c/. The vertical levitation force and stiffness has been measured over the whole sample area using a permanent magnet and force sensors moved by a 3-dimensional positioning system. The measurements were performed in the field-cooled and zero-field-cooled state. In addition the magnetic field distribution of the flux frozen in by the superconductor was mapped with a Hall probe.         Observation of flux distribution on the surface of MPMG-processed YBCO    T. Higuchi, N. Sakai, M. Murakami and M. Hashimoto Summary: A macroscopic observation of a magnetic flux distribution on the surface of a superconducting bulk material was performed. First, a single-domained thin rectangular YBCO sample (10 mm/spl times/10m m/spl times/1 mm) was field-cooled in liquid nitrogen. After the applied field was turned off, a field distribution in the area of 10 mm/spl times/10 mm was mapped by scanning the sample surface at intervals of 0.5 mm using a Hall probe fixed to a XY-stage. The obtained field distribution was visualized into a three-dimensional distribution map and a two-dimensional contour graph. The overall shape of the field distribution had a four-fold symmetry reflected by the sample geometry. Next, assuming that the critical current density J/sub c/ is independent of the field strength, a field distribution generated by square current loops was calculated numerically. The intragranular J/sub c/ was estimated to be 2.6/spl times/10/sup 4/ A/cm/sup 2/ (77 K, OT) by fitting the calculated profile to the measured profile. Finally, it is found that the measurement of field distributions on the surface of a superconductor using a Hall probe is applicable to an estimation of an intragranular J/sub c/ for a superconductor without destroying the samples.         The effect of magnetic field orientation on the critical current of HTS conductor and coils    J.P. Voccio, A.J. Rodenbush, C.H. Joshi, J.W. Ekin and S.L. Bray Summary: The critical current of short samples of HTS multifilamentary conductor and ring-shaped coils has been measured at helium temperatures with varying magnetic field orientation with respect to the conductor. The samples and coil conductor consist of a multifilamentary composite of BSCCO-2223 filaments in a silver matrix. Short conductor samples were tested in a variable temperature system with up to 8 T background field using a sample rotational system. Ring-shaped coils made from the sample type of conductor were exposed to a large background field at liquid helium temperatures and critical current was measured with the ring located at various axial positions within the bore. As the ring moves closer to the end of the magnet, the measured critical current decreases, even though the magnitude of the field to which the ring is exposed decreases. This decrease in J/sub c/ is due to the strong anisotropy of the superconductor and is consistent with short sample measurements.         Improved strain tolerance in aligned-MgO-whisker reinforced (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ tapes    V. Selvamanickam, E. Bamberger, P.M. Martin and D.M. Kroeger Summary: The strain tolerance of monofilamentary BSCCO 2223 tapes has been improved by reinforcing with aligned-MgO whiskers. Tapes reinforced with 15 vol.% whiskers are found to exhibit a superconducting transition temperature of 106 K and a critical current density of 2/spl times/10/sup 4/ A/cm/sup 2/ at 77 K. The magnetic field dependence of current density of the reinforced tapes is found to be identical to that the unreinforced tapes. The reinforced tapes are found to sustain 90% of their initial current density even at a bend strain of 0.6%.         Effect of silver on phase formation and superconducting properties of Bi-2223/Ag tapes    S.X. Dou, Y.C. Guo, R.K. Wang, M. Ionescu, H.K. Liu, E. Babic and I. Kusevic Summary: The effect of Ag on the phase formation and superconducting properties of Ag-clad Bi-2223 tapes has been studied. TEM studies reveal that the grains adjacent to the Ag-sheath are nearly single 2223 phase with their c-axis perpendicular to the Ag-sheath, but in the interior of the superconductor core, an intergrowth of the 2223/2212 polytypoids within the grain and misalignment become evident. Ag addition in the Bi-2223 tapes lowers the annealing temperature and accelerates the formation of 2223 phase. However, its undesirable shape and large size cause grain misorientation and hence leads to a decrease of J/sub c/. The improvement in bend strain is attributable to the interfacial layer adjacent Ag sheath. The results of magnetoresistance of a well defined tape after correction for the parallel conduction through the Ag-sheath and the core show that the effective activation energy for the flux creep is larger than those for the single crystals and thin films. But the dissipative behaviour is similar to single crystals and the epitaxial thin films.         Axial tensile, transverse compressive and bending strain experiments on Bi(2223)/AgMg single core tapes    W. Goldacker, J. Kessler, B. Ullmann, E. Mossang and M. Rikel Summary: For the technical application of Bi(2223) tapes the use of a dispersion hardened AgMg sheath, with improved mechanical properties is of most importance. For the characterization of the strain sensitivity of the superconducting properties, the transport currents of the tapes were investigated with applied axial tensile strain, transverse compressive stress and as a function of bending strain applied at T=77 K. The application of dispersion hardened AgMg sheaths led to significantly improved mechanical properties of the tape, especially at temperatures below 77 K, compared to Bi(2223) tapes with pure Ag sheath. Bi(2223)/AgMg tapes are therefore promising for practical application since long lengths up to 102 m and high transport currents up to J/sub c/=18 000 A/cm/sup 2/ (77 K, OT) were obtained.         A comparative study of microstructure and transport critical current in cold rolled, cold uniaxially pressed and low load hot uniaxially pressed Ag-(Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ ta    M.P. James, B.A. Glowacki, J.E. Evetts, S.P. Ashworth, R. Garre and S. Conti Summary: The microstructure and transport critical current of cold rolled, cold uniaxially pressed, and low load hot uniaxially pressed Ag-(Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/, tape has been investigated. The transverse and longitudinal transport current measurements show strong correlation with morphological non-uniformities induced by the cold deformation processes. The aim of low load hot uniaxial pressing is to increase the density of the ceramic core and reduce the anisotropic nature of the critical current induced during the cold deformation processes. The deformation mechanisms of the silver and ceramic core when under load have been studied, and a deformation mechanism map has been constructed. Experimental investigation of the low load region over a range of temperatures has been carried out.         Ultrathin ceramic insulation for Ag-sheathed high T/sub c/-superconductors    A.D. Nikulin, A.K. Shikov, E.V. Antipova, N.E. Khlebova, I.A. Erokhina and I.I. Akimov Summary: The cover materials of ultrathin ceramic insulation not thicker than 3-6 /spl mu/m were suggested for use in coil processing. This cover was used for Bi-2223/Ag composite tapes without aggravation of their critical properties. High heat resistance (up to 840/spl deg/C) and small destroy bend radius permitted one to use "wind-and-react" as well as "react-and-wind" methods for coil fabrication. Results of critical properties measurements as a function of the cover thickness for insulated Bi-2223/Ag tapes as well as some characteristics of the insulating cover are presented.         Improvement of superconducting characteristics of a Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 2//Ag thick film by controlling the microstructure under reduced O/sub 2/ atmosphere    T. Hasegawa, H. Kobayashi, H. Kumakura and K. Togano Summary: The partial melting and slow cooling heat-treatment for a Bi-2212 thick film was carried out in 7% and 1% oxygen partial pressure. In 1% O/sub 2/ atmosphere, the partial melting point lowered below 850/spl deg/C. When cooling under 1% O/sub 2/, large Bi-free phases which were observed in samples heat-treated in air disappeared, resulting in the formation of this phase on the surface. Reduction of Ca and Cu concentration from stoichiometric composition is also effective to suppress the formation of Bi-free phases. The highest J/sub c/ value of 1.13/spl times/10/sup 5/ A/cm/sup 2/ at 4.2K in 4 T was obtained in a sample with the composition of Bi/sub 2.0/Sr/sub 2.2/Ca/sub 0.8/Cu/sub 1.9/O/sub x/ prepared in 1% O/sub 2/.         Improvement of J/sub c/ in Bi-2212-Ag composite superconductor by controlling Po/sub 2/ on the partial melt process    K. Shibutani, T. Hase, Y. Fukumoto, S. Hayashi, E. Inoue, R. Ogawa and Y. Kawate Summary: In a partial melt process for Bi-2212-Ag composite tapes, round and rectangular shape superconductors, the effects of oxygen partial pressure (Po/sub 2/) on the critical current density (J/sub c/) have been studied. It was found that the J/sub c/ of Bi-2212-Ag composite tapes increased from 4.5/spl times/10/sup 4/ A/cm/sup 2/ to 2.2/spl times/10/sup 5/ A/cm/sup 2/ at 4.2 K in zero magnetic field with increasing Po/sub 2/ from 0.1 bar to 1.0 bar. SEM observation for the cross sectional image and J/sub c/ measurement revealed that the partial melt process under higher Po/sub 2/ was effective in realizing well-aligned structure along the silver wall. These results were explained by the idea that crystallization of the Bi-2212 system starts at the interface between the liquid phase and the oxygen rich gas phase. In order to prove the potentiality of this process for the rectangular shape conductors, fabrication of a solenoid magnet has been attempted using rectangular shape conductors under high oxygen partial pressure. The typical results of this solenoid magnet, 2.7/spl times/10/sup 4/ A/cm/sup 2/ in J/sub c/ with generating magnetic field 0.70 T, and 4.3/spl times/10/sup 4/ A/cm/sup 2/ in quenching current density with generating magnetic field 1.13 T have been observed at 4.2 K in the self magnetic field.         Effect of post annealing on superconducting properties and microstructures of Bi(2212)/Ag tapes    A. Nagata, S. Yamauchi, S. Kamada, K. Sugawara, C. Takahashi, M. Nagano, Y. Wakiya and S. Hanada Summary: Bi(2212)/Ag tapes were fabricated by the melt-growth method at various cooling rates in air and Bi atmosphere followed by furnace cooling. Post-annealing at 810/spl deg/C was carried out for improving T/sub c/ and J/sub c/. T/sub c/ of as-solidified tapes was /spl sim/80 K, which increased to /spl sim/90 K after post-annealing. J/sub c/ of as-solidified tapes was scattered even at the same fabrication condition. Post-annealing reduced scattering of J/sub c/ and improved J/sub c/ of the tape with lower J/sub c/ values. However, samples with high J/sub c/ (4.2 K, 0 T) of 6/spl times/10/sup 4/ A/cm/sup 2/ after solidification was little improved by post-annealing.         Practical, coated BSCCO-2212 high T/sub c/ conductors    M.S. Walker, C.M. Trautwein, L.R. Motowidlo, D.R. Dietderich and F.A. List Summary: Results are reported for short samples of BSCCO-2212 conductor made by a dip-coat process. Samples were characterized by XRD, optical microscopy, SEM and transport critical current measurements. Critical currents of up to 14 amperes were measured in 5 mm wide tapes immersed in liquid nitrogen in zero applied magnetic field, with corresponding overall critical current densities at 77K, 0T of up to 2,700 A/cm/sup 2/.         Effects of Bi and Bi/sub 2/0/sub 3/ additions on the microstructure and superconducting properties of powder-in-tube BSCCO (2212) tapes    J. Guo, J.A. Lewis and K.C. Goretta Summary: The microstructural development and superconducting properties of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ (Bi-2212) Ag-clad powder-in-tube tapes with 2 vol% bismuth (Bi) added from either Bi (s) or Bi/sub 2/O/sub 3/ powders were investigated. Such additives reduce the peritectic decomposition temperature of pure Bi-2212 by approximately 15-20/spl deg/C. Scanning electron microscopy (SEM) and optical microscopy on polished top and cross-sections revealed that the volume fraction of Bi-free phases was lower in the Bi-added specimens relative to those based on pure Bi-2212. In addition, it appeared that the Bi-added samples had improved grain alignment, which was confirmed by X-ray diffraction analysis. Magnetic hysteresis (at 5 K between /spl plusmn/5.5 T) and transport measurements (at 4.2 K) were performed on each specimen. These results showed that Bi-additions yielded superior magnetization critical currents, which is attributed to improved grain alignment and reduced secondary phases.         Critical currents in conductors-exploring the limiting mechanisms    A.D. Caplin, L.F. Cohen, M.N. Cuthbert, M. Dhalle, D. Lacey, G.K. Perkins and J.V. Thomas Summary: The success of the BiSrCaCuO phase conductors in overcoming the "weak-link" problems that plague polycrystalline YBa/sub 2/Cu/sub 3/O/sub 7/ has been outstanding. In order to improve further their performance, we need to determine whether the critical current density J/sub c/ in these high current conductors is limited by "weak links" at the grain boundaries, or if flux pinning is the controlling factor. Magnetisation studies and current-voltage transport measurements made on the same sample allow this issue to be explored in detail. None of the classical "weak link" signatures appear in the behaviour of well-processed BiSrCaCuO conductors, but there is strong evidence of inhomogeneity that is field- and temperature-dependent. At high fields, the pattern of current flow appears to fragment into macroscopic islands, connected by "narrow bridges". The transport current is dominated by dissipation within these "narrow bridges", but this dissipation is similar in form to that found within grains, and is to be associated more closely with our pinning than with "weak links". These conclusions are reinforced by evidence on the anisotropy of the critical current with respect to field orientation, and also by the results of irradiation experiments.         Flux pinning and magnetic anisotropy in neutron irradiated Hg-Ba-Ca-Cu-O    Y.R. Sun, K.M. Amm and J. Schwartz Summary: Magnetic studies are performed on randomly oriented and aligned polycrystalline samples of HgBa/sub 2/CaCu/sub 2/O/sub 6+x/ (Hg-1212) and HgBa/sub 2/Ca/sub 2/Cu/sub 3/O/sub 8+x/ (Hg-1223). The measurements of magnetic hysterisis and magnetic relaxation confirmed the existence of a strong surface barrier. The decay of the critical current density J/sub c/ with temperature is much slower than the decay of their single-layered counterpart, Hg-1201. Measurements of aligned Hg-1212 revealed that the dependence of J/sub c/ on field orientation is relatively weak and the irreversible area in the H-T plane is much wider than other high temperature superconductors. Although neutron irradiation only enhances the critical current values moderately and severely suppresses the surface pinning, neutron irradiation improves all of the magnetic properties mentioned above, and at T=100 K, the hysteresis loop remains open up to H=6 kG.         Persistent current density and flux creep in Bi-Sr-Ca-Cu-O/Ag tapes with splayed columnar defects from 0.8 GeV proton irradiation    J.R. Thompson, L. Krusin-Elbaum, Y.C. Kim, D.K. Christen, A.D. Marwick, R. Wheeler, C. Li, S. Patel, D.T. Shaw, P. Lisowski and J. Ullmann Summary: Composite Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub 8//Ag tapes were irradiated with 0.8 GeV protons to create splayed columnar defects in the superconductor. The resultant effective pinning of vortices leads to an enhanced persistent current density in the CuO planes, displacement of the irreversibility line to higher temperatures and magnetic fields, and a major reduction in the logarithmic time decay rate of the supercurrent density.         Effect on c-axis transport properties of a critical state in Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/ single crystals    J.H. Cho, M.P. Maley and L.N. Bulaevskii Summary: At low temperatures, the c-axis transport properties of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/ single crystals depend strongly on the magnetic field history for fields applied along the c-axis, indicating the effect of a critical state in the ab direction. In this study, we report zero field cooled (ZFC), field cooled warming (FCW), and field cooled cooling (FCC) c-axis transport properties. In addition, we also report magnetic relaxation measurements on the same samples to identify the c-axis dissipation mechanism. We observe a relaxation of the c-axis resistivity that follows the relaxation of the flux profile across the ab plane. By identifying the irreversible temperature vs magnetic field for H/spl par/c, we construct a phase diagram of vortex states. Finally, we will discuss the implication of the phase diagram and the features related to the transport properties of the Josephson-coupled system and the role of pancake vortices in highly two-dimensional superconductors.         Pinning activation energies and the effect of cold deformation on critical currents in Bi(Pb)2223    F. Marti, M. Daumling and R. Flukiger Summary: We have measured magnetic hysteresis loops on silver sheathed Bi(Pb)2223 tapes. In these specially prepared tapes the grains are completely decoupled, thus allowing a determination of the intra-grain properties of Bi(Pb)2223. Mechanical deformation at room temperature causes fracture of the grains, but raises the critical current density by a factor of two. The irreversibility line appears not to be affected by the deformation. Using the generalized inversion scheme of Schnack et al. (1993) we have determined the flux pinning energies U(j,T), as well as the true (non-decayed) critical current density. Best fits are obtained in the local 2D single flux pancake pinning limit, and U(j/j/sub c/=0.1,T=0) is about 70 meV in a magnetic field of 0.2T perpendicular to the tape.         Vortex-glass-liquid transition and critical current density in Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ superconductors    H. Yamasaki, K. Endo, Y. Mawatari, S. Kosaka, M. Umeda, S. Yoshida and K. Kajimura Summary: We have investigated I-V characteristics in epitaxial Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/, thin films and Ag-sheathed tapes in magnetic fields applied parallel to the c-axis, and observed a transition from the vortex-liquid phase characterized by finite linear resistivity /spl rho//sub lin/=(E/J)/sub J/spl rarr/0/=constant, to the vortex-glass phase with vanishing linear resistivity. The transition shows quasi-2D nature and a power-law relation E/spl sim/J/sup z+1//spl ap/J/sup 6.5/ is observed at the transition temperature T/sub g/, while E/spl sim/J/sup z+1//2/spl ap/J/sup 3/ is observed in YBa/sub 2/Cu/sub 3/O/sub 7/ at T=T/sub g/, where z is a critical exponent. The importance of the vortex-glass transition in applied superconductivity is discussed.         Anisotropic flux pinning in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// single crystals    V.M. Pan, V.F. Solovjov, V.L. Svetchnikov and H.C. Freyhardt Summary: Direct transport measurements of the critical currents as well as their angular and field dependencies in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// single crystals were performed. The role of twin planes as extended defects, which provide a vortex locking, is studied and their contribution to the J/sub c/ anisotropy is analyzed. The angular dependence of the critical current is represented as a combination of a contribution from extended defects and a point-like-defect-induced anisotropic background. The latter is responsible for the major part of the measured J/sub c/ anisotropy. The observed Kramer-like scaling law concerning the dependencies of the volume pinning force versus the applied magnetic field component along the c-axis indicates a three-dimensional flux line lattice behavior and excludes vortex decoupling as a possible mechanism of the "fishtail-effect".         A facility for the characterization of the critical current of superconductors as a function of strain and magnetic field    L.T. Summers, R.P. Walsh and J.R. Miller Summary: A unique facility for the characterization of both low and high temperature superconductors is being designed and constructed at The National High Magnetic Field Laboratory (NHMFL). The facility is designed to allow the determination of strain effects on the critical current of superconducting materials as well as mechanical properties as a function of temperature. As presently designed the system can work with small wires (diameter <1.0 mm) and tapes, or it can be modified to handle large conductors with currents up to 10 kA. Mechanical properties can be measured over a broad range, with force resolutions as low as 0.05 N, a maximum load of up to 250 kN, and with monotonic or cyclic loading. Samples can be evaluated in fields up to 14 T with active sample lengths of 150 mm. Here we will report the present status of this facility and describe detailed specifications of testing capabilities.         Tensile strain/transverse compressive stress effects in bronze processed Nb-matrix Nb/sub 3/Sn wires    K. Katagiri, T. Kuroda, H. Wada, H.S. Shin, K. Watanabe, K. Noto, Y. Shoji and H. Seto Summary: Mechanical properties and the strain/stress dependence of the critical current I/sub c/ of Nb-matrix Nb/sub 3/Sn multifilamentary wires fabricated through bronze route were evaluated up to a magnetic field of 14 T at 4.2 K. The wire showed a 0.2% proof stress of 550MPa, which is 3.4 times higher than that in the conventional bronze processed Nb/sub 3/Sn wires. The strain sensitivity of I/sub c/ and the reversible strain limit, 0.8%, were almost the same, but the axial tensile strain for the peak I/sub c/, 0.1%, was small compared with those in the conventional wires. On the other hand, the transverse compressive stress sensitivity of I/sub c/ was remarkably low. The irreversible stress where I/sub c/ on unloading no longer recovers to the initial value was larger than 300MPa, which is several times higher than those in conventional wires. Thus, these results show that the wire is highly tolerant to the external stress/strain.         Residual strain estimation in multifilamentary Nb/sub 3/Sn wires with CuNb reinforcement    K. Watanabe, K. Katagiri, K. Noto, K. Awaji, S. Awaji, K. Goto, N. Sadakata, T. Saito and O. Kohno Summary: The bronze processed multifilamentary Nb/sub 3/Sn superconducting wires with Cu-20 wt.% Nb composite reinforcement, which exhibited the high yield stress even after a typical heat treatment of about 700/spl deg/C for 8 days, have been fabricated. The strain effects on the critical current of the Nb/sub 3/Sn wires reinforced with CuNb composite were measured, and the estimation of residual strain was performed using a rule of mixtures. Good agreement is obtained between measured and calculated residual strain values.         The influence of compressive and tensile axial strain on the critical properties of Nb/sub 3/Sn conductors    B. ten Haken, A. Godeke and H.H. ten Kate Summary: Various Nb/sub 3/Sn conductors are investigated in an axial strain experiment. The superconducting samples are soldered to a substrate that is bent to generate a compressive or tensile axial strain. Especially in the compressive strain range the critical current reduction is smaller than predicted by the well-known scaling law. The influence of the transverse strain components is investigated in a tape conductor by changing the thermal strain. It is found that the axial strain experiments can be described by an upper-critical field that depends on the deviatoric component of the strain tensor only. Finally a comparison of the critical temperature and the critical current as a function of axial strain is made.         Development of a Nb/sub 3/Sn superconducting strand with tie-processed Nb surface coating to limit inter-strand eddy currents in cables    D. Yu, J. Wong and K. Demoranville Summary: ITER/TPX-type bronze-route Nb-coated Nb/sub 3/Sn strands were successfully fabricated using a co-processing technique as an alternative to the existing hard chrome plating method. Results show that a continuous Nb layer as thin as 2-3 /spl mu/m can be formed on the surface of TPX/ITER strands during strand processing. This Nb coating prevents the superconducting strands in a Cable-in-Conduit (CIC) conductor from sintering during Nb/sub 3/Sn reaction heat treatment. It was demonstrated that the Nb surface coating does not degrade the residual resistance ratio (RRR) of the Cu stabilizer in the strand as well as the critical current density in superconducting filaments. The additional magnetization hysteresis loss due to the Nb surface coating is negligible when compared to the loss from Nb/sub 3/Sn filaments in the strand.         Effects of diffusion barrier on the magnetization cycles of Nb/sub 3/Sn strand for ITER conductor    P. Gislon, S. Chiarelli, M. Spadoni, L. Bottura, S. Conti and R. Garre Summary: High performance Nb/sub 3/Sn strands for the high field ITER (International Thermonuclear Experimental Reactor) magnets have been manufactured using diffusion barriers among the multifilamentary cores and the stabilizing copper. In the conductor development programme, billets using a single Ta or a double NbV barrier have been assembled. The barrier is shown to have an influence on magnetization characteristics. The measurements on samples from the two types of strands are shown and analyzed to correlate them with the magnetic behaviour of Nb at low field. The results show that at low field hysteretic losses are greatly increased by the pure Nb of the barrier. At high field, losses of samples with Ta barrier are larger, due to their higher J/sub c/.         Dual barrier for the suppression of residual resistance degradation in chrome-plated niobium-tin strands    E. Gregory, E.A. Gulko, T. Pyon, M.D. Sumption and E.W. Collings Summary: For large fusion magnet applications it has been suggested that the Nb/sub 3/Sn superconductor strand be chrome plated to reduce the sintering tendency and to increase the electrical resistance between the strands. Unfortunately, this chrome plating appears to degrade the RRR after the reaction heat treatment. In addition to the normal Nb/sub 3/Sn material with a barrier separating the copper stabilizer from the rest of the conductor, materials have been made with a second barrier close to the surface. One had 10% and the other 20% by volume of copper on the outside of this external barrier. The variation of the RRR of chrome-plated lengths of these material has been explored for a range of different heat treatments and their significance to TPX and ITER magnets is discussed.         Chromium diffusion into plated Nb/sub 3/Sn strands deduced from electrical resistivity measurement    M.D. Sumption and E.W. Collings Summary: During the reaction heat treatment of Cr-plated Nb/sub 3/Sn multiflamentary strands the purity, and hence resistance ratio, of the Cu stabilizer becomes measurably degraded. The present study exploits the power of resistance-ratio (RR) measurement in exploring the role that Cr plays in this degradation. It is deduced that during the reaction heat treatment (RHT) of unplated strands oxygen diffusion (from the surrounding atmosphere) and subsequent internal oxidation can result in exceptionally high values of RR. Chromium on the other hand has two deleterious influences: (i) it retards the ingress of oxygen thus inhibiting the tendency towards high RR development; (ii) it diffuses in, and itself degrades RR. It is also pointed out that some of the lost RR can be recovered by subjecting the strand to prolonged moderate temperature post-RHT step-cooling from 600/spl deg/C.         YBCO thin-films current-carrying elements on metallic substrates    S.N. Ermolov, V.A. Bliznyuk, V.M. Ievlev, A.Y. Isaev and V.A. Lykhin Summary: Electron-microscopic investigations about growing YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films on monocrystalline Ni substrates with buffer layers of MgO have been carried out. The condition, under which the forming epitaxial YBCO films with T/sub c/(R=0)=85 K, and j/sub c/(H=0.77 K)/spl ap/ 2/spl times/10/sup 5/A/cm/sup 2/ are proceeding, has been determined.         Orientation control of YBaCuO film on flexible metallic substrates with buffer layers using pulsed laser deposition    Y. Yamagata, C.-S. Choi, T. Fujishima, T. Ikegami, K. Ebihara and Y. Suda Summary: A preparation of YBaCuO thin film on a flexible metallic substrate with YSZ buffer layer by the KrF pulsed laser deposition (PLD) was investigated. The orientation of the YBaCuO/YSZ/Metal film was controlled by the YSZ deposition conditions. A critical temperature and a critical current density of the YBaCuO/YSZ film were 81.8 K, 1.2/spl times/10/sup 3/A/cm/sup 2/ (at 77.3 K) for Hastelloy substrate, and 79.2 K, 10/sup 2/A/cm/sup 2/ for Inconel substrate, respectively. Those low values resulted in their polycrystalline structures.         Optimization of YBa/sub 2/Cu/sub 3/O/sub 7-x/ thick films on yttria stabilized zirconia substrates    M.W. Hooker, S.A. Wise, P. Hopson Jr., M.N.H. Kruse and J.W. High Summary: This report describes the optimization of the firing process used in the production of YBa/sub 2/Cu/sub 3/O/sub 7-x/ thick films screen printed on yttria-stabilized zirconia substrates. The highest critical current density (J/sub c/) values were obtained by employing a double layer printing technique in which a single superconductive layer was printed onto a zirconia substrate and fired, followed by the subsequent deposition and firing of second superconductive layer. Using this procedure, thick film superconductors with a superconductive transition temperature (T/sub c/) of 85 K and a J/sub c/ of 130 A/cm/sup 2/ were obtained by sintering the printed films at 950/spl deg/C for 90 minutes, followed by a six hour oxygen annealing treatment at 600/spl deg/C. Specimens sintered for comparable periods of time at 940 and 960/spl deg/C did not exhibit superconductive behavior above 77 K due to either incomplete microstructural development or thermal decomposition of the superconductive phase respectively.         Relationships between processing temperature and microstructure in isothermal melt processed Bi-2212 thick films    T.G. Holesinger, D.S. Phillips, J.O. Willis and D.E. Peterson Summary: The microstructure and phase assemblage of isothermal melt processed (IMP) Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/ (Bi-2212) thick films have been evaluated. Results from compositional analysis and phase identification indicate that the characteristics of the partial melt greatly influence the microstructural and chemical development of the thick films. The highest critical current densities were obtained in films processed below 800/spl deg/C where the partial melt uniformly coats the substrate without excessive phase segregation.         Preparation and superconducting properties of Bi2223 thick films by the doctor-blade process    K. Yoshikawa, J. Hirabayashi, H. Ikeda and R. Yoshizaki Summary: For this feasibility study, superconductor/silver/PSZ (partial-stablized-zirconia) composite samples with a superconductor composition of Bi/sub 1.84/Pb/sub 0.34/Sr/sub 1.91/Ca/sub 2.03/Cu/sub 3.06/O/sub y/ (2223), were fabricated via the doctor-blade technique. It was found that the densification and alignment of 2223 grains along the composite interface was crucial to achieving high critical current densities (J/sub c/). The effects of heat treatment and uniaxial hot pressing pressure were investigated to develop a scheme to maximize J/sub c/. The highest zero-field J/sub c/ value of 3/spl times/10/sup 7/A/m/sup 2/ at 77 K was obtained in a uniaxial hot pressing at 1108 K.         Spraying technology of production of long HTSC coatings    E.V. Bykov, A.V. Grigor'eva and V.A. Shkut Summary: This technology allows one to produce long HTSC coatings for manufacture of tapes and wires, shields and antennas. Gas-thermal methods allow one to obtain films (10-100 /spl mu/m) on non-oriented substrates of arbitrary shape. Crystallisation produced by the gas-flame method allows one to obtain dense coatings with high adhesion. These HTSC composites are easy workable to shape into the desired geometry. Parameters for Bi-Sr-Ca-Cu-O are T/sub c/=107 K, j/sub c/=2 10/sup 3/A/cm/sup 2/ at T=77 K. The proposed method has high productivity and low cost.         Formation of colonies of locally aligned grains during thallination of spray-pyrolyzed Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ thick films    A. Goyal, E.D. Specht, D.M. Kroeger, J.E. Tkacyzk, C.L. Briant and J.A. DeLuca Summary: Recent microstructural studies of high-J/sub c/, Tl-1223, spray-pyrolyzed thick films have shown that the high J/sub c/ and reduced weak-link behavior can be ascribed to the presence of a unique microstructure, wherein the film is divided into "colonies" of biaxially aligned regions. In an effort to understand the nucleation and growth of Tl-1223 as well as the formation of the "colony" microstructure, several sets of films quenched from various stages of the high-temperature thallination process were examined using electron microscopy, X-ray diffraction and electron backscatter diffraction (EBSP). It is found that the crystallization of the 1223 phase is associated with formation of a liquid phase which contains significant amounts of all oxides. X-ray micro-diffraction measurements show that the 1223 phase crystallizes in an aligned manner. Studies of films very early into the thallination process show that local biaxial alignment or the formation of colonies starts to occur at the onset of 1223 crystallization. In addition, it appears that the structure within colonies is a function of the processing conditions employed. This presents the possibility for further optimization of the microstructure to attain improved superconducting properties.         Properties of Tl-1223 superconducting thick films fabricated from precursor inks using a thallium vapor transport process    R.T. Kampwirth, J.G. Hu, J.D. Hettinger, D.J. Miller, K.E. Gray and J.A. DeLuca Summary: Using a two-zone thallium vapor transport furnace and a thick film ink process, we have successfully made superconducting films 10 to 50 /spl mu/m thick on a variety of substrates. Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ and Bi/sub 0.22/Sr/sub 1.6/Ba/sub 0.4/Ca/sub 2/Cu/sub 3/O/sub x/ precursor films with and without Ag additions were made by mixing powders in an organic vehicle, painting a substrate and burning the vehicle off. Films were converted to the superconducting phase by passing an O/sub 2/ carrier gas over a Tl/sub 2/O/sub 3/ source and then the sample. TBCCO 1223 films generally form over a narrow sample temperature range near 860/spl deg/C, whereas TBSBCCO films form 1213, 1223 or a mixture of these phases depending on sample annealing temperature and O/sub 2/ partial pressure. TBCCO T/sub c/'s average 104 K with zero-field J/sub c/ (77 K) /spl ap/3500 A/cm/sup 2/ while TBSBCCO T/sub c/'s are higher at 110 K with J/sub c//spl ap/6800 A/cm2. Both compounds show weak-link behavior in a magnetic field.         Thermal processing of spray-pyrolyzed and electrodeposited Tl superconductor films and optimization of the transport critical current density    P.A. Parilla, D.L. Schulz, R. Bhattacharya, R.D. Blaugher, D.S. Ginley, J.A. Voigt, E.P. Roth and E.L. Venturini Summary: Employing a flow-through "two-zone" thermal processing system to control thallous oxide vapor pressure, we have investigated two different types of precursors and explored their potential for producing open tape conductors with high critical current densities. The two methods examined were: (1) precursor Pb-Sr-Ba-Ca-Cu-O(Ag) sprayed as a colloidal ink onto a heated substrate; (2) precursor material deposited by electrodeposition from an electrolytic solution containing the metal nitrates. Although both of these methods produce precursors with the proper stoichiometric ratios, vast differences in other properties such as reactivity, density, thickness, and morphology exist. The effects of these precursor properties upon subsequent superconducting characteristics such as phase development, final morphology, and electrical transport are characterized by XRD, SEM/optical microscopies, R vs. T and J/sub c/ measurements, respectively. Both types of precursors have produced superconducting films with high J/sub c/'s. Phase-pure textured films have been obtained on a variety of substrates.         Superconducting Tl-Pb-Ba-Sr-Ca-Cu-O(Ag) thick films (5-20 /spl mu/m) prepared using a commercial spray pyrolysis system and 2-zone furnace annealing    D.L. Schulz, P.A. Parilla, D.S. Ginley, J.A. Voigt, E.P. Roth and E.L. Venturini Summary: A spray pyrolysis route to superconducting Pb-, Sr-, and Ag-substituted Tl-Ba-Ca-Cu-O thick films has been developed. First, a precursor powder with the stoichiometry Pb/sub 0.46/Ba/sub 0.40/Sr/sub 1.52/Ca/sub 1.86/Cu/sub 3.00/O/sub x/(Ag/sub /0/sub .37/) (PBSCCO) was synthesized with the particle size of this powder being subsequently reduced to 4-6 /spl mu/m using a ball mill. Next, this powder was mixed with ethyl cellulose binder and sprayed with an airbrush using an N/sub 2/ carrier gas, polycrystalline Y/sub 2/O/sub 3/:ZrO/sub 2/ (YSZ) as single-crystal MgO, SrTiO/sub 3/, NdGaO/sub 3/, and LaAlO/sub 3/ substrates were mounted on a hot plate with typical growth temperatures of 80-100 /spl deg/C. Growth times of /spl sim/10 min provided films which were 5-20 /spl mu/m in thickness. After an intermediate O/sub 2/ anneal to remove the organic binder, these films were subjected to a flowing 2-zone thallination process. Very well c-axis oriented Tl/sub 0.70/Pb/sub 0.36/Ba/sub 0.39/Sr/sub 1.58/Ca/sub 1.98/Cu/sub 3/O/sub x/ (TP-1223) phase material was obtained for films grown on single-crystal LaAlO/sub 3/. Films grown on all other substrates surveyed in the study gave rise to impurity phase formation and/or incomplete reaction. The PBSCCO and TP-1223 films were characterized by /spl theta//2/spl theta/ and /spl omega/-rocking curve X-ray diffraction (XRD) analyses, scanning electron microscopy (SEM), variable temperature magnetic measurement, and inductively coupled plasma atomic emission spectroscopy (ICPAES).         Synthesis and properties of superconducting (Tl,Pb)-(Sr,Ba)-Ca-Cu-O thick films on Ag    E.L. Venturini, J.A. Voigt, D.L. Lamppa, T.L. Aselage and E.P. Roth Summary: We report successful texturing of screen-printed (Tl,Pb)-(Sr,Ba)-Ca-Cu-O thick (20 /spl mu/m) films on both LaAlO/sub 3/ and Ag foil using rapid thermal processing (RTP) followed by furnace annealing. An RTP cycle to /spl ap/915/spl deg/C for 20 seconds in Ar produces massive melting of the superconducting powder but not the Ag substrate. Subsequent annealing under O/sub 2/ in sealed Au foil with a Tl source yields a brick-wall microstructure consisting of c-axis aligned, plate-like grains. X-ray diffraction and Meissner data show a mixture of the Tl-1223 and Tl-1212 phases while energy-dispersive spectroscopy identifies the plate-like grains as the desired Tl-1223. Magnetization data suggest intergranular supercurrents flowing across the entire film. Critical current densities inferred from hysteresis are 9/spl times/10/sup 4/ A/cm/sup 2/ at 5 K in low fields, decreasing by a factor of 5 in 5 tesla.         High-frequency surface impedance and penetration depth of YBa/sub 2/Cu/sub 3/O/sub 7/ films: coherent time-domain spectroscopy method    F. Gao, J.F. Whitaker, C. Uher, S.Y. Hou and J.M. Phillips Summary: The transmission (/spl Jscr/) and phase shift (/spl thetav/) of 0.2-1.5 THz radiation have been measured simultaneously on unpatterned, high-quality YBa/sub 2/Cu/sub 3/O/sub 7/ films (T/sub c/=90 K) in the normal and superconducting states using a coherent, pulsed, time-domain technique. The complex surface impedance has been extracted without contacting or patterning the superconducting films using /spl Jscr/ and /spl thetav/. Above T/sub c/, both the real (R/sub s/) and imaginary (X/sub s/) parts show a metallic /spl radic//spl omega/T dependence with almost equal magnitude as predicted by the normal skin effect. Below T/sub c/, R/sub s/ scales with /spl omega//sup 2/, but only for /spl omega//2/spl pi/ <400GHz; it increases more slowly with frequency above 400 GHz. The reactance X/sub s/ is linear in /spl omega/ for T<         Penetration depth and critical current in NbN resonators: predicting nonlinearities and breakdown in microstrip    T.E. Takken, M.R. Beasley and R.F.W. Pease Summary: Parallel plate and microstrip resonator experiments show that NbN films have large magnetic penetration depth and a peak RF critical current density which either matches or exceeds the DC critical current density, depending on the temperature. The large penetration depth, /spl lambda/, suggests that narrow NbN transmission lines will have increased inductive nonlinearities, when compared with other superconductors. The relation between the DC and peak RF critical current densities indicates that by modeling the RF current distribution a simple DC breakdown measurement can be used to estimate a transmission line's RF current carrying capacity.         Evaluation of magnetic penetration depth and surface resistance of superconducting thin films using coplanar waveguides    K. Yoshida, K. Watanabe, T. Kisu and K. Enpuku Summary: We have proposed a method to evaluate the magnetic penetration depth and the surface resistance of superconducting thin films from the kinetic inductance measurement using coplanar waveguides. The method utilizes the coplanar waveguide resonator where the temperature dependence of the resonant frequency due to the kinetic inductance is measured. Comparison between the observed data and an analytical expression using a conformal mapping technique gives the value of the magnetic penetration depth. The magnetic penetration depth of NbN thin films obtained in this way is shown to be in excellent agreement with that estimated from the dirty limit theory using resistivity and critical temperature. By applying this method to a YBaCuO resonator, we obtained the magnetic penetration depth /spl lambda/(0)=266 nm for a c-axis oriented film. Using the two-fluid model it is also shown that the surface resistance of the film can be evaluated from the quality factor and the kinetic inductance. We obtained the residual surface resistance Rs(0)=20 /spl mu//spl Omega/ at a frequency of 3.8 GHz.         HTS microwave cavity with temperature-independent frequencies    F.M. Mueller, D. Reagor, C.J. Maggiore, D. McMurry, D.W. Cooke, T.C. Plyum, R.E. Muenchaussen, P.N. Arendt, M.A. Daugherty, B.F. Roberts, R.B. Cass and R. Loh Summary: An HTS-walled and sapphire-loaded class of microwave cavities is described whose low TE modes show a frequency maximum at a controllable temperature. This makes the resonant frequencies of such passively compensated cavities independent or invariant of temperature at this point. Two different experimental realizations are presented. For a 7.8 GHz TE 011 mode, one cavity exhibited a frequency shift of less than 12 kHz over a 25 degree range, centered at 115 Kelvin.         Microwave conductivity of patterned YBa/sub 2/Cu/sub 3/O/sub 7/ thin films    A. Porch, J.R. Powell, M.J. Lancaster, J.A. Edwards and R.G. Humphreys Summary: We have used coplanar resonators to provide a sensitive measure of the ab-plane microwave complex conductivity /spl sigma/=/spl sigma//sub 1/-i/spl sigma//sub 2/ at 8 and 16 GHz of high quality, patterned thin films of YBa/sub 2/Cu/sub 3/O/sub 7-/spl sigma// on MgO substrates. No BCS coherence effects were observed in /spl sigma/1(T) below T/sub c/. Instead, we observe a broad peak centred between 40 and 50 K, which was present in all of the samples. The T dependence of the magnetic penetration depth /spl lambda/(T)=(/spl omega//spl mu//sub 0//spl sigma//sub 2/(T))/sup -1/2/ also differed from that expected for a BCS superconductor in the London limit. This difference is most noticeable at low T, where instead of the usual exponential T dependence, we observe a term in T/sup 2/ for every sample. We discuss briefly the effects of sample oxygenation on these results.         Microwave power dependence of HTS thin film transmission lines    J.S. Herd, J. Halbritter and K.G. Herd Summary: Stripline resonator measurements indicate nonlinear response in thin film YBa/sub 2/Cu/sub 3/O/sub 7-x/ transmission lines when microwave power levels exceed a certain critical level. The nonlinearities likely originate in the intergranular junctions of the c-axis epitaxial films. An effective medium approach is used here to model the series impedance of the grain junctions. The field dependence of the surface resistance and penetration depth in the junctions are modeled at low fields with a Ginzburg-Landau type response, at intermediate fields by an intergranular fluxoid state, and at high fields by a flux flow shielding state which occurs at a frequency and temperature dependent transition field H/sub trJ/. Comparisons are made with measured data over a range of frequencies and power levels.         Hysteretic microwave magnetoabsorption in granular cuprate superconductors-the role of random fields    J.S. Ramachandran and S.M. Bhagat Summary: The phenomenon of hysteretic DC field induced microwave absorption is linked to the existence of random fields within the granular sample. A simple method to access the parameters defining the distribution of random fields is demonstrated.         Consequences of d-wave superconductivity for high frequency applications of cuprate superconductors    J. Mao, S.M. Anlage, J.L. Peng and R.L. Greene Summary: A number of recent experiments suggest that the superconducting ground state wave function in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) has d-wave symmetry. However little attention has been given to the consequences of d-wave pairing symmetry on applications of the cuprates. An intrinsic finite residual loss, approximately one order of magnitude below the lowest losses measured in YBCO thin films at 10 GHz, is one important consequence. In addition, an unusual sensitivity to disorder, an intrinsic non-linear power dependence, and unique mid-gap states associated with specific film textures and possibly twin boundaries, are also expected. We present our own attempts to identify these unique properties of d-wave superconductors, and discuss how these results may dictate the ultimate limitations of the cuprates in high frequency applications.         Preparation of high quality YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thick films on flexible Ni-based alloy substrates with textured buffer layers    X.D. Wu, S.R. Foltyn, P. Arendt, J. Townsend, I.H. Campbell, P. Tiwari, Q.X. Jia, J.O. Willis, M.P. Maley, J.Y. Coulter and D.E. Peterson Summary: High current YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thick films on flexible nickel substrates with textured buffer layers were fabricated. Highly textured yttria-stabilized-zirconia (YSZ) buffer layers were deposited by using ion beam assisted deposition (IBAD). Pulsed laser deposited YBCO films were not only c-axis oriented with respect to the film surface but also strongly in-plane textured. The in-plane mosaic spread of YBCO films was/spl sim/10/spl deg/. A critical current density of 8/spl times/10/sup 5/ A/cm/sup 2/ was obtained at 75 K and zero field for thin YBCO films. It was also demonstrated that thick YBCO films with a high critical current and excellent magnetic field dependence at liquid nitrogen temperature can be obtained on flexible nickel substrates by using the textured buffer layers. Issues encountered in producing the films were discussed.         Multilayer Y-Ba-Cu-O structures using ion-assisted intermediate layers    R.P. Reade, P. Berdahl, R.E. Russo and L.W. Schaper Summary: Multilayer thin films of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) were deposited in situ on yttria-stabilized zirconia (YSZ) and CeO/sub 2/ intermediate layers grown using ion-assisted pulsed-laser deposition. These structures were grown on amorphous SiO/sub 2/ dielectric layers. A critical current density of 3/spl times/10/sup 5/ A/cm/sup 2/ was obtained for a YBCO film grown on SiO/sub 2/-coated Haynes Alloy 230 substrate. Improvement of the critical current density was obtained below 77 K by doping the YBCO with 10% Ag. Angular magnetoresistance measurements provide further information about the texture of this film.         Preparation of cathodic arc deposited HTSC Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+y/-Ag composite thin films on Ag substrates    M.S. Chae, M.B. Maple, M.T. Simnad, S. Anders, A. Anders and I.G. Brown Summary: Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+y/-Ag composite thin films on Ag substrates were prepared by cathodic arc deposition of alloy precursors. The deposition technique employed a cathode comprised of a precursor alloy for the vacuum arc plasma source. The precursor alloy was prepared by multiple arc-melting of mixed metallic constituents of the high-temperature superconducting material Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+y/ (BSCCO-2212) and 50 wt.% of Ag. The presence of silver in the precursor alloy film was expected to allow accommodation of the lattice and thermal expansion mismatch between the oxidized film and the silver substrate. Following deposition, controlled oxidation of the precursor alloy thin film on the Ag substrate was performed to produce the superconducting composite on the silver substrate, After the heat treatment, the composite film consisted of single phase BSCCO-2212 highly c-axis oriented normal to the Ag substrate.         High J/sub c/ YBCO thick films prepared by LPE method    I. Hirabayashi, M. Yoshida, T. Kitamura, O.-B. Hyun, Y. Shiohara, S. Tanaka, A. Tsuzuki, Y. Sugawara and Y. Ikuhara Summary: High-J/sub c/ YBa/sub 2/Cu/sub 3/O/sub y/ thick films were prepared by the liquid phase epitaxy (LPE) method. The growth rate was typically about 2 /spl mu/m/min, which was 10-10/sup 2/ times larger than that by conventional vapor growth techniques. The T/sub c/ of the best film exceeded 88 K after oxygen annealing, and the transport zero-field J/sub c/ was over 10/sup 5/ A/cm/sup 2/ at 77 K. The peak effect in J/sub c/-B characteristics was observed at several tesla by magnetic and transport measurements. Based on the micro-structure, the relevant peak effect is considered to be caused by stacking faults which act as a field induced pinning center.         Critical current in Tl-base high-Tc oxides synthesized through a diffusion process    K. Tachikawa, A. Kikuchi, T. Kinoshita and S. Komiya Summary: In the TBCCO diffusion composites, the 2223 phase is easily formed within a short reaction time. The critical current at 77 K is significantly improved by the F addition to the coating layer. The F addition decreases the degradation of critical current under magnetic field at 77 K, and shifts the irreversibility line to higher temperature. The XRD study reveals that the F addition clearly promotes the phase transformation from 2223 to 1223. Meanwhile, the annealing in flowing O/sub 2/ at 550/spl deg/C-600/spl deg/C also increases the critical current at 71 K. A J/sub c/ of about 10,000 A/cm/sup 2/ is obtained at 77 K in the TBCCO diffusion layer by the F addition and the O/sub 2/ annealing.         The effects of stoichiometry in the (Tl,Pb)/sub 1/(Sr,Ba)/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ system on the transport properties of Ag-clad tapes    E.P. Roth, J.A. Voigt, E.L. Venturini and P. Halder Summary: Evidence shows that texturing is necessary to achieve high current densities and strong links in the Tl-based superconductors. Conventional sintering is not sufficient to achieve strong links, but instead, melt processing is required to produce platelets which can develop into a textured structure. Changes in the stoichiometry of the precursor powders can lead to enhanced melt-phase formation at lower processing temperatures. An experimental matrix was designed with variations in the Tl/Pb ratio, the total Tl/Pb content, and the Ca/Cu level to change liquid formation and subsequent grain growth. Thirteen compositions were prepared in both pellet form and as Ag-clad tapes to investigate grain development over a range of thermal processing conditions. Tapes were produced using unreacted powders by the powder-in-tube method and processed by conventional furnace annealing. We report here on the transport properties of these tapes, their strong link behavior, and microstructural development.         Anisotropic transport properties of Tl(1223) magnetically aligned ceramics and spray pyrolyzed films    J.E. Tkaczyk, K.W. Lay, B.A. Jones, B.J. Bednarczyk and J.A. DeLuca Summary: Uniaxially textured TlBaSrCa/sub 2/Cu/sub 3/O/sub 9/ bulk ceramics have been fabricated by slip casting in magnetic fields up to 9 Tesla followed by sintering and reduction annealing. The measured transport properties are compared with those of spray pyrolyzed thick films where the degree of <001> texture is controlled through processing. Transport anisotropy is correlated to the degree of texture but not to the magnitude of the critical current density. In fact, although the critical current density of the aligned ceramic has the lowest value and is the most sensitive to small magnetic fields, it is also the most anisotropic with respect to the field direction. These data indicate that <001> texture is necessary but not sufficient for high critical current density in the Tl(1223) system.         Author Index (1994 - Part 2)    No author information available Summary: Not available

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