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Superconductivity: Past, present, and future

Description: This paper provides an overview of superconductor research and development activities, with emphasis on the potential of high-{Tc} materials for future applications. Superconductor applications are grouped under the following categories: electronics/instrumentation, bulk material/castings, research devices, industrial/commercial, electric power, and transportation/propulsion. Near-term applications are typically based on thin film and cast forms of high-{Tc} materials, while large-scale applica… more
Date: January 1, 1992
Creator: Uherka, K.L.
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Partner: UNT Libraries Government Documents Department
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(Gamma scattering in condensed matter with high intensity Moessbauer radiation)

Description: This report discusses: quasielastic scattering studies on glycerol; gamma-ray scattering from alkali halides; lattice dynamics in metals; Moessbauer neutron scattering, x-ray diffraction, and macroscopic studies of high {Tc} superconductors containing tungsten; NiAl scattering studies; and atomic interference factors and nuclear Casimir effect.
Date: January 1, 1992
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The influence of anharmonic phonons on the isotope effect in high- Tc oxides

Description: Anharmonic phonons are examined to study the unusual isotope effect exponents for the high-{Tc} oxides. Within a simple model of anharmonicity, the mass dependences of the electron-phonon coupling constant {lambda} and the phonon frequency determine the isotope effect exponent {alpha} as a function of coupling strength. A model in which the outer wells of a multiple-well potential deepen as the orthorhombic/low temperature tetragonal phase transition in La{sub 2-x}M{sub x}CuO{sub 4} is approach… more
Date: January 1, 1992
Creator: Crespi, V.H. & Cohen, M.L.
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Partner: UNT Libraries Government Documents Department
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Recent advances in high-temperature superconductor wire fabrication and applications development

Description: In this paper, recent advances in fabrication of HTS wires are summarized, and detailed discussion is provided for developments in near- and intermediate-term applications. Near-term applications, using presently obtainable current densities, include: liquid-nitrogen depth sensors, cryostat current leads, and magnetic bearings. Intermediate-term applications, using current densities expected to be available in the near future include fault-current limiters and short transmission lines. 25 refs.
Date: January 1, 1992
Creator: Hull, J.R. & Uherka, K.L.
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Assessment study of superconducting fault-current limiters operating at 77K

Description: The possible impact of nitrogen-cooled superconductors on the design and cost of superconducting fault-current limiters is assessed by considering the technical specifications such devices must meet and by comparing material properties of 77-K and 4-K superconductors. The main advantage of operating superconductors at 77 K is that the refrigeration operating cost is reduced by a factor of up to 25, and the refrigeration capital cost is reduced by a factor of up to 10. The heat capacity of 77 K … more
Date: January 1, 1992
Creator: Giese, R. F. & Runde, M.
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Partner: UNT Libraries Government Documents Department
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Computer simulation of scattered ion and sputtered species effects in ion beam sputter-deposition of high temperature superconducting thin films

Description: Ion beam sputter-deposition is a technique currently used by many groups to produce single and multicomponent thin films. This technique provides several advantages over other deposition methods, which include the capability for yielding higher film density, accurate stoichiometry control, and smooth surfaces. However, the relatively high kinetic energies associated with ion beam sputtering also lead to difficulties if the process is not properly controlled. Computer simulations have been perfo… more
Date: January 1, 1992
Creator: Krauss, A.R. (Argonne National Lab., IL (United States)) & Auciello, O. (Microelectronics Center of North Carolina, Research Triangle Park, NC (United States))
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Ion beam spectroscopy as a means of in-situ monitoring of thin film deposition

Description: Low energy (5--15 keV) pulsed beam Ion Scattering Spectroscopy (ISS) and Direct Recoil Spectroscopy (DRS) are surface analytical tools which possess the ability to provide a remarkably wide range of information directly relevant to the growth of multi-component semiconductor, metal and metal oxide thin films and layered structures. Ion beam methods have not been widely used for this purpose because the design of existing commercial instrumentation is unsuitable in terms of vacuum requirements, … more
Date: January 1, 1992
Creator: Krauss, A. R.; Rangaswamy, M.; Lamich, G.; Gruen, D. M. (Argonne National Lab., IL (United States)); Schultz, J. A. (Ionwerks, Inc., Houston, TX (United States)) & Schmidt, H. (Schmidt Instruments, Inc., Houston, TX (United States))
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Partner: UNT Libraries Government Documents Department
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Microstructure and properties of in-situ rf sputtered YBa sub 2 Cu sub 3 O sub 7 thin films for microwave applications

Description: The residual surface resistance of a number of films of YBa{sub 2}Cu{sub 3}O{sub 7}, prepared by off-axis sputtering onto MgO substrates, has been measured using parallel-plate resonator technique. Deposition conditions were kept constant, apart from the substrate temperature. There is no correlation between surface resistance and other important microscopic parameters, such as T{sub c} and c-axis lattice parameter. There is, however, a trend to higher R{sub s} with increasing volume fraction o… more
Date: January 1, 1992
Creator: Reagor, D. W.; Houlton, R. J.; Garzon, F. H.; Hawley, M.; Raistrick, I. D. (Los Alamos National Lab., NM (United States)) & Piza, M. E. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science)
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Fine scale mesostructures in superconducting and other materials

Description: We review experimental and theoretical literature on mesoscale features and structures in a variety of displacively transforming materials. These include twinning in martensites and the much finer scale tweed; both may have significant effects on both normal and superconducting properties. Elastic properties are particularly strongly affected. Recent x-ray neutron experiments suggest them in hi-{Tc} materials.
Date: January 1, 1992
Creator: Krumhansl, J.A.
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Oxygen ordering and strain-related morphology in YBa sub 2 Cu sub 3- x O sub 7 systems

Description: Monte Carlo simulations were performed on an anisotropic lattice gas model which represent well the interactions between oxygen atoms in YBa{sub 2}Cu{sub 3}O{sub 7} systems doped with trivalent impurity atoms M such as Fe or Al. Concentration wave amplitudes obtained from these simulations were used to calculate the diffuse X-ray scattering intensity caused by the resulting displacement field using a concentration wave/displacement wave approach, and the results are compared with X-ray and elec… more
Date: January 1, 1992
Creator: Cha, Zhi-Xiong; Zhu, Yimei & Welch, D.O.
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Partner: UNT Libraries Government Documents Department
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A comprehensive review of the XRD data of the primary and secondary phases present in the BSCCO superconductor system: Part 1, Ca-Sr-Cu oxides

Description: X-ray powder patterns for the phases in the CaO-SrO-CuO ternary system, along with the corresponding crystal structures, were obtained from the literature and from the Powder Diffraction File (PDF). Available X-ray diffraction (XRD) patterns were compared with each other and, when possible, with a simulated pattern for each phase, yielding a recommended reference pattern. The simulated powder patterns presented here deal with the phases found within the (Ca, Sr)O, (Ca,Sr){sub 2}CuO{sub 3}, (Ca,… more
Date: January 1, 1992
Creator: Reardon, B.J. (Alfred Univ., NY (United States)) & Hubbard, C.R. (Oak Ridge National Lab., TN (United States))
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Superconducting materials

Description: Our research on high temperatures superconductors has produced novel insights for the normal state properties of copper oxides that have been discovered in the last few years. Advances in materials preparation have produced singly crystal samples, and sophisticated surface cleavage techniques have unveiled truly metallic behavior in many respects. Thus, the recent confirmation of a Fermi surface in several cuprate superconductors by photoemission spectroscopy has aroused interest in experimenta… more
Date: January 1, 1992
Creator: Ruvalds, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Flux dynamics and irreversibility in YBa sub 2 Cu sub 3 O sub 7 with Y sub 2 BaCuO sub 5 inclusions and in single crystal YBa sub 2 Cu sub 3 O sub 7

Description: We have measured the ac magnetic permeability response function {mu} = {mu}{prime} + i{mu}{double prime} in melt-processed melt grown YBa{sub 2}Cu{sub 3}O{sub 7} with Y{sub 2}BaCuO{sub 5} inclusions (MPMG) and in single crystal YBa{sub 2}Cu{sub 3}O{sub 7} (SC) in applied magnetic fields up to 8 Tesla oriented either parallel or perpendicular to the crystalline c-axis. The ac response of the two samples has been mapped out as a function of temperature, frequency, ac field amplitude, dc applied f… more
Date: January 1, 1992
Creator: Fossheim, K.; Karkut, M.G.; Heill, L.K.; Slaski, M.; Sagdahl, L.T. (Norges Tekniske Hoegskole, Trondheim (Norway). Div. of Physics Selskapet for Industriell og Teknisk Forskning, Trondheim (Norway)); Vinokur, V. (Argonne National Lab., IL (United States)) et al.
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Partner: UNT Libraries Government Documents Department
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Midwest Superconductivity Consortium

Description: The Midwest Superconductivity Consortium's, MISCON, mission is to advance the science and understanding of high {Tc} superconductivity. Programmatic research focuses upon key materials-related problems: synthesis and processing; and limiting features in transport phenomena. During the past twenty-one projects produced over eighty-seven talks and seventy-two publications. Key achievements this past year expand our understanding of processing phenomena relating to crystallization and texture, met… more
Date: January 1, 1992
Creator: Liedl, G. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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NQR investigation of pressure-induced charge transfer in oxygen-deficient YBa sub 2 Cu sub 3 O sub 7-. delta. (. delta. = 0. 38)

Description: Measurements of the pressure dependence of {sup 63}Cu nuclear quadrupole frequency in YBa{sub 2}Cu{sub 3}O{sub 6.62} from ambient pressure up to 1.5 GPa at 4k have been performed. {Tc} was found to increase with pressure: d{Tc}/dp {approximately} 5 K/GPa. All observed NQR lines are linear in pressure: dln{nu}{sub Q}/dp=z. We found positive z for the empty chain sites, consistent with ionic (Cu{sup 1+}) configuration in which the atom simply feels a squeezing lattice. Planar coppers close to the… more
Date: January 1, 1992
Creator: Reyes, A. P.; Ahrens, E. T.; Hammel, P. C.; Heffner, R. H. (Los Alamos National Lab., NM (United States)) & Takigawa, M. (International Business Machines Corp., Yorktown Heights, NY (United States). Thomas J. Watson Research Center)
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Infrared absorption spectra of various doping states in cuprate superconductors

Description: Doping states in a two-dimensional three-band extended Peierls-Hubbard model was investigated within inhomogeneous Hartree-Fock and random phase approximation. They are very sensitive to small changes of interaction parameters and their distinct vibrational and optical absorption spectra can be used to identify different doping states. For electronic parameters relevant to cuprate superconductors, as intersite electron-phonon interaction strength increases, the doping state changes from a Zhang… more
Date: January 1, 1992
Creator: Yonemitsu, K.; Bishop, A.R. (Los Alamos National Lab., NM (United States)) & Lorenzana, J. (International School of Advanced Studies, Trieste (Italy))
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The variability residual stresses of thick superconductor films during orthorhombic to tetragonal transformation

Description: YBa{sub 2}Cu{sub 3}O{sub x} thick films have been deposited by spray pyrolysis of a sol-gel on 10 cm diameter polycrystalline MgO wafers. The film thickness was built up in layers of approximately 1 {mu}m thick. The in-plane residual stresses were measured by an optical interferometry (shadow moire) method as a function of film structure. In-plane residual stress maps over the area of the wafer have been obtained. The average stress of the 5 {mu}m orthorhombic phase was 0.84 GPa. As the film tr… more
Date: January 1, 1992
Creator: Wu, W.; Danyluk, S. (Illinois Univ., Chicago, IL (United States). Dept. of Civil Engineering, Mechanics, and Metallurgy); Lanagan, M.T. & Poeppel, R.B. (Argonne National Lab., IL (United States))
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Partner: UNT Libraries Government Documents Department
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A theoretical analysis of the effect of uniaxial elastic strain on the critical temperature of cuprate superconductors

Description: Factors which influence the effect of uniaxial stress and strain on the superconducting critical temperature are discussed, with emphasis on the effect of uniaxial strain on the mobile hole density of YBa[sub 2]Ci[sub 3]O[sub 7].
Date: January 1, 1992
Creator: Welch, D.O. (Brookhaven National Lab., Upton, NY (United States)) & Baetzold, R.C. (Corporate Research Laboratories, Eastman Kodak Co, Rochester, NY (United States))
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Magnetic multilayer interface anisotropy

Description: Ni/Mo and Ni/V multilayer magnetic anisotropy has been investigated as a function of Ni layer thickness, frequency and temperature. Variable frequency ferromagnetic resonance (FMR) measurements show, for the first time, significant frequency dependence associated with the multilayer magnetic anisotropy. The thickness dependence allows one to extract the interface contribution from the total anisotropy. Temperature dependent FMR (9 GHz) and room temperature magnetization indicate that strain bet… more
Date: January 1, 1992
Creator: Pechan, M. J.
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Partner: UNT Libraries Government Documents Department
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Flux pinning by heavy-ion-irradiation induced linear defects in YBa[sub 2]Cu[sub 3]O[sub 7] epitaxial films

Description: We report some transport measurements carried out to study flux pinning by heavy-ion-irradiation induced linear defects in Y[sub 1]Ba[sub 2]Cu[sub 3]O[sub 7] films. Our results show that in these in situ deposited films containing a large concentration of defects frozen-in at the time of film growth, a marginal enhancement in critical current density occurs when the density of linear defects < 5 [times] 10[sup 10]/cm[sup 2], and their diameter of the order of coherence length. This criterion is… more
Date: January 1, 1992
Creator: Budhani, R.C.; Zhu, Y. & Suenaga, M.
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Environmental test program for superconducting materials and devices

Description: The properties of YBa[sub 2]Cu[sub 3]O[sub 7-x] superconducting tapes designed and fabricated into SAFIRE-type, encapsulated, grounding links by the Ceramic Engineering Department at Clemson University were investigated (NASA Contract No. NAG-1-1127). Testing at the Savannah River Site included gamma irradiation, vibration, magnetic field, and long-term evaluation. Irradiation and vibration did not change the physical or electrical properties of the tested samples. An applied magnetic field of … more
Date: January 1, 1992
Creator: Randolph, H. & Verebelyi, D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Microstructural factors influencing critical-current densities of high-temperature superconductors

Description: Microstructural defects are the primary determining factors for the values of critical current densities in superconductors. A review is made to assess, (1) what would be the maximum achievable critical-current density in the oxide superconductors if nearly ideal pinning sites were introduced and (2) what types of pinning defects are currently introduced in these superconductors and how effective are these in pinning the vortices Only the case where the applied field is parallel to the c-axis i… more
Date: January 1, 1992
Creator: Suenaga, M.
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Ion beams as a means of deposition and in-situ characterization of thin films and thin film layered structures

Description: Ion beam-surface interactions produce many effects in thin film deposition which are similar to those encountered in plasma deposition processes. However, because of the lower pressures and higher directionality associated with the ion beam process, it is easier to avoid some sources of film contamination and to provide better control of ion energies and fluxes. Additional effects occur in the ion beam process because of the relatively small degree of thermalization resulting from gas phase col… more
Date: January 1, 1992
Creator: Krauss, A. R.; Rangaswamy, M.; Gruen, D. M. (Argonne National Lab., IL (United States)); Lin, Y. P. (Argonne National Lab., IL (United States) Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science); Schultz, J. A. (Ionwerks, Inc., Houston, TX (United States)); Schmidt, H. (Schmidt Instruments, Inc., Houston, TX (United States)) et al.
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