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in subjects: "Superconductors"  
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Positron lifetimes in solids from first principles calculations

Description: We present a first principles method for calculating positron lifetimes in solids, based on self-consistent calculations using the Linear Muffin-Tin Orbital method. Local density approximations are used for both electron-electron and electron-positron interactions. Results are presented for a variety of elemental metals and vacancies to demonstrate the reliability of this approach. Theoretical calculations of positron lifetimes can be used to interpret experimental data. As an examples of this,… more
Date: August 7, 1991
Creator: Sterne, P. A.; O'Brien, J. C.; Howell, R. H. & Kaiser, J. H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Improvements in the weldability of a superconductor sheath material

Description: This paper investigates the effects of chemistry and heat treatment variation on the 4-K tensile properties of A-286, a candidate sheath material for force-cooled superconductors. Currently, full use of A-286 and similar superalloys is limited by the observed low yield and ultimate tensile strengths in the welded and aged condition. The low strength is shown to be associated with the formation of precipitate-free zones as a result of alloying-element segregation during weld pool solidification.… more
Date: August 7, 1985
Creator: Summers, L.T. & Morris, J.W. Jr.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Design and Development of a 100 MVA HTS Generator for Commercial Entry

Description: In 2002, General Electric and the US Department of Energy (DOE) entered into a cooperative agreement for the development of a commercialized 100 MVA generator using high temperature superconductors (HTS) in the field winding. The intent of the program was to: (1) identify and develop technologies that would be needed for such a generator; (2) develop conceptual designs for generators with ratings of 100 MVA and higher using HTS technology; (3) perform proof of concept tests at the 1.5 MW level … more
Date: June 7, 2007
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A Method to Increase Current Density in a Mono Element Internal Tin Processed Superconductor Utilizing Zr Oxide to Refine Grain Size

Description: The effect of Oxygen on (Nb1Zr)3Sn multifilament conductors manufactured by the Mono Element Internal Tin (MEIT) process was explored to improve the current density by refining the grain size. This followed work first done by General Electric on the Nb3Sn tape process. Techniques to fabricate the more difficult Nb1Zr composites are described and allowed fabrication of long lengths of .254 mm diameter wire from an 88.9 mm diameter billet. Oxygen was incorporated through the use of SnO2 mixed wit… more
Date: April 7, 2008
Creator: Bruce A. Zeitlin, Eric Gregory
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Gas cooled leads. Part 1, Theoretical study

Description: The intent of this paper is to cover as completely as possible and in sufficient detail the topics relevant to lead design. The first part identifies the problems associated with lead design, states the mathematical formulation, and shows the results of numerical and analytical solutions. The second part presents the results of a parametric study whose object is to determine the best choice for cooling method, material, and geometry. These findings axe applied in a third part to the design of h… more
Date: December 7, 1993
Creator: Shutt, R. P.; Rehak, M. L. & Hornik, K. E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Processing method for superconducting ceramics

Description: A process for preparing a superconducting ceramic and particularly YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}, where {delta} is in the order of about 0.1--0.4, is carried out using a polymeric binder which decomposes below its ignition point to reduce carbon residue between the grains of the sintered ceramic and a nonhydroxylic organic solvent to limit the problems with water or certain alcohols on the ceramic composition.
Date: May 7, 1990
Creator: Bloom, I. D.; Poeppel, R. B. & Flandermeyer, B. K.
Item Type: Refine your search to only Patent
Partner: UNT Libraries Government Documents Department
open access

High resolution angle-resolved photoemission study of hightemperature superconductors: charge-ordering, bilayer splitting andelectron-phonon coupling

Description: The latest development of angle-resolved photoemission spectroscopy (ARPES) technique has seen extremely high energy resolution and momentum resolution, as well as multiple angle detection. These advancements have led to new findings through efficient Fermi surface mapping, fine electronic structure resolving, and direct determination of electron self-energy. In this paper, we will highlight some recent high resolution ARPES work on high temperature superconductors. These include: (1) charge-or… more
Date: July 7, 2003
Creator: Zhou, Xingjiang; Hussain, Zahid & Shen, Zhi-xun
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Neutron diffraction from HoNi{sub 2}B{sub 2}C. Version 1

Description: RENi{sub 2}B{sub 2}C (RE=Rare Earth) are quaternary compounds which exhibit a considerable degree of interaction between their superconducting and magnetic properties. The Ho variant is found to become superconducting at {Tc} = 9 K, but anomalous behaviour is observed in the low field magnetic properties at T<7 K (increasing susceptibility with decreasing temperature); at temperatures less than 5.6 K more conventional behaviour is regained. Neutron diffraction measurements demonstrate that at l… more
Date: February 7, 1994
Creator: Tomy, C. V.; Chang, L. J.; Paul, D. M.; Andersen, N. H. & Yethiraj, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Fabrication of wide-IF 200–300GHz superconductor–insulator–superconductor mixers with suspended metal beam leads formed on silicon-on-insulator

Description: This article reports on a fabrication process that uses silicon-oninsulator (SOI) substrates and micromachining techniques to form wide-IF superconductor–insulator–superconductor (SIS) mixer devices that have suspended metal beam leads for rf grounding. Aside from a description of the fabrication process, electrical measurements of these Nb/Al–AlNₓ /Nb trilayer devices will also be presented.
Date: October 7, 2004
Creator: Kaul, Anupama; Bumble, Bruce; Lee, Karen A.; LeDuc, Henry G.; Rice, Frank & Zmuidzinas, Jonas
Item Type: Refine your search to only Article
Partner: UNT College of Engineering
open access

High-Pressure Multi-Mbar Conductivity Experiments on Hydrogen: The Quest for Solid Metallic Hydrogen

Description: Ultra-dense hydrogen has long been the subject of intense experimental and theoretical research due to the fascinating physics which arises from this supposedly simple system. The properties of ultra-dense hydrogen also have important implications for planetary physics, since the interiors of the giant planets Jupiter and Saturn are believed to consist of cores of dense, metallic hydrogen. Finally, ultra-dense hydrogen is of direct programmatic interest, and multiple-shock compression experimen… more
Date: February 7, 2007
Creator: Jackson, D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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On the Theory of Critical Currents and Flux Flow in Superconductors by the Mechanism of Plastic Deformation of the Flux-Line Lattice.

Description: In this paper I will discuss how the nature of the stress state in the flux-line lattice (FLL) of superconductors arises from the distribution, density, geometry, and strength of pinning centers. Under certain conditions this stress causes the onset of plastic deformation in the FLL for values of the current density below that required for flux-flow by general depinning. I will describe an analytic framework, based on a theory of plasticity of the FLL, which describes the flux-flow characterist… more
Date: July 7, 1999
Creator: Welch, D. O.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Absolute measurements of the high-frequency magnetic dynamics in high-{Tc} superconductors

Description: The authors review recent measurements of the high-frequency dynamic magnetic susceptibility in the high-T{sub c} superconducting systems La{sub 2{minus}x}Sr{sub x}CuO{sub 4} and YBa{sub 2}Cu{sub 3}O{sub 6+x}. Experiments were performed using the chopper spectrometers HET and MARI at the ISIS spallation source. The authors have placed their measurements on an absolute intensity scale, this allows systematic trends to be seen and comparisons with theory to be made. They find that the insulating … more
Date: August 7, 1997
Creator: Hayden, S. M.; Aeppli, G.; Dai, P.; Mook, H. A.; Perring, T. G.; Cheong, S. W. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Structural and electrical properties of biaxially textured YBa{sub 2}Cu{sub 3}O{sub 7-x} thin films on buffered Ni-based alloy substrates.

Description: Oxide high-T{sub c} superconducting wires and tapes with high critical current density (J{sub c}) are essential in future electrical power applications. Recently, YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} (YBCO) thin films grown on Ni-based alloy tapes have attracted intense interest because of their promise for these applications. In order to achieve high J{sub c}, buffer layers are necessary for fabricating biaxially aligned YBCO thin films. In our studies, yttria-stabilized zirconia (YSZ) layers w… more
Date: December 7, 2000
Creator: Li, M.; Ma, B.; Jee, Y. A.; Fisher, B. L. & Balachandran, U.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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