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Microwave Cavity Test for Superconductivity

Description: The first part of this paper describes the Meissner effect in superconductors which serves as the most definitive evidence for superconductivity. It is shown that the microwave perturbation technique may be used to demonstrate this effect. By measuring the changes of resonant frequency and inverse quality factor Q of a microwave cavity with a small volume of sample loading, the Meissner effect can be shown by using the Slater perturbation equation. The experimental system is described with deta… more
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Date: December 2001
Creator: Tang, Shan
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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A Constructive Method for Finding Critical Point of the Ginzburg-Landau Energy Functional

Description: In this work I present a constructive method for finding critical points of the Ginzburg-Landau energy functional using the method of Sobolev gradients. I give a description of the construction of the Sobolev gradient and obtain convergence results for continuous steepest descent with this gradient. I study the Ginzburg-Landau functional with magnetic field and the Ginzburg-Landau functional without magnetic field. I then present the numerical results I obtained by using steepest descent with t… more
Date: August 2008
Creator: Kazemi, Parimah
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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High-Temperature Superconductivity in Perspective

Description: This is the second of two OTA assessments on the subject of high-temperature superconductivity (HTS). As the title suggests, this study attempts to put HTS in perspective, both in terms of competing technologies (e.g., the more mature low-temperature superconductors), and in terms of the many technical and economic problems that must be overcome before HTS can be widely used.
Date: April 1990
Creator: United States. Congress. Office of Technology Assessment.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Commercializing high-temperature superconductivity

Description: Since the discovery of high-temperature superconductivity (HTS), research laboratories around the world have pushed the temperature limits steadily upward, opening the way to commercial applications with potentially revolutionary impacts. The scientific race is becoming a commercial race, one featuring U.S. and Japanese companies, and one that the United States could lose. Indeed, American firms may already be falling behind in commercializing the technology of superconductivity.
Date: June 1988
Creator: United States. Congress. Office of Technology Assessment.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The Effect of Shock Stress and Field Strength on Shock-Induced Depoling of Normally Poled PZT 95/5

Description: Shock-induced depoling of the ferroelectric ceramic PZT 95/5 is utilized in a number of pulsed power devices. Several experimental and theoretical efforts are in progress in order to improve numerical simulations of these devices. In this study we have examined the shock response of normally poled PZT 95/5 under uniaxial strain conditions. On each experiment the current produced in an external circuit and the transmitted waveform at a window interface were recorded. The peak electrical field ge… more
Date: September 1, 1999
Creator: CHHABILDAS,LALIT C.; FURNISH,MICHAEL D.; MONTGOMERY,STEPHEN T. & SETCHELL,ROBERT E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Novel structural phenomena at the maximum T{sub c} in 123 and HgBa{sub 2}CuO{sub 4+{delta}} superconductors : evidence for a structural response that competes with superconductivity.

Description: Structural distortions that compete with superconductivity have been investigated in two systems where oxygen content can be used to vary the doping continuously from the under doped state, through the maximum T{sub c} into the over doped state. In the 123 system, (La{sub 1{minus}x}Ca{sub x})(Ba{sub 1.75{minus}x}La{sub 0.25+x})Cu{sub 3}O{sub 7+{delta}}, the buckling of the CuO{sub 2} planes goes through a maximum at the maximum T{sub c}. In HgBa{sub 2}CuO{sub 4+{delta}}, where buckling of the C… more
Date: June 3, 1998
Creator: Jorgensen, J. D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Ordering in classical Coulombic systems.

Description: The author discusses the properties of classical Coulombic matter at low temperatures. It has been well known for some time [1,2] that infinite Coulombic matter will crystallize in body-centered cubic form when the quantity {Lambda} (the dimensionless ratio of the average two-particle Coulomb energy to the kinetic energy per particle) is larger than {approximately}175. But the systems of such particles that have been produced in the laboratory in ion traps, or ion beams, are finite with surface… more
Date: January 22, 1998
Creator: Schiffer, J. P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Decay out of the yrast superdeformed band in {sup 191}Hg.

Description: The excitation energies and spins of the yrast superdeformed band in {sup 191}Hg have been determined by analyzing the quasicontinuum spectrum connecting the superdeformed and normal-deformed states. The results from this analysis, combined with that given by one-step decay lines, give confident assignments of the spins and energies of the yrast superdeformed band in {sup 191}Hg.
Date: March 24, 1999
Creator: Sien, S.; Reiter, P.; Khoo, T.; Lauritsen, T.; Carpenter, M. P.; Ahmad, I. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Superconducting and normal state magnetic properties of RNi{sub 2}B{sub 2}C single crystals

Description: The authors` studies of the magnetic properties of RNi{sub 2}B{sub 2}C single crystals (R = Y, Gd-Tm, Lu) are reviewed. Of particular interest are the ordered magnetic structures when R is a magnetic rare earth atom, the interaction between magnetism and superconductivity, the influence of crystalline electric fields of the magnetic rare earth ions on these behaviors, and the magnetic character of the Ni sublattice.
Date: October 1995
Creator: Johnston, D. C.; Borsa, F. & Cho, B. K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Energy Technology Division research summary - 1999.

Description: The Energy Technology Division provides materials and engineering technology support to a wide range of programs important to the US Department of Energy. As shown on the preceding page, the Division is organized into ten sections, five with concentrations in the materials area and five in engineering technology. Materials expertise includes fabrication, mechanical properties, corrosion, friction and lubrication, and irradiation effects. Our major engineering strengths are in heat and mass flow… more
Date: March 31, 1999
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Proceedings of the fourth international conference and exhibition: World Congress on superconductivity. Volume 2

Description: This document contains papers presented at the 4th International Conference Exhibition: World Congress on Superconductivity held at the Marriott Orlando World Center, Orlando, Florida, June 27--July 1, 1994. This conference encompassed research, technology, applications, funding, political, and social aspects of superconductivity. Specifically, the areas of research, technology, and development covered during the conference included high-temperature materials, thin films, C-60 based superconduc… more
Date: December 31, 1994
Creator: Krishen, K. & Burnham, C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Anisotropic superconducting and normal state magnetic properties of single crystals of RNi*2*B*2*C compounds (R = Y, Gd, Dy, Ho, Er, and Tm)

Description: The interaction of superconductivity with magnetism has been one of the most interesting and important phenomena in solid state physics since the 1950`s when small amounts of magnetic impurities were incorporated in superconductors. The discovery of the magnetic superconductors RNi{sub 2}B{sub 2}C (R = rare earth, Y) offers a new system to study this interaction. The wide ranges of superconducting transition (T{sub c}) and antiferromagnetic (AF) ordering temperatures (T{sub N}) (0 K {le} T{sub … more
Date: November 1, 1995
Creator: Cho, B.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Magnetic profile in Nb/Si superconducting multilayers.

Description: Polarized neutron reflectivity measurements were conducted on [Nb(100{angstrom})/Si(15{angstrom})]xN superconducting multilayers with a T{sub c} {approximately} 7.5 K. Scope of the experiment was to verify the existence of arrays of vortices parallel to the surface above the critical field H{sub cl} = 400 Oe when a magnetic field was applied parallel to the film plane. Measurements at 1.6 K and 700 Oe in the zero-field-cooled condition, and at 30 Oe after field cooling, indicated that reflectiv… more
Date: February 4, 1999
Creator: Yusuf, S. M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Theory of the equation of state of hot dense matter

Description: Ab initio molecular dynamics calculations are adapted to treat dense plasmas for temperatures exceeding the electronic Fermi temperature. Extended electronic states are obtained in a plane wave basis by using pseudopotentials for the ion cores in the local density approximation to density functional theory. The method reduces to conventional first principles molecular dynamics at low temperatures with the expected high level of accuracy. The occurrence of thermally excited ion cores at high tem… more
Date: July 23, 1999
Creator: Barbee, T W; Surh, M & Yang, L H
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Proceedings of the fourth international conference and exhibition: World Congress on superconductivity. Volume 1

Description: The goals of the World Congress on Superconductivity (WCS) have been to establish and foster the development and commercial application of superconductivity technology on a global scale by providing a non-adversarial, non-advocacy forum where scientists, engineers, businessmen and government personnel can freely exchange information and ideas on recent developments and directions for the future of superconductive research. Sessions were held on: accelerator technology, power and energy, persist… more
Date: December 31, 1994
Creator: Krishen, K. & Burnham, C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Imprinted spiral structures as neutron polarizers.

Description: Neutron diffraction from magnetic spiral structures is governed by strong selection rules for the polarization of the outgoing beam. When the sample is entirely of one chirality--for instance a right handed spiral--the neutrons diffracted by some Bragg reflections are fully polarized. While the scattering theory has been formulated long ago, attempts to controllably modify the population of left handed and right handed spiral domains in natural magnetic structures (which for instance occur in s… more
Date: October 7, 1998
Creator: Lohstroh, W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Shock-induced changes in HgO powder

Description: Powder compacts of HgO were subjected to explosively-generated shock-wave loading in Sandia Bear fixtures and recovered for analysis. Although XRD powder spectra show only the orthorhombic form of HgO in both the as-received and recovered samples, XRD line profiles and TEM indicate up to an order of magnitude increase in crystallite size. Magnetic data reveal a superconducting transition below 4.2 K that is attributed to metallic {alpha}-Hg formed by a partial, shock-induced decomposition of th… more
Date: October 1995
Creator: Venturini, E. L.; Newcomer, P. P.; Morosin, B.; Holman, G. T.; Dunn, R. G. & Graham, R. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Techniques for inelastic x-ray scattering with {mu}eV resolution.

Description: We introduce a novel type of spectrometer that provides a {micro}eV bandpass together with a tunability over a few meV. The technique relies on nuclear resonant scattering (Moessbauer effect) of synchrotrons radiation at the 14.4-keV resonance of {sup 57}Fe. Energy tuning is achieved by the Doppler effect in high speed rotary motion. The resonantly scattered monochromatic radiation is extracted by a polarization filtering technique or by spatial separation due to the ''nuclear lighthouse effect… more
Date: October 23, 1998
Creator: Rohlsberger, R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Superconducting nanostructured materials.

Description: Within the last year it has been realized that the remarkable properties of superconducting thin films containing a periodic array of defects (such as sub-micron sized holes) offer a new route for developing a novel superconducting materials based on precise control of microstructure by modern photolithography. A superconductor is a material which, when cooled below a certain temperature, loses all resistance to electricity. This means that superconducting materials can carry large electrical c… more
Date: July 13, 1998
Creator: Metlushko, V.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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