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  • 1
    Electronic Resource
    Electronic Resource
    Dispersive phonon imaging of InAs (1995)
    Springer
    The European physical journal 97 (1995), S. 413-424 
    Details
    ISSN: 1434-6036
    Keywords: 66.70.+f ; 63.20.Dj
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The phonon-focusing patterns of ballistic phonons in InAs are measured in the frequency range 0.1 to 1 THz, in an effort to test the global validity of lattice dynamics models for this semiconductor. Phonon caustic patterns depend sensitively on the shapes of constant frequency surfaces. Several tunnel-junction detectors with sensitivity onsets in this frequency range are used to measure dispersive shifts in the phonon caustics. The measured caustic positions are compared to those predicted by rigid-ion and bond-charge models. Similar to the case of InSb studied by Hebboul and Wolfe, a 6-parameter bond-charge model (BCM)-with force constants determined by neutron, X-ray, and Raman scattering-reproduces the phonon-imaging data both qualitatively and quantitatively. Comparisons of the focusing patterns with an 11-parameter rigid-ion model (RIM) do not show good agreement. New structures are predicted in the phononfocusing patterns at frequencies above about 1.2 THz — presently outside our experimental range-which are highly sensitive to the theoretical modeling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01317224
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    Paper (German National Licenses)
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  • 2
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    Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3O(x) bulk material (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Measurements are reported of the millimeter-wave surface resistance of grain-aligned YBa2Cu3O(x) bulk material grown by a liquid-phase process. The measurements were performed by replacing the endplate of a TE(011) cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. For the parallel configuration, the surface resistance at 77 K and 80 GHz is given. For a very well-aligned sample with a very low density of Y2BaCuO(y) precipitates, measured in the perpendicular configuration, the transition width (10-90 percent) is about 2 K and the surface resistance is derived at 88 K. The effect of microstructure on surface resistance is discussed.
    Keywords: SOLID-STATE PHYSICS
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Dependence of millimeter wave surface resistance on the deposition parameters of laser ablated YBa2Cu3O(x) thin films (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Measurements of millimeter-wave surface resistance versus temperature have been performed for YBa2Cu3O(x) thin films on 100 line-type SrTiO(3) substrates using a TE(011) cylindrical copper cavity at 80 GHz. The 0.6-micron thick films were grown at several deposition temperatures in the range 690 C to 810 C by means of a pulsed excimer laser ablation technique. A surface resistance minimum (60 milliohm at 77 K) near 770 C is shown to correlate with a minimum in c-axis lattice parameter (11.72 A). The highest value of Tc also occurs near this temperature. The surface resistance of films deposited at 790 C on 110 line-type LaAlO3 subtrates is lower, reaching 8 milliohm at 98 GHz and 80 K, demonstrating the influence of substate material on film quality.
    Keywords: SOLID-STATE PHYSICS
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    NASA TECHNICAL REPORTS
  • 4
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    Electron beam flash evaporation for YBaCuO and BiCaSrCuO thin films (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: An electron beam flash evaporation technique is described which reproduces the stoichiometry of superconducting YBa(2)Cu(3)O(x) (123), Bi(2)CaSr(2)Cu(2)O(y) (2122), and Bi(2)Ca(2)Sr(2)Cu(3)O(z) (2223) source powders. Films of each material deposited with this technique exhibit zero resistance temperatures of 78 K or above when furnace annealed; 75 K zero temperatures are obtained for 123 films in situ annealed with atomic oxygen at 775 C. Transport critical current densities are 10,000 A/sq cm in 25-micron stripes patterned from 123 films, and 60,000 A/sq cm in 1-mm stripes of 2122 and 2223 films using a 1-microV/mm measurement criteria. Typical normal state resistivities are 700 micro-ohm cm for 2122 and 2223 films and 5 micro-ohm cm for 123 films. The 2122 films are highly textured with the c axis normal to the substrate. All results are for films deposited on MgO.
    Keywords: SOLID-STATE PHYSICS
    Type: Journal of Applied Physics (ISSN 0021-8979); 66; 4903-490
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    NASA TECHNICAL REPORTS
  • 5
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    Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3O(x) bulk material (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Measurements of the millimeter wave surface resistance of grain-aligned YBa2Cu3O(x) bulk material grown by a liquid phase process are reported. The measurements were performed by replacing the endplate of a TE011 cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. It is shown that, for the parallel configuration, the surface resistance at 77 K and 80 GHz is typically near 100 milliohms. For a very well-aligned sample with a very low density of Y2BaCuO(y) precipitates, measured in the perpendicular configuration, the transition width (10-90 percent) is about 2 K, and the surface resistance is less than 50 milliohms at 88 K. The effect of microstructure on surface resistance is discussed.
    Keywords: SOLID-STATE PHYSICS
    Type: Journal of Applied Physics (ISSN 0021-8979); 69; 874-879
    Format: text
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