Bulk-wave characterization of high-T sub c superconductors. Final report, 1 Apr 88-31 Dec 90
The objective of this research project were to characterize high Tc superconductors and heavy Fermion superconductors with longitudinal and transverse ultrasonic waves and with surface acoustic waves. Sound attenuation measurements in sintered and sinter forged Y1Ba2Cu3O7 exhibited three maxima which appear to be produced by relaxation processes with activation energies in the range of 450 K, 1100 K, and 650 K. The high activation energy is associated with the middle attenuation maximum which appears to be isotropic and is the only one present in another 123 isomorph Er1Ba2Cu3O7. This is the energy of the virtual excitations proposed in some theoretical models that is required for the appearance of high Tc superconductivity. Sound measurements in a Tl based superconducting compound exhibited a frequency independent maximum at the superconducting transition. This appears to be the first attenuation effect that is directly produced by the superconducting transition itself. Such a peak has also been observed in Y1Ba2Cu3O7 after careful analysis of the data. These may be produced by interactions with superconducting fluctuations, enhanced by the two dimensional nature of the systems.
- Research Organization:
- Wisconsin Univ., Milwaukee, WI (United States). Dept. of Physics
- OSTI ID:
- 5480894
- Report Number(s):
- AD-A-234649/2/XAB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACOUSTIC TESTING
ACTIVATION ENERGY
ALKALINE EARTH METAL COMPOUNDS
ATTENUATION
BARIUM COMPOUNDS
BARIUM OXIDES
BISMUTH COMPOUNDS
BISMUTH OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ENERGY
ERBIUM COMPOUNDS
ERBIUM OXIDES
HIGH-TC SUPERCONDUCTORS
MATERIALS TESTING
NONDESTRUCTIVE TESTING
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
RELAXATION
RESEARCH PROGRAMS
SUPERCONDUCTIVITY
SUPERCONDUCTORS
TESTING
THALLIUM COMPOUNDS
THALLIUM OXIDES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
ULTRASONIC TESTING
VARIATIONS
WAVE PROPAGATION
YTTRIUM COMPOUNDS
YTTRIUM OXIDES