ELASTIC ANOMALIES IN Y-123/Ag COMPOSITE MATERIALS

Abstract

With a view to understand the influence of Ag on the microstructure of Y-123 samples, and hence its microstructural impact on the low temperature elastic behavior, a series of Y-123/Ag superconducting composite materials have been prepared by the Sol-Gel method. After characterization, ultrasonic velocity and attenuation measurements were undertaken over a temperature range of 80–300 K, using the pulse transmission technique. In contrast to the normal solids, the ultrasonic velocity of all the samples of the present investigation, in the temperature range of 80–300 K, are found to exhibit elastic anomalies signaling the presence of lattice instabilities. It has also been observed that most of the samples are found to exhibit longitudinal attenuation peaks at temperatures 250 K, 170 K and 100 K. A qualitative explanation for the observed phenomena of both lattice softening and attenuation is given on the basis of microstructure and relaxation.