Ultrasonic velocity anomalies in superconducting sinter-forged YBa₂Cu₃O_7-b

Authors

Z. Zhao, Northwestern University
Shireen Adenwalla, University of Nebraska-LincolnFollow
A. Moreau, Northwestern University
J. B. Ketterson, Northwestern UniversityFollow
Q. Robinson, Northwestern University
D. L. Johnson, Northwestern University
S.-J. Hwu, Northwestern University
K. R. Poeppelmeier, Northwestern University
M-F. Xu, University of Wisconsin - Milwaukee
Y. Hong, University of Wisconsin - Milwaukee
R. F. Wiegert, University of Wisconsin - Milwaukee
M. Levy, University of Wisconsin - Milwaukee
Bimal K. Sarma, University of Wisconsin - Milwaukee

Date of this Version

1989

Citation

PHYSICAL REVIEW B VOLUME 39, NUMBER 1, 1 JANUARY 1989

Comments

Copyright 1989 The American Physical Society

Abstract

The velocity of ultrasound was measured on sinter-forged polycrystalline YBa₂Cu₃O_7-b samples with a superconducting transition temperature of 91 K. The forging process results in crystallites which are preferentially aligned with their c axis aligned parallel to the forging axis as confirmed from optical and x-ray measurements. Sound-velocity measurements show that the material is elastically anisotropic. The temperature dependence of the sound velocity shows distinct anomalies. For propagation parallel to the forging axis, both longitudinal and shear waves displayed a thermal hysteresis between 65 and 260 K; however the longitudinal sound velocity with q in the basal plane showed a much smaller thermal hysteresis. No effect of a magnetic field was observed on sweeping the magnetic field to 7.2 T at temperatures of 4 and 86 K.