Anelastic properties of single-phaseYBa2Cu3O7−δ

The anelastic properties of 90-K single-phase $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$ with $T_c=89\mathrm{}$ K (zero-resistance point) were investigated at about 3 kHz. Internal-friction (IF) peaks of relaxation type were found at about 30, 50, and 80 K. These were enhanced with increasing oxygen deficiency and showed no strain amplitude dependence. The anomalous hardening below $T_c$ reported in ultrasonic studies on this same material was also observed but is suggested to be due to modulus defects associated with the IF peaks.