CREEP AND DIFFUSION IN HIGH-T(C) SUPERCONDUCTORS

Data from steady-state creep and tracer diffusion tests are presented for the high-T(c) superconductors YBa2Cu3Ox and Bi2Sr1.7CaCu2Oy. Both compounds exhibit oxygen nonstoichiometry and possess orthorhombic, la yered perovskite crystal structures in which Cu occupies the B sites a nd the other cations occupy the A sites. For each, the A-site cations diffuse most slowly. For every species that has been measured, diffusi on is much faster in the ab-plane than in the c-direction. At low stre sses, both superconductors deform by diffusional creep with the rate-c ontrolling species being a A-site cation in YBa2Cu3Ox.