Superconducting and Microstructural Properties of Shock-Compacted High-TC Oxide Powders.

摘要

Shock compacted specimens of YBa2)Cu3O7(minus)(delta)) and HoBa2Cu3O7(minus)(delta)) high-Tc oxide powder mixed with 30% (vol) Ag powder have been prepared using the LLNL two-stage light-gas gun in the 30--200 kbar range. We report the experimental technique and results of an investigation of the microstructural and superconducting properties of these composite specimens. Measurements of magnetic susceptibility show that bulk superconductivity is retained in this pressure range with Tc onsets unchanged at 91 K. Oxide particle size is reduced with increasing shock pressure. Complete resistive transitions are observed at Tc) = 90 K only after subsequent heat treatment in oxygen. A transport critical current density of 320 A/sq m at 77 K in zero field was measured for a specimen shocked to 167 kbar, suggesting that the shock process might introduce defects which serve to pin magnetic flux vortices and thereby increase Jc. 9 refs., 4 figs.