Shock wave induced changes in superconductivity in YBa2Cu3O7−δ

Abstract

Shock wave loading produced significant changes in superconductivity in sintered YBa₂Cu₃O_7−δ causing a broad transition with T_c(R=0)∼40 K. The normal‐state resistivity increased by 20–50× with the ρ‐T curve exhibiting a semiconducting behavior. Comparative thermogravimetric analysis, however, indicated no loss of oxygen (δ∼0.1) in the shock‐loaded sample, and x‐ray powder diffraction analysis showed no major changes except for slight line broadening. The observed semiconductive behavior and degredation in superconductivity is thus attributed to a rather subtle disturbance in crystal structure, the nature of which is not clearly understood at present. The lack of sufficient recovery in T_c by post‐shock oxygen processing at temperatures as high as 750 °C and subsequent cooling implies that the atomic‐scale disturbance may not necessarily be related to a simple oxygen disorder. Such defects, if controlled properly, may be advantageously turned into desirable flux‐pinning sites for improved critical currents.