Shock wave induced changes in superconductivity in YBa2Cu3O7−δ

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Abstract
Shock wave loading produced significant changes in superconductivity in sintered YBa2Cu3O7−δ causing a broad transition with Tc(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 Tc 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.