Improvement of the shock-wave-induced resistance-temperature signature for superconducting Y-Ba-Cu-O by silver additions

Abstract

It is now well established that explosive fabrication and shock wave compression produces residual degradation of superconductivity in Y-Ba-Cu-O and other high T{sub c} oxide superconductors. This degradation manifests itself most prominently in alterations in the resistance-temperature (R-T) signatures which are characterized mainly by a semiconducting normal-state behavior and a broadening of the superconducting transition with increasing peak shock pressure. Transmission electron microscope observations have shown shock-induced microstructural changes including clusters or precipitate-like defects which increase with increasing shock pressure. These features are also similar in some respects to observations of radiation-induced variations in the R-T signatures of Y-B-Cu-O. Contrary to these observations of degraded superconductivity, silver additions to oxide ceramics have generally improved superconducting properties. Here we report the effects of silver doping on the shock-wave degradation of R-T signatures in the high - T{sub c} superconductor system Y-Ba-Cu-O. The suppression of normal-state semiconducting behavior and superconducting transition broadening in silver-doped Y-Ba-Cu-O provides some encouragement for the production of explosively-fabricated, bulk superconducting prototype having a zero resistance T{sub c} intercept above liquid nitrogen temperature ({gt}77K). This paper reports on silver-doped Y-Ba-Cu-O superconducting, sintered bars made by solid-state reaction of the constituent oxides Y{sub 2}O{sub 3}, Cu and BaO (ormore » Ba(OH){sub 2}) with approximately 25 wt% Ag.« less