Degradation in Bi-Sr-Ca-Cu-O Thin Films Exposed to Water

Abstract

A study of Bi-Sr-Ca-Cu-O thin films soaked in water demonstrated that film superconductivity was degraded by exposure to water. ICP analysis showed that Sr and Ca, but no Bi and Cu, largely dissolved. EPMA analysis indicated that dissolution took place mostly in nonsuperconducting grains. By contrast, XRD patterns showed no significant change after soaking. That is, superconducting grains were indeed stable, but nonsuperconducting grains were notably degraded in polycrystalline films, with a consequent lowering of overall superconductivity.