Degradation of Y–Ba–Cu–O in a high-humidity environment

Changes in ac susceptibility of the high-T_c superconductor Y–Ba–Cu–O have been used to investigate the degradation of this material in the presence of high humidity. It is found that the fraction of YBa₂Cu₃O₇ in a sample decreases exponentially with time when the sample is kept at 98% relative humidity and 20 °C. The time constant is approximately 22 days.