Diffusion of OH− during hydration of YBa2Cu3O7-y by exposing to water vapor

Abstract

The hydration of YBa2Cu3O7-y in water vapor was investigated at various values of y and at two different PH2O by measuring the weight of the specimen. The reaction was relatively insensitive to the values of y and was extensive in the water vapor pressure of 2.7 kPa at room temperature and 140 °C. This was due to the decomposition of YBa2Cu3O7-y by reacting with H2O. The weight gain was also detected in the water vapor pressure of 270 Pa. The weight gain under lower water vapor pressure was supposed to be controlled by diffusion of OH− in YBa2Cu3O7-y. The diffusion coefficient calculated from the measurement was compared favorably with the oxygen diffusion coefficient.