Non-stoichiometry of YBa₂Cu₃O₇-d Observed by Repeated Temperature Scanning

Abstract

Repeated temperature scanning method was applied to observe non-stoichiometry of YBa₂Cu₃O₇-d, and interesting results were obtained. Two simultaneously occurring processes were separately observed in mass change; one is a fast process and the other is slow, so that their responses to the temperature change are quite different from each other. The fast process follows the cyclic temperature change, but the slow process is observed to be a gradual mass change. Kinetic behaviors of these two processes are also made clear by plotting the mass vs. the temperature. Furthermore, a hysteresis loop was observed in the plot of the mass vs. the temperature in a high temperature range presumably due to the third process, and it depends on the heating and cooling rates.