MECHANISMS FOR THERMAL-DEGRADATION OF YBA2CU3O7-X

An analytical approach is used to describe degradation thermodynamics and kinetics of YBa2Cu3O7-x. Using quazi-chemical reactions allowing f or the formation of charged copper species (Cu'(Cu)) and different oxy gen vacancies (VO.., V-O(.), V-O(X)), we derive analytical expressions for the dependence of x on temperature and oxygen pressure. Our resul ts demonstrate that the kinetics of oxygen loss by the high-T-c phase are described by equations of chain nucleation.