Heterogeneous equilibrium between YBa2Cu3O7-δ and oxygen gas studied by a kinetic approach

Abstract

The kinetic behaviour of the YBa₂CU₃O_7-δ system has been investigated via a ‘T-jump’ experiment. This is realized by a displacement of the thermodynamic system from equilibrium by a temperature jump. The subsequent relaxation process is followed via resistivity measurements. Kinetic models have been formulated by assuming the formation of singly and doubly charged oxygen vacancies and according to the kinetic law of mass action. A good agreement between the theoretical model and the experimental data has been achieved in the case of singly charged oxygen vacancies in the temperature range 400–800°C. At equilibrium the YBa₂Cu₃O_7-δ conductivity is found to be a function of the oxygen partial pressure, P, according to σ∝Pⁿ with ¼<n<½.