On the Chemical Diffusion Coefficient of H2O in AB(1-x)B'Xo(3-X/2)-type Perovskites

Abstract

In proton-conducting perovskites, oxygen ions and protons make a diffusion pair for a chemical diffusion and thus lead to the transport of H2O under its chemical potential gradient. The present manuscript develops relationships between the chemical diffusion coefficient of H2O and the diffusion coefficients of protons and oxygen vacancies with an emphasis on the thermodynamic behavior of the oxygen vacancies. Depending on the degree of hydration X, two different expressions of the chemical diffusion coefficient were obtained: as X 0, and as X 1.