Surface exchange of oxygen in mixed conducting perovskite oxides

Exchange data from a range of mixed conducting perovskites is reviewed. It is noted that the surface exchange coefficient and the self-diffusion coefficient are related, which in turn implies that the vacancy concentration of the material plays an important role in determining the magnitude of the former. On the assumption that the surface vacancy is the site at which exchange takes place, an expression for the surface exchange coefficient is derived in terms of bulk atomistic parameters.