The basic atomic processes of corrosion II. Defect structures and cation transport in transition-metal oxides

Abstract

Abstract An earlier discussion of the fundamental processes controlling corrosion is extended with an account of cation transport in cubic divalent transition-metal oxides. The results of calculations of the energies of defect interaction and activation are given. Our results show that the common interpretations of the experimental data on these materials are inadequate. In particular, we suggest that vacancy clustering in these oxides is far more extensive than has generally been assumed, and that vacancy clusters may migrate by concerted, non-dissociative mechanisms. Our analysis suggests a complex dependence of the cation diffusion coefficient on the stoichiometry of the oxide, for all but the very near-stoichiometric materials.