Defect Equilibria in Transition Metal Oxides

This paper assesses the importance of vacancy aggregates in transition metal oxides. It presents the predictions of quantitative atomistic calculations and discusses them in relation to observed structural, diffusion, thermodynamic, and other data. The results indicate that vacancy complexes constitute the major defect species at high nonstoichiometry. The commonly discussed vacancy‐hole complexes appear to be unimportant except, perhaps, over a very limited composition range.