Oxygen vacancies in metal oxides were known to determine their chemistry and physics. The properties of neutral O vacancies in metal oxides of increasing complexity (MgO, CaO, α-Al2O3 and ZnO) were studied by using density functional theory. Vacancy formation energies, vacancy-vacancy interaction, and the barriers for vacancy migration were determined and rationalized in terms of the ionicity, the Madelung potential, and lattice relaxation. It was found that the Madelung potential controlled the O vacancy properties of highly ionic oxides whereas a more complex picture arose for covalent ZnO.

First-Principles Analysis of the Stability and Diffusion of Oxygen Vacancies in Metal Oxides. J.Carrasco, N.Lopez, F.Illas: Physical Review Letters, 2004, 93[22], 225502