Oxygen interstitial structures in close-packed metal oxides

We examine oxygen incorporation in alpha-Al2O3 using electronic structure techniques. We demonstrate that the ground-state configuration is a peroxide split interstitial, which is more than 2 eV lower in energy than the oxide closed-shell interstitial species in alumina, which proves to be only a transition state. Our results have general implications for the nature of oxygen interstitials in close-packed oxides.