First Principles Simulations on Migration Paths of Oxygen Interstitials in MgAl₂O₄

Thermal stability of the primary electronic defects – F-type centers – in oxide materials is controlled by their recombination with much more mobile complementary defects – interstitial oxygen ions O_i. Thus, the study of interstitial ion migration is of key importance for the prediction of radiation damage in oxides. In this study, several possible migration trajectories for neutral and charged interstitial oxygen ions are calculated in MgAl₂O₄ spinel using the first principles calculations of atomic and electronic structure. The lowest energy barriers are ≈1.0–1.1 eV and 0.8 eV, respectively. The effective atomic charges, charge redistribution, and lengths of bonds closest to O_i interstitials are analyzed in detail.