First principles total energy calculations were performed in order to determine O vacancy migration energies in Ta2O5. A simplified version of the crystalline orthorhombic phase of Ta2O5 was used here. O vacancies in the chosen model of Ta2O5 could be broadly classified into so-called cap and in-plane sites; based upon their location in the lattice. The cap type of vacancies display the largest barriers both for migration to a neighboring cap site or to a neighboring in-plane site, thus behaving as O vacancy sinks. A lowering of the barriers to migration was generally seen when the vacancies were doubly positively charged. All calculations were performed within the local density approximation of density functional theory, and the elastic band method was used in the estimation of migration barriers.

First Principles Study of Oxygen Vacancy Migration in Tantalum Pentoxide. R.Ramprasad: Journal of Applied Physics, 2004, 95[3], 954-7