First principles study of oxygen vacancy migration in tantalum pentoxide

摘要

First principles total energy calculations were performed in order to determine oxygen vacancy migration energies in Ta_(2)O_(5). A simplified version of the crystalline orthorhombic phase of Ta_(2)O_(5) was used in this study. O vacancies in the chosen model of Ta_(2)O_(5) can be broadly classified into 'cap' and 'in-plane' sites based on 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 oxygen vacancy 'sinks'. A lowering of the barriers to migration is generally seen when the vacancies are 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.