Quantitative analysis of the formation energy of neutral point defects in perovskite-type BaTiO3 was carried out using first-principles calculations. A 40-atom super-cell was used, and relaxation of atoms within the second-nearest neighbor shell of the vacancy was taken into account. The formation energy was calculated as a function of the atomic chemical potential of the constituent atoms. The theoretical formation energy of the O vacancy exhibited negative values in the case of the reduction limit of BaTiO3. This was in good agreement with experimental results showing an abundance of O vacancies, when annealed in a reducing atmosphere, and n-type electrical conduction. The formation energies of the Ba vacancy and Ti vacancy, even under oxidizing conditions, were 2.21 and 5.65eV, respectively. This corresponded well with the experimental fact that Ba and Ti vacancies did not form alone in BaTiO3.

First-Principles Calculation of Formation Energy of Neutral Point Defects in Perovskite-Type BaTiO3. H.Moriwake: International Journal of Quantum Chemistry, 2004, 99[5], 824-7