A study was made of the formation energy of the oxygen vacancy and its effect

upon spontaneous polarizations of Bi4Ti3O12 using first-principles theoretical

calculations. It was found that neutral and +2 charged oxygen vacancies preferred

sites in the Bi2O2 layers, while +1 charged oxygen vacancies were not stable. The

spontaneous polarizations of the perfect-crystal Bi4Ti3O12 in both the a and c

directions agreed with experiment. It was also shown that, even if neutral or

charged oxygen vacancies existed in a Bi2O2 layer, the spontaneous polarizations

were not altered significantly from those of the perfect crystal.

Oxygen Vacancy Formation Energy and Its Effect on Spontaneous Polarization in

Bi4Ti3O12: a First-Principles Theoretical Study. T.Hashimoto, H.Moriwake:

Physical Review B, 2008, 78[9], 092106