Formation energies of possible vacancies under different O partial pressures were studied using an ab initio density functional theory and super-cell approach. Under O-rich conditions, Pb vacancies were the stable ones throughout the band-gap, and their ionization level was located at 0.56eV from the top of valence band, which could contribute to p-type conduction. Under O-poor conditions, O vacancies were the stable ones at the top of the valence band. It was a deep donor that may not only dilute the acceptor carriers to weaken the p-type conduction but hardly contributed to n-type conduction.

Study on Vacancy Formation in Ferroelectric PbTiO3 from ab initio. Z.Zhang, P.Wu, L.Lu, C.Shu: Applied Physics Letters , 2006, 88[14], 142902 (3pp)