Study on vacancy formation in ferroelectric PbTiO3 from <i>ab initio</i>

Abstract

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