The structural and electronic properties of fully-relaxed PbTiO3 (001) O-vacancy surface with PbO and TiO2 terminations were investigated by first-principles calculations. In contrast to the perfect surface, the smaller surface rumples and interlayer distances were found. The largest relaxation occurred on the second layer atoms not on the surface layer ones, and some in-gap Ti 3d states at about −1.1eV below the Fermi-level were observed in the TiO2-terminated surface caused by O-vacancies. For the PbO-terminated surface, some in-gap Ti 3d states and Pb 6p states also move into the bulk mid-gap region to become partially occupied, and two different chemical states of the Pb 6s states were found. One was attributed to the bulk perovskite Pb atoms and another one was caused by the relaxation of surface Pb atoms. These theoretical results would give a good reference for the future experimental studies.

First-Principles Study for the Atomic Structures and Electronic Properties of PbTiO3 Oxygen-Vacancies (001) Surface. M.Q.Cai, C.H.Tang, X.Tan, H.Q.Deng, W.Y.Hu, L.L.Wang, Y.G.Wang: Surface Science, 2007, 601[23], 5412-8