First‐principles study of the atomic structures, electronic properties, and surface stability of BaTiO3 (001) and (011) surfaces

Abstract

The atomic structures, electronic properties, and surface stability of (001) and (011) surfaces of BaTiO3 are studied by first‐principles calculations. Four differently terminated BaTiO3 surfaces are considered in this study, including (001)‐BaO, (001)‐TiO2, (011)‐BaTiO, and (011)‐O2 terminations. The relaxations and rumplings are calculated and discussed, finding that the first layer relaxes inwards, while the second layer relaxes outwards for (001) and (110) surfaces. The data obtained for electronic properties show that O2p states in (001)‐BaO/(001)‐TiO2 termination shift to the lower/higher energy region, leading to a wide/narrow band gap. And the new produced surface states are observed in (011) surface terminations, which is mainly attributed to the supplied electrons from outermost surface atoms, even O atoms are oxidized. Furthermore, the (001) surface of BaTiO3 is found to be more stable than the (011) surface according to the predicted surface energy which is 0.86 and 2.92 J/m2 for (001) and (011) surfaces, respectively. Of which, BaO termination is predicted to be more likely to cleavage from the (001) direction than the TiO2 termination is.