Termination, stability and electronic structures of α-Al2O3 (01¯14) surface: An ab initio study

Termination, stability and electronic structure of α-Al2O3 (01¯14) surface were studied using ab initio method for the first time. Five surface models, namely the O–Al-terminated, 1Al-terminated, Al–O-terminated, 1O-terminated and 2O-terminated surface models were calculated combined with thermodynamics, considering the effects of temperature and oxygen partial pressure. Large outward relaxations of outmost oxygen atoms are found in each model and internal atomic positions are obtained. Results indicate that at a given temperature, the termination of α-Al2O3 (01¯14) surface transforms from stoichiometric O–Al termination to 1O termination and then to 2O termination in sequence with the increasing of oxygen partial pressure. The oxygen partial pressure at the transforming point lowers as temperature decreases. Electronic structures of α-Al2O3 (01¯14) surface are also discussed based on analysis of density of states (DOS) and electron localization function (ELF) in this paper.