Ab initio study of oxygen adsorption on the NiTi(1Â 1Â 0) surface and the surface phase diagram

The structures of the clean and oxygen atoms adsorbed austenite NiTi(1 1 0) surfaces were studied by the use of density functional theory. The results showed that the most stable sites for the adsorption of oxygen atoms were those with more Ti atoms as their nearest neighbours. Furthermore, the phase diagram of NiTi(1 1 0) surface was built. It showed that the adsorption of oxygen atoms on NiTi(1 1 0) surface can cause the segregation of Ti atoms at the surface and lead to the selective oxidation of Ti atoms on NiTi(1 1 0) surface when the oxygen chemical potential was high enough.