Adsorption properties of oxygen atom on the surface of Ti2AlNb by first principles calculations

Adsorption behaviors of oxygen on the surfaces of O-phase Ti2AlNb were studied by first principles calculations to clarify the interaction mechanisms between oxygen and Ti2AlNb. The calculated surface energies of low index surfaces of Ti2AlNb indicate that the stoichiometric (0 1 0) surface is the most stable surface of Ti2AlNb. Various adsorption sites of oxygen atom on Ti2AlNb surfaces were considered to search the most stable adsorption configurations. The calculated adsorption energies and the electronic structures illustrate that O atoms tend to bond with Ti and Nb atoms. The hybriding between O p, Nb d and Ti d orbitals was observed, and the charges were found to transfer from nearest Ti and Nb atoms to the adsorbed oxygen, which produce the O-Nb and O-Ti bonds rather than the O-Al bond. The weaker O-Al bonding indicates that at the initial stage the oxidation of O-phase Ti2AlNb in high temperature could not form a protection alumina but instead of the Ti and Nb oxides. (C) 2017 Elsevier B.V. All rights reserved.