The effect of Nb doping on the formation of O vacancies in rutile TiO2 was studied by the use of ab initio density-functional calculations. The formation energies were calculated at different doping concentrations (CNb) and the corresponding electronic structures were analyzed. It was shown that the formation energy was mainly determined by the structural relaxation. As CNb increases, the formation energy first increases and then decreases with the maximum in vicinity of CNb=11.1at%. The investigation of electronic structures shows that the distribution of excess electrons, which was affected by the doping concentration and the types of oxygen vacancy, determines the relaxation and formation energy of oxygen vacancy. The calculated results indicated that the formation of oxygen vacancy in rutile TiO2 could be most effectively suppressed by Nb doping in a large range of Nb doping concentration. This may be one of the reasons why the proper amount of Nb doping could improve the oxidation resistance of γ-TiAl.

Ab initio Studies of Nb Doping Effect on the Formation of Oxygen Vacancy in Rutile TiO2. X.Wang, F.H.Wang, J.X.Shang, Y.S.Zhou: Journal of Physics and Chemistry of Solids, 2012, 73[1], 84–93