Influence of Impurities on Defect Formation and Oxygen Diffusion in TiN

The effect of substitutional impurities on the formation energy of nitrogen vacancies and the oxygen defect on the N-sublattice as well as on the oxygen migration energy in TiN is studied using the projector augmented wave method. It has been shown that 4d transition metals with the exception of Zr and elements of IIIA and IVA groups excluding Al and Si reduce the formation energy of nitrogen vacancies. At the same time, regardless of the impurity, the formation energy of the oxygen defect has a negative value. The oxygen migration energy within the first coordination sphere is increased by almost all impurities, while metals of the middle of the 4dperiod slightly lower the migration barrier of oxygen, which allows it to move away from the impurity atom. The lower and upper limits of the temperature-dependent diffusion coefficient of oxygen in the doped titanium nitride are estimated. It has been revealed that almost all considered impurities reduce the diffusion coefficient mainly due to a change in the migration energy.