First-principles investigation of intrinsic defects and (N, O) impurity atom stimulated Al vacancy in Ti₂AlC

We use first-principles calculations to study the energetics of intrinsic defects in Ti₂AlC and the effect of N or O impurity atoms on the generation of Al vacancies. The insertion of impurity atoms lowers the vacancy formation energy of its neighboring Al. The formation of Al vacancies is related to the experimental observations of growth of AlN or Al₂O₃ nanowires and nanofibers on the surface of Ti₂AlC. Since the growth of these nanostructures is controlled by the generation and migration of intrinsic defects, we propose that a tunable method for synthesis of such nanostructures is possible by controlling impurities.