Ab initio modeling of the formation and migration of monovacancies in Ti 2AlC

Abstract

We performed ab initio calculations for monovacancy formation and migration in Ti 2 AlC. Carbon and aluminum vacancies have almost equally low formation energies, respectively, at (Ti- and Al-rich) and (Ti- and C-rich) growth conditions, wherein both defects exhibit a high equilibrium concentration and structural tolerance to large off-stoichiometry in Ti 2 AlC. In contrast, V Ti has the highest formation energy at all possible conditions. The intrinsic migration energies of various vacancies are determined to be in the sequence E m ( V Al ) < E m ( V Ti ) < E m ( V C ).