Theoretical investigation of thermodynamic stability and mobility of the intrinsic point defects in Ti3AC2 (A = Si, Al)

Abstract

Nano-laminated Ti₃AC₂ (A = Si, Al) are highlighted as nuclear materials for a generation IV (GIV) reactor because they show high tolerance to radiation damage and remain crystalline under irradiation of high fluence heavy ions. In this paper, the energetics of formation and migration of intrinsic point defects are predicted by density functional theory calculations. We find that the space near the A atomic plane acts as a point defect sink and can accommodate lattice disorder. The migration energy barriers of Si/Al vacancy and Ti_Si anti-site defects along the atomic plane A are in the range of 0.3 to 0.9 eV, indicating their high mobility and the fast recovery of Si/Al Frenkel defects and Ti–A antisite pairs after irradiation. This layered structure induced large disorder accommodation and fast defect recovery must play an important role in the micro-structural response of Ti₃AC₂ to irradiation.