Layered Structure Induced Anisotropic Low-Energy Recoils in Ti₃SiC₂

Low-energy recoil events in Ti₃SiC₂ are studied using ab initio molecular dynamics simulations. We find that the threshold displacement energies are orientation dependent because of anisotropic structural and/or bonding characteristic. For Ti and Si in the Ti–Si layer with weak bonds that have mixed covalent, ionic, and metallic characteristic, the threshold displacement energies for recoils perpendicular to the basal planes are larger than those parallel to the basal planes, which is an obvious layered-structure-related behavior. The calculated minimum threshold displacement energies are 7 eV for the C recoil along the (Formula presented.) direction, 26 eV for the Si recoil along the (Formula presented.) direction, 24 eV for the Ti in the Ti–C layer along the (Formula presented.) direction and 23 eV for the Ti in the Ti–Si layer along the (Formula presented.) direction. These results will advance the understanding of the cascade processes of Ti₃SiC₂ under irradiation and are expected to yield new perspective on the MAX phase family that includes more than 100 compounds.