A first principles investigation on the structural, elastic, and mechanical properties of MAX phase M3AlC2 (M= Ta, Ti, V) as a function of pressure

This study investigated the structural, elastic, and mechanical properties of hexagonal M3AlC2 (M = Ta, Ti, and V) within MAX phases by first-principles calculations. The considered properties of M3AlC2 (M = Ta, Ti, and V) compounds at 0 GPa were in reasonable agreement with available experimental and other theoretical data. The elastic stability shows that no structural phase transition occurred in pressure up to 20 GPa for all compounds. The resistances to linear compression were more forceful than the resistances to compression in shape. The bulk modulus, shear modulus, and Young's modulus for M3AlC2 (M = Ta, Ti, and V) compounds follow the order Ta3AlC2 > V3AlC2 > Ti3AlC2. The Bader charge analysis result shows the increasing of covalence bond in their structure after the pressure increased. Furthermore, Pugh's criterion B/G and Poisson's ratio v confirmed that the M3AlC2 (M = Ta, Ti, and V) compounds had intrinsic brittleness. The sound velocity and Debye temperature of all compounds increased with pressure increasing. The bond stiffness and the shear anisotropy affected by pressure were reported and discussed.