Phase stability of the nanolaminates V(2)Ga(2)C and (Mo(1–x)V(x))(2)Ga(2)C from first-principles calculations

We here use first-principles calculations to investigate the phase stability of the hypothetical laminated material V(2)Ga(2)C and the related alloy (Mo(1–x)V(x))(2)Ga(2)C, the latter for a potential parent material for synthesis of (Mo(1–x)V(x))(2)C, a new two-dimensional material in the family of so called MXenes. We predict that V(2)Ga(2)C is thermodynamically stable with respect to all identified competing phases in the ternary V–Ga–C phase diagram. We further calculate the stability of ordered and disordered configurations of Mo and V in (Mo(1–x)V(x))(2)Ga(2)C and predict that ordered (Mo(1–x)V(x))(2)Ga(2)C for x ≤ 0.25 is stable, with an order–disorder transition temperature of ∼1000 K. Furthermore, (Mo(1–x)V(x))(2)Ga(2)C for x = 0.5 and x ≥ 0.75 is suggested to be stable, but only for disordered Mo–V configurations, and only at elevated temperatures. We have also investigated the electronic and elastic properties of V(2)Ga(2)C; the calculated bulk, shear, and Young's modulus are 141, 94, and 230 GPa, respectively.