Phase stability of the nanolaminates V2Ga2C and (Mo1-xVx)2Ga2C from first-principles calculations

We here use first-principles calculations to investigate the phase stability of the hypothetical laminated material V2Ga2C and the related alloy (Mo1-xVx)2Ga2C, the latter for a potential parent material for synthesis of (Mo1-xVx)2C, a new two-dimensional material in the family of so called MXenes. We predict that V2Ga2C 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 (Mo1-xVx)2Ga2C and predict that ordered (Mo1-xVx)2Ga2C for x≤ 0.25 is stable, with an order-disorder transition temperature of ∼1000 K. Furthermore, (Mo1-xVx)2Ga2C 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 V2Ga2C; the calculated bulk, shear, and Young's modulus are 141, 94, and 230 GPa, respectively.