First-principles study of structural and elastic properties of Sc2AC (A=Al, Ga, In, Tl)

Using first-principles calculations, the structural and elastic properties of Sc2AC, with A=Al, Ga, In and Tl, were studied by means of the pseudo-potential plane-waves method. Calculations were performed within the local density approximation to the exchange-correlation approximation energy. The effect of high pressures, up to 20 GPa, on the lattice constants and the internal parameters is calculated. The elastic constants are calculated using the static finite strain technique. We derived the bulk and shear moduli, Young’s moduli and Poisson’s ratio for ideal polycrystalline Sc2AC aggregates. We estimated the Debye temperature of Sc2AC from the average sound velocity. This is the first quantitative theoretical prediction of the elastic properties of Sc2AlC, Sc2GaC, Sc2InC and Sc2TlC compounds, and it still awaits the experimental confirmation.