First-principles investigation of the ternary scandium based inverse-perovskite carbides Sc3AC (A = Al, Ga, In and Tl)

Based on first-principles approach, we present a comparative study of structural, electronic, elastic and thermo-dynamical properties of the series of inverse-perovskites Sc3AC, with A = Al, Ga, In and Tl. The calculated equilibrium lattice constants are in excellent agreement with the experimental and available theoretical data. The electronic band structures and densities of states profiles show that the studied compounds are conductors. Analysis of atomic site projected local density of states and charge densities reveals that a mixture of covalent–ionic–metallic characterizes the chemical bonding of the considered inverse-perovskites. Pressure dependence up to 40 GPa of the single-crystal and polycrystalline elastic constants has been investigated in details. The computed B/G ratios show that all Sc3AC compounds are brittle. We have estimated the sound velocities in the principal directions. Through the quasi-harmonic Debye model, in which the phononic effects are taken into account, the temperature and pressure effects on the lattice constant, bulk modulus, heat capacity and Debye temperature are performed.

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► We studied for the first time some properties of Sc3AC (A = Al, Ga, In, Tl).
► The electronic structures reveal the metallic character of these compounds.
► The elastic parameters increase linearly with the increasing pressure.
► All studied Sc3AC compounds are found to be brittle.
► Temperature and pressure effects on some macroscopic parameters are obtained.