Ab initio study of pressure dependence of the structural, elastic and thermodynamic properties of AlXY3 (X = B, C)

ABSTRACT We have investigated the pressure dependence of the structural, elastic and thermodynamic properties of the ternary AlXY3 (X = B, C) compounds through the ab initio pseudopotential plane wave method within the general gradient approximation developed especially for solids. The optimized lattice parameters are in good agreement with the available experimental and theoretical counterparts. Analysis of the monocrystalline elastic constants predicted through the strain–stress technique shows that the studied materials are mechanically stable with strong elastic anisotropy. The calculated polycrystalline moduli highlight that the title compounds exhibit a moderate resistant to external deformations, AlBC3 is in the border between ductility and brittleness and AlCY3 is brittle. The quasi-harmonic Debye model was used to explore the temperature and pressure dependencies of the lattice parameter, bulk modulus, isochore and isobar heat capacities, volume thermal expansion coefficient and Debye temperature.