Elastic anisotropy of novel YAlC from an ab initio study

First principles calculations are performed to investigate the structural, elastic and electronic properties of orthorhombic YAlC, the first aluminide carbide with a polyacetylene-related geometry. The computed equilibrium structural parameters are consistent with the available experimental data. On the basis of the computed elastic constants, theoretical bulk modulus as well as shear modulus, the elastic anisotropy is evaluated in terms of shear anisotropic factors and directional-dependent bulk modulus and directional-dependent Young's modulus. In conjunction with the unique atomic arrangements, the density of states and electron density analysis reveal that the mixed character of the ionic, covalent and metallic chemical bonding among the ingredients is the main contribution to the remarkable elastic anisotropy. (C) 2016 Elsevier B.V. All rights reserved.