The mechanical, thermodynamic and electronic properties of Al ₃Nb with DO ₂₂ structure: A first-principles study

The lattice constants, elastic properties, electronic structure and thermodynamic properties of Al ₃Nb with DO ₂₂ structure have been investigated by the first-principles calculation. The calculated lattice constants were consistent with the experimental values, and the structural stability was also studied from the energetic point of view. The single-crystal elastic constants (C _ij) as well as polycrystalline elastic parameters (bulk modulus B, shear modulus G, Youngs modulus E, Poissons ratio υ and anisotropy value A) were calculated, and brittleness of Al ₃Nb was discussed in detail. Besides, the electronic structure of tetragonal Al ₃Nb was studied, which indicates a mixture of metallic bond and covalent bond in Al ₃Nb and reveals the underlying mechanism of the stability and elastic properties of Al ₃Nb. Finally, the thermodynamic properties of Al ₃Nb were calculated and the physical properties such as heat capacity and Debye temperature were predicted within the quasi-harmonic approximation.