Structure, mechanical, electronic and thermodynamic properties of Mo5Si3 from first-principles calculations

Transition metal silicides are promising advanced functional materials. However, the structure and relevant properties of Mo5Si3 are not well understood. In this work, we investigate the crystal structure, elastic properties, Vickers hardness, elastic anisotropy, electronic and thermodynamic properties of Mo5Si3 by using the first-principles calculations. Three structures: tetragonal, hexagonal and orthorhombic structures are considered. The calculated results show that those structures are thermodynamically stable. In particular, we firstly predict that Mo5Si3 with hexagonal (P63/mcm) structure is a stable phase. The calculated electronic structure shows that Mo5Si3 exhibits better electronic properties because of the charge overlap between Mo-4d state and Si-3p state near the Fermi level. Importantly, Mo5Si3 shows the strong deformation resistance and high elastic stiffness in comparison to other TM5Si3. Mo5Si3 with tetragonal structure has the smaller percentage anisotropy in compressibility and high percentage anisotropy in shear. We further find that the Debye temperature and heat capacity of tetragonal structure are larger than that of hexagonal structure. The high-temperature thermodynamic properties of Mo5Si3 are attributed to the vibration of Si atom.