Insight into the physical properties of two niobium based compounds, Nb3Be and Nb3Be2, via a first principles calculation

Abstract

We investigate the structural, electronic, mechanical and elastic properties of two niobium based intermetallic compounds, Nb3Be and Nb3Be2, by using the density functional theory (DFT) based theoretical method. A good agreement is found among the structural parameters of both the phases with the experimentally evaluated parameters. For both the phases metallic conductivity is observed, while the Nb3Be phase is more conducting than the Nb3Be2 phase. The evaluated DOS at the Fermi level indicates that the Nb3Be2 phase is electrically more stable than the Nb3Be phase. For both phases the Nb-4d state is mostly responsible for metallic conductivity. A study of the total charge density and Mulliken atomic population reveals the existence of covalent, metallic and ionic bonds in both intermetallics. Both the phases are mechanically stable in nature, while the Nb3Be phase is more ductile than the Nb3Be2 phase. A study of the Vickers hardness shows that the Nb3Be2 phase is harder than the Nb3Be phase. Both compounds are anisotropic in nature, while the Nb3Be phase possesses larger anisotropic characteristics than the Nb3Be2 phase. The Debye temperature of both the compounds are also calculated and discussed.