Anisotropy of elastic properties of cubic Nb3O3 niobium monoxide

The band structure calculation indicated that cubic Nb3O3 niobium monooxide is a com-pound with metallic conductivity. The anisotropy of the elastic properties of cubic (space group Pm3‾m) niobium monoxide Nb3O3 has been studied. The elastic stiffness constants cij for cubic Nb3O3 monoxide are computed using the density functional theory. The dependences of the Young's, bulk and shear moduli, as well as the Poisson's ratio in the (100), (110) and (111) planes of cubic niobium monoxide Nb3O3 on the crystallographic direction [hkl] are calculated. It is found that the maximum the Young's and shear moduli are observed in the [001], [010], and [100] directions, and the minimum values of the Young's and shear moduli are observed in the [±1 ± 1 ±1] directions of cubic niobium monoxide, respectively. Relatively small changes in the elastic characteristics of Nb3O3 depending on the [hkl] direction indicate a slight anisotropy of its elastic properties. Cubic niobium monoxide is mechanically and dynamically stable. The hardness HV and the Debye temperature θD of polycrystalline cubic niobium monoxide Nb3O3 are determined to be 17.2 GPa and ∼640 K, respectively. [Display omitted] •The anisotropy of the elastic properties of cubic Nb3O3 niobium monoxide is studied.•Values of elastic properties of Nb3O3 depend on the crystallographic [hkl] direction.•Small changes of elastic properties on [hkl] direction indicate their slight anisotropy.•Cubic niobium monoxide is mechanically stable.•Hardness and the Debye temperature of polycrystalline Nb3O3 monoxide are determined.