A first-principles prediction of anisotropic elasticity and thermal properties of potential superhard WB3.

The first-principles calculations were used to predict the anisotropic elasticity and thermal properties of hexagonal ( hP 4-WB 3 , hP 8-WB 3 and hP 16-WB 3 ) and trigonal ( hR 24-WB 3 ) WB 3 triborides. The single-crystal and polycrystalline elastic properties were computed from the stress-strain method and Voigt-Reuss-Hill approximations, respectively. Based on the obtained elastic modulus, two theoretical models were used to theoretically calculate Vickers hardness H V of WB 3 . The results showed that hP 16-WB 3 and hR 24-WB 3 are potential candidates for superhard materials. The elastic anisotropies of WB 3 were characterized by elastic anisotropic indexes ( A U , A comp and A shear , and A 1 , A 2 and A 3 ), three-dimensional views and projections of bulk, shear and Young's moduli. The anisotropic elasticity is ordered as hP 8-WB 3 >  hP 4-WB 3 >  hR 24-WB 3 >  hP 16-WB 3 . Furthermore, the thermal properties such as Debye temperature and sound velocity were computed from the elastic constants and moduli. Finally, the directional sound velocities were also discussed. [ABSTRACT FROM AUTHOR]