First-principles prediction on the structural stability, electronic and mechanical properties of Ti_xB_y phases

The structure stability, mechanical and thermodynamic properties of TixBy phases were systematically studied by first-principles calculations. The analysis of phonon dispersion curves, formation enthalpies, energy bands, and density of states demonstrate that TixBy phases exhibit structure stability and metallic properties. Bulk modulus, Shear modulus, Young's modulus of TixBy phases are consistent with those reported experimentally. Anisotropy was explored by anisotropy index, 3D surface constructions and 2D projections. The order of anisotropy is TiB (NaCl) > Ti2B > TiB3 > TiB2 > Ti3B4 > TiB (Feb). Finally, Debye temperature and sound velocity were investigated, the order of Debye temperature is: TiB3 > TiB2 > Ti3B4 > TiB (Feb) > TiB (NaCl) > Ti2B. Other thermodynamical parameters also explored and can provided the useful data for experimental work.