Pressure-Dependent Mechanical Properties of Nb₅Si₃ Phase from First-Principles Calculations

Herein, the pressure dependence of the structure, electronic properties, mechanical stability, elastic properties, and Debye temperature of (α, β, γ)-Nb₅Si₃ is investigated using the GGA-PW91 functional. The results show that the pressure has a clear effect on the mechanical and electronic properties of (α, β, γ)-Nb₅Si₃. The obtained structural and mechanical parameters agree well with the experiments and theoretical values at zero pressure. All these parameters linearly increase with the pressure. In particular, within the range of 25–100 GPa, the ductility of α-Nb₅Si₃ increases with the pressure, indicating that the pressure can improve ductility. The anisotropy A^U and A^T values of Nb₅Si₃ increase with the increasing pressure, and it is clear that Nb₅Si₃ is an anisotropic material. The density of states (DOS) shows that the covalent properties of α-Nb₅Si₃ are enhanced. The total density of states (TDOS) shape curve shows that the height of this peak decreases with the increasing pressure. The position of the peak shifts to lower energy. The Fermi level moves down with the pressure increases.