The elastic anisotropy, electronic and thermodynamic properties of TM5Si4(TM= Sc, Y, Ti, Zr and Hf) silicides from first-principles calculations

In recent years, transition-metal silicon-based high temperature materials have attracted more and more attention due to their excellent physical and chemical properties. In this paper, we explored the phase stability, mechanical, anisotropy and thermodynamic properties of TM5Si4 (TM = Sc, Y, Ti, Zr and Hf) compounds by first-principles calculations. The results indicate that TM5Si4 compounds exhibit the thermodynamical and dynamical stability. And Hf5Si4 exhibits the best phase stability among five compounds. The orthorhombic Sc5Si4 and Y(5)Si(4 )are ductile, but the tetragonal Ti5Si4, Zr5Si4 and Hf5Si4 are brittle. The elastic anisotropies of TM5Si4 were demonstrated by the 3D contours and 2D projections of elastic modulus. The results confirm that the order of anisotropy is as follows: Zr5Si4 < Hf5Si4 < Ti5Si4 < Sc5Si4 < Y5Si4. TM-Si bonds can be formed in TM5Si4 silicides for the strong localized hybridization between TM-d and Si-3p states. Moreover, the thermal parameters confirm that five TM5Si4 silicides display the better thermal stability at elevated temperature.