Theoretical study of structural characteristics, mechanical properties and electronic structure of metal (TM = V, Nb and Ta) silicides

•Structural stability of TMxSiy was explored by first principles calculations.•Nb3Si2, Nb5Si4, Nb6Si5, NbSi and Ta3Si2 are proposed to be stable with lower ΔHf.•The bulk modulus is following the order of Ta-Si > Nb-Si > V-Si at each stoichiometry.•Mechanical and electronic properties of TMxSiy were analyzed in detail.

Using first-principles calculations, the crystal structure, mechanical property and electronic structure were investigated systematically for TM-Si (TM = V, Nb and Ta) systems. Pm  3¯n-V3Si, I4/mcm-V5Si3 and P6222-VSi2 for V-Si system, I4/mcm-Nb5Si3, P6222-NbSi2 for Nb-Si system, and P42/n-Ta3Si, I4/mcm-Ta2Si, I4/mcm-Ta5Si3, P6222-TaSi2 for Ta-Si system, are identified as thermodynamically stable structures, well consistent with previous theoretical and experimental reports. Stable P4/mbm-Nb3Si2, P41212-Nb5Si4, Ibam-Nb6Si5, Pnma-NbSi and P4/mbm-Ta3Si2 are proposed to be more likely realized in experiment because their formation enthalpies are close to convex-hull. The general order of bulk modulus is found to be Ta-Si > Nb-Si > V-Si at each stoichiometry. P6222-TMSi2 in each system shows the better mechanical properties. Both covalent bonding between Si-Si and Si-TM in TMSi2 are responsible for the structural stability and good mechanical property. The present study may shed light on better understanding of the phase relations in these transition metal silicides.