The structure, mechanical and electronic properties of WSi2 from first-principles investigations

Tungsten disilicide (WSi2) is an attractive advanced functional material, which is regarded as the potential thermoelectric devices, energy storage system and aerospace etc. However, the correlation between structure and the related performances of WSi2 is not well understood. To solve those problems, we apply first-principles calculations to study crystal structure, electronic properties, elastic properties and electronic structure of four possible WSi2. We demonstrate the WSi2 with C54 TiS2 -type orthorhombic structure (Fddd, No.70) is a dynamically stable. These results show that MoSi2 -type C11(b), tetragonal structure is more thermodynamically stable than that of the other structures. Importantly, MoSi2-type C11(b), TiSi2-type C49 and HfSi2-type C54 structures show electronic properties because of band overlap between the valence band and the conduction band near the Fermi level. However, NbSi2-type C40 structure shows a semiconductor property with a band gap of 0.049 eV. We further find that MoSi2-type C11(b) structure shows the strong shear deformation resistance and high elastic stiffness due to the pyramidal bonding state. WSi2 with TiSi2-type C54 structure exhibits better ductile in comparison to the other structures.