First principles investigation of elastic and thermodynamic properties of CoSbS thermoelectric material

Abstract Temperature and pressure are the two primary factors affecting the performance of thermoelectric devices. In this work, using density functional theory and the quasi-harmonic approximation, we calculated the pressure-dependent elastic and thermodynamic properties of the natural thermoelectric CoSbS material. The n-type CoSbS was found to exhibit a multi-band characteristic with an indirect band gap of 0.374 ​eV near the conduction band minimum, which was mainly dominated by the Co-d orbital. The calculated elastic constants including the bulk modulus (B) and Young modulus (E) suggest that CoSbS possesses excellent mechanical properties. The hardness (Hv) decreases slightly with increasing pressure and the anisotropy (Au) increases slightly. Moreover, the temperature dependence of the thermodynamic properties indicates that CoSbS exhibits a strong B, and Gruneisen parameter (γ) and thermal expansion coefficient (α) that are smaller in the range of 300–800 ​K. Our simulation indicates that thermoelectric material CoSbS would be useful for designing thermoelectric devices exhibiting stable performance.