Stability, electronic structure, mechanical properties and lattice thermal conductivity of FeS and FeS₂ polymorphs

Abstract

First-principles calculations were used to investigate the stability, electronic structure, elastic and lattice thermal conductivity of FeS and FeS2 polymorphs ([Formula: see text]-FeS, [Formula: see text]-FeS, [Formula: see text]-FeS, [Formula: see text]-FeS2, [Formula: see text]-FeS2). The calculated lattice parameters were in agreement with experimental results. The results showed that these Fe-S binary compounds are thermodynamically and mechanically stable. The elastic anisotropies of Fe-S binary compounds were exhibited by 3D modulus ball and 2D projections. Among all the five compounds, [Formula: see text]-FeS2 compound has the largest bulk modulus and [Formula: see text]-FeS2 has the largest Young’s modulus and hardness. Furthermore, [Formula: see text]-FeS, [Formula: see text]-FeS and [Formula: see text]-FeS compounds can be regarded as ductile material according to [Formula: see text] and Poisson’s ratio. The FeS compounds show metallic character and FeS2 compounds show semiconductor character through analyzing their bandgap and density of states (DOS). The [Formula: see text]-FeS2 has the largest thermal conductivity according to the Clarke model, and the [Formula: see text]-FeS shows the strongest thermal conductivity anisotropy among the five compounds.