High-pressure induced phase transition of FeS2: Electronic, mechanical and thermoelectric properties

Being as the most abundant natural mineral among the iron-based sulphides, iron pyrite (FeS2) has been extensively investigated. These investigations mainly focused on the known marcasite (Pnnm) and pyrite (Pa3¯) phases, due to unknown of high pressure (HP) structural phases of FeS2. Here, we report a theoretical study up to 300 GPa to uncover a brand new monoclinic HP phase of C2/m structure at above 192 GPa. The stable of this structure is evaluated by the thermodynamical, dynamical and mechanical calculations. The C2/m structure is characterized by distorted FeS6 octahedron together with two connected 1D zigzag-like S chains. Analysis of the thermoelectric calculations indicates that the electronic thermal conductivity and electrical conductivity of C2/m structure linearly increasing with increasing temperature. Meanwhile, it is found that the C2/m phase behaves in a ductile manner through the elastic parameters calculations.