Pressure-induced structural and spin transitions of FeS.

Greigite (FeS), isostructural with FeO has recently attracted great scientific interests from material science to geology due to its complicated structure and electronic and magnetic configurations. Here, an investigation into the structural, magnetic and electronic properties of FeS under high pressure has been conducted by first-principle calculations based on density functional theory. The results show that a first-order phase transition of FeS would occur from the inverse spinel (SP) structure to the CrS-type (CS) structure at 3.4 GPa, accompanied by a collapse of 9.7% in the volume, a redistribution of iron cations, and a half-metal to metal transition. In the CS-FeS, Fe located at octahedral environment firstly undergoes a transition from high-spin (HS) state to low-spin (LS) state at 8.5 GPa and Fe subsequently does at 17 GPa. The Equation of State for different phases of FeS are also determined. Our results not only give some clues to explore novel materials by utilizing FeS but also shed light on the fundamental information of FeO, as well as those of other SP-ABX compounds.