Pressure-induced structural and spin transitions of Fe ₃S ₄

Abstract

Greigite (Fe ₃S ₄), isostructural with Fe ₃O ₄ 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 Fe ₃S ₄ 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 Fe ₃S ₄ would occur from the inverse spinel (SP) structure to the Cr ₃S ₄-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-Fe ₃S ₄, Fe ²⁺ located at octahedral environment firstly undergoes a transition from high-spin (HS) state to low-spin (LS) state at 8.5 GPa and Fe ³⁺ subsequently does at 17 GPa. The Equation of State for different phases of Fe ₃S ₄ are also determined. Our results not only give some clues to explore novel materials by utilizing Fe ₃S ₄ but also shed light on the fundamental information of Fe ₃O ₄, as well as those of other SP-AB ₂X ₄ compounds.