Pressure-induced structural and electronic transitions of thiospinel FeS.

We report the investigations on the structural and electronic properties of an inverse spinel FeS at high pressures using synchrotron x-ray diffraction (XRD) and electrical transport measurements. Our XRD measurements at high pressures reveal an irreversible structural phase transformation on compression above  ∼3 GPa from a cubic spinel (Fd-3m space group) into a monoclinic CrS-type structure (I2/m space group). Electrical transport measurements suggest that the high pressure monoclinic phase has a semiconducting behavior. This semiconducting behavior is found to persist up to the highest pressure of measurement of  ∼23 GPa. These results show that while FeS possesses similar high pressure structural properties with other thiospinels, the electronic properties under pressure show a rather strong similarity to its oxide counterpart, FeO, at high pressures.