High pressure and temperature behavior of FeS

Abstract

High pressure and temperature behavior of stoichiometric FeS (troilite) was studied up to 16 GPa and 800 °C using a combination of a large volume press apparatus and a synchrotron X-ray source. A pressuretemperature phase diagram of FeS was determined from more than 200 data points. The phase diagram shows that there are four stable phases; the troilite phase, the hexagonal phase, the NiAs type phase and the high pressure phase with a monoclinic cell. In the compression curve of FeS at 300 °C, an inflection was observed at 7.5 GPa. Minimum value of cubical expansion under high pressure was also observed around 6 GPa. These results suggested an electronic transition of the hexagonal phase between 6 and 8 GPa. The transition might explain a curved boundary between the hexagonal phase and the monoclinic high pressure phase.