title: Structure and Density of FeS at High Pressure and High Temperature and the Internal Structure of Mars.
abstract: In situ x-ray diffraction measurements revealed that FeS, a possible core material for the terrestrial planets, transforms to a hexagonal NiAs superstructure with axial ratio (c/a) close to the ideal close-packing value of 1.63 at high pressure and high temperature. The high-pressure-temperature phase has shorter Fe-Fe distances than the low-pressure phase. Significant shortening of the Fe-Fe distance would lead to metallization of FeS, resulting in fundamental changes in physical properties of FeS at high pressure and temperature. Calculations using the density of the high-pressure-temperature FeS phase indicate that the martian core-mantle boundary occurs within the silicate perovskite stability field.
authors.forename: Y
authors.initials: Y
authors.lastname: Fei
authors.forename: C T
authors.initials: CT
authors.lastname: Prewitt
authors.forename: H K
authors.initials: HK
authors.lastname: Mao
authors.forename: C M
authors.initials: CM
authors.lastname: Bertka