Density of FeS up to the Martian core condition using the X-ray absorption method with laser-heated diamond anvil cell: implication to the Martian core structure

A relationship between density of solid FeS and that of coexisting liquid Fe–S is crucial for understanding the Martian core structure. In the sulfur-rich Martian core (S > 25 wt%), FeS could be a liquidus phase. In this study, the density of FeS V phase was measured using the X-ray absorption method combined with a laser-heated DAC up to 26 GPa and 1950K. The density from the X-ray absorption method is consistent with that from X-ray diffraction (0.04–2.82% in difference). The density of FeS is found to be lower than that of the liquid Fe–30wt%S at the Martian core pressures. Therefore, solid FeS could float in the liquid Fe–S core. The solid FeS outer core may influence the weak Martian magnetic field. If Mars has a solid inner core, FeS is excluded from the liquidus phases in the core, indicating that the sulfur content in the core is constrained to be

固态硫化亚铁（FeS）的密度与共存铁硫（Fe-S）熔体的密度之间的关系，对于理解火星核结构至关重要。在硫含量大于25 wt%的富硫火星核中，FeS可作为液相线相（liquidus phase）。本研究采用X射线吸收法（X-ray absorption method）结合激光加热金刚石对顶砧（laser-heated DAC），在最高26 GPa与1950 K的条件下测定了FeS V相的密度。X射线吸收法得到的密度结果与X射线衍射（X-ray diffraction）所得结果的差值介于0.04%至2.82%之间，二者一致性良好。在火星核压力条件下，固态FeS的密度低于含铁30 wt%硫的铁硫熔体的密度。因此，固态FeS可漂浮于铁硫熔体核中。固态FeS构成的外核可能会对微弱的火星磁场产生影响。若火星存在固态内核，则FeS将被排除在核内液相线相之外，这表明核内硫含量被约束为