Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8915708 | Physics of the Earth and Planetary Interiors | 2018 | 8 Pages |
Abstract
The phase relationships of the Fe-Ni-S system at 15â¯GPa were studied by high pressure quench experiments. The stability fields of (Fe,Ni)3S and (Fe,Ni)3S2 and the melting relationships of the Fe-Ni-S system were determined as a function of Ni content. The (Fe,Ni)3S solid solution is stable in the composition of Ni/(Feâ¯+â¯Ni)â¯>â¯0.7 and melts incongruently into an Fe-Ni alloyâ¯+â¯liquid. The (Fe,Ni)3S2 makes a complete solid solution and melts incongruently into (Fe,Ni)Sâ¯+â¯liquid, whose structure was determined to show Cmcm-orthorhombic symmetry by in situ synchrotron X-ray diffraction experiments. The eutectic contains about 30 at.% of S, and its temperature decreases with increasing Ni content with a rate of â¼5â¯K/at.% from 1175â¯K. The density of the Fe-FeS eutectic composition (Fe70S30) liquid is evaluated to be 6.93â¯Â±â¯0.08â¯g/cm3 at 15â¯GPa and 1200â¯K based on the Clausius-Clapeyron relations and densities of subsolidus phases. The Fe-Ni-S liquids are a primary sulfur-bearing phase in the deep mantle with a reducing condition (250-660â¯km depth), and they would play a significant role in the carbon cycle as a carbon host as well as in the generation of diamond.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geophysics
Authors
Satoru Urakawa, Ryota Kamuro, Akio Suzuki, Takumi Kikegawa,