Liquidus and solidus temperatures of a Fe-O-S alloy up to the pressures of the outer core: Implication for the thermal structure of the Earth's core
Liquidus and solidus temperatures of a Fe-O-S alloy up to the pressures of the outer core: Implication for the thermal structure of the Earth's core
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DOI：
10.1016/j.epsl.2011.02.041
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发表时间：
2011-04
影响因子：
5.3
通讯作者：
H. Terasaki;S. Kamada;T. Sakai;E. Ohtani;N. Hirao;Y. Ohishi
中科院分区：
文献类型：
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作者：
H. Terasaki;S. Kamada;T. Sakai;E. Ohtani;N. Hirao;Y. Ohishi
用激光加热的金刚石压腔结合原位X射线衍射法测定了Fe75O5S20合金的固相线和液相线温度，最高可达157 GPa.Fe(fcc/hcp)、Fe3S2/Fe3S和FeOB1/B8/三方相在亚固相线条件下是稳定的。首先，Fe_3S_2或Fe_3S相在Fe-Fe_3S系共晶点附近熔化，表明5at.%氧对Fe-Fe_3S系共晶温度的合金化影响不大。然后，FeO在比固相线高几百开尔文的温度下熔化，Fe在这个系统中是液相线。由于S和O对Fe熔化温度的合金化作用，使初生液相线温度比纯Fe的熔化温度低260~670K。根据我们的结果，估算出地核/地幔边界(TCMB)和内/外核边界(TICB)的温度分别为3600±200℃、4310±350K和5630±350K。这些结果为地核的热结构提供了重要的制约因素。
The solidus and liquidus temperatures of the Fe75O5S20alloy are determined up to 157GPa using a laser-heated diamond anvil cell combined with in situ X-ray diffraction technique. Fe (fcc/hcp), Fe3S2/Fe3S, and FeO B1/B8/rhombohedral phases are stable under subsolidus conditions. First, Fe3S2or Fe3S phase melts at a temperature close to the eutectic point of the Fe–Fe3S system, suggesting that the alloying effect of 5at.% oxygen on the eutectic temperature in the Fe–Fe3S system is minor. Then FeO melts at several hundreds of degrees Kelvin higher than the solidus, and Fe is a liquidus phase in this system. The liquidus temperature is 260–670K lower than the melting temperature of pure Fe because of the alloying effect of S and O on the melting temperature of Fe. Based on our results, the temperatures at the core/mantle boundary (TCMB) and at the boundary of the inner/outer core (TICB) are estimated to be 3600±200<TCMB<4310±350K and TICB~5630±350K, respectively. These results provide important constraints on the thermal structure of the Earth's core.