Decomposition of Fe3S above 250 GPa

作者：Ozawa Haruka^*; Hirose Kei; Suzuki Toshihiro; Ohishi Yasuo; Hirao Naohisa

来源：Geophysical Research Letters, 2013, 40(18): 4845-4849.

DOI：10.1002/grl.50946

• inner core
• high pressure
• light element

We have determined subsolidus phase relations in the Fe-FeS system up to 271GPa using laser-heated diamond-anvil cell techniques. In situ synchrotron X-ray diffraction (XRD) measurements performed at high pressure and high temperature demonstrate the coexistence of hexagonal close-packed (hcp) Fe and tetragonal Fe3S up to 241GPa and 2510K. In contrast, the XRD data obtained above 250GPa show that the hcp phase coexists with the CsCl (B2)-type phase for three different Fe-S bulk compositions (10, 16, and 20atm% S). Furthermore, chemical analyses using a scanning transmission electron microscope on a retrieved sample indicate that Fe3S sample decomposes into two phases at 271GPa and 2530K, consistent with the XRD data. Theory predicts the presence of extensive solid solution between Fe and FeS at inner core conditions, whereas our results suggest that the Fe-FeS system remains eutectic at least to 271GPa.

• 出版日期2013-9-28