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Decomposition of Fe 3 S above 250 GPa
Author(s) -
Ozawa Haruka,
Hirose Kei,
Suzuki Toshihiro,
Ohishi Yasuo,
Hirao Naohisa
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/grl.50946
Subject(s) - tetragonal crystal system , eutectic system , materials science , phase (matter) , analytical chemistry (journal) , diamond anvil cell , diffraction , synchrotron , inner core , x ray crystallography , transmission electron microscopy , crystallography , solid solution , decomposition , mineralogy , crystal structure , chemistry , microstructure , optics , nanotechnology , metallurgy , composite material , physics , organic chemistry , chromatography
We have determined subsolidus phase relations in the Fe–FeS system up to 271 GPa 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 Fe 3 S up to 241 GPa and 2510 K. In contrast, the XRD data obtained above 250 GPa show that the hcp phase coexists with the CsCl (B2)‐type phase for three different Fe–S bulk compositions (10, 16, and 20 atm% S). Furthermore, chemical analyses using a scanning transmission electron microscope on a retrieved sample indicate that Fe 3 S sample decomposes into two phases at 271 GPa and 2530 K, 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 271 GPa.