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Phase relations of Fe‐Si alloy up to core conditions: Implications for the Earth inner core
Author(s) -
Asanuma Hidetoshi,
Ohtani Eiji,
Sakai Takeshi,
Terasaki Hidenori,
Kamada Seiji,
Hirao Naohisa,
Sata Nagayoshi,
Ohishi Yasuo
Publication year - 2008
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 - 10.1029/2008gl033863
Subject(s) - inner core , silicon , alloy , core (optical fiber) , materials science , silicate , dissolution , outer core , core–mantle boundary , phase (matter) , earth (classical element) , anisotropy , structure of the earth , mantle (geology) , crystallography , metallurgy , geology , composite material , chemical engineering , chemistry , geophysics , optics , physics , engineering , mathematical physics , organic chemistry
X‐ray diffraction experiments were conducted to 257 GPa and high temperature in situ on an iron‐silicon alloy containing 3.4 wt% silicon, a candidate for the Earth's inner core forming material. The results revealed that fcc and hcp phases coexist up to 104 GPa. A single hcp phase is stable at higher pressures at least up to 3600 K at 242 GPa and to 2400 K at 257 GPa. Dissolution of silicon in the liquid outer core following reaction with the silicate mantle during core formation strongly suggests the existence of silicon in the solid inner core. Our results revealed that the iron‐3.4 wt% silicon alloy in the inner core is likely to possess an hcp structure, which can explain the inner core anisotropy observed in seismology.