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Phase relations of Fe‐Si alloy in Earth's core
Author(s) -
Lin JungFu,
Scott Henry P.,
Fischer Rebecca A.,
Chang YunYuan,
Kantor Innokenty,
Prakapenka Vitali B.
Publication year - 2009
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 - 10.1029/2008gl036990
Subject(s) - alloy , inner core , materials science , outer core , phase (matter) , core (optical fiber) , diffraction , diamond anvil cell , crystallography , metallurgy , composite material , chemistry , optics , physics , organic chemistry
Phase relations of an Fe 0.85 Si 0.15 alloy were investigated up to 240 GPa and 3000 K using in situ X‐ray diffraction in a laser‐heated diamond anvil cell. An alloy of this composition as starting material is found to result in a stabilized mixture of Si‐rich bcc and Si‐poor hcp Fe‐Si phases up to at least 150 GPa and 3000 K, whereas only hcp ‐Fe 0.85 Si 0.15 is found to be stable between approximately 170 GPa and 240 GPa at high temperatures. Our extended results indicate that Fe 0.85 Si 0.15 alloy is likely to have the hcp structure in the inner core, instead of the previously proposed mixture of hcp and bcc phases. Due to the volumetric dominance of the hcp phase in the hcp + bcc coexistence region close to the outer‐core conditions, the dense closest‐packed Fe‐Si liquid is more relevant to understanding the properties of the outer core.