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GEOPHYSICAL RESEARCH LETTERS,
VOL. 36,
L06306,
4 PP., 2009
doi:10.1029/2008GL036990
Phase relations of Fe-Si alloy in Earth's core
Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, USA
Department of Physics and Astronomy, Indiana University, South Bend, Indiana, USA
Department of Earth and Planetary Sciences, Northwestern University, Evanston, Illinois, USA
Department of Earth and Planetary Sciences, Northwestern University, Evanston, Illinois, USA
Consortium for Advanced Radiation Sources, University of Chicago, Chicago, Illinois, USA
Consortium for Advanced Radiation Sources, University of Chicago, Chicago, Illinois, USA
Phase relations of an Fe0.85Si0.15 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-Fe0.85Si0.15 is found to be stable between approximately 170 GPa and 240 GPa at high temperatures. Our extended results indicate that Fe0.85Si0.15 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.
Received 11 December 2008; accepted 3 March 2009; published 28 March 2009.
Citation: (2009), Phase relations of Fe-Si alloy in Earth's core, Geophys. Res. Lett., 36, L06306, doi:10.1029/2008GL036990.
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