The FeSi phase diagram to 150 GPa

DOI: 10.1029/2009JB006528

Authors: O. T. Lord (University of Bristol) , M. J. Walter (University of Bristol) , D. P. Dobson (University College London) , L. Armstrong (University of Bristol) , S. M. Clark (Advanced Light Source, Lawrence Berkeley National Laboratory) , A. Kleppe (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Geophysical Research: Solid Earth , VOL 115 , PAGES B06208

State: Published (Approved)
Published: June 2010

Abstract: The melting curve of FeSi has been determined to 150 GPa in the laser-heated diamond anvil cell (LH-DAC) on the basis of discontinuities in the power versus temperature function. A multianvil experimental cross-check at 12 GPa using textural criteria as a proxy for melting is in good agreement with our LH-DAC results. The melting point of FeSi reaches similar to 4000 K at the core mantle boundary and an extrapolated value of 4900 K at the inner-core boundary (ICB). We also present the melting curve as determined by the Lindemann melting law; this agrees well with our experimental curve to 70 GPa and then diverges to higher temperatures, reaching 6200 K at the ICB. These temperatures are substantially higher than previous LH-DAC determinations. The boundary of the epsilon-FeSi -> CsCl-FeSi subsolidus transition has also been determined by synchrotron-based X-ray diffraction at high pressures, and the results confirm a negative Clapeyron slope for the transition. We conclude that if present, FeSi is likely to be solid within the D '' layer and is unlikely to be present within the inner core for any plausible bulk core silicon content.

Subject Areas: Earth Science, Physics


Instruments: I15-Extreme Conditions

Added On: 12/07/2010 14:55

Discipline Tags:

Earth Sciences & Environment Geology Geophysics

Technical Tags:

Diffraction