The Fe-C system at 5 GPa and implications for Earth's core

Nancy L. Chabot, Andrew J. Campbell, William F. McDonough, David S. Draper, Carl B. Agee, Munir Humayun, Heather C. Watson, Elizabeth Cottrell, Sarah A. Saslow

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)


Earth's core may contain C, and it has been suggested that C in the core could stabilize the formation of a solid inner core composed of Fe3C. We experimentally examined the Fe-C system at a pressure of 5 GPa and determined the Fe-C phase diagram at this pressure. In addition, we measured solid metal/liquid metal partition coefficients for 17 trace elements and examined the partitioning behavior between Fe3C and liquid metal for 14 trace elements. Solid metal/liquid metal partition coefficients are similar to those found in one atmosphere studies, indicating that the effect of pressure to 5 GPa is negligible. All measured Fe3C/liquid metal partition coefficients investigated are less than one, such that all trace elements prefer the C-rich liquid to Fe3C. Fe3C/liquid metal partition coefficients tend to decrease with decreasing atomic radii within a given period. Of particular interest, our 5 GPa Fe-C phase diagram does not show any evidence that the Fe-Fe3C eutectic composition shifts to lower C contents with increasing pressure, which is central to the previous reasoning that the inner core may be composed of Fe3C.

Original languageEnglish
Pages (from-to)4146-4158
Number of pages13
JournalGeochimica et Cosmochimica Acta
Issue number16
Publication statusPublished - 2008 Aug 15


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