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Thermoelasticity of Fe 7 C 3 under inner core conditions
Author(s) -
Li Y.,
Vočadlo L.,
Brodholt J.,
Wood I. G.
Publication year - 2016
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2016jb013155
Subject(s) - inner core , thermoelastic damping , softening , core (optical fiber) , outer core , materials science , shear (geology) , thermodynamics , mineralogy , geophysics , geology , physics , thermal , composite material
It has recently been reported, on the basis of extrapolated experimental data, that the iron carbide, Fe 7 C 3 , has shear wave velocities and a Poisson's ratio consistent with the seismological values for the Earth's inner core and thus that Fe 7 C 3 is a strong candidate for the inner core composition. In this study, using ab initio molecular dynamics simulations, we report the thermoelastic properties of Fe 7 C 3 at 350 GPa up to its melting temperature. Due to significant elastic softening prior to melting, the calculated elastic properties, including wave velocities, do indeed agree well with those from seismology. However, the density was found to be much too low (by ~8%) when compared to geophysical data, and therefore, Fe 7 C 3 must be ruled out as a major component of the Earth's inner core.