Equation of state of liquid Fe–17 wt%Si to 12 GPa

Abstract

Equation of state (EOS) of liquid Fe–17 wt%Si has been investigated at a temperature of 1773 K and pressures up to 12 GPa by the sink/float technique using composite spheres. The EOS of liquid Fe–17 wt%Si, in the form of the second order Birch–Murnaghan equation, produces K _0T=68±2 GPa when K′_0T=4.0. Considering the effect of temperature and pressure on K _0T, extrapolation of this EOS to Earth's outer core conditions reveals that the addition of Si to liquid Fe decreases its density ρ and increases its compressional wave velocity V _P , indicating that Si is a possible light element candidate in the outer core. The possible existence of Si in the cores of other planetary bodies is also discussed.

Keywords:

• equation of state
• high P
• T
• liquid Fe–Si density
• planetary core
• bulk modulus
• V _P

Acknowledgements

The authors thank R. Tucker and G. Wood for preparing the probe spheres and Dr M. Liu for the Electron Microprobe analyses. We appreciate Dr. Xi Liu for the helpful discussion. We also thank the anonymous reviewer for comments on this paper. RAS acknowledge NSERC for financial support of this study.