Equation of State of Liquid Iron under Extreme Conditions

Yasuhiro Kuwayama , Guillaume Morard (1, 2) , Yoichi Nakajima , Kei Hirose (3) , Alfred Q R Baron , Saori I Kawaguchi , Taku Tsuchiya (3) , Daisuke Ishikawa , Naohisa Hirao , Yasuo Ohishi (4)

1 IMPMC - Institut de minéralogie, de physique des matériaux et de cosmochimie
2 ISTerre - Institut des Sciences de la Terre
3 UTokyo - The University of Tokyo
4 JASRI - Japan Synchrotron Radiation Research Institute [Hyogo]

The density of liquid iron has been determined up to 116 GPa and 4350 K via static compression experiments following an innovative analysis of diffuse scattering from liquid. The longitudinal sound velocity was also obtained to 45 GPa and 2700 K based on inelastic x-ray scattering measurements. Combining these results with previous shock-wave data, we determine a thermal equation of state for liquid iron. It indicates that the Earth’s outer core exhibits 7.5–7.6% density deficit, 3.7–4.4% velocity excess, and an almost identical adiabatic bulk modulus, with respect to liquid iron.

Domaines: Géophysique [physics.geo-ph]

Yasuhiro Kuwayama, Guillaume Morard, Yoichi Nakajima, Kei Hirose, Alfred Q R Baron, et al.. Equation of State of Liquid Iron under Extreme Conditions. Physical Review Letters, 2020, 124 (16), ⟨10.1103/PhysRevLett.124.165701⟩. ⟨hal-02732910⟩