Sound velocity of liquid Fe alloys under high pressures via inelastic X-ray scattering measurements - Yoichi Nakajima

Yoichi Nakajima - Materials Dynamics Laboratory, RIKEN SPring-8 Center, RIKEN, Hyogo 679-5148, Japan

Lundi 29 février 2016 à 10 h 30
IMPMC - Université P. et M. Curie - 4, Place Jussieu - 75005 Paris

Salle de Conférence - Barre 22-23 - 4e étage - Salle 401

Abstract

The light elements of the Earth’s core have long been controversial. Sound velocity and density given by seismological observations are fundamental information of the Earth’s core. The Fe rich metallic core is predominantly molten, and therefore the longitudinal wave (P-wave) velocity as well as the density of liquid Fe-alloys is a key to constrain the chemical composition of the core. We have performed inelastic X-ray scattering (IXS) measurements combined with the diamond-anvil cell technique at the SPring-8 synchrotron facility, in order to investigate the P-wave velocities of liquid Fe alloys under high pressure and high temperature. We examined liquid Fe alloying with possible components in the core such as C, Si, and S, and then determined their velocities up to 70 GPa and 3000 K. Using the present experimental results and literature data, elastic parameters and equations of state for those liquid alloys were investigated to extrapolate the present velocity data to core pressures and to estimate the densities of these liquids as well. Comparing the present results with seismological velocity and density data, I will discuss the nature of light elements in the Earth’s core.