Fe electronic and structural local environments in iron oxides melt and amorphous phases.

The Earth’s outer-core (136 – 330 GPa) is composed of convecting liquid iron with up to 5% oxygen in addition to other light elements. Layering inside the Earth’s outer-core, crucial for the Geodynamo, has been suggested based on seismological, geomagnetic observations and experiments and could be caused by changes in Fe-O bonding environment. Study of molten iron oxides is a way to investigate Fe-O bonding and dynamic compression allows us to investigate these extreme states. Previous XRD data have shown a change in Fe2O3 structure factor at ~145 GPa under shock although local amorphous / melt structure could not be determined due to limited Q-range [Crepisson et al., under review]. We propose here to perform a XAS study of molten and amorphous FeO and Fe2O3 under shock compression up to 280 GPa to retrieve local structure of Fe by analysis of EXAFS spectra supported by DFT-MD calculations, evidence possible electronic changes based on study of XANES spectra and estimate temperatures.