Melting of iron determined by X-ray absorption spectroscopy to 100 GPa

Giuliana Aquilanti (1) , Angela Trapananti (2) , Amol Karandikar (3, 4) , Innokenty Kantor (2) , Carlo Marini (2) , Olivier Mathon (2) , Sakura Pascarelli (2) , Reinhard Boehler (3)

1 Elettra Sincrotrone Trieste
2 ESRF - European Synchrotron Radiation Facility
3 Geophysical Laboratory [Carnegie Institution]
4 Goethe-Universität Frankfurt am Main

Temperature, thermal history, and dynamics of Earth rely critically on the knowledge of the melting temperature of iron at the pressure conditions of the inner core boundary (ICB) where the geotherm crosses the melting curve. The literature on this subject is overwhelming, and no consensus has been reached, with a very large disagreement of the order of 2,000 K for the ICB temperature. Here we report new data on the melting temperature of iron in a laser-heated diamond anvil cell to 103 GPa obtained by X-ray absorption spectroscopy, a technique rarely used at such conditions. The modifications of the onset of the absorption spectra are used as a reliable melting criterion regardless of the solid phase from which the solid to liquid transition takes place. Our results show a melting temperature of iron in agreement with most previous studies up to 100 GPa, namely of 3,090 K at 103 GPa

Mots clés: XAS; iron melting curve; megabar range

Domaines: Sciences de la Terre

Giuliana Aquilanti, Angela Trapananti, Amol Karandikar, Innokenty Kantor, Carlo Marini, et al.. Melting of iron determined by X-ray absorption spectroscopy to 100 GPa. Proceedings of the National Academy of Sciences of the United States of America, 2015, 112 (39), pp.12042-12045. ⟨10.1073/pnas.1502363112⟩. ⟨hal-01572756⟩