EGU25-17768, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-17768
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Study of iron phases at planetary core conditions using static experiments at the European XFEL
Sébastien Merkel1, Hélène Ginestet1, and the EuXFEL 3063 and 5700 community proposals*
Sébastien Merkel and Hélène Ginestet and the EuXFEL 3063 and 5700 community proposals
  • 1Univ. Lille, CNRS, UMET, 59000 Lille, France (sebastien.merkel@univ-lille.fr)
  • *A full list of authors appears at the end of the abstract

Iron is the main constituent of the Earth's and terrestrial planetary cores. It is in the body-centered-cubic (bcc) structure under ambient conditions and transforms into the face-centered-cubic structure (fcc) upon heating at ambient pressure and into the hexagonal-closed-packed (hcp) structures at ~15 GPa at ambient temperature. Reaching Earth's inner core conditions in experiments is not trivial, and most reports of experiments approaching those pressures and temperature refer to the hcp structure for pure iron. First principles calculations, however, show that the energy difference between hcp and cubic phases of Fe is small at inner core conditions and some have argued for stable cubic Fe phases in the Earth's inner core.

In this work, we explore the phase diagram of Fe up to over 200 GPa and up to melting through a different thermodynamical pathway from conventional laser-heated diamond anvil cell experiments.  The experiments rely on new facilities at the European X-Ray Free-Electron Laser, which provides extremely intense X-ray flashes repeated up to every 220 ns. The facility, coupled with the High Energy Density (HED) instrument, allows heating, melting, and crystallizing iron samples repeatedly and probe for its crystal structure as the sample cools from its previous state.

The experiments show a complex phase diagram for iron, and the observations of different crystal structures for iron as samples are moved through different thermodynamic states. Here, I will present these new experiments and preliminary results that can be obtained on Fe, along with our work on experimental metrology, which are actively pursuing at present.

Presentation on behalf of the EuXFEL 3063 community proposal, led by S. Merkel and G. Morard (doi: 10.22003/XFEL.EU-DATA-003063-00), and the EuXFEL 5700 community proposal, led by A. Dewaele and S. Merkel (doi: 10.22003/XFEL.EU-DATA-005700-00).

EuXFEL 3063 and 5700 community proposals:

Presentation on behalf of the EuXFEL 3063 community proposal, led by S. Merkel and G. Morard (doi: 10.22003/XFEL.EU-DATA-003063-00), and the EuXFEL 5700 community proposal, led by A. Dewaele and S. Merkel (doi: 10.22003/XFEL.EU-DATA-005700-00).

How to cite: Merkel, S. and Ginestet, H. and the EuXFEL 3063 and 5700 community proposals: Study of iron phases at planetary core conditions using static experiments at the European XFEL, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17768, https://doi.org/10.5194/egusphere-egu25-17768, 2025.