Japan Geoscience Union Meeting 2019

Presentation information

[E] Oral

S (Solid Earth Sciences ) » S-IT Science of the Earth's Interior & Techtonophysics

[S-IT25] Planetary cores: Structure, formation, and evolution

Thu. May 30, 2019 10:45 AM - 12:15 PM A09 (TOKYO BAY MAKUHARI HALL)

convener:Hidenori Terasaki(Graduate School of Science, Osaka University), Eiji Ohtani(Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University), William F McDonough(University of Maryland College Park), George Helffrich(Earth-Life Science Institute, Tokyo Institute of Technology), Chairperson:William McDonough(University of Maryland / Tohoku University), Eiji Ohtani(Tohoku University)

11:00 AM - 11:15 AM

[SIT25-07] Ab initio study of Iron-Nickel alloys in Super-Earths cores

*Francois Soubiran1, Razvan Caracas1 (1.Ecole normale superieure de Lyon, Laboratoire de Géologie de Lyon, Université Lyon 1, CNRS UMR 5276, Lyon, France)

Keywords:Super-Earth, iron core, Ab initio simulations

Iron-nickel alloys are considered the main components of Earth and Super-Earth cores, which make them crucial systems in order to comprehend the properties of these planets. While the relative nickel content is anticipated to be around 10% in the Earth, this value could differ slightly in other planets because of different host star metallicity and formation history. It is thus important to understand the properties of iron-nickel systems with various compositions in the multi-megabar regime.

While pure iron is anticipated to have hexagonal close packing at high pressure, nickel is expected to have face-centered cubic packing. This means there is a structural change as the composition is modified, which can also mean a limited stability of the solid solutions of iron-nickel.

We will discuss the properties of iron-nickel alloys in the megabar regime as predicted by ab initio simulations. We will examine the relative stability of different iron-nickel solid solution compositions and the interplay of the spin states. After characterizing the properties of these alloys at pressure-temperature conditions relevant for Super-Earth, we will discuss possible consequences their cores.