ES22-Zhuang-1

Author: Zhuang, Jingyi - Columbia University, Lamont-Doherty Earth Observatory, Palisades

Title: Spin crossover in ferropericlase: beyond ideal solid solution model

Abstract: The pressure- and temperature-induced high spin (HS) to low spin (LS) crossover of Fe2+ ions in ferropericlase (Fp), Mg(1-x)FexO, affects mantle properties such as density, elasticity, thermal properties, iron partitioning between Fp and other co-existing phases, etc. It further affects how we interpret lower mantle observations. Here, we present results of thermodynamic properties computed using a free energy model that goes beyond the ideal HS-LS solid solution framework. As in the past, ab initio calculations were performed using the DFT+ USC method with structure and electronic configuration dependent USC. Results show the influence of iron-iron interactions (elastic or exchange type) on the pressure range of the crossover. Comparison with available experimental data shows considerably improved agreement over that of the ideal solid solution model.

Other authors: Sun, Yang, Columbia University, Lamont-Doherty Earth Observatory, Palisades Wentzcovitch, Renata M., Columbia University, Department of Applied Physics and Applied Mathematics