Free Energies of Fe‐O‐Si Ternary Liquids at High Temperatures and Pressures: Implications for the Evolution of the Earth's Core Composition
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Authors
Zhang, Zhigang
Csányi, Gábor
Alfè, Dario
Zhang, Yigang
Li, Juan
Liu, Jin
Publication Date
2022-02-28Journal Title
Geophysical Research Letters
ISSN
0094-8276
Publisher
American Geophysical Union (AGU)
Volume
49
Issue
4
Type
Article
This Version
AM
Metadata
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Zhang, Z., Csányi, G., Alfè, D., Zhang, Y., Li, J., & Liu, J. (2022). Free Energies of Fe‐O‐Si Ternary Liquids at High Temperatures and Pressures: Implications for the Evolution of the Earth's Core Composition. Geophysical Research Letters, 49 (4) https://doi.org/10.1029/2021gl096749
Abstract
Solubility of oxygen and silicon in the iron-alloying liquids is important for constraining the core composition over the Earth's history. In this study, we systematically simulated the free energies of Fe-O-Si ternary liquids from 3000 K, 55 GPa to 6000 K, and 330 GPa. We found that temperature and pressure have remarkable influences on the free energies, and the nonideality of mixing is important for the chemical potentials even at high temperatures. Equilibrating with SiO$_{2}$ phase, Fe-O-Si liquids significantly enhance the solubility of Si and O simultaneously with increasing temperature. Considering the secular cooling of the Earth's core, this leads to high precipitation rates of SiO$_{2}$ once it was saturated, which would efficiently drive ancient geodynamo. If the evolution of Earth's core started from an oxygen-poor composition, later incorporations of oxygen seem to be needed to reach a core composition compatible with geophysical observations.
Identifiers
External DOI: https://doi.org/10.1029/2021gl096749
This record's URL: https://www.repository.cam.ac.uk/handle/1810/334742
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