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Stability and anisotropy of (Fe(x)Ni(1−x))(2)O under high pressure and implications in Earth’s and super-Earths’ core

Oxygen is thought to be an important light element in Earth’s core but the amount of oxygen in Earth’s core remains elusive. In addition, iron-rich iron oxides are of great interest and significance in the field of geoscience and condensed matter physics. Here, static calculations based on density f...

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Detalles Bibliográficos
Autores principales: Huang, Shengxuan, Wu, Xiang, Qin, Shan
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5762755/
https://www.ncbi.nlm.nih.gov/pubmed/29321631
http://dx.doi.org/10.1038/s41598-017-18678-z
Descripción
Sumario:Oxygen is thought to be an important light element in Earth’s core but the amount of oxygen in Earth’s core remains elusive. In addition, iron-rich iron oxides are of great interest and significance in the field of geoscience and condensed matter physics. Here, static calculations based on density functional theory demonstrate that I4/mmm-Fe(2)O is dynamically and mechanically stable and becomes energetically favorable with respect to the assemblage of hcp-Fe and [Formula: see text] -FeO above 270 GPa, which indicates that I4/mmm-Fe(2)O can be a strong candidate phase for stable iron-rich iron oxides at high pressure, perhaps even at high temperature. The elasticity and anisotropy of I4/mmm-(Fe(x)Ni(1−x))(2)O at high pressures are also determined. Based on these results, we have derived the upper limit of oxygen to be 4.3 wt% in Earth’s lower outer core. On the other hand, I4/mmm-(Fe(x)Ni(1−x))(2)O with high AV (S) is likely to exist in a super-Earth’s or an ocean planet’s solid core causing the locally seismic heterogeneity. Our results not only give some clues to explore and synthesize novel iron-rich iron oxides but also shed light on the fundamental information of oxygen in the planetary core.