Stability and thermoelasticity of iron-rich FenO compound at earth's inner core condition

IF 1.9 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Physics of the Earth and Planetary Interiors Pub Date : 2025-07-21 DOI:10.1016/j.pepi.2025.107419

Guilin Liu , Mei Tang , Zhenwei Niu , Zaixiu Yang

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Abstract

Oxygen is one of the possible light elements in Earth's core, and it is of crucial importance for understanding the evolution of the inner core. Here, we report the stability and thermoelastic properties of iron-rich Fe_nO compounds at 360 GPa up to 7000 K. A series of metastable structures of Fe_nO compounds are predicted with stoichiometric ratio of n = 1–9 at 360 GPa using particle swarm optimization algorithm. Through the analysis of phonon spectra at finite temperatures, we find a new Fe₃O compound with P4/mmm symmetry, which is the only structure that can exist stably at the Earth's inner core condition for Fe_nO (n = 1–9). The thermoelastic properties of Fe₃O at 360 GPa up to 7000 K indicate that the calculated elastic properties, including sound velocities, agree well with those from seismology due to significant anisotropy and elastic softening. However, the density of Fe₃O is much lower than the geophysical data. Therefore, Fe₃O cannot be the major component of the Earth's inner core, and only can be regarded as a minor component.

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地球内核条件下富铁FenO化合物的稳定性和热弹性

氧是地核中可能存在的轻元素之一，对了解地核的演化具有至关重要的意义。在这里，我们报告了富铁的FenO化合物在360 GPa和7000 K下的稳定性和热弹性性能。利用粒子群优化算法预测了在360 GPa下，化学计量比为n = 1-9的一系列FenO化合物的亚稳结构。通过有限温度下的声子光谱分析，我们发现了一种新的具有P4/mmm对称性的fe30o化合物，这是FenO （n = 1-9）在地球内核条件下唯一能稳定存在的结构。在360 GPa ~ 7000 K的温度下，fe30o的热弹性性能表明，计算得到的包括声速在内的弹性性能与地震学结果吻合较好，因为fe30o具有明显的各向异性和弹性软化。然而，fe30的密度远低于地球物理数据。因此，fe30o不可能是地球内核的主要成分，只能看作是一个次要成分。

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来源期刊

Physics of the Earth and Planetary Interiors 地学天文-地球化学与地球物理

CiteScore

5.00

自引率

4.30%

发文量

审稿时长

18.5 weeks

期刊介绍： Launched in 1968 to fill the need for an international journal in the field of planetary physics, geodesy and geophysics, Physics of the Earth and Planetary Interiors has now grown to become important reading matter for all geophysicists. It is the only journal to be entirely devoted to the physical and chemical processes of planetary interiors. Original research papers, review articles, short communications and book reviews are all published on a regular basis; and from time to time special issues of the journal are devoted to the publication of the proceedings of symposia and congresses which the editors feel will be of particular interest to the reader.