Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, People's Republic of China.
Korea Institute for Advanced Study, Seoul 02455, Korea.
J Phys Chem Lett. 2023 Apr 27;14(16):3884-3890. doi: 10.1021/acs.jpclett.3c00500. Epub 2023 Apr 18.
Earth's inner core (IC) consists of mainly iron with some light elements. Understanding its structure and related physical properties has been elusive as a result of its required extremely high pressure and temperature conditions. The phase of iron, elastic anisotropy, and density-velocity deficit at the IC have long been questions of great interest. Here, we find that the electron correlation effect is enhanced by oxygen and modifies several important features, including the stability of iron oxides. Oxygen atoms energetically stabilize hexagonal-structured iron at IC conditions and induce elastic anisotropy. Electrical resistivity is much enhanced in comparison to pure hexagonal close-packed (hcp) iron as a result of the enhanced electron correlation effect, supporting the conventional thermal convection model. Moreover, our calculated seismic velocity shows a quantitative match with geologically observed preliminary reference Earth model (PREM) data. We suggest that oxygen is the essential light element to understand and model Earth's IC.
地球的内核（IC）主要由铁和一些轻元素组成。由于其所需的极高压力和温度条件，其结构和相关物理性质一直难以捉摸。铁的相、弹性各向异性以及内核的密度-速度亏损长期以来一直是人们非常感兴趣的问题。在这里，我们发现氧增强了电子相关效应，并改变了包括铁氧化物稳定性在内的几个重要特征。氧原子在 IC 条件下使六方结构的铁稳定，并引起弹性各向异性。由于电子相关效应的增强，电阻率比纯六方密堆积（hcp）铁大大增强，这支持了传统的热对流模型。此外，我们计算的地震速度与地质上观测到的初步参考地球模型（PREM）数据定量匹配。我们认为，氧是理解和模拟地球内核的必需轻元素。
