High-Pressure Evolution of Crystal Bonding Structures and Properties of FeOOH,The Journal of Physical Chemistry Letters

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High-Pressure Evolution of Crystal Bonding Structures and Properties of FeOOH
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2018-04-12 00:00:00 , DOI: 10.1021/acs.jpclett.8b00947
Cheng Lu ₁ , Changfeng Chen ₁

Affiliation

Recent conflicting reports on the high-pressure structural evolution of iron oxide-hydroxide (FeOOH) offer starkly contrasting scenarios for the hydrogen and oxygen cycles in Earth’s interior. Here we explore the crystal structures of FeOOH using an advanced search algorithm combined with first-principles calculations. Our results indicate a phase transition around 70 GPa from the known ε-FeOOH to a new pyrite-type FeOOH (P-FeOOH) phase, and the two phases remain nearly degenerate in an unusually large pressure range. These findings clarify and explain the experimentally observed structural evolution and extensive phase coexistence. Moreover, our structure search identifies a previously unknown monoclinic (M-FeOOH) phase that is energetically close to P-FeOOH at pressures near the core-mantle boundary. We further reveal that the high-pressure FeOOH phases exhibit remarkably distinct sound-velocity profiles, providing key material properties essential to interpreting seismic data and elucidating FeOOH’s influence on geophysical and geochemical processes in deep Earth.

中文翻译：

晶体结合结构的高压演化及FeOOH的性能

关于氧化铁-氢氧化物（FeOOH）高压结构演变的最新矛盾报告为地球内部的氢和氧循环提供了截然不同的方案。在这里，我们使用先进的搜索算法结合第一性原理计算来探索FeOOH的晶体结构。我们的结果表明，从已知的ε-FeOOH到新的黄铁矿型FeOOH（P-FeOOH）相约有70 GPa的相变，并且这两个相在异常大的压力范围内仍几乎退化。这些发现澄清和解释了实验观察到的结构演变和广泛相共存。此外，我们的结构搜索确定了一个以前未知的单斜相（M-FeOOH），该相在压力接近岩心幔边界时在能量上接近P-FeOOH。

更新日期：2018-04-12

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