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Altered chemistry of oxygen and iron under deep Earth conditions.

ABSTRACT: A drastically altered chemistry was recently discovered in the Fe-O-H system under deep Earth conditions, involving the formation of iron superoxide (FeO2Hx with x?=?0 to 1), but the puzzling crystal chemistry of this system at high pressures is largely unknown. Here we present evidence that despite the high O/Fe ratio in FeO2Hx, iron remains in the ferrous, spin-paired and non-magnetic state at 60-133?GPa, while the presence of hydrogen has minimal effects on the valence of iron. The reduced iron is accompanied by oxidized oxygen due to oxygen-oxygen interactions. The valence of oxygen is not -2 as in all other major mantle minerals, instead it varies around -1. This result indicates that like iron, oxygen may have multiple valence states in our planet's interior. Our study suggests a possible change in the chemical paradigm of how oxygen, iron, and hydrogen behave under deep Earth conditions.

SUBMITTER: Liu J

PROVIDER: S-EPMC6329810 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Altered chemistry of oxygen and iron under deep Earth conditions.

Liu Jin J Hu Qingyang Q Bi Wenli W Yang Liuxiang L Xiao Yuming Y Chow Paul P Meng Yue Y Prakapenka Vitali B VB Mao Ho-Kwang HK Mao Wendy L WL

Nature communications 20190111 1

A drastically altered chemistry was recently discovered in the Fe-O-H system under deep Earth conditions, involving the formation of iron superoxide (FeO<sub>2</sub>Hx with x = 0 to 1), but the puzzling crystal chemistry of this system at high pressures is largely unknown. Here we present evidence that despite the high O/Fe ratio in FeO<sub>2</sub>Hx, iron remains in the ferrous, spin-paired and non-magnetic state at 60-133 GPa, while the presence of hydrogen has minimal effects on the valence o ...[more]

PMID: 30635572

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