Evidence for the charge disproportionation of iron in extraterrestrial bridgmanite

Luca Bindi, Sang Heon Shim, Thomas G. Sharp, Xiande Xie

Abstract

Bridgmanite, MgSiO3 with perovskite structure, is considered the most abundant mineral on Earth. On the lower mantle, it contains Fe and Al that strongly influence its behavior. Experimentalists have debated whether iron may exist in a mixed valence state, coexistence of Fe2+ and Fe3+ in bridgmanite, through charge disproportionation. Here, we report the discovery of Fe-rich aluminous bridgmanite coexisting with metallic iron in a shock vein of the Suizhou meteorite. This is the first direct evidence in nature of the Fe disproportionation reaction, which so far has only been observed in some high-pressure experiments. Furthermore, our discovery supports the idea that the disproportionation reaction would have played a key role in redox processes and the evolution of Earth.

Original languageEnglish (US)
Article numbereaay7893
JournalScience Advances
Volume6
Issue number2
DOIs
Publication statusPublished - Jan 10 2020

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