Title

High-Pressure Evolution of Crystal Bonding Structures and Properties of FeOOH

Document Type

Article

Publication Date

4-12-2018

Publication Title

Journal of Physical Chemistry Letters

Volume

9

First page number:

2181

Last page number:

2185

Abstract

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.

Keywords

Calculations; High pressure effects; High pressure engineering; Iron oxides; Pyrites; Seismology

Disciplines

Chemistry | Earth Sciences

Language

English

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