Iron-rich Fe-O compounds with closest-packed layers at core pressures

2021/10/01 by Jin Liu, Yang Sun, Liu, Jin +17
Earth and Planetary Sciences · Materials Science · #Crystal Structures and Properties #FOS: Physical sciences #Geological and Geochemical Analysis #Geophysics (physics.geo-ph) #High-pressure geophysics and materials #Materials Science (cond-mat.mtrl-sci)

paper · pdf · doi:10.48550/arxiv.2110.00524

openalex publication_date 2021/10/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Oxygen solubility in solid iron is extremely low, even at high pressures and temperatures. Thus far, no Fe-O compounds between Fe and FeO endmembers have been reported experimentally. We observed chemical reactions of Fe with FeO or Fe₂O₃ in situ x-ray diffraction experiments at 220-260 GPa and 3,000-3,500 K. The refined diffraction patterns are consistent with a series of Fe_nO (n > 1) compounds (e.g., Fe₂₅O₁₃ and Fe₂₈O₁₄) identified using the adaptive genetic algorithm. Like ε-Fe in the hexagonal close-packed (hcp) structure, the structures of Fe_nO compounds consist of oxygen-only close-packed monolayers distributed between iron-only layers. Ab initio calculations show systematic electronic properties of these compounds that have ramifications for the physical properties of Earth's inner core.

Citations

• The composition of the Earth
• Projector augmented-wave method
• Efficient iterative schemes forab initiototal-energy calculations using a plane-wave basis set

Related

• Tetragonal Fe2O: the stable iron oxide at Earth's core conditions
• Computational searches for iron oxides at high pressures
• Structural evolution of iron oxides melts at Earth's outer-core pressures
• Reverse chemistry of iron in the deep Earth
• Experimental evidence of a body centered cubic iron at the Earth's core condition