In situ observation of the breakdown of magnetite (Fe3O4) to Fe4O5 and hematite at high pressures and temperatures

2012/09/24 by Alan B. Woodland, A. B. Woodland, D. J. Frost +5 · 6 citations
Earth and Planetary Sciences · Materials Science · Engineering · #High-pressure geophysics and materials #X-ray Diffraction in Crystallography #Metallurgical Processes and Thermodynamics

paper · doi:10.2138/am.2012.4270

Abstract

In situ synchrotron X-ray powder diffraction measurements using a Paris-Edinburgh pressure cell were performed to investigate the nature of the high-pressure breakdown reaction of magnetite (Fe3O4). Refinement of diffraction patterns reveals that magnetite breaks down via a disproportionation reaction to Fe4O5 and hematite (Fe2O3) rather than undergoing an isochemical phase transition. This result, combined with literature data indicates (1) that this reaction occurs at ~9.5-11 GPa and 973-1673 K, and (2) these two phases should recombine at yet higher pressures to produce an h-Fe3O4 phase.

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• Pressure tuning of charge ordering in iron oxide. [europepmc]
• Verwey-Type Charge Ordering and Site-Selective Mott Transition in Fe 4 O 5 under Pressure. [europepmc]
• Post-spinel-type AB 2 O 4 high-pressure phases in geochemistry and materials science. [europepmc]

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