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07:26
Synthesis and Microdiffraction at Extreme Pressures and Temperatures
Published on: October 7, 2013
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Structural complexity of simple Fe2O3 at high pressures and temperatures
E Bykova1,2, L Dubrovinsky1, N Dubrovinskaia2
1Bayerisches Geoinstitut, University of Bayreuth, Universitaetsstrasse 30, D-95447 Bayreuth, Germany.
Nature Communications
|February 12, 2016
Summary
High-pressure, high-temperature studies reveal iron oxide (Fe2O3) transformations, forming new phases like Fe5O7 and Fe25O32. These findings suggest mixed-valence iron oxides are key to Earth's oxygen cycling.
Area of Science:
- Geochemistry
- Materials Science
- Mineral Physics
Background:
- Iron oxide (Fe2O3) exhibits complex behavior under extreme conditions.
- Previous studies lacked structural data for high-pressure, high-temperature transformations.
Purpose of the Study:
- To systematically investigate the behavior of Fe2O3 at pressures >100 GPa and temperatures >2,500 K.
- To elucidate the structural, electronic, and magnetic transformations of Fe2O3.
Main Methods:
- Single crystal X-ray diffraction.
- Synchrotron Mössbauer source spectroscopy.
Main Results:
- Observed decomposition of Fe2O3 and Fe3O4 above 60 GPa and 2,000 K.
- Identified novel iron oxide phases: Fe5O7 and Fe25O32, with oxygen release.
- Established relationships between Fe(II, III) oxides via the homologous series nFeO·mFe2O3.
Conclusions:
- Mixed-valence iron oxides play a crucial role in Earth's oxygen cycling.
- New structural data clarifies enigmatic transformations in Fe2O3.
- Understanding these phases is vital for geochemistry and materials science.
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