Stability and nature of the volume collapse of ε-Fe<sub>2</sub>O<sub>3</sub> under extreme conditions.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30385756.
- Also identified by DOI 10.1038/s41467-018-06966-9 and PMC identifier 6212538.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Iron oxides are among the major constituents of the deep Earth's interior. Among them, the epsilon phase of Fe<sub>2</sub>O<sub>3</sub> is one of the less studied polymorphs and there is a lack of information about its structural, electronic and magnetic transformations at extreme conditions. Here we report the precise determination of its equation of state and a deep analysis of the evolution of the polyhedral units under compression, thanks to the agreement between our experiments and ab-initio simulations. Our results indicate that this material, with remarkable magnetic properties, is stable at pressures up to 27 GPa. Above 27 GPa, a volume collapse has been observed and ascribed to a change of the local environment of the tetrahedrally coordinated iron towards an octahedral coordination, finding evidence for a different iron oxide polymorph.