| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1329619 | Journal of Solid State Chemistry | 2015 | 5 Pages |
•The pressure induces similar phase transformation in Co3−xFexO4 spinels (1≤x≤2).•The postspinel phases decompose after releasing pressure.•The irreversibility of this phase transformation explains the disappearance of magnetism in these spinels after applying pressure.•Accurate equation of state can be obtained up to 10 GPa using an alcohol mixture as pressure transmitting medium.•The equation of state suggests similar elastic properties for these spinels in this composition range.
We report high pressure angle-dispersive x-ray diffraction measurements on CoxFe3−xO4 (x=1, 1.5, 1.75) spinels at room temperature up to 34 GPa. The three samples show a similar structural phase transformation from the cubic spinel structure to an analogous post-spinel phase at around 20 GPa. Spinel and post-spinel phases coexist in a wide pressure range (~20–25 GPa) and the transformation is irreversible. The equation of state of the three cubic spinel ferrites was determined and our results agree with the data obtained in related oxide spinels showing the role of the pressure-transmitting medium for the accurate determination of the equation of state.Measurements releasing pressure revealed that the post-spinel phase is stable down to 4 GPa when it decomposes yielding a new phase with poor crystallinity. Later compression does not recover either the spinel or the post-spinel phases. This phase transformation induced by pressure explains the irreversible lost of the ferrimagnetic behavior reported in these spinels.
Graphical abstractPressure dependence of the unit cell volume per formula unit for Co1.5Fe1.5O4 spinel. Circles and squares stand for spinel and postspinel phases, respectively. Dark (open) symbols: determination upon compression (decompression).Figure optionsDownload full-size imageDownload as PowerPoint slide
