1. Phase transitions of Fe$_2$O$_3$ under laser shock compression
- Author
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Amouretti, A., Crépisson, C., Azadi, S., Cabaret, D., Campbell, T., Chin, D. A., Colin, B., Collins, G. R., Crandall, L., Fiquet, G., Forte, A., Gawne, T., Guyot, F., Heighway, P., Lee, H., McGonegle, D., Nagler, B., Pintor, J., Polsin, D., Rousse, G., Shi, Y., Smith, E., Wark, J. S., Vinko, S. M., and Harmand, M.
- Subjects
Condensed Matter - Materials Science - Abstract
We present in-situ x-ray diffraction and velocity measurements of Fe$_2$O$_3$ under laser shock compression at pressures between 38-116 GPa. None of the phases reported by static compression studies were observed. Instead, we observed an isostructural phase transition from $\alpha$-Fe$_2$O$_3$ to a new $\alpha^\prime$-Fe$_2$O$_3$ phase at a pressure of 50-62 GPa. The $\alpha^\prime$-Fe$_2$O$_3$ phase differs from $\alpha$-Fe$_2$O$_3$ by an 11% volume drop and a different unit cell compressibility. We further observed a two-wave structure in the velocity profile, which can be related to an intermediate regime where both $\alpha$ and $\alpha^\prime$ phases coexist. Density functional theory calculations with a Hubbard parameter indicate that the observed unit cell volume drop can be associated with a spin transition following a magnetic collapse., Comment: 7 pages, 5 figures
- Published
- 2024