Isostructural phase transition of Fe2O3 under laser shock compression
Physical Review Letters American Physical Society
Authors:
Alexis Amouretti, Celine Crepisson, Sam Azadi, Francois Brisset, Delphine Cabaret, Thomas Campbell, David Chin, Gilbert Rip Collins, Linda Hansen, Guillaume Fiquet, Alessandro Forte, Thomas Gawne, Francois Guyot, Patrick Heighway, Eva Heripre, Eric Cunningham, Hae Ja Lee, David McGonegle, Bob Nagler, Juan Pintor, Danae Polsin, Gaelle Rousse, Yuanfeng Shi, Ethan Smith, Justin Wark, Sam Vinko, Marion Harmand
Abstract:
We present in-situ x-ray diffraction and velocity measurements of Fe2O3 under laser shock compression at pressures between 38-122 GPa. None of the high-pressure phases reported by static
compression studies were observed. Instead, we observed an isostructural phase transition from
α-Fe2O3 to a new α′
-Fe2O3 phase at a pressure of 50-62 GPa. The α′
-Fe2O3 phase differs from
α-Fe2O3 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 α and α′ 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.
