Nature of the High-Pressure Transition in Fe2O3 Hematite

James Badro (1, 2) , Guillaume Fiquet (1, 2) , Viktor V Struzhkin (3) , Maddury Somayazulu (3) , Ho-Kwang Mao (3) , Guoyin Shen (4) , Tristan Le Bihan (5)

1 IPGP - Institut de Physique du Globe de Paris
2 IMPMC - Institut de minéralogie, de physique des matériaux et de cosmochimie
3 Geophysical Laboratory [Carnegie Institution]
4 GSECARS
5 ESRF - European Synchrotron Radiation Facility

We present a new method to separate the crystallographic and electronic phase transitions in hematite using x-ray emission spectroscopy and x-ray diffraction. Our observations, based on the behavior of a metastable high-pressure phase in the stability domain of the low-pressure phase, show that the electronic transition is preempted by the crystallographic transition. The former occurs only afterwards in the high-pressure phase, possibly as a result of a Mott transition. The idea that the electronic transition drives the transition in hematite is therefore invalidated. Such methods should help elucidate the mechanics and the driving forces behind a number of first-order high-pressure phase transitions.

Domains: Physics [physics]; Condensed Matter [cond-mat]; Sciences of the Universe [physics]; Earth Sciences; Mineralogy

James Badro, Guillaume Fiquet, Viktor V Struzhkin, Maddury Somayazulu, Ho-Kwang Mao, et al.. Nature of the High-Pressure Transition in Fe2O3 Hematite. Physical Review Letters, 2002, 89 (20), pp.205504. ⟨10.1103/PhysRevLett.89.205504⟩. ⟨insu-01387452⟩