High Pressure Study on Natural Chromite
Abstract
Spinel phase is generally found at crust and upper mantle. Moreover, spinel phase and its modified form play an important role at transition zone and therefore are geologically importance. Besides, spinel phase usually exhibits with solid-solution from a wide range of different size of cations and therefore study of the substation of cations within spinel structure and its high-pressure form are important to better understand the structure and evolution of the deep mantle. In this study, a natural chromite sample, a Cr-rich spinel and an important resource for chromium and iron, was investigated in a diamond anvil cell using synchrotron x-ray diffraction and Raman spectroscopy. In situ synchrotron x-ray diffraction was performed at GSECARS, Advance Photon Source and X17C, National Synchrotron Light Source. Our high-pressure x-ray diffraction study showed a new phase emerging at about 20 GPa which is slightly higher than previously reported transition pressure at about 12 GPa when using a synthetic chromite sample. Furthermore, our Raman study on chromite also did not observe any phase transition at 12 GPa. Instead, our Raman data shows several broad peaks at ambient and continuously observed at high pressures till 30 GPa. Above 30 GPa, the Raman signals of chromite showed new feature and became very weak. Our results suggest that the impurity within chromite may play a critical role for the phase transition.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMMR23B2359S
- Keywords:
-
- 3924 MINERAL PHYSICS High-pressure behavior;
- 3954 MINERAL PHYSICS X-ray;
- neutron;
- and electron spectroscopy and diffraction;
- 3929 MINERAL PHYSICS NMR;
- Mossbauer spectroscopy;
- and other magnetic techniques;
- 6250 PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS Moon