Pressure Induced Phase Transition of Nanocrystalline and Bulk Maghemite (g-Fe2O3) to Hematite (a-Fe2O3)
Phase transition and bulk moduli of bulk and nanocrystalline {gamma}-Fe{sub 2}O{sub 3} were studied using synchrotron X-ray diffraction under high pressure. Contrary to most other nanomaterials, nanocrystalline {gamma}-Fe{sub 2}O{sub 3} begins to transform into {alpha}-Fe{sub 2}O{sub 3} at the same pressure as bulk {gamma}-Fe{sub 2}O{sub 3}, which is caused by a special structure of {gamma}-Fe{sub 2}O{sub 3}, in which there exist vacancies of crystal. It is believed that phase transition starts from a certain site of vacancy because of the stress concentration at vacancy sites. Compared to bulk material, nanocrystalline {gamma}-Fe{sub 2}O{sub 3} has a larger bulk modulus, which is ascribed to the large ratio of surface to volume.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- DOE - OFFICE OF SCIENCE
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1019994
- Report Number(s):
- BNL-95782-2011-JA; JPCSAW; TRN: US201115%%630
- Journal Information:
- Journal of Physics and Chemistry of Solids, Vol. 71, Issue 8; ISSN 0022-3697
- Country of Publication:
- United States
- Language:
- English
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