High-pressure phase transition of hematite, Fe2O3 Original Research Article

Structural phase transitions of iron oxide (Fe2O3) have been investigated at pressures up to 70 GPa and temperatures above 2500 K, using a laser-heated diamond anvil cell technique. A phase transition between α-Fe2O3 (hematite) and perovskite-type Fe2O3 was observed at about 30 GPa. At pressures higher than 50 GPa, we also observed the occurrence of a new high-pressure phase of Fe2O3. Diffraction peaks of the new high-pressure phase can be indexed on the basis of orthorhombic or monoclinic symmetries that are denser than other known Fe2O3 phases. The volume change from perovskite-type to the new high-pressure phase is about 7%.