Existence of a direct phase transformation from haematite to maghemite
- 1 August 1995
- journal article
- research article
- Published by Taylor & Francis in Philosophical Magazine Letters
- Vol. 72 (2) , 105-110
- https://doi.org/10.1080/09500839508241621
Abstract
The observation of a direct phase transformation from haematite α-Fe2O3 (antiferromagnetic) to maghemite γ-Fe2O3 (ferrimagnetic) by the mechanical action of grinding is reported. A simple grinding process is used; it is characterized by the presence of a shearing component exerted on the α-Fe2O3 particles. All crystallographic and magnetic measurements show existence of a phase transformation a - γ. The interpretation is based on a mechanism using two crystallographic concepts: the orientation relationship between the two phases, and movement of the oxygen planes due to a periodic shearing sequence. The results are also consistent with the phenomena related to the inverse transformation γ → α.Keywords
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