An Electron Diffraction Study and a Theory of the Transformation from γ-Fe₂O₃ to α-Fe₂O₃

抄録

Phase transformation of γ-Fe₂O₃ to α-Fe₂O₃ was studied by electron diffraction. Above 400°C γ-Fe₂O₃ is transformed to α-form which consists of twins. The orientation relationship of the transformation is (111)_γ//(0001)_α and [1\bar10]_γ//[01\bar10]_α. The twinning plane of transformation product was determined to be basal or (01\bar10) Plane. The transformation mechanism consists of the re-stacking of close-packed oxygen ion layers and the synchronous displacement of ferric ions located at the interstices of oxygen. These cooperative movements are discussed by dislocation models.