Transformation of goethite to maghaemite in CsI disks [9]

THE formation and stability of γ-Fe₂O₃ (maghaemite) is still a puzzle, as this oxide is metastable with respect to its isomorphic form α-Fe₂O₃ (haematite). However, there are increasing reports about its natural occurrence in certain soils and sediments (see ref. 1 and refs therein). Maghaemite, like magnetite, Fe ₃O₄, is ferrimagnetic and its artificial occurrence may therefore be important in carrying out magnetic concentrations in various processes of iron ores industry²; as well as finding widespread application in the electronic industry³. The artificial preparation of maghaemite is usually carried out by low temperature dehydration of lepidocrocite⁴, γ-FeOOH, or careful oxidation of powdered magnetite^5,6.