The transformation of ferrihydrite into goethite or hematite, revisited
- Groupe de Recherche en Chimie et Metallurgie, Institut National des Sciences Appliquees de Rennes, 20 avenue des buttes de Coesmes, 35043 Rennes cedex (France)
During the oxidation of iron, poorly crystallized phases are firstly formed: 2- and 6-line ferrihydrite, which presents for the last phase, a similarity with wustite FeO but also with hematite {alpha}-Fe{sub 2}O{sub 3}. Crystallization increases with time and the solid phase obtained is dependent on temperature and pH. Obviously, high temperature favours the formation of the oxide hematite {alpha}-Fe{sub 2}O{sub 3}. As for the pH factor, it is more complicated. Low and high values of pH (2-5 and 10-14) favour the formation of goethite {alpha}-FeOOH, while obtaining hematite is favoured at neutral pH (values around 7). Goethite or hematite are obtained either through a dissolution-crystallization process or in the solid state, through a topotactic transformation. Given the structural relationships observed between ferrihydrite and wustite and hematite, it is allowed to think that a structural continuity could exist between wustite Fe{sub (1-} {sub x} {sub )}O and hematite via ferrihydrite.
- OSTI ID:
- 20784914
- Journal Information:
- Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 3 Vol. 179; ISSN 0022-4596; ISSN JSSCBI
- Country of Publication:
- United States
- Language:
- English
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