Structural–chemical transformations of α-Fe2O3 upon transport reduction

Transient regions between iron oxide crystalline phases were found in various stages of α-Fe2O3 structural–chemical transformation into FeO by Mössbauer spectroscopy. Particle sizes in those regions are less than 8 nm. The sequence of phase transformations was established for α-Fe2O3 reduction to iron at temperatures higher and lower than the wustite stability point (∼570°C). Two phases Fe1−xO and FeO were found to form upon the reduction within the wustite stability region (the stoichiometric phase is formed first). It was shown that reduction of hematite into magnetite occurs within temperature range 570–600°C by the multistage mechanism, while magnetite reduction to wustite occurs by a zonal mechanism, where three phases Fe3O4, FeO and Fe are present in a sample simultaneously.