DISPROPORTIONATION OF WUSTITE

Mössbauer spectrometry provided a new tool for studies of the mechanism of disproportionation of normally prepared nonstoichiometric wustite, FeOx. The conclusions of these studies are supported by chemical analyses and by X-ray diffraction data. Initially, FeOx disproportionates by forming Fe3O4 using Fe3+ cations already present in the structure plus Fe2+ and O2- ions necessary to form Fe3O4. Stoichiometric wustite, which we designate as FeO1.0, is also formed during this initial stage but no α-Fe is formed. Finally, when all Fe3+ cations initially present have been used to make Fe3O4, FeO1.0 begins to disproportionate forming α-Fe and additional Fe3O4 according to the generally accepted formula: 4FeO → Fe + Fe3O4.