Studies on the formation of zinc ferrite

The reactions of zinc oxide with α-Fe2O3 and with γ-Fe2O3 leading to the formation of zinc ferrite (ZnFe2O4) have been studied at different partial pressures of oxygen in the temperature range 500-800°C. The ferrite spinel is formed more readily when γ-Fe2O3 is used as the reactant. The DTA and X-ray diffraction results indicate that the γ-Fe2O3 phase is stabilized in presence of ZnO. The lowering of partial pressure of oxygen in the ambient atmosphere favours the formation of zinc ferrite, indicating a cyclic redox process featuring Fe3+, Fe2+ and oxygen at the phase boundaries. At very low oxygen pressures, conversion to zinc ferrite is not facilitated, apparently due to the formation of an intermediate species, Fe3-xZnxO4, which, under these conditions, is not easily converted to ZnFe2O4. © 1974.