X-ray Studies on the Ferrite-Haematite Solid Solutions

Abstract

The variation of the lattice dimension of the solid solution system, NiFe₂O₄–Fe₂O₃, and the precipitation process of α–Fe₂O₃ therefrom were investigated by X-ray analysis. These quenched solid solutions possess unstable inhomogeneities originating in the localized oxidization. When annealed at certain temperatures, the solid solution tends to become stabilized by the precipitation of α–Fe₂O₃. The activation energy for the precipitation was found to be ca 1.03 ev.
The solubility of Fe₂O₃ in NiFe₂O₄ was determined at various temperatures, and the heat of dissolution was found to be 1.3 ev.