Precipitation of nickel ferrites: Nature of intermediate reaction steps

One of the reactions, by which substituted ferrites are formed, (controlled oxidation by nitrates of Fe2+ in the presence of the substituent cations) is examined using the data referring to the precipitation of a family of nickel ferrous ferrites. The precipitation of all the oxides involves two distinctly different pH regimes connected by a very sharp pH transition. The transition occurs for only fractional additions of the oxidizing ions and is a continuons function of the Ni Fetot ratio.