SYNTHESIS OF FERRITE CONTAINING DIVALENT IRON ION

PURPOSE:To obtain the title ferrite whose production has been considered impos sible by the conventional dry process by pulverizing a powder mixture consisting of pulverous Fe2O3 and divalent metal oxide in a specified compositional ratio, mixing the pulverized product, compression molding the mixture, calcining in the air, and calcining further in vacuum. CONSTITUTION:A ferrite of a divalent metal (Mi) is prepd. from the above described compression molded product consisting of an oxide of Mi and Fe2O3 (hematite) in accordance with the following reaction formula: MiO+Fe2 O3 MiFe2O4 (I). Succeedingly, Fe3O4 (magnetite) is prep. from residual Fe2O3 at high temp. in vacuum in accordance with the reaction formula (II): Fe2O3 Fe3 O4+1/202 (II). Aimed ferrite contg. Fe ions is obtnd. thereafter by allowing MiFe2O4 obtd. by formula (I) to react with Fe3O4 obtd. by formula (II) in accor dance with the reaction formula: xFe3O4+(1-x)MiFe2O4 (FexMi1-x)Fe2O4 (III). Suitable MiO is, for example, NiO. A ferrite contg. divalent Fe ions and having an optional shape and high purity is obtd. in a short time by the method of this invention.