Process for producing microcrystalline Co/Ti-substituted barium ferrite platelets

摘要

A process of producing a spinel structure Ni/Zn ferrite- modified, Co/Ti-substituted microcrystalline barium ferrite platelets having an average particle size of 0.03-0.15 m, a temperature coefficient of coercive force of not more than +1 Oe/ C., including small absolute values in negative region, and a saturated magnetization of not less than 56 emu/g, which comprises: forming substantially amorphous preecursors of Co/Ti-substituted barium ferrites; adding an aqueous solution of nickel salts to the dispersion of the precursors of Co/Ti- substituted barium ferrites, and subjecting the slurry to hydrothermal reaction, thereby to provide precursors of spinel structure nickel ferrite-modified, Co/Ti-substituted barium ferrites; depositing a water insoluble zinc compound on the precursors; and calcining the precursors in the presence of barium chloride, washing the calcined products to remove therefrom the barium chloride, and drying.