METHOD OF PRODUCTION OF BARIUM FERRITE POWDER Russian patent published in 1997 - IPC

FIELD: production of ferrite powders, particular, method of production of highly dispersed powder of hexagonal barium ferrite and plate-like barium-base ferrites applicable in manufacture of carrier of high-density magnetic record, flexible high-energy permanent magnets and also SHF devices. SUBSTANCE: the offered method includes treatment of oxide γ-Fe₂O₃ with pulsed magnetic field with magnetic flux density of 0.1-3 T, grinding and mixing of ferrite-forming components and flux, ferritization of mixture by heating up to 900-980 C. Novelty of the method consists in that mixture is heated by radiation with electron beam with energy of 1.0-1.4 MeV and dose of (2.8-6.0)x10¹³cm^-2. The offered method provides for production of single-domain plate-like particles of powder hexagonal in shape with higher diameter-to-thickness ratio (d/h ~ 7-10) and optimal magnetic parameters (magnetization, crystalline magnetic anisotropy, Curie paramagnetic temperature, coercive force) with less quantity of substituting ions (by 25%, cobalt and titanium in the given case) due to acceleration of diffusion capability of ferrite-forming ions by combination of thermal and radiation treatment. EFFECT: improved quality of produced powder due to increased diameter-thickness ratio with preservation of values of magnetic parameter. 1 tbl