PLATE SR FERRITE FINE PARTICLE POWDER FOR MAGNETIC RECORDING USE AND PRODUCTION THEREOF

摘要

PURPOSE:To improve the intensity of magnetization of the subject powder by mixing plate SrFe12O19 fine particles with a specific alkaline suspension and heat-treating the mixture to form a spinel-type iron oxide layer on the surface layer of the plate SrFe12O19 fine particle. CONSTITUTION:Plate SrFe12O19 fine particles are mixed with an alkaline suspen sion having pH of >=9 and containing <=50atom% (based on the total Fe(III) in the fine particle) of Fe(II). The mixed liquid is stirred under heating at 50-100 deg.C and the formed dark brown powder is filtered, washed with water and dried to obtain magnetic recording powder of plate Sr ferrite fine particle having a spinel-type iron oxide layer (Fe3-x/3squarex/3O4; x<1) formed on the surface of the fine particle of the plate Sr ferrite [6yFe3-x/3squarex/3O4.(1-y) SrFe12O19; y<1; square is Fe ion hole].