FINE POWDER OF BA FERRITE PLATE PARTICLE FOR MAGNETIC RECORDING USE AND ITS PREPARATION

摘要

PURPOSE:To produce the titled fine powder having high intensity of magnetization and suitable as a magnetic material for vertical magnetic recroding, by mixing fine powder of Ba ferrite plate particles with an alkaline suspension of Fe(OH)3, and heating the mixture. CONSTITUTION:(A) The fine plate particles of the compd. of formula {0x=1.2; M is Co(II) [and a bivalent metal ion other than Co(II)]} (average diameter; about 0.05-0.3mu, coercivity; about 300-1,000Oe) are mixed with (B) an alkaline suspension (pH; 8-14) of Fe(OH)3 containing =50atom% Fe(II) based on FeIII) in the component A. The obtained mixture is heat-treated at 50-100 deg.C in a non- oxidizing atmosphere to obtain the powder of plate Ba ferrite particles for magnetic recording use having particle surface modified with magnetite of formula y(FeO).Fe2O3 (0y=1) (intensity of magnetization in magnetic field of 10kOe; about =40 emug-1).