| 摘要 |
PURPOSE:To obtain the titled fine powder having specified mean particle size and large value of magnetization and appropriate coercive force suitable for the magnetic material for (perpendicular) magnetic recording by forming fine platy Ba ferrite particles having dissolved Zn on the surface of the particles. CONSTITUTION:Fine platy Ba ferrite particles deposited with hydroxide of Zn on the surface are obtd. by suspending fine particles of platy BaO.nFe2O3 (4<=n<=8) and fine platy Ba ferrite particles contg. a coercive force reducing agent in accordance with demand in an aq. soln. contg. Zn having 4.0-12.0pH prepd. by dissolving ZnCl2, Zn(NO3)2, ZnSO4, or Zn(OAc)2, etc., in water. Then, the platy Ba ferrite particles are separated by filtration and dried. If necessary, the surface of the particles is coated with an Si compd. or Al compd. having sintering inhibiting effect, then calcined by heating at 600-900 deg.C to obtain thus the titled fine particles having 0.05-0.3mu mean particle size and 300-1,000Oe coercive force, contg. 0.2-5.0wt% Zn dissolved in the solid state on the surface of the particles. |
