| 摘要 |
PURPOSE:To provide a magnetic recording medium enabling satisfactory high density recording by forming a magnetic layer contg. magnetic hexagonal ferrite powder of a specified average single particle size having chlorine stuck to the surface by a specified amount. CONSTITUTION:An aqueous alkali soln. is added to an aqueous soln. contg. an iron salt and one or more kinds of metallic salts selected among Ba salts, Sr salts and Pb salts to cause coprecipitation. The resulting precipitate is hydrothermally treated to produce fine hexagonal ferrite particles of <=0.3mum average single particle size, and the particles are heat treated in a chloride flux at a temp. above the m.p. of the flux. Chlorine is stuck to the surfaces of the particles by 0.3-2wt%, sintering is not caused among the particles, and magnetic hexagonal ferrite powder having a large extent of saturation magnetization, superior dispersibility and superior orienting properties is obtd. in the form of hyperfine particles of <=0.3mum average single particle size. When the magnetic powder is used, a magnetic recording medium enabling satisfactory high density recording is obtd.
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