Abstract
Acicular cobalt ferrite fine particles were prepared by using conventional ceramic method. Acicular α-FeOOH and C10H14O4Co⋅2H2O were sintered at 900°C for 5 hours in air, and then were quenched. The acicular cobalt ferrite fine particles, length of about 1.2μm and an aspest ratio of about 12, had coercivity of 1 kOe (80 kA/m) and magnetization values of 67 emu/g (0.45 Wb/m2). Therefore, they were applicable to magnetic recording medium. The torque curve of a coated film which were admixed with the fine particles and binders indicated the magnetic anisotropy of the fine particles was in the direction parallel to long axis of them. The magnetic anisotropy constant was 1.22 × 103 J/m3. The acicular fine particles had several crystallites, which were arranged parallel to <111> direction of spinet structure.
