Acicular BaCoxTixFe_12-2xO₁₉ (X=O-1.0) particles and their coated films were prepared. The homogeneous mixtures of α-FeOOH, Ba(OH)₂, Co acetylacetonate and Ti acetylacetonate were sintered at 900°C for 3 hrs and then quenched.
The aspect ratio of about 10-15 didn't depend on the amount of the substitution, X. The corecive force linearly decreased with the increase of X. As the sample of X=0.7 had the coercive force of about 1 KOe, it is available for the present magnetic recording medium. The magnetization of these samples was unchanged with X until X=0.7.
The mixture of the acicular particles of X=0.7, dispersing agent and binder resins was coated on the polyestel film in the magnetic field of 7 Be perpendicular to the film. It was confirmed that the long axis of the acicular particles was parallel to the base film by the TEN observation of the cross-section of the coated film. The magnetic anisotropy of acicular BaCoxTixFe_12-2xO₁₉ film is in the direction perpendicular to the film. The acicular hexagonal ferrite particles is applicable to a perpendicular magnetic recording medium.