Advances in fine magnetic particles for high density recording

Fine platelet particles of barium ferrite were prepared by the hydrothermal precipitation technique. The magnetic properties such as magnetization, coercivity and temperature variation of the coercivity can be controlled by the selection of the substitution elements. Non-stoichiometric Co²⁺-Ti⁴⁺ substitution yields the formation of the fine particles, and further the replacement of Co ²⁺ by Ni²⁺ reduces the temperature variation degree of the coercivity. These fine particles are thought to be good candidates for high density recording. Furthermore, we briefly discuss the preparation procedure of fine α-Fe acicular particles