| 摘要 |
PURPOSE:To obtain barium ferrite of fine-grain for high density vertical magnetic recording, by performing a heat treatment of barium ferrite powder added with low melting point oxide at a specified temperature range in the air. CONSTITUTION:Iron, barium, etc., are dissolved by a composition wherein hexagonal barium ferrite is produced, a solution containing excessively alkali hydroxide more than or equal to 30 mol/1 as compared with reaction equivalent to metal salt is kept at a temperature higher than or equal to 70 deg.C and mixed by stirring. After that, the produced slurry is introduced into an auto-clape, and treated at a temperature of 130-250 deg.C. After the produced deposit is mixed with a low melting point oxide, it is subjected to a heat treatment at a temperature of 600-900 deg.C, and barium ferrite super fine-grain is obtained. Thus barium ferrite super fine-grain having characteristics desired for the material of high density magnetic recording can be effectively obtained. |
