| 摘要 |
PURPOSE:To obtain barium ferrite powder having hexagonal plate shape suitable for magnetic recording by treating hydrothermally hexagonal plate shape iron oxyhydroxide powder obtd. by a specified method or iron oxide powder prepd. by the dehydration of said iron oxyhydroxide powder by heating, in an autoclave together with a Ba salt. CONSTITUTION:Powder consisting essentially of iron oxyhydroxide having uniform, fine hexagonal plate shape is obtd. by oxidizing quickly the precipitate contg. ferrous hydroxide obtd. from an aq. soln. contg. a ferrous salt such as FeSO4. Ba compd. such as BaCl2 is added to the aq. suspension of said iron oxyhydroxide or iron hydroxide powder, and the mixture is heat-treated in an autoclave at >=100 deg.C to obtain hexagonal plate barium ferrite powder. The barium ferrite powder has <=ca. 0.25mum average particle size and superior magnetic characteristics; accordingly, it is useful for high density magnetic recording. |
