| 摘要 |
PURPOSE:To stabilize magnetic characteristics having no irregularity by a method wherein ferric hydroxide, having prescribed crystal structure, and an aqueous slurry, containing a plurality of specific metallic amorphous hydroxide or an amorphous carbonate, are hydrothermally reacted at a specific temperature by adjusting them to the pH within specific range. CONSTITUTION:This composite spinnel ferrite fine particles have the average particle diameter, which is indicated by the formula separately mentioned, within the range of 0.01 to 0.2mum. (The M in the formula indicates the bivalent metal atom containing at least a kind selected from the group consisting of Ni and Cu, alpha, beta, rho and n indicate the number which satisfies the following relations : 0.1<=alpha<=0.75, 0<=beta<=0.3, 0.05<=gamma<=0.6 and 0.8<=n<=1.2). Ferric hydroxide, trivalent iron and amorphous hydroxide, containing the bivalent metal selected from iron, manganese, nickel and copper, are contained in the above-mentioned ferrite fine powder. The aqueous slurry, which is adjusted in the range of pH 9.0 to 13.0, is hydrothermally reacted at 150 to 230 deg.C. As a result, non- irregularity fine particles having stabilized magnetic characteristics can be obtained. |
