| 摘要 |
<P>PROBLEM TO BE SOLVED: To produce a single crystal cobalt ferrite powder which has an average particle diameter of ≤0.1 μm and a high coercive force at room temperature and which can be applied to a permanent magnet, a magnetic recording medium, a magnetic device, or the like. <P>SOLUTION: The single crystal cobalt ferrite fine particle powder has the average crystal size of 20 to 50 nm and the coercive force at room temperature of ≥158 kA/m. An aqueous solution containing Fe<SP>3+</SP>ions and Co<SP>2+</SP>ions as metal ions is prepared (101). On the other hand, an aqueous solution of a strong alkali is prepared (102) and the solution is heated (103) to a temperature of ≥80°C. When the both solutions are mixed (104) so as to deposit (105) the cobalt ferrite fine powder, the molar ratio. ([metal ion]/[OH<SP>-</SP>]) of the metal ions to hydroxide ions is controlled to 0.1 to 0.4, and the aqueous solution containing the metal ions is added into the aqueous solution containing the strong alkali at a speed of ≤0.1 mol/min while mixing. <P>COPYRIGHT: (C)2004,JPO |
