| 摘要 |
PROBLEM TO BE SOLVED: To obtain magnetite particles excellent in dispersibility by using magnetite having a specified compsn. and specified physical properties. SOLUTION: The objective magnetite particles have an octahedral particle shape, <=0.6μm average particle diameter, 40-1000e coercive force and <=i1×10<4> Ω.cm electric resistance and contain silicon by 0.1-3.0wt.% of the amt. of the magnetite particles. When the magnetite particles are dissolved by 20% (expressed in terms of Fe) from the surfaces of the particles, the total amt. of metals (Si, Al, Ti, Zr, Mn, Mg and Zn) other than Fe is preferably 0.5-4.5wt.% of the amt. of the magnetite particles. |
