| 摘要 |
PROBLEM TO BE SOLVED: To provide a black magnetic iron oxide particle powder having excellent blackness and excellent electrifying performances, capable of stably keeping electrification quantity even under an atmosphere of low temperature-low humidity or high temperature-high humidity and having excellent environmental stability. SOLUTION: The black magnetic iron oxide particle powder is constituted of black granular spinel type iron oxide particles having 0.05 to 1.0μm average particle diameter and has a three phase structure composed of a core part, a surface layer part and an intermediate layer present between the core part and the surface layer part. Each of the core part and the surface layer part contains 0.1 to 10 wt.% one or more kinds of different metal elements except iron, which is selected from Mn, Zn, Cu, Ni, Cr, Cd, Sn, Mg, Ti, Ca and Al, and the intermediate layer does not contain the different metal elements except iron.
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