| 摘要 |
PROBLEM TO BE SOLVED: To provide a magnetite powder having an improved electric wave absorption characteristics in a high-frequency region. SOLUTION: The magnetite powder is obtained by reducing hematite and is characterized in that a layered uneven pattern having an interval of 5-80μm is observed on the surface of each particle in an AFM (atomic force microscope) image. The magnetite powder can be obtained by reducing hematite, obtained by thermally decomposing an Fe-containing acid solution such as a steel pickling waste liquor or the like at a temperature of≥450°C, preferably, at 450-900°C under the atmosphere. Preferable magnetite powder contains particles having an average diameter D<SB>50</SB>of 1-10μm and D<SB>90</SB>of 10-50μm. Further, a powder of magnetite obtained by wet pulverizing the preferable magnetite mentioned above and including primary particles having an average diameter of 0.1-1.0μm is particularly preferable. COPYRIGHT: (C)2006,JPO&NCIPI
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