Spindle-shaped magnetic ironbased alloy particles containing cobalt and iron as the main ingredients and process for producing the same

摘要

Spindle-shaped goethite particles containing cobalt in which Co is 1.0 to 50.0 atm% (calculated as Co) based on the total Fe in the spindle-shaped goethite particles, and having an average major axis diameter of 0.05 to 0.20 mu m, a size distribution (standard deviation/major axis diameter) not more than 0.30, an average minor axis diameter of 0.010 to 0.025 mu m, an aspect ratio of 4 to 15 and an X-ray crystallite size ratio (D020/D110) of 1.5 to 3.5.