Magnetic properties of spindle-type iron fine particles obtained from hematite

Spindle-type iron fine particles have been prepared by reduction of silica-coated-hematite particles. Hydrogen reduction of the coated-hematite cores yielded uniform spindle-type iron particles, which were stabilized by surface oxidation. Narrow particle distributions are observed from TEM measurements. X-ray, Mossbauer and magnetization data are in agreement with the presence of nanosized α-Fe particles, having surface layer of spinel structure oxide. Mossbauer spectra show that the oxide surface is superparamagnetic at room temperature.