Magnetic properties of acicular ultrafine iron particles

Magnetic properties of acicular (/spl sim/60 and /spl sim/200 nm) iron particles, obtained by reduction of alumina-coated goethite particles, are reported. X-ray diffraction and Mossbauer spectroscopy showed that the particles consist of an /spl alpha/-Fe core and a thin surface layer of maghemite. Magnetization data indicated an improvement of /spl sim/28% in the saturation magnetization, coercive field, and squareness for particles with /spl sim/60 nm. This magnetic property enhancement of the present particles, whose size is 40% smaller than those commercially available, could result in a similar decrease of the bit-size for higher density of magnetic media.