Magnetic properties of iron nanoparticles grown in a glass matrix

Iron particles of diameters in the range 5.5–8.5 nm have been synthesized within a suitably chosen oxide glass by subjecting the latter to a 3Na+⇄Fe3+ exchange reaction followed by reduction treatment in hydrogen. Magnetic measurements have been carried out over the temperature range 20–300 K. The coercive force increases as the iron particle size is decreased. The maximum value of coercive force corresponding to 0 K (Hc0)∼548 Oe is obtained for a specimen having diameter of 6.5 nm. The magnetocrystalline anisotropy constant in the case of nanosized iron particles is estimated to be one order of magnitude higher than that of bulk iron.