Structure and Magnetic properties of Amorphous Fe10Mn70B20 Ultrafine Powder

We report on the synthesis of amorphous ultrafine powder of Fe10Mn70B20 by reduction of transition metal ions in a NaBH4 aqueous solution, the morphological-structural characterization and its magnetic properties. The sample consists of both very fine needles, which form skeins, and chains of spherical particles. Magnetization measurements show a progressive blocking of interacting superparamagnetic nanodomains with decreasing temperature. The effect of aging and thermal annealing on the magnetic properties is discussed.