Synthesis of air stable iron nanopowders with various methods.

: Magnetic properties and microstructures of iron-based nanopowders fabricated by several methods, such as sol-gel, thermal decomposition, and self-propagating combustion methods, were investigated. During a subsequent reduction annealing, added aluminum atoms formed coherent oxide shells with a hercynite structure around iron cores in all the nanopowders. In particular, the nanopowders synthesized by the self-propagating combustion method showed the highest saturation magnetization of 175.68 emu/g and oxidation stability to 200 degrees C in air.