Preparation of Fe–50 wt.% Co nanopowders by calcination and hydrogen reduction of nitrate powders

Abstract

An optimum route to synthesize Fe–50 wt.% Co nanoparticles and their magnetic properties were investigated. The powder mixture of Fe-oxide and Co 3O 4 were prepared by calcination of Fe- and Co-nitrate powders. The hydrogen reduction behavior of calcined powders was analyzed by DTA–TG. Thermal analysis revealed that the Fe-oxides and Co 3O 4 were hydrogen-reduced to Fe–Co alloy particles with an average size of 30 nm in the temperature range of 260–420 °C. The powder hydrogen-reduced at 600 °C showed saturation magnetization ( M s) of 204.4 emu/g and coercive force ( H c) of 96.3 Oe. However, in case of the reduced powder at 350 °C, the M s and H c values are changed to 120.0 emu/g and 826.8 Oe, respectively. The change of magnetic properties was explained by the formation of ferrimagnetic particles.