Synthesis of submicron sized Fe₂₀ Ni₈₀ particles and their magnetic properties

Fe-Ni alloy nanoparticles were synthesized by polyol process using hydrazine as a reduction assist reagent. Particle size, crystallite size, and crystal phases varied with the type of polyol. The saturation magnetizations of the as-synthesized Fe-Ni particles synthesized in ethylene glycol (EG) and 1-heptanol were similar to the bulk and were 73 emu/g and 83 emu/g, respectively. On the other hand, the coercivities of the same were 41 and 123 Oe. The coercivity of the Fe-Ni particles synthesized in EG decreased to 27 Oe after heat treatment. Though the magnetic properties were very similar irrespective of the polyol used in this study, the Mössbauer spectroscopic measurements revealed that Fe-Ni particles with single permalloy phase was synthesized only when EG was used.