Composition-Controlled Fe-Ni Alloy Fine Particles Synthesized by Reduction-Annealing of Polyol-Derived Fe-Ni Hydroxide

Fe-Ni hydroxide fine particles with a layered double hydroxide-type structure were precipitated as an intermediate in polyol (ethyleneglycol) solution with Fe compositions ranging between about 10 and 90 at%. Subsequent reduction-annealing of the above polyol-derived particles with 13-56 at% Fe at 673 K resulted in the synthesis of fcc Fe-Ni alloy fine particles with their sizes less than about 50 nm. The lattice constants of fcc Fe-Ni alloy particles were close to those of the bulk fcc Fe-Ni alloy with similar compositions. X-ray absorption spectroscopy measurements suggested that fcc Fe-Ni alloy was formed through simultaneous reduction of Fe and Ni in Fe-Ni hydroxide. Consequently, the reduction-annealing of polyol-derived Fe-Ni hydroxide fine particles is proved to be an effective process for obtaining composition-controlled Fe-Ni alloy fine particles.