Fe/SiO₂ Nanocomposite Soft Magnetic Materials

Abstract

In an effort to explore new highly resistive soft magnetic materials, Fe/SiO 2 nanocomposite materials have been synthesized using a wet chemical reaction approach in which the precursor complex was annealed at various temperatures. The crystallographic structure, nanostructure, morphology, and magnetic properties of the synthetic Fe/SiO 2 particles were studied by x-ray diffraction, transmission electron microscopy, and magnetic measurements. The experimental results show that for this approach, the ac-Fe particles are coated with amorphous silica. The progress of the reaction, the purity of Fe/Si0 2 in the synthetic powder, and the Fe particle size are highly dependent on the annealing temperature. By adjusting the annealing temperature, the particle size can be controlled from approximately 20 nm to 70 nm. For the synthetic nanopowder obtained by H 2 reduction at 400 TC, there exists a superparamagnetic behavior below room temperature; while for the nanopowders obtained by reduction at higher temperatures, the ferromagnetic behavior is dominant. Based on these studies, optimum synthesis conditions for Fe/Si0 2 nanocomposites is determined.