Structure and magnetic properties of FeCo-SiO2 nanocomposite synthesized by a novel wet chemical method

A novel soft magnetic nanocomposite with FeCo particles encapsulated by amorphous SiO₂ was synthesized using a co-precipitation combined H₂ reduction method. The saturation magnetization of the (Fe₇₀Co₃₀)₉₀/(SiO₂)₁₀ nanocomposite is as high as 200 emu/g, which is 4-5 times larger than that of traditional spinel ferrites. The frequency dependence of the complex initial permeability is intensely dependent upon the content of SiO₂ insulating phase. With increasing the content of SiO₂ to 10 wt.%, the cut-off frequency is drastically increased to over 1 GHz. The results show that a new high-frequency soft magnetic material with high saturation magnetization (M_s) can be achieved by introducing FeCo/SiO₂ nanocomposite.