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 (Ms) can be achieved by introducing FeCo/SiO2 nanocomposite.