Highly stable carbon-coated Fe/SiO2 composites: Synthesis, structure and magnetic properties

A new method to coat Fe nanoparticles with carbon by pyrolysis of acetylene is reported. The Fe nanoparticles were beforehand coated with silica layers by sol–gel combined hydrogen method. The antioxidation capability of Fe/SiO2 composites has enhanced greatly after coated with amorphous carbon shells. By the introduction of only 7.5 wt.% nonmagnetic silica and carbon, these composites have relatively high specific magnetization of 200.27 emu/g. The insulating amorphous silica and carbon shells prove effective to reduce the eddy current at high frequency.