Electromagnetic materials for ultra-high frequency applications: Fe/SiO2 composite superfine particles

For high frequency electromagnetic application, we prepared metal/dielectric composite, comprising iron particles with several microns size covered by SiO₂ particles with few hundreds of nanometers size. The structural characteristics of Fe/SiO₂ powders were observed in detail. The direct current magnetic properties were also measured. Composition ratio of Fe/SiO₂ is modified, followed by measuring the relative complex permittivity and complex permeability in the frequency range from 2 GHz to 18 GHz. It is found that the Fe/SiO₂ with micron-size iron particles have high saturation magnetization, which results in interesting electromagnetic properties. In comparison with composites consisting of nanometer-size metallic magnetic particles which have been extensively investigated, this kind of composites is another potential electromagnetic material for ultra-high frequency application such as microwave absorption or shielding.