Facile preparation and enhanced microwave absorption properties of flake carbonyl iron/Fe3O4 composite

Flake carbonyl iron/Fe3O4 (FCI/Fe3O4) composites with enhanced microwave absorption properties were prepared by a direct and flexible surface oxidation technique. The phase structures, morphology, magnetic properties, frequency-dependent electromagnetic and microwave absorption properties of the composites were investigated. The measurement results showed that lower permittivity as well as modest permeability was obtained by the FCI/Fe3O4 composites. The calculated microwave absorption properties indicated that enhanced absorption efficiency and broader absorption band were obtained by the FCI/Fe3O4 composite comparing with the FCI composite. The absorption frequency range with reflection loss (RL) below −5 dB of FCI/Fe3O4 composites at reaction time of 90 min at thickness of 1.5 mm is 13.3 GHz from 4.7 to 18 GHz, while the bandwidth of the FCI composite is only 5.9 GHz from 2.6 to 8.5 GHz at the same thickness. Thus, such absorbers could act as effective and wide broadband microwave absorbers in the GHz range.