Fe3O4/Fe/C composites prepared by a facile thermal decomposition method and their application as microwave absorbers

The Fe3O4/Fe/C composites used as microwave absorbers were synthesized by a facile thermal decomposition method using sodium chloride as a template. The hierarchical flower-like structure was obtained by thermally treating the precursors at 600 degrees C for 2 h under a nitrogen atmosphere with a heating rate of 5 degrees C/min. Based on the complex permittivity and permeability results, the Reflection loss (RL) of the Fe3O4/Fe/C composites were calculated. The Fe3O4/Fe/C composites show a RL peak of -51.3 dB for a 2 mm thick positioned at 17.2 GHz frequency. When the absorber thickness was adjusted to 2.3 mm, the effective adsorption bandwidth (RL <= -10 dB) is 5.6 GHz (12.4-18 GHz) frequency. Simultaneously, the RL peak of the absorber still reaches -40.8 dB at 14.7 GHz frequency. The RL peak is explained using the quarter-wave cancellation model. The microwave absorption behavior of Fe3O4/Fe/C composites can be attributed to the reasonable impedance matching and the existence of interfaces around the composites. Our findings offer an effective way to design and synthesis the excellent microwave absorber of Fe3O4/Fe/C composite. (C) 2019 Elsevier B.V. All rights reserved.