A facile one-pot strategy for fabrication of carbon-based microwave absorbers: effects on annealing and paraffin content.

In this work, a one-pot strategy was proposed to synthesize carbon-coated Fe3O4 and carbon-coated Fe3C via the pyrolysis of colloidal Fe3O4 nanocrystals capped with oleic acid (OA) at different calcination temperatures. After exploring the microwave absorption performance of these composites, we found that carbon-coated Fe3C obtained at 700 °C possesses higher reflection loss (RL) and broader effective bandwidth (RL ≤ -10 dB) at low thickness. So the further investigation of the microwave absorption performance for carbon-capped Fe3C composites mixed with different mass percentages of paraffin was also carried out. The results demonstrated that the multi-dielectric relaxation process and better impedance matching, especially at low thickness and high frequency, contributed to the preferable microwave absorption greatly.