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.