Polyacrylonitrile-Derived Nitrogen-Doped Carbon Nanoparticles Decorated with Fe₃C for Wide-Band Microwave Dissipation

The design of wide-band microwave absorption materials is currently an effective strategy to eliminate excessive microwave radiation contamination. Herein, a facile method of polymerization, magnetic doping and calcination was employed to prepare Fe₃C-decorated N-doped carbon nanoparticles from polyacrylonitrile. The research demonstrates the high defect state of the amorphous carbon within the composites, and the increase in temperature induced enhancement of the Fe²⁺/Fe³⁺ ratio, reducing the performance after absorption saturation. The composite obtained under 650°C treatment has the best microwave absorption ability, with a maximal reflection loss (RL) of 39.32 dB at 3.44 GHz and the broadest efficient absorption bandwidth of 6.19 GHz at only 2.3 mm for a low filling rate of 10 wt.%. The combined effect of conduction loss, dipole and interface polarizations, exchange and natural resonances, and eddy-current loss under matched impedance promotes this excellent absorption performance, which confirms the practicability of this absorber for shielding of electromagnetic radiation pollution.