Facile synthesis and tunable microwave absorption properties of N-doped C modified SiC nanoparticles

N-doped C modified SiC nanoparticles (SiC@C(N)) with core-shell feature were successfully synthesized by a facile method of dopamine (DA) self-polymerization on SiC combined with heat treatment technology. The SiC@C(N) nanocomposites hold tunable microwave absorption properties by tailoring the dosage of DA precursor. When the mass ratio of SiC to DA is 2:1, the synthesized SiC@C(N) nanocomposites achieved a strong microwave absorption capacity, whose optimal reflection loss reaches - 43.94 dB at a frequency of 7.97 GHz with a thickness of 3.10 mm. And the absorption bandwidth below - 20 dB is 14.78 GHz from 3.22 to 18 GHz, with a thickness range of 1.50-6.00 mm. The SiC surface coated by N-doped C causes an intense interface polarization and defect dipole polarization. Moreover, N-doped C-modified SiC can improve the conductivity of SiC due to increased carrier concentration, thus elevating its conductance loss. As a result, the appropriate N-doped C coating modified SiC makes the SiC@C(N) nanocomposites acquire a combined effect in terms of interface polarization, defect dipole polarization, conductance loss, space-charge polarization, and weak magnetic loss, which optimizes the balance between impedance matching and attenuation capacity, thus resulting in excellent microwave absorption performance.