Microwave absorbing property and complex permittivity of nano SiC particles doped with nitrogen

Microwave absorbing property and complex permittivity of the nano SiC particles doped with nitrogen within the frequency range of 8.2-18 GHz were investigated. The nano SiC particles doped with nitrogen was synthesized from hexamethyldisilazane ((Me₃Si)₂NH) (Me:CH₃) by a laser-induced gas-phase reaction. The complex permittivities of the composites can be tailored by the contents of the nano SiC particles. The real part (ε′) and imaginary part (ε″) of the complex permittivity, and the dielectric dissipation factor (tg δ = ε″/ε′) of the composites increase with the volume filling factor (v) of the nano SiC particles doped with nitrogen. The ε′ and ε″ of the composites can be effectively modeled using second-order polynomials (ε′, ε″ = A_v² + B_v + C). The ε′ and ε″ of the nano SiC particles doped with nitrogen decrease with frequency. The high ε″ and tg δ of the nano SiC particles doped with nitrogen are believed to be caused by the substitution of nitrogen for carbon in the nanocrystals of SiC. The single layer composites of 7 wt% nano SiC particles doped with nitrogen with a thickness of 2.96 mm achieved a reflection loss below -10 dB (90% absorption) at 9.8-15.8 GHz, and the minimum value was -63.41 dB at 12.17 GHz. The reflection loss calculations show that the prepared nano SiC particles doped with nitrogen are good electromagnetic wave absorbers in the microwave range.