Dielectric properties of nano Si/C/N composite powder and nano SiC powder at high frequencies

The dielectric properties of nano Si/C/N composite powder and nano SiC powder at high frequencies have been studied. The nano Si/C/N composite powder and nano SiC powder were synthesized from hexamethyldisilazane ((Me3Si)2NH) (Me:CH3) and SiH4–C2H2, respectively, by a laser-induced gas-phase reaction. The complex permittivities of the nano Si/C/N composite powder and nano SiC powder were measured at a frequency range of 8.2–12.4 GHz. The real part (ε′) and imaginary part (ε″) of the complex permittivity, and dissipation factor View the MathML source of nano Si/C/N composite powder are much higher than those of nano SiC powder and bulk SiC, Si3N4, SiO2, and Si, especially the View the MathML source. The promising features of nano Si/C/N composite powder would be due to more complicated Si, C, and N atomic chemical environment than in a mixture of pure SiC and Si3N4 phase. The charged defects and quasi-free electrons moved in response to the electric field, diffusion or polarization current resulted from the field propagation. Because there exists graphite in the nano Si/C/N composite powder, some charge carries are related to the sp3 dangling bonds (of silicon and carbon) and unsaturated sp2 carbons. The high ε″ and View the MathML source of nano Si/C/N composite powder were due to the dielectric relaxation. The nano Si/C/N composite powder would be a good candidate for electromagnetic interface shielding material.