Microwave dielectric properties of B and N co-doped SiC nanopowders prepared by combustion synthesis

Abstract B and N co-doped SiC nanopowders were prepared by combustion synthesis under a nitrogen atmosphere from the Si/C system, using α-Si3N4 powder and B powder as solid nitriding agent and dopant, respectively. The prepared particles had spherical morphology and narrow size distribution. XPS analysis demonstrated that B and N atoms successfully incorporated into SiC crystal and formed Si1-xBxC1-yNy solid solution. Results of dielectric properties showed that the real part e′ and imaginary part e″ of the complex permittivities of the samples decreased first, and then increased with increasing N content. The sample with 5% B and 15% N revealed the greatest values in e′ and e″ and better microwave absorption performance. The corresponding mechanism of the dielectric properties of SiC improved by co-doping was discussed in detail.