Wide-band microwave absorption by <i>in situ</i> tailoring morphology and optimized N-doping in nano-SiC

Abstract

SiC has amazing electromagnetic wave absorption properties based on its excellent dielectric properties. The optimized N-doping nano-SiC with in-situ tailored morphology by a facile one-step synthesis strategy is presented. By using a new N source and gas catalyst, acetonitrile (C2H3N) was exploited to synthesize N-doped nano-SiC with an evolution of morphology from spherical to nanoflake. The surface area of the nanoflake SiC is significantly expanded to support more quantity and types of electric dipoles. Combining the optimized N concentration doping, the complex dielectric and microwave absorption properties of the tailored nano-SiC are clearly improved in the 2–18 GHz range when compared to previously reported SiC and N-doped SiC nanoparticles. The higher ε″ and tan δ values are attributed to fortified polarization relaxation by optimized N-doping and novel nanoflake morphology. A wideband reflection loss exceeding –10 dB (90% microwave absorption) reached 4.1 GHz with an absorber thickness of 1.58 mm. A minimum value of −42 dB at 8 GHz was also achieved. The mechanism of dielectric loss of nanoflake N-doped SiC is discussed in detail.