Synthesis of N-doped SiC nano-powders with effective microwave absorption and enhanced photoluminescence

Although their preparation remains challenging, N-doped SiC nanostructures have received much attention due to their high performance characteristics compared to pure Si3N4 and SiC phases. In this study, N-doped SiC nano-powders were synthesized in one step through hexamethyldisilane pyrolysis in Ar/N2 plasma atmosphere. The results show that the undoped products included β-SiC nanoparticles sized in the range of 5–20 nm and carbon layers with 1–10 layers, while N-doped SiC nano-powders were mainly amorphous Si3N4/SiCN aggregates sized in the range of 30–200 nm with some β-SiC nanoparticles attached. The increased N2 flow rate and arc currents favored nitrogen doping and carbon removal. In addition, according to the X-ray photoelectron spectroscopy, the highest N-doping level approached 20% (atomic ratio). Nitrogen doping can effectively adjust the dielectric properties and affect the microwave absorption ability. The optimal reflection loss reached −56.2 dB at 8.9 GHz under an absorber thickness of 3.1 mm when the N-doping level was 12.1%. Moreover, due to the defect states, the N-doped SiC nano-powders exhibited good photoluminescence performance in the blue-green emission region. Therefore, the synthesized N-doped SiC nano-powders developed herein present potential applicability as microwave absorbers and light-emitting sources.