Preparation and Dielectric Property of Al and N Co-Doped SiC Powder by Combustion Synthesis

As an absorber of microwave, the Al and N co-doped SiC powders have been synthesized by combustion synthesis in a nitrogen or argon atmosphere, using silicon and carbon black as the raw material, polytetrafluoroethylene as the chemical activator, aluminum and ammonium chloride (NH4Cl) as the doping resource, respectively. XRD, SEM, EDS, and Raman spectra were utilized in analyzing phases, morphology, and chemical composition. Results show that the prepared powders are the Al and N co-doped SiC powders. The electric permittivities of prepared powders were determined in the frequency range of 8.2-12.4 GHz. When the molar ratio of Al to NH4Cl change from 0.5 to 1, the electric permittivities of prepared powders in a nitrogen atmosphere decrease and reach the least values for the prepared powders in an argon atmosphere. The dielectric loss mechanism has been discussed.