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 (NH ₄Cl) 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 NH ₄Cl 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.