Effect of aluminium doping on microwave dielectric properties of SiC powder

Al-doped SiC powders were synthesized by solid state reaction at high temperatures, using Al powder and SiC powder as the starting materials. The prepared powders were characterized by X-ray diffraction (XRD) and Raman spectra. Results show that there does not exit any aluminium composite in the products at above 1900°C, and that more Al atoms enter SiC lattice to form Al-SiC solid solution at 2000°C. The permittivities of undoped and doped SiC powders were determined by the waveguide technique in the frequency range of 8.2-12.4GHz. Results show that the microwave dielectric properties of SiC powder can be improved greatly by Al-SiC solid solution arising from Al doping.