Preparation and microwave permittivity of SiC-Al₂O₃ nanocomposite powder

To the best of our knowledge, there is no paper in the open literature dealing with the preparation of SiC-Al₂O₃ nanocomposite powder with the method of sol-gel and carbonthermal reduction. We aim to explore preparing such nanocomposite powder with the above-mentioned procedure and then investigate the variation of its microwave permittivity with aluminum content in the frequency range of 8.2-12.4 GHz. The powder synthesized at 1700°C in the atmosphere of argon consists of globose particles 300-400 nm in diameter, which, in their turn, consist of SiC and AlAl₂O₃ microcrystals approximately 45 nm in diameter. The atom of aluminum cannot resolve in the lattice of SiC; this induces both ε′, the real part of complex permittivity, and the dissipation factor tgδ to decrease with increasing aluminum content, tgδ denotes ε″/ε′, where ε″ is the imaginary part of permittivity.