Silicon carbide (SiC) is considered to be one of the promising EM absorbing materials due to its good oxidation resistance, low density and chemical inertness, and can be used in high-temperature and harsh environments. In this paper, C-SiC wires with different stacking faults densities were prepared by microwave heating following with post heat-treatment under different conditions. Dielectric measurements indicate that their permittivities increase with the increase in stacking faults density in 2-18 GHz. TEM observation suggests that the stacking faults were formed by embedding 2H-SiC segments in 3C-SiC matrix, which resulting in the type-II 2H/3C-SiC heterostructures. Since both the VBM and CBM of 3C-SiC are lower than those of 2H-SiC, respectively, a large conduction-band offset would occur. This may cause plenty of interface dipoles and following with large dipole polarization loss, which might be the origin of high dielectric permittivity of SiC wires.

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Silicon Carbide whiskers have been synthesized using silica sol and activated carbon as reagents via microwave heating without the presence of any of the catalysts, such as Fe, Ni, and Al etc.. The synthesized whiskers were separated and concentrated from the as‐synthesized products using the gravity concentration process. The dielectric properties of the concentrated SiC whiskers were investigated in the frequency range 2–18 GHz. The results indicate that the SiC whiskers exhibit higher dielectric permittivity and loss tangent than those of SiC powders, respectively, due to the high density of stacking faults formed in the SiC whiskers prepared by microwave heating.

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