Preparation of SiO2 Matrix Composite with Tunable Dielectric Properties in Radio Frequency Range

In this paper, C/SiO2 composites were fabricated by self-assembly process combined with heat treatment. The X-ray diffraction (XRD) analysis, SEM and impedance analyzer were used to investigate the microstructure and radio-frequency dielectric properties of the composites. The results showed that the matrix of C/SiO2 composite with a periodical structure formed by the hexagonal stacking of SiO2 microspheres. The sheet carbon distributes in pores formed by SiO2 microspheres and act as the functional phase in the composite. The results indicate that the permittivity of C/SiO2 composite could be easily adjusted by controlling the content of Carbon in the composite. Both real and imaginary parts of the permittivity increase with the content of carbon, but decrease with the frequency.