Xiaolei Su

A Method to Adjust Dielectric Property of SiC Powder in the GHz Range

The SiC powders by AI or N doping have been synthesized by combustion synthesis, using AI powder and NH 4 CI powder as the dopants and polytetrafluoroethylene as the chemical activator. Characterization by X-ray diffraction, Raman spectrometer, scanning electron microscopy and energy dispersive spectrometer demonstrates the formation of AI doped SiC, N doped SiC and the AI and N co-doped SiC solid solution powders, respectively. The electric permittivities of prepared powders have been determined in the frequency range of 8.2–12.4 GHz. It indicates that the electric permittivities of the prepared SiC powders have been improved by the pure AI or N doping and decrease by the AI and N co-doping. The paper presents a method to adjust dielectric property of SiC powders in the GHz range.

EFFECT OF REACTION TIME ON MICROSTRUCTURE, DIELECTRIC PROPERTY AND MICROWAVE ABSORPTION PROPERTY OF Cu-DOPED SiC NANOPOWDER

Cu-doped SiC nanopowders have been prepared via combustion synthesis of the silicon and carbon system in a 0.1 MPa nitrogen atmosphere under different reaction time, using copper as the dopant and PTFE as the chemical activator, respectively. X-ray diffraction, scanning electronic microscope and Raman spectra have been used to characterize the phase and morphology of prepared nanopowders. Results indicate that the lattice constant of prepared Cu-doped SiC nanopowder decreases with extending reaction time. The prepared nanopowders have fine spherical particles and narrow particle size distribution and the particle size increases with increasing reaction time. The electric permittivities of prepared Cu-doped SiC nanopowders in the frequency range of 8.2–12.4 GHz have been determined. The real part e′, imaginary part e′′ and dielectric loss tgδ of complex permittivity decrease with increasing reaction time. All prepared Cu-doped SiC nanopowder exhibits good microwave absorption property in the frequency range of 8.2–12.4 GHz.