Microstructure and the dielectric properties of SiCN–Si3N4 ceramics fabricated via LPCVD/CVI

SiCN–Si3N4 ceramics were fabricated by infiltrating SiCN into porous Si3N4 ceramics with different flux ratio of precursor gases via low-pressure chemical vapor deposition/infiltration (LPCVD/CVI). Several methods of characterization were employed to discuss the effects of different precursor gases ratio on the microstructure and dielectric properties of fabricated SiCN–Si3N4 ceramics. The deposition product is amorphous and mainly consists of Sisingle bondN, Csingle bondC and Sisingle bondC bonds. In SiCN–Si3N4 ceramics, free carbon disperses uniformly in the amorphous and low-conductivity SiCN, which results in suitable dielectric properties. The mean real part (ε′) and imaginary part (εʺ) of permittivity increase from 3.82 and 0.05 to 7.71 and 6.94, respectively. The dielectric loss (tan δ) can be controlled from 0.014 to 0.899 by changing the flux ratio of C3H6.