Dielectric and microwave absorption properties of AlN‐Si BCN lossy ceramics

Abstract Dense AlN‐Si BCN ceramics were fabricated by pyrolysis of a commercially available polyborosilazane followed by hot‐pressing of AlN and Si BCN mixture in N ₂ atmosphere. The effect of Si BCN content on phase behavior, microstructure, electrical conductivity, dielectric and microwave absorption properties of the composites were investigated. The results showed that characteristic peaks of Si ₃ N ₄ , SiC, and BNC appeared above 1650°C during the annealing of Si BCN powder. The composites fabricated with 30 wt.% Si BCN had the highest electrical conductivity and dielectric permittivity, which can be attributed to the formation of SiC nanoparticles. With further increase in Si BCN content, the composites showed the lowest reflection coefficient of −30.88 dB at 8.5 GHz and the frequency bandwidth of 1 GHz below −10 dB in X‐band.