Dielectric and microwave absorption properties of AlN‐SiBCN lossy ceramics

Abstract

Dense AlN-SiBCN ceramics were fabricated by pyrolysis of a commercially available polyborosilazane followed by hot-pressing of AlN and SiBCN mixture in N 2 atmosphere. The effect of SiBCN 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 SiBCN powder. The composites fabricated with 30 wt.% SiBCN had the highest electrical conductivity and dielectric permittivity, which can be attributed to the formation of SiC nanoparticles. With further increase in SiBCN content, the composites showed the lowest reflection coefficient of À30.88 dB at 8.5 GHz and the frequency bandwidth of 1 GHz below À10 dB in X-band. K E Y W O R D S dielectric properties, microstructure, microwaves

Structural, thermal and dielectric properties of AlN–SiC composites fabricated by plasma activated sintering

“…This consequence is different from the dielectric loss from He et al. [39] in AlN–SiBCN. In the 6–16 GHz range, the permittivity and dielectric loss increased from 7.6–8.5 and 0.02–0.1 to 22–26.7 and 0.2–0.53, respectively.…”

“…The loss peak is related to withdrawal and transformation of electron polarisation as well as dipole polarisation; in addition, the high concentration of dipole polarisation would be an impact factor of shifts to low-frequency [38]. This consequence is different from the dielectric loss from He et al [39] in AlN-SiBCN. In the 6-16 GHz range, the permittivity and dielectric loss increased from 7.6-8.5 and 0.02-0.1 to 22-26.7 and 0.2-0.53, respectively.…”

Polymer‐derived FexSiy/SiC@SiOC ceramic nanocomposites with tunable microwave absorption behavior

“…Some studies show that the dielectric properties of polyboronsilazane have been improved by mixing with microwave absorbing agents such as SiC nanoparticles, MWCNTs, or metallic nanoparticles, [19][20][21] and the as-obtained ceramics exhibit promoted MA properties. Because of the porous 3D framework and components with high dielectric loss, polymer-derived ceramic aerogels synthesized via hydrosilylation and freeze-drying also exhibited remarkable electromagnetic absorption performance.…”

Principles, design, structure and properties of ceramics for microwave absorption or transmission at high-temperatures

“…The ε ′ and ε ′′ of the MWCNTs-SiBCN composites obtained at 1350°C were in a range of 4.5-14.0 and 0.5-9.0, while those values of composites annealing at 1500°C were 10.0-16.0 and 4.0-16.0, respectively. The hot-pressed 52.0 wt-% AlN-SiBCN composites at 1700 o C had the RL min of −30.9 dB at 8.5 GHz and an EAB of 1.0 GHz in X band for a thickness of 2.0 mm [86]. The ε ′ and ε ′′ of the various AlN contents containing SiBCN composites hot-pressed at 1700°C were in a range of 10.0-35.0 and 0.5-14.0, respectively.…”

“…The hot-pressed 52.0 wt-% AlN-SiBCN composites at 1700 o C had the RL min of −30.9 dB at 8.5 GHz and an EAB of 1.0 GHz in X band for a thickness of 2.0 mm [86]. The ϵ ′ and ϵ ″ of the various AlN contents containing SiBCN composites hot-pressed at 1700°C were in a range of 10.0–35.0 and 0.5–14.0, respectively.…”