Fe-induced stacking faults engineering for breakthrough broadband absorption in SiBCN ceramics

Polymer-derived SiBCN ceramics (PDCs-SiBCN) have emerged as promising candidates for high-performance electromagnetic wave absorption applications. However, their strong electromagnetic loss, attributed to high crystalline phase content, simultaneously causes impedance mismatch and a narrow absorption bandwidth. To address this challenge, this study proposes an innovative stacking faults (SFs) defect engineering strategy, which can achieve high dielectric loss at low crystallinity. Specifically, SiC whiskers with high-density SFs were catalytically grown using an Fe-mediated liquid-solid interface during polyborosilazane pyrolysis. These SFs serve as effective polarization centers, significantly enhancing dielectric loss capability. By optimizing Fe content, fewer crystalline phases and high SFs density were achieved in SiBCN, thereby realizing impedance matching and strong dielectric loss. Consequently, the unique microstructure expanded the effective absorption bandwidth of SiBCN from 4.82 to 6.36 GHz at 2.1 mm thickness, demonstrating record-breaking broadband absorption performance among PDCs. This Fe-mediated SFs defect engineering provides a strategic pathway to resolve the long-standing conflict between “impedance matching and strong dielectric loss” in PDCs.