Intercalated SiBCN-Mo₂C/PyC-Al₂O₃ Ceramic Hierarchical Lattice Metastructure: A New Paradigm for Ultrabroad Bandwidth-to-Thermal Electromagnetic Absorption

Electromagnetic metamaterials (EM MMs) show significant promise in combating EM radiation (EMR) in the ultrabroad frequency range (i.e., 4–40 GHz). High-efficiency EM MMs have to be a combination of EM lossy materials possessing strong intrinsic loss capability and rationally designed periodic structures exhibiting excellent impedance matching. The traditionally used metastructures and material systems seriously inhibit performance breakthrough and application temperature. In this work, a novel intercalated hierarchical lattice metamaterial, composed of porous Al₂O₃ with a polymer-derived SiBCN coating deposited on nano-layered Mo₂C-PyC absorbents (SiBCN-Mo₂C/PyC-Al₂O₃), was developed by innovatively integrating additive manufacturing (AM), infiltration, and pyrolysis, and the polymer-derived ceramic (PDC) approaches. Benefiting from its good impedance matching of hierarchical architecture, strong intrinsic EM attenuation capability of the Mo₂C/PyC absorbent and improved thermal protection capability provided by the intercalated structure, the obtained SiBCN-Mo₂C/PyC-Al₂O₃ metamaterial exhibited outstanding effective absorption bandwidth (EAB) of 36 GHz from 4 to 40 GHz and minimal reflection loss (RL_min) of −32.7 dB at the temperature of 773K, outperforming the traditionally used triply periodic minimal surface and honeycomb structures with identical ingredient. The key innovations of this work include: (a) An intercalated structure possessing strong EM attenuation capability and improved oxidation resistance capability; (b) An engineered hierarchical lattice metastructure exhibiting excellent impedance matching outperforming the conventional counterpart. This work provides novel insight and ideas for the engineering of advanced metastructures, and paves new avenues for the development of next-generation high-performance EM absorption components.