Dielectric gene engineering in subwavelength-structured amorphous silicon oxycarbide ceramic aerogels for programmable electromagnetic wave absorption

Abstract Amorphous ceramics, distinctively represented by silicon oxycarbide (SiOC), are promising electromagnetic wave absorbers owing to their low density and high-temperature stability. To enable programmable attenuation, we propose a dielectric gene engineering strategy, fabricating subwavelength-structured amorphous SiOC aerogels via wet spinning, sol-gel processing, supercritical drying, and subsequent thermal treatments. At the macroscopic level, the customized multi-scale void network optimizes impedance matching, enhances multiple scattering and reflections, and effectively prolongs the propagation path of electromagnetic waves. At the microscale, intrinsic dielectric genes including the conductive sp2 carbon phase, dielectric SiC nanocrystals, asymmetric SiOxC4−x tetrahedra, and the interfaces of these heterogeneous nanodomains are established by manipulating carbothermal reduction and post-oxidation thermal etching. This engineered structural evolution achieves an optimal synergy among conduction loss from the carbon network, interfacial polarization at heterogeneous boundaries, and dipolar polarization induced by the asymmetric tetrahedra. Consequently, driven by this macro-micro synergy, these amorphous ceramic aerogels achieve programmable and frequency-tunable absorption spanning the C, X, and Ku bands. They deliver minimum reflection losses of –57.87 dB at 5.36 GHz, –70.09 dB at 9.04 GHz, and –54.06 dB at 14.28 GHz. This work demonstrates that integrating subwavelength architectures with dielectric gene engineering provides a paradigm for designing lightweight and frequency-programmable ceramic absorbers.