Additively manufactured pyrolytic carbon/SiOC ceramic hierarchical hybrid metamaterials for ultra-broad electromagnetic absorption

Creating novel electromagnetic (EM) attenuation (meta)structures by multi-scale engineering is an effective strategy to achieve ultra-broad (≥30 GHz) effective absorption bandwidth (EAB). However, most studies, especially concerning ceramic based EM metamaterials, rely on traditional structures, such as woodpile (0°-90°) scaffolds, honeycomb and so on, making the improving of the EM performance challenging. In this work, ceramic-based hierarchical hybrid metamaterials with different structures (e.g., trapezoidal, stepped and honeycomb) were innovatively established on the basis of polymer-derived defect-rich pyrolytic carbon modified SiOC (PyC/SiOC) ceramic scaffold. The intrinsic EM attenuation capability of ingredient PyC/SiOC ceramic scaffolds was maximized by optimizing the volume infill rate and EM attenuation multi-loss mechanisms. EM multi-loss capability, including conductive loss and defects-induced polarization loss, was maximized by controlling the defects populations in the PyC absorbents. The results demonstrate that the synergistic effect of multi-loss mechanisms and hierarchical hybrid metastructural engineering significantly enhances EM absorption performance. Benefiting from these advantageous multi-scale structures, a simulated ultra-broad EAB of 36.8 GHz over the range of 3.2-40 GHz was achieved. This work provides novel insights and new ideas for the design of broadband EM absorbers.