Multi-heterointerface lightweight ceramics achieving temperature-insensitive dielectric properties for high-temperature electromagnetic wave effective absorption

The limitations of conventional electromagnetic wave (EMW) absorbing materials in terms of high-temperature resistance have stimulated interest in the development of high-temperature EMW absorbing materials across various fields. However, due to the temperature dependence of the permittivity, achieving effective EMW absorption across a wide temperature range remains a significant challenge for high-temperature EMW absorbing materials. Herein, a novel molecular-scale strategy is proposed for in-situ construction multi-heterointerface during the polymer-derived ceramics process, thereby achieving temperature-insensitive permittivity. The interfacial dipole polarization generated by multi-heterointerface effectively mitigates the dependence of the permittivity on conductivity, thereby reducing the temperature sensitivity of the overall permittivity. Meanwhile, the preparation of lightweight porous ceramics was further achieved by using the self-sacrificing template method. As a proof-of-concept, multi-heterointerface lightweight ceramics (MHLCs) that exhibited excellent thermal stability (up to 1000 °C), low density (1.03 g/cm³), low thermal conductivity (0.37 W/ (m K)), and high bending strength (33.55 MPa) are designed and fabricated. These ceramics demonstrate excellent temperature-insensitive EMW absorption performance and thickness robustness, effectively absorbing X-band EMW across a temperature range from 25 °C to 900 °C at various thicknesses. This approach to developing temperature-insensitive dielectric ceramics significantly improves the performance and functionality of high-temperature EMW absorbing materials, thereby providing substantial guidance and reference value.