Metasurface-based multifunctional composites with ultra-robust broadband microwave absorption up to 1000 °C

The metamaterials offer methodology and infinite possibilities for ultra-broadband microwave absorption (MA). However, maintaining stable broadband MA under extreme high-temperature environments remains one of the most cutting-edge challenges. Herein, we report a RuO₂/glass resistive material for the fabrication of microwave-absorbing metasurfaces. Based on tunneling effect, an ultra-low temperature coefficient of resistance was achieved in RuO₂/glass, resulting in temperature-insensitivity of its electrical properties, thereby ensuring stability of MA properties of metasurfaces against temperature. Furthermore, using low-dielectric alumina aerogel composites and Al₂O_3f/Al₂O₃ ceramic composites as dielectric spacer layer, we propose the multifunctional composites integrated with MA, thermal insulation and load-bearing (MTL). The MTL integrated composites show an impressive broadband (2~12 GHz) MA performance that is ultra-robust against temperature variations (25~1000 °C), thermal shock (50 cycles at 25~1000 °C), incidence angle (±45°) and polarization. Additionally, the integrated composites also demonstrate a long-term thermal insulation ability and a high compressive modulus (6.58 MPa). This advancement provides insights for developing MA materials that can work in extreme multi-field environments.