An Ultra-Broadband Electromagnetic Wave Absorbing ZrB₂-Based Ceramic Composite Inspired by Barbule of Peacock

Broadband electromagnetic wave (EMW) absorbing ceramic materials are highly required for the thermal parts of aerocraft. As members of ultrahigh temperature ceramics, ZrB₂-based ceramics have great potential for applications in more extreme environments relative to the currently used silicon-based and oxide-based ceramics. However, ZrB₂ is not among the traditional EMW absorbing material candidates due to its high conductivity, which induces the strong reflection of EMW due to the impedance mismatch with free space. Herein, ZrB₂-based ceramic with a bionic microstructure inspired by peacock barbules is proposed. Boron nitride nanotubes acting as polarization centers inside the ZrB₂-based material cause massive EMW dissipation. The ceramic shows an ultra-broadband absorption of 9.6 GHz (<-10 dB from 8.4 to 18 GHz), almost covering the entire X and Ku bands, superior to the reported ceramics. The polarization centers successfully turn the ZrB₂-based ceramic from EMW reflecting material to an excellent EMW absorbing material by the bionic barbule interspersed microstructure. The simulated metamaterial of the ceramic achieves an ultra-broad absorption (lower than -15 dB) in the range of 2-40 GHz. This work provides valuable insights for the development of broadband absorption material for high-temperature environments.