High-temperature oxide ceramic microwave absorber enabled by thermionic migration mediated by electron delocalization
Ruopeng Cui, Zewen Duan, Yi Li, Xuefei Zhang, Xiangyang Liu, Guang Yang, Lihong Yang, Biao Zhao, Chunlei Wan
Abstract
The escalating demand for long-term high-temperature microwave-absorbing materials (HTMAMs) in high-speed aerospace stealth is hindered by limitations such as magnetic loss degradation or oxidation risks. Herein, we introduce rare earth zirconate ceramics that exhibit air stability up to 1600 °C. Abundant oxygen vacancies significantly enhance permittivity and thus microwave-absorbing performance through activated thermionic migration at elevated temperatures. Moreover, the thermionic-facilitated permittivity can be meticulously modulated by electron delocalization, with the extent governed by lattice disorder. We demonstrate this concept through a dual-layer Er2Zr2O7/Gd2Zr2O7 structure to further optimize impedance matching, achieving an ultra-wide bandwidth (8.27 GHz) and strong absorption (−64.61 dB) at ultrathin thicknesses under 1.2 mm at 600 °C mainly by macroscopic interfacial resonance, alongside an ultralow thermal conductivity (1.61 W•m-1•K-1). This work presents an innovative approach to design high-performance and anti-oxidative HTMAMs through thermionic migration tuned by electron delocalization, advancing structural-functional integrated materials for extreme environments. High-temperature, ultrathin, and high-performance microwave absorption is realized in the dual-layer structure with rare earth zirconate ceramics via electron delocalization-mediated thermionic migration and macroscopic interfacial resonance.