Entropy-Driven Ultra-Broadband High-Temperature Electromagnetic Absorption in Spinel Oxides up to 1000°C.

Ultra-broadband high-temperature electromagnetic (EM) ceramic absorbers are extensively desired for next-generation radar stealth technologies; however, current absorbers are far from satisfactory. Here, we employ an entropy-driven strategy to develop an innovative (Co, Ba, Fe, Mg, Cr, Ni, Sr, Ca, Mn)Fe2O4 high-entropy spinel oxide absorber, which possesses an ultrabroad effective absorption bandwidth (EAB) of 13.1 GHz at room temperature (RT), along with a wide-temperature EAB retention of ∼100% up to 1000°C. This ultrabroad high-temperature EM absorption performance mainly stems from the highly stable impedance matching enabled by the entropy-driven sustenance of oxygen vacancy concentration at elevated temperatures, as well as the entropy-driven amplification of EM dissipation via an atomic-interface polarization loss. This work not only presents a promising EM absorber for future high-temperature applications, but, more importantly, provides a key mechanistic insight that can be a guide for exploring high-entropy ceramic absorbers with enhanced absorption performance.