Optimizing electromagnetic attenuation properties via controlled dielectric polarization in Zn single-atom-decorated polymer-derived SiZnCN ceramics
The coordinated metal single-atoms (MSA) can significantly enhance the electromagnetic wave (EMW) absorption properties of materials through adjusting local electron structure and polarization relaxation. The symmetric electronic environments for EMW absorption have been extensively studied, but the asymmetric electron dispersion from an atomic-scale perspective is blurring puzzle. In this work, the amorphous polymer-derived SiZnCN ceramics with porous “Cheese” structure were prepared by regulating Zn coordination and pyrolysis temperature. The SiZnCN (15 wt% ZnAc doping) ceramics pyrolyzed at 1400 °C exhibits an effective absorption bandwidth (EAB) of 4.96 GHz at an ultrathin thickness of 1.28 mm. This SiZnCN ceramics after oxidized at 500 °C still possesses excellent high-temperature EMW absorption performance. Benefiting from the porous structure and coordinated single Zn atoms, the asymmetric electronic environment in amorphous SiZnCN ceramics is established, promoting electron/dipole and interfacial polarization. This work proposes an effective strategy to optimize electromagnetic wave absorption for high temperature by coordinating asymmetric electronic environments in disordered structures.
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