Dielectric regulation of high-graphitized fine ash wrapped cube-like ZnSnO3 composites with boosted microwave absorption performance

Intrinsic dielectric properties and tuning conductivity play important roles in microwave absorption. Novel multi-interfaced ZnSnO3@ fine ash (ZSFA) composite was successfully synthesized by coating cube-like ZnSnO3 particles with highly graphitized gasification fine ash. After hydrothermal reaction and Ostwald ripening process, fine ash was tightly wrapped around the assembly of ZnSnO3 particles. Related electromagnetic parameters and dielectric dissipation ability were discussed with different mass additions. Owing to the strong polarization relaxation, special conductive network, and multi-interface structural design, the as-synthesized ZSFA exhibited adjustable dielectric loss behaviors and efficient microwave absorption ability. When 50% mass added, the maximum reflection loss value of the obtained ZSFA-2 is −47.8 dB at 2.5 mm thickness, showing the enhanced dielectric loss ability. Meanwhile, the widest effective absorption bandwidth (RL ≤ −10 dB) can cover 7.0 GHz (11.0–18.0 GHz) at a thickness of only 2.2 mm, which included the entire Ku band. This unique pure dielectric composite exhibited high-performance electromagnetic wave attenuation property and broadband frequency response, thereby providing a new approach to the production of a superior microwave absorber.