Wrinkle Structure Regulating Electromagnetic Parameters in Constructed Core‐shell ZnFe2O4@PPy Microspheres as Absorption Materials

Abstract

AbstractStructure engineering of magnetic‐dielectric multi‐components is emerging as an effective approach for presuming high‐performance electromagnetic (EM) absorption, but still faces bottlenecks due to the ambiguous regulation mechanism of surface morphology. Here, a novel wrinkled surface structure is tailored on the ZnFe2O4 microsphere via a spray‐pyrolysis induced Kirkendall diffusion effect, the conductivity of the sample is affected, and a better impedance matching is adjusted by modulating the concentration of metal nitrate precursors. Driven by a vapor phase polymerization, conductive polypyrrole (PPy) shell are in situ decorated on the ZnFe2O4 microsphere surfaces, ingeniously constructing a core‐shell ZnFe2O4@PPy composites. Moreover, a systematic investigation reveals that this unique wrinkled surface structure is highly dependent on the metal salt concentration. Optimized wrinkle ZnFe2O4@PPy composite exhibits a minimum reflection loss (RLmin) reached −41.0 dB and the effective absorption bandwidth (EAB) can cover as wide as 4.1 GHz. The enhanced interfacial polarization originated from high‐density ZnFe2O4‐PPy heterostructure, and the conduction loss of PPy contributes to the boosted dielectric loss capability. This study gives a significant guidance for preparing high‐performance EM composites by tailoring the surface wrinkle structure.