Microwave absorption performance of magnetic-dielectric Fe₃O₄@C@PPy composites with a core-double-shell structure prepared by a low-temperature self-propagation method

Microwave absorbers have been developed to counter electromagnetic pollution, and enhancing their performance remains an ongoing concern. In this paper, carbon-coated Fe3O4 and polypyrrole (PPy) were combined to construct composites with a core-double-shell structure, and the influences of multiple synergistic effects from ternary components, carbon defects, and microstructure on the electromagnetic properties of Fe3O4@C@PPy composites were investigated. The Fe3O4@C@PPy composites were successfully prepared by the lowtemperature self-propagation method and in-situ oxidation polymerization process, achieving a -53.67 dB reflection loss at 12.24 GHz when the sample thickness was 2.13 mm, and the effective absorbing (RL < 10 dB) band covered 4.16 GHz (13.84-18 GHz) with a corresponding thickness of only 1.63 mm. The core-double-shell structure perfectly integrated various advantages of each component as well as provided multiple reflections and scatterings. Meanwhile, the polarization loss was notably enhanced by heterogeneous interfaces, and the dielectric-magnetic loss mechanism cooperatively accelerated the dissipation of electromagnetic wave energy.