Constructing heterogeneous conductive network with core-shell Ag@Fe3O4 for dual-band effective microwave absorption

The compatibility of effective microwave absorption for low and middle frequency range is still a huge challenge, which restricts the application prospect in the multi-band electromagnetic environment. To tackle the issue, the core-shell structured Ag@Fe3O4 composites are proposed in this work to construct heterogeneous conductive network, suppressing the conductive capacity and improving the interfacial polarization. The dominant contri-bution of polarization to the permittivity accelerates the decrease of quarter-wavelength thickness with fre-quency, which induces identical theoretical matching thickness over 2-18 GHz with the integral order of n =1 to n = 3. Combined with strong magnetic loss and appropriate dielectric loss, the Fe3O4/Ag composites finally reveal excellent absorption properties at both 2-12 GHz and 15-18 GHz bands. By adjusting the core radius and shell thickness, the sample with Fe3O4/Ag molar ratio of 3:1 achieves the broadest absorption bandwidth of 5.08 GHz, covering both 3.5-7.1 GHz and 16.6-18.0 + GHz. The CST simulations further confirm the RCS reduction of Ag@Fe3O4 composites for practical application. The findings open a new avenue to develop competitive ab-sorbers that can cope with multiband electromagnetic waves.