Hollow magnetic Fe₃O₄ nanospheres for excellent electromagnetic wave absorption

The construction of lightweight magnetic electromagnetic (EM) wave absorption materials is of great significance for the development of EM wave absorption materials. Herein, hollow magnetic Fe3O4 (H-Fe3O4) nanospheres were successfully prepared by hydrothermal method. Analysis of EM parameters indicates that the formation of local conductive and magnetic networks caused by H-Fe3O4 aggregation effects leads to the significantly enhancement of permittivity and permeability. In particular, the H-Fe3O4 composite with a thickness of 2.15 mm achieved the minimum reflection loss of -50.25 dB and the corresponding bandwidth (<-10 dB) was 3.4 GHz. The synergistic effects of ferromagnetic resonance and exchange resonance and polarizations leads to excellent absorption performance. The radar cross section (RCS) simulation indicated that the RCS reduction value of H-Fe3O4 composite can reach 29.8 dB m(2) under the incident angle of 20 degrees. Moreover, the metastructure design shows an ultra-wide EM wave absorption bandwidth. This work can provide ideas for the design and application of ultra-light magnetic materials.