Fabricating Fe3O4 and Fe3O4&Fe Flower-Like Microspheres for Electromagnetic Wave Absorbing in C and X Bands

Magnetic composites have received increasing attention for electromagnetic wave absorption (EMA) applications. However, the practical EMA performance of the materials is severely hampered by mismatching impedance characteristics and finite electromagnetic attenuation capacity. Controlling the components and building the architecture fabrication is necessary to solve these issues. Herein, a series of Fe3O4, Fe3O4&Fe and Fe microspheres with flower-like hierarchical structures were constructed through a solvothermal method followed by an annealed process. This hierarchical structure and the synergy effect of dielectric dissipation and magnetic loss capacity offer Fe3O4 a perfect impedance matching, providing an excellent EMA performance of an effective absorption bandwidth (EAB) of 4.0 GHz and a reflection loss (RL) of 67.9 dB. Meanwhile, the coordination of the hierarchical structures and the multiple components endow Fe3O4&Fe composites with an EAB as wide as 5.7 GHz (9.0–14.7 GHz) and a RL as strong as 78.7 dB at 1.88 mm, which covers 75% X and 45% Ku bands. Such a remarkable lightweight and broad properties is due to the decent X band impedance matching and appropriate attenuation capacity. Therefore, this work highlights the significant of regulating the hierarchical structure and components to enhance the EMA performances.