A novel synthesis of Porous Fe4N/carbon hollow microspheres for thin and efficient electromagnetic wave absorbers

Modulating the structure and morphology is essential in fabricating high-performance electromagnetic absorbing materials. Herein, we obtained porous Fe3O4/carbon hollow microspheres and porous Fe4N/carbon hollow microspheres derived from Fe-glycerol hollow microspheres. Through structure and morphology analysis, we proved the existence of porous and hollow features. By comparison, it can be found that the porous Fe4N/carbon hollow microspheres have electromagnetic wave absorption performance superior to that of porous Fe3O4/carbon hollow microspheres. The reflection loss value of porous Fe4N/carbon hollow microspheres reaches -42.2 dB at a matching thickness of merely 1.4 mm, and its effective absorbing bandwidth approaches 4.5 GHz, whereas the reflection loss of porous Fe3O4/carbon hollow microspheres in the 2-18 GHz range is over -10 dB. Reasons for the better electromagnetic wave absorption performance are revealed to be that the magnetic Fe4N has higher complex permittivity and complex permeability, and the porous hollow microspherical structure increases the multiple scattering and reflection of electromagnetic waves. Meanwhile, the impedance matching and attenuation constant are optimized together through the synergy of dielectric and magnetic loss. This research can provide instructive findings for thin-thickness electromagnetic wave absorbing materials based on Fe4N with an appropriate microstructure. (c) 2023 Elsevier Inc. All rights reserved.