Comparison of microwave absorption performance under solid and hollow structures of ferroferric oxide nanospheres

Ferroferric oxide (Fe₃O₄), as the most widely studied and applied microwave absorption (MA) material, has important scientific and engineering value in studying the influence of its solid and hollow structures on its MA performance. Previous studies have mostly focused on the study of Fe₃O₄ at different scales, making it difficult to compare the effects of hollow and solid structures on MA performance. In this work, we prepared two types of Fe₃O₄ nanoparticles, solid and hollow, with the same radial size. At the same content, hollow Fe₃O₄ (H–Fe₃O₄) nanospheres exhibits superior MA performance. Essentially, the composite with 70 wt% H–Fe₃O₄ shows the best MA performance with the minimum reflection loss (RL_min) of −64.2 dB at 2.75 mm, and the corresponding bandwidth is 3 GHz. Such excellent MA performance is due to the hollow structure causing microwave attenuation enhancement. The research on MA loss mainly comes from polarization, natural ferromagnetic resonance and exchange resonance. The radar cross section (RCS) simulation results indicates that H–Fe₃O₄ has significant advantages in stealth protection.