Novel microwave absorber of Ni_xMn_1-xFe₂O₄/carbonized chaff (x = 0.3, 0.5, and 0.7) based on biomass

A novel magnetic nanocomposite of Ni_xMn_1-xFe₂O₄/carbonized chaff (x = 0.3, 0.5, and 0.7) has been synthesized successfully via the co-carbonization and hydrothermal method. The microstructure, morphology, complex permittivity and permeability, and microwave absorbing properties were systematically studied by X-ray diffraction, scanning electron microscopy, and a vector network analyzer. Compared to the pure Ni_0.5Mn_0.5Fe₂O₄ NPs, the Ni_0.3Mn_0.7Fe₂O₄/carbonized chaff-N₂ composite exhibits an optimal microwave absorption property at 4 mm as the mass percent of carbonized chaff is 10 wt %, the maximum reflection loss of which can reach-14.58 dB at 1.91 GHz with the-10 dB frequency bandwidth in the range of 1.46-2.41 GHz (0.95 GHz). The enhanced electromagnetic wave absorbing performance is ascribed to the good synergistic effect among laminated structures, better impedance matching condition, strong natural resonance loss, Debye dipolar relaxation to some extent, and so forth. Most importantly, this study provides a novel way to prepare easily degradable, environment-friendly, and high-efficiency electromagnetic wave absorbers by utilizing the structural property of renewable biomaterials.