Large Electromagnetic Wave Absorbing Bandwidth of Composites Containing Fe3O4 Nanoribbons

Fe₃O₄ nanoribbons with the average size of ~17.2 nm × 64.3 × 939.1 nm have been synthesized by a hydrothermal method. The crystal structures have been investigated by means of the X-ray diffraction pattern refinement. The frequency dependence of permittivity and permeability for a composite containing the nanoribbons has been studied within 0.5-10 GHz. Interestingly, four resonance peaks of permeability spectra have been observed within the whole measurement frequency range. To investigate the physical origins of multiresonances, the modified exchange resonance model is used. The calculated nature resonance frequency and exchange resonance frequencies are in accordance with the experimental resonance peaks. However, four low-order resonance modes have not been found. The absence of these modes can be attributed to the dispersion of nanoribbons sizes. In addition, the imaginary part of permittivity is too small compared with the real part, indicating the insignificant contribution of dielectric loss to the electromagnetic wave absorption. What is more, large magnetic losses caused by the multiresonance phenomenon are beneficial to broadband absorption within the operating frequencies. For instance, the maximum bandwidth is larger than 4 GHz with the reflection loss less than -10 dB.