Development of spindle-cone shaped of Fe/α-Fe2O3 hybrids and their superior wideband electromagnetic absorption performance

Rational design on microstructure of magnetic material provides new opportunity to enhance the electromagnetic absorption performance. Herein, we demonstrate the successful preparation of spindle-cone of Fe/Fe₂O₃ and Fe₃O₄ samples with an average size of ∼1.2 μm, using a facile two-steps method. The well-defined spindle-cone shaped α-Fe₂O₃ was developed first by a solvothermal route and then reduced by H₂ or NaBH₄, respectively. The morphologies, phase compositions and magnetization of these as-prepared samples are analyzed by Field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and X-ray photoelectron spectrum (XPS) and vibrating sample magnetometer (VSM). Meanwhile, the electromagnetic (EM) absorption performance of Fe/Fe₂O₃ and Fe₃O₄ spindle-cones-paraffin composites with various filling ratios are also studied. The results reveal that Fe/Fe₂O₃ with a filling ratio of 50 wt% achieves the smallest reflection loss value of −26.2 dB at a thickness of 1.4 mm. At thinner thickness (1.0 mm), the bandwidth (RL < −10dB) equals to 4.5 GHz (13.5–18 GHz). The excellent absorption mechanism was discussed in this work, which attributed to the unique nanostructure and moderate impedance matching and EM loss ability.