Controllable preparation and microwave absorption properties of shape anisotropic Fe3O4 nanobelts

To substantially prevent electromagnetic threatens, microwave absorbing materials (MAMs) are required to eliminate surplus electromagnetic waves. As a typical MAM, Fe 3 O 4 particles with complex permittivity and permeability have been widely applied due to the coexistence of magnetic loss and dielectric loss. However, the necessary high mass fraction significantly limited its applications, thus Fe 3 O 4 nanostructures have been extensively investigated to overcome this problem. In this work, uniform Fe 3 O 4 nanobelts were prepared by electrospinning and two-step thermal treatment. By controlling the composition and viscosity of the electrospinning precursor solution, Fe 3 O 4 nanobelts with tunable lateral sizes (200 nm–1 μm) were obtained. The samples with low content (only 16.7 wt%) Fe 3 O 4 exhibited wide maximum effective absorbing bandwidths (EAB) over 3 GHz, and Fe 3 O 4 nanobelts with smaller lateral sizes showed a maximum EAB of 4.93 GHz. Meanwhile, Fe 3 O 4 nanobelts with smaller lateral sizes presented superior reflection loss properties, the lowest reflection loss reached −53.93 dB at 10.10 GHz, while the maximum EAB was up to 2.98 GHz. The excellent microwave reflection loss of Fe 3 O 4 nanobelts was contributed to the enhanced synergistic effect of magnetic loss, dielectric loss, and impedance matching, originated from the hierarchically cross-linked networks and shape anisotropies. This study could broaden the practical applications of magnetic absorbers, and provided an approach for the development of shape anisotropic magnetic materials.