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.