Enhanced broadband microwave absorption of Fe/C core-shell nanofibers in X and Ku bands

Fe/C core-shell nanofibers were prepared via a coaxial electrospinning technique integrated with high-temperature carbonization, in which the Fe(NO3)3-containing PAN solution and Fe(NO3)3 constituted the shell and core structures, respectively. The core-shell structure was perfectly maintained after carbonization, and Fe nanoparticles were uniformly distributed within the carbon nanofibers. The effects of the microscopic morphology and crystallinity of the carbon components on the electromagnetic properties, matching charac-teristics, and electromagnetic wave absorption properties of the Fe/C nanofibers were investigated by adjusting the carbonization temperature. As-prepared Fe/C-800 degrees C core-shell nanofibers mixed with 10 wt% of paraffin showed a minimal reflection loss (RLmin) of-20.6 dB under 11.52 GHz at 2.5 mm of thickness and lower than-20 dB under 2.3-5.0 mm of thickness. The efficient absorption bandwidth (EAB) was 6.24 GHz in the range of 11.76-18 GHz at 2.1 mm, covering the whole Ku band. The absorption bandwidth can cover the whole X and Ku bands by varying the sample thickness. The efficient absorption bandwidth was 3.84 GHz in the range of 8.08-11.92 GHz at 2.9 mm, covering the X band. The effective complementarities between the magnetic loss of Fe nanoparticles, the dielectric loss of PAN-based carbon, and the core-shell structure promoted impedance matching and multiple interface polarization, endowing the produced composites with prominent absorption characteristics of microwaves. Therefore, the prepared Fe/C core-shell nanofibers are an ideal lightweight and broadband electromagnetic wave (EMW)-absorbing material that exhibits high-performance microwave absorption.

Automated summary

Fe/C core-shell nanofibers were prepared by coaxial electrospinning and high-temperature carbonization. The core-shell structure was maintained after carbonization and Fe nanoparticles were distributed within the carbon nanofibers. The electromagnetic properties, matching characteristics, and electromagnetic wave absorption properties of the Fe/C nanofibers were affected by the microscopic morphology and crystallinity of the carbon components.