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Fe/C core-shell nanofibers were prepared via a coaxial electrospinning technique integrated with high-temperature carbonization, in which the Fe(NO 3) 3 -containing PAN solution and Fe(NO 3) 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 characteristics, and electromagnetic wave absorption properties of the Fe/C nanofibers were investigated by adjusting the carbonization temperature. As-prepared Fe/C-800 °C core-shell nanofibers mixed with 10 wt% of paraffin showed a minimal reflection loss (RL min) 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. [ABSTRACT FROM AUTHOR]

Carbon/magnetic metal composites have attracted great interest in the microwave absorption field. Here, polyacrylonitrile (PAN)-based Fe/C nanofibers were fabricated through electrospinning in combination with high-temperature carbonization, which was used as difunctional dielectric and magnetic microwave absorbing materials. The Fe/C nanofibers fabricated were characterized by a high aspect ratio, and magnetic Fe nanoparticles had uniform distribution within dielectric carbon fibers. The Fe/C nanofibers had prominent performance in absorbing microwave because of favorable impedance matching condition, improved capability in attenuating microwave and synergistic influence between dielectric loss of PAN-based carbon materials and magnetic loss of Fe, which was correlated with the carbonization temperature as well as Fe content. The optical Fe content of 5 wt%, carbonization temperature of 1200 ℃, Fe/C/paraffin composites containing 10 wt% fillers had high performance in absorbing microwave, the reflection loss reaching the maximum of |RLmax| = 40.47 dB at 9.36 GHz at 2.5 mm matching thickness, as well as the effective bandwidth (EAB) of 4.64 GHz (13.36–18 GHz), covering 12.88–16.88 GHz at 1.6 mm thin thickness, which nanofibers were easy to obtain and were characterized by strong performance in absorbing microwave, thin thickness and light weight. Thus, the fabricated nanofibers can be recognized as a promising microwave absorber. [Display omitted] [ABSTRACT FROM AUTHOR]

One-dimensional PAN-based carbon nanofibers were prepared by electrospinning in combination with a high-temperature carbonization process. The prepared PAN-based nanofibers were characterized by a high aspect ratio. The microwave absorption property was adjusted by controlling the carbonization temperature. The carbonization temperature affected the degree of graphitization, which directly affected the dielectric loss and further improved the microwave absorption properties of PAN-based carbon nanofibers. The PAN-based carbon fibers were optimized in terms of both maximum reflection loss (RL min) and effective absorption bandwidth (EAB) after carbonization at 800 °C. The PAN-based carbon fiber/paraffin composites containing 10 wt% filler exhibited excellent absorption performance with a maximum reflection loss of − 12.75 dB and an effective absorption bandwidth of 4.88 GHz (13.12–18 GHz) at 2.2 mm, which basically covered the Ku-band (12.88–17.88 GHz). When the absorber thickness was 2.4 mm, the reflection loss at 14.4 GHz was − 11.39 dB, and the maximum effective absorption bandwidth was 5.04 GHz (11.92–16.96 GHz). PAN-based carbon nanofibers showed excellent absorption properties due to the dielectric loss in cooperation with good impedance matching. [Display omitted] [ABSTRACT FROM AUTHOR]