Structural and Carbonized Design of 1D FeNi/C Nanofibers with Conductive Network to Optimize Electromagnetic Parameters and Absorption Abilities

Abstract

The optimized electromagnetic (EM) parameters are highly indispensable for outstanding microwave absorbers. Generally speaking, it is very necessary to suitably improve permittivity and permeability of the materials. The combination of magnetic/dielectric materials is a good choice. Herein, the irregular shaped FeNi/C composites were synthesized in N 2 atmosphere with unsatisfied EM parameters. To further optimize EM parameters and enhance microwave absorption abilities, constructing one-dimensional (1D) structure is also an excellent scheme. 1D FeNi/C nanofibers were successfully obtained by electrospinning technology combined with heat treatment. Enhanced microwave absorption abilities can be fulfilled by conductive network structure, better dielectric loss, and stronger interface polarization intensity. Moreover, carbonized time toward nanofibers plays a key role in microwave absorption, which could influence complex permittivity and dielectric loss of materials. It is found that FeNi/C nanofibers with highly carbonized degree display better microwave absorbing properties. The reflection loss (RL) values less than −10 dB can be observed in 12.8−17.2 GHz (a broad bandwidth of 4.4 GHz) with an absorber thickness of only 1.8 mm. The absorber with a thickness of 2.7 mm has the minimum RL value of −24.8 dB at 9.4 GHz. In this regard, these nanofibers are very likely to be used as EM-wave absorbers in practical application. Furthermore, this work provides a useful strategy to optimize electromagnetic parameters and absorption abilities of metal/carbon absorbers. It may promote the development of 1D metal/carbon composites in microwave absorption field.

Galvanic Replacement Reaction Involving Core–Shell Magnetic Chains and Orientation‐Tunable Microwave Absorption Properties

“…Regarding magnetic absorbers, 1D magnetic absorbing materials, such as FeNi/C nanofibers, [19] Fe/C nanofibers, [20] Fe nanowires, [21] Fe 3 O 4 @ carbon nanochain, [22] CoNi chains, [23] Ni chains, [24] and Co chains, [25,26] competitive EM wave absorption abilities and are lightweight and thin and have strong absorption because of the unique 1D structures, orientation polarization, and natural magnetic loss. [11,24,25] So far, it has been proven that the magnetic-field-induced synthesis is a process which mainly leads to the formation of magnetic metallic 1D nanostructures.…”

Nanofiber network with adjustable nanostructure controlled by PVP content for an excellent microwave absorption

“…Based on their researches, we can discover that the microwave absorption performance closely depends on their design of one-dimensional nanostructures on carbon nanofibers. In principle, morphology change of carbon nanofibers could dramatically influence the transferring path of the electrons as well as the construction of the conductive network 19 . Accordingly, the permittivity and polarization process would be controlled in the range of testing frequency artificially.…”

Most recent developments in electrospun magnetic nanofibers: A review

“…86 Using polycarbosilane and ferric acetylacetonate as precursors, Hou et al 87 88 found that by tailoring the mass ratio of soft and hard phases, the reflection loss and the bandwidth could be optimized for wide-band microwave absorption. A similar material was applied by Xiang et al 89 91 Similarly, Bayat et al 92 found the electromagnetic shielding properties of electrospun Fe 3 O 4 /C nanofibers related to the carbonization temperature and the magnetite nanoparticle diameter. Absorption of thermal neutrons was investigated for PAN containing gadolinium, showing that the addition of this rare earth magnetic material significantly reduced the neutron transmissivity even through a thin shield.…”