Broadband electromagnetic-wave absorption by FeCo/C nanocapsules

Abstract

Electromagnetic-wave absorption by FeCo/C nanocapsules has been investigated. In contrast to earlier reported materials, including other nanocapsules, the absorption amplitude of FeCo/C nanocapsules is found not to decrease with increasing absorption-layer thickness. A reflection loss ͑RL͒ exceeding Ϫ20 dB can be obtained for all frequencies within the 2-18 GHz range by choosing an appropriate layer thickness between 1.6 and 8.5 mm. The broadest bandwidth ͑RL values exceeding Ϫ10 dB͒ from 10 to 18 GHz, covering half of the X-band and the whole K u-band, is obtained for a 2 mm layer.

Tuning Carbon Content and Morphology of FeCo/Graphitic Carbon Core–Shell Nanoparticles using a Salt‐Matrix‐Assisted CVD Process

“…[ 3,[6][7][8][9][10] FeCo/graphitic carbon (FeCo/GC) core-shell nanoparticles have been suggested as a promising material for multipurpose diagnosis and therapeutic applications such as magnetic resonance imaging (MRI), near-infrared (NIR) photothermal therapy, and drug delivery [ 11 ] owing to their combination of a highly magnetic metal core and a graphitic carbon shell with a suitable absorbance of near-infrared (NIR) light and capability of loading drugs (i.e., doxorubicin (DOX)) through π -stacking. They have been also used for other applications including electromagnetic (EM)-wave absorption [ 12 ] and as a support for acid catalysts. [ 13 ] FeCo nanoparticles with graphitic shells have been fabricated through various methods including methane chemical vapor deposition, [ 3 ] radio-frequency plasma torch, [ 4 ] thermal conversion of Prussian blue analogues, [ 6 ] and an arc-discharge process, [ 12,14 ] but a scalable, effi cient, and controllable method for coating metal nanoparticles with a high-quality graphitic shell has thus far been elusive.…”

A cost effective solution for development of broadband radar absorbing material using electronic waste

“…The dielectric and magnetic loss tangents values are found to have opposite trend with frequency. Han et al [26] has also reported a quite similar loss spectrum for FeCo/C nanocapsules based system. They speculated the enhancement of absorption results from an excellent synergistic effect of magnetic and dielectric losses of the material.…”

Synthesis, characterization and microwave absorption of carbon-coated Cu nanocapsules

“…As shown in Figure 3b, for all frequencies within the 1-18 GHz range, RL values exceeding -20 dB can be obtained by selecting an appropriate thickness of the absorbent layer between 1.1 and 10.0 mm. Compared with other carboncoated nanoparticles or nanowires (e.g., Sn/C [3] , Ni/C [28] , FeNi/C [10] , FeCo/C [29] , and FeCoNi/carbon nanotubes [30] ), the non-magnetic carbon-coated Cu nanocapsules present quite different and excellent EM-wave absorption properties, which may be due to the special microstructure of the Cu nanocapsules, the size of the Cu nanocapsules, and also the weight fraction of paraffin-Cu nanocapsules composite 3 . Generally, there are two mechanisms of energy attenuation in materials: magnetic loss and dielectric loss 3 .…”