Pea-like Fe/Fe₃C Nanoparticles Embedded in Nitrogen-Doped Carbon Nanotubes with Tunable Dielectric/Magnetic Loss and Efficient Electromagnetic Absorption

Abstract

One-dimensional microstructure has been regarded as one of the most desirable configurations for magnetic carbon-based microwave absorbing materials (MAMs). Herein, pea-like Fe/Fe 3 C nanoparticles embedded in nitrogen-doped carbon nanotubes (Fe/Fe 3 C@NCNTs) are successfully prepared through a direct pyrolysis of the mixture of FeCl 3 •6H 2 O and melamine under inert atmosphere. The chemical composition and microstructural feature of these Fe/ Fe 3 C@NCNTs composites are highly dependent on the pyrolysis temperature. As a result, their electromagnetic properties can be also manipulated, where dielectric loss gradually decreases with the increasing pyrolysis temperature and magnetic loss presents a reverse variation trend. When the pyrolysis temperature reaches 600 °C, the as-obtained composite, Fe/Fe 3 C@NCNTs-600 can perform a maximum reflection loss of −46.0 dB at 3.6 GHz with a thickness of 4.97 mm and a qualified bandwidth of 14.8 GHz with the integrated thickness from 1.00 to 5.00 mm. It is very interesting that the microwave absorption performance of this new kind of composites is not so susceptible to the pyrolysis temperature as those common magnetic carbon-based MAMs because there is an effective balance between dielectric loss and magnetic loss, which accounts for a very stable attenuation ability when the pyrolysis temperature range changes from 600 to 700 °C. These favorable characteristics, including low-cost raw materials, easy preparation, and stable performance, may render Fe/Fe 3 C@NCNTs composites as a novel kind of MAMs in the future.

Iron Carbides: Control Synthesis and Catalytic Applications in COx Hydrogenation and Electrochemical HER

“…Carbon‐rich organic and carbon nanomaterials could be used as solid carbon sources, which result in the generation of Fe 3 C, a type of FeC x with the lowest carbon content . The Fe 3 C/C hollow spheres were synthesized via a high‐pressure pyrolysis of ferrocene and cyanamide at 700 °C in N 2 .…”

NiFe2O4 nanoparticles supported on cotton-based carbon fibers and their application as a novel broadband microwave absorbent

“…When the matching thickness is 2.4 mm, the effective bandwidth can reach up to 6.5 GHz , which covers the entire Ku-band (12)(13)(14)(15)(16)(17)(18). Even more interesting is the fact that when increasing the matching thickness to 3.2 mm, the optimal microwave absorption values less than À10 dB are in the range of 8.0-12.7 GHz, which covers the entire X-band (8)(9)(10)(11)(12). Therefore, the microwave absorption value less than À10 dB of NiFe 2 O 4 /CCF-2 can cover both X-band and Ku-band at a certain thickness.…”

“…[3][4][5][6] So far, carbon-based composite MAMs have attracted a lot of attention, and the carbon matrix materials which were used to prepare magnetic material/carbon composite MAMs were mainly carbon bers, carbon nanotubes, graphene and metal-organic framework compounds. [7][8][9][10][11] For example, Cao et al synthesized Fe 3 O 4 -MWCNTs composites through co-precipitation route, and the minimum RL value reached À52.8 dB at 12.8 GHz, which was superior to the pure MWCNTs. 12 Ji et al synthesized Fe-Co/nanoporous carbon by the method of carbonizingdehydro-ascorbic acid (DHAA) coated Fe 3 O 4 nanoparticles encapsulated in zeolitic imidazolate framework-67, and the absorption bandwidth for RL < À10 dB covered from 12.2 to 18 GHz.…”

Oxygen-sulfur Co-substitutional Fe@C nanocapsules for improving microwave absorption properties

“…In particular, core-shell heterostructures exhibit the optimized electromagnetic wave absorption performance by integrating the complex permittivity (e r =e 0 Àie}), complex permeability (l r =l 0 Àil}) and the impedance matching between them. In addition, the nanoscale ferromagnetic metal-and metal oxide-based cores have been widely investigated because of the higher Snoek limit than traditional metal and/or metal oxide materials [9][10][11][12][13].…”