Micro-Structural Design of CoFe2O4/SWCNTs Composites for Enhanced Electromagnetic Properties

Abstract

In order to prepare microwave-absorbing materials with low density and high wave absorption performance, CoFe2O4/SWCNTs composites with well-designed necklace-like structures were successfully prepared in this paper by a simple solvothermal method. CoFe2O4/SWCNTs composites with different cobalt salt contents were synthesized by adjusting the experimental parameters. The results of the relative complex permeability and relative permittivity of the samples, which were investigated by vector network analysis in the frequency range of 2 to 18 GHz, are collected to support the study of the microwave absorption characteristics of the samples. Different microsphere densities and different cobalt salt contents have obvious differences in the electromagnetic absorption properties of the composites. When the additions of FeCl3·6H2O, Co(Ac)2·4H2O, and NH4Ac were 0.432, 0.200, and 0.400 g, respectively, the best reflection loss reached −42.07 dB, and the effective absorption frequency (RL < −10 dB) ranges from 3.2 to 18 GHz. Therefore, this is a preparation strategy of CoFe2O4/SWCNTs composites with necklace structure, which has the advantages of simple process, environmental friendliness, low cost, and high stability. The unique necklace-like structure design makes the carbon nanotubes partially exposed, which is more beneficial to achieve good impedance matching and giving the CoFe2O4/SWCNTs composite excellent electromagnetic loss capability.

Molten salt synthesis of disordered spinel CoFe2O4 with improved electrochemical performance for sodium-ion batteries

“…56 In addition, the satellites peaks at 785.38 eV and 802.83 eV indicated the presence of unpaired 3d electron of the high spin Co 2+ . 57,58 In Fig. 4b exposed Fe 2p spectrum and displayed the Fe 2p 3/2 and Fe 2p 1/2 peaks at 710.54 and 723.58 eV, respectively.…”

Superior microwave absorption ability of CuFe2O4/MWCNT at whole Ku-band and half X-band

“…Decorating materials usually include magnetic nanoparticles, conductive polymers or ceramics which can improve absorption performance of carbon-based composites via magnetic, conductive or dielectric losses, respectively. [7][8][9] There are several reports indicating that decorating carbon material and CNTs with ferrite nanoparticles causes an extraordinary enhancement in the microwave absorption performance of resulting composites. For example, the reflection loss of CoFe 2 O 4 /CNTs reached À37.39 dB at a thickness of 1.7 mm, along with an effective absorption bandwidth of 5.2 GHz.…”

“…Decorating materials usually include magnetic nanoparticles, conductive polymers or ceramics which can improve absorption performance of carbon-based composites via magnetic, conductive or dielectric losses, respectively. 7–9…”

Ceramic Films and Coatings: Properties and Applications

“…Moreover, the Special Issue includes two papers discussing microwave absorbing materials. CoFe 2 O 4 /SWCNTs composites with a necklace-like structure were produced using a simple solvent-thermal method, which is conducive to good impedance matching and results in excellent electromagnetic loss performance [19]. MnO-Co@C nanorods with a core shell structure were produced via in situ polymerization and hightemperature carbonization processes.…”