Preparation and enhanced microwave absorption properties of Ni-Co attached single-walled carbon nanotubes and CoFe2O4 nanocomposites

Abstract

The electromagnetism and microwave absorption properties were investigated in the frequency range of 2–18 GHz for the nanocomposites NiCo-SWCNTs/CoFe2O4 consisting of Ni-Co attached single-walled carbon nanotubes (NiCo-SWCNTs) and CoFe2O4 nanocrystals with different ingredient weight ratios. NiCo-SWCNTs were mass-produced by a direct current arc discharge in helium and CoFe2O4 was synthesized by a sol-gel method. Premium microwave absorption properties (mainly in Ku-band, i.e., 12–18 GHz) were obtained due to the appropriate combination of the complex permeability and permittivity resulting from the magnetic nanocrystals and high-crystalline NiCo-SWCNTs. The NiCo-SWCNTs/CoFe2O4 nanocomposites with 15 wt. % NiCo-SWCNTs exhibited the best microwave absorption property, whose reflection loss (RL) value reached −47.9 dB at 14.7 GHz and the absorption bandwidth (RL<−10 dB) was up to 7.1 GHz (from 10.5 to 17.6 GHz) with a matching thickness of only 1.8 mm. Our results indicate that the studied nanocomposite could be used as a promising candidate for lightweight microwave absorption materials.

Cross-Linking-Derived Synthesis of Porous CoxNiy/C Nanocomposites for Excellent Electromagnetic Behaviors

“…(ii) Adequate magnetic loss mechanisms. As already discussed in Figure , all three Co x Ni y /C samples possess hysteresis loss , at the applied field, which is helpful to the enhanced EM wave absorption. Eddy current loss , occurs in the three Co x Ni y /C composites, especially at high frequency.…”

Large-scale preparation of Co nanoparticles as an additive in carbon fiber for microwave absorption enhancement in C band

“…For the XAFS spectrum of Co, the two fitting peaks of Co2p Microwave absorption property. In order to further explore the microwave absorption characteristics of Co/PCNF, two important parameters, the complex permittivity (ε r = ε′ − jε″) and complex permeability (μ r = μ′ − jμ″), were determined by a vector network analyzer 23 . Specifically, the real part of permittivity ε′ (and permeability μ′) are related to the storage of electromagnetic energy and the imaginary part of permittivity ε″ (and permeability μ″) represent the loss of electromagnetic energy 24,25 .…”

Magnetic properties of the ferrimagnetic triangular nanotube with core–shell structure: A Monte Carlo study

“…Experimentally interesting magnetic behaviors have been observed in core-shell nanotubes [53][54][55][56], which motivate us to carry theoretical calculations based on Monte Carlo simulations based on the Metropolis update protocol to better understand these magnetic properties core-shell nanotubes. Thus, in this work, we use Monte Carlo simulation within the framework of the Ising model to study several magnetic properties of the core-shell triangular nanotube structure, considering the effect of anisotropy interaction and the interaction of different spins with an external magnetic field.…”