Synthesis, multi-nonlinear dielectric resonance and electromagnetic absorption properties of hcp-cobalt particles

Wen, Shulai; Liu, Ying; Zhao, Xiuchen; Cheng, Jingwei; Li, Hong

doi:10.1016/j.jmmm.2013.10.030

Cited by 26 publications

(14 citation statements)

References 37 publications

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“…No coercive force exists in the hysteresis loop at 300 K, further indicating the FCC-Co/C nanocapsules are superparamagnetic. The M S of FCC-Co/C nanocapsules at 300 K is 70.4 emu/g, which is smaller than the highest values reported for the bulk cobalt (162 emu/g) and the 133.29 emu/g of HCC-Co particles 19,20 . This difference in the bulk property is explained by weakly coupled and more disordered spins on the surface and the existence of a nonmagnetic C component 5,11 .…”

Section: Charaterization Of Fcc-co/c Nanocapsulescontrasting

confidence: 54%

“…The value of ' µ decreases from 1.19 to 0.98 with increasing frequency, which shows excellent frequency dispersion. The '' µ has a resonance peak at 6.4 GHz, and the large resonance band is observed in the range of 4-14 GHz, which is corresponding to the multi-magnetic resonance, like in CoNi/C nanocapsules, HCP-Co nanoparticles and Co nanoflakes 20,23,24 . In our previous papers, the resonance frequency at 6.4 GHz is due to the large anisotropy energy.…”

Section: Microwave Absorbing Properties Of Fcc-co/c Nanocapsulesmentioning

confidence: 99%

“…One peak may result from the relaxation loss of permanent electric dipoles due to defects in the amorphous carbon shell demonstrated by the TEM image in Figure 2b. The other peaks can be explained on the basis of space charge polarization model of Wagner 21 and Maxwell 20 According to space charge polarization model, the increase of ' ε of complex permittivity at higher frequencies can be attributed to the interfacial space-charge polarization which arises from the heterogeneous mixtures. Interfacial polarization is always present in heterogeneous mixtures including more than one phase like the FCC-Co/C-paraffin composites.…”

Section: Microwave Absorbing Properties Of Fcc-co/c Nanocapsulesmentioning

confidence: 99%

“…When an external electric filed is applied, the space charge can be appeared, due to the fact that the motion of charges will be hindered at various points of the components material. The appearance of such space charge can distort the macroscopic field and appears as polarization to an external observer 20 . Interfacial polarization is present in materials with considerable electrically heterogeneous.…”

Section: Microwave Absorbing Properties Of Fcc-co/c Nanocapsulesmentioning

confidence: 99%

See 3 more Smart Citations

Large Scale Synthesis of Superparamagnetic Face-centered Cubic Co/C Nanocapsules by a Facile Hydrothermal Method and their Microwave Absorbing Properties

Liu

Zhou

et al. 2015

Mat. Res.

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A large scale direct hydrothermal method has been used to prepare face-centered cubic (FCC) Co/C nanocapsules with a core of FCC-Co nanoparticles and a shell of amorphous C. The size distribution is 5-20 nm. The T B of FCC-Co/C nanocapsules is determined as 85 K, indicating that FCC-Co/C nanocapsules are superparamagnetic at 300 K. For FCC-Co/C nanocapsules-paraffin composite, an optimal reflection losbs (RL) of -33.4 dB is observed at 9.6 GHz for the 2.6 mm thick layer. RL values exceeding -20 dB in the 7.4 -15 GHz range are obtained by choosing an appropriate absorption-layer thickness between 1.7 and 3.3 mm. The good microwave absorbing properties of FCC-Co/C nanocapsules is considered to result from the excellent synergetic effect of the multi-dielectric relaxation loss and the multi-magnetic resonance loss. Quantitative calculation demonstrated that not only RL peak position but also the number of the peaks are determined by the quarter-wavelength cancellation model.

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Section: Charaterization Of Fcc-co/c Nanocapsulescontrasting

confidence: 54%

Section: Microwave Absorbing Properties Of Fcc-co/c Nanocapsulesmentioning

confidence: 99%

Section: Microwave Absorbing Properties Of Fcc-co/c Nanocapsulesmentioning

confidence: 99%

Section: Microwave Absorbing Properties Of Fcc-co/c Nanocapsulesmentioning

confidence: 99%

See 2 more Smart Citations

Large Scale Synthesis of Superparamagnetic Face-centered Cubic Co/C Nanocapsules by a Facile Hydrothermal Method and their Microwave Absorbing Properties

Liu

Zhou

et al. 2015

Mat. Res.

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“…Figure 2 shows the typical morphology of the products with different magnifications. The SEM image in Figure 2a The r ε and r µ of the paraffin-based composites are fundamental physical quantities in determining the microwave absorbing properties 15 . Figure 3a shows the frequency (f) dependence of r ε for the paraffin-bonded Ni architecture composites.…”

Section: Fm M;mentioning

confidence: 99%

Hydrothermal Synthesis of Three-dimensional Butterfly-like Ni Architectures as Microwave Absorbers

Sun

Cui

et al. 2015

Mat. Res.

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Three-dimensional butterfly-like Ni architectures were fabricated by a surfactant-assisted hydrothermal method. The Ni architectures, with lengths of about 20 μm and widths of 4-6 μm, were assembled from tens of Ni nanorods with the averaged diameter of about 200 nm. The Ni nanorods were coated by oxide shells. The saturation magnetization of the Ni architectures was found to be 66.2 emu/g. The magnetic loss in the Ni architectures was mainly caused by the natural resonance, while the dielectric relaxation loss was originated from the interfacial relaxation between the oxide shells and the Ni nanorods in addition to the size distribution and morphology of the Ni architectures. Absorbers with a thickness of 2.1 mm exhibited an optimal reflection loss (RL) value of -38.9 dB at 12.8 GHz. RL values exceeding -20 dB in the 8.0-17.8 GHz range were obtained by choosing absorber thicknesses between 1.5 and 3.2 mm. A quarter-wavelength cancellation model was used to explain the observed thickness dependence of RL peak frequency.

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Fabrication and microwave absorption properties of the flaky carbonyl iron/FeSiAl composite in S-band

Xie

et al. 2018

J Mater Sci: Mater Electron

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Synthesis, multi-nonlinear dielectric resonance and electromagnetic absorption properties of hcp-cobalt particles

Cited by 26 publications

References 37 publications

Large Scale Synthesis of Superparamagnetic Face-centered Cubic Co/C Nanocapsules by a Facile Hydrothermal Method and their Microwave Absorbing Properties

Large Scale Synthesis of Superparamagnetic Face-centered Cubic Co/C Nanocapsules by a Facile Hydrothermal Method and their Microwave Absorbing Properties

Hydrothermal Synthesis of Three-dimensional Butterfly-like Ni Architectures as Microwave Absorbers

Fabrication and microwave absorption properties of the flaky carbonyl iron/FeSiAl composite in S-band

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