Dielectric and microwave absorption properties of fluoride-doped MWCNT/Si3N4 composite

Saleem, Adil; Zhang, Yujun; Gong, Hongyu; Majeed, Muhammad K.; Lin, Xiao; Jing, Jie; Sheng, Mingming; Zhao, Cuncai

doi:10.1007/s10854-019-02836-2

Cited by 16 publications

(3 citation statements)

References 35 publications

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“…f denotes the frequency of the microwave in free space, d is the thickness of the absorbing material, and c is the propagation velocity of the electromagnetic wave in free space [ 28 , 29 ]. Here, the real parts of permittivity and permeability ( ε′ and μ′ ) indicate the ability to store electromagnetic energy, and the imaginary parts of permittivity and permeability ( ε″ and μ″ ) indicate the ability to lose electrical energy [ 30 , 31 ].…”

Section: Resultsmentioning

confidence: 99%

Enhanced Electromagnetic Wave Absorption Properties of Ultrathin MnO2 Nanosheet-Decorated Spherical Flower-Shaped Carbonyl Iron Powder

Wang

Yang

et al. 2021

Molecules

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In this work, spherical flower-shaped composite carbonyl iron powder@MnO2 (CIP@MnO2) with CIP as the core and ultrathin MnO2 nanosheets as the shell was successfully prepared by a simple redox reaction to improve oxidation resistance and electromagnetic wave absorption properties. The microwave-absorbing properties of CIP@MnO2 composites with different filling ratios (mass fractions of 20%, 40%, and 60% after mixing with paraffin) were tested and analyzed. The experimental results show that compared with pure CIP, the CIP@MnO2 composites have smaller minimum reflection loss and a wider effective absorption bandwidth than CIP (RL < −20 dB). The sample filled with 40 wt% has the best comprehensive performance, the minimum reflection loss is −63.87 dB at 6.32 GHz, and the effective absorption bandwidth (RL < −20 dB) reaches 7.28 GHz in the range of 5.92 GHz–9.28 GHz and 11.2 GHz–15.12 GHz, which covers most C and X bands. Such excellent microwave absorption performance of the spherical flower-like CIP@MnO2 composites is attributed to the combined effect of multiple beneficial components and the electromagnetic attenuation ability generated by the special spherical flower-like structure. Furthermore, this spherical flower-like core–shell shape aids in the creation of discontinuous networks, which improve microwave incidence dispersion, polarize more interfacial charges, and allow electromagnetic wave absorption. In theory, this research could lead to a simple and efficient process for producing spherical flower-shaped CIP@MnO2 composites with high absorption, a wide band, and oxidation resistance for a wide range of applications.

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Section: Resultsmentioning

confidence: 99%

Enhanced Electromagnetic Wave Absorption Properties of Ultrathin MnO2 Nanosheet-Decorated Spherical Flower-Shaped Carbonyl Iron Powder

Wang

Yang

et al. 2021

Molecules

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“…The elimination of EM interference between EM wave radiating systems and electronic equipment plays a significant impact on practical applications [11][12][13]. Therefore, the EM wave absorbing materials gain much attention, which can effectively absorb EM wave and convert into thermal or interference-dispersed microwave (MW) [14][15][16]. Though, it is still a great challenge to develop a novel EM wave absorbers which simultaneously satisfy all the necessities such as broad and strong absorption bandwidth in a wide frequency range, small thickness and light-weight [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic wave absorption performance of Ni doped Cu-ferrite nanocrystals

Saleem

Zhang

Gong

et al. 2020

Mater. Res. Express

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Ni x Cu 1−x Fe 2 O 4 nanocrystals were prepared by co-precipitation technique to study the electromagnetic (EM) wave absorption properties. The XRD and SEM results confirm the formation of single-phase cubic spinel structure and reveal that the crystallite size decreases with the addition of Ni content. The vibrating sample magnetometer results showed that the as-prepared material was soft magnetic and have potential applications in magnetic storage technology and field sensors. The dielectric parameters and EM wave absorption characteristics of Ni x Cu 1−x Fe 2 O 4 nanocrystals were studied in the frequency range of 1-18GHz using a vector network analyzer. The permittivity, impedance matching, and EM wave absorption of the materials are significantly improved with the increase in Ni content. The lowest value of reflection loss (R L ) is observed −22.8 dB at 16.09 GHz (R L −10dB, absorption >90%), showing an optimal EM wave absorption performance, which might generate from the synergistic effect between relative permittivity and permeability.

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“…(a) Real part and (b) imaginary part of frequency-dependent dielectric function of b-Si 3 N 4 at varying temperatures. Notethat only the real part is given in Ref [34]…”

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confidence: 99%

Deep learning molecular dynamics simulation on microwave high-temperature dielectric function of silicon nitride

Liu¹,

Tan²,

Duan³

et al. 2022

Acta Phys. Sin.

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Silicon nitride (β-Si3N4) is the most promising thermal wave-transparent material. The accurate measurement of its high-temperature dielectric function is essential to solve the "black barrier" problem of hypersonic vehicles and accelerate the design of silicon nitride-based thermal wave-transparent materials. Direct experimental measurements at high temperature are challenging and the accuracy of classical molecular dynamics (CMD) simulations suffers from the choice of empirical potential. In this work, we build a β-Si3N4 model at nanoscale, train the deep learning potential (DLP) using first-principles data, and apply deep potential molecular dynamics (DPMD) to simulate polarization relaxation process. The predicted energy and force by DLP are excellently consistent with first-principles calculations, which proves the high accuracy of DLP. The RMSEs for β-Si3N4are quite low (0.00550 meV/atom for energy and 7.800 meV/Å for force). According to the Cole-Cole formula, the microwave dielectric function in the temperature range 300-1000 K was calculated by using the deep learning molecular dynamics method. Compared with the empirical potential, the computational results of the DLP are consistent with the experimental results in order of magnitude. It is also found that the DPMD performs well in terms of computational speed. In addition, a mathematical model of the temperature dependence of the relaxation time was established to reveal the pattern of relaxation time varies with temperature. This work calculates the high-temperature microwave dielectric function of silicon nitride by implementing large-scale and high-precision molecular dynamics simulations. It provides fundamental data to promote the application of silicon nitride in high-temperature thermal transmission.

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Dielectric and microwave absorption properties of fluoride-doped MWCNT/Si3N4 composite

Cited by 16 publications

References 35 publications

Enhanced Electromagnetic Wave Absorption Properties of Ultrathin MnO2 Nanosheet-Decorated Spherical Flower-Shaped Carbonyl Iron Powder

Enhanced Electromagnetic Wave Absorption Properties of Ultrathin MnO2 Nanosheet-Decorated Spherical Flower-Shaped Carbonyl Iron Powder

Electromagnetic wave absorption performance of Ni doped Cu-ferrite nanocrystals

Deep learning molecular dynamics simulation on microwave high-temperature dielectric function of silicon nitride

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