The effects of temperature and frequency on the dielectric properties, electromagnetic interference shielding and microwave-absorption of short carbon fiber/silica composites

Temperature dependent microwave attenuation behavior for carbon-nanotube/silica composites

Electromagnetic Response and Energy Conversion for Functions and Devices in Low‐Dimensional Materials

To tackle the aggravating electromagnetic wave (EMW) pollution issues, high-efficiency EMW absorption materials are urgently explored. Metal–organic framework (MOF) derivatives have been intensively investigated for EMW absorption due to the distinctive components and structures, which is expected to satisfy diverse application requirements. The extensive developments on MOF derivatives demonstrate its significantly important role in this research area. Particularly, MOF derivatives deliver huge performance superiorities in light weight, broad bandwidth, and robust loss capacity, which are attributed to the outstanding impedance matching, multiple attenuation mechanisms, and destructive interference effect. Herein, we summarized the relevant theories and evaluation methods, and categorized the state-of-the-art research progresses on MOF derivatives in EMW absorption field. In spite of lots of challenges to face, MOF derivatives have illuminated infinite potentials for further development as EMW absorption materials.
Highlights:
1 In terms of components and structures, this review summarizes progresses and highlights strategies of MOF derivatives for efficient electromagnetic wave absorption.2 We also systematically delineate relevant theories and points out the prospects and current challenges.

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Carbon-Based MOF Derivatives: Emerging Efficient Electromagnetic Wave Absorption Agents

Silicon carbide powders: Temperature-dependent dielectric properties and enhanced microwave absorption at gigahertz range

A simulation of the quasi-standing wave and generalized half-wave loss of electromagnetic wave in non-ideal media

Having adopted several sets of new technology and techniques, such as cube-corner prism of higher refractive index, orthogonal holographic grating, non-linear compensation, and fringe fractionization, etc., we have developed a new type of laser angle sensor that can be used to measure two-dimensional angle of moving target. The sensor has high sensitivity, high precision and longer measuring range compared with the original sensor, and its measuring range will achieve ±35°, while its minimum resolution angle is 0.004°. The experimental results show that the measuring error is not greater than ±0.01°. In this paper, several design parameters and measuring results for 2D laser angle sensor are given.

Theoretical analysis of 2D laser angle sensor and several design parameters

Dielectric properties of SiC/Ni nanocomposites prepared by a simple and facile electroless plating approach at X band are investigated. Compared to the original SiC nanoparticles (SiCP), the real part of the permittivity, ', and the dielectric loss tangent tan δe of SiC/Ni nanocomposites are clearly enhanced by about 31% and 33%, respectively. The effective equations for complex permittivity of SiC/Ni nanocomposites are proposed. We also calculate ' and tan δe of SiC/Ni nanocomposites and the calculated results are well consistent with the measured data.

http://iopscience.iop.org/article/10.1088/0256-307X/25/5/104/pdf

Mechanism of Enhanced Dielectric Properties of SiC/Ni Nanocomposites

We present general equations for metal-substrate single-layer microwave absorbing materials. The optimum electromagnetic parameters and matching thicknesses for electric-loss, magnetic-loss, and electromagnetic-loss materials are given, and possible solutions for the equations and the corresponding theoretic curves are discussed as well. The results may be helpful for designing high-performance microwave absorbing materials.

https://iopscience.iop.org/article/10.1088/0256-307X/27/2/027702/pdf

Microwave Absorbing Materials: Solutions for Real Functions under Ideal Conditions of Microwave Absorption

The geometrical and electronic structures of nitrogen-doped β-SiC are investigated by employing the first principles of plane wave ultra-soft pseudo-potential technology based on density functional theory. The structures of SiC1−xNx (x = 0, 1/32, 1/16, 1/8, 1/4) with different doping concentrations are optimized. The results reveal that the band gap of β-SiC transforms from an indirect band gap to a direct band gap with band gap shrinkage after carbon atoms are replaced by nitrogen atoms. The Fermi level shifts from valence band top to conduction band by doping nitrogen in pure β-SiC, and the doped β-SiC becomes metallic. The degree of Fermi levels entering into the conduction band increases with the increment of doping concentration; however, the band gap becomes narrower. This is attributed to defects with negative electricity occurring in surrounding silicon atoms. With the increase of doping concentration, more residual electrons, more easily captured by the 3p orbit in the silicon atom, will be provided by nitrogen atoms to form more defects with negative electricity.

http://iopscience.iop.org/article/10.1088/0256-307X/26/6/067101/pdf

Fang Xiao-Yong

Papers

A simulation of the quasi-standing wave and generalized half-wave loss of electromagnetic wave in non-ideal media

Theoretical analysis of 2D laser angle sensor and several design parameters

Mechanism of Enhanced Dielectric Properties of SiC/Ni Nanocomposites

Microwave Absorbing Materials: Solutions for Real Functions under Ideal Conditions of Microwave Absorption

Modification of Band Gap of β-SiC by N-Doping