Study on the Properties of Microwave Absorption of Zinc Oxide Whisker

2006 ◽  
Vol 510-511 ◽  
pp. 982-985 ◽  
Author(s):  
Long Sheng Chu ◽  
Zuo Wan Zhou ◽  
Yong Zhao
Keyword(s):  
Zinc Oxide ◽  
Microwave Absorption ◽  
Cross Section ◽  
Absorption Efficiency ◽  
Microwave Energy ◽  
Diameter Ratio ◽  
Tunnel Effect ◽  
Conductive Network ◽  
Pure Zinc ◽  
Oxide Whisker

In this paper, the microwave absorption behaviors of zinc oxide whisker were studied. The morphological structure of zinc oxide whisker was observed through scanning electron microscope. The effect of the structure of zinc oxide whisker on the microwave absorption, such as length-diameter ratio, cross-section appearance, and doping was analyzed. The result shows that the more irregular the cross section of the needle of zinc oxide whisker is, the more prominent the microwave absorption appears. The less the length-diameter ratio of the needle of zinc oxide whisker is, the more obvious the microwave absorption of zinc oxide whisker becomes. The zinc oxide whisker, which had inlet ion, such as Al3+, Fe3+ , etc., in its crystal lattice has a better microwave absorption efficiency than the pure zinc oxide whisker. The further analysis found that electric conductive network can be formed easily because of the zinc oxide whisker, and the coating had the porous structure. When microwave reaches the coating of zinc oxide whisker, the polarization of zinc oxide whisker was resulted and the electromagnetic energy lost. Firstly, electric current was transmitted through the electric conductive network and the energy transformed to heat. Secondly, tips’ phenomenon has been observed, which lead to the energy lost. Finally, the microwave energy was lost because of the tunnel effect, which will bring about leakage current. Based on the three reasons above, microwave energy was absorbed by the coating containing the zinc oxide whisker.

scholarly journals Study on electrical conductivity and microwave absorption properties of CNTs/CB/PMMA nanocomposites foam

2021 ◽  
Author(s):  
Huajie Mao ◽  
Xuliang Zhong ◽  
Xiaorui Liu ◽  
Wei Guo ◽  
Danfeng Zhou ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Low Frequency ◽  
Absorption Efficiency ◽  
Conductive Network ◽  
Microwave Absorption Properties ◽  
Composite Foam ◽  
The Monte Carlo Method ◽  
One Step ◽  
Absorption Performance ◽  
Microwave Absorption Performance

Abstract In order to study the conductive and microwave absorption performance of multi-dimensional multiphase filler conductive foam composites, carbon nanotubes (CNTs)/carbon black (CB)/polymethyl methacrylate (PMMA) nanocomposites with different porosity were fabricated via supercritical carbon dioxide (ScCO2) one-step physical constraint foaming technology.The effects of filler component and porosity on the conductivity and absorbing properties of CNTs/PMMA/CB composite foam were studied. The Monte-Carlo method was used to study the percolation of composites and the effect of introduced microcells on the conductive network of multi-dimensional fillers.The results revealed that the volume conductivity of CNTs(3 vol%)/PMMA composites increased from 0.88 S/m to 3.31 S/m after the addition of 1 vol% CB. CNTs and CB had obvious synergistic effect on improving the conductivity of the composites, and the microwave absorption efficiency rose from 12.6 dB to 17.2 dB. With the increase of porosity, the electromagnetic wave absorption peak of CNTs/CB/PMMA composite foam moved to low frequency, while the conductivity showed a first rise and then a decline. The simulated percolation probability obtained by representative volume element (RVE) with different porosity also showed a similar trend, which turned out that with the increase of porosity, the effect of microcells on the convertion of conductive network construction from promoting to inhibiting.

Low Temperature Deposition of Zinc Oxide Films

2003 ◽  
Vol 763 ◽  
Author(s):  
H. W. Lee ◽  
Y. G. Wang ◽  
S. P. Lau ◽  
B. K. Tay
Keyword(s):  
Zinc Oxide ◽  
Carrier Concentration ◽  
Vacuum Arc ◽  
Zno Films ◽  
Al Alloy ◽  
Pure Zinc ◽  
Zinc Oxide Films ◽  
Alloy Target ◽  
Temperature Deposition ◽  
Filtered Cathodic Vacuum Arc

AbstractA detailed study of zinc oxide (ZnO) films prepared by filtered cathodic vacuum arc (FCVA) technique was carried out. To deposit the films, a pure zinc target was used and O2 was fed into the chamber. The electrical properties of both undoped and Al-doped ZnO films were studied. For preparing the Al-doped films, a Zn-Al alloy target with 5 wt % Al was used. The resistivity, Hall mobility and carrier concentration of the samples were measured. The lowest resistivity that can be achieved with undoped ZnO films was 3.4×10-3 Ωcm, and that for Al-doped films was 8×10-4 Ωcm. The carrier concentration was found to increase with Al doping.

Carbon Nanotubes based composites for electromagnetic absorption- A review

2021 ◽  
Vol 01 ◽  
Author(s):  
Navdeep Singh ◽  
Gagan Deep Aul
Keyword(s):  
Carbon Nanotubes ◽  
Microwave Absorption ◽  
Cross Section ◽  
Radar Cross Section ◽  
Complex Permeability ◽  
Tangent Loss ◽  
Microwave Frequencies ◽  
Radar Absorbing Material ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

: Radar is a delicate detection device and since its evolution different techniques for reducing electromagnetic reflections have been discovered. This paper provide concise review on fundamentals of absorption which reduces radar cross section from stealth target with which radar cross section has effects to survivability and mission capability. The reduction of radar cross section depend on dielectric and magnetic properties of material. The first section reviews the Radar Absorbing Material (RAM) in order to provide a background on fundamentals, various stealth techniques for absorption and its properties at microwave frequencies. The second section reviews the Multi-Walled Carbon Nanotubes and its different composites by encapsulation of other metals, polymers or epoxies into it and its microwave absorption properties were studies at microwave frequencies. Multi-Walled Carbon Nanotubes based composites for microwave absorption are reviewed on the basis of various factors; material composition, reflection loss performance, thickness, complex permittivity, complex permeability, dielectric tangent loss, magnetic tangent loss, bandwidth, and frequency band.

Sign in / Sign up

Export Citation Format

Share Document