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Dielectric Properties of Yttria Ceramics at High Temperature

Journal of Electronic science and technology of China 2007年第4期5卷 320-324页

作者： Jian Chen Zheng-Ping Gao Jin-Ming Wang Da-Hai Zhang State Key Lab. of Electronic Thin Films ＆ Integrated Devices University of Electronic Science and Technology of China Chengdu 610054 China National Key Laboratory of Advanced Functional Composite Material. Mail box： 9200 Beijing 100076 China

Based on Clausius-Mosotti equation and Debye relaxation theory, the dielectric model of yttria ceramics was developed according to the dielectric loss mechanism. The dielectric properties of yttria ceramics were predicted at high temperature. The temperature dependence and frequency dependence of dielectric constant and dielectric loss were discussed, respectively. As the result, the data calculated by theoretical dielectric model are in agreement with experimental data.

关键词： Dielectric properties Debye relaxation theory high temperature yttria ceramics.

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Comparison of carbon-based nano materials as conductive fillers for single layer microwave absorber

Comparison of carbon-based nano materials as conductive fill...

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作者： Kim, Jin-Bong Lee, Sang-Kwan Kim, Chun-Gon Korea Institute of Machinery and Materials Composite Materials Laboratory 66 Sangnam-dong Changwon 641- 010 Korea Republic of Korea Advanced Institute of Science and Technology Aerospace Engineering Department 373-1 Guseong-dong Yuseong-gu Daejeon 305- 701 Korea Republic of

In this paper, we have studied the permittivities of E-glass fabric/epoxy composite laminates containing three different types of carbon-based nano conductive fillers such as carbon black (CB), carbon nano fiber (CNF) and multi-wall carbon nano tube (MWNT). The measurements were performed for permittivities at the frequency band of 0.5 GHz ∼ 18.0 GHz using a vector network analyzer with a 7 mm coaxial air line. The experimental results show that the complex permittivities of the composites depend strongly on the natures and concentrations of the conductive fillers. The real and imaginary parts of the complex permittivities of the composites were proportional to the filler concentrations. But, depending on the types of fillers and frequency band, the increasing rates of the real and imaginary parts with respect to the filler concentrations were all different. At the frequency of 10 GHz, the rates in the CNF filled composite and the MWNT filled composite were much larger then those of the CB filled composite. Between the CNF filled composite and MWNT filled composite, however, the former showed a little higher increasing rates than the other. These different rates can have great effect on the thickness in designing the single layer microwave absorbers. The effect of the different rates was examined by using Cole-Cole plots;the plot is composed of a single layer absorber solution line and permittivity lines of these three types of composites.

关键词： Nanotubes

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High Current Density Scandia Doped Pressed Cathode and Shaped Beam Generation

High Current Density Scandia Doped Pressed Cathode and Shape...

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International Conference on Vacuum Electronics

作者： Jinshu Wang Yiman Wang Wei Liu Lili Li Hong Lu Yanchun Wang Hongyi Li Jjiancan Yang The Key Laboratory of Advanced Functional Materials School of Materials Science and Engineering Beijing University of Technology Ministry of Education Beijing China

This paper described the development of high current density Scandia doped pressed cathode and generation of shaped electron beam.

关键词： Current density Cathodes Electron beams Current measurement Materials science and technology Powders Electron devices Current distribution Area measurement Density measurement

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Transmission Properties of Radar Wave through Reentry Plasma Sheath

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Journal of Electronic science and technology of China 2007年第1期5卷 29-32,37页

作者：高正平马兆国刘静李仲平张大海 Engineering Research Center of Electromagnetic Wave Absorbing Materials Ministry of EducationUniversity of Electronic Science and Technology of China State Key Lab. of Electronic Thin Films & Integrated Devices University of Electronic Science and Technology of China Chengdu 610054 China National Key Laboratory of Advanced Functional Composite Materials 9200 Box

In this paper, by taking into account the coupling of the ionization of ablation gas and atmosphere, an electrons density distribution model is built. Using this model, the transmission properties of different polarization radar wave through sheath are evaluated on the basis of the transmission matrix theory. Then, we discuss the effects of the electrons density, the added magnetic field, and the radar wave frequency on the transmission properties. As a result of this investigation, greater transmission power could be gained in order to efficiently shorten communication blackout, by reducing the electrons density or choosing proper added magnetic field and the frequency of the radar wave according to the different polarization form of the radar wave.

关键词： communication blackout plasma sheath radar wave reentry transmigsion properties

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Anomalous magnetic behavior of Mn−Mn dimers in the dilute magnetic semiconductor (Ga,Mn)N

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Physical Review B 2007年第24期76卷 245210-245210页

作者： Qinghua Liu Zhihu Sun Wensheng Yan Wenjie Zhong Zhiyun Pan Luyuan Hao Shiqiang Wei National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei 230029 People’s Republic of China Laboratory of Advanced Functional Materials and Devices Department of Materials Science and Engineering University of Science and Technology of China Hefei 230026 People’s Republic of China

First-principles calculations were performed to study the electronic structure and magnetic interactions of MnGa−MnI dimer formed by the neighboring substitutional MnGa and interstitial MnI ions in the zinc-blende structured (Ga,Mn)N dilute magnetic semiconductor. On the basis of the formation energy calculations, we show that the clustering of MnGa and MnI in (Ga,Mn)N is energetically favored. The MnGa and MnI ions in the MnGa−MnI dimer are antiferromagnetically coupled, but this cannot strikingly reduce the magnetic moments induced by MnGa due to the strong localization character of MnI gap states. It is found that MnGa−MnI dimer in zinc-blende structured (Ga,Mn)N possesses unique electronic and magnetic properties, as compared with their counterparts in wurtzite structured (Ga,Mn)N or zinc-blende structured (Ga,Mn)As. The present study can provide some insight into understanding the rather scattered magnetic moment per Mn ion observed experimentally.

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Synergistic effect and mechanism of ground carbonatite and slag in alkali-activated carbonatite-slag cementitious material

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of technology 2007年第12期29卷 15-19+67页

作者： Zhao, San-Yin Yu, Qi-Jun Qiao, Fei Yin, Su-Hong Zhao, Xu-Guang Wen, Zi-Yun School of Chemistry and Environment Engineering Shaoguan University Shaoguan 512005 China Key Laboratory of Specially Functional Materials and Advanced Manufacturing Technology South China University of Technology Guangzhou 510640 China School of Materials Science and Engineering South China University of Technology Guangzhou 510640 China

Mortar specimens of alkali-activated carbonatite-slag cementitious materials (AACSCM) were prepared, in which finely ground zirconite, being inactive under the reaction condition of this experiment, was also used to replace ground carbonatite or ground granulated blast-furnace slag (GGBFS) by iso-volume, so as to investigate the contribution of each material to the strength of AACSCM. According to the test results of mortar strength and the composition of pore solution of pastes, the effect of GGBFS on the strength improvement of alkali-activated cementitious material (AACCM) was discussed. The results indicated that, at the late stage of reaction, there did exist a synergistic effect between GGBFS and ground carbonatite under the activation of alkaline. The mechanism lied in: During the late period of reaction, the amount of Ca2+, Mg2+ provided by GGBFS to the reaction system was much decreased, while much more Al3+ were retained. The shortage of Ca2+, Mg2+ in the system was compensated by the dissolution of ground carbonated, leading the reaction be continued, and Al3+ were consumed simultaneously in the reaction, which promoted the dissolution of GGBFS in return. With the repeat of this process the reaction degree of AACSCM was much improved.

关键词： Alkali-activated carbonatites Ground granulated blast-furnace slag Pore solution Strength Synergistic effect

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Transmission Properties of Radar Wave through Reentry Plasma Sheath

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Journal of Electronic science and technology 2007年第1期000卷 29-32,37页

作者： GAO Zheng-ping MA Zhao-guo LIU Jing LI Zhong-ping ZHANG Da-hai Engineering Research Center of Electromagnetic Wave Absorbing Materials Ministry of Education University of Electronic Science and Technology of China State Key Lab. of Electronic Thin Films & Integrated Devices University of Electronic Science and Technology of China Chengdu 610054 China Engineering Research Center of Electromagnetic Wave Absorbing Materials Ministry of Education National Key Laboratory of Advanced Functional Composite Materials 9200 Box Chengdu 610054 China Beijing 100076 China

In this paper,by taking into account the coupling of the ionization of ablation gas and atmosphere,an electrons density distribution model is built. Using this model,the transmission properties of different polarization radar wave through sheath are evaluated on the basis of the transmission matrix theory. Then,we discuss the effects of the electrons density,the added magnetic field,and the radar wave frequency on the transmission properties. As a result of this investigation,greater transmission power could be gained in order to efficiently shorten communication blackout,by reducing the electrons density or choosing proper added magnetic field and the frequency of the radar wave according to the different polarization form of the radar wave.

关键词： communicationblackout plasmasheath radarwave reentry transmissionproperties

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A Comparative Study of Failure Mechanisms of Sn-Ag-Cu Assemblies under Temperature Cycling and Board Level Drop Test

A Comparative Study of Failure Mechanisms of Sn-Ag-Cu Assemb...

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International Symposium on High Density Packaging and Microsystem Integration (HDP)

作者： Yanghua Xia Xiaoming Xie Center for Electronic Packaging Materials Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology Daejeon South Korea State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology Chinese Academy and Sciences Shanghai China

The reliability performance and failure mechanisms of lead-free electronic assemblies under temperature cycling and board level drop test was investigated. TSOP (thin small outline package) devices with FeNi leads were reflow soldered on FR4 PCB (printed circuit board) with Sn3.0Ag0.5Cu (wt%) solder paste. The effects of different PCB finishes (organic solderability preservative (OSP) and electroless nickel immersion gold (ENIG)) on the reliability performance were studied. The results show that the assemblies with OSP finishes outperform its ENIG counterparts under temperature cycling, however, the ENIG assemblies reveal better reliability performance than those with OSP finishes under drop test. The failure mechanism is different under these two test conditions: the solder joints fracture into the intermetallic compounds (IMCs) layer under drop test, and cracks initiate in the bulk solder near to the interface under temperature cycling. The surface finishes also have an effect on the failure mode under temperature cycling. The propagation of crack in the ENIG case is along the device/solder interface, while in the case of OSP, the crack extends parallel to the solder/PCB interface.

关键词： Failure analysis Assembly Temperature Circuit testing Environmentally friendly manufacturing techniques Lead Electronic equipment testing Electronics packaging Printed circuits Nickel

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Research on material of retention on leachability Cr (VI) in harden fly ash cement

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of technology 2007年第1期29卷 22-25页

作者： Wei, Jiang-Xiong Yu, Qi-Jun Zeng, Xiao-Xing Bai, Rui-Ying Key Laboratory of Specially Functional Materials and Advanced Manufacturing Technology South China University of Technology Guangzhou 510640 China College of Materials Science and Engineering South China University of Technology Guangzhou 510640 China

Material of Retention on Leachability Cr (VI) was prepared with ground granulated blast-furnace slag (GGBFS) and ground electric steel furnace slag (GESFS). Then, the following two aspects were carried out: (1) investigation into the reducing effect of GGBFS and GESFS on the leachability Cr (VI) in harden fly ash cement;(2) relation between the amount of Cr (VI) leached from hardened fly ash and Cr (VI) concentration in the pore solution of the hardened fly ash. The results indicated that the both slags possessed excellent reducibility on leachability Cr (VI). With the addition of the slags Cr (VI)-containing in hardened fly ashes, the concentration of Cr (VI) in the solution and the leaching of Cr (VI) from hardened fly ashes was reduced, and the effect was kept stable during the investigated term.

关键词： Cr (VI) Hardened fly ashes Leachability Slag

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Coupling theory and simulation of a high speed optical receiver module

Pan Tao Ti Hsueh Pao/Chinese Journal of Semiconductors

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Pan Tao Ti Hsueh Pao/Chinese Journal of Semiconductors 2007年第2期28卷 275-279页

作者： Chen, Shiyu Wang, Gang State Key Laboratory of Optoelectronic Materials and Technologies Sun Yat-Sen University Guangzhou 510275 China Institute of Optoelectronic and Functional Composite Materials Sun Yat-Sen University Guangzhou 510275 China School of Science and Technology Sun Yat-Sen University Guangzhou 510275 China

We propose an optical model of a cylindrical lens for fiber coupling based on the method of coupling an angle-ended fiber to the front facet of a chip that is used in high-speed optical receivers. We also study the effect of the packing process on coupling efficiency with the optical model and software simulation. The simulation results show that the optical coupling efficiency is determined by fiber position, the lens design of the photodiode chips, and the shape of the light source.

关键词： Optical receivers

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