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International Conference on Thermoelectrics (ICT)

作者： Xiaobo Hu Hong Liu Jiyang Wang Huaidong Jiang Shanrong Zhao Dongming Zhang Mingyuan Gu Minhua Jiang State Key Laboratory of Crystal Materials Shandong University Jinan China State Key Laboratory of Advanced Technology of Materials Synthesis and Processing Wuhan University of Technology Wuhan China State Key Laboratory of Metal Matrix Composite Shanghai Jiaotong University Shanghai China

Filled skutterudite NaFe/sub 4/P/sub 12/ single crystal nanowires were synthesized by using a hydrothermal-reduction-alloying method. X-ray diffraction (XRD), Electron diffraction (ED), Raman scattering, as well as elemental analysis were used to characterize the product. High-resolution transmission electron microscope (HRTEM) was used to investigate the microstructure of the nanowire. A growth mechanism of NaFe/sub 4/P/sub 12/ nanowire was proposed.

关键词： Nanowires Iron Crystallization Wire Magnetic fields Image resolution Magnetic cores Atomic layer deposition X-ray scattering Cerium

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Preparation and thermoelectric properties of polyaniline/NaFe/sub 4/P/sub 12/ composite

Preparation and thermoelectric properties of polyaniline/NaF...

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International Conference on Thermoelectrics (ICT)

作者： Hong Liu Jiyang Wang Xiaobo Hui Huaidong Jiang Shanrong Zhao Qiang Li R.I. Boughton Minhua Jiang State Key Laboratory of Advanced Technology of Materials Synthesis and Processing Wuhan Technology University Wuhan P. R. China State Key Laboratory of Crystal Materials Shandong University Jinan P. R. China Shandong University Jinan Shandong CN Center for Materials Science Green State University Bowling Green U.S.A

Polyaniline/NaFe/sub 4/P/sub 12/ whiskers and polyaniline/NaFe/sub 4/P/sub 12/ nanowire composites were prepared by an in situ compounding method. X-ray diffraction (XRD), infrared spectra, thermal gravity analysis (TGA) transmission electron microscope (TEM) and electron diffraction (ED) were used to characterize polyaniline and the composites. Polyaniline can grow on the surface of NaFe/sub 4/P/sub 12/ whisker and forms a novel "brush" structure. The mechanism of the forming of the "brush" structure is suggested. The conductivity and Seebeck coefficient of polyaniline and the composites were measured.

关键词： Thermoelectricity Thermal conductivity Conducting materials Crystalline materials Polymers Inorganic materials materials science and technology Laboratories Composite materials X-ray diffraction

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Multi-filling approach for the improvement of thermoelectric properties of skutterudites

Multi-filling approach for the improvement of thermoelectric...

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International Conference on Thermoelectrics (ICT)

作者： L.D. Chen X.F. Tang T. Kawahara J.S. Dyck W. Chen C. Uher T. Goto T. Hirai State Key Laboratory of High Performance Ceramics and Superfine Structure Shanghai Institute of Ceramics Chinese Academy and Sciences Shanghai China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan China Institute of Materials Research University of Tohoku Sendai Japan Department of Physics University of Michigan Ann Arbor MI USA

Several skutterudite antimonides filled with atoms of different kinds, (Ba, M)/sub y/Co/sub 4/Sb/sub 12/ (M=Ce, La, Sr), have been synthesized by the combination of solid state reaction and melting methods. Thermal conductivity of (Ba,Sr)/sub y/Co/sub 4/Sb/sub 12/ samples shows a behavior similar to that of Ba/sub y/Co/sub 4/Sb/sub 12/. Adding a small amount of Ce or La to the Ba/sub y/Co/sub 4/Sb/sub 12/ system is effective in further reducing the lattice thermal conductivity. The difference in the ionic radii of the two co-filler atoms is the most sensitive factor for scattering of phonons. The multi-filled (Ba, M)/sub y/Co/sub 4/Sb/sub 12/ (M=Sr, Ce, La) show lower Seebeck coefficients as compared to the single-filled Ba/sub y/Co/sub 4/Sb/sub 12/ having the same total filling fraction. It is expected that higher thermoelectric performance could be realized by further optimization of the composition of filler species.

关键词： Thermoelectricity Thermal conductivity Lattices Powders Conducting materials Phonons Filling Atmospheric measurements Laboratories Ceramics

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Solid state reaction synthesis of filled skutterudite compounds (Ce or Y)_y,Fe_xCo_(4-x)Sb_(12) and the effect of filling atoms Ce or Y on lattice thermal conductivity

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Science China Chemistry 2000年第3期43卷 306-312页

作者：唐新峰陈立东後藤孝平井敏雄袁润章 Institute for Materials Research Tohoku University Sendai 980-8577 Japan State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

The synthesis of filled skutterudite compounds (Ce or Y)_y(Fe)_x(Co)_(4x)(Sb)_(12), through a solidstate reaction using chloride of Ce or Y,high purity powder of Co, Fe, and Sb as starting materials,was investigated. (Ce or Y)_y(Fe)_x(Co)_(4x)(Sb)_(12) (x=0--1.0, y=0--0.15) compounds were obtained at850--1 123 K. The results of Rietveld analysis demonstrate that (Ce or Y)_y(Fe)_x(Co)_(4x)(Sb)_12synthesized by a solid state reaction possesses a filled skutterudite structure. The filling fraction ofCe or Y obtained by Rietveld analysis agrees well with the composition obtained by chemicalanalysis. The lattice constant of (Ce)_y(Fe)_x(Co)_(4x)(Sb)_(12) increases with increasing substitution of Fe at Cosites, and with an increasing Ce filling fraction in the Sb-dodecahedron voids. The lattice thermalconductivity of (Ce or Y)_y(Fe)_x(Co)_(4x)(Sb)_(12) decreases significantly with an increasing Ce or Y fillingfraction in the voids and with substitution of Fe at Co sites.

关键词： filled skutterudite compound solid state reaction lattice thermal conductivity

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THE EVOLUTION OF THE DENSITY OPERATORFOR DRIVEN SYSTEM

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Acta Mathematica Scientia 1999年第1期19卷 97-106页

作者：毕桥 The State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

For studying the evolution of the density operator of the time-dependent dynamical system author presents here a general reformulation of subdynamics of driven system to obtain the efficient dynamical equation. The explicit formulas to calculate the creation operator and the destruction operator are given. A new intertwining relation is discussed, The method presented here can be useful to get the evolution formalism of the density operator for any system driven by an external field.

关键词： subdynamics density operator driven system time-dependent Liouvillian

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Manufacture of the Ultrafine Grain WC/Co Cemented Carbides by Combined Sintering processing

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International Journal of Minerals,Metallurgy and materials 1999年第3期13卷 208-213页

作者： Binghai Liu Yue Zhang Shixi Ouyang Qikai Li(Institute of Technical Physics and Chemistry, East China University of Science and technology , Shanghai 200237, China)(material Science and Engineering School. University of Science and technology Beijing, Beijing 100083, China)(state key laboratory for synthesis and processing of advanced materials. Wuhan University of Science and technology, Wuhan 430070, China,) Institute of Technical Physics and Chemistry East China University of Science and Technology Shanghai 200237 China Material Science and Engineering School University of Science and Technology Beijing Beijing 100083 China State Key Laboratory for Synthesis and Processing of Advanced Materials Wuhan University of Science and Technology Wuhan 430070 China

A new kind of sintering process, combined sintering process. i.e. vacuum sintering plus hot isolate pressure sintering (HIP), was introduced for producing ultrafine WC-10% Co (mass fraction. so as the follows) cemented carbides. The effects of some processing parameters on the microstructure and mechanical properties of the obtained cemented carbides were studied. The results show that the rapid shrinkage and the pronounced densification of tile cemented carbides took place during the vacuum sintering stage, which is intinaately correlated with the local liquid sintering occurred during this earl} sintering stage for the high surface activity of ultrafine WC-Co powder. The way of high pressure imposing. isothermal treatment cycle during *** sintering and HIP sintering stage directly influence the densitication of compacts and the mechanical properties of the produced WC-10%Co cemented carbides.

关键词： ultrafine WC-Co cemented carbides vacuum sintering HIP sintering

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The Decoherence-Free in Multi-Coupled Quantum Computing System

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Wuhan University Journal of Natural Sciences 1999年第4期4卷 428-434页

作者： LIU Gui ping, BI Qiao,ZHANG Qing jie state key laboratory of advanced technology for materials synthesis and processing, Wuhan University of technology, Wuhan 430070, China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan China

A subdynamics theory framework for describing multi coupled quantum computing systems is presented first. A general kinetic equation for the reduced system is given then, enabling a sufficient condition to be formulated for constructing a pure coherent quantum computing system. This reveals that using multi coupled systems to perform quantum computing in Rigged Liouville Space opens the door to controlling or eliminating the intrinsic de coherence of quantum computing systems.

关键词： quantum computing system subdynamics rigged liouvile space density operator

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Effect of Nb2O5 on the space-charge conduction of Y2O3-stabilized ZrO2

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SOLID state IONICS 1997年第1-2期99卷 137-142页

作者： Guo, X State Key Laboratory for Synthesis and Processing of Advanced Materials Wuhan University of Technology Wuhan Hubei 430070 People's Republic of China

Up to 1.5 mol% Nb2O5 was added to 9 mol% Y2O3-stabilized ZrO2. According to an XRD analysis, the addition of Nb2O5 did not change the cubic structure of YSZ. As a result of the repulsion effect of the grain-boundary interface and the preferential segregation of Y2O3, the Nb2O5 segregation at the grain boundaries was not detected by EPMA. The resistances were measured by the complex impedance approach in air, Nb2O5 was found to increase the resistance per unit surface area of the grain boundaries. This result suggested that the most likely mechanism of the dissolution of Nb2O5 in YSZ should be Nb2O5 --> 2Nb(Zr) + 2e' + 4O(o)(x) + 1/2 O-2. Despite the Nb2O5 addition, the Arrhenius equation can still be applied to the resistances.

关键词： space-charge conduction ZrO2 Nb2O5 Y2O3

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Effect of DC voltage on the microstructure and electrical properties of stabilized-zirconia

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SOLID state IONICS 1997年第1-2期99卷 143-151页

作者： Guo, X State Key Laboratory for Synthesis and Processing of Advanced Materials Wuhan University of Technology Wuhan Hubei 430070 People's Republic of China

Y2O3 and Al2O3 codoped ZrO2 specimens were treated by a DC voltage of 8 V at 600 degrees C in air. During the treatment, electrons were injected from the cathode into the ZrO2, thus colour centers were formed. After the treatment, no structure and valence state changes were detected by XRD and XPS, and no obvious microstructure and composition change were observed by TEM and EPMA. However, the bulk resistance was found to greatly increase, which is considered to be the result of the formation of colour centers. The grain-boundary resistance was found to greatly decrease, and this phenomenon may be due to a reduced space-charge potential and the reduced size and amount of the amorphous grain-boundary phase.

关键词： stabilized-zirconia microstructure property DC voltage

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Space-charge conduction in yttria and alumina codoped-zirconia

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SOLID state IONICS 1997年第3-4期96卷 247-254页

作者： Guo, X State Key Laboratory for Synthesis and Processing of Advanced Materials Wuhan University of Technology Wuhan Hubei Province 430070 People's Republic of China

The grain-boundary resistances of 9 mol% Y2O3 and 1.5 mol% Al2O3 codoped-ZrO2 after sinterings of 1520-1600 degrees C were measured by the complex impedance approach. And the microstructure of the specimen was analyzed by means of SEM, EPMA and TEM. According to a space-charge theory analysis, the space-charge potential of the Y2O3 and Al2O3-codoped ZrO2 is negative, which is the result of an Al-Zr' segregation and V-O(..) depletion in the space-charge layers. As Al-Zr' has a stronger tendency to form associates with V-O(..) than Y-Zr', the Al-Zr' segregation further reduces the concentration of mobile V-O(..) in the space-charge layers, thus increasing the grain-boundary resistance contributed from the space-charge layers. A higher V-O(..) concentration in the space-charge layers of the Al2O3/ZrO2 is suggested by the space-charge theory, but due to the pores and the amorphous phases covering the Al2O3 particles, the effect of the space-charge layers with high V-O(..) concentration will not be very obvious.

关键词： space-charge zirconia yttria alumina

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