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The influence of impurity on the critical thickness of the CeO_2 buffer layer for coated conductors

Science China(Physics,Mechanics & Astronomy) 2009年第7期52卷 993-996页

作者： PAN Min1, HUANG Zheng2, MA HuanFeng2, QIANG WeiRong2, WEI LianFu1, WANG Long2 & ZHAO Yong1,3.1 Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), superconductivity R&D Center (SRDC), southwest Jiaotong university, Chengdu 61003., China 2 {3. of Physical Science and Technology, southwest Jiaotong university, Chengdu 61003., China 3.superconductivity research group, {3. of materials Science and engineering, university of new south wale, sydney, 2052 nsw,{13. Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China) Superconductivity R&D Center (SRDC) Southwest Jiaotong University Chengdu China school of Physical Science and Technology Southwest Jiaotong University Chengdu China superconductivity research group School of Materials Science and Engineering University of New South Wale Sydney Australia

The lattice parameters, band structure, density of state and elastic constant of RE-doped CeO2 (RE=Sm, Gd, Dy), the buffer material for coated HTS conductors, are calculated using the plane-wave method with pseudopotentials based on the density functional theory (DFT) of first-principle. The rule and mechanism of the effect of rare earth impurity on the critical thickness of the CeO2 buffer layer are investigated. It is found that, in the range of the calculation, the changes of the lattice volume V and elastic constant E of CeO2 with the impurity are mainly determined by the increased electrons ne of the system. The relationship of the elastic constant E and increased electrons ne is established. It is indicated that the critical thickness of the CeO2 single buffer layer doped with Sm, Gd, and Dy may be enhanced by 22%, 43. and 3.%, respectively.

关键词： CeO2 first principle critical thickness elastic constants

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Molecular Dynamics Simulation of Dealloyed Layer-induced Tensile Stress in Cu_3.u

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Journal of university of Science and Technology Beijing 2001年第4期8卷 295-298页

作者： Qikai L, Yue Zhang, Mark Hoffman, Wuyang Chu 1)materials Science and engineering school. {3. of Science and Technology Beijing. Beijing 100083. China 2)school of materials Science & engineering, university of new south wales, sydney 2052, Austral materials Science and engineering school University of Science and Technology Beijing Beijing 100083 China school of materials Science and engineering University of New South Wales Sydney NSW 2052 Australia

During stress corrosion cracking of Cu3.u alloy, there is a dealloyed layer on its surface because of preferential dissolution of Cu, and there is a linear distribution of Cu vacancy concentration in the dealloyed layer. Molecular dynamics simulation has been done on the three-dimensional crystal (about 148 000 atoms) by employing the embedded-atom method (EAM) potential. Simulation shows that Cu3.u crystal in which there is a dealloyed layer on one surface and one end is fixed will be deflected after relaxing for a long time because of a tensile stress generated at or near the dealloyed layer interface. The deflection and then the tensile stress increase with increasing the depth of dealloyed layer and the vacancy concentration in the dealloyed layer.

关键词： dealloyed layer-induced stress molecular dynamics simulation Cu3.u

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Characteristic atom arranging crystallogphy of alloy phases for Au-Cu system

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Science China(Technological Sciences) 2011年第6期54卷 1560-1567页

作者： XIE YouQing1,2,3.LIU XinBi1,2,3.PENG HongJian4,NIE YaoZhuang5,LI XiaoBo6 & LI YanFen1,2,3.1 school of materials Science and engineering,Central {3. university,Changsha 410083.China 2 Powder Metallurgy research Institute,Central {3. university,Changsha 410083.China 3.State Key Laboratory of Powder Metallurgy,Central {3. university,Changsha 410083.China 4 school of Chemistry and Chemical engineering,Central {3. university,Changsha 410083.China 5 school of Physical Science and Technique,Central {3. university,Changsha,410083.China 6 College of Mechanical engineering,Xiangtan university,Xiangtan 411105,China school of materials Science and engineering Central South University Changsha China Powder Metallurgy research Institute Central South University Changsha China State Key Laboratory of Powder Metallurgy Central South University Changsha China school of Chemistry and Chemical engineering Central South University Changsha China school of Physical Science and Technique Central South University Changsha China College of Mechanical engineering Xiangtan University Xiangtan China

In this paper,it is pointed out that the descriptions of alloy phase structures are dependent on structural unit *** the systematic science of alloys(SSA),the alloy phase structures are described by means of the symmetry element sequence combining with characteristic atom *** is named the characteristic atom arranging structure,which can display the characteristic atoms at the lattice sites and the micro-inhomogeneity,besides the *** characteristic atom has its own characters:neighboring configuration,potential energy,volume and electronic *** micro-inhomogeneity of alloy phases can be described by concentrations and short-range ordered parameters of characteristic *** differences between the electronic structures of alloy phases and electronic structures of characteristic atoms in the alloy phases are also discussed.

关键词： systematic science of alloys Au-Cu system alloy phase structure micro-inhomogeneity

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Enhancement of flux pinning in GdBa_2Cu_3._(7-y) bulks prepared by nanoparticle-powder-assisted method

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Journal of Modern Transportation 2011年第2期19卷 104-109页

作者： C.H. CHENG Chang Chun HSIEH Chuan KE H. ZHANG C.C. SORRELL superconductivity research group School of Materials Science and Engineering University of New South Wales Sydney 2052 NSW Australia Key Laboratory for Levitation Technology and Maglev Trains Ministry of Education of China Superconductivity and New Energy Center （SNEC） Southwest Jiaotong University Chengdu 610031 China Department of Physics Peking University Beijing 100871 China

High quality GdBa2Cu3.7-y （Gd123. textured bulks with Nd2BaCuO5 （Nd211） nanoparticle precipitations have been fabricated by a nanoparticle-powders-assisted MTG （melt-textured-growth） technique. The high density nanoscale flux pinning sites were introduced into Gd123.by mixing Nd211 nanoparticle powders （about 20-50 nm） with Gd123.nano-precursors before the MTG process. Microstructural analyses reveal that a large number of Nd211 nanoparticles with a size around 50-150 nm were inserted in the Gd123.matrix, forming a kind of superconducting nanocomposites. The critical current density at 77 K is systematically increased and the flux pinning behavior is significantly improved. The scaling behavior of the flux pinning force shows a magnetic field dependent feature with a peak located at hp≈0.4. This may be the fingerprint of melt-textured 123.compounds, which cannot be interpreted by the simple superposition of different types of elementary pinning sources.

关键词： flux pinning GdBa2Cu3.7-y nanoparticle-powder assisted processing critical current density

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DISCRETE PARTICLE SIMULATION OF SIZE SEGREGATION OF PARTICLE MIXTURES IN A GAS FLUIDIZED BED

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Particuology 2006年第Z1期 122-126页

作者： Y. Q. Feng1,2 and A. B. Yu1,* 1Center for Simulation and Modelling of Particulate Systems, school of materials Science and engineering, The{3.s, sydney nsw 2052, australia 2Divisions of Minerals, Commonwealth Scientific and Industrial research Organization, Box 3.2, Clayton south, Victoria 3.69, australia

This paper presents a study of the mixing/segregation behaviour of particle mixtures in a gas fluidized bed by use of the discrete particle simulation. Spherical particles with diameters 2 mm (jetsam) and 1 mm (flotsam) and den- sity 2 500 kg?m-3.are used as solid mixtures with different volume fractions. The particles are initially packed uniformly in a rectangular bed and then fluidized by gas uniformly injected at the bottom of the bed. The gas injection velocities vary to cover fixed, partially and fully fluidized bed conditions. Segregation/mixing behaviour is discussed in terms of flow patterns, solid concentration profile and mixing kinetics. The results show that segregation, as a transient fluidization process, is strongly affected by gas injection velocities for a given particle mixture. With the increase of the volume frac- tion of flotsam, size segregation appears at lower velocities.

关键词： gas fluidization segregation discrete particle simulation

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Some Challenging Problems in Discrete Element Modelling of Particulate Systems

Some Challenging Problems in Discrete Element Modelling of P...

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2012颗粒材料计算力学会议

作者： Yu Ai-Bing Laboratory for Simulation and Modelling of Particulate Systems (Simpas) school of materials Science and engineering The{3.s sydney,nsw 2052 australia

Particle science and technology is a rapidly developing interdisciplinary research area with its core being the understanding of the relationships between micro-and macro-scopic properties of particulate/granular matter-a state of matter that is widely encountered but poorly understood. The macroscopic behaviour of particulate matter is controlled by the interactions between individual particles as well as interactions with surrounding fluids and wall. Understanding the microscopic mechanisms in terms of these interaction forces is therefore key to leading to truly interdisciplinary research into particulate matter and producing results that can be generally used. This aim can be effectively achieved via particle scale research based on detailed microdynamic information such as the forces acting on and trajectories of individual particles in a considered system. In recent years, such research has been rapidly developed worldwide, mainly as a result of the rapid development of discrete particle simulation technique and computer technology.

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Ti/Al_2O_3.Functionally Gradient Material Prepared by the Explosive Compaction/SHS Process

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Journal of materials Science & Technology 1999年第3期15卷 271-275页

作者： Yimin LI(Powder Metallurgy research Institute, Central-south university of Technology, Changsha 410083. China)Ziqiao ZHENG(Department of {3. Science and engineering, Central-south university of Technology, Changsha 410083. China) Powder Metallurgy research Institute Central-South University of Technology Changsha 410083 China Department of materials Science and engineering Central-South University of Technology Changsha 410083 China

Ti1Al2O3.Functionally Gradient Material (FGM) was prepared by an explosive compaction/SHS process. Ten sheets of the compounding powder were laminated and pressed to get a green body of FGM. It was then compacted explosively By burying the explosive compaction body into a stoichiometric Al/TiO2 mixture and igniting the combustion of the stoichiometric Al/TiO2 mixture, the SHS reaction of the explosive compaction body was initiated by the heat released from the combustion of the stoichiometric Al/TiO2 mixture. In this way, Ti/Al2O3.FGM was synthesized. The adiabatic temperatures of each gradient layer were calculated when the preheating temperatures were 298 K and 1173.K, respectively The microstructure, composition and properties of Ti/Al2O3.FGM and the reaction mechanism of each gradient layer were studied. It was found that Ti/Al2O3.FGM prepared by the explosive compaction/SHS process had a high density and a high microhardness. Its structure, composition and properties showed apparent gradient distribution. The structure of the standard stoichiometric ratio gradient layer of FGM was a network structure. Its reaction mode could be described as follows: Al powder melted first, then the molten Al penetrated into the TiO2 zone and reacted with TiO2, and big pores were left in the original positions of Al powder. The reaction of gradient layers with the addition of Al3.3.as diluents was similar to that of the standard stoichiometric ratio gradient layer, so were their structure and composition. However, the reaction of gradient layers with the addition of Ti as diluents was more complex and the composition deviated slightly from the designed one

关键词： Al SHS Ti/Al2O3.Functionally Gradient Material Prepared by the Explosive Compaction/SHS Process

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Heat transfer characteristics of bio-materials irradiated by pulsed-laser

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Progress in Natural Science:materials International 2002年第12期12卷 52-56页

作者： HUAI Xiulan LIU Dengying, ZHOU Jianhua and YU Aibing(1. Institute of engineering Thermophysics, Chinese Academy of Sciences, Beijing 100080, China 2. school of materials Science and engineering, The university of new south wales, sydney, nsw 2052, australia) Institute of engineering Thermophysics Chinese Academy of SciencesBeijing 100080 China school of materials Science and engineering The University of New South Wales Sydney NSW 2052 Australia

The dynamic temperature variation of bio-materials induced by pulsed-laser irradiation is determined by a rapid transient temperature measuring system. The heat transfer characteristics of bio-materials, and the influence of pulse duration, power density, thickness and initial moisture content of bio-materials on heat transfer are studied. Based on the experiments, a mathematical model of bio-heat transfer is set up. Numerical simulation results show that the calculated results agree well with the experimental results, and bioheat transfer characteristics irradiated by pulsed-laser can be displayed well. Valuable information and experiences are provided for further experimental and theoretical investigation.

关键词： bio-materials dynamic temperature measurement pulsed-laser.

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