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Theoretical study of ZnO adsorption and bonding on Al_2O_3(0001) surface

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Science china(Physics,Mechanics & Astronomy) 2004年第6期47卷 664-675页

作者： LI Yanrong1,YANG Chun1,2,XUE Weidong1,LI Jinshan3 & LIU Yonghua3 1.institute of Microelectronics and Solid State Electronics,University of Electronic Science and Technol- ogy of china,Chengdu 610054,china 2.institute of Mathematics and Software Science,Sichuan Normal University,Chengdu 610068,china 3.institute of Chemical Materials,china Academy of Engineering Physics,Mianyang 621000,china institute of Microelectronics and Solid State Electronics University of Electronic Science and Technology of China Chengdu 610054 China institute of Mathematics and Software Science Sichuan Normal University Chengdu 610068 China institute of Chemical Materials China Academy of Engineering Physics Mianyang 621000 China

ZnO adsorption on sapphire (0001) surface is theoretically calculated by using a plane wave ultrasoft pseudo-potential method based on ab initio molecular dynamics. The results reveal that the surface relaxation in the first layer Al-O is reduced, even eliminated after the surface adsorption of ZnO, and the chemical bonding energy is 434.3(±38.6) kJ·mol?1. The chemical bond of ZnO (0.185 ± 0.01 nm) has a 30° angle away from the adjacent Al-O bond, and the stable chemical adsorption position of the Zn is deflected from the surface O-hexagonal symmetry with an angle of about 30°. The analysis of the atomic populations, density of state and bonding electronic density before and after the adsorption indicates that the chemical bond formed by the O2 of the ZnO ? and the surface Al3+ has a strong ionic bonding characteristic, while the chemical bond formed by the Zn2+ and the surface O2 has an obvious covalent characteristic, which ? comes mainly from the hybridization of the Zn 4s and the O 2p and partially from that of the Zn 3d and the O 2p.

关键词： α-Al2O3 (0001) ZnO ab initio molecular dynamics chemical adsorption density of states

A study of two-dimensional magnetic polaron

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Science china(Physics,Mechanics & Astronomy) 2006年第4期49卷 421-429页

作者： LIU Tao1, ZHANG Huaihong1, FENG Mang1,2 & WANG Kelin1,3 1. School of Science, Southwest University of Science and Technology, Mianyang 621010, china 2. Wuhan institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430070, china 3. Department of Modern Physics, University of Science and Technology of china, hefei 230026, china School of Science Southwest University of Science Technology Mianyang 621010 China Wuhan institute of Physics Mathematics Chinese Academy of Sciences Wuhan 430070 China Department of Modern Physics University of Science Technology of china Hefei 230026 China

By using the variational method and anneal simulation, we study in this paper the self-trapped magnetic polaron (STMP) in two-dimensional anti-ferromagnetic material and the bound magnetic polaron (BMP) in ferromagnetic material. Schwinger angular momentum theory is applied to changing the problem into a coupling problem of carriers and two types of Bosons. Our calculation shows that there are single-peak and multi-peak structures in the two-dimensional STMP. For the ferromagnetic material, the properties of the two-dimensional BMP are almost the same as that in one-dimensional case; but for the anti-ferromagnetic material, the two-dimensional STMP structure is much richer than the one-dimensional case.

关键词： self-trapped magnetic polaron, bound magnetic polaron, impurity potential, anti-ferromagnet.

The suspended sediment transport equation and its near-bed sediment flux

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Science china(Technological Sciences) 2009年第2期52卷 387-391页

作者： LI RuiJie1,2, LUO Feng2 & ZHU WenJin3 1 Key Laboratory of Coastal Disaster and Defence (Hohai University), Ministry of education, Nanjing 210098, china 2 Laboratory of Marine Environment, Hohai University, Nanjing 210098, china 3 institute of Physical Oceanography, Hohai University, Nanjing 210098, china 1. Key Laboratory of Coastal Disaster and Defence (Hohai University) Ministry of Education Nanjing 210098 China 2. Laboratory of Marine Environment Hohai University Nanjing 210098 China 3. institute of Physical Oceanography Hohai University Nanjing 210098 China

The suspended sediment transport equation and its near-bed sediment flux are one of the key problems of sediment transport research under nonequilibrium condition. Based on the three-dimensional primitive suspended transport equation, the two-dimensional suspended sediment transport equation is deduced. The derived process indicates that the physical essence of the near-bed sediment flux is right the bottom boundary condition for the suspended sediment transport equation. This paper analyzes the internal relations between the two methods of sediment carrying capacity and shear stress in common use, points out the consistency of these two methods in terms of form and physical meaning, and unifies these two methods theoretically. Furthermore, based on the analysis and comparison of the expressions of the near-bed sediment flux, this paper summarizes some problems to which attention should be paid, thus offering a novel approach to the study and the solution of the problems of suspended sediment transport and exchange flux of near-bed water sediment.

关键词： suspended sediment transport equation near-bed sediment flux sediment carrying capacity shear stress

Effect of Thermal Fatigue Loading on Tensile Behavior of H13 Die Steel with Biomimetic Surface

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Journal of Bionic Engineering 2010年第4期7卷 390-396页

作者： Zhihui Zhang~1,Luquan Ren~1,Hong Zhou~2,Zhiwu Han~1,Xin Tong~3,Yu Zhao~1,Li Chen~1 1.Key Laboratory of Bionic Engineering (Ministry of education,china),Jilin University,Changchun 130022,P.R.china 2.Key Laboratory of Automobile Materials (Ministry of education,china),Jilin University,Changchun 130022,P.R.china 3.The Department of Materials Surface Engineering,Guangzhou Research institute of Non-Ferrous Metals,Guangzhou 510651,P.R.china [a] Key Laboratory of Bionic Engineering (Ministry of education China) Jilin University Changchun 130022 P. R. China [b] Key Laboratory of Automobile Materials (Ministry of Education China) Jilin University Changchun 130022 P. R. China [c] The Department of Materials Surface Engineering Guangzhou Research Institute of Non-Ferrous Metals Guangzhou 510651 P. R. China

Biomimetic surface is an effective ways to promote the performance grade and applied range of materials without alteringtheir *** improved properties such as resisting fatigue,enduring wear,etc,have been achieved by applyingbiomimetic morphology or structure to some engineering material *** this paper,aiming to reveal the relationshipbetween thermal cracking behavior and mechanical properties of engineering materials with biomimetic surface,biomimeticspecimens were fabricated using laser technique by imitating the heterogeneous structure on the surface of plant *** of thermal fatigue cycling on the tensile properties of H13 die steel specimens with different surfaces (several types ofbiomimetic surfaces and a smooth surface) was compared and *** a result,due to the coupling effects of themorphological features on the surface and the microstructure characteristics within unit zone,these specimens with biomimeticsurface exhibit remarkably enhanced Ultimate Tensile Strength (UTS) and 0.2% Yield Strength (YS) compared with referencespecimens while corresponding ductility remains largely unaffected even heightened,whether the thermal fatigue loads or *** relative mechanisms leading to these improvements have been discussed.

关键词： biomimetic surface coupling thermal fatigue tensile property H13 steel

Anomalous magnetotransport in LaMn_(1-x)Te_xO_3

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Science china(Physics,Mechanics & Astronomy) 2009年第7期52卷 987-992页

作者： TAN GuoTai1,2, CHEN ZhengHao3 & ZHANG XiaoZhong4,5 1 Key Laboratory of Beam Technology & Materials Modification of the Ministry of education, institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing 100875, china 2 Beijing Radiation Center, Beijing 100875, china 3 Laboratory of Optical Physics, institute of Physics, Chinese Academy of Sciences, Beijing 100080, china 4 Key Laboratory of Advanced Materials of the Ministry of education, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, china 5 Beijing National Center for Electron Microscopy, Tsinghua University, Beijing 100084, china 1. Key Laboratory of Beam Technology & Materials Modification of the Ministry of education Institute of Low Energy Nuclear Physics Beijing Normal University Beijing 100875 China 2. Beijing Radiation Center Beijing 100875 China 3. Laboratory of Optical Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China 4. Key Laboratory of Advanced Materials of the Ministry of education Department of Materials Science and Engineering Tsinghua University Beijing 100084 China 5. Beijing National Center for Electron Microscopy Tsinghua University Beijing 100084 China

The LaMn1-xTexO3+δ (x=0.1, 0.2, 0.3) were synthesized using solid-state reaction method for the first time. X-ray photoemission spectrum (XPS) shows that in the samples the Te ions have a valence of Te4+, and Mn3+ ions are partly converted into Mn2+ and Mn4+ due to the excess oxygen and Te doping. The magnetotransport associated with Mn2+, Mn3+ and Mn4+ was investigated. The experimental results show that the samples are insulator at 0 T when the amount of Mn3+ is much larger or less than the sum of Mn2+ and Mn4+; by contrast, the samples display metal to insulator transition with increasing temperature when the amount of Mn3+ is close to the sum of Mn2+ and Mn4+. These anomalous magnetotransport behaviors were analyzed in the frame of the double-exchange (DE) mechanism.

关键词： colossal magnetoresistance La-Te-Mn-O magnetotransport

A new elliptic-parabolic yield surface model revised by an adaptive criterion for granular soils

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Science china(Technological Sciences) 2010年第8期53卷 2152-2159页

作者： LIU HanLong 1,2 ,XIAO Yang 1,2 ,LIU JinYuan 3 &LI GuoYing 4 1 Key Laboratory of Ministry of education for Geomechanics and Embankment Engineering,Hohai University, Nanjing 210098,china 2 Geotechnical Research institute,Hohai University,Nanjing 210098,china 3Department of Civil Engineering,Ryerson University,Toronto,Canada 4 Department of Geotechnical Engineering,Nanjing Hydraulic Research institute,Nanjing 210014,china 1. Key Laboratory of Ministry of education for Geomechanics and Embankment Engineering Hohai University Nanjing 210098 China2. Geotechnical Research Institute Hohai University Nanjing 210098 China3. Department of Civil Engineering Ryerson University Toronto Canada4. Department of Geotechnical Engineering Nanjing Hydraulic Research Institute Nanjing 210014 China

An adaptive criterion for shear yielding as well as shear failure of soils is proposed in this paper to address the fact that most criteria,including the Mohr-Coulomb criterion,the Lade criterion and the Matsuoka-Nakai criterion,cannot agree well with the experimental results when the value of the intermediate principal stress parameter is too *** new criterion can adjust an adaptive parameter based on the experimental results in order to make the theoretical calculations fit the test results more *** original elliptic-parabolic yield surface model can capture both soil contraction and dilation ***,it normally over-predicts the soil strength due to its application of the Extended Mises criterion.A new elliptic-parabolic yield surface mode is presented in this paper,which introduces the adaptive criterion in three-dimensional principal stress *** new model can well model the stress-strain behavior of soils under general stress *** to the original model which can only simulate soil behavior under triaxial compression conditions,the new model can simulate soil behaviors under both triaxial compression conditions and general stress conditions.

关键词： principal stress space intermediate principal stress yield surface failure criterion constitutive model

Synthesis of superheavy nuclei with ^(238)U target

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Science china(Physics,Mechanics & Astronomy) 2009年第10期52卷 1482-1488页

作者： LIU ZuHua1,3 & BAO JingDong2,4 1 Key Laboratory of Beam Technology and Material Modification of Ministry of education,Beijing Normal University,Beijing 100875,china 2 Department of Physics,Beijing Normal University,Beijing 100875,china 3 china institute of Atomic Energy,Beijing 102413,china 4 Center of Theoretical Nuclear Physics,National Laboratory of Heavy Ion Accelerator of Lanzhou,Lanzhou 730000,china Key Laboratory of Beam Technology and Material Modification of Ministry of education Beijing Normal University Beijing 100875 China Department of Physics Beijing Normal University Beijing 100875 China china institute of Atomic Energy Beijing 102413 China Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou 730000 China

The production of superheavy nuclei with Z=108-116 via hot fusion reactions of the neutron-rich projectiles with 238U target is systematically *** results show that the production cross sections of superheavy nuclei do not decrease monotonously as the atomic number Z *** cross sections of the superheavy nuclei at Z = 112 and 115 are enhanced as compared with the whole Z-trend in synthesis of the superheavy nuclei,which clearly illustrates that the reactions with large negative Q-value and shell correction are more favorable to synthesize superheavy nuclei.

关键词： superheavy nuclei fusion reaction cross section 238U target

Comparison between CMM2 & ISO9001

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Wuhan University Journal of Natural Sciences 2001年第Z1期6卷 516-523页

作者： Pan Qiu ling, Liu Zong tian, Wu Peng cheng Research institute of Microcomputer, hefei University of Technology, hefei 230009, china Research institute of Microcomputer Hefei University of Technology Hefei China

The Capability Maturity Model(CMM) and ISO9001 are probably the two best known and most widely used models for software organization quality assurance and improvement. As they both continue to evolve, each has a series of versions which own new aspects. This paper discusses the similarities and differences between the two models, based on the CMM version 2.0 c and the 1997 release of ISO9001, examines 20 clauses in ISO9001 and maps them to practices in the latest CMM. In the end, their implementations in china are presented.

关键词： software quality assurance ISO9001 CMM v2.0 c

STUDY OF Ag DIFFUSION INTO Cu SINGLE CRYSTALS BY RUTHERFORD BACKSCATTERING SPECTROMETRY

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Acta Metallurgica Sinica(English Letters) 2003年第5期16卷 332-334页

作者： R.Wang 1) Key Laboratory of Beam Technology and Materials Modification, Ministry of education, Beijing 100875, china2) institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing 100875, china3) Beijing Radiation Center, Beijing 100875, china Key Laboratory of Beam Technology and Materials Modification Ministry of Education Beijing 100875China institute of Low Energy Nuclear Physics Beijing Normal University Beijing 100875 China Beijing Radiation Center Beijing 100875 China

4.0Me V 7Li++ RBS was used for investigations of thermal diffusion of Ag in Cu single crystals. The annealing of samples was carried out in vacuum in the temperature range from 498K to 613K. The element depth concentration profiles transformed from RBS spectra indicate that the diffusion of Ag into Cu is a typical volume diffusion. The Arrhenius parameters corresponding to the diffusion were obtained.

关键词： Ag diffusion single crystal