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High-pressure synthesis and properties of CeO_2-ZrO_2 solid solution

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chinese science Bulletin 2001年第10期46卷 801-806页

作者： XU Dapeng, WANG Quanyong, LU Zhe, LIU Zhiguo, ZHANG Gongmu & SU Wenhui1. Department of physics, Jilin University, Changchun 13.023.China 2. International center for Materials physics, {3., Shenyang 110015, China 3. center for Condensed Matter and Radiation physics, China center of Advanced science and Technology (World Laboratory), beijing 100080, China Department of physics Jilin University Changchun China International center for Materials physics Chinese Academy of Sciences Shenyang China center for Condensed Matter and Radiation physics China Center of Advanced Science and Technology (World Laboratory) Beijing China

Using nanoparticles of CeO2 and ZrO2 prepared by the chemical precipitation method as starting materials, the single-phase cubic Ce0.5Zr0.5O2 solid solution (c-Ce0.5Z0.5O2) has been synthesized under 3.1 GPa at 1073.K for the first time. The structure of the c-Ce0.5Zr0.5O2 has not been changed before and after annealing at 773.K for 1 h. Only an unknown EPR signal (g =1.990) has been observed in the c-Ce0.5Zr0.5O2 and not varied after annealing at 773.K for 1 h, which exhibited that there exists no Ce3. in the c-Ce0.5Zr0.5O2 and the Ce4. has not been reduced into Ce3. after annealing. The transport mechanism is ionic for the c-Ce0.5Zr0.5O2. The bulk conductivity (a =1.2×10-5 S/cm at 823.K, σ=2.1 ×10-3.S/cm at 1123.K) is the same as that of CeO2, but smaller than that of Y2O3.stabilized ZrO2. A marked curvature at T = 823.K has been observed in the Arrhenius plot of the bulk conductivity. The activation energy below 823.K is lower than that above 823.K, and the reason has been discussed.

关键词： CeO2-ZrO2 nanocrystalline high-pressure and -temperature solid-state reaction solid solution.

β-delayed proton decays near the proton drip line

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science China(physics,Mechanics & Astronomy) 2005年第3期48卷 257-267页

作者： XU Shuwei 1 , LI Zhankui 1 , XIE Yuanxiang 1 , HUANG Wenxue 1 , SHU Nengchuan 2 , CHEN Yongshou 2 , XU Furong 3., WANG Kun 4., PAN Qiangyan 1 , WANG Xudong 1 , YU Yong 1 & XING Yebing 1 1. Institute of Modern physics, chinese academy of sciences, Lanzhou 73.000, China 2. Nuclear physics Department, China Institute of Atomic Energy, {3. 1024.3. China 3. Department of Technical physics, Peking University, {3. 100871, China 4. Shanghai Institute for Nuclear Research, Shanghai 201800, China Institute of Modern physics Chinese Academy of Sciences Lanzhou China Nuclear physics Department China Institute of Atomic Energy Beijing China Department of Technical physics Peking University Beijing China Shanghai Institute for Nuclear Research Shanghai China

We briefly reviewed the experimental study on a-delayed proton decays near the proton drip line published by our group during the period of 1996―2004. namely the first observation of the a-delayed proton decays of 9 new nuclides in the rare-earth region and the new measurements of a-delayed proton decays of 5 nuclides in the mass ～90 region near the N = Z line with the aid of the “p-?” coincidence in combination with a He-jet tape transport system. In the meantime some important experimental technique details were supplemented. The experimental results, including the half -lives, spins, parities, deformations and production reaction cross sections for the 14.nuclei were summarized and compared with the current nuclear-model predictions, and then the following points were represented. (1) The experimental half-lives for 85Mo and 92Rh as well as the predicted “waiting point” nuclei 89Ru and 93.d are 5―10 times longer than the theoretical predictions given by M?ller et al. using a macroscopic-microscopic model. It considerably influences the predictions of the abundances of the nuclides produced in the rp-process. (2) The current-model predictions are not consistent with the experimental assignments of the spins and parities for the proton drip-line nuclei 14.Ho and 128Pm. However, the nuclear potential energy surface (PES) calculated by using a Woods- Saxon-Strutinsky method reproduced the experimental results. (3. The Alice code overestimated the production reaction cross sections of the studied 9 rare-earth nuclei by one order of magnitude or two, while HIVAP code overestimated them by one order of magnitude approximately.

关键词： proton drip line, β-delayed proton decay, He-jet tape transport system, "p-γ" coincidence, spin, parity, deformation, production reaction cross section.

The red damping wing of Gunn-Peterson trough in the high redshift GRBs

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science China(physics,Mechanics & Astronomy) 2009年第9期52卷 1428-1433页

作者： XU Zhou1,2 & WEI DaMing1,3.1 Purple Mountain Observatory, chinese academy of sciences, Nanjing 210008, China 2 Graduate University of chinese academy of sciences, beijing 100012, China 3.Joint {3. for Particle Nuclear {4. and Cosmology of Purple Mountain Observatory-Nanjing University, Nanjing 210008, China Purple Mountain Observatory Chinese Academy of Sciences Nanjing China Graduate University of chinese academy of sciences Beijing China Joint center for Particle Nuclear physics and Cosmology of Purple Mountain Observatory-Nanjing University Nanjing China

We calculate the red damping wing of Gunn-Peterson trough taking the evolution of the neutral fraction into consideration and take a clear look at the ionized region around the ionizing sources. We get the result that the damping wing flux feature is mainly determined by the neutral hydrogen outside the ionized bubble and the cut off in the damping wing would be useful to get the size of the ionized bubble. We also fit the red damping wing of the recently discovered high redshift GRB080913.and find that the ionized bubble is too small to create apparent cut off in the spectrum of this burst.

关键词： cosmology theory intergalactic medium gamma ray burst

The study of energy bands in nucleus ^(102)Zr

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science China(physics,Mechanics & Astronomy) 2010年第1期53卷 106-110页

作者： DONG GuoXiang 1,2 , YU ShaoYing 1,2,3., LIU YanXin 1 , SHEN CaiWan 1,2,4.& DONG YongSheng 1,2,5I School of science, Huzhou Teachers College, Huzhou 3.3.00, China 2 School of science and Information Engineering, Zhejiang Normal University, Jinhua 3.1000, China 3.Institute of theoretical {3., {4., beijing 100080, China 4.center of theoretical Nuclear {3., National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou 73.000, China 5 Department of {3., Jining Teachers College, Jining 012000, China Huzhou Teachers College School of Science Huzhou China (GRID:grid.411440.4) (ISNI:***) Zhejiang Normal University School of Science and Information Engineering Jinhua China (GRID:grid.453534.0) (ISNI:***) Huzhou Teachers College School of Science Huzhou China (GRID:grid.411440.4) (ISNI:***) Zhejiang Normal University School of Science and Information Engineering Jinhua China (GRID:grid.453534.0) (ISNI:***) chinese academy of sciences Institute of Theoretical Physics Beijing China (GRID:grid.9227.e) (ISNI:***) Huzhou Teachers College School of Science Huzhou China (GRID:grid.411440.4) (ISNI:***) Huzhou Teachers College School of Science Huzhou China (GRID:grid.411440.4) (ISNI:***) Zhejiang Normal University School of Science and Information Engineering Jinhua China (GRID:grid.453534.0) (ISNI:***) National Laboratory of Heavy Ion Accelerator of Lanzhou Center of Theoretical Nuclear Physics Lanzhou China (GRID:grid.450259.f) (ISNI:0000 0004 1804 2516) Huzhou Teachers College School of Science Huzhou China (GRID:grid.411440.4) (ISNI:***) Zhejiang Normal University School of Science and Information Engineering Jinhua China (GRID:grid.453534.0) (ISNI:***) Jining Teachers College Department of Physics Jining China (GRID:grid.452558.b)

theoretical calculations of the energy bands in nucleus 102 Zr are carried out by taking the projected shell model approach, which has reproduced the experimental data. In addition, by analyzing band-head energies, corresponding configurations of yrast band, quasi-particle rotational bands and side bands, we have worked out the microscopic formation mechanism of axially symmetric deformation bands: The low-excitation deformation bands are attributed to the high-j intruder states 1g 7/2 and 1h 11/2 in the N=4. 5 shells; the quasi-particles in the orbit v5/2-[53.], v3.2+[4.1] and v3.2+[4.3. in particular play an important role in the deformation of 102 Zr.

关键词： projected shell model yrast band quasi-particle rotational band side band

An Explicit Function Expression for dc Bias and Temperature Dependence of Magnetoresistances in Magnetic Tunnel Junctions

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Journal of Materials science & Technology 2002年第6期18卷 497-501页

作者： Xiufeng HANState Key Laboratory of Magnetism, Institute of physics and center of Condensed Matter physics, {3., {4. 100080, China chinese Acad Sci Inst Phys State Key Lab Magnetism Beijing 100080 Peoples R China chinese Acad Sci Ctr Condensed Matter Phys Beijing 100080 Peoples R China

An explicit function expression for the bias voltage or/and temperature dependences of tunnel magnetoresistance ratio and resistances were obtained with a unique set of intrinsic parameters. Two of these intrinsic parameters are the Curie temperature TC and the density of state (DOS) for itinerant majority and minority electrons ξ(ρM/ρm), which are the eigen parameters of ferromagnetic electrodes. Others are the spin-dependent matrix-element ratio (i.e., |Td|2/|TJ|2 ) and the anisotropic-wavelength-cutoff energy ECγ of spin-wave spectrum in magnetic tunnel junction (MTJ), which are the structure parameters of an MTJ. These intrinsic parameters can be predetermined using the experimental measurement or, in principle, using the first-principle calculation method for an MTJ with the three key layers of FM/I/FM. Furthermore, a series of experimental data for an MTJ, for example, a spin-valve-type MTJ of Ta (5 nm)/Ni79Fe21(25 nm)/lr22Mn78(12 nm)/Co75Fe25(4.nm)/AI(0.8 nm)-oxide/Co75Fe25(4.nm)/Ni79Fe21(20 nm)/Ta (5 nm) in this work, can be self-consistently evaluated and explained using such concise explicit function formulations.

关键词： Magnetic tunnel junction TMR Spin-electron transport Magnon excitation Spin-polarization Magnetotransport

The effect of hydrogen on the electronic structure of kink in bcc iron

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science China(Technological sciences) 2009年第5期52卷 1212-1218页

作者： CHEN LiQun1,QIU ZhengChen1,YU Tao2 & WANG ChongYu2,3.4.1 College of sciences,Central South University of Forestry and Technology,Changsha 4.0004.China 2 Central Iron and Steel Research Institute,beijing 100081,China 3.Department of {4.,Tsinghua University,beijing 100084.China 4.International {4. for Materials {4.,chinese academy of sciences,Shenyang 110016,China College of sciences Central South University of Forestry and Technology Central Iron and Steel Research Institute

The electronic structures of kinks in the [100](010) and 1/2[111](-110) edge dislocations in bcc iron containing hydrogen are investigated by means of the first-principles DMol method and the discrete variational *** effects of hydrogen on the kinks are *** results show that hydro-gen forms weak bonding states with its neighboring host atoms,and since hydrogen draws charge from its neighboring host atoms,the interactions between most of the host atoms are weakened com-pared with those of the corresponding atomic pairs in the clean *** indicates that the migration of kink,*** motion of dislocation,is easier in the doping hydrogen kink than in the clean kink,which may be the solid solution softening effect resulting from the impurity hydrogen.

关键词： electronic structure dislocation kink impurity

Molecular dynamics simulation of kink in 〈100〉 edge dislocation in body centred cubic iron

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chinese science Bulletin 2007年第16期52卷 2291-2296页

作者： CHEN LiQun1,2,WANG ChongYu2,3.4.& YU Tao2 1 College of sciences,Central South University of Forestry & Technology,Changsha 4.0004.China 2 Central Iron and Steel Research Institute,beijing 100081,China 3.Department of {4.,Tsinghua University,beijing 100084.China 4.International {4. for Materials {4.,chinese academy of sciences,Shenyang 110016,China College of sciences Central South University of Forestry & Technology Changsha 410004 China Iron and Steel Research Institute Beijing 100081 China Department of physics Tsinghua University Beijing 100084 China International center for Materials physics Chinese Academy of Sciences Shenyang 110016 China

Using the molecular dynamics method,we have constructed two kink models corresponding to the 〈100〉{010} and 〈100〉{011} edge dislocations (EDs) in body centred cubic (bcc) Fe. It is found that the geometric structure of a kink depends on the type of edge dislocation and the structural energies of the atoms sites in the dislocation core region. The formation energies,migration energies and widths of the kinks in different types of EDs are calculated. The results show that formation and migration of the kink in the 〈100〉{010} edge dislocation are difficult. The 〈100〉{011} edge dislocation moves primarily through kink nucleation,rather than kink migration.

关键词：分子动力学边缘位移铁纽结结构

Further research on high-spin structure in ^(161)Lu

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science China(physics,Mechanics & Astronomy) 2008年第3期51卷 315-320页

作者： LI YanXia1,2,YU ShaoYing1,2,4.SHEN CaiWan1,5,LI XiaoWei6 & CHEN YongShou3.4.1 School of science,Huzhou Teachers College,Huzhou 3.3.00,China 2 College of Mathematics,{4. and Information Engineering,Zhejiang Normal University,Jinhua 3.1000,China 3.China Institute of Atomic Energy,beijing 1024.3.China 4.Institute of {3. {4.,chinese academy of sciences,beijing 100080,China 5 center of {3. Nuclear {4.,National Laboratory of Heavy Ion Accelerator of Lanzhou,Lanzhou 73.000,China 6 Department of {4.,Chifeng University,Chifeng 024.01,China School of science Huzhou Teachers College Huzhou China College of Mathematics Physics and Information Engineering Zhejiang Normal University Jinhua China Institute of theoretical physics Chinese Academy of Sciences Beijing China center of theoretical Nuclear physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou China Department of physics Chifeng University Chifeng China China Institute of Atomic Energy Beijing China

The two-dimensional total routhian surface (TRS) calculations were performed to probe into the triaxial superdeformed characteristics of a strongly populated band X2 in 161Lu. This band was identified as a triaxial superdeformed band by using our TRS method. We also got its formation mechanics,i.e. the neutron-shell correction energy plays a crucial role,while the rotating energy and the deformation-driving effect of high j intruder orbit i13.2 also play an additional role.

关键词： TRS method triaxial superdeformation formation mechanism

The dynamical properties of Rydberg hydrogen atom near a metal surface

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science China(physics,Mechanics & Astronomy) 2005年第6期48卷 667-675页

作者： GE Meihua1, ZHANG Yanhui1, WANG Dehua2, DU Mengli3.& LIN Shenglu1 1. College of physics and Electronics, Shandong Normal University, Jinan 250014. China 2. Department of Mathematics and physics, Shandong Institute of Architecture and Engineering, Jinan 250014. China 3. Institute of {4. physics, {4., beijing 100080, China College of physics and Electronics Shandong Normal University Jinan China Department of Mathematics and physics Shandong Institute of Architecture and Engineering Jinan China Institute of theoretical physics Chinese Academy of Sciences Beijing China

The dynamical properties of Rydberg hydrogen atom near a metal surface are presented by using the methods of phase space analysis and closed orbit theory. Transforming the coordinates of the Hamiltonian, we find that the phase space of the system is divided into vibrational and rotational region. Both the Poincaré surface of section and the closed orbit theory verify the same conclusion clearly. In this paper we choose the atomic principal quantum number as n = 20. The dynamical character of the exited hydrogen atom depends sensitively on the atom-surface distance d. When d is sufficiently large, the atom-surface potential can be expressed by the traditional van der Waals force and the system is integrable. When d becomes smaller, there exists a critical value dc. For d > dc, the system is near-integrable and the motion is regular. While chaotic motion appears for d < dc, and the system tends to be non-integrable. The trajectories become unstable and the electron might be captured onto the metal surface.

关键词： Rydberg hydrogen atom, van der Waals interaction, Poincaré surface of section, closed orbit theory, chaos.