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Electron transport properties of boron-doped capped-carbon-nanotube-based molecular junctions

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Science Bulletin 2010年第36期55卷 4104-4107页

作者： ZHAO Peng1 & LIU DeSheng2 1 school of Science, university of jinan, jinan 250022, china 2 school of physics, state key laboratory of crystal materials, shandong university, jinan 250100, china school of Science University of Jinan Jinan 250022 China school of physics State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China

Using the Landauer formalism that combines both the non-equilibrium Green’s function and first-principles density functional theory, the electron transport properties of a one-dimensional molecular junction based on capped carbon nanotubes with boron doping at various sites are investigated. The results show that the electron transport properties are strongly dependent on the boron-doping site. Negative differential resistance behavior can be observed when boron-atom dopants are present in the tip region.

关键词： carbon nanotube doping non-equilibrium Green’s function density functional theory

Capped carbon nanotube-based molecular switch

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Science Bulletin 2010年第13期55卷 1227-1230页

作者： ZHAO Peng1, WANG PeiJi1, ZHANG Zhong1 & LIU DeSheng2 1 school of Science, university of jinan, jinan 250022, china 2 school of physics, state key laboratory of crystal materials, shandong university, jinan 250100, china school of Science University of Jinan Jinan 250022 China school of physics State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China

Using the Landauer formalism that combines both the non-equilibrium Green's function (NEGF) and first-principles density functional theory (DFT), the electron transport characteristics of one-dimensional molecular switching device based on the capped carbon nanotubes have been investigated. The results show that the transmission can be efficiently tuned within two orders of magnitude just by changing 0.2 nm of the tube-tube separation. Moreover, the electron transport is insensitive to the topology of the facing conformations which can improve the practical stability of the chosen system as a molecular switch.

关键词： carbon nanotube molecular switch non-equilibrium Green function density functional theory

钛酸铋钡陶瓷的介电性、铁电性及对晶格结构的依赖性

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物理学报 2004年第9期53卷 3200-3204页

作者：李正法钟维烈裘忠平葛洪良张沛霖王春雷中国计量学院应用物理系杭州310018 山东大学物理与微电子学院晶体材料国家重点实验室济南250100

采用溶胶凝胶工艺成功制备出BaBi4 Ti4 O1 5微细粉料 ,并利用此微粉烧结出成瓷良好的BaBi4 Ti4 O1 5陶瓷 .研究了BaBi4 Ti4 O1 5陶瓷的铁电顺电相变 ,测定了BaBi4 Ti4 O1 5的介电特性和饱和状态下的铁电特性 .所作测量表明BaBi4 Ti4 ... 详细信息

采用溶胶凝胶工艺成功制备出BaBi4 Ti4 O1 5微细粉料 ,并利用此微粉烧结出成瓷良好的BaBi4 Ti4 O1 5陶瓷 .研究了BaBi4 Ti4 O1 5陶瓷的铁电顺电相变 ,测定了BaBi4 Ti4 O1 5的介电特性和饱和状态下的铁电特性 .所作测量表明BaBi4 Ti4 O1 5可能是一种有序无序型弛豫铁电体 ,呈现一级弥散相变特征。

关键词：钛酸铋钡陶瓷铁电性介电性晶格结构溶胶-凝胶法

Geometric and Electronic Structure of Squaric Acid from DFT Calculation

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Journal of materials Science & Technology 2004年第2期20卷 206-208页

作者： Xuyan XUE, Chunlei WANG and Weilie ZHONGschool of physics and Microelectronics, state key laboratory of crystal materials, shandong university, jinan 250100, china shandong Univ Sch Phys & Microelect State Key Lab Crystal Mat Jinan 250100 Peoples R China

The crystal and electronic structure of antiferroelectric squaric acid is studied using density functional theory method, and the exchange correlation effects are treated by the generalized approximation. In order to understand the ferroelectricity of H2SQ in the molecular plane and the antiferroelectricity in whole crystal, the density of states, charge density distribution and band structure are calculated. The result showed that O2p and C2p play important roles in the interactions between layers. The hybridizations of 02s-Hls and 02p-Hls are responsible for the tendency to ferroelectricity within each layer.

关键词： Antiferroelectricity Electronic structure Squaric acid

Ground state and polaron and bipolaron excited states in polydiacetylene

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Science china(physics,Mechanics & Astronomy) 2006年第4期49卷 430-439页

作者： LI Yuan1, HU Guichao1, XIA Caijuan1, LIU Desheng1,2 & XIE Shijie1,2 1. school of physics and Microelectronics, shandong university, jinan 250100, china 2. National key laboratory of crystal materials, shandong university, jinan 250100, china 1. school of physics and Microelectronics Shandong University Jinan 250100 China 2. National key laboratory of crystal materials Shandong University Jinan 250100 China

The electronic properties of ground state and charged excited states of nondegenerate polydiacetylene were investigated by means of a tight-binding model. The parameters of the model were obtained by comparison of the experimental and other theoretical results. It was found that there is a stable dimerized structure of polydiacetylene in ground state and the doping induces the nonlinear excitations, such as polarons and bipolarons. In order to compare the stability of polaron and bipolaron, the creation energy and binding energy were separately defined. By neglecting the electron-electron Coulomb interaction, a bipolaron is more stable than two independent polarons.

关键词： dimerization, polaron, bipolaron, binding energy.

Lattice Effects and Irreversible Magnetoresistance in Gd Doped La-Ca-Mn-O

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Journal of materials Science & Technology 2002年第6期18卷 509-512页

作者： Baoxin HUANG, Yihua LIU, Ruzhen ZHANG, Chengjian WANG, Gang JI and Liangmo MEIDepartment of physics and state key laboratory of crystal materials, shandong university, jinan, 250100, china shandong Univ Dept Phys Jinan 250100 Peoples R China shandong Univ State Key Lab Crystal Mat Jinan 250100 Peoples R China

The Gd substituting effects for La in La0.67Ca0.33MnO3 has been studied. With increasing the substituting amount of Gd, the phase transition temperature of metal-isolator for the samples decreases, the corresponding peak resistivity increases, the Curie temperature decreases monotonically. The substitution of La-Ca-Mn-O with 11% Gd for La improved the magnetoresistance ratio by an order of magnitude. The effects of substituting Gd can be explained in terms of the lattice effects. An irreversible MR behaviour was observed in Gd-substituting compounds. This effect became marked when the substituting amount of Gd was greater than 7%. A maximum irreversible increment of MR ratio as large as 91% was obtained when Gd substituting amount was 11%.

关键词： Manganese perovskites Colossal magnetoresistance Lattice effect Irreversible magnetoresistance

Negative differential resistance in molecular devices: the role of molecule-electrode coupling

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Science china(physics,Mechanics & Astronomy) 2011年第8期Mechanics & Astronomy) .卷 1455-1460页

作者： ZHAI YaXin1, JI GuoMin1, FANG ChangFeng1, CUI Bin1, ZHAO Peng2 & LIU DeSheng1,3, 1 school of physics, state key laboratory of crystal materials, shandong university, jinan 250100, china 2 school of Science, university of jinan, jinan 250022, china 3 Department of physics and Information Engineering, Jining university, Qufu 273100, china 1. school of physics State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China2. School of Science University of Jinan Jinan 250022 China3. Department of Physics and Information Engineering Jining University Qufu 273100 China

By applying nonequilibrium Green's function formalism combined with the first-principles density functional theory, we investigate the electronic transport in two molecular junctions constituted by a substituted oligo (phenylene ehtynylene) sand-wiched between two Au electrodes. Our calculations show that the weak molecule-electrode coupling is responsible for the observation of the negative differential resistance (NDR) effect in experiments. When the coupling is weak, the projected density of states (PDOS) of the molecule and the electrodes undergoes a mismatch-match-mismatch procedure, which increases and then decreases the transmission peak intensities, leading to a NDR effect. We also find that the localization/delocalization of the molecular orbitals and the change of charge state of the molecule have no direct relation with the NDR effect, because they change little as the voltage increases.

关键词： negative differential resistance substituted oligo (phenylene ehtynylene) molecular junction density functional theory nonequilibrium Green’s function formalism

Large second-order optical nonlinearities of s-triazine derivatives: View from micro molecules to macro crystals

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Science china Chemistry 2005年第3期48卷 203-209页

作者： FANG Qi1, LEI Hong2, CUI Yuezhi3, HUANG Zhenli4, XUE Gang1 & YU Wentao1 1. state key laboratory of crystal materials, shandong university, jinan 250100, china 2. school of Information Science and Engineering, shandong university, jinan 250100, china 3. Department of Chemical Engineering, Light Industry College of shandong, jinan 250100, china 4. key laboratory of Biomedical Photonics, Ministry of Education, Huazhong university of Science and Technology, Wuhan 430074, china 1. state key laboratory of crystal materials Shandong University 250100 Jinan China 2. school of Information Science and Engineering Shandong University 250100 Jinan China 3. Department of Chemical Engineering Light Industry College of Shandong 250100 Jinan China 4. key laboratory of Biomedical Photonics Ministry of Education Huazhong University of Science and Technology 430074 Wuhan China

Three s-triazine derivatives have been synthesized and their structures been de-termined. These are Compound I: 2,4-dimethyl-6-(p-N,N-dimethylaminostyryl)-s-triazine (abbre-viated to NMe-1), Compound II: 2,4-dimethyl-6-(p-N,N-diethylaminostyryl)-s-triazine (to NEt-1), and Compound III: 2-methyl-4,6-bis(p-N,N-dimethylaminostyryl)-s-triazine (NMe-2). NMe-1 and NEt-1 molecules belong to the D-π-A type with a one-dimensional charge-transfer character. NMe-1 crystallizes to centrosymmetric P1 space group, while NEt-1 to non-centrosymmetric polar Cc space group with all of the molecular charge-transfer axes taking the same orientation. Under the irradiation of 1064 nm fundamental laser, NEt-1 powder crystals radiate a 2-order harmonic light with an intensity 46.8 times that of urea. The Λ typed NMe-2 molecule, which has a two-dimensional charge-transfer character, crystallizes to polar P21 space group. Its powder crystals exhibit a 2-order harmonic intensity 46.2 times that of urea. The quantum chemical cal-culations and tensor analyses have been carried out to reveal the dependence of the macro 2-order nonlinear optical (NLO) efficiency on the micro 2-order NLO coefficients (β) and on the crystalline packing styles.

关键词： s-triazine derivatives, synthesis, structure, SHG intensities of crystals, βvalues of molecules.

Size Determination of Ultramicropores and Small Mesopores Using a Calculation Procedure Based on the Tangents of Comparison Plot

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Journal of Wuhan university of Technology(materials Science) 2010年第3期25卷 391-394页

作者：邱芹刘世权 school of materials Science and Engineering University of Jinan

Pore size distribution（PSD） curves of synthesized hollow silica spheres with ultrmicropores and small mesopores were obtained from calculations based on the BJH,KJS,SF,MP,NLDFT models and ***＇s *** indicate that Zhu＇s method not only gives reasonable small mesopore size but also could be further extended to the ultramicropores region for the PSD evaluation.

关键词： pore size distribution comparison plot ultramicropores mesopores