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Analysis of the carbon source for diamond crystal growth

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Chinese science Bulletin 2008年第6期53卷 937-942页

作者： LI Li1.2, XU Bin2,3 & LI MuSen1.2 1.school of Materials {1. & Engineering, Shandong University, jinan 250061. china 2 Shandong Engineering Research Center for Super Hard Materials, Zoucheng 273500, china 3 school of Materials {1. & Engineering, Shandong Jianzhu University, jinan 2501.1. china school of Materials {1. & Engineering Shandong University Jinan China Shandong Engineering Research Center for Super Hard Materials Zoucheng China school of Materials {1. & Engineering Shandong Jianzhu University Jinan China

The lattice constants of diamond and graphite at high pressure and high temperature (HPHT) were calculated on the basis of linear expansion coefficient and elastic constant. According to the empirical electron theory of solids and molecules (EET), the valence electron structures (VESs) of diamond, graphite crystal and their common planes were calculated. The relationship between diamond and graphite structure was analyzed based on the boundary condition of the improved Thomas-Fermi-Dirac theory by Cheng (TFDC). It was found that the electron densities of common planes in graphite were not continuous with those of planes in diamond at the first order of approximation. The results show that during the course of diamond single crystal growth at HPHT with metal catalyst, the carbon sources forming diamond structure do not come from the graphite structure directly. The diamond growth mechanism was discussed from the viewpoint of valence electron structure.

关键词：钻石晶体生长石墨碳源价电子结构

Characterzation and separation of Al_(1.) species using gel-filtration chromatography

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science{1. Chemistry 2006年第4期49卷 326-331页

作者： CHU Yongbao1.2, GAO Baoyu1. YUE Qinyan1. WANG Yan1.& WANG Shuguang1.1. school of Environmental {1. and Engineering, Shandong University, jinan 2501.0, china 2. College of Material and Environment, Qingdao University of {1. and Technology, Qingdao 266042, china school of Environmental {1. and Engineering Shandong University Jinan China College of Material and Environment Qingdao University of Science and Technology Qingdao China

A polyaluminum chloride (PAC) sample was prepared using a slow alkalinetitration method. The Bio-Gel P-1.0 gel column chromatographic technique was used to separate andcharacterize the various forms of aluminum present in the prepared PAC solution. The effluents froma gel column were monitored using online chemical method: AI-Ferron timed complexationspectropho-tometry and by ^(27)Al nuclear magnetic resonance (NMR) spectroscopy. Effects ofdifferent experimental conditions such as eluent flow rate, ionic strength and pH on separation ofAl_(1.) were investigated. Experimental results indicated that molecule size exclusion was not theonly parameter affecting the column chromatographic separation efficiency of Al_(1.) but moleculecharge as well. Reducing the eluent flow rate, increasing the ionic strength and suitable pHresulted in increase in the separation efficiency. Experimental results clearly indicated that byvarying the experimental conditions, it is possible to produce pure Al_(1.) species using a gelcolumn chromatographic technique.

关键词： Al1. species, column chromatography, polyaluminum chloride (PAC), separation and purification.

The influence of laser pulse on the photoabsorption spectra of Li atom in strong external field

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science{1.(Physics,Mechanics & Astronomy) 2006年第2期49卷 178-186页

作者： WANG Dehua1.& LIN Shenglu2 1. school of Physics and Electronic Engineering, Yantai Normal University, Yantai 264025,{1. 2. Department of Physics, Shandong Normal University, jinan 25001.,{1. 1. school of Physics and Electronic Engineering Yantai Normal University Yantai 264025 China 2. Department of Physics Shandong Normal University Jinan 250014 China

Using the time-dependent perturbation theory and the calculation formula of the single- and double-pulse absorption spectra of the atom in strong external fields, we calculate the single- and double-pulse absorption spectra of Li atom in strong magnetic field for different pulse widths. The results show that a pulse of some width can reduce the contribution of the short period closed orbits and eliminate the contribution of the long period orbits. Compared with the single-pulse absorption spectra, we found that for some phase differences, the double-pulse laser absorption spectra are strengthened; while for others, they are reduced. Therefore, we can use the pulse laser to control the oscillation of the absorption spectra and obtain the optimization object.

关键词： laser pulse closed orbit absorption spectra.

Study on the cluster of floating dross before nucleating during hot-dipping process

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science{1. Chemistry 2005年第1期48卷 83-88页

作者： WEI Yunhe1. ZHANG Changqiao1. QIN Jingyu2 & LIU Chengbu1.1. school of Chemistry and Chemical Engineering, Shandong University, {1. 2501.0, china 2. The Key Laboratory of Liquid Structure and Heredity of Materials of Ministry of Education, Shandong University, {1. 250061. china 1. school of Chemistry and Chemical Engineering Shandong University 250100 Jinan China 2. The Key Laboratory of Liquid Structure and Heredity of Materials of Ministry of Education Shandong University 250061 Jinan China

During hot-dipping in molten Zn-55Al, the forming of “floating” dross is closely re- lated with the interaction between the Al and the Fe atoms. Utilizing the thita-thita X-ray diffraction and the Percus-Yevick hard sphere model, this paper investigates the structure of molten Al3Fe that is an approximant of partial melt in practical Zn-55Al alloy melt. It is found that in the melt there exist clusters that resemble the structure of intermetallic compound Al3Fe. The strong in- teraction between Al and Fe atoms is also indicated by the deficiency of the coordination number from 1. and the shrinkage of averaged atomic diameter. Based on such information, it is specu- lated that in the molten Zn-55Al, with the accumulation of Fe, Al3Fe-like clusters form with priority, then grow into dross. On the other hand, after deflating of the effective hard sphere diameter of pure Al atom and enlarging that of the pure Fe atom, the modified model can achieve reasonable fit to the experimental structure factor. Hard sphere modeling also gave a good estimation of the mass density 3.65 g/cm3 of liquid Al3Fe alloy at 1.50℃. Compared with the density of 3.7 g/cm3 of Zn-55Al, the reason for dross floating is satisfactorily understood.

关键词： hot-dipping, dross, Al3Fe alloy, molten structure, P-Y model.

Preparation and Microstructural Analysis of Ti_2AlC/TiAl(Nb) Composite

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Journal of Wuhan University of Technology(Materials science) 2007年第1期22卷 7-11页

作者：岳云龙 Shod of Materials science and Technology Jinan University

By using the spark plasma sintering process, Ti2AlC/TiAlcomposite with the addition of Niobium （Nb） was prepared in-situ and the microstructure of Ti2AlC/TiAl （Nb） composite was investigated by means of transmission electron microscopy （TEM） and high-resolution electron microscopy （HREM）. The results indicate that new-formed Ti2AIC particles disperse with a high degree of uniformity and well combine with the matrix. In the area of phase interface the d-spaces of Ti2AlC （1.0） and TiAI （1.0） were measured as 0.2648 nm and 0.2991.nm,respectively. The atom arrangement beside the interface was only partly corresponding, existing in semicoherent state. On the contrary, in the area of grain interface the d-spaces of TiAl （1.0） and TiAl （1.0） were measured as 0.2462 nm and 0.2631.nm,respectively and the atom arrangement beside the interface was almost corresponding, existing in coherent state.

关键词： Ti2AlC/TiAl CNb) composite interface semicoherent structure coherent structure

The Stamping Formability of AZ31.Magnesium Alloy Sheet Improved by Equal-channel Angular Pressing

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Journal of Wuhan University of Technology(Materials science) 2010年第2期25卷 234-237页

作者：刘英 Department of Material science and Engineering Jinan University

Equal channel angular pressing （ECAP） processing and annealing were applied to the AZ31.magnesium alloy sheets to evaluate the potential improvement in the mechanical properties and formability. The ECAP experiment was conducted at 300 ℃ in a die having an included angle of 90o between two channels by the BCZ route with the sheets rotated by 90°about the normal axis of plate plane. The tensile tests and conical cup tests were conducted at various temperatures from 20 to 250 ℃. The experimental results indicated that improving the working temperatures could lead to the soft in the material and the enhancement of ductility. Comparatively, the ECAPed AZ31.alloy sheets showed the lower yield strength and smaller conical cup value （CCV） than the unECAPed counterpart in the room temperature. The difference in yield strength between them became small in the elevated temperature, but the ECAPed samples still had the smaller CCV value, implying the improved formability. The texture of the AZ31.alloy sheets could be modified by ECAP and the decrease in the yield strength and more uniform deformation realized in the material, so the formability of AZ31.alloy sheets was improved.

关键词： AZ31.magnesium alloy sheets equal-channel angular pressing mechanical properties conical cup value (CCV)

Microstructure and hot compression behavior of twin-roll-casting AZ41. magnesium alloy

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Rare Metals 2010年第4期29卷 396-400页

作者： WANG Shouren WANG Min MA Ru WANG Yong WANG Yanjun school of Mechanical Engineering University of Jinan Jinan 250022 China school of Materials {1. and Engineering Shandong University Jinan 250022 China

The relationship of true stress and true strain of AZ41. magnesium alloy under twin-roll-cast （TRC） and hot compression was analyzed us- ing a Gleeble 1.00 machine. Microstructural evolutions of the TRC magnesium alloy under different deformation conditions （strain, sWain rate and deformation temperature） were examined using optical microscopy and discussed. The relationship of true stress and true sWain pre- dicted that lower deformation temperature and higher sWain rate caused sharp strain hardening. Meanwhile, the flow stress curve turned into a steady state at high temperature and lower strain rate. The intermediate temperature and strain rate （623 K and 0.01.s^-1. is appropriate.

关键词： magnesium alloy deformation behavior twin-roll-casting hot compression microstructural evolution

Synthesis and structural characterization of Zn_3N_2 powder

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science{1.(Physics,Mechanics & Astronomy) 2005年第2期48卷 201-210页

作者： ZONG Fujian1. MA Honglei1. XUE Chengshan2, ZHUANG Huizhao2, ZHANG Xijian1. MA Jin1. JI Feng1.& XIAO Hongdi1.1. school of Physics and Microelectronics, Shandong University, {1. 2501.0, china 2. Institute of Semiconductor, Shandong Normal University, {1. 25001., china school of Physics and Microelectronics Shandong University Jinan 250100 China Institute of Semiconductor Shandong Normal University Jinan 250014 China

Zinc nitride (Zn3N2) powder has been synthesized through the nitridation reaction of Zn powder with NH3 gas (at the flow rate of 500 ml/min) at the nitridation temperature of 600℃ for 1.0 min. X-ray diffraction (XRD) indicates that Zn3N2 is cubic in structure with the lattice constant being a = 0.9788 nm. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that Zn3N2 powder has surface morphology of various types. X-ray photoelectron spectroscopy (XPS) shows the differences in chemical bonding states between Zn3N2 and ZnO, and confirms the formation of N–Zn bonds. Observation through high resolution transmission electron microscopy (HRTEM) also indicates that the computer simulation of the structure of Zn3N2 is consistent with the structural model put forward by Partin.

关键词： nitridation, Zn3N2 powder, structure, XRD, SEM, TEM, HRTEM, XPS.

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

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science{1. 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 2501.0,{1. 2. school of Information science and Engineering, Shandong University, jinan 2501.0,{1. 3. Department of Chemical Engineering, Light Industry College of Shandong, jinan 2501.0,{1. 4. Key Laboratory of Biomedical Photonics, Ministry of Education, Huazhong University of science and Technology, Wuhan 430074,{1. 1. State Key Laboratory of Crystal Materials Shandong University 250100 Jinan China 2. school of Information {1. 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 1.64 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.