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Improvement of water resistance of long afterglow SrAl_2O_4: Dy, Eu phosphor by coating with SiO_2 film

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Rare Metals 2002年第2期21卷 152-155页

作者： ZHANG Junying, CHEN Qingming, LIN Yuanhua, and ZHANG Zhongtaistate key laboratory of new ceramics and fine processing, department of materials science and engineering, tsinghua university,beijing 100084, china department of materials science and engineering Tsinghua University State Key Laboratory of New Ceramics and Fine Processing 北京 100084

The long afterglow SrAl_2O_4: Dy, Eu phosphor is liable tohydrolyze in water with deterioration of the lumin- escent ***_2O_4: Dy, Eu phosphors were therefore heated at 60-90 deg. C inTEOS sol to form a surface gel and then heat-treated at 400 deg. C toobtain SiO_2 coated phosphors. Observation by ?Transmission ElectronMicroscope (TE) and X- ray photoelectron spectroscopy (XPS) showsthat a thin silica film forms on the surface of the phosphors. Thecoating procedure can be illustrated by a four-step process and thetransparent silica film can suppress the hydrolysis process, so thatthe luminescent properties of the phosphors are unimpaired or evenbetter.

关键词： phosphors coating luminescent materials SrAl_2O_4

Effect of Heat Treatment on High Temperature Stress Rupture Strength of Brazing Seam for Nickel-base Superalloy

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Journal of university of science and Technology beijing 2001年第2期8卷 123-125页

作者： Junying Zhang, Zhongtai Zhang, Jisheng Sun, Xiaofang Liu, Wei Tian (state key laboratory of new ceramics and fine processing, department of materials science and engineering, tsinghua university, beijing 100084, china) (beijing Institute of Aeronautical Tsing Hua Univ Dept Mat Sci & Engn State Key Lab New Ceram & Fine Proc Beijing 100084 Peoples R China Inst Aeronaut Mat Beijing 100095 Peoples R China Univ Sci & Technol beijing Mat Sci & Engn Sch Beijing 100083 Peoples R China

In order to enhance the high-temperature stress rupture strength of brazing seam by heat treatment, it was diffusion treated, then solution heat treated, and finally aging treated. The microstructure of brazing seam especially morphology of gamma ' phase and boride was observed and the strength of brazing seam was measured in this process. The results show that heat treatment can enhance high-temperature stress rupture strength by improving the microstructure of brazing seam. The strength of brazing seam after solution heat treatment decreases in comparison with that only after diffusion treatment while aging treatment after solution heat treatment increases the strength of brazing seam.

关键词： wide-gap brazing high temperature stress rupture strength microstructure nickel-base superalloy

A novel synthetic route for LiFePO_4/C cathode materials by addition of starch for lithium-ion batteries

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Chinese Chemical Letters 2007年第2期18卷 237-240页

作者： Shao Hua Luo, Zi Long Tang, Jun Biao Lu, Zhong Tai Zhang state key laboratory of new ceramics and fine processing, department of materials science and engineering, tsinghua university, beijing 100084, china Graduate School at Shenzhen, tsinghua university, Shenzhen 518055, china [a]state key laboratory of new ceramics and fine processing Department of Materials Science and Engineering Tsinghua University Beijing 100084 China [b]Graduate School at Shenzhen Tsinghua University Shenzhen 518055 China

LiFePO4/Carbon composite cathode material was prepared using starch as carbon source by spray-pelleting and subsequent pyrolysis in N2. The samples were characterized by XRD, SEM, Raman, and their electrochemical performance was investigated in terms of cycling behavior. There has a special micro-morphology via the process, which is favorable to electrochemical properties. The discharge capacity of the LiFePO4.C composite was 170 mAh g-1, equal to the theoretical specific capacity at 0.1 C rate. At 4 C current density, the specific capacity was about 80 mAh g-1, which can satisfy for transportation applications if having a more flat discharge flat.

关键词： Lithium-ion batteries Cathode material Carbon coated LiFePO4 Spray-pelleting

EffectofEr^(3+) and Nd^(3+)doping on the luminescent properties of BaMgAl_(10)O_(17):Euphosphor

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Rare Metals 2003年第1期22卷 60-63页

作者： ZHANGLin ZHANGJunying ZHANGZhongtai CenterformaterialsPhysiceandChentistry SchoolofSciencesBeiHangUniversityBeijing100083China PersonnelDivision UniversityofSciehceandTechnologyBeijingBeijing100083China statekeylaboratoryofnewCeram

BaMgAl_(10)O_(17):Eu blue phosphors were synthesized and the effect of dopingE^(3+) and Nd^(3+) ions in the phosphor on the luminescent properties was investigated. When thecontent of Er^(3+) and Nd^(3+) ions is small, the phosphor remains single phase and the luminescentintensity of Eu^(2+) increases effectively. When Er^(3+) is doped, the shape of the excitationspectrum of the phosphor in the UV (ultraviolet) region remains unchanged. As Nd^(3+) is doped inthe phosphor, the location and intensity of the two excitation peaks, and the emission intensityratio excited by corresponding UV change dramatically owing to the alternation of crystal fieldsplitting and level barycenter of 4f^6 5d configuration of Eu^(2+) ion.

关键词： phosphor spectrum luminescent property

Multiparty quantum secret sharing of classical and quantum messages

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Progress in Natural science:materials International 2007年第1期17卷 26-31页

作者： CHEN Pan, DENG Fuguo and LONG Guilu ( key laboratory for Quantum Information and Measurements, and department of Physics, tsinghua university, beijing 100084, china key laboratory of Beam Technology and material Modification, MOE, Institute of Low Energy Nuclear Physics, and department of material science and engineering, beijing Normal university, beijing 100875, china beijing Radiation Center, beijing 100875, china key laboratory for Atomic and Molecular Nano-sciences, tsinghua university, beijing 100084, china) [a]key laboratory for Quantum Information and Measurements and Department of Physics Tsinghua University Beijing China [b]key laboratory of Beam Technology and material Modification MOE Institute of Low Energy Nuclear Physics and Department of Material Science and Engineering Beijing Normal University Beijing China [c]beijing Radiation Center Beijing China [d]key laboratory for Atomic and Molecular Nano-sciences Tsinghua University Beijing China

A scheme for multiparty quantum secret sharing of classical and quantum messages is proposed by using entanglement swapping. This scheme can distribute not only the classical information but also the quantum informati... 详细信息

关键词： quantum secret sharing classical message quantum message EPR pair.

Preparation and thermal stability of zirconia-doped mullite fibers via sol-gel method

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Progress in Natural science:materials International 2011年第2期21卷 117-121页

作者： Wei WANG~(1,2),Duan WENG~1,Xiao-dong WU~1 1.state key laboratory of new ceramics & fine Process,department of materials science and engineering, tsinghua university,beijing 100084,china 2.The Second Artillery NCO Academy of PLA,Qingzhou,Shandong 262500,china [a] state key laboratory of new ceramics & fine Process Department of Materials Science and Engineering Tsinghua University Beijing 100084 China [b] The Second Artillery NCO Academy of PLA Qingzhou Shandong 262500 China

The zirconia-doped mullite fibers were prepared via a sol-gel method from aluminum isopropoxide-aluminum nitrate-tetraethyl orthosilicate *** effects of zirconia doping on the sol spinnability,mullitization,structure and thermal stability of mullite fibers were investigated by means of Fourier transform infrared（FT-IR） spectroscopy,scanning electron microscopy（SEM） and X-ray diffraction（XRD）.The results showed that Zr—O—C bond was presented with the involvement of zirconium acetate,which accelerated the gelation process of the precursor *** mullitization process of the doped fibers was promoted by the formation of less middle-phase residues such as *** the samples investigated,the 1%ZrO2-doped fibers exhibited the highest thermal stability with a grain growth rate of 11%（from 1 000℃to 1300℃）,which is only a half of that for pure mullite fibers.

关键词： mullite fiber zirconia doping thermal stability

Ultralight X-type lattice sandwich structure (Ⅱ):Micromechanics modeling and finite element analysis

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science china(Technological sciences) 2009年第9期52卷 2670-2680页

作者： ZHANG QianCheng1,CHEN AiPing 2,CHEN ChangQing2,3 & LU TianJian2 1 state key laboratory for Mechanical Behavior of materials,School of material science and engineering,Xi’an Jiaotong university,Xi’an 710049,china 2 MOE key laboratory for Strength and Vibration,School of Aerospace,Xi’an Jiaotong university,Xi’an 710049,china 3 department of engineering Mechanics,AML,tsinghua university,beijing 100084,china state key laboratory for Mechanical Behavior of materials School of Material Science and Engineering Xi’an Jiaotong University Xi’an China MOE key laboratory for Strength and Vibration School of Aerospace Xi’an Jiaotong University Xi’an China department of engineering Mechanics AML Tsinghua University Beijing China

The methods of homogenization and finite elements are employed to predict the effective elastic constants and stress-strain responses of a new type of lattice structure,the X-structure proposed by the authors in a companion paper. It is shown that in most cases the predictions by the equivalent homogenization theory agree well with the experimental and 3-dimensional finite element calculated results. The theoretical and numerical study supports the argument that the X-structure is superior to the pyramid lattice structure in terms of mechanical strength.

关键词： sandwich panel lattice structure equivalent homogenization finite element model

A Study on the Wear Resistance of Nano-material/E51

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Journal of materials science & Technology 2004年第3期20卷 340-343页

作者： Yan GAO Zhenjia WANG Quanyu MA Ge TANG Ji LIANG state key laboratory of Tribology, department of Mechanical engineering, tsinghua university, beijing 100084, china Lab. of Tribology Dept. of Mech. Eng. Tsinghua Univ. Beijing 100084 China

Epoxy resin modified by nanometric γ-alumina or multi-walled carbon nanotubes (MCNTs) was prepared with solution mixingmethod, and the wear resistance of the composite was studied. The results show that when an optimum amount of nanometricalumina or MCNTs is filled in epikote51 (E51), the wear resistance of the composite will increase. When 8 wt pct nanometricγ-alumina is filled in E51, the wear resistance of the composite increases to 230%. When 10% MCNTs is filled in E51, thewear resistance of the composite increases to 226%. When nanometric alumina is filled in, the wear resistance of modifiedepikote51 will increase as the cure temperature is heightened.

关键词： Epoxy resin Nanometric γ-alumina Multi-walled carbon nanotubes (MCNTs) Wear resistance

Sediment pollution and its effect on fish through food chain in the Yangtze River

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International Journal of Sediment Research 2008年第4期23卷 338-347页

Suspended sediment adsorbs pollutants from flowing water in rivers and deposits onto the bed. However, the pollutants accumulated in the river bed sediment may affect the bio-community through food chain for a long period of time. To study the problem the concentration of heavy metals (Cr, Cd, Hg, Cu, Fe, Zn, Pb and As) in water, sediment, and fish/invertebrate were investigated in the middle and lower reaches of the Yangtze River during 2006-2007. The concentrations of heavy metals were 100-10,000 times higher in the sediment than in the water. Benthic invertebrates had relatively high concentrations of heavy metals in their tissues due to their proximity to contaminated sediments. Benthic invertivore fish had moderately high concentrations of heavy metals whereas phytoplanktivore fish, such as the silver carp, accumulated the lowest concentration of heavy metals. The concentrations of Cu, Zn, and Fe were higher than Hg, Pb, Cd, Cr, and As in the tissue samples. The concentration of heavy metals was lower in the river sediments than in the lake sediments. Conversely, the concentration of heavy metals was higher in river water than in lake water. While a pollution event into a water body is often transitory, the effects of the pollutants may be long-lived due to their tendency to be absorbed in the sediments and then released into the food chain. The heavy metals were concentrated in the following order: bottom material > demersal fish and benthic fauna > middle-lower layer fish > upper-middle layer fish > water.

关键词： Sediment pollution Heavy metal Fish Invertebrate Yangtze River