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Sample records for ce lummus cffc process

  1. Comment on "138La-138Ce-136Ce nuclear cosmochronometer of the supernova neutrino process"

    CERN Document Server

    Von Neumann-Cosel, P; Byelikov, A

    2009-01-01

    The nuclear chosmochronometer suggested by Hayakawa et al. [Phys. Rev.C 77, 065802 (2008)] based on the 138La-138Ce-136Ce abundance ratio in presolar grains would be affected by the existence of a hitherto unknown low-energy 1+ state in 138La. Results of a recent high-resolution study of the 138Ba(3He,t) reaction under kinematics selectively populating 1+ states in 138La through Gamow-Teller transitions provides strong evidence against the existence of such a hypothetical state.

  2. Synthesis of CeO2/fly ash cenospheres composites as novel photocatalysts by modified pyrolysis process

    Institute of Scientific and Technical Information of China (English)

    张进; 王冰; 崔皓; 李闯; 翟建平; 李琴

    2014-01-01

    A novel fly ash cenospheres (FACs)-supported CeO2 composite (CeO2/FACs) was successfully synthesized by the modi-fied pyrolysis process. The prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and diffuse reflection spectra (DRS) techniques. XRD results indicated that the CeO2 film coated on cenospheres was a face-centered cubic structure. SEM images confirmed that the CeO2 film was relatively com-pact. XPS results showed that Ce was present as both Ce4+and Ce3+oxidation states in CeO2 film coated on FACs substrate. The bandgap of the composite was narrower compared with the pure CeO2. The as-prepared material exhibited good photocatalytic activ-ity for the decolorization of methylene blue (MB) under visible light irradiation, and the first-order reaction rate constant (k) of 0.0028 min–1 for CeO2/FACs composite was higher than 0.0015 min–1 of pure CeO2. The fact that they floated on water meant that CeO2/FACs composites were easily recovered from water by filtration after the reaction. The recycling test revealed that the compos-ites were quite stable during the MB photocatalytic decolorization. The CeO2/FACs catalyst was therefore promising for practical use in the degradation of pollutants or water cleanup.

  3. Target characterization for the 130Ba(alpha,gamma)134Ce gamma-process experiment

    CERN Document Server

    Gyürky, Gy; Farkas, J; Fülöp, Zs; Somorjai, E; Szücs, T

    2011-01-01

    In order to extend the available experimental database for the astrophysical gamma-process, the cross section measurement of the 130Ba(alpha,gamma)134Ce and 130Ba(alpha,n)133Ce reactions is in progress. The measurements are carried out using thin layers of evaporated BaCO3 as target. Since the target thickness enters directly into the calculation of the cross sections, the reliability of its determination is of crucial importance. Three different methods have been used to determine the target thickness. Details of these experiments and the obtained results are presented.

  4. The impact of the new quality management system standards on the CE-marking process.

    Science.gov (United States)

    Donawa, M

    2001-01-01

    In December 2000, the new ISO 9000 quality management system series of standards was published. This represents a significant development for manufacturers marketing medical devices in Europe, who use these standards to demonstrate conformity to the European medical device Directives. This article discusses some issues related to the introduction of these standards in Europe and their use in the CE-marking process.

  5. Electrochemical formation process and phase control of Mg-Li-Ce alloys in molten chlorides

    Institute of Scientific and Technical Information of China (English)

    ZHANG Meng; HAN Wei; ZHANG Milin; ZHU Fengyan; XUE Yun; ZHANG Zhijian

    2013-01-01

    An electrochemical approach for the preparation of Mg-Li-Ce alloys by co-reduction of Mg,Li and Ce on a molybdenum electrode in KCl-LiCl-MgCl2-CeCl3 melts at 873 K was investigated.Cyclic voltammograms (CVs) and square wave voltammograms indicated that the underpotential deposition (UPD) of cerium on pre-deposited magnesium led to the formation of Mg-Ce alloys at electrode potentials around-1.87 V.The order of electrode reactions was as follows:discharge of Mg(Ⅱ) to Mg-metal,UPD of Ce on the surface of pre-deposited Mg with formation of Mg-Ce alloys,discharge of Ce(Ⅲ) to Ce-metal and after that the discharge of Li+ with the deposition of Mg-Li-Ce alloys,which was investigated by CVs,chronoamperometry,chronopotentiometry and open circuit chronopotentiometry.X-ray diffraction (XRD) illuminated that Mg-Li-Ce alloys with different phases were obtained via galvanostatic electrolysis by different current densities.The microstructures of Mg-Li-Ce alloys were characterized by optical microscopy (OM) and scanning electron microscopy (SEM),respectively.The analysis of energy dispersive spectrometry (EDS) showed that Ce existed at grain boundaries to restrain the grain growth.The compositions and the average grain sizes of Mg-Li-Ce alloys could be obtained controllably corresponding with the phase structures of the XRD patterns.

  6. MnO2/CeO2 for catalytic ultrasonic decolorization of methyl orange: Process parameters and mechanisms.

    Science.gov (United States)

    Zhao, He; Zhang, Guangming; Chong, Shan; Zhang, Nan; Liu, Yucai

    2015-11-01

    MnO2/CeO2 catalyst was prepared and characterized by means of Brunauer-Emmet-Teller (BET) method, X-ray diffraction (XRD) and scanning electron microscope (SEM). The characterization showed that MnO2/CeO2 had big specific surface area and MnO2 was dispersed homogeneously on the surface of CeO2. Excellent degradation efficiency of methyl orange was achieved by MnO2/CeO2 catalytic ultrasonic process. Operating parameters were studied and optimized. The optimal conditions were 10 min of ultrasonic irradiation, 1.0 g/L of catalyst dose, 2.6 of pH value and 1.3 W/ml of ultrasonic density. Under the optimal conditions, nearly 90% of methyl orange was removed. The mechanism of methyl orange degradation was further studied. The decolorization mechanism in the ultrasound-MnO2/CeO2 system was quite different with that in the ultrasound-MnO2 system. Effects of manganese and cerium in catalytic ultrasonic process were clarified. Manganese ions in solution contributed to generating hydroxyl free radical. MnO2/CeO2 catalyst strengthened the oxidation ability of ultrasound and realized complete decolorization of methyl orange.

  7. 固体透氧膜法直接还原NiO-CeO_2制备CeNi_5合金%DIRECT ELECTROCHEMICAL REDUCTION OF Nio-CeO_2 POWDER FOR PREPARATION OF CeNi_5 ALLOY BY SOLID-OXYGEN-ION CONDUCTING MEMBRANE PROCESS

    Institute of Scientific and Technical Information of China (English)

    赵炳建; 鲁雄刚; 李重河; 钟庆东

    2009-01-01

    Ce-Ni base alloy CeNi_5 is often used as the hydrogen storage alloy in Ni-H batteries. Its application is more or less limited by the high cost in the traditional preparing process. Therefore, lots of researchers have paid more attention to develop a novel process with high production efficiency and low cost. The goal of the present research was to demonstrate the technical viability of a new process (solid-oxygen-ion conducting membrane process, I.e., SOM process) for the production of CeNi_5 alloy directly from its oxide precursors. This process was improved on the basis of FFC process (Fray-Farthing-Chen Cambridge process): (1) the preparation of cathode was the same as that in FFC process, (2) Cu (or Sn) liquid saturated with carbon was used as anode separated from the melt by a yttria-stabilized zirconia tube in which only oxygen-ion was permeated to prevent the side reactions and decomposition of molten salts taking place until a voltage as high as 3.5 V. This paper was focused on the preparation of hydrogen storage alloy CeNi_5 by SOM process, some parameters such as molten salt temperature, electrolytic time, configurations and phase compositions of products were investigated. The results show that NiO-CeO_2 pellets can be completely reduced to CeNi_5 alloy by SOM process. The analysis of phase compositions of intermediate products indicates that the reduction of NiO-CeO_2 starts from NiO, it reduces firstly into Ni, then reacts with newly-formed CeOCl and finally forms CeNi_5. The comparison of FFC and SOM processes shows that for SOM, NiO-CeO_2 pellet (2.5 g) can be completely reduced to CeNi_5 after electrolyzed for 3 h, and the current efficiency is 75.5%, the electrolysis energy consumption is only as low as 4.03 kW·h/kg; while for FFC, it takes 12 h for the same pellet to be reduced to pure CeNi_5, and the current efficiency is 26.1% but the electrolysis energy consumption is 10.27 kW·h/kg. It could be concluded that SOM process has a bright future

  8. The data processing and analysis for the CE-5T1 GNSS experiment

    Science.gov (United States)

    Liu, Huicui; Cao, Jianfeng; Cheng, Xiao; Peng, Jing; Tang, Geshi

    2017-02-01

    In this paper the performance of a high sensitivity GPS/GLONASS receiver mounted on CE-5T1 Service Module is studied and the data received on the first Earth-lunar transfer orbit is processed and analyzed. At least four GLONASS satellites are visible for 46% of the data span while for 98% of the data span at least four GPS satellites are visible. GLONASS serves as a necessary supplement to GPS in real time positioning whenever less than four GPS satellites are tracked, and helps to optimize the observation geometry by reducing the Position Dilution of Precision (PDOP) values by up to 77%. However, noisier GLONASS pseudorange data should be properly weighted in order not to deteriorate the positioning accuracy. Studies indicate that when the inverse square of the pseudorange measurement error of each satellite is applied as the weight value, single point positioning (SPP) accuracy improves from 57.7 m (RMS) with GPS data alone to 44.6 m (RMS) with the addition of GLONASS data. Transmitter antenna Equivalent Isotropic Radiated Power (EIRP)s of all the four blocks of GPS satellites as well as GLONASS satellites are derived from the received C/N0 data and show significant variance in sidelobe power patterns. In general, the EIRP patterns of GPS Block IIR-M and GLONASS satellite antennas have a comparatively flat power level of around 10 dB W within the off-boresight angle range of 30-80° and roll off at the off-boresight angle of about 80°, offering deep space applications greater benefits than the other three blocks of GPS satellites. In addition, an interesting close encounter happens between CE-5T1 spacecraft and GLONASS satellite R06. Investigations indicate that the PDOP value increases up to 1.4 times and the SPP accuracy deteriorates by more than 142% if satellite R06 is excluded in the positioning computation.

  9. Growth of LaBr_3:Ce~(3+) Single Crystal by Vertical Bridgman Process in Nonvacuum Atmosphere

    Institute of Scientific and Technical Information of China (English)

    Hongbing Chen; Changyong Zhou; Peizhi Yang; Jinhao Wang

    2009-01-01

    The growth of LaBr_3:Ce~(3+) crystal by the vertical Bridgman process in a nonvacuum atmosphere was reported. According to the dehydration procedure of LaBr_3·7H_2O and CeBr_3·7H_2O investigated by differential thermal analysis/thermogravimetry (DTA/TG), anhydrous LaBr_3 and CeBr_3 were prepared by heating LaBr_3·7H_2O and CeBr_3·7H_2O at 240-260℃ for 5-6 h in dried HBr atmosphere. Using the feed materials prepared from the anhydrous lanthanon bromides, a 0.5 mole fraction Ce~(3+) doped LaBr_3 crystal with size ofφ25 mm×50 mm had been grown by vertical Bridgman process successfully. By sealing the feed material in a platinum crucible, the crystal could be grown in a nonvacuum atmosphere as the oxidization and volatilization of the melt could be avoided. The crystal was grown with the optimum conditions such as a growth rate of 0.5-1.0 mm/h and a temperature gradient of around 30℃/cm across solid-liquid interface under a furnace temperature of 850-880℃. The crystal was characterized by DTA/TG, X-ray diffraction (XRD), optical transmission, photoluminescence and X-ray stimulated luminescence measurement. The Bridgman process was confirmed to be promising for growing transparent LaBr_3:Ce~(3+) crystal with high optical quality.

  10. Preparation of Well Dispersed and Ultra-Fine Ce(Zr)O2 Mixed Oxide by Mechanochemical Processing

    Institute of Scientific and Technical Information of China (English)

    程昌明; 李永绣; 周雪珍; 陈伟凡

    2004-01-01

    Ultra-fine CeO2-ZrO2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce2(CO3)3·8H2O, ZrOCl2·xH2O and ammonia were used as reactants. It is found that the crystalline Ce2(CO3)3·8H2O and ZrOCl2·xH2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce0.15Zr0.85O2 mixed oxide with pure tetragonal phase structure and medium particle size(D50)less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.

  11. Catalytic oxidation with Al-Ce-Fe-PILC as a post-treatment system for coffee wet processing wastewater.

    Science.gov (United States)

    Sanabria, Nancy R; Peralta, Yury M; Montañez, Mardelly K; Rodríguez-Valencia, Nelson; Molina, Rafael; Moreno, Sonia

    2012-01-01

    The effluent from the anaerobic biological treatment of coffee wet processing wastewater (CWPW) contains a non-biodegradable compound that must be treated before it is discharged into a water source. In this paper, the wet hydrogen peroxide catalytic oxidation (WHPCO) process using Al-Ce-Fe-PILC catalysts was researched as a post-treatment system for CWPW and tested in a semi-batch reactor at atmospheric pressure and 25 °C. The Al-Ce-Fe-PILC achieved a high conversion rate of total phenolic compounds (70%) and mineralization to CO(2) (50%) after 5 h reaction time. The chemical oxygen demand (COD) of coffee processing wastewater after wet hydrogen peroxide catalytic oxidation was reduced in 66%. The combination of the two treatment methods, biological (developed by Cenicafé) and catalytic oxidation with Al-Ce-Fe-PILC, achieved a 97% reduction of COD in CWPW. Therefore, the WHPCO using Al-Ce-Fe-PILC catalysts is a viable alternative for the post-treatment of coffee processing wastewater.

  12. In-situ transmission electron microscopy study of oxygen vacancy ordering and dislocation annihilation in undoped and Sm-doped CeO2 ceramics during redox processes

    Science.gov (United States)

    Ding, Yong; Chen, Yu; Pradel, Ken C.; Liu, Meilin; Lin Wang, Zhong

    2016-12-01

    Ceria (CeO2) based ceramics have been widely used for many applications due to their unique ionic, electronic, and catalytic properties. Here, we report our findings in investigating into the redox processes of undoped and Sm-doped CeO2 ceramics stimulated by high-energy electron beam irradiation within a transmission electron microscope (TEM). The reduced structure with oxygen vacancy ordering has been identified as the CeO1.68 (C-Ce2O3+δ) phase via high-resolution TEM. The reduction of Ce4+ to Ce3+ has been monitored by electron energy-loss spectroscopy. The decreased electronic conductivity of the Sm-doped CeO2 (Sm0.2Ce0.8O1.9, SDC) is revealed by electron holography, as positive electrostatic charges accumulated at the surfaces of SDC grains under electron beam irradiation, but not at CeO2 grains. The formation of the reduced CeO1.68 domains corresponds to lattice expansion compared to the CeO2 matrix. Therefore, the growth of CeO1.68 nuclei builds up strain inside the matrix, causing annihilation of dislocations inside the grains. By using in-situ high-resolution TEM and a fast OneView camera recording system, we investigated dislocation motion inside both CeO2 and SDC grains under electron beam irradiation. The dislocations prefer to dissociate into Shockley partials bounded by stacking faults. Then, the partials can easily glide in the {111} planes to reach the grain surfaces. Even the Lomer-Cottrell lock can be swept away by the phase change induced strain field. Our results revealed the high mobility of dislocations inside CeO2 and SDC grains during their respective redox processes.

  13. Removal of sulfamethazine antibiotics using CeFe-graphene nanocomposite as catalyst by Fenton-like process.

    Science.gov (United States)

    Wan, Zhong; Hu, Jun; Wang, Jianlong

    2016-11-01

    The presence of sulfonamide (SMT) antibiotics in aquatic environments has received increasing attention in recent years, and they are ubiquitous pollutants which cannot be effectively removed by conventional wastewater treatment processes. In this paper, the nanocomposites Ce(0)/Fe(0)-reduced graphene oxide (Ce(0)/Fe(0)-RGO) were synthesized through chemical reduction method, and characterized by Raman and FTIR before and after use. The addition of RGO can prevent the agglomeration of Ce(0) and Fe(0). The elimination of SMT can be divided into adsorption and degradation process. The adsorption of SMT onto the catalyst can enhance its degradation. The effect of pH value, concentration of H2O2, catalyst dosage, temperature and initial SMT concentration on the removal efficiency of SMT was determined. When pH = 7, T = 25 °C, H2O2 = 8 mM, Ce(0)/Fe(0)-RGO = 0.5 g/L, SMT = 20 mg/L, the removal efficiency of SMT and TOC was 99% and 73%, respectively. The stability of the catalysts was evaluated with repeated batch experiments using ethanol, water and acid as solvents to wash the used catalysts, respectively. The surface change of the catalysts after each use was characterized by Raman and FTIR analysis. The intermediates were detected by GC-MS and IC, the possible degradation pathway of SMT was tentatively proposed.

  14. Treatment on Methyl Orange-Containing Simulation Wastewater by Ce3+ Ion Homogenous Electro-Catalytic Degradation Process%Ce3+电催化降解甲基橙模拟废水的研究

    Institute of Scientific and Technical Information of China (English)

    刘咏; 邹文慧; 廖洋; 操飞; 赵仕林

    2011-01-01

    Experiment of electro-catalytic degradation for treatment of wastewater containing methyl orange was carried out with Ce3 + as catalyst. The kinetics of electro-catalytic degradation wastewater in the Ce3+ system was investigated. In order to probe the decoloring mechanism of Ce3+ to the electro-catalytic degradation of methyl orange, a diaphragmless cell and a diaphragm cell were both filled with the wastewater respectively, and then electrolyzed in different conditions (concluding the dosing method, dosing position of Ce3+ and stirring mode). The changes of cerium concentration, methyl orange concentration, the chemical oxygen demand (COD), and UV-vis spectral in the electrolysis process were determined and analyzed. The results showed that the degradation of methyl orange in the Ce3 + system accorded with firstorder kinetics. The electro-catalytic degradation reaction of Ce3+ to the decolorization of methyl orange mainly happened in the cathode. The Ce3+ in wastewater mainly reduced H2O2 to ·OH, which had strong oxidizability, and could attack the azo bonds in the methyl orange and oxidize Ce3 + to Ce4+. Then the Ce4+ , complexed with the chromophore of methyl orange, was resulting in the blue shift of its absorption peaks to achieve the decolourization.%对添加Ce3+的甲基橙模拟废水进行了电催化处理实验,考察了Ce3+电催化降解甲基橙的反应动力学;为探讨Ce3+电催化降解甲基橙的脱色机理,将废水分别置入有隔膜和无隔膜电解槽中,在不同的条件(Ce3+的投加方式、位置和搅拌方式)下进行电解,测定分析了废水在电解过程中铈含量、甲基橙浓度、COD及体系紫外-可见吸收光谱图的变化.实验结果表明,Ce3+对甲基橙的电催化反应符合一级反应动力学;Ce3+对甲基橙脱色的电催化反应主要发生在阴极;加入废水中的Ce3+主要是通过将电解生成的H2O2还原为具有强氧化性的·OH进攻甲基橙分子中的偶氮键和Ce3+氧化生成的Ce

  15. A New Combustion Process for Nanosized BaCe0.95Y0.05O3-δ Powders

    Institute of Scientific and Technical Information of China (English)

    孟波; 谭小耀; 张宝砚; 杨乃涛

    2004-01-01

    Nanosized BaCe0.95Y0.05O3-δ powders with the homogeneous composition were synthesized by a new combustion process based on the Pechini method.A polymeric precursor sol was formed by use of citric acid and ethylene glycol as the chelating agents of metal ions.The perovskite-type BaCe0.95Y0.05O3-δ powders with uniform shape and smaller than 40 nm in sized were obtained through the combustion of the polymeric precursor sol at the existence of nitric acid and ammonium hydroxide.It was found the particle size could be controlled by modulating the quantities of nitric acid and ammonium hydroxide,the quantities of the residue,carbonate ions were also affected by the quantities of the citric acid and ethylene glycol.

  16. Two-stage coal liquefaction process materials from the Wilsonville Facility operated in the nonintegrated and integrated modes: chemical analyses and biological testing

    Energy Technology Data Exchange (ETDEWEB)

    Later, D.W.

    1985-01-01

    This document reports the results from chemical analyses and biological testing of process materials sampled during operation of the Wilsonville Advanced Coal Liquefaction Research and Development Facility (Wilsonville, Alabama) in both the noncoupled or nonintegrated (NTSL Run 241) and coupled or integrated (ITSL Run 242) two-stage liquefaction operating modes. Mutagenicity and carcinogenicity assays were conducted in conjunction with chromatographic and mass spectrometric analyses to provide detailed, comparative chemical and biological assessments of several NTSL and ITSL process materials. In general, the NTSL process materials were biologically more active and chemically more refractory than analogous ITSL process materials. To provide perspective, the NTSL and ITSL results are compared with those from similar testing and analyses of other direct coal liquefaction materials from the solvent refined coal (SRC) I, SRC II and EDS processes. Comparisons are also made between two-stage coal liquefaction materials from the Wilsonville pilot plant and the C.E. Lummus PDU-ITSL Facility in an effort to assess scale-up effects in these two similar processes. 36 references, 26 figures, 37 tables.

  17. An ion-imprinted polymer supported by attapulgite with a chitosan incorporated sol-gel process for selective separation of Ce(Ⅲ)

    Institute of Scientific and Technical Information of China (English)

    Chun Xiang Li; Jian Ming Pan; Jie Gao; Yong Sheng Yan; Gan Qing Zhao

    2009-01-01

    The surface ion-imprinting concept and chitosan incorporated sol-gel process were applied to the synthesis of a new attapulgite-supported polymer for selective separation of Ce(Ⅲ) from aqueous solution. The imprinting mechanism of prepared ion-imprinted polymer were discussed with the Characteristics of FT-IR and SEM. Results from the experiments of adsorption capacity and selectivity suggested that ion-imprinted polymer offered a fast kinetics for the adsorption of Ce(Ⅲ) under the optimum conditions. Its maximum adsorption capacity was 38.02 mg/g, and the selective recognition towards Ce(Ⅲ) was much higher than that of the non-imprinted polymer and attapulgite. The prepared functional polymer was shown to be promising for selective separation and enrichment of trace Ce(Ⅲ) in environmental samples.

  18. Preparation and characteristics of nano-crystalline Cu-Ce-Zr-O composite oxides via a green route: supercritical anti-solvent process

    Institute of Scientific and Technical Information of China (English)

    KUANG Li; HUANG Pan; SUN Huanhua; JIANG Haoxi; ZHANG Minhua

    2013-01-01

    The nano-crystalline Cu-Ce-Zr-O composite oxides were successfully prepared by the supercritical anti-solvent (SAS) process.The physicochemical properties and catalytic performances were investigated by X-ray diffraction (XRD),Raman spectroscopy,H2 temperature-programmed reduction (H2-TPR),oxygen storage capacity (OSC) measurement and catalytic activity evaluation.It was found that Cu2+ ions incorporated into CeO2-ZrO2 lattice to forn Cu-Ce-Zr-O solid solution associated with the formation of oxygen vacancies.The Cu-Ce-Zr-O catalysts prepared via the SAS process with the Cu content 2.63 mol.% showed the highest OSC index of 636.9 μmol/g.Compared with the samples prepared by impregnation method,Cu doping using SAS process could improve the dispersion of Cu2+ in the composite oxide,enhance the interaction between Cu2+ and CeO2-ZrO2,improve the reducibility of catalyst,and thus improve the OSC performance and increase the catalytic activity for CO oxidation at low temperature.

  19. Chlorination and Dissolution Process of CeO2 in Molten Salt

    Institute of Scientific and Technical Information of China (English)

    MENG; Zhao-kai; LIN; Ru-shan; CHEN; Hui; ZHANG; Kai; JIA; Yan-hong; WANG; Chang-shui; SONG; Peng; HE; Hui

    2015-01-01

    Molten salt electrolysis is considered as a promising technology in pyrochemical process in recent years.In the pyrochemical process of oxides fuel,dissolution of the oxides is a significant issue for study.Oxides cannot be reduced,as the solubility is small in molten salt.The chlorination of oxides can improve the solubility

  20. Modeling of a CeO2 thermochemistry reduction process for hydrogen production by solar concentrated energy

    Science.gov (United States)

    Valle-Hernández, Julio; Romero-Paredes, Hernando; Arancibia-Bulnes, Camilo A.; Villafan-Vidales, Heidi I.; Espinosa-Paredes, Gilberto

    2016-05-01

    In this paper the simulation of the thermal reduction for hydrogen production through the decomposition of cerium oxide is presented. The thermochemical cycle for hydrogen production consists of the endothermic reduction of CeO2 at high temperature, where concentrated solar energy is used as a source of heat; and of the subsequent steam hydrolysis of the resulting cerium oxide to produce hydrogen. For the thermochemical process, a solar reactor prototype is proposed; consisting of a cubic receptacle made of graphite fiber thermally insulated. Inside the reactor a pyramidal arrangement with nine tungsten pipes is housed. The pyramidal arrangement is made respect to the focal point where the reflected energy is concentrated. The solar energy is concentrated through the solar furnace of high radiative flux. The endothermic step is the reduction of the cerium oxide to lower-valence cerium oxide, at very high temperature. The exothermic step is the hydrolysis of the cerium oxide (III) to form H2 and the corresponding initial cerium oxide made at lower temperature inside the solar reactor. For the modeling, three sections of the pipe where the reaction occurs were considered; the carrier gas inlet, the porous medium and the reaction products outlet. The mathematical model describes the fluid mechanics; mass and energy transfer occurring therein inside the tungsten pipe. Thermochemical process model was simulated in CFD. The results show a temperature distribution in the solar reaction pipe and allow obtaining the fluid dynamics and the heat transfer within the pipe. This work is part of the project "Solar Fuels and Industrial Processes" from the Mexican Center for Innovation in Solar Energy (CEMIE-Sol).

  1. CeO2-Y2O3-ZrO2 Membrane with Enhanced Molten Salt Corrosion Resistance for Solid Oxide Membrane (SOM) Electrolysis Process

    Science.gov (United States)

    Zou, Xingli; Li, Xin; Shen, Bin; Lu, Xionggang; Xu, Qian; Zhou, Zhongfu; Ding, Weizhong

    2017-02-01

    Innovative CeO2-Y2O3-ZrO2 membrane has been successfully developed and used in the solid oxide membrane (SOM) electrolysis process for green metallic materials production. The x mol pct ceria/(8- x) mol pct yttria-costabilized zirconia ( xCe(8- x)YSZ, x = 0, 1, 4, or 7) membranes have been fabricated and investigated as the membrane-based inert anodes to control the SOM electroreduction process in molten salt. The characteristics of these fabricated xCe(8- x)YSZ membranes including their corrosion resistances in molten salt and their degradation mechanisms have been systematically investigated and compared. The results show that the addition of ceria in the YSZ-based membrane can inhibit the depletion of yttrium during the SOM electrolysis, which thus makes the ceria-reinforced YSZ-based membranes possess enhanced corrosion resistances to molten salt. The ceria/yttria-costabilized zirconia membranes can also provide reasonable oxygen ion conductivity during electrolysis. Further investigation shows that the newly modified 4Ce4YSZ ceramic membrane has the potential to be used as novel inert SOM anode for the facile and sustainable production of metals/alloys/composites materials such as Si, Ti5Si3, TiC, and Ti5Si3/TiC from their metal oxides precursors in molten CaCl2.

  2. CeO2-Y2O3-ZrO2 Membrane with Enhanced Molten Salt Corrosion Resistance for Solid Oxide Membrane (SOM) Electrolysis Process

    Science.gov (United States)

    Zou, Xingli; Li, Xin; Shen, Bin; Lu, Xionggang; Xu, Qian; Zhou, Zhongfu; Ding, Weizhong

    2016-10-01

    Innovative CeO2-Y2O3-ZrO2 membrane has been successfully developed and used in the solid oxide membrane (SOM) electrolysis process for green metallic materials production. The x mol pct ceria/(8-x) mol pct yttria-costabilized zirconia (xCe(8-x)YSZ, x = 0, 1, 4, or 7) membranes have been fabricated and investigated as the membrane-based inert anodes to control the SOM electroreduction process in molten salt. The characteristics of these fabricated xCe(8-x)YSZ membranes including their corrosion resistances in molten salt and their degradation mechanisms have been systematically investigated and compared. The results show that the addition of ceria in the YSZ-based membrane can inhibit the depletion of yttrium during the SOM electrolysis, which thus makes the ceria-reinforced YSZ-based membranes possess enhanced corrosion resistances to molten salt. The ceria/yttria-costabilized zirconia membranes can also provide reasonable oxygen ion conductivity during electrolysis. Further investigation shows that the newly modified 4Ce4YSZ ceramic membrane has the potential to be used as novel inert SOM anode for the facile and sustainable production of metals/alloys/composites materials such as Si, Ti5Si3, TiC, and Ti5Si3/TiC from their metal oxides precursors in molten CaCl2.

  3. Effects of Ce and Sb on the microstructure and properties of AZ91D magnesium alloy prepared by the EPC process

    Institute of Scientific and Technical Information of China (English)

    LI Jiqiang; DONG Xuanpu; FAN Zitian; WANG Yuanqing

    2008-01-01

    The effects of small amounts of cerium and antimony additions on the microstructure and the mechanical properties of AZ91D (Mg-9A1-Zn)based alloy were researched via the expendable pattern casting (EPC) process.The results show that the microstructure is obviously refined and the tensile strength of the AZ91D based alloy at ambient temperature is significantly improved.When compared to AZ91D,the AZ91D-1.0%Ce-0.4%Sb alloy has higher ultimate tensile strength and elongation.Its ultimate tensile strength and elongation are enhanced by 39% and 47%,respectively.The morphology of the tensile fracture of the AZ91D-1.0%Ce-0.4%Sb alloy has more characteristics of quasi-cleavage,This indicates that it has had a larger plastic deformation before failure.The tensile strength and elongation decrease with the increase of Ce and Sb contents because of the coarsening and volume increase of Cesb and Al11Ce3 phases.

  4. Fabrication of CeO2 by sol-gel process based on microfluidic technology as an analog preparation of ceramic nuclear fuel microspheres

    CERN Document Server

    Ye, Bin; Li, Jiaolong; Zhao, Zichen; Chang, Zhenqi; Serra, Christophe A

    2012-01-01

    Microfluidics integrated with sol-gel processes is introduced in preparing monodispersed MOX nuclear fuel microspheres using nonactive cerium as a surrogate for uranium or plutonium. The detailed information about microfluidic devices and sol-gel processes are provided. The effects of viscosity and flow rate of continuous and dispersed phase on size and size distribution of CeO2 microspheres have been investigated. A comprehensive characterization of the CeO2 microspheres has been conducted, including XRD pattern, SEM, density, size and size distribution. The size of prepared monodisperse particles can be controlled precisely in range of 10{\\mu}m to 1000{\\mu}m and the particle CV is below 3%.

  5. Synthesis and characterization of Ce_(0.8)Sm_(0.2)O_(1.9) nanopowders using an acrylamide polymerization process

    Institute of Scientific and Technical Information of China (English)

    郑颖平; 王绍荣; 王振荣; 邬理伟; 孙岳明

    2010-01-01

    Ce0.8Sm0.2O1.9(SDC) nanopowders were synthesized by an acrylamide polymerization process.The XRD results showed that SDC powders prepared at 700 °C possessed a cubic fluorite structure.Transmission electron microscopy(TEM) indicated that the particle sizes of powders were in the range of 10-15 nm.A 98.3% of theoretical density was obtained when the SDC pellets were sintered at 1350 °C for 5 h,indicating that the powders had good sinterability.The conductivity of the sintered SDC ceramics was 0.019 S/cm at 6...

  6. Factors controlling the microstructure of Ce0.9Gd0.1O2-δ films in pulsed laser deposition process

    DEFF Research Database (Denmark)

    Rodrigo, Katarzyna Agnieszka; Heiroth, S.; Döbeli, M.;

    2010-01-01

    Films of Ce0.9Gd0.1O2-delta (CGO10) are prepared at a range of conditions by pulsed laser deposition (PLD) on a single crystal Si (100) and MgO (100), and on a polycrystalline Pt/MgO (100) substrate. The relationship between the film microstructure, crystallography, chemical composition and PLD...... processing parameters is studied. It is found that the laser fluence has no significant impact on the film density, whereas the substrate temperature and the oxygen pressure are of essential importance for the film microstructure development. The reduction of deposition temperature, down to 250 oC, together...

  7. Fast signal processing of a yttrium-aluminum-perovskite:Ce detector for synchrotron x-ray experiments

    Science.gov (United States)

    Harada, Masaaki; Sakurai, Kenji; Saitoh, Kazuhiro; Kishimoto, Shunji

    2001-11-01

    An amplifier has been developed to form narrow pulses of less than 100 ns for a YAP:Ce scintillator, which appears promising as a detector for high-counting rate x-ray measurements. The performance of the detector system has been evaluated with monochromatic 8, 16.5, and 25 keV synchrotron x-ray photons at the Photon Factory. The whole deadtime obtained was 84 ns, which is around 3.5 times the decay time of the scintillation (25 ns), indicating that the present system is almost optimum. It has been found that the counting loss for 1 M counts/s is only 8%-9%, and that the detector can count extremely strong photons up to 5 M counts/s.

  8. Effect of Mg2+ ions co-doping on luminescence and defects formation processes in Gd3(Ga,Al)5O12:Ce single crystals

    Science.gov (United States)

    Babin, V.; Bohacek, P.; Grigorjeva, L.; Kučera, M.; Nikl, M.; Zazubovich, S.; Zolotarjovs, A.

    2017-04-01

    Photo- and radioluminescence and thermally stimulated luminescence characteristics of Ce3+ - doped and Ce3+, Mg2+ co-doped Gd3(Ga,Al)5O12 (GAGG) single crystals of similar composition are investigated in the 9-500 K temperature range. The Ce3+ - related luminescence spectra and the photoluminescence decay kinetics in these crystals are found to be similar. Under photoexcitation in the Ce3+ - and Gd3+ - related absorption bands, no prominent rise of the photoluminescence intensity in time is observed neither in GAGG:Ce,Mg nor in GAGG:Ce crystals. The afterglow is strongly reduced in GAGG:Ce,Mg as compared to GAGG:Ce, and the afterglow decay kinetics is much faster. Co-doping with Mg2+ results in a drastic decrease of the thermally stimulated luminescence (TSL) intensity in the whole investigated temperature range and in the appearance of a new complex Mg2+ - related TSL glow curve peak around 285 K. After irradiation in the Ce3+ - related 3.6 eV absorption band, the TSL intensity in GAGG:Ce,Mg is found to be comparable with that in the GAGG:Ce epitaxial film of similar composition. The Mg2+ - induced changes in the concentration, origin and structure of the crystal lattice defects and their influence on the scintillation characteristics of GAGG:Ce,Mg are discussed.

  9. Improved Laboratory Transition Probabilities for Ce II, Application to the Cerium Abundances of the Sun and Five r-process Rich, Metal-Poor Stars, and Rare Earth Lab Data

    CERN Document Server

    Lawler, J E; Cowan, J J; Ivans, I I; Hartog, E A Den

    2009-01-01

    Recent radiative lifetime measurements accurate to +/- 5% using laser-induced fluorescence (LIF) on 43 even-parity and 15 odd-parity levels of Ce II have been combined with new branching fractions measured using a Fourier transform spectrometer (FTS) to determine transition probabilities for 921 lines of Ce II. This improved laboratory data set has been used to determine a new solar photospheric Ce abundance, log epsilon = 1.61 +/- 0.01 (sigma = 0.06 from 45 lines), a value in excellent agreement with the recommended meteoritic abundance, log epsilon = 1.61 +/- 0.02. Revised Ce abundances have also been derived for the r-process-rich metal-poor giant stars BD+17 3248, CS 22892-052, CS 31082-001, HD 115444 and HD 221170. Between 26 and 40 lines were used for determining the Ce abundance in these five stars, yielding a small statistical uncertainty of 0.01 dex similar to the Solar result. The relative abundances in the metal-poor stars of Ce and Eu, a nearly pure r-process element in the Sun, matches r-process ...

  10. Diesel/biodiesel soot oxidation with CeO{sub 2} and CeO{sub 2}-ZrO{sub 2}- modified cordierites: a facile way of accounting for their catalytic ability in fuel combustion processes

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Rodrigo F.; Oliveira, Edimar de; Sousa Filho, Paulo C. de; Neri, Claudio R.; Serra, Osvaldo A., E-mail: crneri@usp.b [Universidade de Sao Paulo (DQ/FFCLRP/USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Dept. de Quimica

    2011-07-01

    CeO{sub 2} and mixed CeO{sub 2}-ZrO{sub 2} nanopowders were synthesized and efficiently deposited onto cordierite substrates, with the evaluation of their morphologic and structural properties through XRD, SEM, and FTIR. The modified substrates were employed as outer heterogeneous catalysts for reducing the soot originated from the diesel and diesel/biodiesel blends incomplete combustion. Their activity was evaluated in a diesel stationary motor, and a comparative analysis of the soot emission was carried out through diffuse reflectance spectroscopy. The analyses have shown that the catalyst-impregnated cordierite samples are very efficient for soot oxidation, being capable of reducing the soot emission in more than 60%. (author)

  11. Cyclic voltammetry study of Ce(IV/Ce(III redox couple and Ce(IV-F complex in sulfuric acid medium

    Directory of Open Access Journals (Sweden)

    J. G. He

    2016-10-01

    Full Text Available In this paper the electrochemical behaviors of Ce(IV/Ce(III redox couple and Ce(IV - F complex in sulfuric acid medium were studied by cyclic voltammetry using a platinum electrode. Both of the Ce(IV/Ce(III couple in Ce(IV solution and Ce(IV - F complex is a quasi-reversible process, and gives a linear correlation between the peak potentials and square root of scan rates, showing that the kinetics of the overall process is diffusion controlled. The complexation of cerium(IV and fluoride is favorable for the oxidation of Ce(III. The kinetic parameters such as diffusion coefficients, anodic transfer coefficients and rate constants were studied.

  12. First determination of s-process element abundances in pre-main sequence clusters. Y, Zr, La, and Ce in IC 2391, the Argus association, and IC 2602

    Science.gov (United States)

    D'Orazi, V.; De Silva, G. M.; Melo, C. F. H.

    2017-02-01

    Context. Several high-resolution spectroscopic studies have provided compelling observational evidence that open clusters display a decreasing trend of their barium abundances as a function of the cluster's age. Young clusters (ages ≲ 200 Myr) exhibit significant enhancement in the [Ba/Fe] ratios, at variance with solar-age clusters where the Ba content has been found to be [Ba/Fe] 0 dex. Different viable solutions have been suggested in the literature; nevertheless, a conclusive interpretation of such a peculiar trend has not been found. Interestingly, it is debated whether the other species produced with Ba via s-process reactions follow the same trend with age. Aims: Pre-main sequence clusters (≈10-50 Myr) show the most extreme behaviour in this respect: their [Ba/Fe] ratios can reach 0.65 dex, which is higher than the solar value by a factor of four. Crucially, there are no investigations of the other s-process species for these young stellar populations. In this paper we present the first determination of Y, Zr, La, and Ce in clusters IC 2391, IC 2602, and the Argus association. The main objective of our work is to ascertain whether these elements reveal the same enhancement as Ba. Methods: We have exploited high-resolution, high signal-to-noise spectra in order to derive abundances for Y, Zr, La, and Ce via spectral synthesis calculations. Our sample includes only stars with very similar atmospheric parameters so that internal errors due to star-to-star inhomogeneity are negligible. The chemical analysis was carried out in a strictly differential way, as done in all our previous investigations, to minimise the impact of systematic uncertainties. Results: Our results indicate that, at variance with Ba, all the other s-process species exhibit a solar scaled pattern; these clusters confirm a similar trend discovered in the slightly older local associations (e.g. AB Doradus, Carina-Near), where only Ba exhibit enhanced value with all other s-process species

  13. On Chinglish in C-E Interpretation

    Institute of Scientific and Technical Information of China (English)

    XIAO Gui-fang; LIU Jian-zhu; GUI Ren-na

    2005-01-01

    Based on the author's survey into the different interpretations of some terms from Chinese into English, the paper points out Chinglish exists universally in C-E interpretation.The author also puts forward some proposals on how to avoid and reduce Chinglish in the process of C-E interpretation after exploring its features and causes of Chinglish.

  14. Application of a space-time CE/SE (Conversation Element/Solution Element) method to the numerical solution of chromatographic separation processes

    DEFF Research Database (Denmark)

    including convection-difmsion-reaction PDEs are numerically solved using the two methods on the same spatial grid. Even though the CE/SE method uses a simple stencil structure and is developed on a simple mathematical basis (i.e., Gauss' divergence theorem), accurate and computationally-efficient solutions......For solving partial differential equations (or distributed dynamic systems), the method of lines (MOL) and the space-time conservation element and solution element (CE/SE) method are compared in terms of computational efficiency, solution accuracy and stability. Several representative examples....... It is concluded that the CE/SE method is adequate to capturing shocks in PDEs but for diffusion-dominated stiff PDEs, the MOL with an ODE time integrator is complementary to the CE/SE method....

  15. Atenção Pré-Natal no Município de Quixadá-CE segundo indicadores de processo do SISPRENATAL Atención prenatal en el municipio de Quixadá-CE según indicadores de proceso del SISPRENATAL Prenatal care in Quixadá-CE according to SISPRENATAL's process indicators

    Directory of Open Access Journals (Sweden)

    Gisele Ribeiro Grangeiro

    2008-03-01

    Full Text Available Pesquisa descritiva, documental, que objetivou analisar os indicadores de processo do Sistema de Informação do Pré-natal (SISPRENATAL, em Quixadá-CE. Estudaram-se 1.544 cadastros de gestantes no período de 2001 a 2004. Os dados foram coletados de fevereiro a abril de 2005 no SISPRENATAL, implantado no setor de Epidemiologia da Secretaria Municipal de Saúde. Os resultados foram apresentados em tabela única e analisados à luz da literatura atual e experiência acumulada das autoras. Verificou-se percentual crescente de gestantes com indicador de, no mínimo, seis consultas, todos os exames básicos, teste anti-HIV, imunização antitetânica e consulta puerperal de 2001 a 2004, ou seja, zero, 2,6, 5,68 e 21,11%, respectivamente. É necessário, pois, uma melhora na utilização do Sistema, assim como a leitura sistemática dos indicadores de processo, no sentido de obter subsídios para a melhoria da qualidade da assistência pré-natal.En esta Investigación descriptiva, documental se tuvo como objetivo analizar los indicadores de proceso del Sistema de Información del Prenatal (SISPRENATAL, el el municipio de Quixadá-CE. Fueron estudiados 1.544 registros de mujeres embarazadas en el período de 2001 a 2004. Los datos fueron recolectados de febrero a abril del 2005 en el SISPRENATAL, en el sector de Epidemiología de la Secretaría Municipal de Salud. Los resultados fueron presentados sólo en una tabla y analizados a la luz de la literatura actual y también a partir de las experiencias de las autoras. Se verificó el porcentaje creciente de mujeres embarazadas con indicador mínimo de seis consultas, todos los exámenes básicos, test anti-VIH, inmunización antitetánica y consulta puerperal de 2001 a 2004, es decir, cero, 2,6, 5,68 e 21,11%, respectivamente. Es necesario, pues, una mejor utilización del Sistema, y también una lectura sistemática de los indicadores de proceso para obtener soporte para la mejoría de la calidad de

  16. Preparation,Characterization of CuO/CeO2 and Cu/CeO2 Catalysts and Their Applications in Low-Temperature CO Oxidation

    Institute of Scientific and Technical Information of China (English)

    Zheng Xiucheng; Han Dongzhan; Wang Shuping; Zhang Shoumin; Wang Shurong; Huang Weiping; Wu Shihua

    2005-01-01

    CeO2 was synthesized via sol-gel process and used as supporter to prepare CuO/CeO2, Cu/CeO2 catalysts by impregnation method. The catalytic properties and characterization of CeO2, CuO/CeO2 and Cu/CeO2 catalysts were examined by means of a microreactor-GC system, HRTEM, XRD, TPR and XPS techniques. The results show that CuO has not catalytic activity and the activity of CeO2 is quite low for CO oxidation. However, the catalytic activity of CuO/CeO2 and Cu/CeO2 catalysts increases significantly. Furthermore, the activity of CuO/CeO2 is higher than that of Cu/CeO2 catalysts.

  17. Methane reforming With CO2 to syngas over CeO2-promoted Ni/Al2O3-ZrO2 catalysts Prepared Via a direct sol-gel process

    Institute of Scientific and Technical Information of China (English)

    Hansheng Li; Hang Xu; Jinfu Wang

    2011-01-01

    CeO2-promoted Ni/Al2O3-ZrO2 (Ni/Al2O3-ZrO2-CeO2) catalysts were prepared by a direct sol-gel process with citric acid as gelling agent.The catalysts used for the methane reforming with CO2 was studied by infrared spectroscopy (IR), thermal gravimetric analysis (TGA), microscopic analysis, X-ray diffraction (XRD) and temperature-programmed reduction (TPR).The catalytic performance for CO2 reforming of methane to synthesis gas was investigated in a continuous-flow micro-reactor under atmospheric pressure.TGA, IR, XRD and microscopic analysis show that the catalysts prepared by the direct sol-gel process consist of Ni particles with a nanostructure of around 5 nm and an amorphous-phase composite oxide support.There exists a chemical interaction between metallic Ni particles and supports, which makes metallic Ni well dispersed, highly active and stable.The addition of CeO2 effectively improves the dispersion and the stability of Ni particles of the prepared catalysts, and enhances the adsorption of CO2 on the surface of catalysts.The catalytic tests for methane reforming with CO2 to synthesis gas show that the Ni/Al2O3-ZrO2-CeO2 catalysts show excellent activity and stability compared with the Ni/Al2O3 catalyst.The excellent catalytic activity and stability of the Ni/Al2O3-ZrO2-CeO2 are attributed to the highly, uniformly and stably dispersed small metallic Ni particles, the high reducibility of the Ni oxides and the interaction between metallic Ni particles and the composite oxide supports.

  18. The formation of intermetallic compounds during interdiffusion of Mg–Al/Mg–Ce diffusion couples

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Jiahong [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Jiang, Bin, E-mail: jiangbinrong@cqu.edu.cn [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing 401123 (China); Li, Xin [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Yang, Qingshan [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing 401123 (China); Dong, Hanwu [Chongqing Academy of Science and Technology, Chongqing 401123 (China); Xia, Xiangsheng [No. 59 Institute of China Ordnance Industry, Chongqing 400039 (China); Pan, Fusheng [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing 401123 (China)

    2015-01-15

    Graphical abstract: Al–Ce intermetallic compounds (IMCs) formed in Mg–Al/Mg–Ce diffusion couples. During the whole diffusion process, Al was the dominant diffusing species, and it substituted for Mg atoms of the Mg–Ce substrate. Five Al–Ce IMCs of Al{sub 4}Ce, Al{sub 11}Ce{sub 3}, Al{sub 3}Ce, Al{sub 2}Ce, and AlCe were formed via the reaction of Al and Ce. - Highlights: • Al–Ce IMCs formation in the Mg–Al/Mg–Ce diffusion couples was studied. • Formation of Al{sub 4}Ce as the first phase was rationalized using the Gibbs free energy. • The activation energy for the growth of the diffusion reaction zones was 36.6 kJ/mol. - Abstract: The formation of Al–Ce intermetallic compounds (IMCs) during interdiffusion of Mg–Al/Mg–Ce diffusion couples prepared by solid–liquid contact method was investigated at 623 K, 648 K and 673 K for 24 h, 48 h and 72 h, respectively. During the whole diffusion process, Al was the dominant diffusing species, and it substituted for Mg of the Mg–Ce substrate. Five Al–Ce IMCs of Al{sub 4}Ce, Al{sub 11}Ce{sub 3}, Al{sub 3}Ce, Al{sub 2}Ce and AlCe were formed via the reaction of Al and Ce. The formation of Al{sub 4}Ce as the first kind of IMC was rationalized on the basis of an effective Gibbs free energy model. The activation energy for the growth of the total diffusion reaction layer was 36.6 kJ/mol.

  19. Factors controlling the microstructure of Ce0.9Gd0.1O2-δ films in pulsed laser deposition process

    DEFF Research Database (Denmark)

    Rodrigo, Katarzyna Agnieszka; Heiroth, S.; Döbeli, M.;

    Films of Ce0.9Gd0.1O2-δ(CGO10) are prepared at a range of conditions by pulsed laser deposition (PLD) on a single crystal Si (100) and MgO (100), and on a polycrystalline Pt/MgO (100) substrate. The relationship between the film microstructure, crystallography, chemical composition and PLD...

  20. INFLUENCE OF SYNTHESIS PROCESS ON THE COLOUR PROPERTIES OF MIXED OXIDE PIGMENT Bi1.5Zn0.5Ce2O7

    Directory of Open Access Journals (Sweden)

    Katerina Tesitelova

    2016-10-01

    Full Text Available The synthesis of a new inorganic pigment Bi1.5Zn0.5Ce2O7 is reported. The pigment was prepared by conventional solid-state reaction (SSR, suspension mixing (SM and precipitation reaction (PR with the goal of creating an environmentally benign pigment. The selected samples were characterized by X-ray diffraction analysis. Focusing on pigmentary applications, specific properties of the samples were evaluated, such as colour parameters and particle size distribution. Dark yellow hues were obtained by using SSR and SM after the application samples into the organic binder in mass tone. The PR method was found to be the most suitable for the formation of dark yellow shades in the ceramic glaze. Based on obtained results, Bi1.5Zn0.5Ce2O7 could be considered as a perspective yellow pigment for colouring organic binder systems and ceramic glaze.

  1. Microstructure, mechanical properties and electrical conductivity of Cu–0.3Mg–0.05Ce alloy processed by equal channel angular pressing and subsequent annealing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Guang [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Li, Zhou, E-mail: lizhou6931@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of Powder Metallurgy, Changsha 410083 (China); Yuan, Yuan [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Lei, Qian [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Changsha 410083 (China)

    2015-08-15

    Highlights: • Minor Ce addition can deprive harmful elements and purify the Cu–Mg alloy. • Decrease of Mg content can effectively enhance the conductivity of Cu–Mg alloy. • Ultrafine-grained Cu–Mg–Ce alloy was successfully gained by 8 passes of ECAP. • The strength of Cu–Mg–Ce alloy can be significantly improved by ECAP. • Better comprehensive properties than the commercial Cu–Mg alloy are gained. - Abstract: A Cu–0.3 wt.%Mg–0.05 wt.%Ce alloy was designed and prepared by melting and casting. After hot rolled, the ingot was cut into rod-shape samples for equal channel angular pressing (ECAP) with different passes at room temperature. The microstructure evolutions were investigated using transmission electron microscope (TEM) observation and electron backscatter diffraction (EBSD) analysis. The severe plastic deformation (SPD) caused by ECAP made the grains elongated significantly. With the increase of ECAP passes, the fraction of high-angle boundaries (HABs) (θ ⩾ 15°) increased and the microstructure was refined. Tension testing results indicated that the tensile strength was remarkably improved from 273.4 MPa before ECAP to 587.5 MPa after 8 passes of ECAP, maintaining an appropriate elongation of 11.4% and good electrical conductivity of 73.1%IACS. After annealing treatment at 300 °C for 2 h, the ECAP samples still maintained excellent comprehensive properties: tensile strength was 558.2 MPa, electrical conductivity was 74.7%IACS, and elongation was 13.2%, which showed bright prospect in high-speed railway as a contact wire material.

  2. Partial oxidation of methane on Ni/CeO2-ZrO2/γ-Al2O3 prepared using different processes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qingwei; SHEN Meiqing; WEN Jing; WANG Jun; FEI Yanan

    2008-01-01

    The influences of CeO2-ZrO2 and γ-Al2O3 mixing methods on the catalytic activity and stability of partial oxidation of methane (POM) were investigated over Ni/Ce0.7Zr0.3O2-Al2O3 catalysts. The catalysts were characterized by XRD, TPR, H2-chemsorption, and TG-DTA. For fresh catalysts, the results showed that the salt precursor mixing catalyst (ATOM) presented better performance than the catalysts prepared by the precipitator mixing method (MOL) and the powder mechanically mixing method (MECH). The result of XRD suggested that the interaction between CeO2-ZrO2 and Al2O3 in ATOM sample was stronger than the others, which led to more lattice defects and thereby better initial activity. Moreover, the MECH sample had the best stability and the least coke deposition in 24 h stability tests. The results of TPR and H2-chemsorption indicated that the intimate contact of Ni-Al in MECH sample enhanced the ability of resisting coke deposition and metal sintering.

  3. Study of Ce-modified antibacterial 316L stainless steel

    Directory of Open Access Journals (Sweden)

    Yuan Junping

    2012-11-01

    Full Text Available 316L stainless steel is widely used for fashion jewelry, but it can carry a large number of bacteria and bring the risk of infection since the steel has no antimicrobial performance. In this paper, the effects of Ce on the antibacterial property, corrosion resistance and processability of 316L were studied by microscopic observation, thin-film adhering quantitative bacteriostasis, and electrochemical and mechanical tests. The results show that a trace of Ce can distribute uniformly in the matrix of 316L and slightly improve its corrosion resistance in artificial sweat. With an increase in Ce content, the Ce is prone to form clustering, which degrades the corrosion resistance and the processability. The Ce-containing 316L exhibits Hormesis effect against S. aureus. A small Ce addition stimulates the growth of S. aureus. As the Ce content increases, the modified 316L exhibits an improved antibacterial efficacy. The more Ce is added, the better antibacterial capability is achieved. Overall, if the 316L is modified with Ce alone, it is difficult to obtain the optimal combination of corrosion resistance, antibacterial performance and processability. In spite of that, 0.15 wt.%-0.20 wt.% Ce around is inferred to be the best trade-off.

  4. Preparation and characterization of CNT-CeO2 nanocomposite

    Science.gov (United States)

    Kaur, Jasmeet; Anand, Kanika; Singh, Ravi Chand

    2015-06-01

    This paper reports decoration of CeO2 nanoparticles on multi-walled carbon nanotubes through a reflux process in which Ce (NO3) 3.6H2O serves as precursor and hydrazine hydrate (N2H4.H2O) as reducing agent. Successful deposition of cubic fluorite CeO2 nanoparticles onto multi-walled carbon nanotubes has been confirmed by x-ray diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM) and energy dispersive x-ray spectroscopy (EDS). It was found that CeO2 nanoparticles formed in the presence of CNTs were larger as compared to pure CeO2 nanoparticles. Raman analysis showed that CeO2 induced a decrease in the size of the carbon grain in the CNTs. A red shift from 460 cm-1 to 463 cm-1 for F2g mode of CeO2 has also been observed in Raman spectra of CNT- CeO2 nanocomposite as compared to pure CeO2. The CeO2 coated multi-wall carbon nanotubes (CNT-CeO2) nanocomposite would be a promising candidate for practical applications such as catalysis, sensing and power source applications.

  5. Jovens e formação técnica no IF-CE: dilemas contemporâneos no processo de escolha profissional / Youth and technical education in IF-CE: contemporary dilemmas in the process of occupational choice

    Directory of Open Access Journals (Sweden)

    Fúlvio Holanda Rocha

    2010-09-01

    Full Text Available Abordamos neste trabalho o processo de escolha profissional dos estudantes que ingressam nos cursos técnicos integrados do IF-CE. Isso se configura como um dos novos desafios da atual realidade institucional. O tema proveio da escuta de setores dessa instituição pelo serviço de Psicologia Escolar. No discurso discente, esboçou-se a relação entre as queixas, acompanhadas de sofrimento psíquico, e a necessária escolha profissional no ato de ingresso. Não individualizando as dificuldades decorrentes da escolarização e concebendo a escolha profissional como um processo que se dá nas interações sociais antes, durante e depois da entrada no curso, foi possível demarcar três formas de conceber o IF-CE: como uma escola “preparatória” para o vestibular, como um espaço educacional que traz por “adição” preparo profissional e como um mecanismo de primeira aproximação com uma carreira a ser exercida após a graduação. Verificamos a difusa percepção pelos alunos de que faziam opção por uma carreira e assinalamos a necessidade de oferecer espaços institucionais qualificados para os alunos elaborarem suas opções profissionais.This study evaluates career choice process of IF-CE students enrolled in technical courses. This issue appears as one of the new challenges of current institutional reality and arises from listening to young people and departments of the institution by the Educational Psychology Service. In student discourse, it was outlined the relations between the complaints, which was accompanied by psychological distress, and the necessary occupational choice at time of ingress. Taking the difficulties that results from schooling without individualizing them and conceiving the occupational choice as a process that happens in social interactions before, during and after the ingress to the course was possible to distinguish between three ways of understanding the IF-CE: as a "preparatory" school to the vestibular

  6. Thermal and sonochemical synthesis of porous (Ce,Zr)O2 mixed oxides from metal β-diketonate precursors and their catalytic activity in wet air oxidation process of formic acid.

    Science.gov (United States)

    Cau, Camille; Guari, Yannick; Chave, Tony; Larionova, Joulia; Nikitenko, Sergey I

    2014-07-01

    Porous (Ce0.5Zr0.5)O2 solid solutions were prepared by thermolysis (T=285 °C) or sonolysis (20 kHz, I=32 W cm(-2), Pac=0.46 W mL(-1), T=200 °C) of Ce(III) and Zr(IV) acetylacetonates in oleylamine or hexadecylamine under argon followed by heat treatment of the precipitates obtained in air at 450 °C. Transmission Electron Microscopy images of the samples show nanoparticles of ca. 4-6 nm for the two synthetic approaches. The powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and μ-Raman spectroscopy of solids obtained after heat treatment indicate the formation of (Ce0.5Zr0.5)O2 solid solutions with a metastable tetragonal crystal structure for the two synthetic routes. The specific surface area of the samples varies between 78 and 149 m(2) g(-1) depending on synthesis conditions. The use of Barrett-Joyner-Halenda and t-plot methods reveal the formation of mixed oxides with a hybrid morphology that combines mesoporosity and microporosity regardless of the method of preparation. Platinum nanoparticles were deposited on the surface of the mixed oxides by sonochemical reduction of Pt(IV). It was found that the materials prepared by sonochemistry exhibit better resistance to dissolution during the deposition process of platinum. X-ray photoelectron spectroscopy analysis shows the presence of Pt(0) and Pt(II) on the surface of mixed oxides. Porous (Ce0.5Zr0.5)O2 mixed oxides loaded with 1.5%wt. platinum exhibit high activity in catalytic wet air oxidation of formic acid at 40 °C.

  7. Challenges of CE

    NARCIS (Netherlands)

    Verhagen, Wim J.C.; Stjepandić, Josip; Wognum, Nel

    2015-01-01

    Despite a long pedigree and many positive reports on its use and benefits, concurrent engineering (CE) and its associated research (sub)domains still experience significant development. In this final chapter, a socio-technical framework is applied to classify and analyze challenges identified as

  8. CE-BEMS

    DEFF Research Database (Denmark)

    Mohamed, Nader; Lazarova-Molnar, Sanja; Al-Jaroodi, Jameela

    2016-01-01

    and costs savings in smart buildings significantly depend on the monitoring and control methods used in the installed BEMS. This paper proposes a Cloud-Enabled BEMS (CE-BEMS) for Smart Buildings. This system can utilize cloud computing to provide enhanced management mechanisms and features for energy...

  9. Investigation on preparation of CuO-SnO2-CeO2/γ-Al2O3 catalysts for catalytic wet air oxidation process and their catalytic activity for degradation of phenol

    Institute of Scientific and Technical Information of China (English)

    SUN Xiao-jun; ZHANG Mi-lin; WAN Jia-feng; XIA Zhi; LIU Xiao-hui; LIU hui

    2008-01-01

    Catalytic Wet Air Oxidation process is an efficient measure for treatment of wastewater with great strength which is not biodegradable. Heterocatalysts now become the key investigation subject of catalytic wet air oxidation process due to their good stability and easy separation. In the paper, CuO-SnOE-CeO2/γ-Al2O3 catalysts are prepared by impregnation method, with SnO2 as a doping component, CuO as an active component, CeO2 as a structure stabilizer, γ-Al2O3 as a substrate. XPS test is carried out to investigate the effect of Sn on the chemical surrounding of Cu and O element on the catalyst surface and their catalytic activity. It is shown that the right do-ping of Sn can increase Cu+ content on the catalyst surface, as a result the quantity of adsorption oxygen is also increased. It is found that Cu + content on the catalyst surface is one of the primary factors that determin catalytic activity of catalyst through analyzing the catalytic wet air oxidation process of phenol.

  10. Inimhääle lummus ja topeltverism / Tiiu Levald

    Index Scriptorium Estoniae

    Levald, Tiiu, 1940-

    2008-01-01

    Birgitta festivali raames 10. ja 11. VIII Pirita kloostris toimunud etendustest - Mascagni "Talupoja au", Leoncavallo "Pajatsid" ja Donizetti "Maria Stuart" Moskva Novaja Opera esituses, dirigendid: Eri Klas, Valeri Kritskov ja Sergei Lõssenko

  11. Effect of Ce and La additions in low temperature aluminization process by CVD-FBR on 12%Cr ferritic/martensitic steel and behaviour in steam oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, L. [Universidad Complutense de Madrid, Grupo de Investigacion de Ingenieria de Superficies y Materiales Nanoestructurados, Avenida Complutense s/n, Facultad de Ciencias Quimicas, 28040 Madrid (Spain)], E-mail: lsanche@quim.ucm.es; Bolivar, F.J. [Universidad de Antioquia, Facultad de Ingenierias, Medellin (Colombia); Hierro, M.P.; Perez, F.J. [Universidad Complutense de Madrid, Grupo de Investigacion de Ingenieria de Superficies y Materiales Nanoestructurados, Avenida Complutense s/n, Facultad de Ciencias Quimicas, 28040 Madrid (Spain)

    2008-08-15

    Two different coatings based of iron aluminide on 12% Cr ferritic-martensitic steel have been developed by CVD-FBR technique, which is modified by the introduction of Ce and La as powder in the fluidized bed. These elements change the gaseous environment, which composition is predicted by a thermodynamic approximation. Partial pressures of all gaseous precursors are drastically modified; in consequence AlCl has the highest partial pressure in the system leading to an increment of the coating thickness. Coatings are composed by (Fe, Cr){sub 2}Al{sub 5} or (Fe, Cr){sub 2}Al{sub 5} and (Fe, Cr)Al{sub 3} intermetallic phases. On the other hand, steam oxidation test at 650 deg. C was performed in order to observe improvements in the HCM12A oxidation resistant.

  12. Factors affecting the superconductivity in the process of depositing Nd1.85Ce0.15CuO4-δ by the pulsed electron deposition technique

    Institute of Scientific and Technical Information of China (English)

    GUO; YanFeng

    2007-01-01

    On SrTiO3 single crystal substrate, by using the pulsed electron deposition technique, the high-quality electron doped Nd1.85Ce0.15CuO4-δsuperconducting film was successfully fabricated. After careful study on the R-T curves of the obtained samples deposited with different substrate temperatures, thicknesses, annealing methods and pulse frequencies, the effects of them on the superconductivity of the films were found, and the reasons were also analyzed. Additionally, by using the same model of the pulsed laser deposition technique, the relation between the target-to-substrate distance and the deposition pressure was drawn out as a quantitative one.  ……

  13. Epitaxial Cubic Ce2O3 Films via Ce-CeO2 Interfacial Reaction.

    Science.gov (United States)

    Stetsovych, Vitalii; Pagliuca, Federico; Dvořák, Filip; Duchoň, Tomáš; Vorokhta, Mykhailo; Aulická, Marie; Lachnitt, Jan; Schernich, Stefan; Matolínová, Iva; Veltruská, Kateřina; Skála, Tomáš; Mazur, Daniel; Mysliveček, Josef; Libuda, Jörg; Matolín, Vladimír

    2013-03-21

    Thin films of reduced ceria supported on metals are often applied as substrates in model studies of the chemical reactivity of ceria based catalysts. Of special interest are the properties of oxygen vacancies in ceria. However, thin films of ceria prepared by established methods become increasingly disordered as the concentration of vacancies increases. Here, we propose an alternative method for preparing ordered reduced ceria films based on the physical vapor deposition and interfacial reaction of Ce with CeO2 films. The method yields bulk-truncated layers of cubic c-Ce2O3. Compared to CeO2 these layers contain 25% of perfectly ordered vacancies in the surface and subsurface allowing well-defined measurements of the properties of ceria in the limit of extreme reduction. Experimentally, c-Ce2O3(111) layers are easily identified by a characteristic 4 × 4 surface reconstruction with respect to CeO2(111). In addition, c-Ce2O3 layers represent an experimental realization of a normally unstable polymorph of Ce2O3. During interfacial reaction, c-Ce2O3 nucleates on the interface between CeO2 buffer and Ce overlayer and is further stabilized most likely by the tetragonal distortion of the ceria layers on Cu. The characteristic kinetics of the metal-oxide interfacial reactions may represent a vehicle for making other metastable oxide structures experimentally available.

  14. Hollow nano-particles formation for CuO-CeO2-ZrO2 via a supercritical anti-solvent process

    Institute of Scientific and Technical Information of China (English)

    姜浩锡; 周佳丽; 孙焕花; 李永辉; 张敏华

    2016-01-01

    Hollow CuO-CeO2-ZrO2nano-particles were prepared with supercritical anti-solvent apparatus by using methanol as sol-vent and supercritical carbon dioxide as anti-solvent. Two key factors (i.e., pressure and temperature) were investigated to explore the effects of catalyst structure and physic-chemical properties (i.e., morphology, reducing property, oxygen storage capacity and specific surface area). The resulting materials were characterized with X-ray diffraction (XRD), high resolution transmission electron micros-copy (HRTEM), Brunauer-Emmett-Teller (BET),hydrogen temperature programmed reduction (H2-TPR) and oxygen storage capac-ity (OSC) measurement, respectively. The experimental results showed that lower temperatures promoted production of hollow struc-ture nano-particulates. The particle morphology also changed significantly, i.e. the solid construction was first transferred to hollow structure then back to solid construction. The optimal conditions for obtaining hollow nano-particles were determined at 45 °C, 18.0–24.0 MPa.

  15. 采用低 F 工艺在低碳残留 La2Zr2O7/CeO2缓冲层上沉积 YBCO 膜%Fabrication of YBCO Film on the La 2 Zr 2 O 7/CeO 2 Buffer Layer with Little Residual Carbon by a Low F Content Deposition Process

    Institute of Scientific and Technical Information of China (English)

    贾佳林; 王辉; 李成山; 王耀; 金利华; 吕建凤; 许征兵

    2015-01-01

    In this paper, the La2 Zr2 O7 (LZO) / CeO2 buffer layer and superconducting layer with bi-layer membrane structure were fabricated on the NiW baseband of bi-axial texture by the chemical solution method. In the buffer layer deposition process, the carbon residue among them was reduced by mixing with CO2 in the annealing atmosphere, and the deposition of YB-CO superconducting layer was carried out by the Low F content deposition process. The texture and morphology of the prepared samples were characterized by X ray diffraction (XRD) and scanning electron microscopy (SEM), and the electrical properties of the samples were tested. The result indicates that mixing with a small amount of weakly oxidizing gases did not destroy the texture and morphology of the buffer layer while removing residual carbon in the buffer lay-er. However, the YBCO layer deposited on the flat surface of the buffer layer showed a sharp bi-axial texture and good superconductivity, and this process can be further transplanted into the process of long length baseband preparation.%采用化学溶液法在双轴织构的 NiW 基带上制备了双层膜结构的 La2 Zr2 O7(LZO)/ CeO2缓冲层和超导层,在缓冲层沉积过程中通过在退火气氛中混入 CO2降低其中的碳残留量,YBCO 超导层的沉积则是通过低 F 工艺进行的。利用 X 射线衍射(XRD)和扫描电镜(SEM)对所制得样品的织构和表面形貌进行了表征,并测试了样品的电性能。结果表明,少量弱氧化性气体的混入在除去缓冲层中残留碳的同时并没有破坏缓冲层的织构和形貌。而在平整的缓冲层表面沉积的 YBCO 层显示出了锐利的双轴织构和良好的超导电性,该工艺可以进一步移植到长带制备过程中。

  16. Coexistence phenomenon of Ce(3+)-Ce(4+) and Eu(2+)-Eu(3+) in Ce/Eu co-doped LiBaB9O15 phosphor: luminescence and energy transfer.

    Science.gov (United States)

    Li, Ting; Li, Panlai; Wang, Zhijun; Xu, Shuchao; Bai, Qiongyu; Yang, Zhiping

    2017-02-01

    Ce/Eu-doped LiBaB9O15 (LBB) samples were prepared via conventional high temperature solid state reactions. The XRD patterns, crystal structures, luminescence properties, and decay times were investigated systematically. Ce(3+) ions exist in LBB:xCe(3+) that were synthesized in a reducing atmosphere and in an air atmosphere. However, we observed Eu(2+) ions in LBB:yEu(2+) in a reducing atmosphere and Eu(3+) ions in LBB:zEu(3+) in an air atmosphere. LBB:0.05Ce(3+),yEu(2+) phosphors synthesized in a reducing atmosphere only possess Ce(3+) and Eu(2+) and exhibit a broad excitation band ranging from 350 to 425 nm. A reduction phenomenon of Eu(3+) → Eu(2+) and coexistence of Ce(4+), Ce(3+), Eu(2+) and Eu(3+) were observed when LBB:0.05Ce,wEu phosphors were synthesized in an air atmosphere. There are three processes in LBB:0.05Ce,wEu, i.e., energy transfers from Ce(3+) to Eu(2+) and from Eu(2+) to Eu(3+), and metal-metal charge transfer (MMCT) between Ce(3+) and Eu(3+). Moreover, the MMCT process is dominant in LBB:0.05Ce,wEu due to less efficient energy transfer from Ce(3+) to Eu(2+). Moreover, the CIE coordinates of LBB:0.05Ce,wEu vary systematically from light blue (0.313, 0.129) to red (0.589, 0.315) for LBB:0.05Ce(3+),wEu synthesized in air with the changes in Eu ion concentration. Thus, we can control the color by controlling the synthesis atmospheres.

  17. DNA sequencing by CE.

    Science.gov (United States)

    Karger, Barry L; Guttman, András

    2009-06-01

    Sequencing of human and other genomes has been at the center of interest in the biomedical field over the past several decades and is now leading toward an era of personalized medicine. During this time, DNA-sequencing methods have evolved from the labor-intensive slab gel electrophoresis, through automated multiCE systems using fluorophore labeling with multispectral imaging, to the "next-generation" technologies of cyclic-array, hybridization based, nanopore and single molecule sequencing. Deciphering the genetic blueprint and follow-up confirmatory sequencing of Homo sapiens and other genomes were only possible with the advent of modern sequencing technologies that were a result of step-by-step advances with a contribution of academics, medical personnel and instrument companies. While next-generation sequencing is moving ahead at breakneck speed, the multicapillary electrophoretic systems played an essential role in the sequencing of the Human Genome, the foundation of the field of genomics. In this prospective, we wish to overview the role of CE in DNA sequencing based in part of several of our articles in this journal.

  18. Comparison of energy structure and spectral properties of Ce:LaAlO3 and Ce:Lu2(SiO4)O

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Undoped LaAlO3 and 1 at.%Ce:LaAlO3 single crystals were grown by the Czochralski process.Absorption and fluorescence spectra were measured at room temperature.Detailed energy levels structure of Ce:LaAlO3 was determined.In this paper,two viewpoints were provided.The first one is:the energy levels structure of Ce:LaAlO3 is very similar to that of Ce:Lu2(SiO4)O which is a well-known scintillator.In the energy levels structure of Ce:LaAlO3 and Ce:Lu2(SiO4)O,the lowest 5d energy level of Ce 3+ is located below the bottom of the conduction band of host crystal and the other higher 5d energy levels of Ce 3+ are located above the bottom of the conduction band of host crystal.The second one is:Ce:LaAlO3 single crystal may not be suitable for scintillation application;by comparing the energy levels structures of Ce:LaAlO3 and Ce:Lu2(SiO4)O,the large energy difference(1.13 eV)between the two lowest 5d energy levels of Ce 3+ in LaAlO3 is a crucial factor that causes the luminescence quenching.

  19. Heavy Fermion Character in Ce2Sb and Ce2Bi

    Science.gov (United States)

    Oyamada, Akira; Isobe, Atsushi; Kitazawa, Hideaki; Ochiai, Akira; Suzuki, Takashi; Kasuya, Tadao

    1993-05-01

    Magnetic susceptibilities, electrical resistivities and specific heats of Ce2Sb, Ce2Bi and CeLaBi were measured to clarify these physical properties. The most characteristic points of these compounds are the following. Ce site are two dimensional and the distance between Ce atoms are very small. The similarity between these compounds and CeRh3B2, in which Ce sites are one dimensional and the distance between Ce atoms are very small, are discussed.

  20. Search for double beta decay of $^{136}$Ce and $^{138}$Ce with HPGe gamma detector

    CERN Document Server

    Belli, P; Boiko, R S; Cappella, F; Cerulli, R; Danevich, F A; Incicchitti, A; Kropivyansky, B N; Laubenstein, M; Poda, D V; Polischuk, O G; Tretyak, V I

    2014-01-01

    Search for double $\\beta$ decay of $^{136}$Ce and $^{138}$Ce was realized with 732 g of deeply purified cerium oxide sample measured over 1900 h with the help of an ultra-low background HPGe $\\gamma$ detector with a volume of 465 cm$^3$ at the STELLA facility of the Gran Sasso National Laboratories of the INFN (Italy). New improved half-life limits on double beta processes in the cerium isotopes were set at the level of $\\lim T_{1/2}\\sim 10^{17}-10^{18}$~yr; many of them are even two orders of magnitude larger than the best previous results.

  1. Correlated electronic structure of CeN

    Energy Technology Data Exchange (ETDEWEB)

    Panda, S.K., E-mail: swarup.panda@physics.uu.se [Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala (Sweden); Di Marco, I. [Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala (Sweden); Delin, A. [Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala (Sweden); KTH Royal Institute of Technology, School of Information and Communication Technology, Department of Materials and Nano Physics, Electrum 229, SE-164 40 Kista (Sweden); KTH Royal Institute of Technology, Swedish e-Science Research Center (SeRC), SE-100 44 Stockholm (Sweden); Eriksson, O., E-mail: olle.eriksson@physics.uu.se [Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala (Sweden)

    2016-04-15

    Highlights: • The electronic structure of CeN is studied within the GGA+DMFT approach using SPTF and Hubbard I approximation. • 4f spectral functions from SPTF and Hubbard I are coupled to explain the various spectroscopic manifestations of CeN. • The calculated XPS and BIS spectra show good agreement with the corresponding experimental spectra. • The contribution of the various l-states and the importance of cross-sections for the photoemission process are analyzed. - Abstract: We have studied in detail the electronic structure of CeN including spin orbit coupling (SOC) and electron–electron interaction, within the dynamical mean-field theory combined with density-functional theory in generalized gradient approximation (GGA+DMFT). The effective impurity problem has been solved through the spin-polarized T-matrix fluctuation-exchange (SPTF) solver and the Hubbard I approximation (HIA). The calculated l-projected atomic partial densities of states and the converged potential were used to obtain the X-ray-photoemission-spectra (XPS) and Bremstrahlung Isochromat spectra (BIS). Following the spirit of Gunnarsson–Schonhammer model, we have coupled the SPTF and HIA 4f spectral functions to explain the various spectroscopic manifestations of CeN. Our computed spectra in such a coupled scheme explain the experimental data remarkably well, establishing the validity of our theoretical model in analyzing the electronic structure of CeN. The contribution of the various l-states in the total spectra and the importance of cross sections are also analyzed in detail.

  2. Properties and practical application of thin CeOx films

    Directory of Open Access Journals (Sweden)

    Maksimchuk N. V.

    2010-10-01

    Full Text Available The properties of CeOx films produced by various methods have been investigated. According to the comparative analisys “metallic mirror oxidation” method allows to produce films with significantly better characteristics than the «explosive evaporation» method. Though the latter method yields higher photosensitivity of CeOx films and structures on their base. In the process the optimal value of the substrate temperature was determined. Obtained data expand the CeOx application potential in microelectronic sensor sphere.

  3. Luminescence properties of Gd2Si2O7:Ce and Gd2Si2O7:La,Ce under vacuum ultraviolet irradiation

    Institute of Scientific and Technical Information of China (English)

    M Koshimizu; T Yanagida; Y Fujimoto; K Asai

    2016-01-01

    The luminescence properties of Ce-or Ce and La-doped gadolinium pyrosilicate (Gd2Si2O7, GPS) were characterized using vacuum ultraviolet (VUV) excitation light. A prominent emission band was observed in the luminescence spectra with excitation at 60 nm and ascribed to 5d-4f transition of Ce3+. Because the excitation wavelength of 60 nm corresponded to the excitation in the host matrix, this result indicated that the excitation energy transfer occurred from the host matrix to Ce3+ions. On the basis of the rise in the luminescence time profiles with excitation at 60 nm, the energy transfer occurred within 2 ns, which was much shorter than that of Ce-doped Gd2SiO5. For Ce-doped GPS, the decay rate was slower for the host excitation than that for direct excitation of Ce3+. In contrast, for Ce and La-doped GPS, no significant difference was observed for the host excitation and direct excitation of Ce3+. This result indicated that the energy transfer from the host to Ce3+ions led to a different radiative decay process, and that La doping had an effect on the energy transfer and decay process.

  4. Signature splitting in 129Ce

    Institute of Scientific and Technical Information of China (English)

    LIU Ying; WU Xiao-Guang; ZHU Li-Hua; LI Guang-Sheng; HE Chuang-Ye; LI Xue-Qin; PAN Bo; HAO Xin; LI Li-Hua; WANG Zhi-Min; LI Zhong-Yu; XU Qiang

    2009-01-01

    The high spin states of 129Ce have been populated via heavy-ion fusion evaporation reaction 96Mo (37C1, 1p3n) 129Ce. The γ-γ coincidence and intensity balance used to measure the B(M1; I→I-1)/B(E2; I→I-2) (the probability ratio of the dipole and quadrupole transition) in v7/2[523] rotational band of 129Ce. And the energy splitting (Δe') has been got through the experimental Routhians. The lifetimes and quadrupole moments Qt have been extracted from the lineshape analyses using DSAM. The deformation of the v7/2[523] rotational band of 129Ce was extracted from the Qt and moment of inertia JRR.

  5. Improved sulfur-resistant ability on CO oxidation of Pd/Ce0.75Zr0.25O2 over Pd/CeO2-TiO2 and Pd/CeO2

    Institute of Scientific and Technical Information of China (English)

    沈美庆; 林放; 魏光曦; 王建强; 朱少春

    2015-01-01

    The influence of sulfation on Pd/Ce0.75Zr0.25O2, Pd/CeO2-TiO2 and Pd/CeO2 was investigated. Physical structure and chemical properties of different catalysts were characterized by N2 adsorption, X-ray diffraction (XRD), CO chemisorption, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and X-ray fluorescence (XRF). After 10 h SO2 sulfation, it was found that the decrement on CO oxidation catalytic activity was limited on Pd/Ce0.75Zr0.25O2 compared to Pd/CeO2-TiO2 and Pd/CeO2. It demonstrated that Pd/Ce0.75Zr0.25O2 was more sulfur resistant compared to the other two catalysts. Af-ter sulfur exposure, catalyst texture was not much influenced as shown by N2 adsorption and XRD, and surface Pd atoms were poi-soned indicated by CO chemisorption results. Pd/Ce0.75Zr0.25O2 and Pd/CeO2-TiO2 exhibited less sulfur accumulation compared to Pd/CeO2 in the sulfation process. Furthermore, XPS results clarified that surface sulfur amount, especially surface sulfates amount on the sulfated catalysts was more crucial for the deactivation in sulfur containing environment.

  6. Dissolution of Ce from Cd Solution Containing U/Ce Elements by Electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Si Hyung; Kim, Gha-Young; Lee, Seung-jai; Kim, Taek-Jin; Paek, Seungwoo; Ahn, Do-Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    The U-TRU metal alloy can be supplied by the Pyroprocessing, specifically UTRU recovery process using liquid cadmium cathode (LCC). In a certain case, a lot of rare earth (RE) element could be recovered on the LCC with the TRU element during the Pyroprocessing when the concentration of RE ions is higher than that of the TRU ions in the salt. In this case, most of the RE element needs to be removed from the Cd solution containing U/TRU/RE elements. RAR(Residual Actinides Recovery) technique used the mixed electrolytic-chemical process. In this study, only electrolysis technique was utilized to remove Ce element from Cd solution containing U/Ce elements. U-TRU alloy having less impurity is necessary for the fabrication of SFR fuel and these U-TRU elements can be prepared by Pyroprocessing. Electrolytic method was used to reduce the amount of Ce elements from the Cd solution containing U/Ce elements. It is judged from this study that electrolytic dissolution can be one of the methods to reduce RE elements from the Cd solution containing U-TRU-RE elements.

  7. Cost objective PLM and CE

    CERN Document Server

    Perry, Nicolas

    2010-01-01

    Concurrent engineering taking into account product life-cycle factors seems to be one of the industrial challenges of the next years. Cost estimation and management are two main strategic tasks that imply the possibility of managing costs at the earliest stages of product development. This is why it is indispensable to let people from economics and from industrial engineering collaborates in order to find the best solution for enterprise progress for economical factors mastering. The objective of this paper is to present who we try to adapt costing methods in a PLM and CE point of view to the new industrial context and configuration in order to give pertinent decision aid for product and process choices. A very important factor is related to cost management problems when developing new products. A case study is introduced that presents how product development actors have referenced elements to product life-cycle costs and impacts, how they have an idea bout economical indicators when taking decisions during t...

  8. s-Processing in the Galactic Disk. I. Super-Solar Abundances of Y, Zr, La, Ce in Young Open Clusters

    CERN Document Server

    Maiorca, E; Busso, M; Magrini, L; Palmerini, S

    2011-01-01

    In a recent study, based on homogeneous barium abundance measurements in open clusters, a trend of increasing [Ba/Fe] ratios for decreasing cluster age was reported. We present here further abundance determinations, relative to four other elements hav- ing important s-process contributions, with the aim of investigating whether the growth found for [Ba/Fe] is or not indicative of a general property, shared also by the other heavy elements formed by slow neutron captures. In particular, we derived abundances for yttrium, zirconium, lanthanum and cerium, using equivalent widths measurements and the MOOG code. Our sample includes 19 open clusters of different ages, for which the spectra were obtained at the ESO VLT telescope, using the UVES spectrometer. The growth previously suggested for Ba is confirmed for all the elements analyzed in our study. This fact implies significant changes in our views of the Galactic chemical evolution for elements beyond iron. Our results necessarily require that very low-mass AGB...

  9. Morphology-dependent bactericidal activities of Ag/CeO2 catalysts against Escherichia coli.

    Science.gov (United States)

    Wang, Lian; He, Hong; Yu, Yunbo; Sun, Li; Liu, Sijin; Zhang, Changbin; He, Lian

    2014-06-01

    Silver-loaded CeO2 nanomaterials (Ag/CeO2) including Ag/CeO2 nanorods, nanocubes, nanoparticles were prepared with hydrothermal and impregnation methods. Catalytic inactivation of Escherichia coli with Ag/CeO2 catalysts through the formation of reactive oxygen species (ROS) was investigated. For comparison purposes, the bactericidal activities of CeO2 nanorods, nanocubes and nanoparticles were also studied. There was a 3-4 log order improvement in the inactivation of E. coli with Ag/CeO2 catalysts compared with CeO2 catalysts. Temperature-programmed reduction of H2 showed that Ag/CeO2 catalysts had higher catalytic oxidation ability than CeO2 catalysts, which was the reason for that Ag/CeO2 catalysts exhibited stronger bactericidal activities than CeO2 catalysts. Further, the bactericidal activities of CeO2 and Ag/CeO2 depend on their shapes. Results of 5,5-dimethyl-1-pyrroline-N-oxide spin-trapping measurements by electron spin resonance and addition of catalase as a scavenger indicated the formation of OH, O2(-), and H2O2, which caused the obvious bactericidal activity of catalysts. The stronger chemical bond between Ag and CeO2 nanorods led to lower Ag(+) elution concentrations. The toxicity of Ag(+) eluted from the catalysts did not play an important role during the bactericidal process. Experimental results also indicated that Ag/CeO2 induced the production of intracellular ROS and disruption of the cell wall and cell membrane. A possible production mechanism of ROS and bactericidal mechanism of catalytic oxidation were proposed.

  10. CE-SAM: a conversational interface for ISR mission support

    Science.gov (United States)

    Pizzocaro, Diego; Parizas, Christos; Preece, Alun; Braines, Dave; Mott, David; Bakdash, Jonathan Z.

    2013-05-01

    There is considerable interest in natural language conversational interfaces. These allow for complex user interactions with systems, such as fulfilling information requirements in dynamic environments, without requiring extensive training or a technical background (e.g. in formal query languages or schemas). To leverage the advantages of conversational interactions we propose CE-SAM (Controlled English Sensor Assignment to Missions), a system that guides users through refining and satisfying their information needs in the context of Intelligence, Surveillance, and Reconnaissance (ISR) operations. The rapidly-increasing availability of sensing assets and other information sources poses substantial challenges to effective ISR resource management. In a coalition context, the problem is even more complex, because assets may be "owned" by different partners. We show how CE-SAM allows a user to refine and relate their ISR information needs to pre-existing concepts in an ISR knowledge base, via conversational interaction implemented on a tablet device. The knowledge base is represented using Controlled English (CE) - a form of controlled natural language that is both human-readable and machine processable (i.e. can be used to implement automated reasoning). Users interact with the CE-SAM conversational interface using natural language, which the system converts to CE for feeding-back to the user for confirmation (e.g. to reduce misunderstanding). We show that this process not only allows users to access the assets that can support their mission needs, but also assists them in extending the CE knowledge base with new concepts.

  11. Preparation and characterization of CNT-CeO{sub 2} nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Jasmeet, E-mail: jasmeet.dayal@gmail.com; Anand, Kanika; Singh, Ravi Chand [Department of Physics, Guru Nanak Dev University, Amritsar-143005 (India)

    2015-06-24

    This paper reports decoration of CeO{sub 2} nanoparticles on multi-walled carbon nanotubes through a reflux process in which Ce (NO{sub 3}) {sub 3}·6H{sub 2}O serves as precursor and hydrazine hydrate (N{sub 2}H{sub 4}.H{sub 2}O) as reducing agent. Successful deposition of cubic fluorite CeO{sub 2} nanoparticles onto multi-walled carbon nanotubes has been confirmed by x-ray diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM) and energy dispersive x-ray spectroscopy (EDS). It was found that CeO{sub 2} nanoparticles formed in the presence of CNTs were larger as compared to pure CeO{sub 2} nanoparticles. Raman analysis showed that CeO{sub 2} induced a decrease in the size of the carbon grain in the CNTs. A red shift from 460 cm{sup −1} to 463 cm{sup −1} for F{sub 2g} mode of CeO{sub 2} has also been observed in Raman spectra of CNT- CeO{sub 2} nanocomposite as compared to pure CeO{sub 2}. The CeO{sub 2} coated multi-wall carbon nanotubes (CNT-CeO{sub 2}) nanocomposite would be a promising candidate for practical applications such as catalysis, sensing and power source applications.

  12. RESONANT PHOTOEMISSION OF BULK CeO2 AND NANO—CeO2 FILMS

    Institute of Scientific and Technical Information of China (English)

    M.I.Abbas; K.Ibrahim; Z.Y.Wu; J.Zhang; F.Q.Liu; H.J.Qian

    2001-01-01

    Photoemission behaviors of nano-CeO2 films with parlicle sizes ranging from 8nm to 50nm and bulk CeO2 in Ce 4d-4f absorption region have been investigated.Resonant enhancements of Ce 4f valance band and Ce 5p bands for nano film and bulk material have been observed.The variation of electron density of Ce 4d-4f resonace.

  13. Electrochemical behavior of Ce(Ⅲ) in LiF-BaF2 melts

    Institute of Scientific and Technical Information of China (English)

    LIN Rushan; YE Guoan; HE Hui; TANG Hongbin; OUYANG Yinggen

    2012-01-01

    The electrochemical behavior of Ce(Ⅲ) was investigated in the molten LiF-BaF2 (81 mo1.%-19 mol.%) on a molybdenum elec-trode in the temperature range of 1098-1188 K using cyclic voltammetry and chronopotentiometry.It was observed that CeF3 could be reduced into cerium metal in a reversible one-step process exchanging three electrons (Ce(Ⅲ)+3e-→,Ce(0)) at the operating temperatures on amolybdenum cathode.The electrochemical reduction process was controlled by the diffusion of Ce(Ⅲ) in the solution.The Ce(Ⅲ) diffusion coefficients were calculated at different temperatures and the values obeyed the Arrhenius law with an activation energy of 87.5 kJ/mol.

  14. 3CE Methodology for Conducting a Modeling, Simulation, and Instrumentation Tool Capability Analysis

    Science.gov (United States)

    2010-05-01

    System Design System Dev DT&E IOT &E Operations 3CE – Core Products Process & Procedures Data Toolbox 3CE Network TRADOC RDECOMATEC 3CE...JCS COCOM FCB Strategic Guidance Materiel Solution Analysis ICD MDD Technology Opportunities & Resources AOA LiveVirtual Constructive Concept Dev ... DEV , DTE, SIMEX, LUT, L-V-C, etc… • Research Requirements •Test Requirements •Training Requirements • PM Requirements Source of Requirements

  15. CeOHCO3和CeO2束状纳米结构的制备及表征%Preparation and Characterization of Crystalline CeOHCO3 and CeO2 with Bundle-like Nanostructures

    Institute of Scientific and Technical Information of China (English)

    张晓娟; 张胜义; 田玉鹏; 金葆康; 吴杰颖

    2008-01-01

    The cantaloupe-like particles of CeOHCO3 were synthesized in aqueous solution by using cetyhrimethylammonium bromide (CTAB) as soft template. Then, the bunchiness rods of CeO2 were obtained by calcining CeOHCO3 at 450 ℃. The results of thermogravimetric/differential thermal analysis reveal that an endothermic reaction with decomposition is involved in the transformation process from CeOHCO3 to CeO2. By scanning electron microscopy and X-ray diffraction analysis, it is found that the orthorhombic phase CeOHCO3 particles are constituted of short nanorods with diameters ranging from several tens nm to over 100 nm, and the cubic phase CeO2 rods are composed of small particles with diameter ca. 15 nm. From the results of UV-Vis absorption and photoluminescence analysis, it is found that the CeO2 possess abundant defects, and the band gaps of the CeO2 and CeOHCO3 are ca. 2.70 eV and 3.87 eV, respectively.

  16. Mesoporous CeTiSiMCM-48 as novel photocatalyst for degradation of organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Mureseanu, Mihaela, E-mail: mihaela_mure@yahoo.com [Faculty of Chemistry, University of Craiova, 107 I Calea Bucureşti, 200478 Craiova (Romania); Parvulescu, Viorica, E-mail: vpirvulescu@icf.ro [“Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Radu, Teodora, E-mail: teocluj@gmail.com [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Street, 400293 Cluj Napoca (Romania); Institute of Interdisciplinary Research in Bio-Nano-Sciences, Babes Bolyai University, 400271 Cluj-Napoca (Romania); Filip, Mihaela [“Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Carja, Gabriela, E-mail: carja@uaic.ro [Faculty of Chemical Engineering and Environmental Protection, Technical University of Iasi, 71 D. Mangeron, Iasi (Romania)

    2015-11-05

    This work presents novel photocatalysts containing Ti and/or Ce embedded in the mesoporous silica framework (TiSiMCM-48, CeSiMCM-48 and CeTiSiMCM-48) that were prepared via a facile sol–gel process in the presence of ionic structure directing agents. The structural properties of the obtained materials were analyzed by X-ray diffraction (XRD), nitrogen adsorption-desorption, scanning and transmission electron microscopy (SEM, TEM), EDAX analysis, X-ray photoelectron microscopy (XPS), ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS) and Fourier transformation infrared spectroscopy (FT-IR). The results indicated that Ce and Ti were highly dispersed or incorporated into the framework of the cubic SiMCM-48, with an enhanced light-trapping effect both in the UV and Vis regions. When applied to the photocatalytic degradation of phenol, the best results were obtained for the bimetallic hybrid. The best activity of CeTiSiMCM-48 photocatalyst was ascribed to improved electron–hole pair separation efficiency and formation of more reactive oxygen species due to the presence of Ce{sup 4+}/Ce{sup 3+}. The mesoporous support increases the dispersability of the photoactive Ti{sup 4+} or Ce{sup 4+}/Ce{sup 3+} species on the catalyst surface and the accessibility of the substrate to the active sites. Furthermore, the catalysts can be easily recovered and reused for four cycles without significant loss of activity. - Highlights: • Novel photocatalysts containing Ti and/or Ce embedded in the mesoporous MCM-48 silica. • Ce{sup 4+}/Ce{sup 3+} improved electron–hole pair separation and reactivity of oxygen species. • The mesoporous support increases the dispersability of the photoactive species. • The photocatalyst was highly active and stable for phenol degradation under UV irradiation. • TiCeSiMCM-48 can be recycled up to four cycles without significant loss of activity.

  17. Single-Crystalline CeOHCO3 with Rhombic Morphology:Synthesis and Thermal Conversion to CeO2%单晶菱形CeOHCO3片状物的制备及其向CeO2的热转换

    Institute of Scientific and Technical Information of China (English)

    张泽芳; 俞磊; 刘卫丽; 宋志棠

    2011-01-01

    Single-crystalline CeOHCO3 rhombic micro-plates with an orthorhombic structure were synthesized by the precipitation reaction between (NH4)2Ce(NO3)6 and CO(NH)2 in the presence of 3-aminopropyltriethoxysilane (APS). Polycrystalline CeO2 rhombic micro-plates were prepared by thermal decomposition of single-crystalline CeOHCO3 rhombic micro-plates at 600 ℃ in air. CeOHCO3 and CeO2 rhombic micro-plates were characterized by XRD, filed-emission scanning electron microscopy (FESEM), TEM, and XPS. The results indicate that APS plays an important role in the preparation of single-crystalline CeOHCO3 rhombic micro-plates because the CeO2 is produced without APS. In addition, the rhombic shape of the products is not ruined apparently by the thermal conversion process from CeOHCO3 to CeO2.%以硝酸铈铵和尿素为反应物,γ-氨丙基三乙氧基硅烷(KH550)为助剂,通过沉淀反应制得了单晶菱形CeOHCO3片状物.然后将CeOHCO3在600℃空气气氛中灼烧获得了菱形CeO2.通过XRD和SEM对反应物中是否含有KH550助剂所得的产物进行了分析,结果发现只有含有KH550才能获得菱形CeOHCO3片状物,并且在灼烧过程中产物的形貌仍保持菱形.然后采用TEM对菱形CeOHCO3和CeO2进行了表征,结果发现CeOHCO3为单晶产物而灼烧后所得的CeO2为多晶产物.

  18. Effects of CeF3 on properties of self-shielded flux cored wire

    Institute of Scientific and Technical Information of China (English)

    Yu Ping; Tian Zhiling; Pan Chuan; Xue Jin

    2006-01-01

    Effects of CeF3 on properties of self-shielded flux cored wire including welding process, inclusions in weld metal and mechanical properties are systematically studied. Welding smoke and spatter are reduced with the addition of CeF3. The main non-metallic inclusions in weld metal are AlN and Al2 O3. CeF3 can refine non-metallic inclusions and reduce the amount of large size inclusions, which is attributed to the inclusion floating behavior during the solidification of weld metal. The low temperature impact toughness is improved by adding suitable amount of CeF3 in the flux.

  19. RESONANT PHOTOEMISSION OF BULK CeO2 AND NANO-CeO2 FILMS

    Institute of Scientific and Technical Information of China (English)

    M.I. Abbas; K. Ibrahim; Z.Y. Wu; J. Zhang; F.Q. Liu; H.J. Qian

    2001-01-01

    Photoemission behaviors of nano-CeO2 films with particle sizes ranging from 8nm 1o50nm and bulk CeO2 in Ce 4d-4f absorption region have been investigated. Resonantenhancements of Ce 4f valance band and Ce 5p bands for nano film and bulk materialhave been observed. The variation of electron density of states in valance bands ofnano and bulk structures of CeO2 is discussed in terms of Ce 4d-4f resonance.

  20. Ce que permet le document

    OpenAIRE

    2012-01-01

    Avec l’archive, à laquelle il est souvent associé, le document occupe une place centrale dans les expositions comme dans les publications actuelles sur l’art contemporain. Les présents ouvrages n’ont pas pour objectif d’apporter un éclairage à ce vaste tournant mnémonique qui semble s’emparer des pratiques et des discours sur l’art depuis le début de ce troisième millénaire, même si les contributions de certains de leurs auteurs pointent des éléments conjoncturels (l’après 11 septembre) ou te...

  1. Ce isotope systematics of island arc lavas from the Lesser Antilles

    Science.gov (United States)

    Bellot, Nina; Boyet, Maud; Doucelance, Régis; Pin, Christian; Chauvel, Catherine; Auclair, Delphine

    2015-11-01

    ., 1987; Shimizu et al., 1992). The 138Ce/142Ce ratios of the two chondrites are identical within uncertainty and similar to previous determinations done on other meteorites; the average value is 0.0225654 ± 7 (2 s.d. = 32 ppm). Martinique samples show a limited but significant range of variations for 138Ce/142Ce ratios (∼2 ε-units). The latter ratios correlate well with the Nd isotopes and define a binary mixing between a depleted mantle and subducted sediments that could be similar to those drilled at DSDP-site 144 (Leg 14). The Martinique lavas do not define a single curve in the εCe vs. εNd diagram, but a band. The apparent scattering can be explained by the involvement of sediments with different Ce isotope compositions and/or variations in the melting process itself such as the effect of melting on the light rare earth element ratios. The Ce isotopic signature of Martinique samples is dominated by the contribution of old terrigeneous sediments. However, according to our mixing models a low contribution of a few percent of marine sediment material in the source of the lavas is undetectable and therefore cannot be definitely excluded. Although the participation of marine sediments in this arc system is not demonstrated, our calculations show that the La-Ce system has a potential as geochemical tracer despite its very long half-life.

  2. An Update on NiCE Support for BISON

    Energy Technology Data Exchange (ETDEWEB)

    McCaskey, Alex [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Billings, Jay Jay [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Deyton, Jordan H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wojtowicz, Anna [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-09-01

    The Nuclear Energy Advanced Modeling and Simulation program (NEAMS) from the Department of Energy s Office of Nuclear Energy has funded the development of a modeling and simulation workflow environment to support the various codes in its nuclear energy scientific computing toolkit. This NEAMS Integrated Computational Environment (NiCE) provides extensible tools and services that enable efficient code execution, input generation, pre-processing visualizations, and post-simulation data analysis and visualization for a large portion of the NEAMS Toolkit. A strong focus for the NiCE development team throughout FY 2015 has been support for the Multiphysics Object Oriented Simulation Environment (MOOSE) and the NEAMS nuclear fuel performance modeling application built on that environment, BISON. There is a strong desire in the program to enable and facilitate the use of BISON throughout nuclear energy research and industry. A primary result of this desire is the need for strong support for BISON in NiCE. This report will detail improvements to NiCE support for BISON. We will present a new and improved interface for interacting with BISON simulations in a variety of ways: (1) improved input model generation, (2) embedded mesh and solution data visualizations, and (3) local and remote BISON simulation launch. We will also show how NiCE has been extended to provide support for BISON code development.

  3. ZrCoCe Getter Films for MEMS Vacuum Packaging

    Science.gov (United States)

    Xu, Yaohua; Cui, Jiandong; Cui, Hang; Zhou, Hao; Yang, Zhimin; Du, Jun

    2016-01-01

    In order to specifically support the technology trend of increased miniaturization of micro electro mechanical systems (MEMS) devices, highly porous ZrCoCe non-evaporable getter (NEG) film has been produced by direct current magnetron sputtering from a preformed ZrCoCe alloy target. Scanning electron microscopy and x-ray diffraction analysis indicated that the ZrCoCe film is constructed with porous columnar crystals, which are further built up with assembled ZrCoCe amorphous or nanocrystalline grains with an average grain size of 5 nm. Gas sorption investigation shows that this film can be activated at a low temperature of 300°C for 30 min and has excellent stable sorption characteristics. Sorption properties can be further improved with elevating activation temperatures due to nanocrystals growing and amorphous regions crystallizing. The capability of ZrCoCe films to withstand wafer physical or chemical cleaning processes is investigated, indicating their compatibility with MEMS vacuum packaging and the appropriate way to store them.

  4. Effect of Ce2O3 on Structure, Viscosity, and Crystalline Phase of CaO-Al2O3-Li2O-Ce2O3 Slags

    Science.gov (United States)

    Qi, Jie; Liu, Chengjun; Zhang, Chi; Jiang, Maofa

    2017-02-01

    Aiming at devising new mold flux for Ce-bearing stainless steel, a fundamental investigation on the effect of Ce2O3 on properties of the CaO-Al2O3-Li2O-Ce2O3 slag was provided by the present work. The results show that adding Ce2O3 could decrease the viscosity of the slag due to its effects on decreasing the polymerization of the slag. The crystalline process was restrained by increasing the content of Ce2O3, and the crystalline phases also can be influenced by the slag structure. The crystalline phases were transferred from LiAlO2 and CaO to LiAlO2 and CaCeAlO4 with the addition of Ce2O3 to the slag, which could be well confirmed by the structure of the unit cell of the crystals.

  5. Preparation and Characterization of Graphite Powder Covered with CeO2

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In order to improve the wetting properties of graphite with Al melt and reduce the oxidation of the graphite, by which the segregation of components during the liquid-stir-casting process could be prevented. In this paper, a uniform thin nano-film of CeO2, about 20 nm thick, was successfully prepared onto graphite powder surface by heterogeneous nucleation process. The results show that an obvious chemical reaction did exit between CeO2 film and graphite with the formation of Ce-O-C bond, leading to a shift of the binding energy of C and Ce. The cover with CeO2 film illustrates a distinct change of surface state of graphite with a decrease of angle of contact.

  6. Characterization of Pr-CeO2 Nano-crystallites Prepared by Low-temperature Combustion & Hydrothermal Synthesis

    Institute of Scientific and Technical Information of China (English)

    ZHU Zhen-Feng; WANG Bao-Li; MA Jian-Zhong

    2006-01-01

    Pr-CeO2 Nano-crystalline red pigments were prepared by low-temperature combustion with a later hydrothermal treatment using Ce(NO3)3·6H2O and Pr6O11 as raw materials. The phase composition, coloring mechanism and morphology of pigments were analyzed by XRD, SEM,EDS and XPS. Results showed that Pr-CeO2 solid solution with a fluorite structure was obtained by the diffusion of Pr+3 into CeO2 crystal lattice during the synthesis process. XPS analysis indicated that Pr+3 substitutes Ce+4 in CeO2 and is compensated by oxygen vacancies. Compared with low-temperature combustion synthesis, the Pr-CeO2 pigments prepared with a subsequent hydrothermal treatment have an average grain size of about 16.70 nm, and the crystallinity and red tonality are improved.

  7. One-Pot Polyol Synthesis of Pt/CeO2 and Au/CeO2 Nanopowders as Catalysts for CO Oxidation.

    Science.gov (United States)

    Pilger, Frank; Testino, Andrea; Lucchini, Mattia Alberto; Kambolis, Anastasios; Tarik, Mohammed; El Kazzi, Mario; Arroyo, Yadira; Rossell, Marta D; Ludwig, Christian

    2015-05-01

    The facile one-pot synthesis of CeO2-based catalysts has been developed to prepare a relatively large amount of nanopowders with relevant catalytic activity towards CO oxidation. The method consists of a two-steps process carried out in ethylene glycol: in the first step, 5 nm well-crystallized pure CeO2 is prepared. In a subsequent second step, a salt of a noble metal is added to the CeO2 suspension and the deposition of the noble metal on the nanocrystalline CeO2 is induced by heating. Two catalysts were prepared: Pt/CeO2 and Au/CeO2. The as-prepared catalysts, the thermally treated catalysts, as well as the pure CeO2, are characterized by XRD, TGA, XPS, FTIR, HR-TEM, STEM, particle size distribution, and N2-physisorption. In spite of the identical preparation protocol, Au and Pt behave in a completely different way: Au forms rather large particles, most of them with triangular shape, easily identifiable and dispersed in the CeO2 matrix. In contrast, Pt was not identified as isolated particles. The high resolution X-ray diffraction carried out on the Pt/CeO2 thermally treated sample (500 degrees C for 1 h) shows a significant CeO2 lattice shrinkage, which can be interpreted as an at least partial incorporation of Pt into the CeO2 crystal lattice. Moreover, only Pt2+ and Pt4+ species were identified by XPS. In literature, the incorporation of Pt into the CeO2 lattice is supported by first-principle calculations and experimentally demonstrated only by combustion synthesis methods. To the best of our knowledge this is the first report where ionically dispersed Pt into the CeO2 lattice is obtained via a liquid synthesis method. The thermally treated Pt/CeO2 sample revealed good activity with 50% CO conversion at almost room temperature.

  8. A Study of the Kinetics of the Electrochemical Deposition of Ce3+/Ce4+ Oxides

    Science.gov (United States)

    Valov, I.; Guergova, Desislava; Stoychev, D.

    The kinetics of cathodic electrodeposition of Ce3+ and/or Ce4+ oxides from alcoholic electrolytes on gold substrates has been studied. It was found that, depending on the oxygen content in the CeCl3-based electrolyte, Ce2O3 (in oxygen atmosphere) or CeO2 (in an inert atmosphere), respectively, were obtained. XPS studies clearly separated the two valence states of Ce ions in the oxide layers. The microstructure of the coatings was analyzed by atomic force microscopy (AFM).

  9. Development of a phantom and assessment of (141)Ce as a surrogate radionuclide for flood field uniformity testing of gamma cameras.

    Science.gov (United States)

    Saxena, Sanjay Kumar; Kumar, Yogendra; Malpani, Basant; Rakshit, Sutapa; Dash, Ashutosh

    2016-06-01

    This paper describes an indigenous method for development and deployment of rechargeable liquid filled phantom with newly proposed radionuclide (141)Ce for determination of extrinsic uniformity of gamma cameras. Details about design of phantom, neutron irradiation of cerium targets, chemical processing of (141)Ce, charging of phantom with (141)Ce solution and their performance evaluation are presented. Suitability of (141)Ce in quality assurance of gamma cameras used in in-vivo diagnostic imaging procedures has been amply demonstrated.

  10. CuO/CeO2催化剂在温度变动过程中的CO-PROX催化性能%Catalytic Performance of CuO/CeO2 Catalyst for CO-PROX in Temperature-Varying Process

    Institute of Scientific and Technical Information of China (English)

    高志明; 宋晓媛; 马宏伟; 张强

    2016-01-01

    采用浸渍方法制备不同Cu/Ce原子比的CuO/CeO2催化剂,用于富氢气体中CO优先氧化反应(CO-PROX),考察其在温度变动情况下的催化性能.利用X射线衍射(XRD)、程序升温还原(TPR)方法对反应前后催化剂样品进行了表征.XRD测试表明,催化反应后的催化剂中有金属Cu0生成.这与文献结果一致.与不含CO2的情况比较,当模拟富氢气体中含有CO2时,低温段催化活性明显下降.Cu/Ce原子比为10%的催化剂在温度变动过程中具有较稳定的催化性能.

  11. Characteristics of 5 mol% Ce{sup 3+}-doped barium titanate nanowires prepared by a combined route involving sol–gel chemistry and polycarbonate membrane-templated process

    Energy Technology Data Exchange (ETDEWEB)

    Vasilescu, Catalina-Andreea [University POLITEHNICA of Bucharest, Department of Oxide Materials Science and Engineering (Romania); Trupina, Lucian [National Institute of Materials Physics (Romania); Vasile, Bogdan Stefan [University POLITEHNICA of Bucharest, Department of Oxide Materials Science and Engineering (Romania); Trusca, Roxana [S.C. METAV–Research & Development Bucharest (Romania); Cernea, Marin [National Institute of Materials Physics (Romania); Ianculescu, Adelina-Carmen, E-mail: a-ianculescu@yahoo.com [University POLITEHNICA of Bucharest, Department of Oxide Materials Science and Engineering (Romania)

    2015-11-15

    Ba{sub 0.95}Ce{sub 0.05}Ti{sub 0.9875}O{sub 3} nanowires were fabricated by sol–gel method using as template a polycarbonate membrane with channels of 100 nm diameter. FE-SEM analyses showed that continuous gel wires of length up to 17 µm and an average diameter of 81 nm, were obtained. After calcination at 700 °C for 1 h, these green 1D nanostructures were converted into well-crystallised wires with an average diameter of 59.7 nm, as high-resolution transmission electron microscopy and selected area electron diffraction indicated. The piezoelectric activity of the Ba{sub 0.95}Ce{sub 0.05}Ti{sub 0.9875}O{sub 3} nanowires was investigated using piezoresponse force microscopy (PFM) correlated with atomic force microscopy. The results of PFM measurements indicated that the wires exhibit a significant fraction of ferroelectric domains larger than the grains size and a good piezoelectric response.

  12. Investigation of chemical composition and crystal structure in sintered Ce15Nd15FebalB1 magnet

    Directory of Open Access Journals (Sweden)

    Shu-lin Huang

    2014-10-01

    Full Text Available The substitution of cerium, a more abundant rare-earth element, for sintered Nd-Fe-B magnets has drawn intense interest. In the present work, nominal composition of Ce15Nd15FebalB1 (wt. %, with cerium constitutes increased to 50% of the total rare-earth content, was used. And Ce-free Nd30FebalB1 (wt. % was prepared by the same preparation process as comparison. The microstructure of the sintered magnets has been investigated by means of X-ray diffraction and transmission electron microscope. The results show that there are three kinds of RE-rich phases in the same magnet, i.e., fcc-(Ce,NdOx (a=0.547nm, hcp-(Ce,Nd2O3 (a=0.386nm, c=0.604nm and bcc-(Ce,Nd2O3 (a=1.113nm. Ors of (140(Ce,Nd2Fe14B// (1-21bcc-(Ce,Nd2O3(∼3°, [001](Ce,Nd2Fe14B// [-214]bcc-(Ce,Nd2O3; (01-1(Ce,Nd2Fe14B// (101fcc- (Ce,NdOx(∼2°, [101](Ce,Nd2Fe14B// [12-1]fcc-(Ce,NdOx were found through selected area electron diffraction (SAED analysis. According to the analysis, it can be concluded that cerium has partly substituted for neodymium by occupying the corresponding atom sites in the Ce15Nd15FebalB1 magnet, without changing the crystal configuration.

  13. Synthesis and Characterization of Ce-Doped Y3Al5O12 (YAG:Ce Nanopowders Used for Solid-State Lighting

    Directory of Open Access Journals (Sweden)

    Do Ngoc Chung

    2014-01-01

    Full Text Available Nano-Ce-doped Y3Al5O12 (YAG:Ce powders were synthesized by using a sol-gel low temperature combustion method, followed by thermal annealing. The annealing temperature for enriching nanoparticles was optimized and found to be 1000°C. The process for enriching uniform nanoparticles of YAG:Ce powder was carried out by using the nanosteam technique (NST. The nanoparticles obtained from this NST treatment had a size in the range of 9–20 nm. Measurements of the photoluminescence spectra of the dispersed YAG:Ce nanoparticles solutions showed a blue shift in the photoemission with a value of ca. 10 nm in the green region. WLEDs made from the blue LED chip coated with the nano-YAG:Ce + MEH-PPV composite epoxy exhibit white light with a broad band luminescent spectrum and a high color rending index (CRI. The photoluminescence spectra of the YAG:Ce nanoparticles showed a potential application of the prepared nanostructured YAG:Ce phosphor not only in energy-efficient solid-state lighting, but also in optoelectronic devices, including organic composite solar cells. In addition, it is suggested that NST can be applied for the enrichment of uniform inorganic nanoparticles.

  14. Comparison of Efficiencies and Mechanisms of Catalytic Ozonation of Recalcitrant Petroleum Refinery Wastewater by Ce, Mg, and Ce-Mg Oxides Loaded Al2O3

    Directory of Open Access Journals (Sweden)

    Chunmao Chen

    2017-02-01

    Full Text Available The use of catalytic ozonation processes (COPs for the advanced treatment of recalcitrant petroleum refinery wastewater (RPRW is rapidly expanding. In this study, magnesium (Mg, cerium (Ce, and Mg-Ce oxide-loaded alumina (Al2O3 were developed as cost efficient catalysts for ozonation treatment of RPRW, having performance metrics that meet new discharge standards. Interactions between the metal oxides and the Al2O3 support influence the catalytic properties, as well as the efficiency and mechanism. Mg-Ce/Al2O3 (Mg-Ce/Al2O3-COP reduced the chemical oxygen demand by 4.7%, 4.1%, 6.0%, and 17.5% relative to Mg/Al2O3-COP, Ce/Al2O3-COP, Al2O3-COP, and single ozonation, respectively. The loaded composite metal oxides significantly increased the hydroxyl radical-mediated oxidation. Surface hydroxyl groups (–OHs are the dominant catalytic active sites on Al2O3. These active surface –OHs along with the deposited metal oxides (Mg2+ and/or Ce4+ increased the catalytic activity. The Mg-Ce/Al2O3 catalyst can be economically produced, has high efficiency, and is stable under acidic and alkaline conditions.

  15. Local structure of the Ce3+ ion the yellow emitting phosphor YAG:Ce

    NARCIS (Netherlands)

    Ghigna, P.; Pin, S.; Ronda, C.; Speghini, A.; Piccinelli, F.; Bettinelli, M.

    2011-01-01

    The local structure of the Ce3+ ion in the yellow emitting YAG:Ce phosphor has been studied by Extended X-ray Absorption Fine Structurespectroscopy in the 300−20 K temperature range. It has evidenced that the dopant Ce3+ replaces Y3+ in the garnet structure, giving rise to a significant expan

  16. Preparation and characterization of Cu-Ce-La mixed oxide as water-gas shift catalyst for fuel cells application

    Institute of Scientific and Technical Information of China (English)

    ZHI Keduan; LIU Quansheng; ZHAO Ruigang; HE Runxia; ZHANG Lifeng

    2008-01-01

    Cu-Ce-La mixed oxides were prepared by three precipitation methods (coprecipitation, homogeneous precipitation, and deposition precipitation) with variable precipitators and characterized using X-ray diffraction, BET, temperature-programmed reduction, and catalytic reaction for the water-gas shift. The Cu-Ce-La mixed oxide prepared by coprecipitation method with NaOH as precipitator presented the highest activity and thermal stability. Copper ion substituted quadrevalent ceria entered CeO2 (111) framework was in favor of activity and thermal stability of catalyst. The crystallinity of fresh catalysts increased with the reduction process. La3+ or Ce4+ substituted copper ion entered the CeO2 framework during reduction process. The coexistence of surface copper oxide (crystalline) and pure bulk crystalline copper oxide both contributed to the high activity and thermal stability of Cu-Ce-La mixes oxide catalyst.

  17. Structural characterization and corrosive property of Ni-P/CeO2composite coating

    Institute of Scientific and Technical Information of China (English)

    JIN Huiming; JIANG Shihang; ZHANG Linnan

    2009-01-01

    Electroless Ni-P/nano-CeO2 composite coating was prepared in acidic condition, and its microstructure and corrosive property were compared with its CeO2-free counterpart. Scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), X-ray diffraction spectrometer (XRD), and differential scanning calorimeter (DSC) were used to examine surface morphology and microstructure of the coating. Corrosive investigation was carried out in 3%NaCl+5%H2SO4 solution. The results showed that Ni-P coating had partial amorphous structure mixed with nanocrystals, whereas the Ni-P/CeO2 coating had perfect amorphous structure. In high temperature condition, Ni3P precipitation and Ni crystallization occurred in both coatings but at different temperatures, whereas the Ni-P/CeO2 coating had sintered phase of NiCe2O4 spinels. The anticorrosion property and passivity were improved in the CeO2-containing coating due to its less liability to undergo local-cell corrosion than its CeO2-free counterpart. During the co-deposition process, some Cen+ (n=3, 4) ions may be adsorbed to the metal/solution interface, hinder nickel's crystal-typed deposition and promote phosphorous deposition. The nano-CeO2 doping finally resulted in the coating' perfect amorphous structure and good anti-corrosive property.

  18. Design of an ultrasmall Au nanocluster-CeO2 mesoporous nanocomposite catalyst for nitrobenzene reduction.

    Science.gov (United States)

    Chong, Hanbao; Li, Peng; Xiang, Ji; Fu, Fangyu; Zhang, Dandan; Ran, Xiaorong; Zhu, Manzhou

    2013-08-21

    In this work we are inspired to explore gold nanoclusters supported on mesoporous CeO2 nanospheres as nanocatalysts for the reduction of nitrobenzene. Ultrasmall Au nanoclusters (NCs) and mesoporous CeO2 nanospheres were readily synthesized and well characterized. Due to their ultrasmall size, the as-prepared Au clusters can be easily absorbed into the mesopores of the mesoporous CeO2 nanospheres. Owing to the unique mesoporous structure of the CeO2 support, Au nanoclusters in the Au@CeO2 may effectively prevent the aggregation which usually results in a rapid decay of the catalytic activity. It is notable that the ultrasmall gold nanoclusters possess uniform size distribution and good dispersibility on the mesoporous CeO2 supports. Compared to other catalyst systems with different oxide supports, the as-prepared Au nanocluster-CeO2 nanocomposite nanocatalysts showed efficient catalytic performance in transforming nitrobenzene into azoxybenzene. In addition, a plausible mechanism was deeply investigated to explain the transforming process. Au@CeO2 exhibited efficient catalytic activity for reduction of nitrobenzene. This strategy may be easily extended to fabricate many other heterogeneous catalysts including ultrasmall metal nanoclusters and mesoporous oxides.

  19. Low-temperature solution synthesis and characterization of Ce-doped YAG nanoparticles

    Institute of Scientific and Technical Information of China (English)

    吉成; 冀立宇; 连刘超; 沈丽明; 张晓艳; 王一峰

    2015-01-01

    Monophasic Ce3+-doped yttrium aluminum garnet (Ce:YAG) nanoparticles with high crystallinity and tunable grain size ranging from ~19–30 nm were prepared by a modified co-precipitation process with a follow-up calcination treatment. For the syn-thesis, aluminum, yttrium, and cerium nitrates were used as starting materials, ammonium sulfate as dispersant, and a combination of ammonium bicarbonate and ammonia as precipitating agent. Influence of precipitation temperature, the pH value of precipitant solu-tions, aging period, calcination conditions, and Ce-doping level were investigated for controlling the purity, particle size, and photo-luminescence performance of the Ce:YAG nanoparticles. High-purity YAG nanoparticles were prepared at pH=10.50–11.00 and cal-cination temperatures of 850–1100 ºC with a calcination time of 3 h. With increasing Ce3+ concentration, the peak in the emission spectra of the obtained nanopowders shifted from 529 nm for the 0.67 wt.%-Ce:YAG to 544 nm for the 3.4 wt.%-Ce:YAG, while the strongest photoluminescence intensity was observed for the 1.3 wt.%-Ce:YAG nanoparticles.

  20. The role of Ce(III) in BZ oscillating reactions

    Science.gov (United States)

    Nogueira, Paulo A.; Varela, Hamilton; Faria, Roberto B.

    2012-03-01

    Herein we present results on the oscillatory dynamics in the bromate-oxalic acid-acetone-Ce(III)/Ce(IV) system in batch and also in a CSTR. We show that Ce(III) is the necessary reactant to allow the emergence of oscillations. In batch, oscillations occur with Ce(III) and also with Ce(IV), but no induction period is observed with Ce(III). In a CSTR, no oscillations were found using a freshly prepared Ce(IV), but only when the cerium-containing solution was aged, allowing partial conversion of Ce(IV) to Ce(III) by reaction with acetone.

  1. Evaluation of critical distances for energy transfer between Pr3+ and Ce3+ in yttrium aluminium garnet

    Science.gov (United States)

    Zeng, Peng; Wei, Xiantao; Zhou, Shaoshuai; Yin, Min; Chen, Yonghu

    2016-09-01

    A series of Pr3+/Ce3+ doped yttrium aluminium garnet (Y3Al5O12 or simply YAG) phosphors were synthesized to investigate the energy transfer between Pr3+ and Ce3+ for their potential application in a white light-emitting diode and quantum information storage and processing. The excitation and emission spectra of YAG:Pr3+/Ce3+ were measured and analyzed, and it revealed that the reabsorption between Pr3+ and Ce3+ was so weak that it can be ignored, and the energy transfer from Pr3+ (5d) to Ce3+ (5d) and Ce3+ (5d) to Pr3+ (1D2) did occur. By analyzing the excitation and the emission spectra, the energy transfer from Pr3+ (5d) to Ce3+ (5d) and Ce3+ (5d) to Pr3+ (1D2) was examined in detail with an original strategy deduced from fluorescence dynamics and the Dexter energy transfer theory, and the critical distances of energy transfer were derived to be 7.9 Å and 4.0 Å for Pr3+ (5d) to Ce3+ (5d) and Ce3+ (5d) to Pr3+ (1D2), respectively. The energy transfer rates of the two processes of various concentrations were discussed and evaluated. Furthermore, for the purpose of sensing a single Pr3+ state with a Ce3+ ion, the optimal distance of Ce3+ from Pr3+ was evaluated as 5.60 Å, where the probability of success reaches its maximum value of 78.66%, and meanwhile the probabilities were evaluated for a series of Y3+ sites in a YAG lattice. These results will be of valuable reference for achievement of the optimal energy transfer efficiency in Pr3+/Ce3+ doped YAG and other similar systems.

  2. Effects of Ce on microstructures and mechanical properties of Mg-Zn-Ce alloys processed by reciprocating extrusion and low-temperature forward extrusion%Ce对往复挤压-低温正挤压Mg-Zn-Ce合金组织和力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    杨文朋; 郭学锋; 梁世何

    2015-01-01

    在Mg-6Zn合金中添加0.6%、1%和2% Ce(质量分数),联合往复挤压和低温正挤压细化Mg-Zn-Ce合金组织,利用X射线衍射、光学显微镜、扫描电镜和透射电镜分析合金中相组成和组织演化,测试合金的室温力学性能.结果表明:Mg-6Zn-0.6Ce合金中主要化合物为Mg4Zn7相,Mg-6Zn-1Ce和Mg-6Zn-2Ce合金中主要化合物为T-(MgZn)12Ce相.往复挤压合金经动态再结晶而细化,晶粒尺寸随Ce添加量增加而变小,分别为20.6μm、16.5 μm和9.1μm.低温正挤压时,合金再次发生动态再结晶而再次细化,晶粒尺寸分别为2.0 μm、8.6μm和1.9 μm.Mg-6Zn-0.6Ce合金力学性能最佳,屈服强度、抗拉强度和伸长率分别为266.4 MPa、312.4 MPa和12.8%.合金的优良性能是由细晶强化、颗粒强化和固溶强化的共同作用造成的.

  3. Spectroscopic analysis of LYSO:Ce crystals

    Science.gov (United States)

    Martins, A. F.; Carreira, J. F. C.; Rodrigues, J.; Sedrine, N. Ben; Castro, I. F. C.; Correia, P. M. M.; Veloso, J. F. C. A.; Rino, L.; Monteiro, T.

    2017-02-01

    Rare earth orthosilicates are among the most widely used scintillator materials in the last decades. Particularly, lutetium-yttrium oxyorthosilicate (LYSO) is known to exhibit great potentialities in the field of radiation detectors for medical imaging. Consequently, an in-depth knowledge of the material properties is of utmost interest for the mentioned applications. In this work the spectroscopic properties of commercial cerium doped lutetium-yttrium oxyorthosilicate crystals (LYSO:Ce) were investigated by Raman spectroscopy, steady state photoluminescence, photoluminescence excitation and time resolved photoluminescence. Site selective excitation was used under steady state (325 nm) and pulsed (266 nm) conditions to separately investigate the temperature dependence of the 5d → 4f Ce1 and Ce2 luminescence, allowing to establish the thermal quenching dependence of the Ce2 optical center. In the case of the Ce1 optical center, a luminescence quantum efficiency of 78% was obtained from 14 K to room temperature with 266 nm photon excitation.

  4. Machining Characteristics of Ce-ZrO2/CePO4 Ceramics

    Institute of Scientific and Technical Information of China (English)

    Yu Aibing; Tan Yefa; Yang Xiaoqiang

    2004-01-01

    Two-phase mixtures of Ce-ZrO2 and monazite-type CePO4 were fabricated. Drilling and grinding experiments were carried out to investigate the machining characteristics of Ce-ZrO2/CePO4 ceramics. The machined surfaces of ceramics and wear surfaces of drill bits were observed with scanning electron microscope. Material removals and grinding forces were measured. The transgranular fracture of CePO4 grains, intergranular fracture between ZrO2 and CePO4 grains, and ductile deformation of ceramics were observed on Ce-ZrO2/CePO4 machined surfaces. With the increase of CePO4 proportion to composites, drilling material removal rates increases and specific normal grinding forces decreases.There existed rapid wear of conventional metal cutting tool is caused by abrasive wear. The experimental results indicate that the weak interfaces and properties of Ce-ZrO2/CePO4 ceramics have influences on material removal and machinability.

  5. Preparation and Characterization of CeO2/YSZ/CeO2 Buffer Layers for YBCO Coated Conductors

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    CeO2 seed layer was deposited on rolling-assisted biaxially textured metal substrates by direct-current (DC) magnetron reactive sputtering. The effect of deposition temperature on epitaxial orientation of CeO2 thin films was examined. High quality CeO2 layers were achieved at deposition temperature from 750℃ to 850℃.Subsequently yttria-stabilized zirconia (YSZ) and CeO2 films were deposited to complete the buffer layer structure via the same process. The best samples exhibited a highly biaxial texture, as indicated by FWHM (full width half maximum) values in the range of 4°-5°, and 2°-4° for in-plane and out-of-plane orientations,respectively. Secondary ion mass spectrometer analysis confirmed the effective prevention of buffer layer against Ni and W metal interdiffusion. Atomic force microscope observations revealed a smooth, dense and crack-free surface morphology, which provided themselves as the good buffer structure to the YBa2Cu3O7-δ(YBCO) coated conductors.

  6. Hydrogen production from methane steam reforming over Ni on high surface area CeO2 and CeO2-ZrO supports synthesized by surfactant-assisted method

    Directory of Open Access Journals (Sweden)

    Sumittra Charojrochkul

    2006-11-01

    Full Text Available Methane steam reforming performances of Ni on high surface area (HSA CeO2 and CeO2-ZrO2 supports have been studied under solid oxide fuel cell (SOFC operating conditions. Their performances were compared to general Ni/CeO2, Ni/CeO2-ZrO2, and Ni/Al2O3. It was firstly observed that Ni/CeO2-ZrO2 (HSA with the Ce/Zr ratio of 3/1 showed the best performance in terms of activity and stability toward the methane steam reforming among those with the Ce/Zr ratios of 1/1, 1/3, and 3/1. Both Ni/CeO2-ZrO2 (HSA and Ni/CeO2 (HSA presented better resistance toward carbon formation than the general Ni/CeO2, Ni/CeO2- ZrO2, and Ni/Al2O3 at the same operating conditions. These benefits are related to the high oxygen storage capacity (OSC of CeO2-ZrO2. During the steam reforming process, in addition to the reactions on Ni surface (*, the redox reactions between the gaseous components presented in the system and the lattice oxygen (Ox on CeO2-ZrO2 surface also take place. Among these reactions, the redox reactions between the high carbon formation potential compounds (CH4, CHx-*n and CO and the lattice oxygen (Ox can prevent the formation of carbon species from the methane decomposition and Boudard reactions at the inlet H2O/CH4 ratio of 3.0/1.0.

  7. Smart epoxy coating containing Ce-MCM-22 zeolites for corrosion protection of Mg-Li alloy

    Science.gov (United States)

    Wang, Yanli; Zhu, Yanhao; Li, Chao; Song, Dalei; Zhang, Tao; Zheng, Xinran; Yan, Yongde; Zhang, Meng; Wang, Jun; Shchukin, Dmitry G.

    2016-04-01

    The epoxy coatings containing MCM-22 and Ce-MCM-22 zeolites were prepared by coating method on the Mg-Li alloy surface. The influence of MCM-22 and Ce-MCM-22 zeolites on corrosion protection of the epoxy coating was studied. The epoxy coating containing Ce-MCM-22 zeolites showed high corrosion resistance. Artificial defects in the epoxy coating containing Ce-MCM-22 zeolites on the Mg-Li surface were produced by the needle punching. The results show that the epoxy coating containing Ce-MCM-22 zeolites exhibits self-healing corrosion inhibition capabilities. It is ascribed to the fact that the Ce3+ ions are released from MCM-22 zeolites based on ion exchange of zeolite in the corrosion process of the Mg-Li alloy substrate. MCM-22 zeolites as reservoirs provided a prolonged release of cerium ions.

  8. Proposal for product development model focused on ce certification methodology

    Directory of Open Access Journals (Sweden)

    Nathalia Marcia Goulart Pinheiro

    2015-09-01

    Full Text Available This paper presents a critical analysis comparing 21 product development models in order to identify whether these structures meet the demands Product Certification of the European Community (CE. Furthermore, it presents a product development model, comprising the steps in the models analyzed, including improvements in activities for referred product certification. The proposed improvements are justified by the growing quest for the internationalization of products and processes within companies.

  9. 4d → 4f resonance in photoabsorption of cerium ion Ce3+ and endohedral cerium in fullerene complex {\\rm{Ce}}@{{{\\rm{C}}}_{82}}^{+}

    Science.gov (United States)

    Schrange-Kashenock, G.

    2016-09-01

    cage decreases the autoionizing giant 4d\\to 4f resonance lifetime for endohedral cerium in {{Ce}}@{{{{C}}}82}+ due to the opening of additional decay channels involving electrons of the fullerene shell, which cannot be accounted as a static potential. From consideration of the two-step model, it is clear that these processes are important. However, they lead only to broadening of the resonance. The dramatic reduction in the integrated oscillator strength in the cerium 4d resonance region can only occur when additional processes besides photoionization come into play.

  10. Citrate mediated synthesis of uniform monazite LnPO4 (Ln = La, Ce) and Ln:LaPO4 (Ln = Eu, Ce, Ce + Tb) spheres and their photoluminescence.

    Science.gov (United States)

    Nuñez, Nuria O; Liviano, Sonia R; Ocaña, Manuel

    2010-09-15

    A simple method for the synthesis of spherical LaPO(4) (monazite) particles with narrow size distribution and tailored size in the 150-500 nm range is reported. The procedure is based on a homogeneous precipitation process at low temperature (120 degrees C) from solutions containing La(3+), citrate and phosphate ions under a very restrictive set of experimental conditions, which involves the use of La nitrate, citric acid and phosphoric acid as precursors and ethylene glycol as solvent. The growth mechanism of the spheres was investigated aiming at explaining the differences in particle size and shape observed when varying the experimental conditions. The applicability of this method for the synthesis of spherical particles of other lanthanide (Ce, Tb, Eu) phosphates is also analyzed. Finally, it is shown that the developed procedure can be used to dope the lanthanum phosphate particles with lanthanide cations, which resulted in spherical phosphors as illustrated for the Eu-doped, Ce-doped and Ce, Tb codoped systems, whose luminescent properties are also evaluated.

  11. [Pharmacotherapeutical efficiency of the dry extract "Ce-god-5" in liver injury induced by CCl4 in white rats].

    Science.gov (United States)

    Dashinamzhilov, Zh B; Turtuev, C D

    2014-01-01

    It has been established that the complex plant remedy "Ce-god-5" possesses the marked hepatoprotective effect in liver injury induced by CCl4 in white rats. The ability to inhibit the processes of lipid peroxidation and stimulate antioxidant system of the body is a basic mechanism of hepatoprotective activity of "Ce-god-5".

  12. Synthesis of Ag, CeO2, Ag-CeO2 Nanoparticles and Their Applications in Catalytic CO Oxidation%纳米Ag,CeO2和Ag-CeO2的合成及在CO催化氧化中的应用

    Institute of Scientific and Technical Information of China (English)

    陈婧; 黄新松; 李广社

    2013-01-01

    CeO2 and Ag nanoparticles and Ag-Ce02nanocomposites were systematically prepared. The structures of the catalysts and the catalytic activity for CO oxidation were studied. The results indicate that the catalytic activity of Ag is rather poor. The highest conversion of CO oxidation was only 40% , and smaller particles led to the worsening of the catalytic activity; for CeO2 nanoparticles, the conversion of CO oxidation could be as high as 100% , while the reaction temperature was relatively high( ca. 350 ℃ ). Compared with CeO2 and Ag nanoparticles, Ag-CeO2 nanocomposites showed a markedly enhanced catalytic property; CO can be completely oxidized to CO2 at temperature as low as 150 ℃. The excellent catalytic performance of the Ag-CeO2 nanocomposites is due to the interactions between Ag and CeO2 in nanocomposites. We discussed the relevant catalytic processes using temperature-programmed reduction (TPR) technology.%系统合成了不同粒径的CeO2和Ag纳米粒子及Ag-CeO2纳米复合粒子,并对其进行了结构表征和CO催化氧化性能测试.结果表明,Ag纳米粒子的催化活性较低,以其为催化剂时CO的最大催化转化率仅为40%,且粒径越小越容易失活;在CeO2纳米粒子催化下,CO的催化转化率可达到100%,但催化反应的温度较高(约350℃);与CeO2和Ag相比,Ag-CeO2的催化性能明显增强,CO在较低的温度(150℃)下可实现完全转化.程序升温还原(Temperature-programmed reduction,TPR)分析结果表明,纳米复合材料中Ag和CeO2之间的相互作用是产生优异催化性能的关键原因.

  13. Interaction behavior between binary xCe-yNd alloy and HT9

    Science.gov (United States)

    Kim, Jun Hwan; Cheon, Jin Sik; Lee, Byoung Oon; Kim, June Hyung

    2016-10-01

    Studies were carried out to investigate the role of Ce and Nd, contained inside metal fuel during reactor operation, and their effect on the Fuel-Cladding Chemical Interaction (FCCI) phenomenon, which limits fuel performance in the Sodium-cooled Fast Reactor (SFR). Binary model alloys of xCe-yNd were manufactured, and then diffusion couple tests with HT9 (12Cr-1MoWV) ferritic-martensitic cladding material were carried out at a temperature of 660 °C for up to 25 h. The results showed that both Ce and Nd reacted with Fe in the cladding material to form an interaction layer. Analysis of the microstructure and reaction kinetics revealed that Fe in the cladding material rapidly migrates into Ce to form eutectic reaction, leaving a Fe depleted zone, in which Ce substitutes. In the case of Nd element, a typical solid-solid diffusion process governed to form a Fe17Nd2 type intermetallic compound. Synergism between Ce and Nd occurred so that the reaction thickness was increased, reaching the maximum reaction thickness in the case of the xCe-yNd alloy, whose composition was nearly 1:1.

  14. Ethylene Glycol Adsorption and Reaction over CeOX(111) Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    T Chen; D Mullins

    2011-12-31

    This study reports the interaction of ethylene glycol with well-ordered CeO{sub x}(111) thin film surfaces. Ethylene glycol initially adsorbs on fully oxidized CeO{sub 2}(111) and reduced CeO{sub 2-x}(111) through the formation of one C-O-Ce bond and then forms a second alkoxy bond after annealing. On fully oxidized CeO{sub 2}(111) both recombination of ethylene glycol and water desorption occur at low temperature leaving stable -OCH{sub 2}CH{sub 2}O- (ethylenedioxy) intermediates and oxygen vacancies on the surface. This ethylenedioxy intermediate goes through C-C bond scission to produce formate species which then react to produce CO and CO{sub 2}. The formation of water results in the reduction of the ceria. On a reduced CeO{sub 2-x}(111) surface the reaction selectivity shifts toward a dehydration process. The ethylenedioxy intermediate decomposes by breaking a C-O bond and converts into an enolate species. Similar to the reaction of acetaldehyde on reduced CeO{sub 2-x}(111), the enolate reacts to produce acetaldehyde, acetylene, and ethylene. The loss of O from ethylene glycol leads to a small amount of oxidation of the reduced ceria.

  15. The influence of Mn-doped CeO2 on the activity of CuO/CeO2 in CO oxidation and NO + CO model reaction

    Science.gov (United States)

    Deng, Changshun; Huang, Qingqing; Zhu, Xiying; Hu, Qun; Su, Wenli; Qian, Junning; Dong, Lihui; Li, Bin; Fan, Minguang; Liang, Caiyuan

    2016-12-01

    This work is mainly focused on the investigation of the influence of Mn-doped CeO2 supported by CuO on the physicochemical and catalytic properties for CO oxidation and NO + CO model reaction. The obtained samples were characterized using N2-physisorption (BET), XRD, LRS, TEM, EDS-Mapping, ICP-AES, XPS, H2-TPR, O2-TPD, in situ DRIFTS, CO oxidation, and NO + CO model reaction. The results imply that appropriate doping MnOx into the lattice of CeO2 will cause an obvious change in the properties of the catalyst and the Cu/CeMn-10: 1 catalyst shows the largest specific surface area, the most uniformity of structure, and the most extent of lattice expansion. A few addition of MnOx is more conducive to the generation of low valence manganese ion in the process of calcination, which may contribute to the synergetic introduction. This further results in more Cu+ due to the shifting of redox equilibrium (Cu2+ + Ce3+ ↔ Cu+ + Ce4+) to right, as well as more oxygen vacancies. Moreover, the capability of Cu/CeMn-10: 1 on desorb/transform/decompose of the adsorbed NO species is more effective than that of Cu/CeO2. The results of catalytic performance show that Cu+/Cu0 species play a key role, and the activity is mainly related to the specific surface area, the content of Cu+ and Ce3+, the reduction, desorption capability of chemisorbed O2- (and/or O-) species as well as adsorption behaviors of these catalysts for CO oxidation and NO + CO reaction. Finally, possible reaction mechanisms are tentatively proposed to understand the reactions.

  16. Microstructure and corrosion resistance of Ni-based alloy laser coatings with nanosize CeO2 addition

    Directory of Open Access Journals (Sweden)

    Shi Hong Zhang et al

    2008-01-01

    Full Text Available Micron-size Ni-base alloy (NBA powders were mixed with both 1.5 wt.% (hereinafter % micron-size CeO2 (m-CeO2 and also 1.5% and 3.0% nano-size CeO2 (n- CeO2 powders. These mixtures were coated on low-carbon steel (Q235 by 2.0 kW CO2 laser cladding. The effects on the microstructures, phases and electrochemical corrosion of the coatings upon the addition of m- and n- CeO2 powders to NBA (m- and n- CeO2 /NBA have been investigated. The results showed that a smooth coating was prepared under suitable processing parameters (P= 2.0 kW, V= 180 mm min- 1 by adding 1.5% n- CeO2. In addition to the primary phases of γ-Ni, Cr23 C6 and Ni3 B in the Ni-base alloy coating, CeNi3 was formed in Ni-base alloy coatings with both n- CeO2 and m-CeO2 particles, and CeNi5 appeared in the coating upon decreasing the size of CeO2 particles. Well-developed dendrites were observed in the Ni-base alloy coating; directional dendrites grew at the interface in the coating upon the addition of m-CeO2, whereas fine and multioriented dendrites grew upon decreasing the size of CeO2 particles to the nanoscale. Actinomorphic dendrites and compact equiaxed dendrites grew from the interface to near the surface upon increasing the content of n- CeO2 from 1.5 to 3.0%. In strongly acidic HNO3 solution, the severe corrosion of dendrites occurred and there were many corrosion pits in the Ni-base alloy coating; intercrystalline corrosion also has a dominant role upon the addition of m-CeO2, whereas uniform corrosion occurs in the coating as the size of CeO2 particles is decreased to nanoscale.

  17. Aging Behavior of Cu-Cr-Zr-Ce Alloy

    Institute of Scientific and Technical Information of China (English)

    LIU Yong; LIU Ping; SU Juan-hua; TIAN Bao-hong; LI Wei

    2004-01-01

    The aging properties of Cu-0.35Cr-0.038Zr-0.055Ce alloy are studied. The results show that can obtain higher electrical conductivity and microhardness after solutioned at 920℃for lh, and aged at 500℃. The process of precipitation of the secondary phase can be accelerated with cold deformation before aging, so properties of the alloy are improved.Upon aging at 500℃ for 30 minutes after 60% cold deformation, the values of electrical conductivity and microhardness are69.0%IACS and 152HV respectively, but they are only 66.2%IACS and 136HV upon directly aging after solution. With the addition of a trace of rare earth element Ce, the value of microhardness of Cu-0.35Cr-0.038Zr alloy increases 18~25HV,while the value of electrical conductivity drops a little.

  18. CuO/CeO{sub 2} catalysts prepared with different cerium supports for CO oxidation at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Chi-Yuan [School of Public Health, Chung Shan Medical University, Taichung 402, Taiwan, ROC (China); Department of Occupational Medicine, Chung Shan Medical University Hospital, Taichung 402, Taiwan, ROC (China); Chang, Wen-Chi [Department of Environmental Engineering, National Chung Hsing University, Taichung 402, Taiwan, ROC (China); Wey, Ming-Yen, E-mail: mywey@dragon.nchu.edu.tw [Department of Environmental Engineering, National Chung Hsing University, Taichung 402, Taiwan, ROC (China)

    2013-08-15

    The activity of a catalyst depends on the nature of its support, its active site, and its preparation method. This study aimed to employ various types of CeO{sub 2} supports such as commercial CeO{sub 2} and self-prepared CeO{sub 2} for the preparation of copper catalysts. The CuO/CeO{sub 2} catalysts were prepared using the polyol process and impregnation method. The catalysts were characterized using Brunauer–Emmett–Teller analysis, scanning electron microscopy, and X-ray analysis, and their catalytic activity for CO removal was evaluated in a microcatalytic reactor. The experimental results showed that the catalytic activity of the CuO/CeO{sub 2} catalysts with different calcination temperatures decreased in the following order: 500 °C > 300 °C > 700 °C. Compared to the impregnation method, the polyol process generated well-dispersed metal particles over the support and showed higher CO removal efficiency with low activation energy. Compared to CuO/CeO{sub 2} catalysts with commercial CeO{sub 2}, those with CeO{sub 2} that was self-prepared by pyrolysis had a large pore volume and good crystal structure of CeO{sub 2} and showed good performance. The catalytic activity for CO removal was in the following order: CuO/CeO{sub 2}-P (pyrolysis) > CuO/CeO{sub 2}-C (commercial) > CuO/CeO{sub 2}-D (deposition precipitation). CuO/CeO{sub 2}-P catalysts showed good activity even at low temperature. The CuO/CeO{sub 2}-P(300)-P-120 min catalyst was found to possess the good CO removal rate when the oxygen content was 6%, CO concentration was 500 ppm, catalyst weighed 1.0 g, pollutant gas velocity was 500 mL min{sup −1}, SV was 3.7 × 10{sup 4} h{sup −1}, and reaction temperature was 150 °C. - Highlights: • CuO/CeO{sub 2} catalysts were prepared using polyol and impregnation methods. • The supports of catalyst were self-prepared cerium oxide and commercial cerium oxide. • Pyrolysis and deposition precipitation methods were used for cerium preparation.

  19. Characterizations of electrodeposited Ni–CeO{sub 2} nanocomposite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Kasturibai, S., E-mail: s.kasturibai@yahoo.co.in [Department of Chemistry, Alagappa Government Arts College, Karaikudi 630 003, Tamilnadu (India); Advanced Nanocomposite Coatings Laboratory, Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi 630 003, Tamilnadu (India); Kalaignan, G. Paruthimal, E-mail: pkalaignan@yahoo.com [Advanced Nanocomposite Coatings Laboratory, Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi 630 003, Tamilnadu (India)

    2014-10-15

    The expansion of current machinery requires metallic materials with better surface properties. In the present investigation, CeO{sub 2} reinforced nickel nanocomposite coatings were deposited on mild steel substrate by direct current electrodeposition process employing nickel acetate bath. The effect of incorporation of CeO{sub 2} particles in the Ni nanocomposite coatings on the micro hardness and corrosion behaviour has been evaluated. Smooth and compact nanocomposite deposits containing well-distributed cerium oxide particles were obtained. The crystallite structure was fcc for electrodeposited nickel and Ni–CeO{sub 2} nanocomposite coatings. It has been observed that, the presence of CeO{sub 2} nanoparticles favours the [111] and [200] texture of nickel matrix. The co-deposition of CeO{sub 2} nanoparticles with nickel was found to be favoured at applied current density of 8 A dm{sup −2}. The micro hardness values of the nickel nanocomposite coatings (725 HV) was higher than that of pure nickel (265 HV).The decrease in I{sub corr} values and increase in Constant Phase Element values were investigated in 3.5% NaCl solution which showed the higher corrosion resistant nature of Ni–CeO{sub 2} coatings. - Highlights: • Ni–CeO{sub 2} composite coatings have electrodeposited from eco-friendly acetate bath. • Inclusion of CeO{sub 2} in the composite coating has refined the crystallite size. • Micro hardness values have increased with CeO{sub 2} content in the composite coatings. • The negative shift of E{sub corr} confirming cathodic protective nature of coatings.

  20. Search for double beta decay of {sup 136}Ce and {sup 138}Ce with HPGe gamma detector

    Energy Technology Data Exchange (ETDEWEB)

    Belli, P. [INFN sezione Roma “Tor Vergata”, I-00133 Rome (Italy); Bernabei, R., E-mail: rita.bernabei@roma2.infn.it [INFN sezione Roma “Tor Vergata”, I-00133 Rome (Italy); Dipartimento di Fisica, Università di Roma “Tor Vergata”, I-00133 Rome (Italy); Boiko, R.S. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); Cappella, F. [INFN sezione Roma, I-00185 Rome (Italy); Dipartimento di Fisica, Università di Roma “La Sapienza”, I-00185 Rome (Italy); Cerulli, R. [INFN, Laboratori Nazionali del Gran Sasso, I-67010 Assergi (AQ) (Italy); Danevich, F.A. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); Incicchitti, A. [INFN sezione Roma, I-00185 Rome (Italy); Dipartimento di Fisica, Università di Roma “La Sapienza”, I-00185 Rome (Italy); Kropivyansky, B.N. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); Laubenstein, M. [INFN, Laboratori Nazionali del Gran Sasso, I-67010 Assergi (AQ) (Italy); Poda, D.V. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); Polischuk, O.G.; Tretyak, V.I. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); INFN sezione Roma, I-00185 Rome (Italy)

    2014-10-15

    Search for double β decay of {sup 136}Ce and {sup 138}Ce was realized with 732 g of deeply purified cerium oxide sample measured over 1900 h with the help of an ultra-low background HPGe γ detector with a volume of 465 cm{sup 3} at the STELLA facility of the Gran Sasso National Laboratories of the INFN (Italy). New improved half-life limits on double beta processes in the cerium isotopes were set at the level of lim⁡T{sub 1/2}∼10{sup 17}–10{sup 18} yr; many of them are even two orders of magnitude larger than the best previous results.

  1. Joining of ZrO2/CePO4 Green Bodies Using Slurries

    Institute of Scientific and Technical Information of China (English)

    刘名郑; 刘家臣; 高海; 王丽娟; 霍伟荣; 王凯利

    2004-01-01

    Ce-ZrO2 and ZrO2/CePO4 ceramic system was joined in the green body by using mixed powder. Three kinds of systems are discussed. The microstructure and bending strengths of the joint were investigated and it is found that the Ce-ZrO2 and 30%CePO4/ZrO2 ceramics can be well joined in the green body. A joint with high mechanical property and good microstructure can be obtained after sintering without applied pressure. Complexly shaped ceramic components can be created by the technique of green state joining. A new way to produce them is provided and the cost is reduced due to the simplicity of the process.

  2. Study of Co-Ce coating and surface on pasted nickel electrodes substrate

    Institute of Scientific and Technical Information of China (English)

    WANG Dianlong; WANG Chunyu; DAI Changsong; SUN Dezhi

    2006-01-01

    The process of electroplating Co-Ce alloys on the nickel foam framework surface can improve electro-conductivity for active materials and nickelsubstrate interface. The results of inductive coupled plasma emission spectrometer (ICP), cyclic voltammetry (CV), scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe microanalysis (EPMA) indicate that the Co-Ce coating chemical content of rare earth Ce 0.19wt.%-0.28wt.% can not only alter the microstructure of electroplating coating, but also accelerate the oxidation reaction of Co and improve its transfer rate of electric current conductivity to the active material particles. The grads-like distributing electro-conductive network of CoOOH is formed on the nickel substrate surface, which improves reversibility of pasted nickel electrode. The charging receptivity is improved by Co-Ce coating on the pasted nickel electrode substrate, and its specific discharging capacity is improved by 50%.

  3. Synthesis and characterization of Sm3+-doped CeO2 powders

    Institute of Scientific and Technical Information of China (English)

    LIU Guo-cong; CHEN Li-miao; DUAN Xue-chen; LIANG Da-wen

    2008-01-01

    Sm3+-doped CeO2 (denoted as Ce1-xSmxO2) powders with different morphologies were successfully synthesized via a precursor-growth-calcination approach, in which precursor was first synthesized by a hydrothermal method and Ce1-xSmxO2 powders were finally obtained through a calcination process. The products were characterized with X-ray diffractometry(XRD), field emission scanning electron microscopy(FE-SEM) and fluorescence spectroscopy. The results reveal that the Ce1-xSmxO2 powders obtained by calcining the precursors prepared in the absence and presence of poly(vinyl pyrrolidone) (PVP) exhibit bundle- and sphere-like morphology, respectively. The possible growth process was proposed by preparing a series of intermediate morphologies during the shape evolution of CeO2 based on the SEM image observation. It is also found that the luminescence intensity of bundle-like Ce1-xSmxO2 is enhanced in comparison with that of sphere-like one due to its special morphology.

  4. CeRh3B2: A ferromagnet with anomalously large Ce 5d spin and orbital magnetic moments

    Science.gov (United States)

    Yaouanc, A.; Dalmas de Réotier, P.; Sanchez, J.-P.; Tschentscher, Th.; Lejay, P.

    1998-01-01

    We report a high-energy magnetic-Compton-scattering study performed on the ferromagnet CeRh3B2. This technique solely measures the electron spin magnetic moments. In contrast to a number of Ce intermetallics with nonmagnetic elements, the Ce 5d spin moment is found to be large and parallel to the Ce 4f spin moment. Therefore the Kondo effect does not play a key role for CeRh3B2. The inferred large Ce 5d orbital magnetic moment is a signature of the strong spin-orbit interaction for the Ce 5d band.

  5. The effects of Ce3+ and Ce4+ on the stability of fibroblast growth factor-2

    Science.gov (United States)

    Sun, Liwei; Feng, Hao; Jiang, Rui; Niu, Liping; Song, Yu; Feng, Kai; Qi, Chao

    2010-11-01

    The interaction between tri or tetravalent cerium ions and basic fibroblast growth factor (FGF-2) at 0.1-6: 1 molar ratio under physiological condition was studied by fluorescence and CD spectrum. The different spectra alterations of FGF-2 induced by Ce3+ and Ce4+ showed that Ce3+ and Ce4+ caused different conformational changes of FGF-2 respectively, though both of them destabilized the protein. The instability of FGF-2 in the presence of Ce3+ is involved in the oxidation of its free cystein of protein, but that this treatment nearly does not affect the biological activity. As to Ce4+, it not only induced the conformational changes of protein but also inhibits its activity in a dose-dependent manner, which could be relative to the electrostatic repulsion between Ce4+ and its basic amino acid residues (pI=9.6) or the specific binding of Ce4+ to deprotonated amino acid residues. The interesting results would be helpful to investigate the problem of the stability of proteins.

  6. Measurement of local moment on Ce in CeRh3B2

    Science.gov (United States)

    Devare, S. H.; Devare, H. G.

    1987-03-01

    We have employed the TDPAC technique to measure the paramagnetic enhancement factor β of140Ce in CeRh3B2 in the temperature range 300 K down to 115 K. Our measurements show that above Tc=115 K, the trend for β(T) closely follows that for trivalent cerium.

  7. Mercury speciation by CE: an update.

    Science.gov (United States)

    Kubán, Petr; Pelcová, Pavlína; Margetínová, Jana; Kubán, Vlastimil

    2009-01-01

    This review provides an update on mercury speciation by CE. It includes a brief discussion on physicochemical properties, toxicity and transformation pathways of mercury species (i.e. methyl-, ethyl-, phenyl- and inorganic mercury) and outlines recent trends in Hg speciation by CE. CE is presented as a complementary technique to chromatographic separation techniques, especially in cases when speed, high efficiency and low sample volumes are required. The development of suitable sample preconcentration/isolation (sample stacking, ion exchange, liquid-liquid-liquid extraction, dual-cloud point extraction) to achieve low LODs for analysis of trace concentrations of mercury species in real samples is emphasized. Hyphenation of CE to element specific detectors (i.e. electrothermal atomic absorption spectrometry, atomic fluorescence spectrometry, inductively coupled plasma-optical emission spectrometry, inductively coupled plasma-mass spectrometry) is discussed as well as a potential of CE in interaction studies that may provide useful information on interaction of various Hg species with selected bio-macromolecules.

  8. Microstructure of Rh-Ce particles on silica: Interactions between Ce and SiO sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Krause, K.R.; Schmidt, L.D. (Univ. of Minnesota, Minneapolis (United States)); Schabes-Retchkiman, P. (UNAM, Mexico City (Mexico))

    1992-03-01

    The authors have characterized the microstructure of Rh/Ce on SiO{sub 2} after heat treatments in H{sub 2} and O{sub 2} using TEM, HREM, XPS, and EELS, focusing on the very stable structures formed after heating in H{sub 2}. After initial reduction at 600 C, Rh is present as 50- to 100-{angstrom} metal particles while the Ce forms a uniform amorphous film of Ce{sup 3+} on the SiO{sub 2}. After oxidation at 600 C, Rh is oxidized to Rh{sub 2}O{sub 3} and spreads over the SiO{sub 2} surface while Ce forms small patches and large (> 1,000 {angstrom}) particles of crystalline CeO{sub 2}. After reduction of the oxidized microstructure at 600 C, Rh metal returns with a less uniform particle size distribution, while Ce is reduced to Ce{sup 3+} and structures indicating strong interactions between Ce and Si are formed. Upon reduction in the presence of Rh, the CeO{sub 2} particles are reduced to crystalline Ce{sub 2}Si{sub 2}O{sub 7}. The Ce silicate nucleates at Rh particles and spreads over the support as large thin single-crystal patches. After reoxidation at 650 C, both Ce silicate and CeO{sub 2} were identified using EELS chemical shifts, indicating that the crystalline silicate, once formed, is stable in oxygen. Ce on SiO{sub 2}also showed interaction between Ce and Si, but no crystalline species formed after reduction and only small crystalline CeO{sub 2} particles formed after oxidation. Thus, the formation of the Ce silicate and the oxidation of Ce to CeO{sub 2} are catalyzed by Rh. This work represents the first direct evidence for the formation of a Ce silicate in this system.

  9. Liquid-core waveguide in CE.

    Science.gov (United States)

    Okada, Tetsuo

    2007-10-01

    Liquid-core waveguide (LCW) brings about several advantages in CE. This review discusses some aspects of fundamental and practical importance involved in this method. Sensitivity in absorption and fluorescence detection is in general improved by more than one order of magnitude over usual crossbeam detection arrangements; the improvements come from the long light path in absorption detection and low light scattering in fluorescence detection. Versatile instrumental arrangements are another advantage of LCW in CE, leading to several detection schemes, some of which provide information that is not gained by usual capillary-end crossbeam detection, e.g. whole-capillary imaging, simultaneous monitoring of multicapillary separation, and kinetic evaluation. The high potential and perspectives of LCW in CE are discussed based on the state-of-the-art developments.

  10. New approaches in sensitive chiral CE.

    Science.gov (United States)

    Sánchez-Hernández, Laura; Guijarro-Diez, Miguel; Marina, María Luisa; Crego, Antonio L

    2014-01-01

    CE has shown to have a big potential for chiral separations, with advantages such as high efficiency, high resolution, and low sample and reagents consumption. Nevertheless, when UV detection is employed, CE has some drawbacks, especially the low sensitivity obtained due to the short optical path length. Notwithstanding, sensitivity improvements can be achieved when different approaches are employed, such as sample treatment strategies (off-line or on-line), in-capillary sample preconcentration techniques, and/or alternative detection systems to UV-Vis (such as fluorescence, conductimetry, electrochemiluminiscence, MS, etc.). This article reviews the most recent methodological and instrumental advances reported from June 2011 to May 2013 for enhancing the sensitivity in chiral analysis by CE. The sensitivity achieved for the enantioseparated analytes and the applications carried out using the developed methodologies are also summarized.

  11. Electrical properties of nanocrystalline Ce(0.8)Sm(0.2)O(2-delta) and Ce(1-x)Gd(x)O(2-delta) (0.1 SOFC.

    Science.gov (United States)

    Choi, J W; Hwang, H K; Nam, S W; Park, K

    2010-11-01

    Ce(0.8)Sm(0.2)O(2-delta) and Ce(1-x)Gd(x)O(2-delta) (0.1 < or = x < or = 0.3) nano-sized powders were successfully synthesized by the solution combustion synthesis process. The calcined nanopowders showed a ceria-based single phase with a cubic fluorite structure. In this study, we discussed the structural and electrical characteristics of the sintered Ce(0.8)Sm(0.2)O(2-delta) and Ce(1-x)Gd(x)O(2-delta). We obtained high-quality Ce(0.8)Sm(0.2)O(2-delta) and Ce(1-x)Gd(x)O(2-delta) ceramics with a high density, ultra-fine grain size, and high electrical conductivity even at low sintering temperature using the nanosized powders. The electrical conductivities at 800 degrees C for the Ce(0.8)Sm(0.2)O(2-delta) sintered at 1400 degrees C and the Ce(0.8)Gd(0.2)O(2-delta) sintered at 1350 degrees C were 0.110 and 0.104 Scm(-1), respectively.

  12. Mägede vaikuses ja lumeväljade lummuses / Kristjan Erik Suurväli

    Index Scriptorium Estoniae

    Suurväli, Kristjan Erik

    2003-01-01

    MTÜ Freerider esindajatel Peeter Luigel ja Kristjan Erik Suurväljal avanes võimalus Russian Heliboarding Club kutsel käia tutvumas heliski võimalustega Kaukaasia, Usbekistani ja Kõrgõstani mägedes

  13. Nanocomposite of CeO{sub 2} and ZnO: An active material for the treatment of contaminated water

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Japinder; Bhukal, Santosh; Gupta, Kanu [Department of Chemistry, Panjab University, Chandigarh, 160014 (India); Tripathy, Mukesh [Icon Analytical Equipment (P) Ltd., New Delhi (India); Bansal, Sandeep [Department of Science and Technology, New Delhi (India); Singhal, Sonal, E-mail: sonal1174@gmail.com [Department of Chemistry, Panjab University, Chandigarh, 160014 (India)

    2016-07-01

    A series of catalytically active CeO{sub 2}/ZnO nanocomposites with different molar ratio (CeO{sub 2}: 1, 2, 3, 4, 5 and 6 mol%) were successfully synthesized by hydrothermal method. The synthesized nanocomposites were critically investigated using Powder X-ray diffraction technique, Transmission electron microscopy, Selected area electron diffraction and UV–vis diffused reflectance spectra analysis. Powder X-ray diffraction spectra revealed the presence of diffraction peaks of face-centered cubic phase of CeO{sub 2} and hexagonal wurtzite phase of ZnO. Transmission electron microscopic analysis revealed that nanocomposites consist of ZnO nanorods and CeO{sub 2} nanoparticles; where, CeO{sub 2} nanoparticles were clinging on the surface of ZnO nanorods. UV–vis diffused reflectance spectra analysis revealed the good absorption of all the samples towards UV light. The photocatalytic efficiency of CeO{sub 2}, ZnO and CeO{sub 2}/ZnO was compared by using methylene blue dye as probe molecule. CeO{sub 2}/ZnO nanocomposites were found to possess superior photocatalytic activity as compared to their monocomponent counterparts. Furthermore, CeO{sub 2}/ZnO with 5 mol% CeO{sub 2} presented best photocatalytic performance. Additionally, influence of different process variables on the rate of degradation of methylene blue was investigated using CeO{sub 2}/ZnO with 5 mol% CeO{sub 2} as catalyst. Maximum degradation of methylene blue was observed in alkaline region at a catalyst dosage of 1.00 g/L. - Highlights: • CeO{sub 2}/ZnO nanocomposites were fabricated using hydrothermal method. • Photocatalytic efficiency of CeO{sub 2}/ZnO nanocomposites was compared with their monocomponent counterparts. • Experimental conditions were optimized for the degradation of methylene blue dye. • CeO{sub 2}/ZnO nanocomposite proved to be a better candidate for the photocatalytic degradation of dye.

  14. Enhanced photocatalytic performances of CeO2/TiO2 nanobelt heterostructures.

    Science.gov (United States)

    Tian, Jian; Sang, Yuanhua; Zhao, Zhenhuan; Zhou, Weijia; Wang, Dongzhou; Kang, Xueliang; Liu, Hong; Wang, Jiyang; Chen, Shaowei; Cai, Huaqiang; Huang, Hui

    2013-11-25

    CeO2 /TiO2 nanobelt heterostructures are synthesized via a cost-effective hydrothermal method. The as-prepared nanocomposites consist of CeO2 nanoparticles assembled on the rough surface of TiO2 nanobelts. In comparison with P25 TiO2 colloids, surface-coarsened TiO2 nanobelts, and CeO2 nanoparticles, the CeO2 /TiO2 nanobelt heterostructures exhibit a markedly enhanced photocatalytic activity in the degradation of organic pollutants such as methyl orange (MO) under either UV or visible light irradiation. The enhanced photocatalytic performance is attributed to a novel capture-photodegradation-release mechanism. During the photocatalytic process, MO molecules are captured by CeO2 nanoparticles, degraded by photogenerated free radicals, and then released to the solution. With its high degradation efficiency, broad active light wavelength, and good stability, the CeO2 /TiO2 nanobelt heterostructures represent a new effective photocatalyst that is low-cost, recyclable, and will have wide application in photodegradation of various organic pollutants. The new capture-photodegradation-release mechanism for improved photocatalysis properties is of importance in the rational design and synthesis of new photocatalysts.

  15. Effect of annealing temperature on oxygen vacancy concentrations of nanocrystalline CeO{sub 2} film

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ka; Chang, Yongqin, E-mail: chang@ustb.edu.cn; Lv, Liang; Long, Yi

    2015-10-01

    Highlights: • Nanocrystalline CeO{sub 2} films were prepared by a facile sol–gel spin coating method. • Oxygen vacancy concentrations can be controlled by annealing temperatures. • The films show perfect thermal stability at various annealing temperatures. • PL, XPS and Raman spectra are obviously affected by oxygen vacancy concentrations. - Abstract: Nanocrystalline CeO{sub 2} films with around 250 nm thickness were deposited on Si (0 0 1) substrates by a facile sol–gel process with spin coating method. The films are of cubic fluorite structure, and some lattice distortions exist in the film. The phase stability and small change in lattice parameter at different annealing temperatures indicate the good thermal stability of the nanocrystalline CeO{sub 2} films. The average grain-size and surface roughness of the films increase with the increase of annealing temperature. The content of Ce{sup 3+} and oxygen vacancy is very high in the nanocrystalline CeO{sub 2} films, while, the films still remain cubic phase regardless of its high level non-stoichiometric composition. All the annealed samples show two emission bands, and the defect peak centered at ∼500 nm shows a red-shift. The intensity of the green-emission band increases with the increasing annealing temperature, which might result from the increasing concentration of oxygen vacancies caused by the valence transition from Ce{sup 4+} to Ce{sup 3+}, and it has also been confirmed by the X-ray photoelectron spectroscopy results. This work demonstrates that oxygen vacancy plays an important role on the properties of the nanocrystalline CeO{sub 2} film, and it also provides a possible way to control the concentration of oxygen vacancies.

  16. Ruthenium nanoparticles supported on CeO2 for catalytic permanganate oxidation of butylparaben.

    Science.gov (United States)

    Zhang, Jing; Sun, Bo; Guan, Xiaohong; Wang, Hui; Bao, Hongliang; Huang, Yuying; Qiao, Junlian; Zhou, Gongming

    2013-11-19

    This study developed a heterogeneous catalytic permanganate oxidation system with ceria supported ruthenium, Ru/CeO2 (0.8‰ as Ru), as catalyst for the first time. The catalytic performance of Ru/CeO2 toward butylparaben (BP) oxidation by permanganate was strongly dependent on its dosage, pH, permanganate concentration and temperature. The presence of 1.0 g L(-1) Ru/CeO2 increased the oxidation rate of BP by permanganate at pH 4.0-8.0 by 3-96 times. The increase in Ru/CeO2 dosage led to a progressive enhancement in the oxidation rate of BP by permanganate at neutral pH. The XANES analysis revealed that (1) Ru was deposited on the surface of CeO2 as Ru(III); (2) Ru(III) was oxidized by permanganate to its higher oxidation state Ru(VI) and Ru(VII), which acted as the co-oxidants in BP oxidation; (3) Ru(VI) and Ru(VII) were reduced by BP to its initial state of Ru(III). Therefore, Ru/CeO2 acted as an electron shuttle in catalytic permanganate oxidation process. LC-MS/MS analysis implied that BP was initially attacked by permanganate or Ru(VI) and Ru(VII) at the aromatic ring, leading to the formation of various hydroxyl-substituted and ring-opening products. Ru/CeO2 could maintain its catalytic activity during the six successive runs. In conclusion, catalyzing permanganate oxidation with Ru/CeO2 is a promising technology for degrading phenolic pollutants in water treatment.

  17. Building novel Ag/CeO{sub 2} heterostructure for enhancing photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Leng, Qiang; Yang, Dezhi; Yang, Qi [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Hu, Chenguo, E-mail: hucg@cqu.edu.cn [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Kang, Yue; Wang, Mingjun [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Hashim, Muhammad [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Applied Physics Department, Federal Urdu University of Arts Science and Technology, Islamabad (Pakistan)

    2015-05-15

    Highlights: • Ag nanoparticle is designed to building Schottky heterojunction on CeO{sub 2} nanocube. • The photocatalytic activity of Ag/CeO{sub 2} heterostructure is much enhanced. • 95.33% of MB can be effectively degraded within half an hour. • Ag as acceptor of photoelectrons blocks the recombination of electron–hole pairs. - Abstract: Stable and recyclable photocatalysts with high efficiency to degrade organic contamination are important and widely demanded under the threat of the environment pollution. Ag/CeO{sub 2} heterostructure is designed as a photocatalyst to degrade organic dye under the simulated sunlight. The catalytic activity of CeO{sub 2} nanocubes (NCs) to degrade methylene blue (MB) is obviously enhanced when Ag nanoparticles (NPs) are deposited on the surface of them. The weight ratio of Ag and CeO{sub 2} in forming high efficiency catalyst, the amount of Ag/CeO{sub 2} catalyst used in degradation process, and the dye concentration and pH value of the initial MB solution are examined systematically. 95.33% of MB can be effectively degraded within half an hour when 50 mg of Ag/CeO{sub 2} catalyst in an optimal weight ratio of 1:3, is added to the 100 mL of MB solution (c{sub 0} = 1 × 10{sup −5} mol L{sup −1}, pH 6.2). The mechanism of the enhanced catalytic activity of Ag/CeO{sub 2} heterostructure is discussed. The photocatalytic degradation rate is found to obey pseudo-first-order kinetics equations according to Langmuir–Hinshelwood model. The intermediate products in different stages during the degradation of MB are analyzed.

  18. Enhanced photocatalytic activity of Ce-doped Zn-Al multi-metal oxide composites derived from layered double hydroxide precursors.

    Science.gov (United States)

    Zhu, Jianyao; Zhu, Zhiliang; Zhang, Hua; Lu, Hongtao; Qiu, Yanling; Zhu, Linyan; Küppers, Stephan

    2016-11-01

    In this work, a series of novel Zn-Al-Ce multi-metal oxide (Zn-Al-Ce-MMO) photocatalysts with different Ce doping contents were prepared by calcination of Ce-doped Zn-Al layered double hydroxide (Zn-Al-Ce-LDH) precursors at various temperatures in air atmosphere. The synthesized Zn-Al-Ce-MMO materials were characterized by XRD, FTIR, TGA, BET, SEM, TEM, XPS and UV-vis DRS. The photocatalytic activities of the Zn-Al-Ce-MMO materials were evaluated by the photodegradation of rhodamine B (RhB) dye and paracetamol in aqueous solution under simulated solar light irradiation. The result of photodegradation of RhB showed that the Zn-Al-Ce-MMO samples exhibit much higher photocatalytic activity than that of Zn-Al-MMO, and the optimal Ce doping content is 5% of mole ratio (nCe/n(Zn+Al+Ce)). The enhanced photocatalytic activity of the Zn-Al-Ce-MMO was mainly attributed to the increasing in the separation efficiency of electrons and holes. The effect of calcination temperature was also studied. The photocatalytic activity of Zn-Al-Ce-MMO increased with increasing calcination temperature up to 750°C, which can be ascribed to the formation of well-crystallized metal oxides during calcination. Under experimental conditions, 97.8% degradation efficiency of RhB and 98.9% degradation efficiency of paracetamol were achieved after 240min. Active species trapping and EPR experiments suggested that hole (h(+)), superoxide radical (O2(-)) and hydroxyl radical (OH) played important roles during the RhB photocatalytic process. Moreover, the results indicated that the synthesized Zn-Al-Ce-MMO materials had good stability and reusability.

  19. Metamagnetism in Ce(Ga,Al)2

    Indian Academy of Sciences (India)

    K G Suresh; S Radha; A K Nigam

    2002-05-01

    Effect of Al substitution on the magnetic properties of Ce(Ga1-Al)2 ( = 0, 0.1 and 0.5) system has been studied. The magnetic state of CeGa2 is found to be FM with a C of 8 K, whereas the compounds with =0.1 and 0.5 are AFM and possess N of about 9 K. These two compounds undergo metamagnetic transition and the critical fields are about 1.2 T and 0.5 T, respectively at 2 K. These variations are explained on the basis of helical spin structure in these compounds.

  20. Laser altimeter of CE-1 payloads system

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The design and operation of the Laser Altimeter of CE-1 Payloads System are presented in this paper.The paper includes the design of the system and spacecraft-level laser,the description of the emitting-system and receiving system,and the testing of the laser altimeter.The CE-1 laser altimeter is the first Chinese deep-space probe using a laser.It has one beam and operates at 1 Hz,with a nominal accuracy of 5 m.The laser altimeter has operated successfully in lunar orbit since November 28,2007.It has obtained 9120 thousand data values about the lunar altitude.

  1. Scintillation properties of selected oxide monocrystals activated with Ce and Pr

    Science.gov (United States)

    Wojtowicz, Andrzej J.; Drozdowski, Winicjusz; Wisniewski, Dariusz; Lefaucheur, Jean-Luc; Galazka, Zbigniew; Gou, Zhenhui; Lukasiewicz, Tadeusz; Kisielewski, Jaroslaw

    2006-01-01

    In the last 10-15 years there has been a significant effort toward development of new, more efficient and faster materials for detection of ionizing radiation. A growing demand for better scintillator crystals for detection of 511 keV gamma particles has been due mostly to recent advances in modern imaging systems employing positron emitting radionuclides for medical diagnostics in neurology, oncology and cardiology. While older imaging systems were almost exclusively based on BGO and NaI:Tl crystals the new systems, e.g., ECAT Accel, developed by Siemens/CTI, are based on recently discovered and developed LSO (Lu 2SiO 5:Ce, Ce-activated lutetium oxyorthosilicate) crystals. Interestingly, despite very good properties of LSO, there still is a strong drive toward development of new scintillator crystals that would show even better performance and characteristics. In this presentation we shall review spectroscopic and scintillator characterization of new complex oxide crystals, namely LSO, LYSO, YAG, LuAP (LuAlO 3, lutetium aluminate perovskite) and LuYAP activated with Ce and Pr. The LSO:Ce crystals have been grown by CTI Inc (USA), LYSO:Ce, LuAP:Ce and LuYAP:Ce crystals have been grown by Photonic Materials Ltd., Scotland (PML is the only company providing large LuAP:Ce crystals on a commercial scale), while YAG:Pr and LuAP:Pr crystals have been grown by Institute of Electronic Materials Technology (Poland). All these crystals have been characterized at Institute of Physics, N. Copernicus University (Poland). We will review and compare results of measurements of radioluminescence, VUV spectroscopy, scintillation light yields, scintillation time profiles and low temperature thermoluminescence performed on these crystals. We will demonstrate that all experiments clearly indicate that there is a significant room for improvement of LuAP, LuYAP and YAG. While both Ce-activated LSO and LYSO perform very well, we also note that LuYAP:Ce, LuAP:Ce and YAG:Pr offer some

  2. Effect of Li+ ions co-doping on luminescence, scintillation properties and defects characteristics of LuAG:Ce ceramics

    Science.gov (United States)

    Liu, Shuping; Feng, Xiqi; Mares, Jiri A.; Babin, Vladimir; Hu, Chen; Kou, Huamin; D'Ambrosio, Carmelo; Li, Jiang; Pan, Yubai; Nikl, Martin

    2017-02-01

    Monovalent Li+ codoped Lu3Al5O12:Ce (LuAG:Ce) optical ceramics were fabricated by solid state reaction method and further optimized by an air-annealing process. Optical absorption, radioluminescence spectra and scintillation properties such as light yield, scintillation decay times and afterglow were measured and compared with those of the Li+ free LuAG:Ce ceramic and the commercial LuAG:Ce single crystal samples. Positive effect of Li+ codopant consists mainly in the significant increase of scintillation light yield, acceleration of scintillation decay as well as the decrease of afterglow intensity. With 0.3% Li codoping, the obtained LuAG:Ce,Li ceramic displays a light yield of ∼29200 ph/MeV at 10 μs shaping time, higher than that of the LuAG:Ce single crystal and optical ceramic scintillators ever reported. The partial conversion of the stable Ce3+ to Ce4+ centers and the shallow and deep traps effect suppression by the Li+ codoping are discussed.

  3. Smart epoxy coating containing Ce-MCM-22 zeolites for corrosion protection of Mg-Li alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yanli, E-mail: yanliwang@hrbeu.edu.cn [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Stephenson Institute for Renewable Energy, Department of Chemistry, University of Liverpool, Peach Street, Liverpool L69 7ZF (United Kingdom); Zhu, Yanhao; Li, Chao; Song, Dalei; Zhang, Tao; Zheng, Xinran; Yan, Yongde; Zhang, Meng; Wang, Jun [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Shchukin, Dmitry G. [Stephenson Institute for Renewable Energy, Department of Chemistry, University of Liverpool, Peach Street, Liverpool L69 7ZF (United Kingdom)

    2016-04-30

    Graphical abstract: - Highlights: • The self-healing behaviour of the epoxy coating containing Ce-MCM-22 zeolites on the Mg-Li alloy was studied. • MCM-22 zeolites as reservoirs provide a prolonged release of cerium ions. • The epoxy coating containing Ce-MCM-22 zeolites provides effective long-term active protection for the Mg-Li alloy. - Abstract: The epoxy coatings containing MCM-22 and Ce-MCM-22 zeolites were prepared by coating method on the Mg-Li alloy surface. The influence of MCM-22 and Ce-MCM-22 zeolites on corrosion protection of the epoxy coating was studied. The epoxy coating containing Ce-MCM-22 zeolites showed high corrosion resistance. Artificial defects in the epoxy coating containing Ce-MCM-22 zeolites on the Mg-Li surface were produced by the needle punching. The results show that the epoxy coating containing Ce-MCM-22 zeolites exhibits self-healing corrosion inhibition capabilities. It is ascribed to the fact that the Ce{sup 3+} ions are released from MCM-22 zeolites based on ion exchange of zeolite in the corrosion process of the Mg-Li alloy substrate. MCM-22 zeolites as reservoirs provided a prolonged release of cerium ions.

  4. Effects of CE substitution on the microstructures and intrinsic magnetic properties of Nd–Fe–B alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhi [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); The Key Laboratory of Advanced Functional Materials, Ministry of Education, Beijing University of Technology, Beijing 100124 (China); Liu, Weiqiang, E-mail: liuweiqiang77@hotmail.com [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); The Key Laboratory of Advanced Functional Materials, Ministry of Education, Beijing University of Technology, Beijing 100124 (China); Zha, Shanshun; Li, Yuqing; Wang, Yunqiao; Zhang, Dongtao; Yue, Ming; Zhang, Jiuxing [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); The Key Laboratory of Advanced Functional Materials, Ministry of Education, Beijing University of Technology, Beijing 100124 (China); Huang, Xiulian [Anhui Province Key Laboratories of Rare Earth Permanent Magnet Materials, Anhui 231500 (China); Anhui Earth-panda Advance Magnetic Material co., Ltd., Anhui 231500 (China)

    2015-11-01

    (Nd{sub 1−x}Ce{sub x}){sub 30}Fe{sub 69}B (x=0, 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6) alloys were prepared by inducting melting, and the effect of substitution of Ce for Nd on their microstructure and intrinsic magnetic properties were investigated. With the increase of Ce content, Curie temperature (T{sub c}) decreases from 582.4 to 504.8 K, saturation magnetization (M{sub s}) decreases from 15.88 to 12.71 kGs, and anisotropy field (H{sub A}) decreases from 67.4 to 52.7 kOe. However, the reductions of the intrinsic magnetic properties are relatively gentle, and they still have potential to be prepared as permanent magnets. Moreover, further microstructure observations show that Ce is tending to diffuse into the Nd-rich grain boundary phase instead of main phase during the substitute process. Such aggregation behavior is beneficial to fabricate Ce containing magnet with high M{sub s}. - Highlights: • With the increase of Ce, T{sub c}, M{sub s}, and H{sub A} decrease gradually, but relatively gentle. • The (Nd{sub 1-x}Ce{sub x}){sub 30}Fe{sub 69}B alloys have potential to be prepared as permanent magnets. • Ce is tending to diffuse into the Nd-rich phase instead of main phase.

  5. Neutron scattering from -Ce at epithermal neutron energies

    Indian Academy of Sciences (India)

    A P Murani

    2008-10-01

    Neutron scattering data, using neutrons of incident energies as high as 2 eV, on -Ce and -Ce-like systems such as CeRh2, CeNi2, CeFe24, CeRu2, and many others that point clearly to the substantially localized 4f electronic state in these systems are reviewed. The present interpretation is contrary to the widely held view that the 4f electrons in these systems form a narrow itinerant electron 4f band.

  6. Sm doped mesoporous CeO2 nanocrystals: aqueous solution-based surfactant assisted low temperature synthesis, characterization and their improved autocatalytic activity.

    Science.gov (United States)

    Mandal, Bappaditya; Mondal, Aparna; Ray, Sirsendu Sekhar; Kundu, Amar

    2016-01-28

    Mesoporous Sm(3+) doped CeO2 (Ce-Sm) with a nanocrystalline framework, a high content of Ce(3+) and surface area (184 m(2) g(-1)), have been synthesized through a facile aqueous solution-based surfactant assisted route by using inorganic precursors and sodium dodecyl sulphate as a template. The XRD results indicate that the calcined Ce-Sm and even the as-prepared material have a cubic fluorite structure of CeO2 with no crystalline impurity phase. XRD studies along with HRTEM results confirmed the formation of mesoporous nanocrystalline CeO2 at a lower temperature as low as 100 °C. A detailed analysis revealed that Sm(3+) doping in CeO2 has increased the lattice volume, surface area, mesopore volume and engineered the surface defects. Higher concentrations of Ce(3+) and oxygen vacancies of Ce-Sm resulted in lowering of the band gap. It is evident from the H2-TPR results that Sm(3+) doping in CeO2 strongly modified the reduction behavior of CeO2 by shifting the bulk reduction at a much lower temperature, indicating increased oxygen mobility in the sample which enables enhanced oxygen diffusion at lower temperatures, thus promoting reducibility, i.e., the process of Ce(4+)→ Ce(3+). UV-visible transmission studies revealed improved autocatalytic performance due to easier Ce(4+)/Ce(3+) recycling in the Sm(3+) doped CeO2 nanoparticles. From the in vitro cytotoxicity of both pure CeO2 and Sm(3+) doped CeO2 calcined at 500 °C in a concentration as high as 100 μg mL(-1) (even after 120 h) on MG-63 cells, no obvious decrease in cell viability is observed, confirming their excellent biocompatibility. The presence of an increased amount of surface hydroxyl groups, mesoporosity, and surface defects have contributed towards an improved autocatalytic activity of mesoporous Ce-Sm, which appear to be a potential candidate for biomedical (antioxidant) applications.

  7. Advances in Process Intensification through Multifunctional Reactor Engineering

    Energy Technology Data Exchange (ETDEWEB)

    O' Hern, Timothy [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Engineering Sciences Center; Evans, Lindsay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Materials Sciences and Engineering Center; Miller, Jim [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Materials Sciences and Engineering Center; Cooper, Marcia [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Energetic Components Realization Center; Torczynski, John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pena, Donovan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gill, Walt [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Engineering Sciences Center

    2011-02-01

    This project was designed to advance the art of process intensification leading to a new generation of multifunctional chemical reactors utilizing pulse flow. Experimental testing was performed in order to fully characterize the hydrodynamic operating regimes associated with pulse flow for implementation in commercial applications. Sandia National Laboratories (SNL) operated a pilot-scale multifunctional reactor experiment for operation with and investigation of pulse flow operation. Validation-quality data sets of the fluid dynamics, heat and mass transfer, and chemical kinetics were acquired and shared with Chemical Research and Licensing (CR&L). Experiments in a two-phase air-water system examined the effects of bead diameter in the packing, and viscosity. Pressure signals were used to detect pulsing. Three-phase experiments used immiscible organic and aqueous liquids, and air or nitrogen as the gas phase. Hydrodynamic studies of flow regimes and holdup were performed for different types of packing, and mass transfer measurements were performed for a woven packing. These studies substantiated the improvements in mass transfer anticipated for pulse flow in multifunctional reactors for the acid-catalyzed C4 paraffin/olefin alkylation process. CR&L developed packings for this alkylation process, utilizing their alkylation process pilot facilities in Pasadena, TX. These packings were evaluated in the pilot-scale multifunctional reactor experiments established by Sandia to develop a more fundamental understanding of their role in process intensification. Lummus utilized the alkylation technology developed by CR&L to design and optimize the full commercial process utilizing multifunctional reactors containing the packings developed by CR&L and evaluated by Sandia. This hydrodynamic information has been developed for multifunctional chemical reactors utilizing pulse flow, for the acid-catalyzed C4 paraffin/olefin alkylation process, and is now accessible for use in

  8. Cu-CeO2 nanocomposites: mechanochemical synthesis, physico-chemical properties, CO-PROX activity

    Science.gov (United States)

    Borchers, Christine; Martin, May L.; Vorobjeva, Galina A.; Morozova, Olga S.; Firsova, Alla A.; Leonov, Alexander V.; Kurmaev, Ernst Z.; Kukharenko, Andrey I.; Zhidkov, Ivan S.; Cholakh, Seif O.

    2016-11-01

    Catalytic systems designated for preferential oxidation of CO in the presence of H2 are prepared by ball milling of Cu and CeO2, a simple and cheap one-step process to synthesize such catalysts. It is found that after 60 min of milling, a mixture of 8 wt.% Cu-CeO2 powders exhibits CO conversion of 96% and CO selectivity of about 65% at 438 K. Two active oxygen states, which are not observed in case of pure CeO2, were detected in the nanocomposite lattice and attributed to the presence of Cu in surface sites as well as in subsurface bulk sites. Correspondingly, oxidation of CO to CO2 was found to occur in a two-stage process with T max ≈ 395/460 K, and oxidation of H2 to H2O likewise in a two-stage process with T max ≈ 465/490 K. The milled powder consists of CeO2 crystallites sized 8-10 nm agglomerated to somewhat larger aggregates, with Cu dispersed on the surface of the CeO2 crystallites, and to a lesser extent present as Cu2O.

  9. Automated sample preparation for CE-SDS.

    Science.gov (United States)

    Le, M Eleanor; Vizel, Alona; Hutterer, Katariina M

    2013-05-01

    Traditionally, CE with SDS (CE-SDS) places many restrictions on sample composition. Requirements include low salt content, known initial sample concentration, and a narrow window of final sample concentration. As these restrictions require buffer exchange for many sample types, sample preparation is often tedious and yields poor sample recoveries. To improve capacity and streamline sample preparation, an automated robotic platform was developed using the PhyNexus Micro-Extractor Automated Instrument (MEA) for both the reduced and nonreduced CE-SDS assays. This automated sample preparation normalizes sample concentration, removes salts and other contaminants, and adds the required CE-SDS reagents, essentially eliminating manual steps during sample preparation. Fc-fusion proteins and monoclonal antibodies were used in this work to demonstrate benefits of this approach when compared to the manual method. With optimized conditions, this application has demonstrated decreased analyst "hands on" time and reduced total assay time. Sample recovery greater than 90% can be achieved, regardless of initial composition and concentration of analyte.

  10. HIGH-SPIN STATES IN CE-131

    NARCIS (Netherlands)

    PALACZ, M; SUJKOWSKI, Z; NYBERG, J; BACELAR, J; JONGMAN, J; HESSELINK, W; NASSER, J; PLOMPEN, A; WYSS, R

    1991-01-01

    Gamma ray spectra from the Sn-117(O-18, 4n)131Ce reaction have been studied with the NORDBALL array of 15 Compton-suppressed Ge detectors. States up to I = 51/2 h, E almost-equal-to 8 MeV are populated. Observed bands are interpreted in terms of quasiparticle configurations.

  11. Search for pressure-induced superconductivity in CeFeAsO and CeFePO iron pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Zocco, D. A. [University of California, San Diego; Baumbach, R. E. [University of California, San Diego; Hamlin, J. J. [University of California, San Diego; Janoschek, M. [University of California, San Diego; Lum, I. K. [University of California, San Diego; McGuire, Michael A [ORNL; Safa-Sefat, Athena [ORNL; Sales, Brian C [ORNL; Jin, Rongying [ORNL; Mandrus, David [ORNL; Jeffries, J. R. [Lawrence Livermore National Laboratory (LLNL); Weir, S. T. [Lawrence Livermore National Laboratory (LLNL); Vohra, Y. K. [University of Alabama, Birmingham; Maple, M. B. [University of California, San Diego

    2011-01-01

    The CeFeAsO and CeFePO iron pnictide compounds were studied via electrical transport measurements under high pressure. In CeFeAsO polycrystals, the magnetic phases involving the Fe and Ce ions coexist for hydrostatically applied pressures up to 15 GPa, and with no signs of pressure-induced superconductivity up to 50 GPa for the less hydrostatic pressure techniques. For the CeFePO single crystals, pressure further stabilizes the Kondo screening of the Ce 4f-electron magnetic moments.

  12. Ergonomie práce

    OpenAIRE

    Kučera, Pavel

    2013-01-01

    This thesis deals with ergonomics. The aim of the thesis is identifying risks arising from abusing ergonomics principles. Then make recommendations that would improve the working conditions and environment of the company, thereby increase employee satisfaction and efficiency of the production process. For ergonomic analysis has been selected Kolin plant Lear Corporation Ltd. The thesis consists of theoretical and analytical part. The theoretical part provides basic information about ergonomic...

  13. Luminescence, Energy Transfer and Tunable Color of Ce3+- and Tb3+-Activated Na3Gd(BO3)2 Phosphors

    Science.gov (United States)

    Zhang, Xinguo; Pan, Jialiang; Mo, Fuwang

    2017-02-01

    A series of blue Na3Gd(BO3)2:Ce3+ and blue-to-green color-tunable Na3Gd (BO3)2:Ce3+,Tb3+ phosphors were synthesized by the solid-state method. The luminescence, concentration quenching and energy transfer (ET) process of Na3Gd(BO3)2:Ce3+,Tb3+ were investigated. Both Ce3+ and Tb3+ occupy the Gd3+ site in the Na3Gd(BO3)2 host. Na3Gd(BO3)2:Ce3+ exhibits strong ultraviolet absorption and broadband blue emission. The Ce3+ sensitization effect on Tb3+ has been verified by the variation of PL/PLE spectra, the Ce3+ decay lifetimes and the energy transfer efficiency of Na3Gd(BO3)2:Ce3+,Tb3+ phosphors. The maximum Ce3+-Tb3+ ET efficiency has been calculated to be 95%. The emitting color of the obtained phosphors can be modulated from blue (0.179, 0.204) through bluish-green (0.271, 0.391) to green (0.349, 0.551) by properly changing the ratio of Ce3+/Tb3+.

  14. Valence state of Ce and the magnetism in CeRh3B2

    Science.gov (United States)

    Malik, S. K.; Umarji, A. M.; Shenoy, G. K.; Montano, P. A.; Reeves, M. E.

    1985-04-01

    The compound CeRh3B2 orders magnetically with a high Curie temperature (TC) of 115 K but with a low moment of only absorption edge measurements show a dominant absorption peak at the energy corresponding to trivalent cerium. Magnetic studies on the compounds Ce(Rhsub1-xTsubx)sub3Bsub2 with T=Ru and Os reveal that the magnetic state is very rapidly broken up with the replacement of Rh by Ru and Os. These results along with the observation of a high TsubC in CeRhsub3Bsub2 suggest that magnetism in this compound arises from a strong hybridization of nearly localized or slightly delocalized Ce 4f electrons with conduction electrons. The small moment may be due to a Kondo-type interaction coupled with crystal-field effects.

  15. Photoluminescence properties of Tb3Al5O12:Ce3+ garnet synthesized by the metal organic decomposition method

    Science.gov (United States)

    Onishi, Yuya; Nakamura, Toshihiro; Adachi, Sadao

    2017-02-01

    Tb3Al5O12:Ce3+ garnet (TAG:Ce3+) phosphor was synthesized by the metal organic decomposition (MOD) method and subsequent calcination at Tc = 800-1200°C for 1 h in air. The effects of Ce3+ concentration on the phosphor properties were investigated in detail using X-ray diffraction (XRD) analysis, photoluminescence (PL) analysis, PL excitation (PLE) spectroscopy, and PL decay measurements. The maximum intensity in the Ce3+ yellow emission was observed at the Ce3+ concentration of ∼0.20%. PLE and PL decay measurements suggested an evidence of the energy transfer from Tb3+ to Ce3+. Calcination temperature dependence of the XRD and PL intensities yielded an energy of ∼1.5 eV both for the TAG formation in the MOD process and for the optical activation of Ce3+ in its lattice sites. Temperature dependences of the PL intensity for the TAG:Ce3+ yellow-emitting and K2SiF6:Mn4+ red-emitting phosphors were also examined for the future solid-state lighting applications at T = 20-500 K in 10-K steps. The data of TAG:Ce3+ were analyzed using a theoretical model with considering a reservoir level of Et ∼9 meV, yielding a quenching energy of Eq ∼0.35 eV, whereas the K2SiF6:Mn4+ red-emitting phosphor data yielded a value of Eq ∼1.0 eV. The schematic energy-level diagrams for Tb3+ and Ce3+ were proposed for the sake of a better understanding of these ions in the TAG host.

  16. 大尺寸C/E面板铝蜂窝夹层结构筒形件成型工艺%Forming Process of Cylinder With A Large Size of C/E Panel Aluminum Honeycomb Sandwich Structure Cylindrical

    Institute of Scientific and Technical Information of China (English)

    黄智彬; 蒋文革; 李健芳; 张娅婷; 付平俊

    2013-01-01

    对某大尺寸MT300碳纤维/648环氧树脂面板蜂窝夹层结构筒形件成型工艺进行研究,介绍了内外面板成型工艺、“F”形前后金属端框与铝蜂窝夹芯插接工艺以及“F”形前后金属端框、内外面板与蜂窝夹芯的组装整体固化技术.通过模具设计优化大尺寸夹层结构筒形件尺寸满足设计要求,并解决了内外面板-蜂窝夹芯-前后金属框组装整体固化技术成型难点.%The forming process of carbon fiber MT300/648 epoxy panel honeycomb sandwich structure cylindrical with a large size is investigated in the paper.The forming process of internal and external panel,the plug-in process of aluminum honeycomb with "F" shape metal frames and the assembly co-curing technology of panels-aluminum honeycomb-metal frames are introduced.The size of honeycomb sandwich structure cylindrical achieve the requirements by the mold design optimization,and the difficulty of panel-honeycomb-frames assembly technology is resolved.

  17. Microwave synthesis of pure and doped cerium (IV) oxide (CeO2) nanoparticles for methylene blue degradation.

    Science.gov (United States)

    El Rouby, W M A; Farghali, A A; Hamdedein, A

    2016-11-01

    Cerium (IV) oxide (CeO2), samarium (Sm) and gadolinium (Gd) doped CeO2 nanoparticles were prepared using microwave technique. The effect of microwave irradiation time, microwave power and pH of the starting solution on the structure and crystallite size were investigated. The prepared nanoparticles were characterized using X-ray diffraction, FT-Raman spectroscopy, and transmission electron microscope. The photocatalytic activity of the as-prepared CeO2, Sm and Gd doped CeO2 toward degradation of methylene blue (MB) dye was investigated under UV light irradiation. The effect of pH, the amount of catalyst and the dye concentration on the degradation extent were studied. The photocatalytic activity of CeO2 was kinetically enhanced by trivalent cation (Gd and Sm) doping. The results revealed that Gd doped CeO2 nanoparticles exhibit the best catalytic degradation activity on MB under UV irradiation. For clarifying the environmental safety of the by products produced from the degradation process, the pathways of MB degradation were followed using liquid chromatography/mass spectroscopy (LC/MS). The total organic carbon content measurements confirmed the results obtained by LC/MS. Compared to the same nanoparticles prepared by another method, it was found that Gd doped CeO2 prepared by hydrothermal process was able to mineralize MB dye completely under UV light irradiation.

  18. Cerium incorporated MCM-48 (Ce-MCM-48) as a catalyst to inhibit bromate formation during ozonation of bromide-containing water: Efficacy and mechanism.

    Science.gov (United States)

    Li, Weiwei; Lu, Xiaowei; Xu, Ke; Qu, Jiuhui; Qiang, Zhimin

    2015-12-01

    The composite mesoporous sieve Ce-MCM-48 (cerium incorporated MCM-48) with different Si/Ce molar ratios were synthesized hydrothermally and characterized with X-ray diffraction, X-ray photoelectron spectroscopy, BET surface area, and pHpzc. Results indicate that Ce-MCM-48, especially with a Si/Ce molar ratio of 66 (i.e., Ce66-MCM-48), could significantly inhibit bromate (BrO3(-)) formation during ozonation of Br(-)-containing water, achieving 91% of inhibition efficiency at pH 7.6 and 25 °C. An acidic or alkaline pH decreased the inhibition efficiency of Ce66-MCM-48 to some extent, but reaction temperature ranging from 15 to 30 °C had no significant impact. By comparing the bromine mass balance, aqueous O3 decomposition, and newly formed H2O2 between O3 and O3/Ce66-MCM-48 processes, the inhibition mechanism was proposed: Ce66-MCM-48 promoted aqueous O3 decomposition to generate hydroxyl radicals (OH) that could merge into H2O2, so the oxidative transformation of Br(-) and HOBr/OBr(-) by O3 and OH was primarily suppressed. The catalytic ability of Ce66-MCM-48 was continuously regenerated through the circulating reactions between Ce(III) and Ce(IV) occurring on the catalyst surface. Besides its inhibition on BrO3(-) formation, Ce66-MCM-48 could also enhance the degradation of refractory organic micropollutants. Because of these distinct merits, Ce66-MCM-48 has potential applications to water treatment by ozone.

  19. cDNA library Table: ce-- [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available ce-- NA ce-- C202 x J201 compound eyes mixture of fifth instar larval stage to pupa...l stage mixed pBluescript SK- EcoR1 for 5' Xho1for 3' sequenced from T3 primer (5' -> 3') BP117205-BP118782 ce--[number] ...

  20. Preparation and characterization of CeO_2 doped ZnO nano-tubes fluorescent composite

    Institute of Scientific and Technical Information of China (English)

    李酽; 刘秀琳; 栗建钢

    2010-01-01

    ZnO nanotubes were hydrothermally synthesized and the ZNTs/CeO2 fluorescent composite were prepared by introducing nano CeO2 particles into ZnO nano-tubes via a chemical solution adsorption and annealing process. The samples were characterized by X-ray diffraction, scanning electron microscopy, Fourier transformation infrared spectroscopy and room temperature photoluminescence measurement. Due to the interaction between Ce4+ and the surface atoms of ZnO2 nano-tubes, a photoluminescence enhancement was obser...

  1. Effect of CeO2 on the Property of Zn-Ni/CeO2 Composite Coating%CeO2对Zn-Ni/CeO2复合镀层的影响

    Institute of Scientific and Technical Information of China (English)

    郑振; 李宁; 黎德育; 孟繁宇

    2012-01-01

    采用电沉积方法,通过向镀液中加入不同粒径的CeO2颗粒,制得Zn-Ni/微米CeO2复合镀层和Zn-Ni/纳米CeO2复合镀层,研究了CeO2粒子的大小和加入量对镀层微观形貌、相组成、CeO2在镀层中的复合量以及镀层耐蚀性的影响.结果表明:大量加入CeO2,可使镀层呈现块状的“饼干”结构,并能提高镀层的耐蚀性,此外还可以抑制Ni的沉积,加入10 g/L纳米CeO2时,镀层的合金相主要为Ni2Zn11相,其它Zn-Ni合金相则较少;相比之下,在提高镀层CeO2复合量方面,微米级CeO2效果较好,在提高镀层耐蚀性方面,纳米级CeO2的效果较好.%The Ni-Zn/micro-CeO2 composite material and Ni-Zn/nano-CeO2 composite material were produced by electrodeposition method through adding micro- and nano-CeO2 particles in the Zn-Ni plating bath. The effects of the diameter and the concentration of the CeO2 particles on the microtopography, phase component, CeO2 content and the corrosion resistance of the Ni-Zn coating were studied. The result shows that when the concentration of the CeO2 particles is high, the Ni deposition is inhibited; The composite coatings are characterized with laminate morphology with good corrosion resistance. When the concentration of the nano-CeO2 particles is 10 g/L, the major alloy phase is Ni2Zn11. Compared with the nano-composite coating, the CeO2 content is larger in the micro-CeO2 composite coating. But the corrosion resistance of the nano-CeO2 composite coating is larger than that of the micro-CeO2 ones.

  2. INCA-CE project: status and results

    Science.gov (United States)

    Strauss, Franziska; Meirold-Mautner, Ingo; Bica, Benedikt; Kann, Alexander; Wang, Yong

    2013-04-01

    Every year, Central Europe (CE) is affected by weather extremes challenging civil protection authorities, hydrologists and road maintenance services to timely warnings. Within the INCA-CE project (Integrated Nowcasting through Comprehensive Analysis in Central Europe; http://www.inca-ce.eu) which is supported by the European Regional Development Fund a deepened transnational cooperation between meteorological/hydrological services and three application areas is established. This guarantees for both enhancements of meteorological products in the sense of end-user friendliness, and standardized information exchange across borders. At present, INCA-CE is the only project throughout the world which connects cooperation to such an extent with respect to its transnational and multidisciplinary framework (in the meanwhile it has been chosen as World Weather Research Programme/Forecast Demonstration Project by the World Meteorological Organization). Key partners from eight countries (from national meteorological/hydrological services and the three different application areas) accept the challenge to work on standardization and harmonization tools. Therefore, the INCA nowcasting system - developed at the Austrian weather service (ZAMG) in the 1990ies - has been implemented at all CE meteorological/hydrological services and is advanced and refined to the specific user needs to (i) provide high quality nowcasting products which are standardized and harmonized across borders, (ii) improve information chains from models to warnings and protection measures in case of disaster, and (iii) make the public and stakeholders more familiar with meteorological products. However, the potential to achieve these listed improvements is only possible through the intense transnational and multidisciplinary cooperation, because for one institution and one country alone it would be impossible to cope with all the necessary tasks. In this presentation the status and results of the INCA-CE

  3. Local character of the highest antiferromagnetic Ce-system CeTi{1-x}Sc{x} Ge

    OpenAIRE

    2014-01-01

    The highest antiferromagnetic (AFM) temperature in Ce based compounds has been reported for CeScGe with Tn=47K, but its local or itinerant nature was not deeply investigated yet. In order to shed more light into this unusually high ordering temperature we have investigated structural, magnetic, transport and thermal properties of CeTi{1-x}Sc{x}Ge alloys within the range of stability of the CeScSi-type structure: 0.25

  4. Colour tuning and energy transfer pathways in MgAl2O4 triply doped with 0.1% Ce3+, 0.1% Eu2+, x% Tb3+ (0 ⩽ x ⩽ 2 %) nanocrystals synthesized using sol-gel process

    Science.gov (United States)

    Motloung, S. V.; Dejene, B. F.; Ntwaeaborwa, O. M.; Swart, H. C.; Kroon, R. E.

    2017-04-01

    A series of the undoped, 0.1% Ce3+, 0.1% Eu2+, 0.1% Tb3+ singly doped and 0.1% Ce3+, 0.1% Eu2+, x% Tb3+ (0 ⩽ x ⩽ 2 %) triply doped MgAl2O4 nanophosphors were synthesized by the sol-gel technique and thereafter annealed at 800 °C. The nanocrystals consist of the pure cubic structures. The type of the dopant and varying the Tb3+ mol% influence the crystallites size and morphology of the prepared powders. Photoluminescence (PL) results showed a red emission from Ce3+ singly doped MgAl2O4. Furthermore, the PL results revealed the existence of the energy transfer from Eu2+ → Tb3+ → Ce3+. CIE colour chromaticity showed that the colour can be tuned from bluish → greenish by changing the Tb3+ mol% and the excitation wavelength.

  5. Field Demonstration of a Membrane Process to Separate Nitrogen from Natural Gas: Nineteenth Quarterly Progress Report (Second Quarter 2006)

    Energy Technology Data Exchange (ETDEWEB)

    Kaaeid Lokhandwala

    2006-06-30

    The original proposal described the construction and operation of a 1 MMscfd treatment system to be operated at a Butcher Energy gas field in Ohio. The gas produced at this field contained 17% nitrogen. During pre-commissioning of the project, a series of well tests showed that the amount of gas in the field was significantly smaller than expected and that the nitrogen content of the wells was very high (25 to 30%). After evaluating the revised cost of the project, Butcher Energy decided that the plant would not be economical and withdrew from the project. Since that time, Membrane Technology and Research, Inc. (MTR) signed a marketing and sales partnership with ABB Lummus Global, a large multinational corporation, and is working with the company's Randall Gas Technology group, a supplier of equipment and processing technology to the natural gas industry. Randall's engineering group found a new site for the project at a North Texas Exploration (NTE) gas processing plant, and we continue, but have as yet been unsuccessful in our attempts, to negotiate with Atmos Energy for a final test of the project demonstration unit. In the meantime, MTR has located an alternative testing opportunity and signed a contract for a demonstration plant in Rio Vista, CA. Several commercial sales have resulted from the partnership with ABB, and total sales of nitrogen/natural gas membrane separation units are now approaching $2.6 million.

  6. Laser properties of yag: Nd, Cr, Ce

    Science.gov (United States)

    Kvapil, J.; Kvapil, Jos; Perner, B.; Kubelka, J.; Mánek, B.; Kubeček, V.

    1984-06-01

    Transient absorption of a long lifetime (≧ 20 s) of YAG: Nd is typical of pure material. It is the main reason of thermal deformation of the laser rods accompanied with power decreases at higher CW input. It may be prevented by an admixture of Fe, Ti or Cr. Using a small admixture (≦ 10-3 wt.%) of Ti or Cr the energy transfer among Nd ions and the gain coefficient may be increased. Cr in a higher concentration absorbs the pumping light and serves as earlier described coactivator (sensitizer) only. Fe impurity fully prevents any increase of the gain of YAG: Nd containing Ti or Cr and causes slow but irreversible degradation of the active parameters. Ce favourably modifies properties of YAG: Nd, Cr. YAG: Nd, Cr, Ce free of iron impurity is advisable active material for powerfull CW lasers.

  7. Ce qui se passe dans tes doigts

    OpenAIRE

    Quintans, Santiago; Lähdeoja, Otso

    2010-01-01

    Une question simple, c’est quoi la guitare électrique ? Claude Pavy : C’est une planche avec un manche, des cordes qui font tzing, des micros qui captent tzing, et après on fait joujou avec ça. La guitare électrique c’est d’abord le son. Je dis souvent à mes élèves : « la guitare, cela ne m’intéresse pas ». Alors évidemment, ils me regardent avec des yeux ronds, et ils me disent, « T’es guitariste ? » Oui, mais la guitare en elle-même, cela ne m’intéresse pas. Ce qui m’intéresse, c’est ce qu...

  8. Cerium intermetallics CeTX. Review III

    Energy Technology Data Exchange (ETDEWEB)

    Poettgen, Rainer; Janka, Oliver [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Chevalier, Bernard [Bordeaux Univ., Pessac (France). Inst. de Chimie de la Matiere Condensee de Bordeaux

    2016-05-01

    The structure-property relationships of CeTX intermetallics with structures other than the ZrNiAl and TiNiSi type are systematically reviewed. These CeTX phases form with electron-poor and electron-rich transition metals (T) and X = Mg, Zn, Cd, Hg, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, Sb, and Bi. The review focusses on the crystal chemistry, the chemical bonding peculiarities, and the magnetic and transport properties. Furthermore {sup 119}Sn Moessbauer spectroscopic data, high-pressure studies, hydrogenation reactions and the formation of solid solutions are reviewed. This paper is the third of a series of four reviews on equiatomic intermetallic cerium compound [Part I: R. Poettgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 289; Part II: R. Poettgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 695].

  9. GNSS高精度数据处理方法与技术%GnSS hiGh-preCiSion dAtA proCeSSinG method And teChniQue

    Institute of Scientific and Technical Information of China (English)

    周传根

    2015-01-01

    GAMIT/GLOBK software is globally famous high-precision GNSS data-processing software, which gives high-precision baseline solution to lay a solid basis for subsequent net adjustment to have high-precision station coordinates. GAMIT/GLOBK software is operated in Linux or Unix system by commands. Mastering its operation and usage is the precondition of making high-precision baseline solution.%GAMIT/GLOBK软件是国际上著名的高精度GNSS数据处理软件,通过它可以获得高精度基线解算解,为后续网平差获得高精度测站坐标打下重要基础。GAMIT/GLOBK软件在Linux或Unix系统通过命令运行,能熟练掌握操作和使用方法是进行高精度基线解算的前提。

  10. The CeDRES data portal

    Science.gov (United States)

    Albert-Aguilar, Alexandre; Delmotte, Pauline; André, François; Brissebrat, Guillaume; Canonici, Jean-Christophe; Piguet, Bruno

    2016-04-01

    SAFIRE is the French facility dedicated to airborne measurement for environmental research. The SAFIRE steering committee decided that access to its archives should be improved. If certain data, including recent campaigns, are available online, access to them is difficult for users because these data are dispersed in as many data portals as campaigns. Most of projects are not able to keep medium to long term online access to their database. Therefore, many airborne data, particularly the oldest, are not available online, stored on media whose sustainability is not guaranteed. SAFIRE also decided to identify old data stored in Meudon (France) on paper and hard media and to rescue with the help of an archivist. At the same time, the development of a centralized digital archive - containing data collected with the Fokker - 27 " ARAT " and Merlin IV aircraft - associated to a web portal was given to SEDOO. The first part of the project consisted in modelling the database. The second part, still in progess, was the development of the CeDRES (Centre de Données aéRoportées & SAFIRE) portal (http://cedres.sedoo.fr) which is responsive and bilingual (French and English) ; and metadata standardization (iso 19115). The main objectives of this project are data preservation and open data access. A first test version of CeDRES portal will be release in mid-February 2016. And operational version is planned for summer 2016. In the future, CeDRES portal will be able to receive and to distribute metadata and data of aircraft currently in service (FALCON-20, ATR-42 and PiperAztec-23). The interoperability implementation and data homogenization are planned in the medium term. The CeDRES portal is part of the French atmospheric chemistry data center AERIS (http://www.aeris-data.fr). Every scientist is invited to browse the catalog and use CEDRES data. Feel free to contact cedres-contact@sedoo.fr for any question.

  11. Synthesis and tunable luminescence of RbCaGd(PO4)2:Ce3+, Mn2+ phosphors

    Science.gov (United States)

    Chen, Xue; Lv, Fengzhu; Li, Penggang; Zhang, Yihe

    2016-04-01

    RbCaGd(PO4)2 doped with Ce3+, Mn2+ was synthesized by the sol-gel method. The crystal structure and crystallographic location of Ce3+ in RbCaGd(PO4)2 were identified by Rietveld refinement. Powder X-ray diffraction (XRD) revealed that the structure of RbCaGd(PO4)2:Ce3+ compounds is hexagonal structure which is similar to that of hexagonal LnPO4 with the lattice constant of a = b = 7.005(57) Å, c = 6.352(05) Å, and V (cell volume) = 269.980 Å3. The photoluminescence behavior and emission mechanism were studied systematically by doping activators in the RbCaGd(PO4)2 host. The Mn2+ incorporated RbCaGd(PO4)2:Ce3+, Mn2+ compounds exhibited blue emission from the parity- and spin-allowed f-d transition of Ce3+ and orange-to-red emission from the forbidden 4T1 → 6A1 transition of Mn2+. The emission chromaticity coordinates of RbCaGd(PO4)2:0.10Ce3+, xMn2+ (x = 0.16, 0.25) are close to the white region due to an energy transfer process and the energy transfer mechanism from Ce3+ to Mn2+ in the RbCaGd(PO4)2 host was dominated by dipole-dipole interactions.

  12. Morphology-dependent interplay of reduction behaviors, oxygen vacancies and hydroxyl reactivity of CeO2 nanocrystals.

    Science.gov (United States)

    Gao, Yuxian; Li, Rongtan; Chen, Shilong; Luo, Liangfeng; Cao, Tian; Huang, Weixin

    2015-12-21

    Reduction behaviors, oxygen vacancies and hydroxyl groups play decisive roles in the surface chemistry and catalysis of oxides. Employing isothermal H2 reduction we simultaneously reduced CeO2 nanocrystals with different morphologies, created oxygen vacancies and produced hydroxyl groups. The morphology of CeO2 nanocrystals was observed to strongly affect the reduction process and the resultant oxygen vacancy structure. The resultant oxygen vacancies are mainly located on the surfaces of CeO2 cubes and rods but in the subsurface/bulk of CeO2 octahedra. The reactivity of isolated bridging hydroxyl groups on CeO2 nanocrystals was found to depend on the local oxygen vacancy concentration, in which they reacted to produce water at low local oxygen vacancy concentrations but to produce both water and hydrogen with increasing local oxygen vacancy concentration. These results reveal a morphology-dependent interplay among the reduction behaviors, oxygen vacancies and hydroxyl reactivity of CeO2 nanocrystals, which deepens the fundamental understanding of the surface chemistry and catalysis of CeO2.

  13. Study of energy transfer and spectral downshifting in Ce, RE (RE = Nd and Yb) co-doped lanthanum phosphate

    Science.gov (United States)

    Sawala, N. S.; Omanwar, S. K.

    2017-03-01

    The phosphors LaPO4 (Lanthanum phosphate) doped with Ce(III)/Ce3+ and co-doped with Ce3+-Nd3+ and Ce3+-Yb3+ were effectively synthesized by conventional solid state reaction method. The prepared samples were characterized by powder X-ray diffraction (XRD) and surface morphology was studied by scanning electronic microscope (SEM). The photoluminescence (PL) properties were studied by spectrophotometers in near infrared (NIR) and ultraviolet visible (UV-VIS) region. Additionally the luminescence time decay curves of samples were investigated to confirm energy transfer (ET) process. The Ce3+-Nd3+ ion co-doped LaPO4 phosphors can convert a photon of UV region (278 nm) into photons of NIR region (1058 nm). While Ce3+-Yb3+ ion doped LaPO4 phosphors convert photons of UV region (278 nm) into photons of NIR region (979 nm). The Ce3+ ion acts like sensitizer and Nd3+/Yb3+ ions act as activators. Both kinds of emissions are suitable for improving spectral response of solar cells.

  14. Synthesis and electrochemical properties of CeO{sub 2} nanoparticle modified TiO{sub 2} nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Wen Hao [Key Lab of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Liu Zhifu; Yang Qunbao [Key Lab of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Li Yongxiang, E-mail: yxli@mail.sic.ac.c [Key Lab of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Yu, Jerry [Sensor Technology Lab., School of Electrical and Computer Engineering, RMIT University, Melbourne 3001 (Australia)

    2011-02-28

    In this paper, a cerium dioxide (CeO{sub 2}) modified titanium dioxide (TiO{sub 2}) nanotube array film was fabricated by electrodeposition of CeO{sub 2} nanoparticles onto an anodized TiO{sub 2} nanotube array. The structural investigation by X-ray diffraction, scanning electron microscopy and transmission electron microscopy indicated that the CeO{sub 2} nanoparticles grew uniformly on the walls of the TiO{sub 2} nanotubes. The composite was composed of cubic-phase CeO{sub 2} crystallites and anatase-phase TiO{sub 2} after annealing at 450 {sup o}C. The cyclic voltammetry and chronoamperometric charge/discharge measurement results indicated that the CeO{sub 2} modification obviously increased the charge storage capacity of the TiO{sub 2} nanotubes. The charge transfer process at the surface, that is, the pseudocapacitance, was the dominate mechanism of the charge storage in CeO{sub 2}-modified TiO{sub 2} nanotubes. The greater number of surface active sites resulting from uniform application of the CeO{sub 2} nanoparticles to the well-aligned TiO{sub 2} nanotubes contributed to the enhancement of the charge storage density.

  15. Mid-Temperature Synthesis of CeO2-TiO2 Complex Compound and Its XRD Structure Study

    Institute of Scientific and Technical Information of China (English)

    陈林深; 吕光烈; 胡秀荣

    2003-01-01

    The CeTi2O6, which is formed above 1300 ℃ by ceramic method, was obtained at 700 ℃ using sol-gel synthesis method. XRD analysis shows that there is 8% deficient of Ce in the structure. The chemical formula is Ce0.92Ti2O5.84, which has a monoclinic structure with space group of C 2/m. Its cell parameters are a=0.9811(8) nm, b=0.3726(3) nm, c=0.6831(6) nm, and β=118.84°. After being treated at 1300 ℃ for 3 h, the system keeps stable but the deficient disappears, while the chemical formula change to the normal CeTi2O6, and the cell parameters are a=0.9813(3) nm, b=0.3752(4) nm, c=0.6883(5) nm, β=119.05°. The key to synthesis the precursors of CeTi2O6 is that Ti4+ and Ce3+ ions must reach the atomistic distributing state and prevent the oxidation of Ce3+ during sol-gel process.

  16. Structure and antibacterial activity of Ce~(3+) exchanged montmorillonites

    Institute of Scientific and Technical Information of China (English)

    OUYANG Yousheng; XIE Yushan; TAN Shaozao; SHI Qingshan; CHEN Yiben

    2009-01-01

    Four kinds of Ce~(3+) exchanged montmorillonites(Ce/MMTs) were prepared by an ion-exchange reaction, and characterized with energy dispersive X-ray analysis (EDX), X-ray difference (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron micros-copy (SEM). The surface properties and antibacterial activity of Ce/MMTs were also investigated. The chemical compositions of Ce/MMTs were determined, and the cerium of Ce/MMTs was confirmed to be present as trivalent cerium state. The d001 basal spacings of Ce/MMTs were enlarged with the enhancement of the cerium contents, and the particles were formed with irregular shape. On increasing the Ce con-tents of Ce/MMTs, the special surface areas were decreased, but the total pore volumes and the average pore sizes were increased. The anti-bacterial activity of Ce/MMTs is increased with increasing the cerium contents, and 1.5g/L of Ce/MMT-3 containing 11.46wt.% of curium could remove all the Staphylococcus aureus and more than 99.9% of the Escherichia coli within 24.0 h of contact. Moreover, Ce/MMTs dis-played bactericidal activity.

  17. Growing trend of CE at the omics level: the frontier of systems biology.

    Science.gov (United States)

    Oh, Eulsik; Hasan, Md Nabiul; Jamshed, Muhammad; Park, Soo Hyun; Hong, Hye-Min; Song, Eun Joo; Yoo, Young Sook

    2010-01-01

    In a novel attempt to comprehend the complexity of life, systems biology has recently emerged as a state-of-the-art approach for biological research in contrast to the reductionist approaches that have been used in molecular cell biology since the 1950s. Because a massive amount of information is required in many systems biology studies of life processes, we have increasingly come to depend on techniques that provide high-throughput omics data. CE and CE coupled to MS have served as powerful analytical tools for providing qualitative and quantitative omics data. Recent systems biology studies have focused strongly on the diagnosis and treatment of diseases. The increasing number of clinical research papers on drug discovery and disease therapies reflects this growing interest among scientists. Since such clinical research reflects one of the ultimate purposes of bioscience, these trends will be sustained for a long time. Thus, this review mainly focuses on the application of CE and CE-MS in diagnosis as well as on the latest CE methods developed. Furthermore, we outline the new challenges that arose in 2008 and later in elucidating the system-level functions of the bioconstituents of living organisms.

  18. Study of the mechanical properties of CeO{sub 2} layers with the nanoindentation technique

    Energy Technology Data Exchange (ETDEWEB)

    Roa, J.J., E-mail: joanjosep_roa@ub.ed [Centro DIOPMA, Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Quimica, Universidad de Barcelona, C/Marti i Franques, 1, 08028, Barcelona (Spain); Gilioli, E.; Bissoli, F.; Pattini, F.; Rampino, S. [IMEM-CNR, Area delle Scienze 37/A, 43010 Fontanini-Parma (Italy); Capdevila, X.G.; Segarra, M. [Centro DIOPMA, Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Quimica, Universidad de Barcelona, C/Marti i Franques, 1, 08028, Barcelona (Spain)

    2009-11-02

    The mechanical properties of CeO{sub 2} layers that are undoped or doped with other elements (e.g. Zr and Ta) are a topic of special interest specially in the manufacturing of superconductor buffer layers by pulsed electron deposition. Nowadays, the trend is to produce small devices (i.e. coated conductors), and the correct mechanical characterization is critical. In this sense, nanoindentation is a powerful technique widely employed to determine the mechanical properties of small volumes. In this study, the nanoindentation technique allow us determine the hardness (H) and Young's modulus (E) by sharp indentation of different buffer layers to explore the deposition process of CeO{sub 2} that is undoped or doped with Zr and Ta, and deposited on Ni-5%W at room temperature. This study was carried out on various samples at different ranges of applied loads (from 0.5 to 500 mN). Scanning electron microscopy images show no cracking for CeO{sub 2} doped with Zr, as the doping agent increases the toughness fracture of the CeO{sub 2} layer. This system, presents better mechanical stability than the other studied systems. Thus, the H for Zr-CeO{sub 2} is around 2.75 . 10{sup 6} Pa, and the elastic modulus calculated using the Bec et al. and Rar et al. models equals 249 . 10{sup 6} Pa and 235 . 10{sup 6} Pa respectively.

  19. Achieving real-time capsule endoscopy (CE) video visualization through panoramic imaging

    Science.gov (United States)

    Yi, Steven; Xie, Jean; Mui, Peter; Leighton, Jonathan A.

    2013-02-01

    In this paper, we mainly present a novel and real-time capsule endoscopy (CE) video visualization concept based on panoramic imaging. Typical CE videos run about 8 hours and are manually reviewed by physicians to locate diseases such as bleedings and polyps. To date, there is no commercially available tool capable of providing stabilized and processed CE video that is easy to analyze in real time. The burden on physicians' disease finding efforts is thus big. In fact, since the CE camera sensor has a limited forward looking view and low image frame rate (typical 2 frames per second), and captures very close range imaging on the GI tract surface, it is no surprise that traditional visualization method based on tracking and registration often fails to work. This paper presents a novel concept for real-time CE video stabilization and display. Instead of directly working on traditional forward looking FOV (field of view) images, we work on panoramic images to bypass many problems facing traditional imaging modalities. Methods on panoramic image generation based on optical lens principle leading to real-time data visualization will be presented. In addition, non-rigid panoramic image registration methods will be discussed.

  20. Easy-plane magnetocrystalline anisotropy in the multistep metamagnet CeIr3Si2

    Science.gov (United States)

    Shigetoh, K.; Ishida, A.; Ayabe, Y.; Onimaru, T.; Umeo, K.; Muro, Y.; Motoya, K.; Sera, M.; Takabatake, T.

    2007-11-01

    The magnetization M(B) , electrical resistivity ρ , and specific heat measurements are reported on a single-crystalline sample of CeIr3Si2 , whose structure is characterized with a zigzag chain of Ce ions along the orthorhombic a axis. This compound undergoes magnetic transitions at 3.9 and 3.1K . Easy-plane magnetocrystalline anisotropy is manifested in the magnetization process. For B∥b and B∥c , M(B) curves have a ferromagnetic component of 0.2-0.3μB/Ce and show metamagnetic transitions in a field range from 0.7to1.3T . At B=5T , M(B∥b) and M(B∥c) are 11 times larger than M(B∥a) . Electrical resistivity is also anisotropic, ρb≅ρc⩾2ρa . The magnetic part of ρ exhibits a double-peak structure with maxima at 15 and 350K . The analysis of M(B) and paramagnetic susceptibility using a crystal-field model revealed unusually large energy splitting of 500 and 1600K for the two excited doublets, respectively. The overall splitting is comparable to the largest value ever reported for Ce compounds, 2000K in the unusual ferromagnet CeRh3B2 with a closely related structure.

  1. CO oxidation catalyzed by ag nanoparticles supported on SnO/CeO2

    KAUST Repository

    Khan, Inayatali

    2015-01-01

    Ag-Sn/CeO2 catalysts were synthesized by the co-precipitation method with different Ag-Sn wt.% loadings and were tested for the oxidation of CO. The catalysts were characterized by powder X-ray diffractometry (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS), and selected area electron diffraction (SAED) techniques. UV-Vis measurements were carried out to elucidate the ionic states of the silver particles, and the temperature-programmed reduction (TPR) technique was employed to check the reduction temperature of the catalyst supported on CeO2. There are peaks for silver crystallites in the X-ray diffraction patterns and the presence of SnO was not well evidenced by the XRD technique due to sintering inside the 3D array channels of CeO2 during the calcination process. The Ag-Sn/CeO2 (4%) catalyst was the most efficient and exhibited 100% CO oxidation at 100 °C due to small particle size and strong electronic interaction with the SnO/CeO2 support. © 2015 Sociedade Brasileira de Química.

  2. [Effects of Arbuscular Mycorrhizal Fungi on the Growth and Ce Uptake of Maize Grown in Ce-contaminated Soils].

    Science.gov (United States)

    Wang, Fang; Guo, Weil; Ma, Peng-kun; Pan, Liang; Zhang, Jun

    2016-01-15

    A greenhouse pot experiment was conducted to investigate the effects of arbuscular mycorrhizal (AM) fungi Glomus aggregatum (GA) and Funneliformis mosseae (FM) on AM colonization rate, biomass, nutrient uptake, C: N: P stoichiometric and Ce uptake and transport by maize (Zea mays L.) grown in soils with different levels of Ce-contaminated (100, 500 and 1000 mg x kg(-1)). The aim was to provide basic data and technical support for the treatment of soils contaminated by rare earth elements. The results indicated that symbiotic associations were successfully established between the two isolates and maize, and the average AM colonization rate ranged from 7. 12% to 74.47%. The increasing concentration of Ce in soils significantly decreased the mycorrhizal colonization rate, biomass, nutrition contents and transport rate of Ce from root to shoot of maize, and significantly increased C: P and N: P ratios and Ce contents in shoot and root of maize. Both AM fungi inoculations promoted the growth of maize, but the promoting role of FM was more significant than that of GA in severe Ce-contaminated soils. There were no significant differences in the growth of maize between two AM fungi in mild and moderate Ce-contaminated soils. Inoculation with AM fungi significantly improved nutritional status of maize by increasing nutrient uptake and decreasing C: N: P ratios. GA was more efficient than FM in enhancing nutrient uptake in mild and moderate Ce-contaminated soils, while FM was more efficient in severe Ce-contaminated soils. Moreover, inoculation with AM fungi significantly increased Ce contents of shoot and root in mild Ce-contaminated soils, but had no significant effect on Ce contents of maize in moderate and severe Ce-contaminated soils, and promoted the transport of Ce from root to shoot. The experiment demonstrates that AM fungi can alleviate toxic effects of Ce on plants and have a potential role in the phytoremediation of soils contaminated by rare earth elements.

  3. Structural, topographical and electrical properties of cerium doped strontium barium niobate (Ce:SBN60) ceramics

    Science.gov (United States)

    Raj, S. Gokul; Mathivanan, V.; Kumar, G. Ramesh; Yathavan, S.; Mohan, R.

    2016-05-01

    Tungsten bronze type cerium doped strontium barium niobate (Ce:SBN - Sr0.6B0.4Nb2O6) ceramics were synthesized by solid state process. Cerium was used as dopant to improve its electrical properties. Influence of Ce+ ions on the photoluminescence properties was investigated in detail. The grain size topographical behavior of SBN powders and their associated abnormal grain growth (AGG) were completely analyzed through SEM studies. Finally dielectric, measurement discusses about the broad phase transition observed due to cerium dopant The results were discussed in detail.

  4. Crystallization mechanism of CeAlFeCo bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    王志新; 卢金斌; 席艳君

    2010-01-01

    Crystallization behaviors of Ce60Al15Fe5+xCo20-x(x=0,5,10) bulk metallic glasses(BMGs) were studied by means of differential scanning calorimeter(DSC) and X-ray diffraction(XRD).The crystallization processes of different samples were simulated by JMA equation.Experimental results demonstrated that incubation and crystallization time increased with decreasing isothermal temperature for the same sample.The crystallization mechanism of CeAlFeCo BMGs was discussed.

  5. Optical properties of the Ce and La ditelluride charge density wave compounds

    Energy Technology Data Exchange (ETDEWEB)

    Lavagnini, M.; Sacchetti, A.; Degiorgi, L.; /Zurich, ETH; Shin, K.Y.; Fisher, I.R.; /Stanford U., Geballe Lab. /Stanford U., Appl. Phys. Dept.

    2010-02-15

    The La and Ce di-tellurides LaTe{sub 2} and CeTe{sub 2} are deep in the charge-density-wave (CDW) ground state even at 300 K. We have collected their electrodynamic response over a broad spectral range from the far infrared up to the ultraviolet. We establish the energy scale of the single particle excitation across the CDW gap. Moreover, we find that the CDW collective state gaps a very large portion of the Fermi surface. Similarly to the related rare earth tri-tellurides, we envisage that interactions and Umklapp processes play a role in the onset of the CDW broken symmetry ground state.

  6. Kinetics of thermal decomposition of CeO2 nanocrystalline precursor prepared by precipitation method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The thermal decomposition of CeO2 nanocrystalline precursor prepared by chemical precipitation method was investigated using thermo-gravimetric/differential scanning calorimetry (TG/DSC) and X-ray powder diffraction (XRD).In particular,the differential thermal analysis curves for the decomposition of CeO2 nanocrystalline precursor were measured at different heating rates in air by a thermal analyzer (NETZSCH STA 449C,Germany).The kinetic parameters of the thermal decomposition of CeO2 nanocrystalline precursor were calculated using the Kissinger method and the Coats-Redfern method.Results show that the apparent active energy E of the reaction is 105.51 kJ/mol,the frequency factor lnA is 3.602 and the reaction order n is 2.This thermal decomposition process can be described by the anti-Jander equation and a threedimensional diffusion mechanism.

  7. Electrochemical behaviors of anodic alumina sealed by Ce-Mo in NaCl solutions

    Institute of Scientific and Technical Information of China (English)

    TIAN Lian-peng; ZHAO Xu-hui; ZHAO Jing-mao; ZHANG Xiao-feng; ZUO Yu

    2006-01-01

    The elimination of toxic materials in sealing methods for anodic films on 1070 aluminum alloy was studied. The new process uses chemical treatments in cerium solution and an electrochemical treatment in a molybdate solution. Potentiodynamic polarization and electrochemical impedance spectroscopy(EIS) were used to study the influences of sealing methods on the corrosion behavior of anodic films in NaCl solutions. The results show that the Ce-Mo sealing makes the surface structure and morphology of anodic films uniform and compact. Ce and Mo produce a cooperative effect to improve the corrosion resistance of anodic films. Anodic films sealed by Ce-Mo provide high corrosion resistance both in acidic and basic solutions.

  8. Laser-induced evaporation, reactivity and deposition of ZrO 2, CeO 2, V 2O 5 and mixed Ce-V oxides

    Science.gov (United States)

    Flamini, C.; Ciccioli, A.; Traverso, P.; Gnecco, F.; Giardini Guidoni, A.; Mele, A.

    2000-12-01

    It has been found that pulsed laser ablation has good potentiality for the deposition of ZrO2, CeO2, V2O5 and mixed Ce-V oxides which are very important materials for their application in optics and electrochromic devices. Laser induced compositional changes of thin films in the ablation and deposition processes of these materials have been explored. The effect of the oxygen gas pressure on the thin film composition has been examined. The congruency of the process has been treated on the basis of a thermal mechanism of evaporation-decomposition of the compounds. An attempt to model the processes by means of a thermodynamic approach is reported.

  9. Water Dissociation on CeO2(100) and CeO2(111) Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Mullins, David R [ORNL; Albrecht, Peter M [ORNL; Chen, Tsung-Liang [ORNL; Calaza, Florencia C [ORNL; Biegalski, Micahel [Oak Ridge National Laboratory (ORNL); Christen, Hans [Oak Ridge National Laboratory (ORNL); Overbury, Steven {Steve} H [ORNL

    2012-01-01

    This study reports and compares the adsorption and dissociation of water on oxidized and reduced CeO{sub 2}(100) and CeO{sub 2}(111) thin films. Water adsorbs dissociatively on both surfaces. On fully oxidized CeO{sub 2}(100) the resulting surface hydroxyls are relatively stable and recombine and desorb as water over a range from 200 to 600 K. The hydroxyls are much less stable on oxidized CeO{sub 2}(111), recombining and desorbing between 200 and 300 K. Water produces 30% more hydroxyls on reduced CeO{sub 1.7}(100) than on oxidized CeO{sub 2}(100). The hydroxyl concentration increases by 160% on reduced CeO{sub 1.7}(111) compared to oxidized CeO{sub 2}(111). On reduced CeO{sub 1.7}(100) most of the hydroxyls still recombine and desorb as water between 200 and 750 K. Most of the hydroxyls on reduced CeO{sub 1.7}(111) react to produce H{sub 2} at 560 K, leaving O on the surface. A relatively small amount of H{sub 2} is produced from reduced CeO{sub 1.7}(100) between 450 and 730 K. The differences in the adsorption and reaction of water on CeO{sub X}(100) and CeO{sub X}(111) are attributed to different adsorption sites on the two surfaces. The adsorption site on CeO{sub 2}(100) is a bridging site between two Ce cations. This adsorption site does not change when the ceria is reduced. The adsorption site on CeO{sub 2}(111) is atop a single Ce cation, and the proton is transferred to a surface O in a site between three Ce cations. When the CeO{sub X}(111) is reduced, vacancy sites are produced which allows the water to adsorb and dissociate on the 3-fold Ce cation sites.

  10. A comparison between Ce(III) and Ce(IV) ions in photocatalytic degradation of organic pollutants

    Institute of Scientific and Technical Information of China (English)

    程强; 施薇; 段炼; 孙彬哲; 李晓霞; 徐爱华

    2015-01-01

    Nano cerium oxides are efficient photocatalysts for pollutants degradation with highly dispersed Ce(III) ions as the sug-gested active species to promote the reaction, while Ce(IV) species do not behave as a catalyst. In this paper, to understand the mechanism of Ce-based photocatalysts, we studied the comparison of simple cerium ions, Ce(III) and Ce(IV) in aqueous solution for organic pollutants degradation under UV irradiation. Orange II (AOII), methyl orange, andp-nitrophenol were selected as the target pollutants. The formation and contribution of reactive oxygen species, the kinetics of Ce(IV) photoreduction and Ce(III) photooxida-tion, and the influence of solution pH were investigated in detail. It was found that at low pH Ce(IV) ions showed a higher activity for hydroxyl radicals production and AOII degradation than Ce(III) ions, which could be attributed to its fast reduction rate to Ce(III). However, its activity dramatically decreased when solution pH increased, and was also strongly influenced by the type of pollutants; while Ce(III) exhibited high degradation efficiency of all the tested pollutants over a wide pH range.

  11. Influence of γ-radiation on photoluminescence properties of YPO4:Eu3+,Ce3+ and YPO4:Dy3+,Ce3+ phosphors

    Science.gov (United States)

    Gurugubelli, Sudheer; Dadhich, Anima S.; Saha, Abhijit; Babu Mukkamala, Saratchandra

    2015-10-01

    Hexagonal YPO4 phosphors doped with Eu3+/Dy3+ and co-doped with Ce3+ were synthesized by a hydrothermal route assisted using lauric acid as a capping agent. The prepared phosphors were characterized by transmission electron microscopy, infrared spectroscopy, powder X-ray diffraction and photoluminescence spectra. YPO4: Eu3+ gives two red emission peaks at 587 and 610 nm corresponding to 5D0→7F1 and 5D0→7F2 transitions, respectively. YPO4: Dy3+ exhibits two emission peaks at 485 nm (blue) and 575 nm (yellow) corresponding to 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions, respectively. Ce3+ ions enhanced the emission intensity as a co-dopant in both phosphors. Moreover, the effect of γ-radiation in the dose range 5-300 kGy on the photoluminescence behaviour of YPO4:Eu3+,Ce3+ and YPO4:Dy3+,Ce3+ was also investigated. Quenching of emission intensity, after irradiation at 5 and 300 kGy, was observed in both the phosphors due to loss of excess energy through a non-radiative relaxation process.

  12. Electronic structure of LaTe and CeTe

    Energy Technology Data Exchange (ETDEWEB)

    Chainani, A., E-mail: chainania@gmail.com [RIKEN SPring-8 Centre, 1-1-1 Kouto, Hyogo 679-5148 (Japan); Department of Physics, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578 (Japan); Oura, M. [RIKEN SPring-8 Centre, 1-1-1 Kouto, Hyogo 679-5148 (Japan); Matsunami, M. [UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan); Ochiai, A.; Takahashi, T. [Department of Physics, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578 (Japan); Tanaka, Y. [RIKEN SPring-8 Centre, 1-1-1 Kouto, Hyogo 679-5148 (Japan); Graduate School of Material Science, University of Hyogo, 3-2-1 Kouto, Hyogo 678-1297 (Japan); Tamasaku, K.; Kohmura, Y.; Ishikawa, T. [RIKEN SPring-8 Centre, 1-1-1 Kouto, Hyogo 679-5148 (Japan)

    2016-04-15

    Highlights: • Hard X-ray and soft X-ray photoelectron spectroscopy of LaTe and CeTe. • Evidence for Kondo screening in antiferromagnetic(T{sub N} = 2.2 K) compound CeTe. • Suppressed Kondo resonance in CeTe compared to typical Kondo materials. - Abstract: We report a comparative study of the electronic structure of the compounds LaTe and CeTe, both of which crystallize in the rock salt structure. LaTe is a paramagnetic metal while CeTe is known to exhibit anomalous Kondo-like transport behaviour and undergoes a transition to a complex magnetically ordered state at low temperature (T{sub N} = 2.2 K). We carry out hard X-ray photoelectron spectroscopy (HAXPES) of the core-levels and valence band of LaTe and CeTe at T = 20 K, in order to characterize their intrinsic electronic structure, and to address the role of Kondo effect on the electronic structure of CeTe. The bulk sensitive core level HAXPES spectra show evidence of screened features in the La 3d and Ce 3d states mixed with plasmon features. From a careful analysis of the Te, La and Ce derived core levels, we separate out the respective origins of the satellites and show that CeTe indeed exhibits definitive but weak f{sup 0} and f{sup 2} satellites due to Kondo screening, in addition to the main f{sup 1} peak. The comparison of the valence band spectra of CeTe obtained using HAXPES and soft X-ray PES clearly identifies the Ce 4f derived features. Resonant photoelectron spectrosocopy across the Ce 3d − 4f threshold confirms the Ce 4f{sup 1} final state at the Fermi level, corresponding to the tail of the Kondo resonance feature which occurs above the Fermi level, while the Ce 4f{sup 0} final state feature is observed at a binding energy of 2.4 eV. The 4f{sup 0} and 4f{sup 1} final states show giant resonances compared to the off-resonant spectra. However, in contrast to typical Kondo systems, the tail of the Ce 4f{sup 1} Kondo resonance at the Fermi level is relatively suppressed compared to the Ce 4f

  13. Enhancement of photocatalytic activity of combustion-synthesized CeO2/C3N4 nanoparticles

    Science.gov (United States)

    Li, Dong-Feng; Yang, Ke; Wang, Xiao-qin; Ma, Ya-Li; Huang, Gui-Fang; Huang, Wei-Qing

    2015-09-01

    Nanocrystalline CeO2/C3N4 was synthesized via a one-step solution combustion method using urea as fuel for the first time. The effects of the molar ratio of urea to cerium chloride on the photocatalytic activity of the synthesized samples were investigated. The synthesized nanocrystalline CeO2/C3N4 shows small size and large surface exposure area. Photocatalytic degradation of methylene blue demonstrates that the synthesized nanocrystalline CeO2/C3N4 possesses enhanced photocatalytic activity. It is proposed that the enhanced photocatalytic activity might be related to the favorable morphology and structure, and the effective charge separation between C3N4 and CeO2 in the photocatalytic process.

  14. Preparation of AAO-CeO2 nanotubes and their application in electrochemical oxidation desulfurization of diesel

    Science.gov (United States)

    Du, Xiaoqing; Yang, Yumeng; Yi, Chenxi; Chen, Yu; Cai, Chao; Zhang, Zhao

    2017-02-01

    The coaxial arrays of AAO-CeO2 NTs have been successfully galvanostatically deposited on an anode, characterized and adopted as a catalyst for removing organic sulfurs from diesel. The influence of the main electrochemical oxidation factors on the efficiency of desulfurization have also been investigated. The results show that the fabrication process of AAO-CeO2 NTs is accompanied by the formation of a new phase, namely Al3Ce, and the main oxidation products of the diesel are soluble inorganic sulphides, especially Ce2(SO4)3. When compared with dibenzothiophene and 4, 6-dimethyldibenzothiophene, benzothiophene is much more easily removed, with a removal efficiency that reaches 87.2%. Finally, a possible electrochemical oxidation desulfurization pathway for diesel is proposed.

  15. Effects of Ce on catalytic combustion of methane over Pd-Pt/Al2O3 catalyst

    Institute of Scientific and Technical Information of China (English)

    Xing Fan; Fan Wang; Tianle Zhu; Hong He

    2012-01-01

    Activity and stability of 1%Pd-0.2%Pt/Al2O3 and 1%Pd-0.2%Pt/0.6%Ce/Al2O3 catalysts prepared by impregnation method for catalytic combustion of methane in air were investigated.The catalysts before and after reaction were characterized by BET,CO chemisorption,XRD and XPS techniques.Results showed that the presence of Ce significantly increased the activity and thermal stability of the Pd-Pt/Al2O3 catalyst towards methane combustion,which could be attributed to more highly-dispersed active PdO particles over the Pd-Pt/Ce/Al2O3 catalyst surface as well as the retarded sintering of PdO and the maintained oxidized state of surface Pd during the combustion process in the presence of Ce.

  16. Catalytic Reduction of SO2 on CeO2-La2O3 Rare Earth Mixed Compounds

    Institute of Scientific and Technical Information of China (English)

    胡辉; 李劲; 程国宏; 李胜利

    2004-01-01

    Adding rare earth oxide CeO2 with variable valences to La2O3 formed a mixture of rare earth oxides. By means of dipping CeO2, La2O3 and their mixture, whose carriers were all γ-Al2O3, were used as the catalyst for the reduction of SO2 by CO. The activation process of this catalyst and the impact of temperature and reactant concentration on the activation process were investigated. Using X-ray diffraction, the structure characteristics of catalyst before and after reaction were analyzed to reveal the change of phase structure. The result shows that the rare earth oxide mixtures composing of CeO2 and La2O3, as the catalyst for the reduction of SO2 by CO, diminish activation temperature 50~100 ℃ less and have higher activity than a single oxide CeO2 or La2O3. The reason possibl is that La2O3 goes into in the lattice of CeO2 to form solid phase complex CeO2-La2O3 and increases the capability of CeO2-La2O3/γ-Al2O3 catalyst to store oxygen, which supplies the redox of CeO2 reaction with a better condition. At the same time, elemental sulfur formed in the redox reaction impels La2O3 to be transformed to activation phase La2O2S in a lower temperature, which can be explained with the synergism between redox reaction and COS intermediate mechanism reaction.

  17. Microwave-assisted hydrothermal synthesis of CePO{sub 4} nanostructures: Correlation between the structural and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Palma-Ramírez, D. [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Domínguez-Crespo, M.A., E-mail: mdominguezc@ipn.mx [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Torres-Huerta, A.M. [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Dorantes-Rosales, H. [Instituto Politécnico Nacional, ESIQIE, Departamento de Metalurgia, C.P. 07300 México D.F. (Mexico); Ramírez-Meneses, E. [Universidad Iberoamericana, Departamento de Ingeniería y Ciencias Químicas, Prolongación Paseo de la Reforma 880, Lomas de Santa Fe, C.P. 01219 México D.F. (Mexico); Rodríguez, E. [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico)

    2015-09-15

    Highlights: • An enhancement in the hydrothermal synthesis for obtaining of CePO{sub 4} is presented. • Microwave energy can replace the energy by convection for obtaining CePO{sub 4}. • CePO{sub 4} demonstrates to be an option to increase the optical properties of polymers. • Adjusting the pH, the sintering process is not necessary to obtain the desire phase. • CePO{sub 4} morphologies undergo evolution from nanorods to semispherical nanoparticles. - Abstract: In this work, the microwave-assisted hydrothermal method is proposed as an alternative to the synthesis of cerium phosphate (CePO{sub 4}) nanostructures to evaluate the influence of different synthesis parameters on both the structural and optical properties. In order to reach this goal, two different sets of experiments were designed, varying the reaction temperature (130 and 180 °C), synthesis time (15 and 30 min) and sintering temperature (400 and 600 °C), maintaining a constant pH = 3. Thereafter, two experimental conditions were selected to assess changes in the properties of CePO{sub 4} nanopowders with pH (1, 5, 9 and 11). The crystal structure and morphology of the nanostructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. Diffuse reflectance properties of CePO{sub 4} with different microstructures were studied. The results demonstrated that by using the microwave-assisted hydrothermal method, the shape, size and structural phase of CePO{sub 4} can be modulated by using relatively low synthesis temperatures and short reaction times, and depending on pH, a sintering process is not needed to obtain either a desired phase or size. Under the selected experimental conditions, the materials underwent an evolution from nanorods to semispherical nanoparticles, accompanied by a phase transition from hexagonal to monoclinic.

  18. Long-Time Variation in Magnetic Structure of Ce(IrxRh1-x)3Si2: A New Interpretation of Time Variation

    Science.gov (United States)

    Motoya, Kiyoichiro; Hagihala, Masato; Kimura, Shuji; Matsuda, Masaaki; Ouladdiaf, Bachir

    2017-03-01

    To clarify the key factor for the slow magnetic transitions in CeIr3Si2 and other materials, magnetization and neutron scattering measurements have been carried out on the system Ce(IrxRh1-x)3Si2. In this system, a magnetic phase transition is accomplished through slow and fast processes. The fractions of these processes vary with the chemical composition x. A new interpretation of magnetic phase transitions, which includes the coexistence of two processes, is presented.

  19. Characterization of CeO{sub 2} crystals synthesized with different amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Atla, Shashi B. [Department of Earth and Environmental Sciences, National Chung Cheng University, Minhsiung, Chiayi 621, Taiwan (China); Wu, Min-Nan; Pan, Wei; Hsiao, Yu Tang [Department of Physics, National Chung Cheng University, Minhsiung, Chiayi 621, Taiwan (China); Sun, An-Cheng [Department of Chemical Engineering and Materials Science, Yuan Ze University, No. 135 Yuan-Tung Road, Chungli, Taoyuan 320, Taiwan (China); Tseng, Min-Jen [Department of Life Science, National Chung Cheng University, 168 University Road, Minhsiung, Chiayi 621, Taiwan (China); Chen, Yen-Ju [Department of Earth and Environmental Sciences, National Chung Cheng University, Minhsiung, Chiayi 621, Taiwan (China); Chen, Chien-Yen, E-mail: yen@eq.ccu.edu.tw [Department of Earth and Environmental Sciences, National Chung Cheng University, Minhsiung, Chiayi 621, Taiwan (China); Department of Advanced Institute of Manufacturing with High-tech Innovations, National Chung Cheng University, Minhsiung, Chiayi 621, Taiwan (China)

    2014-12-15

    We investigated the relationship between the structures of the CeO{sub 2} products (particle size, morphology and their characteristics) prepared using different amino acids. Cerium hydroxide carbonate precursors were initially prepared by a hydrothermal method and were subsequently converted to CeO{sub 2} by its thermal decomposition. Various amino acids were used as structure-directing agents in the presence of cerium nitrate and urea as precursors. The results indicate morphology selectivity using different amino acids; CeO{sub 2} structures, such as quasi-prism-sphere, straw-bundle, urchin-flower like and polyhedron prisms, indeed could be produced. Raman and photoluminescence studies indicate the presence of oxygen vacancies in the CeO{sub 2} samples. Photoluminescence spectra of CeO{sub 2} with L-Valine exhibit stronger emission compared with other amino acids utilized under this study, indicating the higher degree of defects in these particles. This study clearly indicates that the degree of defects varied in the presence of different amino acids. Improved precision to control the crystal morphology is important in various material applications and our study provides a novel method to achieve this specificity. - Highlights: • We used urea hydrolysis of process for synthesis of CeO{sub 2}. • Structures have been directed using various amino acids. • We obtained straw bundle-like, quasi prism-sphere, polyhedron prisms and urchin flower-like based on amino acids. • We have found that amino acids could achieve the specificity of different degrees of defects. • This could provide the “tailor-make” of cerium crystals.

  20. Facile hydrothermal synthesis of CeO2 nanopebbles

    Indian Academy of Sciences (India)

    N Sabari Arul; D Mangalaraj; Jeong In Han

    2015-09-01

    Cerium oxide (CeO2) nanopebbles have been synthesized using a facile hydrothermal method. X-ray diffraction pattern (XRD) and transmission electron microscopy analyses confirm the presence of CeO2 nanopebbles. XRD shows the formation of cubic fluorite CeO2 and the average particle size estimated from the Scherrer formula was found to be 6.69 nm. X-ray absorption spectrum of CeO2 nanopebbles exhibits two main sharp white lines at 880 and 898 eV due to the spin orbital splitting of 4 and 5. Optical absorption for the synthesized CeO2 nanopebbles exhibited a blue shift (g = 3.35 eV) with respect to the bulk CeO2 (g = 3.19 eV), indicating the existence of quantum confinement effects.

  1. A thermodynamic assessment of Ce-Al system

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The optimized descriptions of the phase diagram and thermodynamic properties for Ce-Al system have been obtained from experimental thermodynamic and phase diagram data by means of the computer program THERMO-CALC based on the least squares method, using models for the Gibbs energy of individual phases. The system contains five intermetallic compounds. The calculated standard enthalpies of Ce3Al, CeAl, CeAl2, CeAl3 and Ce3Al11 are -26.7, -48.9, -48.4, -44.0 and -41.7 kJ/mol, respectively. A consistent set of thermodynamic parameters was derived. The optimized and experimental data are in good agreement.

  2. Windows CE自定制Shell%Customizing Windows CE Shell

    Institute of Scientific and Technical Information of China (English)

    覃朗; 雷跃明

    2010-01-01

    Shell是用户访问操作系统的接口.Shell开发在Windows CE操作系统开发中占据一定的重要性.对Windows CE Shell进行了概述,并通过建立Shell模型,讲述如何自定制Windows CE Shell和定制Shell必须注意的问题,对Windows CE Shell的定制进行深入研究.

  3. Fabrication and characterization of CeO{sub 2} pellets for simulation of nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    García-Ostos, C.; Rodríguez-Ortiz, J.A. [Department of Mechanical and Materials Engineering, School of Engineering, University of Seville, Seville (Spain); Arévalo, C., E-mail: carevalo@us.es [Department of Mechanical and Materials Engineering, School of Engineering, University of Seville, Seville (Spain); Cobos, J. [CIEMAT, Avenida Complutense, 40, Madrid (Spain); Gotor, F.J. [Materials Science Institute of Seville (CSIC-US), Av. Américo Vespucio, 49, 41092 Seville (Spain); Torres, Y. [Department of Mechanical and Materials Engineering, School of Engineering, University of Seville, Seville (Spain)

    2016-03-15

    Highlights: • CeO{sub 2} is presented as a surrogate material for UO{sub 2} to study nuclear fuel. • Powder-metallurgy methods are applied to fabricate CeO{sub 2} pellets with controlled porosity. • An optimization of the fabrication parameters is established. • Microstructural and tribo-mechanical characterizations are performed. • Properties are compared to those of the nuclear fuel. - Abstract: Cerium Oxide, CeO{sub 2}, has been shown as a surrogate material to understand irradiated Mixed Oxide (MOX) based matrix fuel for nuclear power plants due to its similar structure, chemical and mechanical properties. In this work, CeO{sub 2} pellets with controlled porosity have been developed through conventional powder-metallurgy process. Influence of the main processing parameters (binder content, compaction pressure, sintering temperature and sintering time) on porosity and volumetric contraction values has been studied. Microstructure and physical properties of sintered compacts have also been characterized through several techniques. Mechanical properties such as dynamic Young's modulus, hardness and fracture toughness have been determined and connected to powder-metallurgy parameters. Simulation of nuclear fuel after reactor utilization with radial gradient porosity is proposed.

  4. Valence Fluctuations in CeCo2 and Ti-Doped CeCo2

    Science.gov (United States)

    Öner, Yıldırhan

    2016-12-01

    We report on the magnetic measurements of polycrystalline samples of CeCo2 and CeCo(2-x)Ti x (x = 0.01, 0.02, 0.03, 0.04, and 0.05) which have been synthesized by an arc melting technique. All these compounds crystallize into the face-centered cubic (FCC) structure with the Fd bar{3} m space group. The lattice parameter decreases linearly with increasing Ti content from 7.15808(5) Å for x = 0 (CeCo2) to 7.15231(7) Å for x = 0.05. The magnetic behavior of these compounds has been investigated in the temperature range 5-400 K. The zero field-cooled (ZFC) and field-cooled magnetization (FC) curves show irreversibility below T = 400 K. This result indicates that an inhomogeneous, dynamic magnetic state exists over a wide temperature range. The magnetic susceptibility for both ZFC and FC cases initially decreases with Ti content and then increases with further Ti addition. This behavior is interpreted in terms of band magnetism in the presence of magnetic clusters. This result indicates that the magnetic inhomogeneity of these alloys becomes dominant over a wide temperature range. The observed temperature dependence of the magnetic susceptibility leads us to suggest that these compounds are in a mixed-valence state of the magnetic Ce3+ ions and non-magnetic Ce4+ ions. This fact allows us to successfully interpret the ZFC magnetic susceptibility data with the two-level ionic inter-configuration fluctuations model. We also observe that the magnetic susceptibility increases by the addition of Ti, as evidenced by the enhancement of the formation of magnetic Co clusters due to local disorder. Finally, the magnetic state below the Curie temperatures are discussed based on Griffiths-like behavior.

  5. Inverted opal luminescent Ce-doped silica glasses

    Directory of Open Access Journals (Sweden)

    R. Scotti

    2006-01-01

    Full Text Available Inverted opal Ce-doped silica glasses (Ce : Si molar ratio 1 ⋅ 10−3 were prepared by a sol-gel method using opals of latex microspheres as templates. The rare earth is homogeneously dispersed in silica host matrix, as evidenced by the absence of segregated CeO2, instead present in monolithic Ce-doped SG with the same cerium content. This suggests that the nanometric dimensions of bridges and junctions of the host matrix in the inverted opal structures favor the RE distribution avoiding the possible segregation of CeO2.

  6. Preparation and photocatalyticactivity of CuO/CeO2 nanocomposites%CuO/CeO2复合物的制备及其光催化性质研究

    Institute of Scientific and Technical Information of China (English)

    张晓娟; 张胜义

    2012-01-01

    In the presence of the CTAB soft template, the CuO/CeO2 nanocomposites were prepared by co-precipitation process. The product was characterized by TEM,XRD and UV-vis spectra. The experimental results showed that CuO/CeO2 nanocomposites had a strong adsorptive decolorization activity for organic dye alizarin red. Furthermore, its decolorization activity for alizarin red increased with the increase of the CuO content. Under illumination, this decolorization activity could be further enhanced due to the catalysis of the CuO/ CeO2 nanocomposites.%以CTAB为模板采用共沉淀法合成CuO/CeO2复合物,用透射电镜、X射线粉末衍射和紫外可见光谱对复合物进行表征;研究CuO/CeO2复合物对茜素红的催化脱色效果.实验结果表明,CuO/CeO2复合物既具有吸附作用也具有光催化降解作用,且随着CuO含量和催化剂用量的增加催化脱色效果有明显提高.

  7. CeO2 nanocrystallines ensemble-on-nitrogen-doped graphene nanocomposites: one-pot, rapid synthesis and excellent electrocatalytic activity for enzymatic biosensing.

    Science.gov (United States)

    Du, Xiaojiao; Jiang, Ding; Chen, Saibo; Dai, Liming; Zhou, Lei; Hao, Nan; You, Tianyou; Mao, Hanping; Wang, Kun

    2017-03-15

    Ceria nanomaterials for heterogeneous catalysis have attracted much attention due to their excellent properties and have been extensively applied in recent years. But the poor electron conductivity and the aggregation behavior severely affect their electrocatalytic performances. In this paper, we prepared a novel catalyst based on CeO2 nanocrystallines (CeO2 NCs) ensemble-on-nitrogen-doped graphene (CeO2-NG) nanocomposites through a one-step heat-treatment without the need of the precursor. The results confirmed that the high dispersion of CeO2 NCs with the uniform size distribution of about 5nm on the surface of nitrogen-doped graphene (NG) sheets could be easily obtained via the one-step procedure and the resultant CeO2-NG nanocomposites were an excellent electrode material possessing outstanding electrochemical features for electron transfer. Luminol, an important electroactive substance, was further chosen to inspect the electrocatalytic properties of the as-prepared CeO2-NG nanocomposites. The studies showed that the presence of the NG in CeO2-NG nanocomposites could facilitate the electrochemical redox process of luminol. Compared with pristine CeO2 NCs, the synthesized CeO2-NG nanocomposites can enhance the electrochemiluminescence (ECL) intensity by 3.3-fold and decrease the onset ECL potential for about 72mV in the neutral condition. Employing above superiority, selecting cholesterol oxidase (ChOx) as the model oxidase, a facile ECL method for cholesterol detection with the CeO2-NG nanocomposites as the matrix to immobilize enzyme ChOx was developed. The results demonstrated CeO2-NG nanocomposites exhibited excellent performances in terms of sensitivity and catalytic activities, indicating that NG-based nanomaterials have great promise in electrocatalytic and enzymatic biosensing fields.

  8. Luminescence and energy transfer properties of Sr{sub 3}Y(PO{sub 4}){sub 3}:Ce{sup 3+}, Mn{sup 2+} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jun; Hu, Yihua, E-mail: huyh@gdut.edu.cn; Chen, Li; Wang, Zhonghua; Zhang, Shaoan

    2016-03-15

    A series of highly efficient Sr{sub 3−y}Y{sub 1−x}(PO{sub 4}){sub 3}:xCe{sup 3+},yMn{sup 2+}(SYP:xCe{sup 3+}, Mn{sup 2+}) phosphors have been prepared via a solid state reaction. The XRD (X-ray diffraction) data, PL (photoluminescence) and PLE (photoluminescence excitation) properties and ET (energy transfer) mechanism of obtained phosphors were discussed. When prepared in air, the self-reducing process of turning Ce{sup 4+} into Ce{sup 3+} can be found in SYP:xCe{sup 3+} phosphor. A bright red light emission was presented in the Ce{sup 3+} and Mn{sup 2+} co-doping samples via the efficient ET from the sensitizer Ce{sup 3+} to Mn{sup 2+}, which is ascribed to electric multipolar interaction between these two kinds of ions. The critical concentration of Ce{sup 3+} in SrY{sub 1−x}(PO{sub 4}){sub 3}:xCe{sup 3+} and Mn{sup 2+} in Sr{sub 3−y}Y{sub 1−x}(PO{sub 4}){sub 3}:xCe{sup 3+}, yMn{sup 2+} are x=0.07 and y=0.15, respectively. In addition, the ET efficiency reach 51.6% when the luminescence intensity of Ce{sup 3+} is half of that in the absence of Mn{sup 2+} and the concentration of Mn{sup 2+} is 0.15. The emission color of the phosphors were also clarify by CIE coordinate briefly.

  9. A comparative study of Mn/CeO2, Mn/ZrO2 and Mn/Ce-ZrO2 for low temperature selective catalytic reduction of NO with NH3 in the presence of SO2 and H2O.

    Science.gov (United States)

    Shen, Boxiong; Zhang, Xiaopeng; Ma, Hongqing; Yao, Yan; Liu, Ting

    2013-04-01

    Ce-ZrO2 is a widely used three-way catalyst support. Because of the large surface area and excellent redox quality, Ce-ZrO2 may have potential application in selective catalytic reduction (SCR) systems. In the present work, Ce-ZrO2 was introduced into a low-temperature SCR system and CeO2 and ZrO2 supports were also introduced to make a contrastive study. Mn/CeO2, Mn/ZrO2 and Mn/Ce-ZrO2 were prepared by impregnating these supports with Mn(NO3)2 solution, and have been characterized by N2-BET, XRD, TPR, TPD, XPS, FT-IR and TG. The activity and resistance to SO2 and H2O of the catalysts were investigated. Mn/Ce-ZrO2 and Mn/CeO2 were proved to have better low-temperature activities than Mn/ZrO2, and yielded 98.6% and 96.8% NO conversion at 180 degrees C, respectively. This is mainly because Mn/Ce-ZrO2 and Mn/CeO2 had higher dispersion of manganese oxides, better redox properties and more weakly adsorbed oxygen species than Mn/ZrO2. In addition, Mn/Ce-ZrO2 showed a good resistance to SO2 and H2O and presented 87.1% NO conversion, even under SO2 and H2O treatment for 6 hours, and the activity of Mn/Ce-ZrO2 was almost restored to its original level after cutting off the injection of SO2 and H2O. This was due to the weak water absorption and weak sulfation process on the surface of the catalyst.

  10. Mechanism of Methane Chemical Looping Combustion with Hematite Promoted with CeO 2

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Duane D.; Siriwardane, Ranjani

    2013-08-15

    Chemical looping combustion (CLC) is a promising technology for fossil fuel combustion that produces sequestration-ready CO{sub 2} stream, reducing the energy penalty of CO{sub 2} separation from flue gases. An effective oxygen carrier for CLC will readily react with the fuel gas and will be reoxidized upon contact with oxygen. This study investigated the development of a CeO{sub 2}-promoted Fe{sub 2}O{sub 3}-hematite oxygen carrier suitable for the methane CLC process. Composition of CeO{sub 2} is between 5 and 25 wt % and is lower than what is generally used for supports in Fe{sub 2}O{sub 3} carrier preparations. The incorporation of CeO{sub 2} to the natural ore hematite strongly modifies the reduction behavior in comparison to that of CeO{sub 2} and hematite alone. Temperature-programmed reaction studies revealed that the addition of even 5 wt % CeO{sub 2} enhances the reaction capacity of the Fe{sub 2}O{sub 3} oxygen carrier by promoting the decomposition and partial oxidation of methane. Fixed-bed reactor data showed that the 5 wt % cerium oxides with 95 wt % iron oxide produce 2 times as much carbon dioxide in comparison to the sum of carbon dioxide produced when the oxides were tested separately. This effect is likely due to the reaction of CeO{sub 2} with methane forming intermediates, which are reactive for extracting oxygen from Fe{sub 2}O{sub 3} at a considerably faster rate than the rate of the direct reaction of Fe{sub 2}O{sub 3} with methane. These studies reveal that 5 wt % CeO{sub 2}/Fe{sub 2}O{sub 3} gives stable conversions over 15 reduction/oxidation cycles. Lab-scale reactor studies (pulsed mode) suggest the methane reacts initially with CeO{sub 2} lattice oxygen to form partial oxidation products (CO + H{sub 2}), which continue to react with oxygen from neighboring Fe{sub 2}O{sub 3}, leading to its complete oxidation to form CO{sub 2}. The reduced cerium oxide promotes the methane decomposition reaction to form C + H{sub 2}, which continue to

  11. MnO2/CeO2 for catalytic ultrasonic degradation of methyl orange.

    Science.gov (United States)

    Zhao, He; Zhang, Guangming; Zhang, Quanling

    2014-05-01

    Catalytic ultrasonic degradation of aqueous methyl orange was studied in this paper. Heterogeneous catalyst MnO2/CeO2 was prepared by impregnation of manganese oxide on cerium oxide. Morphology and specific surface area of MnO2/CeO2 catalyst were characterized and its composition was determined. Results showed big differences between fresh and used catalyst. The removal efficiency of methyl orange by MnO2/CeO2 catalytic ultrasonic process was investigated. Results showed that ultrasonic process could remove 3.5% of methyl orange while catalytic ultrasonic process could remove 85% of methyl orange in 10 min. The effects of free radical scavengers were studied to determine the role of hydroxyl free radical in catalytic ultrasonic process. Results showed that methyl orange degradation efficiency declined after adding free radical scavengers, illustrating that hydroxyl free radical played an important role in degrading methyl orange. Theoretic analysis showed that the resonance size of cavitation bubbles was comparable with the size of catalyst particles. Thus, catalyst particles might act as cavitation nucleus and enhance ultrasonic cavitation effects. Measurement of H2O2 concentration in catalytic ultrasonic process confirmed this hypothesis. Effects of pre-adsorption on catalytic ultrasonic process were examined. Pre-adsorption significantly improved methyl orange removal. The potential explanation was that methyl orange molecules adsorbed on catalysts could enter cavitation bubbles and undergo stronger cavitation.

  12. Mineralization of volatile organic compounds (VOCs) over the catalyst CuO-Co3O4-CeO2 and its applications in industrial odor control

    KAUST Repository

    Somekawa, Shouichi

    2011-12-01

    Volatile organic compounds (VOCs) present at ppm levels were decomposed over the catalyst CuO-Co3O4-CeO2 (Cu:Co:Ce = 10:45:45 in mol) in an attempt to scale up for industrial odor control. In addition to enhancing the catalytic activity, CuO-Co3O4 and CeO2 helped, respectively, to maintain the strength of the pelleted catalysts and inhibit their sintering. Using toluene as a VOC model compound, kinetic analysis of the total oxidation to carbon dioxide was conducted. The odor emitted from paint-drying processes could be eliminated effectively using CuO-Co3O4-CeO2 (Cu:Co:Ce = 10:45:45) pelleted catalysts (188 ml) in a large-scale system. © 2011 Elsevier B.V. All rights reserved.

  13. Thermodynamic Equilibrium Studies of Nanocrystallite CeO2 Grain Boundaries by High Temperature X-Ray Photoelectron Spectroscopy and Thermal Gravimetric Analysis

    Institute of Scientific and Technical Information of China (English)

    LIU Zhen-Xiang; XIE Kan

    2000-01-01

    Nanostructured CeO2 thin films and powders are studied by high temperature x-ray photoelectron spectroscopy and thermal gravimetric analysis. The results indicate that the surface composition strongly depends on temperature, the surface O/Ce ratio initially increases with increasing temperature, then decreases with the further increase of temperature, the maximum surface O/Ce ratio is at about 300℃ C. The variation of the surface composition with temperature arises from the ion migration, redistribution and transformation between lattice oxygen and gas phase oxygen near the grain boundaries during the thermodynamic equilibrium process. The results also show that CeO2 has a weakly bond oxygen, high oxygen mobility in the bulk and a high molecular dissociation rate at the surface, especially for the sol-gel prepared nanocrystallite CeO2.

  14. Scintillation and luminescence characteristics of Ce3+doped in Li2O-Gd2O3-BaO-B2O3 scintillating glasses

    Science.gov (United States)

    Zaman, F.; Rooh, G.; Srisittipokakun, N.; Kim, H. J.; Kaewnuam, E.; Meejitpaisan, P.; Kaewkhao, J.

    2017-01-01

    Ce3+ activated Li2O-Gd2O3-BaO-B2O3glass scintillator containing neutron-capture elements (7Li, 11Band 158Gd)were developed by conventional melt-quenching technique. Luminescence spectra under UV and X-ray excitation showed Ce3+ion emission due to 5d→4f transition at 391 nm. Energy transfer from the host glass to Ce3+ions were confirmed by VUV-UV and XEL spectra. The highest emission intensity of Ce3+ions were observed at 0.5 mol%of CeF3. For the same concentration the decay time was obtained to be 19.7 ns and their mean critical distance was calculated about 22.33 Å. The observed decay constants revealed that direct electron-hole capture was a dominant scintillation process in the present glass matrix.

  15. Validation of the tool assessment of clinical education (AssCE): A study using Delphi method and clinical experts.

    Science.gov (United States)

    Löfmark, Anna; Mårtensson, Gunilla

    2017-03-01

    The aim of the present study was to establish the validity of the tool Assessment of Clinical Education (AssCE). The tool is widely used in Sweden and some Nordic countries for assessing nursing students' performance in clinical education. It is important that the tools in use be subjected to regular audit and critical reviews. The validation process, performed in two stages, was concluded with a high level of congruence. In the first stage, Delphi technique was used to elaborate the AssCE tool using a group of 35 clinical nurse lecturers. After three rounds, we reached consensus. In the second stage, a group of 46 clinical nurse lecturers representing 12 universities in Sweden and Norway audited the revised version of the AssCE in relation to learning outcomes from the last clinical course at their respective institutions. Validation of the revised AssCE was established with high congruence between the factors in the AssCE and examined learning outcomes. The revised AssCE tool seems to meet its objective to be a validated assessment tool for use in clinical nursing education.

  16. Hydrogen and syngas production from two-step steam reforming of methane using CeO2 as oxygen carrier

    Institute of Scientific and Technical Information of China (English)

    Xing Zhu; Hua Wang; Yonggang Wei; Kongzhai Li; Xianming Cheng

    2011-01-01

    CeO2 oxygen carrier was prepared by precipitation method and tested by two-step steam reforming of methane (SRM).Two-step SRM for hydrogen and syngas generation is investigated in a fixed-bed reactor.Methane is directly converted to syngas at a H2/CO ratio close to 2∶ 1 at a high temperature (above 750 ℃) by the lattice oxygen of CeO2; methane cracking is found when the reduction degree of CeO2 was above 5.0% at 850 ℃ in methane isothermal reaction.CeO2-δ obtained from methane isothermal reaction can split water to generate CO-free hydrogen and renew its lattice oxygen at 700 ℃; simultaneously, deposited carbon is selectively oxidized to CO2 by steam following the reaction (C+2H2O→CO2+2H2).Slight deactivation in terms of amounts of desired products (syngas and hydrogen) is observed in ten repetitive two-step SRM process due to the carbon deposition on CeO2 surface as well as sintering of CeO2.

  17. Synthesis of Ba-doped CeO{sub 2} nanowires and their application as humidity sensors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zuwei [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Hu Chenguo [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Xiong Yufeng [National Center for Nanoscience and Technology, Beijing 100080 (China); Yang Rusen [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Wang Zhonglin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2007-11-21

    Ba-doped CeO{sub 2} nanowires were obtained from CeO{sub 2} particles through a facile composite-hydroxide-mediated (CHM) route. The products were characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscope (HRTEM). The formation process of the product was discussed. Humidity sensors based on the source material CeO{sub 2} particles, Ba-doped CeO{sub 2} nanowires grown for 12 and 72 h, were fabricated. The responses to humidity for static and dynamic testing proved that both doping Ba into CeO{sub 2} and converting morphology into a nanowire can improve the humidity sensitivity. The resistance changes from 465 to 3.9 M{omega} as the relative humidity (RH) increases from 25% to 88%, indicating promising applications of Ba-doped CeO{sub 2} nanowires in environmental monitoring.

  18. Phase Stability of Ce-Modified La2Zr2O7 Coatings and Chemical Compatibility with YSZ

    Science.gov (United States)

    Wu, Qiong; Ji, Xiaojuan; Peng, Haoran; Ren, Xianjing; Yu, Yueguang

    2016-04-01

    Ce-modified La2Zr2O7 powders, i.e., La2Zr2O7 (LZ), La2(Zr0.7Ce0.3)2O7 (LZ7C3), and La2(Zr0.3Ce0.7)2O7 (LZ3C7), were used to produce thermal barrier coatings by atmospheric plasma spray process. The chemical compatibility of the CeO2-doped La2Zr2O7 with the traditional YSZ was investigated in LZ-YSZ powder mixtures and LZ-YSZ bilayer coatings by x-ray diffraction and scanning electron microscope. The powder mixtures and coatings were aged at 1200 and 1300 °C for 100 h. The results showed that LZ and LZ7C3 presented single pyrochlore structure after the heat treatments at both 1200 and 1300 °C. For LZ3C7, however, fluorite structure was observed at 1300 °C, indicating a poor phase stability of LZ3C7 at the elevated temperature. The results further showed that La2(Zr0.3Ce0.7)2O7 reacted with YSZ in the bilayer ceramic coatings due to the diffusion of cerium, zirconium, and yttrium. While for La2Zr2O7(LZ) and La2(Zr0.7Ce0.3)2O7, a better chemical compatibility with YSZ was shown.

  19. Effects of TM on stability of structure corresponding to prepeak of amorphous Al90TM5Ce5 Alloys

    Institute of Scientific and Technical Information of China (English)

    赵芳; 吴佑实

    2002-01-01

    X-ray diffraction and DSC were used to investigate the crystallization process of amorphous Al90Fe5Ce5 and Al90Ni5Ce5 alloys, and the stability of the structure corresponding to the prepeak. Both these amorphous alloys are crystallized by two stages. The stability of the structure corresponding to the prepeak has a large difference. The structure corresponding to the prepeak for amorphous Al90Fe5Ce5 alloy is more stable than the amorphous matrix. However, it is not stable for amorphous Al90Ni5Ce5 alloys during the first crystallization stage. The prepeak position of amorphous Al90Ni5Ce5 alloys is very close to that of amorphous Al90Fe5Ce5 alloys. It is estimated that the prepeak is also due to diffraction peak broadening caused by very fine quasi-crystalline structure and the structural unit is an icosahedral quasi-crystalline structure with Ni as the central atom. The large difference of the stability of the structure corresponding to the prepeak is likely caused by different stability of the quasi-crystalline structure.

  20. Effect of Ce/La microalloying on microstructural evolution of Mg-Zn-Ca alloy during solution treatment

    Institute of Scientific and Technical Information of China (English)

    张庆鑫; 佟立波; 程丽任; 江中浩; 孟健; 张洪杰

    2015-01-01

    The effect of Ce/La misch metal addition on the microstructural evolution of as-cast and as-soluted Mg-5.3Zn-0.5Ca (wt.%) alloys was systematically investigated. It was found that Ce/La could effectively refine the as-cast alloy and restrain grain growth during solution treatment, which was derived from the constitutional supercooling during solidification process and the formation of stable intermetallic compounds CeMg12 and Mg17La2. Furthermore, Ce/La microalloying and solution treatment resulted in an evolu-tion from the original lamellar Ca2Mg6Zn3/α-Mg to the divorced eutectic structure. The thermal stability of Mg-Zn-Ca alloy could be effectively improved by Ce/La addition, because the low-melting-point binary Mg-Zn phase was transformed to MgxZny-Ca-(Ce/La) phase with higher thermal stability and the amount of Ca2Mg6Zn3/α-Mg eutectic structure was reduced.

  1. Ce-doped α-FeOOH nanorods as high-performance anode material for energy storage

    Science.gov (United States)

    Zhai, Yanjun; Xu, Liqiang; Qian, Yitai

    2016-09-01

    Ce-doped α-FeOOH nanorods with high yields were conveniently prepared by a hydrothermal method followed by an acid-treatment process. It is found that Ce uniformly distributes in the α-FeOOH nanorod nanostructures through elemental mapping analysis. The 0.5 wt% Ce-doped α-FeOOH electrode displayed excellent cycling performance with a high discharge capacity of 830 mA h g-1 after 800 charge/discharge cycles at a high current of 2000 mA g-1. The enhanced electrochemical performance can be attributed to the improved electronic conductivity, Li-ion diffusion kinetics and structure stability after Ce doping. Furthermore, a 0.5 wt% Ce-doped α-FeOOH//LiFePO4 lithium ion cell with an initial discharge capacity of 580 mA h g-1 at 1000 mA g-1 based on the total weight of the anode material has been fabricated for the first time. The obtained 0.5 wt% Ce-doped α-FeOOH electrode as anode material for sodium-ion batteries also exhibits a high initial discharge capacity of 587 mA h g-1 at 100 mA g-1.

  2. Solid state sintering of lime in presence of La2O3 and CeO2

    Indian Academy of Sciences (India)

    T K Bhattacharya; A Ghosh; H S Tripathi; S K Das

    2003-12-01

    The sintering of lime by double calcination process from natural limestone has been conducted with La2O3 and CeO2 additive up to 4 wt.% in the temperature range 1500–1650°C. The results show that the additives enhanced the densification and hydration resistance of sintered lime. Densification is achieved up to 98.5% of the theoretical value with La2O3 and CeO2 addition in lime. Grain growth is substantial when additives are incorporated in lime. The grain size of sintered CaO (1600°C) with 4 wt.% La2O3 addition is 82 m and that for CeO2 addition is 50 m. The grains of sintered CaO in presence of additive are angular with pores distributed throughout the matrix. EDX analysis shows that the solid solubility of La2O3 and CeO2 in CaO grain is 2.9 and 1.7 weight %, respectively. The cell dimension of CaO lattice is 4.803 Å. This value decreases with incorporation of La2O3 and CeO2. The better hydration resistance of La2O3 added sintered lime compared to that of CeO2 added one, is related to the bigger grain size of the lime in former case.

  3. Photocatalytic activity of the binary composite CeO2/SiO2 for degradation of dye

    Science.gov (United States)

    Phanichphant, Sukon; Nakaruk, Auppatham; Channei, Duangdao

    2016-11-01

    In this study, CeO2 photocatalyst was modified by composite with SiO2 to increase efficiency and improve photocatalytic activity. The as-prepared SiO2 particles have been incorporated into the precursor mixture of CeO2 by homogeneous precipitation and subsequent calcination process. The phase compositions of CeO2 before and after compositing with SiO2 were identified by X-ray diffraction (XRD). The morphology and particle size of CeO2/SiO2 composite was analyzed by high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). The results showed SiO2 spheres with the particle size approximately 100-120 nm, and a uniform layer of CeO2 nanoparticles with a diameter of about 5-7 nm that were fully composite to the surfaces of SiO2. The X-ray photoelectron spectroscopy (XPS) technique was carried out in order to characterize the change in valence state and composite characteristic by shifted peaks of binding energies. The photocatalytic activity was studied through the degradation of Rhodamine B in aqueous solution under visible light exposure. The highest photocatalytic efficiency of CeO2/SiO2 composite was also obtained. To explain the high photocatalytic efficiency of CeO2/SiO2 composite, the proposed mechanism involves the high surface properties of the CeO2/SiO2 composite, as measured by Brunauer-Emmett-Teller (BET) method.

  4. Dependence of the Ce(iii)/Ce(iv) ratio on intracellular localization in ceria nanoparticles internalized by human cells

    KAUST Repository

    Ferraro, Daniela

    2017-01-09

    CeO2 nanoparticles (CNPs) have been investigated as promising antioxidant agents with significant activity in the therapy of diseases involving free radicals or oxidative stress. However, the exact mechanism responsible for CNP activity has not been completely elucidated. In particular, in situ evidence of modification of the oxidative state of CNPs in human cells and their evolution during cell internalization and subsequent intracellular distribution has never been presented. In this study we investigated modification of the Ce(iii)/Ce(iv) ratio following internalization in human cells by X-ray absorption near edge spectroscopy (XANES). From this analysis on cell pellets, we observed that CNPs incubated for 24 h showed a significant increase in Ce(iii). By coupling on individual cells synchrotron micro-X-ray fluorescence (μXRF) with micro-XANES (μXANES) we demonstrated that the Ce(iii)/Ce(iv) ratio is also dependent on CNP intracellular localization. The regions with the highest CNP concentrations, suggested to be endolysosomes by transmission electron microscopy, were characterized by Ce atoms in the Ce(iv) oxidation state, while a higher Ce(iii) content was observed in regions surrounding these areas. These observations suggest that the interaction of CNPs with cells involves a complex mechanism in which different cellular areas play different roles.

  5. Study on advanced Ce0.9La0.1O2/Gd2Zr2O7 buffer layers architecture towards all chemical solution processed coated conductors

    DEFF Research Database (Denmark)

    Yue, Zhao; Ma, L.; Wu, W.

    2015-01-01

    Chemical solution deposition is a versatile technique to deposit functional oxide films with low cost. In this study, this approach was employed to grow multi-layered, second-generation, high-temperature superconductors ("coated conductors") with high superconducting properties. The Ce0.9La0.1O2/...

  6. High-performance ZnCo₂O₄@CeO2₂₄ core@shell microspheres for catalytic CO oxidation.

    Science.gov (United States)

    Wang, Fan; Wang, Xiao; Liu, Dapeng; Zhen, Jiangman; Li, Junqi; Wang, Yinghui; Zhang, Hongjie

    2014-12-24

    In this paper, we report a self-assembly method to synthesize high-quality ZnCo2O4@CeO2 core@shell microspheres with tunable CeO2 thickness. ZnCo2O4 spheres were first synthesized as the core, followed by a controlled CeO2 shell coating process. The thickness of CeO2 shell could be easily tuned by varying the feeding molar ratio of Ce/Co. Transmission electron microscope (TEM) images and scanning transmission electron microscope (STEM) image have identified the core@shell structure of these samples. In CO oxidation tests these ZnCo2O4@CeO2 core@shell microspheres exhibited promising catalytic performance, and the catalytic activity of the best sample is even close to the traditional noble metal-CeO2 system, attaining 100% CO conversion at a relatively low temperature of 200 °C. Cycling tests confirm their good stability of these core@shell microspheres besides activity. Their high catalytic performance should be attributed to the core@shell structure formation, and moreover further H2-temperature-programmed reduction (TPR) results revealed the possible synergistic effects between the two components of ZnCo2O4 and CeO2.

  7. Effect of Ce+ Ion Implantation upon Oxidation Resistance of Superalloy K38G

    Institute of Scientific and Technical Information of China (English)

    Qian Yuhai; Li Meishuan; Duo Shuwang; Zhao Youming

    2005-01-01

    The oxidation behavior (isothermal and cyclic oxidation) of cast superalloy K38G and the effect of Ce+ ion implantation with dose of 1×1017 ions/cm2 upon its oxidation resistance at 900 and 1000 ℃ in air were investigated. Meanwhile, the influence of Ce+ implantation on oxidation behavior of K38G with pre-oxide scale at 1000 ℃ in air was compared. The pre-oxidation was performed at 1000 ℃ in static air for 0.25 and 1.5 h, respectively. It is shown that the homogeneous external mixture oxide of rutile TiO2+Cr2O3 and non-continuous internal oxide of Al2O3 are formed during the oxidation procedure in all the cases. The isothermal oxidation resistance and the cracking or spallation resistance of superalloy K38G implanted with Ce+ by both of the two different implantation ways are not improved notably. This may be attributed to the mixed oxide composition characteristics and the blocking effect differences of Ce+ segregation along the oxide grain boundaries on the transport process for different diffusing ions.

  8. Fundamentals and Catalytic Applications of CeO2-Based Materials.

    Science.gov (United States)

    Montini, Tiziano; Melchionna, Michele; Monai, Matteo; Fornasiero, Paolo

    2016-05-25

    Cerium dioxide (CeO2, ceria) is becoming an ubiquitous constituent in catalytic systems for a variety of applications. 2016 sees the 40(th) anniversary since ceria was first employed by Ford Motor Company as an oxygen storage component in car converters, to become in the years since its inception an irreplaceable component in three-way catalysts (TWCs). Apart from this well-established use, ceria is looming as a catalyst component for a wide range of catalytic applications. For some of these, such as fuel cells, CeO2-based materials have almost reached the market stage, while for some other catalytic reactions, such as reforming processes, photocatalysis, water-gas shift reaction, thermochemical water splitting, and organic reactions, ceria is emerging as a unique material, holding great promise for future market breakthroughs. While much knowledge about the fundamental characteristics of CeO2-based materials has already been acquired, new characterization techniques and powerful theoretical methods are deepening our understanding of these materials, helping us to predict their behavior and application potential. This review has a wide view on all those aspects related to ceria which promise to produce an important impact on our life, encompassing fundamental knowledge of CeO2 and its properties, characterization toolbox, emerging features, theoretical studies, and all the catalytic applications, organized by their degree of establishment on the market.

  9. Flower-Like Mn-Doped CeO2 Microstructures: Synthesis, Characterizations, and Catalytic Properties

    Directory of Open Access Journals (Sweden)

    Ling Liu

    2015-01-01

    Full Text Available Mn-doped CeO2 flower-like microstructures have been synthesized by a facile method, involving the precipitation of metallic alkoxide precursor in a polyol process from the reaction of CeCl3·7H2O with ethylene glycol in the presence of urea followed by calcination. By introducing manganese ions, the composition can be freely manipulated. To investigate whether there was a hybrid synergic effect in CH4 combustion reaction, further detailed characteristics of Mn-doped CeO2 with various manganese contents were revealed by XRD, Raman, FT-IR, SEM, EDS, XPS, OSC, H2-TPR, and N2 adsorption-desorption measurements. The doping manganese is demonstrated to increase the storage of oxygen vacancy for CH4 and enhance the redox capability, which can efficiently convert CH4 to CO2 and H2O under oxygen-rich condition. The excellent catalytic performance of MCO-3 sample, which was obtained with the starting Mn/Ce ratios of 0.2 in the initial reactant compositions, is associated with the larger surface area and richer surface active oxygen species.

  10. Scintillation in LiBaF3(Ce) crystals

    NARCIS (Netherlands)

    Gektin, A; Shiran, N; Voloshinovski, A; Voronova, [No Value; Zimmerer, G

    1998-01-01

    Core-valence, self-trapped exciton and Ce3+-luminescences in pure and doped LiBaF3 crystals were determined on the basis of analysis of the time resolved emission and excitation spectra. It is shown that excitation of Ce-luminescence is caused both by carriers capture at or near activator ions and b

  11. Neutron detection using conversion layers and YAP:Ce and YAG:Ce crystals

    Directory of Open Access Journals (Sweden)

    Fiserova Lucie

    2015-01-01

    Full Text Available The work deals with the detection of thermal neutrons using a conversion layer of LiF on YAP:Ce and YAG:Ce scintillation crystals of various sizes. Enriched LiF (95 at. % 6Li in the form of a mixture with 5 % polyvinyl alcohol was deposited on the crystal face by spraying it in a thin layer. The 252Cf isotope with paraffin moderation and lead shielding was used as a neutron source. The detection is based on the nuclear reaction of 6Li with the neutron. The conversion leads to emitting an alpha particle and triton according to the scheme 6Li (n, a3H + + 4.5 MeV which are detected by the scintillation crystal. Due to gamma ray interaction, the optimum thickness of the crystal was estimated to 70 µm.

  12. Epitaxial Ce and the magnetism of single-crystal Ce/Nd superlattices

    OpenAIRE

    Clegg, P. S.; Goff, J.P.; McIntyre, G. J.; Ward, R.C.C.; Wells, M. R .

    2003-01-01

    The chemical structure of epitaxial gamma cerium and the chemical and magnetic structures of cerium/neodymium superlattices have been studied using x-ray and neutron diffraction techniques. The samples were grown using molecular-beam epitaxy, optimized to yield the desired Ce allotropes. The x-ray measurements show that, in the superlattices, both constituents adopt the dhcp structure and that the stacking sequence remains intact down to Tsimilar to2 K; these are the first measurements of mag...

  13. CE APPROVAL IN ELECTRICAL HOUSEHOLD APPLIANCES AND A CASE STUDY

    Directory of Open Access Journals (Sweden)

    Nazmi EKREN

    2009-01-01

    Full Text Available Due to the reason for rapidly developing technology, increasing competition medium, and awareness of the consumers, nowadays, the exigency of production with good quality has gained more and more significance. Certification of the quality and safety of the products to the consumers is compulsory in terms of producers. There are some documents to certify safety of the products. One of them is CE certificate. In this paper, basic information about CE mark is given and CE standards and tests required for electrical household appliances are mentioned. As an application, one of an electrical household appliance, toaster grill is treated and examined. To obtain CE certificate for toaster grill, required tests are made according to EN60335-2-9 and CE certificate is obtained.

  14. First-Principles Phase Diagram for Ce-Th System

    Energy Technology Data Exchange (ETDEWEB)

    Landa, A; Soderlind, P; Ruban, A; Vitos, L; Pourovskii, L

    2004-05-11

    Ab initio total energy calculations based on the exact muffin-tin orbitals (EMTO) theory are used to determine the high pressure and low temperature phase diagram of Ce and Th metals as well as the Ce{sub 43}Th{sub 57} disordered alloy. The compositional disorder for the alloy is treated in the framework of the coherent potential approximation (CPA). Equation of state for Ce, Th and Ce{sub 43}Th{sub 57} has been calculated up to 1 Mbar in good comparison with experimental data: upon compression the Ce-Th system undergoes crystallographic phase transformation from an fcc to a bct structure and the transition pressure increases with Th content in the alloy.

  15. Seamless Ligation Cloning Extract (SLiCE) cloning method.

    Science.gov (United States)

    Zhang, Yongwei; Werling, Uwe; Edelmann, Winfried

    2014-01-01

    SLiCE (Seamless Ligation Cloning Extract) is a novel cloning method that utilizes easy to generate bacterial cell extracts to assemble multiple DNA fragments into recombinant DNA molecules in a single in vitro recombination reaction. SLiCE overcomes the sequence limitations of traditional cloning methods, facilitates seamless cloning by recombining short end homologies (15-52 bp) with or without flanking heterologous sequences and provides an effective strategy for directional subcloning of DNA fragments from bacterial artificial chromosomes or other sources. SLiCE is highly cost-effective and demonstrates the versatility as a number of standard laboratory bacterial strains can serve as sources for SLiCE extract. We established a DH10B-derived E. coli strain expressing an optimized λ prophage Red recombination system, termed PPY, which facilitates SLiCE with very high efficiencies.

  16. Ce3+-ion-induced visible-light photocatalytic degradation and electrochemical activity of ZnO/CeO2 nanocomposite

    OpenAIRE

    2016-01-01

    In this study, pure ZnO, CeO2 and ZnO/CeO2 nanocomposites were synthesized using a thermal decomposition method and subsequently characterized using different standard techniques. High-resolution X-ray photoelectron spectroscopy measurements confirmed the oxidation states and presence of Zn2+, Ce4+, Ce3+ and different bonded oxygen species in the nanocomposites. The prepared pure ZnO and CeO2 as well as the ZnO/CeO2 nanocomposites with various proportions of ZnO and CeO2 were tested for photo...

  17. Ce4+/Ce3+-V2+/V3+氧化还原流动电池的可行性研究(Ⅱ)--旋转圆盘(RDE)与旋转环盘(RRDE)法对Ce4+/Ce3+氧化还原体系的研究%Studies on Feasibility of Ce4+/Ce3+ - V2+/V3+ Redox Flow Cell ( Ⅱ ) --Investigation of Ce4 +/Ce3 + Redox System by RDE and RRDE

    Institute of Scientific and Technical Information of China (English)

    夏熙; 刘洋; 刘洪涛

    2001-01-01

    用RDE与REDE法研究了Ce4+/Ce3+-V2+/V3+氧化还原流动电池中Ce4+/Ce3+体系的电化学动力学参数,以说明组成该新型氧化还原流动电池的可能性.用RDE法得出在铂电极表面与玻碳电极上均会生成一层氧化膜,对Ce3+的氧化反应产生阻碍作用.但在铂上的氧化膜对Ce4+的还原反应却有催化作用.用Rrde法得出Ce3+在玻碳电极上的氧化与析氧之间存在着竞争,为得到较高的Ce3+氧化效率,应控制氧化电流在2~8 mA@cm-2之间.

  18. The mixed-valence state of Ce in the hexagonal CeNi sub 4 B compound

    CERN Document Server

    Tolinski, T; Pugaczowa-Michalska, M; Chelkowska, G

    2003-01-01

    Measurements of the magnetic susceptibility chi, x-ray photoemission spectra (XPS), electrical resistivity rho and electronic structure calculations for CeNi sub 4 B are reported. In the paramagnetic region, CeNi sub 4 B follows the Curie-Weiss law with mu sub e sub f sub f = 0.52 mu sub B /fu and theta -10.7 K. The effective magnetic moment is lower than the free Ce sup 3 sup + -ion value. The Ce(3d) XPS spectra have confirmed the mixed-valence state of Ce ions in CeNi sub 4 B. The f occupancy, n sub f , and the coupling DELTA between the f level and the conduction states were derived to be about 0.83 and 85 meV, respectively. Both susceptibility data and XPS spectra show that Ce ions in CeNi sub 4 B are in the intermediate-valence state. At low temperatures (below 12 K), the magnetic contribution to the electrical resistivity reveals a logarithmic slope characteristic of Kondo-like systems.

  19. Synthesis and Luminescent Properties of Superfine Sr2 CeO4 Phosphors by Sol-Gel Auto-Combustion Method

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Citric acid complexing sol-gel auto-combustion method was explored to synthesize superfine Sr2CeO4 phosphors using the inorganic salts Sr(NO3)2 and Ce(NO3)3 as raw materials together with citric acid (CA) as a chelating agent. TGDTA, XRD, SEM and photoluminescence spectra were used to investigate the formation process, microstructure and luminescent properties of the synthesized Sr2CeO4. The results show that the crystallization of Sr2CeO4 begins at about 800 ℃and completes around 900 ℃ with an orthorhombic structure. When the calcination temperature is above 1000 ℃,Sr2CeO4 partly decomposes into SrCeO3. SEM studies show that the particles of Sr2CeO4 obtained at 900 ℃ are sphericallike shape and superfine with diameter below 100 nm. The excitation spectrum of the superfine Sr2CeO4 phosphors displays a broad band with two peaks around 290 and 350 nm respectively. The former peak is stronger than the latter one. This broad band is due to the charge transfer (CT) band of the Ce4+ ion. Excited by a radiation of 290 nm, the superfine phosphors emit a strong blue-white fluorescence, and the emission spectrum shows a broad band with a peak around 470 nm,which can be assigned to the f→t1g transition of Ce4 + . It is found that the emission intensity is affected by the calcination temperature.

  20. Template-directed synthesis and characterization of microstructured ceramic Ce/ZrO2@SiO2 composite tubes

    Directory of Open Access Journals (Sweden)

    Jörg J. Schneider

    2014-07-01

    Full Text Available An exo-templating synthesis process using polymeric fibers and inorganic sol particles deposited onto structured one-dimensional objects is presented. In particular, CeO2/ZrO2@SiO2 composite tubes were synthesized in a two-step procedure by using electrospun polystyrene fibers as fiber template. First, a sol–gel approach based on an exo-templating technique was employed to obtain polystyrene(PS/SiO2 composite fibers. These composite fibers were subsequently covered by spray-coating with ceria and zirconia sol solutions. After drying and final calcination of the green body composites, the PS polymer template was removed, and composite tubes of the composition CeO2/ZrO2@SiO2 were obtained. The SiO2/ZrO2/CeO2 microtubes, which consist of interconnected silica particles, are held together by ceria and zirconia deposits formed during the thermal treatment process. These microtubes are mainly located in the pendentive connecting the individual spherical silica particles and glue them together. The composition and crystallinity of this material connecting the individual silica particles contains the elements Ce and Zr and O as mixed oxide solid solution identified by XRD, Raman and high-resolution TEM and EFTEM. High-resolution microscopy techniques allowed for an elemental mapping on the surface of the silica host structure and determination of the O, Zr and Ce elemental distribution with nm precision.

  1. Influence of Ce-precursor and fuel on structure and catalytic activity of combustion synthesized Ni/CeO{sub 2} catalysts for biogas oxidative steam reforming

    Energy Technology Data Exchange (ETDEWEB)

    Vita, Antonio, E-mail: antonio.vita@itae.cnr.it; Italiano, Cristina; Fabiano, Concetto; Laganà, Massimo; Pino, Lidia

    2015-08-01

    A series of nanosized Ni/CeO{sub 2} catalysts were prepared by Solution Combustion Synthesis (SCS) varying the fuel (oxalyldihydrazide, urea, carbohydrazide and glycerol), the cerium precursor (cerium nitrate and cerium ammonium nitrate) and the nickel loading (ranging between 3.1 and 15.6 wt%). The obtained powders were characterized by X-ray Diffraction (XRD), N{sub 2}-physisorption, CO-chemisorption, Temperature Programmed Reduction (H{sub 2}-TPR) and Scanning Electron Microscopy (SEM). The catalytic activity towards the Oxy Steam Reforming (OSR) of biogas was assessed. The selected operating variables have a strong influence on the nature of combustion and, in turn, on the morphological and structural properties of the synthesized catalysts. Particularly, the use of urea allows to improve nickel dispersion, surface area, particle size and reducibility of the catalysts, affecting positively the biogas OSR performances. - Highlights: • Synthesis of Ni/CeO{sub 2} nanopowders by quick and easy solution combustion synthesis. • The fuel and precursor drive the structural and morphological properties of the catalysts. • The use of urea as fuel allows to improve nickel dispersion, surface area and particle size. • Ni/CeO{sub 2} (7.8 wt% of Ni loading) powders synthesized by urea route exhibits high performances for the biogas OSR process.

  2. Exploring C-E Translation Process of Difficult Sentences From"Four-Step Analysis"Perspective—Based on Theories of"Three Types of Translation"and"Back Transformation"%汉语难句英译过程"四步骤分析法"探究——基于雅各布逊"翻译三分法"和奈达"逆转换论"

    Institute of Scientific and Technical Information of China (English)

    李会敏

    2015-01-01

    Based on theories of"Three Types of Translation"by Roman Jacobson and"Back Transformation"by Eugene Nida, C-E translation process of difficult sentences common in college English teaching has been explored in the hope of revealing the invis-ible translating process existing between"understanding"and"expressing", a Two-step translating model long advocated by many translators. A simple yet practical translating process, the"Four-step Analysis"is introduced to facilitate non-English ma-jors in effectively grasping the thinking and transferring process of Chinese difficult sentences translation.%针对大学英语教学中的汉语难句英译过程,基于雅各布逊"翻译三分法"和奈达"逆转换论",试图挖掘并揭示存在于传统的"理解+表达"翻译两步骤之间的不可见的专门围绕汉语难句英译的翻译思维转换过程,从而为公英学生学习掌握汉语难句英译思路提供一个简单可见易操作的模式,即"四步骤分析法".

  3. Mn-CeOx/Ti-PILC的制备、表征及脱硝性能研究%Study on preparation, characterization and de-NO activity of Mn-CeOx/Ti-PILC

    Institute of Scientific and Technical Information of China (English)

    沈伯雄; 马宏卿; 杨晓燕; 姚燕

    2012-01-01

    Titania-pillared clay (Ti-PILC) was prepared from butyltitanate, then Mn-CeOx/Ti-PILC was prepared by impregnating method on the Ti-PILC. The catalysts were characterized by BET, FT-IR, XRD, XPS and NH3-TPD. The results showed that, the pillaring process was efficient. Active components exist in Mn2O3 and CeO2 in catalyst Mn-CeOx/Ti-PILC which was a porous mesopore material with high BET surface area (133.7 m2/g), the activity test also indicted that this catalyst had good de-NOx activity, the removal efficiency could reach 83.1% even at 180 ℃.%采用钛酸丁酯溶胶法制备了钛基柱撑黏土(Ti-PILC),通过浸渍法制备Mn-CeOx/Ti-PILC,运用BET、FT-IR、XRD、NH3-TPD、XPS等技术对催化剂进行表征分析.结果说明,经过钛交联柱撑制备的Mn-CeOx/Ti-PILC是一种具备较大比表面积(133.7 m2/g)的多孔性介孔材料;活性成分主要为CeO2以及Mn2O3.Mn-CeOx/Ti-PILC低温下具有较好的选择性能催化剂还原(SCR)脱硝活性,180℃下,脱硝活性达到83.1%.

  4. Nanofibers of CeO{sub 2} via an electrospinning technique

    Energy Technology Data Exchange (ETDEWEB)

    Yang Xinghua [Center for Advanced Optoelectronic Functional Materials Research, Northeast Normal University, Changchun 130024 (China); Shao Changlu [Center for Advanced Optoelectronic Functional Materials Research, Northeast Normal University, Changchun 130024 (China)]. E-mail: changlushao@yahoo.com.cn; Liu Yichun [Center for Advanced Optoelectronic Functional Materials Research, Northeast Normal University, Changchun 130024 (China); Mu Rixiang [Nanoscale Materials and Sensors, Department of Physics, Fisk University, Nashville, TN (United States); Guan Hongyu [Center for Advanced Optoelectronic Functional Materials Research, Northeast Normal University, Changchun 130024 (China)

    2005-05-01

    Thin polyvinyl alcohol/cerium nitrate composite fibers were prepared by using sol-gel processing and electrospinning technique. After calcinations of the above precursor fibers, CeO{sub 2} nanofibers with a diameter of 50-150 nm were successfully obtained. The fibers were characterized by Raman spectroscopy, thermogravimetric analysis, differential thermal analysis, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy.

  5. Ce4+/Ce3+缓冲溶液流动注射电势检测法测定维生素C%Determining Vitamin C with Flow Injection Potentiometry in Ce4+/Ce3+ Redox Buffer

    Institute of Scientific and Technical Information of China (English)

    孔祥伟

    2003-01-01

    Ce4+/Ce3+氧化还原体系作缓冲溶液,用流动注射电势检测法测定了维生素C,将样品注射于以0.1mol/L K2SO4作支持电解质的Ce4+/Ce3+缓冲溶液试剂流, 以流通型氧化还原电势检测电极检测维生素C与Ce4+反应引起的氧化还原电对的电势变化,对3.0×10-4mol/L Ce4+/3.0×10-4mol/L Ce3+缓冲溶液,测定维生素C的线性范围为1.0×10-4~6.0×10-4mol/L,检出限为1.3×10-5mol/L,相对标准偏差为0.36%(n=4),分析频率为120次/小时.

  6. Low-temperature NMR studies of Ce-Al compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gavilano, J.L. (Laboratorium fuer Festkoerperphysik, ETH-Hoenggerberg, CH-8093 Zuerich (Switzerland)); Hunziker, J. (Laboratorium fuer Festkoerperphysik, ETH-Hoenggerberg, CH-8093 Zuerich (Switzerland)); Vonlanthen, P. (Laboratorium fuer Festkoerperphysik, ETH-Hoenggerberg, CH-8093 Zuerich (Switzerland)); Ott, H.R. (Laboratorium fuer Festkoerperphysik, ETH-Hoenggerberg, CH-8093 Zuerich (Switzerland))

    1994-04-01

    Ce-Al compounds display a variety of unconventional magnetic properties at low temperatures. This is particularly well demonstrated by the results of our low-frequency NMR studies on CeAl[sub 2], CeAl[sub 3] and Ce[sub 3]Al[sub 11]. Although CeAl[sub 2] orders antiferromagnetically below 3.4 K, the temperature dependence of the spin-lattice relaxation rate follows a Korringa law below 1 K. For CeAl[sub 3], we observe an increase of the line width below 0.9 K, but no indication of a phase transition is discernible from the temperature dependence of the spin-lattice relaxation rate. Ce[sub 3]Al[sub 11] is ferromagnetic below 6.2 K, but develops an antiferromagnetic and modulated structure below 3.3 K. A field of the order of 3 kG, however, appears to stabilize the ferromagnetic phase. Our spectroscopic data are important in view of some of the unusual thermal properties of these materials. ((orig.))

  7. On the luminescence properties of CaSO4:Ce.

    Science.gov (United States)

    Lapraz, D; Prevost, H; Iacconi, P; Guigues, C; Benabdesselam, M; Briand, D

    2002-01-01

    The luminescent properties of cerium doped calcium sulphate are studied: fluorescence and excitation spectra, optical absorption and thermoluminescence (TSL). It is known that, in rare earth doped CaSO4, only cerium induces a strong 400 degrees C TSL peak. In CaSO4:0.2%Ce samples synthesised under oxidising conditions, the recovery step of Ce3+ fluorescence is correlated with the 400 degrees C TSL peak readout, as mentioned by Nair er al. Our results indicate that an oxidation of Ce3+ ion does occur under X-irradiation (Ce3+ --> Ce4+), followed by a complete return to the trivalent state after thermal annealing at about 500 degrees C; our results confirm the hypothesis of Nair et al that Ce3+ ions are oxidised by ionising irradiation. So, a pure redox reaction seems the most probable for the 400 degrees C TSL peak of CaSO4:Ce. Moreover, the use of the 400 degrees C TSL peak for high temperature dosimetry applications is discussed.

  8. Study of structural and transport properties of nanostructured CeO{sub 2}, Ce{sub 1-x}Ru{sub x}O{sub 2} and Ce{sub 1-x}In{sub x}O{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Rangel, R.; Chavez-Chavez, L. [Division de Estudios de Posgrado, Facultad de Ingenieria Quimica, Universidad Michoacana de S.N.H. (Mexico); Martinez, E. [Centro de Investigacion en Materiales Avanzados, S.C. (CIMAV), Nuevo Leon (Mexico); Bartolo-Perez, P. [Departamento de Fisica Aplicada, CINVESTAV-IPN, Merida, Yucatan (Mexico)

    2012-06-15

    The present work reports for the first time thin films prepared from Ce{sub 1-x}M{sub x}O{sub 2-{delta}} (M = Ru, In) solid solutions for application as gas sensors. The CeO{sub 2}, Ce{sub 0.95}Ru{sub 0.05}O{sub 2} and Ce{sub 0.95}In{sub 0.05}O{sub 2} thin films were prepared by means of the RF sputtering process onto Si (111) substrates. The deposition conditions were carried out at 500 C varying the deposition time. Targets were prepared via sol-gel process starting from C{sub 6}H{sub 9}O{sub 6}In, Ru{sub 3}(CO){sub 12} and Ce(C{sub 2}H{sub 3}O{sub 2}){sub 3} . 1.5H{sub 2}O compounds and using a ceramic method to consolidate them. The samples were characterized by means of XRD, SEM, and AFM. Their thickness was measured using a profilometer. The results herein obtained regarding the microstructure and transport properties indicate that these materials can be used as gas sensors. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Biological reduction-deposition and luminescent properties of nanostructured CePO{sub 4}@NaCe(SO{sub 4}){sub 2}(H{sub 2}O) and CePO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xiaoniu [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China); Research Institute of Green Construction Materials, Southeast University, Nanjing 211189 (China); Qian, Chunxiang, E-mail: cxqian@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China); Research Institute of Green Construction Materials, Southeast University, Nanjing 211189 (China)

    2016-03-01

    Nano-sized CePO{sub 4}@NaCe(SO{sub 4}){sub 2}(H{sub 2}O) and CePO{sub 4} with hexagonal phase have been prepared by simply varying the reactant P/Ce molar ratio in bacterial liquid. The phase composition of two samples was checked via Fourier transform infrared spectroscopy (FTIR), energy dispersive analysis of X-rays (EDS) and X-ray diffraction (XRD) analyses, displaying the presence of CePO{sub 4}@NaCe(SO{sub 4}){sub 2}(H{sub 2}O) and CePO{sub 4} with average crystallite size are 32.34 and 15.61 nm, respectively. The scanning electron microscopy (SEM) images show that nano-clusters and sphere-like in shape with a narrow diameter distribution were observed in two samples. The transmission electron microscopy (TEM) photographs further indicate obtained CePO{sub 4}@NaCe(SO{sub 4}){sub 2}(H{sub 2}O) and CePO{sub 4} nanoparticles correspond to nanosheets and nanorods, respectively. The emission spectra of CePO{sub 4}@NaCe(SO{sub 4}){sub 2}(H{sub 2}O) and CePO{sub 4} display a broad band of 300–380 nm range with the strongest emission at 342 nm in the violet region. - Highlights: • A new method was found to synthesize CePO{sub 4}@NaCe(SO{sub 4}){sub 2}(H{sub 2}O) and CePO{sub 4} nanoparticles. • CePO{sub 4}@NaCe(SO{sub 4}){sub 2}(H{sub 2}O) nanoparticles have good luminescent properties. • Size and luminescent properties of two samples have been studied and compared.

  10. Unusual physical and chemical properties of Cu in Ce(1-x)Cu(x)O(2) oxides.

    Science.gov (United States)

    Wang, Xianqin; Rodriguez, José A; Hanson, Jonathan C; Gamarra, Daniel; Martínez-Arias, Arturo; Fernandez-García, Marcos

    2005-10-27

    The structural and electronic properties of Ce(1-x)Cu(x)O(2) nano systems prepared by a reverse microemulsion method were characterized with synchrotron-based X-ray diffraction, X-ray absorption spectroscopy, Raman spectroscopy, and density functional calculations. The Cu atoms embedded in ceria had an oxidation state higher than those of the cations in Cu(2)O or CuO. The lattice of the Ce(1)(-x)Cu(x)O(2) systems still adopted a fluorite-type structure, but it was highly distorted with multiple cation-oxygen distances with respect to the single cation-oxygen bond distance seen in pure ceria. The doping of CeO(2) with copper introduced a large strain into the oxide lattice and favored the formation of O vacancies, leading to a Ce(1-x)Cu(x)O(2-y) stoichiometry for our materials. Cu approached the planar geometry characteristic of Cu(II) oxides, but with a strongly perturbed local order. The chemical activities of the Ce(1-x)Cu(x)O(2) nanoparticles were tested using the reactions with H(2) and O(2) as probes. During the reduction in hydrogen, an induction time was observed and became shorter after raising the reaction temperature. The fraction of copper that could be reduced in the Ce(1-x)Cu(x)O(2) oxides also depended strongly on the reaction temperature. A comparison with data for the reduction of pure copper oxides indicated that the copper embedded in ceria was much more difficult to reduce. The reduction of the Ce(1-x)Cu(x)O(2) nanoparticles was rather reversible, without the generation of a significant amount of CuO or Cu(2)O phases during reoxidation. This reversible process demonstrates the unusual structural and chemical properties of the Cu-doped ceria materials.

  11. Faceting of (001) CeO{sub 2} Films: The Road to High Quality TFA-YBa{sub 2}Cu{sub 3}O{sub 7} Multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Coll, M [Institut de Ciencia de Materials de Barcelona, C.S.I.C., Campus U.A.Barcelona, 08193 Bellaterra (Spain); Gazquez, J [Institut de Ciencia de Materials de Barcelona, C.S.I.C., Campus U.A.Barcelona, 08193 Bellaterra (Spain); Sandiumenge, F [Institut de Ciencia de Materials de Barcelona, C.S.I.C., Campus U.A.Barcelona, 08193 Bellaterra (Spain); Pomar, A [Institut de Ciencia de Materials de Barcelona, C.S.I.C., Campus U.A.Barcelona, 08193 Bellaterra (Spain); Puig, T [Institut de Ciencia de Materials de Barcelona, C.S.I.C., Campus U.A.Barcelona, 08193 Bellaterra (Spain); Obradors, X [Institut de Ciencia de Materials de Barcelona, C.S.I.C., Campus U.A.Barcelona, 08193 Bellaterra (Spain); Espinos, J P [Instituto de Ciencia de Materiales de Sevilla, C.S.I.C., Avda. Americo Vespucio s/n Isla de la Cartuja, 41092 Sevilla (Spain); Gonzalez-Elipe, A R [Instituto de Ciencia de Materiales de Sevilla, C.S.I.C., Avda. Americo Vespucio s/n Isla de la Cartuja, 41092 Sevilla (Spain)

    2006-06-01

    CeO{sub 2} films are technologically important as a buffer layer for the integration of superconducting YBa{sub 2}Cu{sub 3}O{sub 7} films on biaxially textured Ni substrates. The growth of YBa{sub 2}Cu{sub 3}O{sub 7} layers on the CeO{sub 2} cap layers by the trifluoroacetate (TFA) route remains a critical issue. To improve the accommodation of YBa{sub 2}Cu{sub 3}O{sub 7} on CeO{sub 2}, surface conditioning or CeO{sub 2} is required. In this work we have applied ex-situ post-processes at different atmospheres to the CeO{sub 2} layers deposited on YSZ single crystals using rf sputtering. XPS analysis showed that post-annealing CeO{sub 2} layer in Ar/H{sub 2}/H{sub 2}O catalyses in an unexpected way the growth of (001)- terraces. We also report on the growth conditions of YBa{sub 2}Cu{sub 3}O{sub 7}-TFA on CeO{sub 2} buffered YSZ single crystal grown by chemical solution deposition and we compare them with those leading to optimized YBa{sub 2}Cu{sub 3}O{sub 7}-TFA films on LaAlO{sub 3} single crystals. Critical currents up to 1.6 MA/cm{sup 2} at 77 K have been demonstrated in 300 nm thick YBa{sub 2}Cu{sub 3}O{sub 7} layers on CeO{sub 2}/YSZ system. The optimized processing conditions have then been applied to grow YBa{sub 2}Cu{sub 3}O{sub 7}-TFA films on Ni substrates having vacuum deposited cap layers of CeO{sub 2}.

  12. Relativeca Dopplera efekto ^ce unuforme akcelata movo -- II

    CERN Document Server

    Paiva, F M

    2007-01-01

    Extending physics/0701092, a light source of monochromatic radiation, in rectilinear motion under constant proper acceleration, passes near an observer at rest. In the context of special relativity, we describe the observed Doppler effect. We describe also the interesting discontinuous effect when riding through occurs. An English version of this article is available. - - - - - - - - - - - \\\\ Da^urigante physics/0701092, luma fonto de unukolora radiado ^ce rekta movo ^ce konstanta propra akcelo pasas preter restanta observanto. ^Ce la special-relativeco, ni priskribas la observatan Doppleran efikon. Ni anka^u priskribas la interesan nekontinuan efikon se trapaso okazas.

  13. Degradering van Y₂SiO₅ :Ce fosforpoeie

    Directory of Open Access Journals (Sweden)

    Editorial Office

    2007-09-01

    Full Text Available Die degradering van die katodeluminessensie - (CL intensiteit van yttriumsilikaat gedoteer met serium (Y₂SiO₅:Ce is ondersoek vir moontlike toepassing in lae spanning veldemissie-vertooneenhede (FEDs.Y₂SiO₅:Ce is ’n blou luminesserende seldsameaarde-fosfor wat ondersoek word as ’n alternatief vir die tradisionele blou sinksulfied - (ZnS fosfor. X-straaldiffraksie (XRD, wat gedoen is vir karakterisering, het die ingewikkelde monokliene kristalstruktuur van Y₂SiO₅:Ce getoon.

  14. Mechanical properties of the A356 aluminum alloy modified with La/Ce

    Institute of Scientific and Technical Information of China (English)

    E. Aguirre-De la Torre; R. Pérez-Bustamante; J. Camarillo-Cisneros; C.D. Gómez-Esparza; H.M. Medrano-Prieto; R. Martínez-Sánchez

    2013-01-01

    The research of rare earths for the synthesis of materials with improved mechanical performance is of great interest when they are considered for potential applications in the automotive industry. In this regard, the effect on the mechanical properties and microstructure of the automotive A356 aluminum alloy reinforced with 0.2 (wt.%) Al-6Ce-3La (ACL) was investigated. The ACL was added to the melted A356 alloy in the as-received condition and processed by mechanical milling. In the second route, the effect of the ACL processed by mechanical milling and powder metallurgy techniques was investigated, and compared with the results ob-tained from the A356 alloy strengthened with ACL in the as-received condition. Microstructural properties were evaluated by means of X-ray diffraction in order to observe the solubility of Ce/La in the Al matrix. In addition, electron microscopy was employed in or-der to investigate the effect of milling time on the size and morphology of La/Ce phase under milling process. Mechanical properties of the A356 alloy modified with ACL were measured by hardness and tensile test. For comparison unmodified specimens of the A356 were characterized according to the previous procedure. The microstructural and mechanical characterization was carried out in specimens after solution and artificial aging. Observations in scanning electron microscopy indicated a homogeneous dispersion of La/Ce phases by using both routes;however, mechanical results, in the modified A356 alloy with the ACL in the as-received condi-tion, showed an improvement in the mechanical performance of the A356 alloy over that reinforced with the ACL mechanically milled.

  15. 特殊形貌的PANI/CeO2的电化学制备%ELECTROCHEMICAL PREPARATION OF PANI/CeO2 COMPOSITE WITH SPECIAL MORPHOLOGY

    Institute of Scientific and Technical Information of China (English)

    桑晓光; 曾繁武; 刘晓霞

    2012-01-01

    Composite materials consisting of conducting polymers and inorganic particles have attracted considerable attention as they combine the advantages of both components and have potential applications in many fields. Electrodeposition is an attractive method for the preparation of thin films since it offers the advantages of low processing temperature, normal handling pressure, high purity of deposition, and controlled thickness of the film. Polyaniline/CeO2 (PANI/CeO2) composite with "horn-like" morphology was prepared by potentiostatic electrodeposition method in 0.05 mol/L Ce(NO3)3 containing 0.05 mol/L CH3COOH and 0.025 mol/L aniline (An) at 1.1 V {vs SCE} (pH=5.5) The morphology and composition of the PANl/CeO2 composite were characterized by SEM and TEM. The results indicated that the PANI/CeO2 composite had "horn-like" morphology. Characteristic vibrations of PANI were observed on the Fourier transform infrared spectrum (FTIR) of PANl/CeO2 composite. The PANl/CeO2 composite displayed characteristic electrochemical behaviors of PANI in phosphate buffer (pH=6.9), based on cyclic voltammetric experiments. The influences of electrodeposition conditions on the morphology of the composite were investigated by changing the reaction time and the potentiostatic potential. The results showed that potential is the key factor for the formation of "horn-like"PANI/CeO2 composite. PANI/CeO2 composite obtained at 0.8 V existed in nanoparticles. No "horn-like" composite was observed at this lower potential, even after prolonged reaction time. More protons were released during the electrochemical polymerization of aniline and the electrochemical deposition of CeO2 at higher potential. One-dimensional growth of PANI was promoted due to the effect control of secondary growth of PANI at lower pH media, resulting in nanofibrous composite. More PANI and CeO2 were formed along with the electrodeposition and so more protons were released. Thus the nanofiber changed thinner and "horn

  16. Field Demonstration of a Membrane Process to Separate Nitrogen from Natural Gas

    Energy Technology Data Exchange (ETDEWEB)

    Kaaeid Lokhandwala

    2007-03-31

    The original proposal described the construction and operation of a 1 MMscfd treatment system to be operated at a Butcher Energy gas field in Ohio. The gas produced at this field contained 17% nitrogen. During pre-commissioning of the project, a series of well tests showed that the amount of gas in the field was significantly smaller than expected and that the nitrogen content of the wells was very high (25 to 30%). After evaluating the revised cost of the project, Butcher Energy decided that the plant would not be economical and withdrew from the project. Since that time, Membrane Technology and Research, Inc. (MTR) has signed a marketing and sales partnership with ABB Lummus Global, a large multinational corporation. MTR is working with the company's Randall Gas Technology group, a supplier of equipment and processing technology to the natural gas industry. Randall's engineering group found a new site for the project at a North Texas Exploration (NTE) gas processing plant, which met with limited success. However, a small test system was installed at a Twin Bottoms Energy well in Kentucky. This unit operated successfully for six months, and demonstrated the technology's reliability on a small scale. MTR then located an alternative test site with much larger gas flow rates and signed a contract with Towne Exploration in the third quarter of 2006, for a demonstration plant in Rio Vista, California, to be run through May 2007. The demonstration for Towne has already resulted in the sale of two commercial skids to the company; both units will be delivered by the end of 2007. Total sales of nitrogen/natural gas membrane separation units from the partnership with ABB are now approaching $4.0 million.

  17. HumanViCe: Host ceRNA network in virus infected cells in human

    Directory of Open Access Journals (Sweden)

    Suman eGhosal

    2014-07-01

    Full Text Available Host-virus interaction via host cellular components has been an important field of research in recent times. RNA interference mediated by short interfering RNAs and microRNAs (miRNA, is a widespread anti-viral defence strategy. Importantly, viruses also encode their own miRNAs. In recent times miRNAs were identified as key players in host-virus interaction. Furthermore, viruses were shown to exploit the host miRNA networks to suite their own need. The complex cross-talk between host and viral miRNAs and their cellular and viral targets forms the environment for viral pathogenesis. Apart from protein-coding mRNAs, non-coding RNAs may also be targeted by host or viral miRNAs in virus infected cells, and viruses can exploit the host miRNA mediated gene regulatory network via the competing endogenous RNA effect. A recent report showed that viral U-rich non-coding RNAs called HSUR, expressed in primate virus herpesvirus saimiri (HVS infected T cells, were able to bind to three host miRNAs, causing significant alteration in cellular level for one of the miRNAs. We have predicted protein coding and non protein-coding targets for viral and human miRNAs in virus infected cells. We identified viral miRNA targets within host non-coding RNA loci from AGO interacting regions in three different virus infected cells. Gene ontology (GO and pathway enrichment analysis of the genes comprising the ceRNA networks in the virus infected cells revealed enrichment of key cellular signalling pathways related to cell fate decisions and gene transcription, like Notch and Wnt signalling pathways, as well as pathways related to viral entry, replication and virulence. We identified a vast number of non-coding transcripts playing as potential ceRNAs to the immune response associated genes; e.g. APOBEC family genes, in some virus infected cells. All these information are compiled in HumanViCe, a comprehensive database that provides the potential ceRNA networks in virus

  18. Study of the nitric acid influence on the production of Ce O{sub 2} with high specific surface area; Estudo da influencia do acido nitrico na obtencao de CeO{sub 2} com alta area superficial especifica

    Energy Technology Data Exchange (ETDEWEB)

    Albanez, Nelma Kunrath; Bressiani, Jose Carlos [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    1996-12-31

    The cerium oxide (Ce O{sub 2}) main characteristics for use as catalyst in an exhaust gases purification system are: high specific surface area (approximately 30 m{sup 2}/g after calcination at 800 deg C/ 2 hs), and thermal stability. The Ce O{sub 2} powders obtained by conventional route, i.e., precipitation, and submitted high temperature (800 deg C) heat treatments, showed low specific surface area. In this work nitric acid effects on the Ce O{sub 2} surface area values were investigated. The variables studied were nitric acid concentration, humidity content in the raw material, re pulp after leaching, addition of hydrogen peroxide (H{sub 2} O{sub 2}) and starting material specific surface area. By this process, it was possible to obtain powders with specific surface area larger than 40 m{sup 2}/g, after treatment at 800 deg C during two hours. (author) 8 refs., 3 figs., 1 tab.

  19. Ag对Pd/CeO2催化剂上氧迁移的促进作用%Enhanced Migration of Oxygen on Ag-Modified Pd/CeO2 Catalyst

    Institute of Scientific and Technical Information of China (English)

    曲振平; 程谟杰; 石川; 黄伟新; 包信和

    2001-01-01

    @@Active migration and spillover of surface species on catalyst surface can be cri tical effects in catalytic processes. As a typical instance, the storage and rel ease of oxygen in the Pt-modified CeO2 catalysts were proposed to play a very important role in catalytic elimination of noxious pollutants[1]. It ha s been demonstrated that the active oxygen species transfer between Pt and CeO 2 under different conditions[2,3]. Numerous investigations on the proper ty of Pd in the catalysts have been carried out recently[4]. Compared wi th Pt, Pd has a strong interaction with CeO2 support. Silver is a unique eleme nt whose oxide can decompose thermally

  20. Nanoflake-assembled Al2O3-supported CeO2-ZrO2 as an efficient catalyst for oxidative dehydrogenation of ethylbenzene with CO2

    Science.gov (United States)

    Wang, Tehua; Guan, Xiaolin; Lu, Huiyi; Liu, Zhongwen; Ji, Min

    2017-03-01

    An Al2O3 material assembled by nanoflakes was used to prepare supported CeO2-ZrO2 catalyst via a deposition-precipitation method for oxidative dehydrogenation of ethylbenzene with CO2. Both unsupported and commercial Al2O3-supported CeO2-ZrO2 were prepared for comparison. It was found that the CeO2-ZrO2/nanoflake-assembled Al2O3 catalyst exhibited the best catalytic activity. The characterization results revealed that the slit-shape pores existing in nanoflake-assembled Al2O3 were responsible for the small particle size and high Ce/Zr surface ratio of supported CeO2-ZrO2 species. The dispersion of Ce1-xZrx(OH)4 precursors onto Al2O3 support surface during the deposition-precipitation process was proposed. The high dispersion and large numbers of surface oxygen vacancies of the CeO2-ZrO2 species on nanoflake-assembled Al2O3 contributed to the excellent catalytic performance in oxidative dehydrogenation of ethylbenzene with CO2. This kind of special Al2O3 is expected to be a promising support for preparing highly dispersed metal/metal oxide catalysts.

  1. Thermally Stable Hierarchical Nanostructures of Ultrathin MoS2 Nanosheet-Coated CeO2 Hollow Spheres as Catalyst for Ammonia Decomposition.

    Science.gov (United States)

    Gong, Xueyun; Gu, Ying-Qiu; Li, Na; Zhao, Hongyang; Jia, Chun-Jiang; Du, Yaping

    2016-04-18

    MoS2 ultrathin nanosheet-coated CeO2 hollow sphere (CeO2@MoS2) hybrid nanostructures with a 3D hierarchical configuration were successfully constructed from a facile two-step wet chemistry strategy: first, CeO2 formed on a silica core which served as a template and was subsequently removed by NaOH solution to attain hollow spheres, and then few-layered ultrathin MoS2 nanosheets were deposited on the CeO2 hollow spheres through a hydrothermal process. As a proof of concept application, the as-prepared CeO2@MoS2 hybrid nanostructures were used as catalytic material, which exhibited enhanced catalytic activity in ammonia decomposition for H2 production at high temperature. It was demonstrated that, even with a structural transformation from MoS2 to MoNx under harsh conditions of ammonia decomposition at high temperature (700 °C), the 3D hierarchical nanostructures of the CeO2@MoNx were well kept, indicating the important role of the CeO2 support.

  2. Synergistic inhibition effect of L-phenylalanine and rare earth Ce(IV) ion on the corrosion of copper in hydrochloric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Daquan, E-mail: zhangdaquan@shiep.edu.cn [Department of Environmental Engineering, Shanghai University of Electric Power, Shanghai 200090 (China); Wu Huan; Gao Lixin [Department of Environmental Engineering, Shanghai University of Electric Power, Shanghai 200090 (China)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer Synergistic effect of L-phenylalanine (L-Phe) and Ce(SO{sub 4}){sub 2} on the corrosion of copper on the corrosion inhibition of copper in 0.5 M HCl solution. Black-Right-Pointing-Pointer Structure of the complex film formed by the interaction of L-phenylalanine (L-Phe) and Ce(SO{sub 4}){sub 2} on the copper surface. Black-Right-Pointing-Pointer Mechanism of the improvement of the inhibition property of amino acids by the addition of rare earth compound. - Abstract: The synergistic inhibition effect of L-phenylalanine (L-Phe) and Ce(SO{sub 4}){sub 2} on the corrosion of copper in 0.5 M HCl solution was investigated by weight-loss, electrochemical methods and surface analysis. The electrochemical results showed that L-Phe has definite inhibition effects for copper, while Ce(IV) promoted the anodic process of copper corrosion. The combination L-Phe with Ce(IV) ion produced strong synergistic effect on corrosion inhibition for copper. The maximum inhibition efficiency was 82.7% for 5 mM L-Phe + 2 mM Ce(IV). The results of EIS and potentiodynamic polarization are in good agreement. SEM showed that L-Phe and Ce(IV) can form a dense protective film on the copper surface.

  3. Crystallization and fluorescence properties of Ce:YAG glass-ceramics with low SiO{sub 2} content

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lili [Department of Materials Science and Engineering, University of Science and Technology Beijing 100083 (China); Mei, Lin; He, Gang; Liu, Guanghua [Technical Institute of Physics and Chemistry, Key Laboratory of Functional Crystals and Laser Technology, Chinese Academy of Sciences, Beijing 100190 (China); Li, Jiangtao, E-mail: ljt0012@vip.sina.com [Technical Institute of Physics and Chemistry, Key Laboratory of Functional Crystals and Laser Technology, Chinese Academy of Sciences, Beijing 100190 (China); Xu, Lihua [Department of Materials Science and Engineering, University of Science and Technology Beijing 100083 (China)

    2013-04-15

    Ce{sup 3+} doped YAG (Ce:YAG) glass-ceramics with 20 mol% SiO{sub 2} were fabricated by the method of amorphous sintering followed by controlled crystallization (ASCC). An investigation on the crystallization process of as-sintered glasses revealed that surface crystallization occurred first and YAlO{sub 3} (YAP) was precipitated as the main crystalline phase; then bulk crystallization continued inside these glasses and YAP phase transited to YAG. The phase transition from YAP to YAG could be promoted by an inert atmosphere instead of reductive one and by the increase of the crystallization temperature and holding time. By combining the Ce:YAG glass-ceramics with a blue-emitting InGaN chip, white LEDs with a relatively high color rendering index of 80.3 and low color temperature of 5098 K were produced. Their luminous efficacy decreased with the increasing annealing temperatures, which was probably caused by the degradation of transparency. -- Highlights: ► Translucent SiO{sub 2}-low Ce:YAG glass-ceramics were successfully obtained. ► A white LED (CIR, 80.3 and CT, 5098 K) was equipped with the obtained glass-ceramic. ► Controlled surface and bulk crystallizations of the glass were observed. ► Three Ce{sup 3+} emission centers were possibly involved during the luminescence decay. ► Luminous efficacy decreased with elevated annealing temperatures.

  4. Hot-pressing of monazite Ce0.5Pr0.5PO4 ceramic and its chemical durability

    Science.gov (United States)

    Teng, Yuancheng; Zeng, Pan; Huang, Yi; Wu, Lang; Wang, Xiaohuan

    2015-10-01

    Pr-doped monazite-(Ce) ceramic with the composition of Ce0.5Pr0.5PO4 was successfully fabricated utilizing uniaxial hot-press sintering process. The effects of sintering temperature and holding time on bulk density and microstructure of ceramic were investigated, and sintering parameters were optimized. The chemical durability of ceramic was examined through MCC-1 test. The relatively optimal sintering temperature and holding time at 30 MPa were 1150 °C and 2 h, respectively. The hot-pressed ceramic has a smaller fine-grained, closer packed structure than the pressureless sintered ceramic. The element mapping images of Ce, Pr, P and O show that all the elements are almost distributed homogeneously in the monazite ceramics. Furthermore, the normalized dissolution rates of Ce and Pr decrease with increasing time and remain almost unchanged after 28 days. The 42 days normalized dissolution rates of RL(Ce) and RL(Pr) were equal to 5.7 × 10-6 and 5.3 × 10-5 g m-2 d-1, respectively.

  5. Preparation and properties of Pr$_{3+}$/Ce$_{3+}$:YAG phosphors using triethanolamine as dispersant and pH regulator

    Indian Academy of Sciences (India)

    SHIHONG TONG; JUNYAN ZHAO; XIU WEN

    2016-10-01

    Pr$_{3+}$/Ce$_{3+}$:YAG precursors were co-precipitated using triethanolamine as dispersant and pH regulator. The different dosages of triethanolamine (D) vs. the properties of Pr$_{3+}$/Ce$_{3+}$:YAG phosphors were discussed. When $D = 0.5$ vol%, the pH of titration process was controlled in the range of $\\sim$7.94–8.16 to guarantee the uniform distribution of Al, Y, Ce and Pr in the precursors. The relatively higher pH could decrease the loss of Ce and Pr in the precursors and increase the particle size of the obtained powders, which was beneficial to the enhancement of luminescent intensity. Therefore, the precursors directly converted to pure-phase YAG at 900$^{\\circ}$C, and the phosphors calcined at 1000$^{\\circ}$C showed the best dispersity due to the dispersion effect of triethanolamine and the most excellent luminescent property. When $D ≥ 2$ vol%, although pure-phase YAG was detected, the emission intensity of the phosphors decreased due to the decrease of dispersity and purity. Moreover, the co-doped Pr$^{3+}$ enhanced the red emission of Pr$^{3+}$/Ce$^{3+}$:YAG phosphors.

  6. Luminescent properties of Ce3+-doped transparent oxyfluoride glass ceramics containing BaGdF5 nanocrystals

    Institute of Scientific and Technical Information of China (English)

    王倩; 欧阳绍业; 张为欢; 杨斌; 张约品; 夏海平

    2015-01-01

    The transparent oxyfluoride glass ceramics containing BaGdF5 nanocrystals were prepared with a composition of 42SiO2-12Na2O-16Al2O3-24BaF2-4Gd2O3-2CeF3 (mol.%) by thermal treatment technology. The typical DSC curve, X-ray diffraction (XRD) and transmission electron microscopy (TEM) patterns were measured. The transmission spectra and luminescent properties were in-vestigated. The decay times of the Gd3+ions at 312 nm excited with 275 nm for the Ce3+ions doped glass and glass ceramics speci-mens and the energy transfer process between Gd3+ions and Ce3+ions were also studied. The XRD analysis and the TEM images confirmed the generation of the spherical BaGdF5 nanocrystals. Compared with the PG specimen, the intensity of the luminescence spectra of the glass ceramics specimens was apparently enhanced with the heat treatment temperature increasing, and a blue shift in the excitation spectra and the emission spectra of glass ceramics specimens was obviously observed. In the fluorescence decay curves of the Gd3+ions, it could be obviously observed that the fluorescent intensity decays in the Ce3+ions doped glass and glass ceramics specimens decreased rapidly with the increase of the heat treatment temperature. In addition, the energy transfer efficiency from Gd3+ions to Ce3+ions was also calculated.

  7. Promoter of (Ce-Zr)O2 Solid Solution Modified by Praseodymia in Three-Way Catalysts

    Institute of Scientific and Technical Information of China (English)

    汪文栋; 林培琰; 孟明; 伏义路; 胡天斗; 谢亚宁; 刘涛

    2003-01-01

    The three-way catalysts (TWCs) promoters (Ce-Zr)O2, (Pr-Ce-Zr)O2 and (Pr-Zr)O2 were prepared by sol-gel like method. They were characterized by XRD, EXAFS and BET surface area determination. The reduction features of the promoters were measured by temperature-programmed reduction (TPR) of H2 to access the potential for the promoters containing praseodymia as oxygen storage component in three-way catalyst. The (Pr-Zr)O2 cubic solid solution is formed at high temperature up to 800 ℃, which makes it more reducible than the (Ce-Zr)O2 solid solution. For the (Pr-Ce-Zr)O2 samples, the ternary solid solution plays an important role in the reduction process. The performance of the three-way catalysts with fully formulated Pt, Pd and Rh is proceeded by using both light-off temperature under a stoichiometric gas composition and the conversion of CO, C3H6 and NO under changing air/fuel ratio at a constant reaction temperature 400 ℃. The results indicate that a small amount of praseodymia doping into (Ce-Zr)O2 favors the light-off temperature of C3H6 and NO, and all the catalysts containing praseodymia obviously exhibits enhanced width of S value for NO conversion at lean region (S≥1.00).

  8. Mn-CeOx/Ti-PILCs for selective catalytic reduction of NO with NH3 at low temperature.

    Science.gov (United States)

    Shen, Boxiong; Ma, Hongqing; Yao, Yan

    2012-01-01

    Titanium-pillared clays (Ti-PILCs) were obtained by different ways from TiCl4, Ti(OC3H7)4 and TiOSO4, respectively. Mn-CeO(x)/)Ti-PILCs were then prepared and their activities of selective catalytic reduction (SCR) of NO with NH3 at low-temperature were evaluated. Mn-CeO(x)/Ti-PILCs were characterized by X-ray diffraction, N2 adsorption, Fourier transform infrared spectroscopy, thermal analysis, temperature-programmed desorption of ammonia and H2-temperature-programmed reduction. It was found that Ti-pillar tend to be helpful for the enlargement of surface area, pore volume, acidity and the enhancement of thermal stability for Mn-CeO(x)/Ti-PILCs. Mn-CeO(x)/Ti-PILCs catalysts were active for the SCR of NO. Among three resultant Mn-CeO(x)/Ti-PILCs, the catalyst from TiOSO4 showed the highest activity with 98% NO conversion at 220 degrees C, it also exhibited good resistance to H2O and SO2 in flue gas. The catalyst from TiCl4 exhibited the lowest activity due to the unsuccessful pillaring process.

  9. Structural characterization of SiO2/Zn2SiO4:Ce nanocomposite obtained by sol gel method

    Directory of Open Access Journals (Sweden)

    A. Chelouche

    2014-04-01

    Full Text Available Ce-doped ZnO nanopowder and ZnO:Ce/silica nanocomposite were synthesized by sol–gel process under supercritical drying (temperature and pressure of ethanol. Annealing at 1200 °C under atmospheric pressure has been achieved for the prepared ZnO:Ce/silica nanocomposite. X-ray diffraction (XRD showed good crystallinity and a ZnO hexagonal wurtzite structure of the as-prepared powder. The average crystallite size is of the order of 78 nm. Crystallites agglomerate to form spheres, hexagons and/or hexagons inserted in tori. The introduction of ZnO:Ce in silica leads to the formation of zinc silicate even before annealing. The heat treatment reduces the intensity of the diffraction peaks and enhanced the formation of this new phase. Photoluminescence (PL spectra showed that the introduction of ZnO:Ce in silica before annealing reduces the UV lines and red shifts the entire emission. After annealing the PL intensity of the nanocomposite is significantly reduced.

  10. Dark decay behaviours of photorefractive grating induced by two deep-trap levels in Ce:BaTiO3

    Institute of Scientific and Technical Information of China (English)

    Zhang Ming; Xu Ying; Hong Zhi

    2005-01-01

    Dark decay behaviours of photorefractive grating in Ce:BaTiO3 crystal are studied experimentally. It is observed that two deep-trap levels, i.e. Fe-ion deep level and Ce-ion deep level, both participate in the photorefractive process. A simplified two-deep model is presented based on the one-deep trap model and the shallow-deep trap model, with which we analyse quantitatively the contribution of each deep level to the whole space-electric field and thus the photorefractive grating varying with the different grating wave vectors and different writing intensities.

  11. The photosensitive effect of Ce on the precipitation of Ag nanoparticles induced by femtosecond laser in silicate glass

    Institute of Scientific and Technical Information of China (English)

    Dai Ye; Qiu Jian-Rong

    2009-01-01

    This paper studies the photosensitive effect of cerium oxide on the precipitation of Ag nanoparticles after femtosecond laser irradiating into silicate glass and successive annealing. Spectroscopy analysis and diffraction efficiency measurements show that the introduction of cerium oxide may increase the concentration of Ag atoms in the femtosecond laser-irradiated regions resulting from the photoreduction reaction Ce3+ + Ag+→ Ce4+ + Ag0 via multiphoton excitation. These results promote the aggregation of Ag nanoparticles during the annealing process. It is also found that different concentrations of cerium oxide may influence the Ag nanoparticle precipitation in the corresponding glass.

  12. Uued IT-mõtted CeBITilt / Kai Simson

    Index Scriptorium Estoniae

    Simson, Kai

    2006-01-01

    Riigi Infosüsteemide Arenduskeskuse (RIA) pressiesindaja Rica Semjonova vahendab Eesti stendistide muljeid Hannoveris toimunud IT-messilt CeBIT, kus Eestit tutvustasid nii riigiametid kui eraettevõtted

  13. Combustion synthesis of YAG:Ce and related phosphors

    Science.gov (United States)

    Gupta, K. V. K.; Muley, A.; Yadav, P.; Joshi, C. P.; Moharil, S. V.

    2011-11-01

    YAG:Ce is an important phosphor having applications in various fields ranging from solid state lighting to scintillation detectors. YAG phosphors doped with activators are mainly synthesized by solid state reaction techniques that require high sintering temperatures (above 1500°C) to eliminate YAM and YAP phases. Though several soft chemical routes have been explored for synthesis of YAG, most of these methods are complex and phase pure materials are not obtained in one step, but prolonged annealing at temperatures around 1000°C or above become necessary. One step combustion synthesis of YAG:Ce3+ and related phosphors carried out at 500°C furnace temperature is reported here. Activation with Ce3+ could be achieved during the synthesis without taking recourse to any post-combustion thermal treatment. LEDs prepared from the combustion synthesized YAG:Ce3+, exhibited properties comparable to those produced from the commercial phosphor.

  14. Microstructure and Properties of CePO4 Ceramic

    Institute of Scientific and Technical Information of China (English)

    WANG Lijuan; DU Haiyan; OU Xiujuan

    2006-01-01

    Cerium phosphate powders were synthesized by direct solid liquid reaction of cerium dioxide and phosphate acid at the Ce∶P ratio of 1∶1. Phase-pure and fine grain size CePO4 powers could be obtained by calcining the as received powders at the temperature higher than 600 ℃. It is demonstrated that the grain size and morphology of the CePO4 powders were calcined at various temperatures. An interesting layered crystal structure and a series of microcracks that cross and occur along the extrusion stress direction on the extruded surface inside CePO4 were observed. The ductility and machinabililty of CePO4 ceramic are attributed to the layered structure. Continuous machining debris was observed on the turned surface.

  15. 前驱物对Mn-Ce/Ti-PILC低温SCR脱硝的影响%Study on the effect of Mn-Ce/Ti-PILC on low temperature SCR activity prepared with different precursors

    Institute of Scientific and Technical Information of China (English)

    杨晓燕; 沈伯雄; 马宏卿; 刘亭; 左琛

    2012-01-01

    Titania - pillared clay ( Ti-PILC) was obatined with two different Ti precursors of TiCl4 and Ti(OC3H7)4; with Ti-PILC as support, Mn-Ce/Ti-PILCs catalysts were prepared through impregnation. The catalytic activity of Mn-Ce/Ti-PILCs in low temperature SCR of NO with NH3 was investigated. XRD, BET, FT-IR, NHj-TPD and SEM measurements indicated that the pillaring process can change the structure of the clay; compared with the original clay, the specific surface area, the pore volume and the acidity of Ti-PILCs are increased; meanwhile, Mn-Ce/Ti-PILCs also exhibits higher catalytic activity than Mn-Ce/clay. Moreover, Ti( OC3H7 )4 as Ti precursor is more effective in enhancing the catalytic activity of Mn-Ce/Ti-PILCs than TiCl4.%分别采用TiCl4和钛酸丁酯为Ti前驱物制备了钛基交联黏土(Ti-PILC),通过浸渍法将锰铈负载于Ti-PILC上,制得催化剂Mn-Ce/Ti-PILCs和Mn-Ce/clay,测试了该催化剂在以氨气为还原剂的低温SCR过程中的催化活性,分析了Ti前驱物对黏土结构及催化性能的影响.XRD、BET、FT-IR、NH3-TPD和SEM等表征结果表明,与原土(clay)相比,经钛交联柱撑后,Ti-PILC的微观结构更加合理,其比表面积和孔容都有了一定程度的增加,表面酸性有所增强.与原土负载的Mn-Ce/clay催化剂相比,Mn-Ce/Ti-PILCs的催化活性明显提高.而且,钛酸丁酯作前驱物进行交联比TiCl4交联效果更明显,所得到的催化剂低温活性更好.

  16. Hydrothermal synthesis of Ce: LuzSiO5 scintillator powders

    Institute of Scientific and Technical Information of China (English)

    YUN; Ping; SHI; Ying

    2009-01-01

    The synthesis of cerium-doped lutetium oxyorthosilicate (LSO) polycrystalline powders was investigated by a hydrothermal proc-ess. The precursor was obtained by the hydrothermal reaction of Lu(NO3)3 with Na2SiO3 at 200 ℃ for 10 h by using urea as precipitator, fol-lowed by a calcination uader proper temperatures. The results of XRD indicated that the precursor was crystallized into A-type LSO phase at 1000 ℃, and transfetrred to B-type LSO phase when temperature was raised above 1050 ℃. After being heated at 1250 ℃ for 2 h, single phase of B-type LSO powder was synthesized with homogeneous distribution of particle size ranging from 200 to 300 nm. The photolumi-nescence spectrum of as-synthesized LSO: Ce powders showed a typical broad emission peak centered at 404 nm, corresponding to the 5d1-4f transition of Ce3+.

  17. Corrosion resistance of Mg-Mn-Ce magnesium alloy modified by polymer plating

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Polymeric nano-film on the surface of Mg-Mn-Ce magnesium alloy was fabricated by polymer plating of 6-dihexylamino-1,3,5-triazine-2,4-dithiol monosodium(DHN)to improve its corrosion resistance.The electrochemical reaction process was analyzed by cyclic voltammetry and two obvious peaks of oxidation reaction were observed.The static contact angle of distilled water on polymer-plated surface can be up to 106.3°while on the blank surface it is 45.8°.Potentiodynamic polarization results show that the polymeric film Can increase the corrosion potential from-1.594 V VS SCE for blank to-0.382 V VS SCE.The results of electrochemical impedance spectroscopy indicate that the charge transfer resistances of blank and polymer-plated fabricating hydrophobic film on Mg-Mn-Ce alloy surface and improving its anti-corrosion property.

  18. Preparation of Na{sub 4}UO{sub 2}(CO{sub 3}){sub 3} in presence of Ce-141. I, Influence of the post-reaction time in the concentration of anion species of Ce-141; Preparacion del Na{sub 4}UO{sub 2}(CO{sub 3}){sub 3} en presencia de Ce-141. I, Influencia del tiempo de post-reaccion en la concentracion de especies anionicas de Ce-141

    Energy Technology Data Exchange (ETDEWEB)

    Lopez M, B.E.; Rodriguez S, A.; Iturbe G, J.L

    1991-10-15

    An effective condition to minimize the presence of Ce-141, in the final product of recovery like hexa hydrated uranyl nitrate has been obtained. It is considered to this condition like a pre purification stage in the recovery process of the non-fissioned residual uranium in the fission production of Mo-99. (Author)

  19. Preparation of Ce4+, Sb3+-Codoped TiO2 Films in Electric Field Heating-Treatment

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Titania is an important catalytic material for photo-catalytic applications, and the sol-gel process is one of the most appropriate technologies to prepare TiO2 thin films. In the present paper, the Ce4+, Sb3+-codoped TiO2 films were prepared by sol-gel method, which were heat-treated with an applied electric filed. The phase transformation behavior of Ce4+, Sb3+-codoped TiO2 film in the electric field heating-treatment was studied by XRD and AFM. It is found that the crystals were homogeneous and the average crystal size was about 60 nm. Studies of photo-catalytic degradation show that the photo-catalytic activity of Ce4+, Sb3+-codoped TiO2 films heated to 500 ℃ in an applied electric field was higher.

  20. ARTICLES: Synthesis of Biomorphic ZrO2-CeO2 Nanostructures by Silkworm Silk Template

    Science.gov (United States)

    Zhang, Zong-jian; Li, Jia; Sun, Fu-sheng; Dickon, H. L. Ng; Luen Kwong, Fung

    2010-06-01

    A simple and green technique has been developed to prepare hierarchical biomorphic ZrO2-CeO2, using silkworm silk as the template. Different from traditional immersion technics, the whole synthesis process depends more on the restriction or direction functions of the silkworm silk template. The analytic results showed that ZrO2-CeO2 exhibited a well-crystallized hierarchically interwoven hollow fiber structure with 16-28 μm in diameter. The grain size of the sample calcined at 800 °C was about 14 nm. Consequently, the interwoven meshwork at three dimensions is formed due to the direction of biotemplate. The action mechanism is summarily discussed here. It may bring the biomorphic ZrO2-CeO2 nanomaterials with hierarchical interwoven structures to more applications, such as catalysts.

  1. Study on Mg-PSZ Ceramics Doped with Y2O3 and CeO2

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Mg-PSZ ceramics doped with Y2O3 and CeO2 was prepared using traditional processing method. The fine-grain PSZ ceramics(dc≤10 μm) sintered at low temperature(≤1550 ℃) was obtained by means of composition design. The effects of co-stabilization of Y2O3, CeO2 and annealing at 1100 ℃ on material composition, microstructure and mechanical properties were studied. The results show that Y2O3 and CeO2 during annealing at 1100 ℃ can inhibit subeutectoid decomposition reaction effectively, and optimize nucleation and growth of t-ZrO2 precipitates in c-ZrO2 matrix phase. The materials show transgranular and intergranular fracture characteristics, and exhibit better mechanical properties owing to the cooperative effect of stress-induced transformation toughening and microcrack toughening.

  2. Giant Faraday rotation in Bi(x)Ce(3-x)Fe5O12 epitaxial garnet films.

    Science.gov (United States)

    Chandra Sekhar, M; Singh, Mahi R; Basu, Shantanu; Pinnepalli, Sai

    2012-04-23

    Thin films of Bi(x)Ce(3-x)Fe(5)O(12) with x = 0.7 and 0.8 compositions were prepared by using pulsed laser deposition. We investigated the effects of processing parameters used to fabricate these films by measuring various physical properties such as X-ray diffraction, transmittance, magnetization and Faraday rotation. In this study, we propose a phase diagram which provides a suitable window for the deposition of Bi(x)Ce(3-x)Fe(5)O(12) epitaxial films. We have also observed a giant Faraday rotation of 1-1.10 degree/µm in our optimized films. The measured Faraday rotation value is 1.6 and 50 times larger than that of CeYIG and YIG respectively. A theoretical model has been proposed for Faraday rotation based on density matrix method and an excellent agreement between experiment and theory is found.

  3. Cerocene Revisited: The Electronic Structure of and Interconversion Between Ce2(C8H8)3 and Ce(C8H8)2

    Energy Technology Data Exchange (ETDEWEB)

    Walter, Marc D.; Booth, Corwin H.; Lukens, Wayne W.; Andersen, Richard A.

    2009-02-02

    New synthetic procedures for the preparation of Ce(cot)2, cerocene, from [Li(thf)4][Ce(cot)2], and Ce2(cot)3 in high yield and purity are reported. Heating solid Ce(cot)2 yields Ce2(cot)3 and COT while heating Ce2(cot)3 with an excess of COT in C6D6 to 65oC over four months yields Ce(cot)2. The solid state magnetic susceptibility of these three organocerium compounds shows that Ce(cot)2 behaves as a TIP (temperature independent paramagnet) over the temperature range of 5-300 K, while that of Ce2(cot)3 shows that the spin carriers are antiferromagnetically coupled below 10 K; above 10 K, the individual spins are uncorrelated, and [Ce(cot)2]- behaves as an isolated f1 paramagnet. The EPR at 1.5K for Ce2(cot)3 and [Ce(cot)2]- have ground state of MJ= +- 1/2. The LIII edge XANES of Ce(cot)2 (Booth, C.H.; Walter, M.D.; Daniel, M.; Lukens, W.W., Andersen, R.A., Phys. Rev. Lett. 2005, 95, 267202) and 2Ce2(cot)3 over 30-500 K are reported; the Ce(cot)2 XANES spectra show Ce(III) and Ce(IV) signatures up to a temperature of approximately 500 K, whereupon the Ce(IV) signature disappears, consistent with the thermal behavior observed in the melting experiment. The EXAFS of Ce(cot)2 and Ce2(cot)3 are reported at 30 K; the agreement between the molecular parameters for Ce(cot)2 derived from EXAFS and single crystal X-ray diffraction data are excellent. In the case of Ce2(cot)3 no X-ray diffraction data are known to exist, but the EXAFS are consistent with a"triple-decker" sandwich structure. A molecular rationalization is presented for the electronic structure of cerocene having a multiconfiguration ground state that is an admixture of the two configurations Ce(III, 4f1)(cot1.5-)2 and Ce(IV, 4f0)(cot2-)2; the multiconfigurational ground state has profound effects on the magnetic properties and on the nature of the chemical bond in cerocene and, perhaps, other molecules.

  4. Mechanism of (NH{sub 4})S{sub 2}O{sub 8} to enhance the anti-corrosion performance of Mo-Ce inhibitor on X80 steel in acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yanhua [School of Materials Science and Engineering, Southwest Petroleum University, Chengdu 610500 (China); Zhuang, Jia, E-mail: zj-656@163.com [School of Materials Science and Engineering, Southwest Petroleum University, Chengdu 610500 (China); Zeng, Xianguang [Material Corrosion and Protection Key Laboratory of Sichuan Province, Zigong 643000 (China); Institute of Materials and Chemical Engineering, Sichuan University of Science and Engineering, Zigong 643000 (China)

    2014-09-15

    Highlights: • The 1000 mg/L Na{sub 2}MoO{sub 4} and 500 mg/L Ce(NO{sub 3}){sub 3} has best synergistic effect. • The (NH{sub 4}){sub 2}S{sub 2}O{sub 8} made the valence transformation of cerium (Ce{sup 3+} → Ce{sup 4+}) come true. • The anti-corrosion performance of Mo-Ce inhibitor was improved by (NH{sub 4}){sub 2}S{sub 2}O{sub 8}. • The coordination ability of inhibitor complexes was improved by (NH{sub 4}){sub 2}S{sub 2}O{sub 8}. • The bonding force and adsorption between inhibitor and steel surface was enhanced. - Abstract: Ce(NO{sub 3}){sub 3} and Na{sub 2}MoO{sub 4} are adopted to form (Mo-Ce) composite corrosion inhibitor in allusion to the corrosion problem of steel in acidic conditions. The experimental results showed that the anticorrosion effects were enhanced and the inhibition efficiencies were increased by (NH{sub 4}){sub 2}S{sub 2}O{sub 8}. The reason of enhancement is the increase of coordination bonds amount between Ce{sup 4+} and MoO{sub 4}{sup 2−}, the augment of combining sites of interface between anti-corrosion film and steel, and the reinforce of adsorption caused by the transformation of Ce{sup 3+} to Ce{sup 4+} by oxidants. The process and conditions for transformation of Ce{sup 3+} to Ce{sup 4+} and formation of complexes are discussed. The related thermodynamic and kinetic parameters are calculated and the possibility for (NH{sub 4}){sub 2}S{sub 2}O{sub 8} to improve the performance of Mo-Ce corrosion inhibitor is proved.

  5. Spectroscopic properties of the Ce-doped borate glasses

    Science.gov (United States)

    Kindrat, I. I.; Padlyak, B. V.; Mahlik, S.; Kukliński, B.; Kulyk, Y. O.

    2016-09-01

    The EPR, optical absorption and photoluminescence (emission and excitation) spectra as well as decay kinetics of a series of the Ce-doped glasses with Li2B4O7, LiKB4O7, CaB4O7, and LiCaBO3 compositions have been investigated and analysed. The borate glasses were obtained from the corresponding polycrystalline compounds in the air atmosphere, using standard glass technology. The EPR signals of the isolated Ce3+ and pair Ce3+-Ce3+ centres, coupled by magnetic dipolar and exchange interactions were registered at liquid helium temperatures. The characteristic for glass host broad bands corresponding to the 4f → 5d transitions of the Ce3+centres have been observed in the optical absorption and photoluminescence (emission and excitation) spectra. The obtained luminescence decay curves can be satisfactory described by exponential function with lifetimes in the 19.8-26.1 ns range, which depend on the basic glass composition. The local structure of Ce3+ centres in the investigated glasses has been considered and discussed.

  6. Ca2+-Doped CeBr3 Scintillating Materials

    Energy Technology Data Exchange (ETDEWEB)

    Guss, Paul [NSTec; Foster, Michael E. [SNL; Wong, Bryan M. [SNL; Doty, F. Patrick [SNL; Shah, Kanai [RMD; Squillante, Michael R. [RMD; Shirwadkar, Urmila [RMD; Hawrami, Rastgo [RMD; Tower, Josh [RMD; Yuan, Ding [NSTec

    2014-01-01

    Despite the outstanding scintillation performance characteristics of cerium tribromide (CeBr3) and cerium-activated lanthanum tribromide, their commercial availability and application are limited due to the difficulties of growing large, crack-free single crystals from these fragile materials. This investigation employed aliovalent doping to increase crystal strength while maintaining the optical properties of the crystal. One divalent dopant (Ca2+) was used as a dopant to strengthen CeBr3 without negatively impacting scintillation performance. Ingots containing nominal concentrations of 1.9% of the Ca2+ dopant were grown. Preliminary scintillation measurements are presented for this aliovalently doped scintillator. Ca2+-doped CeBr3 exhibited little or no change in the peak fluorescence emission for 371 nm optical excitation for CeBr3. The structural, electronic, and optical properties of CeBr3 crystals were studied using the density functional theory within the generalized gradient approximation. The calculated lattice parameters are in good agreement with the experimental data. The energy band structures and density of states were obtained. The optical properties of CeBr3, including the dielectric function, were calculated.

  7. Fabrication of PMMA CE microchips by infrared-assisted polymerization.

    Science.gov (United States)

    Chen, Yun; Duan, Haotian; Zhang, Luyan; Chen, Gang

    2008-12-01

    In this report, a method based on the infrared-assisted polymerization of methyl methacrylate has been developed for the rapid fabrication of PMMA CE microchips. Methyl methacrylate containing AIBN was allowed to prepolymerize in a water bath to form a fast-curing molding solution that was subsequently sandwiched between a silicon template and a piece of 1 mm-thick PMMA plate. The images of microchannels on the silicon template were precisely replicated into the synthesized PMMA substrates during the infrared-assisted polymerization of the molding solution. The polymerization could be completed within 50 min at 50 degrees C. The obtained channel plate was subsequently bonded to a piece of PMMA cover sheet to form a microchip with the aid of heat and pressure. The new fabrication approach obviates the need for special equipment and significantly simplifies the process of fabricating PMMA microchips. The attractive performance of the obtained PMMA microchips has been demonstrated in connection with contactless conductivity detection for the separation and detection of ionic species.

  8. Defects-assisted ferromagnetism due to bound magnetic polarons in Ce into Fe, Co:ZnO nanoparticles and first-principle calculations.

    Science.gov (United States)

    Verma, Kuldeep Chand; Kotnala, R K

    2016-02-21

    Zn0.94TM0.03Ce0.03O [Zn0.94Fe0.03Ce0.03O (ZFCeO) and Zn0.94Co0.03Ce0.03O (ZCCeO)] nanoparticles were synthesized by a sol-gel process. Elemental analysis of these nanoparticles detects the weight percentage of Zn, Co, Fe, Ce and O in each sample. The Rietveld refinement of the X-ray diffraction pattern obtains the occupancy of dopant atoms, Wurtzite ZnO structure, crystallinity and lattice deformation with doping. The Ce doping into ZFO and ZCO form nanoparticles than nanorods was observed in pure ZnO, ZFO and ZCO samples that described due to chemical and ionic behavior of Ce, Fe, Co and Zn ions. The Raman active modes have peak broadening, intensity changes and peak shifts with metal doping that induces lattice defects. Photoluminescence spectra show blue-shifts at near-band edges and defects that influence broad visible emission with Ce doping. An enhancement in ferromagnetism in the magnetic hysteresis at 5 K is measured. The zero-field cooling and field cooling at H = 500 Oe and T = 300-5 K could confirm antiferromagnetic interactions mediated by defect carriers. The bound magnetic polaron at defect sites is responsible for the observed ferromagnetism. The ac magnetic susceptibility measurements determine the antiferromagnetic to ferromagnetic transition with some magnetic clustered growth in the samples and reveal a frequency independent peak that shows the Neel temperature. Weak room temperature ferromagnetism and optical quenching in ZFCeO are described by valance states of Fe and Ce ions, respectively. Using first-principle calculations, we studied the occupancy of Ce (replacing Zn atoms) in the Wurtzite structure.

  9. A protected annealing strategy to enhanced light emission and photostability of YAG:Ce nanoparticle-based films

    Energy Technology Data Exchange (ETDEWEB)

    Revaux, Amelie; Dantelle, Geraldine; George, Nathan; Seshadri, Ram; Gacoin, Thierry; Boilot, Jean-Pierre

    2012-03-14

    A significant obstacle in the development of YAG:Ce nanoparticles as light converters in white LEDs and as biological labels is associated with the difficulty of finding preparative conditions that allow simultaneous control of structure, particle size and size distribution, while maintaining the optical properties of bulk samples. Preparation conditions frequently involve high-temperature treatments of precursors (up to 1400 C), which result in increased particle size and aggregation, and lead to oxidation of Ce(III) to Ce(IV). We report here a process that we term protected annealing, that allows the thermal treatment of preformed precursor particles at temperatures up to 1000 C while preserving their small size and state of dispersion. In a first step, pristine nanoparticles are prepared by a glycothermal reaction, leading to a mixture of YAG and boehmite crystalline phases. The preformed nanoparticles are then dispersed in a porous silica. Annealing of the composite material at 1000 C is followed by dissolution of the amorphous silica by hydrofluoric acid to recover the annealed particles as a colloidal dispersion. This simple process allows completion of YAG crystallization while preserving their small size. The redox state of Ce ions can be controlled through the annealing atmosphere. The obtained particles of YAG:Ce (60 {+-} 10 nm in size) can be dispersed as nearly transparent aqueous suspensions, with a luminescence quantum yield of 60%. Transparent YAG:Ce nanoparticle-based films of micron thickness can be deposited on glass substrates using aerosol spraying. Films formed from particles prepared by the protected annealing strategy display significantly improved photostability over particles that have not been subject to such annealing.

  10. Ce O{sub 2}-Zr O{sub 2} tetragonal ceramics (Ce-TZP): mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Nono, Maria do Carmo de Andrade [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Laboratorio Associado de Sensores e Materiais

    1994-12-31

    This work presents the development and the characterization of Ce O{sub 2}-stabilized tetragonal Zr O{sub 2} polycrystals (Ce-TZP ceramics), since it is considered candidate material for applications as structural high performance ceramics, an as substitute of some metallic materials. Ce-TZP ceramics attain remarkable increasing in strength and fracture toughness. Sintered ceramics were fabricated from mixtures of powders containing different Ce O{sub 2} content prepared by conventional mechanical technique. It were adopted the bending strength, Vickers hardness and fracture toughness techniques to the determination of the mechanical parameters. These results were discussed and compared to those published in international literature. (author) 11 refs., 10 figs.

  11. Development of all chemical solution derived Ce0.9La0.1O2 − y/Gd2Zr2O7 buffer layer stack for coated conductors: influence of the post-annealing process on surface crystallinity

    DEFF Research Database (Denmark)

    Yue, Zhao; Li, Xiaofen; Khoryushin, Alexey

    2012-01-01

    Preparation and characterization of a biaxially textured Gd2Zr2O7 and Ce0.9La0.1O2 − y (CLO, cap)/Gd2Zr2O7 (GZO, barrier) buffer layer stack by the metal–organic deposition route are reported. YBa2Cu3O7 − d (YBCO) superconductor films were deposited by the pulsed-laser deposition (PLD) technique ......-field), demonstrating that the novel CLO/GZO stack is very promising for further development of low cost buffer layer architectures for coated conductors....

  12. Magnetic susceptibility study of Ce{sup 3+} in PbCeA (A=Te, Se, S)

    Energy Technology Data Exchange (ETDEWEB)

    Gratens, X., E-mail: xgratens@gmail.com [Instituto de Fisica, Universidade de Sao Paulo, 05315-970, Sao Paulo (Brazil); Isber, S., E-mail: si00@aub.edu.lb [American University of Beirut, Department of Physics, Bliss Street, PO Box 11-0236, Beirut 1107-2020 (Lebanon); Charar, S., E-mail: salam.charar@iut-nimes.fr [Group d' Etudes des Semiconducteurs (GES), Universite Montpellier II, CC074, 34095 Montpellier Cedex 5 (France); Golacki, Z. [Institute of Physics, Polish Academy of Sciences, Pl.02-668 Warsaw (Poland)

    2012-09-15

    The magnetic susceptibility of Pb{sub 1-x}Ce{sub x}A (A=S, Se and Te) crystals with Ce{sup 3+} concentrations 0.006{<=}x{<=}0.036 was investigated in the temperature range from 2 K to 300 K. The magnetic susceptibility data was found to be consistent with a {sup 2}F{sub 5/2} lowest manifold for Ce{sup 3+} ions with a crystal-field splitting {Delta}=E({Gamma}{sub 8})-E({Gamma}{sub 7}) of about 340 K, 440 K and 540 K for Pb{sub 1-x}Ce{sub x}Te, Pb{sub 1-x}Ce{sub x}Se, and Pb{sub 1-x}Ce{sub x}S, respectively. For all the three compounds the doublet {Gamma}{sub 7} lies below the {Gamma}{sub 8} quadruplet which confirms the substitution of Pb{sup 2+} by Ce{sup 3+} ions in the host crystals. The observed values for the crystal-field splitting are in good agreement with the calculated ones based on the point-charge model. Moreover, the effective Lande factors were determined by X-band ({approx}9.5 GHz), electron paramagnetic measurements (EPR) to be g=1.333, 1.364, and 1.402 for Ce ions in PbA, A = S, Se and Te, respectively. The small difference with the predicted Lande factor g of 10/7 for the {Gamma}{sub 7} (J=5/2) ground state was attributed to crystal-field admixture. - Highlights:: Black-Right-Pointing-Pointer Magnetic susceptibility of Pb{sub 1-x}Ce{sub x}A (A=Te, Se and S). Black-Right-Pointing-Pointer Computed the zero-field splitting of Ce{sup 3+} ion in lead chalcogenides. Black-Right-Pointing-Pointer Explained the existence of four Ce{sup 3+} sites in PbA (A=Te, Se and S).

  13. Performance comparison between ceramic Ce:GAGG and single crystal Ce:GAGG with digital-SiPM

    Science.gov (United States)

    Park, C.; Kim, C.; Kim, J.; Lee, Y.; Na, Y.; Lee, K.; Yeom, J. Y.

    2017-01-01

    The Gd3Al2Ga3O12 (Ce:GAGG) is a new inorganic scintillator known for its attractive properties such as high light yield, stopping power and relatively fast decay time. In this study, we fabricated a ceramic Ce:GAGG scintillator as a cost-effective alternative to single crystal Ce:GAGG and, for the first time, investigated their performances when coupled to the digital silicon photomultiplier (dSiPM)—a new type of photosensor designed for applications in medical imaging, high energy and astrophysics. Compared to 3 × 3 × 2 mm3 sized single crystal Ce:GAGG, the translucent ceramic Ce:GAGG, which has a much lower transmittance than the single crystal, was determined to give an output signal amplitude that is approximately 61% of single crystal Ce:GAGG. The energy resolution of the 511 keV annihilation peak of a 22Na source was measured to be 9.9 ± 0.2% and 13.0 ± 0.3% for the single and ceramic scintillators respectively. On the other hand, the coincidence resolving time (CRT) of ceramic Ce:GAGG was 307 ± 23 ps, better than the 465 ± 37 ps acquired with single crystals—probably attributed to its slightly faster decay time and higher proportion of the fast decay component. The ceramic Ce:GAGG may be a promising cost-effective candidate for applications that do not require thick scintillators such as x-ray detectors and charged particle detectors, and those that require time-of-flight capabilities.

  14. The Problems of C-E Public Signs' Translating%The Problems of C-E Public Signs'Translating

    Institute of Scientific and Technical Information of China (English)

    冯煊

    2016-01-01

    With the development of our country, we build up a good relationship with western countries. Public signs are regarded as a symbol of our country.Thus, appropriate translations of the public signs can guarantee a good communication between the Chinese and the international people. However, there are many problems on C-E public signs' translation. This paper gives some advice for C-E public signs' translating under the guidance of Skopostheorie.

  15. Electroless ternary NiCeP coatings: Preparation and characterisation

    Energy Technology Data Exchange (ETDEWEB)

    Balaraju, J.N., E-mail: jnbalraj@nal.res.in [Surface Engineering Division, CSIR National Aerospace Laboratories, Post Bag No. 1779 Bangalore 560017, Karnataka (India); Chembath, Manju [Surface Engineering Division, CSIR National Aerospace Laboratories, Post Bag No. 1779 Bangalore 560017, Karnataka (India)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Rare earth element (Ce) has been successfully codeposited in NiP matrix. Black-Right-Pointing-Pointer Surface analysis carried out by XPS showed that the Ce is present in +3 and +4 oxidation state. Black-Right-Pointing-Pointer Palladium stability test indicated that the Ce salts in electroless nickel bath has reduced the stability. Black-Right-Pointing-Pointer Cerium codeposition in NiP matrix has increased the microhardness both in as-plated and annealed conditions. Black-Right-Pointing-Pointer Higher thermal stability has been obtained by Ce incorporation. - Abstract: Electroless ternary NiCeP deposits were prepared from alkaline citrate bath containing nickel sulphate, cerium chloride and sodium hypophosphite. Concentration of rare earth cerium was varied from 1 to 2 g/L to obtain ternary deposits containing variable Ce and P contents. The influence of cerium on the deposit properties was analysed. The deposit exhibited a maximum cerium content of 6.2 {+-} 0.1 wt.% when the cerium chloride concentration was 2 g/L. The result of the Pd stability test showed that the stability of the bath was reduced due to Ce salt addition. The microhardness measurements made on both as-plated and heat treated samples exhibited a peak hardness of 1006 {+-} 11 VHN for cerium concentration of 1.5 g/L. The concept of kinetic strength analysis was proved to be applicable only for binary and not for ternary alloys due to multistep deposition mechanism with different kinetic energies. X-ray diffraction (XRD) patterns of as-plated and heat treated samples revealed peaks corresponding to Ni (1 1 1) and nickel phosphide (Ni{sub 3}P). Higher amount of Ce incorporation in NiP matrix increased the crystallisation temperature of the deposit which could be due to the suppression of nickel crystallisation prior to Ni{sub 3}P compound formation and thus increasing the activation energy for the formation of stable phases. Surface compositional analysis

  16. The CE3R Network: current status and future perspectives

    Science.gov (United States)

    Lenhardt, Wolfgang; Pesaresi, Damiano; Živčić, Mladen; Costa, Giovanni; Kuk, Kresimir; Bondár, István; Duni, Llambro; Spacek, Petr

    2016-04-01

    In order to improve the monitoring of seismic activities in the border regions and to enhance the collaboration between countries and seismological institutions in Central Europe, the Environment Agency of the Slovenian Republic (ARSO), the Italian National Institute for Oceanography and Experimental Geophysics (OGS), the University of Trieste (UniTS) and the Austrian Central Institute for Meteorology and Geodynamics (ZAMG) established in 2001 the "South Eastern Alps Transfrontier Seismological Network". In May 2014 ARSO, OGS, UniTS and ZAMG agreed to formalize the transfrontier network, to name it "Central and East European Earthquake Research Network", (CE3RN or CE3R Network) in order to locate it geographically since cross-border networks can be established in other areas of the world and to expand their cooperation, including institutions in other countries. The University of Zagreb (UniZG) joined CE3RN in October 2014. The Kövesligethy Radó Seismological Observatory (KRSZO) of the Hungarian Academy of Sciences joined CE3RN in October 2015. The Institute of Geosciences, Energy, Water and Environment (IGEWE) of the Polytechnic University of Tirana joined CE3RN in November 2015. The Institute of Physics of the Earth (IPE) of the Masaryk University in Brno joined CE3RN in November 2015. CE3RN Parties intend to formalize and possibly extend their ongoing cooperation in the field of seismological data acquisition, exchange and use for seismological and earthquake engineering and civil protection purposes. The purpose of this cooperation is to retain and expand the existing cross-border network, specify the rules of conduct in the network management, improvements, extensions and enlargements, enhance seismological research in the region, and support civil protection activities. Since the formal establishment of CE3RN, several common projects have been completed, like the SeismoSAT project for the seismic data center connection over satellite funded by the Interreg

  17. The role of calcification for staging cystic echinococcosis (CE)

    Energy Technology Data Exchange (ETDEWEB)

    Hosch, Waldemar; Kauffmann, Guenter W. [University Hospital Heidelberg, Department of Radiology, Heidelberg (Germany); Stojkovic, Marija; Junghanss, Thomas [University Hospital of Heidelberg, Section of Clinical Tropical Medicine, Heidelberg (Germany); Jaenisch, Thomas [University Hospital of Heidelberg, Section of Clinical Tropical Medicine, Heidelberg (Germany); University Hospital of Heidelberg, Section of Biostatistics and Epidemiology, Heidelberg (Germany)

    2007-10-15

    The prevalence of calcified cysts and the significance of calcification as a sign of cyst inactivity in cystic echinococcosis (CE) was evaluated. Seventy-eight patients (36 females, 42 males, mean age 40.8 {+-} 16.9 years) with CE, having a total of 137 abdominal cysts (116 hepatic, three splenic, one renal and 17 peritoneal cysts), were diagnosed and followed-up by ultrasound during and after albendazole treatment or as part of the watch-and-wait approach recording changes in the cyst wall and content. In 48 patients with 94 cysts, computed tomography (CT) imaging was additionally available and was correlated with ultrasound findings. Cyst wall calcification was classified into (1) ''sprinkled'', (2) ''eggshell-like'', and (3) ''circular''. Calcification of the cyst wall and/or cyst content was detected in 67 echinococcal cysts (48.9% of all cysts) in 39 patients (15 females, 24 males, mean age 40.8 {+-} 14.8 years). Of the total of 67 calcified cysts, only 23 were compatible with WHO type CE5, 18 with WHO type CE4. Judged by cyst content, the remaining 26 were of WHO type CE1, CE2 and CE3 (n = 1, n = 8, and n = 17, respectively). During a mean period of 34.3 months ({+-}21.3 months) the majority of cysts (n = 32) did not exhibit any change in cyst content and wall properties. Fourteen cysts showed signs of progressive involution, five cysts (all of WHO type CE3) of renewed activity defined by recurring fluid collection. In 16 cysts, no follow-up was available due to surgery or drop out. Calcification of the cyst is not restricted to the inactive WHO cyst types CE4 and CE5, but occurs in all stages and in up to 50% of cysts. The completeness and, most importantly, the stability of consolidation of cyst content over time predicts cyst inactivity more reliably. (orig.)

  18. Effects of CeO2 Support Facets on VOx/CeO2 Catalysts in Oxidative Dehydrogenation of Methanol

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan; Wei, Zhehao; Gao, Feng; Kovarik, Libor; Peden, Charles HF; Wang, Yong

    2014-05-13

    CeO2 supports with dominating facets, i.e., low index (100), (110) and (111) facets, are prepared. The facet effects on the structure and catalytic performance of supported vanadium oxide catalysts are investigated using oxidative dehydrogenation of methanol as a model reaction. In the presence of mixed facets, Infrared and Raman characterizations demonstrate that surface vanadia species preferentially deposit on CeO2 (100) facets, presumably because of its higher surface energy. At the same surface vanadium densities, VOx species on (100) facets show better dispersion, followed by (110) and (111) facets. The VOx species on CeO2 nanorods with (110) and (100) facets display higher activity and lower apparent activation energies compared to that on CeO2 nanopolyhedras with dominating (111) facets and CeO2 nanocubes with dominating (100) facets. The higher activity for VOx/CeO2(110) might be related to the more abundant oxygen vacancies present on the (110) facets, evidenced from Raman spectroscopic measurements.

  19. SYNTHESIS OF CeAPO- 5 MOLECULAR SIEVE%CeAPO-5分子筛的合成

    Institute of Scientific and Technical Information of China (English)

    张岩; 秦海莉; 高平强

    2010-01-01

    以三乙胺为模板剂、利用水热晶化法合成CeAPO-5分子筛,系统考察了铝源、水量以及晶化条件对CeAPO-5分子筛合成的影响.研究结果表明:铝源是决定CeAPO-5分子筛合成及结构的关键组分之一,拟薄水铝石AlO(OH)是合成CeAPO-5分子筛的比较合适的铝源;在n(P2O5)∶n(Al2O3)∶n(Et3N)∶n(H2O)∶n(Ce2O3)=1∶0.8∶0.26∶60∶0.5;晶化温度150℃;晶化72小时的条件下,可合成CeAPO-5分子筛.

  20. Role of surface Ni and Ce species of Ni/CeO2 catalyst in CO2 methanation

    Science.gov (United States)

    Zhou, Guilin; Liu, Huiran; Cui, Kaikai; Jia, Aiping; Hu, Gengshen; Jiao, Zhaojie; Liu, Yunqi; Zhang, Xianming

    2016-10-01

    CeO2, which was used as support to prepare mesoporous Ni/CeO2 catalyst, was prepared by the hard-template method. The prepared NiO/CeO2 precursor and Ni/CeO2 catalyst were studied by H2-TPR, in-situ XPS, and in-situ FT-IR. The catalytic properties of the prepared Ni/CeO2 catalyst were also investigated by CO2 catalytic hydrogenation methanation. H2-TPR and in-situ XPS results showed that metal Ni species and surface oxygen vacancies could be formed by H2 reduction. In-situ FT-IR and in-situ XPS results indicated that CO2 molecules could be reduced by active metal Ni species and surface oxygen vacancies to generate active CO species and promote CO2 methanation. The Ni/CeO2 catalyst presented the high CO2 methanation activity, and CO2 conversion and CH4 selectivity reached 91.1% and 100% at 340 °C and atmospheric pressure.

  1. Enhancement of photocatalytic activity of combustion-synthesized CeO{sub 2}/C{sub 3}N{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dong-Feng; Yang, Ke; Wang, Xiao-qin; Ma, Ya-Li; Huang, Gui-Fang; Huang, Wei-Qing [Hunan University, Department of Applied Physics, School of Physics and Electronics, Changsha (China)

    2015-09-15

    Nanocrystalline CeO{sub 2}/C{sub 3}N{sub 4} was synthesized via a one-step solution combustion method using urea as fuel for the first time. The effects of the molar ratio of urea to cerium chloride on the photocatalytic activity of the synthesized samples were investigated. The synthesized nanocrystalline CeO{sub 2}/C{sub 3}N{sub 4} shows small size and large surface exposure area. Photocatalytic degradation of methylene blue demonstrates that the synthesized nanocrystalline CeO{sub 2}/C{sub 3}N{sub 4} possesses enhanced photocatalytic activity. It is proposed that the enhanced photocatalytic activity might be related to the favorable morphology and structure, and the effective charge separation between C{sub 3}N{sub 4} and CeO{sub 2} in the photocatalytic process. (orig.)

  2. A novel Ce(IO3)4 catalyst: Facile preparation and high activity in degradation of organic dyes without light irradiation at room temperature

    Science.gov (United States)

    Li, Jiayin; Ma, Xinping; Zhao, Caixian; Lan, Fujun; Chen, Feng; Liu, Xuan; Tang, Jianting

    2017-01-01

    Developing efficient catalysts capable of degrading organic dye free of light irradiation is highly interesting from the energy-saving point of view. In this work, we prepared a new Ce(IO3)4 catalyst by a facile precipitation method. The obtained Ce(IO3)4 sample showed remarkably superior performance to the reported CeGeO4 analog in degradation of rhodamine B (RhB), methyl orange (MO) or methylene blue (MB) dyes in the dark at room temperature. The ultraviolet-visible (UV-vis) absorption spectra of dye solution during degradation, the XPS results of Ce(IO3)4 and the control experiments confirmed that the dye degradation is a catalytic process. The reusability of it was also investigated in the degradation experiments.

  3. Influence of preparation methods on CuO-CeO2 catalysts in the preferential oxidation of CO in excess hydrogen

    Institute of Scientific and Technical Information of China (English)

    Zhigang Liu; Renxian Zhou; Xiaoming Zheng

    2008-01-01

    Influence of three different preparation methods, i.e. impregnation, coprecipitation, and inverse coprecipitation, on the preferential oxidation of CO in excess hydrogen (PROX) over CuO-CeO2 catalysts has been investigated and CuO-CeO2 catalysts are characterized using BET, XPS, XRD, UV Raman, and TPR techniques. The results show that the catalysts prepared by coprecipitation have smaller particle sizes, well-dispersed CuOx species, more oxygen vacancies, and are more active in the PROX than those prepared by the other methods. However, the inverse coprecipitation depresses the catalytic performance of CuO-CeO2 catalysts and causes the growth of CuO-CeO2 because of different pH value in the precipitation process.

  4. Utilizing peroxide as precursor for the synthesis of CeO2/ZnO composite oxide with enhanced photocatalytic activity

    Science.gov (United States)

    Lv, Zijian; Zhong, Qin; Ou, Man

    2016-07-01

    A facile synthesis method of CeO2/ZnO composite oxides with higher oxygen vacancy concentration was developed by a two-step precipitation method, in which peroxide was used as precursor. The photocatalytic activity of the catalysts under UV irradiation was studied in degradation of methylene blue (MB). All CeO2/ZnO photocatalysts exhibited higher photocatalytic performance than pure ZnO, and 1%CeO2/ZnO showed highest photocatalytic activity among the prepared catalysts. It was confirmed that the synergistic effect of CeO2 and oxygen vacancy caused the improved photocatalytic activity. Furthermore, the mechanism was investigated by introducing different additives, and it was found that the hydroxyl radicals played a crucial role in degradation process.

  5. Blue-yellow photoluminescence from Ce{sup 3+} {yields} Dy{sup 3+} energy transfer in HfO{sub 2}:Ce{sup 3+}:Dy{sup 3+} films deposited by ultrasonic spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Martinez, R. [Instituto de Fisica y Matematicas, Universidad Tecnologica de la Mixteca, Carretera a Acatlima Km. 2.5, Huajuapan de Leon, Oaxaca 69000 (Mexico); Lira, A.C. [Unidad Academica Profesional Nezahualcoyotl, Universidad Autonoma del Estado de Mexico, Av. Bordo de Xochiaca s/n, Nezahualcoyotl, Estado de Mexico 57000 (Mexico); Speghini, A. [DiSTeMeV, Universita di Verona, and INSTM, UdR Verona, Via Della Pieve 70, I-37029 San Floriano (Verona) (Italy); Falcony, C. [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, Mexico, D.F. 09340 (Mexico); Caldino, U., E-mail: cald@xanum.uam.mx [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, Mexico, D.F. 09340 (Mexico)

    2011-02-10

    Research highlights: > A blue-yellow emission phosphor excited with UV radiation can be manufactured with CeCl{sub 3} and DyCl{sub 3} doped HfO{sub 2} films deposited at 300 deg. C by the ultrasonic spray pyrolysis technique. > The addition of DyCl{sub 3} in the HfO{sub 2}:CeCl{sub 3} film leads to a non-radiative energy transfer from Ce{sup 3+} to Dy{sup 3+} under Ce{sup 3+} excitation at 280 nm. > The efficiency of this transfer increases up to 86 {+-} 3% for the film with the highest Dy{sup 3+} content. > The possibility of achieving the coordinates of ideal white light with increasing the concentration of dysprosium is demonstrated. - Abstract: HfO{sub 2} films codoped with Ce{sup 3+} and several concentrations of Dy{sup 3+} have been processed by the ultrasonic spray pyrolysis technique. Emissions from Dy{sup 3+} ions centred at 480 and 575 nm associated with the {sup 4}F{sub 9/2} {yields} {sup 6}H{sub 15/2} and {sup 4}F{sub 9/2} {yields} {sup 6}H{sub 13/2} transitions, respectively, have been observed upon UV excitation via a non-radiative energy transfer from Ce{sup 3+} to Dy{sup 3+} ions. Such energy transfer via an electric dipole-quadrupole interaction appears to be the most probable transfer mechanism. The efficiency of this transfer increases up to 86 {+-} 3% for the film with the highest Dy{sup 3+} content (1.9 {+-} 0.1 at.% as measured from EDS). The possibility of achieving the coordinates of ideal white light with increasing the concentration of dysprosium is demonstrated.

  6. A comparative study of CeO2-Al2O3 support prepared with different methods and its application on MoO3/CeO2-Al2O3 catalyst for sulfur-resistant methanation

    Science.gov (United States)

    Jiang, Minhong; Wang, Baowei; Yao, Yuqin; Li, Zhenhua; Ma, Xinbin; Qin, Shaodong; Sun, Qi

    2013-11-01

    The CeO2-Al2O3 supports prepared with impregnation (IM), deposition precipitation (DP), and solution combustion (SC) methods for MoO3/CeO2-Al2O3 catalyst were investigated in the sulfur-resistant methanation. The supports and catalysts were characterized by N2-physisorption, transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy (RS), and temperature-programmed reduction (TPR). The N2-physisorption results indicated that the DP method was favorable for obtaining better textural properties. The TEM and RS results suggested that there is a CeO2 layer on the surface of the support prepared with DP method. This CeO2 layer not only prevented the interaction between MoO3 and γ-Al2O3 to form Al2(MoO4)3 species, but also improved the dispersion of MoO3 in the catalyst. Accordingly, the catalysts whose supports were prepared with DP method exhibited the best catalytic activity. The catalysts whose supports were prepared with SC method had the worst catalytic activity. This was caused by the formation of Al2(MoO4)3 and crystalline MoO3. Additionally, the CeO2 layer resulted in the instability of catalysts in reaction process. The increasing of calcination temperature of supports reduced the catalytic activity of all catalysts. The decrease extent of the catalysts whose supports were prepared with DP method was the lowest as the CeO2 layer prevented the interaction between MoO3 and γ-Al2O3.

  7. Luminescence properties and energy transfer investigations of Sr{sub 3}Lu(PO{sub 4}){sub 3}:Ce{sup 3+}, Tb{sup 3+} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zaifa; Xu, Denghui, E-mail: xudh@btbu.edu.cn; Sun, Jiayue; Du, Jiangnan; Gao, Xuedong

    2016-09-15

    Highlights: • A phosphor Sr{sub 3}Lu(PO{sub 4}){sub 3}:Ce{sup 3+}, Tb{sup 3+} for UV-based white LEDs was firstly synthesized successfully. • The phase structure and photoluminescence properties of samples were studied in detail. • The energy transfer process from Ce{sup 3+} to Tb{sup 3+} ions was illustrated in detail. • Sr{sub 3}Lu(PO{sub 4}){sub 3}:Ce{sup 3+}, Tb{sup 3+} phosphor has potential applications as an UV-convertible phosphor for white light emitting diodes. - Abstract: A series of Ce{sup 3+} or Tb{sup 3+} doped and Ce{sup 3+}/Tb{sup 3+} co-doped Sr{sub 3}Lu(PO{sub 4}){sub 3} phosphors were prepared via the conventional high temperature solid-state reaction. The phase structure, photoluminescence and energy transfer properties of samples were studied in detail. The optimal proportion of Ce{sup 3+} single doping is 4 mol% with maximal fluorescence intensity. The Sr{sub 3}Lu(PO{sub 4}){sub 3}:Ce{sup 3+}, Tb{sup 3+} phosphor shows both a blue emission (428 nm) from Ce{sup 3+} and a yellowish-green emission (545 nm) from Tb{sup 3+} with considerable intensity under ultraviolet (UV) excitation (268 nm). The energy transfer from Ce{sup 3+} to Tb{sup 3+} ions takes place in the Sr{sub 3}Lu(PO{sub 4}){sub 3}:Ce{sup 3+}, Tb{sup 3+} phosphor on the basis of the analysis of the luminescence spectra. The energy transfer mechanism from Ce{sup 3+} to Tb{sup 3+} ions was proved to be dipole–dipole interaction. The energy transfer behaviors in Sr{sub 3}Lu(PO{sub 4}){sub 3}:Ce{sup 3+}, Tb{sup 3+} phosphor is also investigated by the lifetime measurement. The results show that this phosphor has potential applications for UV white-light LEDs.

  8. Fluorescence properties of novel near-infrared phosphor CaSc{sub 2}O{sub 4}:Ce{sup 3+}, Nd{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Meng, J.X., E-mail: tmjx@jnu.edu.c [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); Zhang, F.J.; Peng, W.F.; Wan, W.J.; Xiao, Q.L.; Chen, Q.Q.; Cao, L.W. [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Wang, Z.L. [School of Chemistry and Biotechnology, Yunnan Nationalities University, Kunming 650031 (China)

    2010-10-15

    Research highlights: Novel near-infrared (NIR) phosphor, CaSc{sub 2}O{sub 4}:Ce{sup 3+}, Nd{sup 3+}, was synthesized. The phosphor gives strong Nd{sup 3+} characteristic NIR emissions in the range of 880-930 nm. The NIR emission intensity gets a 200 times enhancement benefited from the efficient energy transfer from a co-doped Ce{sup 3+}. The energy transfer mechanism was also briefly based on detailed investigation on spectrum and fluorescence lifetime. - Abstract: Novel near-infrared (NIR) phosphor, CaSc{sub 2}O{sub 4}:Ce{sup 3+}, Nd{sup 3+}, was synthesized by co-precipitation method followed by firing at 1300 {sup o}C in reduced atmosphere. When irradiated with blue light, the phosphor gives strong Nd{sup 3+} characteristic NIR emissions in the range of 880-930 nm. The NIR emission intensity gets a 200 times enhancement by co-doping of Ce{sup 3+}. Detailed investigation on spectrum and fluorescence lifetimes indicated the NIR luminescence enhancement is obtained from an energy transfer process. The process initiates with efficient absorption of blue light by Ce{sup 3+} ions via an allowed 4f-5d transition, follow by efficient energy transfer from Ce{sup 3+} to Nd{sup 3+}, and emitting strong Nd{sup 3+} characteristic fluorescence.

  9. Growth and characterization of air annealing Mn-doped YAG:Ce single crystal for LED

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Weidong, E-mail: xiangweidong001@126.com [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325035 (China); College of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Zhong, Jiasong [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325035 (China); College of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Zhao, Yinsheng [Pan Asia Technical Automotive Center Co. Ltd., Shanghai 201201 (China); Zhao, Binyu [College of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Liang, Xiaojuan [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325035 (China); Dong, Yongjun [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800 (China); Zhang, Zhimin; Chen, Zhaoping; Liu, Bingfeng [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325035 (China)

    2012-11-25

    Highlights: Black-Right-Pointing-Pointer The YAG:Ce,Mn single crystal was well synthesized by the Czochralski (CZ) method. Black-Right-Pointing-Pointer The emission intensity of the sample has been influenced after annealing. Black-Right-Pointing-Pointer Annealed in the air at 1200 Degree-Sign C was the most optimal annealing condition. Black-Right-Pointing-Pointer The single crystal could be used in the white light LED which emitted by blue light. - Abstract: The growth of Mn-doped YAG:Ce (yttrium aluminum garnet doped cerium) single crystal by the Czochralski (CZ) method and the characterization of its spectroscopy and color-electric parameters are presented. The absorption spectra indicate that the crystal absorbed highly in the 300-500 nm wavelength range. The emission spectrum of the crystal consists of a peak around 538 nm when excited by 460 nm blue light, which prove the YAG:Ce,Mn single crystal could be used in the white light emitting doides (LED). The different charges of Mn ions have different luminescence properties, and the air annealing process for the single crystal would change the concentration of Mn ions with different charges, which could influence the emission intensity of the single crystal.

  10. Sorption of La(III) and Ce(III) by oxidized carbon nanotubes

    Science.gov (United States)

    Lyu, Sh. T.; Rakov, E. G.

    2016-10-01

    The ion-exchange sorption of La(III) and Ce(III) from nitrate solutions using oxidized carbon nanotubes with a solubility of 4.2 g/L is studied at metal concentration C = 5-160 mg/L, pH 2.5-6.0, ratio S: L = 0.002-0.06, and room temperature. At C = 35 mg/L, the equilibrium capacity is shown to grow dramatically with pH rising from 3.0 to 4.0-4.5 and reaching 840 mg/g in La and 950 mg/g in Ce when S: L 4.0-4.5. The introduction of ionic salts is found to reduce the capacity (at pH > 4 and concentrations of 0.01 M and 0.1 M NaCl, the Ce capacity is reduced to ~500 and ~200 mg/g). It is concluded that the sorption equilibrium is better described by the Langmuir equation, while the process kinetics, by pseudo-first and pseudo-second order equations.

  11. Magnetocaloric Properties Response in High-Speed Melt-Spun La-Ce-Fe-Si Ribbons

    Science.gov (United States)

    Hou, Xueling; Han, Ning; Xue, Yun; Lu, Qianqian; Wang, Xiaochen; Phan, Manh-Huong

    2016-10-01

    The structure and magnetocaloric properties of La-Ce-Fe-Si alloys have been studied. The samples were prepared by melt spinning, the surface speed of the Cu wheel being 55 m/s. The as-spun ribbons were subsequently annealed at 1273 K for different times (10 min-1 h) and then quenched to room temperature. When the annealing time was 20 min, on a 1.5-T applied magnetic field, the maximum magnetic entropy change (Δ S M) of the ribbons reached values of 33.8 J/kg K at the Curie temperature of T C ˜ 182 K. When the annealing time was longer than 20 min, the maximum magnetic entropy change (|Δ S M,Max|) tended to decrease while the T C remained almost unchanged. In the annealing process, La/Ce located at grain boundaries was easily oxidized on the ribbon surface. The presence of large grain sizes and La2O3 or LaO were shown to degrade the magnetocaloric properties. On the other hand, the substitution of Ce for La improved the magnetocaloric effect of La-Fe-Si compounds, which is of practical importance for magnetic refrigeration.

  12. Equilibrium and kinetic modeling of adsorptive sulfur removal from gasoline by synthesized Ce-Y zeolite

    Science.gov (United States)

    Montazerolghaem, Maryam; Rahimi, Amir; Seyedeyn-Azad, Fakhry

    2010-11-01

    In this research, the adsorption of a model sulfur compound, thiophene, from a simulated gasoline onto Ce-Y zeolite in pellet and powder forms was investigated. For this purpose, zeolite Na-Y was synthesized, and Ce-Y zeolite was prepared via solid-state ion-exchanged (SSIE) method. Adsorptive desulfurization of model gasoline was conducted in a batch reactor at ambient conditions to evaluate the equilibrium and kinetics of thiophene adsorption onto Ce-Y zeolite. The equilibrium data were fitted to Langmuire and Toth models. Pseudo-n-order and modified n-order models, LDF-base model, and intra-particle diffusion model were evaluated to fit the kinetic of the adsorption process and to determine the mechanism of it. The corresponding parameters and/or correlation coefficients of each model were reported. The LDF-base model was used also to fit the mass transfer coefficient for both powder and pellet forms of the adsorbent. The best fit estimates for the mass transfer coefficient were obtained 4 × 10-11 m/s and k = 3.1 × 10-12[exp( - t/τ) + 1/(t + 10-4)], for powder and pellet form adsorbents, respectively.

  13. Preparation, characterization, and photocatalytic performance of Ce2S3 for nitrobenzene reduction

    Science.gov (United States)

    Chen, Shifu; Zhang, Huaye; Fu, Xianliang; Hu, Yingfei

    2013-06-01

    Ce2S3 photocatalysts were synthesized by a co-precipitation method using cerium nitrate and thioacetamide as raw materials. The samples were characterized by X-ray powder diffraction analysis, UV-visible diffuse reflectance spectroscopy, scanning electron microscopy, and differential thermal analysis. Photocatalytic reduction of nitrobenzene (NB) under UV or visible light illumination was used to evaluate the photocatalytic activity of the Ce2S3 samples. The result indicated that the sample prepared at 300 °C for 12 h exhibited the highest activity. For 140 mL 8.13 × 10-4 mol/L of NB in methanol solvent, after illumination for 5 h, about 43.9% and 34.7% of NB were reduced to aniline over the sample under UV and visible light irradiation, respectively. The effects of the catalyst amount, illumination time, and sorts of solvent on the photocatalytic performance were investigated specifically. The reduction process of NB over Ce2S3 was finally discussed.

  14. Synthesis and characterization of nano-sized YAG∶Ce,Sm spherical phosphors

    Institute of Scientific and Technical Information of China (English)

    SUN Haiying; ZHANG Xiyan; BAI Zhaohui

    2013-01-01

    YAG:Ce,Sm spherical phosphors were synthesized by malic acid sol-gel method.The formation process of crystalline was characterized by X-ray diffraction (XRD) technique.The influence of Sm3+ doping on the luminescent intensity and the morphology of phosphors were studied by fluorescence spectrum and scanning electron microscopy (SEM) techniques,respectively.The results indicated that the size of spherical powders was about 100 nm calcined at 1200 ℃ for 3 h.The emission spectra of phosphors showed gradual red-shift from 525 to 540 nm with the increase of doping concentration of Sm3+ ion.A broadband emission spectrum of Ce3+ ion appeared at 540 nm,and a series of emission peaks corresponding to the 4G5/2→6HJ transition of Sm3+ ion also appeared at 617 nm with the doping of Sm3+.The red component of YAG:Ce phosphors increased with the doping of Sm3+.

  15. Production of hydrogen by partial oxidation of methanol over Au/CeO2, Au-Pd/CeO2 and Pd/CeO2 catalysts%Au/CeO2、Pd/CeO2和Au-Pd/CeO2催化剂甲醇部分氧化制氢性能的研究

    Institute of Scientific and Technical Information of China (English)

    李苑; 罗来涛

    2009-01-01

    采用沉积沉淀法制备了Au/CeO2、Pd/CeO2和Au-Pd/CeO2催化剂,研究了催化剂的甲醇部分氧化制氢性能,并运用XRD、UV-Vis、TPR、H2-TPD和CO-TPD等手段对催化剂进行了表征.结果表明,与Pd/CeO2和Au/CeO2相比,Au-Pd/CeO2双金属催化剂显示出较高的催化活性和较高的氢产率,这是由于Au和Pd的相互作用减少了Pd对反应产物H2的吸附,有利于活性中心再生,且减小了H2的深度氧化,同时Au和Pd相互作用使金粒子较稳定、不易聚集,有利于高温时H2选择性的稳定.

  16. Luminescent properties of Ce3+/Tb3+co-doped glass ceramics containing YPO4 nanocrystals for W-LEDs

    Institute of Scientific and Technical Information of China (English)

    张志雄; 张约品; 冯治刚; 王成; 夏海平; 张新民

    2016-01-01

    Ce3+/Tb3+ co-doped transparent glass ceramics containing YPO4 nanocrystals were prepared using high temperature melt-ing method, and their structural and luminous properties were investigated. XRD analysis and TEM images confirmed the existence of YPO4 nanocrystals in glass ceramics. The transmission spectra proved that the glass ceramics specimens still maintained a high transparency. Then the excitation and emission spectra of the Ce3+ and Tb3+ single-doped and co-doped glass and glass ceramics were discussed, which proved that the glass ceramics had better luminescent properties. Under the near ultraviolet (331 nm) excitation, the broadband emission located at 385 nm was observed which was ascribed to 5d→2F5/2 and2F7/2 transition of Ce3+ ions. Several char-acteristic sharp peaks centered at 489, 543, 578 and 620 nm originated from the5D4 to7FJ (J=6, 5, 4, 3) of Tb3+ ions. The decay time of Tb3+ ions at 543 nm and the relevant energy levels of Ce3+ ions and Tb3+ ions illustrated the transfer process from Ce3+ ions to Tb3+ ions. The best CIE chromaticity coordinate of the glass ceramics specimen was calculated as (x=0.3201,y=0.3749), which was close to the NTSC standard values for white (x=0.333,y=0.333). All the results suggested that the YPO4-based Ce3+/Tb3+ co-doped glass ceramics could act as potential luminescent materials for white light-emitting diodes.

  17. Mechanochemical synthesis of magnetically hard anisotropic RFe10Si2 powders with R representing combinations of Sm, Ce and Zr

    Science.gov (United States)

    Gabay, A. M.; Hadjipanayis, G. C.

    2017-01-01

    Alloy synthesis consisting of mechanical activation followed by annealing was explored as a method of manufacturing medium-grade permanent magnet materials with a reduced content of the critical rare earth elements. Four RxFe10Si2 alloys with R=Sm, Sm0.7Zr0.3, Sm0.3Ce0.3Zr0.4 and Ce0.6Zr0.4 (nominal compositions) were prepared from mixtures of Sm2O3, CeO2, ZrO2, Fe2O3 and Si powders in the presence of a reducing agent Ca and a CaO dispersant. The collected alloy particles typically consisted of few joined submicron crystals. For R=Sm, X-ray diffraction analysis reveals a significant amount of the unwanted Th2Zn17-type compound forming alongside the desired ThMn12-type 1:12 compound. A more pure 1:12 phase could be obtained for R=Ce0.6Zr0.4, but it exhibited a room-temperature coercivity of less than 1 kOe. The most pure 1:12 phase and the highest values of the coercivity (10.8 kOe) and calculated maximum energy product (13.8 MGOe) were obtained for R=Sm0.7Zr0.3 processed at 1150 °C. The calculated maximum energy products of the Sm0.3Ce0.3Zr0.4Fe10Si2 particles, with half of their rare earths constituents represented by the relatively abundant Ce, was 10.1 MGOe.

  18. Optimal Conditions for Preparing Ultra-Fine CeO2 Powders in A Submerged Circulative Impinging Stream Reactor

    Institute of Scientific and Technical Information of China (English)

    Chi Ru'an; Xu Zhigao; Wu Yuanxin; Wang Cunwen

    2007-01-01

    Cerium carbonate powders were produced in a submerged circulation impinging stream reactor (SCISR) from Ce(NO3)3·6H2O. NH4HCO3 was used as a precipitant in the reaction. Cerium carbonate powders were roasted to produce ultra-fine cerium dioxide (CeO2) powders. The optimal conditions of such production process were obtained by orthogonal and one-factor experiments. The results showed that ultra-fine and narrowly distributed cerium carbonate powders were produced under the optimal flowing conditions. The concentrations of Ce(NO3)3 and NH4HCO3 solutions were 0.25 and 0.3 mol·L-1, respectively. The concentration of PEG4000 added in these two solutions was 4 g·L-1. The stirring ratio, reaction temperature, feeding time, solution pH, reaction time and digestion time were 900 r·min-1, 80 ℃, 20 min, 5~6, 5 min and 1 h, respectively. The final product, CeO2 powders, was obtained by roasting the produced cerium carbonate in air for 3 h at 500 ℃. The finally produced CeO2 powders were torispherical particles with a narrow size distribution of 0.8~2.5 μm. The crystal structure of CeO2 powders belonged to cubic crystal system and its space point group was O5H-FM3M. Under optimal conditions, powders produced by SCISR were finer and more narrowly distributed than that by Stirred Tank Reactor (STR).

  19. Near-infrared luminescence of Tm{sup 3+}-doped CeO{sub 2} films based on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Xue; Wang, Shenwei; Li, Ling; Mu, Guangyao; Huang, Miaoling; Yi, Lixin [Beijing Jiaotong University, Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing (China)

    2016-02-15

    CeO{sub 2}/Tm{sub 2}O{sub 3} multilayer films were deposited on silicon substrates by electron-beam evaporation. Tm{sup 3+} ions were doped in CeO{sub 2} after the films were annealed in oxygen atmosphere at 1000 C. The doping concentration of Tm{sup 3+} varies in the range of 0.1-3 mol%. A series of near-infrared emission peaks were observed under the excitation of 330 nm, which correspond to {sup 1}G{sub 4}-{sup 3}H{sub 5}, {sup 3}H{sub 4}-{sup 3}H{sub 6}, {sup 1}G{sub 4}-{sup 3}H{sub 4}, {sup 3}H{sub 5}-{sup 3}H{sub 6}, {sup 3}F{sub 2}-{sup 3}H{sub 5}, {sup 3}H{sub 4}-{sup 3}F{sub 4}, {sup 1}G{sub 4}-{sup 3}F{sub 3,2} and {sup 3}F{sub 4}-{sup 3}H{sub 6} transitions of Tm{sup 3+}, respectively. The dominant transition of {sup 3}H{sub 4}-{sup 3}H{sub 6} near 805 nm was within optical transmission window. The luminescence properties and the crystal structure of CeO{sub 2}:Tm{sup 3+} films were investigated by excitation and emission spectroscopy and X-ray diffraction. Meanwhile, the substitution process of Ce{sup 4+} by Tm{sup 3+} was illustrated, and lattice expansion of the matrix CeO{sub 2} gave rise to the increase in FWHM of CeO{sub 2} diffraction peaks. In addition, the effect of Tm{sup 3+} concentration on photoluminescence was also studied, and the optimal concentration of Tm{sup 3+} was 0.5 mol%. (orig.)

  20. Comparison between the Oxygen Reduction Reaction Activity of Pd5Ce and Pt5Ce

    DEFF Research Database (Denmark)

    Tripkovic, Vladimir; Zheng, Jian; Rizzi, Gian Andrea;

    2015-01-01

    confirmed that in our sample, L-Pd5Ce is the dominant phase, both in the bulk and the outermost layers, while a H-Pd5Ce-like phase is also present as a minor component far below the surface. Electrochemical ORR assessments show that the Pd overlayer in Pd5Ce is less active than the polycrystalline Pd sample...

  1. SELF-ASSEMBLY CE OXIDE/ORGANOPOLYSILOXANE COMPOSITE COATINGS.

    Energy Technology Data Exchange (ETDEWEB)

    SUGAMA,T.; SABATINI,R.; GAWLIK,K.

    2005-01-01

    A self-assembly composite synthesis technology was used to put together a Ce(OH){sub 3}-dispersed poly-acetamide-acetoxyl methyl-propylsiloxane (PAAMPA) organometallic polymer. Three spontaneous reactions were involved; condensation, amidation, and acetoxylation, between the Ce acetate and aminopropylsilane triol (APST) at 150 C. An increase in temperature to 200 C led to the in-situ phase transformation of Ce(OH){sub 3} into Ce{sub 2}O{sub 3} in the PAAMPA matrix. A further increase to 250 C caused oxidative degradation of the PAAMPA, thereby generating copious fissures in the composite. We assessed the potential of Ce(OH){sub 3}/ and Ce{sub 2}O{sub 3}/ PAAMPA composite materials as corrosion-preventing coatings for carbon steel and aluminum. The Ce{sub 2}O{sub 3} composite coating displayed better performance in protecting both metals against NaCl-caused corrosion than did the Ce(OH){sub 3} composite. Using this coating formed at 200 C, we demonstrated that the following four factors played an essential role in further mitigating the corrosion of the metals: First was a minimum susceptibility of coating's surface to moisture; second was an enhanced densification of the coating layer; third was the retardation of the cathodic oxygen reduction reaction at the metal's corrosion sites due to the deposition of Ce{sub 2}O{sub 3} as a passive film over the metal's surface; and, fourth was its good adherence to metals. The last two factors contributed to minimizing the cathodic delamination of coating film from the metal's surface. We also noted that the affinity of the composite with the surface of aluminum was much stronger than that with steel. Correspondingly, the rate of corrosion of aluminum was reduced as much as two orders of magnitude by a nanoscale thick coating. In contrast, its ability to reduce the corrosion rate of steel was lower than one order of magnitude.

  2. Electrochemical and optical properties of CeO2-SnO2 and CeO2-SnO2:X (X = Li, C, Si films

    Directory of Open Access Journals (Sweden)

    Berton Marcos A.C.

    2001-01-01

    Full Text Available Thin solid films of CeO2-SnO2 (17 mol% Sn and CeO2-SnO2:X (X = Li, C and Si were prepared by the sol-gel route, using an aqueous-based process. The addition of Li, C and Si to the precursor solution leads to films with different electrochemical performances. The films were deposited by the dip-coating technique on ITO coated glass (Donnelly Glass at a speed of 10 cm/min and submitted to a final thermal treatment at 450 °C during 10 min in air. The electrochemical and optical properties of the films were determined from the cyclic voltammetry and chronoamperometry measurements using 0.1 M LiOH as supporting electrolyte. The ion storage capacity of the films was investigated using in situ spectroelectrochemical method and during the insertion/extraction process the films remained transparent. The powders were characterized by thermal analysis (DSC/TGA and X-ray diffraction.

  3. LiCe9Mo16O35

    Directory of Open Access Journals (Sweden)

    Patrick Gougeon

    2012-03-01

    Full Text Available The structure of lithium nonacerium hexadecamolybdenum pentatridecaoxide, LiCe9Mo16O35, is isotypic with LiNd9Mo16O35 [Gougeon Gall, Cuny, Gautier, Le Polles, Delevoye & Trebosc (2011. Chem. Eur. J. 17, 13806–13813]. It is characterized by Mo16O26iO10a units (where i = inner and a = apical containing Mo16 clusters that share some of their O atoms to form infinite molybdenum cluster chains running parallel to the b axis and separated by Li+ and Ce3+ cations. The Mo16 cluster units are centred at Wyckoff positions 2c and have point-group symmetry 2/m. The Li+ atom, in a flattened octahedron of O atoms, is in a 2a Wyckoff position with 2/m symmetry. The Ce3+ cations have coordination numbers to the O atoms of 6, 9 or 10. Two Ce, two Mo and five O atoms lie on sites with m symmetry (Wyckoff site 4i, and one Ce and one O atom on sites with 2/m symmetry (Wyckoff sites 2b and 2d, respectively.

  4. Photoemission spectra of CeAl[sub 3], CeBe[sub 13], CeSi[sub 2], and CeCu[sub 2]Si[sub 2]: Weights and widths of the 4[ital f] emission features

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, J.M. (Physics Department, University of California, Irvine, California 92717 (United States)); Arko, A.J.; Joyce, J.J.; Blyth, R.I.R.; Bartlett, R.J.; Canfield, P.C.; Fisk, Z. (Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)); Riseborough, P.S. (Physics Department, Polytechnic University, Brooklyn, New York 11201 (United States))

    1993-06-15

    We present valence-band photoemission spectra for CeAl[sub 3], CeBe[sub 13], CeSi[sub 2], CeCu[sub 2]Si[sub 2], and related conventional rare-earth counterpart compounds, taken at photon energies corresponding to the giant 4[ital d] resonance with resolution [similar to]150 meV. We take into account the 5[ital d] emission, which comprises 30% of the valence-band emission at the 4[ital d] resonance. We compare the resulting 4[ital f] emission to the predictions of the Anderson impurity model calculated in a low-order 1/[ital N] expansion, and including spin-orbit, crystal-field, and finite Coulomb correlation effects. The calculation gives order-of-magnitude fits to the data, but underestimates the spectral weight near the Fermi level by a factor of 2 and overestimates the width of the main [ital f] emission at 2 eV by a factor of 4. We argue that Ce photoemission remains an open problem and discuss several experimental and theoretical issues which need to be resolved to make further progress.

  5. The synthesis of CeO2 nanospheres with different hollowness and size induced by copper doping

    Science.gov (United States)

    Liu, Wei; Liu, Xiufang; Feng, Lijun; Guo, Jinxin; Xie, Anran; Wang, Shuping; Zhang, Jingcai; Yang, Yanzhao

    2014-08-01

    In this paper, copper-doped ceria oxides with different hollowness and size are fabricated by changing the Cu2+ doping concentration in the mixed water-glycol system. Results show that the copper-doped CeO2 oxides undergo a morphology transformation from the solid nanospheres to core-shell, then to hollow nanospheres with the increase of the Cu2+ doping concentration. The corresponding size becomes smaller during this transfer process. The Cu2+ doping induced acceleration in the nucleation and growth process is further investigated. The resultant Cu2+-doped CeO2 oxides exhibit enhanced CO conversion performance and better reduction behaviors.In this paper, copper-doped ceria oxides with different hollowness and size are fabricated by changing the Cu2+ doping concentration in the mixed water-glycol system. Results show that the copper-doped CeO2 oxides undergo a morphology transformation from the solid nanospheres to core-shell, then to hollow nanospheres with the increase of the Cu2+ doping concentration. The corresponding size becomes smaller during this transfer process. The Cu2+ doping induced acceleration in the nucleation and growth process is further investigated. The resultant Cu2+-doped CeO2 oxides exhibit enhanced CO conversion performance and better reduction behaviors. Electronic supplementary information (ESI) available: Fig. S1 the TEM images of the Cu2+-doped CeO2 (a-c): P2, P5 and P6; Fig. S2 EDS spectrum of the Cu2+-doped ceria sample; Fig. S3 the HRTEM images about lattice fringes of the Cu2+-doped CeO2: (a and b) P3; (c and d) P4; Fig. S4 the corresponding XPS survey spectrum of nanospheres: P1 and P4; Fig. S5 XRD pattern of P3 obtained at different solvothermal time, illustrated as (a) 1 h, (b) 2 h, (c) 4 h and (d) 8 h; Fig. S6 the TEM images of (a) the P1 sample at 36 h and (b) the P4 sample at 2 h; Fig. S7 N2 adsorption-desorption isotherms of the pure and Cu2+ doped CeO2: (a) P1, (b) P2, (c) P3, (d) P4, (e) P5 and (f) P6. Insets are the

  6. Magnetic, thermal and electronic properties of Ce{sub 11}Ni{sub 4}In{sub 9} and CeNi{sub 9}In{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Szytuła, A., E-mail: andrzej.szytula@uj.edu.pl [Marian Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Kraków (Poland); Baran, S.; Penc, B. [Marian Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Kraków (Poland); Przewoźnik, J. [Department of Solid State Physics, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków (Poland); Winiarski, A. [August Chełkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Tyvanchuk, Yu.; Kalychak, Ya.M. [Department of Analytical Chemistry, Ivan Franko National University of Lviv, Kyryla and Mephodiya 6, 79005 Lviv (Ukraine)

    2014-03-15

    Highlights: • Basis on the X-ray data the crystal structure of Ce{sub 11}Ni{sub 4}In{sub 9} and CeNi{sub 9}In{sub 2} compounds determined. • In Ce{sub 11}Ni{sub 4}In{sub 9} the Ce magnetic moments order at low temperatures, where in CeNi{sub 9}In{sub 2} not detected localized moment. • Magnetic and specific heat data of Ce{sub 11}Ni{sub 4}In{sub 9} indicate two phase transitions at 5 and 16.5 K. • XPS spectra indicate for both compounds sizable hybridization of the Ce4f electrons with conduction band. • For CeNi{sub 9}In{sub 2} the existence of Ce3d{sup 9}4f{sup 0} configuration indicates the mixed-valence state. -- Abstract: Crystal structure, magnetic, thermal and electronic properties of Ce{sub 11}Ni{sub 4}In{sub 9} and CeNi{sub 9}In{sub 2} compounds were investigated by means of X-ray diffraction, magnetic, calorimetric and X-ray photoelectron spectroscopy measurements. Ce{sub 11}Ni{sub 4}In{sub 9} crystallizes in the orthorhombic Nd{sub 11}Pd{sub 4}In{sub 9}-type structure (space group Cmmm) while CeNi{sub 9}In{sub 2} crystallizes in the YNi{sub 9}In{sub 2}-type structure (space group P4/mbm) (in which Ce atoms occupy only one Wyckoff position). Magnetic and specific heat measurements indicate that in Ce{sub 11}Ni{sub 4}In{sub 9} the Ce magnetic moment orders below 16.5 K, while in CeNi{sub 9}In{sub 2} it does not carry a localized moment. Our data indicate that Ni atoms are likely non-magnetic in both compounds. The XPS spectra of the valence band and the core-level are reported. The contributions to the density of states at E{sub F} are dominated by the Ni3d states. The XPS Ce3d data indicate sizable hybridization of the Ce-4f electrons with conduction band for both compounds. The existence in CeNi{sub 9}In{sub 2} of Ce3d{sup 9}4f{sup 0} configuration indicates a mixed-valence system. The core-level Ni2p{sub 3/2} spectra indicate incomplete Ni3d band filling in this compound.

  7. Influence of growth rate on the epitaxial orientation and crystalline quality of CeO2 thin films grown on Al2O3(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Nandasiri, M. I.; Nachimuthu, P.; Varga, T.; Shutthanandan, V.; Jiang, W.; Kuchibhatla, Satyanarayana V. N. T.; Thevuthasan, S.; Seal, S.; Kayani, A.

    2011-01-01

    Growth rate-induced epitaxial orientations and crystalline quality of CeO2 thin films grown on Al2O3(0001) by oxygen plasma-assisted molecular beam epitaxy were studied using in-situ and ex-situ characterization techniques. CeO2 grows as three-dimensional (3-D) islands and two-dimensional (2-D) layers at growth rates of 1-7 Å/min, and ≥9 Å/min, respectively. The formation of epitaxial CeO2(100) and CeO2(111) thin films occurs at growth rates of 1 Å/min and ≥ 9 Å/min, respectively. Glancing incidence x-ray diffraction (GIXRD) measurements have shown that the films grown at intermediate growth rates (2-7 Å/min) consist of polycrystalline CeO2 along with CeO2(100). The thin film grown at 1 Å/min exhibits six in-plane domains, characteristic of well-aligned CeO2(100) crystallites. The content of the poorly-aligned CeO2(100) crystallites increases with increasing growth rate from 2 Å/min to 7 Å/min, and three out of six in-plane domains gradually decrease and eventually disappear, as confirmed by XRD pole figures. At growth rates ≥9 Å/min, CeO2(111) film with single in-plane domain was identified. The formation of CeO2(100) 3-D islands at growth rates of 1-7 Å/min is a kinetically driven process unlike at growth rates ≥9 Å/min which result in an energetically and thermodynamically more stable CeO2(111) surface.

  8. Mixed cerium-platinum oxides: Electronic structure of [CeO]Ptn (n = 1, 2) and [CeO2]Pt complex anions and neutrals

    Science.gov (United States)

    Ray, Manisha; Kafader, Jared O.; Topolski, Josey E.; Jarrold, Caroline Chick

    2016-07-01

    The electronic structures of several small Ce-Pt oxide complexes were explored using a combination of anion photoelectron (PE) spectroscopy and density functional theory calculations. Pt and Pt2 both accept electron density from CeO diatomic molecules, in which the cerium atom is in a lower-than-bulk oxidation state (+2 versus bulk +4). Neutral [CeO]Pt and [CeO]Pt2 complexes are therefore ionic, with electronic structures described qualitatively as [CeO+2]Pt-2 and [CeO+]Pt2-, respectively. The associated anions are described qualitatively as [CeO+]Pt-2 and [CeO+]Pt2-2, respectively. In both neutrals and anions, the most stable molecular structures determined by calculations feature a distinct CeO moiety, with the positively charged Ce center pointing toward the electron rich Pt or Pt2 moiety. Spectral simulations based on calculated spectroscopic parameters are in fair agreement with the spectra, validating the computationally determined structures. In contrast, when Pt is coupled with CeO2, which has no Ce-localized electrons that can readily be donated to Pt, the anion is described as [CeO2]Pt-. The molecular structure predicted computationally suggests that it is governed by charge-dipole interactions. The neutral [CeO2]Pt complex lacks charge-dipole stabilizing interactions, and is predicted to be structurally very different from the anion, featuring a single Pt-O-Ce bridge bond. The PE spectra of several of the complexes exhibit evidence of photodissociation with Pt- daughter ion formation. The electronic structures of these complexes are related to local interactions in Pt-ceria catalyst-support systems.

  9. Oxygen vacancy and Ce{sup 3+} ion dependent magnetism of monocrystal CeO{sub 2} nanopoles synthesized by a facile hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Leini [School of Physics and Materials Science, Anhui University, Hefei 230039 (China); Anhui Key Laboratory of Information Materials and Devices, Anhui University, Hefei 230039 (China); Meng, Fanming, E-mail: mrmeng@ahu.edu.cn [School of Physics and Materials Science, Anhui University, Hefei 230039 (China); Anhui Key Laboratory of Information Materials and Devices, Anhui University, Hefei 230039 (China); Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024 (China)

    2013-09-01

    Graphical abstract: - Highlights: • Monocrystal CeO{sub 2} nanopoles are synthesized by hydrothermal method. • Suitable reaction time is beneficial for the growth CeO{sub 2} nanopoles. • As-synthesized CeO{sub 2} nanopoles show excellent RTFM. • The RTFM can be attributed to the influences of oxygen vacancies and Ce{sup 3+} ions. - Abstract: Monocrystal CeO{sub 2} nanopoles of 15–25 nm in diameter and 300–900 nm or more in length were synthesized within 100 h using hydrothermal method with CeCl{sub 3}·7H{sub 2}O as cerium source, NaOH as mineralizer, and ethylenediamine as complexant. The results of XRD and SADE analysis indicate that the as-synthesized CeO{sub 2} samples have the fluorite structure. The band gaps of CeO{sub 2} samples are 0.08–0.38 eV smaller than that of bulk CeO{sub 2}. X-ray photoelectron spectroscopy shows that the concentration of Ce{sup 3+} is higher than 20% for CeO{sub 2} samples. All the as-synthesized CeO{sub 2} samples exhibit the room temperature ferromagnetism (RTFM), and the saturation magnetization (M{sub s}) gradually increases with the increase of E{sub g} up to 2.92 eV and then decreases with E{sub g} increasing more. The highest M{sub s} of 0.167 emu/g is obtained from the CeO{sub 2} nanopoles synthesized within 100 h. The RTFM mechanism of CeO{sub 2} nanopoles has been proposed which can be mainly attributed to the influence of oxygen vacancies and Ce{sup 3+} ions.

  10. Transverse wobbling motion in $^{134}$Ce and $^{136}$Nd

    CERN Document Server

    Petrache, C M

    2016-01-01

    The existence of one-phonon and possible two-phonon transverse wobbling bands is proposed for the first time in two even-even nuclei, $^{134}$Ce and $^{136}$Nd. The predominant $E2$ character of the $\\Delta I = 1$ transitions connecting the one-phonon wobbling band in $^{134}$Ce to the two-quasiparticle yrast band supports the wobbling interpretation. The extracted wobbling frequencies decrease with increasing spin, indicating the transverse character of the wobbling motion, with the angular momenta of the two quasiparticles aligned perpendicular to the axis of collective rotation. A candidate for two-phonon wobbling motion is also proposed in $^{136}$Nd. The wobbling frequencies calculated in the harmonic frozen approximation are in good agreement with the experimental ones for both the$^{134}$Ce and $^{136}$Nd nuclei.

  11. Scintillating properties of LiYSiO4:Ce

    Institute of Scientific and Technical Information of China (English)

    FU Zai-Wei; CHEN Xiao-Hui; NING Zhe; HENG Yue-Kun; QI Ming; HUANG Pin-Wen; ZHANG Huai-Jin; WANG Ji-Yang; JIA Ru; QIAN Sen; LI Shao-Li

    2011-01-01

    LiYSiO4:Ce is a promising scintillator and some of its properties have been reported in previous papers.In this paper,samples doped with different concentrations of Ce are prepared and studied.First,the relative light yields of the samples are measured as 28.1%-37.1% compared with a standard anthracene crystal being irradiated by α particles and as ~27.2% compared with NaI being irradiated by X-rays.Second,the effects of sample thicknesses on light yields are presented.Finally the timing behaviors of samples with different doped concentrations being irradiated with alpha particles and X-rays are discussed.The result shows that LiYSiO4:Ce is a kind of fast scintillator (~ 30 ns) with a moderate light yield that can be used for neutron detection.

  12. Beam fanning effect and image storage in Ce: KNSBN crystal

    Institute of Scientific and Technical Information of China (English)

    LI PanLai; GUO QingLin; WANG ZhiJun; PANG LiBin; LIANG BaoLai

    2007-01-01

    A non-synchronously-numerating experimental system is applied in this research. The effect of the incident beam intensity Ⅰ and the beam incident angle θ on beam fanning effect is investigated with a singular beam incident on Ce:KNSBN crystal. The results show that the beam fanning effect strongly depends on Iand θ. The threshold effect of/for the beam fanning in Ce:KNSBN crystal is observed, and the threshold intensity of incident beam keeps the same value of 38.2 mW/cm2 for different θ, and the steady beam fanning intensity Ifsat reaches a peak at θ=15° under the same Ⅰ. In addition, the effect of the incident beam modulated on the beam fanning noise and holographic storage in Ce:KNSBN crystal is studied. And the results suggest that the beam fanning noise is effectively suppressed, and the quality of the reappearance image is greatly improved.

  13. Homoleptic Ce(III) and Ce(IV) Nitroxide Complexes: Significant Stabilization of the 4+ Oxidation State

    Energy Technology Data Exchange (ETDEWEB)

    Bogart, Justin A.; Lewis, Andrew J.; Medling, Scott A.; Piro, Nicholas A.; Carroll, Patrick J.; Booth, Corwin H.; Schelter, Eric J.

    2014-06-25

    Electrochemical experiments performed on the complex Ce-IV[2-((BuNO)-Bu-t)py](4), where [2-((BuNO)-Bu-t)py](-) = N-tert-butyl-N-2-pyridylnitroxide, indicate a 2.51 V stabilization of the 4+ oxidation state of Ce compared to [(Bu4N)-Bu-n](2)[Ce(NO3)(6)] in acetonitrile and a 2.95 V stabilization compared to the standard potential for the ion under aqueous conditions. Density functional theory calculations suggest that this preference for the higher oxidation state is a result of the tetrakis(nitroxide) ligand framework at the Ce cation, which allows for effective electron donation into, and partial covalent overlap with, vacant 4f orbitals with delta symmetry. The results speak to the behavior of CeO2 and related solid solutions in oxygen uptake and transport applications, in particular an inherent local character of bonding that stabilizes the 4+ oxidation state. The results indicate a cerium(IV) complex that has been stabilized to an unprecedented degree through tuning of its ligand-field environment.

  14. Ce Core-Level Spectroscopy, and Magnetic and Electrical Transport Properties of Lightly Ce-Doped YCoO3

    Science.gov (United States)

    Kobayashi, Yoshihiko; Koike, Tsuyoshi; Okawa, Mario; Takayanagi, Ryohei; Takei, Shohei; Minohara, Makoto; Kobayashi, Masaki; Horiba, Koji; Kumigashira, Hiroshi; Yasui, Akira; Ikenaga, Eiji; Saitoh, Tomohiko; Asai, Kichizo

    2016-11-01

    We have investigated the Ce and Co core level spectroscopy, and the magnetic and electrical transport properties of lightly Ce-doped YCoO3. We have successfully synthesized single-phase Y1-xCexCoO3 for 0.0 ≤ x ≤ 0.1 by the sol-gel method. Hard X-ray photoelectron and X-ray absorption spectroscopy experiments reveal that the introduced Ce ions are tetravalent, which is considered to be the first case of electron doping into bulk trivalent Co oxides with perovskite RECoO3 (RE: rare-earth element or Y) caused by RE site substitution. The magnitude of the effective magnetic moment peff obtained from the temperature dependence of magnetic susceptibility χ(T) at higher temperatures is close to that for high-spin Co2+ introduced by the Ce doping, implying that the electrons doped into the Co site induce Co2+ with a high-spin state. For x = 0.1, ferromagnetic ordering is observed below about 7 K. Electrical transport properties such as resistivity and thermoelectric power show that negative electron-like carriers are introduced by Ce substitution.

  15. Fabrication and characterization of spark plasma sintered Ce:LuAG ceramic for scintillation application

    Science.gov (United States)

    Kumar, S. Arun; Senthilselvan, J.

    2016-05-01

    Rare earth Cerium doped Lutetium Aluminum Garnet (Ce:LuAG) ceramics are widely used as phosphor material in medical imaging and high-energy physics. Due to its technological importance, an attempt has been made to fabricate Ce:LuAG ceramics by using spark plasma sintering (SPS) technique. XRD patterns of SPS sintered Ce:LuAG ceramics reveals a mixed LuAG and CeO2 (antisite defect) phases. The microstructures of SPS sintered Ce:LuAG ceramics shows limited densification, inappropriate compaction of particles and existence of residual pores, voids between the grain boundaries affects the transparency of Ce:LuAG ceramics. Relative density and hardness of post sintered Ce:LuAG ceramic is also determined. The effect of Ce3+ doping concentration and sintering temperature on optical luminescence behavior of Ce:LuAG ceramic is presented.

  16. Ce1-xSmxO2-δ-attapulgite nanocomposites:synthesis via simple microwave approach and investigation of its catalytic activity

    Institute of Scientific and Technical Information of China (English)

    李霞章; 胡宗林; 赵晓兵; 陆晓旺

    2013-01-01

    Ce1-xSmxO2-δ-attapulgite (ATP) nanocomposites were successfully prepared via a facile microwave approach. This was a facile and rapid process requiring only low power of microwave irradiation (160 W). The catalytic performance of the Ce1-xSmxO2-δ-ATP nanocomposites with different Sm contents for degradation of methylene blue (MB) was systematically evaluated. The Ce1-xSmxO2-δ-ATP nanocomposites showed enhanced catalytic activities compared with pure CeO2/ATP. Specifically, the cata-lytic activities of Ce1-xSmxO2-δ-ATP nanocomposites increased with increase in Sm content from x=0.0 to 0.3. The introduction of an optimal amount of Sm3+into CeO2 contributed to the formation of structure defects and electronic defects in the oxide lattice, which could increase concentration of oxygen vacancies. However, further increasing Sm content to x=0.4 induced the formation of more agglomerates, leading to decreased catalytic activity. It was believed that this facile, rapid microwave-assisted strategy was scalable and could be applied to synthesize other nanocomposites for different applications.

  17. Effect of Addition of Base on Ceria and Reactivity of CuO/CeO2 Catalysts for Low-Temperature CO Oxidation

    Institute of Scientific and Technical Information of China (English)

    Xiucheng Zheng; Xiaoli Zhang; Shuping Wang; Xiangyu Wang; Shihua Wu

    2007-01-01

    In this work, we have reported the influence of the addition of base (KOH) on the physicochemical property of ceria synthesized by alcohothermal process, and the alcohothermal mechanism was also put forward. Furthermore, the prepared CeO2 was used as the support to prepare CuO/CeO2 catalysts via the wet impregnation method. The samples were characterized by N2 adsorption-desorption, X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM), and temperatureprogrammed reduction by H2 (H2-TPR). The catalytic properties of the CuO/CeO2 catalysts for lowtemperature CO oxidation were studied using a microreactor-GC system. The crystal size of CeO2-A was much smaller than that of CeO2-B, and the corresponding copper oxide catalysts exhibited higher catalytic activity than that of the CeO2-B-supported catalysts under the same reaction conditions. The alcohothermal mechanism indicated that KOH plays a key role in determining the physicochemical and catalytic properties of ceria-based materials.

  18. Yb,Er-doped CeO2 nanotubes as an assistant layer for photoconversion-enhanced dye-sensitized solar cells

    Science.gov (United States)

    Zhao, Rongfang; Huan, Long; Gu, Peng; Guo, Rong; Chen, Ming; Diao, Guowang

    2016-11-01

    Yb,Er-doped CeO2 nanotubes were successfully synthesized using Ag nanowires as a hard template via a facile hydrothermal reaction and subsequent calcination and leaching processes. Yb,Er-doped CeO2 nanotubes as a promising assistant layer were investigated to determine theirs photovoltaic properties in an effort to enhance the power conversion efficiency of dye-sensitized solar cells (DSSCs). The influence factors of photoelectric properties of CeO2:Yb,Er NTs, including diameter of nanotubes, hydrothermal time, calcination temperature, and elements doping, have been studied. Compared with pristine P25 photoanode, the DSSCs fabricated by CeO2:Yb,Er nanotubes and P25 exhibited a power conversion efficiency (η) of 8.67%, an increase of 34%, and incident photo-to-electric conversion efficiency (IPCE) of 92.96%, an increase of 48.83%, which evidence that CeO2:Yb,Er NTs are a promising assistant photoanode material for DSSCs. The enhance mechanism of CeO2:Yb,Er nanotubes has been further revealed according to experimental results.

  19. Temperature Optimized Ammonia and Ethanol Sensing Using Ce Doped Tin Oxide Thin Films in a Novel Flow Metric Gas Sensing Chamber

    Directory of Open Access Journals (Sweden)

    K. Govardhan

    2016-01-01

    Full Text Available A simple process of gas sensing is represented here using Ce doped tin oxide nanomaterial based thin film sensor. A novel flow metric gas chamber has been designed and utilized for gas sensing. Doping plays a vital role in enhancing the sensing properties of nanomaterials. Ce doped tin oxide was prepared by hydrothermal method and the same has been used to fabricate a thin film for sensing. The microstructure and morphology of the prepared materials were analysed by SEM, XRD, and FTIR analysis. The SEM images clearly show that doping can clamp down the growth of the large crystallites and can lead to large agglomeration spheres. Thin film gas sensors were formed from undoped pure SnO2 and Ce doped SnO2. The sensors were exposed to ammonia and ethanol gases. The responses of the sensors to different concentrations (50–500 ppm of ammonia and ethanol at different operating temperatures (225°C–500°C were studied. Results show that a good sensitivity towards ammonia was obtained with Ce doped SnO2 thin film sensor at an optimal operating temperature of 325°C. The Ce doped sensor also showed good selectivity towards ammonia when compared with ethanol. Pure SnO2 showed good sensitivity with ethanol when compared with Ce doped SnO2 thin film sensor. Response time of the sensor and its stability were also studied.

  20. Utilizing peroxide as precursor for the synthesis of CeO{sub 2}/ZnO composite oxide with enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Zijian [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094 (China); Nanjing AIREP Environmental Protection Technology Co., Ltd, Nanjing, Jiangsu 210091 (China); Zhong, Qin, E-mail: zq304@mail.njust.edu.com.cn [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094 (China); Nanjing AIREP Environmental Protection Technology Co., Ltd, Nanjing, Jiangsu 210091 (China); Ou, Man [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094 (China); Nanjing AIREP Environmental Protection Technology Co., Ltd, Nanjing, Jiangsu 210091 (China)

    2016-07-15

    Graphical abstract: - Highlights: • The CeO2/ZnO composite oxide is synthesized with peroxide as a precursor. • The excellent photocatalytic activity is due to the synergistic effect of CeO2 and oxygen vacancy. • The hydroxyl radicals are confirmed to be the dominant active species. - Abstract: A facile synthesis method of CeO{sub 2}/ZnO composite oxides with higher oxygen vacancy concentration was developed by a two-step precipitation method, in which peroxide was used as precursor. The photocatalytic activity of the catalysts under UV irradiation was studied in degradation of methylene blue (MB). All CeO{sub 2}/ZnO photocatalysts exhibited higher photocatalytic performance than pure ZnO, and 1%CeO{sub 2}/ZnO showed highest photocatalytic activity among the prepared catalysts. It was confirmed that the synergistic effect of CeO{sub 2} and oxygen vacancy caused the improved photocatalytic activity. Furthermore, the mechanism was investigated by introducing different additives, and it was found that the hydroxyl radicals played a crucial role in degradation process.

  1. Investigation of surface defect states in CeO{sub 2-y} nanocrystals by Scanning−tunneling microscopy/spectroscopy and ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Radović, Marko; Stojadinović, Bojan; Tomić, Nataša; Golubović, Aleksandar; Dohčević-Mitrović, Zorana, E-mail: zordoh@ipb.ac.rs [Institute of Physics, Pregrevica 118, University of Belgrade, 11 000 Belgrade (Serbia); Matović, Branko [Institute for Nuclear sciences “Vinča,” Materials Science Laboratory, University of Belgrade, 11 000 Belgrade (Serbia); Veljković, Ivana [Institute for Multidisciplinary Research, Kneza Viseslava 1a, University of Belgrade, 11 000 Belgrade (Serbia)

    2014-12-21

    Synthesis process strongly influences the nanocrystalline CeO{sub 2-y} defective structure. The presence of surface defects, in the form of oxygen vacancies in different charge states (F centers), can change the electronic properties of ceria nanocrystals. Nanocrystalline CeO{sub 2-y} samples were synthesized using three different methods (precipitation, self-propagating room temperature, and hydrothermal synthesis). Raman spectroscopy was used to identify the presence of oxygen vacancies which presumably were formed at the nanoparticle surface. The defect concentration depended on the crystallite size of differently prepared CeO{sub 2-y} samples. Scanning tunneling microscopy/spectroscopy and ellipsometry were employed to investigate the electronic band structure of defective CeO{sub 2-y} nanocrystals. Scanning tunneling spectroscopy measurements demonstrated that inside the band gap of CeO{sub 2-y} nanocrystals, besides the filled 4 f states, appeared additional states which were related to occupied and empty F center defect states. From the ellipsometric measurements, using the critical points model, the energy positions of different F centers states and the values of the reduced band gap energies were determined. The analysis of obtained data pointed out that depending on the synthesis method, different types of F centers (F{sup +} and F{sup 0}) can be formed in the CeO{sub 2-y} nanocrystals. The formation of different F center defect states inside the ceria gap have a strong impact on the electrical, optical, and magnetic properties of ceria nanocrystals.

  2. Sensitive redox speciation of neptunium by CE-ICP-MS

    Energy Technology Data Exchange (ETDEWEB)

    Stoebener, Nils; Amayri, Samer; Gehl, Aaron; Kaplan, Ugras; Malecha, Kurtis; Reich, Tobias [Johannes Gutenberg-Universitaet Mainz, Institute of Nuclear Chemistry, Mainz (Germany)

    2012-11-15

    Capillary electrophoresis (CE) was used to separate the neptunium oxidation states Np(IV) and Np(V), which are the only oxidation states of Np that are stable under environmental conditions. The CE setup was coupled to an inductively coupled plasma mass spectrometer (Agilent 7500ce) using a Mira Mist CE nebulizer and a Scott-type spray chamber. The combination of the separation capacity of CE with the detection sensitivity of inductively coupled plasma mass spectrometry (ICP-MS) allows identification and quantification of Np(IV) and Np(V) at the trace levels expected in the far field of a nuclear waste repository. Limits of detection of 1 x 10{sup -9} and 5 x 10{sup -10} mol L{sup -1} for Np(IV) and Np(V), respectively, were achieved, with a linear range from 10{sup -9} to 10{sup -6} mol L{sup -1}. The method was applied to study the redox speciation of the Np remaining in solution after interaction of 5 x 10{sup -7} mol L{sup -1} Np(V) with Opalinus Clay. Under mildly oxidizing conditions, a Np sorption of 31% was found, with all the Np remaining in solution being Np(V). A second sorption experiment performed in the presence of Fe{sup 2+} led to complete sorption of the Np onto the clay. After desorption with HClO{sub 4}, a mixture of Np(IV) and Np(V) was found in solution by CE-ICP-MS, indicating that some of the sorbed Np had been reduced to Np(IV) by Fe{sup 2+}. (orig.)

  3. Eletroforese capilar acoplada à espectrometria de massas (CE-MS: vinte anos de desenvolvimento Capillary electrophoresis coupled to mass spectrometry (CE-MS: twenty years of development

    Directory of Open Access Journals (Sweden)

    Nilson Antonio Assunção

    2008-01-01

    Full Text Available CE-MS has been increasingly used for analysis of a vast array of compounds. This article reviews the different electrophoretic modes, interfaces and mass analyzers that are commonly used in the CE-MS coupling, as well as the technique advantages and performance characteristics. A large compilation of CE-MS applications is also presented. Therefore, this review is both a guide for beginners and a collection of key references for people who are familiar to the technique. Furthermore, this is the first CE-MS review published in a Brazilian journal and marks the installation of the first two commercial CE-MS units in Sao Paulo State.

  4. Pd/CeO2/SiC Chemical Sensors

    Science.gov (United States)

    Lu, Weijie; Collins, W. Eugene

    2005-01-01

    The incorporation of nanostructured interfacial layers of CeO2 has been proposed to enhance the performances of Pd/SiC Schottky diodes used to sense hydrogen and hydrocarbons at high temperatures. If successful, this development could prove beneficial in numerous applications in which there are requirements to sense hydrogen and hydrocarbons at high temperatures: examples include monitoring of exhaust gases from engines and detecting fires. Sensitivity and thermal stability are major considerations affecting the development of high-temperature chemical sensors. In the case of a metal/SiC Schottky diode for a number of metals, the SiC becomes more chemically active in the presence of the thin metal film on the SiC surface at high temperature. This increase in chemical reactivity causes changes in chemical composition and structure of the metal/SiC interface. The practical effect of the changes is to alter the electronic and other properties of the device in such a manner as to degrade its performance as a chemical sensor. To delay or prevent these changes, it is necessary to limit operation to a temperature CeO2 films is based partly on the observation that nanostructured materials in general have potentially useful electrical properties, including an ability to enhance the transfer of electrons. In particular, nanostructured CeO2, that is CeO2 with nanosized grains, has shown promise for incorporation into hightemperature electronic devices. Nanostructured CeO2 films can be formed on SiC and have been shown to exhibit high thermal stability on SiC, characterized by the ability to withstand temperatures somewhat greater than 700 C for limited times. The exchanges of oxygen between CeO2 and SiC prevent the formation of carbon and other chemical species that are unfavorable for operation of a SiC-based Schottky diode as a chemical sensor. Consequently, it is anticipated that in a Pd/CeO2/SiC Schottky diode, the nanostructured interfacial CeO2 layer would contribute to

  5. NMR studies on polyphosphide Ce6Ni6P17

    Science.gov (United States)

    Koyama, T.; Yamada, H.; Ueda, K.; Mito, T.; Aoyama, Y.; Nakano, T.; Takeda, N.

    2016-02-01

    We report the result of 31P nuclear magnetic resonance (NMR) studies on Ce6Ni6P17. The observed NMR spectra show a Lorentzian-type and an asymmetric shapes, reflecting the local symmetry around each P site in the cubic unit cell. We have identified the observed NMR lines corresponding to three inequivalent P sites and deduced the temperature dependence of the Knight shift for each site. The Knight shifts increase with decreasing temperature down to 1.5 K, indicating a localized spin system of Ce6Ni6P17. Antiferromagnetic correlation between 4f spins is suggested from the negative sign of the Weiss-temperature.

  6. Lattice anomalies in CeNi unstable valence compound

    Energy Technology Data Exchange (ETDEWEB)

    Lazukov, V.N.; Nefeodova, E.V.; Alekseev, P.A.; Nemkovski, K.S.; Sadikov, I.P.; Tiden, N.N. [RRC ' ' Kurchatov Institute' ' , 123182 Moscow (Russian Federation); Sikolenko, V.V. [JINR, 141980 Dubna, Moscow region (Russian Federation); Staub, U.; Pradervand, C. [SLS, PSI, 5232 Villigen PSI (Switzerland); Braden, M. [LLB, CEA/Saclay, 91191 Gif sur Yvette Cedex (France); INFP Postfach 3640, 76021 Karlsruhe (Germany); Soderholm, L. [Chemistry Division, Argonne National Laboratory, Argonne Il-60439 (United States)

    2002-07-01

    Neutron diffraction and X-ray absorption measurements have been performed to study the changes in the structure and the Ce valence between 10 K and 295 K. No evidence for a phase transition was obtained, but some nearest-neighbour distances have clear peculiarities in the temperature range of 100 K to 150 K. The valence of Ce increases continuously with decreasing temperature, which can explain neither the lattice anomalies nor the previously observed temperature dependence of the phonon frequencies. A correlation between the gap-like magnetic excitation spectrum formed at low temperatures and observed lattice anomalies is discussed. (orig.)

  7. Conductivity and dielectric studies on LiCeO_2

    Institute of Scientific and Technical Information of China (English)

    M.Prabu; S.Selvasekarapandian; A.R.Kulkarni; G.Hirankumar; C.Sanjeeviraja

    2010-01-01

    LiCeO2 was prepared by a solid-state reaction method using microwave heat treatment and identified by X-ray diffractometry.LiCeO2 has monoclinic crystal structure whose conductivity and dielectric properties were studied over a range of frequency(42 Hz to 1 MHz) and temperatures(30-500 °C) using ac technique of complex impedance analyzer HIOKI 3532.Combined impedance and modulus plots were used as tools to analyze the sample behaviour as a function of frequency at different temperatures.The d.c.conductivity...

  8. Baize-like CeO2 and NiO/CeO2 nanorod catalysts prepared by dealloying for CO oxidation

    Science.gov (United States)

    Zhang, Xiaolong; Li, Kun; Shi, Wenyu; Wei, Caihua; Song, Xiaoping; Yang, Sen; Sun, Zhanbo

    2017-01-01

    Baize-like monolithic CeO2 and NiO/CeO2 nanorod catalysts were prepared by combined dealloying and calcination and the catalytic activities were evaluated using CO catalytic oxidation. The CeO2 catalysts were composed of nanorods and exhibited a three-dimensional supporting structure with pores. After introduction of NiO, dispersed NiO nanosheets and nanoparticles were supported on the surface of CeO2 nanorods and they were not well-crystallined due to CeO2 inhibiting the NiO crystallization. The Raman and x-ray photoelectron spectroscopy analyses revealed that the introduction of NiO species into CeO2 generated more coordinate unsaturated Ni atoms, oxygen vacancies, defects and active sites for CO catalytic reactions. The reaction activation energy of NiO/CeO2 nanorod catalyst prepared from the Al83Ce10Ni7 precursor alloy was just 31.2 kJ mol-1 and the CO conversion can reach up to 97% at 240 °C, which was superior to that of pure CeO2 and nanoporous NiO. The enhanced catalytic activity of baize-like NiO/CeO2 nanorods can be attributed to the strong synergistic effects between finely dispersed NiO species and surface oxygen vacancies in CeO2 nanorods.

  9. Adsorption of Ce(Ⅳ) Anionic Nitrato Complexes onto Anion Exchangers and Its Application for Ce(Ⅳ) Separation from Rare Earths(Ⅲ)

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Ce(Ⅳ) nitrato complexes were adsorbed on two anion exchangers based on polyvinyl pyridine (PVP) and quaternized PVP incorporated into porous silica matrix. The effect of nitric acid concentration (0.5~6 mol·L-1) and temperature (278~318 K) on Ce(Ⅳ) sorption efficiency was investigated. Sorption increased with increasing nitric acid concentration, indicating that [Ce(NO3)6]2- complex is the main adsorbed Ce(Ⅳ) species. Oxidation of sorbents by adsorbed Ce(Ⅳ) species resulting in Ce(Ⅲ) release to the solution was observed. Pyridine based anion exchangers exhibited higher oxidation stability compared to the commercial strong base anion exchanger. Ce(Ⅳ) reduction was temperature dependent and obeyed pseudo-first-order reaction kinetics. Column separation of Ce(Ⅳ) from La(Ⅲ) and Y(Ⅲ) was carried out from 6 mol·L-1 nitric acid with PVP based anion exchanger. Reasonable Ce(Ⅳ) breakthrough capacity (0.7 mol·kg-1 PVP) was achieved. No remarkable decrease of capacity was observed within 3 consequent runs. In contrast, Ce(Ⅲ) leakage due to reduction decreased and breakthrough capacity slightly increased. This effect was more pronounced with increasing temperature. Regeneration with 0.1 mol·L-1 nitric acid was successful (recovery 100%±4%) and Ce solution of high purity (>99.97%) with respect to La and Y content was gained.

  10. An ion-imprinted functionalized SBA-15 adsorbent synthesized by surface imprinting technique via reversible addition-fragmentation chain transfer polymerization for selective removal of Ce(III) from aqueous solution.

    Science.gov (United States)

    Meng, Minjia; Meng, Xiangguo; Liu, Yan; Liu, Zhanchao; Han, Juan; Wang, Yun; Luo, Min; Chen, Rui; Ni, Liang; Yan, Yongsheng

    2014-08-15

    A novel Ce(III) ion-imprinted polymer (Ce(III)-IIP) has been prepared by surface imprinting technique with reversible addition-fragmentation chain transfer (RAFT) polymerization based on support matrix of SBA-15. The prepared adsorbent is characterized by FT-IR, XRD, SEM, TEM, nitrogen adsorption-desorption, GPC, and TGA. The results suggest that the surface imprinted polymer synthesized by RAFT is a thin layer. For adsorption experiments, Ce(III)-IIP is investigated to remove Ce(III) by column study at different flow rates, initial metal ion concentrations, and adsorption temperature. The dynamic kinetics analyses reveal that the overall adsorption process is successfully fitted with the pseudo-first-order kinetic model and the equilibrium time was 60 min. Meanwhile, the experimental data is in good agreement with Thomas model. Ce(III)-IIP has the excellent selectivity and regenerate property. Meanwhile, the proposed method has been successfully applied in the removal of Ce(III) in natural water samples with satisfactory results. All the results suggest that Ce(III)-IIP could be used as an excellent adsorbent for efficient removal of Ce(III) from aqueous solution.

  11. Controlled synthesis of Ce(OH)CO3 flowers by a hydrothermal method and their thermal conversion to CeO2 flowers

    Institute of Scientific and Technical Information of China (English)

    Dongen Zhang; Feng Li; Jian Gu; Qing Xie; Shanzhong Li; Xiaobo Zhang; Guiquan Han; Ailing Ying; Zhiwei Tong

    2012-01-01

    Highly uniform Ce(OH)CO3 flowers were successfully prepared in large quantities using a facile hydrothermal approach from the reaction of Ce(NH4)(NO3)4 with CO(NH2)2 at 160 ℃ in a water-N2H4 complex,The influences of the N2H4 content and temperature on flower formation were discussed.CeO2 flowers were prepared by thermal conversion of Ce(OH)CO3 flowers at 500 ℃ in air.Both Ce(OH)CO3 and CeO2 flowers were characterized by X-ray powder diffraction (XRD),and scanning electron microscopy (SEM),The UV-vis adsorption spectrum of the CeO2 flowers showed that the band gap energy (Eg) is 2.66 eV,which is lower than that of bulk ceria.

  12. Insight on the glass-forming ability of Al–Y–Ni–Ce bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shih-Fan, E-mail: sfchen@ntut.edu.tw [Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei 106, Taiwan (China); Chen, Chih-Yuan, E-mail: chen6563@gmail.com [Department of Energy Engineering, National United University, Miaoli 36003, Taiwan (China); Lin, Chia-Hung [Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei 106, Taiwan (China)

    2015-07-15

    Highlights: • Adding 1 at.% cerium to Al{sub 87}Y{sub 8}Ni{sub 5} alloy causes glass transition. • A large ΔT{sub x} indicates that (Al{sub 87}Y{sub 8}Ni{sub 5}){sub 99}Ce{sub 1} is possibly a ductile amorphous alloy. • Ce is effective in improving the thermal stability of the Al–Y–Ni amorphous alloy. • The hardness of the crystallized cerium-bearing alloy was as high as 593 Hv. - Abstract: In the present study, the role of Ce in the thermal stability and glass forming ability (GFA) of (Al{sub 87}Y{sub 8}Ni{sub 5}){sub 99}Ce{sub 1} alloy ribbons produced by a single roller melt-spinning process has been investigated in an attempt to understand the influences of multiple RE elements in an Al–TM–RE (TM: transition metal, RE: rear earth metal) alloy system. Only the (Al{sub 87}Y{sub 8}Ni{sub 5}){sub 99}Ce{sub 1} alloy ribbon showed a glass transition temperature (T{sub g}) at 483.2 K, and its ΔT{sub x} value was 41.3 K. Crystallization occurred in the temperature range of 500–750 K in three exothermic reaction stages. The peak temperature for these reactions shifted toward higher temperatures at higher heating rates. XRD and SEM analysis of annealed samples revealed that nano-sized Al particles precipitated within the amorphous matrix during the first exothermic reaction. The maximum hardness was obtained for both non-cerium and cerium addition alloys after crystallization in the 550–660 K region due to numerous nano-sized precipitates randomly and homogeneously distributed in the amorphous matrix. Moreover, from observation of the fracture surface, it is found that the fracture mode transforms from ductile to brittle when the sample is annealed at a higher crystallization temperature, at which brittle intermetallic compounds appear.

  13. High performance of NO oxidation over Ce-Co-Ti catalyst: The interaction between Ce and Co

    Science.gov (United States)

    Shang, Danhong; Zhong, Qin; Cai, Wei

    2015-01-01

    Ce0.2Co0.2Ti mixed oxide catalyst was synthesized by a facile sol-gel method and the catalytic activity was evaluated through NO oxidation. The catalyst was characterized by XRD, Raman, TEM, H2-TPR, O2-TPD and XPS. The results showed that Ce0.2Co0.2Ti exhibited high catalytic activity of NO oxidation with maximum conversion of 76% at 300 °C under the condition of 400 ppm NO, 8% O2 and 30 000 h-1 GHSV. The high activity was ascribed to the strong interaction between Ce and Co, which resulted in small particle, excellent redox and large amount of chemisorbed oxygen. These features were favorable for the high catalytic performance of NO oxidation.

  14. Synthesis of the Nanotublar Cubic Fluorite CeO2%纳米管状结构立方萤石型CeO2的合成

    Institute of Scientific and Technical Information of China (English)

    杨儒; 郭亮

    2004-01-01

    低温水热条件下,Ce4+离子经尿素水解均匀沉淀,在十八胺分子模板导向下形成了多层有序排列的纳米管状结构的立方萤石型CeO2,采用粉末X射线衍射(PXRD)、透射电镜(TEM)、高分辨透射电镜(HRTEM)以及选区电子衍射(SEAD)等手段对产物进行了表征.结果表明,该结构是由单根外、内径分别为10~20 nm、5~6 am左右的纳米管有序排列形成的纳米管束构成,且产物具有结晶性良好的立方萤石型CeO2晶体结构.在管束的生长过程中,反应体系首先形成单根纳米管,继而管与管之间又相互缔合生长成多层有序排列的纳米管束.控制尿素的水解,获得了不同pH值下的反应产物,发现反应体系pH值在5~6之间时产物为立方萤石型CeO2、6~8时为立方萤石型CeO2与六方型Ce(OH)CO3的混合物、大于8则为六方型Ce(OH)CO3.%Under hydrothermal condition,nitrate cerium(IV) was used as a cerium source,octadecylamine (C18H37NH2)as the molecular template and urea as a precipitating agent, and the hierarchically well-aligned nanotublar bunches of the cubic fluorite ceria were successfully synthesized.The materials have been characterized by Powder X-ray diffraction (PXRD),transmission electron microscopy (TEM),high-resolution transmission electron microscopy (HRTEM)and the selected area electron diffraction (SAED).The products exhibited the hierarchically well-aligned nanotublar bunch which was composed of single nanotube with outer and inner diameter 10~20 and 5~6 nm. The growth process of nanotublar hunches was monitored.Firstly, the separated nanotube appeared in the reaction system. Subsequently, the separated nanotubes integrated into the hierarchically well-aligned nanotublar bunch each other. In addition, the products have different crystalline phase and composition ad increasing the final pH value of reaction system; And when the final pH values of reaction system were at 5~6,6~8 and >8 respectively, the

  15. Light-induced scattering of light in NBS:Ce crystals

    Science.gov (United States)

    Voronov, V. V.; Dorosh, I. R.; Kuzminov, Iu. S.; Tkachenko, N. V.

    1980-11-01

    An experiment is described in which light-induced scattering of laser light was observed in Ce-doped (Sr/x/Ba/1-x/)/1-y/(Nb2O6)/y/ crystals with x = 0.61 and y = 0.4993. It is shown that the observed effect results from the holographic amplification of light scattered by crystal defects and that the observed asymmetry of the scattering is associated with the diffusion mechanism of hologram recording in crystals. A theoretical model of the scattering process is constructed for the diffusion recording mechanism.

  16. GISAXS study of temperature evolution in nanostructured CeVO{sub 4} films

    Energy Technology Data Exchange (ETDEWEB)

    Turkovic, Aleksandra; Dubcek, Pavo [Ruder Boskovic Institute, PO Box 180, HR-10002 Zagreb (Croatia); Orel, Bojan [Faculty of Computer and Information Science, University of Ljubljana, Trzaska Cesta 25, SI-1001 Ljubljana (Slovenia); Lucic-Lavcevic, Magdy [Department of Physics, Faculty of Chemical Technology, Teslina 10, 21000 Split (Croatia); Orel, Zorica Crnjak [National Institute of Chemistry, Hajdrihova 19, PO Box 3430, SI-1001 Ljubljana (Slovenia); Bernstorff, Sigrid [Sincrotrone Trieste, ss. 14, km 163, 5 Basovizza, 34012 Trieste (Italy)

    2007-09-06

    Cerium vanadate films on glass substrate were obtained by sol-gel process. The morphology of these nanostructured and porous films was studied by grazing-incidence small-angle X-ray scattering (GISAXS) at synchrotron ELETTRA, Trieste, Italy. The aim of the GISAXS study was to investigate the changes in grain sizes due to the temperature evolution with three different time intervals (5, 15 and 30 min) of annealing at 673 K. We found that the effects of the different times of annealing are different for surface and bulk properties of this V/Ce oxide. (author)

  17. GISAXS View of Induced Morphological Changes in Nanostructured CeVO4 Thin Films

    Directory of Open Access Journals (Sweden)

    Magdy Lučić Lavčević

    2011-01-01

    Full Text Available Nanostructured CeVO4 films, designed for applications in electrochemical cells and electrochromic devices, were obtained on glass substrates by the sol-gel process. An analysis of morphological modifications in these films, induced by ultrasonication, annealing, and introduction of lithium ions, was performed, using the grazing-incidence small-angle X-ray scattering technique (GISAXS. The GISAXS results are discussed and related with complementary examinations of the same films in real space, performed by scanning electron microscopy on a different length scale.

  18. Tidal Streams in Newly Discovered compact elliptical (cE) galaxies

    CERN Document Server

    Huxor, Avon; Price, James; Harniman, Rob

    2010-01-01

    We present two newly-discovered, compact elliptical (cE) galaxies, which exhibit clear evidence of tidal steams, found in a search of SDSS DR7. The structural parameters of the cEs are derived using GALFIT and give effective radii < 400 pc. They also possess young to intermediate-age stellar populations. These two cEs provide direct evidence, a "smoking gun", for the process of tidal stripping that is believed to be the origin of M32-type galaxies. Both are found in small group environments with many late-type galaxies, suggesting that we may be seeing the formation of such galaxies in dynamically young galaxy groups.

  19. Structural and growth aspects of electron beam physical vapor deposited NiO-CeO{sub 2} nanocomposite films

    Energy Technology Data Exchange (ETDEWEB)

    Kuanr, Sushil Kumar; K, Suresh Babu, E-mail: sureshbabu.nst@pondiuni.edu.in [Centre for Nanoscience and Technology, Madanjeet School of Green Energy Technologies, Pondicherry University, Puducherry 605 014 (India)

    2016-03-15

    Deposition of composite materials as thin film by electron beam physical vapor deposition technique (EB-PVD) still remains as a challenge. Here, the authors report the deposition of NiO-CeO{sub 2} (30/70 wt. %) composites on quartz substrate by EB-PVD. Two NiO-CeO{sub 2} nanocomposite targets—one as green compact and the other after sintering at 1250 °C—were used for the deposition. Though the targets varied with respect to physical properties such as crystallite size (11–45 nm) and relative density (44% and 96%), the resultant thin films exhibited a mean crystallite size in the range of 20–25 nm underlining the role of physical nature of deposition. In spite of the crystalline nature of the targets and similar elemental concentration, a transformation from amorphous to crystalline structure was observed in thin films on using sintered target. Postannealing of the as deposited film at 800 °C resulted in a polycrystalline structure consisting of CeO{sub 2} and NiO. Deposition using pure CeO{sub 2} or NiO as target resulted in the preferential orientation toward (111) and (200) planes, respectively, showing the influence of adatoms on the evaporation and growth process of NiO-CeO{sub 2} composite. The results demonstrate the influence of electron beam gun power on the adatom energy for the growth process of composite oxide thin films.

  20. Qu’est-ce que le naturalisme ?

    Directory of Open Access Journals (Sweden)

    Olivier Morin

    2012-01-01

    Full Text Available Cet article répond aux critiques récemment adressées aux tenants du « naturalisme social » dans les pages de la revue SociologieS. Il le fait en défendant un naturalisme minimal, bâti sur trois idées : l’interdisciplinarité est permise ; la pensée est un processus causal qui a lieu dans un monde matériel ; l’humanité est une espèce animale. Ces idées pourront sembler triviales ; le débat auquel nous assistons montre qu’il n’en est rien. Je passerai en revue les arguments les plus fréquemment opposés à ce naturalisme. Le dialogue entre sciences cognitives et sciences sociales ne prélude pas à une O.P.A. de la neurobiologie sur les autres disciplines. Aucun chercheur sérieux ne voit la cognition humaine comme un assemblage de modules à l’architecture entièrement fixée dès la naissance et incapables d’interagir avec leur environnement. Le fait que les processus mentaux n’aient pas lieu uniquement dans nos têtes est aujourd’hui un lieu commun des sciences cognitives. Enfin, l’étude de l’évolution de l’humanité, vue comme une espèce biologique, est porteuse de conclusions qui pour être très générales, n’en sont pas moins pertinentes pour les sciences sociales.What is Naturalism?This article responds to recent critics addressed to the advocates of « social naturalism » in the journal SociologieS. It does so by defending a minimal naturalism structured around three ideas: interdisciplinarity is allowed; thought is a causal process that occurs in a material world; humanity is a species. These ideas may seem trivial; the debate we’re assisting to shows us otherwise. I will go through the arguments that most frequently oppose naturalism. The dialogue between cognitive and social sciences is not a prelude to the takeover of neurobiology on other disciplines. No serious researcher sees human cognition as an assembly of architectural modules entirely fixed from birth and incapable of

  1. The observation of scintillation in a hydrated inorganic compound: CeCl3 6H2O

    Energy Technology Data Exchange (ETDEWEB)

    Boatner, Lynn A [ORNL; Neal, John S [ORNL; Ramey, Joanne Oxendine [ORNL; Chakoumakos, Bryan C [ORNL; Custelcean, Radu [ORNL

    2013-01-01

    We have recently reported the discovery of a new family of rare-earth metal-organic single-crystal scintillators based on Ce3+ as the activator ion. Starting with the CeCl3(CH3OH)4 prototype, this family of scintillators has recently been extended to include complex metal-organic adducts produced by reacting CeCl3 with heavier organics (e.g., isomers of propanol and butanol). Some of these new rare-earth metal-organic materials incorporated waters of hydration in their structures, and the observation of scintillation in these hydrated compounds was an original finding for any solid scintillator. In the present work, we now report what is apparently the initial observation of gamma-ray-excited scintillation in an inorganic hydrated material, namely single-crystal monoclinic CeCl3 6H2O. This observation shows that the mechanisms of the various scintillation energy-transfer processes are not blocked by the presence of waters of hydration in an inorganic material and that the observation of scintillation in other hydrated inorganic compounds is not precluded.

  2. Myotubularin family phosphatase ceMTM3 is required for muscle maintenance by preventing excessive autophagy in Caenorhabditis elegans

    Directory of Open Access Journals (Sweden)

    Yu Xiaokun

    2012-10-01

    Full Text Available Abstract Background Autophagy is a ubiquitous cellular process responsible for the bulk degradation of cytoplasmic components through the autophagosomal-lysosomal pathway. In skeletal muscle, autophagy has been regarded as a key regulator for muscle mass maintenance, and its imbalance leads to sarcopenia. However, the underlying mechanism is poorly understood. Results In this study, we demonstrate that ceMTM3, a FYVE-domain containing myotubalarin family phosphatase, is required for the maintenance of muscle fibers by preventing excessive autophagy in Caenorhabditis elegans. Knockdown of ceMTM3 by using feeding-based RNA interference caused loss of muscle fibers accompanied by shortening of muscle cell and body size in aged C. elegans worms. This was preceded by the occurrence of excessive autophagy in the muscle and other tissues, which subsequently resulted in increased lysosomal activity and necrotic cell death. However, knockdown of ceMTM3 did not aggravate the abnormalities of muscle wasting in autophagy-deficient atg-18 mutant worms. Conclusions Our data suggest an important role of ceMTM3 in regulating autophagy and maintaining muscle fibers. This study may have clinical implications for prevention and treatment of sarcopenia.

  3. Site-preference and valency for rare-earth sites in (R-Ce)(2)Fe14B magnets

    Energy Technology Data Exchange (ETDEWEB)

    Alam, A; Khan, M; McCallum, RW; Johnson, DD

    2013-01-28

    Rare-earth (R) permanent magnets of R2Fe14B have technological importance due to their high energy products, and they have two R-sites (Wyckoff 4f and 4g, with four-fold multiplicity) that affect chemistry and valence. Designing magnetic behavior and stability via alloying is technologically relevant to reduce critical (expensive) R-content while retaining key properties; cerium, an abundant (cheap) R-element, offers this potential. We calculate magnetic properties and Ce site preference in (R1-xCex)(2)Fe14B [R = La, Nd] using density functional theory (DFT) methods-including a DFT+U scheme to treat localized 4f-electrons. Fe moments compare well with neutron data-almost unaffected by Hubbard U, and weakly affected by spin-orbit coupling. In La2Fe14B, Ce alloys for 0 <= x <= 1 and prefers smaller R(4f) sites, as observed, a trend we find unaffected by valence. Whereas, in Nd2Fe14B, Ce is predicted to have limited alloying (x <= 0.3) with a preference for larger R(4g) sites, resulting in weak partial ordering and segregation. The Curie temperatures versus x for (Nd, Ce) were predicted for a typical sample processing and verified experimentally. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4789527

  4. Site-preference and valency for rare-earth sites in (R-Ce)2Fe14B magnets

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Aftab [Ames Laboratory; Khan, Mahmud [Ames Laboratory; McCallum, R. W. [Ames Laboratory; Johnson, Duane D [Ames Laboratory

    2013-01-28

    Rare-earth (R) permanent magnets of R2Fe14B have technological importance due to their high energy products, and they have two R-sites (Wyckoff 4f and 4g, with four-fold multiplicity) that affect chemistry and valence. Designing magnetic behavior and stability via alloying is technologically relevant to reduce critical (expensive) R-content while retaining key properties; cerium, an abundant (cheap) R-element, offers this potential. We calculate magnetic properties and Ce site preference in (R1-xCex)2Fe14B [R=La,Nd] using density functional theory (DFT) methods—including a DFT+U scheme to treat localized 4f-electrons. Fe moments compare well with neutron data—almost unaffected by Hubbard U, and weakly affected by spin-orbit coupling. In La2Fe14B, Ce alloys for 0 ≤ x ≤ 1 and prefers smaller R(4f) sites, as observed, a trend we find unaffected by valence. Whereas, in Nd2Fe14B, Ce is predicted to have limited alloying (x ≤ 0.3) with a preference for larger R(4g) sites, resulting in weak partial ordering and segregation. The Curie temperatures versus x for (Nd,Ce) were predicted for a typical sample processing and verified experimentally.

  5. CO oxidation on CuO/CeO{sub 2} catalyst prepared by solvothermal synthesis: influence of catalyst activation temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Yuling; Mao, Dongsen, E-mail: dsmao@sit.edu.cn; Sun, Shuaishuai; Fu, Guangying [Shanghai Institute of Technology, Research Institute of Applied Catalysis, School of Chemical and Environmental Engineering (China)

    2015-12-15

    A series of CuO/CeO{sub 2} catalysts were prepared using a solvothermal method and a subsequent activation process. The influences of activation temperature (300–600 °C) on physicochemical properties and catalytic behavior of the prepared CuO/CeO{sub 2} catalysts have been investigated by XRD, SEM, Raman spectroscopy, S{sub BET} measurement, XPS surface analysis, H{sub 2}-TPR, CO-TPD techniques, and CO oxidation testing. The catalyst activated at 450 °C was found to have the highest catalytic activity, which can be ascribed to its higher dispersion of Cu species, higher concentration of oxygen vacancies, and larger amount of more active lattice oxygen. The lower activity of the CuO/CeO{sub 2} catalysts activated at lower (<450 °C) and higher (>450 °C) temperatures are attributed to the weaker interaction between CuO and CeO{sub 2}, and to the sintering of CuO nanoparticles, respectively.

  6. Comparison of the effects of platinum and CeO2 on the properties of single grain, Sm-Ba-Cu-O bulk superconductors

    Science.gov (United States)

    Zhao, Wen; Shi, Yunhua; Radušovská, Monika; Dennis, Anthony R.; Durrell, John H.; Diko, Pavel; Cardwell, David A.

    2016-12-01

    SmBa2Cu3O7-δ (Sm-123) is a light-rare-earth barium-cuprate (LRE-BCO) high-temperature superconductor (HTS) with significant potential for high field industrial applications. We report the fabrication of large, single grain bulk [Sm-Ba-Cu-O (SmBCO)] superconductors containing 1 wt% CeO2 and 0.1 wt% Pt using a top-seeded melt growth process. The performance of the SmBCO bulk superconductors containing the different dopants was evaluated based on an analysis of their superconducting properties, including critical transition temperature, T c and critical current density, J c , and on sample microstructure. We find that both CeO2 and Pt dopants refine the size of Sm2BaCuO5 (Sm-211) particles trapped in the Sm-123 superconducting phase matrix, which act as effective flux pinning centres, although the addition of CeO2 results in broadly improved superconducting performance of the fully processed bulk single grain. However, 1 wt% CeO2 is significantly cheaper than 0.1 wt% Pt, which has clear economic benefits for use in medium to large scale production processes for these technologically important materials. Finally, the use of CeO2 results generally in the formation of finer Sm-211 particles and to the generation of fewer macro-cracks and Sm-211 free regions in the sample microstructure.

  7. Structural characterization of nanosized CeO(2)-SiO(2), CeO(2)-TiO(2), and CeO(2)-ZrO(2) catalysts by XRD, Raman, and HREM techniques.

    Science.gov (United States)

    Reddy, Benjaram M; Khan, Ataullah; Lakshmanan, Pandian; Aouine, Mimoun; Loridant, Stéphane; Volta, Jean-Claude

    2005-03-03

    Structural characteristics of nanosized ceria-silica, ceria-titania, and ceria-zirconia mixed oxide catalysts have been investigated using X-ray diffraction (XRD), Raman spectroscopy, BET surface area, thermogravimetry, and high-resolution transmission electron microscopy (HREM). The effect of support oxides on the crystal modification of ceria cubic lattice was mainly focused. The investigated oxides were obtained by soft chemical routes with ultrahighly dilute solutions and were subjected to thermal treatments from 773 to 1073 K. The XRD results suggest that the CeO(2)-SiO(2) sample primarily consists of nanocrystalline CeO(2) on the amorphous SiO(2) surface. Both crystalline CeO(2) and TiO(2) anatase phases were noted in the case of CeO(2)-TiO(2) sample. Formation of cubic Ce(0.75)Zr(0.25)O(2) and Ce(0.6)Zr(0.4)O(2) (at 1073 K) were observed in the case of the CeO(2)-ZrO(2) sample. Raman measurements disclose the fluorite structure of ceria and the presence of oxygen vacancies/Ce(3+). The HREM results reveal well-dispersed CeO(2) nanocrystals over the amorphous SiO(2) matrix in the cases of CeO(2)-SiO(2), isolated CeO(2), and TiO(2) (anatase) nanocrystals, some overlapping regions in the case of CeO(2)-TiO(2), and nanosized CeO(2) and Ce-Zr oxides in the case of CeO(2)-ZrO(2) sample. The exact structural features of these crystals as determined by digital diffraction analysis of HREM experimental images reveal that the CeO(2) is mainly in cubic fluorite geometry. The oxygen storage capacity (OSC) as determined by thermogravimetry reveals that the OSC of the mixed oxide systems is more than that of pure CeO(2) and is system dependent.

  8. Tunable multicolor and white luminescence in Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+} doped CePO{sub 4} via energy transfer

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Zhigao [School of Materials Science and Engineering, Key Laboratory of Low-dimensional Materials and Application Technology (Ministry of Education), Xiangtan University, Xiangtan 411105 (China); Lu, Wei [University Research Facility in Materials Characterization and Device Fabrication, The Hong Kong Polytechnic University (Hong Kong); Zeng, Songjun, E-mail: songjunz@hunnu.edu.cn [College of Physics and Information Science and Key Laboratory of Low-dimensional Quantum Structures and Quantum Control of the Ministry of Education, Hunan Normal University, Changsha 410081, Hunan (China); Wang, Haibo; Rao, Ling [School of Materials Science and Engineering, Key Laboratory of Low-dimensional Materials and Application Technology (Ministry of Education), Xiangtan University, Xiangtan 411105 (China); Li, Zheng, E-mail: lizheng@xtu.edu.cn [School of Materials Science and Engineering, Key Laboratory of Low-dimensional Materials and Application Technology (Ministry of Education), Xiangtan University, Xiangtan 411105 (China)

    2015-07-15

    Highlights: • Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+} doped CePO{sub 4} DCNPs were prepared by a one-pot hydrothermal process. • The PL properties and the ET mechanism of these DCNPs were investigated in detail. • These DCNPs exhibit tunable multi-color output under UV excitation. • Intense white emissions can be realized by singly doping Dy{sup 3+} and Mn{sup 2+} in CePO{sub 4} host. - Abstract: In this paper, a series of Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+} doped CePO{sub 4} downconversion nanophosphors (DCNPs) were prepared by a one-pot hydrothermal process. The obtained DCNPs presented monoclinic and hexagonal phase structure with wire-like shape. The photoluminescence (PL) properties and the energy transfer (ET) mechanism of these DCNPs were investigated in detail. The ET mechanism of Ce{sup 3+}/Tb{sup 3+} in CePO{sub 4} host was calculated by means of concentration quenching and spectral overlapping, and calculation results revealed that dipole–dipole interactions should be more responsible. The maximum value of ET efficiency was measured to 87.4% for Tb{sup 3+} doped CePO{sub 4} system. In addition, owing to the efficient ET between Ce{sup 3+} and Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+}, these as-prepared DCNPs exhibit tunable multi-color output under ultra-violet (UV) light excitation. More importantly, the intense cold and warm white emissions can be realized by singly doping 2%Dy{sup 3+} and 20%Mn{sup 2+} in CePO{sub 4} host under UV irradiation, respectively. The corresponding CIE 1931 coordinates were calculated to be (0.30, 0.30) and (0.30, 0.32), respectively, which are closed to the standard white emission (0.33, 0.33). These findings demonstrate the efficient white light emission by singly doped Dy{sup 3+} or Mn{sup 2+} in CePO{sub 4} system for the first time, which is different from commonly used co-doped or tri-doped system. The multicolor tuning and white emission make these Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+} doped CePO{sub 4} DCNPs potential phosphors in

  9. Phase Equilibria of the Ce-Mg-Zn Ternary System at 300 °C

    Directory of Open Access Journals (Sweden)

    Ahmad Mostafa

    2014-05-01

    Full Text Available The isothermal section of the Ce-Mg-Zn system at 300 °C was experimentally established in the full composition range via diffusion multiple/couples and key alloys. Annealed key alloys were used to confirm the phase equilibria obtained by diffusion multiple/couples and to determine the solid solubility ranges. Spot analysis was carried out, using wavelength dispersive X-ray spectroscopy (WDS, to identify the composition of the observed phases. The composition profiles were obtained using WDS line-scans across the diffusion zones. X-ray diffraction (XRD was performed to identify the phases in the annealed alloys and to confirm the WDS results. Eight ternary compounds, in the Ce-Mg-Zn isothermal section at 300 °C, were observed from 45–80 at.% Zn. These are: τ1 (Ce6Mg3Zn19, τ2 (CeMg29Zn25, τ3 (Ce2Mg3Zn3, τ4 (CeMg3Zn5, τ5 (CeMg7Zn12, τ6 (CeMg2.3−xZn12.8+x; 0 ≤ x ≤ 1.1, τ7 (CeMgZn4 and τ8 (Ce(Mg1−yZny11; 0.096 ≤ y ≤ 0.43. The ternary solubility of Zn in the Ce-Mg compounds was found to increase with a decrease in Mg concentration. Accordingly, the ternary solid solubility of Zn in CeMg12 and CeMg3 was measured as 5.6 and 28.4 at.% Zn, respectively. Furthermore, the CeMg and CeZn showed a complete solid solubility. The complete solubility was confirmed by a diffusion couple made from alloys containing CeMg and CeZn compounds.

  10. Magnetic Phase Transitions of CeSb. I

    DEFF Research Database (Denmark)

    Fischer, Pernille Hertz; Lebech, Bente; Meier, G.;

    1978-01-01

    The magnetic ordering of the anomalous antiferromagnet CeSb, which has a NaCl crystal structure, was determined in zero applied magnetic field by means of neutron diffraction investigations of single crystals and powder. Below the Neel temperature TN of (16.1+or-0.1)K, there exist six partially...

  11. Estimation of bulk transfer coefficient for latent heat flux (Ce)

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.

    specific humidity at sea surface tempera- ture, qn is the specific humidity at deck level, and U is the wind speed at the height of anemometer. All the available data in each area and along the boundaries are used to compute E. NFD and Ce. 3. Results...

  12. Solid Electrolyte Based on Perovskite-type BaCeO3 and SrCeO3%BaCeO3和SrCeO3基钙钛矿型固体电解质

    Institute of Scientific and Technical Information of China (English)

    张俊英; 张中太

    2000-01-01

    综述了BaCeO3基和SrCeO3基钙钛矿型固体电解质.从结构、不同气氛中导电性方面进行了介绍,对其应用方面进行了较为详细的分析.在燃料电池、电解池、薄膜反应器、气体传感器等方面的应用分析表明这2类固体电解质有广泛的应用前景.%Solid electrolyte based on perovskite-type BaCeO3 and SrCeO3 was reviewed .Microstructure and conductivity in different atmosphere were introduced while application was analyzed in detail. Applications in fuel cell, steam electrolysis cell, membrane reactor, gas sensor indicate that these kinds of solid electrolytes may be prospective materials that can be used in many fields.

  13. Itinerant magnetism in CeRh3B2

    DEFF Research Database (Denmark)

    Eriksson, Olle; Johansson, Börje; Brooks, M. S. S.

    1989-01-01

    Spin-polarized energy-band calculations, including spin-orbit coupling in the band Hamiltonian, have been performed on CeRh3B2. Good agreement is obtained between theory and experiment concerning the magnetic moment. It is also found that the magnetic moment varies strongly with volume and from...

  14. CE microchips: an opened gate to food analysis.

    Science.gov (United States)

    Escarpa, Alberto; González, María Cristina; Crevillén, Agustín González; Blasco, Antonio Javier

    2007-03-01

    CE microchips are the first generation of micrototal analysis systems (-TAS) emerging in the miniaturization scene of food analysis. CE microchips for food analysis are fabricated in both glass and polymer materials, such as PDMS and poly(methyl methacrylate) (PMMA), and use simple layouts of simple and double T crosses. Nowadays, the detection route preferred is electrochemical in both, amperometry and conductivity modes, using end-channel and contactless configurations, respectively. Food applications using CE microchips are now emerging since food samples present complex matrices, the selectivity being a very important challenge because the total integration of analytical steps into microchip format is very difficult. As a consequence, the first contributions that have recently appeared in the relevant literature are based primarily on fast separations of analytes of high food significance. These protocols are combined with different strategies to achieve selectivity using a suitable nonextensive sample preparation and/or strategically choosing detection routes. Polyphenolic compounds, amino acids, preservatives, and organic and inorganic ions have been studied using CE microchips. Thus, new and exciting future expectations arise in the domain of food analysis. However, several drawbacks could easily be found and assumed within the miniaturization map.

  15. A Sesame Equation of State for Dense Ce

    Energy Technology Data Exchange (ETDEWEB)

    Greeff, Carl William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Crockett, Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-15

    We generated a new Sesame equation of state table for Ce. It is a single effective phase table for the high density phases α, α ', ϵ and liquid. Also, the EOS is meant to be used with a ramp to represent the initial low density γ phase.

  16. Commensurate-commensurate magnetic phase transitions in CeSb

    DEFF Research Database (Denmark)

    Lebech, Bente; Broholm, C.; Clausen, K.;

    1986-01-01

    The q=2/3 to q=4/7 commensurate-commensurate phase transition in CeSb has been studied by neutron diffraction. On cooling the commensurate wave vector q changes abruptly from 2/3 to a higher-order commensurate value (≈14/23) at T1

  17. Improved performance of QCD code on ALiCE

    CERN Document Server

    Sroczynski, Z

    2003-01-01

    We present results for the performance of QCD code on ALiCE, the Alpha-Linux Cluster Engine at Wuppertal. We describe the techniques employed to optimise the code, including the metaprogramming of assembler kernels, the effects of data layout and an investigation into the overheads incurred by the communication.

  18. Improved performance of QCD code on ALiCE

    Science.gov (United States)

    Sroczynski, Z.

    2003-05-01

    We present results for the performance of QCD code on ALiCE , the Alpha-Linux Cluster Engine at Wuppertal. We describe the techniques employed to optimise the code, including the metaprogramming of assembler kernels, the effects of data layout and an investigation into the overheads incurred by the communication.

  19. Ce-Y-O固溶体及其PdO/Ce-Y-O催化剂的制备,表征和CH4氧化性能%Characterization and Preparation of Ce-Y-O Solid Solutions and PdO/Ce-Y-O Catalysts for CH4 Oxidation

    Institute of Scientific and Technical Information of China (English)

    罗孟飞; 单文娟; 李美俊; 鲁继青; 李灿

    2001-01-01

    Ce-Y-O Solid Solution was prepared by citrate sol-gel method,and characterized by using XRD,Raman and TPR techniques.The structure of the solid solution depends on the Ce/(Ce+Y)ratio.When Ce/(Ce+Y)≥0.6,only face centered cubic phase is observed.When Ce/(Ce+Y)≤0.5,only body centered cubic phase is observed.The addition of Y atoms into CeO2 improves the reduction-oxidation behavior.Ce-Y-O-supported PdO catalysts show higher activity for CH4 oxidation than PdO/CeO2 and PdO/Y2O3 catalysts.The PdO/Ce0.8Y0.2O1.90 catalyst is the most active of all catalysts.%采用柠檬酸溶胶-凝胶法制备了Ce-Y-O固溶体,并用XRD和Raman对Ce-Y-O固溶体的物相结构进行了表征,发现当n(Ce)/n(Ce+Y)(摩尔比)≥0.6时,Ce-Y-O固溶体为面心立方结构,而n(Ce)/n(Ce+Y)≤0.5时为体心立方结构。固溶体的生成有利于提高氧化还原性能。Ce-Y-O固溶体担载PdO催化剂的CH4氧化活性表明,n(Ce)/n(Ce+Y)对担载PdO催化剂的CH4氧化活性影响很大,当n(Ce)/n(Ce+Y)=0.8时催化剂活性最高,CH4转化率50%的温度为350℃,完全转化温度为600℃。

  20. Study on solid solution and aging process of AZ91D magnesium alloy with cerium

    Institute of Scientific and Technical Information of China (English)

    GUO

    2010-01-01

    The influence of Ce on solid solution and aging process of AZ91D magnesium alloy was analyzed.The results showed that the decomposition of β-Mg17Al12 phase in AZ91D magnesium alloy at 420 ℃ could be completed within 12 h,while this process in the Ce-containing alloy required more time.In subsequent aging process at 175 ℃,Ce obviously delayed the aging process of AZglD.It was inferred that the influence of Ce on process of solid solution and aging was relative to the Ce that existed in β-Mg17Al12 phase of original structure in the form of solid solution,and the interaction of the Ce and Al was an important factor to get process of solution and aging slowly.

  1. Evolution of magnetism from mixed-valent CeIr3B2 to trivalent CeIr3Si2

    Science.gov (United States)

    Umarji, A. M.; Dhar, S. K.; Malik, S. K.; Vijayaraghavan, R.

    1987-12-01

    The ternary compound CeIr3B2 is a mixed-valent material crystallizing in a monoclinic structure, closely related to the hexagonal CeCo3B2-type structure. The structural and magnetic phase diagrams of the systems CeRh3-yIryB2 (y=0-2) and CeIr3B2-xSix (x=0-2) have been investigated. Properties of the new compound CeIr3Si2 have been reported for the first time. It is shown that the structure of CeIr3B2 transforms to the hexagonal type on substitution of Rh and Si at Ir and B sites, respectively. Accompanying the structural transformation is an electronic transition in which the mixed-valent Ce atoms become more magnetic. The observed ferromagnetic ground state is similar to the one seen in CeRh3B2 (TC=115 K and μsat=0.4μB). The role of Ce-atom ligands and their hybridization is thought to be the primary cause for the unusual nature magnetism in CeT3B2-type compounds.

  2. Ce3+-ion-induced visible-light photocatalytic degradation and electrochemical activity of ZnO/CeO2 nanocomposite

    Science.gov (United States)

    Rajendran, Saravanan; Khan, Mohammad Mansoob; Gracia, F.; Qin, Jiaqian; Gupta, Vinod Kumar; Arumainathan, Stephen

    2016-08-01

    In this study, pure ZnO, CeO2 and ZnO/CeO2 nanocomposites were synthesized using a thermal decomposition method and subsequently characterized using different standard techniques. High-resolution X-ray photoelectron spectroscopy measurements confirmed the oxidation states and presence of Zn2+, Ce4+, Ce3+ and different bonded oxygen species in the nanocomposites. The prepared pure ZnO and CeO2 as well as the ZnO/CeO2 nanocomposites with various proportions of ZnO and CeO2 were tested for photocatalytic degradation of methyl orange, methylene blue and phenol under visible-light irradiation. The optimized and highly efficient ZnO/CeO2 (90:10) nanocomposite exhibited enhanced photocatalytic degradation performance for the degradation of methyl orange, methylene blue, and phenol as well as industrial textile effluent compared to ZnO, CeO2 and the other investigated nanocomposites. Moreover, the recycling results demonstrate that the ZnO/CeO2 (90:10) nanocomposite exhibited good stability and long-term durability. Furthermore, the prepared ZnO/CeO2 nanocomposites were used for the electrochemical detection of uric acid and ascorbic acid. The ZnO/CeO2 (90:10) nanocomposite also demonstrated the best detection, sensitivity and performance among the investigated materials in this application. These findings suggest that the synthesized ZnO/CeO2 (90:10) nanocomposite could be effectively used in various applications.

  3. Ce(3+)-ion-induced visible-light photocatalytic degradation and electrochemical activity of ZnO/CeO2 nanocomposite.

    Science.gov (United States)

    Rajendran, Saravanan; Khan, Mohammad Mansoob; Gracia, F; Qin, Jiaqian; Gupta, Vinod Kumar; Arumainathan, Stephen

    2016-08-16

    In this study, pure ZnO, CeO2 and ZnO/CeO2 nanocomposites were synthesized using a thermal decomposition method and subsequently characterized using different standard techniques. High-resolution X-ray photoelectron spectroscopy measurements confirmed the oxidation states and presence of Zn(2+), Ce(4+), Ce(3+) and different bonded oxygen species in the nanocomposites. The prepared pure ZnO and CeO2 as well as the ZnO/CeO2 nanocomposites with various proportions of ZnO and CeO2 were tested for photocatalytic degradation of methyl orange, methylene blue and phenol under visible-light irradiation. The optimized and highly efficient ZnO/CeO2 (90:10) nanocomposite exhibited enhanced photocatalytic degradation performance for the degradation of methyl orange, methylene blue, and phenol as well as industrial textile effluent compared to ZnO, CeO2 and the other investigated nanocomposites. Moreover, the recycling results demonstrate that the ZnO/CeO2 (90:10) nanocomposite exhibited good stability and long-term durability. Furthermore, the prepared ZnO/CeO2 nanocomposites were used for the electrochemical detection of uric acid and ascorbic acid. The ZnO/CeO2 (90:10) nanocomposite also demonstrated the best detection, sensitivity and performance among the investigated materials in this application. These findings suggest that the synthesized ZnO/CeO2 (90:10) nanocomposite could be effectively used in various applications.

  4. Preparation with laser ablation and photoluminescence of Y3Al5O12:Ce nanophosphors

    Science.gov (United States)

    Cho, Young-Sik; Huh, Young-Duk; Park, Chan Ryang; Do, Young Rag

    2014-03-01

    We prepared Y3Al5O12:Ce (YAG:Ce) nanophosphors with a mean size of 15 nm by using laser ablation of micron-sized commercial YAG:Ce target phosphor in 1,4-butanediol. The photoluminescence properties of the YAG:Ce nanophosphors were compared with those of micron-sized YAG:Ce phosphor. The elimination of back-scattering effect was confirmed by the optical properties of the YAG:Ce nanophosphors. The thermal stability of the YAG:Ce nanophosphors was also examined for the use of high power white LED. We convinced that the laser ablation method in 1,4-butanediol is an adequate method for the preparation of YAG:Ce nanophosphors for high power white LED with enhancement of the transmittance of the blue light from the InGaN chip.

  5. A novel sensitive sheathless CE-MS device for peptide and protein analysis

    DEFF Research Database (Denmark)

    Nguyen, Tam T. T. N.; Petersen, Nickolaj J.; Rand, Kasper Dyrberg

    Introduction CE-MS has shown considerable potential in protein research and pharmaceutical development, however, technical challenges of hyphenation of CE with MS have limited its use. Here, we have developed a sensitive CE-MS setup for peptide and protein analysis, that employs a novel and low......-cost sheathless CE-MS interface and a poly(ethyleneglycol)-coated capillary. Using the CE-MS setup, we have achieved fast and efficient separation and sensitive mass analysis of individual components of a complex sample of pharmaceutically relevant human proteins including insulin, tissue factor, α......-synuclein and a tryptic digest of bovine serum albumin. We have furthermore compared the performance of the CE-MS technique to UPLC-MS and demonstrate significant advantages of the CE-MS setup in terms of analysis time, sample consumption and separation capacity. Methods The sheathless CE-MS interface is based...

  6. The equiatomic intermetallics REPtCd (RE = La, Ce, Pr, Nd, Eu) and magnetic properties of CeAuCd

    Energy Technology Data Exchange (ETDEWEB)

    Johnscher, Michael; Niehaus, Oliver; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Tappe, Frank [Hochschule Hamm-Lippstadt, Hamm (Germany)

    2015-06-01

    The cadmium intermetallics REPtCd (RE = La, Ce, Pr, Nd, Eu) and CeAuCd were synthesized by induction-melting of the elements in sealed niobium ampoules followed by annealing in muffle furnaces. The samples were characterized by powder X-ray diffraction. The structures of CePtCd (ZrNiAl type, P anti 62m, a = 763.8(6), c = 409.1(4) pm, wR2 = 0.0195, 298 F{sup 2} values, 14 variables) and EuPtCd (TiNiSi type, Pnma, a = 741.3(2), b = 436.4(1), c = 858.0(4) pm, wR2 = 0.0385, 440 F{sup 2} values, 20 variables) were refined from single-crystal data. The REPtCd structures exhibit three-dimensional networks of corner- and edge-sharing Cd rate at Pt{sub 2/6}Pt{sub 2/3} and Cd rate at Pt{sub 4/4} tetrahedra, which leave cages for the rare earth atoms. Temperature-dependent magnetic susceptibility data of CeAuCd reveal a paramagnetic to antiferromagnetic phase transition at T{sub N} = 3.7(5) K.

  7. Evaluation of production samples of the scintillators LaBr3:Ce andLaCl3:Ce

    Energy Technology Data Exchange (ETDEWEB)

    Choong, Woon-Seng; Derenzo, Stephen E.; Moses, William W.

    2005-09-15

    We report on the evaluation of the performance of two recently developed scintillator materials, LaCl{sub 3}:Ce and LaBr{sub 3}:Ce, at the task of gamma ray spectroscopy. Their performance is compared to a standard scintillator used for gamma ray spectroscopy--a 25 mm diameter 25 mm tall cylinder of NaI:Tl. We measure the pulse height, energy resolution, and full-energy efficiency of production LaBr{sub 3}:Ce and LaCl{sub 3}:Ce scintillation crystals of different sizes and geometries for a variety of gamma-ray energies. Using production rather than specially selected crystals will establish whether immediate large-scale use is feasible. The crystal is excited by gamma rays from one of six isotopic sources ({sup 125}I, {sup 241}Am, {sup 57}Co, {sup 22}Na, {sup 137}Cs, and {sup 60}Co) placed 15 cm away from the scintillator. Our measurements show that both LaCl{sub 3} and LaBr{sub 3} outperform NaI:Tl in almost all cases. They outperform NaI:Tl at all energies for the photopeak fraction and counting rate measurements, and for energy resolution at higher energies (above 200 keV for LaCl{sub 3} and 75 keV for LaBr{sub 3}). The performance of production crystals is excellent and these scintillators should be considered for immediate use in systems where stopping power and energy resolution are crucial.

  8. Design and Preparation of MnO2/CeO2-MnO2 Double-Shelled Binary Oxide Hollow Spheres and Their Application in CO Oxidation.

    Science.gov (United States)

    Zhang, Jian; Cao, Yidan; Wang, Chang-An; Ran, Rui

    2016-04-06

    Herein, we designed an extremely facile method to prepare well-defined MnO2@CeO2-MnO2 ball-in-ball binary oxide hollow spheres by employing carbon spheres (CSs) as sacrificial templates. The synthesis process involves a novel self-assembled approach to prepare core-shell CSs@CeO2 precursor, which would directly react with KMnO4 aqueous solution to form yolk-shell CSs@MnO2/CeO2-MnO2 precursor in the following step. Well-dispersed Ce-Mn binary oxide with double-shelled hollow sphere structure could be achieved after annealing the precursor in air. The evolution process and formation mechanism of this novel structure were thoroughly studied in this paper. Especially the as-prepared double-shell MnO2/CeO2-MnO2 hollow spheres exhibited enhanced catalytic activity for CO oxidation compared with the pure MnO2 hollow spheres and pure CeO2 hollow spheres. We believe the high surface area, hierarchical porous structures, and strong synergistic interaction between CeO2 and MnO2 contribute to the excellent catalytic activity. Most importantly, this method could be extended to prepare other transition metal oxides. As an example, triple-shelled Co-Mn composite hollow spheres assembled by ultrathin nanoplates were successfully prepared.

  9. 甘氨酸-硝酸盐法制备NiO-Sm掺杂CeO2复合阳极粉末研究%Synthesis of NiO-SDC Composite Powders for Anode by Glycine-Nitrate Process

    Institute of Scientific and Technical Information of China (English)

    孙明涛; 孙俊才; 季世军

    2006-01-01

    采用甘氨酸-硝酸盐燃烧法合成了中温固体氧化物燃料电池NiO-SDC复合阳极粉末.通过XRD和扫描电子显微镜对不同甘氨酸/金属离子摩尔比合成的复合粉末的结构和形貌进行了研究.XRD结果表明,直接燃烧合成的复合粉末除了NiO和CeO2的衍射峰外,还有Ni2O3衍射峰存在,粉末经900℃煅烧2 h后Ni2O3峰消失,表明形成了NiO-SDC复合阳极粉末.氢气条件下的热重分析表明,复合粉末中NiO和SDC两相比例与溶液组分配比基本一致.制备的不同NiO含量薄膜阳极的电解质支撑单电池性能测试结果表明,阳极为60%NiO-SDC的单电池具有最高的开路电压.

  10. Competition Between Organic Matter and Solid Surface for Cation Sorption: Ce and Rare Earth Element as Proxy

    Science.gov (United States)

    Davranche, M.; Pourret, O.; Gruau, G.; Dia, A.

    2006-12-01

    Aquatic or soil organic matter are well-known to be strong adsorbent of many cations due to their adsorption capacity. Among these cations, the trivalent rare earth element (REE) and particularly Ce seem to be promising tools to investigate the impact of competition in between organic or inorganic ligands. Ce (III) is oxidized into Ce (IV) by oxidative surface such as Fe and Mn oxyhydroxides. Since Ce (IV) is preferentially adsorbed (as compared to other REE), a positive and negative Ce anomaly is developed respectively onto the solid and within the solution. Previous studies (Davranche et al., 2004, 2005) highlighted the suppression of this feature when Ce occurs to be complexed with organic matter (as humate species). Recent experiments were designed to evaluate the competition between humate and Mn oxide for REE complexation (each reactant being added simultaneously). Two parameters control the competition: time and pH. While organic matter does adsorb immediately the free REE, a desorption of REE occurs through time. Desorption is marked by the development of a Ce anomaly in the REE pattern that reflects the complexation with Mn oxide surface. Along the time, solid surface becomes thus more competitive than the organic matter. PH still influences the competition since at basic pH, REE and organic matter - probably as REE-organic complexes - are adsorbed onto the solid surface. Ultrafiltration analyses at 5 KD were also performed to separate organic matter and organic complexes from the solution. Results provide evidence that in presence of a solid surface, HREE (high rare earth element) desorption from the organic matter occurs through time. This leads to HREE enrichment in solution. All these results suggest that complexation of organic matter is kinetically favoured as compared to the complexation with solid surfaces. However, the organic complex formed during the first stage of the complexation process involves weak bindings. These bindings are easily broken

  11. Effects of strong interactions between Ti and ceria on the structures of Ti/CeO2.

    Science.gov (United States)

    Yao, Xiao-Dan; Zhu, Kong-Jie; Teng, Bo-Tao; Yu, Cao-Ming; Zhang, Yun-Lei; Liu, Ya; Fan, Maohong; Wen, Xiao-Dong

    2016-11-30

    The effects of strong interactions between Ti and ceria on the structures of Ti/CeO2(111) are systematically investigated by density functional theory calculation. To our best knowledge, the adsorption energy of a Ti atom at the hollow site of CeO2 is the highest value (-7.99 eV) reported in the literature compared with those of Au (-0.88--1.26 eV), Ag (-1.42 eV), Cu (-2.69 eV), Pd (-1.75 eV), Pt (-2.62 eV) and Sn (-3.68 eV). It is very interesting to find that Ti adatoms disperse at the hollow site of CeO2(111) to form surface TiOx species, instead of aggregating to form Ti metal clusters for the Ti-CeO2 interactions that are much stronger than those of Ti-Ti ones. Ti adatoms are completely oxidized to Ti(4+) ions if they are monatomically dispersed on the next near hollow sites of CeO2(111) (xTi-NN-hollow); while Ti(3+) ions are observed when they locate at the near hollow sites (xTi-N-hollow). Due to the electronic repulsive effects among Ti(3+) ions, the adsorption energies of xTi-N-hollow are slightly weaker than those of xTi-NN-hollow. Simultaneously, the existence of unstable Ti(3+) ions on xTi-N-hollow also leads to the restructuring of xTi-N-hollow by surface O atoms of ceria transferring to the top of Ti(3+) ions, or oxidation by O2 adsorption and dissociation. Both processes improve the stability of the xTi/CeO2 system by Ti(3+) oxidation. Correspondingly, surface TiO2-like species form. This work sheds light into the structures of metal/CeO2 catalysts with strong interactions between the metal and the ceria support.

  12. Modification and aging precipitation behavior of hypereutectic Al-21wt.%Si alloy treated by P+Ce combination

    Institute of Scientific and Technical Information of China (English)

    Liu Pei; Wang Aiqin; Xie Jingpei

    2014-01-01

    In the present study, the tested hypereutectic Al-21wt.%Si al oys were prepared by modifying the melt using different proportions of P and Ce, and then applying T6 heat treatment. The modification effects and mechanism of P+Ce complex modifier on the Si phase of hypereutectic Al-21wt.%Si al oy were studied, and the aging precipitation behavior after modification was characterized by means of tensile strength measurement, OM, SEM and TEM analysis. The results show that the massive primary silicon phase particles are significantly refined after modification, while the needle-like eutectic silicon crystals become fibrous and short. It was found that the mechanism of phosphorus modification on the primary silicon can be attributed to heterogeneous nucleation of AlP, while the modification mechanism of Ce can be explained by adsorbing-twinning theory. In the aged microstructure of the modified hypereutectic Al-21wt.%Si al oy, there existed some strengthening phases such as Al4Cu9, Al2Cu, AlCu3, and Al57Mn12. The P+Ce complex modifier not only affected the size of primary silicon and eutectic silicon, but also the aging behavior of al oys under the heat treatment process. When Al-21wt.%Si al oy was modified using 0.08%wt.P + 0.6wt.% Ce, the aging precipitates were dispersed uniformly in the al oy, and its mechanical properties at room and elevated temperatures are optimized (Rm = 287.6 MPa at RT, Rm = 210 MPa at 300 ℃).

  13. Dehybridization of the 4f shell in Si-substituted CeRh3B2

    Science.gov (United States)

    Malik, S. K.; Shenoy, G. K.; Dhar, S. K.; Paulose, P. L.; Vijayaraghavan, R.

    1986-12-01

    The compound CeRh3B2 is known to order magnetically with an unusually high Curie temperature (TC) of 115 K and a low saturation moment of about 0.4μB. We have studied the magnetic behavior of the system CeRh3(B1-xSix)2 (0CeRh3B2 arises because of the Ce 4f hybridization with the neighboring ligands.

  14. CE: Incorporating Acupressure into Nursing Practice.

    Science.gov (United States)

    Wagner, Judy

    2015-12-01

    Rooted in traditional Chinese medicine, the use of acupressure to alleviate symptoms, support the healing process, promote relaxation, and improve overall health has grown considerably in the West. The effects of acupressure--like those of acupuncture, with which it shares a theoretical framework--cannot always be explained in terms of Western anatomical and physiologic concepts, but this noninvasive practice involves minimal risk, can be easily integrated into nursing practice, and has been shown to be effective in treating nausea as well as low back, neck, labor, and menstrual pain. The author discusses potential clinical indications for the use of acupressure, describes the technique, explains how to evaluate patient outcomes, and suggests how future research into this integrative intervention might be improved.

  15. In-situ electrochemical route to aerogel electrode materials of graphene and hexagonal CeO₂.

    Science.gov (United States)

    Chen, Kunfeng; Xue, Dongfeng

    2015-05-15

    We reported a one-step in-situ electrochemical route to synthesize 3D aerogel electrode materials including graphene and hexagonal CeO2 composites. The graphene/CeO2 aerogel can be formed via freeze-drying graphene/CeO2 colloidal solution that was obtained by electrochemical exfoliation of graphite anode and in-situ deposition of CeO2 nanoparticles on graphene sheets in mixing electrolyte of (NH4)2SO4/Ce(NO3)3 and (NH4)2SO4/(NH4)2Ce(NO3)6. The as-obtained CeO2 nanoparticles were closely contacted with graphene, which can enhance the synergistic effect between graphene and CeO2. It is interesting that the as-obtained CeO2 products possessed hexagonal crystal structure that was rarely reported. The Faradaic reactivity of the graphene/CeO2 composites as supercapacitor was enhanced with the increase of the concentration of Ce salts in initial electrolyte. The introduction of CeO2 to graphene electrode can lead to the presence of additional pseudocapacitance besides the electric double-layer capacitance. This simple one-step in-situ electrochemical route can be extended to synthesize various graphene/metal oxide aerogel electrode materials for electric energy storage.

  16. Redox enzyme-mimicking activities of CeO2 nanostructures: Intrinsic influence of exposed facets

    Science.gov (United States)

    Yang, Yushi; Mao, Zhou; Huang, Wenjie; Liu, Lihua; Li, Junli; Li, Jialiang; Wu, Qingzhi

    2016-10-01

    CeO2 nanoparticles (NPs) have been well demonstrated as an antioxidant in protecting against oxidative stress-induced cellular damages and a potential therapeutic agent for various diseases thanks to their redox enzyme-mimicking activities. The Ce3+/Ce4+ ratio and oxygen vacancies on the surface have been considered as the major originations responsible for the redox enzyme-mimicking activities of CeO2 NPs. Herein, CeO2 nanostructures (nanocubes and nanorods) exposed different facets were synthesized via a facile hydrothermal method. The characterizations by X-ray photoelectron spectroscopy, Raman spectroscopy, and UV-Vis spectroscopy show that the Ce3+/Ce4+ ratio and oxygen vacancy content on the surfaces of as-synthesized CeO2 nanostructures are nearly at the same levels. Meanwhile, the enzymatic activity measurements indicate that the redox enzyme-mimicking activities of as-synthesized CeO2 nanostructures are greatly dependent on their exposed facets. CeO2 nanocubes with exposed {100} facets exhibit a higher peroxidase but lower superoxide dismutase activity than those of the CeO2 nanorods with exposed {110} facets. Our results provide new insights into the redox enzyme-mimicking activities of CeO2 nanostructures, as well as the design and synthesis of inorganic nanomaterials-based artificial enzymes.

  17. Photocatalytic degradation of methyl orange by CeO2 and Fe-doped CeO2 films under visible light irradiation.

    Science.gov (United States)

    Channei, D; Inceesungvorn, B; Wetchakun, N; Ukritnukun, S; Nattestad, A; Chen, J; Phanichphant, S

    2014-08-29

    Undoped CeO2 and 0.50-5.00 mol% Fe-doped CeO2 nanoparticles were prepared by a homogeneous precipitation combined with homogeneous/impreganation method, and applied as photocatalyst films prepared by a doctor blade technique. The superior photocatalytic performances of the Fe-doped CeO2 films, compared with undoped CeO2 films, was ascribed mainly to a decrease in band gap energy and an increase in specific surface area of the material. The presence of Fe(3+) as found from XPS analysis, may act as electron acceptor and/or hole donor, facilitating longer lived charge carrier separation in Fe-doped CeO2 films as confirmed by photoluminescence spectroscopy. The 1.50 mol% Fe-doped CeO2 film was found to be the optimal iron doping concentration for MO degradation in this study.

  18. Spectroscopy Study on Crystal Structure of Ce(NO3)3(phen)2 and Interactions of Ce(NO3)3(phen)2 with DNA

    Institute of Scientific and Technical Information of China (English)

    Hu Ruiding; Lin Qiuyue; Huang Wei; Yu Qingsen

    2005-01-01

    The absorption, fluorescence and Raman spectra of Ce(NO3)3(phen)2 complex were assigned and the crystal structure of the complex was studied. Meanwhile the interactions between Ce(NO3)3(phen)2 and DNA were studied by spectrum methods. As DNA was added, it is found that both the UV absorption bands of Ce(NO3)3(phen)2 and the SERS bands of Ce(NO3)3(phen)2 weaken evidently, while the fluorescence intensity of Ce(NO3)3(phen)2 enhance dramatically. The complex compete against EB on the reaction with DNA. It is indicated by this spectrum methods that there are strong interactions between Ce(NO3)3(phen)2 and DNA, and the bond mode is intercalation. The bond constant of the complex with DNA is determined to be 1.7×105.

  19. Pt metal-CeO2 interaction: direct observation of redox coupling between Pt0/Pt2+/Pt4+ and Ce4+/Ce3+ states in Ce(0.98)Pt(0.02)O2-delta catalyst by a combined electrochemical and x-ray photoelectron spectroscopy study.

    Science.gov (United States)

    Sharma, Sudhanshu; Hegde, M S

    2009-03-21

    Pt ions-CeO(2) interaction in Ce(1-x)Pt(x)O(2-delta) (x=0.02) has been studied for the first time by electrochemical method combined with x-ray diffraction and x-ray photoelectron spectroscopy. Working electrodes made of CeO(2) and Ce(0.98)Pt(0.02)O(2-delta) mixed with 30% carbon are treated electrochemically between 0.0-1.2 V in potentiostatic (chronoamperometry) and potentiodynamic (cyclic voltametry) mode with reference to saturated calomel electrode. Reversible oxidation of Pt(0) to Pt(2+) and Pt(4+) state due to the applied positive potential is coupled to simultaneous reversible reduction of Ce(4+) to Ce(3+) state. CeO(2) reduces to CeO(2-y) (y=0.35) after applying 1.2 V, which is not reversible; Ce(0.98)Pt(0.02)O(2-delta) reaches a steady state with Pt(2+):Pt(4+) in the ratio of 0.60:0.40 and Ce(4+):Ce(3+) in the ratio of 0.55:0.45 giving a composition Ce(0.98)Pt(0.02)O(1.74) at 1.2 V, which is reversible. Composition of Pt ion substituted compound is reversible between Ce(0.98)Pt(0.02)O(1.95) to Ce(0.98)Pt(0.02)O(1.74) within the potential range of 0.0-1.2 V. Thus, Ce(0.98)Pt(0.02)O(2-delta) forms a stable electrode for oxidation of H(2)O to O(2) unlike CeO(2). A linear relation between oxidation of Pt(2+) to Pt(4+) with simultaneous reduction in Ce(4+) to Ce(3+) is observed demonstrating Pt-CeO(2) metal support interaction is due to reversible Pt(0)/Pt(2+)/Pt(4+) interaction with Ce(4+)/Ce(3+) redox couple.

  20. Synthesis of CeFe10.5Mo1.5 with ThMn12-type structure by melt spinning

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, C; Tessema, M; Meyer, MS; Pinkerton, FE

    2013-06-01

    Rare earth compounds RFe12_xMx with tetragonal ThMn12-type structure are of great research interest for potential applications as permanent magnets. These materials are known to serve as the precursors for nitriding and hydriding processes which in certain conditions can dramatically increase the Curie temperature, spontaneous magnetization, and affect the magnetic anisotropy. In this paper, we report the phase study of CeFe10.5Mo1.5 samples melt spun at various surface wheel speeds vs between 5 m/s and 60 m/s. The results from quantitative Rietveld analysis indicate that the as-spun ribbons are a mixture of primary CeFe10.5Mo1.5 phase with impurity phases such as Ce2Fe17, Fe-Mo alloy and CeFe2. When the wheel speed vs is below 25 m/s, CeFe10.5Mo1.5 phase accounts for greater than 85 wt% in the as-spun ribbons, while the Fe-Mo alloy is the only detectable impurity phase. Above v(s)=25 m/s, as the wheel speed increases, CeFe10.5Mo1.5 phase decreases monotonically to about 60 wt% at v(s)=6O m/s while the amounts of impurity phases increase. Thermogravimetric measurement indicates that the Curie temperature T-c. corresponding to CeFe10.5Mo1.5 phase is 341 K. As a result, the best performing sample melt spun at v(s),=15 m/s only exhibits an energy product BHmax=0.121 MGOe at room temperature. Although such a number is modest for a permanent magnet, further nitriding is expected to greatly enhance the Curie temperature, and hence the magnetic performance. (C) 2013 Elsevier B.V. All rights reserved.

  1. Suwannee River flow variability 1550-2005 CE reconstructed from a multispecies tree-ring network

    Science.gov (United States)

    Harley, Grant L.; Maxwell, Justin T.; Larson, Evan; Grissino-Mayer, Henri D.; Henderson, Joseph; Huffman, Jean

    2017-01-01

    Understanding the long-term natural flow regime of rivers enables resource managers to more accurately model water level variability. Models for managing water resources are important in Florida where population increase is escalating demand on water resources and infrastructure. The Suwannee River is the second largest river system in Florida and the least impacted by anthropogenic disturbance. We used new and existing tree-ring chronologies from multiple species to reconstruct mean March-October discharge for the Suwannee River during the period 1550-2005 CE and place the short period of instrumental flows (since 1927 CE) into historical context. We used a nested principal components regression method to maximize the use of chronologies with varying time coverage in the network. Modeled streamflow estimates indicated that instrumental period flow conditions do not adequately capture the full range of Suwannee River flow variability beyond the observational period. Although extreme dry and wet events occurred in the gage record, pluvials and droughts that eclipse the intensity and duration of instrumental events occurred during the 16-19th centuries. The most prolonged and severe dry conditions during the past 450 years occurred during the 1560s CE. In this prolonged drought period mean flow was estimated at 17% of the mean instrumental period flow. Significant peaks in spectral density at 2-7, 10, 45, and 85-year periodicities indicated the important influence of coupled oceanic-atmospheric processes on Suwannee River streamflow over the past four centuries, though the strength of these periodicities varied over time. Future water planning based on current flow expectations could prove devastating to natural and human systems if a prolonged and severe drought mirroring the 16th and 18th century events occurred. Future work in the region will focus on updating existing tree-ring chronologies and developing new collections from moisture-sensitive sites to improve

  2. Myxomycetes da Chapada do Araripe (Crato - CE, Brasil Myxomycetes from Chapada do Araripe (Crato, CE, Brazil

    Directory of Open Access Journals (Sweden)

    Laise de Holanda Cavalcanti

    1998-12-01

    Full Text Available Foi efetuado um levantamento dos Myxomyeetes ocorrentes em área de floresta no município do Crato, CE (7º13'53" S; 39º24'28'' W; Alt. 422m, assinalando-se as seguintes famílias e gêneros: Ceratiomyxaceae (Ceratiomyxa, 1 sp.; Cribrariaceae (Cribraria, lsp., Dictydium, 1 sp.; Didymiaceae (Didymium, 2sp.; Enteridiaceae (Dicrydiaethalium, 1sp.; Physaraceae (Badhamia, 2sp., Fuligo, 2sp., Physarum, 5sp.; Steinonitaceae (Comatricha, 3sp., Sfemonitis, 6sp.; Trichiaceae (Arcyria, 3sp., Hemitrichia, 2sp., Periclwena, 1 sp.- Constatou-se preferência das espécies para frutificar em troncos mortos de dicotiledôneas, seguindo-se restos de palmeiras e folhedo. O levantamento eleva para 30 o número de espécies referidas para o Ceará. Uma família e 19 espécies são novos registros para o Estado e Arcyria magna var. rosea Rex é nova referência para o Brasil. São apresentados comentários, chave de identificação e distribuição geográfica das espécies no Nordeste do Brasil.A survey on Myxomycetes was made in the woods of Crato Municipality. State of Ceará, Brazil (7º13'53" S; 39º24,28" W; Alt. 422m. when the following families and genera were registered: Ceratiomyxaceae (Ceratiomyxa, 1 sp.; Cribrariaceae (Cribraria, 1 sp., Dictydium. 1 sp.; Didymiaceae (Didymium, 2sp.; Enteridiaceae Dictydiaethalium, 1 sp.; Physaraceae (Badhamia. 2sp., Fuligo, 2sp., Physarum, 5sp.; Stemonitaceae Comatricha, 3sp., Stemonitis, 6sp.; Trichiaceae (Arcyria, 3sp., Hemitrichia, 2sp., Perichaena, lsp..The species sporulated mostly on dead dicotyledones wood, followed by monocotyledones (Arecaceae debris and litter. The survey raises the number of registers referred to the State of Ceará to 30 species. One family and 19 species are new records for that State while Arcyria magna var. rosea Rex represents a new record for Brazil. Key for the species, comments and geographical distribution in Northeast Brazil arc presented.

  3. Air, aqueous and thermal stabilities of Ce3+ ions in cerium oxide nanoparticle layers with substrates

    KAUST Repository

    Naganuma, Tamaki

    2014-01-01

    Abundant oxygen vacancies coexisting with Ce3+ ions in fluorite cerium oxide nanoparticles (CNPs) have the potential to enhance catalytic ability, but the ratio of unstable Ce3+ ions in CNPs is typically low. Our recent work, however, demonstrated that the abundant Ce3+ ions created in cerium oxide nanoparticle layers (CNPLs) by Ar ion irradiation were stable in air at room temperature. Ce valence states in CNPs correlate with the catalytic ability that involves redox reactions between Ce3+ and Ce4+ ions in given application environments (e.g. high temperature in carbon monoxide gas conversion and immersion conditions in biomedical applications). To better understand the mechanism by which Ce3+ ions achieve stability in CNPLs, we examined (i) extra-long air-stability, (ii) thermal stability up to 500 °C, and (iii) aqueous stability of Ce 3+ ions in water, buffer solution and cell culture medium. It is noteworthy that air-stability of Ce3+ ions in CNPLs persisted for more than 1 year. Thermal stability results showed that oxidation of Ce 3+ to Ce4+ occurred at 350 °C in air. Highly concentrated Ce3+ ions in ultra-thin CNPLs slowly oxidized in water within 1 day, but stability was improved in the cell culture medium. Ce 3+ stability of CNPLs immersed in the medium was associated with phosphorus adsorption on the Ce3+ sites. This study also illuminates the potential interaction mechanisms of stable Ce3+ ions in CNPLs. These findings could be utilized to understand catalytic mechanisms of CNPs with abundant oxygen vacancies in their application environments. © The Royal Society of Chemistry 2014.

  4. Synthesis and characterization of manganese doped CeO2 nanopowders from hydrolysis and oxidation of Ce37Mn18C45

    Institute of Scientific and Technical Information of China (English)

    DU Yanan; NI Jiansen; HU Pengfei; WANG Jun'an; HOU Xueling; XU Hui

    2013-01-01

    The Mn-doped CeO2 nanopowders with high catalysis activity were successfully fabricated through a simple hydrolyzed-oxidized approach.Firstly,the alloy Ce37Mn18C45 was prepared in vacuum induction melting furnace.Subsequently,Mn-doped CeO2 nanopowders with 142 m2/g of specific surface area were obtained through a simple hydrolyzed-oxidized procedure of the alloy.Those nanopowders were heat treated at different temperatures.The obtained materials were characterized by X-ray diffraction (XRD),transmission electron microscopy (TEM),high-resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS).And the catalytic activity on vinyl chloride (VC) emission combustion was investigated.The results showed that those nanopowders after hydrolyzed-oxidized from Ce37Mn1sC45 mainly consisted of CeO2 and Mn3O4.Manganese element increased the thermal stability of CeO2 nanopowders.The Mn-doped CeO2 nanopowders had three morphologies.Small particles were Mn-doped CeO2,square particles were Mn3O4 and the rods were Mn3O4 and Mn2O3.The Mn-doped CeO2 nanopowders had good vinyl chloride (VC) emission catalytic performance.

  5. Characterization of the structure features of CeZrO2 and Ni/CeZrO2 catalysts for tar gasification with steam

    OpenAIRE

    A. Krztoń; L.A. Dobrzański; M. Pawlyta; A. Łamacz

    2011-01-01

    Purpose: The aim of this study was to find out how CeZrO2 and Ni/CeZrO2 structures change after the steam reforming of toluene.Design/methodology/approach: Nickel oxide supported on CeZrO2 (Ni/CeZrO2) with nickel loading of 10 wt. % was prepared by incipient wetness impregnation using an aqueous solution of nickel nitrate. Structure, morphology and chemical composition changes after the steam reforming of toluene were investigated by means of scanning electron microscopy (SEM), energy dispers...

  6. COMPARISION OF THE COLOR PROPERTIES OF COMPOUNDS Ln2Ce2O7 AND Ln2CeZrO7

    OpenAIRE

    B. Hablovicova; P. Sulcova

    2015-01-01

    Pyrochlore type pigments Ln2Ce2O7 and Ln2CeZrO7 (Ln = Nd, Sm, Gd, Dy, Er, Yb and Y) prepared by solid-state reaction were investigated. Effect of rare earths and zirconium ions and calcination temperature (1400, 1500 and 1600oC for Ln2Ce2O7 and 1400, 1450 and 1500 C for Ln2CeZrO7) on their color properties in organic matrix and ceramic glazes, particle size distribution and phase composition were evaluated. The most interesting shades achieve compounds with the highest calcination temperature...

  7. Physical, biochemical and genetic characterization of enterocin CE5-1 produced by Enterococcus faecium CE5-1 isolated from Thai indigenous chicken intestinal tract

    Directory of Open Access Journals (Sweden)

    Kraiyot Saelim

    2015-06-01

    Full Text Available Enterocin CE5-1 produced by Enterococcus faecium CE5-1 isolated from the chicken gastrointestinal tract was active in the wide range of pH 2-10 and temperature 30-100°C and sensitive to proteolytic enzymes and -amylase. It remained active after storage at -20°C for 2 months. Moreover, enterocin CE5-1 showed antibacterial activity against lactobacilli, bacilli, listeria, staphylococci and enterococci, especially antibiotic-resistant enterococci. In vitro study of enterocin CE5-1 decreased the population of Ent. faecalis VanB from 6.03 to 4.03 log CFU/ml. The lethal mode of action of enterocin CE5-1 appeared to be pore and filament formation in the cell wall. PCR sequencing analysis revealed the presence of two open reading frames (ORFs, containing enterocin CE5-1 (entCE5-1 and enterocin immunity (entI gene. Therefore, enterocin CE5-1 from Ent. faecium CE5-1 could possibly be used as an antimicrobial agent to control foodborne pathogen, spoilage bacteria and antibiotic-resistant enterococci in foods, feeds and the environments.

  8. XAFS study of BaCe1-xTixO3 and Ba1-yCe1-xYxO3 protonic solid electrolytes

    Science.gov (United States)

    Seremak-Peczkis, P.; Schneider, K.; Zajączkowski, W.; Kapusta, Cz.; Zając, D. A.; Pasierb, P.; Bućko, M.; Drożdż-Cieśla, E.; Rękas, M.

    2009-10-01

    The paper reports on the doping-influenced evolution of the local structure in a new class of solid electrolytes, BaCe1-xTixO3 and Ba1-yCe1-xYxO3 perovskites, to be used in intermediate temperature fuel cells. The local environments of the Ti, Y and Ce cations were studied by means of X-ray absorption spectroscopy. The Ti XAFS spectra reveal a decrease of the local symmetry of titanium site with increasing doping. The Ce and Y EXAFS functions show a larger amount of oxygen vacancies created by Y doping than that caused by barium understoichiometry.

  9. Enhanced densification and microwave dielectric properties of Mg{sub 2}TiO{sub 4} ceramics added with CeO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bhuyan, R.K.; Kumar, T. Santhosh [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 39 (India); Goswami, D. [Department of Electronics and Communication Engineering, Indian Institute of Technology Guwahati, Guwahati 39 (India); James, A.R. [Defense Metallurgical Research Laboratory, Kanchanbagh, Hyderabad (India); Perumal, A. [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 39 (India); Pamu, D., E-mail: pamu@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 39 (India)

    2013-04-20

    Highlights: ► MTO ceramics are prepared at lower sintering temperature with fine CeO{sub 2} particles. ► CeO{sub 2} improves densification and form uniform microstructure with larger grains. ► MTO–CeO{sub 2} exhibit superior microwave dielectric properties, as compared to pure MTO. ► The mechanism to get higher densification and uniform microstructure are discussed. ► The properties are suitable for various microwave communication applications. -- Abstract: We report the study of the effects of processing parameters and additive concentration on the structure, microstructure and microwave dielectric properties of MTO–CeO{sub 2} (x wt.%) ceramics with x = 0, 0.5, 1.0 and 1.5 prepared by solid-state reaction method by adding CeO{sub 2} nanoparticles as a sintering aid. The pure Mg{sub 2}TiO{sub 4} ceramics were not densifiable below 1450 °C. However, when CeO{sub 2} nanoparticles were added to MTO, the densification achieved at 1300 °C along with the increase in average grain size with the uniform microstructure and improved microwave dielectric properties. This is mainly driven by the large surface energy of CeO{sub 2} nanoparticles and their defect energy during the sintering process. While the addition of CeO{sub 2} nanoparticles in MTO ceramics does not change the dielectric constant (ε{sub r}), the unloaded quality factor (Q{sub u}) was altered significantly. MTO–CeO{sub 2} (1.5 wt.%) ceramics sintered at 1300 °C exhibit superior microwave dielectric properties (ε{sub r} ∼ 14.6, Q × f{sub 0} ∼ 167 THz), as compared to the pure Mg{sub 2}TiO{sub 4} ceramics. The observed results are correlated to the enhancement in density and the development of uniform microstructure with the enhanced grain size.

  10. Gamma-ray spectroscopy of the nucleus {sup 139}Ce

    Energy Technology Data Exchange (ETDEWEB)

    Bucurescu, D.; Cata-Danil, G.; Cata-Danil, I.; Ivascu, M.; Marginean, N.; Marginean, R.; Mihailescu, L.C.; Rusu, C.; Suliman, G. [Horia Hulubei National Institute of Physics and Nuclear Engineering, P.O. Box MG-6, Bucharest (Romania)

    2006-03-15

    Gamma-ray coincidence techniques are used to determine new level structures in the N=81 nucleus {sup 139}Ce, at low spins and excitation energies with the {sup 139}La(p,n{gamma}) reaction at 5.0 and 6.0 MeV incident energy, and at high spins with the {sup 130}Te({sup 12}C,3n{gamma}) reaction at 50.5 MeV, respectively. Lifetime determinations are also made in the (p,n{gamma}) reaction with the centroid DSA method. The observed level structures are discussed by comparison with existing calculations and with those in the neighbouring nucleus {sup 140}Ce. (orig.)

  11. Identification and Quality Assessment of Chrysanthemum Buds by CE Fingerprinting

    Directory of Open Access Journals (Sweden)

    Xiaoping Xing

    2015-01-01

    Full Text Available A simple and efficient fingerprinting method for chrysanthemum buds was developed with the aim of establishing a quality control protocol based on biochemical makeup. Chrysanthemum bud samples were successively extracted by water and alcohol. The fingerprints of the chrysanthemum buds samples were obtained using capillary electrophoresis and electrochemical detection (CE-ED employing copper and carbon working electrodes to capture all of the chemical information. 10 batches of chrysanthemum buds were collected from different regions and various factories to establish the baseline fingerprint. The experimental data of 10 batches electropherogram buds by CE were analyzed by correlation coefficient and the included angle cosine methods. A standard chrysanthemum bud fingerprint including 24 common peaks was established, 12 from each electrode, which was successfully applied to identify and distinguish between chrysanthemum buds from 2 other chrysanthemum species. These results demonstrate that fingerprint analysis can be used as an important criterion for chrysanthemum buds quality control.

  12. Polarized neutron diffraction study of CePd{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Givord, F.; Galera, R.M.; Murani, A.P.; Lelievre-Berna, E

    2004-07-15

    We have performed polarized neutron diffraction measurements on the intermediate valence compound CePd{sub 3} using the D3 spectrometer at the ILL. The results show that at low temperatures, 1.7 K, as well as at 100 K, the field-induced magnetic amplitudes measured in a field of 4.6 T could be interpreted in terms of two contributions: a 4f-type contribution with a Ce{sup 3+} form factor, and an extra delocalized contribution (relatively narrow in q-extent). In particular, we find that the values of the 4f moment deduced from the extrapolation of the neutron data to Q=0 are systematically lower than the values deduced from bulk magnetization measurements performed on the same sample. This difference can be ascribed to a possible positive polarization of the conduction band which is similar at both temperatures.

  13. Thermal Conductivity of Ce Doped Bi-2212 Superconductors

    Institute of Scientific and Technical Information of China (English)

    LI Bo; WU Bai-Mei; M.Ausloos

    2004-01-01

    The temperature dependence of the thermal conductivity in Bi2Sr2 Ca1-x Cex Cu2Oy x = 0.1, 0.2, 0.3, 0.4 is presented. With increasing Ce-doping level, the thermal conductivity peak under TC is suppressed then disappears,while another peak appears at low temperatures for the non-superconducting compounds. The numerical analysis shows that the thermal conductivity peak under TC can be well described by the normal electron relaxation-time contribution model, and the phonon-induced thermal conductivity peak could be well described within the Debye approximation of the phonon spectrum. The existence and variation of these two thermal conductivity peaks indicate the adjustability between the superconducting and insulating components in the samples with different Ce-doping levels.

  14. Ni-CeO2 Cermets Synthesis by Solid State Sintering of Ni/CeO2 Multilayer

    Directory of Open Access Journals (Sweden)

    Aleksandras ILJINAS

    2013-12-01

    Full Text Available Nickel and gadolinium doped cerium oxide (GDC cermet is intensively investigated for an application as an anode material for solid oxide fuel cells based on various electrolytes. The purpose of the present investigation is to analyze morphology, microstructure, and optical properties of deposited and annealed for one hour in the temperatures from 500 ºC to 900 ºC Ni/CeO2 multilayer thin films deposited by sputtering. The crystallographic structure of thin films was investigated by X-ray diffraction. The morphology of the film cross-section was investigated with scanning electron microscope. The elemental analysis of samples was investigated by energy-dispersive X-ray spectroscopy. The fitting of the optical reflectance data was made using Abeles matrix method that is used for the design of interference coatings. The film cross-section of the post-annealed samples consisted of four layers. The first CeO2 layer (on Si had the same fine columnar structure with no features of Ni intermixing. The part of Ni (middle-layer after annealing was converted to NiO with grain size exceeding 100 nm. The CeO2 layer deposited on Ni was divided into two layers. Lower layer had small grains not exceeding 25 nm and consisting of NiO and CeO2 mixture. Upper layer consisted of CeO2 columns with approximate thickness of 50 nm. Ni sample annealed at 600 ºC was fully oxidized. The NiO thickness and refraction index were almost steady after annealing in various temperatures. The approximation of experimental reflectance data was successful only for the samples with one transparent homogeneous layer. The reflectance of the Ni/CeO2 samples annealed at intermediate temperatures could not be fitted using one-layer or three-layer model. That may show that a simplified model could not be implemented.  The real system has complicated distribution of refraction index. DOI: http://dx.doi.org/10.5755/j01.ms.19.4.3073

  15. Electron spectroscopic investigation of metal-insulator transition in Ce1-SrTiO3

    Indian Academy of Sciences (India)

    U Manju; S R Krishnakumar; Sugata Ray; S Raj; M Onoda; C Carbone; D D Sarma

    2003-10-01

    We have carried out detailed electron spectroscopic investigation of Ce1-SrTiO3 exhibiting insulator-metal transition with . Core level X-ray photoelectron spectra of Ce 3 as well as resonant photoemission spectra obtained at the Ce 4 → 4 resonant absorption threshold establish Ce as being in the trivalent state throughout the series. Using the `off-resonance’ condition for Ce 4 states, we obtain the Ti 3 dominated spectral features close to , exhibiting clear signatures of coherent and incoherent peaks. We discuss the implications of our findings in relation to the metal-insulator transition observed in this series of compounds.

  16. Violet/blue photoluminescence from CeO2 thin film

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    CeO2 thin film was fabricated by dual ion beam epitaxial technique. The violet/blue PL at room temperature and lower temperature was observed from the CeO2 thin film. After the analysis of crystal structure and valence in the compound was carried out by the XRD and XPS technique, it was inferred that the origin of CeO2 PL was due to the electrons transition from Ce4f band to O2p band and the defect level to O2p band. And these defects levels were located in the range of 1 eV around Ce4f band.

  17. Influence of CeO_2 on scintillating properties of Tb~(3+)-doped silicate glasses

    Institute of Scientific and Technical Information of China (English)

    孙心瑗; 顾牡; 张敏; 黄世明

    2010-01-01

    A series of Tb3+-,Ce3+-doped,and Tb3+/Ce3+-codoped silicate glasses were synthesized by melt-quenching technique.Some properties of the investigated glasses were characterized by X-ray photoelectron spectroscopy(XPS),photoluminescence(PL),X-ray excited luminescence(XEL) and thermoluminescence(TL) spectra.The result of XPS revealed that both Ce3+ and Ce4+ ions coexisted in these silicate glasses,and energy transfer from Ce3+ to Tb3+ ions was observed under UV excitation.However,under X-ray excitation the XEL...

  18. Sequential microfluidic flow synthesis of CePO4 nanorods decorated with emission tunable quantum dots.

    Science.gov (United States)

    Fang, Jie; Evans, Cameron W; Willis, Glen J; Sherwood, David; Guo, Yanglong; Lu, Guanzhong; Raston, Colin L; Iyer, K Swaminathan

    2010-10-07

    CePO(4) nanorods decorated with QDs (QDs@CePO(4)) can be prepared in a sequential, aqueous procedure under continuous flow using a rotating tube processor and a narrow channel reactor. The emission from the QD@CePO(4) is tunable from green to red by simply adjusting the feeding rate, which in turn regulates the particle size of the QDs. The Ce(3+) ions in the QDs@CePO(4) serve as an efficient fluorescence resonance energy transfer (FRET) donor, effectively enlarging the Stokes shift of the QDs.

  19. The application of Ce-Zr oxide solid solution to oxygen storage promoters in automotive catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ozawa, Msakuni (Toyota Central Research and Development Labs. Inc., Aichi (Japan)); Kimura, Mareo (Toyota Central Research and Development Labs. Inc., Aichi (Japan)); Isogai, Akio (Toyota Central Research and Development Labs. Inc., Aichi (Japan))

    1993-03-15

    The complex oxides in the CeO[sub 2]-ZrO[sub 2] system were examined for the improvement of oxygen storage capacity in automotive catalysts. The formation of Ce-Zr oxide solid solution improved the thermal stability and activity of CeO[sub 2]. The Ce-Zr addition enhanced the removal activity for CO, NO[sub x] and hydrocarbons under dynamic air-fuel ratio condition. The automotive catalyst was designed and developed through research on the oxides in the CeO[sub 2]-ZrO[sub 2] system. (orig.)

  20. Nouvelle espèce des Syntomides (Lepidoptera Heterocera)

    NARCIS (Netherlands)

    Snellen, P.C.T.

    1886-01-01

    Quatre mâles frais et bien conservés de 58—64 millim. d’envergure. Cette nouvelle espèce, gigantesque pour une Syntomide, appartient au genre Automolis, tel qu’il a été défini par Herrich-Schäffer, dans son ouvrage »Sammlung aussereuropäischer Schmetterlinge” (p. 21); le nom est emprunté au bien con

  1. Burstein Moss effect in nanocrystalline CaS : Ce

    Indian Academy of Sciences (India)

    Geeta Sharma; Puja Chawla; S P Lochab; Nafa Singh

    2011-07-01

    The nanocrystalline CaS : Ce nanophosphors are synthesized by wet chemical co-precipitation method. The particles possess an average size of 10 nm as calculated using Debye–Scherrer formula. The particle size and the crystalline nature of the formed nanoparticles are confirmed by TEM micrograph. The optical studies are carried out using UV–Vis absorption spectroscopy. The absorption edge is found to show blue shift with increasing cerium concentration. The shift may be attributed to Burstein Moss effect.

  2. Contamination in LaCl3:Ce Scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Milbrath, Brian D.; McIntyre, Justin I.; Runkle, Robert C.; Smith, Leon E.

    2005-12-01

    The gamma-, beta-, and x-ray-contamination in LaCl3:Ce scintillators due to the presence of the naturally occurring radioisotope La-138 is discussed. As the size of lanthanum halide crystals grows towards commercially useful sizes, and the effects of alpha-contamination due to Ac-227 has been substantially reduced, the effects of La-138 in background and low-count spectra become more problematic. The crystal's performance in high neutron fluxes is also examined.

  3. Itinerant magnetism in CeRh3B2

    OpenAIRE

    1989-01-01

    Spin-polarized energy-band calculations, including spin-orbit coupling in the band Hamiltonian, have been performed on CeRh3B2. Good agreement is obtained between theory and experiment concerning the magnetic moment. It is also found that the magnetic moment varies strongly with volume and from this a qualitative explanation for the anomalously high Curie temperature of the compound is proposed. Furthermore, the spin density is found to be highly nonspherical.

  4. Itinerant magnetism in CeRh3B2

    Science.gov (United States)

    Eriksson, Olle; Johansson, Börje; Brooks, M. S. S.; Skriver, H. L.; Sjöström, Jörgen

    1989-09-01

    Spin-polarized energy-band calculations, including spin-orbit coupling in the band Hamiltonian, have been performed on CeRh3B2. Good agreement is obtained between theory and experiment concerning the magnetic moment. It is also found that the magnetic moment varies strongly with volume and from this a qualitative explanation for the anomalously high Curie temperature of the compound is proposed. Furthermore, the spin density is found to be highly nonspherical.

  5. Structure of ∼130 nuclei in La–Ce region

    Indian Academy of Sciences (India)

    Tumpa Bhattacharjee

    2010-07-01

    The variety of shapes and structures, observed in light rare earth $A ∼ 130$ nuclei, have been discussed in view of different angular momentum coupling schemes and their interplay that comes into effect at high spin. The = 79 and 80 isotopes in La–Ce region, produced via fusion evaporation reaction, have been studied using the Indian National Gamma Array (INGA) consisting of 18 clover HPGe detectors. Two nearly degenerate = 1 bands have been observed at high spin of 137Ce and a triaxial deformation of = ± 30°$ has been assigned to the bands, from the total Routhian surface (TRS) calculations. The high-spin candidates of the yrast band of 138Ce show signature splitting both in energy and (1)/(2) values. The bandcrossing due to the alignment of a pair of ℎ11/2 proton particles has been conjectured at ħ ω ∼ 0.3 MeV, from the single-particle Routhians obtained from TRS calculations. Lifetime measurements by Doppler shift attenuation method (DSAM) has been carried out and from the estimated reduced transition probability (1), the = 1 band in 138Ce has been characterized as a magnetic rotation (MR) band. The rise in the values of (1), for the higher spin candidates of the band, has been conjectured as the reopening of a different shear at the top of the Band B1. The characteristic of the MR bands in ∼ 130 region has been discussed in the light of a phenomenological calculation and compared to the MR bands in other mass regions.

  6. 超便携PC亮相CeBit

    Institute of Scientific and Technical Information of China (English)

    胡纲

    2006-01-01

    微软终于在德国汉诺威举行的CeBIT 2006科技展示上揭开了所谓Origami项目的神秘面纱:原来这是一种使用Windows XP Tablet操作系统,具有触摸屏和无线连接的超便携PC (UltraMobile PC,简称UMPC)。

  7. 水热法制备高纯超细CeO2-ZrO2复合氧化物%Preparation of High Purity and Superfine CeO2-ZrO2 by Hydrothermal Method

    Institute of Scientific and Technical Information of China (English)

    郑育英; 黄慧民; 邓淑华; 李大光; 余双平

    2005-01-01

    Superfine composite powders of CeO2-ZrO2 (CZ) and CeO2-ZrO2-La2O3 (CZL) were prepared by hydrothermal method. The effects of pH ,temperature and time for hydrothermal process on the performance of the resulting powders were studied. The optimized reaction parameters were on follows: the precursor's pH≈9.0, hydrothermal temperature of 200 ℃ holding for 2 h. Thermal stable powders with average particle size smaller than 10 nm and specific surface area of 171 m2·g-1 were obtained. A BET specific surface area was still at 44 m2·g-1 after calcination at 1 000 ℃ for 6 hours.

  8. Collective magnetic response of CeO2 nanoparticles

    Science.gov (United States)

    Coey, Michael; Ackland, Karl; Venkatesan, Munuswamy; Sen, Siddhartha

    2016-07-01

    The magnetism of nanoparticles and thin films of wide-bandgap oxides that include no magnetic cations is an unsolved puzzle. Progress has been hampered by both the irreproducibility of much of the experimental data, and the lack of any generally accepted theoretical explanation. The characteristic signature is a virtually anhysteretic, temperature-independent magnetization curve that saturates in an applied field that is several orders of magnitude greater than the magnetization. It would seem as if a tiny volume fraction, sugar or latex microspheres. The saturation magnetization, Ms ≍ 60 A m-1 for compact samples, is maximized by 1 wt% lanthanum doping. Dispersing the CeO2 nanopowder reduces its magnetic moment by up to an order of magnitude, and there is a characteristic length scale of order 100 nm for the magnetism to appear in CeO2 nanoparticle clusters. The phenomenon is explained in terms of a giant orbital paramagnetism that appears in coherent mesoscopic domains due to resonant interaction with zero-point fluctuations of the vacuum electromagnetic field. The theory explains the observed temperature-independent magnetization curve and its doping and dispersion dependence, based on a length scale of 300 nm that corresponds to the wavelength of a maximum in the ultraviolet absorption spectrum of the magnetic CeO2 nanoparticles. The coherent domains occupy roughly 10% of the sample volume.

  9. Magnetoresistance in CePtSn under high hydrostatic pressures

    Energy Technology Data Exchange (ETDEWEB)

    Misek, M. [Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Ke Karlovu 5, 121 16 Prague (Czech Republic)], E-mail: martinmisek@hotmail.com; Prokleska, J.; Javorsky, P.; Sechovsky, V. [Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Ke Karlovu 5, 121 16 Prague (Czech Republic)

    2009-07-01

    We report the evolution of magnetic-history dependent antiferromagnetic phases in CePtSn. We concentrate on the magnetoresistance in magnetic fields up to 14 T applied along the crystallographic b-axis, measured on a CePtSn single crystal subjected to hydrostatic pressure (p {<=} 2.2 GPa) generated in a double-layered CuBe/NiCrAl piston cylinder cell. We observe a gradual increase of the critical field B{sub c}{sup LF} of the low field (LF) transition up to {approx}1.2 GPa where only one transition is observed at {approx}11.5 T. For pressures above 1.2 GPa we observe two transitions again and B{sub c}{sup LF} decreases with further increasing pressure to reach B{sub c}{sup LF}{approx}7.5T at 2.5 GPa. The position of the high field (HF) transition remains almost unaffected by applied pressure. A scenario considering the spin-slip AF structure in CePtSn is briefly discussed.

  10. Optical properties of CeO2 thin films

    Indian Academy of Sciences (India)

    S Debnath; M R Islam; M S R Khan

    2007-08-01

    Cerium oxide (CeO2) thin films have been prepared by electron beam evaporation technique onto glass substrate at a pressure of about 6 × 10-6 Torr. The thickness of CeO2 films ranges from 140–180 nm. The optical properties of cerium oxide films are studied in the wavelength range of 200–850 nm. The film is highly transparent in the visible region. It is also observed that the film has low reflectance in the ultra-violet region. The optical band gap of the film is determined and is found to decrease with the increase of film thickness. The values of absorption coefficient, extinction coefficient, refractive index, dielectric constant, phase angle and loss angle have been calculated from the optical measurements. The X-ray diffraction of the film showed that the film is crystalline in nature. The crystallite size of CeO2 films have been evaluated and found to be small. The experimental -values of the film agreed closely with the standard values.

  11. NMR study of CeTe at low temperatures

    Science.gov (United States)

    Hinderer, J.; Weyeneth, S. M.; Weller, M.; Gavilano, J. L.; Felder, E.; Hulliger, F.; Ott, H. R.

    2006-05-01

    We present 125Te NMR measurements on CeTe powder at temperatures between 1 and 150 K and in magnetic fields between 5 and 8 T. CeTe is a rocksalt-type intermetallic compound. It orders antiferromagnetically at TN≈2.2 K with a much reduced ordered moment [H.R. Ott, J.K. Kjems, F. Hulliger, Phys. Rev. Lett. 42 20 (1979) 1378]. From our low-temperature NMR spectra we infer the presence of at least three inequivalent Te sites at low temperatures. Considering the crystal structure this result is completely unexpected. The linewidths and the Knight shifts of the individual lines are significantly different and increase substantially with decreasing temperature. They follow the temperature dependence of the magnetic susceptibility above 20 K. Above TN, hyperfine fields of 1.6, 0.8 and 0.0 T at the three Te sites per Bohr magneton of Ce moment are deduced from Knight shift vs. magnetic susceptibility data. These values are typical for transferred hyperfine fields via conduction electrons.

  12. Alumina/Ce-Tzp Functionally Graded Materials by Electrophoretic Deposition

    Institute of Scientific and Technical Information of China (English)

    C.Zhao, J.Vleugels; O.Van Der Biest

    2000-01-01

    Cylindrical Al2O3/Ce-TZP functionally graded composites were fabricated by electrophoretic deposition and pressureless sintering in air. A continuous change in composition was realized by changing the composition of the suspension during deposition. In order to achieve full densification, a temperature above 1550℃ was necessary. The resultant FGM cylinder with a diameter of 5.6 mm shows the following structure: a central hole with a diameter less than 0.5 mm, a tough Ce-ZrO2 core with a diameter of about 3 mm, a gradient layer of about 1 mm, and a hard Al2O3-rich surface layer. The Ce-ZrO2 core has a Vickers hardness between 10and 11 GPa and an excellent toughness (>10 MPa√m). In the gradient layer, hardness and toughness vary continuously along the radius. The surface layer has a hardness of 15.5 GPa and a modest toughness of 2.5MPa√m.

  13. Synthesis and Characterization of Ce-Containing MCM-41

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ SUMMARY. The cerium-containing MCM-41 (Ce-MCM-41) has been synthesized with size in the micrometer range by direct hydrothermal method. Transmission electron microscopy shows the regular hexagonal array of uniform channel characteristics of MCM-41. Five peaks were detected in the lov-angle XRD patterns,an interplanar spacing d100 = 40.6 A was obtained that can be indexed on a hexagonal unit cell with a0 = 46.9 A. Nitrogen adsorption isotherm at 77 K revealed a surface area of 920 m2/g, pore size of 26.2 A and wall thickness of 18.1 A. A cell contraction of 2.6 A upon calcination was observed. The spectroscopic studies indicate that the synthesized sample is with MCM-41 structure and Ce is in the framework position. A weak Lewis acidity was indicated by infrared spectra of pyridine adsorption. The synthesized Ce-MCM-41 exhibits fairly catalytic activity for the NO reduction by CO.

  14. Synthesis and Characterization of Ce-Containing MCM-41

    Institute of Scientific and Technical Information of China (English)

    CHIEN; ShuHua

    2001-01-01

    SUMMARY.  The cerium-containing MCM-41 (Ce-MCM-41) has been synthesized with size in the micrometer range by direct hydrothermal method. Transmission electron microscopy shows the regular hexagonal array of uniform channel characteristics of MCM-41. Five peaks were detected in the lov-angle XRD patterns,an interplanar spacing d100 = 40.6 A was obtained that can be indexed on a hexagonal unit cell with a0 = 46.9 A. Nitrogen adsorption isotherm at 77 K revealed a surface area of 920 m2/g, pore size of 26.2 A and wall thickness of 18.1 A. A cell contraction of 2.6 A upon calcination was observed. The spectroscopic studies indicate that the synthesized sample is with MCM-41 structure and Ce is in the framework position. A weak Lewis acidity was indicated by infrared spectra of pyridine adsorption. The synthesized Ce-MCM-41 exhibits fairly catalytic activity for the NO reduction by CO.  ……

  15. Unusual Compression Behavior of Nanocrystalline CeO2

    Science.gov (United States)

    Wang, Qiming; He, Duanwei; Peng, Fang; Lei, Li; Liu, Pingping; Yin, Shuai; Wang, Pei; Xu, Chao; Liu, Jing

    2014-01-01

    The x-ray diffraction study of 12 nm CeO2 was carried out up to ~40 GPa using an angle dispersive synchrotron-radiation in a diamond-anvil cell with different pressure transmitting medium (PTM) (4:1 methanol: ethanol mixture, silicone oil and none) at room temperature. While the cubic fluorite-type structure CeO2 was retained to the highest pressure, there is progressive broadening and intensity reduction of the reflections with increasing pressure. At pressures above 12 GPa, an unusual change in the compression curve was detected in all experiments. Significantly, apparent negative volume compressibility was observed at P = 18–27 GPa with silicone oil as PTM, however it was not detected in other circumstances. The expansion of the unit cell volume of cubic CeO2 was about 1% at pressures of 15–27 GPa. To explain this abnormal phenomenon, a dual structure model (hard amorphous shell and relatively soft crystalline core) has been proposed. PMID:24658049

  16. Radon gamma-ray spectrometry with YAP:Ce scintillator

    CERN Document Server

    Plastino, W; De Notaristefani, F

    2002-01-01

    The detection properties of a YAP:Ce scintillator (YAlO sub 3 :Ce crystal) optically coupled to a Hamamatsu H5784 photomultiplier with standard bialkali photocathode have been analyzed. In particular, the application to radon and radon-daughters gamma-ray spectrometry was investigated. The crystal response has been studied under severe extreme conditions to simulate environments of geophysical interest, particularly those found in geothermal and volcanic areas. Tests in water up to a temperature of 100 deg.C and in acids solutions such as HCl (37%), H sub 2 SO sub 4 (48%) and HNO sub 3 (65%) have been performed. The measurements with standard radon sources provided by the National Institute for Metrology of Ionizing Radiations (ENEA) have emphasized the non-hygroscopic properties of the scintillator and a small dependence of the light yield on temperature and HNO sub 3. The data collected in this first step of our research have pointed out that the YAP:Ce scintillator can allow high response stability for rad...

  17. Preparation and catalytic behavior of CeO2 nanoparticles on Al2O3 crystal

    Science.gov (United States)

    Hattori, Takashi; Kobayashi, Katsutoshi; Ozawa, Masakuni

    2017-01-01

    In this work, we examined the preparation, morphology, and catalytic behavior of CeO2 nanoparticles (NPs) on Al2O3(0001) crystal substrates. A CeO2 NP layer was prepared by the dipping method using a CeO2 nanocrystal colloid solution. Even after heat treatment at 1000 °C, the CeO2 NP layer maintained the granular morphology of CeO2 with a grain diameter of less than 40 nm. CeO2 NPs on an Al2O3 crystal showed higher oxidation activity for gaseous hydrogen at moderate temperatures and enhanced oxygen release properties of CeO2, compared with CeO2 powder. This was due to the highly dispersed CeO2 NPs and the interaction between CeO2 NPs and Al2O3; this clarified the importance of the Al2O3 support for the CeO2 catalyst.

  18. Enhancement of room temperature ferromagnetic behavior of rf sputtered Ni-CeO2 thin films

    Science.gov (United States)

    Murugan, R.; Vijayaprasath, G.; Mahalingam, T.; Ravi, G.

    2016-12-01

    Ni-doped CeO2 thin films were prepared under Ar+ atmosphere on glass substrates using rf magnetron sputtering. To assess the properties of the prepared thin films, the influence of various amounts of Ni dopant on structural, morphological, optical, vibrational, compositional and magnetic properties of the CeO2 films were studied by using X-Ray diffraction (XRD), atomic force microscope (AFM), photoluminescence (PL), micro-Raman, X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). XRD patterns for all the samples revealed the expected CeO2 cubic fluorite-type structure and Ni ions were uniformly distributed in the samples. AFM images of the prepared samples indicate high dense, columnar structure with uniform distribution of CeO2. Room-temperature photoluminescence (PL) and micro-Raman spectroscopic studies revealed an increase of oxygen vacancies with higher concentration of Ni in CeO2. XPS results confirm the presence of Ni2p, O1s and Ce and depict that cerium is present as both Ce4+ and Ce3+ oxidation states in Ce1-xNixO2 (x = 15%) thin film. Field dependent magnetization measurements revealed a paramagnetic behavior for pure CeO2, while a ferromagnetic behavior appeared when Ni is doped in CeO2 films. Doping dependent magnetization measurements suggest that the observed ferromagnetism is due to the presence of metallic Ni clusters with nanometric size and broad size distribution.

  19. Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting

    Science.gov (United States)

    Wieg, A. T.; Penilla, E. H.; Hardin, C. L.; Kodera, Y.; Garay, J. E.

    2016-12-01

    We introduce high thermal conductivity aluminum nitride (AlN) as a transparent ceramic host for Ce3+, a well-known active ion dopant. We show that the Ce:AlN ceramics have overlapping photoluminescent (PL) emission peaks that cover almost the entire visible range resulting in a white appearance under 375 nm excitation without the need for color mixing. The PL is due to a combination of intrinsic AlN defect complexes and Ce3+ electronic transitions. Importantly, the peak intensities can be tuned by varying the Ce concentration and processing parameters, causing different shades of white light without the need for multiple phosphors or light sources. The Commission Internationale de l'Eclairage coordinates calculated from the measured spectra confirm white light emission. In addition, we demonstrate the viability of laser driven white light emission by coupling the Ce:AlN to a readily available frequency tripled Nd-YAG laser emitting at 355 nm. The high thermal conductivity of these ceramic down-converters holds significant promise for producing higher power white light sources than those available today.

  20. Synthesis and Characterization of CeO2-SiO2 Nanoparticles by Microwave-Assisted Irradiation Method for Photocatalytic Oxidation of Methylene Blue Dye

    Directory of Open Access Journals (Sweden)

    R. M. Mohamed

    2012-01-01

    Full Text Available CeO2-SiO2 nanoparticles were synthesized for the first time by a facile microwave-assisted irradiation process. The effect of irradiation time of microwave was studied. The materials were characterized by N2 adsorption, XRD, UV-vis/DR, and TEM. All solids showed mesoporous textures with high surface areas, relatively small pore size diameters, and large pore volume. The X-ray diffraction results indicated that the as-synthesized nanoparticles exhibited cubic CeO2 without impurities and amorphous silica. The transmission electron microscopy (TEM images revealed that the particle size of CeO2-SiO2 nanoparticles, which were prepared by microwave method for 30 min irradiation times, was around 8 nm. The photocatalytic activities were evaluated by the decomposition of methylene blue dye under UV light irradiations. The results showed that the irradiation under the microwave produced CeO2-SiO2 nanoparticles, which have the best crystallinity under a shorter irradiation time. This indicates that the introduction of the microwave really can save energy and time with faster kinetics of crystallization. The sample prepared by 30 min microwave irradiation time exhibited the highest photocatalytic activity. The photocatalytic activity of CeO2-SiO2 nanoparticles, which were prepared by 30 min irradiation times was found to have better performance than commercial reference P25.

  1. Catalytic oxidation of Hg(0) by MnOx-CeO2/γ-Al2O3 catalyst at low temperatures.

    Science.gov (United States)

    Wang, Pengying; Su, Sheng; Xiang, Jun; You, Huawei; Cao, Fan; Sun, Lushi; Hu, Song; Zhang, Yun

    2014-04-01

    MnOx-CeO2/γ-Al2O3 (MnCe) selective catalytic reduction (SCR) catalysts prepared by sol-gel method were employed for low-temperature Hg(0) oxidation on a fixed-bed experimental setup. BET, XRD and XPS were used to characterize the catalysts. MnCe catalysts exhibited high Hg(0) oxidation activity at low temperatures (100-250 °C) under the simulated flue gas (O2, CO2, NO, SO2, HCl, H2O and balanced with N2). Only a small decrease in mercury oxidation was observed in the presence of 1200 ppm SO2, which proved that the addition of Ce helped resist SO2 poisoning. An enhancing effect of NO was observed due to the formation of multi-activity NOx species. The presence of HCl alone had excellent Hg(0) oxidation ability, while 10 ppm HCl plus 5% O2 further increased Hg(0) oxidation efficiency to 100%. Hg(0) oxidation on the MnCe catalyst surface followed the Langmiur-Hinshelwood mechanism, where reactions took place between the adsorbed active species and adsorbed Hg(0) to form Hg(2+). NH3 competed with Hg(0) for active sites on the catalyst surface, hence inhibiting Hg(0) oxidation. This study shows the feasibility of a single-step process integrating low-temperature SCR and Hg(0) oxidation from the coal combustion flue gas.

  2. Ultrafast pump-probe spectroscopy studies of CeO2 thin film deposited on Ni-W substrate by RF magnetron sputtering

    Science.gov (United States)

    Singh, Preetam; Srivatsa, K. M. K.; Jewariya, Mukesh

    2016-08-01

    This study presents the first investigation of rapid dynamical processes that occur in pure CeO2 thin film, using ultra fast pump-probe spectroscopy at room temperature. For this purpose we have used a single (200) oriented CeO2 film deposited on biaxially textured Ni-W substrate by RF magnetron sputtering technique. The ultrafast transient spectra show initial sharp rise transition followed by an exponential photon decay. This rise time is about 10 ps irrespective of the probe wavelengths range 500-800 nm. The initial decay constant (τ) at 500 nm probe wavelength is found to be 171 ps, while at 800 nm probe wavelength it is 107.5 ps. The ultrafast absorption spectra show two absorption peaks at 745 and 800 nm, and are attributed to the electronic transitions from 2F7/2-2F5/2 and 1S0-1F3 respectively. The relatively high intensity absorption peak at 745 nm indicates dominant f-f electronic transition. Further, the absorption peak at 745 nm splits into two distinct peaks with respect to delay time, and is attributed to the charge transfer in between Ce4+ and Ce3+ ions. These results indicate that CeO2 itself is a potential candidate and can be used for optical applications.

  3. Superparamagnetic Fe3O4-PEG2K-FA@Ce6 Nanoprobes for in Vivo Dual-mode Imaging and Targeted Photodynamic Therapy

    Science.gov (United States)

    Yin, Ting; Huang, Peng; Gao, Guo; Shapter, Joseph G.; Shen, Yulan; Sun, Rongjin; Yue, Caixia; Zhang, Chunlei; Liu, Yanlei; Zhou, Sui; Cui, Daxiang

    2016-11-01

    The development of targeted nanoprobes is a promising approach to cancer diagnostics and therapy. In the present work, a novel multifunctional photo/magnet-diagnostic nanoprobe (MNPs-PEG2K-FA@Ce6) has been developed. This nanoprobe is built using folic acid (FA), bifunctional polyethylene glycol (PEG2K) and photosensitizer chlorin e6 (Ce6). The MNPs-PEG2K-FA@Ce6 nanoprobes are superparamagnetic, can be synthesized on a large scale by a one-pot hydrothermal process without further surface modification and are stable in an aqueous environment for eight months. Compared with free Ce6 nanoprobes in vitro studies, the MNPs-PEG2K-FA@Ce6 nanoprobes significantly enhance cellular uptake efficiency and promote the effectiveness of photodynamic therapy (PDT) with the assistance of 633 nm laser irradiation. The unique nanoprobes show superior penetration and a retention time of more than six days with less accumulation in the liver allowing highly effective tumor recognition and monitoring. Additionally, there was little damage to healthy organs or tissues. These exciting new nanoprobes could be potential building blocks to develop new clinical therapies and translational medicine.

  4. Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting

    Directory of Open Access Journals (Sweden)

    A. T. Wieg

    2016-12-01

    Full Text Available We introduce high thermal conductivity aluminum nitride (AlN as a transparent ceramic host for Ce3+, a well-known active ion dopant. We show that the Ce:AlN ceramics have overlapping photoluminescent (PL emission peaks that cover almost the entire visible range resulting in a white appearance under 375 nm excitation without the need for color mixing. The PL is due to a combination of intrinsic AlN defect complexes and Ce3+ electronic transitions. Importantly, the peak intensities can be tuned by varying the Ce concentration and processing parameters, causing different shades of white light without the need for multiple phosphors or light sources. The Commission Internationale de l’Eclairage coordinates calculated from the measured spectra confirm white light emission. In addition, we demonstrate the viability of laser driven white light emission by coupling the Ce:AlN to a readily available frequency tripled Nd-YAG laser emitting at 355 nm. The high thermal conductivity of these ceramic down-converters holds significant promise for producing higher power white light sources than those available today.

  5. Temperature Programmed Reduction Studies on CeO2-Containing Catalysts

    Institute of Scientific and Technical Information of China (English)

    Noriyoshi Kakuta; Harunobu Ohkita; Takanori Mizushima

    2004-01-01

    Temperature programmed reduction (TPR) study was carried out for CeO2/Al2O3 and CeO2/ZrO2 catalysts to evaluate oxygen storage property induced by a facile redox cycling of Ce ion. The CeO2/ZrO2 catalyst possesses excellent oxygen storage activity at 373 K after reduction above 1173 K although the oxygen storage of CeO2/Al2O3 catalyst after reduction above 1173 K is poor because of the formation of CeAlO3. Consequently, the oxygen storage on the CeO2/ZrO2 catalyst smoothly occurs from low temperatures when the catalyst is reduced even at high temperatures.

  6. Interaction at Pt-CeO2 Contact Interface over Pt/CeO2/SBA-15 Catalyst%Pt/CeO2/SBA-15催化剂上Pt-CeO2接触界面的相互作用

    Institute of Scientific and Technical Information of China (English)

    毕亚东; 张微; 徐恒泳; 李文钊

    2009-01-01

    通过沉积沉淀法(Deposition precipitation,DP)将CeO2纳米粒子高度分散在SBA-15分子筛上,进一步采用浸渍法负载Pt后制备了 Pt/CeO2/SBA-DP催化剂.紫外-可见漫反射光谱分析表明,在Pt/CeO2/SBA-DP催化剂上可以形成更多的Pt-CeO2接触界面,有利于从CeO2到Pt的电子转移过程.CO程序升温还原(CO-TPR)测试证实,Pt/CeO2/SBA-DP催化剂上CeO2表面氧物种具有较高的还原能力.

  7. Investigation of the isothermal section of the Ce-Co-Al ternary system at 573 K

    Institute of Scientific and Technical Information of China (English)

    YAO Qingrong; ZHOU Huaiying; TANG Chengying; PAN Shunkang

    2011-01-01

    The isothermal section of the Ce-Co-Al ternary system at 573 K was investigated by X-ray powder diffraction (XRD),scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) techniques.It consisted of 19 single-phase regions,46 two-phase regions and 25 three-phase regions.Four ternary compounds,namely CeCoAl,Ce2Co15Al2,CeCoAl4,CeCo2Al8,were confirmed in this system.At 573 K,the maximum solid solubilities of Co in CeAl2 and A1 in CeCo2 were about 10.4 at.% and 10.0 at.%,respectively.The homogeneity range of CoAl phase extended from about 46.0 to 56.0 at.% Al.

  8. Ferromagnetic enhancement in the hexagonal Ce(Rh1-xIrx)3B2 system

    Science.gov (United States)

    Hsu, S. W.; Ku, H. C.

    1988-08-01

    Electrical resistivity, magnetization, and crystallographic measurements have been carried out for the pseudoternary system Ce(Rh1-xIrx)3B2. A single-phase hexagonal CeCo3B2-type structure persists from x=0.0 up to x0.95. The ferromagnetic Curie temperature Tc is enhanced from 115 K for CeRh3B2 to 125 K for Ce(Rh0.8Ir0.2)32, then decreases slowly to 118 K at x=0.5 before decreasing sharply to 69 K at x=0.67, even though the magnetic moment per Ce ion decreases monotonically with increasing Ir substitution. The Tc of 125 K in Ce(Rh0.8Ir0.2)3B2 is the highest magnetic-ordering temperature observed so far for all Ce-based systems with nonmagnetic constituents.

  9. Energy transfer from Ce~(3+) to Tb~(3+) and Eu~(3+) in zinc phosphate glasses

    Institute of Scientific and Technical Information of China (English)

    马崇庚; 江莎; 周贤菊

    2010-01-01

    Ce3+,Eu3+ and Tb3+ singly doped and Ce3+/Eu3+ and Ce3+/Tb3+ co-doped zinc phosphate glasses were prepared by sintering P2O5,ZnO,Ce2(C2O4)3·10H2O and Eu2O3/Tb4O7 mixtures at 1200 °C in the air for 2 h and then annealing at 450 °C for 10 h.The obtained glasses were homogeneous and transparent.The glasses without Ce3+ were colorless and those with Ce3+ showed slightly yellow.The singly doped glasses showed strong emissions and excitations from doped trivalent rare earth ions.Strong energy transfer from Ce3+ to...

  10. Generation and reactivity of putative support systems, Ce-Al neutral binary oxide nanoclusters: CO oxidation and C–H bond activation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhe-Chen; Yin, Shi; Bernstein, Elliot R., E-mail: erb@lamar.colostate.edu [Department of Chemistry and NSF ERC for Extreme Ultraviolet Science and Technology, Colorado State University, Fort Collins, Colorado 80523 (United States)

    2013-11-21

    Both ceria (CeO{sub 2}) and alumina (Al{sub 2}O{sub 3}) are very important catalyst support materials. Neutral binary oxide nanoclusters (NBONCs), Ce{sub x}Al{sub y}O{sub z}, are generated and detected in the gas phase and their reactivity with carbon monoxide (CO) and butane (C{sub 4}H{sub 10}) is studied. The very active species CeAlO{sub 4}{sup •} can react with CO and butane via O atom transfer (OAT) and H atom transfer (HAT), respectively. Other Ce{sub x}Al{sub y}O{sub z} NBONCs do not show reactivities toward CO and C{sub 4}H{sub 10}. The structures, as well as the reactivities, of Ce{sub x}Al{sub y}O{sub z} NBONCs are studied theoretically employing density functional theory (DFT) calculations. The ground state CeAlO{sub 4}{sup •} NBONC possesses a kite-shaped structure with an O{sub t}CeO{sub b}O{sub b}AlO{sub t} configuration (O{sub t}, terminal oxygen; O{sub b}, bridging oxygen). An unpaired electron is localized on the O{sub t} atom of the AlO{sub t} moiety rather than the CeO{sub t} moiety: this O{sub t} centered radical moiety plays a very important role for the reactivity of the CeAlO{sub 4}{sup •} NBONC. The reactivities of Ce{sub 2}O{sub 4}, CeAlO{sub 4}{sup •}, and Al{sub 2}O{sub 4} toward CO are compared, emphasizing the importance of a spin-localized terminal oxygen for these reactions. Intramolecular charge distributions do not appear to play a role in the reactivities of these neutral clusters, but could be important for charged isoelectronic BONCs. DFT studies show that the reaction of CeAlO{sub 4}{sup •} with C{sub 4}H{sub 10} to form the CeAlO{sub 4}H•C{sub 4}H{sub 9}{sup •} encounter complex is barrierless. While HAT processes have been previously characterized for cationic and anionic oxide clusters, the reported study is the first observation of a HAT process supported by a ground state neutral oxide cluster. Mechanisms for catalytic oxidation of CO over surfaces of Al{sub x}O{sub y}/M{sub m}O{sub n} or M{sub m}O{sub n

  11. Structural Perceptions and Mechanical Evaluation of β-Ca3(PO4)2/c-CeO2 Composites with Preferential Occupancy of Ce(3+) and Ce(4).

    Science.gov (United States)

    Nandha Kumar, Ponnusamy; Mishra, Sandeep Kumar; Kannan, Sanjeevi

    2017-02-24

    The role of cerium in the formation of stable β-Ca3(PO4)2/c-CeO2 composites and their structural analysis with varied compositional ratios were investigated. The composite formation was attempted through an in situ precipitation technique, and the gradual structural changes during heat treatments to yield the pure form of β-Ca3(PO4)2/c-CeO2 composites was presented. The cerium was found in Ce(3+) and Ce(4+) oxidation states in composites. Ce(3+) prefers to occupy the Ca(2+)(1), Ca(2+)(2), and Ca(2+)(3) sites of β-Ca3(PO4)2, whereas, beyond the saturation occupancy limit, excess cerium prefers to crystallize in the form of thermodynamically stable cubic ceria (c-CeO2). A uniform expansion of the β-Ca3(PO4)2 unit cell and the delayed allotropic conversion of β-Ca3(PO4)2 → α-Ca3(PO4)2 have been detected due to the Ce(3+) occupancy at the β-Ca3(PO4)2 lattice. β-Ca3(PO4)2/c-CeO2 composites exhibited a steady upsurge in the mechanical properties with consistent enhancement of c-CeO2 content in the composites. The overall results from the investigation imply the appropriateness of the β-Ca3(PO4)2/c-CeO2 composites for applications in hard tissue replacements.

  12. CO catalytic oxidation over Au/CeO2 catalysts%Au/CeO2催化CO氧化反应行为研究

    Institute of Scientific and Technical Information of China (English)

    李卫力; 葛庆杰; 徐恒泳

    2016-01-01

    通过考察不同比表面积CeO2载体和催化剂预处理条件对Au/CeO2催化CO氧化反应性能的影响,研究了影响Au/CeO2催化活性的关键因素及催化剂表面氧活化行为和反应机理。结果表明,含有不同比表面积CeO2载体的Au/CeO2催化剂具有不同的CO氧化反应活性,其中以Au/CeO2-89.0的催化性能最佳。 O2预处理有利于催化剂的反应性能,而H2预处理则明显降低了催化剂的反应活性。载体CeO2的表面晶格氧可参与Au/CeO2表面的CO氧化反应,表面晶格氧和CO反应形成CO2并脱附后,形成氧空位,然后气相中的O2填补氧空位,重新形成晶格氧,形成氧化还原循环,维持反应的持续进行。%The influences of CeO2 supports with different surface areas and pretreatment conditions on the CO oxidation over the Au/CeO2 catalysts were investigated experimentally. Based on which, the key factors affecting the activity of catalyst and the surface oxygen activation behavior and reaction mechanism of the catalyst were discussed. Results shows that Au/CeO 2 catalysts with different CeO2 supports had different CO oxidation activities, among which Au/CeO2-89.0 exhibited the best. O2 pretreatment of Au/CeO2 could improve its catalytic activity while H2 pretreatment evidently decrease the catalytic activity. Lattice oxygen participates in the CO oxidation on the surface of Au/CeO2. Lattice oxygen reacts with adsorbed CO to form CO2, and then oxygen vacancies form on the catalyst surface. The oxygen vacancies could react with gas phase O2 to form lattice oxygen again. Such recycling keeps the running of CO oxidation over Au/CeO2 catalyst.

  13. Experimental and theoretical study about sulfur deactivation of Ni/ CeO{sub 2} and Rh/CeO{sub 2} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ocsachoque, Marco A., E-mail: ocmarco@quimica.unlp.edu.ar [Centro de Investigación y Desarrollo en Ciencias Aplicadas “Dr Jorge J. Ronco”, (CONICET, CCT La Plata), Departamento de Química, Facultad de Cs Exactas (UNLP), Calle 48 N° 257, 1900 La Plata (Argentina); Eugenio Russman, Juan I.; Irigoyen, Beatriz [Instituto de Tecnologías del Hidrógeno y Energías Sostenibles (ITHES), Departamento de Ingeniería Química, Facultad de Ingeniería (UBA), Buenos Aires (Argentina); Gazzoli, Delia [Dipartimento di Chimia, Universitá di Roma “La Sapienza”, Roma (Italy); González, María G. [Centro de Investigación y Desarrollo en Ciencias Aplicadas “Dr Jorge J. Ronco”, (CONICET, CCT La Plata), Departamento de Química, Facultad de Cs Exactas (UNLP), Calle 48 N° 257, 1900 La Plata (Argentina)

    2016-04-01

    Sulfur deactivation of Ni/CeO{sub 2} and Rh/CeO{sub 2} catalysts were examined through an experimental and theoretical study. These catalysts were characterized by N{sub 2} adsorption, X-ray diffraction, temperature programmed reaction, thermogravimetric analysis, Uv–visible spectroscopy and Raman spectroscopy, and tested under the methane dry reforming reaction in the presence of H{sub 2}S. On the other hand, different possible interactions of sulfur with Rh, Ni or surface sites of the CeO{sub 2} support were evaluated by performing energy calculations with the density functional theory (DFT). Overall, the results indicate that tolerance to sulfur of Rh/CeO{sub 2} catalyst is higher than that of Ni/CeO{sub 2} one. In this sense, TPR measurements show that reduction of CeO{sub 2} is promoted by the presence of Rh. This effect, probably caused by hydrogen spillover to CeO{sub 2} support during the reduction of RhO{sub x} species, could be linked to a high oxygen donation capacity of Rh/CeO{sub 2} catalysts. Accordingly, the O{sup 2−} species existing on Rh/CeO{sub 2} catalysts, revealed by Raman spectra of these samples, could favor sulfur oxidation and prevent Rh–S interactions. Likewise, the theoretical calculations show that desorption of S–O species from Rh/CeO{sub 2} system is more favorable than that from Ni/CeO{sub 2} one. Therefore, our experimental and theoretical study about sulfur deactivation of Ni and Rh supported on CeO{sub 2} allow us to postulate that Rh can help to desorb SO{sub x} species formed on the support, retarding sulfur poisoning of the Rh/CeO{sub 2} catalysts. - Highlights: • CeO{sub 2} support can act as a sacrifice trap decreasing sulfur poisoning. • Theoretical calculations indicate an important nickel affinity with sulfur. • Rh would favor desorption of S–O species formed on the support. • The O{sup 2−} species present on the Rh–CeO{sub 2} sample favor sulfur removal.

  14. Growth and chemical analysis of bulk Nd 2- xCe xCuO y single crystals

    Science.gov (United States)

    Zhigunov, D. I.; Shiryaev, S. V.; Kurnevich, L. A.; Kalanda, N. A.; Kurochkin, L. A.; Barilo, S. N.; Vashuk, V. V.; Smakhtin, L. A.

    1999-03-01

    Single crystals of Nd 2- xCe xCuO y (0< x<0.17) from a family of the electron-type superconductors have been grown using platinum crucibles by the top seeded solution growth technique. The structural quality of the crystals was examined by X-ray diffraction. The FWHM of the Bragg reflections for the best samples varies from 8 to 20 angular seconds. Full neutron activation analysis was carried out to determine the chemical composition of the as-grown crystals. Small cation stoichiometry deviations from ideal (NdCe)/Cu ratio are found as well as Pt substitution on the copper sublattice at a level up to 2 at% exists depending on growth conditions. The results of thermogravimetric measurements and further annealing of samples show that the problem of an oxygen reduction of large Nd 2- xCe xCuO y crystals is closely connected with inhomogeneity of anion distribution in the lattice possibly caused by non-optimal parameters for the reduction process and the level of impurities contamination. A three step reduction process which produces superconductivity with Tc˜19 K in single crystals thicker than 1 mm has been developed.

  15. Intrinsic Kinetics of Dimethyl Ether Synthesis from Plasma Activation of CO2 Hydrogenation over Cu-Fe-Ce/HZSM-5.

    Science.gov (United States)

    Su, Tongming; Zhou, Xinhui; Qin, Zuzeng; Ji, Hongbing

    2017-02-02

    CO2 is activated in a plasma reactor followed by hydrogenation over a Cu-Fe-Ce/HZSM-5 catalyst, and the intrinsic kinetics of the plasma catalytic process are studied. Compared with CO2 hydrogenation using Cu-Fe-Ce/HZSM-5 alone, the CO2 conversion and the dimethyl ether selectivity for the plasma catalytic process are increased by 16.3 %, and 10.1 %, respectively, indicating that the CO2 was activated by the plasma to promote hydrogenation. A study of the intrinsic kinetics shows that the activation energies of methanol formation, the reverse water-gas shift reaction, and methanol dehydration to dimethyl ether are 149.34, 75.47, and 73.18 kJ mol(-1) , respectively, which are lower than if Cu-Fe-Ce/HZSM-5 is used without plasma, indicating that the activation of CO2 in the plasma reduces the activation energy of the hydrogenation reaction and improves the yield of dimethyl ether.

  16. Easy peak tracking in CE-UV and CE-UV-ESI-MS by incorporating temperature-correlated mobility scaling

    DEFF Research Database (Denmark)

    Li, Bin; Petersen, Nickolaj Jacob; Andersen, Line Hvass;

    2013-01-01

    A simple data reconstruction technique in capillary electrophoresis - ultraviolet - electrospray ionization - mass spectrometry (CE-UV-ESI-MS) is presented to overcome the drift in mobilities caused by various factors compromising the reproducibility of such data, e.g. Joule heating effects...... and the variation in thermostatic control along the capillary, drift in electroosmotic flow (EOF) and the suction effect caused by the nebulizing gas in coaxial CE-MS interfaces. We present here a method to transform the traditional time-based electropherogram into the corresponding temperature-correlated mobility...... scale allowing tracking of analytes independent from capillary dimensions, electric field strengths, temperature control, and distance between the detectors. The main principle of this alignment is based on including the current in the mobility calculations and relating this to the initial electrical...

  17. Phase Formation and Thermal Stability of fcc (Fluorite) Ce1−xTbxO2−δ Solid Solutions

    NARCIS (Netherlands)

    Vries, de K.J.; Meng, G-Y.

    1998-01-01

    Ce1−xTbxO2−δ solid solutions (x = 0.3, 0.4, and 0.5) were synthesized by a coprecipitation method, using ammonia. The formation process of the solid solutions was studied as a function of temperature up to 1200°C by X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry

  18. Freestanding GaN-based light-emitting diode membranes on Y3Al5O12:Ce3+ crystal phosphor plate for efficient white light emission

    Science.gov (United States)

    Feng, Lungang; Li, Yufeng; Xiong, Han; Wang, Shuai; Wang, Jiangteng; Ding, Wen; Zhang, Ye; Yun, Feng

    2016-08-01

    GaN-based light-emitting diode (LED) membranes were peeled from the substrate using electrochemical etching of the bottom sacrificial layer. The freestanding membranes were transferred onto a Y3Al5O12:Ce3+ (YAG:Ce3+) crystal phosphor plate to realize a compact white light source. Verified by the Raman test, the initial strain within the original GaN layers was greatly released after the exfoliation process, which induced alleviation of the quantum confined stark effect. The electroluminescence measurement of a blue LED membranes-on-YAG:Ce3+ plate-structured device was conducted exhibiting color coordinates and a correlated color temperature of (0.3367,0.4525) and 5450 K at 10 mA, respectively.

  19. Y2O3-CeO2-ZrO2 Powder Prepared by Co-Precipitation and As-Plasma-Sprayed Coating

    Institute of Scientific and Technical Information of China (English)

    SHAO Gang-qin; ZHANG Wen-xi; HOU Zhong-tao; YUAN Run-zhang

    2004-01-01

    The Y2O3-CeO2-ZrO2 powders were prepared using a co-precipitation process and the corresponding coatings were prepared by plasma spraying. The results show that an optimal composition exists in Y2O3-doped CeO2-ZrO2, but not in CeO2-doped Y2O3-ZrO2. The powders mainly contain tetragonal phase and a trace amount of monoclinic phase. The homogeneity in composition, large agglomerate size, ideal particle size distribution and high flowability were obtained. The as-sprayed coatings are composed of non-transformable tetragonal phase, tz′structure, and resistant to transformation under thermal or mechanical stresses.

  20. Phase Equilibria and Magnetic Phases in the Ce-Fe-Co-B System

    Directory of Open Access Journals (Sweden)

    Tian Wang

    2016-12-01

    Full Text Available Ce-Fe-Co-B is a promising system for permanent magnets. A high-throughput screening method combining diffusion couples, key alloys, Scanning Electron Microscope/Wavelength Dispersive X-ray Spectroscope (SEM/WDS, and Magnetic Force Microscope (MFM is used in this research to understand the phase equilibria and to explore promising magnetic phases in this system. Three magnetic phases were detected and their homogeneity ranges were determined at 900 °C, which were presented by the formulae: Ce2Fe14−xCoxB (0 ≤ x ≤ 4.76, CeCo4−xFexB (0 ≤ x ≤ 3.18, and Ce3Co11−x FexB4 (0 ≤ x ≤ 6.66. The phase relations among the magnetic phases in this system have been studied. Ce2(Fe, Co14B appears to have stronger magnetization than Ce(Co, Fe4B and Ce3(Co, Fe11B4 from MFM analysis when comparing the magnetic interactions of selected key alloys. Also, a non-magnetic CeCo12−xFexB6 (0 ≤ x ≤ 8.74 phase was detected in this system. A boron-rich solid solution with Ce13FexCoyB45 (32 ≤ x ≤ 39, 3 ≤ y ≤ 10 chemical composition was also observed. However, the crystal structure of this phase could not be found in the literature. Moreover, ternary solid solutions ε1 (Ce2Fe17−xCox (0 ≤ x ≤ 12.35 and ε2 (Ce2Co17−xFex (0 ≤ x ≤ 3.57 were found to form between Ce2Fe17 and Ce2Co17 in the Ce-Fe-Co ternary system at 900 °C.

  1. Synthesis and Characterization of Ag/Ce1-xMnxO2-δ Oxidation Catalysts

    Directory of Open Access Journals (Sweden)

    David Alami

    2013-06-01

    Full Text Available The aim of this work was to obtain samples of Ag - doped manganese-cerium mixed oxides and explore their characteristics. Six catalysts were prepared by the co-precipitation process followed by impregnation method for Ag incorporation. These catalysts were characterized in particular by means of TEM, XRD, TPR and examined on the reaction of hydrogen peroxide catalytic decomposition. The samples obtained were solid solution nanoparticle agglomerates with irregular surface morphology. The results pointed out that the highest activity in oxidation reactions should possess Ag/Ce0.23Mn0.77O2-δ catalyst.  © 2013 BCREC UNDIP. All rights reservedReceived: 2nd April 2013; Revised: 11st May 2013; Accepted: 24th May 2013[How to Cite: Alami, D., Bulavin, V. (2013. Synthesis and Characterization of Ag/Ce1-xMnxO2-δ Oxidation Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (1: 83-88. (doi:10.9767/bcrec.8.1.4718.83-88][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.1.4718.83-88] | View in  |

  2. Special educaction and rewiews in the municipality of large scale Sobral (CE

    Directory of Open Access Journals (Sweden)

    Ana Paula Lima Barbosa Cardoso

    2012-11-01

    Full Text Available This article aims to discuss and analyze the participation of students with disabilities in public schools of the city of Sobral-CE in the assessment scale developed in that context. It follows a case study, a qualitative approach, conducted within the Department of Education and two municipal schools; the highest and lowest IDEB results (2009. The data collection instruments: analysis of documents, interviews and observation, and content analysis. The theoretical framework discusses the large-scale evaluation in the brazilian context in conjunction with the literature on the evaluation of teaching for students with disabilities. We describe the landscape of education in general sobralense and also data on special education. The research results discussed two cases of large-scale evaluation that occurred in that municipality: municipal evaluation and Proof Brazil. Regarding the first, the subjects affirms the participation of students with disabilities through a mechanism that prevents these results affect other students, are called "children of the shore." In Proof Brazil, the subjects again reported the participation of these students in national testing. It's criticizing the appropriateness of that instrument to assess this particular student body, suggesting the need of developping more "relevant" ones. Finally, it appears that the large-scale evaluation calls into question the process of schooling experienced by pupils with disabilities in Sobral-CE, showing the challenges and difficulties of the actions of school inclusion proposals in that context.

  3. Contemporary sample stacking in CE: a sophisticated tool based on simple principles.

    Science.gov (United States)

    Malá, Zdena; Krivánková, Ludmila; Gebauer, Petr; Bocek, Petr

    2007-01-01

    Sample stacking is a general term for methods in CE which are used for on-line concentration of diluted analytes. During the stacking process, analytes present at low concentrations in a long injected sample zone are concentrated into a short zone (stack). The stacked analytes are then separated and individual zones are detected. Thus stacking provides better separation efficiency and detection sensitivity. Many papers have been published on stacking till now, various procedures have been described, and, many names have been proposed for stacking procedures utilizing the same principles. This contribution brings an easy and unified view on stacking, describes the basic principles utilized, makes a list of recognized operational principles and brings an overview of principal current procedures. Further, it surveys selected recent practical applications ordered according to their operational principles and includes the terms, nicknames, and acronyms used for these actual stacking procedures. This contribution may help both newcomers and experts in the field of CE to orient themselves in the already quite complex topic of sample stacking.

  4. Fabrication, microstructure, and optical properties of nanocrystalline transparent LAST glass ceramics containing CeO2

    Institute of Scientific and Technical Information of China (English)

    Mohammad Sadegh Shakeri

    2014-01-01

    In the present research, the effect of CeO2 dopant on the fabrication of transparent lithium aluminosilicate titanate (LAST) glass ceramics was investigated. Nanocrystallineβ-quartz solid solution (s.s.) was observed to be the main phase crystallized in this system. Com-parable refractive indices of the glassy matrix andβ-quartz s.s., as well as the incorporation of very fine grains size were determined as the main reasons for retaining the transparency of the glass ceramics. CeO2 was introduced as a suitable optical agent, playing a role as a network modifier in the glass ceramics, because it does not accelerate the growth process and retards the extended growth of crystals. Optical investi-gations indicate that the Fermi energy level, direct and indirect band gaps, and Urbach energy decrease with increasing nanocrystal content in the glassy matrix of specimens, which can be related to the expansion of conduction band, the enhancement of ionic bonds in the crystal lat-tice, and the enhancement of structural arrangement degree, respectively.

  5. Dopant-induced modification of active site structure and surface bonding mode for high-performance nanocatalysts: CO oxidation on capping-free (110)-oriented CeO2:Ln (Ln = La-Lu) nanowires.

    Science.gov (United States)

    Ke, Jun; Xiao, Jia-Wen; Zhu, Wei; Liu, Haichao; Si, Rui; Zhang, Ya-Wen; Yan, Chun-Hua

    2013-10-09

    Active center engineering at atomic level is a grand challenge for catalyst design and optimization in many industrial catalytic processes. Exploring new strategies to delicately tailor the structures of active centers and bonding modes of surface reactive intermediates for nanocatalysts is crucial to high-efficiency nanocatalysis that bridges heterogeneous and homogeneous catalysis. Here we demonstrate a robust approach to tune the CO oxidation activity over CeO2 nanowires (NWs) through the modulation of the local structure and surface state around Ln(Ce)' defect centers by doping other lanthanides (Ln), based on the continuous variation of the ionic radius of lanthanide dopants caused by the lanthanide contraction. Homogeneously doped (110)-oriented CeO2:Ln NWs with no residual capping agents were synthesized by controlling the redox chemistry of Ce(III)/Ce(IV) in a mild hydrothermal process. The CO oxidation reactivity over CeO2:Ln NWs was dependent on the Ln dopants, and the reactivity reached the maximum in turnover rates over Nd-doped samples. On the basis of the results obtained from combined experimentations and density functional theory simulations, the decisive factors of the modulation effect along the lanthanide dopant series were deduced as surface oxygen release capability and the bonding configuration of the surface adsorbed species (i.e., carbonates and bicarbonates) formed during catalytic process, which resulted in the existence of an optimal doping effect from the lanthanide with moderate ionic radius.

  6. Localized and mixed valence state of Ce 4 f in superconducting and ferromagnetic CeO1 -xFxBiS2 revealed by x-ray absorption and photoemission spectroscopy

    Science.gov (United States)

    Sugimoto, T.; Ootsuki, D.; Paris, E.; Iadecola, A.; Salome, M.; Schwier, E. F.; Iwasawa, H.; Shimada, K.; Asano, T.; Higashinaka, R.; Matsuda, T. D.; Aoki, Y.; Saini, N. L.; Mizokawa, T.

    2016-08-01

    We have performed Ce L3-edge x-ray absorption spectroscopy (XAS) and Ce 4 d -4 f resonant photoemission spectroscopy (PES) on single crystals of CeO1 -xFxBiS2 for x =0.0 and 0.5 in order to investigate the Ce 4 f electronic states. In Ce L3-edge XAS, a mixed valence of Ce was found in the x =0.0 sample, and F doping suppressed it, which is consistent with the results on polycrystalline samples. As for resonant PES, we found that the Ce 4 f electrons in both x =0.0 and 0.5 systems respectively formed a flat band at 1.0 and 1.4 eV below the Fermi level and there was no contribution to the Fermi surfaces. Interestingly, Ce valence in CeOBiS2 deviates from Ce3 + even though Ce 4 f electrons are localized, indicating the Ce valence is not in a typical valence fluctuation regime. We assume that localized Ce 4 f in CeOBiS2 is mixed with unoccupied Bi 6 pz , which is consistent with a previous local structural study. Based on the analysis of the Ce L3-edge XAS spectra using Anderson's impurity model calculation, we found that the transfer integral becomes smaller, increasing the number of Ce 4 f electrons upon the F substitution for O.

  7. Studies on Y{sub 2}SiO{sub 5}:Ce phosphors prepared by gel combustion using new fuels

    Energy Technology Data Exchange (ETDEWEB)

    Muresan, L.E., E-mail: laura_muresan2003@yahoo.com [“Raluca Ripan” Institute for Research in Chemistry, Babeş Bolyai University, Fântânele 30, 400294 Cluj-Napoca (Romania); Oprea, B.F.; Cadis, A.I.; Perhaita, I. [“Raluca Ripan” Institute for Research in Chemistry, Babeş Bolyai University, Fântânele 30, 400294 Cluj-Napoca (Romania); Ponta, O. [Faculty of Physics, Babeş Bolyai University, 400084 Cluj-Napoca (Romania)

    2014-12-05

    Highlights: • Y{sub 2}SiO{sub 5}:Ce was prepared by combustion using aspartic or glutamic acid as fuels. • Combustion process occurs differently depending on the fuels amount. • Single phase X2-Y{sub 2}SiO{sub 5} phosphors were obtained in fuel rich conditions. • PL measurements indicate that aspartic acid is a better fuel than glutamic. • Optimal preparative conditions were established for synthesis of Y{sub 2}SiO{sub 5}:Ce. - Abstract: Cerium activated yttrium silicate (Y{sub 2}SiO{sub 5}:Ce) phosphors were prepared by combustion, using yttrium–cerium nitrate as oxidizer, aspartic or glutamic acid as fuel and TEOS as source of silicon. In this study, aspartic and glutamic acid are used for the first time for the synthesis of Y{sub 2}SiO{sub 5}:Ce phosphors. The fuels molar amount was varied from 0.5 mol to 1.5 mol in order to reveal the thermal behavior of intermediary products (gels and ashes) same as the structural and luminescent characteristics of final products (phosphors). According to thermal analysis correlated with FTIR and XPS investigations, the combustion process occurs differently depending on the fuel amount; unreacted nitrate compounds have been identified in fuel lean conditions and carbonate based compounds along with organic residue in rich fuel conditions. The conversion to well crystallized silicates was revealed by changes of FTIR vibration bands and confirmed by XRD measurements. Based on luminescent spectra, aspartic acid is a better fuel than glutamic acid. A positive effect on the luminescence have been observed for samples fired in air due to complete remove of organic residue. The best luminescence was obtained for combustions with 0.75 mol aspartic acid and 1.25 mol glutamic respectively, fired at 1400 °C for 4 h in air atmosphere.

  8. Steam reforming of bio-ethanol over Ni on Ce-ZrO2 support: Influence of redox properties on the catalyst reactivity

    Directory of Open Access Journals (Sweden)

    Sumittra Charojrochkul

    2006-11-01

    Full Text Available The steam reforming of ethanol over Ni on Ce-ZrO2 support, (Ni/ Ce-ZrO2 were studied. The catalyst provides significantly higher reforming reactivity and excellent resistance toward carbon deposition compared to Ni/Al2O3 under the same conditions. At the temperature above 800ºC, the main products from the reforming processes over Ni/Ce-ZrO2 were H2, CO, and CO2 with small amount of CH4 depending on the inlet ethanol/steam and oxygen/ethanol ratios, whereas high hydrocarbon compounds i.e., C2H4 and C2H6 were also observed from the reforming of ethanol over Ni/Al2O3 in the range of conditions studied (700- 1000ºC.These excellent ethanol reforming performances of Ni/Ce-ZrO2 in terms of stability, reactivity and product selectivities are due to the high redox property of Ce-ZrO2. During the ethanol reforming process, in addition to the reactions on Ni surface, the gas-solid reactions between the gaseous components presented in the system (C2H5OH, C2H6, C2H4, CH4, CO2, CO, H2O, and H2 and the lattice oxygen (Ox on Ce-ZrO2 surface also take place. Among these redox reactions, the reactions of adsorbed surface hydrocarbons with the lattice oxygen (Ox (CnHm + Ox → nCO + m/2(H2 + Ox-n can eliminate the formation of high hydrocarbons (C2H6 and C2H4, which easily decompose and form carbon species on Ni surface (CnHm→ nC + m/2H2.

  9. Selective Plasmonic Gas Sensing: H2, NO2, and CO Spectral Discrimination by a Single Au-CeO2 Nanocomposite Film

    Energy Technology Data Exchange (ETDEWEB)

    Joy, N.; Nandasiri, Manjula I.; Rogers, Phillip H.; Jiang, Weilin; Varga, Tamas; Kuchibhatla, Satyanarayana V N T; Thevuthasan, Suntharampillai; Carpenter, Michael A.

    2012-06-05

    A Au-CeO2 nanocomposite film has been investigated as a potential sensing element for high-temperature plasmonic sensing of H2, CO, and NO2 in an oxygen containing environment. The CeO2 thin film was deposited by molecular beam epitaxy (MBE) and Au was implanted into the as-grown film at an elevated temperature followed by high temperature annealing to form well-defined Au nanoclusters. The Au-CeO2 nanocomposite film was characterized by x-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). For the gas sensing experiments, separate exposures to varying concentrations of H2, CO, and NO2 were performed at a temperature of 500°C in oxygen backgrounds of 5.0, 10, and ~21% O2. Changes in the localized surface plasmon resonance (LSPR) absorption peak were monitored during gas exposures and are believed to be the result of oxidation-reduction processes that fill or create oxygen vacancies in the CeO2. This process affects the LSPR peak position either by charge exchange with the Au nanoparticles or by changes in the dielectric constant surrounding the particles. Multivariate analysis was used to gauge the inherent selectivity of the film between the separate analytes. From principal component analysis (PCA), unique and identifiable responses were seen for each of the analytes. Linear discriminant analysis (LDA) was also used and showed separation between analytes as well as trends in gas concentration. Results indicate that the Au-CeO2 thin film is selective to O2, H2, CO, and NO2 in separate exposures. Combined with the observed stability over long exposure periods, the Au-CeO2 film shows good potential as an optical sensing element for harsh environmental conditions.

  10. Microstructure and mechanical properties of Al-Si-Ni-Ce alloys prepared by gas-atomization spark plasma sintering and hot-extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Wang, E.R. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Hui, X.D., E-mail: xdhui@ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Wang, S.S.; Zhao, Y.F.; Chen, G.L. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2011-07-15

    Highlights: {yields} There are distinct microstructures in the as-atomized powders with different size. {yields} The morphology of Al{sub 11}Ce{sub 3} crystals is related to the Ni content. {yields} Tiny Al{sub 3}Ni precipitated from the supersaturated matrix after SPS process. {yields} Hot-extrusion leads to the improved microstructures. {yields} This kind of alloy exhibits high comprehensive mechanical properties. - Abstract: Al-Si-Ni-Ce alloys with the composition of Al{sub 78.5}Si{sub 19}Ni{sub 2}Ce{sub 0.5}, Al{sub 76}Si{sub 19}Ni{sub 4}Ce{sub 1} and Al{sub 73}Si{sub 19}Ni{sub 7}Ce{sub 1} were atomized and then sintered by using spark plasma method. The microstructure of the as-atomized powders, sintered and hot-extruded samples was analyzed. The influences of granularity and sintering parameters including time and temperature on the density of sintered alloy were also discussed. It is shown that the atomized powders are composed of Si, Al{sub 11}Ce{sub 3}, Al{sub 3}Ni and alpha Al. Tiny Al{sub 3}Ni particles precipitate from supersaturated matrix near the powder boundaries during SPS. Hot-extrusion process leads to the layer structure and more homogeneous distribution of precipitates. These alloys exhibit high comprehensive mechanical properties with combination of high Vicker's micro-hardness, moderate tensile properties and elongation, which provide a novel kind of promising engineering materials.

  11. Glass forming ability of the Al-Ce-Ni system; Avaliacao da capacidade de formacao vitrea do sistema Al-Ce-Ni

    Energy Technology Data Exchange (ETDEWEB)

    Triveno Rios, C. [Engenharia Mecanica, Universidade Federal de Mato Grosso, Rondonopolis, MT (Brazil)], e-mail: triveno@ufmt.br; Surinach, S.; Baro, M.D. [Departamento de Engenharia de Materiais - Universidade Federal de Sao Carlos, SP (Brazil); Bolfarini, C.; Botta, W.J.; Kiminami, C.S. [Departamento de Fisica da Universidade Autonoma de Barcelona, Bellaterra (Spain)

    2010-07-01

    In the present work, the glass forming ability (GFA) and its compositional dependence on Al-Ni-Ce system alloys were investigated in function of several thermal parameters. Rapidly quenched Al{sub 85}Ni{sub 15}-{sub X}Ce{sub X} (X=4,5,6,7,10), Al{sub 90}Ni{sub 5}Ce{sub 5}, Al{sub 89}Ni{sub 2}.{sub 4}Ce{sub 8}.{sub 6}, Al{sub 80}Ni{sub 15.6}Ce{sub 4}.{sub 4} and Al{sub 78}Ni{sub 18.5}Ce{sub 3.5} amorphous ribbons were produced by melt-spinning and the structural transformation during heating was studied using a combination of X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results showed that the GFA and the thermal stability in the Al-rich corner of Al- Ni-Ce system alloys were enhanced by increasing the solute content and specifically the Ce content (author)

  12. Preparation for CeO2/Nanographite Composite Materials and Electrochemical Degradation of Phenol by CeO2/Nanographite Cathodes.

    Science.gov (United States)

    Yu, Li; Yu, Xiujuan; Sun, Tianyi; Wang, Na

    2015-07-01

    CeO2/nanographite (CeO2/nano-G) composite materials were got by chemical precipitation method with nanographite (nano-G) and cerous nitrate hexahydrate as raw materials. The microstructures of CeO2/nano-G composite materials were characterized by means of SEM, XRD, XPS and Raman. The cathodes were made by nano-G and CeO2/nano-G composite materials, respectively. The electrolysis phenol was conducted by the diaphragm cell prepared cathode and the Ti/RuO2 anode. The results indicated that the Cerium oxide is mainly in nanoscale spherical state, uniformly dispersed in the nanographite sheet surface, and there are two different oxidation states for elemental Ce, namely, Ce(III) and Ce(IV). In the diaphragm electrolysis system with the aeration conditions, the degradation rate of phenol reached 93.9% under 120 min's electrolysis. Ceria in the cathode materials might lead to an increase in the local oxygen concentration, which accelerated the two-electron reduction of O2 to hydrogen peroxide (H2O2). The removal efficiency of phenol by using the CeO2/nano-G composite cathode was better than that of the nano-G cathode.

  13. Effects of CeO2 Nanoparticles on Terrestrial Isopod Porcellio scaber: Comparison of CeO2 Biological Potential with Other Nanoparticles.

    Science.gov (United States)

    Malev, Olga; Trebše, Polonca; Piecha, Małgorzata; Novak, Sara; Budič, Bojan; Dramićanin, Miroslav D; Drobne, Damjana

    2017-02-01

    Nano-sized cerium dioxide (CeO2) particles are emerging as an environmental issue due to their extensive use in automobile industries as fuel additives. Limited information is available on the potential toxicity of CeO2 nanoparticles (NPs) on terrestrial invertebrates through dietary exposure. In the present study, the toxic effects of CeO2 NPs on the model soil organism Porcellio scaber were evaluated. Nanotoxicity was assessed by monitoring the lipid peroxidation (LP) level and feeding rate after 14-days exposure to food amended with nano CeO2. The exposure concentration of 1000 μg of CeO2 NPs g(-1) dry weight food for 14 days significantly increased both the feeding rate and LP. Thus, this exposure dose is considered the lowest observed effect dose. At higher exposure doses of 2000 and 5000 μg of CeO2 NPs g(-1) dry weight food, NPs significantly decreased the feeding rate and increased the LP level. Comparative studies showed that CeO2 NPs are more biologically potent than TiO2 NPs, ZnO NPs, CuO NPs, CoFe2O4 NPs, and Ag NPs based on feeding rate using the same model organism and experimental setup. Based on comparative metal oxide NPs toxicities, the present results contribute to the knowledge related to the ecotoxicological effects of CeO2 NPs in terrestrial invertebrates exposed through feeding.

  14. Influence of hybridization in the Magnetic Circular X-ray Dichroism at the Ce-M4,5 absorption edges of Ce-Fe systems

    NARCIS (Netherlands)

    Finazzi, M.; de Groot, F.M.F.; Dias, A.-M.; Kappler, J.-P.; Schulte, O.; Felsch, W.; Krill, G.

    2013-01-01

    We have performed a Magnetic Circular X-ray Dichroism (XMCD) study at the Ce-M*,s absorption edges on some Ce-Fe systems. We find that the dichroism signal in these systems is very sensitive to the degree of hybridization of the 4f electrons with the valence band. XMCD is able to demonstrate that th

  15. Influence of hybridization in the magnetic circular X-ray dichroism at the Ce-M(4,5) absorption edges of Ce-Fe systems

    NARCIS (Netherlands)

    Finazzi, M; deGroot, FMF; Dias, AM; Kappler, JP; Schulte, O; Felsch, W; Krill, G

    1996-01-01

    We have performed a Magnetic Circular X-ray Dichroism (XMCD) study at the Ce-M(4,5) absorption edges on some Ce-Fe systems. We find that the dichroism signal in these systems is very sensitive to the degree of hybridization of the 4f electrons with the valence band. XMCD is able to demonstrate that

  16. EnTranCe to the second life of gas : EnTranCe as source of innovation and human resources

    NARCIS (Netherlands)

    Aué, Jan-jaap; Gemert, Wim van; Martinus, Gerard

    2015-01-01

    The living lab EnTranCe provides a platform for open innovations. Stakeholders from large industry, SME’s, government and the research community team up to work on the future of the European energy system, with gas in a pivotal role. An important element of the innovation strength of EnTranCe is tha

  17. Optical and scintillation properties of Ce3+ doped LiYF4 and LiLuF4 crystals

    NARCIS (Netherlands)

    Combes, CM; Dorenbos, P; vanEijk, CWE; Pedrini, C; DenHartog, HW; Gesland, JY; Rodnyi, PA

    1997-01-01

    Optical properties of LiYF4:Ce and LiLuF4:Ce were studied viz. optical absorption spectra and X-ray induced emission spectra. The scintillation characteristics of LiYF4:Ce and LiLuF4:Ce were investigated viz. gamma-ray induced pulse height spectra and decay time measurements. A model is presented to

  18. Enhancement of red to orange emission ratio of YPO4:Eu3+,Ce3+ and its dependence on Ce3+ concentration

    Institute of Scientific and Technical Information of China (English)

    ZHAN Shiping; GAO Yongyi; LIU Yunxin; ZHONG Hui

    2012-01-01

    Eu3+ and Ce3+ co-doped YPO4 microspheres were synthesized by hydrothermal method without template.The emission spectra showed that the red emission centered at 618 nm could be readily increased relatively to the orange emission centered at 590 nm by controlling the doping concentration of Ce3+ ion.The investigation based on excitation spectra and decay curves demonstrated that the doped Ce3+ ions took two efficient energy transfers to Eu3+ ions and affected the lifetime of the emission states ofEu3+ ions so that the emission spectra of Eu3+ ion were accordingly tuned with the Ce3+ content increasing.This controllable red (5D0→7F2) to orange (5D0→7F1) emission ratio of YPO4:Eu3+,Ce3+ made it very promising for encoded anti-fake labels and bio-labels.

  19. Effect of Ce addition on the surface properties and n-dodecane dehydrogenation performance of Pt-Sn/Ce-Al2O3 catalyst

    Science.gov (United States)

    Li, Xianru; He, Songbo; Wei, Huangzhao; Luo, Sha; Gu, Bin; Sun, Chenglin

    2015-08-01

    Ce-modified alumina carriers with different Ce content were prepared by vacuum isovolume impregnation method aiming to improve the n-dodecane catalytic dehydrogenation performance of PtSn/Al2O3 catalyst. The support and catalyst were characterized by XRD, N2 adsorption-desorption, NH3-TPD, H2-TPR, CO-pulse adsorption and TG-DTG. Results showed that Ce addition decreased the surface acid amount significantly and inhibited the reduction of SnO x species. Besides, Ce containing catalyst showed higher n-dodecane dehydrogenation activity and stability and lower coke deposition amount and coke burning temperature. In our study, the optimal Ce addition amount for n-dodecane dehydrogenation was 2%.

  20. Thermodynamic Assessment of the ZrO2-CeO2 and ZrO2-CeO1.5 Binary System

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An optimal set of thermodynamic parameters of the ZrO2-CeO1.5 system has been obtained using phase diagram data by modern CALPHAD (CALculation of PHAse Diagrams) technique. The liquid and other solid solution phases were regarded as substitutional solution. The ordered Zr2Ce2O7 phase was treated as a stoichiometric compound. The ZrO2-CeO2 system has been re-optimized with new reference state. A comparison between the ZrO2-CeO2 system and ZrO2-CeO1.5 system has been made through calculation. With the calculation, the experimental information is well reproduced and a good agreement is obtained.

  1. Ce4Ag3Ge4O(0.5)--chains of oxygen-centered [OCe2Ce(2/2)] tetrahedra embedded in a [CeAg3Ge4] intermetallic matrix.

    Science.gov (United States)

    Heymann, Gunter; Riecken, Jan F; Johrendt, Dirk; Rayaprol, Sudhindra; Pöttgen, Rainer; Huppertz, Hubert

    2013-11-14

    The oxidation of an intermetallic phase under high-pressure/high-temperature conditions led to the synthesis of Ce4Ag3Ge4O(0.5) exhibiting [OCe2Ce(2/2] tetrahedral chains, in which the oxygen atoms statistically occupy the tetrahedral centres. Starting from a 1:1:1 CeAgGe precursor (NdPtSb type), a multianvil high-pressure/high-temperature experiment at 11.5 GPa and 1250-1300 °C revealed Ce4Ag3Ge4O(0.5), crystallizing in the space group Pnma with the following lattice parameters: a = 2087.3(4), b = 439.9(1), and c = 1113.8(2) pm. Magnetic measurements showed Curie-Weiss behavior above 100 K with an experimental magnetic moment of 2.42 µB per Ce atom, close to the value for the free Ce(3+) ion, clearly indicating trivalent cerium in Ce4Ag3Ge4O(0.5). Full potential GGA+U band structure calculations resulted in metallic properties and a magnetic ground state with one unpaired 4f-electron per cerium in agreement with the experiments.

  2. Thermoelectric transport properties of nanostructured FeSb 2 and Ce-based heavy-fermions CeCu and CeAl 3

    Science.gov (United States)

    Pokharel, Mani R.

    Thermoelectric (TE) energy conversion is an all-solid-state technology which can convert waste thermal energy into useful electric power and cool ambience without using harmful gases like CFC. Due to their several advantages over traditional energy conversion technologies, thermoelectric generators (TEG) and coolers (TEC) have drawn enormous research efforts. The objective of this work is to find promising materials for thermoelectric cooling applications and optimize their thermoelectric performances. Finding a material with a good value for the thermoelectric figure-of-merit (ZT) at cryogenic temperatures, specifically below 77 K, has been of great interest. This work demonstrates that FeSb2 1, CeCu6 2 and CeAl3 3, all belonging to a class of materials with strongly correlated electron behavior; exhibit promising thermoelectric properties below 77 K. In general, ZT of a TE material can be increased using two basic approaches: lattice thermal conductivity reduction and power factor (PF) enhancement. The results of this study indicate that nanostructuring effectively decreases the thermal conductivity of FeSb2, CeCu6 and CeAl 3 leading to improved ZT. The approach of introducing point-defect scattering to further reduce the thermal conductivity is successfully implemented for Te-substituted FeSb2 nanostructured samples 4. A semiconductor/metal interface has long been proposed to exhibit enhanced thermoelectric properties. We use this technique by introducing Ag-nanoparticles in the host FeSb2 which further increases ZT by 70% 5. Additionally, a detailed investigation is made on the phonon-drag effect as a possible mechanism responsible for the large value of the Seebeck coefficient of FeSb2 6. We show that the phonon-drag mechanism contributes significantly to the large Seebeck effect in FeSb2 and hence this effect cannot be minor as was proposed in literatures previously. A model based on Kapitza-resistance and effective medium approach (EMA) is used to analyze

  3. Scintillation and optical properties of Ce-doped YAGG transparent ceramics

    Institute of Scientific and Technical Information of China (English)

    Masaki Mori; Jian Xu; Go Okada; Takayuki Yanagida; Jumpei Ueda; Setsuhisa Tanabe

    2016-01-01

    We investigated photoluminescence (PL) and scintillation properties of Ce3+-doped Y3Al2Ga3O12 (Ce:YAGG) trans-parent ceramics synthesized by vacuum sintering with different Ce3+ concentrations (mol.%) from 0.3% to 1% (0.3%Ce:YAGG, 0.5%Ce:YAGG, 0.8%Ce:YAGG and 1%Ce:YAGG). The samples were synthesized by the vacuum sintering technique. The obtained samples showed a very strong and broad PL emission by the 5d1-4f transition of Ce3+in the wavelength range from 470 to 600 nm. The PL decay profiles were approximated by a single exponential decay function with the time constants of around 33–39 ns. Fur-thermore, the scintillation spectra induced by X-rays showed similar features with those observed in PL. The scintillation decay time profiles followed a second-order exponential decay function. The fast component group (ranged 35–42 ns) were dominantly contrib-uted by the 5d1-4f transition of Ce3+. The pulse height spectra utilizing the latter emissions showed a clear photoabsorption peak. Among those samples tested, 0.5%Ce:YAGG sample showed the highest scintillation light yield of 21,400 ph/MeV under 137Csγ-ray irradiation.

  4. Origin of enhanced photocatalytic activity of F-doped CeO2 nanocubes

    Science.gov (United States)

    Miao, Hui; Huang, Gui-Fang; Liu, Jin-Hua; Zhou, Bing-Xin; Pan, Anlian; Huang, Wei-Qing; Huang, Guo-Fang

    2016-05-01

    CeO2 nanoparticles are synthesized using a low-temperature solution combustion method and subsequent heat treatment in air. It is found that F-doping leads to smaller particle size and the formation of CeO2 nanocubes with higher percentage of reactive facets exposed. The band gap is estimated to be 3.16 eV and 2.88 eV, for pure CeO2 and fluorine doped CeO2 (F-doped CeO2) nanocubes, respectively. The synthesized F-doped CeO2 nanocubes exhibit much higher photocatalytic activities than commercial TiO2 and spherical CeO2 for the degradation of MB dye under UV and visible light irradiation. The apparent reaction rate constant k of MB decomposition over the optimized F-doped CeO2 nanocubes is 9.5 times higher than that of pure CeO2 and 2.2 times higher than that of commercial TiO2. The enhanced photocatalytic activity of F-doped CeO2 nanocubes originates from the fact that F-doping induces the small size, the highly reactive facets exposed, the intense absorption in the UV-vis range and the narrowing of the band gap. This research provides some new insights for the synthesis of the doping of the foreign atoms into photocatalyst with controlled morphology and enhanced photocatalytic activity.

  5. Controllable preparation of CeO2 nanostructure materials and their catalytic activity

    Institute of Scientific and Technical Information of China (English)

    Shan Wenjuan; Guo Hongjuan; Liu Chang; Wang Xiaonan

    2012-01-01

    Well-crystalline CeO2 nanostructures with the morphology ofnanorods and nanocubes were synthesized by a template-free hydrothermal method.X-ray diffraction (XRD),transmission electron microscopy (TEM),Brunauer-Emmett-Teller (BET) nitrogen adsorption-desorption measurements were employed to characterize the synthesized materials.The reducibility and catalytic activity of nanostructured CeO2 were examined by hydrogen temperature-programmed reduction (H2-TPR) and CO oxidation.The results showed that CeO2 nanorods could be converted into CeO2 nanocubes with the increasing of the reaction time and the hydrothermal temperature,CeO2 nanorods became longer gradually with the increasing of the concentrations of NaOH.H2-TPR characterization demonstrated that the intense low-temperature reduction peak in the CeO2 nanorods indicated the amount of hydrogen consumed is larger than CeO2 nanocubes.Meantime the CeO2 nanorods enhanced catalytic activity for CO oxidation,the total conversion temperature was 340 ℃.The reasons were that CeO2 nanorods have much smaller crystalline sizes and higher surface areas than CeO2 nanocubes.

  6. Microstructures and mechanical properties in B{sub 4}C-CeO{sub 2} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sun Shuchen, E-mail: sunsc@smm.neu.edu.cn [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Sakamoto, Tatsuaki; Nakai, Kiyomichi [Department of Materials Science and Biotechnology, Ehime University, 3Bunkyo-cho, Matsuyama 790-8577 (Japan); Kurishita, Hiroaki [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Kobayashi, Sengo [Department of Materials Science and Biotechnology, Ehime University, 3Bunkyo-cho, Matsuyama 790-8577 (Japan); Xu Jingyu; Cao Hui; Gao Bo; Bianxue; Wu Wenyuan; Tu Ganfeng [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Matsuda, Seiji [Department of Anatomy and Embryology, Ehime University, Shizugawa, Toon 791-0295 (Japan)

    2011-10-01

    B{sub 4}C-CeO{sub 2} composite ceramics with various concentrations of CeO{sub 2} were fabricated by hot press. The effects of CeO{sub 2} on the microstructures and mechanical properties of the B{sub 4}C-CeO{sub 2} ceramics have been investigated. During hot press, CeB{sub 6} was formed by the reaction between CeO{sub 2} and B{sub 4}C. The B{sub 4}C-CeO{sub 2} ceramics had higher levels of density, fracture toughness, flexural strength and Vickers hardness than those in monolithic B{sub 4}C. The microstructures of the B{sub 4}C-CeO{sub 2} ceramics were observed and analyzed by transmission electron microscopy. In-situ synthesized CeB{sub 6} indicated whisker-like shape and grew along the interface with B{sub 4}C, and different boron carbides with different content of C existed at/around the interface of CeB{sub 6} with B{sub 4}C in the composite ceramics. It made mechanical properties greatly improved.

  7. The scintillation mechanism in LaCl sub 3 :Ce sup 3 sup +

    CERN Document Server

    Loef, E; Eijk, C W E

    2003-01-01

    The scintillation properties of LaCl sub 3 crystals, doped with Ce sup 3 sup + concentrations of 0.57, 1.0, 2.0, 4.0, and 10%, are studied under x-ray and gamma-quanta excitation at various temperatures. Under x-ray excitation, characteristic doublet Ce sup 3 sup + emission is observed with a maximum at 3.7 eV. Also self-trapped exciton (STE) emission is observed with a maximum near 3.1 eV. The contribution of STE luminescence to the total light yield decreases with increasing Ce concentration. For LaCl sub 3 :0.57%Ce sup 3 sup + , the contribution is 33%, whereas for LaCl sub 3 :10%Ce sup 3 sup + it is 4%. The total light yield of the Ce sup 3 sup + -doped samples ranges from 38 000 photons per megaelectronvolt (ph MeV sup - sup 1) of absorbed gamma-ray energy to 47 000(ph MeV sup - sup 1) for LaCl sub 3 :0.57%Ce sup 3 sup + and LaCl sub 3 :10%Ce sup 3 sup + , respectively. A model is proposed to explain the energy transfer from the host lattice to the Ce sup 3 sup + ions. At these Ce concentrations, energy ...

  8. Chemical interaction of Ce-Fe mixed oxides for methane selective oxidation

    Institute of Scientific and Technical Information of China (English)

    祝星; 杜云鹏; 王华; 魏永刚; 李孔斋; 孙令玥

    2014-01-01

    Chemical interaction of Ce-Fe mixed oxides was investigated in methane selective oxidation via methane temperature pro-grammed reduction and methane isothermal reaction tests over Ce-Fe oxygen carriers. In methane temperature programmed reduction test, Ce-Fe oxide behaved complete oxidation at the lower temperature and selective oxidation at higher temperatures. Ce-Fe mixed oxides with the Fe content in the range of 0.1-0.5 was able to produce syngas with high selectivity in high-temperature range (800-900 °C), and a higher Fe amount over 0.5 seemed to depress the CO formation. In isothermal reaction, complete oxidation oc-curred at beginning following with selective oxidation later. Ce1-xFexO2-δ oxygen carriers (x≤0.5) were proved to be suitable for the selective oxidation of methane. Ce-Fe mixed oxides had the well-pleasing reducibility with high oxygen releasing rate and CO selec-tivity due to the interaction between Ce and Fe species. Strong chemical interaction of Ce-Fe mixed oxides originated from both Fe* activated CeO2 and Ce3+ activated iron oxides (FeOm), and those chemical interaction greatly enhanced the oxygen mobility and se-lectivity.

  9. Catalytic reforming of toluene as tar model compound: effect of Ce and Ce-Mg promoter using Ni/olivine catalyst.

    Science.gov (United States)

    Zhang, Ruiqin; Wang, Huajian; Hou, Xiaoxue

    2014-02-01

    Tar produced by biomass gasification as a route of renewable energy must be removed before the gas can be used. This study was undertaken using toluene as a model tar compound for evaluating its steam reforming conversion with three Ni-based catalysts, Ni/olivine, Ni-Ce/olivine and Ni-Ce-Mg/olivine. Effects of Ce and Mg promoters on the reaction activity and coke deposition were studied. Overall the performance of Ce and Mg promoted Ni/olivine catalysts is better than that of only Ce promoter and Ni/olivine alone. The experimental results indicate that Ni-Ce-Mg/olivine catalysts could improve the resistance to carbon deposition, enhance energy gases yield and resist 10ppm H2S poison at 100mLmin(-1) for up to 400min. Furthermore, the activity of catalysts was related to the steam/carbon (S/C) ratios; at S/C ratio=5, T=790°C, space velocity=782h(-1) and t=2h, the Ni-Ce-Mg/olivine system yielded 89% toluene conversion, 5.6Lh(-1) product gas rate, 62.6mol% H2 content and 10% (mol useful gas mol(-1) toluene) energy yield. Moreover, at low S/C ratio, it had higher reaction activity and better ability to prevent coking. There is a small amount of carbon deposition in the form of amorphous carbon after 7h. Various characterization techniques such as XRD, FTIR and thermogravimetric were performed to investigate the coke deposition of Ni/olivine, Ni-Ce/olivine and Ni-Ce-Mg/olivine. It is suggested that 3% Ni-1% Ce-1% Mg/olivine was the most promising catalyst due to its minimum coke amount and the lower activation energy of coke burning.

  10. Manipulating Ce Valence in RE2Fe14B Tetragonal Compounds by La-Ce Co-doping: Resultant Crystallographic and Magnetic Anomaly.

    Science.gov (United States)

    Jin, Jiaying; Zhang, Yujing; Bai, Guohua; Qian, Zeyu; Wu, Chen; Ma, Tianyu; Shen, Baogen; Yan, Mi

    2016-07-26

    Abundant and low-cost Ce has attracted considerable interest as a prospective alternative for those critically relied Nd/Pr/Dy/Tb in the 2:14:1-type permanent magnets. The (Nd, Ce)2Fe14B compound with inferior intrinsic magnetic properties to Nd2Fe14B, however, cannot provide an equivalent magnetic performance. Since Ce valence is sensitive to local steric environment, manipulating it towards the favorable trivalent state provides a way to enhance the magnetic properties. Here we report that such a desirable Ce valence can be induced by La-Ce co-doping into [(Pr, Nd)1-x(La, Ce)x]2.14Fe14B (0 ≤ x ≤ 0.5) compounds via strip casting. As verified by X-ray photoelectron spectroscopy results, Ce valence shifts towards the magnetically favorable Ce(3+) state in the composition range of x > 0.3, owing to the co-doping of large radius La(3+) into 2:14:1 phase lattice. As a result, both crystallographic and magnetic anomalies are observed in the same vicinity of x = 0.3, above which lattice parameters a and c, and saturation magnetization Ms increase simultaneously. Over the whole doping range, 2:14:1 tetragonal structure forms and keeps stable even at 1250 K. This finding may shed light on obtaining a favorable Ce valence via La-Ce co-doping, thus maintaining the intrinsic magnetic properties of 2:14:1-type permanent magnets.

  11. Oxidative carbonylation of phenol with a Pd-O/CeO2-nanotube catalyst

    Institute of Scientific and Technical Information of China (English)

    Ye Yuan; Zhimiao Wang; Hualiang An; Wei Xue; Yanji Wang

    2015-01-01

    CeO2 nanotubes (CeO2-NT) were synthesized using carbon nanotubes as template by a liquid phase deposition and hydrothermal method. X-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption were used to characterize the CeO2-NT. The wall of CeO2-NT was composed of small interconnected nanocrystallites ranging from 4 to 9 nm in size. The specific surface area of CeO2-NT was 108.8 m2/g with an outer diameter of 25 nm and length > 300 nm. Supported Pd cata-lyst, Pd-O/CeO2-NT, was prepared using CeO2-NT as the support. Temperature-programmed reduc-tion analysis showed that the surface oxygen on Pd-O/CeO2-NT could be reduced at low tempera-ture, therefore it showed high activity in the reaction. Pd-O/CeO2-NT was used as the catalyst for the oxidative carbonylation of phenol. It has better activity and DPC selectivity than Pd-O/CeO2-P, which was prepared by supporting Pd on zero dimensional CeO2particles. Under the optimized conditions, phenol conversion was 67.7% with 93.3% DPC selectivity with Pd-O/CeO2-NT. However, its catalyt-ic activity decreased when the catalyst was used for the second time. This was attributed to the destruction of the tubular structure of Pd-O/CeO2-NT and Pd leaching during the reaction.

  12. Synthesis, characterization, and ecotoxicity of CeO2 nanoparticles with differing properties

    Science.gov (United States)

    Alam, Bushra; Philippe, Allan; Rosenfeldt, Ricki R.; Seitz, Frank; Dey, Sonal; Bundschuh, Mirco; Schaumann, Gabriele E.; Brenner, Sara A.

    2016-10-01

    CeO2 nanoparticles with various characteristics find an increasing number of applications in the electronic, medical, and other industries and are therefore likely released in the environment. This calls for investigations linking the physicochemical properties of these particles with their potential environmental impacts. In this study, CeO2 nanoparticle powders were prepared using three different precursors [Ce(NO3)3, CeCl3, and Ce(CH3COO)3] and annealing temperatures (300, 500, and 700 °C). This procedure resulted in nine different types of nanoparticles with differing size (5-90 nm), morphology, surface Ce3+/Ce4+ ratio, and slightly different crystal structures as characterized using transmission electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy, and X-ray diffraction measurements with Rietveld refinement. These CeO2 nanoparticles underwent toxicity testing at concentrations up to 64 mg L-1 using Daphnia magna. Toxic effects were observed for three particle types with EC50 values between 5 and 64 mg L-1. No clear correlation was observed between the physicochemical properties (size, shape, oxygen occupancy, Ce3+/Ce4+ ratio) of the nanoparticles and their toxicity. However, toxicity was correlated with the amount of Ce remaining suspended in the test medium after 24 h. This indicated that toxic effects may depend on the colloidal stability of CeO2 nanoparticles during the first day of exposure. Therefore, being readily suspended and remaining stable for several days in the aquatic media increases the likelihood that CeO2 nanoparticles will cause unwanted adverse effects.

  13. Hydrothermal synthesis of hexagonal CeO{sub 2} nanosheets and their room temperature ferromagnetism

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Fanming, E-mail: mrmeng@ahu.edu.cn [School of Physics and Materials Science, Anhui University, Hefei 230601 (China); Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China); Zhang, Cheng; Fan, Zhenghua; Gong, Jinfeng; Li, Aixia; Ding, Zongling; Tang, Huaibao; Zhang, Miao; Wu, Guifang [School of Physics and Materials Science, Anhui University, Hefei 230601 (China)

    2015-10-25

    Hexagonal CeO{sub 2} nanosheets of 40–50 nm in thickness and 300–400 nm in side-length have been successfully synthesized via controlling the morphology of CeCO{sub 3}OH precursors by a facile hydrothermal technique using CeCl{sub 3}·7H{sub 2}O as cerium source, ammonium hydrogen carbonate as precipitants, and ethylenediamine as complexant. The reaction time and the amount of CeCl{sub 3}·7H{sub 2}O and ethylenediamine were systematically investigated. The as-synthesized hexagonal CeO{sub 2} nanosheets were examined by XRD, SEM, TEM, XPS, Raman scattering and magnetization measurements. It is found that the amount of CeCl{sub 3}·7H{sub 2}O and ethylenediamine are key parameters for controlling the final morphology. The hexagonal CeO{sub 2} nanosheets have a fluorite cubic structure and there are Ce{sup 3+} ions and oxygen vacancies in surface of samples. The synthesized CeO{sub 2} shows excellent room temperature optical properties. M–H curve exhibits excellent room-temperature ferromagnetism (RTFM) with saturation magnetization (M{sub s}) of 3.02 × 10{sup −2} emu/g, residual magnetization (M{sub r}) of 0.68 × 10{sup −2} emu/g and coercivity (H{sub c}) of 210 Oe, which is likely attributed to the effects of the Ce{sup 3+} ions and oxygen vacancies. - Highlights: • Hexagonal CeO{sub 2} nanosheets with superexerllent RTFM are synthesized by a facile hydrothermal method. • RTFM mechanism of CeO{sub 2} nanosheets can be attributed to the influences of oxygen vacancies and Ce{sup 3+} ions. • A defect driven dissolution–recrystallization mechanism is suggested to explain the transformation from nanowires to nanosheets.

  14. Structure and photoluminescence properties of Na{sub 2}Y{sub 2}B{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+} phosphors for solid-state lighting application

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Dawei; Yang, Hui; Yang, Guanhui; Shi, Jianxin, E-mail: cessjx@mail.sysu.edu.cn; Wu, Mingmei, E-mail: ceswmm@mail.sysu.edu.cn; Su, Qiang

    2014-05-01

    Novel phosphors of Na{sub 2}Y{sub 2}B{sub 2}O{sub 7}:Ce{sup 3+} and Na{sub 2}Y{sub 2}B{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+} were synthesized by a solid-state process and characterized with X-ray diffraction, photoluminescence (PL), PL excitation (PLE), and fluorescence decay time. The relationship between the observed Ce{sup 3+} emission properties and the crystal structure of Na{sub 2}Y{sub 2}B{sub 2}O{sub 7} is built and the result shows that Ce{sup 3+} ions occupy two non-equivalent Y{sup 3+} sites in the host. The codoping of Tb{sup 3+} in Na{sub 2}Y{sub 2}B{sub 2}O{sub 7}:Ce{sup 3+} can tune the emitting colour from blue to green and increase the luminescence quantum efficiency to 75.2% by the energy transfer of Ce{sup 3+}→Tb{sup 3+}. The energy transfer processes of Ce{sup 3+}–Ce{sup 3+} and Ce{sup 3+}–Tb{sup 3+} are analysed and determined to be electric dipole–dipole and dipole–quadrupole, respectively. The broad PLE spectra of Na{sub 2}Y{sub 2}B{sub 2}O{sub 7}:Ce{sup 3+} and Na{sub 2}Y{sub 2}B{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+} are well matched with the emission from near UV LED chips, which indicates that they are promising blue and green phosphors for phosphor-converted white LEDs. - Graphical abstract: Colour-tunable phosphors Na{sub 2}Y{sub 2}B{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+} with optimal quantum yield of 75.2% are synthesized and the phosphors can be served as n-UV pumped materials for LEDs. - Highlights: • Green phosphor Na{sub 2}Y{sub 2}B{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+} with quantum efficiency of 75.2% for n-UV application is synthesized. • The site occupation of Ce{sup 3+} in Na{sub 2}Y{sub 2}B{sub 2}O{sub 7} is investigated with the crystal structure and photoluminescence spectra. • The energy transfer of Ce{sup 3+}–Ce{sup 3+} and Ce{sup 3+}–Tb{sup 3+}, which is responsible to the tunable emitting colour of the phosphor, is demonstrated and the mechanism is studied.

  15. Luminescence properties of Ce{sup 3+} co-activated LaPO{sub 4}:Dy{sup 3+} nanorods prepared in different solvents and tunable blue to white light emission from Eu{sup 3+} co-activated LaPO{sub 4}:Dy{sup 3+}, Ce{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Phaomei, Ganngam [Department of Chemistry, Manipur University, Manipur 795003 (India); Rameshwor Singh, W., E-mail: dr.rmsingh@yahoo.co.in [Department of Chemistry, Manipur University, Manipur 795003 (India); Shanta Singh, N. [Department of Physics, Manipur University, Manipur 795003 (India); Ningthoujam, R.S., E-mail: nraghu_mani@yahoo.co.in [Chemistry Division, Bhabha Atomic Research Center, Mumbai 400085 (India)

    2013-02-15

    The nanorods of Ce{sup 3+} sensitized LaPO{sub 4}:Dy{sup 3+} with and without co-activation of Eu{sup 3+} have been synthesized by simple chemical route at relatively low temperature (150 Degree-Sign C). Effect of solvents on photoluminescence properties of Ce{sup 3+} sensitized LaPO{sub 4}:Dy{sup 3+} is studied by taking different solvents such as water, ethylene glycol (EG), dimethyl sulfoxide (DMSO) and their mixture. The samples prepared in EG and DMSO show monoclinic phase, whereas the samples prepared in water and mixed solvents show hexagonal phase. This hexagonal phase is transformed to monoclinic phase when the sample is heated at or above 600 Degree-Sign C and exhibits less luminescence intensity than that in monoclinic phase. The luminescence intensity of Dy{sup 3+} is enhanced when co-doped with Ce{sup 3+} because of energy transfer process. The luminescence color can be tuned from blue to white when Eu{sup 3+} is co-doped into LaPO{sub 4}:Dy{sup 3+}, Ce{sup 3+}. The prepared nanoparticles are dispersible and their polymer films are prepared after incorporation in to the polymer matrix. - Graphical Abstract: White emission production from Ce{sup 3+} sensitized LaPO{sub 4}:Dy{sup 3+}, Eu{sup 3+} nanorods. Highlights: Black-Right-Pointing-Pointer Synthesis of Ce{sup 3+} sensitized LaPO{sub 4}:Dy{sup 3+} nanorods. Black-Right-Pointing-Pointer Photoluminescence properties of samples prepared in different solvents. Black-Right-Pointing-Pointer Tuning of color from blue to white on co-doping of Eu{sup 3+} in LaPO{sub 4}:Dy{sup 3+}, Ce{sup 3+}. Black-Right-Pointing-Pointer Dispersion of particles in polar medium. Black-Right-Pointing-Pointer Polymer based film formation.

  16. The Reaction of bis(1,2,4-tri-t-butylcyclopentadienyl)ceriumbenzyl, Cp'2CeCH2Ph with Methylhalides: a Metathesis Reaction that does not proceed by a Metathesis Transition State

    Energy Technology Data Exchange (ETDEWEB)

    Werkema, Evan; Andersen, Richard; Maron, Laurent; Eisenstein, Odile

    2009-09-02

    The experimental reaction between [1,2,4-(Me3C)3C5H2]2CeCH2Ph and CH3X, X = F, Cl, Br, and I, yields the metathetical exchange products, [1,2,4-(Me3C)3C5H2]2CeX and CH3CH2Ph. The reaction is complicated by the equilibrium between the benzyl derivative and the metallacycle [[1,2,4-(Me3C)3C5H2] [(Me3C)2C5H2C(CH3)2CH2]Ce, plus toluene since the metallacycle reacts with CH3X. Labelling studies show that the methyl group of the methylhalide is transferred intact to the benzyl group. The mechanism, as revealed by DFT calculations on (C5H5)2CeCH2Ph and CH3F, does not proceed by way of a four-center mechanism, (sigma-bond metathesis) but a lower barrier process involves a haptotropic shift of the Cp2Ce fragment so that at the transition state the para-carbon of the benzene ring is attached to the Cp2Ce fragment while the CH2 fragment of the benzyl group attacks CH3F that is activated by coordination to the metal ion. As a result the mechanism is classified as an associative interchange process.

  17. CeO{sub 2} nanoparticles decorated multi-walled carbon nanotubes for electrochemical determination of guanine and adenine

    Energy Technology Data Exchange (ETDEWEB)

    Wei Yan [College of Chemistry and Materials Sciences, Anhui Normal University, Wuhu 241000 (China); Department of Chemistry, Wannan Medical College, Wuhu 241002 (China); Huang Qinan [Department of Chemistry, Wannan Medical College, Wuhu 241002 (China); Li Maoguo [College of Chemistry and Materials Sciences, Anhui Normal University, Wuhu 241000 (China); Huang Xingjiu [Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031 (China); Fang Bin, E-mail: binfang_47@yahoo.com.cn [College of Chemistry and Materials Sciences, Anhui Normal University, Wuhu 241000 (China); Wang Lun, E-mail: wanglun@mail.ahnu.edu.cn [College of Chemistry and Materials Sciences, Anhui Normal University, Wuhu 241000 (China)

    2011-10-01

    Sub-10 nm CeO{sub 2} nanoparticles decorated multi-walled carbon nanotubes has been constructed for electrochemial determination of guanine and adenine. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to characterize the nanoparticles CeO{sub 2}/MWCNTs. Electrochemical impedance spectroscopy (EIS) was used to characterize the electrode modifying process. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to study the electrocatalytic activity toward the electrochemical oxidation of guanine and adenine. The detection limit (S/N = 3) for adenine and guanine was found to be 20 and 10 nM, respectively. The obtained sensitivity toward guanine and adenine was 1.26 and 1.13 {mu}A/{mu}M in the linear concentration range 5-50 {mu}M and 5-35 {mu}M, respectively. These results demonstrate that the carbon nanotubes could provide huge locations and facilitate the adsorptive accumulation of the guanine and adenine, and the CeO{sub 2} nanoparticles are promising substrates for the development of high-performance electrocatalysts for biosensing.

  18. Citric Gel Synthesis and Luminescent Properties of Ce3+-Activated SrGa2O4 Phosphor

    Institute of Scientific and Technical Information of China (English)

    Qiao Bin; Tang Zilong; Zhang Zhongtai; Chen Lei

    2007-01-01

    Ce3+-activated SrGa2O4 phosphor was synthesized by a method of citric gel, wherein citric acid served as a chelate agent, and the as-synthesized powder was calcined in a slightly reduced ambient. The crystallization characteristics of the sample varied with the calcining temperature. Compared with the phosphor prepared by the solid-state reaction, the phosphor synthesized by citric gel was calcined at a relatively lower temperature. Consequently, the volatilization of Ga2O3 during high-temperature calcining process was avoided. The typical double-peak emission of Ce3+ originated from 2D(5d)→4F5/2(4f), and 2D(5d)→4F7/2(4f) was observed, and the intrinsic emission of SrGa2O4 host was much restricted. The emission intensity varied with the calcining temperature because the different crystallinity and the optimal concentration of Ce-dopant was determined at 3%.

  19. miRSponge: a manually curated database for experimentally supported miRNA sponges and ceRNAs.

    Science.gov (United States)

    Wang, Peng; Zhi, Hui; Zhang, Yunpeng; Liu, Yue; Zhang, Jizhou; Gao, Yue; Guo, Maoni; Ning, Shangwei; Li, Xia

    2015-01-01

    In this study, we describe miRSponge, a manually curated database, which aims at providing an experimentally supported resource for microRNA (miRNA) sponges. Recent evidence suggests that miRNAs are themselves regulated by competing endogenous RNAs (ceRNAs) or 'miRNA sponges' that contain miRNA binding sites. These competitive molecules can sequester miRNAs to prevent them interacting with their natural targets to play critical roles in various biological and pathological processes. It has become increasingly important to develop a high quality database to record and store ceRNA data to support future studies. To this end, we have established the experimentally supported miRSponge database that contains data on 599 miRNA-sponge interactions and 463 ceRNA relationships from 11 species following manual curating from nearly 1200 published articles. Database classes include endogenously generated molecules including coding genes, pseudogenes, long non-coding RNAs and circular RNAs, along with exogenously introduced molecules including viral RNAs and artificial engineered sponges. Approximately 70% of the interactions were identified experimentally in disease states. miRSponge provides a user-friendly interface for convenient browsing, retrieval and downloading of dataset. A submission page is also included to allow researchers to submit newly validated miRNA sponge data. Database URL: http://www.bio-bigdata.net/miRSponge.

  20. Effect of hot plastic deformation on microstructure and mechanical property of Mg-Mn-Ce magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Hot plastic deformation was conducted using a new solid die on a Mg-Mn-Ce magnesium alloy. The results of microstructural examination through OM and TEM show that the grain size is greatly refined from 45 μm to 1.1 μm with uniform distribution due to the occurrence of dynamic recrystallization. The grain refinement and high angle grain boundary formation improve the mechanical properties through tensile testing with the strain rate of 1.0× 10-4 s-1 at room temperature and Vickers microhardness testing. The maximum values of tensile strength, elongation and Vickers microhardness are increased to 256.37 MPa,17.69% and HV57.60, which are 21.36%, 133.80% and 20.50% more than those of the as-received Mg-Mn-Ce magnesium alloy,respectively. The SEM morphologies of tens