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Sample records for ce lummus cffc process

  1. Photodynamic Processes in Fluoride Crystals Doped with Ce3+

    Directory of Open Access Journals (Sweden)

    Pavlov V.V.

    2015-01-01

    Full Text Available Integrated studies of photoelectric phenomena and their associated photodynamic processes in LiCaAlF6, LiLuF4, LiYF4, LiY0,5Lu0,5F4, SrAlF5 crystals doped with Ce3+ ions have been carried out using the combination of the methods of optical and dielectric spectroscopy. The numerical values of the basic parameters of photodynamic processes and their spectral dependence in 240 – 310 nm spectral range are evaluated. It has been shown that the most probable process, which leads to the photoionization of Ce3+ ions in LiYxLu1-xF4:Ce3+ (x=0; 0,5; 1 and LiCaAlF6:Ce3+ crystals, is excited-state absorption to the states of mixed configurations of Ce3+ ions localized near/in the conduction band of crystal.

  2. CE IGCC Repowering plant sulfuric acid plant. Topical report, June 1993

    Energy Technology Data Exchange (ETDEWEB)

    Chester, A.M.

    1993-12-01

    A goal of the CE IGCC Repowering project is to demonstrate a hot gas clean-up system (HGCU), for the removal of sulfur from the product gas stream exiting the gasifier island. Combustion Engineering, Inc. (ABB CE) intends to use a HGCU developed by General Electric Environmental Services (GEESI). The original design of this system called for the installation of the HGCU, with a conventional cold gas clean-up system included as a full-load operational back-up. Each of these systems removes sulfur compounds and converts them into an acid off-gas. This report deals with the investigation of equipment to treat this off-gas, recovering these sulfur compounds as elemental sulfur, sulfuric acid or some other form. ABB CE contracted ABB Lummus Crest Inc. (ABB LCI) to perform an engineering evaluation to compare several such process options. This study concluded that the installation of a sulfuric acid plant represented the best option from both a technical and economic point of view. Based on this evaluation, ABB CE specified that a sulfuric acid plant be installed to remove sulfur from off-gas exiling the gas clean-up system. ABB LCI prepared a request for quotation (RFQ) for the construction of a sulfuric acid production plant. Monsanto Enviro-Chem Inc. presented the only proposal, and was eventually selected as the EPC contractor for this system.

  3. Energy migration processes in undoped and Ce-doped multicomponent garnet single crystal scintillators

    International Nuclear Information System (INIS)

    Multicomponent garnets (Y3−xGdxAl5−yGayO12) doped with Ce3+ ions are promising scintillators with a high density, fast response time and high light yield. To deepen the knowledge about the transfer stage of scintillation mechanism we discuss the energy migration and energy transfer processes in the set of undoped and Ce3+ activated multicomponent garnet single crystals. Temperature dependence of Gd3+ emission intensities as well as decay kinetics in Y3−xGdxAl5−yGayO12 (x,y=1,2,3) crystals point to the Gd3+→Gd3+ nonradiative energy migration, which is diffusion limited. Concentration quenching of Gd3+ emission occurs by energy migration to accidental impurities and/or structure defects. Temperature dependence of photoluminescence emission intensities and decay time measurements of Gd3+ as well as Ce3+ ions in Gd3Ga3Al2O12:Ce3+ single crystal reveal nonradiative energy transfer Gd3+→Ce3+ (including migration through Gd3+ sublattice) which is responsible for slow Ce3+ fluorescence decay component. - Highlights: • Gd3+and Ce3+ luminescence features in Y3−xGdxAl5−yGayO12 measured. • Temperature dependence of emission spectra and decays studied. • Concentration dependence of Gd3+ emission and decay time features investigated. • Energy migration and transfer processes in Gd-sublattice discussed

  4. Energy migration processes in undoped and Ce-doped multicomponent garnet single crystal scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Bartosiewicz, K., E-mail: bartosiewicz@fzu.cz [Institute of Physics AS CR, Cukrovarnicka 10, Prague 16253 (Czech Republic); Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, Praha 1 11519 (Czech Republic); Babin, V. [Institute of Physics AS CR, Cukrovarnicka 10, Prague 16253 (Czech Republic); Kamada, K. [NICHe, Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Yoshikawa, A. [NICHe, Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan); Nikl, M. [Institute of Physics AS CR, Cukrovarnicka 10, Prague 16253 (Czech Republic)

    2015-10-15

    Multicomponent garnets (Y{sub 3−x}Gd{sub x}Al{sub 5−y}Ga{sub y}O{sub 12}) doped with Ce{sup 3+} ions are promising scintillators with a high density, fast response time and high light yield. To deepen the knowledge about the transfer stage of scintillation mechanism we discuss the energy migration and energy transfer processes in the set of undoped and Ce{sup 3+} activated multicomponent garnet single crystals. Temperature dependence of Gd{sup 3+} emission intensities as well as decay kinetics in Y{sub 3−x}Gd{sub x}Al{sub 5−y}Ga{sub y}O{sub 12} (x,y=1,2,3) crystals point to the Gd{sup 3+}→Gd{sup 3+} nonradiative energy migration, which is diffusion limited. Concentration quenching of Gd{sup 3+} emission occurs by energy migration to accidental impurities and/or structure defects. Temperature dependence of photoluminescence emission intensities and decay time measurements of Gd{sup 3+} as well as Ce{sup 3+} ions in Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:Ce{sup 3+} single crystal reveal nonradiative energy transfer Gd{sup 3+}→Ce{sup 3+} (including migration through Gd{sup 3+} sublattice) which is responsible for slow Ce{sup 3+} fluorescence decay component. - Highlights: • Gd{sup 3+}and Ce{sup 3+} luminescence features in Y{sub 3−x}Gd{sub x}Al{sub 5−y}Ga{sub y}O{sub 12} measured. • Temperature dependence of emission spectra and decays studied. • Concentration dependence of Gd{sup 3+} emission and decay time features investigated. • Energy migration and transfer processes in Gd-sublattice discussed.

  5. Parallel Signal Processing and System Simulation using aCe

    Science.gov (United States)

    Dorband, John E.; Aburdene, Maurice F.

    2003-01-01

    Recently, networked and cluster computation have become very popular for both signal processing and system simulation. A new language is ideally suited for parallel signal processing applications and system simulation since it allows the programmer to explicitly express the computations that can be performed concurrently. In addition, the new C based parallel language (ace C) for architecture-adaptive programming allows programmers to implement algorithms and system simulation applications on parallel architectures by providing them with the assurance that future parallel architectures will be able to run their applications with a minimum of modification. In this paper, we will focus on some fundamental features of ace C and present a signal processing application (FFT).

  6. Effective thickness of CeO2 buffer layer for YBCO coated conductor by advanced TFA-MOD process

    International Nuclear Information System (INIS)

    YBCO films were fabricated on PLD-CeO2/IBAD-Gd2Zr2O7/Hastelloy substrates using the advanced TFA-MOD process. The effective thickness of the CeO2 buffer layer for obtaining high Ic was investigated in short samples of YBCO films. The CeO2 buffer layer was epitaxially grown on an IBAD-Gd2Zr2O7 template tape with 18 deg. of Δφ by a reel-to-reel PLD system. The in-plane grain alignment of PLD-CeO2 buffer layers rapidly improved with the thickness and saturated at a critical thickness of 0.8 μm. The size of CeO2 grains was about 1 μm at the saturated thickness of Δφ. YBCO films with the thickness of 1 μm were deposited by the TFA-MOD on the CeO2 buffer layer with different thickness films. Improvement of the CeO2 in-plane grain alignment resulted in increase of Ic. The Ic values of 250-290 A were obtained with the CeO2 layer thicker than 0.8 μm. The CeO2 thickness, at which the intensity ratio of the BaCeO3 was saturated, corresponded to the critical thickness. From the view points of achieving higher production rates and to obtain the CeO2 Δφ value of 5 deg. as well as considering the reaction between YBCO and CeO2, the optimum thickness of the CeO2 buffer layer on the IBAD-Gd2Zr2O7 with 18 deg. of Δφ was found to be at least 0.8 μm

  7. The effects of physicochemical properties of CeO2 nanoparticles on toxicity to soil denitrification processes

    Science.gov (United States)

    Dahle, Jessica Teague

    The studies presented in this thesis identify the impact of NP CeO 2 on soil denitrifying microbial communities and reveal that physical and chemical characteristics including particle size, speciation, concentration, pH, and presence of ligands are key to predicting environmental fate and reactivity of NP CeO2 in the soil. A review of the literature in Chapter 1 revealed a widespread lack of toxicological information for soil exposures to NP CeO2. Soil denitrifying bacteria are a keystone species because they serve an important role in the global nitrogen cycle controlling the atmospheric nitrogen input. Soil denitrifiers are important to this study because the reducing conditions during denitrification could induce phase transformation of Ce(IV) to Ce(III), potentially influencing the toxicity of Ce. Cerium is well known for being the only lanthanide that is thermodynamically stable in both the trivalent and tetravalent state in low temperature geochemical environments. Using well characterized NP Ce(IV)O 2 as well as bulk soluble Ce(III), batch denitrification experiments were conducted to evaluate the toxicity of Ce species to the denitrifying community in a Toccoa sandy loam soil. The statistical analysis on the antimicrobial effect on soil denitrifiers was conducted using both steady-state evaluation and zero-order kinetic models in order to compare the toxicity of the Ce(III) species to the NPs. These studies, presented in Chapter 3, show that soluble Ce(III) is far more toxic than Ce(IV)O2 NPs when an equal total concentration of Ce is used, though both species exhibit toxicity to the denitrifiers via statistically significant inhibition of soil denitrification processes. Particle-size dependent toxicity, species-dependent toxicity, and concentration-dependent toxicity were all observed in this study for both the steady-state and the kinetic evaluations. The possibility of toxicity enhancement and diminishment via dissolution and ligand complexation

  8. 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.

  9. 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

  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. PMID:22907449

  12. Photodynamic Processes and Lasing in Ce,Yb:LiYXLu1-XF4 Crystals

    Directory of Open Access Journals (Sweden)

    Nurtdinova L.A.

    2015-01-01

    Full Text Available Measurements of photoconductivity were conducted in LiYXLu1-XF4:RE (RE = Ce(1%, Yb (1%; x = 0..1 crystals. It was found that the excited state absorption transitions of Ce3+ ions are intracenter and terminate at 6s state of cerium ions. Lasing at room temperature was achieved, differential gain (up to ~22% and tuning range were determined. By lowering the temperature of the active element and using additional antisolarant pumping at 532 nm lasing differential gain efficiency was increased (up to ~ 35%, and the tuning range was expanded.

  13. 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.

  14. Chlorine/chloride based processes for uranium ores

    International Nuclear Information System (INIS)

    The CE Lummus Minerals Division was commissioned by The Department of Supply and Services to develop order-of-magnitude capital and operating cost estimates for chlorine/chloride-based processes for uranium ores. The processes are designed to remove substantially all radioactive consituents from the ores to render the waste products harmless. Two processes were selected, one for a typical low grade ore (2 lb. U3O8/ton ore) and one for a high grade ore (50 lbs U3O8 /ton). For the low grade ore a hydrochloric acid leaching process was chosen. For high grade ore, a more complex process, including gaseous chlorination, was selected. Capital cost estimates were compiled from information obtained from vendors for the specified equipment. Building cost estimates and the piping, electrical and instrumentation costs were developed from the plant layout. Utility diagrams and mass balances were used for estimating utilities and consumables. Detailed descriptions of the bases for capital and operating cost estimates are given

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

    OpenAIRE

    Ye, Bin; Miao, Jilang; 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, ...

  16. Improving CE with PDM

    NARCIS (Netherlands)

    Wognum, P.M. (Nel); Bondarouk, T.V. (Tanya); Weber, F.; Pawar, K.S.; Thoben, K.D.

    2003-01-01

    The concept of Concurrent Engineering (CE) centers around the management of information so that the right information will be at the right place at the right time and in the right format. Product Data Management (PDM) aims to support a CE way of working in product development processes. In specific

  17. New insight into the promoting role of process on the CeO₂-WO₃/TiO₂ catalyst for NO reduction with NH₃ at low-temperature.

    Science.gov (United States)

    Zhang, Shule; Zhong, Qin; Shen, Yuge; Zhu, Li; Ding, Jie

    2015-06-15

    This study aimed at investigating the reason of high catalytic activity for CeO2-WO3/TiO2 catalyst from the aspects of WO3 interaction with other species and the NO oxidation process. Analysis by X-ray diffractometry, photoluminescence spectra, diffuse reflectance UV-visible, X-ray photoelectron spectroscopy, density functional theory calculations, electron paramagnetic resonance spectroscopy, temperature-programmed-desorption of NO and in situ diffuse reflectance infrared transform spectroscopy showed that WO3 could interact with CeO2 to improve the electron gaining capability of CeO2 species. In addition, WO3 species acted as electron donating groups to transfer the electrons to CeO2 species. The two aspects enhanced the formation of reduced CeO2 species to improve the formation of superoxide ions. Furthermore, the Ce species were the active sites for the NO adsorption and the superoxide ions over the catalyst needed oxidizing the adsorbed NO to improve the NO oxidation. This process was responsible for the high catalytic activity of CeO2-WO3/TiO2 catalyst. PMID:25746195

  18. 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.

  19. Sol-gel processing and physic-chemical characterization of La and Ce doped lead titanate ceramics

    Directory of Open Access Journals (Sweden)

    Guaaybess Y.

    2013-09-01

    Full Text Available PbTiO3 (PT sol gel processed powders doped with lanthanum (PLT14 and cerium (PLCexT14, x = 1; 3; 6; 10 were characterized by XRD and Raman spectroscopy. The samples crystallize in a pure perovskite phase at temperatures smaller than those reported for the same compounds prepared by other conventional methods. The effect of cerium or/and lanthanum on the crystal structure, microstructural and dielectric properties of PbTiO3 were investigated using FTIR, XRD, SEM, Raman spectroscopy and impedance spectroscopy. Incorporation of Ce reduces the temperature of crystallization of the samples, the temperature of the maximum of the permittivity and the diffuseness character of the ferroelectric to paraelectric transition, and enhances the permittivity.

  20. 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.

  1. Study on Electroless Plating Ni-Ce-P Process on 27SiMn Surface%27SiMn化学镀Ni-Ce-P工艺研究

    Institute of Scientific and Technical Information of China (English)

    任鑫; 杜学芸; 侯静; 谷永旭

    2011-01-01

    Based on the mining hydraulic support column 27SiMn, the cerous sulfate was added to the electroless Ni-P solution. The plating velocity was used as an evaluation indice, the optimum technology was obtained by orthogonal test. At the same time, the morphology of the plating obtained at the optimum technology was analyzed. The results show that the plating velocity reaches 33.38 μm/h under the condition of the solution containing 40 mg/L cerous sulfate. Compared with the electroless plating Ni-P coating, Ni-Ce-P plating surface becomes more compact and smooth.%以液压支架立柱常用材料27SiMn为基体,在Ni-P化学镀的基础上加入稀土硫酸高铈.通过正交试验对施镀工艺参数进行优化,以镀速为评定指标,获得了化学镀Ni-Ce-P的最优工艺配方,并对最优工艺条件下得到镀层的形貌进行了分析.结果表明:含有40 mg/L硫酸高铈的最优配方下的镀速为33.38 μm/h;相对于二元Ni-P镀层,加入稀土得到的镀层胞状结构更细小,表面更加平整、致密.

  2. 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.

  3. Prenatal care in the primary health care network in FortalezaCE: an assessment of the structure, process and results

    Directory of Open Access Journals (Sweden)

    Rebeca Silveira Rocha

    2012-09-01

    Full Text Available Objective: To evaluate the prenatal care assistance in the primary health care network in Fortaleza-CE, considering the structure, process and results. Methods: A cross sectional descriptive study, of quantitative approach, performed between October 2009 and February 2011, in 30 Health Units randomly selected, keeping the ratio for each Regional Executive Secretary. For analysis of the structure, the information obtained was scored and classified as: excellent, satisfactory, precarious or insufficient. The form used was submitted to four experts for validation. In evaluating the process and results, data was available by the Municipal Health Secretary of Fortaleza for obtainance of the indicators recommended by the Ministry of Health. Results: There was, in general, a satisfactory structure. As for the process and result, we obtained: pregnant women who had, at least, six prenatal visits (7.6%; pregnant women who received tetanus immunization (22.8%; newborns with congenital syphilis (1.4%; newborns with neonatal tetanus (0%; maternal mortality rate (78.5% in 2008 and 51% in 2009 and total neonatal mortality rate (10.1% in 2008 and 11.2% in 2009. Conclusions: Despite good results with regard to the structure, the reflections on the process and outcome indicators were not positive, with low rates compared to those expected by the World Health Organization or the Ministry of Health, or in comparison with other regions.

  4. Effect of oxygen partial pressure on the morphology and properties of Ce doped YBCO films fabricated by a MOCVD process

    International Nuclear Information System (INIS)

    Rare-earth (RE) (e.g. Sm, Dy, Ce, etc.) doping has been widely investigated to improve critical current density (Jc) of YBa2Cu3O7-X (YBCO) coated conductors (CC). Oxygen partial pressure is known to be a key parameter in terms of affecting the Jc of YBCO films. In this work, the effect of oxygen partial pressure on the microstructure and Jc of a Ce doped YBCO film was examined. Ce doped YBCO films were deposited on (1 0 0) SrTiO3 (STO) single crystal substrates at oxygen partial pressures of 2.5, 5.0, and 10.0 Torr using a metal organic chemical vapor deposition (MOCVD) method. Due to the enhanced migration of surface adatoms under reduced oxygen partial pressure, a 1 wt% Ce doped YBCO film had a stoichiometric, dense surface. In addition, the zero-field Jc (at 77 K) of the 1 wt% Ce doped YBCO film deposited at reduced oxygen partial pressure was increased. Irrespective of the amount of Ce, the Ce doped YBCO film showed an increased zero-field Jc (at 77 K) under reduced oxygen partial pressure.

  5. Synthesis of CeO2 Nanoparticles by Azeotropic Distillation Processing%共沸蒸馏法合成CeO2纳米颗粒研究

    Institute of Scientific and Technical Information of China (English)

    宋晓岚; 何希; 曲鹏; 江楠; 邱冠周

    2008-01-01

    分别以乙醇、正丙醇、异丙醇、正丁醇、异丁醇、仲丁醇及叔丁醇等七种有机醇作为共沸剂,采用液相沉淀法结合共沸蒸馏处理前驱体成功合成了分散性良好、粒子尺寸分布为10~20nm的纳米CeO2颗粒,运用TG/DTA、FIIR、XRD、TEM等方法对不同有机醇的共沸蒸馏作用以及产品性能进行了分析和表征,探讨了共沸蒸馏法制备纳米CeO2的机理.结果表明:共沸蒸馏能起到有效脱除前驱体凝胶中的水分,防止其干燥和焙烧过程中的硬团聚形成的作用,其中七种醇中以正丁醇的共沸蒸馏效果最佳,所得纳米CeO2颗粒的粒度、均匀及分散性能最好.%CeO2 nanoparticles were synthesized by precipitation method.The azeotropic distillation technique was carried out to dehydrate hydrous gels and ensure complete elimination of the residual water in the precursors.The effects of seven different alcohols(ethanol,n-propyl alcohol,isopropanol,n-butyl alcohol,isobutanol,secondary butyl alcohol,tert-butyl alcohol)as entrainer were compared with each other.DSC(different scanning calorimetry)/TG(thermalgravimetric),FI-IR(Infra-red spectrum analysis),XRD(X-ray diffraction)and TEM(transmission electron spectroscopy)were performed to characterize the structures and properties of CeO2 nanoparticles.Among seven alcahols,n-butyl aleohol has the best effect during azeotropic distillation.After azeotropic distillation with n-butyl alcohol,particles with well dispersity and an average size of 10~20nm were obtained.The azeotropic distillation processing Was proved to be quite effective in reduced the possibility of the formation of chemical bonds and prevented the formation of hard agglomerates.

  6. Adsorption and dissociation of molecular hydrogen on Pt/CeO2 catalyst in the hydrogen spillover process: A quantum chemical molecular dynamics study

    International Nuclear Information System (INIS)

    Ultra accelerated quantum chemical molecular dynamics method (UA-QCMD) was used to study the dynamics of the hydrogen spillover process on Pt/CeO2 catalyst surface for the first time. The direct observation of dissociative adsorption of hydrogen on Pt/CeO2 catalyst surface as well as the diffusion of dissociative hydrogen from the Pt/CeO2 catalyst surface was simulated. The diffusion of the hydrogen atom in the gas phase explains the high reactivity observed in the hydrogen spillover process. Chemical changes, change of adsorption states and structural changes were investigated. It was observed that parallel adsorption of hydrogen facilitates the dissociative adsorption leading to hydrogen desorption. Impact with perpendicular adsorption of hydrogen causes the molecular adsorption on the surface, which decelerates the hydrogen spillover. The present study also indicates that the CeO2 support has strong interaction with Pt catalyst, which may cause an increase in Pt activity as well as enhancement of the metal catalyst dispersions and hence increasing the rate of hydrogen spillover reaction.

  7. 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).

  8. 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.

  9. 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%.

  10. Red electroluminescent process excited by hot holes in SrGa2S4:Ce, Mn thin film

    International Nuclear Information System (INIS)

    This paper reports the first observation of red electroluminescence (EL) in SrGa2S4:Ce, Mn thin film. The EL spectrum consists of single broad emission band having a peak wavelength of 665 nm. The dominant EL decay time was 31 μs. The relationship between the applied voltage and the EL waveform was measured in single insulating thin film electroluminescent (TFEL) devices. An asymmetric EL waveform was observed in SrGa2S4:Ce, Mn TFEL devices under a rectangular applied voltage. The polarity of the EL waveform in these devices was different from the waveform in manganese-activated zinc sulfide ZnS:Mn devices. This indicates that hot holes excite the Mn2+ ions to cause the red EL.

  11. Effect of Processing Parameters on Microstructure and Mechanical Properties of an Al-Al11Ce3-Al2O3 In-Situ Composite Produced by Friction Stir Processing

    NARCIS (Netherlands)

    Chen, C. F.; Kao, P. W.; Chang, L. W.; Ho, N. J.

    2010-01-01

    Friction stir processing (FSP) was applied to produce aluminum-based in-situ composites from powder mixtures of Al-5 mol pct CeO2. A billet of powder mixtures was prepared using the conventional pressing and sintering route. The sintered billet was then subjected to multiple passages of FSP. This te

  12. 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...

  13. Preparation and prop erties of Ce0.8Ca0.2O1.8 anode material by glycine-nitrate process

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ce0.8Ca0.2O1.8 (CDC82) anode material was prepared by glycine-nitrate process(GNP). Thermogravimetric(TG) analysis and differential scanning calorimetric(DSC) methods were adopted to characterize the reaction process of CDC82 material. X-ray diffractometry(XRD), scanning electron microcopy(SEM), direct current four probe (four-probe DC) and temperature process reduce(TPR) techniques were adopted to characterize the properties of CDC82 material. After the precursor was sintered at 750 ℃for 4 h, CDC82 material with pure-fluorite structure and nanometer size was obtained. The total conductivity of CDC82 changes little with temperature in air at 50-850 ℃, and the maximum value is 0.04 S/cm at 750 ℃. The total conductivity wholly becomes larger when the atmosphere changes from air to hydrogen, which greatly increases with increasing temperature and reaches the maximum value of 1.09 S/cm at 850 ℃. Some impurities such as CeMg and La2O3 exist after the mixture of CDC82 anode and La1-xSrxGa1-yMgyO3-δ (LSGM) electrolyte material is sintered at 1 200 ℃ for 15 h. The CDC82 material as anode material has excellent catalytic property for hydrogen and methane.

  14. Improvement of pre- and post-processing environments of the dynamic two-dimensional reservoir model CE-QUAL-W2 based on GIS.

    Science.gov (United States)

    Ha, S R; Bae, G J; Park, D H; Cho, J H

    2003-01-01

    An Environmental Information System (EIS) coupled with a Geographic Information System (GIS) and water quality models is developed to improve the pre- and post-data processing function of CE-QUAL-W2. Since the accuracy of the geometric data in terms of a diverse water body has a great effect on the water quality variables such as the velocity, kinetic reactions, the horizontal and vertical momentum, to prepare the bathymetry information has been considered a difficult issue for modellers who intend to use the model. For identifying Cross Section and Profile Information (CSPI), which precisely contains hydraulic features and geographical configuration of a waterway, the automated CSPI extraction program has been developed using Avenue Language of the PC Arc/view package. The program consists of three major steps: (1) getting the digital depth map of a waterway using GIS techniques; (2) creating a CSPI data set of segments in each branch using the program for CE-QUAL-W2 bathymetry input; (3) selecting the optimal set of bathymetry input by which the calculated water volume meets the observed volume of the water body. Through those approaches, it is clear that the model simulation results in terms of water quality as well as reservoir hydraulics rely upon the accuracy of bathymetry information. PMID:15137156

  15. 电沉积工艺参数对Ni-TiN-CeO_2二元纳米复合镀层中粒子复合量的影响%Effects of electrodeposition process parameters on particle contents of Ni-TiN-CeO2 composite coating

    Institute of Scientific and Technical Information of China (English)

    吴蒙华; 刘娜娜; 李智

    2012-01-01

    Ni-TiN-CeO2 binary nanocomposite coatings were prepared by ultrasonic-pulse electrodeposition, the effects of the electrodeposition process parameters on the particle content of the Ni-TiN-CeO2 composite coating were reasearched, the surface morphology and composition of the composite coating were also analysed. The re- sults showed that the optimal process parameters of the nanocomposite coating prepared by ultrasonic-pulse electrodeposition was: cathode current density of 4A/dm2 , adding amounts of TiN particles was 15g/L, adding amounts of CeO2 particles was 40g/L, positive pulse duty cycle of 20%, ultrasonic power of 180W. Under these optimum conditions, we could prepare Ni-TiN-CeO2 binary nanocomposite coatings with CeO2 and TiN particles mass fraction of 3.3% and 4.4% respectively. Meanwhile, with CeO2 and TiN particles adding to the bath, the composites of the two kinds of nanoparticles gave full play to the synergies, and optimized the sedi- mentary way of particles and metal matrix, the quality of the coatings was improved greatly.%采用超声-脉冲电沉积法制备了Ni-TiN-CeO2二元纳米复合镀层,研究了工艺参数对镀层中CeO2及TiN粒子复合量的影响,并对镀层的表面形貌及成分进行了测试和分析。结果表明,超声-脉冲电沉积Ni-TiN-CeO2纳米复合镀层的最佳工艺参数为阴极电流密度4A/dm2,TiN粒子添加量15g/L,CeO2粒子添加量40g/L,正向脉冲占空比20%,超声波功率180W。在该工艺条件下,可获得CeO2质量分数为3.3%、TiN质量分数为4.4%的Ni-TiN-CeO2二元纳米复合镀层。同时,TiN与CeO2二元纳米粒子的加入,充分发挥了两种纳米粒子复合的协同效应,优化了粒子与基质金属的共沉积方式,大大改善了镀层质量。

  16. 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)

  17. 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.

  18. Cathodoluminescence degradation of SiO2:Ce,Tb powder phosphors prepared by a sol-gel process

    International Nuclear Information System (INIS)

    Auger electron spectroscopy (AES), cathodoluminescence (CL) spectroscopy, and x-ray photoelectron spectroscopy (XPS) were used to study the CL intensity degradation of SiO2:Cb,Tb powder phosphors prepared by a sol-gel process. The AES and the CL data were collected simultaneously when the powders were bombarded for 10 h with a beam of electrons of current density of 54 mA/cm2, accelerated by 2 kV in a vacuum chamber containing either 1x10-8 or 1x10-7 Torr O2. A decrease of CL intensity was simultaneous with desorption of oxygen (O) from the surface, i.e., there is a correlation between the degradation of CL intensity and desorption of O. The AES and the XPS data suggest that a nonluminescent oxygen-deficient layer of SiOx (x<2) that could decrease the CL intensity was formed on the surface. Mechanisms by which oxygen desorption leads to a reduction of the CL intensity are discussed

  19. 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

  20. 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.

  1. Effects of calcining process and CeO2 on properties of (1-x)LaAlO3-xCaTiO3 microwave dielectric ceramics%预烧工艺和CeO2添加剂对(1-x)LaAlO3-xCaTiO3微波介质陶瓷性能的影响

    Institute of Scientific and Technical Information of China (English)

    薛田良; 付云侠; 夏俊芳

    2012-01-01

    利用常规固相法制备了[(1-x)LaAlO3-xCaTiO3]+yCeO2陶瓷(y为CeO2的质量分数),研究了预烧工艺和CeO2添加剂对所制陶瓷微波介电性能的影响.结果表明,LaAlO3与CaTiO3一次预烧能获得较好的微波介电性能,CeO2添加剂能有效提高材料的烧结性能和微波介电性能.(0.4LaAlO3-0.6CaTiO3)+0.2%CeO2陶瓷经1 450℃烧结5h后能获得最佳微波介电性能:εr=43.1、Q·f=29 700 GHz、τf=-2.4×10-6/℃.%[(l-x)LaA1O3-xCaTi03]+yCe02 ceramics(y was mass fraction of CeO2) were prepared by the solid-state reaction. The effects of calcining process and CeO2 addition on microwave dielectric properties of the [(l-x)LaA103-xCaTi03]+yCe02 ceramics were investigated. It shows that more excellent microwave dielectric properties are obtained when LaAlO3 and CaTiO3 are calcined together, and CeO2 addition can improve effectively the sinterablity and microwave dielectric properties of [(l-x)LaA103-xCaTi03]+yCe02 ceramics. (0.4LaAlO3-0.6CaTiO3)+0.2%CeO2 ceramics sintered at 1 450 ℃ for 5 h has best microwave dielectric properties with er of 43.1, Q ·f o f29 700 GHz and tfof-2.4× 10-6/ ℃.

  2. Violet-blue luminescence from hafnium oxide layers doped with CeCl{sub 3} prepared by the spray pyrolysis process

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Hipolito, M.; Alvarez-Fragoso, O.; Alvarez-Perez, M.A.; Martinez-Martinez, R. [Departamento de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico (Mexico); Caldino, U. [Universidad Autonoma Metropolitana, Iztapalapa, Mexico DF (Mexico); Falcony, C. [Departamento de Fisica, CINVESTAV-IPN, Mexico (Mexico)

    2007-07-15

    HfO{sub 2}:CeCl{sub 3} coatings were deposited by the spray pyrolysis method employing hafnium dichloride oxide and CeCl{sub 3} dissolved in deionized water (18 M{omega}/cm). The room temperature photoluminescence characteristics of the HfO{sub 2}:CeCl{sub 3} films were studied as a function of the deposition parameters such as doping concentrations and substrate temperature. The presence of two different Ce{sup 3+} centres in HfO{sub 2} is detected from photoluminescence measurements. A reduction of the luminescence intensity is observed with an increase of both the CeCl{sub 3} concentration and the deposition temperature. X-ray diffraction measurements of these films showed that the crystalline structure depends on the substrate temperature. For substrate temperatures less than 350 C the deposited films are almost amorphous, while substrate temperatures higher than 400 C produce diffraction peaks corresponding to the monoclinic phase of HfO{sub 2}. The chemical composition of the films as determined by energy dispersive spectroscopy is also reported. Furthermore, the surface morphology characteristics of the coatings, as a function of the deposition temperature, are also presented. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. 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.

  4. 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 proces...

  5. 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 p...

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. β-Cyclodextrin-assisted preparation of hierarchical walnut-like CeOHCO3 and CeO2 mesocrystals

    International Nuclear Information System (INIS)

    The hierarchical walnut-like CeOHCO3 mesocrystals were prepared by a facile hydrothermal method under low temperature with β-cyclodextrin (β-CD) as assistant agent. The hierarchical walnut-like CeO2 mesocrystals were obtained by thermal decomposition of CeOHCO3 mesocrystals. The crystal phase, morphology, and structure of CeOHCO3 and CeO2 mesocrystals were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). The time-dependent experimental results indicated that the morphology transformation from shuttle-like to walnut-like and the crystal phase transformation from orthorhombic to hexagonal simultaneously occurred in the formation processes of CeOHCO3 mesocrystals. On the basis of the morphological and crystal phase evolution processes, the formation mechanism of hierarchical walnut-like CeOHCO3 mesocrystals, including dissolution-recrystallization processes, was discussed. β-CD was believed to play an important role in the formation of the hierarchical walnut-like CeOHCO3 mesocrystals. The effects of reaction temperature, β-CD amount, and concentration of reactants on the morphologies of the products were systematically studied. CeO2 mesocrystals exhibited the distinct red-shift phenomenon in UV-vis absorption spectra.

  12. The determination of mass transfer coefficient on the extractions of Ce(IV) by D2EHPA was used tin layer process

    International Nuclear Information System (INIS)

    It has be done to determination of mass transfer coefficient on the extractions Ce (IV) by Di (2- ethylhexyl) phosphoric acid (D2EHPA) using CELL ARMOLLEX. CELL ARMOLLEX have two stirrers are top and down to make tin layer between organic face and water face to be constant so that diffusion mechanism reaction was took place. It was obtained that mass transfer coefficient on variation of acids 1-3 N = 2.50x10-3 - 1.06x10-3 ; on variation of concentration reactant 2.5 - 7.5% = 2.21x10-3 - 2.58x10-3 and on the variation of stirring speed = 4.703x10-3 - 1.88x10-4

  13. 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.  ……

  14. Optimization Of Process Parameters For The Production Of Bio diesel From Waste Cooking Oil In The Presence Of Bifunctional γ-Al2O3-CeO2 Supported Catalysts

    International Nuclear Information System (INIS)

    Huge quantities of waste cooking oils are produced all over the world every day, especially in the developed countries with 0.5 million ton per year waste cooking oil are being generated in Malaysia alone. Such large amount of waste cooking oil production can create disposal problems and contamination to water and land resources if not disposed properly. The use of waste cooking oil as feedstock for bio diesel production will not only avoid the competition of the same oil resources for food and fuel but will also overcome the waste cooking oil disposal problems. However, waste cooking oil has high acid value, thus would require the oil to undergo esterification with an acid catalyst prior to transesterification with a base catalyst. Therefore, in this study, bifunctional catalyst supports were developed for one-step esterification-transesterification of waste cooking oil by varying the CeO2 loading on γ-Al2O3. The bifunctional supports were then impregnated with 5 wt % Mo and characterized using N2 adsorption-desorption isotherm to determine the surface area of the catalysts while temperature programmed desorption with NH3 and CO2 as adsorbents were used to determine the acidity and basicity of the catalysts. Results show that the γ-Al2O3-CeO2 supported Mo catalysts are active for the one-step esterification-transesterification of waste cooking oil to produce bio diesel with the Mo/ γ-Al2O3-20 wt% CeO2 as the most active catalyst. Optimization of process parameters for the production of bio diesel from waste cooking oil in the presence of this catalyst show that 81.1 % bio diesel yield was produced at 110 degree Celsius with catalyst loading of 7 wt %, agitation speed of 600 rpm, methanol to oil ratio of 30:1 and reaction period of 270 minutes. (author)

  15. The evaluation of the x-ray fluorescence (XRF) technique for process monitoring of vitreous slag from thermal waste treatment systems: A comparative study of the analysis of Plasma Hearth slag for Ce, Fe and Cr by XRF and inductively coupled plasma spectrometries

    Energy Technology Data Exchange (ETDEWEB)

    Sutton, M.A.H.; Crane, P.J.; Cummings, D.G.; Carney, K.P.

    1995-05-01

    Slag material produced by the Plasma Hearth Process (PHP) varies in chemical composition due to the heterogeneous nature of the input sample feed. X-ray fluorescence (XRF) is a spectroscopic technique which has been evaluated to perform elemental analyses on surrogate slag material for process control. Vitreous slag samples were ground to a fine powder in an impact ball mill and analyzed directly using laboratory prepared standards. The fluorescent intensities of Si, Al and Fe in the slag samples was utilized to determine the appropriate matrix standard set for the determination of Ce. The samples were analyzed for Cr, Ni, Fe and Ce using a wavelength dispersive XRF polychromator. Split samples were dissolved and analyzed by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The precision of the XRF technique was better than 5% RSD. The limit of detection for Ce varied with sample matrix and was typically below 0.01% by weight. The linear dynamic range for the technique was evaluated over two orders of magnitude. Typical calibration standards ranged from 0.01% Ce to 1% Ce. The Ce determinations performed directly on ground slag material by the XRF techniques were similar to ICP-AES analyses. Various chemical dissolution and sample preparation techniques were evaluated for the analysis of Ce in slag samples. A fusion procedure utilizing LiBO{sub 2} was found to provide reliable analyses for the actinide surrogate in a variety of slag matrices. The use of the XRF technique reduced the time of analysis for Ce and Cr from three days to one day for five samples. No additional waste streams were created from the analyses by the XRF technique, while the ICP technique generated several liters of liquid waste.

  16. 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

  17. 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.

  18. 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...... savings in smart buildings. This system is connected to the cloud to have access to a number of advanced cloud-based services to enhance energy management in smart buildings. In this paper, we discuss the current limitations of BEMS, the conceptual design of the proposed system, and the advantages...

  19. 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.

  20. Biofunctionalization of CeF(3):Tb(3+) nanoparticles.

    Science.gov (United States)

    Kong, D Y; Wang, Z L; Lin, C K; Quan, Z W; Li, Y Y; Li, C X; Lin, J

    2007-02-21

    CeF(3):Tb(3+) nanoparticles (short pillar-like morphology with an average length and width of 11 and 5 nm, respectively) were successfully prepared by a polyol process using diethyleneglycol (DEG) as solvent. After being functionalized with a SiO(2)-NH(2) layer, these CeF(3):Tb(3+) nanoparticles can be conjugated with biotin molecules (activated by thionyl chloride) and further with avidin. The as-formed CeF(3):Tb(3+) nanoparticles, CeF(3):Tb(3+) nanoparticles functionalized with amino groups, biotin conjugated amino-functionalized CeF(3):Tb(3+) nanoparticles and biotinylated CeF(3):Tb(3+) nanoparticles bonded with avidin were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), UV/vis absorption spectra and luminescence spectra, respectively. The biofunctionalization of the CeF(3):Tb(3+) nanoparticles has less effect on their luminescence properties, i.e. they still show strong green emission (from Tb(3+), with (5)D(4)-(7)F(5) at 543 nm as the most prominent group), indicative of the great potential for these CeF(3):Tb(3+) nanoparticles to be used as biological fluorescence probes. PMID:21730503

  1. Biofunctionalization of CeF3:Tb3+ nanoparticles

    Science.gov (United States)

    Kong, D. Y.; Wang, Z. L.; Lin, C. K.; Quan, Z. W.; Li, Y. Y.; Li, C. X.; Lin, J.

    2007-02-01

    CeF3:Tb3+ nanoparticles (short pillar-like morphology with an average length and width of 11 and 5 nm, respectively) were successfully prepared by a polyol process using diethyleneglycol (DEG) as solvent. After being functionalized with a SiO2-NH2 layer, these CeF3:Tb3+ nanoparticles can be conjugated with biotin molecules (activated by thionyl chloride) and further with avidin. The as-formed CeF3:Tb3+ nanoparticles, CeF3:Tb3+ nanoparticles functionalized with amino groups, biotin conjugated amino-functionalized CeF3:Tb3+ nanoparticles and biotinylated CeF3:Tb3+ nanoparticles bonded with avidin were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), UV/vis absorption spectra and luminescence spectra, respectively. The biofunctionalization of the CeF3:Tb3+ nanoparticles has less effect on their luminescence properties, i.e. they still show strong green emission (from Tb3+, with 5D4-7F5 at 543 nm as the most prominent group), indicative of the great potential for these CeF3:Tb3+ nanoparticles to be used as biological fluorescence probes.

  2. Effect of scanning speeds on microstructure and wear behavior of laser-processed NiCr-Cr3C2-MoS2-CeO2 on 38CrMoAl steel

    Science.gov (United States)

    Sun, Guifang; Tong, Zhaopeng; Fang, Xiaoyu; Liu, Xiaojun; Ni, Zhonghua; Zhang, Wei

    2016-03-01

    Self-lubricating wear-resistant NiCr-Cr3C2-MoS2-CeO2 layers were fabricated on 38CrMoAl extruder screws by laser processing. The effect of scanning speeds on microstructure, phases, microhardness, and wear behavior was investigated. The obtained results indicate that the laser-processed layers had fine and nonuniform microstructures with undissolved MoS2 particles distributed on the matrix. With an increase of the laser-scanning speeds, the microstructures changed from hypoeutectic to hypereutectic, volume fraction of martensite increased, microhardness increased, and thickness and friction coefficients of the layers decreased. Wear resistance of the optimized layer was increased by 29.76 times compared with that of the substrate. The undissolved MoS2 was separated from the matrix on loading. In addition to the grain-refining and solution-strengthening effects, oxide films formed on the surface of the layers shielded them and enhanced their wear resistance. The crack or fracture behavior of the laser-processed layers on loading was determined by its toughness, which also had an important effect on the wear behavior of the processed layers.

  3. 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.

  4. Nioboaeschynite-(Ce, Ce(NbTiO6

    Directory of Open Access Journals (Sweden)

    Shaunna M. Morrison

    2012-08-01

    Full Text Available Nioboaeschynite-(Ce, ideally Ce(NbTiO6 [cerium(III niobium(V titanium(IV hexaoxide; refined formula of the natural sample is Ca0.25Ce0.79(Nb1.14Ti0.86O6], belongs to the aeschynite mineral group which is characterized by the general formula AB2(O,OH6, where eight-coordinated A is a rare earth element, Ca, Th or Fe, and six-coordinated B is Ti, Nb, Ta or W. The general structural feature of nioboaeschynite-(Ce resembles that of the other members of the aeschynite group. It is characterized by edge-sharing dimers of [(Nb,TiO6] octahedra which share corners to form a three-dimensional framework, with the A sites located in channels parallel to the b axis. The average A—O and B—O bond lengths in nioboaeschynite-(Ce are 2.471 and 1.993 Å, respectively. Moreover, another eight-coordinated site, designated as the C site, is also located in the channels and is partially occupied by A-type cations. Additionally, the refinement revealed a splitting of the A site, with Ca displaced slightly from Ce (0.266 Å apart, presumably resulting from the crystal-chemical differences between the Ce3+ and Ca2+ cations.

  5. 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.

  6. 球磨工艺参数对醇水系纳米CeO2悬浮液稳定性的影响%Effect of process parameters of ball mill on stability of nanometer CeO2 suspension in dispersion medium of water and alcohol

    Institute of Scientific and Technical Information of China (English)

    陈刚; 黎向锋; 左敦稳; 王宏宇; 孙玉利

    2011-01-01

    使用行星式球磨机分散醇水系纳米CeO2悬浮液,引入沉淀率及其变化量评价其分散稳定性,讨论了球磨时间、球料比、球磨机转速和纳米CeO2质量分数对分散稳定性的影响.通过破碎力打开团聚体的形式来分析球磨时间的影响,从颗粒受作用次数方面来讨论球料比的影响,球磨机转速是划分研磨力和冲击力的主次地位的重要参数;理论Ce2O质量分数和球料比的选择要综合考虑分散稳定性和球磨机的能量利用率.%In this work, the planetary mill was used to disperse nanometer CeO2 particles in the dispersion medium of water and alcohol. Precipitation rate (PR) and its varied quantity (PRVQ) were introduced to evaluate the stability of CeO2 suspension. Effect of ball milling time (BMT), ball to powder ratio (BPR), milling speed (MS) and theoretic mass fraction (TMF) of CeO2 particles on stability of CeO2 suspension was discussed. In terms of the crushing force opening the agglomerates, the effect of BMT was discussed. And in the respective of crushing frequency of particles, the effect of BPR was evaluated. MS was the significant factor of the division of the milling force and the impact force. The selections of TMF and BPR need to give consideration to dispersion stabilization, energy efficiency and PR in a comprehensive way.

  7. Ce que soigner veut dire

    OpenAIRE

    Mol, Annemarie

    2013-01-01

    Qu'est-ce que bien soigner? Dans ce livre provoquant et original, Annemarie Mol montre que ce n'est pas, comme on l'a beaucoup dit, laisser les patients choisir. À partir de l'exemple des personnes atteintes de diabète, l'auteur propose une nouvelle manière de prendre soin des personnes, qui ne les transforme pas en citoyens ou en consommateurs, mais qui les reconnaît comme corps et âmes souffrants, comme individus investis dans leur propre prise en charge, comme membres de collectifs multipl...

  8. 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.

  9. 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.

  10. 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.

  11. s-PROCESSING IN THE GALACTIC DISK. I. SUPER-SOLAR ABUNDANCES OF Y, Zr, La, AND Ce IN YOUNG OPEN CLUSTERS

    International Nuclear Information System (INIS)

    In a recent study based on homogeneous barium abundance measurements in open clusters (OCs), a trend of increasing [Ba/Fe] ratios for decreasing cluster age was reported. We present here further abundance determinations, relative to four other elements having important s-process contributions, with the aim of investigating whether or not the growth found for [Ba/Fe] is 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 width measurements and the MOOG code. Our sample includes 19 OCs of different ages, for which the spectra were obtained by the ESO Very Large 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 asymptotic giant branch stars (M∼sun) produce larger amounts of s-process elements (and hence activate the 13C-neutron source more effectively) than previously expected. Their role in producing neutron-rich elements in the Galactic disk has been so far underestimated, and their evolution and neutron-capture nucleosynthesis should now be reconsidered.

  12. Investigation on the nature of active species in the CeCl{sub 3}-doped sodium alanate system

    Energy Technology Data Exchange (ETDEWEB)

    Fan Xiulin; Xiao Xuezhang [Department of Materials Science and Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China); Chen Lixin, E-mail: lxchen@zju.edu.cn [Department of Materials Science and Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China); Li Shouquan; Wang Qidong [Department of Materials Science and Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China)

    2011-09-15

    Research highlights: > The additive of CeCl{sub 3} is reduced in doping process, causing the formation of NaCl and highly dispersed Ce species. > After dehydrogenation, Al-Ce alloy with a structure of CeAl{sub 4} comes into being and remains almost unchanged in the following cycles. > Directly doping CeAl{sub 4} into the system results in much similar kinetics. - Abstract: CeCl{sub 3}-doped NaAlH{sub 4} was directly synthesized in hydrogenation process using NaH/Al with 2 mol% CeCl{sub 3} under ball-milling. X-ray diffraction was utilized to unveil the nature of cerium during NaAlH{sub 4} synthesis process and succedent cycling. It is found that, CeCl{sub 3} is reduced in the ball-milling process and following cycles, causing the formation of NaCl and Al-Ce alloy with a structure of CeAl{sub 4}. The catalytic enhancement arising upon doping the ball-milled CeAl{sub 4} alloy is quite similar to that achieved in the CeCl{sub 3}-doped sodium alanate. Because the CeAl{sub 4} dopant does not consume the effective hydrogen storage component, the CeAl{sub 4}-doped NaAlH{sub 4} exhibits more hydrogen storage capacity. Moreover, CeCl{sub 3}-doped NaAlH{sub 4} and CeAl{sub 4}-doped NaAlH{sub 4} exhibit similar apparent activation energies estimated from Kissinger's method, suggesting the reactions are all determined by the same rate-limiting step. These results clearly demonstrate that the in situ formed CeAl{sub 4} acts as active species to catalyze the reversible dehydriding/rehydriding of NaAlH{sub 4}.

  13. 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...

  14. 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. PMID:24662462

  15. 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...

  16. 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.

  17. 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.

  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. Synthesis and characterization of BaCeO3 nanocrystals viasolvothermal-based method

    Institute of Scientific and Technical Information of China (English)

    XU Chao; ZHU Junwu; YANG Xujie; LU Lude; WANG Xin

    2008-01-01

    A facile approach to preparing well-dispersed nanocrystals of BaCeO3 was developed by a combination of solvothermal and annealing processes. The precursor consisted of amorphous BaCO3 and CeO2, and the conversion of the precursor to crystalline BaCeO3 nanocrystals occurred upon heat treatment at a relatively low temperature. The as-processed BaCeO3 had an orthorhombic structure and the average size of such crystals was approximately 80 nm. The obtained products were characterized by Fourier Transform Infrared (FT-IR), X-Ray Diffraction (XRD), Laser Raman Spectroscopy (LRS), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectrometry (EDS), and Transmission Electron Microscopy (TEM). This preparation process could also be used to synthesize doped barium cerate complex oxides BaCe0.95M0.05O3-d (M=Y, Nd, Gd, and Sm).

  20. 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.

  1. Radiative energy transfer in ZnAl{sub 2}O{sub 4}:0.1% Ce{sup 3+}, x% Eu{sup 3+} nanophosphor synthesized by sol–gel process

    Energy Technology Data Exchange (ETDEWEB)

    Motloung, S.V., E-mail: motloungsv@qwa.ufs.ac.za [Department of Physics, University of the Free State (Qwaqwa Campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Dejene, F.B. [Department of Physics, University of the Free State (Qwaqwa Campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Kroon, R.E.; Swart, H.C.; Ntwaeaborwa, O.M. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa)

    2015-07-15

    Zinc aluminate (ZnAl{sub 2}O{sub 4}) hosts and 0.1% Ce{sup 3+}, x% Eu{sup 3+} co-activated ZnAl{sub 2}O{sub 4} phosphor were successfully prepared at a relatively low temperature (~80 °C) using the sol–gel method. The co-activator (Eu{sup 3+}) concentration was varied in the range of 0≤x≤2 mol%, while the 0.1% Ce{sup 3+} was kept constant. The X-ray diffraction (XRD) data revealed that all annealed samples consisted of the pure cubic ZnAl{sub 2}O{sub 4} structure. The estimated crystallite size was in the range of 18–21 nm in diameter. The results showed that the full width at half maximum (FWHM) increased with the increase in Eu{sup 3+} mol%, which suggested a decrease in particle size. The nanopowder microstructure revealed that the material consisted of non-uniform sizes and the loss of lattice fringes as the Eu{sup 3+} concentration was increased suggested the increase in strain or disorder. The photoluminescence (PL) results showed that the host, activated and co-activated nanophosphor emitted at different wavelengths. The peak shifts suggested that the luminescence might originate either from the defects in the host, Ce{sup 3+} or Eu{sup 3+} ions. The incorporation of the co-activator (Eu{sup 3+}) at higher concentration resulted in radiative energy transfer from Ce{sup 3+}→Eu{sup 3+}. The CIE colour coordinates showed a shift from the blue to orange region as the Eu{sup 3+} concentration was increased.

  2. Identification of levels in neutron-rich 145Ce and 147Ce nuclei

    International Nuclear Information System (INIS)

    High-spin structures in the neutron-rich nuclei 145Ce and 147Ce produced in the spontaneous fission of 252Cf have been investigated by prompt γ-ray spectroscopy. A collective band structure in 145Ce is identified. Several sidebands along with the new high-spin states in 147Ce are also identified. Particle-plus-rotor model calculations indicate that the yrast bands in 145Ce and 147Ce most probably originate from coupling of the νi13/2 orbital to the ground states of 144Ce and 146Ce. The ground state configurations of 145,147Ce are (νh9/2+νf7/2) and νh9/2, respectively. (c) 1999 The American Physical Society

  3. 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.

  4. Energy levels of the Ce activator relative to the YAP(Ce) scintillator host

    International Nuclear Information System (INIS)

    The electronic structure of the cerium-activated yttrium aluminum perovskite [YAP(Ce)] scintillator has been studied by core level x-ray spectroscopy and first-principles calculations. X-ray absorption and emission spectra at the oxygen K-edge of YAP(Ce) and CeO2 have been measured and compared with the calculated partial density of states. With the known band gap of CeO2, the measured oxygen K-edge absorption and emission spectra are used to construct a fixed relation between the valence and conduction bands of YAP and CeO2. This allows us to determine the fundamental band gap of YAP to be 8.1 ± 0.3 eV. A comparison between the cerium M4,5-edges x-ray absorption spectra of the YAP(Ce) and Ce model compounds (CeO2, CeF3, and Ce foils) then shows that the Ce activator is in the desired Ce3+, with a small fraction of Ce4+ due to oxidization at the surface. Finally, we determine that the ground state 4f1 energy level of the Ce3+ activator lies 1.8 ± 0.5 eV above the top of the valence band of the host YAP. (paper)

  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. 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).

  7. Luminescence from Ce in sol-gel SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Kroon, R.E., E-mail: KroonRE@ufs.ac.za [Department of Physics, University of the Free State, IB51, Box 339, Bloemfontein 9300 (South Africa); Seed Ahmed, H.A.A.; Ntwaeaborwa, O.M. [Department of Physics, University of the Free State, IB51, Box 339, Bloemfontein 9300 (South Africa); Koao, L.F. [Department of Physics, University of the Free State (Qwaqwa Campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Nagpure, I.M.; Gusowski, M.A. [Department of Physics, University of the Free State, IB51, Box 339, Bloemfontein 9300 (South Africa); Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, Box 77000, Port Elizabeth 6031 (South Africa); Swart, H.C. [Department of Physics, University of the Free State, IB51, Box 339, Bloemfontein 9300 (South Africa)

    2012-05-15

    The sol-gel process provides an attractive low temperature alternative to the melt process for producing Ce-doped silica, but reports of the emission wavelength have not been consistent. In this paper, luminescence measurements using a variety of excitation methods, including cathodoluminescence not yet reported by other researchers, are compared and evaluated in the light of previously published data. Several papers report luminescence around 350 nm but emission near this wavelength was not found from our samples. This luminescence originates from Ce that has not yet been incorporated in the silica and is found in samples that have not undergone high temperature annealing. Our photoluminescence results from samples annealed in a reducing atmosphere suggest that emission from Ce incorporated in the silica lattice occurs near 455 nm, and some indication of the emission from Ce in amorphous clusters at 400 nm is also found. However, our results also confirm earlier indications that intrinsic defects in silica can create photoluminescence near both these wavelengths, which can make identification of the luminescence due to Ce difficult. Finally, it has been found that samples which have been annealed in air, and therefore display poor photoluminescence because most of the Ce occurs in the tetravalent form, are luminescent under electron beam excitation. It is suggested that during cathodoluminescence measurements Ce{sup 4+} ions capture electrons to form excited Ce{sup 3+} ions from which the luminescence originates.

  8. Transport properties of pure and doped CeO2

    International Nuclear Information System (INIS)

    The oxides that crystallize in the fluorite structure are noted for their ability to accommodate a high degree of disorder on the oxygen sublattice. Cerium oxide is a semiconductor and ionically- conductor oxide with important electrical and chemical applications as a solid oxide fuel cell electrolyte, a catalyst for gas phase oxidation and reduction reactions, and as an oxygen buffer in the automotive 3-way catalyst. Polycrystalline samples of different grain size were prepared by uniaxial hot pressing and their sintering behavior was investigated, at various temperatures and pressures. The cerium dioxide has been prepared by this way and characterized by X-ray diffraction and transmission electron microscopy (SEM). Measurements of electronic conductivity have confirmed that electron transport in CeO2-x proceeds via a small polaron process. The electrical properties of CeO2-UO2 solid solutions are examined as a function of temperature (600 deg. C - 1400 deg. C), oxygen partial pressure (10 - 22 - 1 atm), and Ce/U ratio (CeO2- 1.65% UO2, CeO2- 5% UO2). The PO2 values were controlled by mixing Ar-O2 and CO2-H2 or Ar-H2, gases in appropriate proportions. Electrical conductivity data obtained for U-doped CeO2 solid solution were shown to be in good agreement with predictions and thereby enable derivation of a number of key parameters, including those controlling generation of oxygen Frenkel defects, doubly ionized vacancies and electrons by reduction, and electron mobilities. (authors)

  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. PMID:27031297

  10. Isolation and functional characterization of CE1 binding proteins

    Directory of Open Access Journals (Sweden)

    Yu Ji-hyun

    2010-12-01

    Full Text Available Abstract Background Abscisic acid (ABA is a plant hormone that controls seed germination, protective responses to various abiotic stresses and seed maturation. The ABA-dependent processes entail changes in gene expression. Numerous genes are regulated by ABA, and promoter analyses of the genes revealed that cis-elements sharing the ACGTGGC consensus sequence are ubiquitous among ABA-regulated gene promoters. The importance of the core sequence, which is generally known as ABA response element (ABRE, has been demonstrated by various experiments, and its cognate transcription factors known as ABFs/AREBs have been identified. Although necessary, ABRE alone is not sufficient, and another cis-element known as "coupling element (CE" is required for full range ABA-regulation of gene expression. Several CEs are known. However, despite their importance, the cognate transcription factors mediating ABA response via CEs have not been reported to date. Here, we report the isolation of transcription factors that bind one of the coupling elements, CE1. Results To isolate CE1 binding proteins, we carried out yeast one-hybrid screens. Reporter genes containing a trimer of the CE1 element were prepared and introduced into a yeast strain. The yeast was transformed with library DNA that represents RNA isolated from ABA-treated Arabidopsis seedlings. From the screen of 3.6 million yeast transformants, we isolated 78 positive clones. Analysis of the clones revealed that a group of AP2/ERF domain proteins binds the CE1 element. We investigated their expression patterns and analyzed their overexpression lines to investigate the in vivo functions of the CE element binding factors (CEBFs. Here, we show that one of the CEBFs, AtERF13, confers ABA hypersensitivity in Arabidopsis, whereas two other CEBFs enhance sugar sensitivity. Conclusions Our results indicate that a group of AP2/ERF superfamily proteins interacts with CE1. Several CEBFs are known to mediate defense or

  11. 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.

  12. Photoelectron spectra of CeO{sup −} and Ce(OH){sub 2}{sup −}

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Manisha; Felton, Jeremy A.; Kafader, Jared O.; Topolski, Josey E.; Jarrold, Caroline Chick, E-mail: cjarrold@indiana.edu [Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405 (United States)

    2015-02-14

    The photoelectron spectrum of CeO{sup −} exhibits what appears to be a single predominant electronic transition over an energy range in which numerous close-lying electronic states of CeO neutral are well known. The photoelectron spectrum of Ce(OH){sub 2}{sup −}, a molecule in which the Ce atom shares the same formal oxidation state as the Ce atom in CeO{sup −}, also exhibits what appears to be a single transition. From the spectra, the adiabatic electron affinities of CeO and Ce(OH){sub 2} are determined to be 0.936 ± 0.007 eV and 0.69 ± 0.03 eV, respectively. From the electron affinity of CeO, the CeO{sup −} bond dissociation energy was determined to be 7.7 eV, 0.5 eV lower than the neutral bond dissociation energy. The ground state orbital occupancies of both CeO{sup −} and Ce(OH){sub 2}{sup −} are calculated to have 4f 6s{sup 2} Ce{sup +} superconfigurations, with open-shell states having 4f5d6s superconfiguration predicted to be over 1 eV higher in energy. Low-intensity transitions observed at higher electron binding energies in the spectrum of CeO{sup −} are tentatively assigned to the {sup 1}Σ{sup +} (Ω = 0) state of CeO with the Ce{sup +2}⍰6s{sup 2} superconfiguration.

  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. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Lifetimes of Excited Levels in 131Ce

    Institute of Scientific and Technical Information of China (English)

    LI Guang-Sheng; LI Xian-Feng; WEN Li-Jun; ZHENG Yong-Nan; ZHENG Yong; LIU Yun-Zuo; YUAN Guan-Jun; YANG Chun-Xiang; MENG Rui; ZHU Li-Hua; ZHANG Zhen-Long; WANG Yue; WANG Zhi-Min; WEN Shu-Xian; LU Jing-Bin; ZHAO Guang-Yi

    2004-01-01

    @@ The fusion-evaporation reaction 116Sn (1gF, p3n) 131 Ce at projectile energy of 95 MeV is used to populate high spin states in 131 Ce. The de-exciting γ-rays are detected in γ-γ coincidence measurement with Compton-suppressed BGO-HPGe detectors. Level lifetimes of 131 Ce were determined by using the Doppler shift attenuation method.The experimental results indicate that collectivity of 131 Ce is reduced relative to that of 130 Ce and it follows that deformation decreases with increase of the neutron number on the basis of systematic comparison of transition quadrupole moments for the light cerium isotopes.

  20. 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.

  1. 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.

  2. Temperature dependence of the scintillation properties of Ce:GSO and Ce:GSOZ

    Energy Technology Data Exchange (ETDEWEB)

    Kurosawa, Shunsuke, E-mail: kurosawa@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Sugiyama, Makoto [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yanagida, Takayuki [New Industry Creation Hatchery Center (NICHe), 6-6-10 Aoba Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Yokota, Yuui [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yoshikawa, Akira [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), 6-6-10 Aoba Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan)

    2012-10-21

    The light output and decay times of Ce:GSO and Ce:GSOZ scintillators depend on Ce concentration and temperature. We investigated the temperature dependence of the light output and the decay time for Ce:GSO and Ce:GSOZ doped with 0.3 (only GSO), 0.5, 1.0, and 1.5 mol% Ce. These samples were measured with a ruggedized photomultiplier (PMT) (Hamamatsu R6877A) at 175 Degree-Sign C (in the thermostat chamber). Up to 100 Degree-Sign C, the relative light output of all of the samples remained within 10% after correcting the PMT gain, which depends on the temperature. The decay times of the GSO and GSOZ samples with the identical Ce concentrations were equal. Moreover, the quenching energy values for all the samples were equivalent.

  3. 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.

  4. Study on co-precipitation synthesized Y_3Al_5O_(12):Ce yellow phosphor for white LED

    Institute of Scientific and Technical Information of China (English)

    张书生; 庄卫东; 何涛; 刘元红; 刘荣辉; 高文贵; 胡运生; 龙震

    2010-01-01

    A precursor of the Y3Al5O12:Ce (YAG:Ce) phosphor was obtained by co-precipitation of the solution of high purity nitrates with ammonium bicarbonate solution. The precipitation process of the precursor was studied in this work. YAG:Ce yellow phosphors with fine morphology was synthesized by annealing the precursor at a reducing atmosphere. The crystal phase, microstructure of the phosphors and their photoluminescence were investigated. The results indicated that the pure phase of YAG:Ce could be obtained at ...

  5. 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.

  6. 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.

  7. 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

    fullerene 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.

  8. 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.

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

    International Nuclear Information System (INIS)

    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

  10. 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.

  11. 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.

  12. 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.

  13. Structural and magnetic properties of Ce/Fe and Ce/FeCoV multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Tixier, S.; Boeni, P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Mannix, D.; Stirling, W.G. [Liverpool Univ. (United Kingdom); Lander, G.H.

    1997-09-01

    Ce/Fe and Ce/FeCoV multilayers have been grown by magnetron sputtering. The interfaces are well defined and the layers are crystalline down to an individual layer thickness of 20 A. Ce/FeCoV multilayers show sharper interfaces than Ce/Fe but some loss of crystallinity is observed. Hysteresis loops obtained by SQUID show different behaviour of the bulk magnetisation as a function of the layer thickness. Fe moments are found by Moessbauer spectroscopy to be perpendicular to the interfaces for multilayers with small periodicity. (author) 2 figs., 2 refs.

  14. 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.

  15. 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%.

  16. 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.

  17. 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.

  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. PMID:27474815

  19. Superconductivity in an intermediate valence Ce compound with a quasi-two-dimensional structure

    Energy Technology Data Exchange (ETDEWEB)

    Gruner, Thomas; Geibel, Christoph [MPI for Chemical Physics of Solids, 01187, Dresden (Germany); Anupam, M.; Hossain, Zakir [Department of Physics, IIT Kanpur, 208016, Kanpur (India)

    2012-07-01

    Binary rare earth - transition metal metallographic phase diagrams show a large immiscibility gap for early transition metals (i.e. from the left side of the periodic table). As a result, no binary compound forms and only very few ternary compounds have been reported. Among them CeRe{sub 4}Si{sub 2} presents an interesting structure: a stacking of Re{sub 2}Si and Ce layers results in a quasi-two-dimensional character. The preparation of this compound is challenging because of the high melting point of Re (3180 C) and the fact that CeRe{sub 4}Si{sub 2} likely forms in a solid-state reaction. We developed an appropriate synthesis process and obtained almost phase pure polycrystalline samples. Results of electrical resistivity, magnetic susceptibility and specific heat measurements show that Ce is in an intermediate valence state and that the compound becomes superconducting below T{sub c} {approx} 3.2 K. CeRe{sub 4}Si{sub 2} is thus one of the very few intermediate valence Ce-based superconductors. The properties of this superconducting state will be discussed.

  20. Microstructures, mechanical properties and corrosion resistances of extruded Mg-Zn-Ca-xCe/La alloys.

    Science.gov (United States)

    Tong, L B; Zhang, Q X; Jiang, Z H; Zhang, J B; Meng, J; Cheng, L R; Zhang, H J

    2016-09-01

    Magnesium alloys are considered as good candidates for biomedical applications, the influence of Ce/La microalloying on the microstructure, mechanical property and corrosion performance of extruded Mg-5.3Zn-0.6Ca (wt%) alloy has been investigated in the current study. After Ce/La addition, the conventional Ca2Mg6Zn3 phases are gradually replaced by new Mg-Zn-Ce/La-(Ca) phases (T1'), which can effectively divide the Ca2Mg6Zn3 phase. The Ca2Mg6Zn3/T1' structure in Mg-Zn-Ca-0.5Ce/La alloy is favorably broken into small particles during the extrusion, resulting in an obvious refinement of secondary phase. The dynamic recrystallized grain size is dramatically decreased after 0.5Ce/La addition, and the tensile yield strength is improved, while further addition reverses the effect, due to the grain coarsening. However, the corrosion resistance of extruded Mg-Zn-Ca alloy deteriorates after Ce/La addition, because the diameter of secondary phase particle is remarkably decreased, which increases the amount of cathodic sites and accelerates the galvanic corrosion process. PMID:27179307

  1. Effect of annealing temperature on oxygen vacancy concentrations of nanocrystalline CeO2 film

    International Nuclear Information System (INIS)

    Highlights: • Nanocrystalline CeO2 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 CeO2 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 CeO2 films. The average grain-size and surface roughness of the films increase with the increase of annealing temperature. The content of Ce3+ and oxygen vacancy is very high in the nanocrystalline CeO2 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 Ce4+ to Ce3+, 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 CeO2 film, and it also provides a possible way to control the concentration of oxygen vacancies

  2. 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.

  3. 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.

  4. Building novel Ag/CeO2 heterostructure for enhancing photocatalytic activity

    International Nuclear Information System (INIS)

    Highlights: • Ag nanoparticle is designed to building Schottky heterojunction on CeO2 nanocube. • The photocatalytic activity of Ag/CeO2 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/CeO2 heterostructure is designed as a photocatalyst to degrade organic dye under the simulated sunlight. The catalytic activity of CeO2 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 CeO2 in forming high efficiency catalyst, the amount of Ag/CeO2 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/CeO2 catalyst in an optimal weight ratio of 1:3, is added to the 100 mL of MB solution (c0 = 1 × 10−5 mol L−1, pH 6.2). The mechanism of the enhanced catalytic activity of Ag/CeO2 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

  5. 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.

  6. Influence of preparation conditions on 211 particle refinement in YBCO bulk superconductors with Ce addition

    Energy Technology Data Exchange (ETDEWEB)

    Diko, Pavel, E-mail: dikos@saske.sk; Volochová, Daniela; Radušovská, Monika; Zmorayová, Katarína; Šefčiková, Martina; Antal, Vitalij; Jurek, Karel; Jirsa, Miloš; Kováč, Jozef

    2013-11-15

    Highlights: •CeO{sub 2} causes coarsening of Y211 particles in nominal composition Y{sub 1.5}Ba{sub 2}Cu{sub 3}O{sub x}. •Y211 particles grow during sintering at 940 °C. •High local density of Y211 particles hinders their growth at sintering stage. •Addition of BaCeO{sub 3} leads to smaller Y211 particles. •Skeleton of Y211 particles prevents pollution of grown samples. -- Abstract: The influence of CeO{sub 2} and BaCeO{sub 3} addition and the influence of processing conditions on Y{sub 2}BaCuO{sub 5} (Y211) particle size and particle distribution in melt-processed YBa{sub 2}Cu{sub 3}O{sub 7}/Y{sub 2}BaCuO{sub 5} (Y123/Y211) bulk superconductors with nominal composition Y{sub 1.5}Ba{sub 2}Cu{sub 3}O{sub x} was investigated. Ce dissolved in the peritectic melt can actively hinder the Y211 particle growth by the Ostwald ripening process at melting stage. At sintering of intensively milled samples, Y211 particles in the charge free of CeO{sub 2} are smaller than Y211 particles formed in the charge with CeO{sub 2} addition and this behaviour can be related to the melt formation around added CeO{sub 2}. The Y211 particle refinement in the mildly milled samples with large Y123 particles in the pressed green bodies is caused by very dense Y211 skeleton resistant to melt formation at the sintering stage. This skeleton is a barrier for pollution of the sample from the substrate and from the seed. BaCeO{sub 3} added instead CeO{sub 2} causes significant Y211 particle refinement also in the samples with homogenously distributed Y211 particles.

  7. 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.

  8. Graphite oxide-mediated synthesis of porous CeO2 quadrangular prisms and their high-efficiency adsorptive performance

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Porous CeO2 quadrangular prisms have been prepared via graphite oxide-mediated synthesis. • Dual-pore hierarchical systems are formed with the pore distributions around 4 nm and 30 nm. • Porous CeO2 exhibits a rapid adsorption to Rhodamine B with a removal efficiency of ∼99%. • Porous CeO2 retains the same performances in different pH solutions. - Abstract: We report a graphite oxide-mediated approach for synthesizing porous CeO2 through a facile hydrothermal process followed by thermal annealing in air. The phase structure, morphology, microstructure and porosity of the products have been revealed by a combination of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and N2 adsorption. The as-prepared CeO2 products show well-defined quadrangular prism morphology, and they are composed of interconnected nanoparticles with diameters around 30–100 nm. In particular, the dual-pore hierarchical systems are created in the CeO2 quadrangular prisms with the pore distributions around 4 nm and 30 nm. The dye sorption capacity of the porous CeO2 is investigated, which exhibits a rapid adsorption to rhodamine B with a high removal efficiency of ∼99%. Moreover, the CeO2 absorbent retains the same performances in different pH solutions

  9. Polishing behavior of PS/CeO2 hybrid microspheres with controlled shell thickness on silicon dioxide CMP

    International Nuclear Information System (INIS)

    Organic-inorganic composite microspheres with PS as a core and CeO2 nanoparticles as a shell were synthesized by in situ decomposition reaction of Ce(NO3)3 on the surfaces of PS microspheres prepared through soap-free emulsion polymerization. The shell thickness of the composite microspheres could be turned by varying the concentration of Ce(NO3)3 in the reaction solution. The whole process required neither surface treatment for PS microspheres nor additional surfactant or stabilizer. The as-synthesized PS/CeO2 composite microsphere samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Oxide chemical mechanical polishing (CMP) performance of the PS/CeO2 composite abrasives with different shell thickness was characterized by atomic force microscopy (AFM). The results indicated that the as-prepared core-shell structured composite microspheres (220-260 nm in diameter) possessed thin shell (10-30 nm) composed of CeO2 nanoparticles (particle diameter of 5-10 nm), and the final CeO2 contents of the composite microspheres ranged from 10 to 50 wt%. A possible mechanism for the formation of PS/CeO2 composite microspheres was discussed also. The CMP test results confirmed that the novel core-shell structured composite abrasives are useful to improve oxide CMP performance. In addition, there is an obvious effect of shell thickness of the composite abrasives on oxide CMP performance.

  10. Superconductivity in CeCo2 nanoparticles

    International Nuclear Information System (INIS)

    Both Ce and Co are essentially nonmagnetic in Pauli-paramagnetic CeCo2, which undergoes a superconducting transition near 1K. When made into 58-A nanoparticles, the compound becomes paramagnetic. Meanwhile, based on heat capacity measurements, the nanoparticles remain to be nonsuperconducting down to 0.4K but exhibit a low-temperature Kondo anomaly with C/T∼ 350mJ/molK2 at 0.4K. Such intriguing effects are consequences of the competition between superconducting gap and electronic spectrum's mean level spacing

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Experimental study on Hg0 removal from flue gas over columnar MnOx-CeO2/activated coke

    International Nuclear Information System (INIS)

    Highlights: • The Hg0 removal efficiency over columnar MnCe6/activated coke up to 94%. • MnOx and CeO2 exhibited a significant synergistic role in Hg0 removal over MnCe/AC. • Lattice oxygen, chemisorbed oxygen and OH groups on the surface of MnCe/AC contributed to Hg0 oxidation. • Hg0 removal mechanisms over MnCe/AC were identified firstly. - Abstract: Mn-Ce mixed oxides supported on commercial columnar activated coke (MnCe/AC) were employed to remove elemental mercury (Hg0) at low temperatures (100–250 °C) without the assistance of HCl in flue gas. The samples were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Effects of some factors, including Mn-Ce loading values, active component, reaction temperatures and flue gas components (O2, SO2, NO, H2O), on Hg0 removal efficiency were investigated. Results indicated that the optimal Mn-Ce loading value and reaction temperature were 6% and 190 °C, respectively. Considerable high Hg0 removal efficiency (>90%) can be obtained over MnCe6/AC under both N2/O2 atmosphere and simulated flue gas atmosphere at 190 °C. Besides, it was observed that O2 and NO exerted a promotional effect on Hg0 removal, H2O exhibited a suppressive effect, and SO2 hindered Hg0 removal seriously when in the absence of O2. Furthermore, the XPS spectra of Hg 4f and Hg-TPD results showed that the captured mercury were existed as Hg0 and HgO on the MnCe6/AC, and HgO was the major species, which illustrated that adsorption and catalytic oxidation process were included for Hg0 removal over MnCe6/AC, and catalytic oxidation played the critical role. What's more, both lattice oxygen and chemisorbed oxygen or OH groups on MnCe6/AC contributed to Hg0 oxidation. MnCe6/AC, which exhibited excellent performance on Hg0 removal in the absence of HCl, appeared to be promising in industrial application, especially for low-rank coal fired

  16. 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...

  17. Proton induced activation of LaBr3:Ce and LaCl3:Ce

    International Nuclear Information System (INIS)

    In the framework of an assessment of lanthanum halide scintillators, such as LaBr3:Ce and LaCl3:Ce on their suitability for space based gamma-ray spectroscopy, proton induced activation of the materials has been studied. One inch scintillators were subjected to proton irradiations in the range of 60-184 MeV, where after the activation was measured. The activation was analyzed by identifying the decaying isotopes by means of gamma-ray spectroscopy and lifetime measurements using both a germanium detector and the activated scintillator itself. It was found that the dominant source of activation in the scintillators originates from the lighter elements in the materials: bromide and chloride, respectively. The activation of LaBr3:Ce manifest itself through gamma-decay, which partly leaves the volume. Activation of LaCl3:Ce originates mainly from beta decay, which is confined to the volume itself

  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. 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. PMID:26072989

  20. 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

  1. The microstructure evolution of an Al-Mg-Si-Mn-Cu-Ce alloy during homogenization

    International Nuclear Information System (INIS)

    The microstructure evolution in an Al-Mg-Si-Mn-Cu-Ce alloy during homogenization was investigated by optical microscopy, scanning electron microscopy and energy dispersive spectroscopy techniques in this paper. The purpose is to study the transformation of coarse intermetallic phases and the precipitation process of dispersoids. The results show that the phase constituents in the as-cast microstructure are Al(MnFe)3Si2, AlCuMgSi, AlCuSiCe, and ternary eutectic α-Al + AlCuMgSi +Si. After homogenization (3 h at 470 deg. C), the low melting point phase (AlCuMgSi) and ternary eutectic phase (α-Al + AlCuMgSi + Si) were almost completely dissolved. The obvious dissolution of the Al(MnFe)3Si2 phase started at 570 deg. C. Long-time heat treatment impels Mn to substitute for Fe in this phase. Because of the low solid solubility of Ce in Al-matrix, enrichment of the Ce was observed in the resulting AlCuSiCe particles after homogenization. Otherwise many dispersoid particles containing Mn precipitated during homogenization. The uniformity of dispersoid distribution is mostly dependent on the diffusion rate of Si through Al-matrix. A lot of Q phases were also discovered in this alloy after furnace cooling due to the effect of Cu on the precipitation process.

  2. Nd1.8Ce0.2CuO4+δ:Ce0.9Gd0.1O2-δ as a composite cathode for intermediate-temperature solid oxide fuel cells

    Science.gov (United States)

    Khandale, A. P.; Bhoga, S. S.

    2014-12-01

    The (100 - x)Nd1.8Ce0.2CuO4+δ:(x)Ce0.9Gd0.1O2-δ (x = 00, 10, 20 and 30 vol.%) composite systems are obtained by impregnating a stoichiometric solution of cerium and gadolinium nitrates followed by sintering at 900 °C for 4 h. Impregnating the Ce0.9Gd0.1O2-δ not only inhibits the growth of the host Nd1.8Ce0.2CuO4+δ grains during sintering but also enlarges the oxygen reduction reaction zone by introducing a nanosized phase that is ionically conductive, which significantly decreases the electrode polarization resistance of the composite cathode. A minimum polarization resistance value of 0.23 ± 0.02 Ω cm2 is obtained at 700 °C for a (80)Nd1.8Ce0.2CuO4+δ:(20)Ce0.9Gd0.1O2-δ composite cathode, and this value is attributed to the optimal dispersion into the porous Nd1.8Ce0.2CuO4+δ matrix. The impedance spectra are modeled using an electrical equivalent model that consists of a mid-frequency ZR1 -CPE circuit (parallel combination of R1 and constant phase element (CPE)) and a low-frequency Gerischer impedance. The Gerischer impedance decreases significantly when Ce0.9Gd0.1O2-δ infiltrates the Nd1.8Ce0.2CuO4+δ matrix. The oxygen partial pressure-dependent polarization study suggests a medium-frequency response, which is due to charge transfer step; however, the low-frequency response corresponds to the non-charge transfer oxygen adsorption-desorption and the diffusion process during the overall oxygen reduction reaction process.

  3. 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] ...

  4. The development of Ce3+-activated (Gd,Lu3Al5O12 garnet solid solutions as efficient yellow-emitting phosphors

    Directory of Open Access Journals (Sweden)

    Jinkai Li, Ji-Guang Li, Shaohong Liu, Xiaodong Li, Xudong Sun and Yoshio Sakka

    2013-01-01

    Full Text Available Ce3+-activated Gd3Al5O12 garnet, effectively stabilized by Lu3+ doping, has been developed for new yellow-emitting phosphors. The powder processing of [(Gd1−xLux1−yCey]3Al5O12 solid solutions was achieved through precursor synthesis via carbonate precipitation, followed by annealing. The resultant (Gd,LuAG:Ce3+ phosphor particles exhibit typical yellow emission at ~570 nm (5d–4f transition of Ce3+ upon blue-light excitation at ~457 nm (the 2F5/2–5d transition of Ce3+. The quenching concentration of Ce3+ was determined to be ~1.0 at% (y = 0.01 and the quenching mechanism was suggested to be driven by exchange interactions. The best luminescent [(Gd0.9Lu0.10.99Ce0.01]AG phosphor is comparative to the well-known YAG:Ce3+ in emission intensity but has a substantially red-shifted emission band that is desired for warm-white lighting. The effects of processing temperature (1000–1500 °C on the spectroscopic properties of the phosphors, especially those of Lu3+/Ce3+, were thoroughly investigated and discussed from the centroid position and crystal field splitting of the Ce3+ 5d energy levels.

  5. Development and construction of a fast spectroelectrochemical device. Applications to the reaction kinetic study of the Eu(III/II), Ce(IV/III) and U(VI/V) redox processes

    International Nuclear Information System (INIS)

    The reaction kinetics of redox processes for the f transition elements is investigated. An experimental device consisting in a spectrophotometer and an electrochemical system is developed. The time needed for the optical spectra acquisition is 512 microseconds per spectrum. The experiments on europium allowed testing the electrochemical behavior of both the cell and the electrode. From the experiments performed with cerium, the equilibrium potential and the heterogeneous standard velocity constant are obtained. A reaction mechanism is proposed. The reduction of uranium in acid media is analyzed

  6. Effect of La,Ce,Tb Concentration on Luminescence Properties of (La,Ce,Tb)BO3%La,Ce,Tb含量对(La,Ce,Tb)BO3发光性能的影响

    Institute of Scientific and Technical Information of China (English)

    王林生; 黄可龙; 周智; 文小强; 周健; 赖华生

    2012-01-01

    采用高温固相法合成(La,Ce,Tb)BO3荧光粉,并对该荧光粉进行XRD和SEM分析.结果表明:(La,Ce,Tb)BO3的晶体结构和LaBO3相同,Ce3+,Tb3+的掺入没有改变晶体的结构,发光粉颗粒大小均匀,形貌规则,粒度在5 μm左右.研究了(La,Ce,Tb)BO3的光谱性质,在(La,Ce,Tb)BO3的发射和激发光谱中除了有Tb3+的特征发射和激发峰外,还有Ce3+的特征发射和激发峰.%The phosphors of (La,Ce,Tb)BO3 were synthesized by high temperature solid state reaction. X-ray diffractometry (XRD) patterns indicate that the crystal structures of (La,Ce,Tb)BO3 and LaBO3 are the same. The crystal structure has not been changed by Ce3+ and Tb3+ doping. Emission scanning electron microscopy (SEM) images show that the particle sizes of phosphors are more uniform, the morphology is more regular, and the granularity is about 5 μm. The content of TbBO3 phase in (La,Ce,Tb)BO3 increases with increasing of Tb content in (La,Ce,Tb)BO3. When Tb concentration reaches 15% and above, the content of TbBO3 phase in (La,Ce,Tb)BO3 increases more rapidly. The luminescence properties of (La,Ce,Tb)BO3 and the sensitization of Ce to Tb were studied. In the excitation spectrum of Ce there are three peaks at 244, 268 and 330 nm, respectively. And in the emission spectrum of Ce , there are two peaks at 365 and 380 nm, respectively. All of them have the large overlap. The Maximum emission wavelength of Tb3+ is 541 nm, and its excitation peaks is 230 nm. Both the Tb characteristic emission and excitation peaks and the Ce characteristic emission and excitation peaks were observed in the emission and excitation spectrum of (La,Ce,Tb)BO3. Comparing the excitation spectrum of (La,Ce)BO3 with the emission spectrum of (La,Tb)BO3, it is found that they have the large overlap. It is indicated that there is a remarkable energy transfer from Ce to Tb in (La,Ce,Tb)BO3. When the concentration of Ce or Tb in (La,Ce,Tb)BO3 is fixed, because of concentration self

  7. Preparation of ZnO:CeO2-x thin films by AP-MOCVD: Structural and optical properties

    International Nuclear Information System (INIS)

    The growth of columnar CeO2, ZnO and ZnO:CeO2-x films on quartz and AA6066 aluminum alloy substrates by economic atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD) is reported. A novel and efficient combination of metal acetylacetonate precursors as well as mild operating conditions were used in the deposition process. The correlation among crystallinity, surface morphology and optical properties of the as-prepared films was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and UV-vis spectroscopy. The synthesized films showed different crystallographic orientations depending on the ZnO and CeO2 lattice mismatch, cerium content and growth rate. The CeO2 films synthesized in this work showed plate-like compact structures as a result of the growth process typical of CVD. Both pure and ZnO:CeO2-x films were obtained with a hexagonal structure and highly preferred orientation with the c-axis perpendicular to both substrates under the optimal deposition conditions. The microstructure was modified from dense, short round columns to round structures with cavities ('rose-flower-like' structures) and the typical ZnO morphology by controlling the cerium doping the film and substrate nature. High optical transmittance (>87%) was observed in the pure ZnO films. As for the ZnO:CeO2-x films, the optical transmission was decreased and the UV absorption increased, which subsequently was affected by an increase in cerium content. This paper assesses the feasibility of using ZnO:CeO2-x thin films as UV-absorbers in industrial applications. - Graphical abstract: TEM micrographs and their corresponding SAED pattern obtained for the as-deposited ZnO-CeO2-x thin films for a Zn/Ce metallic ratio 16:9.

  8. Effect of 10Ce-TZP/Al2O3 nanocomposite particle amount and sintering temperature on the microstructure and mechanical properties of Al/(10Ce-TZP/Al2O3) nanocomposites

    International Nuclear Information System (INIS)

    Highlights: • Increasing the 10Ce-TZP/Al2O3 content up to 7 wt.%, enhanced composites’ hardness. • Significant enhancement in compressive strength is obtained with 7% 10Ce-TZP/Al2O3. • Sintering at 450 °C, hardness and compressive strength are higher than at 400 °C. - Abstract: A zirconia/alumina nanocomposite stabilized with cerium oxide (Ce-TZP/Al2O3 nanocomposite) can be a good substitute as reinforcement in metal matrix composites. In the present study, the effect of the amount of 10Ce-TZP/Al2O3 particles on the microstructure and properties of Al/(10Ce-TZP/Al2O3) nanocomposites was investigated. For this purpose, aluminum powders with average size of 30 μm were ball-milled with 10Ce-TZP/Al2O3 nanocomposite powders (synthesized by aqueous combustion) in varying amounts of 1, 3, 5, 7, and 10 wt.%. Cylindrical-shape samples were prepared by pressing the powders at 600 MPa for 60 min while heating at 400–450 °C. The specimens were then characterized by scanning and transmission electron microscopy (SEM and TEM) in addition to different physical and mechanical testing methods in order to establish the optimal processing conditions. The highest compression strength was obtained in the composite with 7 wt.% (10Ce-TZP/Al2O3) sintered at 450 °C

  9. Temperature dependent spectroscopic studies of the electron delocalization dynamics of excited Ce ions in the wide band gap insulator, Lu2SiO5

    NARCIS (Netherlands)

    Van der Kolk, E.; Basun, S.A.; Imbusch, G.F.; Yen, W.M.

    2003-01-01

    Electron delocalization processes of optically excited states of Ce3+ impurities in Lu2SiO5 were investigated by means of a temperature and spectrally resolved photoconductivity study. By monitoring separately the strength of the photocurrent resulting from excitation into each of the Ce3+ 5d absorp

  10. 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.

  11. Convenient synthesis of CeO2 nanotubes

    International Nuclear Information System (INIS)

    A simple and facile route was used in the fabrication of CeO2 nanotubes within anodic alumina membrane. A piece of membrane was first immersed into Ce(NO3)3 aqueous solution under ambient conditions. After dried at 50 deg. C and thermally calcined at 150 deg. C and 550 deg. C, CeO2 nanotubes can be easily synthesized. The characterization with electron microscopy and X-ray diffraction indicated that CeO2 nanotubes were composed of tiny well-crystalline CeO2 nanoparticles

  12. 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.

  13. Maanhonka hirsitalot CE-merkintä

    OpenAIRE

    Nieminen, Ville

    2012-01-01

    Tämän insinöörityön tarkoitus oli saada päivitettyä Maanhonka hirsitalojen ETA, joka oli mennyt vanhaksi marraskuussa 2010. ETA-hyväksynnän ja vaatimuksen-mukaisuustodistuksen myötä on tarkoitus hakea yritykselle CE-merkintäoikeus. CE-merkintä tulee pakolliseksi talotehtaille ja kaikille rakennustuotteille 1.7.2013 alkaen. Prosessi kestää yrityksestä riippuen vähintään puolesta vuodesta vuoteen. Riippuen siitä, mitä ETAan sisällytetään ja mitä testejä yrityksellä on jo ennestään tehtynä. VTT:...

  14. 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].

  15. 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.

  16. 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.

  17. Effect of rare earth Ce on the far infrared radiation property of iron ore tailings ceramics

    International Nuclear Information System (INIS)

    Highlights: • Detailed process proposed for preparation of iron ore tailings ceramics. • Replace natural minerals with iron ore tailings as raw materials for preparing functional ceramics. • Impact mechanism of Ce on far infrared ceramics, as well as its optimum addition amounts can be obtained. • Propose a new perspective on considering the mechanism of far infrared radiation. - Abstract: A kind of far infrared radiation ceramics was prepared by using iron ore tailings, CaCO3 and SiO2 as main raw materials, and Ce as additive. The result of Fourier transform infrared spectroscopy showed that the sample exhibits excellent radiation value of 0.914 when doping 7 wt.% Ce. Ce4+ dissolved into iron diopside and formed interstitial solid solution with it sintered at 1150 °C. The oxidation of Fe2+ to Fe3+ caused by Ce4+ led to a decrease of crystallite sizes and enhancement of Mg–O and Fe–O vibration in iron diopside, which consequently improved the far infrared radiation properties of iron ore tailings ceramics

  18. Effect of rare earth Ce on the far infrared radiation property of iron ore tailings ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jie [Key Laboratory of Special Functional Materials for Ecological Environment and Information (Hebei University of Technology), Ministry of Education, Tianjin 300130 (China); Institute of Power Source and Ecomaterials Science, Hebei University of Technology, Tianjin 300130 (China); Meng, Junping, E-mail: srlj158@sina.com [Key Laboratory of Special Functional Materials for Ecological Environment and Information (Hebei University of Technology), Ministry of Education, Tianjin 300130 (China); Institute of Power Source and Ecomaterials Science, Hebei University of Technology, Tianjin 300130 (China); Liang, Jinsheng; Duan, Xinhui [Key Laboratory of Special Functional Materials for Ecological Environment and Information (Hebei University of Technology), Ministry of Education, Tianjin 300130 (China); Institute of Power Source and Ecomaterials Science, Hebei University of Technology, Tianjin 300130 (China); Huo, Xiaoli [Institute of Power Source and Ecomaterials Science, Hebei University of Technology, Tianjin 300130 (China); Tang, Qingguo [Key Laboratory of Special Functional Materials for Ecological Environment and Information (Hebei University of Technology), Ministry of Education, Tianjin 300130 (China); Institute of Power Source and Ecomaterials Science, Hebei University of Technology, Tianjin 300130 (China)

    2015-06-15

    Highlights: • Detailed process proposed for preparation of iron ore tailings ceramics. • Replace natural minerals with iron ore tailings as raw materials for preparing functional ceramics. • Impact mechanism of Ce on far infrared ceramics, as well as its optimum addition amounts can be obtained. • Propose a new perspective on considering the mechanism of far infrared radiation. - Abstract: A kind of far infrared radiation ceramics was prepared by using iron ore tailings, CaCO{sub 3} and SiO{sub 2} as main raw materials, and Ce as additive. The result of Fourier transform infrared spectroscopy showed that the sample exhibits excellent radiation value of 0.914 when doping 7 wt.% Ce. Ce{sup 4+} dissolved into iron diopside and formed interstitial solid solution with it sintered at 1150 °C. The oxidation of Fe{sup 2+} to Fe{sup 3+} caused by Ce{sup 4+} led to a decrease of crystallite sizes and enhancement of Mg–O and Fe–O vibration in iron diopside, which consequently improved the far infrared radiation properties of iron ore tailings ceramics.

  19. Comparison of Ce$^{3+}$ and Pr$^{3+}$ activators in alkaline-earth fluoride crystals

    OpenAIRE

    Radzhabov, E.; Nepomnyaschikh, A.

    2012-01-01

    The emission spectra of Ce$^{3+}$ or Pr$^{3+}$ doped CaF$_2$, SrF$_2$, BaF$_2$ excited by vacuum ultraviolet photons or by x-ray as well as excitation and absorption spectra in vacuum ultraviolet region (6-13 eV) were studied. The transfer of exciton energy is the main channel for Ce$^{3+}$ excitation in alkaline-earth fluorides. Three different stages of energy transfer were observed. Pr$^{3+}$ excited by two processes, slow f-f luminescence excited by excitons, fast d-f luminescence excited...

  20. Mesoporous Silica Coated CeF3:Tb3+ Particles for Drug Release

    OpenAIRE

    Deyan Kong; Piaoping Yang; Zhenling Wang; Ping Chai; Shanshan Huang; Hongzhou Lian; Jun Lin

    2008-01-01

    CeF3:Tb3+ nanoparticles were successfully prepared by a polyol process using diethylene glycol (DEG) as solvent. After being coated with dense silica, these CeF3:Tb3+ nanoparticles can be coated with mesoporous silica using nonionic triblock copolymer EO20PO70EO20 (P 123) as structure-directing agent. The composite can load ibuprofen and release the drug in the PBS. The composite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen absorption/desorpti...

  1. 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.

  2. The 144Ce source for SOX

    Science.gov (United States)

    Durero, M.; Vivier, M.; Agostini, M.; Altenmüller, K.; Appel, S.; Bellini, G.; Benziger, J.; Berton, N.; Bick, D.; Bonfini, G.; Bravo, D.; Caccianiga, B.; Calaprice, F.; Caminata, A.; Cavalcante, P.; Chepurnov, A.; Choi, K.; Cribier, M.; D'Angelo, D.; Davini, S.; Derbin, A.; Di Noto, L.; Drachnev, I.; Etenko, A.; Farinon, S.; Fischer, V.; Fomenko, K.; Franco, D.; Gabriele, F.; Gaffiot, J.; Galbiati, C.; Ghiano, C.; Giammarchi, M.; Goeger-Neff, M.; Goretti, A.; Gromov, M.; Hagner, C.; Houdy, T.; Hungerford, E.; Ianni, Aldo; Ianni, Andrea; Jonqueres, N.; Jedrzejczak, K.; Kaiser, M.; Kobychev, V.; Korablev, D.; Korga, G.; Kornoukhov; Kryn, D.; Lachenmaier, T.; Lasserre, T.; Laubenstein, M.; Lehnert, B.; Link, J.; Litvinovich, E.; Lombardi, F.; Lombardi, P.; Ludhova, L.; Lukyanchenko, G.; Machulin, I.; Manecki, S.; Maneschg, W.; Marcocci, S.; Maricic, J.; Mention, G.; Meroni, E.; Meyer, M.; Miramonti, L.; Misiaszek, M.; Montuschi, M.; Muratova, V.; Musenich, R.; Neumair, B.; Oberauer, L.; Obolensky, M.; Ortica, F.; Pallavicini, M.; Papp, L.; Perasso, L.; Pocar, A.; Ranucci, G.; Razeto, A.; Re, A.; Romani, A.; Roncin, R.; Rossi, N.; Schönert, S.; Scola, L.; Semenov, D.; Simgen, H.; Skorokhvatov, M.; Smirnov, O.; Sotnikov, A.; Sukhotin, S.; Suvorov; Tartaglia, R.; Testera, G.; Thurn, J.; Toropova, M.; Veyssiére, C.; Unzhakov, E.; Vogelaar, R. B.; von Feilitzsch, F.; Wang, H.; Weinz, S.; Winter, J.; Wojcik, M.; Wurm, M.; Yokley, Z.; Zaimidoroga, O.; Zavatarelli, S.; Zuber, K.; Zuzel, G.

    2016-02-01

    The SOX (Short distance neutrino Oscillations with BoreXino) project aims at testing the light sterile neutrino hypothesis. To do so, two artificials sources of antineutrinos and neutrinos respectively will be consecutively deployed at the Laboratori Nazionali del Gran Sasso (LNGS) in close vicinity to Borexino, a large liquid scintillator detector. This document reports on the source production and transportation. The source should exhibit a long lifetime and a high decay energy, a requirement fullfilled by the 144Ce-144Pr pair at secular equilibrium. It will be produced at FSUE “Mayak” PA using spent nuclear fuel. It will then be shielded and packed according to international regulation and shipped to LNGS across Europe. Knowledge of the Cerium antineutrino generator (CeANG) parameters is crucial for SOX as it can strongly impact the experiment sensitivity. Several apparatuses are being used or designed to characterize CeANG activity, radioactive emission and content. An overview of the measurements performed so far is presented here.

  3. [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. PMID

  4. [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.

  5. Moessbauer studies of nano phase Ce-Fe oxide composites

    International Nuclear Information System (INIS)

    Chemical co-precipitation method was used to synthesize nano-structured α-Fe2O3-CeO2 composite by calcination of the goethite-cerium hydroxide precursor. It was observed that the precursor contained goethite matrix doped with cerium. Calcination of the precursor at 400oC showed the formation of nanosize hematite. Moessbauer spectra show the presence of a paramagnetic component in the precursor but not in the samples calcined at 400oC to 800oC temperatures. Our study shows that Ce precipitated as CeO2 and stuck on the surface of hematite particles. The precipitation of Ce as CeO2 is independent of the concentration of Ce in the Ce-Fe-O composite.

  6. Resistive switching behaviour of highly epitaxial CeO2 thin film for memory application

    International Nuclear Information System (INIS)

    We report on the remarkable potential of highly epitaxial and pure (001)-oriented CeO2 thin films grown on conducting Nb-doped SrTiO3 (NSTO) substrates by laser molecular beam epitaxy for nonvolatile memory application. Resistive switching (RS) devices with the structure of Au/epi-CeO2/NSTO exhibit reversible and steady bipolar RS behaviour with large high/low resistance ratio and a narrow dispersion of the resistance values. Detailed analysis of the conduction mechanisms reveals that the trapping/detrapping processes and oxygen vacancies migration play important roles in the switching behaviour. In the light of XPS measurement results, the CeO2/NSTO interface with oxygen vacancies or defects is responsible for the RS effect. Furthermore, a model is proposed to explain this resistance switching behaviour. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. 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.

  8. Facile synthesis of graphene-CeO2 nanocomposites with enhanced electrochemical properties for supercapacitors.

    Science.gov (United States)

    Saravanan, T; Shanmugam, M; Anandan, P; Azhagurajan, M; Pazhanivel, K; Arivanandhan, M; Hayakawa, Y; Jayavel, R

    2015-06-01

    Graphene-ceria (CeO2G) nanocomposites were prepared by using a low-temperature solution process with different weight percentages of graphene, and their electrochemical properties were investigated. Structural properties of the nanocomposites were studied by X-ray diffraction, Raman spectroscopy, and FTIR spectral analyses. FE-SEM and HRTEM images revealed a "wrinkled paper"-like morphology of the prepared composites. Elemental mapping images were recorded by using the FE-EPMA technique. XPS analyses revealed the binding states of different elements present in the composites. The composite with 5% graphene displayed a specific capacitance of 110 F g(-1), according to cyclic voltammetric studies, which is higher than that observed for pure CeO2 (75 F g(-1)). The significant increase in the specific capacitance suggests that the CeO2G is a promising material for supercapacitor applications. PMID:25940081

  9. Resistive switching behaviour of highly epitaxial CeO{sub 2} thin film for memory application

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun; Zhao, Hongbin; Wei, Feng; Yang, Mengmeng; Yang, Zhimin [General Research Institute for Nonferrous Metals, Beijing 100088 (China); Chen, Qiuyun; Chen, Jun [Science and Technology on Surface Physics and Chemistry Laboratory, Sichuan 621907 (China)

    2014-01-15

    We report on the remarkable potential of highly epitaxial and pure (001)-oriented CeO{sub 2} thin films grown on conducting Nb-doped SrTiO{sub 3} (NSTO) substrates by laser molecular beam epitaxy for nonvolatile memory application. Resistive switching (RS) devices with the structure of Au/epi-CeO{sub 2}/NSTO exhibit reversible and steady bipolar RS behaviour with large high/low resistance ratio and a narrow dispersion of the resistance values. Detailed analysis of the conduction mechanisms reveals that the trapping/detrapping processes and oxygen vacancies migration play important roles in the switching behaviour. In the light of XPS measurement results, the CeO{sub 2}/NSTO interface with oxygen vacancies or defects is responsible for the RS effect. Furthermore, a model is proposed to explain this resistance switching behaviour. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. 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.

  11. 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.

  12. 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.

  13. Experimental study on Hg0 removal from flue gas over columnar MnOx-CeO2/activated coke

    Science.gov (United States)

    Xie, Yine; Li, Caiting; Zhao, Lingkui; Zhang, Jie; Zeng, Guangming; Zhang, Xunan; Zhang, Wei; Tao, Shasha

    2015-04-01

    Mn-Ce mixed oxides supported on commercial columnar activated coke (MnCe/AC) were employed to remove elemental mercury (Hg0) at low temperatures (100-250 °C) without the assistance of HCl in flue gas. The samples were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Effects of some factors, including Mn-Ce loading values, active component, reaction temperatures and flue gas components (O2, SO2, NO, H2O), on Hg0 removal efficiency were investigated. Results indicated that the optimal Mn-Ce loading value and reaction temperature were 6% and 190 °C, respectively. Considerable high Hg0 removal efficiency (>90%) can be obtained over MnCe6/AC under both N2/O2 atmosphere and simulated flue gas atmosphere at 190 °C. Besides, it was observed that O2 and NO exerted a promotional effect on Hg0 removal, H2O exhibited a suppressive effect, and SO2 hindered Hg0 removal seriously when in the absence of O2. Furthermore, the XPS spectra of Hg 4f and Hg-TPD results showed that the captured mercury were existed as Hg0 and HgO on the MnCe6/AC, and HgO was the major species, which illustrated that adsorption and catalytic oxidation process were included for Hg0 removal over MnCe6/AC, and catalytic oxidation played the critical role. What's more, both lattice oxygen and chemisorbed oxygen or OH groups on MnCe6/AC contributed to Hg0 oxidation. MnCe6/AC, which exhibited excellent performance on Hg0 removal in the absence of HCl, appeared to be promising in industrial application, especially for low-rank coal fired flue gas.

  14. Interaction of Pseudomonas fluorescens with Eu(III) and Ce(IV) - Desferrioxamine Complexes

    Science.gov (United States)

    Yoshida, T.; Ozaki, T.; Ohnuki, T.; Francis, A.

    2002-12-01

    Naturally occurring chelating agents-, such as siderophores, are able to form complexes with actinides and enhance their solubility and mobility in the environment. Adsorption and/or biodegradation of chelated actinides by microorganisms are important processes which regulate their mobility in the natural environment. In this study, association of Eu(III), Ce(IV), and Fe(III) - desferrioxamine B (DFO) complexes with aerobic bacterium, Pseudomonas fluorescens (ATCC 55241), was investigated-, Eu(III) and Ce(IV) were used as analogues to trivalent and tetravalent actinides, respectively. When 20 μM of 1:1 Eu(III) - and Ce(IV) - DFO complexes were incubated with P. fluorescens in 0.1 M Tris-HCl buffer (pH = 7.3), the metals were removed from solution, with no change in DFO in solution. With decreasing metal/DFO molar ratio from 1 to 0.01, the accumulation of Eu(III) and Ce(IV) by P. fluorescens decreased. Kinetics study showed that accumulation of Eu(III) reached the maximum within 30 minutes, and then it decreased slightly with time. On the other hand, Ce(IV) accumulation proceeded in a parabolic process where the kinetics was slower than that of Eu(III) accumulation. In comparison to Eu(III) and Ce(IV), the removal of Fe(III) added as a DFO complex by P. fluorescens was not observed. The formation constants (log K) of Eu(III) - DFO and Fe(III) - DFO are reported to be 15 and 30.6, respectively. These results suggest that Eu(III) - DFO complex was dissociated in the presence of bacteria cells and was readily biosorbed.

  15. 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.

  16. CO, CO2 and H2 adsorption on ZnO, CeO2, and ZnO/CeO2 surfaces: DFT simulations.

    Science.gov (United States)

    Reimers, Walter G; Baltanás, Miguel A; Branda, María M

    2014-06-01

    The adsorption of the molecules CO, CO2, and H2 on several ceria and zinc oxide surfaces was studied by means of periodical DFT calculations and compared with infrared frequency data. The stable CeO2(111), CeO2(331), and ZnO(0001) perfect faces were the first substrates considered. Afterwards, the same surfaces with oxygen vacancies and a ZnO monolayer grown on Ceria(111) were also studied in order to compare the behaviors and reactivities of the molecules at those surfaces. The ceria surfaces were substantially more reactive than the ZnO surface towards the CO2 molecule. The highest adsorption energy for this molecule was obtained on the CeO2(111) surface with oxygen vacancies. The molecules CO and H2 both presented low or very low reactivities on all of the surfaces studied, although some reactivity was observed for the adsorption of CO onto the surfaces with oxygen vacancies, whereas H2 exhibited reactivity towards the CeO2(111) surface with oxygen vacancies. This work was performed to provide a firm foundation for novel process development in methanol synthesis from carbon oxides, steam reforming of methanol for hydrogen production, and/or the water-gas shift reaction. PMID:24903980

  17. 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.

  18. Role of the Ce valence in the coexistence of superconductivity and ferromagnetism of CeO$_{1-x}$F$_{x}$BiS$_{2}$ revealed by Ce $L_3$-edge x-ray absorption spectroscopy

    OpenAIRE

    Sugimoto, Takuya; Joseph, Boby; Paris, Eugenio; Iadecola, Antenolla; Mizokawa, Takashi; Demura, Satoshi; Mizuguchi, Yoshikazu; Takano, Yoshihiko; Saini, Naurang L.

    2014-01-01

    We have performed Ce $L_3$-edge x-ray absorption spectroscopy (XAS) measurements on CeO$_{1-x}$F$_x$BiS$_2$, in which the superconductivity of the BiS$_2$ layer and the ferromagnetism of the CeO$_{1-x}$F$_x$ layer are induced by the F-doping, in order to investigate the impact of the F-doping on the local electronic and lattice structures. The Ce $L_3$-edge XAS spectrum of CeOBiS$_2$ exhibits coexistence of $4f^1$ (Ce$^{3+}$) and $4f^0$ (Ce$^{4+}$) state transitions revealing Ce mixed valency...

  19. O{sup -} centers in LuAG:Ce,Mg ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Chen; Liu, Shuping [Key Laboratory of Transparent Opto-functional Inorganic Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai (China); University of Chinese Academy of Sciences, Beijing (China); Fasoli, Mauro; Vedda, Anna [Department of Materials Science, University of Milano-Bicocca, Milan (Italy); Nikl, Martin [Institute of Physics, ASCR, Prague (Czech Republic); Feng, Xiqi; Pan, Yubai [Key Laboratory of Transparent Opto-functional Inorganic Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai (China)

    2015-04-01

    Electron traps are known to a have great influence on the carriers transport process in Ce based scintillators. On the other hand, the role of hole traps in the scintillation process has been less considered. By means of electron spin resonance (ESR), we detected hole traps in highly Ce-doped LuAG:Ce,Mg ceramics in the form of σ-type O{sup -} centers. The g -tensor components turn out to be g {sub perpendicular} {sub to} = 2.0103, and g {sub parallel} = 2.0023, revealing the axial symmetry of these defects. Mg-perturbed variants of O{sup -} centers are proposed to exist in LuAG:Ce,Mg. Their occurrence is related to an elongated Mg-O bond as evidenced by DFT calculations. Finally, the multiple role of O{sup -} centers in the scintillation process is discussed. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Optical properties and radiation response of Ce{sup 3+}-doped GdScO{sub 3} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yamaji, Akihiro; Fujimoto, Yutaka; Futami, Yoshisuke; Yokota, Yuui; Kurosawa, Shunsuke [Institute of Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Kochurikhin, Vladimir [General Physics Institute, 38 Vavilov Str., 119991 Moscow (Russian Federation); Yanagida, Takayuki [New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Yoshikawa, Akira [Institute of Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

    2012-12-15

    10%-Ce doped GdScO{sub 3} perovskite type single crystal was grown by the Czochralski process. The Ce concentration in the crystal was measured. No impurity phases were observed by powder X-ray diffraction analysis. We evaluated the optical and radiation properties of the grown crystal. Ce:GdScO{sub 3} crystal showed photo- and radio-luminescence peaks due to Ce{sup 3+} of 5d-4f transition and colour centre. The photoluminescence decay time was sub-ns order. The relative light yield under 5.5 MeV alpha-ray excitation was calculated to be approximately 9% of BGO. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. 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.

  2. Scintillation mechanism and radiation damage in Ce{sub x}La{sub 1-x}F{sub 3} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Wojtowicz, A.J.; Wisniewski, D. [Boston Univ., MA (United States)]|[N. Copernicus Univ., Torun (Poland); Lempicki, A.; Brecher, C. [Boston Univ., MA (United States); Bartram, R.H. [Univ. of Connecticut, Storrs (United States); Woody, C.; Levy, P.; Stoll, S.; Kierstead, J. [Brookhaven National Lab., Upton, NY (United States); Pedrini, C. [CNRS, Villeurbanne (France)] [and others

    1994-08-01

    Recent spectroscopic and radiation damage experiments on a series of Ce{sub x}La{sub 1{minus}x}F{sub 3} crystals suggest that the scintillation light output is limited by an unusual quenching mechanism, which also plays a major role in minimizing radiation-induced damage. The intensity of the radiation-induced absorptions is a strong function of the Ce content x, reaching a maximum for x = 0.03 and a minimum for x = 1. This peculiar dependence appears to be due to the influence of deep-lying Ce levels on both scintillation mechanism and radiation damage. The authors suggest that various charge transfer processes can explain many aspects of the performance of Ce{sub x}La{sub 1{minus}x}F{sub 3} scintillators.

  3. The mechanism of the nano-CeO2 films deposition by electrochemistry method as coated conductor buffer layers

    International Nuclear Information System (INIS)

    Highlights: • Crack-free CeO2 film thicker than 200 nm was prepared on NiW substrate by ED method. • Different electrochemical processes as hydroxide/metal mechanisms were identified. • The CeO2 precursor films deposited by ED method were in nano-scales. - Abstract: Comparing with conventional physical vapor deposition methods, electrochemistry deposition technique shows a crack suppression effect by which the thickness of CeO2 films on Ni–5 at.%W substrate can reach a high value up to 200 nm without any cracks, make it a potential single buffer layer for coated conductor. In the present work, the processes of CeO2 film deposited by electrochemistry method are detailed investigated. A hydroxide reactive mechanism and an oxide reactive mechanism are distinguished for dimethyl sulfoxide and aqueous solution, respectively. Before heat treatment to achieve the required bi-axial texture performance of buffer layers, the precursor CeO2 films are identified in nanometer scales. The crack suppression for electrochemistry deposited CeO2 films is believed to be attributed to the nano-effects of the precursors

  4. The mechanism of the nano-CeO{sub 2} films deposition by electrochemistry method as coated conductor buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yuming; Cai, Shuang [Department of Physics, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of High Temperature Superconductors, Shanghai 200444 (China); Liang, Ying, E-mail: yliang@ecust.edu.cn [Institute of Nuclear Technology and Application, School of Science, East China University of Science and Technology, Shanghai 200237 (China); Bai, Chuanyi; Liu, Zhiyong; Guo, Yanqun; Cai, Chuanbing [Department of Physics, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of High Temperature Superconductors, Shanghai 200444 (China)

    2015-05-15

    Highlights: • Crack-free CeO{sub 2} film thicker than 200 nm was prepared on NiW substrate by ED method. • Different electrochemical processes as hydroxide/metal mechanisms were identified. • The CeO{sub 2} precursor films deposited by ED method were in nano-scales. - Abstract: Comparing with conventional physical vapor deposition methods, electrochemistry deposition technique shows a crack suppression effect by which the thickness of CeO{sub 2} films on Ni–5 at.%W substrate can reach a high value up to 200 nm without any cracks, make it a potential single buffer layer for coated conductor. In the present work, the processes of CeO{sub 2} film deposited by electrochemistry method are detailed investigated. A hydroxide reactive mechanism and an oxide reactive mechanism are distinguished for dimethyl sulfoxide and aqueous solution, respectively. Before heat treatment to achieve the required bi-axial texture performance of buffer layers, the precursor CeO{sub 2} films are identified in nanometer scales. The crack suppression for electrochemistry deposited CeO{sub 2} films is believed to be attributed to the nano-effects of the precursors.

  5. 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

  6. 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.

  7. Microwave-assisted hydrothermal synthesis of CePO4 nanostructures: Correlation between the structural and optical properties

    International Nuclear Information System (INIS)

    Highlights: • An enhancement in the hydrothermal synthesis for obtaining of CePO4 is presented. • Microwave energy can replace the energy by convection for obtaining CePO4. • CePO4 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. • CePO4 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 (CePO4) 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 CePO4 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 CePO4 with different microstructures were studied. The results demonstrated that by using the microwave-assisted hydrothermal method, the shape, size and structural phase of CePO4 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

  8. Integration of atomic layer deposition CeO2 thin films with functional complex oxides and 3D patterns

    International Nuclear Information System (INIS)

    We present a low-temperature, < 300 °C, ex-situ integration of atomic layer deposition (ALD) ultrathin CeO2 layers (3 to 5 unit cells) with chemical solution deposited La0.7Sr0.3MnO3 (LSMO) functional complex oxides for multilayer growth without jeopardizing the morphology, microstructure and physical properties of the functional oxide layer. We have also extended this procedure to pulsed laser deposited YBa2Cu3O7 (YBCO) thin films. Scanning force microscopy, X-ray diffraction, aberration corrected scanning transmission electron microscopy and macroscopic magnetic measurements were used to evaluate the quality of the perovskite films before and after the ALD process. By means of microcontact printing and ALD we have prepared CeO2 patterns using an ozone-robust photoresist that will avoid the use of hazardous lithography processes directly on the device components. These bilayers, CeO2/LSMO and CeO2/YBCO, are foreseen to have special interest for resistive switching phenomena in resistive random-access memory. - Highlights: • Integration of atomic layer deposition (ALD) CeO2 layers on functional complex oxides • Resistive switching is identified in CeO2/La0.7Sr0.3MnO3 and CeO2/YBa2Cu3O7 bilayers. • Study of the robustness of organic polymers for area-selective ALD • Combination of ALD and micro-contact printing to obtain 3D patterns of CeO2

  9. Oxygen vacancy formation in CeO2 and Ce(1-x)Zr(x)O2 solid solutions: electron localization, electrostatic potential and structural relaxation.

    Science.gov (United States)

    Wang, Hai-Feng; Li, Hui-Ying; Gong, Xue-Qing; Guo, Yang-Long; Lu, Guan-Zhong; Hu, P

    2012-12-28

    Ceria (CeO(2)) and ceria-based composite materials, especially Ce(1-x)Zr(x)O(2) solid solutions, possess a wide range of applications in many important catalytic processes, such as three-way catalysts, owing to their excellent oxygen storage capacity (OSC) through the oxygen vacancy formation and refilling. Much of this activity has focused on the understanding of the electronic and structural properties of defective CeO(2) with and without doping, and comprehending the determining factor for oxygen vacancy formation and the rule to tune the formation energy by doping has constituted a central issue in material chemistry related to ceria. However, the calculation on electronic structures and the corresponding relaxation patterns in defective CeO(2-x) oxides remains at present a challenge in the DFT framework. A pragmatic approach based on density functional theory with the inclusion of on-site Coulomb correction, i.e. the so-called DFT + U technique, has been extensively applied in the majority of recent theoretical investigations. Firstly, we review briefly the latest electronic structure calculations of defective CeO(2)(111), focusing on the phenomenon of multiple configurations of the localized 4f electrons, as well as the discussions of its formation mechanism and the catalytic role in activating the O(2) molecule. Secondly, aiming at shedding light on the doping effect on tuning the oxygen vacancy formation in ceria-based solid solutions, we summarize the recent theoretical results of Ce(1-x)Zr(x)O(2) solid solutions in terms of the effect of dopant concentrations and crystal phases. A general model on O vacancy formation is also discussed; it consists of electrostatic and structural relaxation terms, and the vital role of the later is emphasized. Particularly, we discuss the crucial role of the localized structural relaxation patterns in determining the superb oxygen storage capacity in kappa-phase Ce(1-x)Zr(1-x)O(2). Thirdly, we briefly discuss some

  10. 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.

  11. Electrical resistivity of CeFe2

    International Nuclear Information System (INIS)

    Electrical and magneitc properties of CeFe2 were investigated from the temperature dependence of electrical resistivity in the range of 1,5 to 3000K. The critical temperature, determined from the maximum of dp/dT, gives T sub(c) = 2200K and the temperature independent magnetic resistivity is 87μωcm. This value is compared with the corresponding in YFe2. At low temperature the resistivity shows a fairly large variation proportional to AT2 up to about 320K with A = 1,2x10-2 μωcm/0K2. (Author)

  12. Internal bremsstrahlung spectrum of 139Ce

    International Nuclear Information System (INIS)

    The internal bremsstrahlung spectrum which accompanies the electron capture decay of 139Ce to the first excited state of 139La has been measured in coincidence with the nuclear gamma ray which deexcites that state. The measured intensity above 42 keV is found to be (1.070±0.024) times that predicted by the recent calculations of Suriacute c et al. The QEC value is found to be 264.6±2.0 keV. copyright 1996 The American Physical Society

  13. 放眼CeBIT 2010

    Institute of Scientific and Technical Information of China (English)

    李璐

    2010-01-01

    @@ 来自国际展览业巨头汉诺威公司的消息,作为全球规模最大的ICT产业盛会,2010年在德国举行的汉诺威消费电子,信息及通信博览会(CeBIT),将吸引更多中国企业参展,在这个高端舞台上,放眼国际市场寻找商机.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  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. 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.

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

    International Nuclear Information System (INIS)

    (Nd1−xCex)30Fe69B (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 (Tc) decreases from 582.4 to 504.8 K, saturation magnetization (Ms) decreases from 15.88 to 12.71 kGs, and anisotropy field (HA) 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 Ms. - Highlights: • With the increase of Ce, Tc, Ms, and HA decrease gradually, but relatively gentle. • The (Nd1-xCex)30Fe69B alloys have potential to be prepared as permanent magnets. • Ce is tending to diffuse into the Nd-rich phase instead of main phase

  4. 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.

  5. Near-infrared luminescence of Tm3+-doped CeO2 films based on silicon substrates

    International Nuclear Information System (INIS)

    CeO2/Tm2O3 multilayer films were deposited on silicon substrates by electron-beam evaporation. Tm3+ ions were doped in CeO2 after the films were annealed in oxygen atmosphere at 1000 C. The doping concentration of Tm3+ 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 1G4-3H5, 3H4-3H6, 1G4-3H4, 3H5-3H6, 3F2-3H5, 3H4-3F4, 1G4-3F3,2 and 3F4-3H6 transitions of Tm3+, respectively. The dominant transition of 3H4-3H6 near 805 nm was within optical transmission window. The luminescence properties and the crystal structure of CeO2:Tm3+ films were investigated by excitation and emission spectroscopy and X-ray diffraction. Meanwhile, the substitution process of Ce4+ by Tm3+ was illustrated, and lattice expansion of the matrix CeO2 gave rise to the increase in FWHM of CeO2 diffraction peaks. In addition, the effect of Tm3+ concentration on photoluminescence was also studied, and the optimal concentration of Tm3+ was 0.5 mol%. (orig.)

  6. 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.

  7. 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.

  8. 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. PMID:24369902

  9. Sn-CeO2 thin films prepared by rf magnetron sputtering: XPS and SIMS study

    International Nuclear Information System (INIS)

    Sn addition in the CeO2 thin film by simultaneous Sn metal and cerium oxide magnetron sputtering causes growth of Ce3+ rich films whilst pure cerium oxide sputtering provides stoichiometric CeO2 layers. Ce4+ → Ce3+ conversion is explained by a charge transfer from Sn atoms to unoccupied orbital Ce 4f0 of cerium oxide by forming Ce 4f1 state. XPS and SIMS revealed a formation of a new chemical Ce(Sn)+ state, which belongs to SnCeO2 species.

  10. 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/...

  11. Study of f electron correlations in nonmagnetic Ce by means of spin resolved resonant photoemission

    Energy Technology Data Exchange (ETDEWEB)

    Yu, S; Komesu, T; Chung, B W; Waddill, G D; Morton, S A; Tobin, J G

    2005-11-28

    We have studied the spin-spin coupling between two f electrons of nonmagnetic Ce by means of spin resolved resonant photoemission using circularly polarized synchrotron radiation. The two f electrons participating in the 3d{sub 5/2} {yields} 4f resonance process are coupled in a singlet while the coupling is veiled in the 3d{sub 3/2} {yields} 4f process due to an additional Coster-Kronig decay channel. The identical singlet coupling is observed in the 4d {yields} 4f resonance process. Based on the Ce measurements, it is argued that spin resolved resonant photoemission is a unique approach to study the correlation effects, particularly in the form of spin, in the rare-earths and the actinides.

  12. 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.

  13. 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.

  14. Structural and electrical properties of nonstoichiometric semiconducting pyrochlores in Ca-Ce-Ti-Nb-O system

    International Nuclear Information System (INIS)

    Research highlights: → Nonstoichiometric semiconducting pyrochlores, CaCexTiNbO7-δ (x = 0.5-1.0) system have been synthesized by the conventional solid state route. → CaCe0.7TiNbO6.55, crystallizes into a pure cubic pyrochlore structure by accommodating smaller Ti ions on the A site. → The impedance analysis indicates relaxor behavior of these compounds due to disorder in the system. - Abstract: A series of quaternary nonstoichiometric cubic pyrochlores with varying cerium content in Ca-Ce-Ti-Nb-O system has been synthesized through solid state route. The powder X-ray diffraction and Rietveld analysis indicate that smaller Ti cation occupies the A site by displacing the A and O' ions causing displacive disorder in the cubic pyrochlore structure. The electrical conductivity measurements reveal that they exhibit semiconductor behavior in a broad temperature range (30-600 deg. C) and the conductivity increases with increase in Ce content. The X-ray photoelectron spectroscopy (XPS) analysis corroborates the presence of Ce in 3+ state. The impedance analysis reveals two types of conduction processes from the frequency dependent conductivity plots, i.e. low frequency conduction due to short range hopping and high frequency conduction due to the localized reorientation hopping mechanism. The relaxational properties indicate that hopping frequency is dependent on cerium concentration and is a measure of degree of disorder in the system.

  15. Au/CeO{sub 2}-chitosan composite film for hydrogen peroxide sensing

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Wei [Key Laboratory of Medical Diagnostics, Ministry of Education, College of Laboratory Medicine, Chongqing Medical University, Chongqing 400016 (China); Xie Guoming, E-mail: guomingxie@cqmu.edu.cn [Key Laboratory of Medical Diagnostics, Ministry of Education, College of Laboratory Medicine, Chongqing Medical University, Chongqing 400016 (China); Li Shenfeng; Lu Lingsong; Liu Bei [Key Laboratory of Medical Diagnostics, Ministry of Education, College of Laboratory Medicine, Chongqing Medical University, Chongqing 400016 (China)

    2012-08-01

    Au nanoparticles (AuNPs) were in situ synthesized at the cerium dioxide nanoparticles (CeO{sub 2}NPs)-chitosan (CS) composite film by one-step direct chemical reduction, and the resulting Au/CeO{sub 2}-CS composite were further modified for enzyme immobilization and hydrogen peroxide (H{sub 2}O{sub 2}) biosensing. Transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), UV-vis spectra and electrochemical techniques have been utilized for characterization of the prepared composite. The stepwise assembly process and electrochemical performances of the biosensor were characterized by means of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and typical amperometric response (i-t). The Au/CeO{sub 2}-CS composite exhibited good conductibility and biocompatibility, and the developed biosensor exhibited excellent response to hydrogen peroxide in the linear range of 0.05-2.5 mM (r = 0.998) with the detection limit of 7 {mu}M (S/N = 3). Moreover, the biosensor presented high affinity (K{sub m}{sup app}=1.93mM), good reproducibility and storage stability. All these results demonstrate that the Au/CeO{sub 2}-CS composite film can provide a promising biointerface for the biosensor designs and other biological applications.

  16. 32 CFR Appendix B to Part 247 - CE Publications

    Science.gov (United States)

    2010-07-01

    ... publication any advertising of the following types: (1) paid political advertisements for a candidate, party... publication. CE publishers sell advertising to cover costs and secure earnings, print the publications, and... staff who produce the non-advertising content of the CE publication may perform certain...

  17. 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.

  18. Multimedia Experience on Web-Connected CE Devices

    Science.gov (United States)

    Tretter, Dan; Liu, Jerry; Zhang, Xuemei; Gao, Yuli; Atkins, Brian; Chao, Hui; Xiao, Jun; Wu, Peng; Lin, Qian

    Consumer electronics (CE) are changing from stand-alone single-function devices to products with increasing connectivity, convergence of functionality, and a focus on customer experience. We discuss the features that characterize the new generation of CE and illustrate this new paradigm through an examination of how web services can be integrated with CE products to deliver an improved user experience. In particular, we focus on one aspect of the CE segment, digital photography. We introduce AutoPhotobook, an automatic photobook creation service and provide a detailed look at how it addresses the complexity of photobook authoring through a portfolio of automatic photo analysis and composition technologies. We then show how this collection of technologies is integrated into a larger ecosystem with other web services and web-connected CE devices to deliver an enhanced user experience.

  19. 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.

  20. 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...

  1. Experimental study on Hg{sup 0} removal from flue gas over columnar MnO{sub x}-CeO{sub 2}/activated coke

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yine [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Li, Caiting, E-mail: ctli@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Zhao, Lingkui; Zhang, Jie; Zeng, Guangming; Zhang, Xunan; Zhang, Wei; Tao, Shasha [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China)

    2015-04-01

    Highlights: • The Hg{sup 0} removal efficiency over columnar MnCe6/activated coke up to 94%. • MnO{sub x} and CeO{sub 2} exhibited a significant synergistic role in Hg{sup 0} removal over MnCe/AC. • Lattice oxygen, chemisorbed oxygen and OH groups on the surface of MnCe/AC contributed to Hg{sup 0} oxidation. • Hg{sup 0} removal mechanisms over MnCe/AC were identified firstly. - Abstract: Mn-Ce mixed oxides supported on commercial columnar activated coke (MnCe/AC) were employed to remove elemental mercury (Hg{sup 0}) at low temperatures (100–250 °C) without the assistance of HCl in flue gas. The samples were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Effects of some factors, including Mn-Ce loading values, active component, reaction temperatures and flue gas components (O{sub 2}, SO{sub 2}, NO, H{sub 2}O), on Hg{sup 0} removal efficiency were investigated. Results indicated that the optimal Mn-Ce loading value and reaction temperature were 6% and 190 °C, respectively. Considerable high Hg{sup 0} removal efficiency (>90%) can be obtained over MnCe6/AC under both N{sub 2}/O{sub 2} atmosphere and simulated flue gas atmosphere at 190 °C. Besides, it was observed that O{sub 2} and NO exerted a promotional effect on Hg{sup 0} removal, H{sub 2}O exhibited a suppressive effect, and SO{sub 2} hindered Hg{sup 0} removal seriously when in the absence of O{sub 2}. Furthermore, the XPS spectra of Hg 4f and Hg-TPD results showed that the captured mercury were existed as Hg{sup 0} and HgO on the MnCe6/AC, and HgO was the major species, which illustrated that adsorption and catalytic oxidation process were included for Hg{sup 0} removal over MnCe6/AC, and catalytic oxidation played the critical role. What's more, both lattice oxygen and chemisorbed oxygen or OH groups on MnCe6/AC contributed to Hg{sup 0} oxidation. MnCe6/AC, which exhibited

  2. Color tuning of Ba{sub 2}ZnSi{sub 2}O{sub 7}:Ce{sup 3+}, Tb{sup 3+} phosphor via energy transfer

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhongfu; Hu, Yihua, E-mail: huyh@gdut.edu.cn; Chen, Li; Wang, Xiaojuan

    2014-09-15

    A series of Ce{sup 3+} or Tb{sup 3+} doped and Ce{sup 3+}/Tb{sup 3+} co-doped Ba{sub 2}ZnSi{sub 2}O{sub 7} phosphors were prepared via the conventional high temperature solid state reaction method. The photoluminescence and energy transfer properties of samples were studied in detail. The optimal proportion of Ce{sup 3+} single doping is 2 mol% with maximal fluorescence intensity. Ba{sub 1.98−x}ZnSi{sub 2}O{sub 7}:0.02Ce{sup 3+}, xTb{sup 3+} shows both a blue emission (428 nm) from Ce{sup 3+} and a yellowish-green emission (542 nm) from Tb{sup 3+} with considerable intensity under ultraviolet (UV) excitation (352 nm). The emission chromaticity coordinates can be adjusted from blue to green region by tuning the concentration of Tb{sup 3+} ions from 0.00 to 0.06 through an energy transfer process. The energy transfer mechanism from Ce{sup 3+} to Tb{sup 3+} ions was proved to be dipole–dipole interaction. The Ce{sup 3+} and Tb{sup 3+} co-doped Ba{sub 2}ZnSi{sub 2}O{sub 7} phosphors are potential UV-convertible candidates with green light emitting in UV-LEDs for the high efficient energy transfer from Ce{sup 3+} to Tb{sup 3+} ions. - Highlights: • The emission color can be adjusted from blue to green region by tuning the concentration of Tb{sup 3+} ions. • There is very high transfer efficiency with the maximal value 84.4% from Ce{sup 3+} to Tb{sup 3+}. • The energy transfer mechanism from Ce{sup 3+} to Tb{sup 3+} ions was proved to be dipole–dipole interaction.

  3. Controlled fabrication and enhanced photocatalystic performance of BiVO4@CeO2 hollow microspheres for the visible-light-driven degradation of rhodamine B

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • m-BiVO4@CeO2 hollow microspheres were firstly fabricated. • m-BiVO4@CeO2 was used for photocatalytic degradation of rhodamine B. • The photocatalytic activity of heterogeneous hollow microspheres is enhanced. • Photocatalytic mechanism on m-BiVO4@CeO2 by visible light irradiation was proposed. • Efficient separation of photoexcited charges results in enhanced catalytic activity. - Abstract: m-BiVO4@CeO2 hollow microspheres have been fabricated by a facile low-temperature co-precipitation method and subsequent annealing process. The composition, morphology and size of the as-fabricated m-BiVO4@CeO2 hollow microspheres were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The vibrational features and the electronic state of the as-obtained m-BiVO4@CeO2 hollow microspheres were studied by Raman spectra and X-ray photoelectron spectroscopy (XPS). Band-gap energy of the as-prepared m-BiVO4@CeO2 hollow microspheres was evaluated by UV–vis spectrum. The visible-light-driven photocatalystic performances were evaluated by degradation for RhB dye molecules, demonstrating that the as-fabricated m-BiVO4@CeO2 hollow microspheres exhibit the enhanced photocatalystic activity, compared to the obtained pure m-BiVO4 microspheres. The separation of photoinduced electron–hole pairs and transfer between CeO2 and BiVO4 has been discussed in detail, in order to have in-depth understanding on the enhanced photocatalytic performance. The results indicate that the enhanced photocatalystic activity of the as-fabricated m-BiVO4@CeO2 hollow microspheres is attributed to the efficient separation of the photoexcited electrons and holes

  4. Enthalpies of mixing in binary Fe-Sb, Ce-Fe and ternary Ce-Fe-Sb liquid alloys

    Energy Technology Data Exchange (ETDEWEB)

    Usenko, Natalia; Kotova, Natalia [Taras Shevchenko National Univ., Kyiv (Ukraine). Dept. of Chemistry; Ivanov, Michael; Berezutski, Vadim [National Academy of Sciences, Kyiv (Ukraine). I. Frantsevich Institute for Problems of Materials Science

    2016-01-15

    The enthalpies of mixing in liquid alloys in the binary Fe-Sb, Ce-Fe and ternary Ce-Fe-Sb systems were determined over a wide range of composition by means of isoperibolic calorimetry in the temperature range 1600-1830 K. The minimum values of the integral enthalpy of mixing (ΔH{sub min}) were determined to be (-2.32 ± 0.22) kJ . mol{sup -1} at x{sub Sb} = 0.5 in the Fe-Sb system, and (-0.97 ± 0.19) kJ . mol{sup -1} at x{sub Ce} = 0.35 in the Ce-Fe system. The enthalpies of mixing in liquid ternary Ce-Fe-Sb alloys were found to increase smoothly from the binary boundary systems Ce-Fe and Fe-Sb towards the Ce-Sb system, reaching the minimum value of (-107.5 ± 3.6) kJ . mol{sup -1} in the vicinity of the phase CeSb.

  5. 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.

  6. 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.

  7. Structural and growth aspects of electron beam physical vapor deposited NiO-CeO2 nanocomposite films

    International Nuclear Information System (INIS)

    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-CeO2 (30/70 wt. %) composites on quartz substrate by EB-PVD. Two NiO-CeO2 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 CeO2 and NiO. Deposition using pure CeO2 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-CeO2 composite. The results demonstrate the influence of electron beam gun power on the adatom energy for the growth process of composite oxide thin films

  8. 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.

  9. Applicability of CeO 2 as a surrogate for PuO 2 in a MOX fuel development

    Science.gov (United States)

    Kim, Han Soo; Joung, Chang Yong; Lee, Byung Ho; Oh, Jae Yong; Koo, Yang Hyun; Heimgartner, Peter

    2008-08-01

    The applicability of cerium oxide, as a surrogate for plutonium oxide, was evaluated for the fabrication process of a MOX (mixed oxide) fuel pellet. Sintering behavior, pore former effect and thermal properties of the Ce-MOX were compared with those of Pu-MOX. Compacting parameters of the Pu-MOX powder were optimized by a simulation using Ce-MOX powder. Sintering behavior of Ce-MOX was very similar to that of Pu-MOX, in particular for the oxidative sintering process. The sintered density of both pellets was decreased with the same slope with an increasing DA (dicarbon amide) content. Both the Ce-MOX and Pu-MOX pellets which were fabricated by an admixing of 0.05 wt% DA and sintering in a CO 2 atmosphere had the same average grain size of 11 μm and a density of 95%T.D. The thermal conductivity of the Pu-MOX was a little higher than that of the Ce-MOX at a lower temperature but both conductivities became closer to each other above 900 K. Cerium oxide was found to be a useful surrogate to simulate the Pu behavior in the MOX fuel fabrication.

  10. 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.

  11. The application of GNSS in the near-Earth navigation of China’s lunar probe CE-5T1

    Science.gov (United States)

    Huang, Yong; Fan, Min; Hu, Xiaogong; Li, Peijia

    2015-08-01

    After CE-1, CE-2 and CE-3, China’s fourth lunar probe CE-5T1 was launched on 23 Oct., 2014, which goal is to test the returning capability of the lunar probe. On 31 Oct., the landing portion of CE-5T1 successfully landed in the North China. CE-5T1 is a high eccentricity orbit with apogee of about 413 thousand km. A GNSS receiver was installed in CE-5T1 to test the ability of GNSS navigation for a High Earth Orbit (HEO) spacecraft. The receiver performed well and GPS side lobe signals have been tracked when the probe was at an altitude from 10000 to 60000 km during about two 3-hours periods, and most of time it is above the altitude of the GPS constellation. In these two periods, the average GPS satellites tracked is about 8-9, and the GDOP is from 1 to 30. We processed these GNSS data after the mission, and the noise level of the differenced pseudo-range is less than 10 m. We used the GNSS data to determine the orbit of CE-5T1, compared with the use of ground based tracking data including range, Doppler and VLBI. The results are encouraging, and the position difference between orbit determination (OD) with GNSS data and ground based data is less than 100 m. In CE-5T1 mission, the separation point is about 5000 km altitude, where the lander will separate from the orbiter then return to the ground. The separation point prediction accuracy directly affects the landing position. As plan there is a maneuver about 5 hours before the separation (canceled in fact), so there is only 3-4 hours tracking data to be used to predict the separation point. Analysis shows that combination of two types of data can improve the orbit accuracy as well as the accuracy of the predicted orbit. CE-5T1 made a successful test of the GNSS using for HEO spacecraft. Obviously, GNSS can be used as a low-cost OD sensor and the use of GNSS technique can reduce the observing pressure of the ground antenna in the lunar and deep space exploration.

  12. 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)

  13. 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.

  14. 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.))

  15. 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.

  16. Reel-to-reel continuous simultaneous double-sided deposition of highly textured CeO2 templates for YBa2Cu3O7-δ coated conductors

    International Nuclear Information System (INIS)

    A reel-to-reel system which allows simultaneous two-sided deposition of epitaxial CeO2 buffer layers on long length biaxially textured Ni-5 at.%W tape with direct current (dc) reactive magnetron sputtering is described. Deposition is accomplished through two opposite symmetrical sputtering guns with a radiation heater. Meter-long double-sided epitaxial CeO2 buffer layers have been produced for the first time on textured metal substrates in a run using a reel-to-reel process with a speed of about 1.2 m h-1. The CeO2 films were characterized by means of x-ray diffraction (XRD) and atomic force microscopy (AFM). The samples exhibited good epitaxial growth with the c-axis perpendicular to the substrate surface for both sides. Full width at half maximum (FWHM) values of the out-of-plane and in-plane orientation for both sides were 3.20 and 3.10, 5.30 and 5.10, respectively. AFM observations revealed a smooth, dense and crack-free surface morphology. In addition, x-ray scans have been performed as a function of length to determine the crystallographic consistency of the epitaxial CeO2 over the length. Subsequently anyttria-stabilized zirconia (YSZ) barrier and CeO2 cap layers were deposited to complete the CeO2/YSZ/CeO2 structure via the same process. Epitaxial YBa2Cu3O7-δ (YBCO) films grown by dc sputtering on the short prototype CeO2/YSZ/CeO2/NiW conductors yielded self-field critical current densities (Jc) as high as 1.3 MA cm-2 at 77 K. An Ic value of 113 A cm-1 was obtained for double-sided YBCO coated conductors

  17. Faceting of (001) CeO2 Films: The Road to High Quality TFA-YBa2Cu3O7 Multilayers

    International Nuclear Information System (INIS)

    CeO2 films are technologically important as a buffer layer for the integration of superconducting YBa2Cu3O7 films on biaxially textured Ni substrates. The growth of YBa2Cu3O7 layers on the CeO2 cap layers by the trifluoroacetate (TFA) route remains a critical issue. To improve the accommodation of YBa2Cu3O7 on CeO2, surface conditioning or CeO2 is required. In this work we have applied ex-situ post-processes at different atmospheres to the CeO2 layers deposited on YSZ single crystals using rf sputtering. XPS analysis showed that post-annealing CeO2 layer in Ar/H2/H2O catalyses in an unexpected way the growth of (001)- terraces. We also report on the growth conditions of YBa2Cu3O7-TFA on CeO2 buffered YSZ single crystal grown by chemical solution deposition and we compare them with those leading to optimized YBa2Cu3O7-TFA films on LaAlO3 single crystals. Critical currents up to 1.6 MA/cm2 at 77 K have been demonstrated in 300 nm thick YBa2Cu3O7 layers on CeO2/YSZ system. The optimized processing conditions have then been applied to grow YBa2Cu3O7-TFA films on Ni substrates having vacuum deposited cap layers of CeO2

  18. CE-merkityn murskeen tuottaminen rakennusurakan sivutuottena - kannattavuusselvitys

    OpenAIRE

    Komulainen, Ville

    2014-01-01

    Työssä tutkittiin murskatun kiviaineksen CE-merkintäperusteita sekä mitä tuotannollisia sekä laadullisia vaatimuksia kiviainestuotannolle CE-merkintä edellyttää. Lisäksi tutkittiin, onko mahdollista saada CE-merkityn kiviaineksen tuotanto ISO 9001 -standardin sisältävän laadunhallintajärjestelmän alle ja voiko tuotanto olla osa kyseistä laadunhallintajärjestelmää. Työ tehdään Graniittirakennus Kallio Oy:lle. Tuotannon kannattavuusselvityksen osalta tutkittiin eri tuotantomalleja, mikä on ...

  19. Non-Fermi Liquid Scaling in CeRhSn

    International Nuclear Information System (INIS)

    We have recently shown that CeRhSn exhibits non-Fermi liquid temperature dependences in its low-temperature physical properties. Here we suggest that the non-Fermi liquid behavior observed in CeRhSn may be due to the existence of a Griffiths phase in the vicinity of a quantum critical point, based on electrical resistivity, magnetic susceptibility , and specific heat measurements. For CeRhSn, the low-temperature scaling of bulk properties (C/T ∝ χ ∝ T-1+λ, where λ<1) is masked by an anomaly at about 6 K, which is of magnetic origin. (author)

  20. 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.

  1. 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.

  2. Determination of the Ce142(γ,n) cross section using quasi-monoenergetic Compton backscattered γ rays

    Science.gov (United States)

    Sauerwein, A.; Sonnabend, K.; Fritzsche, M.; Glorius, J.; Kwan, E.; Pietralla, N.; Romig, C.; Rusev, G.; Savran, D.; Schnorrenberger, L.; Tonchev, A. P.; Tornow, W.; Weller, H. R.

    2014-03-01

    Background: Knowing the energy dependence of the (γ,n) cross section is mandatory to predict the abundances of heavy elements using astrophysical models. The data can be applied directly or used to constrain the cross section of the inverse (n,γ) reaction. Purpose: The measurement of the reaction Ce142(γ,n)141Ce just above the reaction threshold amends the existing experimental database in that mass region for p-process nucleosynthesis and helps to understand the s-process branching at the isotope Ce141. Method: The quasi-monoenergetic photon beam of the High Intensity γ-ray Source (HIγS), TUNL, USA, is used to irradiate naturally composed Ce targets. The reaction yield is determined afterwards with high-resolution γ-ray spectroscopy. Results: The experimental data are in agreement with previous measurements at higher energies. Since the cross-section prediction of the Ce142(γ,n) reaction is exclusively sensitive to the γ-ray strength function, the resulting cross-section values were compared to Hauser-Feshbach calculations using different γ-ray strength functions. A microscopic description within the framework of the Hartree-Fock-BCS model describes the experimental values well within the measured energy range. Conclusions: The measured data show that the predicted (γ,n) reaction rate is correct within a factor of 2 even though the closed neutron shell N =82 is approached. This agreement allows us to constrain the (n,γ) cross section and to improve the understanding of the s-process branching at Ce141.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. Highly Enhanced Concentration and Stability of Reactive Ce^3+ on Doped CeO_2 Surface Revealed In Operando

    OpenAIRE

    Chueh, William C.; McDaniel, Anthony H.; Grass, Michael E.; Hao, Yong; Jabeen, Naila; Liu, Zhi; Haile, Sossina M.; McCarty, Kevin F.; Bluhm, Hendrik; El Gabaly, Farid

    2012-01-01

    Trivalent cerium ions in CeO_2 are the key active species in a wide range of catalytic and electro-catalytic reactions. We employed ambient pressure X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy to quantify simultaneously the concentration of the reactive Ce^3+ species on the surface and in the bulk of Sm-doped CeO_2(100) in hundreds of millitorr of H2–H2O gas mixtures. Under relatively oxidizing conditions, when the bulk cerium is almost entirely in the 4+ oxida...

  9. Optical properties of CeNi{sub 5} and CeNi{sub 4}M (M = Al, Cu) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Knyazev, Yu. V., E-mail: knyazev@imp.uran.ru [Institute of Metal Physics, Ural Division, RAS, 18 Kovalevskaya St., 620990 Ekaterinburg (Russian Federation); Kuz' min, Yu. I.; Kuchin, A.G. [Institute of Metal Physics, Ural Division, RAS, 18 Kovalevskaya St., 620990 Ekaterinburg (Russian Federation)

    2011-01-21

    The experimental study of the optical properties of CeNi{sub 5}, CeNi{sub 4}Cu and CeNi{sub 4}Al compounds was carried out in the 0.083-5.64 eV energy range using the ellipsometry method. The optical constants, dielectric functions and electronic parameters (plasma and relaxation frequencies) were determined. The energy dependencies of the optical interband conductivities are discussed by using the available information on the electronic band structure of these compounds. In the ternary alloys the optical spectra show the presence of peculiarities related to effect of Cu or Al substitution at Ni sites.

  10. Optical properties of CeNi5 and CeNi4M (M = Al, Cu) compounds

    International Nuclear Information System (INIS)

    The experimental study of the optical properties of CeNi5, CeNi4Cu and CeNi4Al compounds was carried out in the 0.083-5.64 eV energy range using the ellipsometry method. The optical constants, dielectric functions and electronic parameters (plasma and relaxation frequencies) were determined. The energy dependencies of the optical interband conductivities are discussed by using the available information on the electronic band structure of these compounds. In the ternary alloys the optical spectra show the presence of peculiarities related to effect of Cu or Al substitution at Ni sites.

  11. 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.

  12. Ionic liquid-based hydrothermal synthesis and luminescent properties of CaF2:Ce3+/Mn2+ nanocrystals

    International Nuclear Information System (INIS)

    CaF2:Ce3+/Mn2+ sub-micro cubes and nanospheres were successfully prepared through an ionic liquid-based hydrothermal method. OmimPF6 and OmimBF4 were utilized to introduce a new fluoride source and act as templates. The effects of ionic liquid amount and species on the morphologies and sizes of the nanocrystals have been studied. The photoluminescence properties of CaF2:Ce3+/Mn2+ sub-micro cubes have been discussed, and the results show that the emission intensity of Mn2+ ions can be enhanced by co-doping with Ce3+ ions through an efficient resonance-type energy transfer process.

  13. 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.

  14. 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.

  15. Study of the nitric acid influence on the production of Ce O2 with high specific surface area

    International Nuclear Information System (INIS)

    The cerium oxide (Ce O2) main characteristics for use as catalyst in an exhaust gases purification system are: high specific surface area (approximately 30 m2/g after calcination at 800 deg C/ 2 hs), and thermal stability. The Ce O2 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 O2 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 (H2 O2) and starting material specific surface area. By this process, it was possible to obtain powders with specific surface area larger than 40 m2/g, after treatment at 800 deg C during two hours. (author)

  16. Thermoelectric Properties of Nanostructured CeAl3

    Science.gov (United States)

    Pokharel, Mani; Dahal, Tulashi; Ren, Zhifeng; Opeil, Cyril; Opeil Group Team; Ren Group Team

    2014-03-01

    Past investigations into the heavy fermion compound CeAl3 reveal a complex low-temperature physics resulting from the strong hybridization of localized 4f states with delocalized conduction electrons. This phenomenon gives rise to unusual electronic, thermal, and magnetic properties. We investigate the low-temperature thermoelectric properties of this strongly correlated system for its potential application as a p-type Peltier cooling element. In our work, nanostructured samples of CeAl3 have been prepared using dc hot-press method and evaluated for their thermoelectric properties. Effects of different hot-pressing temperatures on the nanostructure and the thermoelectric properties will be discussed. Our results on CeAl3 will be compared with our previous work on CeCu6. Funding for this work was provided by the DOD, USAF-OSR, MURI Program under Contract FA9550-10-1-0533.

  17. Three-Dimensional Structure of CeO2 Nanocrystals

    DEFF Research Database (Denmark)

    Tan, Joyce Pei Ying; Tan, Hui Ru; Boothroyd, Chris;

    2011-01-01

    Visualization of three-dimensional (3D) structures of materials at the nanometer scale can shed important information on the performance of their applications and provide insight into the growth mechanism of shape-controlled nanomaterials. In this paper, the 3D structures and growth pathway of CeO2...... samples synthesized under different conditions. The homogeneous growth environment in solution with polyvinylpyrrolidone (PVP) molecules led to the formation of regular octahedral CeO2 nanocrystals with small {001} facet truncations. When the PVP surfactant was removed, the aggregation of regular...... truncated octahedral CeO2 particles through a lattice matched interface generated irregular compressed truncated octahedral CeO2 nanoparticles. The formation of this irregular shape is attributed to the lower surface diffusion and slow incorporation of atoms on surfaces by step attachment of the fused...

  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 Na4UO2(CO3)3 in presence of Ce-141. II, Treatment of uranium decontamination

    International Nuclear Information System (INIS)

    It was settled down that the coexistence of chemical species structurally different of cerium, is a consequence of the preparation time; whose practical application, for the purification of the uranium, it can constitute the technological aspect but important in the ion exchange process, to separate the Ce-141 from the uranium. (Author)

  20. Hydrothermal synthesis of Ce: Lu_2SiO_5 scintillator powders

    Institute of Scientific and Technical Information of China (English)

    YUN Ping; SHI Ying; ZHOU Ding; XIE Jianjun

    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(NO_3)_3 with Na_2SiO_3 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 Ce~(3+).

  1. Solvothermal synthesis, electrochemical and photocatalytic properties of monodispersed CeO2 nanocubes

    International Nuclear Information System (INIS)

    Cubic-like CeO2 nanocrystals were successfully synthesized through an improved-toluene solvothermal process using hexadecylamine (HAD) as a capping agent and CeCl3.7H2O as a precursor at 180 deg. C for 24 h. These nanocubes are about 10 nm in size, and have a tendency to assemble into 2D superstructure. The obtained samples were characterized by means of X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). It was found that the water content, the concentration of ligand and kinds of aliphatic amine played important roles in the formation of the novel morphology. A possible formation mechanism was proposed based on the controlling reaction parameters. The electrochemical and photocatalytic properties of the as-synthesized samples exhibited the size/shape-dependent properties and potential applications.

  2. 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+.

  3. 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.

  4. Mesoporous Silica Coated CeF3:Tb3+ Particles for Drug Release

    Directory of Open Access Journals (Sweden)

    Deyan Kong

    2008-01-01

    Full Text Available CeF3:Tb3+ nanoparticles were successfully prepared by a polyol process using diethylene glycol (DEG as solvent. After being coated with dense silica, these CeF3:Tb3+ nanoparticles can be coated with mesoporous silica using nonionic triblock copolymer EO20PO70EO20 (P 123 as structure-directing agent. The composite can load ibuprofen and release the drug in the PBS. The composite was characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, nitrogen absorption/desorption isotherms, fluorescence spectra, and UV/Vis absorption spectra, respectively. The composite particles have considerable large pore volume and large surface area. In addition, the composite still emits strong green fluorescence (Tb3+ and can be used as fluorescent probes in drug delivery system.

  5. 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.

  6. 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.

  7. CeDeC, materiales educativos al alcance de todos

    OpenAIRE

    González, Agala

    2013-01-01

    El Centro Nacional de Desarrollo Curricular en Sistemas no Propietarios (CeDeC) tiene como finalidad el diseño, la promoción y el desarrollo de materiales educativos digitales a través de software libre. CeDeC pone a disposición de toda la comunidad educativa materiales y recursos educativos en su portal web

  8. 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.

  9. CeO2 nanoparticles for high performance supercapacitor electrode

    International Nuclear Information System (INIS)

    Cerium Oxide plays a vital role in rising technologies for energy-related applications. In this study, CeO2 nanoparticles have been successfully synthesized by microwave irradiation method and its capacitance performance is further investigated. Prepared nanoparticles were analysed by X-Ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). X-ray diffraction analysis confirms that CeO2 Nanoparticles in cubic phase and the grain size was calculated to be 15 nm using Debye-Scherrer formula. The FTIR spectrum of the CeO2 exhibits the stretching vibration of Ce-O at about 601 cm-1. The SEM analysis shows the irregular spherical morphology with some of the particles agglomerated. Electrochemical characterization of the sample was performed using a standard three electrode cell configuration. Cyclic Voltammogram (CV) and galvanostatic (GV) charge-discharge measurements demonstrated that the CeO2 electrode exhibited superior capacitive properties in 1 M Na2SO4 aqueous solution within the potential range -0.2V to 1.5V The discharge curves are linear in the total range of potential with constant slopes at a constant current of 0.9 A/g showing perfect capacitive behavior. These findings can open up new opportunities for CeO2 nanoparticles in constructing the high-performance electrochemical supercapacitors as well as other energy storage devices. (author)

  10. 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.

  11. 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.

  12. 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.

  13. Structural and optical study of Ce segregation in Ce-doped SiO{sub 1.5} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Beainy, G.; Castro, C.; Pareige, P.; Talbot, E., E-mail: etienne.talbot@univ-rouen.fr [Groupe de Physique des Matériaux, Université et INSA de Rouen, UMR CNRS 6634, Normandie Université, Avenue de l' Université, BP 12, 76801 St Etienne du Rouvray (France); Weimmerskirch-Aubatin, J.; Stoffel, M.; Vergnat, M.; Rinnert, H. [Université de Lorraine, UMR CNRS 7198, Institut Jean Lamour, BP 70239, 54506 Vandoeuvre-lès-Nancy (France)

    2015-12-21

    Cerium doped SiO{sub 1.5} thin films fabricated by evaporation and containing silicon nanocrystals were investigated by atom probe tomography. The effect of post-growth annealing treatment has been systematically studied to correlate the structural properties obtained by atom probe tomography to the optical properties measured by photoluminescence spectroscopy. The atom probe results demonstrated the formation of Ce-Si rich clusters upon annealing at 900 °C which leads to a drastic decrease of the Ce-related luminescence. At 1100 °C, pure Si nanocrystals and optically active cerium silicate compounds are formed. Consequently, the Ce-related luminescence is found to re-appear at this temperature while no Si-nanocrystal related luminescence is observed for films containing more than 3% Ce.

  14. Ce-doped nanoparticles of TiO{sub 2}: Rutile-to-brookite phase transition and evolution of Ce local-structure studied with XRD and XANES

    Energy Technology Data Exchange (ETDEWEB)

    Kityakarn, Sutasinee [Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10903 (Thailand); Center for Advanced Studies of Tropical Natural Resources, Kasetsart University, Bangkok 10903 (Thailand); Worayingyong, Attera [Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10903 (Thailand); Suramitr, Anwaraporn [Faculty of Science at Siracha, Kasetsart University, Siracha Campus, Chonburi 20230 (Thailand); Smith, M.F., E-mail: mfsmith@g.sut.ac.th [School of Physics, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Thailand Center of Excellence in Physics (ThEP), Commission of Higher Education, Ministry of Education, Bangkok 10400 (Thailand)

    2013-05-15

    The crystal and electronic structural changes undergone by TiO{sub 2} nanoparticles when Ce is introduced were studied using X-ray diffraction (XRD) and X-ray absorption near-edge spectroscopy (XANES). A small amount of Ce (less than 1% molar concentration) resulted in i/a significant reduction of the average size of the TiO{sub 2} nanoparticles and ii/a phase transition in which brookite replaced rutile as the minority phase component (anatase was the majority phase component at all Ce concentrations studied up to 10% molar concentration). The Ce L3 edge XANES revealed changes in the local environment of Ce impurities. As Ce concentration was increased the fraction of Ce that have formal valence of +3 decreased and, for the remaining Ce with valence +4, the 4f orbitals became less-strongly hybridized with the p-orbitals of oxygen neighbors. The results have implications for photocatalytic and gas sensing properties of Ce-doped TiO{sub 2}. - Highlights: ► Ce-doping: TiO{sub 2} nanoparticles shrink and minority phase changes rutile-> brookite. ► XANES reveals phase change for arbitrarily small particles (while XRD fails). ► As Ce added: fraction of Ce{sup +3} dopants falls, hybridization of Ce{sup +4} with O weakens.

  15. Non-Stoichiometry of UO2-CeO2: The System UO2-CeO2-CeO1.5 at 900 to 1200°C

    International Nuclear Information System (INIS)

    This investigation covers the substoichiometric fluorite (UO2-CeO2) phase, that is, the behaviour of the system U1-yCe1-yO2+x. Though UO2 and CeO2 are completely miscible, and in the CeO2-CeO1-5 system the fluorite phase extends to CeO1.72 , the UO2-CeO2-CeO1.5 system is characterized by a large two-phase region, where two fluorite- type structures, one CeO2-rich, the other UO2-rich, coexist. Only in the UO2-rich corner of the ternary system is a noticeable single-phase region present. This is in contrast to the CeO2-UO2-UO267 system where a large single-phase region exists. The oxygen activity as a function of composition x was measured in U1-yCe1-yO2+x (y = 0.15 and 0.35) at 900°C, using H2/H2O and metal/metal oxide equilibria. In all cases the oxygen activity increases extremely rapidly with decreasing x; the behaviour of the system resembles that of dilute solutions of UO2+X in ThO2. Both systems can be explained by assuming defect complexes: a vacancy bound to two Ce3+, an interstitial oxygen bound to two U5+. (author)

  16. 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.

  17. 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.

  18. 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.)

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Simultaneous removal of elemental mercury and NO from flue gas by V2O5–CeO2/TiO2 catalysts

    International Nuclear Information System (INIS)

    Highlights: • V2O5–CeO2/TiO2 catalyst was developed for both NO and Hg0 removal from simulated flue gas. • The existence of the redox cycle of V4+ + Ce4+ ↔ V5+ + Ce3+ over V2O5–CeO2/TiO2 catalyst could not only greatly improve the NO conversion, but also promote the oxidation of Hg0. • The roles of NH3/NO ratio, O2, SO2, and H2O (g) in the flue gas on both NO conversion and Hg0 oxidation were well explored. • A feasible one step process for nitrogen oxides and mercury removal in the flue gas was proposed. - Abstract: A series of Ce-doped V2O5/TiO2 catalysts synthesized by an ultrasound assisted impregnation method were employed to investigate simultaneous removal of elemental mercury (Hg0) and NO in lab-scale experiments. Scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), X-ray diffractogram (XRD), and X-ray photoelectron spectroscopy (XPS) analyses were used to characterize the samples. Compared to TiO2 support, the catalytic performance of CeO2 doped on both TiO2 and V2O5/TiO2 catalysts have been improved. Remarkably, 1%V2O5–10% CeO2/TiO2 (V1Ce10Ti) exhibited the highest Hg0 oxidation efficiency of 81.55% at 250 °C with a desired NO removal efficiency under the same condition. Both the NO conversion and Hg0 oxidation efficiency were enhanced in the presence of O2. The activity was inhibited by the injection of NH3 with the increase of NH3/NO. When in the presence of 400 ppm SO2, Hg0 oxidation was slightly affected. Furthermore, Hg0 removal behavior under both oxidation and selective catalytic reduction (SCR) condition over V1Ce10Ti were well investigated to further probe into the feasibility of one single unit for multi-pollutants control in industry application. The existence of the redox cycle of V4+ + Ce4+ ↔ V5+ + Ce3+ in V2O5–CeO2/TiO2 catalyst could not only greatly improve the NO conversion, but also promote the oxidation of Hg0

  5. 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.

  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. 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.

  8. Pressure and temperature dependence of the Ce valence and c -f hybridization gap in Ce T2In5(T =Co ,Rh ,Ir ) heavy-fermion superconductors

    Science.gov (United States)

    Yamaoka, H.; Yamamoto, Y.; Schwier, E. F.; Honda, F.; Zekko, Y.; Ohta, Y.; Lin, J.-F.; Nakatake, M.; Iwasawa, H.; Arita, M.; Shimada, K.; Hiraoka, N.; Ishii, H.; Tsuei, K.-D.; Mizuki, J.

    2015-12-01

    Pressure- and temperature-induced changes in the Ce valence and c -f hybridization of the Ce115 superconductors have been studied systematically. Resonant x-ray-emission spectroscopy indicated that the increase of the Ce valence with pressure was significant for CeCoIn5, and moderate for CeIr (In0.925Cd0.075)5 . We found no abrupt change of the Ce valence in the Kondo regime for CeIr (In0.925Cd0.075)5 , which suggests that valence fluctuations are unlikely to mediate the superconductivity in this material. X-ray-diffraction results were consistent with the pressure-induced change in the Ce valence. High-resolution photoelectron spectroscopy revealed a temperature-dependent reduction of the spectral intensity at the Fermi level, indicating enhanced c -f hybridization on cooling.

  9. Ce que Foucault a appris de Bentham

    Directory of Open Access Journals (Sweden)

    Christian Laval

    2011-05-01

    Full Text Available Michel Foucault, à plusieurs reprises et sous différents angles, a dit ce qu’il devait à Jeremy Bentham, considéré comme le principal « technologue » de la société disciplinaire. Mais Foucault est beaucoup plus qu’un lecteur  de Bentham. Il doit être regardé sur certains points comme un héritier théorique inavoué et sur d’autres comme un interprète  original de son œuvre et de sa place dans l’histoire des formes et des conceptions politiques. La conception foucaldienne du pouvoir comme structuration d’un  certain champ d’action rappelle immanquablement les considérations de Bentham sur « l’influence », sur la « méthode oblique »  et sur la « législation indirecte » par lesquelles on peut orienter le comportement des sujets. D’autre part, la distinction qu’il opère entre « souveraineté » et  « gouvernementalité »   permet de considérer d’une nouvelle façon l’originalité théorique et historique de l’auteur du Fragment sur le gouvernement. Le concept foucaldien de biopolitique en est un parfait exemple.Michel Foucault insisted in several instances, and in several ways, on what he owed Jeremy Bentham, the main “technologist” of disciplinary societies. But Foucault did not only read Bentham: he must be regarded as, on the one hand, an unacknowledged disciple, and on the other, an original interpreter of his work and his role in the history of political forms and concepts. Foucault’s understanding of power as the structuring of a field of action cannot fail to recall Bentham’s views on “influence” and on “indirect legislation” as means of channelling the subjects’ behaviour. Elsewhere, his distinction between “sovereignty” and “governmentality” allows us to cast a fruitful retrospective look on the thought of the author of the Fragment on Government. Foucault’s concept of “biopolitics” provides a perfect example.

  10. Sol–gel synthesis and characterization of fluoride-rich lanthanum-alumino-silicate gels doped with Ce{sup 3+} and Ti{sup 4+}

    Energy Technology Data Exchange (ETDEWEB)

    Lakshminarayana, G.; Torres, Joseph A.; Lin, Terri C. [Materials Science and Technology Division (MST-7), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Kityk, I.V. [Electrical Engineering Department, Czestochowa University Technology, Armii Krajowej 19, 42-201 Czestochowa (Poland); Hehlen, Markus P., E-mail: hehlen@lanl.gov [Materials Science and Technology Division (MST-7), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2014-07-15

    Highlights: • Lanthanum-alumino-silicate gels with high fluorine content are synthesized. • Trifluoroacetic acid (TFA) is used as the fluorine source in a sol–gel process. • Thermal decomposition of TFA prevents the conversion of gels to monolithic glasses. • The Ce-doped gels show photoluminescence in the blue spectral region. - Abstract: A series of lanthanum-alumino-silicate gels doped with Ce{sup 3+} (0.5–10.0 mol%) and Ti{sup 4+} were synthesized by a sol–gel process using trifluoroacetic acid (TFA) as a fluorine source. The structural (X-ray diffraction, scanning electron microscopy), thermal (differential scanning calorimetry), and optical (absorption, photoluminescence, photoluminescence-excitation) properties were investigated. A high fluorine content of up to 22.3 at.% was measured in the dried gels, significantly exceeding the ⩽5 at.% fluorine content of earlier studies. The monolithic gels were transparent, amorphous, and stable up to 250–300 °C. However, the gels lost their structural integrity at temperatures above 315 °C due to the thermal decomposition of TFA. The sol–gel route using TFA as a fluorine source is therefore not a viable route for the preparation of nanostructured glass ceramics containing a high volume fraction of crystalline LnF{sub 3}. All Ce{sup 3+}-doped gels showed luminescence in the blue spectral region. Gels containing Ti{sup 4+} had an additional strong oxygen-to-metal charge transfer transition that competed with the Ce{sup 3+} optical excitation and led to overall lower emission intensity. The measured luminescence intensity of all gel compositions decreased with increasing Ce{sup 3+} concentration as a result of increased reabsorption of Ce{sup 3+} emission by other Ce{sup 3+} ions in the gel as well as energy migration among Ce{sup 3+} ions to quenching sites.

  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

    International Nuclear Information System (INIS)

    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 x 10-11 m/s and k = 3.1 x 10-12[exp( - t/τ) + 1/(t + 10-4)], for powder and pellet form adsorbents, respectively.

  13. 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

    2016-06-01

    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 (ΔS 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 (|ΔS 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.

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

    International Nuclear Information System (INIS)

    Highlights: ► The YAG:Ce,Mn single crystal was well synthesized by the Czochralski (CZ) method. ► The emission intensity of the sample has been influenced after annealing. ► Annealed in the air at 1200 °C was the most optimal annealing condition. ► 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.

  15. 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.

  16. Investigation on the magnetic behaviour of CeO2 nanoparticles prepared by co-precipitation method

    International Nuclear Information System (INIS)

    Cerium oxide (CeO2) nanoparticles have been extensively studied owing to their potential in the fields of polishing powders, catalysts, gas sensors and electrode materials for solid oxide fuel cells. Numerous techniques have been proposed to synthesize nano-sized CeO2 particles with promising control of properties. Among them, due to the simple process, easy scale-up and low cost, the precipitation technique attracts more attention. In recent years, magnetic study on bulk and nanocrystalline CeO2 is gaining more interest in order to have a profound understanding of its magnetic origin. In this paper, we report the investigation of structural, optical and magnetic properties of nanocrystalline CeO2 synthesized by co-precipitation method. Phase analysis of the samples was done using X-Ray Diffraction (XRD) technique, which confirms the single phase formation of cubic CeO2. Transmission electron microscopy (TEM) images clearly illustrate the nanocrystalline nature (∼ 20 nm) and a uniform particle size distribution. The band gap, calculated using UV-Vis reflectance spectroscopy, was found to be 3.4 eV which is slightly greater than that of its bulk counterpart. Magnetization data was recorded using vibrating sample magnetometer (VSM) with a maximum applied field of ± 7 kOe. M-H curve of CeO2 nanoparticles presents a clear diamagnetic behaviour at room temperature in contrary to the earlier studies; the reason for which is discussed in detail based on the significant role of oxygen vacancies. (author)

  17. 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.)

  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. 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

  20. 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.

  1. 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.

  2. 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.

  3. Levels in 146Ce and the N = 88 isotones

    International Nuclear Information System (INIS)

    An investigation of the level structure of 146Ce following the beta decay of the low-spin isomer of 146La has been carried out at the ISOL facility TRISTAN at Brookhaven National Laboratory. The half-life for the low spin isomer was found to be 6.0 +- 0.4s. A partial level scheme for 146Ce below 2 MeV is given. The level energies and some B(E2) values extracted from our data have been compared with IBA-2 calculations done entirely with extrapolated parameters from neighboring Z nuclei in order to check the predictive power of the model. Systematics of the Z = 58 isotopes and N = 88 isotones indicate that although 146Ce is more deformed than its isotones with Z >= 60, the transition to the well-deformed region can probably more correctly be thought to occur after 146Ce, between N = 88 and N = 90, as it does for Z >= 60. The abrupt onset of deformation present in the higher Z isotopes is not seen in the Ce isotopes where the trend is found to be rather smooth throughout. (orig.)

  4. 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.

  5. 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

    2016-07-28

    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. PMID:27475371

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Performance Evaluation of CE-OFDM in PLC Channel

    Directory of Open Access Journals (Sweden)

    El ghzaoui Mohammed, Belkadid Jamal, Benbassou Ali

    2011-02-01

    Full Text Available One major drawback associated with an OFDM system is that the transmitter’soutput signal may have a high peak-to-average ratio (PAPR. High levels of PARmay be a limiting factor for power line communication (PLC where regulatorybodies have fixed the maximum amount of transmit power. To overcome thisproblem, many approaches have been presented in the literature. One potentialsolution for reducing the peak-to-average power ratio (PAPR in an OFDMsystem is to utilize a constant envelope OFDM (CE-OFDM system. This paperdescribes a CE-OFDM based modem for Power Line Communications (PLCover the low voltage distribution network. The impact of the electrical applianceson the signal transmission is investigated. The good performances of the BERhave been checked by the simulation platform of real PLC channel using Matlab.Finally, CE-OFDM-CPM is compared with conventional OFDM under HomePlugAV..

  11. Performance Evaluation of CE-OFDM in PLC Channel

    Directory of Open Access Journals (Sweden)

    El Ghzaoui Mohammed

    2011-02-01

    Full Text Available One major drawback associated with an OFDM system is that the transmitter’s output signal may have a high peak-to-average ratio (PAPR. High levels of PAR may be a limiting factor for power line communication (PLC where regulatory bodies have fixed the maximum amount of transmit power. To overcome this problem, many approaches have been presented in the literature. One potential solution for reducing the peak-to-average power ratio (PAPR in an OFDM system is to utilize a constant envelope OFDM (CE-OFDM system. This paper describes a CE-OFDM based modem for Power Line Communications (PLC over the low voltage distribution network. The impact of the electrical appliances on the signal transmission is investigated. The good performances of the BER have been checked by the simulation platform of real PLC channel using Matlab. Finally, CE-OFDM-CPM is compared with conventional OFDM under HomePlug AV.

  12. 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.

  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. 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...... to assess the efficiency of such a novel buffer layer stack. Biaxial texture quality and morphology of the buffer layers and the YBCO superconductor films were fully characterized. The surface crystallinity of the buffer layers is studied by the electron backscatter diffraction technique. It is revealed......-field), demonstrating that the novel CLO/GZO stack is very promising for further development of low cost buffer layer architectures for coated conductors....

  15. Technological Innovation and Urban Processes

    OpenAIRE

    Aragona, Stefano

    2006-01-01

    Technological innovation pushes transformatioin, rennovation and urban regenaration of areas and services. Special attention is given to the major urban centres, for the most related to nationale and/or Ue policy (Ce, 2003; Ce, 2004). A number of important questions are emerging between the reinforcement of the bigger areas, both metropolitan and urban, and the smaller centres. Moreover, according with different institutional actors it would be better more balanced process of anthropization b...

  16. 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.)

  17. The solid solutions (Ce1-xLax)RuSn

    International Nuclear Information System (INIS)

    X-Ray-pure samples of the solid solutions (Ce1-xLax)RuSn were obtained up to x = 0.5. Powder diffraction data show the CeRuSn-type superstructure up to x ∼ 0.3 and the CeCoAl-type subcell for higher lanthanum contents. The structure of a single crystal with x = 0.5 was refined on the basis of single-crystal X-ray diffractometer data: CeCoAl type, C2/m, a = 1160.8(2), b = 477.6(1), c = 511.6(1) pm, β = 102.97(2) , wR = 0.0510, 444 F2 values, 20 variables. Magnetic investigations were performed for all samples up to a lanthanum content of x = 0.4. No cooperative phenomena could be observed, and all samples show Curie-Weiss behavior above a certain temperature. The cerium valence is about 3.32(2) for all samples of the solid solution. Hence, La3+ has to replace Ce3+ as well as Ce4+ in a particular quantity. The electrical resistivity measurements confirm the suppression of the magnetic ordering and the structural transition upon replacement of cerium by lanthanum. 119Sn Moessbauer spectra of samples with x = 0.2 and 0.5 are indicative of single tin sites with isomer shifts of δ = 1.86(1) mm s-1 for x = 0.2 and δ = 1.88(1) mm s-1 for x = 0.5. Both signals are subject to significant quadrupole splitting, a consequence of the low site symmetry. Results of XANES measurements are perfectly in line with the cerium valences determined by susceptibility measurements and yield a constant value of 3.16(1) for all investigated compounds. (orig.)

  18. Microstructure and Composition of a Ce-pyrochlore: A Chemical Analog for Pu-pyrochlore

    Science.gov (United States)

    Xu, Huifang; Wang, Yifeng; Garvie, Laurence A. J.; Putnam, Robert L.; Navrotsky, Alexandra

    2003-07-01

    Ce-pyrochlore (CaCeTi2O7), is a chemical analogue for CaPuTi2O7, which is a proposed ceramic waste form for deposition of excess weapon-usable Pu in geological repositories. Ce-pyrochlore was synthesized by firing and annealing a mixture of Ce(NO3)4, TiO2, and Ca(OH)2 with a stoichiometry of CaCeTi2O7 at 1,300°C for 50 hours. The annealed product contains Ce-pyrochlore, Ce-bearing perovskite, CeO2 (cerianite), and minor CaO. Electron energy-loss spectroscopy (EELS) was used to determine the valence of Ce in the synthesized materials using the shape of the Ce M4,5 edge. Cerium in the perovskite is dominated by Ce3+. The Ce4+/ΣCe in the pyrochlore is 0.8, giving (Ca0.87Ce0.203+Ce0.864+Ti0.05)Ti2O7. High-resolution TEM images show that the boundary between pyrochlore and perovskite is semicoherently bonded. The orientational relationship between the neighboring pyrochlore and perovskite is not random. There are no glassy phases observed at the grain boundaries between pyrochlore and perovskite, and between CeO2 and pyrochlore. It is postulated, based on the presence of trivalent Ce in the Ce-pyrochlore, that the neutron poisons such as Gd can be incorporated into the CaPuTi2O7 phase.

  19. The influence of CeO2 on the microstructure and electrical behaviour of ZnO-Bi2O3 based varistors

    International Nuclear Information System (INIS)

    The processing-microstructure-property relations have been studied in order to understand the role of the addition of CeO2 (up to 0.9 mole%) in the ZnO-Bi2O3 based varistor recipe. The microstructural investigation suggests that CeO2 is segregated at the corners of the ZnO grains in addition to the existence of the Zn7Sb2O12 spinel phase. However, the α -spinel phase was observed instead of the β -spinel phase that is usually found in most commercial and laboratory ZnO-Bi2O3 based varistors. The α -spinel phase is more stable than the β -spinel phase and does not transform to the pyrochlore phase during the cooling process. The most significant effect of the CeO2 particles is the ZnO grain refinement owing to the pinning effect of the grain growth. The average grain size decreases from 7.8 to 5.7 μm when compared to the 0.9 mole% CeO2-added sample against the CeO2-free sample. This grain refinement results in a significantly enhanced breakdown field when compared to the CeO2-free sample. The coefficient of nonlinearity of the current-voltage (I-V) characteristics is found to be nearly identical for the CeO2 added varistor materials. However, when a slower cooling cycle (1 deg. C min-1 instead of 4 deg. C min-1) is used in the sintering process, these varistor materials exhibited a high nonlinear coefficient (α = 29 ± 5) as extracted from the I-V behaviour

  20. 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.

  1. 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 sensor structures. The present proposal to incorporate interfacial 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

  2. Certification of Confluence Proofs using CeTA

    OpenAIRE

    Nagele, Julian; Thiemann, René

    2015-01-01

    CeTA was originally developed as a tool for certifying termination proofs which have to be provided as certificates in the CPF-format. Its soundness is proven as part of IsaFoR, the Isabelle Formalization of Rewriting. By now, CeTA can also be used for certifying confluence and non-confluence proofs. In this system description, we give a short overview on what kind of proofs are supported, and what information has to be given in the certificates. As we will see, only a small amount of informa...

  3. 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.

  4. 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.

  5. 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.

  6. Synthesis and Luminescence Properties of (La,Ce,Tb)BO_3 Phosphors%(La,Ce,Tb)BO_3的合成及光谱性质

    Institute of Scientific and Technical Information of China (English)

    王林生; 文小强; 周健; 赖华生; 王玉香; 黄可龙

    2009-01-01

    采用高温固相法合成了(La,Ce,Tb)BO_3绿色发光粉,并对该发光粉进行了XRD和SEM分析.结果表明:(La,Ce,Tb)BO_3的晶体结构和LaBO_3相同,Ce~(3+)、Tb~(3+)的掺入并没有改变晶体的结构,发光粉颗粒大小均匀,形貌规则,粒度在5 μm左右.研究了(La,Ce,Tb)BO_3的光谱性质,在(La,Ce,Tb)BO_3的发射和激发光谱中除了有Tb~(3+)的特征发射和激发峰外,还有Ce~(3+)的特征发射和激发峰.比较了(La,Ce)BO_3发射光谱和(La,Tb)BO_3的激发光谱,两者存在重叠,这为Ce~(3+)→Tb~(3+)的能量传递提供了条件.将(La,Ce,Tb)BO_3的发射光谱与商品粉(La,Ce,Tb)PO_4进行比较,两者的发射主峰都在541 nm处, (La,Ce,Tb)BO_3在489 nm处的峰位稍有红移,通过计算表明,(La,Ce,Tb)BO_3的发光亮度达到商品粉(La,Ce,Tb)PO_4的94.7%.因此,(La,Ce,Tb)BO_3是一种很有应用前景的绿色发光粉.

  7. OILY WASTEWATER TREATMENT FOR CATALYTIC OXIDATION WITH K-MNO2/CeO2

    OpenAIRE

    JERÔNIMO, Carlos Enrique de Medeiros; FERNANDES, Hermano Gomes; SOUSA, João Fernandes

    2012-01-01

    The search for alternatives for the treatment of industrial effluents, especially high toxicity is one of the main difficulties of the industrial treatment systems. This work aims to use potassium as a promoter of electrons for the oxidation to the catalyst by impregnating it MnO2/CeO2 to degrade the effluent coming from the processing of cashew nuts in the presence of oxygen. The experiments were performed in a slurry bed reactor. In the experiments were kept constant initial concentratio...

  8. Oxygen vacancy pairs on CeO2(110): A DFT + U study

    International Nuclear Information System (INIS)

    Oxygen vacancy pairs have been suggested to play a role in the reduction of NO molecules on ceria and for the oxidation processes of reducible rare-earth oxides. The formation energy of the oxygen vacancy pairs and the changes in the structural and electronic properties of the ceria (110) surface with oxygen vacancy pairs are investigated using density-functional theory (DFT + U) methodology within the generalized gradient approximation. It is found that the excess electrons localize on the Ce ions neighbouring the vacancies, and the most stable structure for the oxygen vacancy pairs on the ceria (110) surface is at next-nearest-neighbour site.

  9. 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.

  10. Analysis of FEL-based CeC amplification at high gain limit

    International Nuclear Information System (INIS)

    An analysis of Coherent electron Cooling (CeC) amplifier based on 1D Free Electron Laser (FEL) theory was previously performed with exact solution of the dispersion relation, assuming electrons having Lorentzian energy distribution. At high gain limit, the asymptotic behavior of the FEL amplifier can be better understood by Taylor expanding the exact solution of the dispersion relation with respect to the detuning parameter. In this work, we make quadratic expansion of the dispersion relation for Lorentzian energy distribution and investigate how longitudinal space charge and electrons@@@ energy spread affect the FEL amplification process.

  11. Enhanced photocatalytic activity of CeO2 using β-cyclodextrin on visible light assisted decoloration of methylene blue.

    Science.gov (United States)

    Pitchaimuthu, Sakthivel; Velusamy, Ponnusamy

    2014-01-01

    An attempt has been made to enhance the photocatalytic activity of CeO(2) for visible light assisted decoloration of methylene blue (MB) dye in aqueous solutions by β-cyclodextrin (β-CD). The inclusion complexation patterns between host and guest (i.e., β-CD and MB) have been confirmed with UV-visible spectral data. The interaction between CeO(2) and β-CD has also been characterized by field emission scanning electron microscopy analysis. The photocatalytic activity of the catalyst under visible light was investigated by measuring the photodegradation of MB in aqueous solution. The effects of key operational parameters such as initial dye concentration, initial pH, CeO(2) concentration as well as illumination time on the decolorization extents were investigated. Among the processing parameters, the pH of the reaction solution played an important role in tuning the photocatalytic activity of CeO(2). The maximum photodecoloration rate was achieved at basic pH (pH 11). Under the optimum operational conditions, approximately 99.6% dye removal was achieved within 120 min. The observed results indicate that the decolorization of the MB followed a pseudo-first order kinetics. PMID:24434976

  12. 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.

  13. 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.

  14. 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.

  15. 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

  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. Generation and reactivity of putative support systems, Ce-Al neutral binary oxide nanoclusters: CO oxidation and C–H bond activation

    International Nuclear Information System (INIS)

    Both ceria (CeO2) and alumina (Al2O3) are very important catalyst support materials. Neutral binary oxide nanoclusters (NBONCs), CexAlyOz, are generated and detected in the gas phase and their reactivity with carbon monoxide (CO) and butane (C4H10) is studied. The very active species CeAlO4• can react with CO and butane via O atom transfer (OAT) and H atom transfer (HAT), respectively. Other CexAlyOz NBONCs do not show reactivities toward CO and C4H10. The structures, as well as the reactivities, of CexAlyOz NBONCs are studied theoretically employing density functional theory (DFT) calculations. The ground state CeAlO4• NBONC possesses a kite-shaped structure with an OtCeObObAlOt configuration (Ot, terminal oxygen; Ob, bridging oxygen). An unpaired electron is localized on the Ot atom of the AlOt moiety rather than the CeOt moiety: this Ot centered radical moiety plays a very important role for the reactivity of the CeAlO4• NBONC. The reactivities of Ce2O4, CeAlO4•, and Al2O4 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 CeAlO4• with C4H10 to form the CeAlO4H•C4H9• 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 AlxOy/MmOn or MmOn/AlxOy materials are proposed consistent with the presented experimental and theoretical results

  18. 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

  19. 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

  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. 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.

  2. 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 d...

  3. Estimation of bulk transfer coefficient for latent heat flux (Ce)

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.

    The bulk transfer coefficient for latent heat flux (Ce) has been estimated over the Arabian Sea from the moisture budget during the pre-monsoon season of 1988. The computations have been made over two regions (A: 0-8 degrees N: 60-68 degrees E: B: 0...

  4. 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...

  5. CeBIT为ICT发展奠定基石

    Institute of Scientific and Technical Information of China (English)

    电子贸促会

    2010-01-01

    @@ 德国当地时间3月6日.全球规模最大的ICT产业盛会-汉诺威消费电子、信息及通信博览会(CeBIT2010)在德国汉诺威博览中心正式落下帷幕.在此间举行的CeBIT闭幕新闻发布会上,主办方德国汉诺威展览公司董事局成员劳尔说:"本次展会的成功举办充分体现了CeBIT展所带来的行业影响力,并为未来几个月的商业发展奠定了稳固基石.为吸引新的目标群体以及巩固CeBIT的领导地位,下届展会将会更加强化各大展区主题."

  6. 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.

  7. 气凝胶骨架镶嵌的 CeO2 纳米团簇催化氧化 HCl 制 Cl2%CeO2 nanoclusters stabilized in aerogel matrix as catalysts for Cl2 production from HCl oxidation

    Institute of Scientific and Technical Information of China (English)

    徐希化; 费兆阳; 陈献; 汤吉海; 崔咪芬; 乔旭

    2015-01-01

    CeO2 nanoclusters inserted into aerogel matrix (CeO2@MxOy, MxOy= SiO2, ZrO2, Al2O3) prepared by a single-step sol-gel method were used as catalysts for recycling Cl2 from HCl oxidation. Due to their remarkable quantum-size effects, the properties of CeO2 nanoclusters were significantly different from crystal phase CeO2. The CeO2 nanoclusters could be completely reduced at the temperature range for reduction of the surface oxygen species of crystal phase CeO2. The unique properties of CeO2 nanoclusters resulted in the high activity of CeO2@MxOy in the process of HCl oxidation reaction. 40CeO2@SiO2 exhibited the highest activity and the STY (space time yield of Cl2) reached to 2.10 g·(g cat)?1·h?1 at 430℃ with VO2/VHCl of 1 and contact time of 0.1598 h. Kinetic studies showed that both O2 and HCl competed for the active sites rendering desorption of surface Cl as the rate-determining step.%采用一步溶胶-凝胶法制备了镶嵌于气凝胶骨架内的 CeO2 纳米团簇催化材料(CeO2@MxOy, MxOy= SiO2、ZrO2、Al2O3)用于 HCl 催化氧化反应.镶嵌于气凝胶骨架内的 CeO2 纳米团簇显著的量子尺寸效应导致其表现出不同于晶相 CeO2 的特性,H2-TPR 测试结果显示在晶相 CeO2 表面氧物种还原温区内 CeO2 纳米团簇即可被充分还原.优异的氧化还原性能导致 CeO2@MxOy 在 HCl 氧化过程具有良好的催化活性,其中,40CeO2@SiO2 的活性最高,在接触时间为 0.1598 h,VO2/VHCl 为 1,430℃时,Cl2 空时产率可以达到 2.10 g·(g cat)?1·h?1.催化剂表面的 HCl氧化反应同时受 O2 分压和 HCl 分压的影响,这表明 Cl2 从催化剂表面的脱附是该反应的决速步骤.

  8. New CeMgCo4 and Ce2MgCo9 compounds: Hydrogenation properties and crystal structure of hydrides

    Science.gov (United States)

    Denys, R. V.; Riabov, A. B.; Černý, R.; Koval'chuk, I. V.; Zavaliy, I. Yu.

    2012-03-01

    Two new ternary intermetallic compounds, CeMgCo4 (C15b pseudo-Laves phase, MgCu4Sn type) and Ce2MgCo9 (substitution derivative of PuNi3 type) were synthesized by mechanical alloying method. The structural and hydrogenation properties of these compounds were studied by X-ray diffraction and Pressure-Composition-Temperature measurements. Both compounds absorb hydrogen at room temperature and pressures below 10 MPa forming hydrides with maximum compositions CeMgCo4H6 and Ce2MgCo9H12. Single plateau behavior was observed in P-C isotherm during hydrogen absorption/desorption by Ce2MgCo9 alloy. The CeMgCo4-H2 system is characterized by the presence of two absorption/desorption plateaus corresponding to formation of β-CeMgCo4H4 and γ-CeMgCo4H6 hydride phases. The structure of β-hydride CeMgCo4H(D)4 was determined from X-ray and neutron powder diffraction data. In this structure initial cubic symmetry of CeMgCo4 is preserved and hydrogen atoms fill only one type of interstitial sites, triangular MgCo2 faces. These positions are occupied by 70% and form octahedron around Mg atom with Mg-D bond distances 1.84 Å.

  9. 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.

  10. Modification and aging precipitation behavior of hypereutectic Al-21wt.%Si alloy treated by P+Ce combination

    Directory of Open Access Journals (Sweden)

    Liu Pei

    2014-11-01

    Full Text Available In the present study, the tested hypereutectic Al-21wt.%Si alloys 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 alloy 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 alloy, 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 alloys under the heat treatment process. When Al-21wt.%Si alloy was modified using 0.08%wt.P + 0.6wt.% Ce, the aging precipitates were dispersed uniformly in the alloy, and its mechanical properties at room and elevated temperatures are optimized (Rm = 287.6 MPa at RT, Rm = 210 MPa at 300 ℃.

  11. Evidence for extreme floods in arid subtropical northwest Australia during the Little Ice Age chronozone (CE 1400-1850)

    Science.gov (United States)

    Rouillard, A.; Skrzypek, G.; Turney, C.; Dogramaci, S.; Hua, Q.; Zawadzki, A.; Reeves, J.; Greenwood, P.; O'Donnell, A. J.; Grierson, P. F.

    2016-07-01

    Here we report a ∼2000-year sediment sequence from the Fortescue Marsh (Martuyitha) in the eastern Pilbara region, which we have used to investigate changing hydroclimatic conditions in the arid subtropics of northwest Australia. The Pilbara is located at the intersection of the tropical Indian and Pacific Oceans and its modern rainfall regime is strongly influenced by tropical cyclones, the Intertropical Convergence Zone (ITCZ) and the Indo-Pacific Warm Pool. We identified four distinct periods within the record. The most recent period (P1: CE ∼1990-present) reveals hydroclimatic conditions over recent decades that are the most persistently wet of potentially the last ∼2000 years. During the previous centuries (P2: ∼CE 1600-1990), the Fortescue Marsh was overall drier but likely punctuated by a number of extreme floods, which are defined here as extraordinary, strongly episodic floods in drylands generated by rainfall events of high volume and intensity. The occurrence of extreme floods during this period, which encompasses the Little Ice Age (LIA; CE 1400-1850), is coherent with other southern tropical datasets along the ITCZ over the last 2000 years, suggesting synchronous hydroclimatic changes across the region. This extreme flood period was preceded by several hundred years (P3: ∼CE 700-1600) of less vigorous but more regular flows. The earliest period of the sediment record (P4: ∼CE 100-700) was the most arid, with sedimentary and preservation processes driven by prolonged drought. Our results highlight the importance of developing paleoclimate records from the tropical and sub-tropical arid zone, providing a long-term baseline of hydrological conditions in areas with limited historical observations.

  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. Effects of flue gas components on removal of elemental mercury over Ce-MnOx/Ti-PILCs.

    Science.gov (United States)

    He, Chuan; Shen, Boxiong; Li, Fukuan

    2016-03-01

    The adsorption and oxidation of elemental mercury (Hg(0)) under various flue gas components were investigated over a series of Ce-MnOx/Ti-PILC catalysts, which were synthesized by an impregnation method. To discuss the mechanism, the catalysts were characterized by various techniques such as N2 adsorption-desorption, scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) analysis and X-ray photoelectron spectroscopy (XPS). The results indicated that the presence of 500 ppm SO2 in the flue gas significantly restrained the Hg(0) adsorption and oxidation over 6%Ce-6%MnOx/Ti-PILC due to the formation of SO4(2-) species. Hg(0) could be oxidized to HgCl2 in the presence of HCl, because the Deacon process occurred. NO would react with active oxygen to form NO2-containing species, which facilitated Hg(0) oxidation. While the presence of NO limited the Hg(0) adsorption on 6%Ce-6%MnOx/Ti-PILC due to the competitive adsorption of NO with Hg(0). The addition of NH3 in the flue gas significantly restrained Hg(0) adsorption and oxidation, because the formed NH4(+) species covered the active adsorption sites on the surfaces, and further limited Hg(0) oxidation. However, when NO and NH3 were simultaneously added into the flue gas, the Hg(0) oxidation efficiency of 6%Ce-6%MnOx/Ti-PILC exhibited a relatively high value (72%) at 250°C, which indicated the practicability to use Ce-MnOx/Ti-PILC for Hg(0) removal under SCR conditions. PMID:26546699

  14. 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.

  15. 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...

  16. Magnetic properties of Ce3+ in PbCeA (A= Te, Se, S

    Directory of Open Access Journals (Sweden)

    Golacki Z.

    2013-01-01

    Full Text Available The magnetic susceptibility of Pb1-xCexA (A = S, Se and Te crystals with 0.006 ≤  x ≤ 0.036  were studied in the temperature range from 20 mK up to room temperature. X-band (~9.5 GHz Electron Paramagnetic Resonance (EPR showed small shifts in the effective Landé factors that were attributed to crystal-field admixture. The EPR measurements were correlated with the magnetic susceptibility data and resulted in estimating the crystal-field splitting Δ = E(Γ8 - E(Γ7 of the lowest 2F5/2 manifold for Ce3+ ions in PbA (A = S, Se and Te of about 340 K, 440 K and 540 K for Pb1-xCexTe, Pb1-xCexSe, and Pb1-xCexS, respectively. The values for the crystal-field splitting deduced from the magnetic data were found to be in agreement with the calculated ones based on the point charge model. Moreover, the deHaas van-Alphen magnetic oscillations in the susceptibility measurements of Pb1-xCexTe (x~ 0.05 and 0.07 were observed at ultra-low temperature (20 mK; The oscillations were investigated and the values of the oscillatory period for Pb1-xCexTe (x = 0.0048 and 0.007 are reported.

  17. 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.

  18. Electronic structure of CeO studied by a four-component relativistic configuration interaction method.

    Science.gov (United States)

    Moriyama, Hiroko; Tatewaki, Hiroshi; Yamamoto, Shigeyoshi

    2013-06-14

    We studied the ground and excited states of CeO using the restricted active space CI method in the energy range below 25,000 cm(-1). Energy levels are computed to within errors of 2700 cm(-1). Electron correlation effects arising from the ionic core composed of Ce5s, 5p, 4f(*), 5d(*), and O2s, 2p spinors play crucial role to CeO spectra, as well as correlation effects of electrons distributed in the valence Ce 4f, 5d, 6s, and 6p spinors. Here, 4f(*) and 5d(*) denote spinors expanded to describe electron polarization between Ce and O. A bonding mechanism is proposed for CeO. As the two separate atoms in their ground states, Ce(4f(1)5d(1)6s(2))(1)G4 and O(2s(2)2p(4))(3)P2, approach each other, a CeO(2+) core is formed by two-electron transfer from Ce5d, 6s to O2p. Inside this ellipsoidal ion, a valence bond between Ce5p and O2s and an ionic bond between O2p and Ce5p are formed with back-donation through Ce 4f(*) and 5d(*). PMID:23781798

  19. Hydrolysis Activities of Resins of Complexes Made from Polysaccharides and Ce4+

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Resins of complexes made from agarose-Ce4+ (RCA-Ce) and chitosan-Ce4+ (RCC-Ce) were prepared. Hydrolysis rates of methamidophos, omethoate and chlorpyrifos treated by RCA-Ce were 32.39%, 27.12% and 46.62%, respectively, those of chlorpyrifos and methamidophos in mung bean sprout juice 38.28% and 35.45%, and that of chlorpyrifos in tea extract 59.76%. Hydrolysis rates of protein in tea extract treated by RCA-Ce increased by 86.46%. RCC-Ce could be employed in the apple juice production. The contents of methamidophos and parathion-methyl in the juice treated by RCC-Ce decreased 58.76% and 71.92%. Furthermore, RCC-Ce was used to clarification for beer by the ways of a column. RCC-Ce could hydrolyze sensitive protein and increase contents of free amino acid in the beer. Therefore, the beer treated by RCC-Ce could stay oxidation and aging procedure due to some metal ions being absorbed by RCC-Ce.

  20. Effect of CeO2 Infiltration on Hybrid Direct Carbon Fuel Cell Performance

    DEFF Research Database (Denmark)

    Ippolito, Davide; Deleebeeck, Lisa; Kammer Hansen, Kent

    2014-01-01

    The effect of CeO2 infiltration into the anode or CeO2 mixed with the carbon-fuel on the performance of a Hybrid Direct Carbon Fuel Cell (HDCFC) was studied through the use of polarization curves and electrochemical impedance spectroscopy. The use CeO2 in both ways helped to increase the cell...

  1. Catalytic propane reforming mechanism over Mn-Doped CeO2 (111)

    Science.gov (United States)

    Krcha, Matthew D.; Janik, Michael J.

    2015-10-01

    MnOx/CeOx mixed oxide systems exhibit encouraging hydrocarbon oxidation activity, without the inclusion of a noble metal. Using density functional theory (DFT) methods, we examined the oxidative reforming path of propane over the Mn-doped CeO2 (1 1 1) surface. A plausible set of elementary reaction steps are identified for conversion of propane to CO/CO2 and H2/H2O over the oxide surface. The rate-limiting reaction process may vary with redox conditions, with C-H dissociation limiting under more oxidizing conditions and more complex reaction sequences, including surface re-oxidation, limiting under highly reducing conditions. The possibility of intermediate desorption from the surface during the reforming process is low, with desorption energies of the intermediates being much less favorable than further surface reactions until CO/CO2 products are formed. The reforming paths over Mn-doped ceria are similar to those previously identified over Zr-doped ceria. The extent of surface reduction and the electronic structure of the surface intermediates are examined.

  2. 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. PMID:26559160

  3. Enhanced reduction properties of mesostructured Ce{sub 0.5}Zr{sub 0.5}O{sub 2} solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang, Jing, E-mail: jingouyang@csu.edu.cn; Yang, Huaming, E-mail: hmyang@csu.edu.cn

    2013-06-15

    Mesostructured Ce{sub 0.5}Zr{sub 0.5}O{sub 2} solid solutions (M-CZ) were hydrothermally synthesized using Gemini surfactant as the template. X-ray diffraction (XRD), small-angle X-ray diffraction (SAXRD), N{sub 2} adsorption–desorption isotherms and high-resolution transmission electronic microscopy (HRTEM) were adopted to characterize the samples. The product had a surface area of 123.5 m{sup 2} g{sup −1} with maximum oxygen storage capacity (OSC) of 0.58 mol O{sub 2}/mol Ce. Oxygen anions in the M-CZ can be repeatedly released and resumed during the redox recycles. Reduction of Ce{sup 4+} to Ce{sup 3+} or lower valence and Zr{sup 4+} to Zr{sup 3+} were fulfilled with an obvious color change during the temperature programmed reduction (TPR) process, while the crystal structure of the product remained unchanged even after severe reduction. The mesostructure of the product can improve the reductive ability of Ce{sup 4+} and Zr{sup 4+} cations, which was beneficial to the enhancement of OSC. - Highlights: • Gemini was successfully used to synthesis mesoporous Ce{sub 0.5}Zr{sub 0.5}O{sub 2} materials. • A OSC up to 0.58 mol O{sub 2}/mol Ce was obtained without any structural changes. • Step by step redox circles in the sample were detected.

  4. Luminescence and multi-step energy transfer in GdAl{sub 3}(BO{sub 3}){sub 4} doped with Ce{sup 3+}/Tb{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    He, Jin; Shi, Rui [MOE Laboratory of Bioinorganic and Synthetic Chemistry, KLGHEI of Environment and Energy Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Brik, Mikhail G. [College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Institute of Physics, University of Tartu, Ravila 14C, Tartu 50411 (Estonia); Dorenbos, Pieter [Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Huang, Yan; Tao, Ye [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China); Liang, Hongbin, E-mail: cesbin@mail.sysu.edu.cn [MOE Laboratory of Bioinorganic and Synthetic Chemistry, KLGHEI of Environment and Energy Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2015-05-15

    Ce{sup 3+} and/or Tb{sup 3+} doped GdAl{sub 3}(BO{sub 3}){sub 4} phosphors were prepared via a high-temperature solid-state reaction method. The band gap of GdAl{sub 3}(BO{sub 3}){sub 4} is determined from the VUV excitation spectrum of a Ce{sup 3+} doped sample at 14 K and further confirmed by that of undoped and Tb{sup 3+} doped samples at RT. X-ray excited luminescence (XEL) of GdAl{sub 3}(BO{sub 3}){sub 4}: Ce{sup 3+} was measured. The main electron-vibrational interaction (EVI) parameters for Ce{sup 3+} in GdAl{sub 3}(BO{sub 3}){sub 4} were simulated. The vacuum referred binding energy (VRBE) scheme of lanthanide 4f/5d states in GdAl{sub 3}(BO{sub 3}){sub 4} was constructed. Using this scheme, the lowest 5d excitation band of Pr{sup 3+} in GdAl{sub 3}(BO{sub 3}){sub 4} was predicted, showing that the estimation is in agreement with the experimental result. The occurrence of multi-step energy transfer processes which include Gd{sup 3+}→Ce{sup 3+}, Gd{sup 3+}→Tb{sup 3+}, Ce{sup 3+}→Tb{sup 3+}, and Tb{sup 3+}→Gd{sup 3+}, Tb{sup 3+}→Ce{sup 3+} under different excitations was derived from excitation, emission, and fluorescence decay spectra. - Highlights: • The main EVI parameters for Ce{sup 3+} in GdAl{sub 3}(BO{sub 3}){sub 4} were simulated. • The VRBE scheme was constructed, thermal-quenching of Ce{sup 3+} luminescence was predicted. • Multi-step energy transfer processes occur under different excitations.

  5. 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

    if results on a several-fold activity increase of a series of Pt/rare-earth alloys hold also for Pd rare-earth alloys. Pd5Ce crystallizes in two phases, a so-called low-temperature phase, L-Pd5Ce, which has a cubic symmetry, and a high-temperature phase, H-Pd5Ce, with a hexagonal symmetry. In both cases...

  6. 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.

  7. 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...

  8. 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.

  9. Redox potentials and kinetics of the Ce 3+/Ce 4+ redox reaction and solubility of cerium sulfates in sulfuric acid solutions

    Science.gov (United States)

    Paulenova, A.; Creager, S. E.; Navratil, J. D.; Wei, Y.

    Experimental work was performed with the aim of evaluating the Ce 4+/Ce 3+ redox couple in sulfuric acid electrolyte for use in redox flow battery (RFB) technology. The solubility of cerium sulfates in 0.1-4.0 M sulfuric acid at 20-60 °C was studied. A synergistic effect of both sulfuric acid concentration and temperature on the solubility of cerous sulfate was observed. The solubility of cerous sulfate significantly decreased with rising concentration of sulfuric acid and rising temperature, while the solubility of ceric sulfate goes through a significant maximum at 40 °C. Redox potentials and the kinetics of the cerous/ceric redox reaction were also studied under the same temperature-concentration conditions. The redox potentials were measured using the combined redox electrode (Pt-Ag/AgCl) in equimolar Ce 4+/Ce 3+ solutions (i.e.[Ce 3+]=[Ce 4+]) in sulfuric acid electrolyte. The Ce 3+/Ce 4+ redox potentials significantly decrease (i.e. shift to more negative values) with rising sulfuric acid concentration; a small maximum is observed at 40 °C. Cyclic voltammetric experiments confirmed slow electrochemical kinetics of the Ce 3+/Ce 4+ redox reaction on carbon glassy electrodes (CGEs) in sulfuric acid solutions. The observed dependencies of solubilities, the redox potentials and the kinetics of Ce 3+/Ce 4+ redox reaction on sulfuric acid concentration are thought to be the result of inequivalent complexation of the two redox species by sulfate anions: the ceric ion is much more strongly bound to sulfate than is the cerous ion. The best temperature-concentration conditions for the RFB electrolytes appear to be 40 °C and 1 M sulfuric acid, where the relatively good solubility of both cerium species, the maximum of redox potentials, and the more or less satisfying stability of CGE s were found. Even so, the relatively low solubility of cerium salts in sulfuric acid media and slow redox kinetics of the Ce 3+/Ce 4+ redox reaction at carbon indicate that the Ce 3+/Ce

  10. Molecular magnetism and crystal field effects in the Kondo system Ce{sub 3}Pd{sub 20}(Si,Ge){sub 6} with two Ce sublattices

    Energy Technology Data Exchange (ETDEWEB)

    Nikiforov, V.N. [M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Koksharov, Yu.A. [M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Kurnakov Institute of General and Inorganic Chemistry, Leninskii pr. 31, Moscow 119991 (Russian Federation); Gribanov, A.V. [M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Baran, M. [Institute of Physics, Polish Academy of Science, Warsaw (Poland); Irkhin, V.Yu., E-mail: valentin.irkhin@imp.uran.ru [Institute of Metal Physics, Ekaterinburg 620990 (Russian Federation)

    2015-06-01

    The unusual electronic and magnetic properties of the systems Ce{sub 3}Pd{sub 20}T{sub 6} (T=Ge, Si) with two non-equivalent Ce positions are discussed. The logarithmic growth of resistance for both systems confirms the presence of the Kondo effect in the two respective temperature ranges. The two-scale behavior is explained by consecutive splitting of Ce ion levels in the crystal field. The effects of the frustration caused by the coexistence of the different Ce positions are treated, which may also significantly enhance the observed values of specific heat. A model of “molecular magnetism” with Ce2 cubes is developed. - Highlights: • We study unusual properties of the systems Ce{sub 3}Pd{sub 20}T{sub 6} with two Ce positions. • The logarithmic growth of resistance confirms presence of the Kondo effect. • The effects of the frustration owing to different Ce positions are discussed. • A model of “molecular magnetism” with Ce2 cubes is developed.

  11. 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.

  12. Tunable emission and the systematic study on energy-transfer properties of Ce{sup 3+}- and Tb{sup 3+}-co-doped Sr{sub 3}(PO{sub 4}){sub 2} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhijun [Guangzhou Maritime Institute, Department of Shipping Engineering, Guangzhou (China)

    2015-09-15

    An emitting color tunable phosphor Sr{sub 3}(PO{sub 4}){sub 2}:Ce{sup 3+}, Tb{sup 3+} was synthesized by the traditional high-temperature solid-state reaction method. The photoluminescence and energy-transfer (ET) properties of Ce{sup 3+}- and Tb{sup 3+}-doped Sr{sub 3}(PO{sub 4}){sub 2} host were studied in detail. The obtained phosphors show both a blue emission from Ce{sup 3+} and a yellowish green emission from Tb{sup 3+} with considerable intensity under ultraviolet (UV) excitation (∝311 nm). When the content of Ce{sup 3+} was fixed at 0.03, the emission chromaticity coordinates could be adjusted from blue to green region by tuning the contents of Tb{sup 3+} ions with the aid of ET process. The critical distance between Ce{sup 3+} and Tb{sup 3+} is 14.69 A. The ET mechanism from Ce{sup 3+} to Tb{sup 3+} ions was identified with dipole-dipole interaction. The obtained phosphor exhibits a strong excitation in UV spectral region and high-efficient ET from Ce{sup 3+} to Tb{sup 3+} ions. It may find applications as a green light-emitting UV-convertible phosphor in white LED devices. (orig.)

  13. 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...

  14. 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.

  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. The data distribution of the ESPaCE project

    Science.gov (United States)

    Thuillot, W.

    2015-10-01

    In the framework of the European Union project entitled ESPaCE (European Satellite Partnership for Computing Ephemerides, 2011-2015) we have carried out research by collecting unexploited space data and ground-based data for providing new dynamical orbit models and ephemeris of natural satellites and spacecraft orbits. Besides new digitization of old astrometric plate data, Radio Science, VLBI tracking, Laser Ranging methods are applied to these goals. Furthermore shape and gravity field data, reference systems are provided for several natural satellites. This project intends to put all this material online for free access by the scientific community. We will describe the data acquisition and distribution performed and in particular the setup of the ESPaCE-NSDB astrometric database.

  17. 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.

  18. Boèce, Traité de la musique

    OpenAIRE

    Lejbowicz, Max

    2008-01-01

    Le destin du De institutione musica de Boèce est étrange. Si l’on excepte une allusion purement rhétorique de son rival Cassiodore, trois siècles séparent la rédaction du texte de son premier témoin, sans que les spécialistes se soient accordés sur l’origine de l’archétype (voir, dans le livre sous examen, les p. 12-13). Mais, à partir de cette résurgence, quel succès ! Entre le VIIIe et le XVe s., ce sont près de cent soixante-dix manuscrits qu’il faut compter, tandis que la Renaissance l’éd...

  19. CeBIT:"数字"嘉年华

    Institute of Scientific and Technical Information of China (English)

    李璐

    2006-01-01

    @@ 随着全球ICT技术和产业迅猛发展,ICT市场持续稳定增长,全球规模最大的信息和通信技术盛会CeBIT(汉诺威信息及通信技术博览会)受到越来越多人的关注.2006年3月9~15日,CeBIT2006再次在德国汉诺威市隆重举行,展会全面展示整个信息及通信技术领域最新产品,也为知识转让和网络化提供了平台.

  20. 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.

  1. 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

  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. 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.

  4. 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.

  5. Synergetic migration behavior of La and Ce and related microstructure character of Cr-V-RE co-doped WC-Co alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li; TANG Wei; CHEN Shu; NAN Qing; XIE Mingwei

    2012-01-01

    The as-sintered sinter skin and the polished section of WC-11Co-0.4Cr3C2-0.3VC-0.2RE (RE =mischmetal with La/Ce ratio of 0.65)alloy were analyzed.It was shown that the microstructures on the skin and in the inner part of the alloy were all characterized with a WC+β+ M structure,where β was a cobalt-based binder phase and M represented a RE-containing phase.There existed an inward diffusion of S atoms,which caught and fixed the Ce atoms in the alloy and an outward diffusion of La atoms during the sintering process.Consequently,the M phase was characterized with the decreased La/Ce ratio (0.59) in the inner part and the increased La/Ce ratio (1.01) on the skin.The M phase on the skin was characterized with a γ-Ce2S3 type structure.To suppress the long range migration of rare earth to the skin,S in the sintering atmosphere had to be eliminated.

  6. 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.

  7. Effect of 10 MeV iodine ion irradiation on the magnetic properties and lattice structure of CeO2

    International Nuclear Information System (INIS)

    We have studied the magnetic properties and the lattice structure of pure CeO2 irradiated with swift heavy ions. Experimental results showed that the ferromagnetism was induced at room temperature by 10 MeV I ion irradiation. The value of saturation magnetization increases with increasing the ion fluence and reaches a maximum value at about the fluence of 1.2 × 1013/cm2, and then decreases. The X-ray diffraction (XRD) spectra showed that the lattice parameter of CeO2 increases with increasing ion fluence. To examine the origin of the ferromagnetic state in CeO2, we compared the result for 10 MeV I ion irradiation with that for 200 MeV Xe ion irradiation. We also estimated the magnetic properties for CeO2 pellets annealed at 1273 K in a vacuum. From the experimental results, we concluded that oxygen vacancies, which are produced by electronic excitation process due to high energy ion beam, play an important role in the appearance of the ferromagnetic state in CeO2. (author)

  8. Structure and oxygen storage capacity of Pd/Pr/CeO2-ZrO2 catalyst:effects of impregnated praseodymia

    Institute of Scientific and Technical Information of China (English)

    冉锐; 张宏伟; 吴晓东; 樊俊; 翁端

    2014-01-01

    Praseodymium (Pr) was impregnated to CeO2-ZrO2 solid solution by an impregnation method. The as-obtained Pr modi-fied CeO2-ZrO2 was impregnated with 1 wt.%Pd to prepare the catalysts. The structure and reducibility of the fresh and hydrother-mally aged catalysts were characterized by X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), CO chemi-sorption and H2 temperature-programmed reduction (H2-TPR). The oxygen storage capacity (OSC) was evaluated with CO serving as probe gas. Effects of impregnated Pr on the structure and oxygen storage capacity of catalysts were investigated. The results showed that the aged Pr-impregnated samples had much higher OSC and better reducibility than the unmodified ones. The scheme of structural evolutions of the catalysts with and without Pr was also established. Partial of the impregnated Pr diffused into the bulk of CeO2-ZrO2 during ageing, which inhibited the sintering, and increased the amount of oxygen vacancies in CeO2-ZrO2 support. Furthermore, those impregnated Pr species which covered on the surface of the support obstructed the strong metal-support interaction between Pd and Ce so as to reduce the encapsulation of Pd as well as the back spill-over of the oxygen during the catalytic process.

  9. Highly Active and Stable Pt-Loaded Ce0.75Zr0.25O2 Yolk-Shell Catalyst for Water-Gas Shift Reaction.

    Science.gov (United States)

    Shim, Jae-Oh; Hong, Young Jun; Na, Hyun-Suk; Jang, Won-Jun; Kang, Yun Chan; Roh, Hyun-Seog

    2016-07-13

    Multishelled, Pt-loaded Ce0.75Zr0.25O2 yolk-shell microspheres were prepared by a simple spray pyrolysis process for use in the water-gas shift (WGS) reaction. The Pt-loading was optimized, obtaining highly active Pt/Ce0.75Zr0.25O2 yolk-shell nanostructures for the WGS. Of the prepared catalysts, a 2% Pt loading of the Ce0.75Zr0.25O2 yolk-shell microspheres showed the highest CO conversion. The high catalytic activity of the 2% Pt/Ce0.75Zr0.2O2 catalyst was mainly due to its easier reducibility and the maintenance of active catalytic Pt species. The Pt-loaded Ce0.75Zr0.25O2 catalyst microspheres were highly resistant to Pt sintering because of their unique yolk-shell structure. Spray pyrolysis was found to be highly efficient for the production of precious-metal-loaded, multicomponent metal oxide yolk-shell microspheres for catalytic applications. PMID:27315135

  10. Saccharinato complexes of Ce(V) with 2-hydroxypyridine: Synthesis, spectroscopic and thermal characteristics of [Ce(sac) 2(SO 4)(H 2O) 4] and [Ce(sac) 2(SO 4)(PyOH) 2

    Science.gov (United States)

    Gaballa, Akmal S.; Teleb, Said M.; Müller, Thomas

    2008-10-01

    The synthesis of Ce(IV) complexes [Ce(sac) 2(SO 4)(H 2O) 4] ( 1) and [Ce(sac) 2 (SO 4)(PyOH) 2] ( 2) (sac = saccharinate, PyOH = 2-hydroxypyridine) starting with sodium saccharinate is described. Their vibrational and nuclear magnetic resonance ( 1H, 13C) spectra as well as their thermal mode of degradation were investigated. The data indicate that sac in complex 1 behaves as a monodentate ligand through the nitrogen atoms. Saccharinato ligand in complex 2 shows different mode of coordination, where it behaves as tridentate and binds Ce(IV) through its carbonylic oxygen, nitrogen and sulphonylic oxygen atoms. The most probable structure in complex 2 is that, units of [Ce(sac) 2(SO 4)(PyOH) 2] are linked by bridges of the O- of sac sulphonyl leading to polymeric chains.

  11. Role of Ce in Yb/Al laser fibers: prevention of photodarkening and thermal effects.

    Science.gov (United States)

    Jetschke, Sylvia; Unger, Sonja; Schwuchow, Anka; Leich, Martin; Jäger, Matthias

    2016-06-13

    We report on detailed investigations of ytterbium (Yb) and aluminum (Al) doped silica fiber and preform samples co-doped with cerium (Ce). The prevention of pump-induced photodarkening (PD) by temporary oxidation of Ce3+ to Ce4+ (or rather Ce3++) was proved by observed modifications in the ultraviolet (UV) spectra of transient absorption during near-infrared (NIR) pumping of thin preform slices. Only a small part of available Ce3+ ions (absorption spectra disappeared completely when the pump power was switched-off. From these observations we conclude that the recombination to Ce3+ takes place very fast thereby enabling these ions to capture liberated holes h+ perpetually during further pumping. We found a concentration ratio of Ce/Yb ≈0.5 to be sufficient to reduce PD loss to 10% in comparison to Ce-free fibers. Thus, the thermal load caused by absorption of PD color centers at pump (and laser) wavelength is expected to be also reduced. Unfortunately, new heat sources arise with the presence of Ce which cannot be explained by the absorption of Ce ions at the pump wavelength but must be attributed to the interaction with excited Yb ions. Fiber temperature increase of more than 200 K was observed if both, Yb2O3 and Ce2O3 concentration exceed 0.4 mol%. PMID:27410320

  12. 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.

  13. Tunable luminescence from Ce-doped aluminoborosilicate glasses

    Institute of Scientific and Technical Information of China (English)

    E Malchukova; B Boizot

    2014-01-01

    A series of aluminoborosilicate glasses were prepared using the melt-quenching technique for mixture of stoichiometric amounts of SiO2, Al2O3, H3BO3, Na2CO3, and ZrO2 with adding of different amounts of CeO2. The samples were investigated by means of luminescence spectroscopy. Tunable luminescence from violet to blue/green was observed from these glasses with different Xe-lamp excitation wavelengths ranging from 370 to 480 nm as well as with laser excitation of 266 and 355 nm. Moreover it was found that the possibility of tuning the light by changing of excitation wavelength was not unique. The same effect was observed by adjusting conditions for luminescence measurements as well as under exposure toβ-irradiation. The obtained phenomena could be explained taking into account structural characteristics of this glass and it could be concluded that tunable luminescence results from the presence of different Ce-sites the glass matrix. Thus the results suggest that Ce-doped glasses could be considered as conversion materials for blue light-emitting diode chips to generate white light-emitting diodes.

  14. Level structure studies in 140La and 140Ce

    International Nuclear Information System (INIS)

    Energy and relative intensity measurements with precision have been done in 140Li and 140Ce using 8 c.c. Ge(Li) detector. In addition, gamma-gamma directional correlation measurements were carried out for 537-(14)-30, 305-(133)-30 and 305-162 keV cascades in 140Ia and 329-487, 487-1596 and 329-487, 487-1596 and 329-(487)-1596 keV cascades in 140Ce. From the data, spin assignments 0- and 1- have been made to the 581 and 468 keV levels in 140La. Multipole admixtures in 30,305,162,329, and 487 keV gamma-rays have been found to be M1+(2.5 +-.5)%E2, M1+(94+-1)%E2, M+(1+-.5)%E2, E2+(2+-1)%M3 and M1+0.25%E2 respectively. A comparison of experimental transition probabilities with Weisskopf estimates describes low lying states of 140La as states in which f7sub(/)2 neutron is coupled to unpaired proton and these of 140Ce, as single particle states with some core contribution. (author)

  15. 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.

  16. 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.  ……

  17. 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...

  18. 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.

  19. Oxygen non-stoichiometries in (Th0.7Ce0.3)O2-x

    International Nuclear Information System (INIS)

    Oxygen non-stoichiometry in (Th0.7Ce0.3)O2-x oxide solid solutions was investigated from the viewpoint of Ce reduction. The oxygen non-stoichiometry was experimentally determined by means of thermogravimetric analysis as a function of oxygen potential at 1173, 1273 and 1373 K. Features of the isotherms of oxygen non-stoichiometry in (Th0.7Ce0.3)O2-x similar to those in oxygen non-stoichiometric actinide and lanthanide dioxides were observed. The oxygen non-stoichiometry in (Th0.7Ce0.3)O2-x was compared with those of CeO2-x and (U0.7Ce0.3)O2-x. It was concluded that the Ce reduction has some relation to defect forms and their transformations in the solid solutions.

  20. Electrorheological Performance of SiO2 Particle Materials of Ce-Doping and Adsorbed Chitosan

    Institute of Scientific and Technical Information of China (English)

    Li Shuxin; Ma Shuzhen; Xu Mingyuan; Shang Yanli; Li Junran; Zhang Shaohua; Zhang Yuanjing; Gao Song

    2004-01-01

    The electrorheological(ER) materials of pure SiO2 ( Sample 1 ), Ce-doping SiO2 ( Ce-SiO2, Sample 2) and Ce-SiO2 adsorbed chitosan (Ce-SiO2-chitosan, Sample 3 ) were prepared using Na2SiO3, Ce( NO3 )3 and chitosan as starting materials. Their ER properties were studied. The results show that Ce-doping can enhance the ER activity of SiO2, and the ER activity of SiO2 can be further improved by adsorbing chitosan on the surfaces of Ce-SiO2 particles.The ER activity of a particle material is correlated with the average grain size, surface area, pore volume and average pore size of the material.

  1. Isolation of several metastable phases in Ce-Gd-Zr-O system

    International Nuclear Information System (INIS)

    Cerium based zirconates pyrochlore; Ce2Zr2O7 attracts special attention due to potential catalytic application of CeO2-ZrO2 system in various chemical reactions. The mechanistic studies revealed that oxygen stoichiometry between CeO2 and Ce2O3 plays an important role in Ce2Zr2O7 for oxygen storage and release at relatively lower temperature by fluctuation of oxidation state of cerium. The crystal chemical properties of CeO2-ZrO2 system studied under different redox conditions indicate that the pyrochlore lattice can be maintained by a mild oxygen intercalation. The instability of the stoichiometric CeO2-ZrO2 system with pyrochlore structure imposes a major challenge on the synthetic methods. Several metastable phases have been isolated, for the first time, by adopting various modified reaction parameters

  2. 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...

  3. Structure and Dielectric Study of Ce3 NbO7+δ

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The structure, phase composition, and migration of oxygen ion in Ce3NbO7+δ were reported on the basis of lone-pair substitution concept.X-ray diffraction study revealed that Ce3NbO7+δ sample was comprised of Ce3NbO7+δ phase and CeNbO4.25 phase.In the dielectric study of Ce3NbO7+δ sample, two dielectric loss peaks were observed both in temperature spectra and frequency spectra.Both peaks were shifted towards higher temperature with increase in frequency in temperature spectra and towards higher frequency with increase in temperature in frequency spectra, indicating the relaxation essence of these two peaks.It was suggested that the short distance diffusions of oxygen ions in both Ce3NbO7+δ phase and CeNbO4.25 phase gave rise to the two dielectric relaxation peaks.

  4. 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.

  5. Blue-green-red luminescence from CeCl3- and MnCl2-doped hafnium oxide layers prepared by ultrasonic spray pyrolysis

    International Nuclear Information System (INIS)

    Hafnium oxide films doped with CeCl3 and/or MnCl2, and deposited at 300 deg. C by an ultrasonic spray pyrolysis process, were characterized using x-ray diffraction (XRD), energy-dispersive spectroscopy and photoluminescence. The XRD results revealed that the films are predominantly amorphous. The weak green-red emission of Mn2+ is enhanced through an efficient energy transfer from Ce3+ to Mn2+ ions. Spectroscopic data revealed that the energy transfer is nonradiative in nature and it could occur in Ce3+ and Mn2+ clusters through a short-range interaction mechanism. The efficiency of this transfer increases with the Mn2+ ion concentration, so that an efficiency of about 78% is attained for a 5 at.% of MnCl2 concentration, which makes these films interesting phosphors for the design of luminescent layers with blue, green and red emissions

  6. 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.

  7. Densification and Grain Growth during Early-stage Sintering of Ce0.9Gd0.1O1.95-δ in Reducing Atmosphere

    DEFF Research Database (Denmark)

    He, Zeming; Yuan, Hao; Glasscock, Julie;

    2010-01-01

    The present work investigates the processes of densification and grain growth of Ce0.9Gd0.1O1.95-δ (CGO10) during sintering in reducing atmosphere. Sintering variables were experimentally characterized and analyzed using defect chemistry and sintering constitutive laws. Based on the achieved...

  8. The influence of different salting-out agents on the extraction of Ce, Eu, Gd, Tb using tri-n-butyl phosphate

    International Nuclear Information System (INIS)

    The extraction enthalpies ΔH0 of Ce, Eu, Gd, Tb nitrates using TBP in the presence of different salting-out agents in aqueous phase were determined. It was established that the extraction process is the most exothermic in the case of LiNO3. (Author)

  9. Luminescence spectroscopy of the Gd-rich Ce3+-, Tb3+- and Mn2+-doped phosphate glasses

    International Nuclear Information System (INIS)

    Absorption, emission and excitation spectra and luminescence decay kinetics of Na(K)GdCe, NaGdTb and NaGdMn phosphate glasses and their dependence on the temperature (in the 1.7-300 K range) and on the glass composition have been studied. The processes of energy migration through the Gd3+ ions and following energy transfer in Gd3+-impurity pairs have been compared for the three types of the glasses studied. It has been suggested that the Gd3+ →Tb3+ energy transfer occurs only in the closest pairs through a very short-range exchange interaction, while the Gd3+ →Ce3+ and Gd3+ →Mn2+ energy transfer is possible also in more separated pairs mainly due to the longer-range multipolar Gd3+-impurity interaction. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  10. The improvement of corrosion resistance of Ce conversion films on aluminum alloy by phosphate post-treatment

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Haibing [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zuo Yu [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)], E-mail: zuoy@mail.buct.edu.cn

    2008-06-15

    A phosphate post-treatment process for Ce conversion film on aluminum was studied. SEM (scanning electronic microscope), XPS (X-ray photoelectron spectroscopy) and electrochemical measurements were used to characterize the properties of the films. After the post-treatment the micro-cracks on the film surface obviously diminished, and corrosion resistance of the conversion film in NaCl solution increased. The conversion film, without post-treatment, was mainly composed of hydrated cerium oxides, and the dehydration of the film may cause cracking of the films. After phosphate treatment, stable cerium phosphate CePO{sub 4} was formed on the surface, and the content of crystal water decreased greatly, leading to improvement of the film performance with less micro-cracks.

  11. New CeMgCo{sub 4} and Ce{sub 2}MgCo{sub 9} compounds: Hydrogenation properties and crystal structure of hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Denys, R.V.; Riabov, A.B. [Karpenko Physico-Mechanical Institute NAS Ukraine, 5, Naukova Street, Lviv, 79000 (Ukraine); Cerny, R., E-mail: alexr@ipm.lviv.ua [Laboratory of Crystallography, University of Geneva, 24, Quai Ansermet, Geneva (Switzerland); Koval' chuk, I.V.; Zavaliy, I.Yu. [Karpenko Physico-Mechanical Institute NAS Ukraine, 5, Naukova Street, Lviv, 79000 (Ukraine)

    2012-03-15

    Two new ternary intermetallic compounds, CeMgCo{sub 4} (C15b pseudo-Laves phase, MgCu{sub 4}Sn type) and Ce{sub 2}MgCo{sub 9} (substitution derivative of PuNi{sub 3} type) were synthesized by mechanical alloying method. The structural and hydrogenation properties of these compounds were studied by X-ray diffraction and Pressure-Composition-Temperature measurements. Both compounds absorb hydrogen at room temperature and pressures below 10 MPa forming hydrides with maximum compositions CeMgCo{sub 4}H{sub 6} and Ce{sub 2}MgCo{sub 9}H{sub 12}. Single plateau behavior was observed in P-C isotherm during hydrogen absorption/desorption by Ce{sub 2}MgCo{sub 9} alloy. The CeMgCo{sub 4}-H{sub 2} system is characterized by the presence of two absorption/desorption plateaus corresponding to formation of {beta}-CeMgCo{sub 4}H{sub 4} and {gamma}-CeMgCo{sub 4}H{sub 6} hydride phases. The structure of {beta}-hydride CeMgCo{sub 4}H(D){sub 4} was determined from X-ray and neutron powder diffraction data. In this structure initial cubic symmetry of CeMgCo{sub 4} is preserved and hydrogen atoms fill only one type of interstitial sites, triangular MgCo{sub 2} faces. These positions are occupied by 70% and form octahedron around Mg atom with Mg-D bond distances 1.84 A. - Graphical abstract: Crystal structure of the {beta}-CeMgCo{sub 4}D{sub 4.2} deuteride. Octahedra of D-sites around Mg atoms are shown. Highlights: Black-Right-Pointing-Pointer Two new ternary compounds have been synthesized in the Ce-Mg-Co system. Black-Right-Pointing-Pointer Below 100 bar H{sub 2} CeMgCo{sub 4} and Ce{sub 2}MgCo{sub 9} reversibly absorb hydrogen at room temperature. Black-Right-Pointing-Pointer Crystal structure of cubic CeMgCo{sub 4}D{sub 4.2} deuteride has been determined.

  12. Preparation and thermochromic properties of Ce-doped VO{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Song, Linwei [College of Materials Science and Engineering, Sichuan University, Chengdu 610064 (China); Zhang, Yubo [College of Materials Science and Engineering, Sichuan University, Chengdu 610064 (China); Sichuan Engineering Technical College, Deyang 618000 (China); Huang, Wanxia, E-mail: huangwanxiascu@yahoo.com.cn [College of Materials Science and Engineering, Sichuan University, Chengdu 610064 (China); Shi, Qiwu; Li, Danxia; Zhang, Yang; Xu, Yuanjie [College of Materials Science and Engineering, Sichuan University, Chengdu 610064 (China)

    2013-06-01

    Graphical abstract: This effect of doping concentration on the phase transition temperature of VO{sub 2} films demonstrates that the phase transition temperature is decreasing along with the increase of the Ce dopant concentrations. After doping Ce, the transition temperature of VO{sub 2} film changes appreciably. Highlights: ► Ce-doped VO{sub 2} films were prepared on muscovite substrate by inorganic sol–gel method for the first time. ► The cerium existing in the VO{sub 2} films in the form of Ce{sup 4+} and Ce{sup 3+} was substituted for part of V atoms in the lattice. ► Ce doping could remarkably reduce the particle size of the Ce-doped films compared with undoped films. ► The phase transition temperature of Ce-doped VO{sub 2} films decreased appreciably with maintaining high-quality phase transition. - Abstract: Mixture of cerium (III) nitrate hexahydrate and vanadium pentaoxide powder were used as precursor to prepare Ce-doped VO{sub 2} films on the muscovite substrate by inorganic sol–gel method. SEM, XRD and XPS were used to investigate the morphologies and structures of VO{sub 2} films. The results show that the VO{sub 2} films grow on the muscovite substrate with preferred orientated (0 1 1) plane and the Ce exists in the form of Ce{sup 4+} and Ce{sup 3+} replacing part of V atoms in the lattice. The infrared transmittance change was measured from room temperature to the temperature above the metal–insulator transition. The films have excellent thermochromic performance. The metal–insulator transition temperature of VO{sub 2} films changes appreciably with Ce doped, which decreases by 4.5 °C per 1 at.% doping. Furthermore, Ce doping could remarkably reduce the particle size of VO{sub 2} films.

  13. Effects of Ce additions on the age hardening response of Mg–Zn alloys

    International Nuclear Information System (INIS)

    The effects of Ce additions on the precipitation hardening behaviour of Mg–Zn are examined for a series of alloys, with Ce additions at both alloying and microalloying levels. The alloys are artificially aged, and studied using hardness measurement and X-ray diffraction, as well as optical and transmission electron microscopy. It is found that the age-hardening effect is driven by the formation of fine precipitates, the number density of which is related to the Zn content of the alloy. Conversely, the Ce content is found to slightly reduce hardening. When the alloy content of Ce is high, large secondary phase particles containing both Ce and Zn are present, and remain stable during solutionizing. These particles effectively reduce the amount of Zn available as solute for precipitation, and thereby reduce hardening. Combining hardness results with thermodynamic analysis of alloy solute levels also suggests that Ce can have a negative effect on hardening when present as solutes at the onset of ageing. This effect is confirmed by designing a pre-ageing heat treatment to preferentially remove Ce solutes, which is found to restore the hardening capability of an Mg–Zn–Ce alloy to the level of the Ce-free alloy. - Highlights: • The effects of Ce additions on precipitation in Mg–Zn alloys are examined. • Additions of Ce to Mg–Zn slightly reduce the age-hardening response. • Ce-rich secondary phase particles deplete the matrix of Zn solute. • Hardening is also decreased when Ce is present in solution. • Pre-ageing to preferentially precipitate out Ce restores hardening capabilities

  14. Orbit Determination for CE-2 Libration Flight and Asteroid Exploration Trial

    Science.gov (United States)

    Cao, J. F.

    2016-01-01

    Setting within the context of the flight trial of CE-2 (Chang'e 2) around the Sun-terrestrial libration point, the asteroid exploration as well as the YH-1 Mars exploration mission, this paper conducted various related studies on orbit determination techniques for deep space exploration. The research results provided high-precision orbit support for the successful photographing of the Toutatis. This paper also carried out preliminary orbit determination studies on YH-1 mission. Although the study findings can not be used directly in the Mars exploration mission, they can still be useful for the future explorations. This thesis is composed of the following five aspects. (1)Reviewed the statistical orbit determination theory, and gave a description of the spatiotemporal frame of reference, dynamical model issues, methods of estimation, perturbation analysis theory, as well as the algorithms for considering covariance analysis. (2)Developed the observational model for the deep space exploration. Based on theoretical analysis, the models of ranging, ranging rate, and VLBI (Very Long Baseline Interferometry) are derived. During the modeling process, the algorithm is optimized to improve the computational efficiency without deteriorating the accuracy. In addition, with the spin-stabilized characteristic of CE-2 in its cruise phase taken into consideration, a spin stabilization correction model of the tracking data is constructed, which not only meets the requirement of data correction, but also can estimate the alignment of antenna. (3)Carried out a study on the selection of integration center for CE-2 libration flight trial. The result shows that the Earth is most suitable for orbital prediction. A precise satellite ephemeris for CE-2's flight trial is provided. The transformation relation between the spatial-fixed coordinate system and the rotation coordinate system is constructed. An orbital accuracy of 2--10 km in the whole flight process and 5 km for the stable

  15. 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.

  16. TEM investigation of irradiation damage in single crystal CeO2

    International Nuclear Information System (INIS)

    In order to understand the evolution of radiation damage in oxide nuclear fuel, 150-1000 keV Kr ions were implanted into single crystal CeO2, as a simulation of fluorite ceramic UO2, while in situ transmission electron microscopy (TEM) observations were carried out. Two characteristic defect structures were investigated: dislocation/dislocation loops and nano-size gas bubbles. The growth behavior of defect clusters induced by 1 MeV Kr ions up to doses of 5 x 1015 ions/cm2 were followed at 600 deg. C and 800 deg. C. TEM micrographs clearly show the development of defect structures: nucleation of dislocation loops, transformation to extended dislocation lines, and the formation of tangled dislocation networks. The difference in dislocation growth rates at 600 deg. C and 800 deg. C revealed the important role which Ce-vacancies play in the loop formation process. Bubble formation, studied through 150 keV Kr implantations at room temperature and 600 deg. C, might be influenced by either the mobility of metal-vacancies correlated with at threshold temperature or the limitation of gas solubility as a function of temperature.

  17. 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  |

  18. 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.

  19. CE Marking of Structural Timber: the European Standardization Framework and its Effects on Italian Manufacturers

    Directory of Open Access Journals (Sweden)

    Francesco Negro

    2013-03-01

    Full Text Available Structural timber has been used for centuries in construction and represents a traditional building component in many countries of the European Union. Nowadays, the interest in its use has been renewed due to several factors such as: ease of processing, relative lightness, mechanical performance, sustainability and decorative appearance. On March 2011, the European Parliament adopted the Regulation (EU No. 305/2011 (known as CPR, laying down harmonized conditions for the marketing of construction products. According to CPR’s dispositions, since January 1st 2012 CE marking of structural solid timber has been mandatory. While on one hand for the building sector enterprises this implies remarkable challenges, on the other hand it will allow a better valorisation of structural timber. In this context, the present work illustrates the European standardization framework for CE marking of structural timber, particularly with respect to the visual grading method applicable to solid wood products and to the Italian experience in adopting the new rules.

  20. Synthesis and characterization of thermoluminescent glass-ceramics Li{sub 2}O-Al{sub 2}O{sub 3}-SiO{sub 2}:CeO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, Omar. D., E-mail: omargutierrez@itm.edu.c [Grupo Mytec, Instituto Tecnologico Metropolitano, Calle 73 No 76A-354 Via al Volador, Medellin (Colombia); Osorio, Edison [Grupo de Quimica-Fisica Teorica, Instituto de Quimica, Universidad de Antioquia, A A. 1226, Medellin (Colombia); Departamento de Ciencias Quimicas, Universidad Andres Bello, Av. Republica 275, Santiago (Chile); Paucar, Carlos. G. [Grupo de Ceramicos y Vitreos, Facultad de Ciencias, Universidad Nacional de Colombia, A A. 568, Medellin (Colombia); Cogollo, Rafael [Grupo de Materiales y Fisica Aplicada, Universidad de Cordoba, Codigo Postal 354, Monteria (Colombia); Hadad, C.Z. [Grupo de Quimica-Fisica Teorica, Instituto de Quimica, Universidad de Antioquia, A A. 1226, Medellin (Colombia)

    2009-08-15

    Vitroceramic powders of Li{sub 2}O-Al{sub 2}O{sub 3}-SiO{sub 2} systems (LAS), doped with 1% (LAS:1Ce) and 10% (LAS:10Ce) molar of cerianite (CeO{sub 2}) were synthesized by means of the gelification technique of metal formates of aluminum and lithium, in the presence of tetraethoxy silane and CeO{sub 2}. The gels obtained were dried (120 deg. C, 2.5 h), calcined (480 deg. C, 5 h) and sinterized (1250 deg. C, 30 min). The sinterized samples were characterized by X-ray difraction (XRD), scanning electron microscopy (SEM) and microchemical analysis (EDS). There is evidence for a mixture of two phases of 64% beta-spodumene (Li{sub 2}O-Al{sub 2}O{sub 3}-4SiO{sub 2}) and 36% beta-eucryptite (Li{sub 2}O-Al{sub 2}O{sub 3}-2SiO{sub 2}). The LAS:1Ce system was enriched in aluminum, the LAS:10Ce system showed areas of heterogeneous composition; some regions with a shortage of CeO{sub 2}, while others zones with cerium cumulus. From the microscopy images it was found that CeO{sub 2} acts as a densificant agent in LAS system, favoring the sintering in the host. The chemical route and the sintering processes utilized allow the production of samples exhibiting an acceptable linear correlation between total thermoluminescent emission intensity and the irradiation dose when the CeO{sub 2} concentration is low (less than 1%), opening the possibility of using this kind of glass-ceramic in dosimetry.

  1. 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.

  2. Impression and Charm of CeBIT 2005%2005年CeBIT印象与魅力

    Institute of Scientific and Technical Information of China (English)

    何发; 雨霞

    2005-01-01

    2005年3月10日,一年一度的德国CeBIT大展再次拉开全球IT产品盛会的序幕。作为行业的晴雨表,CeBIT总能搅动着IT行业的激情,牵动着ICT市场的神经。作为全球顶级IT盛会的CeBIT在组织者的有产管理下,历久弥新,以其宏大的规模和合理的会场安排,奉献给业界一道德式大餐。琳琅满目的参展产品从MP3、DV到大型计算机,解决方案应有尽有,新产品、新技术、新方案层出不穷,行业的权威企业悉数到场。

  3. Scintillation response of YAlO3:Ce and Lu0.7Y0.3AlO3:Ce single crystal scintillators

    Science.gov (United States)

    Phunpueok, A.; Chewpraditkul, W.; Limsuwan, P.; Wanarak, C.

    2012-09-01

    The scintillation response of YAlO3:Ce (YAP:Ce) and Lu0.7Y0.3AlO3:Ce (LuYAP:Ce) crystals with same size of 10 × 10 × 5 mm3 were studied for gamma ray energies ranging from 22.1 to 1274.5 keV. The light yield, its non-proportionality and the energy resolution were measured with the photomultiplier tube (PMT). The intrinsic resolution of the crystals versus energy of gamma rays has been determined after correcting the measured energy resolution for photomultiplier tube statistics. For 662 keV gamma rays (137Cs source), the YAP:Ce showed the light yield of 32,000 ph/MeV,which is much higher than that of 9800 ph/MeV obtained for LuYAP:Ce. The energy resolution of 4.4% obtained for YAP:Ce is much better than that of 7.9% obtained for LuYAP:Ce, due to its much higher light yield and better intrinsic resolution. The scintillation light loss of tested crystals at 511 keV gamma rays (22Na source) was also presented. The estimated photofraction was determined for both crystals and compared with the cross-sections ratio calculated using WinXCom program. The experimental results of the total mass attenuation coefficients for both crystals are in good agreement with the theoretical values, within the experimental uncertainty.

  4. 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)

  5. Temperature-dependent nonradiative energy transfer from Gd{sup 3+} to Ce{sup 3+} ions in co-doped LuAG:Ce,Gd garnet scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Onderisinova, Z. [Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic); Kucera, M., E-mail: kucera@karlov.mff.cuni.cz [Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic); Hanus, M. [Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic); Nikl, M. [Institute of Physics, AS CR, Cukrovarnicka 10, 162 00 Prague 6 (Czech Republic)

    2015-11-15

    Energy transfer from donor Gd{sup 3+} to acceptor Ce{sup 3+} ions was studied in low doped lutetium aluminum garnet, LuAG:Ce,Gd. High purity single crystalline films were prepared by liquid phase epitaxy. The mechanism of nonradiative energy transfer from {sup 6}P{sub J} (Gd{sup 3+}) multiplet to crystal field split 5d{sub 2} ({sup 2}D) states of Ce{sup 3+} was established as long-range dipole–dipole interaction and the average critical transfer distance between Gd{sup 3+} and Ce{sup 3+} ions was found ~14 Å at room temperature. It is shown that the single step energy transfer between donor–acceptor pairs is dominant while migration of excitation energy within the donor Gd{sup 3+} subsystem is only a small perturbation in the energy transfer mechanism in the studied low doped garnets. - Highlights: • Photoluminescence and decay kinetics in co-doped LuAG:Ce,Gd garnets. • Energy transfer from Gd{sup 3+} to Ce{sup 3+} in LuAG:Ce,Gd garnets. • Ce doped multicomponent garnet scintillators.

  6. 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%.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Low-frequency dielectric spectroscopy of BaTiO3:Ce3+ ceramics

    Science.gov (United States)

    Berbecaru, Ciceron

    2015-10-01

    Dielectric spectroscopy of BaTiO3 (BT) doped with Ce3+ (BT:Ce3+) ceramics was performed at extended temperatures and in the low-frequency ranges. BT:Ce3+ displays decreasing values of all phase transition temperatures with increasing Ce3+ content. Permittivity versus temperature plots showed decreasing values with increasing frequency with low dispersion and shifting values of the Curie temperatures (Tc) towards high frequencies. Comparable values of losses for BT and BT:Ce3+ ceramics suggest good charge compensation. At low frequencies and higher temperatures, thermally activated mechanisms of conduction increase the loss values. With increasing frequency, the BT:Ce3+ system displays increased and shifted loss peaks up to Tc and decreasing values above Tc. The characteristic exponent of the modified Curie-Weiss law is higher than one. These figures suggest a relaxor-like behaviour of BT:Ce3+ ceramics for low Ce3+ content. Phase diagrams of BT:Ce3+ ceramics show a strong decrease of Tc for low Ce3+ content.

  15. 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 ...

  16. 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.

  17. 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

    2016-01-01

    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. PMID:27457408

  18. 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

    2016-01-01

    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 Ce3+ state in the composition range of x > 0.3, owing to the co-doping of large radius La3+ 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. PMID:27457408

  19. 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.

  20. 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%.

  1. Effect of yttrium addition on water-gas shift reaction over CuO/CeO2 catalysts

    Institute of Scientific and Technical Information of China (English)

    SHE Yusheng; LI Lei; ZHAN Yingying; LIN Xingyi; ZHENG Qi; WEI Kemei

    2009-01-01

    This paper presented a study on the role of yttrium addition to CuO/CeO2 catalyst for water-gas shift reaction. A single-step co-precipitation method was used for preparation of a series of yttrium doped CuO/CeO2 catalysts with yttrium content in the range of 0-5wt.%. Properties of the obtained samples were characterized and analyzed by X-ray diffraction (XRD), Raman spectroscopy, H2-TPR, cyclic voltammetry (CV) and the BET method. The results revealed that catalytic activity was increased with the yttrium content at first, but then decreased with the further increase of yttrium content. Herein, CuO/CeO2 catalyst doped with 2wt.% of yttrium showed the highest catalytic activity (CO conversion reaches 93.4% at 250℃) and thermal stability for WGS reaction. The catalytic activity was correlated with the surface area, the area of peak y of H2-TPR profile (I.e., the reduction of surface copper oxide (crystalline forms) interacted with surface oxygen vacancies on ceria), and the area of peak C2 and A1 (Cu0→Cu2+ in cyclic voltammetry process), respectively. Besides, Raman spectra provided evidences for a synergistic Cu-Ovacancy interaction, and it was indicated that doping yttrium may facilitate the formation of oxygen vacancies on ceria.

  2. Luminescence properties of Ce3+ and Tb3+ co-activated ZnAl2O4 phosphor

    Science.gov (United States)

    Tshabalala, K. G.; Cho, S.-H.; Park, J.-K.; Pitale, Shreyas S.; Nagpure, I. M.; Kroon, R. E.; Swart, H. C.; Ntwaeaborwa, O. M.

    2012-05-01

    In this study, a solution combustion method was used to prepare green emitting Ce3+-Tb3+ co-activated ZnAl2O4 phosphor. The samples were annealed at 700 °C in air or hydrogen atmosphere to improve their crystallinity and optical properties. X-ray diffraction study confirmed that both as-prepared and post-preparation annealed samples crystallized in the well known cubic spinel structure of ZnAl2O4. An agglomeration of irregular platelet-like particles whose surfaces were encrusted with smaller spheroidal particles was confirmed by scanning electron microscopy (SEM). The fluorescence data collected from the annealed samples with different concentrations of Ce3+ and Tb3+ show the enhanced green emission at 543 nm associated with 5D4→7F5 transitions of Tb3+. The enhancement was attributed to energy transfer from Ce3+ to Tb3+. Possible mechanism of energy transfer via a down conversion process is discussed. Furthermore, cathodoluminescence (CL) intensity degradation of this phosphor was also investigated and the degradation data suggest that the material was chemically stable and the CL intensity was also stable after 10 h of irradiation by a beam of high energy electrons.

  3. Luminescence properties of Ce3+ and Tb3+ co-activated ZnAl2O4 phosphor

    International Nuclear Information System (INIS)

    In this study, a solution combustion method was used to prepare green emitting Ce3+–Tb3+ co-activated ZnAl2O4 phosphor. The samples were annealed at 700 °C in air or hydrogen atmosphere to improve their crystallinity and optical properties. X-ray diffraction study confirmed that both as-prepared and post-preparation annealed samples crystallized in the well known cubic spinel structure of ZnAl2O4. An agglomeration of irregular platelet-like particles whose surfaces were encrusted with smaller spheroidal particles was confirmed by scanning electron microscopy (SEM). The fluorescence data collected from the annealed samples with different concentrations of Ce3+ and Tb3+ show the enhanced green emission at 543 nm associated with 5D4→7F5 transitions of Tb3+. The enhancement was attributed to energy transfer from Ce3+ to Tb3+. Possible mechanism of energy transfer via a down conversion process is discussed. Furthermore, cathodoluminescence (CL) intensity degradation of this phosphor was also investigated and the degradation data suggest that the material was chemically stable and the CL intensity was also stable after 10 h of irradiation by a beam of high energy electrons.

  4. 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 tensile fractured surface indicate that the density and size of ductile dimples rise with accumulative strain increasing. The mechanism of microstructural evolution and the relationship between microstructure and mechanical property of Mg-Mn-Ce magnesium alloy processed by this solid die were also analyzed.

  5. 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.

  6. Characterization of Ce SUP 3+-tributyl phosphate coordination complexes produced by fused droplet electrospray ionization with a target capillary

    Energy Technology Data Exchange (ETDEWEB)

    Gary S. Groenewold; Jean-Jacques Gaumet

    2011-12-01

    Coordination complexes containing Ce(III) and tri-n-butyl phosphate (TBP) in the 1+, 2+ and 3+ charge states were generated using desorption electrospray ionization (DESI) mass spectrometry, in which the analyte solutions were supplied via a target capillary orthogonally situated with respect to the electrospray. Comparison with direct electrospray (ESI) showed that the same coordination complexes were produced in each experiment, and could be described by the general formula [Ce(NO3)m=0-2(TBP)n](3-m)+. This result indicates that DESI has utility for measuring metal speciation for metal ligand solutions where the gas-phase complexes generated by ESI have been correlated with solution speciation. Such an application would be useful for analyses where it is desirable to limit the total amount of metal being handled, or that have solvent systems that are not readily amenable to ESI. Both the direct ESI and DESI mass spectra showed similar trends with respect to the TBP:Ce ratio, viz. high values tend to favor formation of a larger fraction of the 1+ species, and the 2+ and 3+ species become relatively more important as the ratio is decreased. Within individual charge state ion envelopes, lower TBP:Ce ratios produce coordination complexes with fewer ligands, a trend also seen using both approaches. These trends again point toward strong similarity between the direct ESI and DESI analyses of the metal-ligand solutions. The DESI experiments were less sensitive for measuring the coordination complexes compared to the direct ESI experiments, by a factor of 10 - 100 depending on whether minimum detectable concentration or absolute ion abundances were considered. Nevertheless, mid-picomolar quantities of coordination complexes were measured using the target capillary, indicating that sensitivity would be sufficient for measuring species in many industrial separations processes.

  7. A facile synthesis and photoluminescence properties of water-dispersible Re3+ doped CeF3 nanocrystals and solid nanocomposites with polymers.

    Science.gov (United States)

    Li, Chunguang; Li, Feifei; Li, Tao; Bai, Tianyu; Wang, Long; Shi, Zhan; Feng, Shouhua

    2012-04-28

    Water-dispersible Re(3+) doped CeF(3) colloidal nanocrystals with well controllable morphology and high crystallinity have been successfully synthesized through a solvothermal process. The TEM images illustrate that the Re(3+) doped CeF(3) nanocrystals are rectangular (or cubic) with a mean diameter of ~10 nm. The excellent dispersibility in some of the polar solvents including water is achieved by using polyethyleneimine as the capping agent. The amine groups of the polymer chains on one hand bind to the nanocrystal surface; on the other hand the free ones could link to functional materials including bio-molecules. The CeF(3) nanocrystals doped with Tb(3+) and Dy(3+) ions show the characteristic emission of Tb(3+ 5)D(4)-(7)F(J) (J = 6-3, with (5)D(4)-(7)F(5) green emission at 542 nm as the strongest one) and Dy(3+ 4)F(9/2)-(6)H(15/2) (blue-green color at 478 nm) and (4)F(9/2)-(6)H(13/2) (yellow color at 571 nm) transitions, respectively. The energy transfer from Ce(3+) to Tb(3+) and Dy(3+) was also investigated in detail. In vitro studies of Re(3+) doped CeF(3) colloidal nanocrystals on HepG2 cells confirm their excellent biological compatibility. The obtained solid CeF(3) : Tb(3+)/PDMS nanocomposites are very stable and flexible and exhibit strong green photoluminescence upon UV excitation. PMID:22398580

  8. Influence of Different Subsistence States of CeO2-ZrO2 Mixed Oxides in Catalyst Coating on Catalytic Properties

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The metallic substrate-catalysts with different subsistence states of CeO2-ZrO2 mixed oxides were prepared and the catalytic properties were investigated. The studies on CeO2-ZrO2-V2O5-CuO mixed oxides which were prepared by coprecipitation, show that the doping of V5+ and Cu2+ in CeO2-ZrO2 mixed oxides can enhance the catalytic activity and thermal stability of coating materials. Moreover, different additives were doped in slurries of γ-Al2O3 to investigate the influence of additives on oxidation activity of catalysts. The mixture of ceria-zirconia, alkali metals and other rare earths acting as additives exhibits promotion effect on oxidation activity by optimizing the distribution of oxygen on the surface and in the bulk of ceria species. This mentioned mixture was mixed with γ-Al2O3 and a newly proposed active component to prepare a new catalyst. Afterward, the influence of thermal treatment on the new catalyst were investigated by calcinations at 500, 650, 750, 800, 850 and 900 ℃ for 2 h. The light-off curves of CO and HC show that after being treated at 650~750 ℃, catalysts present the best activity. XRD patterns show that ceria and zirconia species in the newly proposed active component form a phase of extra CeO2-ZrO2 mixed oxides on the surface of catalysts after the thermal treatment at 750 ℃, which has practical value for improving the preparation process and promoting the catalytic properties. Moreover, XPS results imply the existence of Ce1-xPdxO2-σ and Ce1-xPtxO2-σ on the surface of these treated samples, which may show influence on the catalytic activities.

  9. Luminescence properties and energy transfer investigations of Zn{sub 2}P{sub 2}O{sub 7}: Ce{sup 3+}, Tb{sup 3+} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Mengjiao; Wang, Luxiang; Jia, Dianzeng, E-mail: jdz@xju.edu.cn; Le, Fuhe

    2015-02-15

    A novel green light emitting phosphor Zn{sub 2}P{sub 2}O{sub 7}: Ce{sup 3+}, Tb{sup 3+} was synthesized by the traditional solid state reaction method at 850 °C. The crystal structure, photoluminescence properties, thermal stability and luminous efficiency were investigated. Co-doping of Ce{sup 3+} enhanced the emission intensity of Tb{sup 3+} greatly by transferring its energy to Tb{sup 3+}. Through an efficient energy transfer process, the obtained phosphors exhibit both the weak emission of Ce{sup 3+} (5d–4f) and the strong emission of Tb{sup 3+} ({sup 5}D{sub 4}–{sup 7}F{sub J}) with considerable intensity. The energy transfer mechanism from Ce{sup 3+} to Tb{sup 3+} ion was determined to be dipole–dipole interaction, and the energy transfer efficiency was over 90%. The effect of Ce{sup 3+} and Tb{sup 3+} concentrations on luminescence in single and co-doped phosphors was also studied. The novel phosphors have excellent thermal stability and remarkable CIE chromaticity coordinates of (0.3149, 0.5652), which points to its high potential as green emitting phosphor in lighting field. - Highlights: • A novel green Zn{sub 2}P{sub 2}O{sub 7} phosphor was synthesized by the solid state method. • The energy transfer mechanism of Ce{sup 3+}–Tb{sup 3+} was discussed in detail. • The phosphors have excellent optical property, luminous efficiency and thermal stability.

  10. Epitaxial growth of CeO2 thin film on cube textured NiW substrate using a propionate-based metalorganic deposition (MOD) method

    International Nuclear Information System (INIS)

    Highlights: ► Accurate study of decomposition of cerium propionate based precursors. ► Epitaxial CeO2 thin film on Ni–W substrate in a reducing atmosphere. ► The films exhibit a high degree of epitaxy within the Dimos criteria. ► The obtained CeO2 films are appropriate for YBCO based coated conductor application. - Abstract: The CeO2 films were epitaxially grown on (0 0 1)[1 0 0]Ni–W biaxially textured substrate using a propionate-based metalorganic deposition (MOD) method. The as deposited CeO2 films exhibit a sharp biaxial texture, with a full width at half maximum (FWHM) of φ and ω-scans of about 7.15° and 7.8°, respectively. The in-plane and out-of plane epitaxial relationship are [0 0 1]CeO2//[0 0 1]Ni–W and [1 0 0]CeO2//[1 1 0]Ni–W, respectively. The morphology of the films is strongly correlated with the film thickness and crystallization temperature. Thus, the 0.3 μm thick film crystallized at 1100 °C has a smooth surface free of cracks or voids with a root mean square roughness (RMS) of about 2.5 nm, whilst the 1.1 μm thick film presents many cracks and a low density of voids. The cracks along the substrate grain boundaries observed in the thicker films take place in the already crystallized film during the rapid cooling process due to difference between the thermal expansion coefficients of the film and metallic Ni–W substrate.

  11. Gene expression analysis and enzyme assay reveal a potential role of the carboxylesterase gene CpCE-1 from Cydia pomonella in detoxification of insecticides.

    Science.gov (United States)

    Yang, Xue-Qing

    2016-05-01

    Carboxylesterases (CarEs) are responsible for metabolism of xenobiotics including insecticides in insects. Understanding the expression patterns of a such detoxifying gene and effect of insecticides on its enzyme activity are important to clarify the function of this gene relevant to insecticides-detoxifying process, but little information is available in the codling moth Cydia pomonella (L.). In this study, we investigated the expression profiles of CarE gene CpCE-1 at different developmental stages and in different tissues of C. pomonella, as well as the larvae exposed to chlorpyrifos-ethyl and lambda-cyhalothrin by using absolute real-time quantitative PCR (absolute RT-qPCR). Results indicated that CpCE-1 expression was significantly altered during C. pomonella development stages, and this expression differed between sexes, with a higher transcript in females than males. Meanwhile, CpCE-1 is overexpressed in cuticle, midgut and head than silk gland, fat body and Malpighian tubules. Exposure of third instar larvae to a non-lethal dosage of chlorpyrifos-ethyl and lambda-cyhalothrin resulted in induction of CpCE-1 transcript. The total carboxylesterase enzyme activity was inhibited by chlorpyrifos-ethyl in vivo; in contrast, the activity of Escherichia coli produced recombinant CpCE-1 was significantly inhibited by both lambda-cyhalothrin and chlorpyrifos-ethyl in vitro. These results suggested that CpCE-1 in C. pomonella is potentially involved in the development and in detoxification of chlorpyrifos-ethyl and lambda-cyhalothrin. PMID:27017882

  12. Kinetic Study of Ce4+ Extraction with Cyanex 923

    Institute of Scientific and Technical Information of China (English)

    于桂红; 乐善堂; 李德谦; 凤优游

    2001-01-01

    Ce4+ extraction rate from aqueous sulphate solutions by Cyanex923 in heptane was studied using a constant interfacial cell with laminar flow at 30 ℃. The experimental hydrodynamic conditions were chosen and the contribution of diffusion to the measured rate of reaction was minimized. Cerium extraction rate was measured at different chemical composition by varying the concentrations of hydrogen ion, sulphate and Cyanex923. A cerium-Cyanex923(B) extractive is formed at the interface. The data were analyszed in terms of pseudo-first order constants and a reaction mechanism was developed.

  13. Programming Windows® Embedded CE 60 Developer Reference

    CERN Document Server

    Boling, Douglas

    2010-01-01

    Get the popular, practical reference to developing small footprint applications-now updated for the Windows Embedded CE 6.0 kernel. Written by an authority on embedded application development, this book focuses in on core operating concepts and the Win32 API. It delivers extensive code samples and sample projects-helping you build proficiency creating innovative Windows applications for a new generation of devices. Discover how to: Create complex applications designed for the unique requirements of embedded devicesManage virtual memory, heaps, and the stack to minimize your memory footprintC

  14. Kantavien teräsrakenteiden CE-merkintä

    OpenAIRE

    Rissanen, Ilkka

    2016-01-01

    Tässä diplomityössä käsitellään pienelle kotimaiselle konepajalle tehtyä kehityshanketta. Työn taustalla on Euroopan unionin talousalueella 1.7.2013 voimaan astunut asetus. Asetuksessa vaaditaan, että rakennustuotteilla, joita markkinoidaan Euroopan unionin talousalueella ja, joita koskevat yhtenäistetyt Euroopan unionin tuotedirektiivit täytyy olla varustettuna CE-merkinnällä. Teräsrakenteille asetus astui lopullisesti voimaan 1.7.2014. Työn tavoitteena oli kehittää kohdeyrityksen teräs...

  15. Projected shell model study of neutron-deficient 122Ce

    Indian Academy of Sciences (India)

    Rani Devi; B D Sehgal; S K Khosa

    2006-09-01

    The observed excited states of 122Ce nucleus have been studied in the frame-work of projected shell model (PSM). The yrast band has been studied up to spin 26 ħ. The first band crossing has been predicted above a rotational frequency of 0.4 MeV/ħ that corresponds to first backbending. The calculation reproduces the experimentally observed ground state band up to spin 14ħ. The electromagnetic quantities, transition quadrupole moments and -factors are predicted and there is a need to measure these quantities experimentally.

  16. Preparation and Characterization of Nanocrystalline CeO2 by Precipitation Method

    Institute of Scientific and Technical Information of China (English)

    董相廷; 李明; 张伟; 刘桂霞; 洪广言

    2002-01-01

    CeO2 nanocrystalline particulates with different sizes were prepared by precipitation method using ethanol as dispersive and protective reagent. XRD spectra show that the synthesized CeO2 has cubic crystalline structure of space group O5H-FM3M, when calcination temperature is in the range of 250~800 ℃. TEM images reveal that CeO2 particles are spherical in shape. The average size of the particles increases with the increase of calcination temperature. Thermogravimetric analysis indicates that the weight loss of precursor mainly depends on the calcination temperature, and little depends on the calcination time. Measurements of CeO2 relative density show that the relative density of CeO2 nanocrystalline powders increases with increasing CeO2 particle size.

  17. Equiatomic cerium intermetallics CeXX' with two p elements

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-01

    The equiatomic CeXX' phases (X and X' = elements of the 3{sup rd}, 4{sup th}, or 5{sup th} main group) extend the large series of CeTX intermetallics (T = electron-rich transition metal). These phases crystallize with simple structure types, i.e. ZrNiAl, TiNiSi, CeScSi, α-ThSi{sub 2}, AlB{sub 2}, and GdSi{sub 2}. In contrast to the CeTX intermetallics one observes pronounced solid solutions for the CeXX' phases. The main influence on the magnetic ground states results from the absence of d electrons. All known CeXX' phases show exclusively trivalent cerium and antiferro- or ferromagnetic ordering at low temperatures. The crystal chemical details and some structure-property relationships are reviewed.

  18. Long Lasting Phosphorescence in Eu2+ and Ce3+ Co-Doped Strontium Borate Glasses

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Long lasting phosphorescence (LLP) was observed in Eu2+, Ce3+ co-doped strontium borate glasses prepared under the reducing atmosphere due to the emission of both Eu2+ and Ce3+. The methods of photoluminescence, thermoluminescence and phosphorescence were used to study the samples, and possible mechanism was suggested. The co-doping of Ce3+ ions poisoned the phosphorescence emission of Eu2+ because of the competition to obtain the trapped electron. The phosphorescence of Ce3+ in the sample decays more quickly than that of Eu2+, which is suggested for the reason that the emission energy of Ce3+ is higher or the distance between Ce3+ and electron traps of the glasses is longer.

  19. Morphology Controlling of the Ultrafine Cerium Dioxide (CeO2) Precursor

    Institute of Scientific and Technical Information of China (English)

    Jianqing CHEN; Zhigang CHEN; Jinchun LI

    2004-01-01

    The synthesis of ultrafine cerium dioxide precursor via homogeneous precipitation was studied. Mixed aqueous solution of anhydrous cerium nitrate and urea was first heated to 85℃ for 2 h, and the prepared suspension was then aged at room temperature for various periods of time. White precipitate was finally collected by centrifuging and washed with distilled water and anhydrous ethanol. The obtained cerium dioxide (CeO2) precursor was observed with SEM. It was found that the morphology and size of the precursor were strongly affected by aging time and stirring conditions (with or without stirring).The precipitated fine spherical particles of the precursor changed their shape from ellipse to slice or directly to slice. Fine spherical monodispersed (300 nm) precursor powders could be obtained by controlling the aging time. Stirring the solution also could change the reaction process and thus the morphology and size of the precursor were changed.

  20. Vibronic interaction and crystal structure distortion in Cm4+:CeF4

    International Nuclear Information System (INIS)

    We have applied selective excitation to unravel the complex 5f state spectra of Cm4+ in CeF4 which arises from multiple metal ion sites and vibronic interactions. An unusual laser-induced site distortion on one of the two ion-sites has been studied. Distinct spectral lines of the distorted ion site were detected. The site distortion was found to be stable below 45 K and reverted, via a thermally activated process, at higher temperatures. Below 45 K, persistent spectral holes were burnt in the absorption lines of Cm4+ on distorted site. Site distortion and hole burning are interpreted based on excited-state vibronic coupling and the assumption of an asymmetric two-minimum potential surface. 15 refs., 2 figs

  1. YAG: Ce Phosphors for WLED via Nano-Pesudoboehmite Sol-Gel Route

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The sub-micron sized YAG: Ce phosphors were synthesized via a modified sol-gel method by peptizing nano-pesudoboehmite particulate. It is found that YAG phase from the dried gel powders appears at 1000 ℃ then the pure YAG phase exists at a relatively lower sintering temperature of 1400 ℃. The smaller sizes of phosphors in the ranges of 1 ~ 3 μm are obtained due to the contribution of seeding effects of nano-sized alumina particles to strengthen each step of the processes. Both the excitation and emission spectra of photoluminescence of the phosphor obtained at 1400 ℃ meet well with the spectroscopic requirements of the WLED phosphors.

  2. Vibronic interaction and crystal structure distortion in Cm4+ in CeF 4

    International Nuclear Information System (INIS)

    This paper reports on selective excitation to unravel the complex 5f-state spectra of Cm4+ in CeF4, which arise from multiple metal ion sites and vibronic interactions. an unusual laser-induced site distortion on one of the two ion sites has been studied. Distinct spectral lines of the distorted ion site were detected. The site distortion was found to be stable below 45 K and reverted, via a thermally activated process, at higher temperatures. Below 45 K, persistent spectral holes were burnt in the absorption lines of Cm4+ on the distorted site. Site distortion and hole burning are interpreted in light of excited-state vibronic coupling and the assumption of an asymmetric two-minimum potential surface

  3. Light-induced acoustic effect in LiNbO3:Fe:Ce crystals

    Institute of Scientific and Technical Information of China (English)

    Huang Wei; Wu Zhong-Kang; Wang Chang-Qing

    2005-01-01

    The phenomena of acoustic emission in LiNbO3:Fe:Ce crystals have been observed in the process of light-induced quasi-breakdown. It is found that the ultra-high frequency acoustic signal introduced into the crystal is modulated by the low frequency acoustic waves. Its frequency increases with the increase of the intensity of incident light and its jump period of breakdown is the same as that of the photovoltaic current Ic, the change of light-induced refractive index △n and the diffracted light intensity L. This phenomenon has been analysed in this paper, which is caused by the inverse piezoelectric strain effect of the jump of space charge field during the quasi-breakdown.

  4. Fabrication and Mechanical Properties of Sm2O3 Doped CeO2 Reinforced Ti3AlC2 Nano Composite

    Institute of Scientific and Technical Information of China (English)

    Jae Ho Han; Sang Whan Park; Young Do Kim

    2004-01-01

    The fabrication process of Sm2O3 doped CeO2 reinforced Ti3AlC2 nano composites including the nano particle dispersion process by a hetero-coagulation process was developed using in-situ synthesis and densification process of Ti3AlC2. The effects of Sm2O2 doped CeO2 nano particles on mechanical properties of Ti3AlC2 were investigated. It was found that the presence of 20SDC nano particles in Ti3AlC2 was very effective to improve the mechanical properties of Ti3AlC2 without spoiling the unique characteristics of Ti3AlC2temary carbide.

  5. CeO2-ZnO hexagonal nanodisks: Efficient material for the degradation of direct blue 15 dye and its simulated dye bath effluent under solar light

    International Nuclear Information System (INIS)

    Highlights: • Synthesis of CeO2-ZnO hexagonal nanodisks. • Excellent morphological, crystalline and photoluminescent properties. • Solar light responsive photocatalyst for degradation of direct blue 15 dye and its simulated dye bath effluent. - Abstract: Well-crystalline CeO2-ZnO hexagonal nanodisks were synthesized by simple and facile chemical reaction process at low-temperature and characterized in detail by using several techniques such as powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) emission spectroscopy and X-ray photoelectron spectroscopy (XPS). The detailed characterizations results revealed that the prepared samples are well-crystalline with good optical and structural properties and possessing hexagonal morphologies. Further, the prepared material was used as efficient photocatalyst for the photocatalytic degradation of highly hazardous direct blue (DB)-15 dye under solar light irradiation. The CeO2-ZnO hexagonal nanodisks exhibited superior photocatalytic performance towards the degradation of DB 15 dye and its simulated dye bath effluent under solar light. The enhanced photocatalytic activity of CeO2-ZnO hexagonal nanodisks could be attributed to the suppression of photo-induced e−/h+ pair recombination. Moreover, various scavengers have been used to study the role of reactive species in the photo-degradation process

  6. Tuning the properties of the UiO-66 metal organic framework by Ce substitution.

    Science.gov (United States)

    Nouar, Farid; Breeze, Matthew I; Campo, Betiana C; Vimont, Alexandre; Clet, Guillaume; Daturi, Marco; Devic, Thomas; Walton, Richard I; Serre, Christian

    2015-10-01

    Crystallisation of a mixed-metal form of the porous framework UiO-66 in which Zr is partially replaced by Ce produces a ligand-defective material, that contains some Ce(III) as well as a majority of Ce(IV). Infrared spectroscopy shows enhanced binding of methanol in the substituted material that leads to catalytic decomposition of the alcohol, which may be due to a combination of defects and redox activity. PMID:26278204

  7. Structural and magnetic phase transitions in CeCu6 -xTx (T =Ag ,Pd )

    Science.gov (United States)

    Poudel, L.; de la Cruz, C.; Payzant, E. A.; May, A. F.; Koehler, M.; Garlea, V. O.; Taylor, A. E.; Parker, D. S.; Cao, H. B.; McGuire, M. A.; Tian, W.; Matsuda, M.; Jeen, H.; Lee, H. N.; Hong, T.; Calder, S.; Zhou, H. D.; Lumsden, M. D.; Keppens, V.; Mandrus, D.; Christianson, A. D.

    2015-12-01

    The structural and the magnetic properties of CeCu6 -xAgx (0 ≤x ≤0.85 ) and CeCu6 -xPdx (0 ≤x ≤0.4 ) have been studied using neutron diffraction, resonant ultrasound spectroscopy (RUS), x-ray diffraction measurements, and first principles calculations. The structural and magnetic phase diagrams of CeCu6 -xAgx and CeCu6 -xPdx as a function of Ag/Pd composition are reported. The end member, CeCu6, undergoes a structural phase transition from an orthorhombic (P n m a ) to a monoclinic (P 21/c ) phase at 240 K. In CeCu6 -xAgx , the structural phase transition temperature (Ts) decreases linearly with Ag concentration and extrapolates to zero at xS ≈0.1 . The structural transition in CeCu6 -xPdx remains unperturbed with Pd substitution within the range of our study. The lattice constant b slightly decreases with Ag/Pd doping, whereas a and c increase with an overall increase in the unit cell volume. Both systems, CeCu6 -xAgx and CeCu6 -xPdx , exhibit a magnetic quantum critical point (QCP), at x ≈0.2 and x ≈0.05 , respectively. Near the QCP, long range antiferromagnetic ordering takes place at an incommensurate wave vector (δ10 δ2), where δ1˜0.62 ,δ2˜0.25 ,x =0.125 for CeCu6 -xPdx and δ1˜0.64 ,δ2˜0.3 ,x =0.3 for CeCu6 -xAgx . The magnetic structure consists of an amplitude modulation of the Ce moments which are aligned along the c axis of the orthorhombic unit cell.

  8. Thermal-neutron scintillator: Ce3+ activated Rb2LiYBr6

    NARCIS (Netherlands)

    Birowosuto, M.D.; Dorenbos, P.; De Haas, J.T.M.; Van Eijk, C.W.E.; Krämer, K.W.; Güdel, H.U.

    2007-01-01

    Scintillation and luminescence characteristics of Rb2LiYBr6 doped with 0.1%, 0.5%, 1%, and 5% Ce3+ are presented. Under optical and x-ray excitation, Ce3+ doublet emission is observed at 385 and 420 nm. Rb2LiYBr6:0.5% Ce3+ shows very high thermal neutron scintillation light output of 83 000 photons/

  9. Neutron scattering studies of non-Fermi liquid behavior in Ce compounds

    Science.gov (United States)

    Park, J.-G.; Adroja, D. T.; McEwen, K. A.; Murani, A. P.; So, J.-Y.; Beirne, E.; Echizen, Y.; Takabatake, T.

    2002-03-01

    We have studied the inelastic neutron scattering from two Ce heavy fermion compounds, Ce(Ni0.935Cu0.065)Sn and Ce(Rh0.8Pd0.2)Sb, that are located at the magnetic-non-magnetic boundary. We find that the magnetic scattering follows a power law scaling behavior, and that the dynamical susceptibility, as deduced from the magnetic scattering, shows E/T scaling behavior with significantly different exponents for the two systems.

  10. Spectral characteristics and energy transfer from Ce3+ to Tb3+ in compounds Lu1 - x - y Ce x Tb y BO3

    Science.gov (United States)

    Shmurak, S. Z.; Kedrov, V. V.; Kiselev, A. P.; Fursova, T. N.; Smyt'ko, I. M.

    2016-03-01

    The structure, IR absorption spectra, morphology, and spectral characteristics of compounds Lu1 - x - y Ce x Tb y BO3 have been investigated. It has been shown that the Tb3+ luminescence excitation spectrum of the Lu1 - x - y Ce x Tb y BO3 compounds is dominated by a broad band coinciding with the excitation band of Ce3+ ions, which clearly indicates energy transfer from the Ce3+ ions to the Tb3+ ions. The spectral position of this band depends on the structural state of the sample: in the structures of calcite and vaterite, the band has maxima at ~339 and ~367 nm, respectively. By varying the ratio between the calcite and vaterite phases in the sample, it is possible to purposefully change the Tb3+ luminescence excitation spectrum, which is important for the optimization of the spectral characteristics of Lu1 - x - y Ce x Tb y BO3 when it is used in light-emitting diode sources. An estimate has been obtained for the maximum distance between Ce3+ and Tb3+ ions, which corresponds to electronic excitation energy transfer. It has been shown that the high intensity of Tb3+ luminescence in these compounds is due to the high efficiency of electronic excitation energy transfer from the Ce3+ ions to the Tb3+ ions as a result of the dipole-dipole interaction.

  11. High-pressure Raman study on CeO{sub 2} nanospheres self-assembled by 5 nm CeO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bo; Liu, Bingbing; Li, Quanjun; Li, Zepeng; Yao, Mingguang; Liu, Ran; Zou, Xu; Lv, Hang; Wu, Wei; Cui, Wen; Liu, Zhaodong; Li, Dongmei; Zou, Bo; Cui, Tian; Zou, Guangtian [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China)

    2011-05-15

    CeO{sub 2} undergoes a first-order phase transition from fluorite to {alpha}-PbCl{sub 2}-type structure under high pressure. To evaluate the changes in physical properties of CeO{sub 2} nanomaterials as the particle size decreasing, high-pressure Raman study under quasi-hydrostatic condition has been performed on CeO{sub 2} nanospheres self-assembled by 5 nm CeO{sub 2} nanoparticles at room temperature. Surprisingly, as the pressure elevate to 34 GPa, the CeO{sub 2} nanospheres still retain the cubic fluorite-type structure, indicating the sample is more stable than the bulk counterpart. Whereas, previous high-pressure studies show the phase transition at 22.3/26.5 GPa for 12 nm CeO{sub 2} nanoparticles, which is less stable than the bulk materials. The enhancement of phase stability might be attributed to the increase of surface energy of CeO{sub 2} nanospheres as the size of the building units decrease. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Synthesis, Crystal Structure and Thermal Decomposition of [Ce(NO3)5H2O]·(C3N2H5)2%[Ce(NO3)5H2O]·(C3H5N2)2的合成、晶体结构及热分析

    Institute of Scientific and Technical Information of China (English)

    薛岗林; 杨一心; 李恒新; 何水样; 李君

    2001-01-01

    Colorless crystal,[Ce(NO3) 5H2O]·(C3N2H5)2, has been obtained from the reaction of Ce(NO3)3 with imdazole in the aqueous solution and its crystal structure has been determined by single crystal X-ray diffraction techniques. The crystal belongs to triclinic, space group P1. The cell parameters are: a=0.7489(1) nm, b=0.7914(2)nm, c=1.8139(3)nm, α=89.39(2)°, β=89.37(1)°, γ=63.18(2)°, Dc=2. lg·cm-3, Z=2, R=0.0319. In the compound, all of five nitrates are bidentate and one molecule of water is monodentate, the coordination number of Ce(Ⅲ) is 11.The processes of thermal decomposition of the compound was proposed by its TG curve.

  13. Thermal Variance Investigation and Scintillation Mechanisms of Cs2LiLaBr6-xClx:Ce (CLLBC) and Cs2LiYBr6:Ce (CLYB)

    Energy Technology Data Exchange (ETDEWEB)

    Coupland, Daniel David Schechtman [Los Alamos National Laboratory; Budden, Brent Scott [Los Alamos National Laboratory; Stonehill, Laura Catherine [Los Alamos National Laboratory

    2015-11-23

    We perform an investigation into the scintillation processes and performance of elpasolites Cs2LiLaBr6-xClx:Ce (CLLBC) and Cs2LiYBr6:Ce (CLYB) using a thermal cycle over a range of -20 to +50º C. At 10º increments, we acquire data with both a waveform digitizer and charge-integrating electronics. We identify decay components and evaluate decay times, thermal neutron gamma-equivalent energy (GEE), and pulse shape discrimination (PSD) performance. Results are compared to common Cs2LiYCl6:Ce (CLYC).

  14. Preparation of Na{sub 4}UO{sub 2}(CO{sub 3}){sub 3} in presence of Ce-141. II, Treatment of uranium decontamination; Preparacion del Na{sub 4}UO{sub 2}(CO{sub 3}){sub 3} en presencia de Ce-141. II, Tratamiento de descontaminacion de uranio

    Energy Technology Data Exchange (ETDEWEB)

    Lopez M, B.E.; Rodriguez S, A

    1992-02-15

    It was settled down that the coexistence of chemical species structurally different of cerium, is a consequence of the preparation time; whose practical application, for the purification of the uranium, it can constitute the technological aspect but important in the ion exchange process, to separate the Ce-141 from the uranium. (Author)

  15. Non-aqueous CE-MS of cinchona alkaloids - characterization of a novel CE-ESI-MS interface

    DEFF Research Database (Denmark)

    Hansen, Frederik André; Hansen, Steen Honoré; Petersen, Nickolaj J.

    the composition of alkaloids in Cinchona bark. One common problem for sheatless interfaces for CE-MS has been establishing a stable electric contact at the end of the separation capillary that does not induce band broadening or affect the spray stability. In our device the electric contact is generated through....... Furthermore, the increased conductivity of the buffer in the fracture generates field free pumping of the analytes towards the ESI spray tip. In this study the device was used to analyze the four major alkaloids (diastereomeric pairs of quinine/quinidine and cinchonine/cinchonidine) in Cinchona bark samples...

  16. Study of structural and electronic transport properties of Ce-doped LaMnO3

    Indian Academy of Sciences (India)

    Shahid Husain; R J Choudhary; Ravi Kumar; S I Patil; J P Srivastava

    2002-05-01

    The structural and electronic transport properties of La1-CeMnO3 (=0.0-1.0) have been studied. All the samples exhibit orthorhombic crystal symmetry and the unit cell volume decreases with Ce doping. They also make a metal–insulator transition (MIT) and transition temperature increases with increase in Ce concentration up to 50% doping. The system La0.5Ce0.5MnO3 also exhibits MIT instead of charge-ordered state as observed in the hole doped systems of the same composition.

  17. Metallic oxides supported in CeO{sub 2} and CeO{sub 2}-La{sub 2} O{sub 3} for low temperature shift reaction; Oxidos metalicos suportados em CeO{sub 2} e CeO{sub 2}-La{sub 2} O{sub 3} para reacao shift a baixa temperatura

    Energy Technology Data Exchange (ETDEWEB)

    Maluf, Silvia Salua; Assaf, Elisabete Moreira [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Inst. de Quimica]. E-mail: sil_maluf@iqsc.usp.br

    2008-07-01

    This work studied copper and zinc oxides supported in CeO{sub 2} and CeO{sub 2}/La{sub 2}O{sub 3}. The catalytic tests for low temperature shift reaction, carried out for samples, showed the Cu-Ce catalyst presents the highest value of CO conversion (50%) and after the Cu-Ce-La catalysts (30%). The other catalysts showed CO conversion in range of 15%. This behavior is related with surface area, and also with the amount of Cu in the surface of samples (author)

  18. Growth and Photoluminescence of Epitaxial CeO2 Film on Si (111) Substrate

    Institute of Scientific and Technical Information of China (English)

    GAO Fei; ZHANG Jian-Hui; QIN Fu-Guang; YAO Zhen-Yu; LIU Zhi-Kai; WANG Zhan-Guo; LIN Lan-Ying

    2001-01-01

    A CeO2 film with a thickness of about 80nm was deposited by a mass-analysed low-energy dual ion beam deposition technique on an Si(111) substrate. Reflection high-energy electron diffraction and x-ray diffraction measurements showed that the film is a single crystal. The tetravalent state of Ce in the film was confirmed by xray photoelectron spectroscopy measurements, indicating that stoichiometric CeO2 was formed. Violet/blue light emission (379.5 nm) was observed at room temperature, which may be tentatively explained by charge transitions from the 4f band to the valence band of CeO2.

  19. Experimental investigation and thermodynamic calculation of the Zn–Fe–Ce system

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Longfei; Wu, Changjun [Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Jiangsu 213164 (China); Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou University, Jiangsu 213164 (China); Wang, Jianhua, E-mail: wangjh@cczu.edu.cn [Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Jiangsu 213164 (China); Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou University, Jiangsu 213164 (China); Liu, Ya; Tu, Hao; Su, Xuping [Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Jiangsu 213164 (China); Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou University, Jiangsu 213164 (China)

    2015-11-05

    The 450 °C and 600 °C isothermal sections of the Zn–Fe–Ce system were investigated using equilibrated alloys and diffusion couples. The samples were analyzed by Scanning Electron Microscopy equipped with Energy Dispersive X-ray Spectrometer analysis and X-ray power diffraction. 15 and 13 three-phase regions were identified to exist at 450 °C and 600 °C, respectively. No ternary compound was found. Ce can not dissolve into all the Zn–Fe binary compounds and the solubilities of Fe in all the Zn–Ce binary phases were limited. All the Zn–Fe compounds can equilibrate with CeZn{sub 11} and all the Ce–Zn compounds (except CeZn) can equilibrate with α-Fe. Furthermore, thermodynamic extrapolation of the Zn–Fe–Ce system was carried out and showed good agreement well with detected phase relationships. - Highlights: • 450 °C and 600 °C sections of the Zn–Fe–Ce system were constructed. • No ternary compound exists. • Ce can not dissolve into all the Zn–Fe compounds. • All the Fe–Zn compounds can equilibrate with CeZn{sub 11}. • Thermodynamic extrapolation results agree with experimental data.

  20. Oxygen storage and catalytic NO removal promoted by CeO2-containing mixed oxides

    International Nuclear Information System (INIS)

    CeO2-ZrO2 mixed oxides show improved redox properties as compared to CeO2 which makes them important innovative materials for three-way catalysts. The origin of this effect and the structural/redox correlation are discussed. The influence of the improved redox capacities on the reduction of NO by CO catalyzed by Rh/CeO2-ZrO2 catalysts is reported and evidence for an active role of the CeO2-ZrO2 support in NO activation is presented. (orig.)

  1. Selective synthesis and growth mechanism of CeVO4 nanoparticals via hydrothermal method

    Institute of Scientific and Technical Information of China (English)

    LIU Fengzhen; SHAO Xin; YIN Yibin; ZHAO Limin; SUN Qiaozhen; SHAO Zhuwei; LIU Xuehua; MENG Xianhua

    2011-01-01

    Selective-controlled structure and shape of CeVO4 nanocrystals were successfully synthesized via a hydrothermal method from electron microscopy (FESEM) and energy dispersive spectroscopy (EDS). The influence of hydrothermal temperature, precursor solution concentration on the crystal and morphology of products were further studied. The results showed that the as-synthesized products exhibited pure single-crystal CeVO4 nanoparticles with tetragonal structure. The hydrothermal temperature and precursor solution concentration had important effects on the formation of CeVO4 nanoparticles. Furthermore, the growth mechanism of CeVO4 nanoparticles was explained with Ostwald ripening mechanism.

  2. Growth and Electronic Properties of Ag Nanoparticles on Reduced CeO2-x(111) Films

    Institute of Scientific and Technical Information of China (English)

    Dan-dan Kong; Yong-he Pan; Guo-dong Wang; Hai-bin Pan; Jun-fa Zhu

    2012-01-01

    Ag nanoparticles grown on reduced CeO2-x thin films have been studied by X-ray photoelectron spectroscopy and resonant photoelectron spectroscopy of the valence band to understand the effect of oxygen vacancies in the CeO2-x thin films on the growth and interfacial electronic properties of Ag.Ag grows as three-dimensional particles on the CeO2-x(111) surface at 300 K.Compared to the fully oxidized ceria substrate surface,Ag favors the growth of smaller particles with a larger particle density on the reduced ceria substrate surface,which can be attributed to the nucleation of Ag on oxygen vacancies.The binding energy of Ag3d increases when the Ag particle size decreases,which is mainly attributed to the final-state screening.The interfacial interaction between Ag and CeO2-x(111) is weak.The resonant enhancement of the 4f level of Ce3+ species in RPES indicates a partial Ce4+→Ce3+ reduction after Ag deposited on reduced ceria surface.The sintering temperature of Ag on CeO 1.85 (111) surface during annealing is a little higher than that of Ag on CeO2 (111) surface,indicating that Ag nanoparticles are more stable on the reduced ceria surface.

  3. Effect of Cerium on Chemical Short-Range Order of Al-Fe-Ce Amorphous Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The chemical short-range order of Al-Fe-Ce amorphous alloy was studied by means of X-ray diffraction(XRD) and differential scanning calorimetry(DSC). It is found that the prepeak position in X-ray diffraction intensity curve shifts to higher angles as the content of Fe increases, but it shifts to smaller angles as the content of Ce increases. The crystallization character of the amorphous alloy changes with the variation of the content of Fe and Ce. Ce can improve the interaction between atoms and the capacity of compound formation, so it is favorable to Al-based glass formability.

  4. Research on CeO2 cap layer for YBCO-coated conductor

    Institute of Scientific and Technical Information of China (English)

    Shi Dong-Qi; Ma Ping; Ko Rock-Kil; Kim Ho-Sup; Chung Jun-Ki; Song Kyu-Jeong; Park Chan

    2007-01-01

    Two groups of coated conductor samples with different thicknesses of CeO2 cap layers deposited by pulsed laser deposition (PLD) under the same conditions have been studied. Of them, one group is of CeO2 films, which are deposited on stainless steel (SS) tapes coated by IBAD-YSZ (IBAD-YSZ/SS), and the other group is of CeO2/YSZ/Y2O3 multilayers, which are deposited on NiW substrates by PLD for the fabrication of YBCO-coated conductor through the RABiTS approach. YBCO film is then deposited on the tops of both types of buffer layers by PLD. The effects of the thickness of the CeO2 film on the texture of the CeO2 film and the critical current density (Jc) of the YBCO film are analysed. For the case of CeO2 film on IBAD-YSZ/SS, there appears a self-epitaxy effect with increasing thickness of the CeO2 film. For CeO2/YSZ/Y2O3/NiW, in which the buffer layers are deposited by PLD, there occurs no self-epitaxy effect, and the optimal thickness of CeO2 is about 50nm. The surface morphologies of the two groups of samples are examined by SEM.

  5. Electronic structure of the heavy fermion superconductor Ce2PdIn8: Experiment and calculations

    International Nuclear Information System (INIS)

    The electronic structure of a heavy-fermion superconductor Ce2PdIn8 was investigated by means of X-ray photoelectron spectroscopy (XPS) and ab initio density functional band structure calculations. The Ce 3d core-level XPS spectra point to stable trivalent configuration of Ce atoms that is also reproduced in the band structure calculations within the generalized gradient approximation GGA+U approach. Analysis of the 3d9f2 weight in the 3d XPS spectra within the Gunnarsson-Schönhammer model suggests that the onsite hybridization energy between Ce 4f and the conduction band states, Δfs, is ∼120 meV, which is about 30 meV larger than Δfs in isostructural Ce2TIn8 compounds with T = Co, Rh, and Ir. Taking into account a Coulomb repulsion U on both the Ce 4f and Pd 4d states in electronic band structure calculations, a satisfactory agreement was found between the calculated density of states (DOS) and the measured valence band XPS spectra. - Highlights: • XPS data validated strong electronic correlations in superconducting Ce2PdIn8. • DFT calculations reproduced XPS spectra measured for Ce2PdIn8. • Crucial role of Pd d electrons in the HF behavior of Ce2PdIn8 was established

  6. Microstructure and properties of a Mo-CeO2 heated cathode material

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jiuxing; WAN Xiaofeng; LI Xiangbo; ZHOU Wenyuan; ZHOU Meiling

    2004-01-01

    The microstructure, mechanical properties, and electron-emission properties of a newly developed heated cath ode material Mo-CeO2 with 4.0% (mass fraction) of CeO2 were investigated. It is shown that the Mo-CeO2 cathode material possesses high tensile strength and good room-temperature ductility. After carbonized, the Mo-CeO2 cathode material has a higher zero field emission current density and a lower work function compared with the W-ThO2 cathode material.

  7. Fragility and glass forming ability of Al-Ni-Ce alloy melts

    Institute of Scientific and Technical Information of China (English)

    赵岩; 边秀房; 孙民华; 张均艳

    2004-01-01

    The fragility of Al-Ni-Ce alloy melts with three kinds of different compositions, Al85Ni10Ce5,Al85Ni8Ce7, Al85Ni5Ce10(mole fraction, %), was studied using oscillating-vessel viscometer and differential scanning calorimetry. Their fragility parameters obtained from experiments and theoretic calculation are:238,228 and 335 respectively. The results indicate that these three kinds of Al-Ni-Ce alloy melts are very fragile liquids, which kinetically show strong non-Arrhenius behaviour in the Angell plot, so they have poor glass forming ability (GFA).The alloy melt Al85Ni5Ce10 has the largest fragility parameter among the three alloy melts. In the preparation of rapidly quenched amorphous ribbons, Al85Ni10Ce5 and Al85Ni8Ce7 can gain amorphous ribbons when the rotate speed of the roller reaches 800 r/min, while for Al85Ni5Ce10 it must exceed 1 000 r/min.

  8. Perturbing the superconducting planes in CeCoIn5 by Snsubstitution

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, M.; Bauer, E.D.; Han, S.-W.; Booth, C.H.; Cornelius,A.L.; Pagliuso, P.G.; Sarrao, J.L.

    2005-01-11

    In contrast to substitution on the Co or Ce site, Sn substitution has a remarkably strong effect on superconductivity in CeCoIn{sub 5-x}Sn{sub x}, with T{sub c} {yields} 0 beyond only {approx}3.6% Sn. Instead of being randomly distributed on in-plane and out-of-plane In sites, extended x-ray absorption fine structure measurements show the Sn atoms preferentially substitute within the Ce-In plane. This result highlights the importance of the In(1) site to impurity scattering and clearly demonstrates the two-dimensional nature of superconductivity in CeCoIn{sub 5}.

  9. High frequency of labral pathology in dysplastic hips with a CE angle between 20-25

    DEFF Research Database (Denmark)

    Jakobsen, Stig Storgaard; Hartig-Andreasen, Charlotte; Mikkelsen, Lone Rømer;

    Background: Hip dysplasia becomes symptomatic due to labral pathology and secondary muscular pain. A CE angle pathologic and defined as dysplasia in PAO centres in Denmark. However, it is debated whether a CE angle between 20 and 25 is borderline. Purpose / Aim of Study: We aimed...... to investigate the degree of labral pathology in symptomatic patients with CE between 20 and 25 compared with patients with CE ... of osteoarthritis 0 or 1. All patients had a magnetic resonance arthrography (MRA) performed. The MRA was assessed for labral pathology in terms of degeneration, hypertrophic changes, tears and paralabral cysts. Labral lesions were graded according to the Czerny classification. Findings / Results: In the group...

  10. Low-temperature catalytic oxidation of NO over Mn-Ce-O_x catalyst

    Institute of Scientific and Technical Information of China (English)

    李华; 唐晓龙; 易红宏; 于丽丽

    2010-01-01

    A series of manganese-cerium oxide catalysts were prepared by different methods and used for low-temperature catalytic oxidation of NO in the presence of excess O2.Their surface properties were evaluated by means of BET and were characterized by using scanning electron microscopy(SEM) and X-ray diffractometer(XRD).The activity test of Mn-Ce-Ox catalysts showed that addition of Ce enhanced the activities of NO oxidation.The most active catalysts with a molar Ce/(Mn+Ce) ratio of 0.3 were prepared by co-precip...

  11. Optical properties of Ce3+ doped fluorophosphates scintillation glasses

    Science.gov (United States)

    Yao, Yongxin; Liu, Liwan; Zhang, Yu; Chen, Danping; Fang, Yongzheng; Zhao, Guoying

    2016-01-01

    Fluorophosphates (P2O5-BaO-BaF2-Al2O3-Gd2O3-Ce2O3) glasses with different Gd2O3 and BaF2 concentrations have been prepared by a melt quenching method. The effect of Gd2O3 and BaF2 on the glass performance including the density, absorption as well as luminescence properties under both ultraviolet (UV) and X-ray excitation was studied systematically. Energy transfer from Gd3+ to Ce3+ plays an important role in the scintillation mechanism of these glasses and the optimum concentration of Gd2O3 is found to be approximately 3 mol%. The highest integrated light emission intensity of these glass samples excited by X-ray is 25% of BGO and the decay time constants are in the range of 25-35 ns, much shorter than the 300 ns decay time of BGO. Meanwhile, replacing lighter compound BaO with the BaF2 can increase the density of the glasses and also improve the light yield.

  12. Band structures in near spherical {sup 138}Ce

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, T. [Variable Energy Cyclotron Centre, Kolkata 700 064 (India)], E-mail: btumpa@veccal.ernet.in; Chanda, S. [Variable Energy Cyclotron Centre, Kolkata 700 064 (India); Fakir Chand College, Diamond Harbour, West Bengal (India); Bhattacharyya, S.; Basu, S.K. [Variable Energy Cyclotron Centre, Kolkata 700 064 (India); Bhowmik, R.K.; Das, J.J. [Inter University Accelerator Centre, New Delhi 110 067 (India); Pramanik, U. Datta [Saha Institute of Nuclear Physics, Kolkata 700 064 (India); Ghugre, S.S. [UGC-DAE Consortium for Scientific Research, Kolkata Centre, Kolkata 700 098 (India); Madhavan, N. [Inter University Accelerator Centre, New Delhi 110 067 (India); Mukherjee, A.; Mukherjee, G. [Variable Energy Cyclotron Centre, Kolkata 700 064 (India); Muralithar, S.; Singh, R.P. [Inter University Accelerator Centre, New Delhi 110 067 (India)

    2009-06-15

    The high spin states of N=80{sup 138}Ce have been populated in the fusion evaporation reaction {sup 130}Te({sup 12}C, 4n){sup 138}Ce at E{sub beam}=65 MeV. The {gamma} transitions belonging to various band structures were detected and characterized using an array of five Clover Germanium detectors. The level scheme has been established up to a maximum spin and excitation energy of 23h and 9511.3 keV, respectively, by including 53 new transitions. The negative parity {delta}I=1 band, developed on the 6536.3 keV 15{sup -} level, has been conjectured to be a magnetic rotation band following a semiclassical analysis and comparing the systematics of similar bands in the neighboring nuclei. The said band is proposed to have a four quasiparticle configuration of [{pi}g{sub 7/2}h{sub (11)/2}]x[{nu}h{sub (11)/2}]{sup -2}. Other band structures are interpreted in terms of multi-quasiparticle configurations, based on Total Routhian Surface (TRS) calculations. For the low and medium spin states, a shell model calculation using a realistic two body interaction has been performed using the code OXBASH.

  13. Genome Mining in Sorangium cellulosum So ce56

    Science.gov (United States)

    Ewen, Kerstin Maria; Hannemann, Frank; Khatri, Yogan; Perlova, Olena; Kappl, Reinhard; Krug, Daniel; Hüttermann, Jürgen; Müller, Rolf; Bernhardt, Rita

    2009-01-01

    Myxobacteria, especially members of the genus Sorangium, are known for their biotechnological potential as producers of pharmaceutically valuable secondary metabolites. The biosynthesis of several of those myxobacterial compounds includes cytochrome P450 activity. Although class I cytochrome P450 enzymes occur wide-spread in bacteria and rely on ferredoxins and ferredoxin reductases as essential electron mediators, the study of these proteins is often neglected. Therefore, we decided to search in the Sorangium cellulosum So ce56 genome for putative interaction partners of cytochromes P450. In this work we report the investigation of eight myxobacterial ferredoxins and two ferredoxin reductases with respect to their activity in cytochrome P450 systems. Intriguingly, we found not only one, but two ferredoxins whose ability to sustain an endogenous So ce56 cytochrome P450 was demonstrated by CYP260A1-dependent conversion of nootkatone. Moreover, we could demonstrate that the two ferredoxins were able to receive electrons from both ferredoxin reductases. These findings indicate that S. cellulosum can alternate between different electron transport pathways to sustain cytochrome P450 activity. PMID:19696019

  14. CE-4 Mission and Future Journey to Lunar

    Science.gov (United States)

    Zou, Yongliao; Wang, Qin; Liu, Xiaoqun

    2016-07-01

    Chang'E-4 mission, being undertaken by phase two of China Lunar Exploration Program, represents China's first attempt to explore farside of lunar surface. Its probe includes a lander, a rover and a telecommunication relay which is scheduled to launch in around 2018. The scientific objectives of CE-4 mission will be implemented to investigate the lunar regional geological characteristics of landing and roving area, and also will make the first radio-astronomy measurements from the most radio-quiet region of near-earth space. The rover will opreate for at least 3 months, the lander for half a year, and the relay for no less than 3 years. Its scinetific instruments includes Cameras, infrared imaging spectrometer, Penetrating Radar onboard the rover in which is the same as the paylads on board the CE-3 rover, and a Dust-analyzer, a Temperature-instrument and a Wide Band Low Frequency Digital Radio Astronomical Station will be installed on board the lander. Our scientific goals of the future lunar exploration will aim at the lunar geology, resources and surface environments. A series of exploraion missions such as robotic exploration and non-manned lunar scientific station is proposed in this paper.

  15. La vérite sur ce qui nous motive

    CERN Document Server

    Pink, Daniel H

    2011-01-01

    Voici enfin la traduction française du best-seller international DRIVE ! Qu'est-ce qui nous motive vraiment ? Dans quels cas sommes-nous les plus performants et les plus enthousiastes ? La plupart d'entre nous sommes persuadés que les récompenses (salaire, primes...) sont notre meilleure motivation. La logique de la carotte et du bâton finalement... Et si nous faisions fausse route ? En s'appuyant sur quatre décennies d'études scientifiques et psychologiques sur la motivation humaine, Pink démontre que les entreprises dirigent très mal leurs équipes avec d'énormes conséquences sur notre vie (absence d'ambition, lassitude, morosité). Le secret de la performance (et de la satisfaction) dans les entreprises, l'enseignement ou dans notre vie personnelle , c'est le besoin profondément humain de diriger sa propre vie, d'apprendre, de créer de nouvelles choses et de s'améliorer. Dans ce livre, Pink examine les 3 éléments de la motivation, l'autonomie, la maîtrise et le besoin de donner un sens ...

  16. The role of Ce reduction in the segregation of metastable phases in the ZrO2–CeO2 system

    OpenAIRE

    Sanjuán, M. L.; Oliete, Patricia B.; Várez, A.; Sanz Lázaro, Jesús

    2012-01-01

    The complexity of the ZrO2–CeO2 phase diagram arises from several factors: the low solubility of each compound into the other one, the slow kinetics of cation diffusion, the occurrence of Ce reduction at high temperatures, and the existence of several metastable phases whose appearance and evolution depend on synthesis method and thermal history of the sample. Identification of phase content is moreover complicated because the X-ray diffractograms of some ZrO2–CeO2 phases are very close or ev...

  17. A density functional theory study of the competitive complexation of pyridine against H{sub 2}O and Cl{sup -} to Cm{sup 3+} and Ce{sup 4+}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhuxiang [Chinese Academy of Sciences (CAS), Beijing (China). Laboratory of Nuclear Analysis Techniques; Peking Univ., Beijing (China). Beijing National Laboratory for Molecular Sciences; Chu, Taiwei [Peking Univ., Beijing (China). Beijing National Laboratory for Molecular Sciences; Chai, Zhifang; Wang, Dongqi [Chinese Academy of Sciences (CAS), Beijing (China). Laboratory of Nuclear Analysis Techniques

    2014-04-01

    Density functional theory was used to study the coordination of Cm{sup 3+} and Ce{sup 4+} with pyridine (Py), water (H{sub 2}O) and chloride anion (Cl{sup -}). The competitive coordination of Cl{sup -} and Py was investigated to simulate the ligand exchange between Cl{sup -} and Py at high concentration of hydrochloric acid (HCl), where Cm{sup 3+} and Ce{sup 4+} may exist in the form of [CmCl{sub 6}]{sup 3-} and [CeCl{sub 6}]{sup 2-}, while that of water and Py to simulate the process at low concentration or without the presence of Cl{sup -}. The calculations show that Ce{sup 4+} has higher affinity to Py than Cm{sup 3+} in the absence of Cl{sup -}, while it binds much more weakly at high concentration of HCl. This is consistent with experimental data that at high concentration of HCl, Ce{sup 4+} has much shorter retention time than Cm{sup 3+} using tertiary pyridine resin (TPR). In view of the strengthening of M-Cl and the weakening of M-OW at bonds upon the coordination of Py, we conclude that the distinct coordination abilities of the three ligands to Ce{sup 4+} and Cm{sup 3+} are due to different strengths of the inner-shell electrostatic interaction between the ligands and the central metal ions. (orig.)

  18. Investigation of the Poisoning Mechanism of Lead on the CeO2-WO3 Catalyst for the NH3-SCR Reaction via in Situ IR and Raman Spectroscopy Measurement.

    Science.gov (United States)

    Peng, Yue; Si, Wenzhe; Li, Xiang; Chen, Jianjun; Li, Junhua; Crittenden, John; Hao, Jiming

    2016-09-01

    The in situ IR and Raman spectroscopy measurements were conducted to investigate lead poisoning on the CeO2-WO3 catalysts. The deactivation mechanisms were studied with respect to the changes of surface acidity, redox property, nitrate/nitrite adsorption behaviors, and key active sites (note that the results of structure-activity relationship of CeO2-WO3 were based on our previous research). (1) Lewis acid sites originated from CeO2 and crystalline WO3, whereas Brønsted acid sites originated from Ce2(WO4)3. The poisoned catalysts exhibited a lower surface acidity than the fresh catalysts: the number of acid sites decreased, and their thermal stability weakened. (2) The reducibility of catalysts and the amount of active oxygen exhibited a smaller influence after poisoning because lead preferred to bond with surface WOx species rather than CeO2. (3) The quantity of active nitrate species decreased due to the lead coverage on the catalyst and the partial bridged-nitrate species induced by lead exhibited a low degree of activity at 200 °C. (4) Crystalline WO3 and Ce2(WO4)3 originated from the transformation of polytungstate sites. These sites were the key active sites during the SCR process. The formation temperatures of polytungstate on the poisoned catalysts were higher than those on the fresh catalysts. PMID:27480109

  19. Investigation of the Poisoning Mechanism of Lead on the CeO2-WO3 Catalyst for the NH3-SCR Reaction via in Situ IR and Raman Spectroscopy Measurement.

    Science.gov (United States)

    Peng, Yue; Si, Wenzhe; Li, Xiang; Chen, Jianjun; Li, Junhua; Crittenden, John; Hao, Jiming

    2016-09-01

    The in situ IR and Raman spectroscopy measurements were conducted to investigate lead poisoning on the CeO2-WO3 catalysts. The deactivation mechanisms were studied with respect to the changes of surface acidity, redox property, nitrate/nitrite adsorption behaviors, and key active sites (note that the results of structure-activity relationship of CeO2-WO3 were based on our previous research). (1) Lewis acid sites originated from CeO2 and crystalline WO3, whereas Brønsted acid sites originated from Ce2(WO4)3. The poisoned catalysts exhibited a lower surface acidity than the fresh catalysts: the number of acid sites decreased, and their thermal stability weakened. (2) The reducibility of catalysts and the amount of active oxygen exhibited a smaller influence after poisoning because lead preferred to bond with surface WOx species rather than CeO2. (3) The quantity of active nitrate species decreased due to the lead coverage on the catalyst and the partial bridged-nitrate species induced by lead exhibited a low degree of activity at 200 °C. (4) Crystalline WO3 and Ce2(WO4)3 originated from the transformation of polytungstate sites. These sites were the key active sites during the SCR process. The formation temperatures of polytungstate on the poisoned catalysts were higher than those on the fresh catalysts.

  20. Novel nanostructured CeO2 as efficient catalyst for energy and environmental applications

    Indian Academy of Sciences (India)

    Sumanta Kumar Meher; G Ranga Rao

    2014-03-01

    We report here versatile methods to engineer the microstructure and understand the fundamental physicochemical properties of CeO2 to improve its catalytic viability for practical applications. In this context, different morphologies of CeO2 are synthesized using tailored homogeneous precipitation methods and characterized by XRD, BET, SEM and TPR methods. The shuttle-shaped CeO2 prepared under hydrothermal condition shows higher surface area and low-temperature reducibility. The 0.5 wt% Pt-impregnated shuttle-shaped CeO2 shows lower-temperature CO oxidation behaviour as compared to its bulk-like CeO2 (with 0.5 wt% Pt) counterpart, synthesized by conventional-reflux method. Further, nanorod morphology of CeO2 prepared with Cl−as counter ion shows lower-temperature oxidation of soot as compared to the mesoflower morphology of CeO2, prepared with NO$^{−}_{3}$ as counter ion in the reaction medium. Further, linear sweep voltammetry, chronopotentiometry and CO-stripping voltammetry studies are performed to evaluate the promoting activity of CeO2 to Pt/C for ethanol electro-oxidation reaction in acidic media. Results show that CeO2 provides active triple-phase-interfacial sites for suitable adsorption of OH species which effectively oxidize the COads on Pt/C. The results presented here are significant in the context of understanding the physicochemical fine prints of CeO2 and CeO2 based hetero-nanocomposites for their suitability to important catalytic and energy-related applications.