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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. Experimental insights on the electron transfer and energy transfer processes between Ce3+-Yb3+ and Ce3+-Tb3+ in borate glass

    International Nuclear Information System (INIS)

    A facile method to describe the electron transfer and energy transfer processes among lanthanide ions is presented based on the temperature dependent donor luminescence decay kinetics. The electron transfer process in Ce3+-Yb3+ exhibits a steady rise with temperature, whereas the Ce3+-Tb3+ energy transfer remains nearly unaffected. This feature has been investigated using the rate equation modeling and a methodology for the quantitative estimation of interaction parameters is presented. Moreover, the overall consequences of electron transfer and energy transfer process on donor-acceptor luminescence behavior, quantum efficiency, and donor luminescence decay kinetics are discussed in borate glass host. The results in this study propose a straight forward approach to distinguish the electron transfer and energy transfer processes between lanthanide ions in dielectric hosts, which is highly advantageous in view of the recent developments on lanthanide doped materials for spectral conversion, persistent luminescence, and related applications

  8. Data processing and error analysis for the CE-1 Lunar microwave radiometer

    International Nuclear Information System (INIS)

    The microwave radiometer (MRM) onboard the Chang' E-1 (CE-1) lunar orbiter is a 4-frequency microwave radiometer, and it is mainly used to obtain the brightness temperature (TB) of the lunar surface, from which the thickness, temperature, dielectric constant and other related properties of the lunar regolith can be derived. The working mode of the CE-1 MRM, the ground calibration (including the official calibration coefficients), as well as the acquisition and processing of the raw data are introduced. Our data analysis shows that TB increases with increasing frequency, decreases towards the lunar poles and is significantly affected by solar illumination. Our analysis also reveals that the main uncertainty in TB comes from ground calibration. (research papers)

  9. 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.

  10. Study of resolution and linearity in LaBr3: Ce scintillator through digital-pulse processing

    International Nuclear Information System (INIS)

    Advent of digital pulse processing has led to a paradigm shift in pulse processing techniques by replacing analog electronics processing chain with equivalent algorithms acting on pulse profiles digitized at high sampling rates. In this paper, we have carried out offline digital pulse processing of Cerium-doped Lanthanum bromide scintillator (LaBr3: Ce) detector pulses, acquired using CAEN V1742 VME digitizer module. Algorithms have been written to approximate the functioning of peak sensing analog-to-digital convertor (ADC) and charge-to-digital convertor (QDC). Energy dependence of resolution and energy linearity of LaBr3: Ce scintillator detector has been studied by utilizing aforesaid algorithms

  11. Digital processing of signals from LaBr3:Ce scintillation detectors

    International Nuclear Information System (INIS)

    In this paper, we report on the results of digital signal processing of LaBr3(Ce) detectors. The photomultiplier (PMT) output signals from two cylindrical LaBr3(Ce) detectors (1.5'' diameter and 2'' tall) were directly digitized with an ultrafast digitizer (sampling rate up to 4 GSample/s and 10-bits resolution) and the energy and timing information were extracted through offline analysis of the pulses. It is shown that at high sampling rates (4 GS/s) a simple integration of pulses is sufficient to reproduce the analogue energy resolution of the detectors (3.5% at 662 keV energy) and by employing a digital version of constant-fraction discrimination (CFD) timing a time resolution of 240 ps (FWHM) is achieved at the energy lines of 60Co. The effects of pulse sampling rate were studied, indicating a degradation of the performance of the detectors with reducing the pulse sampling rate. In particular, it was found that at sampling rates below 1 GS/s, the digital timing can be limited by the aliasing error. By using an anti-aliasing filter, a time resolution of 375 ps (FWHM) and an energy resolution of 3.5% at 662 keV were achieved with a sampling rate of 500 MS/s

  12. Digital processing of signals from LaBr3:Ce scintillation detectors

    Science.gov (United States)

    Nakhostin, M.; Podolyak, Zs; Regan, P. H.

    2014-12-01

    In this paper, we report on the results of digital signal processing of LaBr3(Ce) detectors. The photomultiplier (PMT) output signals from two cylindrical LaBr3(Ce) detectors (1.5'' diameter and 2'' tall) were directly digitized with an ultrafast digitizer (sampling rate up to 4 GSample/s and 10-bits resolution) and the energy and timing information were extracted through offline analysis of the pulses. It is shown that at high sampling rates (4 GS/s) a simple integration of pulses is sufficient to reproduce the analogue energy resolution of the detectors (3.5% at 662 keV energy) and by employing a digital version of constant-fraction discrimination (CFD) timing a time resolution of 240 ps (FWHM) is achieved at the energy lines of 60Co. The effects of pulse sampling rate were studied, indicating a degradation of the performance of the detectors with reducing the pulse sampling rate. In particular, it was found that at sampling rates below 1 GS/s, the digital timing can be limited by the aliasing error. By using an anti-aliasing filter, a time resolution of 375 ps (FWHM) and an energy resolution of 3.5% at 662 keV were achieved with a sampling rate of 500 MS/s.

  13. Data processing and initial results from the CE-3 Extreme Ultraviolet Camera

    International Nuclear Information System (INIS)

    The Extreme Ultraviolet Camera (EUVC) onboard the Chang'e-3 (CE-3) lander is used to observe the structure and dynamics of Earth's plasmasphere from the Moon. By detecting the resonance line emission of helium ions (He+) at 30.4 nm, the EUVC images the entire plasmasphere with a time resolution of 10 min and a spatial resolution of about 0.1 Earth radius (RE) in a single frame. We first present details about the data processing from EUVC and the data acquisition in the commissioning phase, and then report some initial results, which reflect the basic features of the plasmasphere well. The photon count and emission intensity of EUVC are consistent with previous observations and models, which indicate that the EUVC works normally and can provide high quality data for future studies

  14. 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

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. Energy migration processes in undoped and Ce-doped multicomponent garnet single crystals scintillators

    Czech Academy of Sciences Publication Activity Database

    Bartosiewicz, Karol; Babin, Vladimir; Kamada, K.; Yoshikawa, A.; Nikl, Martin

    2015-01-01

    Roč. 166, Oct (2015), s. 117-122. ISSN 0022-2313 R&D Projects: GA ČR GAP204/12/0805 EU Projects: European Commission(XE) 316906 - LUMINET Institutional support: RVO:68378271 Keywords : multicomponent garnets * Ce3+ * Luminescence * Energy transfer Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.719, year: 2014

  20. Effects of Zr/Ce molar ratio and water content on thermal stability and structure of ZrO2–CeO2 mixed oxides prepared via sol–gel process

    International Nuclear Information System (INIS)

    Highlights: ► Tetragonal t″ phase was stabilized in Zr0.5Ce0.5O2 solid solution at temperature as high as 1000 °C. ► Specific surface area of powders decreased with the increase of water addition and the Ce content. ► The single stable phase was controlled by adjusting the volume ratio of water and ethanol. ► Tetragonal (t″) phase dissociated into cubic and tetragonal (t′) phases at 1200 °C. -- Abstract: ZrO2–CeO2 mixed oxides were synthesized via sol–gel process. Thermal stability, structure and morphology of samples were investigated by powder X-ray diffraction, FT-Raman spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. In this approach, the solvent composition and Zr/Ce molar ratio have great influences on the structure and morphology of final products. With decreasing water content in the mixed solvent, specific surface area of powders increased and the single tetragonal phase was obtained. Only when the volume ratio of water and ethanol and the Zr/Ce molar ratio were 1:1, tetragonal t″-Zr0.5Ce0.5O2 could be stabilized in powders at temperature as high as 1000 °C. Meanwhile, tetragonal (t′) and (t″) phases coexisted in Zr0.5Ce0.5O2 solid solution without peak splitting after calcination at 1100 °C, further transforming into cubic and tetragonal (t′) phases at 1200 °C. The effective activation energy for Zr0.5Ce0.5O2 nanocrystallite growth during annealing is about 5.24 ± 0.15 kJ/mol.

  1. 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

  2. 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, ...

  3. A specific Ce oxidation process during sorption of rare earth elements on biogenic Mn oxide produced by Acremonium sp. strain KR21-2

    Science.gov (United States)

    Tanaka, Kazuya; Tani, Yukinori; Takahashi, Yoshio; Tanimizu, Masaharu; Suzuki, Yoshinori; Kozai, Naofumi; Ohnuki, Toshihiko

    2010-10-01

    Sorption of rare earth elements (REEs) and Ce oxidation on natural and synthetic Mn oxides have been investigated by many researchers. Although Mn(II)-oxidizing microorganisms are thought to play an important role in the formation of Mn oxides in most natural environments, Ce oxidation by biogenic Mn oxide and the relevance of microorganisms to the Ce oxidation process have not been well understood. Therefore, in this study, we conducted sorption experiments of REEs on biogenic Mn oxide produced by Acremonium sp. strain KR21-2. The distribution coefficients, Kd(REE), between biogenic Mn oxide (plus hyphae) and 10 mmol/L NaCl solution showed a large positive Ce anomaly and convex tetrad effect variations at pH 3.8, which was consistent with previous works using synthetic Mn oxide. The positive Ce anomaly was caused by oxidation of Ce(III) to Ce(IV) by the biogenic Mn oxide, which was confirmed by analysis of the Ce L III-edge XANES spectra. With increasing pH, the positive Ce anomaly and convex tetrad effects became less pronounced. Furthermore, negative Ce anomalies were observed at a pH of more than 6.5, suggesting that Ce(IV) was stabilized in the solution (HPLC-ICP-MS showed that some fractions of REEs in the filtrates (<0.2 μm) after sorption experiments were bound to organic molecules (40 and <670 kDa fractions), which were possibly released from hyphae. A line of our data indicates that the negative Ce anomalies under circumneutral pH conditions arose from Ce(III) oxidation on the biogenic Mn oxide and subsequent complexation of Ce(IV) with organic ligands. The suppression of tetrad effects is also explained by the complexation of REEs with organic ligands. The results of this study demonstrate that the coexistence of the biogenic Mn oxide and hyphae of strain KR21-2 produces a specific redox chemistry which cannot be explained by inorganic species.

  4. 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

  5. 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

  6. Experimental insights on the electron transfer and energy transfer processes between Ce{sup 3+}-Yb{sup 3+} and Ce{sup 3+}-Tb{sup 3+} in borate glass

    Energy Technology Data Exchange (ETDEWEB)

    Sontakke, Atul D., E-mail: sontakke.atul.55a@st.kyoto-u.ac.jp; Katayama, Yumiko; Tanabe, Setsuhisa [Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501 (Japan); Ueda, Jumpei [Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501 (Japan); Delft University of Technology, Faculty of Applied Science, Department of Radiation Science and Technology (FAME-LMR), 2629 JB Delft (Netherlands); Dorenbos, Pieter [Delft University of Technology, Faculty of Applied Science, Department of Radiation Science and Technology (FAME-LMR), 2629 JB Delft (Netherlands)

    2015-03-30

    A facile method to describe the electron transfer and energy transfer processes among lanthanide ions is presented based on the temperature dependent donor luminescence decay kinetics. The electron transfer process in Ce{sup 3+}-Yb{sup 3+} exhibits a steady rise with temperature, whereas the Ce{sup 3+}-Tb{sup 3+} energy transfer remains nearly unaffected. This feature has been investigated using the rate equation modeling and a methodology for the quantitative estimation of interaction parameters is presented. Moreover, the overall consequences of electron transfer and energy transfer process on donor-acceptor luminescence behavior, quantum efficiency, and donor luminescence decay kinetics are discussed in borate glass host. The results in this study propose a straight forward approach to distinguish the electron transfer and energy transfer processes between lanthanide ions in dielectric hosts, which is highly advantageous in view of the recent developments on lanthanide doped materials for spectral conversion, persistent luminescence, and related applications.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Radio- and thermaluminescence and energy transfer processes in Ce 3+ (Tb 3+ )-doped photosphate scintillating glasses

    Czech Academy of Sciences Publication Activity Database

    Nikl, Martin; Mareš, Jiří A.; Mihóková, Eva; Nitsch, Karel; Solovieva, Natalia; Babin, V.; Krasnikov, A.; Zazubovich, S.; Martini, M.; Vedda, A.

    2001-01-01

    Roč. 33, - (2001), s. 593-596. ISSN 1350-4487 R&D Projects: GA MŠk ME 462 Grant ostatní: NATO(XX) sfp 973510 Institutional research plan: CEZ:AV0Z1010914 Keywords : scintillator * phosphate glasses * transfer processes * energy migration Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.003, year: 2001

  12. Deposition of CeO 2/YSZ buffer layer on Hastelloy substrates for MOD process of YBa 2Cu 3O 7- x film

    Science.gov (United States)

    Fuji, Hiroshi; Honjo, Tetsuji; Nakamura, Yuichi; Izumi, Teruo; Takeshi, Araki; Hirabayashi, Izumi; Shiohara, Yuh; Iijima, Yasuhiro; Takeda, Kaoru

    2001-08-01

    Trifluoroacetate metalorganic deposition (TFA-MOD) process is expected as a low cost process for mass production of coated conductors because it is a non-vacuum process. In order to apply the technique to fabrication of coated conductors, suitable buffer layers have to be considered to achieve a high orientation of superconducting layer and prevention of the reaction with metal substrate. The combination of CeO 2 on IBAD-YSZ is considered as an effective buffer for TFA-MOD process expecting to satisfy a high acid resistivity and high crystal grain alignment. The CeO 2 buffer layer was deposited on IBAD-YSZ/Hastelloy substrates by RF magnetron sputtering. From XRD analysis, the CeO 2 buffer layer showed very good in-plane alignment on YSZ-IBAD buffer layer. In a holding time of 1 h, the suitable maximum heat treatment temperature was found to be from 750°C to 775°C for TFA-Y123 on metal substrate. The Jc- B property of Y123 on CeO 2/YSZ/Hastelloy shows the Jc values of 1.4 MA/cm 2 at 77.3 K, 0 T and more than 10 5 A/cm 2 at 77.3 K, 2 T. The high performance under high magnetic field was confirmed.

  13. 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.

  14. 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).

  15. 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.

  16. Violet-blue luminescence from hafnium oxide layers doped with CeCl3 prepared by the spray pyrolysis process

    International Nuclear Information System (INIS)

    HfO2:CeCl3 coatings were deposited by the spray pyrolysis method employing hafnium dichloride oxide and CeCl3 dissolved in deionized water (18 MΩ/cm). The room temperature photoluminescence characteristics of the HfO2:CeCl3 films were studied as a function of the deposition parameters such as doping concentrations and substrate temperature. The presence of two different Ce3+ centres in HfO2 is detected from photoluminescence measurements. A reduction of the luminescence intensity is observed with an increase of both the CeCl3 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 HfO2. 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.)

  17. 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%.

  18. 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.

  19. 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

  20. 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.

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

    CERN Document Server

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

    2009-01-01

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

  2. Isolation of CeLu2 N@Ih -C80 through a Non-Chromatographic, Two-Step Chemical Process and Crystallographic Characterization of the Pyramidalized CeLu2 N within the Icosahedral Cage.

    Science.gov (United States)

    Stevenson, Steven; Thompson, Hannah R; Arvola, Kristine D; Ghiassi, Kamran B; Olmstead, Marilyn M; Balch, Alan L

    2015-07-13

    By combining two chemical methods of purification, 4 mg of purified CeLu2 N@C80 was readily isolated from 500 mg of carbon soot extract without the use of recycling HPLC, a method which has previously been necessary to obtain pure samples of endohedral fullerenes. In stage 1, CeLu2 N@C80 was selectively precipitated by virtue of its low first oxidation potential (+0.01 V) and the judicious choice of MgCl2 as the Lewis acid precipitant. For stage 2, we used a stir and filter approach (SAFA), which employed the electron-rich NH2 groups immobilized on silica gel to selectively bind residual endohedrals and higher cage fullerenes that were contaminants from stage 1. Crystallographic analysis of CeLu2 N@C80 in the co-crystal CeLu2 N@Ih -C80 ⋅Ni(octaethylporphyrin)⋅2(toluene) reveals that the Ih -C80 cage is present with a pyramidalized CeLu2 N unit inside. PMID:26059441

  3. 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。

  4. Diesel/biodiesel soot oxidation with CeO2 and CeO2-ZrO2- modified cordierites: a facile way of accounting for their catalytic ability in fuel combustion processes

    International Nuclear Information System (INIS)

    CeO2 and mixed CeO2-ZrO2 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)

  5. 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)

  6. Electrochemical aspects of Ce+3 / Ce system in Flinak

    International Nuclear Information System (INIS)

    The voltammetric electrodeposition of cerium has been studied on three types of substrates - Ag, W and vitreous Carbon with the aim of know the mechanisms of the process. The Flinak - Ce F3 melt was used, with temperature range of 500-850O C. No alkaline metals co deposition was observed. (author)

  7. Electrochemical properties of Atomic layer deposition processed CeO2 as a protective layer for the molten carbonate fuel cell cathode

    International Nuclear Information System (INIS)

    Highlights: • Nano-structured CeO2-coated Ni by Atomic Layer Deposition, crystalline as-deposited. • Progressive transformation into a complex surface stable in molten carbonates. • Lower Ni solubility with CeO2 protective coating. • Feasibility of CeO2 coating in Molten Carbonate Fuel Cell cathode conditions. - Abstract: In order to increase the lifetime and performance of the molten carbonate fuel cell, it is compulsory to control the corrosion and dissolution of the state of the art porous nickel oxide cathode. A protective coating constituted by more stable oxides appears to be the best approach. Previous research on CeO2 coatings obtained by DC reactive magnetron sputtering to protect the Molten carbonate fuel cell cathode gave promising results but it was necessary to improve the coating adhesion. In this paper Atomic Layer Deposition, producing high quality, homogeneous and conformal layers, was used to obtain thin layers of CeO2 (20 nm and 120 nm) deposited over porous nickel. CeO2-Ni coated samples were tested as cathodes in Li2CO3-K2CO3 (62-38 mol %) eutectic mixture under standard cathode atmosphere (CO2/air 30:70 vol. %). Structural and morphological characterizations of the nickel coated cathode before and after electrochemical tests in the molten carbonate melt are reported together with the Open Circuit Potential evolution all over 230 h for both the bare porous nickel and the CeO2-coated samples

  8. The Doniach diagram and hydrogenation of the ternary compounds CePdIn and CePdSn

    OpenAIRE

    Chevalier, Bernard; Wattiaux, Alain; Bobet, Jean-Louis

    2006-01-01

    The process of hydrogenation of the antiferromagnetic compounds CePdIn and CePdSn has been studied. Investigation of the new hydrides CePdInH and CePdSnH by means of x-ray powder diffraction reveals that they adopt the same crystal symmetry as the original intermetallic but the unit cell volume increases during the hydrogenation. Magnetization, electrical resistivity, thermoelectric power and 119Sn Mössbauer spectroscopy measurements reveal that CePdInH and CePdSnH order antiferromagnetically...

  9. 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

  10. 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

  11. 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.)

  12. 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.

  13. 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.

  14. 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...

  15. 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...

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

    International Nuclear Information System (INIS)

    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

  17. 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.

  18. Radiative energy transfer in ZnAl2O4:0.1% Ce3+, x% Eu3+ nanophosphor synthesized by sol–gel process

    International Nuclear Information System (INIS)

    Zinc aluminate (ZnAl2O4) hosts and 0.1% Ce3+, x% Eu3+ co-activated ZnAl2O4 phosphor were successfully prepared at a relatively low temperature (~80 °C) using the sol–gel method. The co-activator (Eu3+) concentration was varied in the range of 0≤x≤2 mol%, while the 0.1% Ce3+ was kept constant. The X-ray diffraction (XRD) data revealed that all annealed samples consisted of the pure cubic ZnAl2O4 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 Eu3+ 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 Eu3+ 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, Ce3+ or Eu3+ ions. The incorporation of the co-activator (Eu3+) at higher concentration resulted in radiative energy transfer from Ce3+→Eu3+. The CIE colour coordinates showed a shift from the blue to orange region as the Eu3+ concentration was increased

  19. 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

  20. 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

  1. 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.

  2. Ce(III)/Ce(IV) in methanesulfonic acid as the positive half cell of a redox flow battery

    International Nuclear Information System (INIS)

    The characteristics of the Ce(III)/Ce(IV) redox couple in methanesulfonic acid were studied at a platinum disk electrode (0.125 cm2) over a wide range of electrolyte compositions and temperatures: cerium (III) methanesulfonate (0.1-1.2 mol dm-3), methanesulfonic acid (0.1-5.0 mol dm-3) and electrolyte temperatures (295-333 K). The cyclic voltammetry experiments indicated that the diffusion coefficient of Ce(III) ions was 0.5 x 10-6 cm2 s-1 and that the electrochemical kinetics for the oxidation of Ce(III) and the reduction of Ce(IV) was slow. The reversibility of the redox reaction depended on the electrolyte composition and improved at higher electrolyte temperatures. At higher methanesulfonic acid concentrations, the degree of oxygen evolution decreased by up to 50% when the acid concentration increased from 2 to 5 mol dm-3. The oxidation of Ce(III) and reduction of Ce(IV) were also investigated during a constant current batch electrolysis in a parallel plate zinc-cerium flow cell with a 3-dimensional platinised titanium mesh electrode. The current efficiencies over 4.5 h of the process Ce(III) to Ce(IV) and 3.3 h electrolysis of the reverse reaction Ce(IV) to Ce(III) were 94.0 and 97.6%, respectively. With a 2-dimensional, planar platinised titanium electrode (9 cm2 area), the redox reaction of the Ce(III)/Ce(IV) system was under mass-transport control, while the reaction on the 3-dimensional mesh electrode was initially under charge-transfer control but became mass-transport controlled after 2.5-3 h of electrolysis. The effect of the side reactions (hydrogen and oxygen evolution) on the current efficiencies and the conversion of Ce(III) and Ce(IV) are discussed.

  3. 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.; Pryds, Nini; Linderoth, Søren; Schou, Jørgen; Lippert, T.

    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...... composition is affected by the applied fluence. At a low fluence, 0.5 J/cm², a congruent transfer is obtained while a relative Gd enrichment results for substantially higher fluences (3.5-5.5 J/cm²)....

  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.; Pryds, Nini; Linderoth, Søren; Schou, Jørgen; Lippert, T.

    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...... composition is affected by the applied fluence. At a low fluence, 0.5 J/cm², a congruent transfer is obtained while a relative Gd enrichment results for substantially higher (3.5-5.5 J/cm²)....

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

    DEFF Research Database (Denmark)

    For solving partial differential equations (or distributed dynamic systems), the method of lines (MOL) and the space-time conservation element and solution element (CE/SE) method are compared in terms of computational efficiency, solution accuracy and stability. Several representative examples...... are obtained in a stable manner in most cases. However, a remedy is still needed for PDEs with a stiff source term. It seems to be out of date to use the MOL for solving PDEs containing steep moving fronts because of the dissipation error caused by spatial discretization and time consuming...

  6. Characteristics of 5 mol% Ce3+-doped barium titanate nanowires prepared by a combined route involving sol–gel chemistry and polycarbonate membrane-templated process

    International Nuclear Information System (INIS)

    Ba0.95Ce0.05Ti0.9875O3 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 Ba0.95Ce0.05Ti0.9875O3 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

  7. Localization Effect on Pt-Loaded Ce0.5Zr0.5O2 Nanoparticles Inserted Into Mesoporous SBA-16 by Hydrothermal Processing.

    Science.gov (United States)

    Yotou, Hiroaki; Okamoto, Takumi; Ito, Miho; Sekino, Tohru; Tanaka, Shun-Ichiro

    2015-09-01

    We succeeded to use hydrothermal treatment to insert prefabricated Pt-loaded Ce0.5Zr0.5O2 (PtCZ) nanoparticles into the mesopores of the SBA-16 mesoporous silica without disordering of the mesoporous structure. Samples prepared by the hydrothermal treatment exhibited superior oxygen storage capacity compared to that of simple dry mixed sample. The oxygen storage capacity of the hydrothermally treated PtCZ is attributed to the localized PtCZ nanoparticles inside the mesopores of the SBA-16. FTIR analysis suggested that the PtCZ nanoparticles inside the mesopores possess the Si-O-Zr linkages that are bonded to the inner walls of the SBA-16 host. This linkage is the key reason for the superior oxygen storage capacity of PtCZ localized in the mesopores by hydrothermal treatment. It is considered that the formation of the Si-O-Zr linkage in the hydrothermally treated samples resulted in crystalline distortions of Ce0.5Zr0.5O2 nanoparticles inside the mesopores, and which contribute to enhance the oxygen storage capacity of PtCZ. PMID:26716294

  8. Electro-regeneration of Ce(IV) in real spent Cr-etching solutions.

    Science.gov (United States)

    Chen, Te-San; Huang, Kuo-Lin

    2013-11-15

    This paper presents the electro-regeneration of Ce(IV) in real (hazardous) spent thin-film transistor liquid-crystal display (TFT-LCD) Cr-etching solutions. In addition to Ce(III)>Ce(IV) in diffusivity, a quasi-reversible behavior of Ce(III)/Ce(IV) was observed at both boron-doped diamond (BDD) and Pt disk electrodes. The Ce(IV) yield on Pt increased with increasing current density, and the best current efficiency (CE) was obtained at 2A/2.25 cm(2). The performance in terms of Ce(IV) yield and CE of tested anodes was in order BDD>Pt>dimensional stable anode (DSA). At 2A/2.25 cm(2) on Pt and 40 °C for 90 min, the Ce(IV) yield, CE and apparent rate constant (k) for Ce(III) oxidation were 81.4%, 21.8% and 3.17 × 10(-4) s(-1), respectively. With the increase of temperature, the Ce(IV) yield, CE, and k increased (activation energy = 10.7 kJ/mol), but the specific electricity consumption decreased. The Neosepta CMX membrane was more suitable than Nafion-117 and Nafion-212 to be used as the separator of the Ce(IV) regeneration process. The obtained parameters are useful to design divided batch reactors for the Ce(IV) electro-regeneration in real spent Cr-etching solutions. PMID:24140527

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

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

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

  10. 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

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

    International Nuclear Information System (INIS)

    Two different coatings based of iron aluminide on 12% Cr ferritic-martensitic steel have been developed by CVD-FBR technique, which is modified by the introduction of Ce and La as powder in the fluidized bed. These elements change the gaseous environment, which composition is predicted by a thermodynamic approximation. Partial pressures of all gaseous precursors are drastically modified; in consequence AlCl has the highest partial pressure in the system leading to an increment of the coating thickness. Coatings are composed by (Fe, Cr)2Al5 or (Fe, Cr)2Al5 and (Fe, Cr)Al3 intermetallic phases. On the other hand, steam oxidation test at 650 deg. C was performed in order to observe improvements in the HCM12A oxidation resistant

  12. 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.

  13. 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)

  14. Crystal structure and solution species of Ce(III) and Ce(IV) formates: from mononuclear to hexanuclear complexes.

    Science.gov (United States)

    Hennig, Christoph; Ikeda-Ohno, Atsushi; Kraus, Werner; Weiss, Stephan; Pattison, Philip; Emerich, Hermann; Abdala, Paula M; Scheinost, Andreas C

    2013-10-21

    Cerium(III) and cerium(IV) both form formate complexes. However, their species in aqueous solution and the solid-state structures are surprisingly different. The species in aqueous solutions were investigated with Ce K-edge EXAFS spectroscopy. Ce(III) formate shows only mononuclear complexes, which is in agreement with the predicted mononuclear species of Ce(HCOO)(2+) and Ce(HCOO)2(+). In contrast, Ce(IV) formate forms in aqueous solution a stable hexanuclear complex of [Ce6(μ3-O)4(μ3-OH)4(HCOO)x(NO3)y](12-x-y). The structural differences reflect the different influence of hydrolysis, which is weak for Ce(III) and strong for Ce(IV). Hydrolysis of Ce(IV) ions causes initial polymerization while complexation through HCOO(-) results in 12 chelate rings stabilizing the hexanuclear Ce(IV) complex. Crystals were grown from the above-mentioned solutions. Two crystal structures of Ce(IV) formate were determined. Both form a hexanuclear complex with a [Ce6(μ3-O)4(μ3-OH)4](12+) core in aqueous HNO3/HCOOH solution. The pH titration with NaOH resulted in a structure with the composition [Ce6(μ3-O)4(μ3-OH)4(HCOO)10(NO3)2(H2O)3]·(H2O)9.5, while the pH adjustment with NH3 resulted in [Ce6(μ3-O)4(μ3-OH)4(HCOO)10(NO3)4]·(NO3)3(NH4)5(H2O)5. Furthermore, the crystal structure of Ce(III) formate, Ce(HCOO)3, was determined. The coordination polyhedron is a tricapped trigonal prism which is formed exclusively by nine HCOO(-) ligands. The hexanuclear Ce(IV) formate species from aqueous solution is widely preserved in the crystal structure, whereas the mononuclear solution species of Ce(III) formate undergoes a polymerization during the crystallization process. PMID:24090406

  15. CE-BEMS

    DEFF Research Database (Denmark)

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

    2016-01-01

    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...

  16. 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.

  17. Properties of LuAP: CE scintillator containing intentional impurities

    CERN Document Server

    Petrosyan, A G; Ovanesyan, K; Lecoq, Paul; Auffray, Etiennette; Trummer, Julia; Kronberger, Matthias; Pédrini, C; Dujardin, C; Anfre, P

    2007-01-01

    Single crystals of LuAP:Ce and LuYAP(Lu*70%):Ce co-doped with tetravalent (Hf and Zr) and pentavalent (Ta) ions were grown from melts by the Bridgman process. Underlying absorption, slope of the optical edge and transmission in the range of emission were compared to those of LuAP:Ce crystals. Absorption coefficients at 260 nm less than 2 cm−1 have been recorded in LuAP:Ce crystals containing tetravalent ions that are lower than the corresponding figures (5–6 cm−1) measured in undoped LuAP. At high concentrations of added impurities, despite of suppression of the parasitic underlying absorption below 300 nm, the slope of the optical edge and transmission in the range of emission are seriously damaged. Scintillation parameters of crystals with added impurities are compared to those of LuAP:Ce.

  18. 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.

  19. 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

  20. 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.

  1. O- centers in LuAG:Ce,Mg ceramics

    International Nuclear Information System (INIS)

    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- centers. The g -tensor components turn out to be g perpendicular to = 2.0103, and g parallel = 2.0023, revealing the axial symmetry of these defects. Mg-perturbed variants of O- 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- centers in the scintillation process is discussed. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. 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.

  3. 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.

  4. 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.

  5. 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...

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

    OpenAIRE

    Lawler, J. E.; Sneden, C.; Cowan, J. J.; Ivans, I. I.; Hartog, E.A. den

    2009-01-01

    Recent radiative lifetime measurements accurate to +/- 5% using laser-induced fluorescence (LIF) on 43 even-parity and 15 odd-parity levels of Ce II have been combined with new branching fractions measured using a Fourier transform spectrometer (FTS) to determine transition probabilities for 921 lines of Ce II. This improved laboratory data set has been used to determine a new solar photospheric Ce abundance, log epsilon = 1.61 +/- 0.01 (sigma = 0.06 from 45 lines), a value in excellent agree...

  7. 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.

  8. Isolation of CeLu2N at Ih-C80 through a Non-Chromatographic, Two-Step Chemical Process and Crystallographic Characterization of the Pyramidalized CeLu2N within the Icosahedral Cage

    OpenAIRE

    Stevenson, S.; Thompson, HR; Arvola, KD; Ghiassi, KB; Olmstead, MM; Balch, AL

    2015-01-01

    © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. By combining two chemical methods of purification, 4mg of purified CeLu2N at C80 was readily isolated from 500mg of carbon soot extract without the use of recycling HPLC, a method which has previously been necessary to obtain pure samples of endohedral fullerenes. In stage1, CeLu2N at C80 was selectively precipitated by virtue of its low first oxidation potential (+0.01V) and the judicious choice of MgCl2 as the Lewis acid precipitant. For st...

  9. 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.

  10. 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.

  11. EMERGInG RISKS In SMART PROCESS InDUSTRY CRAnES SURVEY: SAF€RA RESEARCH PROJECT SPRInCE

    Directory of Open Access Journals (Sweden)

    Vesna Spasojević Brkić

    2015-11-01

    Full Text Available Current accident theories show that the solution to avoid human error cannot be based on focusing only on the correction of operators’ behavior, but needs certain innovation that will help to keep an error away. Since, as evidenced by several incident surveys, cranes are the most dangerous equipment in industrial and construction sites and human error is the most frequent cause of accidents, in this frame the crane navigation system is an important and challenging component, with a great potential for safety improvement. However, as the emerging and rapid development of new technologies aims improving the working conditions and environment through solutions regarding existing well-known problems in occupational safety, their implementation also could lead to emerging hazards and risks that must be taken into account and managed. Based on these facts, SPRINCE (Smart PRocess INdustry CranEs project aims implementing a real-time object detection solution, which deals with cranes’ tracking systems and incorporates visual feedback, developing and implementing an innovative tool for evaluation of organizational and human (operator-specific factors. These factors will be included in the risk indicators of the implemented real-time object detection solution using case studies approach.

  12. 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...

  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. Characterizations of electrodeposited Ni–CeO2 nanocomposite coatings

    International Nuclear Information System (INIS)

    The expansion of current machinery requires metallic materials with better surface properties. In the present investigation, CeO2 reinforced nickel nanocomposite coatings were deposited on mild steel substrate by direct current electrodeposition process employing nickel acetate bath. The effect of incorporation of CeO2 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–CeO2 nanocomposite coatings. It has been observed that, the presence of CeO2 nanoparticles favours the [111] and [200] texture of nickel matrix. The co-deposition of CeO2 nanoparticles with nickel was found to be favoured at applied current density of 8 A dm−2. The micro hardness values of the nickel nanocomposite coatings (725 HV) was higher than that of pure nickel (265 HV).The decrease in Icorr values and increase in Constant Phase Element values were investigated in 3.5% NaCl solution which showed the higher corrosion resistant nature of Ni–CeO2 coatings. - Highlights: • Ni–CeO2 composite coatings have electrodeposited from eco-friendly acetate bath. • Inclusion of CeO2 in the composite coating has refined the crystallite size. • Micro hardness values have increased with CeO2 content in the composite coatings. • The negative shift of Ecorr confirming cathodic protective nature of coatings

  15. 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}.

  16. Heat-treatment-induced luminescence degradation in Tb3+-doped CePO4 nanorods

    International Nuclear Information System (INIS)

    CePO4:Tb nanorods were synthesized via a simple wet-chemical route. The as-synthesized CePO4:Tb nanorods present high photoluminescence efficiency due to an efficient energy transfer form Ce3+ to Tb3+. However, heat treatment at 150 deg. C in air leads to a significant decrease of photoluminescence. X-ray photoelectron spectroscopy and excitation spectra revealed the oxidation of Ce3+ to Ce4+ in the heat-treatment process, which should be responsible for significant photoluminescence degradation due to the breakage of Ce3+→Tb3+ energy transfer. This conclusion is further supported by atmosphere and size effects of photoluminescence of CePO4:Tb under the heat treatment.

  17. 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

  18. A simple modeling study of the Ce(IV) regeneration in sulfuric acid solutions

    International Nuclear Information System (INIS)

    Highlights: → The simple model of electrochemical regeneration of Ce(IV) in sulfuric acid solutions at PbO2 anode has been developed. → The study showed that Ce(SO4)2- is the kinetically active species and the decomposition of surface complex of Ce(IV) at the anode surface is the rate determining step. → There is no relation between current density and concentrations of ions participating in the anodic reaction. - Abstract: The electrochemical regeneration of Ce(IV) for mediated electrochemical oxidation in sulfuric acid media was investigated in an electrolytic membrane reactor. A simple kinetic model was developed to analyze and simulate the regeneration of Ce(IV) in the electrolysis process. The model was based on the Faraday's law and the mass balance of components in the reactor. The key operating conditions of the initial electrolyte concentration and the regeneration time were analyzed. It was found that the simulating model agreed well with the experimental data for regeneration of Ce(IV). Experimental results showed that Ce(SO4)2- is the active species. The decomposition of surface complex of Ce(IV) at the anode surface is the rate determining step. Constant-current electrolysis shows that the high proton and Ce(III) concentrations are electrochemically favorable for the regeneration of Ce(IV). The current efficiency for regeneration of Ce(IV) decrease obviously with the increase of SO42- concentration from 0.8 to 2.4 mol/L.

  19. 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.

  20. Lattice dynamics of γ--Ce

    International Nuclear Information System (INIS)

    The phonon and magnetic measurements described in the thesis produced the following significant results concerning the lattice dynamical and magnetic properties of γ-Ce. The phonon spectrum is relatively soft, which is consistent with results obtained for CeSn3. The L [110] and T [111] branches of the dispersion curve are anomalous. The C11 and C44 elastic constants are quite close in value. No discrete magnetic excitations were observed. The magnetic scattering is qualitatively similar to the results from Ce0.74Th0.26, however, GAMMA/sub Ce/ less than GAMMA/sub Ce-Th/. The various lattice dynamical and magnetic similarities among γ-Ce, CeSn3, and Ce0.74Th0.26 are mixed valence compounds. Therefore, a complete theoretical description of the observed properties of Ce and its compounds may provide a basis for understanding a whole class of mixed valence materials

  1. Utilization of high specific surface area CuO-CeO2 catalysts for high temperature processes of hydrogen production: steam re-forming of ethanol and methane dry re-forming.

    Science.gov (United States)

    Djinović, Petar; Batista, Jurka; Cehić, Benis; Pintar, Albin

    2010-03-25

    CuO-CeO(2) mixed oxide catalysts with 10, 15, and 20 mol % CuO content were prepared by the hard template method using KIT-6 silica as a template. The applied synthesis method yields solids with BET surface area in excess of 147 m(2)/g, highly porous nanocrystalline CeO(2) morphology and dispersion of CuO phase between 28 and 40%, corresponding to CuO particle size between 1.3 and 1.9 nm. Increasing the CuO content caused a decrease in dispersion of this phase and a further decrease of surface acid site abundance, determined by NH(3) chemisorption/TPD method, but improved the reducibility extent of CeO(2) (14.5, 16.1 and 24.5% for CuCe10, CuCe15, and CuCe20 catalyst, respectively) and oxygen mobility of prepared powders. It was discovered during ethanol steam re-forming experiments that increasing CuO content is favorable in terms of ethanol conversion but also causes quicker catalyst deactivation, primarily as a result of sintering and loss of CuO dispersion. Reaction temperatures in excess of 550 degrees C strongly promoted ethanol dehydratation reaction, leading to a rise in methane production and extensive coking of the catalyst surface. Coking was slower in the case of CuO-CeO(2) catalysts with a higher CuO content as a result of lower acid site abundance and more pronounced oxygen mobility. Temperatures in excess of 450 degrees C are required for any noticeable CO(2) and CH(4) conversion in methane dry re-forming reaction over CuO-CeO(2) materials. The examined materials displayed steady performance during stability tests at a reaction temperature of 650 degrees C, with catalysts containing 15 and 20 mol % CuO exhibiting the highest activity. Additionally, very low amounts of carbon were deposited on spent catalyst samples. PMID:19883056

  2. High efficiency energy transfer in Ce,Tb co-doped silica prepared by sol-gel method

    International Nuclear Information System (INIS)

    Amorphous Ce,Tb co-doped silica (SiO2) was prepared using the sol-gel method with the aim of studying the energy transfer from Ce to Tb ions. It was initially found that adding Ce reduced the Tb emission intensity, implying that energy transfer did not occur. In fact, the Ce single doped sample exhibited very poor emission. Ultraviolet-visible diffuse reflectance measurements displayed the signature of non-luminescent Ce4+ rather than Ce3+ ions. We therefore annealed the samples in a reducing atmosphere of 4% hydrogen in argon gas at 1000 °C. The reduced Ce single doped samples exhibited bright luminescence and the diffuse reflectance measurements now showed the characteristic of Ce3+ ions. The reduced Ce,Tb co-doped samples excited at the Ce absorption wavelength gave characteristic Tb emission (with negligible Ce emission), indicating that very efficient energy transfer from Ce to Tb was achieved. For samples containing 1 mol% Tb, the maximum luminescence was found when co-doping with 0.5 mol% Ce. Using such co-doped silica samples exhibiting energy transfer, it is possible to obtain effective luminescence from the Tb3+ ions via excitation of Ce3+ ions at 325 nm, instead of exciting the Tb3+ ions directly which requires a shorter wavelength of about 227 nm. - Highlights: ► Vast improvement in energy transfer from Ce to Tb in sol-gel silica. ► Tb doped silica effectively excited at 325 nm instead of 227 nm after Ce co-doping. ► Improved annealing process for sol-gel silica with Ce for luminescence applications.

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

    International Nuclear Information System (INIS)

    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 Ce4+/Ce3+. The mesoporous support increases the dispersability of the photoactive Ti4+ or Ce4+/Ce3+ 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. • Ce4+/Ce3+ 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

  4. 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.

  5. Room-temperature synthesis and characterization of porous CeO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Dewei; Masuda, Yoshitake; Ohji, Tatsuki; Kato, Kazumi [National Institute of Advanced Industrial Science and Technology (AIST), Anagahora, Shimoshidami, Moriyama-ku, Nagoya (Japan)

    2012-01-15

    CeO{sub 2} thin films with hexagonal-shaped pores were successfully prepared by a facile electrodeposition at room temperature combined with an etching process. By using electrodeposited ZnO nanorods as a soft template, the morphology, and microstructure of the CeO{sub 2} could be controlled. TEM observation indicated that as-prepared CeO{sub 2} film is composed of nanocrystals with average size of several nanometers, while XPS analysis showed the coexistence of Ce{sup 3+} and Ce{sup 4+} in the film. The photoluminescence properties of CeO{sub 2} films were measured, which showed much higher sensitivity compared to bare substrate. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Room-temperature synthesis and characterization of porous CeO2 thin films

    International Nuclear Information System (INIS)

    CeO2 thin films with hexagonal-shaped pores were successfully prepared by a facile electrodeposition at room temperature combined with an etching process. By using electrodeposited ZnO nanorods as a soft template, the morphology, and microstructure of the CeO2 could be controlled. TEM observation indicated that as-prepared CeO2 film is composed of nanocrystals with average size of several nanometers, while XPS analysis showed the coexistence of Ce3+ and Ce4+ in the film. The photoluminescence properties of CeO2 films were measured, which showed much higher sensitivity compared to bare substrate. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. 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.

  8. Collective excitations in 132Ce

    International Nuclear Information System (INIS)

    The structure of normally deformed states (β2∼0.2) in 132Ce has been investigated using EUROGAM2. Eight ΔI=2 bands and three ΔI=1 bands have been identified up to spin 40. The results are interpreted with the aid of Woods-Saxon cranking calculations which suggest a variety of triaxial shapes stabilized by specific active quasiparticle orbitals. (authors)

  9. 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.

  10. 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).

  11. Fabrication process of ionization chamber multidetector and multidetector got by this process. Procede de fabrication d'un multidetecteur a chambres d'ionisation et multidetecteur obtenu par ce procede

    Energy Technology Data Exchange (ETDEWEB)

    Tirelli, M.; Lecolant, R.; Hecquet, R.

    1986-06-20

    The multidetector ionization chamber walls are fixed one related to the others and carried together with a tool above a resin bath to polymerize. After resin hardening, the detector includes resin basis. To contain the resin bath, the realization of a mould cut in a massive resin block are been provided for. This allows for its manutention all along the process without any deterioration risk.

  12. 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.

  13. Nuclear data treatment for SAM-CE Monte Carlo calculations

    International Nuclear Information System (INIS)

    The treatment of nuclear data by the SAM-CE Monte Carlo code system is presented. The retrieval of neutron, gamma production, and photon data from the ENDF/B fils is described. Integral cross sections as well as differential data are utilized in the Monte Carlo calculations, and the processing procedures for the requisite data are summarized

  14. 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

  15. 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)

  16. 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.

  17. 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.

  18. 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.

  19. 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)

  20. Luminescence of Ce3+ doped LaPO4 nanophosphors upon Ce3+ 4f-5d and band-to-band excitation

    International Nuclear Information System (INIS)

    Luminescence spectral-kinetic studies have been performed for pure and Ce-doped LaPO4 micro- and nanosized phosphates using synchrotron radiation for the excitation within 5-20 eV energy range at T=8-300 K. Mechanisms for the excitation of Ce3+ 5d-4f emission as well as the quenching processes are discussed. The influence of surface defects has been considered to modify considerably the luminescent properties of nanosized phosphors upon the excitation in the energy range of Ce3+ 4f-5d transitions and LaPO4 host absorption

  1. 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.

  2. 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

  3. 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.

  4. Mechanical properties of Ce-TZP ceramics obtained from powders prepared by lyophilization of coprecipitated

    International Nuclear Information System (INIS)

    In this paper is shown and discussed the influence of freeze-drying process on the physical characteristics of powder as well as on the microstructural, characteristics, on tetragonal-to-monoclinic stress induced transformation and, finally, on some mechanical properties of the Ce-TZP ceramics (bending strength, Vickers hardness and fracture toughness). Powders containing different Ce O2 content were prepared by freeze-drying process and conventional drying of Ce and Zr coprecipitated hydroxides from initial chlorides. The powder characteristics show adequate compaction and sintering behavior. (author)

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

    International Nuclear Information System (INIS)

    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,Nd)Ox (a=0.547nm), hcp-(Ce,Nd)2O3 (a=0.386nm, c=0.604nm) and bcc-(Ce,Nd)2O3 (a=1.113nm). Ors of (140)(Ce,Nd)2Fe14B// (1-21)bcc-(Ce,Nd)2O3(∼3°), [001](Ce,Nd)2Fe14B// [-214]bcc-(Ce,Nd)2O3; (01-1)(Ce,Nd)2Fe14B// (101)fcc- (Ce,Nd)Ox(∼2°), [101](Ce,Nd)2Fe14B// [12-1]fcc-(Ce,Nd)Ox 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

  6. 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.

  7. 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.

  8. Preparation of FeCeOx by ultrasonic impregnation method for heterogeneous Fenton degradation of diclofenac.

    Science.gov (United States)

    Chong, Shan; Zhang, Guangming; Zhang, Nan; Liu, Yucan; Zhu, Jia; Huang, Ting; Fang, Shunyan

    2016-09-01

    FeCeOx has been successfully synthesized by ultrasonic impregnation method and applied in diclofenac removal in heterogeneous Fenton process. The effects of ultrasonic density, impregnation time, mole ratio of Fe and Ce and calcination temperature were investigated. Nitrogen adsorption/desorption, SEM, XRD, HRTEM, Raman and XPS analyses were characterized. Stability and reusability of FeCeOx were evaluated. The results indicated that 83% degradation efficiency of diclofenac was achieved by FeCeOx under the optimum preparation conditions. Fe ions were distributed uniformly in crystal structure and the solid solution structure of FeCeOx with a lattice constriction was formed. Exposed crystalline plane (200) with a relatively high surface energy may be the main reason to provide high catalytic activity of FeCeOx. Oxygen vacancies took part in catalytic process and a portion of them were oxidized after reaction. FeCeOx showed an excellent chemical stability and reusability in heterogeneous Fenton process. PMID:27150766

  9. Information System through ANIS at CeSAM

    Science.gov (United States)

    Moreau, C.; Agneray, F.; Gimenez, S.

    2015-09-01

    ANIS (AstroNomical Information System) is a web generic tool developed at CeSAM to facilitate and standardize the implementation of astronomical data of various kinds through private and/or public dedicated Information Systems. The architecture of ANIS is composed of a database server which contains the project data, a web user interface template which provides high level services (search, extract and display imaging and spectroscopic data using a combination of criteria, an object list, a sql query module or a cone search interfaces), a framework composed of several packages, and a metadata database managed by a web administration entity. The process to implement a new ANIS instance at CeSAM is easy and fast : the scientific project has to submit data or a data secure access, the CeSAM team installs the new instance (web interface template and the metadata database), and the project administrator can configure the instance with the web ANIS-administration entity. Currently, the CeSAM offers through ANIS a web access to VO compliant Information Systems for different projects (HeDaM, HST-COSMOS, CFHTLS-ZPhots, ExoDAT,...).

  10. 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.

  11. 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.

  12. 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.

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

    International Nuclear Information System (INIS)

    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 °C (in the thermostat chamber). Up to 100 °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.

  14. 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.

  15. 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.

  16. Two Ce(SO4)2.4H2O polymorphs: Crystal structure and thermal behavior

    International Nuclear Information System (INIS)

    Syntheses, crystal structures and thermal behavior of two polymorphic forms of Ce(SO4)2.4H2O are reported. The first modification, α-Ce(SO4)2.4H2O (I), crystallizes in the orthorhombic space group Fddd, with a=5.6587(1), b=12.0469(2), c=26.7201(3) A and Z=8. The second modification, β-Ce(SO4)2.4H2O (II), crystallizes in the orthorhombic space group Pnma, with a=14.6019(2), b=11.0546(2), c=5.6340(1) A and Z=4. In both structures, the cerium atoms have eight ligands: four water molecules and four sulfate groups. The mutual position of the ligands differs in (I) and (II), resulting in geometrical isomerism. Both these structures are built up by layers of Ce(H2O)4(SO4)2 held together by a hydrogen bonding network. The dehydration of Ce(SO4)2.4H2O is a two step (I) and one step (II) process, respectively, forming Ce(SO4)2 in both cases. During the decomposition of the anhydrous form, Ce(SO4)2, into the final product CeO2, intermediate xCeO2.yCe(SO4)2 species are formed. - Graphical abstract: The cerium atoms are eight-coordinated in both α-Ce(SO4)2.4H2O (I) and β-Ce(SO4)2.4H2O (II) forming slightly distorted square antiprisms, but the mutual position of the ligands differs, resulting in stereoisomerism. Both structures are built up by layers of Ce(H2O)4(SO4)2 held together by a hydrogen bonding network

  17. 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.

  18. 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 ...

  19. Unstable magnetic moments in Ce compounds

    International Nuclear Information System (INIS)

    The problems which are connected with the appearance or disappearance of local moments in metals are well reflected in the magnetic behaviour of Ce intermetallic compounds. This work describes experiments on two Ce compounds which are typical examples of unstable moment systems. The first of these is CeAl2 which at low temperatures, shows coexistence of antiferromagnetic order and the Kondo effect. Measurements are presented of the magnetization and the susceptibility in different magnetic field and temperature regions. An analysis of these measurements, using a model for the crystal field effects, shows the agreement between the measurements and the calculations to be reasonably good for CeAl2, but this agreement becomes worse upon decreasing Ce concentration. A phenomenological description of the observations is given. The second compound reported on is CeCu2Si2, the first 'heavy-fermion' superconductor to be investigated. The superconducting state is possibly formed by the quasi-particles of a non-magnetic many body singlet state, and not simply by the (sd) conduction electrons. This being a novel phenomenon, a number of experiments were performed to test this picture and to obtain a detailed description of the behaviour of CeCu2Si2. Measurements of the Meissner volume, confirmed the superconductivity to be intrinsic. (Auth.)

  20. Chemiluminescent Diagnostics of Free-Radical Processes in an Abiotic System and in Liver Cells in the Presence of Nanoparticles Based on Rare-Earth Elements nReVO4:Eu3+ (Re = Gd, Y, La) and CeO2

    Science.gov (United States)

    Averchenko, E. A.; Kavok, N. S.; Klochkov, V. K.; Malyukin, Yu. V.

    2014-11-01

    We have used luminol-dependent chemiluminescence with Fenton's reagent to study the effect of nanoparticles based on rare-earth elements of different sizes and shapes on free-radical processes in abiotic and biotic cell-free systems, and also in isolated cells in vitro. We have estimated the effects of rare-earth orthovanadate nanoparticles of spherical (GdYVO4:Eu3+, 1-2 nm), spindle-shaped (GdVO4:Eu3+, 25 ×8 nm), and rod-shaped (LaVO4:Eu3+, 57 × (6-8) nm) nanoparticles and spherical CeO2 nanoparticles (sizes 1-2 nm and 8-10 nm). We have shown that in contrast to the abiotic system, in which all types of nanoparticles exhibit antiradical activity, in the presence of biological material, extra-small spherical (1-2 nm) nanoparticles of both types exhibit pro-oxidant activity, and also enhance pro-oxidant induced oxidative stress (for the pro-oxidants hydrogen peroxide and tert-butyl hydroperoxide). The effect of rare-earth orthovanadate spindle and rod shaped nanoparticles in this system was neutral; a moderate antioxidant effect was exhibited by 8-10 nm CeO2 nanoparticles.

  1. Synthesis and characterization of mixed conductor CeNbO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guoguang, E-mail: zhanggg0306@126.com [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Wan, Weibin; Long, Peiqing; Li, Qin; Deng, Cuizhen [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Yi, Zhiguo [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Chinese Academy of Sciences, Fujian 350002 (China)

    2014-12-15

    Highlights: • XPS results indicated the existence of both Ce{sup 3+} and Ce{sup 4+} cations in the quenched CeNbO{sub 4} sample. • An internal friction peak was observed and attributed to the short-distance jump of interstitial oxygens. • The ionic transfer number was about 0.4. - Abstract: CeNbO{sub 4} samples were synthesized via solid state reactions and characterized by XRD, XPS, internal friction and impedance measurements. The XRD pattern showed that the sample quenched from 1173 K to room temperature was mainly composed of monoclinic CeNbO{sub 4} phase. XPS analysis showed that the oxygen lattice can be present in form of Ce–O and Nb–O while niobium exists in Nb{sup 5+} state and cerium exists in both Ce{sup 3+} and Ce{sup 4+} states. One relaxation process was observed by the internal friction (IF) measurement, which was attributed to the short distance migration of interstitial oxygens. The activation energy of the IF peak is deduced to be 0.34 eV. In the impedance measurement, the ionic transfer number estimated by impedance calculation was about 0.4. The activation energies for ionic conductivity (E{sub ion}), electronic conductivity (E{sub hole}) and total conductivity (E{sub t}) were calculated to be 0.34, 0.29, and 0.64 eV, respectively.

  2. 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

  3. Hydrogenation of the intermediate valence ternary stannides CeRhSn and CeIrSn

    OpenAIRE

    Chevalier, Bernard; Sebastian, C. P.; Pöttgen, Rainer

    2006-01-01

    CeRhSn and CeIrSn were synthesized from the elements via arc-melting. A single crystal from the CeIrSn sample was investigated on the basis of X-ray diffractometer data: ZrNiAl type, P2m, a=743.8(2), c=407.58(7) pm, wR2=0.0308, 352 F2 values and 14 variable parameters. An important structural feature of CeIrSn are relatively short Cesingle bondIr distances (4×303 and 1×308 pm). Hydrogenation of these ternary stannides leads to the formation of the new hydrides CeRhSnH0.8 and CeIrSnH0.7 which ...

  4. 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

  5. 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.

  6. Radiation streaming with SAM-CE

    International Nuclear Information System (INIS)

    The SAM-CE Monte Carlo code has been employed to calculate doses, due to neutron streaming, on the operating floor and other locations of the Millstone Unit II Nuclear Power Facility. Calculated results were compared against measured doses

  7. CuO/CeO2 catalysts prepared with different cerium supports for CO oxidation at low temperature

    International Nuclear Information System (INIS)

    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 CeO2 supports such as commercial CeO2 and self-prepared CeO2 for the preparation of copper catalysts. The CuO/CeO2 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/CeO2 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/CeO2 catalysts with commercial CeO2, those with CeO2 that was self-prepared by pyrolysis had a large pore volume and good crystal structure of CeO2 and showed good performance. The catalytic activity for CO removal was in the following order: CuO/CeO2-P (pyrolysis) > CuO/CeO2-C (commercial) > CuO/CeO2-D (deposition precipitation). CuO/CeO2-P catalysts showed good activity even at low temperature. The CuO/CeO2-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−1, SV was 3.7 × 104 h−1, and reaction temperature was 150 °C. - Highlights: • CuO/CeO2 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. • Catalytic activity of CuO/CeO2 catalysts were evaluated by the removal of CO

  8. 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.

  9. 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.

  10. Magnetic and transport properties of CePdAs and CePdSb

    International Nuclear Information System (INIS)

    The results of measurements of electrical resistivity ρ, magnetic susceptibility χ, magnetization M and specific heat C are reported on single-crystalline samples of CePdAs and CePdSb. As for CePdAs, ρ(T) perpendicular to the c-axis behaves like a metal and a sharp drop appears around 4 K corresponding to the magnetic transition. But ρ(T) parallel to the c-axis shows a maximum at about 10 K and semiconducting behavior at high temperature. ρ(T) perpendicular to the c-axis on CePdSb shows the same metallic behavior as in the case of CePdAs. The strong aniosotropy in ρ(T) suggests that CePdAs and CePdSb are better characterized as quasi-two-dimensional electrical conductors. This anisotropy is also manifested in χ and M. χ(T) and M(H) along the c-axis of CePdAs and CePdSb exhibits antiferromagnetic ordering at 4 and 17 K, respectively. But χ(T) along the a-axis increases, with decreasing temperature following Curie-Weiss-like behavior of a ferromagnet. (orig.)

  11. 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.

  12. Structural study of (N2H5,H)2.9U1.1Ce0.9(C2O4)5·10H2O from a conventional X-ray diffraction diagram obtained on a powder synthesized by a fast vortex process

    International Nuclear Information System (INIS)

    In the context of research on U/minor actinides for nuclear fuel reprocessing in the transmutation process, developments are first studied with surrogates containing uranium and lanthanides to facilitate testing. The tests consist of precipitating and calcining a hydrazinium uranium/cerium oxalate. The structure of this oxalate had not been previously determined, but was necessary to validate the physicochemical mechanisms involved. The present study, firstly demonstrates the structural similarity of the U/Ce oxalate phase (N2H5,H)2.9U1.1Ce0.9(C2O4)5·10H2O, synthesized using a vortex precipitator for continuous synthesis of actinide oxalates, with previously known oxalates, crystallizing in P63/mmc symmetry, obtained by more classical methods. This fast precipitation process induces massive nucleation of fine powders. Their structural and microstructural determination confirms that the raw and dried phases belong to the same structural family as (NH4)2U2(C2O4)5·0.7H2O whose structure was described by Chapelet-Arab in P63/mmc symmetry, using single crystal data. However, they present an extended disorder inside the tunnels of the structure, even after drying at 100 °C, between water and hydrazinium ions. This disorder is directly related to the fast vortex method. This structure determination can be used as a basis for further semi-quantitative analysis on the U/minor actinides products formed under various experimental conditions. - Highlights: • Uranium cerium oxalate precipitate characterization by X-ray powder diffraction. • Morphology characterization by SEM analysis. • Structure determination by unit cell Rietveld refinement

  13. Different synthesis protocols for Co3O4 -CeO2 catalysts--part 1: influence on the morphology on the nanoscale.

    Science.gov (United States)

    Yang, Jingxia; Lukashuk, Liliana; Akbarzadeh, Johanna; Stöger-Pollach, Michael; Peterlik, Herwig; Föttinger, Karin; Rupprechter, Günther; Schubert, Ulrich

    2015-01-01

    Co3 O4 -modified CeO2 (Co/Ce 1:4) was prepared by a combination of sol-gel processing and solvothermal treatment. The distribution of Co was controlled by means of the synthesis protocol to yield three different morphologies, namely, Co3 O4 nanoparticles located on the surface of CeO2 particles, coexistent Co3 O4 and CeO2 nanoparticles, or Co oxide structures homogeneously distributed within CeO2 . The effect of the different morphologies on the properties of Co3 O4 -CeO2 was investigated with regard to the crystallite phase(s), particle size, surface area, and catalytic activity for CO oxidation. The material with Co3 O4 nanoparticles finely dispersed on the surface of CeO2 particles had the highest catalytic activity. PMID:25384333

  14. Spectral hole burning in the 4f-5d transition of Ce3+ in LuPO4 and YPO4

    International Nuclear Information System (INIS)

    Persistent spectral holes in the inhomogeneously broadened 4f1-4f05d1 zero-phonon transitions in LuPO4:Ce3+ and YPO4:Ce3+ crystals were burned at T=2 K. The holes observed in absorption were deep (up to 50%) and could be observed at least minutes after they were burned. The burning process was very efficient and is due to a single photon process. The observed spectral holes are burned in a photochemical process of photoionization of Ce3+ ions involving electron tunneling from Ce3+ centers to traps

  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. Optical properties and radiation response of Ce3+-doped GdScO3 crystals

    International Nuclear Information System (INIS)

    10%-Ce doped GdScO3 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:GdScO3 crystal showed photo- and radio-luminescence peaks due to Ce3+ 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.)

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

    International Nuclear Information System (INIS)

    We report a high-energy magnetic-Compton-scattering study performed on the ferromagnet CeRh3B2. This technique solely measures the electron spin magnetic moments. In contrast to a number of Ce intermetallics with nonmagnetic elements, the Ce 5d spin moment is found to be large and parallel to the Ce 4f spin moment. Therefore the Kondo effect does not play a key role for CeRh3B2. The inferred large Ce 5d orbital magnetic moment is a signature of the strong spin-orbit interaction for the Ce 5d band. copyright 1998 The American Physical Society

  18. Different magnetic behaviour of the Kondo compounds Al3Ce and Al11Ce3

    International Nuclear Information System (INIS)

    Neutron diffraction experiments on the Al3Ce and Al11Ce3 compounds have been performed on the multidetector of the I.L.L. high flux reactor. No magnetic structure has been detected on the Al3Ce compound down to 20 mK. This confirms the non magnetic ground state of Al3Ce. For Al11Ce3, two magnetic structures have been observed: a ferromagnetic one at 4.2 K and an antiferromagnetic one at 2 K. The antiferromagnetic structure, which corresponds to a propagation vector (0,0,1/3), implies a strong reduction of the magnetic moment of determined sites; this reflects the Kondo character of the compounds

  19. 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

  20. Effect of Ce Doping on RGO-TiO2 Nanocomposite for High Photoelectrocatalytic Behavior

    Directory of Open Access Journals (Sweden)

    Md. Rakibul Hasan

    2014-01-01

    Full Text Available Ce doped RGO-TiO2 composite films on ITO substrates were prepared by sol-gel process using tetrabutyl titanate and reduced graphene oxide (RGO as the starting materials. The sample was designed for the photoelectrocatalytic applications. The obtained samples were characterized by X-ray diffraction, UV-vis absorption spectroscopy, scanning electron microscopy, and Fourier transformed infrared spectroscopy. The results showed that doping of Ce on RGO-TiO2 composite film inhibited the TiO2 anatase-rutile phase transformation. In this case, Ce atoms could serve as dispersion oxide and suppress the recombination of photoinduced electron-hole pairs. Besides, the change in absorbance from UV to visible region was observed in Ce doped RGO-TiO2 nanocomposite films. The Ce doped RGO-TiO2 composite film showed higher photoelectrochemical performance than that of RGO-TiO2 composite and pure TiO2 under solar simulator irradiation. The main reason might be attributed to the optimum content of Ce that could act as electrons acceptor to hinder the recombination loss and facilitate the better transportation for photoinduced charge carriers.

  1. 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.

  2. 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

  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. 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

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. 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.

  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. CeO2-stabilized tetragonal ZrO2 polycrystals (Ce-TZP ceramics)

    International Nuclear Information System (INIS)

    This work presents the development and the characterization of CeO2-stabilized tetragonal ZrO2 polycrystals (Ce-TZP ceramics), since it is considered candidate material for applications as structural high performance ceramics. Sintered ceramics were fabricated from mixtures of powders containing different CeO2 content prepared by conventional and nonconventional techniques. These powders and their resultant sintered ceramics were specified by chemical and physical characterization, compactation state and mechanical properties. The chemical characteristics were determined by chemical analysis and the physical characteristics were evaluated by phase content, particle and agglomerate size and aspect, and powder porosity. (author)

  15. 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...

  16. Seebeck coefficient of CePd3

    International Nuclear Information System (INIS)

    Rare earth compounds have potential applications in thermoelectric devices due to their large value conductivity and Seebeck coefficient. CePd3 has the highest reported Seebeck coefficient (S ∼ 125 μV/K), when doped appropriately, among all rare-earth compounds. This high value is explained as a result of the placement of the cerium f1 level. (author)

  17. Simplifying instrumentation for CE-MS analysis

    Czech Academy of Sciences Publication Activity Database

    Týčová, Anna; Foret, František

    Vienna, 2015. s. 37-37. [MassSpec-Forum-Vienna-2015. 17.02.2015-18.02.2015, Vienna] R&D Projects: GA ČR(CZ) GBP206/12/G014; GA ČR(CZ) GA15-15479S Institutional support: RVO:68081715 Keywords : interface * CE-MS * sheathless Subject RIV: CB - Analytical Chemistry, Separation

  18. Some regularities of Ce(3) and Ce(4) stabilization in their compounds with β-diketones

    International Nuclear Information System (INIS)

    Adduct formation of cerium (3) and cerium (4) β-diketonates (acetylacetonate, benzoylacetonate, dibenzoylmethanate and thenoyltrifluoroacetonate) with oxygen- and nitrogen-donor ligands (Q-α, α'-dipyridyl, o-phenanthroline, trioctylphosphine oxide and triphenylphosphine oxide) is studied. The compounds obtained as a results of the reactions are studied by means of IR-spectroscopic, derivatographic and X-ray phase methods. It is concluded that composition and thermodynamic stability of adducts of Ce(3) tris-β-diketonates are determined by correlation of donor properties of the basis and additional ligand and stability of adducts to oxidation - as well as by their solubility. Introduction of the additional ligand to the system Ce(4)-β-diketones even in the presence of air oxygen stabilizes Ce(3) and destabilizes Ce(4)

  19. 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

  20. 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

  1. 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

  2. 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.

  3. 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

  4. 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] ...

  5. 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.

  6. INCA-CE project: status and results

    Science.gov (United States)

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

    2013-04-01

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

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. The cerium ground state in the intermetallic compounds Al2Ce, Al3Ce at very low temperature

    International Nuclear Information System (INIS)

    Nuclear orientation experiments show the different behaviour between the Al2Ce and Al3Ce compounds. Despite the occurrence of a Kondo coupling, the first compound is well ordered down to 5 mK. No long range ordering seems to exist in Al3Ce but crystal field effects can partly mask the ordering. (author)

  12. Cerium intermetallics CeTX. Review III

    International Nuclear Information System (INIS)

    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 119Sn 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].

  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. Low flow electrospray interfacing CE/MS

    Czech Academy of Sciences Publication Activity Database

    Foret, František; Týčová, Anna; Křenková, Jana; Klepárník, Karel

    2015. L-10. ISBN N. [International Symposium on Electro- and Liquid Phase-Separation Techniques (ITP2015) /22./ and the Nordic Separation Science (NoSSS) symposium /8./. 30.08.2015-03.09.2015, Helsinki] R&D Projects: GA ČR(CZ) GBP206/12/G014 Institutional support: RVO:68081715 Keywords : electrospray * CE/MS * GAP20612G014 Subject RIV: CB - Analytical Chemistry, Separation

  16. Thermoemission of Ce+ ions and its fluctuations

    Science.gov (United States)

    Gladyszewski, Longin

    1994-12-01

    The surface ionization of cerium on tungsten and its fluctuatins (noises) have been studied using a single filament ion source in a 90° magnetic mass spectrometer. The statistical behaviour of the spectral density and autocorrelation functions for Ce+ ion thermoemission noise were investigated by means of a special stochastic analyser. These noises are generated as a result of adsorbate density fluctuations. The method used made it possible to determine the atom desorption and migration energy for cerium from tungsten.

  17. 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.

  18. 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

  19. Ce3+Pr3+:LiY0.3Lu0.7F4 Mixed Crystal as a Perspective Upconversionally Pumped UV Active Medium

    International Nuclear Information System (INIS)

    The key parameters of processes provided up-conversion pumping of 5d-states of Ce3+ ions in Ce3+, Pr3+:LiY0.3Lu0.7F4 mixed crystals were estimated for the first time. The prospects of this material as the first up-convertionally pumped UV active media were demonstrated

  20. 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

  1. YAP (Ce) as focal plane detectors

    International Nuclear Information System (INIS)

    YAP (Ce) has been known to be one of the commercially available new scintillators that can be used for several applications. It has a good timing response and a very high value for the radiation hardness, compared to other known inorganic scintillators. Several studies have been reported on the properties of the scintillator, viz., light yield, decay time constant, gamma and charged particle response, pulse shape discrimination and timing characteristics. The YAP(Ce) crystals has a very good response to the energetic heavy ions and attempts have been made to employ it as a viable alternative to the Si detectors for the detection of heavy ions. As a part of the experimental facilities, being developed for the upcoming Superconducting cyclotron at VECC, the possibility is being explored for using the YAP(Ce) as an E detector, preceded by a position sensitive MWPCs as αE counterpart, at the focal plane of the proposed superconducting solenoid spectrometer. The selection of Photo Multiplier Tubes (PMT) has been very crucial in such cases in order to have good timing response and energy resolution for energetic heavy ions. The responses have been tested for different bias voltages of the tube and the best values have been reported here

  2. Mass spectrometric studies on Ce-Cd system

    International Nuclear Information System (INIS)

    Molten salt electrorefining process, which is a pyrochemical reprocessing method, is ideally suited for reprocessing of metallic fuels. Separation of fuel material and fission products is carried out by electrorefining of spent fuel by using solid mandrel and liquid cadmium as cathodes for the electrodeposition of uranium and transuranium elements, respectively. Due to the standard electrode potentials of rare earths being close to that of transuranium elements, some amount of rare-earths are accompanied during the electrodeposition of Pu and minor actinides at liquid cadmium cathode. Therefore the investigation of thermodynamic properties of rare earth-cadmium system is essential. As part of this, vaporization studies on Ce-Cd system with the initial composition of 63.3 at % Cd (corresponding to Cd2Ce+CdCe phase region) has been investigated by Knudsen effusion mass spectrometry. This paper reports the preliminary studies carried out on this system. High purity cadmium (99.99%, M/s. Johnson Matthey Chemical Ltd, England) and cerium (99.8%, M/s. Alfa Aesar) were used for the preparation. The sample was prepared by isopiestic method by equilibrating Cd vapours over the Ce samples in a vacuum sealed quartz set up kept in a gradient furnace. The quartz set up was subsequently quenched and opened inside an argon atmosphere glove box to retrieve the sample. The phase characterization was carried out by XRD. A VG Micromass 30 BK mass spectrometer was employed for the vaporisation studies. The sample was taken in an alumina Knudsen cell (Sample loading carried out inside an argon atmosphere glovebox) and this was placed inside a molybdenum outer cup and a tungsten lid. The cell was heated by electron bombardment and the vapour effusing from Knudsen cell was ionized by electron impact, the ions produced were mass analysed by a 90° sector magnetic analyser and detected by a secondary electron multiplier. Cd+ was the ion detected in the mass spectra of the equilibrium

  3. 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

  4. Synthesis and electrochemical properties of CeO2 nanoparticle modified TiO2 nanotube arrays

    International Nuclear Information System (INIS)

    In this paper, a cerium dioxide (CeO2) modified titanium dioxide (TiO2) nanotube array film was fabricated by electrodeposition of CeO2 nanoparticles onto an anodized TiO2 nanotube array. The structural investigation by X-ray diffraction, scanning electron microscopy and transmission electron microscopy indicated that the CeO2 nanoparticles grew uniformly on the walls of the TiO2 nanotubes. The composite was composed of cubic-phase CeO2 crystallites and anatase-phase TiO2 after annealing at 450 oC. The cyclic voltammetry and chronoamperometric charge/discharge measurement results indicated that the CeO2 modification obviously increased the charge storage capacity of the TiO2 nanotubes. The charge transfer process at the surface, that is, the pseudocapacitance, was the dominate mechanism of the charge storage in CeO2-modified TiO2 nanotubes. The greater number of surface active sites resulting from uniform application of the CeO2 nanoparticles to the well-aligned TiO2 nanotubes contributed to the enhancement of the charge storage density.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-02-28

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

  6. 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.

  7. Determination of thermo-physical properties of (Th,Ce)O2 MOX using classical molecular dynamics simulations

    International Nuclear Information System (INIS)

    This paper calculates lattice thermal expansion (LTE) and thermal conductivity (TC) of Th1-xCexO2 (x=0.0, 0.0625 and 0.125) MOX using classical molecular dynamic simulations. The potential parameters of Coulomb-Buckingham function for Th-O, Ce-O and O-O were determined by fitting experimentally available LTE data for pure ThO2 and CeO2. The calculated linear thermal expansion coefficients in the temperature range 300-1500K for ThO2, CeO2, Th93.75Ce6.25O2 and Th87.5Ce12.5O2 are 10.61, 13.08, 10.78 and 10.93x10-6 K-1, respectively. The MD calculated LTE values of ThO2 and (Th,Ce)O2 MOX are slightly higher than the experimentally determined values. The MD calculated TC values of ThO2 and (Th,Ce)O2 MOX in the high temperature range (600 to 1200 K) our results accords very well with the experimental measurements and at the low temperature range (300-500 K) our results are slightly different from some experimental results as the difference comes from our presumption that the dominant mechanism for phonon scattering is the Umklapp process. (author)

  8. 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.

  9. Fabrication and luminescence of BiPO4:Tb3+/Ce3+ nanofibers by electrospinning

    Science.gov (United States)

    Yang, Yuguo; Liu, Bing; Zhang, Yuanyuan; Lv, Xianshun; Wei, Lei; Wang, Xuping

    2016-02-01

    BiPO4:Tb3+/Ce3+ nanofibers are synthesized by a simple electrospinning process and followed by a calcination treatment. The nanofibers are characterized by TG-DSC, XRD, FT-IR, SEM, TEM, and spectrophotometer. The calcined BiPO4:Tb3+/Ce3+ nanofibers have a monoclinic phase and the diameters are in the range of 80-200 nm. The SEM and TEM images show that the nanofibers are mesoporous and composed of lots of linked nanoparticles. Under an excitation at 369 nm, BiPO4:Tb3+ and BiPO4:Tb3+/Ce3+ nanofibers show characteristic emission bands originating from the 5D4 → 7Fj (j = 6, 5, 4, and 3) transitions of Tb3+ ions. The luminescent properties of BiPO4:Tb3+ indicate that the quenching concentration for Tb3+ ions in BiPO4 host is about 15 mol%. The co-doped Ce3+ ions can improve the emission intensity through the energy transfer from Ce3+ to Tb3+ ions.

  10. 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

  11. 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.

  12. 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.

  13. 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...

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

    Science.gov (United States)

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

    2016-05-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-02-15

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

  16. 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...

  17. 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.

  18. 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.)

  19. 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.

  20. Global distribution analysis of potassium on lunar surface using CE1-GRS data

    International Nuclear Information System (INIS)

    In order to acquire the global distribution of potassium (K) on the lunar surface, the methods and data processing procedure of the Chang'E-1 (CE1) gamma-ray spectrometer (GRS) were studied using the level 2C spectra data measured by the CE1- GRS, and the preliminary global count map of K was derived. K is primarily concentrated within and around the western-most maria on the near side and a secondary abundance concentration is located in the South Pole-Aitken basin. On the far side, K generally shows the feature of low abundance. Compared with the global map of K measured by the Lunar Prospector (LP) GRS, the result shows that major features of the global K distribution appeared in CE1-GRS map are consistent with that from LP-GRS. (authors)

  1. 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

  2. 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.

  3. The ABB-CE system 80 standard plant design

    International Nuclear Information System (INIS)

    Design standardization of nuclear power plants provides more cost certainty and safer, more reliable plant performance to electric utilities. The U.S. nuclear market recognized these benefits of standardization in the mid-1970's and embarked on a program of licensing standard plant designs. ABB Combustion Engineering Nuclear Power (ABB-CE) had long before realized the many benefits of standardization and established a design approach that maximized these benefits. Standardization, however, does not mean stagnation. The System 80 design is a modern, proven pressurized water reactor (PWR) that has evolved through a process of continuous improvement. It has been in operation at the three unit station at Palo Verde in the U.S. since 1986. Subsequent System 80 plants (eight units) are either in operation, conducting initial start-up, or are under construction in the Republic of Korea. This design offers a high degree of safety as exhibited by the low core damage frequency (CDF) and many years of safe operation. As a group, the System 80 plants have maintained a high plant availability, with an average value exceeding 80 percent since 1991. Over the last three years, the System 80 plants have an average availability exceeding the EPRI ALWR Utility Requirements Document goal of 87%. The purpose of this paper is to provide descriptions and information regarding ABB-CE's System 80 Standard Plant, which is currently implemented in South Korea, and is ideally suited and being proposed for future deployment in Asia

  4. Mechanism of (NH4)S2O8 to enhance the anti-corrosion performance of Mo-Ce inhibitor on X80 steel in acid solution

    International Nuclear Information System (INIS)

    Highlights: • The 1000 mg/L Na2MoO4 and 500 mg/L Ce(NO3)3 has best synergistic effect. • The (NH4)2S2O8 made the valence transformation of cerium (Ce3+ → Ce4+) come true. • The anti-corrosion performance of Mo-Ce inhibitor was improved by (NH4)2S2O8. • The coordination ability of inhibitor complexes was improved by (NH4)2S2O8. • The bonding force and adsorption between inhibitor and steel surface was enhanced. - Abstract: Ce(NO3)3 and Na2MoO4 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 (NH4)2S2O8. The reason of enhancement is the increase of coordination bonds amount between Ce4+ and MoO42−, the augment of combining sites of interface between anti-corrosion film and steel, and the reinforce of adsorption caused by the transformation of Ce3+ to Ce4+ by oxidants. The process and conditions for transformation of Ce3+ to Ce4+ and formation of complexes are discussed. The related thermodynamic and kinetic parameters are calculated and the possibility for (NH4)2S2O8 to improve the performance of Mo-Ce corrosion inhibitor is proved

  5. 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.

  6. 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.

  7. Reconstructing the landing trajectory of the CE-3 lunar probe by using images from the landing camera

    International Nuclear Information System (INIS)

    An accurate determination of the landing trajectory of Chang'e-3 (CE-3) is significant for verifying orbital control strategy, optimizing orbital planning, accurately determining the landing site of CE-3 and analyzing the geological background of the landing site. Due to complexities involved in the landing process, there are some differences between the planned trajectory and the actual trajectory of CE-3. The landing camera on CE-3 recorded a sequence of the landing process with a frequency of 10 frames per second. These images recorded by the landing camera and high-resolution images of the lunar surface are utilized to calculate the position of the probe, so as to reconstruct its precise trajectory. This paper proposes using the method of trajectory reconstruction by Single Image Space Resection to make a detailed study of the hovering stage at a height of 100 m above the lunar surface. Analysis of the data shows that the closer CE-3 came to the lunar surface, the higher the spatial resolution of images that were acquired became, and the more accurately the horizontal and vertical position of CE-3 could be determined. The horizontal and vertical accuracies were 7.09 m and 4.27 m respectively during the hovering stage at a height of 100.02 m. The reconstructed trajectory can reflect the change in CE-3's position during the powered descent process. A slight movement in CE-3 during the hovering stage is also clearly demonstrated. These results will provide a basis for analysis of orbit control strategy, and it will be conducive to adjustment and optimization of orbit control strategy in follow-up missions

  8. Grèce antique et Grèce moderne

    OpenAIRE

    Baud-Bovy, Samuel

    2015-01-01

    Alors que les savants grecs du siècle dernier, que ce soit pour faire plaisir aux philhellènes ou pour combattre la théorie de Fallermayer sur la slavisation de la Grèce au Moyen Age, mettaient tout en œuvre pour prouver que les Grecs modernes étaient les descendants directs des Grecs anciens, les générations suivantes se lassèrent de ce culte exclusif voué aux ancêtres. Il arrivait même à Palamas, le poète national du XXe siècle naissant, de s’insurger contre cette mentalité : Les tombes, mê...

  9. A study of the Ce3+/Ce4+ redox couple in sulfamic acid for redox battery application

    International Nuclear Information System (INIS)

    Highlights: ► SA served as media electrolyte for Ce3+/Ce4+ was reported. ► A Zn–Ce redox battery was assembled and it showed impressive charge–discharge performance. ► The performance of Zn–Ce battery was improved by adding carbonate such as NH4HCO3. Its energy efficiency reached up to 53%. -- Abstract: The present paper reports a cerium sulfamate electrolyte for use in redox battery. The electrochemical behavior of Ce3+/Ce4+ in sulfamic acid (SA) media has been investigated using linear-sweep voltammetry and cyclic voltammetry. The formal potential of the Ce3+/Ce4+ redox couple in SA is approximately 1.52 V vs. NHE. The exchange current density and standard rate constant of the Ce3+/Ce4+ redox reaction on platinum electrode in SA are determined as 5.95 × 10−4 A cm−2 and 4.95 × 10−5 cm s−1 respectively. The diffusion coefficient of Ce3+ in SA is 5.93 × 10−6 cm2 s−1. The conductivity of cerium(III) sulfamate solution is improved significantly by adding NH4+. A zinc–cerium test cell with Ce3+/Ce4+ sulfamate solution as the positive electrolyte is constructed and the charge-discharge performance is evaluated. The coulombic efficiency of the Zn–Ce cell is calculated to be 90%. The preliminary exploration shows that the cerium sulfamate electrolyte is promising for redox battery application and is worthy of further study.

  10. 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.)

  11. 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...

  12. Low temperature magnetic behavior of Ce7Ni3

    International Nuclear Information System (INIS)

    Low-temperature specific heat (CP) (70 mK7Ni3 (under applied magnetic fields up to B=6 T) are presented. The maxima in CP (at 1.55 K) and in χ (at 1.85 K) are related to an antiferromagnetic (AF) type transition. The experimental results are interpreted in terms of three Ce sublattices (1CeI, 3CeII and 3CeIII atoms per formula unit) of the Th7Ni3-type structure. These sublattices correspond to the three different Ce local environments. According to the entropy gain the AF order is related to the CeI sublattice and the CeII atoms behave as heavy fermions, with γLT∼2.7 J/CeII-at.K2 and a characteristic temperature of TK∼4 K. The CeIII atoms are responsible for an intermediate valence behavior with γHT∼0.3 J/CeIII-at.K2 and a characteristic temperature of T0∼70 K, which is confirmed by the ln T dependence of the electrical resistivity. ((orig.))

  13. CuO-CeO2 binary oxide nanoplates: Synthesis, characterization, and catalytic performance for benzene oxidation

    International Nuclear Information System (INIS)

    This work reports the first synthesis of CuO-CeO2 binary oxides with a plate-like morphology by a solvothermal method. The as-prepared CuO-CeO2 nanoplates calcined at 400 oC were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectrum, and tested for catalytic oxidation of dilute benzene in air. Various structural characterizations showed that large amounts of copper species were exposed on the CuO-CeO2 nanoplate surface. The effect of the synthesis conditions on the structure of the product, as well as the growth process of the nanoplates, has been studied and discussed. The CuO-CeO2 nanoplates exhibited an excellent catalytic activity for benzene oxidation despite its relatively low surface area and could catalyze the complete oxidation of benzene at a temperature as low as 240 oC.

  14. 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.

  15. 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.)

  16. 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.

  17. 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

  18. 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)

  19. 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

  20. 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.

  1. 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

  2. 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

  3. 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

  4. Bismuth flux growth of CeRh6Ge4 and CeRh2Ge2 single crystals

    International Nuclear Information System (INIS)

    Single crystals of the germanides CeRh6Ge4 and CeRh2Ge2 were synthesized from the elements in bismuth fluxes. Polycrystalline samples are available by arc-melting. The structures were refined on the basis of single-crystal X-ray diffractometer data. CeRh6Ge4: LiCo6P4 type, P anti 6m2, a = 715.4(2), c = 385.5(1) pm, wR2 = 0.0554, 273 F2 values, 19 variables; CeRh2Ge2: ThCr2Si2 type, I4/mmm, a = 415.69(6), c = 1048.5(2) pm, wR2 = 0.0391, 131 F2 values, 9 variables. The rhodium and germanium atoms build three-dimensional, covalently bonded [Rh6Ge4] and [Rh2Ge2] networks with Rh-Ge distances ranging from 246 to 255 pm. The cerium atoms are located in larger cavities within these networks: Ce rate at Ge6Rh12 in CeRh6Ge4 and Ce rate at Ge8Rh8 in CeRh2Ge2. Temperature-dependent magnetic susceptibility data of CeRh6Ge4 show Curie-Weiss behavior above 70 K with an experimental magnetic moment of 2.35(1) μB per Ce atom. Low-field measurements are indicative of magnetic ordering below 2.5 K. (orig.)

  5. 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.

  6. A pressure study of CePt{sub 3}B

    Energy Technology Data Exchange (ETDEWEB)

    Rauch, Daniela; Suellow, Stefan [Institute of Condensed Matter Physics, University of Technology Braunschweig, Braunschweig (Germany); Hartwig, Steffen [Institute of Condensed Matter Physics, University of Technology Braunschweig, Braunschweig (Germany); BENSC, Helmholtz Zentrum Berlin, Berlin (Germany); Hidaka, Hiroyuki; Yamazaki, Seigo; Amitsuka, Hiroshi [Department of Physics, Hokkaido University, Sapporo (Japan); Bauer, Ernst [Institute of Solid State Physics, Vienna University of Technology, Vienna (Austria)

    2013-07-01

    CePt{sub 3}B is isostructural to the non-centro symmetric heavy-fermion superconductor CePt{sub 3}Si. In contrast to the latter system, CePt{sub 3}B exhibits a complex magnetically ordered state at low temperatures, with an antiferromagnetic phase below T{sub N}=7.8 K and a weakly ferromagnetic transition below T{sub C}∼5 K. CePt{sub 3}B can be understand as a low pressure variant of CePt{sub 3}Si. Here we report a study of CePt{sub 3}B by means of high pressure magnetization measurements, this way in particular accessing the pressure evolution of the ferromagnetic transition temperature T{sub C}. From our investigation up to about 40 kbar we observe an almost constant transition temperature T{sub C} with pressure. This behavior we discuss in the context of alloying studies on this material.

  7. 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.

  8. Valence state of Ce and the magnetism in CeRh3B2

    International Nuclear Information System (INIS)

    The compound CeRh3B2 orders magnetically with a high Curie temperature (T/sub C/) of 115 K but with a low moment of only 0.4 μ/sub B/. L/sub III/ absorption-edge measurements show a dominant absorption peak at the energy corresponding to trivalent cerium. Magnetic studies on the compounds Ce(Rh/sub 1-x/T/sub x/)3B2 with T = Ru and Os reveal that the magnetic state is very rapidly broken up with the replacement of Rh by Ru and Os. These results, along with the observation of a high T/sub C/ in CeRh3B2, suggest that magnetism in this compound arises from a strong hybridization of nearly localized or slightly delocalized Ce 4f electrons with conduction electrons. The small moment may be due to a Kondo-type interaction coupled with crystal-field effects. 14 references, 4 figures

  9. Thermodynamic assessment of Al-Ce-Cu system

    International Nuclear Information System (INIS)

    The Ce-Cu binary system has been thermodynamically reassessed by CALPHAD approach based on experimental data and thermodynamic properties of phase diagram. Incorporating the thermodynamic evaluations of Al-Ce and Al-Cu systems from literature, the Al-Ce-Cu ternary system has been assessed using CALPHAD approach. The solution phases including liquid, Fcc and Bcc were treated as substitutional solution phases and the Redlich-Kister polynomial was used to describe their excess Gibbs energies. All binary and ternary intermetallic compounds were treated as stoichiometric phases and their Gibbs energies of formation were optimized. The calculated Al-Ce-Cu phase diagram agreed well with available experimental data.

  10. Complex charge ordering in CeRuSn

    Energy Technology Data Exchange (ETDEWEB)

    Feyerherm, Ralf; Dudzik, Esther; Valencia, Sergio [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, 12489 Berlin (Germany); Mydosh, John A. [MPI-CPFS, 01187 Dresden (Germany); Kamerlingh Onnes Laboratory, Leiden University, 2300RA Leiden (Netherlands); Hermes, Wilfried; Poettgen, Rainer [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, 48149 Muenster (Germany)

    2012-07-01

    At room temperature (RT), CeRuSn exhibits coexistence of trivalent Ce{sup 3+} and intermediate valent Ce{sup (4-{delta})+} in a metallic environment. Charge ordering produces a doubling of the unit cell along the c-axis with respect to the basic CeCoAl type structure. Below RT, a phase transition with broad hysteresis has been observed in various bulk properties. The present X-ray diffraction results show that at low temperatures the doubling of the CeCoAl type structure is replaced by an ill-defined modulated ground state in which at least three modulation periods compete. The dominant mode is close to a tripling of the basic cell. XANES data suggest that the average Ce valence remains constant. We propose a qualitative structure model with modified stacking sequences of Ce{sup 3+} and Ce{sup (4-{delta})+} layers in the various modulated phases. Surprisingly, far below 100 K the modulated state is sensitive to synchrotron X-ray irradiation. With a photon flux {approx} 10{sup 12} s{sup -1}, the modulated ground state is destroyed on a timescale of minutes and the doubling of the CeCoAl cell observed at room temperature is recovered. The final state is metastable at 10 K. Heating the sample above 60 K again leads to a recovery of the modulated state.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.)

  19. Thermodynamic stabilities of SrCeO3 and Sr2CeO4 using the fluoride EMF technique

    International Nuclear Information System (INIS)

    The standard Gibbs energies of formation of SrCeO3 and Sr2CeO4 were measured by the EMF method using CaF2 as a solid electrolyte. Three fluoride galvanic cells (I-III) were constructed in order to determine ΔfG deg. of SrCeO3. The ΔfG deg. of Sr2CeO4 was determined using galvanic cell (IV). The cells used were Pt,O2(g)(1bar),SrO(s),SrF2(s) vertical bar CaF2 vertical bar SrF2(s),CeO2(s),SrCeO3(s),O2(g) (1bar) (I); Pt,O2(g)(1bar),SrO(s),SrF2(s) vertical bar SrF2 vertical bar SrF2(s),CeO2(s),SrCeO3(s), O2(g)(1bar) (II); Pt,O2(g)(1bar),SrF2(s),CeO2(s),SrCeO3(s) vertical bar CaF2 vertical bar CaF2(s), CaO(s),O2(1bar) (III); Pt,O2(g)(1bar),SrO(s),SrF2(s) vertical bar CaF2 vertical bar SrF2(s),SrCeO3(s),Sr2CeO4(s),O2(1bar),Pt (IV). The standard Gibbs energy of formation of SrCeO3, derived from the mean of the EMFs of the above galvanic cells (I to III), is given by the following expression:ΔfG deg. (SrCeO3)+/-17(kJmol-1)=-1703+0.327T(K)(788-1142K) By combining this expression with the EMF measured using Cell IV, the following expression was obtained for the temperature dependence of the standard Gibbs energy of formation of Sr2CeO4ΔfG deg. (Sr2CeO4)+/-21(kJmol-1)=-2307+0.4400T(K)(805-1066K)

  20. Ce and T magnetism in CeTPO compounds (T = Os, Ru, Fe, Co) - large variety of ground states

    International Nuclear Information System (INIS)

    In the last years we have started a detailed investigation of the CeTPO compounds (T = Os, Ru, Fe, Co). These materials correspond to the family of LnTPnO systems, crystallizing in the tetragonal ZrCuSiAs structure-type, which attracts a lot of attention due the observation of high temperature superconductivity (SC) in the doped LnFeAsO compounds. Whereas the 3d-magnetism of the Fe is essentially for the occurrence of SC in LnFeAsO, the magnetism in CeTPO is dominated by the 4f-electrons of Ce3+. In this contribution, we summarize our results on the single crystal growth of the CeTPO materials together with a thorough physical characterization, including magnetization, susceptibility, resistivity, specific heat, and thermopower. These measurements reveal four different magnetic ground states: (1) CeRuPO is a rare example of a ferromagnetically ordered Kondo-lattice system with TC=15 K and a Kondo scale of TK∝10 K; (2) CeOsPO orders antiferromagnetically at TN=4.5 K; (3) CeFePO is a heavy-fermion system on the non-magnetic side of a ferromagnetic instability; (4) CeCoPO present ferromagnetic order of the Co-ions at TC=75 K and Ce-moments close to magnetism. Therefore, these new materials present a nice playground to study in detail the phenomena of strongly correlated electron systems.

  1. 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.

  2. 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.

  3. Measurement of the CE-phase of 5 fs pulses and its application

    International Nuclear Information System (INIS)

    Full text: Since many strong-field processes depend on the electric field the carrier envelope (CE) phase is therefore a critical parameter in many few-cycle lightmatter interactions. The purpose of this experiment is to investigate the effect of the CE-phase on the yields of ionized atoms using ultrashort pulses for a non phase stable laser. In the experiment the single and double ionization of Xenon is studied. In particular in the case of the double ionization of Xenon the regime of nonsequential double ionization (NSDI) is focused upon. Using f - 2f interferometry while simultaneously measuring the photoelectron or photoion signal, it is possible to investigate the effect of the CE-phase for each laser shot. Using this method previously an asymmetry of approximately 10 % in the photoelectron signal was observed. In this experiment two different pulse durations are used in order to compare the photoelectron and photoion yields in both cases. Phase effects in the ion momenta have already been measured using comparable pulse durations, however, the total yield appears to be insensitive to the CE-phase. A scheme to influence NSDI by controlling the trajectory of the returning electron is discussed, which represents control of the electron on an attosecond timescale. Using a Cold Target Recoil Ion Momentum Spectrometer (COLTRIMS) it is possible to measure the momenta of particles after ionization. Plans for such an experiment are presented. Refs. 3 (author)

  4. 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.

  5. 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.

  6. 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.

  7. Synthesis and structural characterization of Ce-doped bismuth titanate

    International Nuclear Information System (INIS)

    Ce-modified bismuth titanate nanopowders Bi4-xCexTi3O12 (x ≤ 1) have been synthesized using a coprecipitation method. DTA/TG, FTIR, XRD, SEM/EDS and BET methods were used in order to investigate the effect of Ce-substitution on the structure, morphology and sinterability of the obtained powders. The phase structure investigation revealed that after calcinations at 600 deg. C powder without Ce addition exhibited pure bismuth titanate phase; however, powders with Ce (x = 0.25, 0.5 and 0.75) had bismuth titanate pyrochlore phase as the second phase. The strongest effect of Ce addition on the structure was noted for the powder with the highest amount of Ce (x = 1) having a cubic pyrochlore structure. The presence of pure pyrochlore phase was explained by its stabilization due to the incorporation of cerium ions in titanate structure. Ce-modified bismuth titanate ceramic had a density over 95% of theoretical density and the fracture in transgranular manner most probably due to preferable distribution of Ce in boundary region

  8. Investigation of thermal neutron capture in 23Na, 138Ba, 140Ce and 142Ce

    International Nuclear Information System (INIS)

    A measurement of the angular correlation of γ-rays emitted in the capture of thermal neutrons in 23Na has been used to determine the multipole mixing ratio delta for seventeen transitions in 24Na, of which seven are primary transitions. For these primary transitions also the capture state spin admixture α has been derived. The neutron capture reaction proceeds predominantly through the Jsup(π)=1+ channel, as expected from previous cross-section measurements. A measurement of the circular polarization of γ-rays resulting from the capture of polarized thermal neutrons in 138Ba, 140Ce and 142Ce has yielded spin assignments for p-states in the final nuclei. Excitation energies and reaction Q-values have been obtained from the analysis of singles spectra taken with unpolarized neutrons. (Auth.)

  9. Collective excitations in {sup 132}Ce; Excitations collectives de {sup 132}Ce

    Energy Technology Data Exchange (ETDEWEB)

    Paul, E.S.; Boston, A.J.; Zoss, D.T.; Nolan, P.J.; Sampson, J.A.; Semple, A.T. [Oliver Lodge Laboratory, University of Livepool, Liverpool (United Kingdom); Farget, F.; Gizon, A.; Gizon, J.; Santos, D. [Inst. des Sciences Nucleaires, Grenoble-1 Univ., 38 (France); Nyako, B.M. [Institute of Nuclear Research, Debrecen (Hungary); O`Brien, N.J.; Parry, C.M.; Wadsworth, W. [Department of Physics, University of York, Helsington, York (United Kingdom)

    1997-12-31

    The structure of normally deformed states ({beta}{sub 2}{approx}0.2) in {sup 132}Ce has been investigated using EUROGAM2. Eight {Delta}I=2 bands and three {Delta}I=1 bands have been identified up to spin 40. The results are interpreted with the aid of Woods-Saxon cranking calculations which suggest a variety of triaxial shapes stabilized by specific active quasiparticle orbitals. (authors)

  10. Valence fluctuation in CeMo2Si2C

    International Nuclear Information System (INIS)

    Highlights: •Evidence for valence fluctuation of Ce ions. •XAS provides average formal LIII valence of Ce. •Kadowaki Woods ratio and Sommerfeld Wilson ratio indicate Fermi-liquid behavior. •DFT calculations reveal strong hybridization between Ce 4f and Mo 4d states. -- Abstract: We report on the valence fluctuation of Ce in CeMo2Si2C as studied by means of magnetic susceptibility χ(T), specific heat C(T), electrical resistivity ρ(T) and X-ray absorption spectroscopy. Powder X-ray diffraction revealed that CeMo2Si2C crystallizes in CeCr2Si2C-type layered tetragonal crystal structure (space group P4/mmm). The unit cell volume of CeMo2Si2C deviates from the expected lanthanide contraction, indicating non-trivalent state of Ce ions in this compound. The observed weak temperature dependence of the magnetic susceptibility and its low value indicate that Ce ions are in valence fluctuating state. The formal LIII Ce valence in CeMo2Si2C〈ν∼〉=3.14 as determined from X-ray absorption spectroscopy measurement is well below the value 〈ν∼〉≃3.4 in tetravalent Ce compound CeO2. The temperature dependence of specific heat does not show any anomaly down to 1.8 K which rules out any magnetic ordering in the system. The Sommerfeld coefficient obtained from the specific heat data is γ = 23.4 mJ/mol K2. The electrical resistivity follows the T2 behavior in the low temperature range below 35 K confirming a Fermi liquid behavior. Accordingly both the Kadowaki Woods ratio A/γ2 and the Sommerfeld Wilson ratio χ(0)/γ are in the range expected for Fermi-liquid systems. In order to get some information on the electronic states, we calculated the band structure within the density functional theory, eventhough this approach is not able to treat 4f electrons accurately. The non-f electron states crossing the Fermi level have mostly Mo 4d character. They provide the states with which the 4f sates are strongly hybridized, leading to the intermediate valent state

  11. 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.

  12. Moment dilution in the heavy fermion compound Ce2Bi

    International Nuclear Information System (INIS)

    The heavy fermion compound Ce2Bi has two inequivalent Ce-sites. La was doped on these sites to study the influence of the antiferromagnetic order on the high electronic contribution of the specific heat (γHT(T>TN)∼340mJ/Ce-molK2). The slightly larger La atom replaces the Ce2 site first and then subsequently the Ce1 site in the La2Sb structure. Lattice parameters, magnetic susceptibility and specific heat are used to elucidate the magnetic nature of the two different cerium sites. We find a somewhat enhanced γHT, a decrease in TN and furthermore a metamagnetic transition at 2.2T (2K), which is closely related to the long-range antiferromagnetic order. ((orig.))

  13. Ordering of CeIII/CeIV and interstitial oxygens in CeTaO4+x (x ∼ 0.17) superstructure

    International Nuclear Information System (INIS)

    A structural model for CeTaO4+x (x ∼ 0.17) or alternately Ce4IIICe2IVTa6O25 (monoclinic, P21, a = 7.616(2), b = 16.459(5), c = 7.704(2) angstrom, β = 102.48(2)degree, Z = 2) is derived from X-ray powder diffraction data. The starting model was a 3 x b superstructure of CeTaO4+x (x = 0.0) with excess oxygen atoms occupying interstices between the Ce atom layers consistent with the electron diffraction determined space group symmetry P21. Unexpectedly, the four Ce atoms surrounding the interstitial oxygen are not oxidized. During the refinement the model was forced to be chemically plausible by restraining bond valence sums, bond lengths, and O-O distances. This was necessary due to the very weak scattering contribution to the XRD profile by oxygen atoms. The mechanism for oxidation of the subject phase from CeTaO4+x (x = 0.0) is discussed and a reason for the limiting composition for this phase is proposed

  14. 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.

  15. Structural and electronic properties of Ce overlayers and low-dimensional Pt-Ce alloys on Pt{111}

    International Nuclear Information System (INIS)

    The structural, thermal, chemisorptive, and electronic properties of Ce on Pt{111} are studied by photoemission, Auger spectroscopy, scanning tunnel microscope (STM), and low-energy electron diffraction (LEED). Stranski-Krastanov-like growth of low-density Ce layers is accompanied by substantial valence charge transfer from Ce to Pt: in line with this, the measured dipole moment and polarizability of adsorbed Ce at low coverages are 7.2x10-30Cm and ∼1.3x10-29m3, respectively. Pt-Ce intermixing commences at ∼400K and with increasing temperature a sequence of five different ordered surface alloys evolves. The symmetry, periodicities, and rotational epitaxy observed by LEED are in good accord with the STM data which reveal the true complexity of the system. The various bimetallic surface phases are based on growth of crystalline Pt5Ce, a hexagonal layer structure consisting of alternating layers of Pt2Ce and Kagomacute e nets of Pt atoms. This characteristic ABAB layered arrangement of the surface alloys is clearly imaged, and chemisorption data permit a distinction to be made between the more reactive Pt2Ce layer and the less reactive Pt Kagomacute e net. Either type of layer can appear at the surface as the terminating structure, thicker films exhibiting unit mesh parameters characteristic of the bulk alloy. copyright 1997 The American Physical Society

  16. 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.

  17. 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

  18. Preparation and luminescence properties of Ce3+ and/or Tb3+ doped LaPO4 nanofibers and microbelts by electrospinning

    International Nuclear Information System (INIS)

    Ce3+ and/or Tb3+ doped LaPO4 nanofibers and microbelts have been prepared by a combination method of sol-gel process and electrospinning. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), low voltage cathodoluminescence (CL) and time-resolved emission spectra as well as kinetic decays were used to characterize the resulting samples. SEM and TEM results indicate the as-formed precursor fibers and belts are smooth, and the as-prepared nanofibers and microbelts consist of nanoparticles. The doped rare-earth ions show their characteristic emission under ultraviolet excitation, i.e. Ce3+ 5d-4f and Tb3+5D4-7FJ (J=6-3) transitions, respectively. The energy transfer process from Ce3+ to Tb3+ in LaPO4:Ce3+, Tb3+ nanofibers was further studied by the time-resolved emission spectra. Under low-voltage electron beam excitation, LaPO4:Ce3+, Tb3+ microbelt phosphors have a higher intensity than that of nanofiber phosphors. - Graphical Abstract: Ce3+ and/or Tb3+ LaPO4 nanofibers and microbelts have been prepared by electrospinning. A systematic study on the optical properties of LaPO4:Ce3+, Tb3+ samples has shown that they are good green-emitting phosphors in fluorescent lamps and field emission displays. The energy transfer process from Ce3+ to Tb3+ in LaPO4:Ce3+, Tb3+ nanofibers is further studied by the time-resolved emission spectra.

  19. 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...

  20. 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

  1. Catalytic soot oxidation over Ce- and Cu-doped hydrotalcites-derived mesoporous mixed oxides.

    Science.gov (United States)

    Wang, Zhongpeng; Wang, Liguo; He, Fang; Jiang, Zheng; Xiao, Tiancun; Zhang, Zhaoliang

    2014-09-01

    Ce- and Cu-doped hydrotalcites derived mixed oxides were prepared through co-precipitation and calcination method, and their catalytic activities for soot oxidation with O2 and O2/NO were investigated. The solids were characterized by XRD, TG-DTG, BET, H2-TPR, in situ FTIR and TPO techniques. All the catalysts precursors showed the typical diffraction patterns of hydrotalcite-like materials having layered structure. The derived mixed oxides exhibited mesoporous properties with specific surface area of 45-160 m2/g. After both Ce and Cu incorporated, mixed crystalline phases of CuO (tenorite), CeO2 (fluorite) and MgAl2O4 (spinel) were formed. As a result, the NO(x) adsorption capacity of this catalyst was largely increased to 201 μmol/g, meanwhile, it was also the most effective to convert NO into NO2 in the sorption process due to the enhanced reducibility. The in situ FTIR spectra revealed that NO(x) were stored mainly as chelating bidentate and monodentate nitrate. The interaction effect between Cu and Ce in the mixed oxide resulted in different NO(x) adsorption behavior. Compared with the non-catalyzed soot oxidation, soot conversion curves over the mixed oxides catalysts shift to low temperature in O2. The presence of NO in the gas phase significantly enhanced the soot oxidation activity with ignition temperature decreased to about 320 degrees C, which is due to NO conversion to NO2 over the catalyst followed by the reaction of NO2 with soot. This explains the cooperative effect of Ce and Cu in the mixed oxide on soot oxidation with high activity and 100% selectivity to CO2 formation. PMID:25924375

  2. Thermal properties of some cerium compounds, particularly CeB6

    International Nuclear Information System (INIS)

    Using measurements of specific heat between 0.3 to 250K in the absence of a magnetic field, and from 2 to 250K for magnetic fields between 0 and 8T, it is shown that the γ 8 quadruplet is the fundamental level of the Ce3+ ion, the γ 8-7 separation energy being of the order of 500K. Detailed analysis suggests a lifting of degeneracy of the multiplet γ 8 in the paramagnetic phase, according to usual processes. Specific heat results obtained at very low temperatures reveal the importance of a significant gap in the spin wave energy spectra. Measurements under a strong magnetic field, around the two magnetic phase transitions of CeB6 show a spectacular reinforcement of the specific heat anomaly at a temperature of the order of TQ. Thermal conductivity of CEB6 is also studied in relation to the possible existence of a Jahn-Teller effect, likely to affect heat transfer by phonons. The problem of the different components of thermal transport prompts the analysis of the Weidemann-Franz law in the Kondo net, and also the study of the thermal conductivity of the compounds CeCu6, CeA12, the alloys Ce0.75La0.25B6, CexLa1-xCu6, and the fluctuating valence system SmB6. In all these bodies, an important contribution of phonons to electron transfer is shown. In the dense incoherent Kondo phase, it is not possible to envisage differences from the Weidemann-Franz law greater than those observed for highly diluted Kondo alloys

  3. 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

  4. Applicability of CeO2 as a surrogate for PuO2 in a MOX fuel development

    International Nuclear Information System (INIS)

    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 CO2 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

  5. 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.

  6. Comparative Study on Redox Properties of Nanosized CeO2 and CuO/Ce2 Under CO/O2

    International Nuclear Information System (INIS)

    Nanosized CeO2 and CuO/CeO2 samples, active for CO-PROX or related processes were comparatively examined by O2 probe electron paramagnetic resonance and in situ Raman and X-ray diffraction techniques. Their behavior toward CO reduction, as well as the oxygen-handling properties of the CO-reduced samples, was explored. An appreciable reduction of the ceria bulk was detected on treatment under CO at 473 K. On the basis of the analysis of the evolution of different oxygen-derived species (superoxide, peroxide, O-) on low-temperature (77-300 K) oxygen chemisorption on the CO-reduced samples, a general picture of the redox properties of the samples is presented. Results demonstrate that the presence of copper promotes completion of the redox cycle under CO/O2 by favoring both ceria reduction and oxidation. This can be relevant to explaining the remarkable oxidation activity and synergetic effects observed for catalysts combining CuO and CeO2

  7. 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.

  8. Microwave sintering of ZrO2-12 mol% CeO2

    International Nuclear Information System (INIS)

    Sintering of ZrO2-12 mol% CeO2 was accelerated by microwave processing at 2.45 GHz as compared with conventional firing. However, the size of the ''microwave effect'' was significantly smaller than that which was previously observed for microwave sintering of ZrO2-8 mol% Y2O3. The difference in the effect that the microwave field had on the two zirconia systems is interpreted in terms of their ionic conductivities

  9. Passivity of OC404 steel modified electrochemically with CeO2-Ce2O3 layers in sulfuric acid media

    International Nuclear Information System (INIS)

    The effect of cerium oxides film, formed electrochemically on OC404 stainless steel (SS), upon the corrosion behavior of steel in 0.1N H2SO4 was investigated. The modification of the steel surface by deposition of cerium oxides films was found to improve the steel corrosion resistance. A linear dependence between the stationary corrosion potential of the cerium oxides/SS system and the cerium concentration in the oxide film was established. The shift of the corrosion potential in the positive direction was found to depend on the proceeding of a depolarizing cathode reaction of CeO2 reduction (instead of the hydrogen depolarizing reaction) occurring on the cathodic zones, formed by this oxide. On the basis of XPS analyses of the samples, subjected to real corrosion under the conditions of self-dissolution, a pronounced drop of the surface concentration of CeO2 was established. This is a proof of the occurrence of an effective cathode process of CeO2 reduction to Ce2O3, which was then dissolved in H2SO4. Data were obtained (XPS) on the composition and structure of the surface film (SEM) after electrodeposition of cerium oxides and after corrosion in the sulfuric acid medium under consideration for time intervals ranging from 50 up to 1000 h. The ICP-AES studies acquired data on the quantity of dissolved elements, forming the passive layer. After exposure to the corrosive medium, the deposited layer showed enrichment in oxides of chromium and aluminium. The passive film on stainless steel, modified in this way, proved to be more stable to the effect of aggressive sulfuric acid medium, compared to the case of natural passive film.

  10. Passivity of OC404 steel modified electrochemically with CeO{sub 2}-Ce{sub 2}O{sub 3} layers in sulfuric acid media

    Energy Technology Data Exchange (ETDEWEB)

    Stoyanova, E.; Guergova, D. [Institute of Physical Chemistry, Bulgarian Academy of Sciences, ' Acad. G. Bonchev' Str., Block 11, Sofia 1113 (Bulgaria); Stoychev, D., E-mail: stoychev@ipchp.ipc.bas.b [Institute of Physical Chemistry, Bulgarian Academy of Sciences, ' Acad. G. Bonchev' Str., Block 11, Sofia 1113 (Bulgaria); Avramova, I.; Stefanov, P. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, ' Acad. G. Bonchev' Str., Block 11, Sofia 1113 (Bulgaria)

    2010-02-01

    The effect of cerium oxides film, formed electrochemically on OC404 stainless steel (SS), upon the corrosion behavior of steel in 0.1N H{sub 2}SO{sub 4} was investigated. The modification of the steel surface by deposition of cerium oxides films was found to improve the steel corrosion resistance. A linear dependence between the stationary corrosion potential of the cerium oxides/SS system and the cerium concentration in the oxide film was established. The shift of the corrosion potential in the positive direction was found to depend on the proceeding of a depolarizing cathode reaction of CeO{sub 2} reduction (instead of the hydrogen depolarizing reaction) occurring on the cathodic zones, formed by this oxide. On the basis of XPS analyses of the samples, subjected to real corrosion under the conditions of self-dissolution, a pronounced drop of the surface concentration of CeO{sub 2} was established. This is a proof of the occurrence of an effective cathode process of CeO{sub 2} reduction to Ce{sub 2}O{sub 3}, which was then dissolved in H{sub 2}SO{sub 4}. Data were obtained (XPS) on the composition and structure of the surface film (SEM) after electrodeposition of cerium oxides and after corrosion in the sulfuric acid medium under consideration for time intervals ranging from 50 up to 1000 h. The ICP-AES studies acquired data on the quantity of dissolved elements, forming the passive layer. After exposure to the corrosive medium, the deposited layer showed enrichment in oxides of chromium and aluminium. The passive film on stainless steel, modified in this way, proved to be more stable to the effect of aggressive sulfuric acid medium, compared to the case of natural passive film.

  11. Luminescence properties of Ce3+ co-activated LaPO4:Dy3+ nanorods prepared in different solvents and tunable blue to white light emission from Eu3+ co-activated LaPO4:Dy3+, Ce3+

    International Nuclear Information System (INIS)

    The nanorods of Ce3+ sensitized LaPO4:Dy3+ with and without co-activation of Eu3+ have been synthesized by simple chemical route at relatively low temperature (150 °C). Effect of solvents on photoluminescence properties of Ce3+ sensitized LaPO4:Dy3+ is studied by taking different solvents such as water, ethylene glycol (EG), dimethyl sulfoxide (DMSO) and their mixture. The samples prepared in EG and DMSO show monoclinic phase, whereas the samples prepared in water and mixed solvents show hexagonal phase. This hexagonal phase is transformed to monoclinic phase when the sample is heated at or above 600 °C and exhibits less luminescence intensity than that in monoclinic phase. The luminescence intensity of Dy3+ is enhanced when co-doped with Ce3+ because of energy transfer process. The luminescence color can be tuned from blue to white when Eu3+ is co-doped into LaPO4:Dy3+, Ce3+. The prepared nanoparticles are dispersible and their polymer films are prepared after incorporation in to the polymer matrix. - Graphical Abstract: White emission production from Ce3+ sensitized LaPO4:Dy3+, Eu3+ nanorods. Highlights: ► Synthesis of Ce3+ sensitized LaPO4:Dy3+ nanorods. ► Photoluminescence properties of samples prepared in different solvents. ► Tuning of color from blue to white on co-doping of Eu3+ in LaPO4:Dy3+, Ce3+. ► Dispersion of particles in polar medium. ► Polymer based film formation.

  12. Microstructure and texture evolution of CeO{sub 2} buffer layers prepared via dip-coating sol-gel method on IBAD-YSZ/Hastelloy substrates

    Energy Technology Data Exchange (ETDEWEB)

    Du, P. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China)], E-mail: honey00@mails.tsinghua.edu.cn; Wang, S.S.; Chen, H.; Wang, Z.; Sun, J.C.; Han, Z. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China); Schmidt, W.; Neumuller, H.W. [Siemens AG, CT PS 3, Erlangen 91052 (Germany)

    2007-10-01

    We have fabricated CeO{sub 2} buffer layers on IBAD-YSZ/Hastelloy substrates via dip-coating sol-gel method using inorganic salts as starting materials. X-ray diffraction (XRD), scanning electron microscopy (SEM) and scanning probe microscope (SPM) were applied to investigate the influential factors in film formation and texture evolution. Flat, crack-free CeO{sub 2} films with sharp (0 0 2) c-axis orientation and good texture were obtained by carefully controlling the precursor solution quality, dip-coating and heating process. Compared with IBAD-YSZ/Hastelloy substrates, textures of CeO{sub 2} films were effectively improved.

  13. Influence of the Incorporation of CeO2 Nanoparticles on the Ion Exchange Behavior of Dodecylsulfate Doped Polypyrrole Films: Ac-Electrogravimetry Investigations

    OpenAIRE

    Benmouhoub, Chabba; Agrisuelas, Jeronimo; Benbrahim, N.; Pillier, Francoise; Gabrielli, Claude; Kadri, A.; Pailleret, Alain; Perrot, Hubert; Sel, Ozlëm

    2014-01-01

    Cerium oxide (CeO2) nanoparticles (NPs) possessing defined size and crystallinity have been synthe-sised by a co-precipitation method. The effect of several parameters, such as the nature of the solventand the calcination process, on the crystallite size was studied by XRD, TEM and BET methods. TheseCeO2nanoparticles were then incorporated in dodecylsulfate (DS) doped PPy films during their elec-trodeposition in potentiodynamic conditions in order to produce PPy-DS/CeO2NPs nanocomposite thinf...

  14. 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)

  15. Exotic clustering in Ce and Nd isotopes

    CERN Document Server

    Buck, B; Pérez, S M

    1999-01-01

    We propose exotic binary cluster models for the intermediate mass nuclei sup 1 sup 4 sup 6 sup , sup 1 sup 4 sup 8 sup , sup 1 sup 5 sup 0 Ce and sup 1 sup 4 sup 8 sup , sup 1 sup 5 sup 0 sup , sup 1 sup 5 sup 2 sup , sup 1 sup 5 sup 4 Nd. The optimum choice of cluster and core is determined by joint consideration of the penetrability for exotic cluster emission, the deviations of cluster and core binding energies from underlying liquid drop values and the Q-values for breakup. It is noticeable that the core neutron number selected in this way is at or near the N = 82 shell closure. We use a standard form of the cluster-core potential to calculate the energies and wave functions of states in the ground 0 sup + , 2 sup + , 4 sup + , ... and lowest lying negative parity 1 sup - , 3 sup - , 5 sup - , ... bands. The theoretical spectra and electromagnetic properties are compared with measurements, and their general trends are reproduced satisfactorily.

  16. 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 ...

  17. Template electrosynthesis of CeO2 nanotubes

    International Nuclear Information System (INIS)

    Nanotube arrays of CeO2 were produced in a single step by potentiostatic electrochemical deposition from a non-aqueous electrolyte, using anodic alumina membrane templates. The CeO2 nanotubes showed a polycrystalline structure, and they were assembled in the membrane nanochannels. The nanotubes had somewhat uniform diameters, with an average external value of about 210 nm, and a maximum length of about 60 μm; the latter parameter was controlled by the electrodeposition time. Each single nanotube was found to consist of crystalline grains having a size of about 3 nm. Raman analysis shows that these CeO2 nanotubes are suitable for catalytic applications

  18. 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)

  19. Growth of LGSO: Ce crystals by the Czochralski method

    International Nuclear Information System (INIS)

    Single crystals of Lu2xGd2-2xSiO5: Ce (0 1/c to C2/c in the course of substitution of lutetium for gadolinium occurs at the ratio Lu/(Lu + Gd) = 0.1. The lattice thus formed with symmetry C2/c in the structure of Lu2xGd2-2xSiO5: Ce crystals favors the maximum possible incorporation of Ce3+ ions into the sevenfold-coordinated position with respect to oxygen. This explains the substantial improvement of the scintillation characteristics of the grown crystals.

  20. 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

  1. 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

  2. A unique CE16 acetyl esterase from Podospora anserina active on polymeric xylan.

    Science.gov (United States)

    Puchart, Vladimír; Berrin, Jean-Guy; Haon, Mireille; Biely, Peter

    2015-12-01

    The genome of the coprophilous fungus Podospora anserina displays an impressive array of genes encoding hemicellulolytic enzymes. In this study, we focused on a putative carbohydrate esterase (CE) from family 16 (CE16) that bears a carbohydrate-binding module from family CBM1. The protein was heterologously expressed in Pichia pastoris and purified to electrophoretic homogeneity. The P. anserina CE16 enzyme (PaCE16A) exhibited different catalytic properties than so far known CE16 esterases represented by the Trichoderma reesei CE16 acetyl esterase (TrCE16). A common property of both CE16 esterases is their exodeacetylase activity, i.e., deesterification at positions 3 and 4 of monomeric xylosides and the nonreducing end xylopyranosyl (Xylp) residue of oligomeric homologues. However, the PaCE16A showed lower positional specificity than TrCE16 and efficiently deacetylated also position 2. The major difference observed between PaCE16A and TrCE16 was found on polymeric substrate, acetylglucuronoxylan. While TrCE16 does not attack internal acetyl groups, PaCE16A deacetylated singly and doubly acetylated Xylp residues in the polymer to such an extent that it resulted in the polymer precipitation. Similarly as typical acetylxylan esterases belonging to CE1, CE4, CE5, and CE6 families, PaCE16A did not attack 3-O-acetyl group of xylopyranosyl residues carrying 4-O-methyl-D-glucuronic acid at position 2. PaCE16A thus represents a CE16 member displaying unique catalytic properties, which are intermediate between the TrCE16 exodeacetylase and acetylxylan esterases designed to deacetylate polymeric substrate. The catalytic versatility of PaCE16A makes the enzyme an important candidate for biotechnological applications. PMID:26329850

  3. 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.

  4. Enhanced Activity of CuCeO Catalysts for CO Oxidation: Influence of Cu2O and the Dispersion of Cu2O, CuO, and CeO2.

    Science.gov (United States)

    Wang, Zhenhua; Li, Ren; Chen, Qianwang

    2015-08-01

    CuCeO catalysts prepared by a hydrothermal method with subsequent calcination are tested for the catalytic oxidation of CO. This synthesis method leads to a homogeneous dispersion of Cu2 O, CuO, and CeO2 in the catalysts. The composition of the catalysts is determined by the molar ratio of the metals, the hydrothermal process, and calcination temperature and influences the catalytic performance. The catalyst containing Cu2 O exhibits high catalytic activity with almost 100 % CO conversion at 105 °C and shows excellent stability with the conversion ratio not decreasing after four months of storage. PMID:26017784

  5. 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.

  6. 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

  7. Preparation of Na4UO2(CO3)3 in presence of Ce-141. I, Influence of the post-reaction time in the concentration of anion species of Ce-141

    International Nuclear Information System (INIS)

    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)

  8. 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

  9. Decontamination of 60Co and 144Ce. low-activity liquid wastes with the Fe3+ /OH- /Ca2+ /PO-4-3- system

    International Nuclear Information System (INIS)

    The influence of reaction time, concentrations of Fe3+ and PO-4-3+, temperature and agitation velocity in the efficiency of decontamination of 60Co and 144Ce low-activity liquid wastes using the Fe3+ /OH-/Ca2+ /PO-4-3+ precipitator system was stud ied in this paper. The mathematical models of this process were obtained for 60Co and 144Ce. The best conditions for the decontamination we re calculated using the optimization program

  10. 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.

  11. 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.

  12. 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...

  13. Crystallization and fluorescence properties of Ce:YAG glass-ceramics with low SiO2 content

    International Nuclear Information System (INIS)

    Ce3+ doped YAG (Ce:YAG) glass-ceramics with 20 mol% SiO2 were fabricated by the method of amorphous sintering followed by controlled crystallization (ASCC). An investigation on the crystallization process of as-sintered glasses revealed that surface crystallization occurred first and YAlO3 (YAP) was precipitated as the main crystalline phase; then bulk crystallization continued inside these glasses and YAP phase transited to YAG. The phase transition from YAP to YAG could be promoted by an inert atmosphere instead of reductive one and by the increase of the crystallization temperature and holding time. By combining the Ce:YAG glass-ceramics with a blue-emitting InGaN chip, white LEDs with a relatively high color rendering index of 80.3 and low color temperature of 5098 K were produced. Their luminous efficacy decreased with the increasing annealing temperatures, which was probably caused by the degradation of transparency. -- Highlights: ► Translucent SiO2-low Ce:YAG glass-ceramics were successfully obtained. ► A white LED (CIR, 80.3 and CT, 5098 K) was equipped with the obtained glass-ceramic. ► Controlled surface and bulk crystallizations of the glass were observed. ► Three Ce3+ emission centers were possibly involved during the luminescence decay. ► Luminous efficacy decreased with elevated annealing temperatures

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

    International Nuclear Information System (INIS)

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

  15. 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...

  16. Performance evaluation of LaBr3: Ce scintillator

    International Nuclear Information System (INIS)

    The cerium doped lanthanum bromide crystal (LaBr3: Ce) is a new kind of scintillator with many advantages such as good energy resolution, high light output, short decay time, good proportionality response. These properties make the LaBr3: Ce attractive substantial interest to use in the radiation detection. The energy resolution were investigated with Φ25 × 25 mm LaBr3: Ce coupled to a Hamamatsu R8900 photomultiplier tube. Energy resolution of 3.6% (FWHM) have been achieved for 511 keV photons (18F source) at room temperature. Decay time constant of 20 ns have been acquired with a Hamamatsu fast-time-response R9800 photomultiplier tube. The results approve the excellent characterizations of LaBr3: Ce and imply its enormous potentiality in the radiation detectors of gamma-ray spectroscopy and PET. (authors)

  17. Nuclear structure of 130-136Ce in IBM-1

    International Nuclear Information System (INIS)

    The level structure of Ce isotopes with N < 82 has been studied in recent experiments, yielding increasing information on the non yrast bands. The Interacting Boson Model (IBM-1) offers a useful tool for such phenomenological study

  18. 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.

  19. Combustion synthesis of nanocrystalline ceria (CeO2) powders by a dry route

    International Nuclear Information System (INIS)

    In this study, ceria (CeO2) powders were synthesized with 50 g per batch via a combustion technique using two kinds of starting materials-urea [(NH2)2CO] (as a fuel) and ceric ammonium nitrate [Ce(NH4)2(NO3)6] (acting as both the source of cerium ion and an oxidizer). The starting materials were mixed thoroughly without adding water, and then ignited in the air at room temperature. It underwent a self-combustion process with a large amount of smoke, a voluminous loose product. The as-synthesized powders were characterized by X-ray diffraction (XRD) analysis, transmission electron microscope (TEM), scanning electron microscope (SEM), CHN elemental analyzer, surface area measurements, and sinterability. Experimental results revealed that the nanocrystalline CeO2 powders with low impurity content (2/g and ∼25 nm, respectively, through the stoichiometric fuel/oxidizer ratio reaction. The powder, when cold pressed and sintered in the air at 1250 deg. C for 1 h, was measured to attain the sintered density ∼92% of theoretical density having submicron grain size. In addition, the thermal decomposition and combustion process of the reactant mixture were investigated using thermogravimetry (TG), differential scanning calorimetry (DSC), and mass spectrometry (MS) techniques simultaneously. Based on the results of thermal analysis, a possible mechanism concerning the combustion reaction is proposed

  20. 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)

  1. 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)

  2. 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.

  3. 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.

  4. 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.

  5. 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+).

  6. 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+.

  7. 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)

  8. 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.

  9. A study on the growth kinetics of CeO{sub 2}-modified aluminide coating and its computer fitting

    Energy Technology Data Exchange (ETDEWEB)

    Wen Jiuba [School of Materials Science and Engineering Henan University of Science and Technology, Luoyang Henan 471003 (China)], E-mail: wenjiuba@mail.haust.edu.cn; Yang Liusong; Zhu Limin; Zhang Jinmin; Li QuanAn [School of Materials Science and Engineering Henan University of Science and Technology, Luoyang Henan 471003 (China)

    2009-01-15

    A CeO{sub 2}-modified aluminide coating was obtained by composite electro-deposition Ni and CeO{sub 2} particles on 20 steel with different holding time using pack cementation. The growth kinetics curve was given with computer fitting by measuring the thickness of the layer. Scanning electronic microscopy and X-ray energy dispersive spectrometry were used to analyze the microstructure and components of the layer. The results showed that the content of CeO{sub 2} was up to 5.21 wt.% in the rich area of NiAl coatings, which restrain the interdiffusion between the coating and the base during the oxidation process at high temperature. Meanwhile, the growth curve obtained could offer an important basis to forecasting and controlling the depth of the coating.

  10. A study on the growth kinetics of CeO2-modified aluminide coating and its computer fitting

    International Nuclear Information System (INIS)

    A CeO2-modified aluminide coating was obtained by composite electro-deposition Ni and CeO2 particles on 20 steel with different holding time using pack cementation. The growth kinetics curve was given with computer fitting by measuring the thickness of the layer. Scanning electronic microscopy and X-ray energy dispersive spectrometry were used to analyze the microstructure and components of the layer. The results showed that the content of CeO2 was up to 5.21 wt.% in the rich area of NiAl coatings, which restrain the interdiffusion between the coating and the base during the oxidation process at high temperature. Meanwhile, the growth curve obtained could offer an important basis to forecasting and controlling the depth of the coating

  11. 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.

  12. Analyzing input/output subsystem security in Windows CE

    OpenAIRE

    Pereira, Barbara A.

    2001-01-01

    In the past few years, mobile handheld devices have emerged as an exciting new tool for accomplishing everyday tasks. Devices with the Windows CE operating system provide flexibility for the designer in the form of customizable modules and components. With wireless capabilities and a familiar user interface, Windows CE devices are becoming popular for such tasks as inventory control and information retrieval. By enhancing the self-protection of the operating system, handheld devices could be ...

  13. 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.

  14. 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)

  15. Ultraviolet spectra of CeO2 nano-particles

    International Nuclear Information System (INIS)

    Full text: Quantum size effect is generally expected in nanometer size materials. The effect has been observed in many metal clusters and semiconducting nano-particles, but seldom in oxides, because the size control of crystalline oxides is generally difficult due to the ionic bond character. CeO2 (ceria) is one of the rare-earth oxides and the size effect is worth studying from the viewpoint of an ultraviolet (u.v.) spectroscopy and applications. This report describes the first observation of a blue shift of u.v. spectra in ceria nano-particles of 2-5 nm in diameter with its deviation within 20%. A ceria aqueous sol (pH ≅ 2.5) having particle sizes under 6 nm in diameter was produced by ultrafiltration with a polyether sulfone membrane (SIP-1013, Asahi Chemical Industry Co.) from an original ceria aqueous sol (pH ≅ 1.5) having particle sizes extending over a wide range. Obtained sol contains a high concentration of Ce3+ ions because of the high acidity. In order to separate ceria particles from Ce3+ ions and fractionate the particle size, two kinds of anion-type surfactants were used in microemulsification process with toluene and water. One is sodium dodecylbenzene sulfonate (SD-BS) which is 2 nm in length and another is sodium octyl sulfonate (SOS) which is 1.2 nm in length. U.v. spectroscopic measurements and high resolution transmission electron microscopic (HRTEM) observations were performed for (SOS)t , (SOS+SOS)t , and (SDBS+SOS+SDBS)t , where (SOS)t is a ceria suspension in toluene obtained by an emulsification with SOS surfactant, (SOS+SOS)t indicates the same product obtained by the further emulsification with SOS for an aqueous phase of the emulsion with SOS, and (SDBS+SOS+SDBS)t means that obtained by an additional emulsification with SDBS for an aqueous phase obtained by two successive emulsifications with SDBS and SOS. Optical density data for (SOS)t , (SOS+SOS)t , and (SDBS+SOS+SDBS)t show absorption edges at 4076 Angstroms, 3997 Angstroms, and

  16. 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.

  17. 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.

  18. Optical properties of LaF3:Ce and LaF3:Ce, Tb embedded polymer nanocomposites

    International Nuclear Information System (INIS)

    Colloidal solutions containing LaF3:Ce and LaF3:Ce,Tb nanoparticles were synthesized and embedded in polyacrylamide through a simple procedure. Very fine colloidal nanoparticle suspension in dm-water was synthesized by adopting co-precipitation technique in acidic environment. Nanoparticles were characterized for their crystal structure, particle size, UV-ViS absorption and photoluminescence behavior using X-ray diffraction, DLS, and photoluminescence spectroscopy techniques respectively. Size of nano-crystals was estimated using the Scherer formula. The life time measurements of the colloidal solutions were done. The transparent polymer nano composites containing LaF3:Ce and LaF3:Ce, Tb exhibited emissions at 304 and 490, 543, 585, 622 nm respectively. The colloidal route for polymer nanocomposite synthesis seems to be an easy and effective way to fabricate optically transparent photo-luminescent composite materials in variety of sizes and shapes. (author)

  19. 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)

  20. 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

  1. Electroless ternary NiCeP coatings: Preparation and characterisation

    International Nuclear Information System (INIS)

    Highlights: ► Rare earth element (Ce) has been successfully codeposited in NiP matrix. ► Surface analysis carried out by XPS showed that the Ce is present in +3 and +4 oxidation state. ► Palladium stability test indicated that the Ce salts in electroless nickel bath has reduced the stability. ► Cerium codeposition in NiP matrix has increased the microhardness both in as-plated and annealed conditions. ► 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 (Ni3P). 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 Ni3P compound formation and thus increasing the activation energy for the formation of stable phases. Surface compositional analysis using X-ray photoelectron spectroscopy (XPS) carried out on as-plated NiCeP-2 deposit showed a prominent peak of P existing in +1 oxidation

  2. 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

  3. 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.

  4. 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.

  5. 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.)

  6. Influence of secondary phases on phase and microwave dielectric properties of new Ca2Ce2Ti5O16 ceramics

    International Nuclear Information System (INIS)

    Ca2Ce2Ti5O16 ceramics processed via mix oxide route was investigated. Phase composition and microwave dielectric properties were measured using X-ray diffraction and a cavity method, respectively. CeO2 and another unidentified phase (that vanishes at ≥1400°C) existed as secondary phases along with the parent Ca2Ce2Ti5O16 phase. The amount of the parent Ca2Ce2Ti5O16 phase increased with increasing sintering temperature from 1350°C to 1450 °C accompanied by a decrease in the apparent density. The density decreased but εr and Qufo increased with sintering temperature. An εr ∼87.2, Qufo ∼5915 GHz and τf ∼219 GHz was achieved for the sample sintered at 1450°C

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

    International Nuclear Information System (INIS)

    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.

  8. 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

  9. 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.

  10. Quantitative analysis and efficiency study of PSD methods for a LaBr3:Ce detector

    Science.gov (United States)

    Zeng, Ming; Cang, Jirong; Zeng, Zhi; Yue, Xiaoguang; Cheng, Jianping; Liu, Yinong; Ma, Hao; Li, Junli

    2016-03-01

    The LaBr3:Ce scintillator has been widely studied for nuclear spectroscopy because of its optimal energy resolution (radiation background of LaBr3:Ce is a critical issue, and pulse shape discrimination (PSD) has been shown to be an efficient potential method to suppress the alpha background from the 227Ac. In this paper, the charge comparison method (CCM) for alpha and gamma discrimination in LaBr3:Ce is quantitatively analysed and compared with two other typical PSD methods using digital pulse processing. The algorithm parameters and discrimination efficiency are calculated for each method. Moreover, for the CCM, the correlation between the CCM feature value distribution and the total charge (energy) is studied, and a fitting equation for the correlation is inferred and experimentally verified. Using the equations, an energy-dependent threshold can be chosen to optimize the discrimination efficiency. Additionally, the experimental results show a potential application in low-activity high-energy γ measurement by suppressing the alpha background.

  11. 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.

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

    Science.gov (United States)

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

    2010-11-01

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

  13. Microstructure, flaw tolerance, and reliability of Ce-TZP and Y-TZP ceramics

    International Nuclear Information System (INIS)

    Ce-TZP and Y-TZP ceramics were heat-treated for various times and temperatures in order to vary the microstructure. Flaw tolerance was investigated using the indentation-strength test. Reliability was quantified using conventional two-parameter Weibull statistics. Some Ce-TZP specimens were indented at slightly elevated temperatures where no transformation was observed. Results indicated that the Ce-TZP specimens were extremely flaw tolerant, and showed a relatively high Weibull modulus that scaled with both R-curve behavior and flaw tolerance. Y-TZP, on the other hand, with very little if any R-curve behavior or flaw tolerance, had a low Weibull modulus. The results also show that flaw history, i.e., whether or not a transformation zone exists along the wake of the crack, has a significant influence on strength. Strength was much less dependent on initial crack size when the crack had an associated transformation zone, whereas strength was highly dependent on cracks typical of natural processing defects. It is argued that the improvement in reliability, flaw tolerance, and dependence on flaw history are all ramifications of pronounced R-curve behavior

  14. 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.

  15. Peculiarities of excitation of Ce-emission in core region of chlorine perovskites

    International Nuclear Information System (INIS)

    Excitation spectra of Ce-doped KCaCl3, RbCaCl3, CsSrCl3 and CsCaCl3 crystals were studied at 300 and 9 K in the 4-35 eV spectral range using synchrotron radiation. Peculiarities of the excitation spectra in the region of the uppermost core are considered from the view point of feasibility of the energy transfer from the core excitons and holes to Ce-centers. The possible channels for excitation of the activator luminescence are assumed for the CsCaCl3 and CsSrCl3 crystals exhibiting core-valence luminescence (CVL) as follows: (i) the reabsorption of the CVL by Ce-centers; (ii) the creation of the valence holes on account of radiative decay of core excitations via CVL and (iii) the migration of the core holes. All these schemes are distinctly impossible for the CVL-free KCaCl3 and RbCaCl3 crystals where core excitations decay just through the non radiative Auger-process

  16. Methanol conversion to light olefins over nanostructured CeAPSO-34 catalyst: Thermodynamic analysis of overall reactions and effect of template type on catalytic properties and performance

    International Nuclear Information System (INIS)

    Graphical abstract: In this research nanostructured CeAPSO-34 was synthesized to explore the effect of TEAOH and morpholine on its physiochemical properties and MTO performance. Prepared catalysts were characterized with XRD, FESEM, BET, FTIR and NH3-TPD techniques. The results indicated that the nature of the template determines the physiochemical properties of CeAPSO-34 due to different rate of crystal growth. The catalyst obtained by using morpholine showed longer life time as well as sustaining light olefins selectivity at higher values. Furthermore, a comprehensive thermodynamic analysis of overall reactions network was carried out to address the major channels of methanol to olefins conversion. - Highlights: • Introduction of Ce into SAPO-34 framework. • Comparison of CeAPSO-34 synthesized using morpholine and TEAOH. • The nature of the template determines the physiochemical properties of CeAPSO-34. • Morpholine enhances catalyst lifetime in MTO process. • Presenting a complete reaction network for MTO process. - Abstract: TEAOH and morpholine were employed in synthesis of nanostructured CeAPSO-34 molecular sieve and used in methanol to olefins conversion. Prepared samples were characterized by XRD, FESEM, EDX, BET, FTIR and NH3-TPD techniques. XRD patterns reflected the higher crystallinity of the catalyst synthesized with morpholine. The FESEM results indicated that the nature of the template determines the morphology of nanostructured CeAPSO-34 due to different rate of crystal growth. There was a meaningful difference in the strength of both strong and weak acid sites for CeAPSO-34 catalysts synthesized with TEAOH and morpholine templates. The catalyst synthesized with morpholine showed higher desorption temperature of both weak and strong acid sites evidenced by NH3-TPD characterization. The catalyst obtained using morpholine template had the longer lifetime and sustained desired light olefins at higher values. A comprehensive thermodynamic

  17. 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.

  18. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-02-15

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

  20. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-01-01

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

  2. 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.)

  3. 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

    2Zr2O7 buffer layer stack and the 200 nm thick YBa2Cu3O7 (YBCO) superconducting layer were sequentially deposited on textured NiW substrates using metal-organic deposition routes. The surface texture of the Gd2Zr2O7 barrier layer deteriorates when the film thickness increases to 80 nm, although the...... global texture retains a sharp biaxial orientation, as determined by conventional X-ray diffraction. We paid particular attention to improving the surface quality in terms of crystallographic orientation and local flatness after depositing a Ce0.9La0.1O2 thin film as a cap layer. From a comprehensive...

  4. Photoluminescence, and scintillation/thermoluminescence yields of several Ce3+ and Eu2+ activated borates

    International Nuclear Information System (INIS)

    Powder samples of the borates YBO3 : Ce3+, GdBO3 : Ce3+, Li6Y(BO3)3 : Ce3+, LaB3O6 : Ce3+, GdB3O6 : Ce3+, LaMgB5O10 : Ce3+, YMgB5O10 : Ce3+, CaLaB7O13 : Ce3+, CaLaB7O13 : Eu2+, Ca4YO(BO3)3 : Ce3+ and CaYOBO3 : Eu2+ were studied. The photoluminescence properties of Ce3+ in these compounds are discussed and some of them are reported for the first time. The scintillation light yield of the orthoborates YBO3 : Ce3+, GdBO3 : Ce3+, ScBO3 : Ce3+ and YAl3B4O12 : Ce3+ is of the order of 10,000 pho/MeV. The light yield due to Ce3+ in the other borates is an order of magnitude lower. In LaB3O6 : Ce3+ and LaMgB5O10 : Ce3+ a broad emission band, attributed to self-trapped exciton (STE) emission, is observed under X-ray excitation. The STE light yield of LaB3O6 : Ce3+ (0.05%) is 8000 pho/MeV and it is quenched at higher Ce concentrations. Thermoluminescence measurements show that none of these materials has a potential to be utilized as a thermal neutron storage phosphor

  5. 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...

  6. 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

  7. Crystal structure of the CeIr3 compound

    International Nuclear Information System (INIS)

    The crystal structure of the CeIr3 compound was refined for the first time from single-crystal X-ray diffraction data, down to R=0.0490, wR2=0.1052. This compound crystallizes in the PuNi3 structure type, space group R3-bar m (a=5.290(2) A, c=26.220(4) A, Z=9, V=635.44 A3, ρ=16.835 g cm-3, μ=156.36 mm-1). CeIr3 belongs to the R2m+nM4m+5n family, where m and n are the numbers of MgCu2- and CaCu5-type slabs, respectively. For CeIr3, m and n were found to be both equal to 1

  8. 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.

  9. 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..

  10. 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.

  11. 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.

  12. Surface and bulk 4f-photoemission spectra of CeIn3 and CeSn3

    International Nuclear Information System (INIS)

    Resonant photoemission spectroscopy was performed on CeIn3 and CeSn3 at the 4d-4f and 3d-4f core thresholds. Using the different surface sensitivity between the two photon energies, surface and bulk 4f-photoemission spectra were derived for both compounds. With the noncrossing approximation of the Anderson impurity model, the 4d-4f resonant spectra together with the surface and bulk spectra were self-consistently analyzed to obtain the microscopic parameters such as the 4f-electron energy and the hybridization strength with conduction electrons. The result shows a substantial difference in these parameters between the surface and the bulk, indicating that it is important to take into account the surface effect in analyzing photoemission spectra of Ce compounds. It is also found that the 4f surface core-level shift is different between CeIn3 and CeSn3. copyright 1997 The American Physical Society

  13. 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.)

  14. 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.)

  15. Fabrication and characterization of spark plasma sintered Ce:LuAG ceramic for scintillation application

    Science.gov (United States)

    Kumar, S. Arun; Senthilselvan, J.

    2016-05-01

    Rare earth Cerium doped Lutetium Aluminum Garnet (Ce:LuAG) ceramics are widely used as phosphor material in medical imaging and high-energy physics. Due to its technological importance, an attempt has been made to fabricate Ce:LuAG ceramics by using spark plasma sintering (SPS) technique. XRD patterns of SPS sintered Ce:LuAG ceramics reveals a mixed LuAG and CeO2 (antisite defect) phases. The microstructures of SPS sintered Ce:LuAG ceramics shows limited densification, inappropriate compaction of particles and existence of residual pores, voids between the grain boundaries affects the transparency of Ce:LuAG ceramics. Relative density and hardness of post sintered Ce:LuAG ceramic is also determined. The effect of Ce3+ doping concentration and sintering temperature on optical luminescence behavior of Ce:LuAG ceramic is presented.

  16. Eletroforese capilar acoplada à espectrometria de massas (CE-MS: vinte anos de desenvolvimento Capillary electrophoresis coupled to mass spectrometry (CE-MS: twenty years of development

    Directory of Open Access Journals (Sweden)

    Nilson Antonio Assunção

    2008-01-01

    Full Text Available CE-MS has been increasingly used for analysis of a vast array of compounds. This article reviews the different electrophoretic modes, interfaces and mass analyzers that are commonly used in the CE-MS coupling, as well as the technique advantages and performance characteristics. A large compilation of CE-MS applications is also presented. Therefore, this review is both a guide for beginners and a collection of key references for people who are familiar to the technique. Furthermore, this is the first CE-MS review published in a Brazilian journal and marks the installation of the first two commercial CE-MS units in Sao Paulo State.

  17. Effect of Addition of Base on Ceria and Reactivity of CuO/CeO2 Catalysts for Low-Temperature CO Oxidation

    Institute of Scientific and Technical Information of China (English)

    Xiucheng Zheng; Xiaoli Zhang; Shuping Wang; Xiangyu Wang; Shihua Wu

    2007-01-01

    In this work, we have reported the influence of the addition of base (KOH) on the physicochemical property of ceria synthesized by alcohothermal process, and the alcohothermal mechanism was also put forward. Furthermore, the prepared CeO2 was used as the support to prepare CuO/CeO2 catalysts via the wet impregnation method. The samples were characterized by N2 adsorption-desorption, X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM), and temperatureprogrammed reduction by H2 (H2-TPR). The catalytic properties of the CuO/CeO2 catalysts for lowtemperature CO oxidation were studied using a microreactor-GC system. The crystal size of CeO2-A was much smaller than that of CeO2-B, and the corresponding copper oxide catalysts exhibited higher catalytic activity than that of the CeO2-B-supported catalysts under the same reaction conditions. The alcohothermal mechanism indicated that KOH plays a key role in determining the physicochemical and catalytic properties of ceria-based materials.

  18. Fracto-mechanoluminescence and thermoluminescence properties of UV and γ-irradiated Ca2 Al2 SiO7 :Ce(3+) phosphor.

    Science.gov (United States)

    Tiwari, Geetanjali; Brahme, Nameeta; Sharma, R; Bisen, D P; Sao, Sanjay Kumar; Singh, Manisha

    2016-05-01

    Ce(3+) -doped calcium aluminosilicate phosphor was prepared by a combustion-assisted method at an initiating temperature of 600°C. Structural characterization was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The absorption spectra of Ca2 Al2 SiO7 :Ce(3+) showed an absorption edge at 230 nm. The optical characterization of Ca2 Al2 SiO7 :Ce(3+) phosphor was investigated in a fracto-mechanoluminescence (FML) and thermoluminescence (TL) study. The peak of ML intensity increased as the height of impact of the moving piston increased. The TL intensity of Ca2 Al2 SiO7 :Ce(3+) was recorded for different exposure times of UV and γ-irradiation and it was observed that TL intensity was maximum for a UV irradiation time of 30 min and for a γ-dose of 1180 Gy. The TL intensity had three peaks for UV irradiation at temperatures 82°C, 125°C and 203°C. Also the TL intensity had a single peak at 152°C for γ-irradiation. The TL and ML emission spectra of Ca2 Al2 SiO7 :Ce(3+) phosphor showed maximum emission at 400 nm. The possible mechanisms involved in the TL and ML processes of the Ca2 Al2 SiO7 :Ce(3+) phosphor are also explained. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26394791

  19. Optical and gain properties of series of crystals LiF-YF3-LuF3 doped with Ce3+ and Yb3+ ions

    International Nuclear Information System (INIS)

    Here, we present first results of systematic studies of host cation variation impact on spectral-kinetic, photochemical and gain properties of Ce3+-doped LiYF4 (YLF), LiLuF4 (LLF) and LiY1-x Lu x F4 family crystals. 5d-4f luminescence decay of Ce3+ ions studies, together with pump-probe experiments, indicate that previously reported twice higher luminescence quantum yield in LLF compared with that of YLF crystals is provided by more efficient upper lasing level feeding due to recombination and higher color center destruction rate in LLF against YLF crystals. Namely, it is responsible for higher energetic characteristics of laser based on Ce3+:LLF crystals. Strong and wide pump-induced absorption band centered at 310 nm is observed in Ce3+:YLF. This band is shifted to blue and its intensity goes down with Lu content. We have evaluated free charges recombination rate, excited state absorption cross-section for Ce3+ ions and some other photodynamic processes related microparameters. Fitting results indicate that pump-induced color centers lifetime decreases with Lu-content in LiYF4-LiLuF4 mixture and it can be associated with more efficient color center bleaching by Ce3+ ions 5d-4f fluorescence

  20. Fabrication of Ni-5 at. %W Long Tapes with CeO2 Buffer Layer by Reel-to-Reel Method

    DEFF Research Database (Denmark)

    Ma, Lin; Tian, Hui; Yue, Zhao;

    2015-01-01

    A 10-m-long homemade textured Ni-5at.%W (Ni5W) long tape with a CeO2 buffer layer has been prepared successfully by means of rolling-assisted biaxially textured substrate (RABiTS) route followed by a chemical solution deposition method in a reel-to-reel manner. Globally, the Ni5W substrate and CeO2...... film exhibit high homogeneity in terms of biaxial texture over the tape. The average values of full width at half maximum of in-plane and out-of-plane texture are 7.2° and 6.1° in Ni5W substrate, 7.6° and 6.1° in CeO2 buffer layer, respectively, all of those with a small standard deviation. On a...... microlevel, the CeO2 film epitaxially grows well on top of the Ni5W tape. A continuous, smooth, and crack-free morphology was observed on the CeO2 film and the fraction of low-angle grain boundaries (≤ 10°) is about 98 %. This process is a potential possibility for producing long-length textured CeO2/Ni5W...

  1. Investigation of surface defect states in CeO2-y nanocrystals by Scanning−tunneling microscopy/spectroscopy and ellipsometry

    International Nuclear Information System (INIS)

    Synthesis process strongly influences the nanocrystalline CeO2-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 CeO2-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 CeO2-y samples. Scanning tunneling microscopy/spectroscopy and ellipsometry were employed to investigate the electronic band structure of defective CeO2-y nanocrystals. Scanning tunneling spectroscopy measurements demonstrated that inside the band gap of CeO2-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+ and F0) can be formed in the CeO2-y nanocrystals. The formation of different F center defect states inside the ceria gap have a strong impact on the electrical, optical, and magnetic properties of ceria nanocrystals

  2. Luminescence spectroscopy of scintillating glasses doped with Tb3+/Ce3+ with different concentrations of cerium under photo- and electron excitation

    International Nuclear Information System (INIS)

    The luminescence of Li2O–B2O3–P2O5–CaF2 scintillation glass doped Tb3+, Ce3+ under electron beam excitation are investigated. Changing the cerium concentration of 0.2–1 wt% leads to an increase in luminescence intensity of Ce3+ and Tb3+ ions. Luminescence decay of cerium time is 30 ns and weakly depends on the ion concentration and the density of the excitation energy. The luminescence spectrum of the Tb3+ ions and excitation spectrum are dependent on the concentration of Ce3+. The radiative level of cerium ion does not participate in the process of energy transfer from the cerium to terbium. The transfer of energy between Ce3+ and Tb3+ occurs non-radiatively. - Highlights: • A series of Li2O–B2O3–P2O5–CaF2:Tb5, Ce (0.2; 0.5; 1 weight %) glasses were prepared. • Effect of cerium ion with different concentrations on absorption, photoluminescence, cathodoluminescence, decay dynamics was investigated. • The luminescence decay kinetics of cerium was investigated in detail. • The mechanism of energy transfer of lithium–phosphate–borate–fluoride glasses doped with Tb3+ and Ce3+ has been discussed

  3. Atomic transition probabilities of Ce I from Fourier transform spectra

    International Nuclear Information System (INIS)

    Atomic transition probabilities for 2874 lines of the first spectrum of cerium (Ce I) are reported. These data are from new branching fraction measurements on Fourier transform spectra normalized with previously reported radiative lifetimes from time-resolved laser-induced-fluorescence measurements (Den Hartog et al 2009 J. Phys. B: At. Mol. Opt. Phys. 42 085006). The wavelength range of the data set is from 360 to 1500 nm. Comparisons are made to previous investigations which are less extensive. Accurate Ce i transition probabilities are needed for lighting research and development on metal halide high-intensity discharge lamps.

  4. Atomic transition probabilities of Ce I from Fourier transform spectra

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, J E; Wood, M P; Den Hartog, E A [Department of Physics, University of Wisconsin, 1150 University Ave., Madison, WI 53706 (United States); Chisholm, J [Department of Physics, Boston College, 140 Commonwealth Ave., Chestnut Hill, MA 02467 (United States); Nitz, D E [Department of Physics, St. Olaf College, 1520 St. Olaf Ave., Northfield, MN 55057 (United States); Sobeck, J, E-mail: jelawler@wisc.ed, E-mail: chishojd@bc.ed, E-mail: nitz@stolaf.ed, E-mail: mpwood@wisc.ed, E-mail: jsobeck@uchicago.ed, E-mail: eadenhar@wisc.ed [Department of Astronomy and Astrophysics, University of Chicago, 5640 Ellis Ave., Chicago, IL 60637 (United States)

    2010-04-28

    Atomic transition probabilities for 2874 lines of the first spectrum of cerium (Ce I) are reported. These data are from new branching fraction measurements on Fourier transform spectra normalized with previously reported radiative lifetimes from time-resolved laser-induced-fluorescence measurements (Den Hartog et al 2009 J. Phys. B: At. Mol. Opt. Phys. 42 085006). The wavelength range of the data set is from 360 to 1500 nm. Comparisons are made to previous investigations which are less extensive. Accurate Ce i transition probabilities are needed for lighting research and development on metal halide high-intensity discharge lamps.

  5. 57Fe NMR study of nitrided Ce2 Fe17

    International Nuclear Information System (INIS)

    The 57 Fe NMR of Ce2 Fe17 Nx (x=0-1.5) was measured in the ordered magnetic state at 4.2 K. For x = 0, resonances coming from all Fe sites have been identified in the 30 - 45 MHz range. With nitrogenation, new lines appear in the range 37 - 54 MHz. Every nitrogenated sample shows three sets of lines, arising from regions where Ce atoms have 0, 2, and 3 nitrogen atoms as near neighbors. (author). 5 refs., 1 fig

  6. 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...

  7. 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

  8. Response of CeRh2Si2 to pressure

    International Nuclear Information System (INIS)

    Under atmospheric pressure, CeRh2Si2 orders antiferromagnetically at TN = 35 K, with magnetic entropy S = R ell n2 associated with the ordered groundstate. Application of modest pressure (∼9 kbar) to CeRh2Si2 suppresses TN to near zero Kelvin, increases its Sommerfeld coefficient of specific heat by nearly a factor of 3.5 and induces some form of superconductivity below 400 mK that is depressed by a magnetic field at a rate of -80 mK/kG

  9. 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.

  10. 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

  11. Radon alpha and gamma-ray spectrometry with YAP:Ce-scintillator

    International Nuclear Information System (INIS)

    Full text: The detection properties of a YAP:Ce scintillator (YAlO 3:Ce crystal) for radon and radon daughters alpha and 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%), H2SO4 (48%) and HNO3 (65%) have been performed. The experimental array consisted of a bare cylindrical crystal of YAP:Ce optically coupled to a Hamamatsu H5784 photomultiplier with standard bialkali photocatode. The crystal size was 8 mm diameter and 30 mm height. The crystal was positioned at the geometrical center of a 6 l stainless steel light- and gas-tight vessel equipped with gas input/output and a pass-through electrical connectors. Output signals were integrated with a charge preamplifier, shaped with a spectroscopy amplifier (ORTEC-450) and processed by a multichannel analyzer card (ORTEC-Trump). The collected pulse-height spectrum was managed by a suitable MCA emulation software (ORTEC-Maestro32). The device was serially connected to the radon Reference Measurement System (RMS) developed at the National Institute for Metrology of Ionizing Radiations (INMRI-ENEA). The RMS is routinely used for calibration and testing of radon measuring instruments and it provided the reference radon- in-air activity concentration needed for efficiency calibration of the YAP:Ce radon spectrometer. The RMS is based on a cylindrical electrostatic cell with a Si detector. It is used for the alpha spectrometry of the electrostatically collected polonium ions produced in the decay of radon. The radioactive source section consisted in a 35 cm3 glass bulb filled with about 15 kBq radon in air. The internal volume of the whole circuit was about 10 l. The energy calibration curves of the device were obtained irradiating the crystal by means of a set of

  12. Doping effects on protonic conduction in SrCeO3- and BaCeO3 - based perovskites

    International Nuclear Information System (INIS)

    One studied the electric conductivity of SrCe1-xMxO3 and BaCe1-xMxO3 (M - rare-earth elements) proton conductors with the perovskite structure depending on the doping level. Occurrence of maximums and minimums of the proton conductivity was explained on the basis of the typical conductivity was explained on the basis of the typical structure variations of the lattice under doping. One studied the anomalies of BaCe1-xErxO3 ceramics properties within two-phase range on the basis of the concepts about percolation clusters. It is shown, that mobility percolation types in proton-conducting thin films and ceramics should differ essentially

  13. TDPAC study of 140Ce local susceptibility in the Kondo insulator system CeNi1-xCoxSn

    International Nuclear Information System (INIS)

    We have measured the local magnetic susceptibility (χloc) of 140Ce in the alloy system CeNi1-xCoxSn for x=0,0.3 and 0.38 in the range 28-300 K using TDPAC method. The results show strongly reduced χloc values in all the alloys. Using the Coqblin-Schrieffer model we obtain the Kondo temperatures TK to be 90, 112 and 170 K for x=0.0,0.38 and 0.30, respectively. In addition, for x=0.38, the data show an abrupt drop in the χloc value at 48 K indicating a first-order valence transition for Ce ions. (orig.)

  14. 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.

  15. 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...

  16. 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.

  17. Optimization of the Time Response of LaBr3(Ce) Detectors, and Its Dependence on Ce Concentration

    Science.gov (United States)

    Vedia, V.; Mach, H.; Fraile, L. M.; Lalkovski, S.; Udías, J. M.

    Fast inorganic scintillators that exhibit good spectroscopy performance, like LaBr3(Ce), are the crystals of choice for many applications; they play a crucial role in the Ultra Fast Timing technique by virtue of their good energy resolution and fast response [1]. This method, which is very sensitive to the LaBr3(Ce) time resolution, allows measurements of nuclear level lifetimes down to few ps range. There are indications that the nominal Ce concentration does strongly influence on the timing properties as well as it varies the photon yield and the energy resolution [2]. In this work we have searched for the best settings in order to optimize the time resolution of three cylindrical LaBr3(Ce) detectors equipped with crystals identical in volume and shape but with different Ce dopant concentration. The time resolution of every detector depends on the proper selection of the fast photomultiplier tube and the set up parameters that can be further optimized by fine-tuning of the Constant Fraction Discrimination (CFD) and the PMT bias voltage. Very good time resolution can be obtained with the ORTEC 935 CFD for very short time-delays. Timing properties of the three crystals were studied by delayed coincidence measurements against a reference BaF2 detector, whose time response is well known. The LaBr3(Ce) detector and the reference unit were placed in a close geometry with the radioactive source in between. We report timing results measured at the 60Co and 22Na energies.

  18. 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.

  19. 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.

  20. Channeling Studies of CeO₂ and Ce₁-xZrxO₂ Films on Yttria-Stabilized ZrO₂(111)

    Energy Technology Data Exchange (ETDEWEB)

    Shutthanandan, V; Thevuthasan, Suntharampillai; Kim, Y J; Peden, Charles HF

    2001-07-01

    Rutherford backscattering spectrometry and channeling techniques have been used to investigate the crystalline quality and interfacial properties of epitaxially grown CeO₂ and Ce₀.₇Zr₀.₃O₂ films on yttria-stabilized ZrO₂(111) substrates. Both films appear to have high crystalline quality with minimum yeild of Ce in the CeO₂ and Ce₀.₇Zr₀.₃O₂ films determined to be 4.7% and 12.1% respectively. Visibility of more Ce atoms to the ion beam at the interface compared to the bulk of the film indicates that both films show significant disorder at the interface. The normalized angular yield curves obtained from Ce and Zr indicate that the Ce atomic rows in the CeO₂ film are parallel to the Zr atomic rows in the substrates. Both films appear to have high crystalline quality with minimum yeild of Ce in the CeO₂ and Ce₀.₇Zr₀.₃O₂ films determined to be 4.7% and 12.1% respectively. Visibility of more Ce atoms to the ion beam at the interface compared to the bulk of the film indicates that both films show significant disorder at the interface. The normalized angular yield curves obtained from Ce and Zr indicate that the Ce atomic rows in the CeO₂ film are parallel to the Zr atomic rows in the substrates. Approximately 88% of the Zr atoms substitutionally occupy the Ce cation lattice sites in the Ce₀.₇Zr₀.₃O₂ film.

  1. 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.

  2. The role of crystallography and thermodynamics on phase selection in binary magnesium–rare earth (Ce or Nd) alloys

    International Nuclear Information System (INIS)

    In-depth understanding of secondary-phase selection during solidification and ageing is a crucial factor underpinning microstructure design and alloy development. Experimental observations show significantly different behavior of secondary phase selection between the Mg–Nd and Mg–Ce systems. Mg–Nd alloys show a significant degree of metastability of secondary phase selection during solidification, with NdMg12 forming upon slow cooling and NdMg3 upon fast cooling. However, at high heat treatment temperatures and long enough times, Nd5Mg41 forms. In contrast, Mg–Ce alloys form CeMg12 under a wide variety of casting conditions, and this phase remains stable even after long annealing times at high temperatures. However, both Mg–Ce and Mg–Nd alloys undergo a similar precipitation sequence during ageing. Based on recently developed thermodynamic data and crystallographic matching calculations, the phase selection in these two alloy systems under different processing regimes is well explained by the competition between the driving force (reduction in bulk Gibbs energy) and the nucleation energy barrier (increment of surface energy). The approach used here can be also applied to similar phase selection problems in other alloy systems.

  3. CO oxidation on CuO/CeO2 catalyst prepared by solvothermal synthesis: influence of catalyst activation temperature

    International Nuclear Information System (INIS)

    A series of CuO/CeO2 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/CeO2 catalysts have been investigated by XRD, SEM, Raman spectroscopy, SBET measurement, XPS surface analysis, H2-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/CeO2 catalysts activated at lower (<450 °C) and higher (>450 °C) temperatures are attributed to the weaker interaction between CuO and CeO2, and to the sintering of CuO nanoparticles, respectively

  4. 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

  5. CO oxidation on CuO/CeO{sub 2} catalyst prepared by solvothermal synthesis: influence of catalyst activation temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Yuling; Mao, Dongsen, E-mail: dsmao@sit.edu.cn; Sun, Shuaishuai; Fu, Guangying [Shanghai Institute of Technology, Research Institute of Applied Catalysis, School of Chemical and Environmental Engineering (China)

    2015-12-15

    A series of CuO/CeO{sub 2} catalysts were prepared using a solvothermal method and a subsequent activation process. The influences of activation temperature (300–600 °C) on physicochemical properties and catalytic behavior of the prepared CuO/CeO{sub 2} catalysts have been investigated by XRD, SEM, Raman spectroscopy, S{sub BET} measurement, XPS surface analysis, H{sub 2}-TPR, CO-TPD techniques, and CO oxidation testing. The catalyst activated at 450 °C was found to have the highest catalytic activity, which can be ascribed to its higher dispersion of Cu species, higher concentration of oxygen vacancies, and larger amount of more active lattice oxygen. The lower activity of the CuO/CeO{sub 2} catalysts activated at lower (<450 °C) and higher (>450 °C) temperatures are attributed to the weaker interaction between CuO and CeO{sub 2}, and to the sintering of CuO nanoparticles, respectively.

  6. Effect of Ce concentration on luminescence properties of Gd3Ga3Al2O12:Ce nanocrystals

    Science.gov (United States)

    Singh, K. V.; Singh, J. P.; Shinde, S.; Singh, A. K.; Tyagi, M.

    2016-05-01

    Gd3Ga3Al2O12 (GGAG) polycrystalline nano-powders doped with different Ce concentrations were prepared by a co-precipitation method followed by heat treatment at 1000°C for 24 h in air and Ar ambient. Structural and morphological studies show that the synthesized powder is pure phase having nanometer (30-50 nm) particle size. Luminescence studies carried out using UV and X-ray excitations revealed a decrease in the luminescence intensity for a Ce concentration greater than 0.5 mol% due to the concentration quenching.

  7. 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

  8. Tunable multicolor and white luminescence in Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+} doped CePO{sub 4} via energy transfer

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Zhigao [School of Materials Science and Engineering, Key Laboratory of Low-dimensional Materials and Application Technology (Ministry of Education), Xiangtan University, Xiangtan 411105 (China); Lu, Wei [University Research Facility in Materials Characterization and Device Fabrication, The Hong Kong Polytechnic University (Hong Kong); Zeng, Songjun, E-mail: songjunz@hunnu.edu.cn [College of Physics and Information Science and Key Laboratory of Low-dimensional Quantum Structures and Quantum Control of the Ministry of Education, Hunan Normal University, Changsha 410081, Hunan (China); Wang, Haibo; Rao, Ling [School of Materials Science and Engineering, Key Laboratory of Low-dimensional Materials and Application Technology (Ministry of Education), Xiangtan University, Xiangtan 411105 (China); Li, Zheng, E-mail: lizheng@xtu.edu.cn [School of Materials Science and Engineering, Key Laboratory of Low-dimensional Materials and Application Technology (Ministry of Education), Xiangtan University, Xiangtan 411105 (China)

    2015-07-15

    Highlights: • Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+} doped CePO{sub 4} DCNPs were prepared by a one-pot hydrothermal process. • The PL properties and the ET mechanism of these DCNPs were investigated in detail. • These DCNPs exhibit tunable multi-color output under UV excitation. • Intense white emissions can be realized by singly doping Dy{sup 3+} and Mn{sup 2+} in CePO{sub 4} host. - Abstract: In this paper, a series of Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+} doped CePO{sub 4} downconversion nanophosphors (DCNPs) were prepared by a one-pot hydrothermal process. The obtained DCNPs presented monoclinic and hexagonal phase structure with wire-like shape. The photoluminescence (PL) properties and the energy transfer (ET) mechanism of these DCNPs were investigated in detail. The ET mechanism of Ce{sup 3+}/Tb{sup 3+} in CePO{sub 4} host was calculated by means of concentration quenching and spectral overlapping, and calculation results revealed that dipole–dipole interactions should be more responsible. The maximum value of ET efficiency was measured to 87.4% for Tb{sup 3+} doped CePO{sub 4} system. In addition, owing to the efficient ET between Ce{sup 3+} and Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+}, these as-prepared DCNPs exhibit tunable multi-color output under ultra-violet (UV) light excitation. More importantly, the intense cold and warm white emissions can be realized by singly doping 2%Dy{sup 3+} and 20%Mn{sup 2+} in CePO{sub 4} host under UV irradiation, respectively. The corresponding CIE 1931 coordinates were calculated to be (0.30, 0.30) and (0.30, 0.32), respectively, which are closed to the standard white emission (0.33, 0.33). These findings demonstrate the efficient white light emission by singly doped Dy{sup 3+} or Mn{sup 2+} in CePO{sub 4} system for the first time, which is different from commonly used co-doped or tri-doped system. The multicolor tuning and white emission make these Tb{sup 3+}/Dy{sup 3+}/Mn{sup 2+} doped CePO{sub 4} DCNPs potential phosphors in

  9. Práce s dyskalkulikem

    OpenAIRE

    MATĚJKOVÁ, Daniela

    2011-01-01

    Thesis: "Remedial approaches to students with discalculia" defines the term of specific learning disability, individual specific learning disabilities with an emphasis on discalculia (mathematics disorder). It gives a brief overview of the methods, forms, aids (tools), individual re-education practices and affects the possibilities to integrate these students into current elementary school. The practical part deals with the integration of dyscalculia students into the teaching process and to ...

  10. Low Cost CE-NMR with Microcoils for Chemical Detection

    Energy Technology Data Exchange (ETDEWEB)

    Adams, K L; Klunder, G; Demas, V; Malba, V; Bernhardt, A; Evan, L; Harvey, C; Maxwell, R; Herberg, J

    2008-07-25

    Understanding speciation in solids and solutions is important for environmental and toxicological purposes. Capillary electrophoresis (CE) is a simple rapid separation technique that can be used to identify species in solution. CE is particularly is well suited for rapid separations of metal containing samples. Direct on-capillary measurement of metal compound speciation can be obtained with nuclear magnetic resonance (NMR). The development of a low-cost microcoil CE-NMR system for in situ characterization of samples of interest is discussed. High precision laser lithography is used to produce copper sputtered microcoils that have comparable resistivity and quality factors to that of hand wound microcoils. A portable NMR system coupled with a CE system has the potential to identify chemical species in aqueous solutions. In addition, transient isotachophoresis can separate and pre-concentrate samples of interest to obtain separate chemical peaks for speciation by online NMR analysis. We are developing separation assays to determine the speciation of chemical complexes in solutions with minimal perturbation to the original sample equilibrium. On-line NMR measurements will be made downstream of the UV detector.

  11. Low Cost CE-NMR with Microcoils for Chemical Detection

    Energy Technology Data Exchange (ETDEWEB)

    Adams, K; Klunder, G; Demas, V; Malba, V; Bernhardt, A; Evan, L; Harvey, C; Maxwell, R; Herberg, J L

    2009-01-08

    Understanding speciation in solids and solutions is important for environmental and toxicological purposes. Capillary electrophoresis (CE) is a simple rapid separation technique that can be used to identify species in solution. CE is particularly is well suited for rapid separations of metal containing samples. Direct on-capillary measurement of metal compound speciation can be obtained with nuclear magnetic resonance (NMR). The development of a low-cost microcoil CE-NMR system for in situ characterization of samples of interest is discussed. High precision laser lithography is used to produce copper sputtered microcoils that have comparable resistivity and quality factors to that of hand wound microcoils. A portable NMR system coupled with a CE system has the potential to identify chemical species in aqueous solutions. In addition, transient isotachophoresis can separate and pre-concentrate samples of interest to obtain separate chemical peaks for speciation by online NMR analysis. We are developing separation assays to determine the speciation of chemical complexes in solutions with minimal perturbation to the original sample equilibrium. On-line NMR measurements will be made downstream of the UV detector.

  12. 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.

  13. Improved performance of QCD code on ALiCE

    CERN Document Server

    Sroczynski, Z

    2003-01-01

    We present results for the performance of QCD code on ALiCE, the Alpha-Linux Cluster Engine at Wuppertal. We describe the techniques employed to optimise the code, including the metaprogramming of assembler kernels, the effects of data layout and an investigation into the overheads incurred by the communication.

  14. Investigation of positive parity degenerate dipole bands in 133Ce

    International Nuclear Information System (INIS)

    A pair of dipole bands B2 and B3 have been identified with same parity in 133Ce. To study the decay properties of these bands and measure their electromagnetic transition strengths, an experiment was carried out to collect high statistics and high fold γ-coincidence data

  15. 32 CFR Appendix B to Part 247 - CE Publications

    Science.gov (United States)

    2010-07-01

    ... statement of work with appropriate contractual terms and conditions, using 48 CFR chapter I and II as guides... Printing. While CE contracts are not subject to the FAR (48 CFR chapter I) or the DFARS (48 CFR chapter II... sources include the OASD(PA), AFIS, the Military Departments and their subordinate levels of command,...

  16. Magnetotransport in CeCu6-xAux

    International Nuclear Information System (INIS)

    We report on a comparative study of the low-temperature magnetoresistance ρxx(B) and Hall resistance ρxy(B) of CeCu6-xAux for 0=xx(B), and of the anomalous Hall effect and bandstructure effects of the heavy-quasiparticle bands affecting ρxy(B)

  17. O- centers in LuAG:Ce,Mg ceramics

    Czech Academy of Sciences Publication Activity Database

    Hu, C.; Liu, S.; Fasoli, M.; Vedda, A.; Nikl, Martin; Feng, X. Q.; Pan, Y.B.

    2015-01-01

    Roč. 9, č. 4 (2015), s. 245-249. ISSN 1862-6254 R&D Projects: GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : scintillator * hole center * EPR * LuAG * Ce 3+ Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.142, year: 2014

  18. 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...

  19. A comparison of 3D-CTA and 4D-CE-MRA for the dynamic monitoring of angiogenesis in a rabbit VX2 tumor

    International Nuclear Information System (INIS)

    Purpose: To compare three-dimensional computed tomography angiography (3D-CTA) and four-dimensional contrast-enhanced magnetic resonance angiography (4D-CE-MRA) for the in vivo monitoring of tumor angiogenesis. Materials and methods: VX2 tumors were implanted into the right thigh muscle of 30 New Zealand white rabbits. The animals were randomly assigned to 5 groups, which, respectively, were scanned by 3D-CTA and 4D-CE-MRA on day 4, 7, 10, 13, or 16 after tumor implantation. After scanning, tumors were resected and processed for conventional histology and CD-31 immunohistochemistry. Tumor volume measurements derived from CT and MR imaging were compared with histopathological data. The minimum tumor diameter and the number of new tumor blood vessels detectable by 3D-CTA and 4D-CE-MRA were also compared. Results: There were no significant differences in the tumor volume measurements derived from CT, MR, and histological analysis. The minimum diameter of tumor vessels detectable by 3D-CTA (0.68 ± 0.07 mm) was significantly less than that by 4D-CE-MRA (0.85 ± 0.12 mm) (P = 0.005). The number of tumor vessels detected by each imaging method was not significantly different until day 13 after implantation, when 3D-CTA detected a greater number (P < 0.001). The morphologic process of tumor angiogenesis was demonstrated dynamically by 3D-CTA and 4D-CE-MRA in vivo. Conclusions: Tumor angiogenesis can be dynamically monitored in vivo by 3D-CTA and 4D-CE-MRA. Of the two methods, 3D-CTA has better spatial resolution, but 4D-CE-MRA allows temporal resolution of tumor angiogenesis.

  20. 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.

  1. 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.

  2. Optically and thermally stimulated luminescence of KMgF3:Ce3+ and NaMgF3:Ce3+

    International Nuclear Information System (INIS)

    The potentialities of optically stimulated luminescence (OSL) for personal dosimetry of ionising radiation have stimulated the search for new synthetic materials with good dosimetric properties. The sensitivity of two new OSL materials KMgF3 and NaMgF3 doped with Ce3+ ions has been evaluated and found to be of the same order of magnitude as that of Al2O3:C. Several other characteristics have also been investigated. Promising results for KMgF3:Ce are the high sensitivity and the low fading. However, this material suffers from a high self-dose due to the presence of 40K. NaMgF3:Ce is sensitive as well but shows strong fading. Interesting information on the mechanism has been obtained by correlating the signals of OSL and TL. Furthermore, the different bleachabilities under blue LED illumination of the strongly overlapping glow peaks allowed the extraction of one single peak for KMgF3:Ce3+. The results demonstrate new possibilities offered by the combination of TL and OSL. (author)

  3. Evaluation of production samples of the scintillators LaBr3:Ce and LaCl3:Ce

    International Nuclear Information System (INIS)

    We report on the evaluation of the performance of two recently developed scintillator materials, LaCl3:Ce and LaBr3:Ce, at the task of gamma ray spectroscopy. Their performance is compared to a standard scintillator used for gamma ray spectroscopy--a 25 mm diameter 25 mm tall cylinder of NaI:Tl. We measure the pulse height, energy resolution, and full-energy efficiency of production LaBr3:Ce and LaCl3:Ce scintillation crystals of different sizes and geometries for a variety of gamma-ray energies. Using production rather than specially selected crystals will establish whether immediate large-scale use is feasible. The crystal is excited by gamma rays from one of six isotopic sources (125I, 241Am, 57Co, 22Na, 137Cs, and 60Co) placed 15 cm away from the scintillator. Our measurements show that both LaCl3 and LaBr3 outperform NaI:Tl in almost all cases. They outperform NaI:Tl at all energies for the photopeak fraction and counting rate measurements, and for energy resolution at higher energies (above 200 keV for LaCl3 and 75 keV for LaBr3). The performance of production crystals is excellent and these scintillators should be considered for immediate use in systems where stopping power and energy resolution are crucial

  4. 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 ℃).

  5. 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.

  6. 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 ℃.

  7. Selective catalytic reduction of NO with NH3 over sol-gel-derived CuO-CeO2-MnOx/y-Al2O3 catalysts

    International Nuclear Information System (INIS)

    Sulfur dioxide (SO2) and nitrogen oxides (NOX) are major air pollutants. Before emitting flue gas into the atmosphere, these pollutants must be removed using various processes. A sol-gel process has been developed to prepare alumina granular support and catalyst. The sol-gel-derived alumina granules have a large surface area, large pore volume, uniform pore size distribution, and excellent mechanical properties such as attrition resistance and crush strength. This paper discussed an experiment that synthesized two catalysts using the sol-gel oil-drop method. The paper described the experimental procedure and presented the results of the experiment. This included the effect of temperature on the catalytic activity of CuO-CeO2-MnOx/y-Al2O3 catalysts; desorption of ammonia (NH3) and nitric oxide (NO) on the CuO-CeO2-MnOx/y-Al2O3 catalysts; transient response of NH3 and NO on CuO-CeO2-MnOx/y-Al2O3 catalysts; and the reaction kinetics and characterization of CuO-CeO2-MnOx/y-Al2O3 catalysts. It was concluded that the CuO-CeO2-MnOx/y-Al2O3 catalysts made by the sol-gel method have higher activity and a wider operating temperature range. 17 refs., 1 tab., 9 figs

  8. Preparation and luminescence properties of Ce 3+ and/or Tb 3+ doped LaPO 4 nanofibers and microbelts by electrospinning

    Science.gov (United States)

    Hou, Zhiyao; Wang, Lili; Lian, Hongzhou; Chai, Ruitao; Zhang, Cuimiao; Cheng, Ziyong; Lin, Jun

    2009-04-01

    Ce 3+ and/or Tb 3+ doped LaPO 4 nanofibers and microbelts have been prepared by a combination method of sol-gel process and electrospinning. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), low voltage cathodoluminescence (CL) and time-resolved emission spectra as well as kinetic decays were used to characterize the resulting samples. SEM and TEM results indicate the as-formed precursor fibers and belts are smooth, and the as-prepared nanofibers and microbelts consist of nanoparticles. The doped rare-earth ions show their characteristic emission under ultraviolet excitation, i.e. Ce 3+ 5 d-4 f and Tb 3+5D 4- 7F J ( J=6-3) transitions, respectively. The energy transfer process from Ce 3+ to Tb 3+ in LaPO 4:Ce 3+, Tb 3+ nanofibers was further studied by the time-resolved emission spectra. Under low-voltage electron beam excitation, LaPO 4:Ce 3+, Tb 3+ microbelt phosphors have a higher intensity than that of nanofiber phosphors.

  9. 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

  10. 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.

  11. Evaluation of a new low sheath-flow interface for CE-MS.

    Science.gov (United States)

    González-Ruiz, Víctor; Codesido, Santiago; Far, Johann; Rudaz, Serge; Schappler, Julie

    2016-04-01

    The current trend for increasing technical complexity in the field of CE-ESI-MS interfaces has incited for more accessible alternatives. In this work, a simple low sheath-flow ESI interface operating in the submicroliter nanospray regime without nebulizing gas assistance was evaluated. The use of sheath liquid enabled improving the ionization of the analytes, while the absence of nebulizing gas minimized sample dilution and loss of efficiency. After a rapid qualification, the effect of main operational parameters such as sheath liquid composition and flow rate, working distance and ESI potential was studied. Simulation of the mixing processes inside the Taylor cone proved its size to be of utmost importance in band broadening processes. As a proof of concept, the interface was eventually applied to a set of representative basic drugs analyzed by CE-TOF/MS. Limits of detection reached the 25-100 ppb range with suitable robustness and repeatability results. This design has demonstrated good performance while being simple and accessible to the user. PMID:26846463

  12. 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

  13. 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...

  14. CeRu2Si2: an example of heavy fermion metamagnetism

    International Nuclear Information System (INIS)

    The strong interplay between lattice, electronic and magnetic properties in CeRu2Si2 is emphasized. Special attention is given on the broadening of the metamagnetic-like transition. Comparison is made with similar phenomena in other heavy fermion cerium compounds: CeCu6, CeAl3. ((orig.))

  15. CeCu2Si2: More nearly magnetic than UBe13

    International Nuclear Information System (INIS)

    We have prepared and studied, via dc and ac susceptibility and specific heat, samples of Ce1-xMxCu2.2Si2, with M=Y, La, and Lu. All samples show an increase in the Wilson ratio, ∝χ/γ, with the low-temperature χ per Ce mole increasing from Lu to Y to La and Ce1-xLaxCu2.2Si2 actually having χ(1.8 K) per Ce mole larger than in pure CeCu2.2Si2 for x>0.5. The low-temperature specific heat of CeCu2.2Si2 is enhanced by dilution by La, when normalized per Ce mole, whereas dilution by Y and Lu strongly depresses the per-Ce-mole specific heat. These two contrasting effects may be linked to a volume effect, since Y and Lu contract the CeCu2.2Si2 lattice while La expands it. The fact that dilute Ce in the expanded host lattice Ce1-xLaxCu2.2Si2 has increased χ and γ at low temperatures argues for a nearness to magnetism (substantiated by recent work on Ce1-xThxCu2.2Si2) that contrasts with results for U1-xMxBe13

  16. CE IGCC repowering project: Materials for coal gasification environment. Topical report, June 1993

    Energy Technology Data Exchange (ETDEWEB)

    Gibbons, T.B.; O`Neill, J.K.; Plumley, A.L.; Thibeault, P.R.; Waryasz, R.W.

    1993-10-01

    A task to develop material requirements and a materials testing strategy was established with the Materials and Water Chemistry Department of the ABB Power plant Laboratories. This involved examining the requirements for each system under ABB CE scope. The basis for the material recommendations was largely based on in-house test programs under DOE contract and ABB CE experience. Consultants were utilized in a parallel task to assist in the design and material specification for the solids handling systems. ABB CE experience includes operating data from a former process development unit (PDU) located in Windsor, Connecticut. The unit gasified Pittsburgh seam coal at a nominal firing rate of 120 tons per day. The objectives of the program were to produce clean, low-Btu gas from coal, and to provide the design information for scale-up to commercial-size plants. The results of the task were used to specify and, depending on scope, design the equipment used in the plant. A detailed document was developed and used to generate a Metallurgical Flow Diagram. Specifications were developed from this diagram. For the equipment designed, these selections were provided to representatives of cognizant design and manufacturing departments. In addition, where appropriate, recommendations were made for operating procedures and for design changes. Specified materials will be again evaluated during detailed engineering. In some areas the results of the task were not conclusive. Additional investigation will be required. These areas are the types of approaches which can be taken to accommodate product gas sulfidation resistance and solids transport erosion.

  17. Hydrogen activation, diffusion, and clustering on CeO₂(111): a DFT+U study.

    Science.gov (United States)

    Fernández-Torre, Delia; Carrasco, Javier; Ganduglia-Pirovano, M Verónica; Pérez, Rubén

    2014-07-01

    We present a comprehensive density functional theory+U study of the mechanisms underlying the dissociation of molecular hydrogen, and diffusion and clustering of the resulting atomic species on the CeO2(111) surface. Contrary to a widely held view based solely on a previous theoretical prediction, our results show conclusively that H2 dissociation is an activated process with a large energy barrier ~1.0 eV that is not significantly affected by coverage or the presence of surface oxygen vacancies. The reaction proceeds through a local energy minimum--where the molecule is located close to one of the surface oxygen atoms and the H-H bond has been substantially weaken by the interaction with the substrate--, and a transition state where one H atom is attached to a surface O atom and the other H atom sits on-top of a Ce(4+) ion. In addition, we have explored how several factors, including H coverage, the location of Ce(3+) ions as well as the U value, may affect the chemisorption energy and the relative stability of isolated OH groups versus pair and trimer structures. The trimer stability at low H coverages and the larger upward relaxation of the surface O atoms within the OH groups are consistent with the assignment of the frequent experimental observation by non-contact atomic force and scanning tunneling microscopies of bright protrusions on three neighboring surface O atoms to a triple OH group. The diffusion path of isolated H atoms on the surface goes through the adsorption on-top of an oxygen in the third atomic layer with a large energy barrier of ~1.8 eV. Overall, the large energy barriers for both, molecular dissociation and atomic diffusion, are consistent with the high activity and selectivity found recently in the partial hydrogenation of acetylene catalyzed by ceria at high H2/C2H2 ratios. PMID:25005299

  18. 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.

  19. Synthesis of CeFe10.5Mo1.5 with ThMn12-type structure by melt spinning

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, C; Tessema, M; Meyer, MS; Pinkerton, FE

    2013-06-01

    Rare earth compounds RFe12_xMx with tetragonal ThMn12-type structure are of great research interest for potential applications as permanent magnets. These materials are known to serve as the precursors for nitriding and hydriding processes which in certain conditions can dramatically increase the Curie temperature, spontaneous magnetization, and affect the magnetic anisotropy. In this paper, we report the phase study of CeFe10.5Mo1.5 samples melt spun at various surface wheel speeds vs between 5 m/s and 60 m/s. The results from quantitative Rietveld analysis indicate that the as-spun ribbons are a mixture of primary CeFe10.5Mo1.5 phase with impurity phases such as Ce2Fe17, Fe-Mo alloy and CeFe2. When the wheel speed vs is below 25 m/s, CeFe10.5Mo1.5 phase accounts for greater than 85 wt% in the as-spun ribbons, while the Fe-Mo alloy is the only detectable impurity phase. Above v(s)=25 m/s, as the wheel speed increases, CeFe10.5Mo1.5 phase decreases monotonically to about 60 wt% at v(s)=6O m/s while the amounts of impurity phases increase. Thermogravimetric measurement indicates that the Curie temperature T-c. corresponding to CeFe10.5Mo1.5 phase is 341 K. As a result, the best performing sample melt spun at v(s),=15 m/s only exhibits an energy product BHmax=0.121 MGOe at room temperature. Although such a number is modest for a permanent magnet, further nitriding is expected to greatly enhance the Curie temperature, and hence the magnetic performance. (C) 2013 Elsevier B.V. All rights reserved.

  20. 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.

  1. 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.

  2. 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.

  3. Air, aqueous and thermal stabilities of Ce3+ ions in cerium oxide nanoparticle layers with substrates

    KAUST Repository

    Naganuma, Tamaki

    2014-01-01

    Abundant oxygen vacancies coexisting with Ce3+ ions in fluorite cerium oxide nanoparticles (CNPs) have the potential to enhance catalytic ability, but the ratio of unstable Ce3+ ions in CNPs is typically low. Our recent work, however, demonstrated that the abundant Ce3+ ions created in cerium oxide nanoparticle layers (CNPLs) by Ar ion irradiation were stable in air at room temperature. Ce valence states in CNPs correlate with the catalytic ability that involves redox reactions between Ce3+ and Ce4+ ions in given application environments (e.g. high temperature in carbon monoxide gas conversion and immersion conditions in biomedical applications). To better understand the mechanism by which Ce3+ ions achieve stability in CNPLs, we examined (i) extra-long air-stability, (ii) thermal stability up to 500 °C, and (iii) aqueous stability of Ce 3+ ions in water, buffer solution and cell culture medium. It is noteworthy that air-stability of Ce3+ ions in CNPLs persisted for more than 1 year. Thermal stability results showed that oxidation of Ce 3+ to Ce4+ occurred at 350 °C in air. Highly concentrated Ce3+ ions in ultra-thin CNPLs slowly oxidized in water within 1 day, but stability was improved in the cell culture medium. Ce 3+ stability of CNPLs immersed in the medium was associated with phosphorus adsorption on the Ce3+ sites. This study also illuminates the potential interaction mechanisms of stable Ce3+ ions in CNPLs. These findings could be utilized to understand catalytic mechanisms of CNPs with abundant oxygen vacancies in their application environments. © The Royal Society of Chemistry 2014.

  4. 10 GHz 2ωce heavy ion source CAPRICE

    International Nuclear Information System (INIS)

    By using a new 0.8 T sextupole, the second step of metamorphosis of the ECR magnetic structure of the CAPRICE source is achieved. The 2ωce surface is now extended everywhere in the second stage except the extraction part. Thus, a strong flux of deconfined plasma is available at the extraction area and therefore high currents of high charge state ions are extracted. Optimum rf power is increased by a factor of 3 with respect to the single ωce profile and currents of high charge state ions are increased by a factor of 10. The optimum performance for all gases and all solid elements is shown. The third step of the metamorphosis is planned for next year to achieve and work with two complete ECR surfaces. Future developments are also expected. (orig./HSI)

  5. Anisotropic Thermoelectric Properties of CeRhAs with Superstructures

    International Nuclear Information System (INIS)

    We report thermoelectric, magnetic and structural properties of the so-called Kondo semiconductor CeRhAs. The resistivity ρ(T) along the three principal axes exhibits step-like anomalies at T1 = 370, T2 = 235 and T3 = 165 K, respectively, and increases by two orders of magnitude on cooling to 1.5 K. Below T1 an abrupt drop in the magnetic susceptibility along all the axes is associated with the cell doubling along the b - and c -axes, suggesting a charge-density-wave transition. Below T3 the increase in the thermopower is strongest along the a -axis with a maximum of 186 μV/K at 35 K. The thermoelectric figure of merit becomes largest along the c-axis with the maximum value of 1.0x10-3/K, being comparable with that of CePd3. (author)

  6. 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...

  7. 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.

  8. Dynamic correlations in the Kondo system CeAl2

    International Nuclear Information System (INIS)

    Complete text of publication follows. CeAl2 exhibits a very complex magnetic behaviour due to the interplay between the RKKY-interaction and the Kondo effect not fully investigated until now. Inelastic neutron scattering experiments have been performed on CeAl2 below the Neel temperature TN = 3.8 K in the zero field multi-domain-state and also in a single-domain-state generated by applying a magnetic field and have determined the magnetic excitation spectra along the [1-10]-direction. In both cases the magnetic excitations are found to be very broad in energy and they differ only slightly in the intensity distribution. In zero magnetic field the excitation spectra do not change much with temperature and the inelastic signal is still observed at temperatures up to about 4 times TN. (author)

  9. 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.

  10. CE separation approaches for combinations of anthracyclines and taxanes.

    Science.gov (United States)

    Shakalisava, Yuliya; Regan, Fiona

    2009-09-01

    For the first time the versatility of CE is demonstrated for the separation of different types of anticancer drugs - anthracyclines and taxanes simultaneously. The use of these drugs in combination therapy for cancer has sparked interest in the development of methods for potential application. The simultaneous analysis of anthracyclines and taxanes can significantly increase a sample throughput of a clinical laboratory. The study shows the potential of CE for such a challenge: anthracyclines and taxanes were separated by CZE, MEKC and MEEKC. The MEEKC method was successfully applied to these compounds for the first time and was characterised by very short separation time, high efficiencies of peaks and was proven to be generic for the separation of different combinations of anthracyclines and taxanes. This separation approach could be highly beneficial for clinical analysis if applied with a sensitive detection system. MEKC and high-speed MEEKC methods were proven to show good potential in their application to plasma samples. PMID:19681049

  11. TRX and UO2 criticality benchmarks with SAM-CE

    International Nuclear Information System (INIS)

    A set of thermal reactor benchmark calculations with SAM-CE which have been conducted at both MAGI and at BNL are described. Their purpose was both validation of the SAM-CE reactor eigenvalue capability developed by MAGI and a substantial contribution to the data testing of both ENDF/B-IV and ENDF/B-V libraries. This experience also resulted in increased calculational efficiency of the code and an example is given. The benchmark analysis included the TRX-1 infinite cell using both ENDF/B-IV and ENDF/B-V cross section sets and calculations using ENDF/B-IV of the TRX-1 full core and TRX-2 cell. BAPL-UO2-1 calculations were conducted for the cell using both ENDF/B-IV and ENDF/B-V and for the full core with ENDF/B-V

  12. 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.

  13. 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

  14. Commensurate-commensurate magnetic phase transitions in CeSb

    DEFF Research Database (Denmark)

    Lebech, Bente; Broholm, C.; Clausen, K.; Vogt, O.

    The q=2/3 to q=4/7 commensurate-commensurate phase transition in CeSb has been studied by neutron diffraction. On cooling the commensurate wave vector q changes abruptly from 2/3 to a higher-order commensurate value (≈14/23) at T1

  15. Experimental investigation of the structure of 124Ce

    International Nuclear Information System (INIS)

    Gamma-ray transitions have been observed for the first time in 124Ce using the Daresbury Recoil Separator. The excitation energy of the first excited state, 142keV, implies a deformation epsilon2 approx. = 0.31. This value confirms the trend to higher deformation for the more neutron-deficient cerium isotopes, but it is larger than that predicted by recent calculations. (author)

  16. 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.

  17. 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 t...... this a qualitative explanation for the anomalously high Curie temperature of the compound is proposed. Furthermore, the spin density is found to be highly nonspherical....

  18. A new 144Ce/144Pr radioisotope generator system

    International Nuclear Information System (INIS)

    A miniaturized generator system was developed containing manganese dioxide-coated alumina on which 144Ce is deposited and from which 144Pr is eluted with an aqueous solution of 1% KIO3 in 1 N nitric acid. More than 60% of the 144Pr was recovered with a 99.9% radionuclide purity even after 2000 ml eluant and 1000 1 or air had been passed through the column. (author)

  19. 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.

  20. Parallel CE/SE Computations via Domain Decomposition

    Science.gov (United States)

    Himansu, Ananda; Jorgenson, Philip C. E.; Wang, Xiao-Yen; Chang, Sin-Chung

    2000-01-01

    This paper describes the parallelization strategy and achieved parallel efficiency of an explicit time-marching algorithm for solving conservation laws. The Space-Time Conservation Element and Solution Element (CE/SE) algorithm for solving the 2D and 3D Euler equations is parallelized with the aid of domain decomposition. The parallel efficiency of the resultant algorithm on a Silicon Graphics Origin 2000 parallel computer is checked.

  1. Gd interactions in (Ce,Gd)Al3

    International Nuclear Information System (INIS)

    The susceptibility of Ce1√/sub x/Gd/sub x/Al3 for 0.08≤x≤0.9 has an anomaly which resembles that associated with a spin-glass transition. For x greater than the percolation threshold concentration for antiferromagnetism at x≅0.5, the size of the susceptibility anomaly decreases two orders of magnitude and a resistivity anomaly appears

  2. 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.

  3. Investigation into kinetics of redox interaction in the system Ce(4) β-diketonate-additional ligand

    International Nuclear Information System (INIS)

    The rate of reduction of β-diketonate complexes of Ce(4) to Ce(3) β-diketonates in benzene solution in the presence and in the absence of additional ligands is studied using spectrophotometry. The rate of reduction of Ce(4) β-diketonates increases in the series Ce(TTFA)44444 (TTFA - thenoyltrifluoroacetone, DPM- --dipivaloylmethane, DBM - dibenzoylemethane, BA benzoylacetone, AA - acetylaceton). The studied phosphorus-containing additional ligands as to their effect on the rate of Ce (4) reduction can be arranged in the following order: trioctylphosphine oxide>triphenylphosphine oxide>tributyl phosphate

  4. 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.

  5. Carrier-free 139Ce obtaining and separation from lanthanum target

    International Nuclear Information System (INIS)

    The isotope 139Ce is widely used as a component of calibration multisources. In our laboratory preparation of high purity carrier-free 139Ce was worked out. The thick target yield of 139Ce produced by bombardment of 139La with 13 MeV deuterons was found to be 4.3 μCi/μAh. The product 139Ce was separated from macroquantities of lanthanum by extraction with diethyl ether (DEE) in the system DEE-HNO3. The optimum conditions of 139Ce isolation were determined. (author). 4 figs

  6. Magnetic Phase Transitions of CeSb. I

    DEFF Research Database (Denmark)

    Fischer, Pernille Hertz; Lebech, Bente; Meier, G.; Rainford, B. D.; Vogt, O.

    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...... disordered magnetic phases of antiphase domain type ((100) superstructures) with (100) orientation of the magnetic moments. At 4.4K, the ordered magnetic moment equals (2.10+or-0.04) mu B, which corresponds to the free-ion value of 2.14 mu mB for Ce3+. The temperature dependence of the ordered moment shows a...... first-order phase transition at TN. At approximately TN/2 there is a first-order phase transition to a FCC type IA low-temperature configuration. The unusual magnetic properties of CeSb, which result from anisotropic exchange and crystalline electric field effects, resemble those of certain actinide Na...

  7. Zur Analyse der Fügung ce fripon de valet

    Directory of Open Access Journals (Sweden)

    Moritz Regula

    2016-02-01

    Full Text Available Alle bisherigen Deutungen des Syntagmas ce tripon de valet sorgfältig überprüfend, gelangt S t. Lyer in einer historisch und psychologisch unter­ bauten Sonderstudie: Les appositions romanes du type li tel d'anemis, ce tripon de valet (ZRPh, LVIII, S. 348-359 zu dem überzeugenden Ergebnis, dass die: erwähnten Fügungen nicht als Fortsetzung der lat. Wendungen scelus viri, jlagitium hominis, monstrum mulieris, sondern als Neuschöpfung der Affektsyntax zu betrachten sind. Auch darin wird man dem Verfasser beipflichten müssen, dass die Fügung ce tripon de valet nicht mit dem in mehrfacher Hinsicht abweichenden Typ la ville de Paris auf einen Plan gestellt werden kann. Wenn ich trotz der in den Hauptpunkten bestehenden Übereinstimmung dasselbe Problem nochmals aufrolle, geschieht es, urn nach Beseitigung einer Unvollkommenheit in der Strukturanalyse eine eindeutige Diagnose der Satzgliendschaft beider Elemente zu gewinnen.

  8. 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...

  9. 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)

  10. Optical properties of CeO2 thin films

    Indian Academy of Sciences (India)

    S Debnath; M R Islam; M S R Khan

    2007-08-01

    Cerium oxide (CeO2) thin films have been prepared by electron beam evaporation technique onto glass substrate at a pressure of about 6 × 10-6 Torr. The thickness of CeO2 films ranges from 140–180 nm. The optical properties of cerium oxide films are studied in the wavelength range of 200–850 nm. The film is highly transparent in the visible region. It is also observed that the film has low reflectance in the ultra-violet region. The optical band gap of the film is determined and is found to decrease with the increase of film thickness. The values of absorption coefficient, extinction coefficient, refractive index, dielectric constant, phase angle and loss angle have been calculated from the optical measurements. The X-ray diffraction of the film showed that the film is crystalline in nature. The crystallite size of CeO2 films have been evaluated and found to be small. The experimental -values of the film agreed closely with the standard values.

  11. 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.  ……

  12. Synthesis and Characterization of Ce-Containing MCM-41

    Institute of Scientific and Technical Information of China (English)

    CHIEN ShuHua; CHEN ChunLong

    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.

  13. 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.)

  14. 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.

  15. 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)

  16. 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.

  17. 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

  18. Defects induced in Yb3+/Ce3+ co-doped aluminosilicate fiber glass preforms under UV and γ-ray irradiation

    DEFF Research Database (Denmark)

    Chiesa, Mario; Mattsson, Kent Erik; Taccheo, Stefano; Robin, Thierry; Lablonde, Laurent; Mechin, David; Milanese, Daniel

    2014-01-01

    high Yb content samples is observed on as prepared samples regardless of the presence of Ce3+ ions. Si-E′ and Al-OHC centers were identified upon photon irradiation. The results are correlated to the micro-structural origin of the photodarkening process occurring in Ce–Yb doped glass fibers.......A set of Ce-/Yb-co-doped silica optical fiber preform cores, differing in terms of dopant concentrations are studied by Electron Paramagnetic Resonance (EPR) spectroscopy before and after irradiation of the samples with excimer UV laser light and γ-rays. Evidence of Yb3+ clustering in the case of...

  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. 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

  1. 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.

  2. Synthesis of Zr O2-Ce O2 ceramic powders by coprecipitation

    International Nuclear Information System (INIS)

    Ceria stabilized zirconia powders with 8 to 16 mol% (Ce O2) were prepared by a coprecipitation process with ammonium hydroxide solutions. Wet chemical process were used with the purpose of producing dense ceramics with appropriate microstructure at low sintering temperatures. For the characterization of the produced powders, techniques as particle size distribution, specific surface measurement crystalline phase identification and others were used. It has been found that powders with ceria contents higher than 12 mol% shows tetragonal phase stabilization. Ceramic bodies were pressed and sintered at 1500 and 1600deg C for 1 hour, with good final densification and microstructure formed by uniformly shaped grains with diameters of about 1 μm. (author)

  3. 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...

  4. 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)

  5. Effect of Mg2+ co-doping on the scintillation performance of LuAG:Ce ceramics

    International Nuclear Information System (INIS)

    Ce-doped Lu3Al5O12 optical ceramics co-doped with Mg2+ are fabricated by solid-state reaction method and further optimized by an air-annealing process. Mg2+ co-doping leads to a significant decrease of thermoluminescence intensity above room temperature and an increase of scintillation light yield (LY) value and fast component content even if the overall scintillation efficiency decreases. Scintillation LY of ∝21900 ph/MeV has been achieved with a short shaping time of 1 μs, and the ratio of LY values for 1 μs and 10 μs shaping times was as high as 79%. The acceleration of scintillation response induced by Mg2+ co-doping and the role of Ce4+ ions in the scintillation mechanism are discussed. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. 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.

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

    International Nuclear Information System (INIS)

    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 CePO4 was formed on the surface, and the content of crystal water decreased greatly, leading to improvement of the film performance with less micro-cracks

  8. 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.)

  9. 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.

  10. Structural and luminescence study of Ce3+ and Tb3+ doped Ca3Sc2Si3O12 garnets obtained by freeze-drying synthesis method

    Science.gov (United States)

    Velázquez, J. J.; Fernández-González, R.; Marrero-Jerez, J.; Rodríguez, V. D.; Lukowiak, A.; Chiappini, A.; Chiasera, A.; Ferrari, M.; Núñez, P.

    2015-08-01

    Ca3Sc2Si3O12 garnets doped with Ce3+ and Tb3+ ions were synthesized by a freeze-drying precursor method. The structural characterization was performed by X-ray diffraction (XRD) and Raman spectroscopy. Scanning Electron Microscopy (SEM) images of the calcined material were studied. High temperature treatments and doping with RE3+ ions resulted in a reduction of the secondary phases (Sc2O3) and an increase of the mean size of the nanocrystals, from 75 to 149 nm. These effects were confirmed by means of Raman spectra. Moreover, luminescence features of Ce3+ and Tb3+ doped samples indicated that these ions are effectively incorporated into the crystalline phase. In addition, the energy transfer processes between Ce3+ and Tb3+ ions in codoped garnets have been studied.

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. 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  |

  16. 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.

  17. High count rate γ-ray spectroscopy with LaBr3:Ce scintillation detectors

    International Nuclear Information System (INIS)

    The applicability of LaBr3:Ce detectors for high count rate γ-ray spectroscopy is investigated. A 3 in.×3 in. LaBr3:Ce detector is used in a test setup with radioactive sources to study the dependence of energy resolution and photo peak efficiency on the overall count rate in the detector. Digitized traces were recorded using a 500 MHz FADC and analysed with digital signal processing methods. Good performance is obtained using standard techniques up to about 500 kHz counting rate. A pile-up correction method is applied to the data in order to further improve the capabilities at even higher rates with a focus on recovering the losses in efficiency due to signal pile-up. It is shown that γ-ray spectroscopy can be performed with only moderate lossen in efficiency and high resolution at count rates even above 1 MHz and that the performance can be enhanced in the region between 500 kHz and 10 MHz by using the applied pile-up correction techniques.

  18. 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

  19. 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.

  20. 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.