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Sample records for ce winsor site

  1. Implantation sites of Ce and Gd in diamond

    CERN Document Server

    Bharuth-Ram, K; Hofsäss, H C; Ronning, C; Dietrich, M

    2002-01-01

    The implantation sites of rare earth (RE) probes /sup 141/Ce (t/sub 1 /2/=32 d) and /sup 149/Gd (t/sub 1/2/=9.28 d) in diamond have been investigated using the emission channeling (EC) technique. Parent isotopes /sup 141/Cs and /sup 149/Dy were implanted into type IIa, diamond samples at an energy of 60 keV at the online isotope separator ISOLDE at CERN. /sup 141/Cs decays through the chain /sup 141/Cs-/sup 141/Ba-/sup 141/La-/sup 141/Ce-/sup 141/ Pr. EC measurements were made on the 102 keV conversion electrons emitted in the decay of /sup 141/Pr to its ground state. The decay of /sup 149 /Dy follows the chain /sup 149/Dy-/sup 149/Tb-/sup 149/Gd-/sup 149 /Eu-/sup 149/Sm. EC measurements were made on the 101 keV electrons emitted in the decay of /sup 149/Eu. Two-dimensional channeling patterns of the conversion electrons were obtained along and axial directions by raster scans with a Si surface barrier detector. Comparison of the observed patterns with simulated spectra show that in diamond 45-50% of the RE...

  2. Formation of Broensted acids sites in the reaction of cyclohexanol on NaCeY zeolites

    International Nuclear Information System (INIS)

    Vogt, O.; Nattich, M.; Datka, J.; Gil, B.

    2002-01-01

    This study was undertaken to elucidate why the catalytic activity of NaCeY in cyclohexanol reactions carried out in a pulse reactor increases with the pulse number. We studied therefore the effect of cyclohexanol and also of ethanol and water on catalytic activity NaCeY (of exchange degrees 36 and 72%) in cyclohexanol reactions: isomerization and disproportionation. We also studied the reaction of cyclohexanol and water with NaCeY zeolite by IR spectroscopy. Our results evidenced that new Broensted acid sites were formed by the reaction of cyclohexanol and water. This was shown by IR spectroscopy: the increase of Si-O 1 H-Al band 3638 cm -1 and in increase of ammonium ions band (upon ammonia adsorption). The new sites were formed by hydrolysis of Ce 3+ ions with water introduced in a pulse, or produced by dehydration of cyclohexanol catalyzed by acid sites. Formation of new Broensted acid sites resulted in an increase of catalytic activity of NaCeY in cyclohexane reaction as observed in this study and also in cyclohexanol reactions. (author)

  3. Site-sensitive energy transfer modes in Ca3Al2O6: Ce(3+)/Tb(3+)/Mn(2+) phosphors.

    Science.gov (United States)

    Zhang, Jilin; He, Yani; Qiu, Zhongxian; Zhang, Weilu; Zhou, Wenli; Yu, Liping; Lian, Shixun

    2014-12-28

    Ce(3+)/Eu(2+), Tb(3+) and Mn(2+) co-doping in single-phase hosts is a common strategy to achieve white-light phosphors via energy transfer, which provides a high color rendering index (CRI) value and good color stability. However, not all hosts are suitable for white-light phosphors due to inefficient energy transfer. In this study, the site-sensitive energy transfer from different crystallographic sites of Ce(3+) to Tb(3+)/Mn(2+) in Ca3Al2O6 has been investigated in detail. The energy transfer from purplish-blue Ce(3+) to Tb(3+) is an electric dipole-dipole mode, and the calculated critical distance (Rc) suggests the existence of purplish-blue Ce(3+)-Tb(3+) clusters. No energy transfer is observed from purplish-blue Ce(3+) to Mn(2+). In co-doped phosphors based on greenish-blue Ce(3+), however, the radiative mode dominates the energy transfer from Ce(3+) to Tb(3+), and an electric dipole-quadrupole interaction is responsible for the energy transfer from Ce(3+) to Mn(2+). A detailed discussion on the site-sensitive energy transfer modes might provide a new aspect to discuss and understand the possibilities and mechanisms of energy transfer, according to certain crystallographic sites in a complex host with different cation sites, as well as provide a possible approach in searching for single-phase white-light-emitting phosphors.

  4. Mise en place du site internet du CFPC et de la communication qui entoure ce changement

    OpenAIRE

    Chollet, Sylvie; Mathelier, Guillaume

    2009-01-01

    Le présent travail porte sur la mise en place du site internet « école » du Centre de Formation Professionnelle de la Construction (CFPC). Cette école, appartenant au post-obligatoire, est née de la scission du Centre d’Enseignant Professionnel, Technique et Artisanal (CEPTA) suite à une nouvelle législature en août 2007. La communication interne et externe ainsi que les outils et les canaux doivent être modifiés, réadaptés, ou abandonnés. Ce document concerne spécifiquement la communication ...

  5. CO adsorption on ionic Pt, Pd and Cu sites in Ce MxO 2− (M= Pt 2 ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 123; Issue 4. CO adsorption on ionic Pt, Pd and Cu sites in Ce1−MxO2− (M=Pt2+, Pd2+, Cu2+). Gargi Dutta Asha Gupta Umesh V Waghmare M S Hegde. Volume 123 Issue 4 July 2011 pp 509-516 ...

  6. The 1997 Excavations at the Big Eddy Site (23CE426) in Southwest Missouri

    National Research Council Canada - National Science Library

    Lopinot, Neal

    1998-01-01

    .... The site also contains significant Early Archaic, Early/Middle Paleoindian, and possible pre-Clovis components, and has yielded the first reliable dates associated with a fluted point component...

  7. Fe-doped CeO2 solid solutions: Substituting-site doping versus interstitial-site doping, bulk doping versus surface doping

    Science.gov (United States)

    Bao, Huizhi; Qian, Kun; Fang, Jun; Huang, Weixin

    2017-08-01

    Doping CeO2 cubic fluorite with transitional metal ions can effectively improve its redox behavior, oxygen storage capacity and catalytic performance, but the relevant fundamental understanding of the promotion effect is still insufficient due to the difficulty on determining the distribution of dopant. We herein demonstrate an effective approach to determine this dopant distribution by combining X-ray absorption spectroscopy and selective chemisorption. Cubic CexFe1-xO2 fluorite solid solutions (x ≥ 0.70) were prepared by co-precipitation method. With the increasing of Fe molar ratio in CexFe1-xO2, Fe3+ initially substitutes Ce4+ and/or occupy intersitial sites with x ≥ 0.80, and then transfers to form sub-Fe2O3 structure in fluorite lattice as more Fe3+ are present; meanwhile, the Fe3+ doping initially occurs only in the bulk with x ≥ 0.96 and then extends to the surface with 0.87 ≤ x fluorite solid solutions at the molecular level that are of great importance for the fundamental understanding of their properties.

  8. Something black in the American Psyche: formal innovation and Freudian imagery in the comics of Winsor McCay and Robert Crumb.

    Science.gov (United States)

    Shannon, Edward A

    2010-01-01

    Winsor McCay’s Little Nemo in Slumberland anticipates Robert Crumb’s work. McCay’s innocent dreamscapes seem antithetical to the sexually explicit work of anti-capitalist Crumb, but Nemo looks forward to Crumb in subject and form. Nemo’s presentation of class, gender, and race, and its pre-Freudian sensibility are ironic counterpoints to Crumb’s political, Freudian comix.

  9. Dielectric properties estimation of the lunar regolith at CE-3 landing site using lunar penetrating radar data

    Science.gov (United States)

    Feng, Jianqing; Su, Yan; Ding, Chunyu; Xing, Shuguo; Dai, Shun; Zou, Yongliao

    2017-03-01

    The second channel (CH2) of the Lunar Penetrating Radar (LPR) carried on the Chang'e-3 (CE-3) Yutu Rover was used to determine the thickness and structure of the lunar regolith. Accurately revealing the true structure beneath the surface requires knowledge of the dielectric permittivity of the regolith, which allows one to properly apply migration to the radar image. In contrast to simple assumptions in previous studies, this paper takes account of heterogeneity of the regolith and derives regolith's permittivity distribution laterally and vertically by a method widely used in data processing of terrestrial Ground Penetrating Radar (GPR). We find that regolith permittivity at the landing site increases with depth more quickly than previously recognized. At a depth of ∼2.5-3 m, the dielectric constant reaches the value of solid basalt. The radar image was migrated on the basis of the permittivity profile. We do not find any continuous distinct layers or an apparent regolith/rock interface in the migrated radargram, which implies that this area is covered by relatively young, poorly layered deposits.

  10. A comparative study of surface energies and water adsorption on Ce-bastnäsite, La-bastnäsite, and calcite via density functional theory and water adsorption calorimetry.

    Science.gov (United States)

    Goverapet Srinivasan, Sriram; Shivaramaiah, Radha; Kent, Paul R C; Stack, Andrew G; Riman, Richard; Anderko, Andre; Navrotsky, Alexandra; Bryantsev, Vyacheslav S

    2017-03-15

    Bastnäsite, a fluoro-carbonate mineral, is the single largest mineral source of light rare earth elements (REE), La, Ce and Nd. Enhancing the efficiency of separation of the mineral from gangue through froth flotation is the first step towards meeting an ever increasing demand for REE. To design and evaluate collector molecules that selectively bind to bastnäsite, a fundamental understanding of the structure and surface properties of bastnäsite is essential. In our earlier work (J. Phys. Chem. C, 2016, 120, 16767), we carried out an extensive study of the structure, surface stability and water adsorption energies of La-bastnäsite. In this work, we make a comparative study of the surface properties of Ce-bastnäsite, La-bastnäsite, and calcite using a combination of density functional theory (DFT) and water adsorption calorimetry. Spin polarized DFT+U calculations show that the exchange interaction between the electrons in Ce 4f orbitals is negligible and that these orbitals do not participate in bonding with the oxygen atom of the adsorbed water molecule. In agreement with calorimetry, DFT calculations predict larger surface energies and stronger water adsorption energies on Ce-bastnäsite than on La-bastnäsite. The order of stabilities for stoichiometric surfaces is as follows: [101[combining macron]0] > [101[combining macron]1] > [101[combining macron]2] > [0001] > [112[combining macron]2] > [101[combining macron]4] and the most favorable adsorption sites for water molecules are the same as for La-bastnäsite. In agreement with water adsorption calorimetry, at low coverage water molecules are strongly stabilized via coordination to the surface Ce 3+ ions, whereas at higher coverage they are adsorbed less strongly via hydrogen bonding interaction with the surface anions. Due to similar water adsorption energies on bastnäsite [101[combining macron]1] and calcite [101[combining macron]4] surfaces, the design of collector molecules that selectively bind to

  11. Anomalous behavior of the magnetic hyperfine field at 140Ce impurities at La sites in LaMnSi2

    Science.gov (United States)

    Domienikan, C.; Bosch-Santos, B.; Cabrera-Pasca, G. A.; Saxena, R. N.; Carbonari, A. W.

    2018-05-01

    Magnetic hyperfine field has been measured in the orthorhombic intermetallic compound LaMnSi2 with perturbed angular correlation (PAC) spectroscopy using radioactive 140La(140Ce) nuclear probes. Magnetization measurements were also carried out in this compound with MPSM-SQUID magnetometer. Samples of LaMnSi2 compound were prepared by arc melting the component metals with high purity under argon atmosphere followed by annealing at 1000°C for 60 h under helium atmosphere and quenching in water. X-ray analysis confirmed the samples to be in a single phase with correct crystal structure expected for LaMnSi2 compound. The radioactive 140La (T1/2 = 40 h) nuclei were produced by direct irradiation of the sample with neutrons in the IEA-R1 nuclear research reactor at IPEN with a flux of ˜ 1013 n cm-2s-1 for about 3 - 4 min. The PAC measurements were carried out with a six BaF2 detector spectrometer at several temperatures between 10 K and 400 K. Temperature dependence of the hyperfine field, Bhf was found to be anomalous. A modified two-state model explained this anomalous behavior where the effective magnetic hyperfine field at 140Ce is believed to have two contributions, one from the unstable localized spins at Ce impurities and another from the magnetic Mn atoms of the host. The competition of these two contributions explains the anomalous behavior observed for the temperature dependence of the magnetic hyperfine field at 140Ce. The ferromagnetic transition temperature (TC) of LaMnSi2 was determined to be 400(1) K confirming the magnetic measurements.

  12. Electronic and thermoelectric properties of Ce{sub 3}Te{sub 4} and La{sub 3}Te{sub 4} computed with density functional theory with on-site Coulomb interaction correction

    Energy Technology Data Exchange (ETDEWEB)

    Vo, Trinh; Allmen, Paul von; Huang, Chen-Kuo; Ma, James; Bux, Sabah; Fleurial, Jean-Pierre [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States)

    2014-10-07

    The electronic properties and Seebeck coefficients of Ce{sub 3}Te{sub 4} and La{sub 3}Te{sub 4} are computed using Density Functional Theory with on-site Coulomb interaction correction. We found that the Seebeck coefficients of Ce{sub 3}Te{sub 4} and La{sub 3}Te{sub 4} are almost equal at temperatures larger than the Curie temperature of Ce{sub 3}Te{sub 4}, and in good agreement with the measurements reported by May et al. [Phys. Rev. B 86, 035135 (2012)]. At temperatures below the Curie temperature, the Seebeck coefficient of Ce{sub 3}Te{sub 4} increases due to the ferromagnetic ordering, which leads the f-electron of Ce to contribute to the Seebeck coefficient in the relevant range of electron concentration.

  13. Protein extraction into the bicontinuous microemulsion phase of a Water/SDS/pentanol/dodecane winsor-III system: Effect on nanostructure and protein conformation.

    Science.gov (United States)

    Hayes, Douglas G; Ye, Ran; Dunlap, Rachel N; Cuneo, Matthew J; Pingali, Sai Venkatesh; O'Neill, Hugh M; Urban, Volker S

    2017-12-01

    Bicontinuous microemulsions (BμEs), consisting of water and oil nanodomains separated by surfactant monolayers of near-zero curvature, are potentially valuable systems for purification and delivery of biomolecules, for hosting multiphasic biochemical reactions, and as templating media for preparing nanomaterials. We formed Winsor-III systems by mixing aqueous protein and sodium dodecyl sulfate (SDS) solutions with dodecane and 1-pentanol (cosurfactant) to efficiently extract proteins into the middle (BμE) phase. Bovine serum albumin (BSA) and cytochrome c partitioned to the BμE phase at 64% and 81% efficiency, respectively, producing highly concentrated protein solutions (32 and 44gL -1 , respectively), through release of water and oil from the BμEs. Circular dichroism spectroscopic analysis demonstrated that BSA underwent minor secondary structural changes upon incorporation into BμEs, while the secondary structure of cytochrome c and pepsin underwent major changes. Small-angle x-ray scattering (SAXS) results show that proteins promoted an increase of the interfacial fluidity and surface area per volume for the BμE surfactant monolayers, and that each protein uniquely altered self-assembly in the Winsor-III systems. Cytochrome c partitioned via electrostatic attractions between SDS and the protein's positively-charged groups, residing near the surfactant head groups of BμE monolayers, where it decreased surfactant packing efficiency. BSA partitioned through formation of SDS-BSA complexes via hydrophobic and electrostatic attractive interactions. As the BSA-SDS ratio increased, complexes' partitioning favored BμEs over the oil excess phase due to the increased hydrophilicity of the complexes. This study demonstrates the potential utility of BμEs to purify proteins and prepare nanostructured fluids possessing high protein concentration. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Radiometric survey in the sites of Regional office in Fortaleza, research gallery and camp in Itataia, CE (Brazil)

    International Nuclear Information System (INIS)

    1982-02-01

    The radiometric survey in Regional officer sites in Fortaleza, Brazil, research gallery and camp in Itataia is presented. The measurings to be done, the instrumentation used and results obtained are described as well as the conclusions and recommendations. (C.M.) [pt

  15. Effects of A-Site (NaCe) Substitution with Na-Deficiency on Structures and Properties of CaBi4Ti4O15-Based High-Curie-Temperature Ceramics

    Science.gov (United States)

    Yan, Haixue; Li, Chengen; Zhou, Jiaguang; Zhu, Weimin; He, Lianxin; Song, Yuxin; Yu, Youhua

    2001-11-01

    Three kinds of bismuth-layer-structured ferroelectric (BLSF) ceramics, CaBi4Ti4O15 (CBT), Ca0.8(CeNa)0.1Bi4Ti4O15 (CNBT), and Na-deficient Ca0.8(Ce0.1Na0.05\\Box0.05)Bi4Ti4O15 [CN\\BoxBT] (where \\Box represents vacancies) were prepared by a conventional ceramic technique. X-ray powder diffraction showed that their crystal structures are a single phase of BLSF with m=4. Sintering characteristics of the three ceramics were also discussed. Scanning electron microscope (SEM) micrographs of CN\\BoxBT showed that the grain is platelike. The A-site (NaCe) substitution can improve the piezoelectric constant d33 and high-temperature resistivity with decreasing Curie temperature. The modification by A-site (NaCe) substitution with Na-deficiency is more pronounced than CNBT, which not only leads to a very high piezoelectric constant d33 and high-temperature resistivity but also increases the Curie temperature. The reason for the high Tc (Tc=866°C) of CN\\BoxBT is considered to be internal stress. As a result, Na-deficient CN\\BoxBT ceramic is found to be an excellent high-temperature piezoelectric material.

  16. CO adsorption on ionic Pt, Pd and Cu sites in Ce1−xMxO2−δ (M=Pt ...

    Indian Academy of Sciences (India)

    tuting noble metal ions in CeO2 and TiO2 supports on exhaust catalysis.12 When oxide supports are doped with lower valent noble metal ions, it creates oxygen vacancies in the support oxide to balance the overall charge. The study on CO oxidation by AuxCe1−xO2 catalyst (using standard DFT and DFT+U methods),.

  17. Effect of protein incorporation on the nanostructure of the bicontinuous microemulsion phase of Winsor-III systems: a small-angle neutron scattering study.

    Science.gov (United States)

    Hayes, Douglas G; Gomez del Rio, Javier A; Ye, Ran; Urban, Volker S; Pingali, Sai Venkatesh; O'Neill, Hugh M

    2015-02-17

    Small-angle neutron scattering (SANS) analysis using the Teubner-Strey model has been employed to evaluate the effect of protein incorporation into the middle, bicontinuous microemulsion (BμE) phase of Winsor-III (WIII) systems formed by an aerosol-OT (AOT)/alkyl ethoxylate mixed surfactant system to understand better the extraction of proteins into and out of BμEs and to study the effect of proteins on a system that serves as a biomimetic analog of cell membranes. Under conditions of high salinity, the incorporation of positively charged proteins cytochrome c, lysozyme, and α-chymotrypsin, near their solubilization limit in the BμEs promoted the release of water and oil from the BμEs, a decrease in the quasi-periodic repeat distance (d), an increase in ordering (a decrease in the amphiphilicity factor, fa) for the surfactant monolayers, and a decrease in the surface area per surfactant headgroup, suggesting that the proteins affected the self-assembly of components in the BμE phase and produced Debye shielding of AOT's sulfonate headgroup. For WIII systems possessing lower salinity, cytochrome c reduced the efficiency of surfactant in the BμE phase, noted by increases in d and fa, suggesting that the enzyme and AOT underwent ion pairing. The results of this study demonstrate the importance of ionic strength to modulate protein-surfactant interactions, which in turn will control the release of proteins encapsulated in the BμEs, relevant to WIII-based protein extraction and controlled release from BμE delivery systems, and demonstrate the utility of BμEs as a model system to understand the effect of proteins on biomembranes.

  18. 2D NiFe/CeO2 Basic-Site-Enhanced Catalyst via in-Situ Topotactic Reduction for Selectively Catalyzing the H2 Generation from N2H4·H2O.

    Science.gov (United States)

    Wu, Dandan; Wen, Ming; Gu, Chen; Wu, Qingsheng

    2017-05-17

    An economical catalyst with excellent selectivity and high activity is eagerly desirable for H 2 generation from the decomposition of N 2 H 4 ·H 2 O. Here, a bifunctional two-dimensional NiFe/CeO 2 nanocatalyst with NiFe nanoparticles (∼5 nm) uniformly anchored on CeO 2 nanosheets supports has been successfully synthesized through a dynamic controlling coprecipitation process followed by in-situ topotactic reduction. Even without NaOH as catalyst promoter, as-designed Ni 0.6 Fe 0.4 /CeO 2 nanocatalyst can show high activity for selectively catalyzing H 2 generation (reaction rate (mol N2H4 mol -1 NiFe h -1 ): 5.73 h -1 ). As ceria is easily reducible from CeO 2 to CeO 2-x , the surface of CeO 2 could supply an extremely large amount of Ce 3+ , and the high-density electrons of Ce 3+ can work as Lewis base to facilitate the absorption of N 2 H 4 , which can weaken the N-H bond and promote NiFe active centers to break the N-H bond preferentially, resulting in the high catalytic selectivity (over 99%) and activity for the H 2 generation from N 2 H 4 ·H 2 O.

  19. Oxidation of Ce(III) in Foam Decontaminant by Ozone

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Chong Hun; Yoon, I. H.; Choi, W. K.; Moon, J. K.; Yang, H. B. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, J. S. [Gachon University, Seongnam (Korea, Republic of)

    2016-10-15

    A nanoparticle-based foam decontaminant is composed of a surfactant and nanoparticles for the generation and maintenance of foam, and a chemical decontamination agent made of Ce(IV) dissolved in nitric acid. Ce(IV) will be reduced to Ce(III) through the decontamination process. Oxidizing cerium(III) can be reused as a decontamination agent, Ce(IV). Oxidation treatment technology by ozone uses its strong oxidizing power. It can be regarded as an environmentally friendly process, because ozone cannot be stored and transported like other industrial gases (because it quickly decays into diatomic oxygen) and must therefore be produced on site, and used ozone can decompose immediately. The ozonation treatment of Ce(III) in foam decontaminant containing a surfactant is necessary for the effective regeneration of Ce(III). Thus, the present study was undertaken to determine the optimal conditions for ozonation treatment in the regeneration of Ce(III) into Ce(IV) in the nanoparticle-based foam decontaminant containing surfactant. This study was undertaken to determine the optimal conditions for ozonation treatment in the regeneration of Ce(III) to Ce(IV) in nanoparticle-based foam decontaminant containing a TBS surfactant. The oxidation conversion rate of Ce(III) was increased with an increase in the flow rate of the gas mixture and ozone injection amount. The oxidation time required for the 100% oxidation conversion of Ce(III) to Ce(IV) at a specific ozone injection amount can be predicted from these experimental data.

  20. CE-BEMS

    DEFF Research Database (Denmark)

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

    2016-01-01

    Energy consumption in smart buildings is monitored and controlled using Building Energy Management Systems (BEMS). A BEMS provides a set of methods to monitor and control a building's energy needs while maintaining a good quality of living in all of the building's spaces. Energy efficiency...... and costs savings in smart buildings significantly depend on the monitoring and control methods used in the installed BEMS. This paper proposes a Cloud-Enabled BEMS (CE-BEMS) for Smart Buildings. This system can utilize cloud computing to provide enhanced management mechanisms and features for energy...... savings in smart buildings. This system is connected to the cloud to have access to a number of advanced cloud-based services to enhance energy management in smart buildings. In this paper, we discuss the current limitations of BEMS, the conceptual design of the proposed system, and the advantages...

  1. CE and nanomaterials - Part II: Nanomaterials in CE.

    Science.gov (United States)

    Adam, Vojtech; Vaculovicova, Marketa

    2017-10-01

    The scope of this two-part review is to summarize publications dealing with CE and nanomaterials together. This topic can be viewed from two broad perspectives, and this article is trying to highlight these two approaches: (i) CE of nanomaterials, and (ii) nanomaterials in CE. The second part aims at summarization of publications dealing with application of nanomaterials for enhancement of CE performance either in terms of increasing the separation resolution or for improvement of the detection. To increase the resolution, nanomaterials are employed as either surface modification of the capillary wall forming open tubular column or as additives to the separation electrolyte resulting in a pseudostationary phase. Moreover, nanomaterials have proven to be very beneficial for increasing also the sensitivity of detection employed in CE or even they enable the detection (e.g., fluorescent tags of nonfluorescent molecules). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. CeO{sub 2} nanoparticles deposited on carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Zheng Guobin; Nomiyama, Ryoma; Sano, Hideaki; Uchiyama, Yasuo, E-mail: gbzheng@nagasaki-u.ac.jp [Department of Materials Science and Engineering, Nagasaki University, Bunkyo machi 1-14, Nagasaki, 852-8521 (Japan)

    2011-10-29

    Carbon nanotubes (CNTs) with average diameter of 14 nm were modified by oxidation in nitric acid and followed by treatment in sodium dodecyl sulfate (SDS). XPS analysis verified the introduction of carboxyl group and SDS molecules onto the CNT surface. The CeO{sub 2} coatings on CNTs were synthesized using two different processes; chemical precipitation method and solvothermal method. TEM observation showed that the coatings consisted of CeO{sub 2} nanoparticles with size of several nanometers. It is believed that in chemical precipitation method, the surface modification with carboxyl group and SDS provided nucleation sites of CeO{sub 2}, thus facilitating further growth and attachment of CeO{sub 2} nanoparticles. In solvothermal method, due to the interaction between graphene surface of CNTs and solvent pyridine, CeO{sub 2} particles could form on the pristine CNTs, and the surface modification decreased the nucleation sites of CeO{sub 2} and thus led to thinner or incomplete coating.

  3. Crystal structure and magnetic properties of the off-stoichiometric compounds CeNi sub 3 Cu sub 3 and CeNi sub 4 Cu sub 2

    CERN Document Server

    Moze, O; Brück, E; Buschow, K H J

    1998-01-01

    The crystallographic properties of the compounds CeNi sub 3 Cu sub 3 and CeNi sub 4 Cu sub 2 have been investigated by time-of-flight neutron diffraction. A Rietveld profile refinement of the data shows that these compounds crystallize in the hexagonal TbCu sub 7 -type structure and that Ni atoms have a greater preference as compared with Cu atoms for occupying the 2e dumb-bell site. A site preference of Cu atoms for the 2c sites is observed. Magnetic measurements made on these compounds show that the trivalent character of the Ce atoms increases with Cu concentration. (author)

  4. Contributing opportunistic resources to the grid with HTCondor-CE-Bosco

    Science.gov (United States)

    Weitzel, Derek; Bockelman, Brian

    2017-10-01

    The HTCondor-CE [1] is the primary Compute Element (CE) software for the Open Science Grid. While it offers many advantages for large sites, for smaller, WLCG Tier-3 sites or opportunistic clusters, it can be a difficult task to install, configure, and maintain the HTCondor-CE. Installing a CE typically involves understanding several pieces of software, installing hundreds of packages on a dedicated node, updating several configuration files, and implementing grid authentication mechanisms. On the other hand, accessing remote clusters from personal computers has been dramatically improved with Bosco: site admins only need to setup SSH public key authentication and appropriate accounts on a login host. In this paper, we take a new approach with the HTCondor-CE-Bosco, a CE which combines the flexibility and reliability of the HTCondor-CE with the easy-to-install Bosco. The administrators of the opportunistic resource are not required to install any software: only SSH access and a user account are required from the host site. The OSG can then run the grid-specific portions from a central location. This provides a new, more centralized, model for running grid services, which complements the traditional distributed model. We will show the architecture of a HTCondor-CE-Bosco enabled site, as well as feedback from multiple sites that have deployed it.

  5. Ce3+/Eu2+ doped SrSc2O4 phosphors: Synthesis, luminescence and energy transfer from Ce3+ to Eu2+

    Science.gov (United States)

    Zhao, Jitao; Sun, Xiaoyu; Wang, Zhenqing

    2018-01-01

    Ce3+/Eu2+ doped SrSc2O4 phosphors were synthesized by a solid state reaction. The phase and luminescent properties of the synthesized phosphors were investigated. In SrSc2O4 host, Ce3+/Eu2+ substitute Sr2+ sites and form the solid solution. Ce3+/Eu2+ singly doped SrSc2O4 phosphors respectively show emission band locating in green and deep red regions and the emission peaks shift to longer wavelength with the increasing concentration due to the enhancements of crystal field. In Ce3+/Eu2+ codoped SrSc2O4 phosphors, the intensities of Ce3+ and Eu2+ emissions change with the changing Eu2+ concentrations due to energy transfer from Ce3+ to Eu2+.

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

    KAUST Repository

    Naganuma, Tamaki

    2014-01-01

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

  7. Measurement of Ce(IV) Concentration in Foam Decontaminant containing Fluorosurfactant

    International Nuclear Information System (INIS)

    Jung, Chong Hun; Yang, H. B.; Yoon, I. H.; Choi, W. K.; Moon, J. K.; Lee, J. S.

    2016-01-01

    To improve the stability of the foam, surfactants and inorganic materials such as nanoparticles can be added. A nanoparticle-based foam decontaminant is composed of a surfactant and nanoparticles for the generation and maintenance of foam, and a chemical decontamination agent made of Ce(IV) dissolved in nitric acid. Ce(IV) will be reduced to Ce(III) through the decontamination process. Oxidizing the cerium (III) can be reused as a decontamination agent, Ce(IV). Oxidation treatment technology by ozone uses its strong oxidizing power. It can be regarded as an environmentally friendly process, because ozone cannot be stored and transported like other industrial gases (because it quickly decays into diatomic oxygen) and must therefore be produced on site, and used ozone can be decomposed immediately. A concentration analysis of Ce(IV) in foam decontaminant containing a surfactant is necessary prior to the derivation of optimal conditions for the regeneration of Ce(III) through ozonation treatment. A UV spectrometric method using the absorbance or potentiometric method with a potential difference in Ce(III)/Ce(IV), or a potentiometric titration method using Fe (II), can be used for a Ce(IV) concentration analysis. A UV spectrometric method has a problem receiving the influence of the surfactant, and a potentiometric method is difficult to use because of the problem of an insignificant change in the potential difference value of the Ce(III)/Ce(IV). Thus, the present study was undertaken to determine whether the potentiometric titration method can be used for an analysis of the Ce(IV) concentration in the nanoparticle-based foam decontaminant containing surfactant. It will be effectively used for the Ce(IV) concentration measurement, in relation to the subsequent research on the derivation of optimal conditions for the regeneration of Ce(III) through ozonation treatment.

  8. Measurement of Ce(IV) Concentration in Foam Decontaminant containing Fluorosurfactant

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Chong Hun; Yang, H. B.; Yoon, I. H.; Choi, W. K.; Moon, J. K. [KAERI, Daejeon (Korea, Republic of); Lee, J. S. [Gachon University, Seongnam (Korea, Republic of)

    2016-05-15

    To improve the stability of the foam, surfactants and inorganic materials such as nanoparticles can be added. A nanoparticle-based foam decontaminant is composed of a surfactant and nanoparticles for the generation and maintenance of foam, and a chemical decontamination agent made of Ce(IV) dissolved in nitric acid. Ce(IV) will be reduced to Ce(III) through the decontamination process. Oxidizing the cerium (III) can be reused as a decontamination agent, Ce(IV). Oxidation treatment technology by ozone uses its strong oxidizing power. It can be regarded as an environmentally friendly process, because ozone cannot be stored and transported like other industrial gases (because it quickly decays into diatomic oxygen) and must therefore be produced on site, and used ozone can be decomposed immediately. A concentration analysis of Ce(IV) in foam decontaminant containing a surfactant is necessary prior to the derivation of optimal conditions for the regeneration of Ce(III) through ozonation treatment. A UV spectrometric method using the absorbance or potentiometric method with a potential difference in Ce(III)/Ce(IV), or a potentiometric titration method using Fe (II), can be used for a Ce(IV) concentration analysis. A UV spectrometric method has a problem receiving the influence of the surfactant, and a potentiometric method is difficult to use because of the problem of an insignificant change in the potential difference value of the Ce(III)/Ce(IV). Thus, the present study was undertaken to determine whether the potentiometric titration method can be used for an analysis of the Ce(IV) concentration in the nanoparticle-based foam decontaminant containing surfactant. It will be effectively used for the Ce(IV) concentration measurement, in relation to the subsequent research on the derivation of optimal conditions for the regeneration of Ce(III) through ozonation treatment.

  9. Field test around Fukushima Daiichi nuclear power plant site using improved Ce:Gd3(Al,Ga)5O12 scintillator Compton camera mounted on an unmanned helicopter

    International Nuclear Information System (INIS)

    Shikaze, Yoshiaki; Nishizawa, Yukiyasu; Sanada, Yukihisa; Torii, Tatsuo; Jiang, Jianyong; Shimazoe, Kenji; Takahashi, Hiroyuki; Yoshino, Masao; Ito, Shigeki; Endo, Takanori; Tsutsumi, Kosuke; Kato, Sho; Sato, Hiroki; Usuki, Yoshiyuki; Kurosawa, Shunsuke; Kamada, Kei; Yoshikawa, Akira

    2016-01-01

    An improved light-weight Compton camera exhibiting low power consumption was developed to be mountable on an unmanned helicopter to detect cesium radiation hot spots and confirm the decontamination effect of cesium-affected areas. An increase in the Ce:Gd 3 (Al,Ga) 5 O 12 scintillator array from 4 × 4 to 8 × 8 and expansion of the interlayer distance enhanced the detection efficiency and angular resolution, respectively. Measurements were performed over the Ukedo riverbed in Namie, Fukushima Prefecture (Japan). The helicopter's flight path and speed were pre-programmed to lines interspaced by 5 and 10 m intervals and 1 m/s, respectively, facilitating measurements over areas of 65 × 60 m 2 and 65 × 180 m 2 at a height of 10 m for approximately 20 and 30 min, respectively. Results provided accurate ambient dose equivalent rate maps at a height of 1 m with an angular resolution corresponding to a position resolution of approximately 10 m from a height of 10 m. Hovering flights were executed over hot-spot areas for 10–20 min at a height of 5–20 m. Gamma-ray images of these hot spots were obtained using a reconstruction software. Comparison between position-shifted measurement results showed that the angular resolution coincided with that evaluated in the laboratory (approximately 10°). (author)

  10. Wind Energy in the Backyard of our House?! Environmental Perception of Social and Environmental Impacts in the Installation and Operation of a Plant in the Community of the Site in Cumbe Aracati-CE

    Directory of Open Access Journals (Sweden)

    Roseilda Nunes Moreira

    2013-06-01

    Full Text Available This theoretical and empirical study aimed to understand the perception that local people have about the environmental impacts caused by the installation and operation of an eolic enterprise in the surrounding community. The study of environmental perception is crucial for us to better understand the interrelationships between man and the environment, expectations, desires, satisfactions and dissatisfactions, judgments and behaviors. The spatial area adopted for the study is the community of Cumbe in Aracati / CE for its geomorphologic and climatologic presented sufficient conditions for the installation and use of wind energy in order to change the energy matrix of the municipality. This research is exploratory and descriptive design literature and case study, where to collect the data were collected through interviews with open questions to a group of residents near the eolic enterprise investigated and a prosecutor's Aracati. In the field research, we investigated the environmental impacts caused by the eolic plant, the level of understanding in the community about wind energy and the enterprise's contribution to community development, among other issues.

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

    Science.gov (United States)

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

    2015-11-01

    The La-Ce systematics has one of the longest half-lifes (T1/2 = 292.5 Ga) of radioactive decay systems used in isotope geochemistry. Variations of the 138Ce/142Ce ratio are expected to be small and the use of Ce as isotopic tracer requires a very precise measurement. Compared to Sm-Nd studies, the La-Ce decay system can provide additional information about the nature of sediments recycled in subduction zones, because unusually large Ce anomalies relative to the neighboring rare earth elements exist in marine sediments such as fish teeth or hydrothermal deposits. Here, we present a chemical purification technique for Ce, and mass spectrometric technique to perform accurate and reproducible analyses of Ce isotopes of natural samples. We report a large set of Ce isotope data including analysis of 2 Ce reference material solutions (AMES and JMC-304), 2 rock standards (BCR-2 and BHVO-2), 2 chondrites (the carbonaceous chondrite Allende and the enstatite chondrite Sahara 97072), 4 mid-ocean ridge basalts, 30 arc lavas from the Martinique Island and 5 oceanic sediments from DSDP-site 144 drilled on the Demerara rise. The long-term, external precision obtained on the AMES reference material is 80 ppm (2 s.d., 138Ce/142Ce = 0.0225732 ± 18, n = 89). However, we note an evolution of isotopic ratios measured in static mode over the duration of this study (33 months). When the reproducibility is calculated from the AMES reference material measured during the same analytical session, it averages 40 ppm. All the 138Ce/142Ce ratios have been normalized to the AMES value of 0.0225746 (measured in session 7, 2 s.d. = 14 ppm, n = 8), a session during which the chondritic value has been defined and the peak tailing was negligible. The 138Ce/142Ce ratio measured for the JMC-304 Ce reference reagent is 0.0225706 ± 9 (2 s.d. = 38 ppm, n = 10). The analytical precision on natural samples is improved by a factor of about 4 in relation to previous studies on island arcs (Tanaka et al

  12. Experimental and theoretical study about sulfur deactivation of Ni/ CeO{sub 2} and Rh/CeO{sub 2} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ocsachoque, Marco A., E-mail: ocmarco@quimica.unlp.edu.ar [Centro de Investigación y Desarrollo en Ciencias Aplicadas “Dr Jorge J. Ronco”, (CONICET, CCT La Plata), Departamento de Química, Facultad de Cs Exactas (UNLP), Calle 48 N° 257, 1900 La Plata (Argentina); Eugenio Russman, Juan I.; Irigoyen, Beatriz [Instituto de Tecnologías del Hidrógeno y Energías Sostenibles (ITHES), Departamento de Ingeniería Química, Facultad de Ingeniería (UBA), Buenos Aires (Argentina); Gazzoli, Delia [Dipartimento di Chimia, Universitá di Roma “La Sapienza”, Roma (Italy); González, María G. [Centro de Investigación y Desarrollo en Ciencias Aplicadas “Dr Jorge J. Ronco”, (CONICET, CCT La Plata), Departamento de Química, Facultad de Cs Exactas (UNLP), Calle 48 N° 257, 1900 La Plata (Argentina)

    2016-04-01

    Sulfur deactivation of Ni/CeO{sub 2} and Rh/CeO{sub 2} catalysts were examined through an experimental and theoretical study. These catalysts were characterized by N{sub 2} adsorption, X-ray diffraction, temperature programmed reaction, thermogravimetric analysis, Uv–visible spectroscopy and Raman spectroscopy, and tested under the methane dry reforming reaction in the presence of H{sub 2}S. On the other hand, different possible interactions of sulfur with Rh, Ni or surface sites of the CeO{sub 2} support were evaluated by performing energy calculations with the density functional theory (DFT). Overall, the results indicate that tolerance to sulfur of Rh/CeO{sub 2} catalyst is higher than that of Ni/CeO{sub 2} one. In this sense, TPR measurements show that reduction of CeO{sub 2} is promoted by the presence of Rh. This effect, probably caused by hydrogen spillover to CeO{sub 2} support during the reduction of RhO{sub x} species, could be linked to a high oxygen donation capacity of Rh/CeO{sub 2} catalysts. Accordingly, the O{sup 2−} species existing on Rh/CeO{sub 2} catalysts, revealed by Raman spectra of these samples, could favor sulfur oxidation and prevent Rh–S interactions. Likewise, the theoretical calculations show that desorption of S–O species from Rh/CeO{sub 2} system is more favorable than that from Ni/CeO{sub 2} one. Therefore, our experimental and theoretical study about sulfur deactivation of Ni and Rh supported on CeO{sub 2} allow us to postulate that Rh can help to desorb SO{sub x} species formed on the support, retarding sulfur poisoning of the Rh/CeO{sub 2} catalysts. - Highlights: • CeO{sub 2} support can act as a sacrifice trap decreasing sulfur poisoning. • Theoretical calculations indicate an important nickel affinity with sulfur. • Rh would favor desorption of S–O species formed on the support. • The O{sup 2−} species present on the Rh–CeO{sub 2} sample favor sulfur removal.

  13. Experimental and theoretical investigations for site preference and anisotropic size change of RE{sub 11}Ge{sub 4}In{sub 6−x}M{sub x} (RE = La, Ce; M = Li, Ge; x = 1, 1.96)

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Beom-Yong; Jeon, Jieun [Department of Chemistry, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of); Lee, Junseong [Department of Chemistry, Chonnam National University, Gwangju, Chonnam 500-757 (Korea, Republic of); Kim, Jongsik [Department of Chemistry, Dong-A University, Pusan 604-714 (Korea, Republic of); You, Tae-Soo [Department of Chemistry, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of)

    2015-01-25

    Graphical abstract: Reported is experimental and theoretical studies to understand the site-preference between anionic elements and the anisotropic size-change of the 3-D anionic frameworks of two polar intermetallic compounds in the RE{sub 11}Ge{sub 4}In{sub 6−x}M{sub x} (RE = La, Ce; M = Li, Ge; x = 1, 1.96) phase. Indium atoms with a smaller electronegativity prefer to occupy the “dumbbell-site” having the smaller QVAL value, and the anisotropic size-change of the anionic framework in La{sub 11}Ge{sub 4}In{sub 5.00(1)}Li{sub 1.00} is rationalized by using various COHP curves analyses. - Highlights: • Site-preference between anions was elucidated by the QVAL value of each site. • Ten models with different atomic orderings were examined by coloring problems. • COHP curves explained the anisotropic size-change of La{sub 11}Ge{sub 4}In{sub 5.00(1)}Li{sub 1.00}. - Abstract: Two polar intermetallic compounds in the RE{sub 11}Ge{sub 4}In{sub 6−x}M{sub x} (RE = La, Ce; M = Li, Ge; x = 1, 1.96) series have been synthesized by conventional high-temperature reactions and characterized by both single-crystal and powder X-ray diffractions. Both compounds crystallized in the tetragonal crystal system (space group I4/mmm, Z = 4, Pearson symbol tI84) with nine crystallographically independent atomic positions in the asymmetric unit and adopted the Sm{sub 11}Ge{sub 4}In{sub 6}-type structure, which can be considered as an ordered version of the Ho{sub 11}Ge{sub 10}-type. The lattice parameters are a = 11.8370(4) Å and c = 17.2308(7) Å for La{sub 11}Ge{sub 4}In{sub 5.00(1)}Li{sub 1.00}; a = 11.8892(4) Å, c = 16.5736(7) Å for Ce{sub 11}Ge{sub 5.96(3)}In{sub 4.04}. The overall crystal structures of two isotypic compounds can be described as a combination of the cage-shaped 3-dimensional (3-D) anionic framework and three different types of cationic polyhedra filling the inside of the 3-D frameworks. Anionic elements consisting of the frameworks indicate the

  14. The role of charge transfer in the oxidation state change of Ce atoms in the TM13-CeO2(111) systems (TM = Pd, Ag, Pt, Au): a DFT + U investigation.

    Science.gov (United States)

    Tereshchuk, Polina; Freire, Rafael L H; Ungureanu, Crina G; Seminovski, Yohanna; Kiejna, Adam; Da Silva, Juarez L F

    2015-05-28

    Despite extensive studies of transition metal (TM) clusters supported on ceria (CeO2), fundamental issues such as the role of the TM atoms in the change in the oxidation state of Ce atoms are still not well understood. In this work, we report a theoretical investigation based on static and ab initio molecular dynamics density functional theory calculations of the interaction of 13-atom TM clusters (TM = Pd, Ag, Pt, Au) with the unreduced CeO2(111) surface represented by a large surface unit cell and employing Hubbard corrections for the strong on-site Coulomb correlation in the Ce f-electrons. We found that the TM13 clusters form pyramidal-like structures on CeO2(111) in the lowest energy configurations with the following stacking sequence, TM/TM4/TM8/CeO2(111), while TM13 adopts two-dimensional structures at high energy structures. TM13 induces a change in the oxidation state of few Ce atoms (3 of 16) located in the topmost Ce layer from Ce(IV) (itinerant Ce f-states) to Ce(III) (localized Ce f-states). There is a charge flow from the TM atoms to the CeO2(111) surface, which can be explained by the electronegativity difference between the TM (Pd, Ag, Pt, Au) and O atoms, however, the charge is not uniformly distributed on the topmost O layer due to the pressure induced by the TM13 clusters on the underlying O ions, which yields a decrease in the ionic charge of the O ions located below the cluster and an increase in the remaining O ions. Due to the charge flow mainly from the TM8-layer to the topmost O-layer, the charge cannot flow from the Ce(IV) atoms to the O atoms with the same magnitude as in the clean CeO2(111) surface. Consequently, the effective cationic charge decreases mainly for the Ce atoms that have a bond with the O atoms not located below the cluster, and hence, those Ce atoms change their oxidation state from IV to III. This increases the size of the Ce(III) compared with the Ce(IV) cations, which builds-in a strain within the topmost Ce layer, and

  15. Promotional effect of tungsten-doped CeO{sub 2}/TiO{sub 2} for selective catalytic reduction of NOx with ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Dong Wook; Hong, Sung Chang, E-mail: schong@kgu.ac.kr

    2015-11-30

    Graphical abstract: - Highlights: • Catalysts were prepared by adding various metals to Ce/Ti to improve the activity. • The Ce{sup 3+} ratio of 10Ce/Me/Ti was proportional to the SCR activity of the catalyst. • When tungsten was added to 10Ce/Ti, an excellent SO{sub 2} resistance was displayed. - Abstract: We examined the effects that the physicochemical properties of Ce/Me/Ti catalysts had on the selective catalytic reduction (SCR) activity after various metals (W, Mo, and La) were added to non-vanadium-based catalysts in order to improve NH{sub 3}–SCR activity. We studied the properties of the catalysts through the use of physiochemical techniques, including Brunauer–Emmett–Teller (BET) surface area analysis, X-ray diffraction (XRD), H{sub 2} temperature-programmed reduction (H{sub 2}-TPR), X-ray photoelectron spectroscopy (XPS) transmission infrared spectroscopy (IR), and inductively coupled plasma optic emission spectroscopy (ICP). The catalytic activity tests of the Ce/Ti catalysts with various ceria loadings revealed that the Ce/Ti with 10 wt.% ceria (10Ce/Ti) exhibited excellent activity. Thus, various metals were added to the 10Ce/Ti. The tungsten-doped 10Ce/Ti catalyst exhibited the highest activity (10Ce/W/Ti: Ce was deposited after tungsten had been deposited on TiO{sub 2}). We investigated the correlation between the catalyst's Ce valence state and its activity. Different Ce{sup 3+} ratios were observed when various metals were added to Ce/Ti. The highest Ce{sup 3+} ratio was observed in 10Ce/W/Ti at 0.3027, and the catalyst efficiency had a positive correlation with higher Ce{sup 3+} ratios. The SCR activity was found to increase as the Ce{sup 3+} ratio increased when tungsten was added to 10Ce/W/Ti. Furthermore, in the case of 10Ce/W/Ti, it seemed that the Brønsted acid sites were more abundant relative to those on 10Ce/Ti. Upon the injection of SO{sub 2} in the SCR reaction, 10Ce/Ti was rapidly deactivated. However, the 10Ce

  16. Diffusion of hydrogen in Pd-(Ce, Y, B) alloys

    International Nuclear Information System (INIS)

    Sakamoto, Y.; Kaneko, H.; Tsukahara, T.; Hirata, S.

    1987-01-01

    The study has been carried out to determine the diffusivity of hydrogen in Pd alloys containing Ce, Y and B in atom fractions up to θ/sub μ/ = 0.1 by an electrochemical permeation method, and to examine the lattice dilation effect on the diffusivity in these alloys. Ce and Y have been chosen because the solid solubility of both in Pd is about 13 at% in spite of the very large atomic size-factor difference between Pd and the solutes, and thus the expansion of the Pd lattice by Ce and Y is much larger than by Ag. Furthermore, it is of interest that the partial enthalpy of the dissolved hydrogen at infinite dilution ΔH 0 /sub H/ for Ce and Y is much smaller than for Pd. On the other hand, B atom also expands the Pd lattice in a way similar to Y, and sometimes B atoms may dissolve in the octahedral interstitial sites in the same way as hydrogen atoms

  17. Preparation and characterization of Ce-doped ZnO nanofibers by an electrospinning method

    Directory of Open Access Journals (Sweden)

    Jong-Pil Kim

    2011-02-01

    Full Text Available ZnO and Ce-doped ZnO Nanofibers on (111 Pt/SiO2/Si substrates were produced using an electrospinning technique. The as-prepared composite fibres were subjected to high-temperature calcination to produce inorganic fibers. After calcining at a temperature of 500 °C, the average diameter of the ZnO and Ce-doped ZnO nanofibers were determined to be 170 nm and 225 nm, respectively. The average grain size of the ZnO and Ce-doped ZnO nanofibers were about 50 nm and 57 nm, respectively. The microstructure, chemical bonding state and photoluminescence of the produced ZnO and Ce-doped ZnO nanofibers were investigated. The Ce-doped ZnO nanofiber can be assigned to the presence of Ce ions on substitutional sites of Zn ions and the Ce3+ state from X-ray photoelectron spectra. Compared with PL spectra of ZnO nanofibers, the peak position of the UV emission of the Ce-doped ZnO nanofibers is sharply suppressed while the green emission band is highly enhanced.

  18. Local structure around Sn in CeCoIn5-xSnx

    International Nuclear Information System (INIS)

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

    2004-01-01

    The local structure around Sn dopants in CeCoIn 5-x Sn z has been probed by extended x-ray absorption fine structure (EXAFS) technique. The fit results for both x = 0.12 and x = 0.18 clearly indicate the dopant Sn atoms predominantly occupying the planar In(1) site. These results are consistent with the quasi-two-dimensional electronic properties of CeCoIn 5 and is discussed in relation to the observed bulk properties

  19. Lattice dynamics and elastic properties of the 4f electron system: CeN

    DEFF Research Database (Denmark)

    Kanchana, V.; Vaitheeswaran, G.; Zhang, Xinxin

    2011-01-01

    are hence allowed to hop from site to site, without an on-site Hubbard U, and contribute to the bonding, in a picture often referred to as itinerant. It is argued that this picture is appropriate for CeN at low temperatures, while the anomalous thermal expansion observed at elevated temperatures indicates...... entropy-driven localization of the Ce f electrons, similar to the behavior of elemental cerium. The elastic constants are predicted from the total energy variation of strained crystals and are found to be large, typical for nitrides. The phonon dispersions are calculated showing no soft modes...

  20. NMR study of CeTe at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hinderer, J. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland)]. E-mail: hinderer@phys.ethz.ch; Weyeneth, S.M. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Weller, M. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Gavilano, J.L. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Felder, E. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Hulliger, F. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Ott, H.R. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland)

    2006-05-01

    We present {sup 125}Te NMR measurements on CeTe powder at temperatures between 1 and 150K and in magnetic fields between 5 and 8T. CeTe is a rocksalt-type intermetallic compound. It orders antiferromagnetically at T{sub N}{approx}2.2K with a much reduced ordered moment [H.R. Ott, J.K. Kjems, F. Hulliger, Phys. Rev. Lett. 42 20 (1979) 1378]. From our low-temperature NMR spectra we infer the presence of at least three inequivalent Te sites at low temperatures. Considering the crystal structure this result is completely unexpected. The linewidths and the Knight shifts of the individual lines are significantly different and increase substantially with decreasing temperature. They follow the temperature dependence of the magnetic susceptibility above 20K. Above T{sub N}, hyperfine fields of 1.6, 0.8 and 0.0T at the three Te sites per Bohr magneton of Ce moment are deduced from Knight shift vs. magnetic susceptibility data. These values are typical for transferred hyperfine fields via conduction electrons.

  1. Muon spin relaxation study on itinerant ferromagnet CeCrGe₃ and the effect of Ti substitution on magnetism of CeCrGe₃.

    Science.gov (United States)

    Das, Debarchan; Bhattacharyya, A; Anand, V K; Hillier, A D; Taylor, J W; Gruner, T; Geibel, C; Adroja, D T; Hossain, Z

    2015-01-14

    A Muon spin relaxation (µSR) study has been performed on the Kondo lattice heavy fermion itinerant ferromagnet CeCrGe3. Recent investigations of bulk properties have revealed a long-range ordering of Cr moments at Tc = 70 K in this compound. Our µSR investigation between 1.2 K and 125 K confirm the bulk magnetic order which is marked by a loss in initial asymmetry below 70 K accompanied with a sharp increase in the muon depolarization rate. Field dependent µSR spectra show that the internal field at the muon site is higher than 0.25 T apparently due to the ferromagnetic nature of ordering. The effect of Ti substitution on the magnetism in CeCrGe3 is presented. A systematic study has been made on polycrystalline CeCr(1-x)Ti(x)Ge3 (0 ⩽ x ⩽ 1) using magnetic susceptibility χ(T), isothermal magnetization M(H), specific heat C(T) and electrical resistivity ρ(T) measurements which clearly reveal that the substitution of Ti for Cr in CeCrGe3 strongly influences the exchange interaction and ferromagnetic ordering of Cr moments. The Cr moment ordering temperature is suppressed gradually with increasing Ti concentration up to x = 0.50 showing Tc = 7 K beyond which Ce moment ordering starts to dominate and a crossover between Cr and Ce moment ordering is observed with a Ce moment ordering Tc = 14 K for x = 1.0. The Kondo lattice behavior is evident from temperature dependence of ρ(T) in all CeCr(1-x)Ti(x)Ge3 samples.

  2. Satellite line mapping in Eu3+–Ce3+ and Pr3+–Ce3+ codoped Y2SiO5

    International Nuclear Information System (INIS)

    Serrano, D.; Karlsson, J.; Zheng, L.; Dong, Y.; Ferrier, A.; Goldner, P.; Walther, A.; Rippe, L.; Kröll, S.

    2016-01-01

    In this work we perform a high-resolution spectroscopic investigation of Eu 3+ –Ce 3+ and Pr 3+ –Ce 3+ codoped Y 2 SiO 5 crystals. Satellite line spectra were recorded at low temperatures around the Eu 3+ : 7 F 0 → 5 D 0 and the Pr 3+ : 3 H 4 → 1 D 2 transitions. It is observed that the incorporation of Ce 3+ as a codopant notably changes the Eu 3+ and Pr 3+ satellite line patterns. Satellite lines measured in singly doped Eu 3+ :Y 2 SiO 5 were found at the same spectral positions in Eu 3+ –Ce 3+ codoped crystals. These coincident lines were concluded to be due to pairs of Eu 3+ ions. Extra satellite lines appeared in the codoped crystals, which were assigned to Ce 3+ related structures such as Ce 3+ –Eu 3+ pairs. The analysis of the Pr 3+ satellite line spectra presents further challenges. Satellite lines associated to Pr 3+ pairs show weaker intensity, presumably due to the efficient quenching of the Pr 3+1 D 2 emission through cross-relaxation paths ( 1 D 2 → 1 G 4 ; 3 H 4 → 3 F 4 ). The investigation of the Eu 3+ and Pr 3+ satellite line patterns in Y 2 SiO 5 is particularly interesting for their exploitation in rare-earth based quantum computation schemes. - Highlights: • We recorded Eu and Pr satellite lines in Y 2 SiO 5 with and without Ce as a codopant. • The presence of Ce leads to the appearance of extra satellite lines in the spectra. • The satellite lines are associated to minor crystal sites such as ion pairs. • Less than 100 ion pairs were detected per satellite line. • The exploitation of the satellite line structure is proposed for quantum computing.

  3. Chemically abrupt interface between Ce oxide and Fe films

    International Nuclear Information System (INIS)

    Lee, H.G.; Lee, D.; Kim, S.; Kim, S.G.; Hwang, Chanyong

    2005-01-01

    A chemically abrupt Fe/Ce oxide interface can be formed by initial oxidation of an Fe film followed by deposition of Ce metal. Once a Ce oxide layer is formed on top of Fe, it acts a passivation barrier for oxygen diffusion. Further deposition of Ce metal followed by its oxidation preserve the abrupt interface between Ce oxide and Fe films. The Fe and Ce oxidation states have been monitored at each stage using X-ray photoelectron spectroscopy

  4. Pyrazolates advance cerium chemistry: a CeIII/CeIV redox equilibrium with benzoquinone.

    Science.gov (United States)

    Werner, Daniel; Deacon, Glen B; Junk, Peter C; Anwander, Reiner

    2017-05-16

    Two stable cerium(iv) 3,5-dialkylpyrazolate complexes are presented, namely dimeric [Ce(Me 2 pz) 4 ] 2 (Me 2 pz = 3,5-dimethylpyrazolate) and monomeric Ce(tBu 2 pz) 4 (tBu 2 pz = 3,5-di-tert-butylpyrazolate) along with their trivalent counterparts [Ce(Me 2 pz) 3 ] and [Ce(tBu 2 pz) 3 ] 2 . All complexes were obtained from protonolysis reactions employing the silylamide precursors Ce[N(SiHMe 2 ) 2 ] 4 and Ce[N(SiMe 3 ) 2 ] 3 . Treatment of homoleptic Ce IV and Ce III Me 2 pz complexes with 1,4-hydroquinone (H 2 hq) or 1,4-benzoquinone (bq), respectively, ultimately gave the same trimetallic Ce III species via a cerium redox equilibrium. The Ce III complex Ce 3 (Me 2 pz) 5 (pchd) 2 (L) (pchd = 1,4-bis(3,5-dimethylpyrazol-1-yl)cyclohex-2,5-diene-1,4-diolato; L = Me 2 pzH or (thf) 2 ) results from a di-1,4-pyrazolyl attack on pre-coordinated bq. The reduction of bq by [Ce(Me 2 pz) 3 (thf)] 2 , and re-oxidation by the resulting Ce IV species was supported by UV-vis spectroscopic investigations. Comparisons with the redox-innocent complexes [Ln(Me 2 pz) 3 (thf)] 2 (Ln = La and Pr) revealed far less selective reactions with bq, giving hexametallic and octametallic rare-earth metal side products containing 2-Me 2 pz substituted hq ligands.

  5. (EC+β+) decay of 130Ce

    International Nuclear Information System (INIS)

    Xu Shuwei; Zhang Tianmei; Xie Yuanxiang; Ma Ruichang; Ge Yuanxiu; Guo Yingxiang; Wang Chunfang; Li Zhankui; Guo Bing; Xing Jianping; Guo Tianrui; Zhu Shaofei; Xu Wang; Du Jinzhou

    1996-01-01

    The nuclide 130 Ce was produced by a ( 16 O, 4n) reaction on an enriched 118 Sn target. Reaction products were transported to a shielded location by using a helium-jet tape transport system. A 22.9 min activity in chemically separated cerium sample was identified as 130 Ce. The (EC+β + ) decay scheme of 130 Ce was proposed for the first time. This scheme includes 108 γ-lines, 107 γ-lines among them being new. More than 13 1 + low-lying states of 130 La are populated in the decay of 130 Ce. Two new isomers with half-life of 77±10 ns and 17±5 ns were observed by means of delayed γ-γ coincidence measurements. (orig.). With 5 figs., 3 tabs

  6. Solute diffusion in Pu and Ce

    International Nuclear Information System (INIS)

    Marbach, Gabriel; Charissoux, Christian; Janot, Christian

    1976-01-01

    The diffusion rate of Co, Au and Ag in the bcc phases of Pu and Ce is studied. In the bcc delta phase of Pu, Au and Ag have the same diffusion rate that the matrix and Co is a very rapid solute. In the bcc phase of Ce, the diffusion coefficients of the three metals are remarkably high. This phenomenon is also observed in certain metallic matrices (Pb, Sn, [fr

  7. Metamagnetism in Ce(Ga,Al)2

    Indian Academy of Sciences (India)

    Abstract. Effect of Al substitution on the magnetic properties of Ce(Ga1−x Alx )2 (x = 0, 0.1 and. 0.5) system has been studied. The magnetic state of CeGa2 is found to be FM with a TC of 8 K, whereas the compounds with x =0.1 and 0.5 are AFM and possess TN of about 9 K. These two com- pounds undergo metamagnetic ...

  8. Ce O2-Zr O2 tetragonal ceramics (Ce-TZP): mechanical properties

    International Nuclear Information System (INIS)

    Nono, Maria do Carmo de Andrade

    1994-01-01

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

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

    International Nuclear Information System (INIS)

    Lu, Chi-Yuan; Chang, Wen-Chi; Wey, Ming-Yen

    2013-01-01

    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 2 supports such as commercial CeO 2 and self-prepared CeO 2 for the preparation of copper catalysts. The CuO/CeO 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 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 2 catalysts with commercial CeO 2 , those with CeO 2 that was self-prepared by pyrolysis had a large pore volume and good crystal structure of CeO 2 and showed good performance. The catalytic activity for CO removal was in the following order: CuO/CeO 2 -P (pyrolysis) > CuO/CeO 2 -C (commercial) > CuO/CeO 2 -D (deposition precipitation). CuO/CeO 2 -P catalysts showed good activity even at low temperature. The CuO/CeO 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 −1 , SV was 3.7 × 10 4 h −1 , and reaction temperature was 150 °C. - Highlights: • CuO/CeO 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. • Catalytic activity of CuO/CeO 2 catalysts were evaluated by the removal of CO

  10. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Hyperfine field and magnetic structure in the B phase of CeCoIn5

    Energy Technology Data Exchange (ETDEWEB)

    Graf, Matthias J [Los Alamos National Laboratory; Curro, Nicholas J [UNIV OF CAL; Young, Ben - Li [NATIONAL CHIAO UNIV; Urbano, Ricardo R [FL STATE UNIV

    2009-01-01

    We re-analyze Nuclear Magnetic Resonance (NMR) spectra observed at low temperatures and high magnetic fields in the field-induced B-phase of CeCoIn{sub 5}. The NMR spectra are consistent with incommensurate antiferromagnetic order of the Ce magnetic moments. However, we find that the spectra of the In(2) sites depend critically on the direction of the ordered moments, the ordering wavevector and the symmetry of the hyperfine coupling to the Ce spins. Assuming isotropic hyperfine coupling, the NMR spectra observed for H {parallel} [100] are consistent with magnetic order with wavevector Q = {pi}(1+{delta}/a, 1/a, 1/c) and Ce moments ordered antiferromagnetically along the [100] direction in real space. If the hyperfine coupling has dipolar symmetry, then the NMR spectra require Ce moments along the [001] direction. The dipolar scenario is also consistent with recent neutron scattering measurements that find an ordered moment of 0.15{micro}{sub B} along [001] and Q{sub n} = {pi}(1+{delta}/a, 1+{delta}c, 1/c) with incommensuration {delta} = 0.12 for field H {parallel} [1{bar 1}0]. Using these parameters, we find that the hyperfine field is consistent with both experiments. We speculate that the B phase of CeCoIn{sub 5} represents an intrinsic phase of modulated superconductivity and antiferromagnetism that can only emerge in a highly clean system.

  12. Solid state speciation of uranium and its local structure in Sr2CeO4 using photoluminescence spectroscopy

    Science.gov (United States)

    Sahu, M.; Gupta, Santosh K.; Jain, D.; Saxena, M. K.; Kadam, R. M.

    2018-04-01

    An effort was taken to carry our speciation study of uranium ion in technologically important cerate host Sr2CeO4 using time resolved photoluminescence spectroscopy. Such studies are not relevant only to nuclear industry but can give rich insight into fundamentals of 5f electron chemistry in solid state systems. In this work both undoped and varied amount of uranium doped Sr2CeO4 compound is synthesized using complex polymerization method and is characterized systematically using X-ray diffraction (XRD), Raman spectroscopy, photoluminescence spectroscopy and scanning electron microscopy (SEM). Both XRD and Raman spectroscopy confirmed the formation of pure Sr2CeO4 which has tendency to decompose peritectically to SrCeO3 and SrO at higher temperature. Uranium doping is confirmed by XRD. Uranium exhibits a rich chemistry owing to its variable oxidation state from +3 to +6. Each of them exhibits distinct luminescence properties either due to f-f transitions or ligand to metal charge transfer (LMCT). We have taken Sr2CeO4 as a model host lattice to understand the photophysical characteristics of uranium ion in it. Emission spectroscopy revealed the stabilization of uranium as U (VI) in the form of UO66- (octahedral uranate) in Sr2CeO4. Emission kinetics study reflects that uranate ions are not homogeneously distributed in Sr2CeO4 and it has two different environments due to its stabilization at both Sr2+ as well as Ce4+ site. The lifetime population analysis interestingly pinpointed that majority of uranate ion resided at Ce4+ site. The critical energy-transfer distance between the uranate ion was determined based on which the concentration quenching mechanism was attributed to electric multipolar interaction. These studies are very important in designing Sr2CeO4 based optoelectronic material as well exploring it for actinides studies.

  13. Platinum uptake and Ba2CePtO6 formation during in situ BaCe(1-x)M(x)O(3-δ) (M = La, In) formation.

    Science.gov (United States)

    Lussier, Joey A; Shafi, Shahid P; Donaberger, Ronald L; Bieringer, Mario

    2014-08-18

    We report the formation, structures, temperature-dependent phase transitions, and high-temperature reactivity of the potential proton and oxide ion conductors BaCe(1-x)M(x)O3 (M(3+) = In(3+), La(3+)). The present in situ diffraction studies show oxidative platinum uptake at temperatures as low as 950 °C into BaCeO3, forming the cubic Ba2CePtO6 double perovskite. The transient B-site double perovskite expels platinum at around 1200-1250 °C. Platinum oxidation via BaCeO3 is investigated by in situ powder X-ray and neutron diffraction experiments in various atmospheres. Doped BaCe(1-x)M(x)O3 phases show the formation of Ba2CePtO6 without incorporating the M(3+) dopant. Oxidative platinum uptake is also observed during the synthesis of BaCeO3 on platinum metal. We report the reaction pathway for the low-temperature oxidative formation of Ba2CePtO6 and the subsequent liberation of platinum for the barium cerate system. The findings are supported by ambient-temperature X-ray diffraction, in situ powder X-ray, and powder neutron diffraction as well as XPS.

  14. Role of Microstructure and Surface Defects on the Dissolution Kinetics of CeO2, a UO2 Fuel Analogue.

    Science.gov (United States)

    Corkhill, Claire L; Bailey, Daniel J; Tocino, Florent Y; Stennett, Martin C; Miller, James A; Provis, John L; Travis, Karl P; Hyatt, Neil C

    2016-04-27

    The release of radionuclides from spent fuel in a geological disposal facility is controlled by the surface mediated dissolution of UO2 in groundwater. In this study we investigate the influence of reactive surface sites on the dissolution of a synthesized CeO2 analogue for UO2 fuel. Dissolution was performed on the following: CeO2 annealed at high temperature, which eliminated intrinsic surface defects (point defects and dislocations); CeO2-x annealed in inert and reducing atmospheres to induce oxygen vacancy defects and on crushed CeO2 particles of different size fractions. BET surface area measurements were used as an indicator of reactive surface site concentration. Cerium stoichiometry, determined using X-ray Photoelectron Spectroscopy (XPS) and supported by X-ray Diffraction (XRD) analysis, was used to determine oxygen vacancy concentration. Upon dissolution in nitric acid medium at 90 °C, a quantifiable relationship was established between the concentration of high energy surface sites and CeO2 dissolution rate; the greater the proportion of intrinsic defects and oxygen vacancies, the higher the dissolution rate. Dissolution of oxygen vacancy-containing CeO2-x gave rise to rates that were an order of magnitude greater than for CeO2 with fewer oxygen vacancies. While enhanced solubility of Ce(3+) influenced the dissolution, it was shown that replacement of vacancy sites by oxygen significantly affected the dissolution mechanism due to changes in the lattice volume and strain upon dissolution and concurrent grain boundary decohesion. These results highlight the significant influence of defect sites and grain boundaries on the dissolution kinetics of UO2 fuel analogues and reduce uncertainty in the long term performance of spent fuel in geological disposal.

  15. Fabrication of Nano-CeO2 and Application of Nano-CeO2 in Fe Matrix Composites

    International Nuclear Information System (INIS)

    Tiebao, W.; Chunxiang, C.; Xiaodong, W.; Guobin, L.

    2010-01-01

    It is expatiated that nano-CeO2 is fabricated by the direct sedimentation method. The components and particles diameter of nano-CeO2 powders are analyzed by XRD and SEM . The thermodynamic analysis and acting mechanism of nano-CeO2 with Al in Fe matrix composites are researched, which shows that the reaction is generated between CeO2 and Al in the composite, that is, 3CeO2+4Al - 2Al2O3+3[Ce], which obtains Al2O3 and active [Ce] during the sintering process. The active [Ce] can improve the performance of CeO2/Fe matrix composites. The suitable amount of CeO2 is about 0.05% in CeO2/Fe matrix composites. SEM fracture analysis shows that the toughness sockets in nano-CeO2/Fe matrix composites are more than those in no-added nano-CeO2 composites, which can explain that adding nano-CeO2 into Fe matrix composite, the toughness of the composite is improved significantly. Applied nano-CeO2 to Fe matrix diamond saw blades shows that Fe matrix diamond saw blade is sharper and of longer cutting life than that with no-added nano-CeO2.

  16. Emission properties of Ce-doped alkaline earth borate glasses for scintillator applications

    Science.gov (United States)

    Torimoto, Aya; Masai, Hirokazu; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

    2017-11-01

    We investigate the photoluminescence (PL) and X-ray-induced luminescence properties of 0.1 mol% Ce-doped MO-B2O3 (M = Ca, Sr, and Ba) glasses. We also determine the Ce3+/(Ce3++Ce4+) ratio by X-ray absorption near-edge structure analyses. The emission intensities of PL, X-ray scintillation, and thermally stimulated luminescence (TSL) depend on the host glass composition. The order of the PL intensity from highest to lowest is as follows: Ca-substituted glass, Ba-substituted glass, and Sr-substituted glass. Our results suggest that the optical absorption edge and quantum yield (QY) are influenced by the local coordination state of Ce3+, which, in turn, is likely to be affected by the optical basicity. The order of the X-ray scintillation intensity from highest to lowest is reverse of that of the PL intensity. This is probably because the interaction probability of X-rays with matter depends on the effective atomic number of the material and the effective atomic number has a stronger influence on the scintillation intensity than does the QY. Though the TSL glow curves reveal that the density and energy depth of the trap sites depend on the substituted alkaline earth oxides, we are unable to correlate the electron spin resonance (ESR) spectra with the TSL results. Therefore, it is considered that the ESR active sites are not responsible for the TSL in these systems.

  17. Optical, luminescence and scintillation characteristics of non-stoichiometric LuAG:Ce ceramics

    Czech Academy of Sciences Publication Activity Database

    Liu, S.; Feng, X.; Mareš, Jiří A.; Babin, Vladimir; Nikl, Martin; Beitlerová, Alena; Shi, Y.; Zeng, Y.; Pan, Y.; D'Ambrosio, C.; Huang, Y.

    2016-01-01

    Roč. 169, Jan (2016), s. 72-77 ISSN 0022-2313 R&D Projects: GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : non-stoichimetric LuAG:Ce ceramics * radioluminescence * scintillation response * anti -site defects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.686, year: 2016

  18. Download - tRNADB-CE | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available switchLanguage; BLAST Search Image Search Home About Archive Update History Data List Contact us tRNA...rch and download 1 README README_e.html - 2 tRNA sequence data, annotation data a...f This Database Site Policy | Contact Us Download - tRNADB-CE | LSDB Archive ...

  19. Physico-chemical properties of (U,Ce)O2

    International Nuclear Information System (INIS)

    Yamada, K.; Yamanaka, S.; Katsura, M.

    1998-01-01

    The high-temperature X-ray diffraction analysis of (U,Ce)O 2 with CeO 2 contents ranging from 0 to 20 mol.% CeO 2 was performed to obtain the variation of the linear thermal expansion coefficient with the CeO 2 content. Ultrasonic pulse-echo measurements were also carried out from room temperature to 673 K to estimate the change in the mechanical properties of (U,Ce)O 2 with the CeO 2 content. The variation in the linear thermal expansion coefficient at the low CeO 2 content region is more steep than that expected from the linear thermal expansion coefficient of UO 2 and CeO 2 . The Young's and shear moduli of all (U,Ce)O 2 were found to decrease with rising temperature. This was due to the increase of the bond length accompanied by the thermal expansion. Although the lattice parameter decreased with CeO 2 content, the moduli of (U,Ce)O 2 were found to decrease with increasing CeO 2 content at room temperature. These results show that in the range from 0 to 20 mol.% of CeO 2 , as CeO 2 content increases, the bottom of the potential energy in (U,Ce)O 2 is shallower and broader. (orig.)

  20. Fabrication of CeO2–MOx (M = Cu, Co, Ni composite yolk–shell nanospheres with enhanced catalytic properties for CO oxidation

    Directory of Open Access Journals (Sweden)

    Ling Liu

    2017-11-01

    Full Text Available CeO2–MOx (M = Cu, Co, Ni composite yolk–shell nanospheres with uniform size were fabricated by a general wet-chemical approach. It involved a non-equilibrium heat-treatment of Ce coordination polymer colloidal spheres (Ce-CPCSs with a proper heating rate to produce CeO2 yolk–shell nanospheres, followed by a solvothermal treatment of as-synthesized CeO2 with M(CH3COO2 in ethanol solution. During the solvothermal process, highly dispersed MOx species were decorated on the surface of CeO2 yolk–shell nanospheres to form CeO2–MOx composites. As a CO oxidation catalyst, the CeO2–MOx composite yolk–shell nanospheres showed strikingly higher catalytic activity than naked CeO2 due to the strong synergistic interaction at the interface sites between MOx and CeO2. Cycling tests demonstrate the good cycle stability of these yolk–shell nanospheres. The initial concentration of M(CH3COO2·xH2O in the synthesis process played a significant role in catalytic performance for CO oxidation. Impressively, complete CO conversion as reached at a relatively low temperature of 145 °C over the CeO2–CuOx-2 sample. Furthermore, the CeO2–CuOx catalyst is more active than the CeO2–CoOx and CeO2–NiO catalysts, indicating that the catalytic activity is correlates with the metal oxide. Additionally, this versatile synthesis approach can be expected to create other ceria-based composite oxide systems with various structures for a broad range of technical applications.

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

    Directory of Open Access Journals (Sweden)

    J. G. He

    2016-10-01

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

  2. Ultraviolet-vacuum ultraviolet photoluminescence and x ray radioluminescence of Ce3+-doped Ba3MgSi2O8

    NARCIS (Netherlands)

    Ding, X.; Liang, H.; Hou, D.; Su, Q.; Dorenbos, P.; Sun, S.; Tao, Y.

    2011-01-01

    Ce3+-doped Ba3MgSi2O8 phosphors were prepared by a solid-state reaction route. The photoluminescence properties in the vacuum ultraviolet-vis spectral range and the x ray excited radioluminescence were investigated. Ce3+ ions were found to enter three different sites in the host lattice. Five

  3. Renormalized electronic structures of CeSi{sub 2}, CeRu{sub 2} and CeAl{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Costa-Quintana, J. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme; Gonzalez-Leon, E. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme; Lopez-Aguilar, F. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme; Puig-Puig, L. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme; Sanchez-Lopez, M.M. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme

    1995-02-01

    The renormalized density of states of some Ce compounds is analyzed by considering self-energy effects. We study the influence of the hybridization introduced by the self-energy and how it can affect the shape of the characteristic lower, upper and middle-energy resonance. ((orig.)).

  4. Crystal structure, energy transfer and tunable luminescence properties of Ca8ZnCe(PO4)7:Eu2+,Mn2+ phosphor

    Science.gov (United States)

    Ding, Chong; Tang, Wanjun

    2018-02-01

    Single-phased Ca8ZnCe(PO4)7:Eu2+,Mn2+ phosphors with whitlockite-type structure have been prepared via the combustion-assisted synthesis technique. The XRD pattern show that the as-obtained phosphors crystallize in a trigonal phase with space group of R-3c (161). Ca8ZnCe(PO4)7 host is full of sensitizers (Ce3+) and the Ce3+ emission at different lattice sites has been discussed. The efficient energy transfers from Ce3+ ions to Eu2+/Mn2+ ions and from Eu2+ to Mn2+ have been validated. Under UV excitation, the emitting color of Ca8ZnCe(PO4)7:Eu2+/Mn2+ samples can be modulated from violet blue to green and from violet blue to red-orange by the energy transfers of Ce3+→Eu2+ and Ce3+→Mn2+, respectively. Additionally, white emission has been obtained through adjusting the relative concentrations of Eu2+ and Mn2+ ions in the Ca8ZnCe(PO4)7 host under UV excitation. These results indicate that as-prepared Ca8ZnCe(PO4)7:Eu2+,Mn2+ may be a potential candidate as color-tunable white light-emitting phosphors.

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

    Science.gov (United States)

    Zhang, Xinguo; Pan, Jialiang; Mo, Fuwang

    2017-07-01

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

  6. Effect of lithium ion addition on afterglow time of green-emitting Ce3+ and Pr3+ codoped CaS phosphor by black light irradiation

    International Nuclear Information System (INIS)

    Kojima, Yoshiyuki; Aoyagi, Kenichi; Yasue, Tamotsu

    2005-01-01

    This paper reports the effect of lithium ion addition on the afterglow time of green-emitting Ce 3+ and Pr 3+ codoped CaS phosphor by black light irradiation. CaS:Ce 3+ , Pr 3+ , irradiated with black light, emitted in the green region and showed afterglow. The afterglow time of CaS:Ce 3+ , Pr 3+ was relatively short (about 10 min). When a Li + invades the free space in a CaS crystal lattice, new cation vacancy is formed for the charge compensation in the Ca 2+ site. The afterglow intensity of CaS:Ce 3+ , Pr 3+ , with Li + incorporated in the host, increased to three times that of the original sample (CaS:Ce 3+ , Pr 3+ ). The afterglow time of CaS:Ce 3+ , Pr 3+ , with Li + incorporated was extended to 40 min

  7. Ce-valence state and hydrogen-induced volume effects in Ce-based intermetallic compounds and their hydrides

    International Nuclear Information System (INIS)

    Stange, M.; Paul-Boncour, V.; Latroche, M.; Percheron-Guegan, A.; Isnard, O.; Yartys, V.A.

    2005-01-01

    An average Ce-valence state (v) of two types of Ce-containing intermetallic compounds, equiatomic CeNiX (X= Al, Ga, Sn) and CeM 3 (M= Ni, Co, Mn), and their hydrides was estimated from X-ray absorption spectroscopy (XAS) and analysed in parallel with hydrogen-induced volume changes on hydrogenation. The largest valence states in the initial compounds were found in CeM 3(v=3.32-3.36) followed by CeNiAl 1-x Ga x (v=3.25-3.27). This contrasts to CeNiSn, which is close to a pure trivalent state (v=3.07). On hydrogenation, a conversion from mixed-valent CeNiAl 1-x Ga x , x=0.5, 1, to pure Ce III hydrides takes place (ΔV /V=19.6-20.0 %). In CeNiSnD z (z=1, 1.8, ΔV/V=3.0, 8.0%) the changes in the valence state towards Ce III are very small. The situation for the CeM 3 -hydrides is complex. For CeNi 3 D 2.8 , CeNi 2.75 Mn 0.25 D 3.4 and CeCo 3 D 3.4 (ΔV /V=24-32%) where rather similar electronic properties can be expected, a decrease in the contribution of Ce IV for CeNi 3 D 3 and CeNi 2.75 Mn 0.25 D 3.4 (v=3.18 and 3.12, respectively) contrasts to the behaviour of CeCo 3 D 3.4 where the hydrogen induced valence change is very small (v=3.32)

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

    International Nuclear Information System (INIS)

    Andrade Nono, M.C. de.

    1990-12-01

    This work presents the development and the characterization of CeO 2 -stabilized tetragonal ZrO 2 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 CeO 2 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)

  9. Production of 139Ce by the 139La(p,n)139Ce reaction

    International Nuclear Information System (INIS)

    Ishioka, Noriko S.; Sekine, Toshiaki; Izumo, Mishiroku; Hashimoto, Kazuyuki; Kobayashi, Katsutoshi; Matsuoka, Hiromitsu

    2002-01-01

    To produce a carrier-free 139 Ce to be used as an efficiency-calibration source for Ge detectors, a target-preparation method and a chemical separation method were studied. It was found that commercially available powders of lanthanum-oxide and lanthanum metal are applicable to a target material in the nuclear reaction 139 La(p,n) 139 Ce. In the separation of 139 Ce from an irradiated lanthanum target, a solvent-extraction method and an ion-exchange method gave final products in good chemical purity. (author)

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

    Science.gov (United States)

    Onishi, Yuya; Nakamura, Toshihiro; Adachi, Sadao

    2017-02-01

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

  11. Microneedle Array Interface to CE on Chip

    NARCIS (Netherlands)

    Lüttge, Regina; Gardeniers, Johannes G.E.; Vrouwe, E.X.; van den Berg, Albert; Northrup, M.A.; Jensen, K.F; Harrison, D.J.

    2003-01-01

    This paper presents a microneedle array sampler interfaced to a capillary electrophoresis (CE) glass chip with integrated conductivity detection electrodes. A solution of alkali ions was electrokinetically loaded through the microneedles onto the chip and separation was demonstrated compared to a

  12. Metamagnetism in Ce(Ga,Al)2

    Indian Academy of Sciences (India)

    Metamagnetism in Ce(Ga,Al)2. K G SURESH1,∗. , S RADHA2 and A K NIGAM3. 1Department of Physics, Indian Institute of Technology, Mumbai 400 076, India. 2Department of Physics, Mithibai College, Mumbai 400 056, India. 3Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India. ∗.

  13. (Ln = Ce, Pr and Nd) microwave ceramics

    Indian Academy of Sciences (India)

    125–128. c Indian Academy of Sciences. Influence of lead oxide addition on LnTiTaO6 (Ln = Ce, Pr and Nd) ... A number of samples with improved microwave dielectric properties were obtained on all the systems suitable for practical ... circuits due to their compactness, thermal stability, low cost of production, high efficiency ...

  14. The crystal structure of the new mineral dyrnaesite-(La), Na8CeIVREE2(PO4)6

    DEFF Research Database (Denmark)

    Balic Zunic, Tonci

    2017-01-01

    sites, or Na sites in a [010] row (similar to [100] in vitusite-(Ce)) assume two types of coordinations with and without mirror symmetry and two different configurations of surrounding PO4 tetrahedra. This summarizes the topological difference to vitusite-(Ce) where the corresponding coordinations...

  15. Correlated electronic structure of CeN

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-04-15

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

  16. Effect of CeO2 addition on electrical and optical properties of lithium borate glasses

    International Nuclear Information System (INIS)

    Gedam, R.S.; Ramteke, D.D.

    2011-01-01

    Rare earth (RE) ions play an important role in modern technology as an active ion in many optical materials. RE-doped glasses were used in many optical devices because of abundant number of the absorption and emission bands arising from the transitions between the RE elements energy levels. Among all rare earth, glasses containing CeO 2 are extensively studied for scintillating applications. Radiation length of CeO 2 containing lithium silicate glasses decreases and absorption edge in transmittance shift towards longer wavelength. In the present study an attempt has been made to verify similar results in borate containing glasses. Therefore glass series 15Li 2 O-xCeO 2 -(85''x)B 2 O 3 where x= 0.25, 0.5, 0.75, 1 mol% was prepared by conventional melt quench technique. Their electrical and optical properties have been investigated. It is observed that the conductivity of these glasses decreases while density, glass transition temperature and refractive index increases with the addition of CeO 2 . The conductivity of the glasses is mostly controlled by the activation energy. Since the lithium fraction in the present series is kept constant, the decrease in conductivity for glasses may be attributed to the reduction in the number of available vacant sites for the mobile lithium ions when boron is substituted with CeO 2 . The radiation length was determined using density values and it was found to decrease with the addition of CeO 2 . The absorption coefficient a were determined near the absorption edge of different photon energy for all glass samples and plot of (αhν) 1/2 Vs. hν (Tauc's plot) is shown. It is observed that the optical band gap energy (E g Opt ) decreases with the addition of CeO 2

  17. The Asia-RiCE activity with data cube

    Science.gov (United States)

    Oyoshi, K.; Sobue, S.; LE Toan, T.; Lam, N. D.

    2017-12-01

    The Asia-RiCE initiative (http://www.asia-rice.org) has been organized to enhance rice production estimates through the use of Earth observation satellites data, and seeks to ensure that Asian rice crops are appropriately represented within GEO Global Agriculture Monitoring (GEO-GLAM) to support FAO Agriculture Market Information System (FAO-AMIS). Asia-RiCE is composed of national teams that are actively contributing to the Crop Monitor for AMIS and developing technical demonstrations of rice crop monitoring activities using both Synthetic Aperture Radar (SAR) data (Radarsat-2 from 2013; Sentinel-1 and ALOS-2 from 2015.From 2016 after the successful rice crop area and growing estimation using SAR in a technical demonstration site (provincial level), wall-to-wall (national scale) excurse as phase 2 has been implemented in Vietnam and Indonesia in cooperation with ministry of agriculture and space agencies. This paper reports this year activity of 2017 accomplishment and way forward, especially for analysis ready data (ARD) definition of SAR to ingest to CEOS data cube to provide national scale service in Vietnam and Indonesia.

  18. Crystal structures of isotypic aluminides CeRuAl and CeRhAl

    International Nuclear Information System (INIS)

    Gribanov, A.V.; Tursina, A.I.; Grytsiv, A.V.; Murashova, E.V.; Bukhan'ko, N.G.; Rogl, P.; Seropegin, Y.D.; Giester, G.

    2008-01-01

    The crystal structures of the compounds CeRuAl and CeRhAl were studied by single crystal X-ray diffraction. Both compounds crystallize in the orthorhombic LaNiAl type with space group Pnma (No. 62) and are related to the structure types of hexagonal ZrNiAl and orthorhombic TiNiSi. Parameters for CeRuAl and CeRhAl are: a = 7.2057(2) A, b = 4.0589(1) A, c = 15.8728(5) A; R F = 0.023; a = 7.107(2) A, b = 4.2237(10) A, c = 15.965(3) A; R F 0.032, respectively

  19. Tuning Ce distribution for high performanced Nd-Ce-Fe-B sintered magnets

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Xiaodong [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China); Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China); Guo, Shuai; Chen, Kan; Chen, Renjie; Lee, Don [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China); You, Caiyin, E-mail: caiyinyou@xaut.edu.cn [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China); Yan, Aru, E-mail: aruyan@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China)

    2016-12-01

    A dual-alloy method was applied to tune the distribution of Ce for enhancing the performance of Nd-Ce-Fe-B sintered magnets with a nominal composition of (Nd{sub 0.75}Ce{sub 0.25}){sub 30.5}Fe{sub bal}Al{sub 0.1}Cu{sub 0.1}B. In comparison to the single alloy of (Nd{sub 0.75}Ce{sub 0.25}){sub 30.5}Fe{sub bal}Al{sub 0.1}Cu{sub 0.1}B, the coercivity was enhanced from 10.3 kOe to 12.1 kOe and the remanence was increased from 13.1 kG to 13.3 kG for the magnets with a dual-alloy method. In addition, the remanence temperature coefficient α and coercivity temperature coefficient β were also slightly improved for the magnet with the dual alloys. The results of microstructure characterizations show the uniform distribution of Ce for the magnet with a single alloy, and the coexistence of the Ce-rich and Ce-lean regions for the magnet with the dual alloys. In combinations with the nucleation of reversal domains and magnetic recoil curves, the property enhancement of magnets with a dual-alloy method was well explained. - Highlights: • Improved magnetic properties were obtained in dual-alloy magnet. • This is due to the tuning of Ce distribution and the change in microstructure. • The magnetic hardening effect can be observed in dual-alloy magnet.

  20. Synthesis, Characterization and Properties of CeO2-doped TiO2 Composite Nanocrystals

    Directory of Open Access Journals (Sweden)

    Oman ZUAS

    2013-12-01

    Full Text Available Pure TiO2 and CeO2-doped TiO2 (3 % CeO2-97 %TiO2 composite nanocrystals were synthesized via co-precipitation method and characterized using TGA, XRD, FTIR, DR-UV-vis and TEM. The XRD data revealed that the phase structure of the synthesized samples was mainly in pure anatase having crystallite size in the range of 7 nm – 11 nm. Spherical shapes with moderate aggregation of the crystal particles were observed under the TEM observation. The presence of the CeO2 at TiO2 site has not only affected morphologically but also induced the electronic property of the TiO2 by lowering the band gap energy from 3.29 eV (Eg-Ti to 3.15 eV (Eg-CeTi. Performance evaluation of the synthesized samples showed that both samples have a strong adsorption capacity toward Congo red (CR dye in aqueous solution at room temperature experiment, where  the capacity of the CeTi was higher than the Ti sample. Based on DR-UV data, the synthesized samples obtained in this study may also become promising catalysts for photo-assisted removal of synthetic dye in aqueous solution. DOI: http://dx.doi.org/10.5755/j01.ms.19.4.2732

  1. Emission and excitation spectra of Ce3+ and Pr3+ ions in hexafluoroelpasolite lattices.

    Science.gov (United States)

    Duan, Chang-Kui; Tanner, Peter A; Makhov, Vladimir; Khaidukov, Nicholas

    2011-08-18

    The emission and excitation spectra of Ce(3+) and Pr(3+) doped into the cubic host Cs(2)NaYF(6) have been recorded at room temperature and ∼10 K using synchrotron radiation. The two 5d(1) T(2g) states of Ce(3+) have been located from the excitation spectra, whereas the E(g) state is placed above the host band gap. Decay measurements of the 5d(1) → 4f(1) Ce(3+) emission, and spectra collected using selective excitation, indicate the occupation of more than one type of site by Ce(3+) in this host lattice. By contrast, the location of features in the 4f(1)5d(1) → 4f(2) emission of Pr(3+) is independent of the excitation wavelength. Assignments are presented for some of the 4f(1)5d(1) levels and for the Pr(3+)-F(-) charge transfer band. The 5d emission lifetimes for Ce(3+) and Pr(3+) in the Cs(2)NaYF(6) host are 42 and 29 ± 1 ns, respectively, and are not temperature-dependent. © 2011 American Chemical Society

  2. Photocatalytic activity of the binary composite CeO{sub 2}/SiO{sub 2} for degradation of dye

    Energy Technology Data Exchange (ETDEWEB)

    Phanichphant, Sukon [Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Nakaruk, Auppatham [Department of Industrial Engineering, Faculty of Engineering, Naresuan University, Phitsanulok 65000 (Thailand); Centre of Excellence for Innovation and Technology for Water Treatment, Naresuan University, Phitsanulok 65000 (Thailand); Channei, Duangdao, E-mail: duangdaoc@nu.ac.th [Department of Chemistry, Faculty of Science, Naresuan University, Phitsanulok 65000 (Thailand); Research Center for Academic Excellence in Petroleum, Petrochemicals and Advanced Materials, Naresuan University, Phitsanulok 65000 (Thailand)

    2016-11-30

    Highlights: • The enhanced photocatalytic activity of the CeO{sub 2}/SiO{sub 2} composite can be explained by the presence of the SiO{sub 2} adsorbent, which effectively increased the surface area of the CeO{sub 2}. • The increased surface area of CeO{sub 2} should be helpful to facilitate more effective adsorption sites, which enhances the photocatalytic degradation of organic pollutant significantly. • SiO{sub 2} modification is effective in separating the photogenerated electrons and holes, which is of great importance for photocatalytic activity. • SiO{sub 2} acted as a carrier for CeO{sub 2} attachment and avoided the agglomeration of CeO{sub 2} particles. - Abstract: In this study, CeO{sub 2} photocatalyst was modified by composite with SiO{sub 2} to increase efficiency and improve photocatalytic activity. The as-prepared SiO{sub 2} particles have been incorporated into the precursor mixture of CeO{sub 2} by homogeneous precipitation and subsequent calcination process. The phase compositions of CeO{sub 2} before and after compositing with SiO{sub 2} were identified by X-ray diffraction (XRD). The morphology and particle size of CeO{sub 2}/SiO{sub 2} composite was analyzed by high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). The results showed SiO{sub 2} spheres with the particle size approximately 100–120 nm, and a uniform layer of CeO{sub 2} nanoparticles with a diameter of about 5–7 nm that were fully composite to the surfaces of SiO{sub 2}. The X-ray photoelectron spectroscopy (XPS) technique was carried out in order to characterize the change in valence state and composite characteristic by shifted peaks of binding energies. The photocatalytic activity was studied through the degradation of Rhodamine B in aqueous solution under visible light exposure. The highest photocatalytic efficiency of CeO{sub 2}/SiO{sub 2} composite was also obtained. To explain the high photocatalytic

  3. Magnetic and structural effects of partial Ce substitution in Y b{sub 14}MnSb{sub 11}

    Energy Technology Data Exchange (ETDEWEB)

    Grebenkemper, Jason H.; Kauzlarich, Susan M., E-mail: smkauzlarich@ucdavis.edu [Department of Chemistry, University of California, One Shields Ave., Davis, California 95616 (United States)

    2015-04-01

    Single crystals of Y b{sub 14−x}Ce{sub x}MnSb{sub 11} were grown from tin metal as a flux solvent with a maximum Ce incorporation of 0.6. The phases with x ∼ 0.1–0.6 crystallize in the tetragonal Ca{sub 14}AlSb{sub 11} structure type with I4{sub 1}/acd space group. In this structure type, there are 4 crystallographically unique Yb sites and the structure can be described according to the Zintl concept as containing 14Y b{sup 2+} + [MnSb{sub 4}]{sup 9−} + [Sb{sub 3}]{sup 7−} + 4Sb{sup 3−}. For x > 0.3, Ce is incorporated on specific Yb sites in the structure as a function of x, initially at x = 0.3 on the Yb(2) site followed by Yb(4) at higher values of x. These sites have the largest volume as indicated by Hirshfeld surface analysis of chemical bonding. As Ce content is increased, the ferromagnetic ordering temperatures decrease and effective paramagnetic moments increase. The magnetic ordering temperatures decrease from the undoped T{sub C} of 50 K until x ∼ 0.4, where the lowest T{sub C} of 39 K is reached. As the additional electron introduced by Ce{sup 3+} fills the hole associated with [MnSb{sub 4}]{sup 9−}, the screening of the Mn moments is reduced. This leads to an increase in overall moment attributed to Mn in addition to the moment from the Ce{sup 3+}f electron. Increasing Ce content also leads to an increase in electrical resistivity, an expected effect from reducing the carrier concentration.

  4. Neutron scattering from α-Ce at epithermal neutron energies

    Indian Academy of Sciences (India)

    tures (~10 K), whereas CeSn3 is an α-Ce-like (valence fluctuation) system (TK ~ 35. meV) that remains paramagnetic down to low temperatures. Figure 1 shows the magnetic response from CeIn3 at 20 K [9]. A broad, well-defined crystal field exci- tation and a central quasielastic distribution are observed in this compound.

  5. Facile hydrothermal synthesis of CeO2 nanopebbles

    Indian Academy of Sciences (India)

    Administrator

    Abstract. 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.

  6. Metamagnetism in Ce (Ga, Al) 2

    Indian Academy of Sciences (India)

    Strongly Correlated Electron Systems Volume 58 Issue 5-6 May-June 2002 pp 769-771 ... 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 ...

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

    International Nuclear Information System (INIS)

    Liu Jian-Jun; Yan Wei; Li Chun-Lai; Tan Xu; Ren Xin; Mu Ling-Li

    2014-01-01

    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. Thermodynamic stability studies of Ce-Sb compounds with Fe

    Science.gov (United States)

    Xie, Yi; Zhang, Jinsuo; Benson, Michael T.; Mariani, Robert D.

    2018-02-01

    Lanthanide fission products can migrate to the fuel periphery and react with cladding, causing fuel-cladding chemical interaction (FCCI). Adding a fuel additive dopant, such as Sb, can bind lanthanide, such as Ce, into metallic compounds and thus prevent migration. The present study focuses on the thermodynamic stability of Ce-Sb compounds when in contact with the major cladding constituent Fe by conducting diffusion couple tests. Ce-Sb compounds have shown high thermodynamic stability as they did not react with Fe. When Fe-Sb compounds contacted with Ce, Sb was separated out of Fe-Sb compounds and formed the more stable Ce-Sb compounds.

  9. Itinerant f-electron behavior in Ce and U compounds

    International Nuclear Information System (INIS)

    Crabtree, G.W.

    1985-04-01

    The experimentally observed Fermi surface properties in URh 3 , UIr 3 , UGe 3 , CeSn 3 , CeB 6 , U 3 As 4 , U 3 P 4 , and CeSb are reviewed. For the compounds with no magnetic order, band structure models of the Fermi surface geometry are confirmed and f-ligand hybridization is found to be dominant. For CeB 6 , U 3 As 4 , and U 3 P 4 the experiments show that both local moments and f hybridization are important. In CeSb new data can be explained by a purely local model with no f-hybridization

  10. Spin reorientation and Ce-Mn coupling in antiferromagnetic oxypnictide CeMnAsO

    Science.gov (United States)

    Vaknin, David; Zhang, Qiang; Peterson, Spencer; Dennis, Kevin; Tian, Wei

    2015-03-01

    Structure and complex magnetic properties of CeMnAsO, a parent compound of the ``1111''-type oxypnictides, have been investigated using neutron powder diffraction and magnetization measurements. Whereas there is no structural transition from the P4/nmm tetragonal phase below 420 K, CeMnAsO undergoes a C-type antiferromagnetic order with Mn2+ (S = 5 / 2) moments pointing along the c-axis below a relatively high Néel temperature of TN = 345 K. Below TSR = 35 K, two instantaneous transitions occur where the Mn moments reorient to the ab-plane preserving the C-type magnetic order, and Ce moments undergo long-range AFM ordering with moments in the ab-plane. Another transition to a noncollinear magnetic structure occurs below 7 K. We find that CeMnAsO primarily falls into the category of a local-moment antiferromagnetic insulator in which the nearest-neighbor interaction (J1) is dominant. The spin reorientation transition driven by the coupling between rare earth Ce and transition metal seems to be common to Mn, Fe and Cr ion,but not to Co and Ni ions in the iso-structural oxypnictides. Supported by the Office of Basic Energy Sciences, US-DOE, Number DE-AC02-07CH11358.

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

    Science.gov (United States)

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

    2016-01-15

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

  12. Structural and spectroscopic properties of pure and doped LiCe(PO{sub 3}){sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Abdelhedi, M., E-mail: m_abdelhedi2002@yahoo.fr [Laboratoire de Chimie Inorganique, Université de Sfax, Faculté des Sciences de Sfax, BP 1171, 3000 Sfax (Tunisia); Horchani-Naifer, K. [Laboratoire de Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National des Recherches en Sciences des Matériaux, Technopole de Borj Cedria, 6 BP 73, 8027 Soliman (Tunisia); Dammak, M. [Laboratoire de Chimie Inorganique, Université de Sfax, Faculté des Sciences de Sfax, BP 1171, 3000 Sfax (Tunisia); Ferid, M. [Laboratoire de Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National des Recherches en Sciences des Matériaux, Technopole de Borj Cedria, 6 BP 73, 8027 Soliman (Tunisia)

    2015-10-15

    Graphical abstract: Emission and excitation and spectra of Eu{sup 3+} doped LiCe(PO{sub 3}){sub 4} host lattice with 1, 2, 3 and 4 mol%. - Highlights: • Europium–doped LiCe(PO{sub 3}){sub 4} were prepared by flux method. • It was analyzed by infrared and Raman spectroscopy, and luminescence spectroscopy. • LiCe(PO{sub 3}){sub 4} doped with Eu{sup 3+} ions as luminophore host materials to produce an intense red. - Abstract: Single crystals of LiCe(PO{sub 3}){sub 4} polyphosphate have been synthesized by the flux method and its structural and luminescence properties have been investigated. This compound crystallizes in the space group C2/c with unit cell dimensions a = 16.52(7) Å, b = 7.09(4) Å, c = 9.83 (4)Å, β = 126.29(4)°, Z = 8 and V = 927.84(3) Å{sup 3}. The obtained polytetraphosphate exhibits very small crystals and the dopant Eu{sup 3+} ions were successfully incorporated into the sites of Ce{sup 3+} ions of the host lattice. The spectroscopy properties confirm the potentiality of present LiCe(PO{sub 3}){sub 4} doped with Eu{sup 3+} ions as luminophore host materials to produce an intense red luminescence at 628 nm corresponding to {sup 5}D{sub 0} → {sup 7}F{sub 2} emission level and have significant importance in the development of emission optical systems.

  13. In vitro skin decontamination of the organophosphorus pesticide Paraoxon with nanometric cerium oxide CeO2.

    Science.gov (United States)

    Salerno, Alicia; Devers, Thierry; Bolzinger, Marie-Alexandrine; Pelletier, Jocelyne; Josse, Denis; Briançon, Stéphanie

    2017-04-01

    Organophosphorus compounds (OP), which mainly penetrate via the percutaneous pathway, represent a threat for both military and civilians. Body surface decontamination is vital to prevent victims poisoning. The development of a cost-effective formulation, which could be efficient and easy to handle in case of mass contamination, is therefore crucial. Metal oxides nanoparticles, due their large surface areas and the large amount of highly reactive sites, present high reactivity towards OP. First, this study aimed at evaluating the reaction of CeO 2 nanoparticles, synthetized by microwave path and calcined at 500 or 600 °C, with Paraoxon (POX) in aqueous solution. Results showed that both nanoparticles degraded 60%-70% of POX. CeO 2 calcined at 500 °C, owing to its larger specific area, was the most effective. Moreover, the degradation was significantly increased under Ultra-Violet irradiation (initial degradation rate doubled). Then, skin decontamination was studied in vitro using the Franz cell method with pig-ear skin samples. CeO 2 powder and an aqueous suspension of CeO 2 (CeO 2 -W) were applied 1 h after POX exposure. The efficiency of decontamination, including removal and/or degradation of POX, was compared to Fuller's earth (FE) and RSDL lotion which are, currently, the most efficient systems for skin decontamination. CeO 2 -W and RSDL were the most efficient to remove POX from the skin surface and decrease skin absorption by 6.4 compared to the control not decontaminated. FE reduced significantly (twice) the absorbed fraction of POX, contrarily to CeO 2 powder. Considering only the degradation rate of POX, the products ranged in the order CeO 2  > RSDL > CeO 2 -W > FE (no degradation). This study showed that CeO 2 nanoparticles are a promising material for skin decontamination of OP if formulated as a dispersion able to remove POX like CeO 2 -W and to degrade it as CeO 2 powder. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  14. Spin reorientation and Ce-Mn coupling in antiferromagnetic oxypnictide CeMnAsO

    OpenAIRE

    Zhang, Qiang; Tian, Wei; Peterson, Spencer G.; Dennis, Kevin W.; Vaknin, David

    2014-01-01

    Structure and magnetic properties of high-quality polycrystlline CeMnAsO, a parent compound of the "1111"-type oxypnictides, have been investigated using neutron powder diffraction and magnetization measurements. We find that CeMnAsO undergoes a C-type antiferromagnetic order with Mn$^{2+}$ ($S=5/2$) moments pointing along the \\textit{c}-axis below a relatively high N\\'{e}el temperature of $T_{\\rm N} = 345$ K. Below $T_{\\rm SR} = 35$ K, two instantaneous transitions occur where the Mn moments...

  15. Neutron emission following muon capture in Ce-142, Ce-140, Ba-138, and Sn-120.

    Science.gov (United States)

    Lucas, G. R., Jr.; Martin, P.; Welsh, R. E.; Jenkins, D. A.; Powers, R. J.; Kunselman, A. R.; Miller, G. H.

    1973-01-01

    Branching ratios to excited nuclear states formed after muon capture have been measured with Ge(Li) detectors. The delayed gamma rays were observed in studies of muonic Ce-142, Ce-140, Ba-138, and Sn-120, using separated isotopes. The resulting isotopes formed indicate at least a 60% probability of neutron emission upon muon capture, with the most likely product resulting from single-neutron emission. No evidence for delayed proton emission with a probability higher than 2% was found. Using our more precise energies for the observed nuclear transitions, we present revised energy levels schemes for La-141, La-139, Cs-137, and In-119.

  16. Transient analysis capabilities at ABB-CE

    International Nuclear Information System (INIS)

    Kling, C.L.

    1992-01-01

    The transient capabilities at ABB-Combustion Engineering (ABB-CE) Nuclear Power are a function of the computer hardware and related network used, the computer software that has evolved over the years, and the commercial technical exchange agreements with other related organizations and customers. ABB-CEA is changing from a mainframe/personal computer network to a distributed workstation/personal computer local area network. The paper discusses computer hardware, mainframe computing, personal computers, mainframe/personal computer networks, workstations, transient analysis computer software, design/operation transient analysis codes, safety (licensed) analysis codes, cooperation with ABB-Atom, and customer support

  17. Synthesis and characterization of Ce doped MFI zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Kalita, Banani [Department of Chemistry, Gauhati University, Guwahati, Assam 781014 (India); Talukdar, Anup K., E-mail: anup_t@sify.com [Department of Chemistry, Gauhati University, Guwahati, Assam 781014 (India)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer Cerium was incorporated into the tetrahedral position of MFI zeolite structure. Black-Right-Pointing-Pointer Unit cell volume increases with an increase of Ce content in the framework of MFI. Black-Right-Pointing-Pointer A band at 310 nm in the UV-vis spectra indicates Ce incorporation in MFI structure. Black-Right-Pointing-Pointer The mass loss (%) in the region 373-423 K decreases with increase of Ce in MFI. - Abstract: Ce doped MFI (mobil five) zeolites with different Si to (Ce + Al) and different Ce to Al ratios were synthesized by a hydrothermal synthesis method. All the samples were characterized by different techniques such as X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), UV-vis diffuse reflectance spectroscopy (DRS) and scanning electron microscopy (SEM). The results showed that almost pure MFI phase was obtained in all cases with incorporation of cerium metal into the framework. The increase in unit cell parameters observed with an increase in Ce content is indicative of incorporation of Ce into the framework structure of microporous material MFI. Corroboration of the framework incorporation of Ce into the MFI zeolite structure was also obtained from the UV-vis DRS spectra by the presence of an absorption band at 280 nm. TGA and SEM of the samples provide complementary evidence for Ce incorporation into the framework MFI structure.

  18. La Substitution and Pressure Studies on CeCoSi: A Possible Antiferroquadrupolar Ordering Induced by Pressure

    Science.gov (United States)

    Tanida, Hiroshi; Muro, Yuji; Matsumura, Takeshi

    2018-02-01

    The La-substitution and pressure effects on antiferromagnet CeCoSi with a tetragonal crystal structure were investigated in order to clarify the origin of the pressure induced ordered phase (PIOP) with an enormously high transition temperature of T0 ˜ 38 K. By substituting Ce with La, the PIOP shifts to high pressures, and the maximum value of T0 is suppressed, indicating that the PIOP originates from a Ce-Ce interaction. At T0, the magnetic susceptibility exhibits not a cusp, but an increase with decreasing temperature, as is frequently observed in antiferroquadrupolar (AFQ) ordering. Based on these results, we propose that a possible origin of the PIOP is an AFQ ordered phase of Ce-4f electron. Due to the lack of local inversion symmetry at the Ce sites, the AFQ order could be accompanied by odd parity multipolar moments. Since there is no clear evidence of successive transitions below T0, the remaining Kramers degeneracy could be lifted by the Kondo coupling.

  19. Structural analysis and superconductivity of CeFeAsO1-xHx

    Science.gov (United States)

    Matsuishi, Satoru; Hanna, Taku; Muraba, Yoshinori; Kim, Sung Wng; Kim, Jung Eun; Takata, Masaki; Shamoto, Shin-Ich; Smith, Ronald I.; Hosono, Hideo

    2012-01-01

    We performed the neutron powder diffraction (NPD) and synchrotron x-ray diffraction measurements on CeFeAsO1-x(D,H)x (x = 0.0 - 0.48) as a representative of 1111-type family of iron-based superconductors LnFeAsO1-xHx (Ln = lanthanoid). Deuterated and hydrogenated samples (CeFeAsO1-xDx and CeFeAsO1-xHx) were synthesized by the solid-state reaction of a metal oxide, arsenides, and a hydride and a deuteride source under an applied pressure of 2 GPa. No distinct differences were found between the structural and superconducting properties of the hydride and deuteride samples. Rietveld analyses of the NPD patterns demonstrated that deuterium exclusively substitutes on the oxygen sites in the 1111-type structures according to the nominal composition. Bulk superconductivity was observed over a wide x region (0.1 x x = 0.25. It was concluded from density functional theory calculations and comparison with the superconducting dome of the fluorine-substituted system that the charge state of the hydrogen substituting the oxygen sites was -1. The relationship between the lattice parameter a and Tc in our samples prepared from metal hydrides is almost the same as that reported previously for samples prepared from cerium hydroxide. These results strongly suggest that H- ions exclusively occupy the oxygen sites in both samples, regardless of the hydrogen species in the starting material.

  20. Ab initio study of solid CeIn3 at high pressures

    Directory of Open Access Journals (Sweden)

    M. Ilkhani

    2008-06-01

    Full Text Available   Electric field gradients (EFG’s at the In sites and spin magnetic moments at the Ce sites were calculated for the case of solid CeIn3. The calculations were performed by increasing pressure gradually from -5 to +22 GPa within the density functional theory (DFT using the augmented plane waves plus local orbital (APW+lo method employing the well-known PBE-GGA+U and WC-GGA+U schemes. The results almost show a linear reduction of spin magnetic moments of Ce by gradually increasing the pressure from -5 GPa to 22 GPa. However, from our results one can see that the calculated electric field gradients at the In site are growing up by increasing the pressure. We have compared the EFG’s at zero pressure with experimental and theoretical results of the others. The comparison shows that at ambient pressure our EFG’s are more consistent with experiment than the results of the other groups. Our result shows that the calculated spin magnetic moments are suppressed in the vicinity of some quantum critical point.

  1. Anodized porous titanium coated with Ni-CeO2 deposits for enhancing surface toughness and wear resistance

    Science.gov (United States)

    Zhou, Xiaowei; Ouyang, Chun

    2017-05-01

    In order to make large improvements of surface toughness and wear resistance for pure titanium (Ti) substrate, anodic titanium oxide (ATO) surface with nanoporous structure was coated with the Ni-CeO2 nanocomposite coatings. Regarding TiO2 barrier layer on Ti surface to inhibit its electrochemical activity, pre-treatments were successively processed with anodizing, sensitizing, activating, and then followed by electroless Ni-P film to be acted as an activated layer for electroplating Ni-CeO2 deposits. The existing Pd atoms around ATO nanopores were expected as the heterogeneous nucleation sites for supporting the growing locations of electroless Ni-P film. The innovative of interface design using porous structure was introduced for bonding pinholes to achieve a metallurgical adhesion interface between Ti substrate and surface coatings. Besides the objectives of this work were to elucidate how effects by the adding CeO2 nanoparticles on modifying microstructures and wear mechanisms of Ni-CeO2 nanocomposite coatings. Many efforts of XRD, FE-SEM, TEM and Nanoindentation tests were devoted to comparing different wear behaviors of Ni-CeO2 coatings relative to pure nickel. Results indicated that uniform-distributed Ti nanopores with an average diameter size of ∼200 nm was achieved using the Phosphate-type anodizing solution at DC 150 V. A worn surface without fatigue cracks was observed for TAO surface coated with Ni-CeO2 deposits, showing the existing Ce-rich worn products to be acted as a solid lubricant phase for making a self-healing effect on de-lamination failures. More important, this finding will be the guidelines for Ce-rich precipitations to be expected as the strengthening phase in anodized porous of Ti, Al and Mg alloys for intensifying their surface properties.

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

    International Nuclear Information System (INIS)

    Kim, Si Hyung; Kim, Gha-Young; Lee, Seung-jai; Kim, Taek-Jin; Paek, Seungwoo; Ahn, Do-Hee

    2015-01-01

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

  3. The broad emission at 785 nm in YAG:Ce3 +,Cr3 + phosphor

    Science.gov (United States)

    Zhou, Xianju; Luo, Xiaoxia; Wu, Bing; Jiang, Sha; Li, Li; Luo, Xiaobing; Pang, Yu

    2018-02-01

    Luminescence of defects and/or impurities is important for phosphors. One broad emission band centered at 785 nm was observed in (Y0.97Ce0.03)3(Al1-xCrx)5O12 (x = 0.005, 0.01, 0.03, 0.06, 0.09), (YAG:Ce,Cr) nano-particles synthesized by polymer-assisted sol-gel method in this work. In order to study the source of this wide emission band, the crystalline phase structure of the phosphors was examined by X-ray diffraction (XRD). No obvious diffraction peaks due to impurity phase were observed even though the calcining temperature of the samples arrived at 1400 °C. The anti-site defects were excluded. No detectable signals of impurities were obtained by X-ray Photoelectron Spectroscopy (XPS) or inductively coupled plasma mass spectrometry (ICP-MS). Based on the photo-luminescence results of YAG:Ce,Cr, YAG:Ce and YAG:Fe phosphors, the wide emission band is attributed to the 4T1(4G) → 6A1(6S) transition from the trace impurity of Fe3 +. The excitation band at 280 nm is assigned to Fe3 +-O2- charge transfer band.

  4. Public Data at CeSAM

    Science.gov (United States)

    Moreau, C.; Le Brun, V.; Agneray, F.; Gimenez, S.; Roehlly, Y.

    2014-05-01

    Modern large observational programs produce important amounts of data from various origins, and need high level data-quality control, fast data access via easy-to-use graphic interfaces, as well as possibility to cross-correlate informations coming from different observations. The Centre de donneS Astrophysique de Marseille (CeSAM) has for mission to provide support to the teams in charge of the observational programs (specifications, software development and infrastructures), to produce and give the final data by proposing tools increasing their scientific value. We present here the various datasets hosted by the CeSAM under the ANIS environment. Even if mainly oriented towards large spectro-photometric extragalactic samples, we host as well an exoplanet transit database, or resolved galaxy data. The main datasets are those from the VVDS final release (45000 spectra), the Herschel extragalactic surveys (HerMES, HRS, GOODS-Herschel, VNGS), the CFHTLS-WIDE photometric redshifts catalog (17 millions objects), or the HST-COSMOS information system, that allows request from any of the 6 and access to the corresponding values in the other catalogs.

  5. Direct observation of multivalent states and 4 f →3 d charge transfer in Ce-doped yttrium iron garnet thin films

    Science.gov (United States)

    Vasili, H. B.; Casals, B.; Cichelero, R.; Macià, F.; Geshev, J.; Gargiani, P.; Valvidares, M.; Herrero-Martin, J.; Pellegrin, E.; Fontcuberta, J.; Herranz, G.

    2017-07-01

    Due to their large magneto-optic responses, rare-earth-doped yttrium iron garnets, Y3F e5O12 (YIG), are highly regarded for their potential in photonics and magnonics. Here, we consider the case of Ce-doped YIG (Ce-YIG) thin films, in which substitutional C e3 + ions are magnetic because of their 4 f1 ground state. In order to elucidate the impact of Ce substitution on the magnetization of YIG, we have carried out soft x-ray spectroscopy measurements on Ce-YIG films. In particular, we have used the element specificity of x-ray magnetic circular dichroism to extract the individual magnetization curves linked to Ce and Fe ions. Our results show that Ce doping triggers a selective charge transfer from Ce to the Fe tetrahedral sites in the YIG structure. This, in turn, causes a disruption of the electronic and magnetic properties of the parent compound, reducing the exchange coupling between the Ce and Fe magnetic moments and causing atypical magnetic behavior. Our work is relevant for understanding magnetism in rare-earth-doped YIG and, eventually, may enable a quantitative evaluation of the magneto-optical properties of rare-earth incorporation into YIG.

  6. Luminescence properties and gamma-ray response of the Ce and Ca co-doped (Gd,Y)F{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kamada, Kei, E-mail: k-kamada@furukawakk.co.jp [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai (Japan); Furukawa Co. Ltd. (Japan); Yanagida, Takayuki; Fujimoto, Yutaka; Fukabori, Akihiro [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai (Japan); Yoshikawa, Akira [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai (Japan); New Industry Creation Hatchery Center, Tohoku University, Sendai (Japan); Nikl, Martin [Institute of Physics AS CR (Czech Republic)

    2011-12-11

    The Ca0.5% and Ce1%, 3%, 7%, 10% co-doped Gd{sub 0.5}Y{sub 0.5}F{sub 3} single crystals were grown by the {mu}-PD method. In the Ca0.5% and Ce3% co-doped sample, Ce{sup 3+}-perturbed luminescence at 380 nm was observed with 32.4 ns photoluminescence decay time. The energy transfer in the sequence of the regular Ce{sup 3+}{yields} (Gd{sup 3+}){sub n}{yields} the perturbed Ce{sup 3+} sites was evidenced through observation of decay time shortening of the regular Ce{sup 3+} and Gd{sup 3+} centers and the change between the Gd{sup 3+} and Ce{sup 3+}-perturbed emission intensity. The gamma-ray excited scintillation response of the Ca0.5%, Ce7% co-doped Gd{sub 0.5}Y{sub 0.5}F{sub 3} sample was investigated with the help of the pulse height spectra and the light yield, energy resolution and non-proportionality was evaluated in the interval of energies of 59.4-1274 keV.

  7. Luminescence properties and gamma-ray response of the Ce and Ca co-doped (Gd,Y)F3 single crystals

    International Nuclear Information System (INIS)

    Kamada, Kei; Yanagida, Takayuki; Fujimoto, Yutaka; Fukabori, Akihiro; Yoshikawa, Akira; Nikl, Martin

    2011-01-01

    The Ca0.5% and Ce1%, 3%, 7%, 10% co-doped Gd 0.5 Y 0.5 F 3 single crystals were grown by the μ-PD method. In the Ca0.5% and Ce3% co-doped sample, Ce 3+ -perturbed luminescence at 380 nm was observed with 32.4 ns photoluminescence decay time. The energy transfer in the sequence of the regular Ce 3+ → (Gd 3+ ) n → the perturbed Ce 3+ sites was evidenced through observation of decay time shortening of the regular Ce 3+ and Gd 3+ centers and the change between the Gd 3+ and Ce 3+ -perturbed emission intensity. The gamma-ray excited scintillation response of the Ca0.5%, Ce7% co-doped Gd 0.5 Y 0.5 F 3 sample was investigated with the help of the pulse height spectra and the light yield, energy resolution and non-proportionality was evaluated in the interval of energies of 59.4-1274 keV.

  8. Neutron scattering from α-Ce at epithermal neutron energies

    Indian Academy of Sciences (India)

    the constant-ω integration within an energy bandwidth of ±30 meV around. 170 meV [13]. The continuous curve through the data shows the Ce3+ mag- netic form factor. The doted line shows the calculated form factor for an itinerant 4f electron band for α-Ce [14]. et al [14] calculated within the itinerant 4f band model for Ce.

  9. A novel structural design of a Pt/C-CeO{sub 2} catalyst with improved performance for methanol electro-oxidation by {beta}-cyclodextrin carbonization

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Yuan-Yuan; Jiang, Zheng-Zhi [School of Chemical Engineering and Technology, Harbin Institute of Technology, No.92 West-Da Zhi Street, Harbin (China); School of Science, Harbin Institute of Technology, Harbin (China); Wang, Zhen-Bo; Yin, Ge-Ping [School of Chemical Engineering and Technology, Harbin Institute of Technology, No.92 West-Da Zhi Street, Harbin (China); Gu, Da-Ming [School of Science, Harbin Institute of Technology, Harbin (China)

    2011-07-19

    A novel structural Pt/C-CeO{sub 2} catalyst synthesized using MP-CeO{sub 2} coated with carbon by in situ {beta}-cyclodextrin carbonization and then depositing Pt nanoparticles using a fast and facile microwave-assisted polyol process. The increased electron conductivity and the more oxygen-containing species of carbon available for the Pt site contribute to the improved activity and stability for methanol oxidation compared to Pt/CeO{sub 2}. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Broadband Luminescence in Rare Earth Doped Sr2SiS4: Relating Energy Levels of Ce3+ and Eu2+

    Directory of Open Access Journals (Sweden)

    Anthony B. Parmentier

    2013-08-01

    Full Text Available Sr2SiS4:Ce3+ is an efficient blue-emitting (460 nm phosphor, excitable with light of wavelengths up to 420 nm. From the excitation spectrum, we construct the energy level scheme and use it to check the predictive power of the Dorenbos model, relating the positions of the Ce3+ energy levels with those of Eu2+ in the same host. For strontium thiosilicate, this method gives excellent results and allows us to determine which of two available crystallographic sites is occupied by cerium. We use the Dorenbos method for extracting information on the coordination of Ce3+ from the observed crystal field splitting.

  11. CeO2-ZrO2 ceramic compounds

    International Nuclear Information System (INIS)

    Melo, F.C.L.; Cairo, C.A.C.; Devezas, T.C.; Nono, M.C.A.

    1988-01-01

    In order to study the mechanical properties of tetragonal polycrystal zirconia stabilized with ceria various powder compositions with different CeO 2 content were made. Modulus of rupture for those compounds was measured. Tetragonal retained phase was determined for samples of CeO 2 -ZrO 2 ceramics with and without superficial mechanical treatment. The experimental results allowed us to evaluate the effects of CeO 2 content and sintering temperature in the mechanical properties and tetragonal transformed phase (t→ m) in ceramics of CeO 2 -ZrO 2 systems. (author) [pt

  12. High-Resolution Resonance Photoemission Study of CeNi

    International Nuclear Information System (INIS)

    Sekiyama, A.; Kadono, K.; Iwasaki, T.; Imada, S.; Kasai, S.; Suga, S.; Araki, S.; Onuki, Y.

    2003-01-01

    We have performed the high-resolution Ce 3d - 4f resonance photoemission study of a considerably hybridized CeNi with the Kondo temperature of ∼ 150 K. The tail of the Kondo-resonance peak is predominantly observed in the bulk Ce 4f photoemission spectra, where its spin-orbit partner is suppressed compared with the so far reported surface-sensitive Ce 4d-4f resonance spectrum. Our results show that the bulk 4f electronic states are essentially understood by the single impurity Anderson model. (author)

  13. Inverted opal luminescent Ce-doped silica glasses

    Directory of Open Access Journals (Sweden)

    R. Scotti

    2006-01-01

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

  14. Synthesis and physico-chemical characterization of CeO2/ZrO2-SO42- mixed oxides

    International Nuclear Information System (INIS)

    Hernandez E, J. M.; Silva R, R.; Garcia A, R.; Garcia S, L. A.; Handy, B. E.; Cardenas G, G.; Cueto H, A.

    2012-01-01

    Environmentally friendly solid-acid catalysts CeO 2 /ZrO 2 -SO 4 2- were prepared by the sol gel method varying CeO 2 content (10, 20 and 30 wt %) and using sulfation in situ, maintaining the sulfate ions amount present in the materials at 20 wt %. ZrO 2 and ZrO 2 -SO 4 2- were also prepared for comparison proposes using the same synthesis method. The materials were characterized by X-ray diffraction, nitrogen physisorption, potentiometric titration with n-butylamine, decomposition of 2-propanol and n-pentane isomerization. The specific surface area of ZrO 2 -SO 4 2- was high (160 m 2 /g) compared with the unmodified ZrO 2 (80 m 2 /g), however this area decreased with increasing the CeO 2 content (37-100 m 2 /g). There was no significant effect of CeO 2 on the tetragonal structure of ZrO 2 -SO 4 2- . The variation of acid sites amount runs parallel to the change of specific surface area. The acid sites amount decreased with increasing cerium oxide content. The decomposition of 2-propanol results fundamentally in the formation of dehydration products such as propylene and diisopropyl ether, both involving acid sites. In addition, a good performance during the n-pentane isomerization was observed for these materials. The selectivity towards isopentane reaches 84% when the Pt/CeO 2 /ZrO 2 -SO 4 2- catalyst with the highest CeO 2 content was used. (Author)

  15. Study of the crystal field in CeF3 and CeF3:Pr3+

    Directory of Open Access Journals (Sweden)

    Shafikov F.F., Savinkov A.V., Tagirov M.S.

    2016-12-01

    Full Text Available The crystal field analysis based on calculations in the framework of the semi phenomenological exchange charge model was carried out. The set of crystal field parameters for Ce3+ and Pr3+ ions in the matrix CeF3 related to the crystallographic system of coordinates has been obtained and used to reproduce satisfactory the crystal field energies of Ce3+ and Pr3+ ions.

  16. Interfacing HTCondor-CE with OpenStack

    Science.gov (United States)

    Bockelman, B.; Caballero Bejar, J.; Hover, J.

    2017-10-01

    Over the past few years, Grid Computing technologies have reached a high level of maturity. One key aspect of this success has been the development and adoption of newer Compute Elements to interface the external Grid users with local batch systems. These new Compute Elements allow for better handling of jobs requirements and a more precise management of diverse local resources. However, despite this level of maturity, the Grid Computing world is lacking diversity in local execution platforms. As Grid Computing technologies have historically been driven by the needs of the High Energy Physics community, most resource providers run the platform (operating system version and architecture) that best suits the needs of their particular users. In parallel, the development of virtualization and cloud technologies has accelerated recently, making available a variety of solutions, both commercial and academic, proprietary and open source. Virtualization facilitates performing computational tasks on platforms not available at most computing sites. This work attempts to join the technologies, allowing users to interact with computing sites through one of the standard Computing Elements, HTCondor-CE, but running their jobs within VMs on a local cloud platform, OpenStack, when needed. The system will re-route, in a transparent way, end user jobs into dynamically-launched VM worker nodes when they have requirements that cannot be satisfied by the static local batch system nodes. Also, once the automated mechanisms are in place, it becomes straightforward to allow an end user to invoke a custom Virtual Machine at the site. This will allow cloud resources to be used without requiring the user to establish a separate account. Both scenarios are described in this work.

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

    KAUST Repository

    Ferraro, Daniela

    2017-01-09

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

  18. Dopant concentration dependence of radiation-induced positive hysteresis of Ce:GSO and Ce:GSOZ

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Fujimoto, Yutaka; Watanabe, Kenichi

    2014-01-01

    Positive hysteresis and radiation tolerance to high-dose radiation exposure were investigated for Ce 0.5, 1, and 1.5%-doped Gd 2 SiO 5 (GSO) and for Zr co-doped GSO with the same Ce concentrations (GSOZ). When they were irradiated by 200–800 Gy 60 Co in 200 Gy steps, all Ce-doped GSO samples exhibited light yield enhancement (positive hysteresis). On the other hand, the light yield of GSOZ decreased greatly. Ce 0.5%-doped GSO showed the highest positive hysteresis, with ∼20% light yield enhancement. When the Ce concentration was increased, the positive hysteresis became weaker. - Highlights: • Positive hysteresis Ce 0.5, 1, and 1.5% doped GSO and GSOZ are studied. • Ce 0.5, 1, and 1.5% doped GSO show the positive hysteresis by 2–8 M rad 60 Co irradiation. • Ce 0.5, 1, and 1.5% doped GSOZ do not show the positive hysteresis. • By Zn co-doping, radiation tolerance of GSO becomes weaker. • By dense Ce doping, radiation tolerance of GSO and GSOZ are improved

  19. Traducerea: între ce se poate traduce și ce trebuie tradus

    Directory of Open Access Journals (Sweden)

    Magda Jeanrenaud

    2016-02-01

    Full Text Available Pornind de la o tulburătoare interpretare a lui Jacques Derrida, studiul de față își propune să investigheze și încearcă să explice blocajul ce intervine în versiunile englezești, franceze și românești (semnate de Antoine Berman, Alexis Nouss, Steven Rendall, Catrinel Pleșu etc. ale celebrului text al lui Walter Benjamin, Die Aufgabe des Übersetzers, atunci cînd traducătorii transpun în cele trei limbi țintă cele două citate cuprinse în acesta: un citat din Mallarmé, lăsat netradus de Benjamin însuși, și un altul, din Pannwitz. Într-un fel sau altul, ambele citate au o formă discursivă ce lasă să se întrevadă o sintaxă ce se abate deliberat de la normă, ca și cum ar fi deja niște „traduceri”. Analiza mai pune în evidență și comportamentul (cumva o dominantă a psihologiei traducătorilor? celor ce au transpus textul benjaminian, comportament marcat de obsesia lizibilității văzută ca o trăsătură congenitală a oricărei traduceri, chiar și atunci cînd textul original nu tinde spre aceasta. De unde și dilema, dureroasă, legată de spinoasa chestiune a intenționalității textului (nu doar de tradus...

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

    Indian Academy of Sciences (India)

    Recently, Smith et al [1] have communicated the existence of neutron-deficient 122Ce and its excited states have been reported up to spin 14¯h. The band has been as- signed to 122Ce by detecting γ-rays in coincidence with evaporated charged particles and neutrons. The nucleus is believed to have large ground state ...

  1. Facile hydrothermal synthesis of CeO2 nanopebbles

    Indian Academy of Sciences (India)

    Administrator

    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 .... state.26 In our case, the valence of cerium ions will be mainly 4+ state, because the estimated particle size of.

  2. Three-Dimensional Structure of CeO2 Nanocrystals

    DEFF Research Database (Denmark)

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

    2011-01-01

    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...

  3. Ce que nous faisons | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Le CRDI appuie des travaux de recherche dans les pays en voie de développement en vue de produire un changement réel et durable. Ce savoir peut servir d'outil pour résoudre des problèmes mondiaux urgents. Nous partageons ce savoir avec les autres en :

  4. A permselective CeO{sub x} coating to improve the stability of oxygen evolution electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Obata, Keisuke; Takanabe, Kazuhiro [King Abdullah University of Science and Technology (KAUST), KAUST Catalysis Center (KCC) and Physical Sciences and Engineering Division PSE, Thuwal (Saudi Arabia)

    2018-02-05

    Highly active NiFeO{sub x} electrocatalysts for the oxygen evolution reaction (OER) suffer gradual deactivation with time owing to the loss of Fe species from the active sites into solution during catalysis. The anodic deposition of a CeO{sub x} layer prevents the loss of such Fe species from the OER catalysts, achieving a highly stable performance. The CeO{sub x} layer does not affect the OER activity of the catalyst underneath but exhibits unique permselectivity, allowing the permeation of OH{sup -} and O{sub 2} through while preventing the diffusion of redox ions through the layer to function as a selective O{sub 2}-evolving electrode. The use of such a permselective protective layer provides a new strategy for improving the durability of electrocatalysts. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. A permselective CeOx coating to improve the stability of oxygen evolution electrocatalysts

    International Nuclear Information System (INIS)

    Obata, Keisuke; Takanabe, Kazuhiro

    2018-01-01

    Highly active NiFeO x electrocatalysts for the oxygen evolution reaction (OER) suffer gradual deactivation with time owing to the loss of Fe species from the active sites into solution during catalysis. The anodic deposition of a CeO x layer prevents the loss of such Fe species from the OER catalysts, achieving a highly stable performance. The CeO x layer does not affect the OER activity of the catalyst underneath but exhibits unique permselectivity, allowing the permeation of OH - and O 2 through while preventing the diffusion of redox ions through the layer to function as a selective O 2 -evolving electrode. The use of such a permselective protective layer provides a new strategy for improving the durability of electrocatalysts. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. A Permselective CeOx Coating Improves the Stability of Oxygen Evolution Electrocatalysts

    KAUST Repository

    Obata, Keisuke

    2017-12-05

    Highly active NiFeOx electrocatalysts for the oxygen evolution reaction (OER) suffer gradual deactivation with time due to the loss of Fe species from the active sites into solution during catalysis. Here, we describe the anodic deposition of a CeOx layer that prevents the loss of such Fe species from the OER catalysts, achieving a highly stable performance. The CeOx layer does not affect the OER activity of the catalyst underneath but exhibits unique permselectivity, allowing the permeation of OH- and O2 through while preventing the diffusion of redox ions through the layer to function as a selective O2-evolving electrode. The use of such permselective protective layer provides a new strategy for improving the durability of electrocatalysts.

  7. Anodized porous titanium coated with Ni-CeO{sub 2} deposits for enhancing surface toughness and wear resistance

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiaowei, E-mail: zhouxiaowei901@163.com; Ouyang, Chun

    2017-05-31

    Highlights: • Structural design of anodized nanoporous Ti was introduced for bonding pinholes to achieve a metallurgical bonding interface. • Anodized porous Ti substrate was activated by electroless Ni-P film to be acted as transitional layer to deposit Ni-CeO{sub 2} nanocomposite coatings. • An analytical model was validated for predicting the Ce-rich worn products as a self-lubricant phase for monitoring wear mechanisms. - Abstract: In order to make large improvements of surface toughness and wear resistance for pure titanium (Ti) substrate, anodic titanium oxide (ATO) surface with nanoporous structure was coated with the Ni-CeO{sub 2} nanocomposite coatings. Regarding TiO{sub 2} barrier layer on Ti surface to inhibit its electrochemical activity, pre-treatments were successively processed with anodizing, sensitizing, activating, and then followed by electroless Ni-P film to be acted as an activated layer for electroplating Ni-CeO{sub 2} deposits. The existing Pd atoms around ATO nanopores were expected as the heterogeneous nucleation sites for supporting the growing locations of electroless Ni-P film. The innovative of interface design using porous structure was introduced for bonding pinholes to achieve a metallurgical adhesion interface between Ti substrate and surface coatings. Besides the objectives of this work were to elucidate how effects by the adding CeO{sub 2} nanoparticles on modifying microstructures and wear mechanisms of Ni-CeO{sub 2} nanocomposite coatings. Many efforts of XRD, FE-SEM, TEM and Nanoindentation tests were devoted to comparing different wear behaviors of Ni-CeO{sub 2} coatings relative to pure nickel. Results indicated that uniform-distributed Ti nanopores with an average diameter size of ∼200 nm was achieved using the Phosphate-type anodizing solution at DC 150 V. A worn surface without fatigue cracks was observed for TAO surface coated with Ni-CeO{sub 2} deposits, showing the existing Ce-rich worn products to be acted as a

  8. Low temperature synthesis of fluorite-type Ce-based oxides of ...

    Indian Academy of Sciences (India)

    M MALATHI

    type) Ce-based oxides of compositions Ln2Ce2O7 (Ln = Pr, Nd and Eu). F-type oxides can be considered as multi-functional materials due to the deficiency of anions. Pr2Ce2O7 (PCO), Nd2Ce2O7 (NCO) and Eu2Ce2O7 (ECO) were prepared ...

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

    Science.gov (United States)

    Zhang, Yongwei; Werling, Uwe; Edelmann, Winfried

    2014-01-01

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

  10. Multimedia Experience on Web-Connected CE Devices

    Science.gov (United States)

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

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

  11. 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.

  12. 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.

  13. Radio- and photoluminescence properties of Ce/Tb co-doped glasses with huntite-like composition

    Science.gov (United States)

    Lorenzi, Roberto; Golubev, Nikita V.; Ziaytdinova, Mariyam Z.; Jarý, Vítězslav; Babin, Vladimir; Malashkevich, Georgii E.; Paleari, Alberto; Sigaev, Vladimir N.; Fasoli, Mauro; Nikl, Martin

    2018-04-01

    Optical properties of yttria-aluminoborate (YAB) glasses with general composition 10(CexTbyY(1-x-y))-30Al2O3-60B2O3 are investigated and compared with data available on YAB crystals with huntite-like structure. Ce doped samples show optical features ascribable to preferential location of rare earth ions in sites with specific geometry similar to that observed in crystalline structures. Samples prepared with Tb ions as emission activator and Ce ions as sensitizer have been studied within the framework of non-radiative energy transfer. The resulting Förster radius is of 4.6 ± 0.5 Å comparable with that observed in Ce/Tb co-doped YAl3(BO3)4 crystals. The investigated materials possess radio- and photoluminescence emission efficiencies and performances comparable to that of crystalline counterparts with the advantage of having easiness of preparation and workability typical of glassy systems.

  14. In situ DRIFTS investigation of NH3-SCR reaction over CeO2/zirconium phosphate catalyst

    Science.gov (United States)

    Zhang, Qiulin; Fan, Jie; Ning, Ping; Song, Zhongxian; Liu, Xin; Wang, Lanying; Wang, Jing; Wang, Huimin; Long, Kaixian

    2018-03-01

    A series of ceria modified zirconium phosphate catalysts were synthesized for selective catalytic reduction of NO with ammonia (NH3-SCR). Over 98% NOx conversion and 98% N2 selectivity were obtained by the CeO2/ZrP catalyst with 20 wt.% CeO2 loading at 250-425 °C. The interaction between CeO2 and zirconium phosphate enhanced the redox abilities and surface acidities of the catalysts, resulting in the improvement of NH3-SCR activity. The in situ DRIFTS results indicated that the NH3-SCR reaction over the catalysts followed both Eley-Rideal and Langmuir-Hinshelwood mechanisms. The amide (sbnd NH2) groups and the NH4+ bonded to Brønsted acid sites were the important intermediates of Eley-Rideal mechanism.

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

    CERN Document Server

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

    2003-01-01

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

  16. Sulfur resistance of Ce-Mn/TiO2 catalysts for low-temperature NH3-SCR

    Science.gov (United States)

    Xu, Quan; Yang, Wenjing; Cui, Shitong; Street, Jason; Luo, Yan

    2018-03-01

    Ce-Mn/TiO2 catalyst prepared using a simple impregnation method demonstrated a better low-temperature selective catalytic reduction of NO with NH3 (NH3-SCR) activity in comparison with the sol-gel method. The Ce-Mn/TiO2 catalyst loading with 20% Ce had the best low-temperature activity and achieved a NO conversion rate higher than 90% at 140-260°C with a 99.7% NO conversion rate at 180°C. The Ce-Mn/TiO2 catalyst only had a 6% NO conversion rate decrease after 100 ppm of SO2 was added to the stream. When SO2 was removed from the stream, the catalyst was able to recover completely. The crystal structure, morphology, textural properties and valence state of the metals involving the novel catalysts were investigated using X-ray diffraction, N2 adsorption and desorption analysis, X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive spectroscopy, respectively. The decrease of NH3-SCR performance in the presence of 100 ppm SO2 was due to the decrease of the surface area, change of the pore structure, the decrease of Ce4+ and Mn4+ concentration and the formation of the sulfur phase chemicals which blocked the active sites and changed the valence status of the elements.

  17. Effect of Adding Cerium on Microstructure and Morphology of Ce-Based Inclusions Formed in Low-Carbon Steel

    Science.gov (United States)

    Adabavazeh, Z.; Hwang, W. S.; Su, Y. H.

    2017-05-01

    Intra-granular Acicular Ferrite (IAF), as one of the most well-known desirable microstructure of ferrite with a chaotic crystallographic orientation, can not only refine the microstructure and retard the propagation of cleavage crack but also provide excellent combination of strength and toughness in steel. The effect of adding cerium on microstructure and controlling proper cerium-based inclusions in order to improve properties in low-carbon commercial steel (SS400) were investigated. The type of inclusions can be controlled by changing S/O ratio and Ce content. Without Ce modification, MnS is a dominate inclusion. After adding Ce, the stable inclusion phases change from AlCeO3 to Ce2O2S. The optimum amount of cerium, 0.0235 wt.%, lead in proper grain refinement and formation of cerium oxide, oxy-sulfide and sulfide inclusions. Having a high amount of cerium results in increasing the number of inclusions significantly as a result it cannot be effective enough and the inclusions will act like barriers for others. It is found that the inclusions with a size of about 4∼7 μm can serve as heterogeneous nucleation sites for AF formation. Thermodynamic calculations have been applied to predict the inclusion formation in this molten steel as well, which show a good agreement with experimental one.

  18. Possible Frustration Effects on a New Antiferromagnetic Compound Ce6Pd13Zn4 with the Octahedral Ce Sublattice

    Science.gov (United States)

    Matsuoka, Eiichi; Oshima, Akihiro; Sugawara, Hitoshi; Sakurai, Takahiro; Ohta, Hitoshi

    2018-01-01

    Magnetization, specific heat, and electrical resistivity measurements have been performed on polycrystalline samples of a new cubic compound, Ce6Pd13Zn4. This compound exhibits metallic behavior and is classified as a Kondo-lattice system. The trivalent Ce ions are responsible for the antiferromagnetic transition at TN = 3.3 K and the phase transition at T'N = 1.3 K with the formation of superzone gaps. The increase in magnetic susceptibilities below TN and the considerably large value of the specific heat divided by temperature (1.25 J·Ce-mol-1·K-2) imply the existence of non-ordered Ce magnetic moments due to the geometrical frustration on the octahedral Ce sublattice.

  19. Tetragonal zirconia ceramics in Zr O2-Ce O2 system (Ce-TZP): preparation, characterization and mechanical properties

    International Nuclear Information System (INIS)

    Andrade Nono, M.C. de.

    1992-01-01

    This paper describes and discusses the results achieved in a study about Ce-TZP ceramics prepared from conventional powder mixtures of Zr O 2 and Ce O 2 (with composition in the range of 8 to 16 mol% Ce O 2 ). Physical and chemical characteristics were related with the powder compaction behavior and with the sintering state. The sintered ceramics showed a level of high porosity (≅ 4%), mainly due to the fairly adequate powder characteristics and compaction. The crystalline phases were analysed from X-rays diffraction data and showed that these ceramics can present tetragonal-to-monoclinic stress induced transformation. The bending strength, fracture toughness and Vickers hardness results were influenced by Ce O 2 content microstructure and sintering temperature. These Ce-TZP ceramics showed mechanical strength results comparable to those published in the international literature. (author)

  20. Design of MnO2/CeO2-MnO2hierarchical binary oxides for elemental mercury removal from coal-fired flue gas.

    Science.gov (United States)

    Ma, Yongpeng; Mu, Bailong; Yuan, Dongli; Zhang, Hongzhong; Xu, Haomiao

    2017-07-05

    MnO 2 /CeO 2 -MnO 2 hierarchical binary oxide was synthesized for elemental mercury (Hg 0 ) removal from coal-fired flue gas. CeO 2 in-situ grow on the surface of carbon spheres, and that CeO 2 @CSs acted as precursor for porous MnO 2 /CeO 2 -MnO 2 . XRD, Raman, XPS, FT-IR, and H 2 -TPR were selected for the physical structural and chemical surface analysis. The results indicated that the composite has sufficient surface oxygen and hierarchical porous structure. The Hg 0 removal experiments results indicated that MnO 2 /CeO 2 -MnO 2 exhibited excellent Hg 0 removal performance, with an 89% removal efficiency of total 300min at 150°C under 4% O 2 . MnO 2 was the primary active site for Hg 0 catalytic oxidation. The porous structure was beneficial for gaseous mercury physically adsorption. In addition, CeO 2 enhanced the oxygen capture performance of the composite and the oxidation performance for MnO 2 . Moreover, the effects of O 2 , SO 2 and H 2 O were also tested in this study. O 2 promoted the Hg 0 removal reaction. While SO 2 and H 2 O can poison the MnO 2 active site, resulted in a low Hg 0 removal efficiency. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Surface Reduced CeO2 Nanowires for Direct Conversion of CO2 and Methanol to Dimethyl Carbonate: Catalytic Performance and Role of Oxygen Vacancy

    Directory of Open Access Journals (Sweden)

    Zhongwei Fu

    2018-04-01

    Full Text Available Ultralong 1D CeO2 nanowires were synthesized via an advanced solvothermal method, surface reduced under H2 atmosphere, and first applied in direct synthesis of dimethyl carbonate (DMC from CO2 and CH3OH. The micro morphologies, physical parameters of nanowires were fully investigated by transmission electron microscopy (TEM, X-ray diffraction (XRD, N2 adsorption, X-ray photoelectron spectrum (XPS, and temperature-programmed desorption of ammonia/carbon dioxide (NH3-TPD/CO2-TPD. The effects of surface oxygen vacancy and acidic/alkaline sites on the catalytic activity was explored. After reduction, the acidic/alkaline sites of CeO2 nanowires can be dramatically improved and evidently raised the catalytic performance. CeO2 nanowires reduced at 500 °C (CeO2_NW_500 exhibited notably superior activity with DMC yield of 16.85 mmol gcat−1. Furthermore, kinetic insights of initial rate were carried out and the apparent activation energy barrier of CeO2_NW_500 catalyst was found to be 41.9 kJ/mol, much tiny than that of CeO2_NW catalyst (74.7 KJ/mol.

  2. Effects of strong interactions between Ti and ceria on the structures of Ti/CeO2.

    Science.gov (United States)

    Yao, Xiao-Dan; Zhu, Kong-Jie; Teng, Bo-Tao; Yu, Cao-Ming; Zhang, Yun-Lei; Liu, Ya; Fan, Maohong; Wen, Xiao-Dong

    2016-11-30

    The effects of strong interactions between Ti and ceria on the structures of Ti/CeO 2 (111) are systematically investigated by density functional theory calculation. To our best knowledge, the adsorption energy of a Ti atom at the hollow site of CeO 2 is the highest value (-7.99 eV) reported in the literature compared with those of Au (-0.88--1.26 eV), Ag (-1.42 eV), Cu (-2.69 eV), Pd (-1.75 eV), Pt (-2.62 eV) and Sn (-3.68 eV). It is very interesting to find that Ti adatoms disperse at the hollow site of CeO 2 (111) to form surface TiO x species, instead of aggregating to form Ti metal clusters for the Ti-CeO 2 interactions that are much stronger than those of Ti-Ti ones. Ti adatoms are completely oxidized to Ti 4+ ions if they are monatomically dispersed on the next near hollow sites of CeO 2 (111) (xTi-NN-hollow); while Ti 3+ ions are observed when they locate at the near hollow sites (xTi-N-hollow). Due to the electronic repulsive effects among Ti 3+ ions, the adsorption energies of xTi-N-hollow are slightly weaker than those of xTi-NN-hollow. Simultaneously, the existence of unstable Ti 3+ ions on xTi-N-hollow also leads to the restructuring of xTi-N-hollow by surface O atoms of ceria transferring to the top of Ti 3+ ions, or oxidation by O 2 adsorption and dissociation. Both processes improve the stability of the xTi/CeO 2 system by Ti 3+ oxidation. Correspondingly, surface TiO 2 -like species form. This work sheds light into the structures of metal/CeO 2 catalysts with strong interactions between the metal and the ceria support.

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

    International Nuclear Information System (INIS)

    Dai, Jiahong; Jiang, Bin; Li, Xin; Yang, Qingshan; Dong, Hanwu; Xia, Xiangsheng; Pan, Fusheng

    2015-01-01

    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 4 Ce, Al 11 Ce 3 , Al 3 Ce, Al 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 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 4 Ce, Al 11 Ce 3 , Al 3 Ce, Al 2 Ce and AlCe were formed via the reaction of Al and Ce. The formation of Al 4 Ce as the first kind of IMC was rationalized on the basis of an effective Gibbs free energy model. The activation energy for the growth of the total diffusion reaction layer was 36.6 kJ/mol

  4. A new adsorbent of a Ce ion-implanted metal-organic framework (MIL-96) with high-efficiency Ce utilization for removing fluoride from water.

    Science.gov (United States)

    Yang, Xuan; Deng, Shuangshuang; Peng, Fumin; Luo, Tao

    2017-02-14

    A novel Ce(iii) ion-implanted aluminum-trimesic metal-organic framework (Ce-MIL-96) was synthesized for the first time via alcohol-solvent incipient wetness impregnation. Compared to previously reported Ce-contained adsorbents, the fluoride adsorption performance of the new ion-implanted metal-organic framework demonstrated much higher adsorption capacity and more efficient regeneration of Ce. In a wide pH range of 3 to 10, Ce-MIL-96 maintained constant adsorption performance for fluoride, and the residual Ce and Al in the treated solution were below the safe limits in drinking water. The maximum adsorption capacity of Ce-MIL-96 was 38.65 mg g -1 at 298 K. Excluding the contribution of MIL-96, the maximum adsorption capacity of Ce ions was 269.75 mg g -1 , which demonstrated that the service efficiency of cerium in Ce-MIL-96 is about 6 times that in Ce 2 O 3 , nearly 10 times that in Ce-mZrp, and double that in Mn-Ce oxides. There was no significant influence on fluoride removal by Ce-MIL-96 due to the presence of chloride, nitrate, sulfate, bicarbonate or phosphate. Moreover, the adsorption capacity of Ce-MIL-96 remained at more than 70% after nine cycles of adsorption-desorption. Due to this excellent adsorption performance and its regeneration properties, Ce-MIL-96 is a promising adsorbent for the removal of fluoride from groundwater.

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

    Directory of Open Access Journals (Sweden)

    Suman eGhosal

    2014-07-01

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

  6. Unraveling the oxygen vacancy structures at the reduced Ce O2(111 ) surface

    Science.gov (United States)

    Han, Zhong-Kang; Yang, Yi-Zhou; Zhu, Beien; Ganduglia-Pirovano, M. Verónica; Gao, Yi

    2018-03-01

    Oxygen vacancies at ceria (Ce O2 ) surfaces play an essential role in catalytic applications. However, during the past decade, the near-surface vacancy structures at Ce O2(111 ) have been questioned due to the contradictory results from experiments and theoretical simulations. Whether surface vacancies agglomerate, and which is the most stable vacancy structure for varying vacancy concentration and temperature, are being heatedly debated. By combining density functional theory calculations and Monte Carlo simulations, we proposed a unified model to explain all conflicting experimental observations and theoretical results. We find a novel trimeric vacancy structure which is more stable than any other one previously reported, which perfectly reproduces the characteristics of the double linear surface oxygen vacancy clusters observed by STM. Monte Carlo simulations show that at low temperature and low vacancy concentrations, vacancies prefer subsurface sites with a local (2 × 2) ordering, whereas mostly linear surface vacancy clusters do form with increased temperature and degree of reduction. These results well explain the disputes about the stable vacancy structure and surface vacancy clustering at Ce O2(111 ) , and provide a foundation for the understanding of the redox and catalytic chemistry of metal oxides.

  7. Negative Ce anomalies in Mn oxides: The role of Ce4+ mobility during water-mineral interaction

    Science.gov (United States)

    Loges, Anselm; Wagner, Thomas; Barth, Matthias; Bau, Michael; Göb, Susanne; Markl, Gregor

    2012-06-01

    We present one of the very rare natural examples of extremely negative Ce anomalies (up to 4 orders of magnitude) in manganese oxides, caused by higher mobility of Ce4+ compared to REE3+ in an aquatic environment. The young secondary Mn oxides formed together with fluorites and goethites during water-mineral interaction in a hydrothermal fluorite vein. Our findings are in contrast to the oxidative scavenging of Ce, which is commonly observed in Mn oxides. Comparison of REE patterns from modern mine waters with primary and secondary minerals demonstrates that this cannot be solely explained as a source-related feature or by immobilization of Ce, but must at least partially be the result of preferential mobilization of Ce4+ compared to REE3+. We propose that this very unusual behavior is due to strong complexation of Ce4+, most likely by siderophores or similar organic molecules, based on published complex formation constants. The presence of dissolved organic carbon (DOC) even in water samples outflowing at the deepest mine level lends support to this model. Recent experimental studies have also demonstrated that negative Ce anomalies develop in biogenic Mn oxides, but this effect has not yet been reported from a natural environment. Our findings emphasize the relevance of experimental results for natural systems and have considerable implications for the assessment of the mobility of tetravalent actinide elements (especially Pu4+) in earth surface environments or potential high-level permanent repositories.

  8. Vacancy Generation and Oxygen Uptake in Cu-Doped Pr-CeO2 Materials using Neutron and in Situ X-ray Diffraction.

    Science.gov (United States)

    D'Angelo, Anita M; Webster, Nathan A S; Chaffee, Alan L

    2016-12-19

    The oxygen uptake ability of Pr-CeO 2 -based oxygen carriers, catalysts, and solid oxide fuel cells can be attributed to 3+ cation generation and the presence of vacant oxygen sites. Oxygen occupancies of CeO 2 , Pr-CeO 2 , and 5% Cu-doped Pr-CeO 2 were investigated using neutron diffraction and related to the oxygen uptake as determined using thermogravimetric analysis (TGA). The presence of vacant tetrahedral oxygen sites at room temperature did not correspond to low-temperature oxygen uptake. The materials did not uptake oxygen at 420 °C, but oxygen uptake was observed at 600 °C, which indicated that a minimum temperature needs to be met to generate sufficient vacancies/3+ cations. Variations in the lattice parameter as a function of temperature were revealed using in situ X-ray diffraction (XRD). With increasing temperature the lattice parameter increased linearly due to thermal expansion and was followed by an exponential increase at ∼300-400 °C as cations were reduced. Despite segregation of Cu into CuO at high dopant concentration, at 600 °C a higher O 2 uptake was obtained for Ce 0.65 Pr 0.20 Cu 0.15 O 2-δ (120 μmol g -1 ), in comparison to Ce 0.75 Pr 0.2 Cu 0.05 O 2-δ (92 μmol g -1 ), and was higher than that for Ce 0.8 Pr 0.2 O 2-δ (55 μmol g -1 ). Both Pr and Cu introduce vacancies and promote the O 2 uptake of CeO 2 .

  9. 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)

    Aghamohammadi, Sogand; Haghighi, Mohammad; Charghand, Mojtaba

    2014-01-01

    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 NH 3 -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 NH 3 -TPD characterization. The catalyst obtained using morpholine template had the longer lifetime and sustained desired light olefins at higher values. A comprehensive thermodynamic

  10. Crystal structure and magnetic properties of CeTe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Stoewe, K. [Universitaet des Saarlandes, Saarbruecken (Germany). Anorganische und Analytische Chemie und Radiochemie

    2000-07-14

    X-ray diffraction single-crystal structure analysis of CeTe{sub 2} prepared by chemical vapor transport reactions in the presence of mg-traces of iodine revealed superstructure reflections indicating a (2 x 2 x 2) supercell of the basic anti-Fe{sub 2}As type in contrast to the (2 x 2 x 1) supercell found for LaTe{sub 2}. The best interpretation of data set was obtained choosing for CeTe{sub 2} the tetragonal space group P4 with the lattice parameters a=899.75(5) pm and c=1821.2(1) pm (Z=16). The doubling of the c axis compared to LaTe{sub 2} is observed due to different polyanionic structural motifs in the heights z{approx}0 and z{approx}1/2. These are a herringbone pattern of [Te{sub 2}] dumbbell pairs - a topology which is also found in LaTe{sub 2} - isolated [Te{sub 4}] four-membered rings in z{approx}1/2 and additionally [Te{sub 8}] branched four-membered rings in z{approx}1/2. These structural elements give a diffraction pattern, which is all in all to be explained by a statistical superposition of the different elements. Magnetic susceptibility measurements revealed pronounced crystal field effects for the trivalent Ce ions, but apart from that are in agreement with former investigations finding a magnetic transition below T=4 K due to ferrimagnetic ordering. A formerly observed spin sequence of the magnetic moments at different sites A and B of ABBA,A may now be well understood by a classification of the Ce ions into two types with different coordinational environment in the actual structure model. (orig.)

  11. DRIFT study of CuO-CeO₂-TiO₂ mixed oxides for NOx reduction with NH₃ at low temperatures.

    Science.gov (United States)

    Chen, Lei; Si, Zhichun; Wu, Xiaodong; Weng, Duan

    2014-06-11

    A CuO-CeO2-TiO2 catalyst for selective catalytic reduction of NOx with NH3 (NH3-SCR) at low temperatures was prepared by a sol-gel method and characterized by X-ray diffraction, Brunner-Emmett-Teller surface area, ultraviolet-visible spectroscopy, H2 temperature-programmed reduction, scanning electron microscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). The CuO-CeO2-TiO2 ternary oxide catalyst shows excellent NH3-SCR activity in a low-temperature range of 150-250 °C. Lewis acid sites generated from Cu(2+) are the main active sites for ammonia activation at low temperature, which is crucial for low temperature NH3-SCR activity. The introduction of ceria results in increased reducibility of CuO species and strong interactions between CuO particles with the matrix. The interactions between copper, cerium and titanium oxides lead to high dispersion of metal oxides with increased active oxygen and enhanced catalyst acidity. Homogeneously mixed metal oxides facilitate the "fast SCR" reaction among Cu(2+)-NO, nitrate (coordinated on cerium sites) and ammonia (on titanium sites) on the CuO-CeO2-TiO2 catalyst at low temperatures.

  12. CE-MS fingerprinting of Laurencia complex algae (Rhodophyta).

    Science.gov (United States)

    Machín-Sánchez, María; Asensio-Ramos, María; Hernández-Borges, Javier; Gil-Rodríguez, María Candelaria

    2014-03-01

    The use of CE-ESI-MS has been considered as a new chemical strategy for the possible discernment of genera and species of the Laurencia complex. After the selection of the CE-MS and the extraction conditions, a total of 28 specimens of the complex, including different species of four genera (Laurencia, Laurenciella, Palisada, and Osmundea) collected from five intertidal locations on the Island of Tenerife (Canary Islands, Spain) were analyzed. CE-MS fingerprints revealed that CE-MS can be used as a useful tool for these studies in order to assess similarities and differences between them and that it constitutes an important starting point for further studies in the field. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Performance evaluation of LaBr3: Ce scintillator

    International Nuclear Information System (INIS)

    Xie Ming; Lin Li; Liu Shihao; Xiao Peng; Xie Qingguo

    2012-01-01

    The cerium doped lanthanum bromide crystal (LaBr 3 : 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 LaBr 3 : Ce attractive substantial interest to use in the radiation detection. The energy resolution were investigated with Φ25 × 25 mm LaBr 3 : Ce coupled to a Hamamatsu R8900 photomultiplier tube. Energy resolution of 3.6% (FWHM) have been achieved for 511 keV photons ( 18 F 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 LaBr 3 : Ce and imply its enormous potentiality in the radiation detectors of gamma-ray spectroscopy and PET. (authors)

  14. Temperature-independent photoluminescence response in ZnO:Ce ...

    Indian Academy of Sciences (India)

    2017-12-06

    Ce3+ nanophosphors prepared by combustion method and solid-state reaction method is presented in this study. The powder XRD exhibits hexagonal wurtzite phase and crystallite size falls in the nanometre range. The optical ...

  15. Uued IT-mõtted CeBITilt / Kai Simson

    Index Scriptorium Estoniae

    Simson, Kai

    2006-01-01

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

  16. Hydrogen-bridge Si(μ-H)3CeH and inserted H3SiCeH molecules: Matrix infrared spectra and DFT calculations for reaction products of silane with Ce atoms

    Science.gov (United States)

    Xu, Bing; Shi, Peipei; Huang, Tengfei; Wang, Xuefeng

    2017-10-01

    Reactions of laser-ablated cerium atoms with silane were investigated by matrix isolation infrared spectroscopy and theoretical calculations. The reaction products, Si(μ-H)3CeH, H3SiCeH, H2Si(μ-H)CeH and HSi(μ-H)2CeH were identified on the basis of the SiD4 isotopic substitutions and DFT frequency calculations. In the solid argon or krypton matrix, the inserted H3SiCeH molecule was observed as initial product on deposition, which rearranged to hydrogen bridge species Si(μ-H)3CeH on follow-up annealing through H2Si(μ-H)CeH and HSi(μ-H)2CeH species. The Sisbnd Hsbnd Ce hydrogen bridge was investigated by NBO and ELF analysis. Calculation suggested that in Si(μ-H)3CeH molecule Ce atom donated one electron to Si atom, resulting in electron-rich SiH3 subunit, which was confirmed by ESP and AIM analysis. The increased basicity of Sisbnd H bond facilitates the formation of hydrogen bridge bond between Si and Ce. For comparison only insertion H3CCeH structure was obtained from the reaction of Ce atoms with CH4.

  17. Seamless Ligation Cloning Extract (SLiCE) Cloning Method

    OpenAIRE

    Zhang, Yongwei; Werling, Uwe; Edelmann, Winfried

    2014-01-01

    SLiCE (Seamless Ligation Cloning Extract) is a novel cloning method that utilizes easy to generate bacterial cell extracts to assemble multiple DNA fragments into recombinant DNA molecules in a single in vitro recombination reaction. SLiCE overcomes the sequence limitations of traditional cloning methods, facilitates seamless cloning by recombining short end homologies (15–52 bp) with or without flanking heterologous sequences and provides an effective strategy for directional subcloning of D...

  18. Description and Application of the CE-SE Scheme

    Directory of Open Access Journals (Sweden)

    Martin KOSÍK

    2010-12-01

    Full Text Available The CE-SE scheme is new numerical methodology for conservation laws. It was developed by Dr.Chang of NASA Glenn Research Center and his collaborators. The 1D and 2D variant of CE-SE scheme for scalar convection and for Euler equations for incompressible flows is described. The CESE scheme is compared with classical schemes in 1D. The solution to inviscid incompressible flow in GAMM channel in 2D is presented.

  19. Dissolved cerium contributes to uptake of Ce in the presence of differently sized CeO2-nanoparticles by three crop plants.

    Science.gov (United States)

    Schwabe, Franziska; Tanner, Simon; Schulin, Rainer; Rotzetter, Aline; Stark, Wendelin; von Quadt, Albrecht; Nowack, Bernd

    2015-03-01

    We investigated the uptake of cerium (Ce) dioxide nanoparticles (NPs) by hydroponically grown wheat, pumpkin and sunflower plants. The presence of plant roots in nutrient solution led to a substantial increase in the dissolution of CeO2-NP compared to plant-free medium. Experiments with Zr/CeOx-NP revealed that Ce was not only taken up in the form of NPs, but simultaneously to a significant degree also as dissolved Ce(iii) ions, which then re-precipitated in the form of CeO2-NPs inside the leaves. The contribution of dissolved Ce uptake was particularly large for particles smaller than 10 nm due to their higher dissolution rate. Our data also indicate that the translocation of Ce resulting from NP-root-exposure is species dependent. When Ce was supplied as dissolved ions, sunflower had the highest capacity of Ce-ion accumulation inside the leaves, while there was no significant difference between pumpkin and wheat. We found no Ce translocation from roots into shoots when only NPs bigger than 20 nm were applied. This study highlights that plant root activity can have a significant impact on the dissolution of CeO2-NPs in soil solution and that uptake of dissolved Ce(iii) followed by re-precipitation needs to be considered as an important pathway in studies of CeO2-NP uptake by plants.

  20. Growth and Characterization of Ce- Substituted Nd2Fe1411B Single Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Susner, M. A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Conner, B. S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Saparov, B. I. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; McGuire, M. A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Crumlin, E. J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source; Veith, G. M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source; Cao, H. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division; Shanavas, K. V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Parker, D. S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Chakoumakos, B. C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division; Sales, B. C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division

    2015-08-31

    Single crystals of (Nd1-xCex)2Fe14B are grown out of Fe-(Nd,Ce) flux. Chemical and structural analysis of the crystals indicates that (Nd1-xCex)2Fe14B forms a solid solution until at least x = 0.38 with a Vegard-like variation of the lattice constants with x. Refinements of single crystal neutron diffraction data indicate that Ce has a slight site preference (7:3) for the 4g rare earth site over the 4f site. Furthermore, magnetization measurements show that for x = 0.38 the saturation magnetization at 400 K, a temperature important to applications, falls from 29.8 for the parent Nd2Fe14B to 27.6 μB/f.u., the anisotropy field decreases from 5.5 T to 4.7 T, and the Curie temperature decreases from 586 to 543 K. First principles calculations carried out within density functional theory are used to explain the decrease in magnetic properties due to Ce substitution. Although the presence of the lower-cost and more abundant Ce slightly affects these important magnetic characteristics, this decrease is not large enough to affect a multitude of applications. Ce-substituted Nd2Fe14B is therefore a potential high-performance permanent magnet material with substantially reduced Nd content.

  1. Crystal structure and anisotropic magnetic properties of new ferromagnetic Kondo lattice compound Ce(Cu,Al,Si)2

    Science.gov (United States)

    Maurya, A.; Thamizhavel, A.; Dhar, S. K.; Provino, A.; Pani, M.; Costa, G. A.

    2017-03-01

    Single crystals of the new compound CeCu0.18Al0.24Si1.58 have been grown by high-temperature solution growth method using a eutectic Al-Si mixture as flux. This compound is derived from the binary CeSi2 (tetragonal α-ThSi2-type, Pearson symbol tI12, space group I41/amd) obtained by partial substitution of Si by Cu and Al atoms but showing full occupation of the Si crystal site (8e). While CeSi2 is a well-known valence-fluctuating paramagnetic compound, the CeCu0.18Al0.24Si1.58 phase orders ferromagnetically at TC=9.3 K. At low temperatures the easy-axis of magnetization is along the a-axis, which re-orients itself along the c-axis above 30 K. The presence of hysteresis in the magnetization curve, negative temperature coefficient of resistivity at high temperatures, reduced jump in the heat capacity and a relatively lower entropy released up to the ordering temperature, and enhanced Sommerfeld coefficient (≈100 mJ/mol K2) show that CeCu0.18Al0.24Si1.58 is a Kondo lattice ferromagnetic, moderate heavy fermion compound. Analysis of the high temperature heat capacity data in the paramagnetic region lets us infer that the crystal electric field split doublet levels are located at 178 and 357 K, respectively, and Kondo temperature (8.4 K) is of the order of TC in CeCu0.18Al0.24Si1.58.

  2. [Study on deactivation of Cu/Al-Ce-PILC in the selective catalytic reduction of NO by propylene].

    Science.gov (United States)

    Lin, Qi-Chun; Hao, Ji-Ming; Li, Jun-Hua; Fu, Li-Xin; Lin, Wei-Ming

    2007-03-01

    New pillared clay catalysts were studied for NO removal by hydrocarbon in the presence of oxygen. The purpose of this work is to study the deactivation of Cu/Al-Ce-PILC in the SCR of NO. Montmorillonite was pillared by multi oligomeric hydroxyl cation to synthesize Al-Ce-PILC and treated by (NH4) 2SO4, then it was used as catalyst support. Cu/Al-Ce-PILC catalyst was prepared by impregnation and applied to the SCR of NO by C3 H6. The NO conversion to N2 reached its maximum of 56% at 350 degrees C and decreased to 22% at 700 degrees C. To study the deactivation of Cu/Al-Ce-PILC in the SCR of NO at high temperature, the fresh and post-reaction catalysts were characterized by XPS, TPR, TGA, Py-IR and DSC. The results showed that only Cu+ species existed on the fresh catalyst pretreated in hydrogen, while another species CuO was detected on the post-reaction catalyst. The loss of structural hydroxyl and SO4(2-) on Al-Ce-PILC weakened the surface acidity of the catalyst at high reaction temperature. Furthermore, the coke deposition on the catalyst covered part of the active sites and blocked the pores of the catalyst. The deactivation of Cu/Al-Ce-PILC may be due to the combined effects of CuO formation, the decrease on acidity and the coke deposition, which facilitated propylene combustion and inhibited NO reduction.

  3. Interfacial interactions of semiconductor with graphene and reduced graphene oxide: CeO2 as a case study.

    Science.gov (United States)

    Xu, Liang; Huang, Wei-Qing; Wang, Ling-Ling; Huang, Gui-Fang

    2014-11-26

    The pursuit of superb building blocks of light harvesting systems has stimulated increasing efforts to develop graphene (GR)-based semiconductor composites for solar cells and photocatalysts. One critical issue for GR-based composites is understanding the interaction between their components, a problem that remains unresolved after intense experimental investigation. Here, we use cerium dioxide (CeO2) as a model semiconductor to systematically explore the interaction of semiconductor with GR and reduced graphene oxide (RGO) with large-scale ab initio calculations. The amount of charge transferred at the interfaces increases with the concentration of O atoms, demonstrating that the interaction between CeO2 and RGO is much stronger than that between CeO2 and GR due to the decrease of the average equilibrium distance between the interfaces. The stronger interaction between semiconductor and RGO is expected to be general, as evidenced by the results of two paradigms of TiO2 and Ag3PO4 coupled with RGO. The interfacial interaction can tune the band structure: the CeO2(111)/GR interface is a type-I heterojunction, while a type-II staggered band alignment exists between the CeO2(111) surface and RGO. The smaller band gap, type-II heterojunction, and negatively charged O atoms on the RGO as active sites are responsible for the enhanced photoactivity of CeO2/RGO composite. These findings can rationalize the available experimental reports and enrich our understanding of the interaction of GR-based composites for developing high-performance photocatalysts and solar cells.

  4. Crystal structure and anisotropic magnetic properties of new ferromagnetic Kondo lattice compound Ce(Cu,Al,Si){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, A.; Thamizhavel, A.; Dhar, S.K. [Department of Condensed Matter Physics & Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005 (India); Provino, A.; Pani, M.; Costa, G.A. [Department of Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova (Italy); Institute SPIN-CNR, Corso Perrone 24, 16152 Genova (Italy)

    2017-03-15

    Single crystals of the new compound CeCu{sub 0.18}Al{sub 0.24}Si{sub 1.58} have been grown by high-temperature solution growth method using a eutectic Al-Si mixture as flux. This compound is derived from the binary CeSi{sub 2} (tetragonal α-ThSi{sub 2}-type, Pearson symbol tI12, space group I4{sub 1}/amd) obtained by partial substitution of Si by Cu and Al atoms but showing full occupation of the Si crystal site (8e). While CeSi{sub 2} is a well-known valence-fluctuating paramagnetic compound, the CeCu{sub 0.18}Al{sub 0.24}Si{sub 1.58} phase orders ferromagnetically at T{sub C}=9.3 K. At low temperatures the easy-axis of magnetization is along the a-axis, which re-orients itself along the c-axis above 30 K. The presence of hysteresis in the magnetization curve, negative temperature coefficient of resistivity at high temperatures, reduced jump in the heat capacity and a relatively lower entropy released up to the ordering temperature, and enhanced Sommerfeld coefficient (≈100 mJ/mol K{sup 2}) show that CeCu{sub 0.18}Al{sub 0.24}Si{sub 1.58} is a Kondo lattice ferromagnetic, moderate heavy fermion compound. Analysis of the high temperature heat capacity data in the paramagnetic region lets us infer that the crystal electric field split doublet levels are located at 178 and 357 K, respectively, and Kondo temperature (8.4 K) is of the order of T{sub C} in CeCu{sub 0.18}Al{sub 0.24}Si{sub 1.58}.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-12-31

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

  6. Electronic and crystallographic properties of the system CeY2Ni9Dx (0-bar x-bar 8.7) measured by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Latroche, M.; Paul-Boncour, V.; Percheron-Guegan, A.

    2005-01-01

    The electronic and crystallographic properties of CeY 2 Ni 9 D x (0-bar x-bar 8.7D/f.u.) have been investigated by X-ray absorption spectroscopy (XAS). The PuNi 3 -type structure (space group R3-bar m) is described as a stacking of RM 2 and RM 5 units (R: Y, Ce; M: Ni). Hydrogen occupies the RM 2 units only. The Ce-L III and Ni-K edges have been measured by XAS as a function of hydrogen uptake. A heterogeneous mixed valence state is reported for Ce in the hydride and related to differences in deuterium site occupancies. Huge anisotropic volume expansion is observed and is related to hydrogen absorption and valence change of Ce

  7. Optical and scintillation properties of Ce-doped LuLiF{sub 4} with different Ce concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Yanagida, Takayuki, E-mail: yanagida@lsse.kyutech.ac.jp [Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu, Fukuoka 808-0196 (Japan); Fujimoto, Yutaka [Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu, Fukuoka 808-0196 (Japan); Fukuda, Kentaro [Tokuyama Corporation, Shibuya 3-chome, Shibuya-ku, Tokyo 150-8383 Japan (Japan); Chani, Valery [Tohoku Univ., 2-1-1 Katahira, Sendai 980-8577 (Japan)

    2013-11-21

    The crystals of 0.1, 0.5, and 1 mol% Ce-doped LuLiF{sub 4} (Ce:LLF) grown by the micro-pulling down (μ-PD) method were examined for their optical and scintillation properties. Ce:LLF crystals had ∼80% transparency at wavelengths longer than 300 nm. In photoluminescence spectra, they demonstrated intense emission peaks at 310 and 330 nm with the quantum yield of 60–90%. Ce{sup 3+} 5d–4f emission peaks were also detected at similar wavelengths of 310 and 330 nm in the radioluminescence spectra obtained under X-ray excitation. According to pulse height spectra recorded under γ-ray irradiation, the absolute light yield of Ce 0.1, 0.5, and 1% were 3600±400, 3000±300, and 1700±200 ph/MeV, respectively. Decay time kinetics was also inspected using a pulse X-ray equipped streak camera system. The decay time components of Ce:LLF were ∼70 ns and ∼1 μs for all the samples.

  8. Optical and scintillation properties of Ce-doped LuLiF4 with different Ce concentrations

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Fujimoto, Yutaka; Fukuda, Kentaro; Chani, Valery

    2013-01-01

    The crystals of 0.1, 0.5, and 1 mol% Ce-doped LuLiF 4 (Ce:LLF) grown by the micro-pulling down (μ-PD) method were examined for their optical and scintillation properties. Ce:LLF crystals had ∼80% transparency at wavelengths longer than 300 nm. In photoluminescence spectra, they demonstrated intense emission peaks at 310 and 330 nm with the quantum yield of 60–90%. Ce 3+ 5d–4f emission peaks were also detected at similar wavelengths of 310 and 330 nm in the radioluminescence spectra obtained under X-ray excitation. According to pulse height spectra recorded under γ-ray irradiation, the absolute light yield of Ce 0.1, 0.5, and 1% were 3600±400, 3000±300, and 1700±200 ph/MeV, respectively. Decay time kinetics was also inspected using a pulse X-ray equipped streak camera system. The decay time components of Ce:LLF were ∼70 ns and ∼1 μs for all the samples

  9. Influence of Ce-H bonding on the physical properties of the hydrides CeCoSiH1.0 and CeCoGeH1.0

    International Nuclear Information System (INIS)

    Chevalier, B; Matar, S F; Menetrier, M; Marcos, J Sanchez; Fernandez, J Rodriguez

    2006-01-01

    The hydrides CeCoSiH 1.0 and CeCoGeH 1.0 which crystallize like the parent antiferromagnetic compounds CeCoSi and CeCoGe in the tetragonal CeFeSi-type structure, have been investigated by specific heat and thermoelectric power measurements and 1 H nuclear magnetic resonance (NMR). CeCoSiH 1.0 is an intermediate valence compound whereas CeCoGeH 1.0 can be considered as a nearly trivalent cerium compound. This behaviour is corroborated by the occurrence of a slight broadening of the 1 H NMR signal in the sequence CeCoSiH 1.0 → CeCoGeH 1.0 . The band structure calculations performed on these hydrides reveal the existence of strong bonding Ce-H interaction, found to be larger in CeCoSiH 1.0 than in CeCoGeH 1.0

  10. Effect of yttrium on electron–phonon coupling strength of 5d state of Ce3+ ion in LYSO:Ce crystals

    International Nuclear Information System (INIS)

    Ding, Dongzhou; Liu, Bo; Wu, Yuntao; Yang, Jianhua; Ren, Guohao; Chen, Junfeng

    2014-01-01

    This paper aims at an improved understanding of luminescence properties of (Lu 1−x Y x ) 2 SiO 5 :Ce (x=0 at%, 26 at%, 45 at%, 66 at% and 100 at%). Photoluminescence emission and excitation spectra as well as Raman spectra of (Lu 1−x Y x ) 2 SiO 5 :Ce were investigated as a function of yttrium (shortened as Y) content in it. Obtained Huang–Rhys factor S indicates that the coupling between Ce1 (7-oxygen-coordinated), Ce2 (6-oxygen-coordinated) and LYSO lattice is intermediate and strong, respectively. Besides, it was found that: with the increase of Y content, crystal field strength around Ce1 and Ce2 decreases, Stokes shift of Ce1 and Ce2 presents an increase trend, and S of Ce2 tends to decrease. These phenomena were explained by geometrical influence of Y 3+ /Lu 3+ on the crystal field splitting of the 5d levels of Ce 3+ and coupling strength. With the increase of Y content, the evolution of S and coupling energy ħω of Ce1 present a slight increase and decrease trend respectively, while S and coupling energy ħω of Ce2 present an obvious decrease and increase trend, respectively. - Highlights: • Crystal field strength around Ce1 decreases with increase of Y content in LYSO:Ce. • A diagram of Huang–Rhys factor S against Y content in LYSO:Ce was constructed. • A diagram of coupling energy ħω against Y content in LYSO:Ce was constructed. • A diagram of Stokes shift against Y content in LYSO:Ce was constructed

  11. Ce-doped nanoparticles of TiO2: Rutile-to-brookite phase transition and evolution of Ce local-structure studied with XRD and XANES

    International Nuclear Information System (INIS)

    Kityakarn, Sutasinee; Worayingyong, Attera; Suramitr, Anwaraporn; Smith, M.F.

    2013-01-01

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

  12. Investigating the capability of ToF-SIMS to determine the oxidation state of Ce

    Science.gov (United States)

    Seed Ahmed, H. A. A.; Swart, H. C.; Kroon, R. E.

    2018-04-01

    The capability of time of flight secondary ion mass spectrometry (ToF-SIMS) to determine the oxidation state of Ce ions doped in a phosphor was investigated. Two samples of SiO2:Ce (4 mol%) with known Ce3+/Ce4+ relative concentrations were subjected to ToF-SIMS measurements. The spectra were very similar and no significant differences in the relative peak intensities were observed that would readily allow one to distinguish Ce3+ from Ce4+. Although ToF-SIMS was therefore not useful to distinguish the charge state of Ce ions doped in this phosphor material, the idea in principle was also tested on two other samples, namely CeF3 and CeF4 These contain Ce as part of the host (i.e. much higher concentration) and are fluorides, which is significant because ToF-SIMS has previously been reported to be able to distinguish Eu2+ from Eu3+ in Eu doped Sr5(PO4)3F phosphor. The spectrum of CeF4 contained a small peak related to Ce4+ which was not observed in the CeF3 spectrum, yet the peak related to the Ce3+ ions was found to be much more intense in the spectrum of CeF4 than CeF3, showing that the ToF-SIMS signals cannot be directly interpreted as retaining the charge state of the ions in the original material. Nevertheless, the significant differences in the Ce-related peaks in the ToF-SIMS spectra from CeF3 and CeF4 show that the charge state of Ce may be distinguished. This study shows that while in principle ToF-SIMS may be used to distinguish the charge state of Ce ions, this depends on the sample and it would not be easy to interpret the spectra without a standard or reference.

  13. Photocatalytic activity of Ce-modified SBA-15 for the degradation of ...

    Indian Academy of Sciences (India)

    CeO2 or CeO2-based materials have also been found to be very important under environmental protection materials family. In particular, supported CeO2 and CeO2-based mixed oxides are effective catalysts for the ... made slurry in ethanol containing aluminum isopropoxide for 8 h at room temperature. The filtered ...

  14. Adsorption mechanism and kinetics of azo dye chemicals on oxide nanotubes: a case study using porous CeO2 nanotubes

    Science.gov (United States)

    Wu, Junshu; Wang, Jinshu; Du, Yucheng; Li, Hongyi; Jia, Xinjian

    2016-07-01

    Metal oxide nanotubes are believed to be promising materials with adsorption functionality for water purification due to their synergistic effect of the overall microscale morphology for easy separation and nanoscale surface characters providing enough surface active absorption sites. This work shows the synthesis of uniform hierarchical porous CeO2 nanotubes via nanowire-directed templating method and describes the adsorption behavior of CeO2 nanotubes for a typical azo dye Congo red which has resistance to oxidation and decoloration in natural conditions. Fourier transform infrared spectroscopy spectra provided the evidence that Congo red was successfully coated on the surface of CeO2 nanotubes by both bidentate-type bridge link of Ce4+ cations from sulfonate SO3 - groups and the electrostatic attraction between the protonated surface generated by oxygen vacancies and dissociated sulfonate groups. The adsorption kinetic data fitted well to the pseudo-second-order kinetic equation, whereas the Langmuir isotherm equation exhibited better correlation with the experimental data. The calculated maximum adsorption capacity from the isothermal model was 362.32 mg/g. In addition, the prepared CeO2 nanotubes exhibited good recyclability and reusability as highly efficient adsorbents for Congo red removal after regeneration. These favorable performances enable the obtained CeO2 nanotubes to be promising materials for dye removal from aqueous solution.

  15. Sorption of Fe3+ , Co2+ , Ce3+ , Cs+ and Ba2+ in zeolite X

    International Nuclear Information System (INIS)

    Martinez M, V.

    1994-01-01

    The sorption behavior of Fe 3+ , Co 2+ , Ce 3+ , Cs + , and Ba 2+ in aqueous solutions, was studied in presence of zeolite X. Solutions of Fe(NO 3 ) 3 . 9 H 2 O, Co(NO 3 ) 2 . 6 H 2 O, Ce(NO 3 ) 3 . 6 H 2 O, Cs NO 3 and Ba(NO 3 ) 2 were labelled with the respectively radioactive isotopes Fe 59 , Co 60 , Cs 134 , Ba 139 and Ce 141 . 20 ml. of each solution was left in contact with 200 mg. of zeolite for different periods. Later the zeolites were separated by centrifugation from the aqueous solutions and the radioactivity of the aqueous phases was measured with a NaI(Tl) solid-state well detector coupled to a single-channel Picker analyzer or with a Gel hyper pure solid-state detector coupled to a 2048 channel pulse height analyzer. When Cs + in the aqueous solutions was left in contact with zeolite X it was found that it does not occupy all cationic sites in the zeolite due to the ionic radium effect. A similar behavior was found for the divalent ions. In all cases, when the pH was not controlled, the zeolite lost part of its crystallinity and when the divalent ions were exchanged again by Na + , the zeolite recovered completely its crystallinity. During the sorption, the ionic radius, and the charge are important parameters as well as the pH. When the pH of the solution was adjusted between 6.5 - 7.0 the crystallinity was maintained in some cases. For Fe 3+ the crystallinity after the ion exchange was 94 % and when the pH was not adjusted the crystallinity was completely lost. It was found as well that the zeolite X induces the formation of H 3 O + which competes with the cations for the sites in the zeolite. (Author)

  16. Synergy of CuO and CeO2 combination for mercury oxidation under low-temperature selective catalytic reduction atmosphere

    KAUST Repository

    Li, Hailong

    2016-07-19

    Synergy for low temperature Hg0 oxidation under selective catalytic reduction (SCR) atmosphere was achieved when copper oxides and cerium oxides were combined in a CuO-CeO2/TiO2 (CuCeTi) catalyst. Hg0 oxidation efficiency as high as 99.0% was observed on the CuCeTi catalyst at 200 °C, even the gas hourly space velocity was extremely high. To analyze the synergistic effect, comparisons of catalyst performance in the presence of different SCR reaction gases were systematically conducted over CuO/TiO2 (CuTi), CeO2/TiO2 (CeTi) and CuCeTi catalysts prepared by sol-gel method. The interactions between copper oxides and cerium oxides in CuCeTi catalyst yielded more surface chemisorbed oxygen, and facilitated the conversion of gas-phase O2 to surface oxygen, which are favorable for Hg0 oxidation. Copper oxides in the combination interacted with NO forming more chemisorbed oxygen for Hg0 oxidation in the absence of gas-phase O2. Cerium oxides in the combination promoted Hg0 oxidation through enhancing the transformations of NO to NO2. In the absence of NO, NH3 exhibited no inhibitive effect on Hg0 oxidation, because enough Lewis acid sites due to the combination of copper oxides and cerium oxides scavenged the competitive adsorption between NH3 and Hg0. In the presence of NO, although NH3 lowered Hg0 oxidation rate through inducing reduction of oxidized mercury, complete recovery of Hg0 oxidation activity over the CuCeTi catalyst was quickly achieved after cutting off NH3. This study revealed the synergistic effect of the combination of copper oxides and cerium oxides on Hg0 oxidation, and explored the involved mechanisms. Such knowledge would help obtaining maximum Hg0 oxidation co-benefit from SCR units in coal-fired power plants.

  17. Synthesis, characterization and magnetic properties of NiFe{sub 2−x}Ce{sub x}O{sub 4} nanoribbons by electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jianan; Jing, Panpan; Zhang, Xinlei; Cao, Derang; Wei, Jinwu; Pan, Lining [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Liu, Zhenlin [Analysis and researching center of Gansu province, Lanzhou 730000 (China); Wang, Jianbo [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Key Laboratory for Special Function Materials and Structural Design of the Ministry of the Education, Lanzhou University, Lanzhou 730000 (China); Liu, Qingfang, E-mail: liuqf@lzu.edu.cn [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2017-03-01

    NiFe{sub 2−x}Ce{sub x}O{sub 4} (x = 0–0.03) nanoribbons have been successfully fabricated using electrospinning technique and followed by calcining in air at 500 °C. The crystalline, morphologies and compositions of NiFe{sub 2−x}Ce{sub x}O{sub 4} nanoribbons are characterized by X-ray diffraction, selected area electron diffraction, transmission electron microscope, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy (EDX). The results show that the components, mean crystallite sizes and morphologies change along with the content of Ce{sup 3+}. A formation mechanism of NiFe{sub 2-x}Ce{sub x}O{sub 4} nanoribbons is proposed. The magnetic hysteresis loops of NiFe{sub 2−x}Ce{sub x}O{sub 4} nanoribbons reveals that the coercivity changes from 165 Oe to 64 Oe and saturation magnetizations change from 40.97 emu/g to 25.05 emu/g at room temperature. Morevover, the Mössbauer spectra of {sup 57}Fe in NiFe{sub 2−x}Ce{sub x}O{sub 4} nanoribbons is discussed in detail. It is believed that this work will play important role in magnetic application with the advantage of excellent magnetic properties, efficient functionalization and relatively low cost. - Highlights: • The NiFe{sub 2−x}Ce{sub x}O{sub 4} nanoribbons have been fabricated using electrospinning technique. • Ce{sup 3+} ions occupy B sites by replacing Fe{sup 3+} ions. • The coercivity changes from 165 Oe to 64 Oe. • The saturation magnetizations change from 40.97 emu/g to 25.05 emu/g.

  18. Magnetic Structure of the Heavy-fermion Compound CeAuSb2 in Zero-field

    Science.gov (United States)

    Marcus, Guy G.; Kim, Dae-Jeong; Lee, Hannoh; Fisk, Zachary; Rodriguez-Rivera, Jose A.; Broholm, Collin L.

    2015-03-01

    We have used neutron diffraction to determine the zero-field magnetic structure of the heavy-fermion compound CeAuSb2. Below TN ~ 6 . 2 K, we observe the development of antiferromagnetic Bragg diffraction consistent with previous transport and magnetization measurements. The intensities observed at 7 magnetic satellite locations indicate the staggered magnetization is predominantly along the c-axis. The maximum moment size is 1 . 15 +/- 0 . 08μB which is large compared with the 0 . 4μB moment in the iso-structural heavy fermion ferromagnet CeAgSb2. This suggests that the antiferromagnetic CeAuSb2 is deeper into a magnetic phase. The spin structure, due mainly to the Ce-4f sites, is described as a transverse polarized spin density wave with an incommensurate component of the wave vector in the basal plane. We will discuss these results and bulk measurements in terms of an ANNNI model and effective near neighbor exchange interactions. The work at IQM was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Material Sciences and Engineering under Grant No. DE-FG02-08ER46544. GGM also acknowledges support from the NSF-GRFP Grant No. DGE-1232825.

  19. Evidence for a second-order phase transition around 350 K in Ce3Rh4Sn13

    Science.gov (United States)

    Kuo, C. N.; Chen, W. T.; Tseng, C. W.; Hsu, C. J.; Huang, R. Y.; Chou, F. C.; Kuo, Y. K.; Lue, C. S.

    2018-03-01

    We report an observation of a phase transition in Ce3Rh4Sn13 with the transition temperature T*≃350 K by means of synchrotron x-ray powder diffraction, specific heat, electrical resistivity, Seebeck coefficient, thermal conductivity, as well as 119Sn nuclear magnetic resonance (NMR) measurements. The phase transition has been characterized by marked features near T* in all measured physical quantities. The lack of thermal hysteresis in the specific heat indicates a second-order phase transition in nature. From the NMR analysis, the change in the transferred hyperfine coupling constant for two tin sites has been resolved. The obtained result has been associated with the reduction in the averaged interatomic distance between Ce and Sn atoms, particularly for the Sn2 atoms. It indicates that the movement of the Sn2 atoms, which deforms the high-temperature structure, shortens the Ce-Sn2 bond length at low temperatures. We therefore provide a concise picture that the observed second-order phase transition at T* of Ce3Rh4Sn13 should be characterized by a structural modulation essentially due to lattice distortions arising from phonon instability.

  20. Ce3 - xMgxCo9 : Transformation of a Pauli Paramagnet into a Strong Permanent Magnet

    Science.gov (United States)

    Lamichhane, Tej N.; Taufour, Valentin; Palasyuk, Andriy; Lin, Qisheng; Bud'ko, Sergey L.; Canfield, Paul C.

    2018-02-01

    We report on the synthesis of single-crystal and polycrystalline samples of Ce3 -xMgxCo9 solid solution (0 ≤x ≲1.4 ) and characterization of their structural and magnetic properties. The crystal structure remains rhombohedral in the whole composition range and Mg partially replaces Ce in the 6 c site of the CeCo3 structure. Ferromagnetism is induced by Mg substitutions starting as low as x =0.18 and reaching a Curie temperature as high as 450 K for x =1.35 . Measurements on single crystals with x =1.34 and TC=440 K indicate an axial magnetic anisotropy with an anisotropy field of 6 T and a magnetization of 6 μB/f .u . at 300 K. Coercicity is observed in the polycrystalline samples consistent with the observed axial magnetic anisotropy. Our discovery of ferromagnetism with large axial magnetic anisotropy induced by substituting a rare-earth element by Mg is a very promising result in the search of inexpensive permanent-magnet materials and suggests that other nonmagnetic phases, similar to CeCo3 , may also conceal nearby ferromagnetic phases.

  1. Structural, optical and EPR studies of NaCe(PO{sub 3}){sub 4} metaphosphate doped with Cr{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Godlewska, P.; Matraszek, A. [Wrocław University of Economics, Faculty of Chemistry and Food Technology, Komandorska 118/120, 53-345 Wrocław (Poland); Kaczmarek, S.M.; Fuks, H.; Skibiński, T. [West Pomeranian University of Technology, Institute of Physics, Al. Piastów 48, 70-311 Szczecin (Poland); Hermanowicz, K.; Ptak, M. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422 Wrocław (Poland); Szczygieł, I. [Wrocław University of Economics, Faculty of Chemistry and Food Technology, Komandorska 118/120, 53-345 Wrocław (Poland); Macalik, L., E-mail: L.Macalik@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422 Wrocław (Poland); Lisiecki, R.; Ryba-Romanowski, W. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422 Wrocław (Poland); Hanuza, J. [Wrocław University of Economics, Faculty of Chemistry and Food Technology, Komandorska 118/120, 53-345 Wrocław (Poland); Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422 Wrocław (Poland)

    2014-02-15

    The undoped and Cr{sup 3+}-doped NaCe(PO{sub 3}){sub 4} metaphosphates were synthesized by the modified Pechini method and obtained as the crystalline powders. They were characterized by means of X-ray diffraction, vibrational and optical spectroscopy to clarify the structure and mechanism of Cr{sup 3+} emission in NaCe(PO{sub 3}){sub 4}. This phosphor crystallizes in the monoclinic P12{sub 1}/n1 structure with an infinite (PO{sub 3}){sub n} chain. The Cr{sup 3+} ions can substitute the C{sub 1} symmetry site occupied by cerium ions. They can also occupy the tunnels formed in the anionic layer. Spectroscopic properties of the Cr{sup 3+} and Ce{sup 3+} ions were discussed in terms of structure of the studied crystalline powders. IR and Raman data confirm the predicted structure and indicate C{sub 1} site symmetry of the Cr{sup 3+} active ions. The Cr{sup 3+} ions appear in the distorted octahedral environment of the weak crystal field. Optical studies were confirmed by EPR results carried out in the temperature range of 4–293 K. In addition, the magnetic measurements were performed up to 305 K. The Cr{sup 3+} ions reveal negligible ferromagnetic interactions while the Ce{sup 3+} ions change their magnetic interactions from slightly antiferromagnetic to significantly ferromagnetic above 20 K. -- Highlights: • NaCe(PO{sub 3}){sub 4}:Cr{sup 3+} crystalline powders were synthesized by the modified Pechini method. • The optical and magnetic properties of the NaCe(PO{sub 3}){sub 4}:Cr{sup 3+} crystalline powders were investigated. • Cr{sup 3+} ions replacing Ce{sup 3+} ions in the unit cell are in the distorted octahedral environment. • Cr{sup 3+} ions reveal ferromagnetic interactions, that strength depends on temperature.

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

    International Nuclear Information System (INIS)

    Gowdy, G.M.; Chrien, R.E.; Chu, Y.Y.

    1981-01-01

    An investigation of the level structure of 146 Ce following the beta decay of the low-spin isomer of 146 La 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 146 Ce 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 146 Ce is more deformed than its isotones with Z greater than or equal to 60, the transition to the well-deformed region can probably more correctly be thought to occur after 146 Ce, between N = 88 and N = 90, as it does for Z greater than or equal to 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

  3. 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.

  4. Effect of Tb3+ concentration on the optical and vibrational properties of YBO3 tri-doped with Eu3+, Ce3+, and Tb3+

    International Nuclear Information System (INIS)

    Sohal, S.; Hassanzadeh, E.; Huang, J. Y.; Nazari, M.; Holtz, M.; Zhang, X.; Chaudhuri, J.; Kuryatkov, V. V.; Hope-Weeks, L. J.

    2014-01-01

    Structural and optical studies are reported of yttrium orthoborate YBO 3 when tri-doped with Eu 3+ , Ce 3+ , and Tb 3+ , focusing on the role of terbium concentration. Incorporation of Tb 3+ affects emission properties for photoluminescence (PL) excited by near ultraviolet light. For constant cerium and europium concentrations, increasing the Tb 3+ results in diminished PL from the Ce 3+ and Tb 3+ color centers. Simultaneously, the PL excitation bands related to both Ce 3+ and Tb 3+ increase in intensity for red emission from the Eu 3+ . Results are consistent with a Ce 3+  → (Tb 3+ ) n  → Eu 3+ energy transfer scheme, where (Tb 3+ ) n denotes a chain incorporating n terbium ions. A high red to orange PL intensity ratio is obtained, ranging from 1.34 to 2.09. Raman vibrational bands show a systematic change, with Tb 3+ concentration, in the B 3 O 9 ring terminal oxygen bending mode coordinated with the yttrium site where dopant ions substitute. The structural changes are interpreted as variations in the local neighborhood of these sites in the YBO 3 :Ce 3+ ,Tb 3+ ,Eu 3+ crystal structure

  5. Luminance behavior of Ce3+ doped ZnS nanostructures.

    Science.gov (United States)

    Shanmugam, N; Cholan, S; Kannadasan, N; Sathishkumar, K; Viruthagiri, G

    2014-01-24

    We report the synthesis and characterization of undoped and various levels of Ce(3+) doped ZnS nanocrystal. The structure and size of the products were studied by X-ray diffraction (XRD). The existence of functional groups was identified by Fourier transform infrared spectrometry (FT-IR). The UV-Visible measurements reveal that the synthesized products are blue shifted when compared with bulk phase of ZnS as a result of quantum confinement effect. The PL studies show an enhancement in the intensity of emission band in the UV region on increased Ce(3+) doping. The morphology of the products was evaluated by Field emission scanning electron microscope (FESEM) and High resolution transmission electron microscopy (FESEM). The presence of Ce(3+) was confirmed by Energy dispersive spectral analysis (EDS). The thermal stability of pure and doped products was analyzed by thermo gravimetric and differential thermal analysis (TG-DTA). Copyright © 2013 Elsevier B.V. All rights reserved.

  6. 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.

  7. Cooperative effects in CeCu2Si2

    International Nuclear Information System (INIS)

    Lang, M.; Modler, R.; Ahlheim, U.; Helfrich, R.; Reinders, P.H.P.; Steglich, F.; Assmus, W.; Sun, W.; Bruls, G.; Weber, D.; Luethi, B.

    1991-01-01

    Heavy-fermion superconductivity and other cooperative effects have been explored by thermal expansion, specific heat and ultrasound measurements on CeCu 2 Si 2 single crystals. Crystals annealed under Cu atmosphere show sharp superconducting transitions at Tc max =0.63 K. At the same temperature the ''as grown'', i.e., non-bulk-superconducting, crystals reveal a pronounced phase-transition anomaly, presumably of structural origin. This new transition is associated with an expansion of the volume upon cooling and gives rise to magnetic correlations. Our results indicate a complex interplay between lattice instability, magnetic phenomena and superconductivity in CeCu 2 Si 2 . (orig.)

  8. Magnetic Phase Transitions of CeSb. I

    DEFF Research Database (Denmark)

    Fischer, Pernille Hertz; Lebech, Bente; Meier, G.

    1978-01-01

    The magnetic ordering of the anomalous antiferromagnet CeSb, which has a NaCl crystal structure, was determined in zero applied magnetic field by means of neutron diffraction investigations of single crystals and powder. Below the Neel temperature TN of (16.1+or-0.1)K, there exist six partially...... 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...

  9. Crystalline field effect and magnetic ordering in the heavy fermion Kondo lattice Ce{sub 6}Pd{sub 12}In{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Falkowski, M. [Highly Correlated Matter Research Group, Physics Department, University of Johannesburg, PO Box 524, Auckland Park 2006 (South Africa); Strydom, A.M., E-mail: amstrydom@uj.ac.za [Highly Correlated Matter Research Group, Physics Department, University of Johannesburg, PO Box 524, Auckland Park 2006 (South Africa); Max Planck Institute for Chemical Physics of Solids, Nöthnitzerstr. 40, Dresden 01187 (Germany)

    2014-11-15

    Highlights: • A new moderate heavy fermion Kondo lattice, Ce{sub 6}Pd{sub 12}In{sub 5}. • Low-temperature antiferromagnetic order in a complex metal alloy. • Competing energy scales produce a field-driven metamagnetic instability. • Ground state formed between ferro-like metamagnetism and antiferromagnetic order. - Abstract: Results of magnetic, specific heat, electric and thermal transport studies carried out on the novel hexagonal-type structure Ce{sub 6}Pd{sub 12}In{sub 5} compound, with a unique site for Ce, two sites for In and four sites for Pd are reported. The compound exhibits long-range order, probably of antiferromagnetic type, below T{sub N}=1.6 K in spite of a moment reducing Kondo effect acting on the magnetic Ce{sup 3+} ions. A strong influence of magnetic field on the low temperature dependencies of susceptibility, specific heat and electrical resistivity is observed. The crystal-electric field effect, CEF, plays an influential role in the ground state of this compound. The CEF parameters have been estimated. Based upon the low-temperature specific heat we observe heavy fermion behavior with the electronic specific heat coefficient that is enhanced to the value of γ=132 mJ/Ce-mol K{sup 2}. In the electrical resistivity, a logarithmic character ρ{sub 4f}(T)∼-lnT is observed that arises from incoherent Kondo scattering. Towards low temperature this behavior evolves into Kondo lattice formation with a coherence temperature T{sub coh}≃5.3 K, before long-range order takes place. We propose that Ce{sub 6}Pd{sub 12}In{sub 5} presents a new case study for competing Kondo and magnetic ordering in a high-symmetry lattice, with CEF and magnetocrystalline anisotropy further impacting upon the cooperative magnetic behavior.

  10. Synthesis and physico-chemical characterization of CeO{sub 2}/ZrO{sub 2}-SO{sub 4}{sup 2-} mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez E, J. M.; Silva R, R.; Garcia A, R. [Instituto Tecnologico de Ciudad Madero, Div. de Estudios de Posgrado e Investigacion, Juventino Rosas y Jesus Urueta s/n, Col. Los Mangos, 89440 Ciudad Madero, Tamaulipas (Mexico); Garcia S, L. A. [IPN, Centro Interdisciplinario de Investigaciones y de Estudios sobre Medio Ambiente y Desarrollo, 30 de Junio No. 1520, Barrio La Laguna Ticoman, 07340 Mexico D. F. (Mexico); Handy, B. E.; Cardenas G, G. [Universidad Autonoma de San Luis Potosi, CIEP, Facultad de Ciencias Quimicas, Av. Dr. Manuel Nava No. 6, Zona Universitaria, 78210 SLP, San Luis Potosi (Mexico); Cueto H, A. [Universidad Autonoma Metropolitana, Unidad Azcapotzalco, Av. San Pablo No. 180, Col. Reynosa Tamaulipas, 02200 Mexico D. F. (Mexico)

    2012-07-01

    Environmentally friendly solid-acid catalysts CeO{sub 2}/ZrO{sub 2}-SO{sub 4}{sup 2-} were prepared by the sol gel method varying CeO{sub 2} content (10, 20 and 30 wt %) and using sulfation in situ, maintaining the sulfate ions amount present in the materials at 20 wt %. ZrO{sub 2} and ZrO{sub 2}-SO{sub 4}{sup 2-} were also prepared for comparison proposes using the same synthesis method. The materials were characterized by X-ray diffraction, nitrogen physisorption, potentiometric titration with n-butylamine, decomposition of 2-propanol and n-pentane isomerization. The specific surface area of ZrO{sub 2}-SO{sub 4}{sup 2-} was high (160 m{sup 2}/g) compared with the unmodified ZrO{sub 2} (80 m{sup 2}/g), however this area decreased with increasing the CeO{sub 2} content (37-100 m{sup 2}/g). There was no significant effect of CeO{sub 2} on the tetragonal structure of ZrO{sub 2}-SO{sub 4}{sup 2-}. The variation of acid sites amount runs parallel to the change of specific surface area. The acid sites amount decreased with increasing cerium oxide content. The decomposition of 2-propanol results fundamentally in the formation of dehydration products such as propylene and diisopropyl ether, both involving acid sites. In addition, a good performance during the n-pentane isomerization was observed for these materials. The selectivity towards isopentane reaches 84% when the Pt/CeO{sub 2}/ZrO{sub 2}-SO{sub 4}{sup 2-} catalyst with the highest CeO{sub 2} content was used. (Author)

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

    Science.gov (United States)

    Isber, S.; Gratens, X.; Charar, S.; Golacki, Z.

    2013-01-01

    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.

  12. Studies of the Ce(III)/Ce(IV) couple in multiphase systems containing a phase transfer reagent: Pt. 2

    International Nuclear Information System (INIS)

    Pletcher, D.; Valdes, E.M.

    1988-01-01

    The oxidation of some toluenes and aromatic hydrocarbons by Ce(IV) in aqueous nitric acid/organic solvent emulsions containing a phase transfer reagent, tributylphosphate or tetrabutylammonium ion are reported. With toluenes, a number of products are formed and the relative yield depends most strongly on substituents; with p-xylene and p-methoxytoluene, reasonable yields of aldehydes were obtained with short reaction times. With anthracene and naphthalene, the reactions are again fast and good yields of quinones are observed. On the basis of these studies it is possible to select conditions for the indirect oxidation of some organic molecules in an emulsion and using Ce(III)/Ce(IV) as the redox mediator. (author)

  13. Novel Ni-Ce-Zr/Al2O3 Cellular Structure for the Oxidative Dehydrogenation of Ethane

    Directory of Open Access Journals (Sweden)

    Juan Pablo Bortolozzi

    2017-11-01

    Full Text Available A novel γ-alumina-supported Ni-Ce-Zr catalyst with cellular structure was developed for oxidative dehydrogenation of ethane (ODHE. First, powdered samples were synthesized to study the effect of both the total metal content and the Ce/Zr ratio on the physicochemical properties and performance of these catalysts. All synthesized powdered samples were highly active and selective for ODHE with a maximum ethylene productivity of 6.94 µmolethylene gact cat−1 s−1. According to the results, cerium addition increased the most reducible nickel species population, which would benefit ethane conversion, whereas zirconium incorporation would enhance ethylene selectivity through the generation of higher amounts of the least reducible nickel species. Therefore, the modification of active site properties by addition of both promoters synergistically increases the productivity of the Ni-based catalysts. The most efficient formulation, in terms of ethylene productivity per active phase amount, contained 15 wt% of the mixed oxide with Ni0.85Ce0.075Zr0.075 composition. This formulation was selected to synthesize a Ni-Ce-Zr/Al2O3 structured body by deposition of the active phase onto a homemade γ-alumina monolith. The structured support was manufactured by extrusion of boehmite-containing dough. The main properties of the Ni0.85Ce0.075Zr0.075 powder were successfully preserved after the shaping procedure. In addition, the catalytic performance of the monolithic sample was comparable in terms of ethylene productivity to that of the powdered counterpart.

  14. Charge transfer and formation of reduced Ce3+ upon adsorption of metal atoms at the ceria (110) surface

    International Nuclear Information System (INIS)

    Nolan, Michael

    2012-01-01

    The modification of cerium dioxide with nanoscale metal clusters is intensely researched for catalysis applications, with gold, silver, and copper having been particularly well studied. The interaction of the metal cluster with ceria is driven principally by a localised interaction between a small number of metal atoms (as small as one) and the surface and understanding the fundamentals of the interaction of metal atoms with ceria surfaces is therefore of great interest. Much attention has been focused on the interaction of metals with the (111) surface of ceria, since this is the most stable surface and can be grown as films, which are probed experimentally. However, nanostructures exposing other surfaces such as (110) show high activity for reactions including CO oxidation and require further study; these nanostructures could be modified by deposition of metal atoms or small clusters, but there is no information to date on the atomic level details of metal-ceria interactions involving the (110) surface. This paper presents the results of density functional theory (DFT) corrected for on-site Coulomb interactions (DFT+U) calculations of the adsorption of a number of different metal atoms at an extended ceria (110) surface; the metals are Au, Ag, Cu, Al, Ga, In, La, Ce, V, Cr, and Fe. Upon adsorption all metals are oxidised, transferring electron(s) to the surface, resulting in localised surface distortions. The precise details depend on the identity of the metal atom. Au, Ag, Cu each transfer one electron to the surface, reducing one Ce ion to Ce 3+ , while of the trivalent metals, Al and La are fully oxidised, but Ga and In are only partially oxidised. Ce and the transition metals are also partially oxidised, with the number of reduced Ce ions possible in this surface no more than three per adsorbed metal atom. The predicted oxidation states of the adsorbed metal atoms should be testable in experiments on ceria nanostructures modified with metal atoms.

  15. Charge transfer and formation of reduced Ce3+ upon adsorption of metal atoms at the ceria (110) surface

    Science.gov (United States)

    Nolan, Michael

    2012-04-01

    The modification of cerium dioxide with nanoscale metal clusters is intensely researched for catalysis applications, with gold, silver, and copper having been particularly well studied. The interaction of the metal cluster with ceria is driven principally by a localised interaction between a small number of metal atoms (as small as one) and the surface and understanding the fundamentals of the interaction of metal atoms with ceria surfaces is therefore of great interest. Much attention has been focused on the interaction of metals with the (111) surface of ceria, since this is the most stable surface and can be grown as films, which are probed experimentally. However, nanostructures exposing other surfaces such as (110) show high activity for reactions including CO oxidation and require further study; these nanostructures could be modified by deposition of metal atoms or small clusters, but there is no information to date on the atomic level details of metal-ceria interactions involving the (110) surface. This paper presents the results of density functional theory (DFT) corrected for on-site Coulomb interactions (DFT+U) calculations of the adsorption of a number of different metal atoms at an extended ceria (110) surface; the metals are Au, Ag, Cu, Al, Ga, In, La, Ce, V, Cr, and Fe. Upon adsorption all metals are oxidised, transferring electron(s) to the surface, resulting in localised surface distortions. The precise details depend on the identity of the metal atom. Au, Ag, Cu each transfer one electron to the surface, reducing one Ce ion to Ce3+, while of the trivalent metals, Al and La are fully oxidised, but Ga and In are only partially oxidised. Ce and the transition metals are also partially oxidised, with the number of reduced Ce ions possible in this surface no more than three per adsorbed metal atom. The predicted oxidation states of the adsorbed metal atoms should be testable in experiments on ceria nanostructures modified with metal atoms.

  16. Effect of cerium on the corrosion behaviour of sintered (Nd,Ce)FeB magnet

    Science.gov (United States)

    Yang, Lijing; Bi, Mengxue; Jiang, Jianjun; Ding, Xuefeng; Zhu, Minggang; Li, Wei; Lv, Zhongshan; Song, Zhenlun

    2017-06-01

    For the balanced consumption of rare-earth elements, cerium (Ce) was partially used for NdFeB magnets instead of Nd. The corrosion behaviour of the (Nd,Ce)FeB magnet with different Ce contents in 3.5% NaCl solution was investigated by SEM, XRD, EDS and electrochemical tests. After immersion, the weight loss was calculated and the magnetic properties of the samples were measured. Results showed that Ce affected the corrosion of the (Nd,Ce)FeB magnet. Compared with the NdFeB magnet without Ce but of the same grade as the magnetic energy product, (Nd,Ce)FeB magnet showed better corrosion resistance. With increased Ce content, the corrosion resistances and magnetic properties of (Nd,Ce)FeB magnets were investigated.

  17. Confirmatory Survey Results For Portions Of The ABB Combustion Engineering Site In Windsor, Connecticut During The Fall Of 2011

    International Nuclear Information System (INIS)

    Adams, Wade C.

    2011-01-01

    From the mid-1950s until mid-2000, the Combustion Engineering, Inc. (CE) site in Windsor, Connecticut (Figure A-1) was involved in the research, development, engineering, production, and servicing of nuclear fuels, systems, and services. The site is currently undergoing decommissioning that will lead to license termination and unrestricted release in accordance with the requirements of the License Termination Rule in 10 CFR Part 20, Subpart E. Asea Brown Boveri Incorporated (ABB) has been decommissioning the CE site since 2001.

  18. CONFIRMATORY SURVEY RESULTS FOR PORTIONS OF THE ABB COMBUSTION ENGINEERING SITE IN WINDSOR, CONNECTICUT DURING THE FALL OF 2011

    Energy Technology Data Exchange (ETDEWEB)

    Wade C. Adams

    2011-12-09

    From the mid-1950s until mid-2000, the Combustion Engineering, Inc. (CE) site in Windsor, Connecticut (Figure A-1) was involved in the research, development, engineering, production, and servicing of nuclear fuels, systems, and services. The site is currently undergoing decommissioning that will lead to license termination and unrestricted release in accordance with the requirements of the License Termination Rule in 10 CFR Part 20, Subpart E. Asea Brown Boveri Incorporated (ABB) has been decommissioning the CE site since 2001.

  19. Optimization of the time response of LaBr3(Ce) detectors, and its dependence on Ce concentration

    International Nuclear Information System (INIS)

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

    2015-01-01

    Fast inorganic scintillators that exhibit good spectroscopy performance, like LaBr 3 (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. This method, which is very sensitive to the LaBr 3 (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. In this work we have searched for the best settings in order to optimize the time resolution of three cylindrical LaBr 3 (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 BaF 2 detector, whose time response is well known. The LaBr 3 (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 60 Co and 22 Na energies. (author)

  20. Preparation and emission properties of NaBi(WO4)2 and NaBi(WO4)2:Ce single crystals

    International Nuclear Information System (INIS)

    Nitsch, K.; Nikl, M.; Barta, C.; Triska, A.

    1990-01-01

    The preparation of pure and Ce 3+ -doped NaBi(WO 4 ) 2 single crystals (NBW) and the determination of their basic transmission and emission properties including time-resolved measurements are described. The decay of NBW emission is obviously non-exponential. It can be concluded that emission arises at regular sites of the crystal lattice and is connected with electronic transitions from Bi 3+ to the WO 4 2- group and/or excitation of the WO 4 2- group itself. It is not possible to excite Ce 3+ ions directly

  1. [Analysis of Irregular Antibody Production in Severe β-Thalassemia Children with long-term Blood Transtusion and Its Correlation with RH Gene and Anemia Gene Mutation Site].

    Science.gov (United States)

    Wang, Ming-Quan; Gao, Jing-Jing; Xie, Ren-Wei; Wang, Qing-Hai

    2017-12-01

    To analyze the prevalence of irregular antibodies in children with severe β-thalassemia after long-term blood transfusion and its correlation with RH and anemia gene mutations site. One hundred twenty children with severe β-thalassemia and long-term blood transfusion were selected in our hospital, the genomic DNA was extracted and the genotype of RH factor were determined by PCR-SSP. The irregular antibodies and their types were screened and identified by the serological method, the gene types of the severe β-thalassemia were analyzed by reverse dot blot hybridization on DNA chip and PCR amplification. The major of RH genotypes in 120 children were Ce/Ce (59.17%) and CE/ce (25%), among them 10 children possessed the positive irregular antibodies (8.33%), out of these 10 children, the genotypes of RH factor were Ce/Ce in 6 cases, cE/cE, CE/ce, cE/ce and Ce/ce in one case; among these 10 children with positive irregular antibodies, the anemia gene mutations were IVs-11654M in 2 cases, cD4142M in 6 cases, 28M in 1 case, and CD71-72M in 1 case. Irregular antibodies produced by regular blood transfusion in children with severe β-thalassemia may be related with RH factor and anemia gene mutation sites.

  2. A new 3DOM Ce-Fe-Ti material for simultaneously catalytic removal of PM and NOx from diesel engines.

    Science.gov (United States)

    Cheng, Ying; Liu, Jian; Zhao, Zhen; Song, Weiyu; Wei, Yuechang

    2018-01-15

    A new 3DOM material was designed and synthesized for the simultaneous removal of PM (soot particulates) and NOx from diesel engine exhausts. The catalytic purification taking place over the material with double efficacy is cost-efficient. The contact between solid PM and catalyst active site has been process intensified by 3DOM unique structure. 3DOM Ce 0.7 Fe 0.2 Ti 0.1 O 2 catalyst possess a high SCR activity and an excellent selectivity to N 2 , giving a maximum concentration of CO 2 at 385°C for PM combustion and 100% NO conversion in the temperature range of 281-425°C. The dual redox cycles (Fe 3+ +Ce 3+ ↔Fe 2+ +Ce 4+ ,Fe 3+ +Ti 3+ ↔Fe 2+ +Ti 4+ ) and the excellent reducibility and sufficient acid sites of catalysts play key roles for the highly catalytic performance. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Non-aqueous CE-MS of cinchona alkaloids - characterizationof a novel CE-ESI-MS interface

    DEFF Research Database (Denmark)

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

    a submicron fracture in the capillary close the ESI tip. The fracture provides a zero dead volume and excellent conducting properties due to the large amount of ions in the electric double layer. Electric current exceeding the upper limit of CE instrumentation of up to 300 µA can easily be obtained...... the composition of alkaloids in Cinchona bark. One common problem for sheatless interfaces for CE-MS has been establishing a stable electric contact at the end of the separation capillary that does not induce band broadening or affect the spray stability. In our device the electric contact is generated through...

  4. Improvement of photoluminescence intensity of Ce-doped Y{sub 3}Al{sub 5}O{sub 12} phosphor by Si{sub 3}N{sub 4} addition

    Energy Technology Data Exchange (ETDEWEB)

    Shyu, Jiin-Jyh, E-mail: jjshyu@ttu.edu.tw; Yang, Chia-Wei

    2017-06-01

    Yttrium aluminum garnet (Y{sub 3}Al{sub 5}O{sub 12}, YAG) has been widely used as a host for luminescent ions. The present paper describes the effects of Si{sub 3}N{sub 4} addition on the formation and photoluminescence properties of the Ce-doped YAG yellow phosphors. Phosphor powders with the nominal compositions of Y{sub 2.95}Ce{sub 0.05}Al{sub 5-m}Si{sub m}O{sub 12-m}N{sub m} (m = 0–0.6) were prepared by calcining the mixed raw materials at 1500 °C in nitrogen atmosphere. X-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscope, and transmission electron microscopy equipped with an energy dispersive x-ray spectrometer were used to characterize the structure of the calcined powders. The photoluminescence properties were measured with fluorescence spectrophotometry. It was found that in the range of m = 0–0.27, single phase YAG solid solution (s.s.) in which the Y, Al, and O sites are partially occupied by Ce, Si, and N ions, respectively. The nitrogen ions do not distribute homogeneously over the YAG lattice. The tendency to bond with nitrogen ion for the cations is (Y, Ce) > Si > Al. With the increase in the Si{sub 3}N{sub 4} content, the increase in both the Ce{sup 3+}/(Ce{sup 3+} + Ce{sup 4+}) ratio and the Ce-N bonds improve the intensity of the photoluminescent emission. At m = 0.27, the emission intensity reaches a maximum which is about 2.5 and 1.6 times of that for the Si{sub 3}N{sub 4}-free composition (m = 0) calcined in air and nitrogen, respectively. When the Si{sub 3}N{sub 4} content (m) is higher than 0.27, the emission intensity decreases due to the existence of residual Si{sub 3}N{sub 4} phase. - Highlights: • Addition of Si{sub 3}N{sub 4} can increase the emission intensity of YAG:Ce up to 2.5 times. • Increase in the Ce{sup 3+}/Ce{sup 4+} ratio and the number of Ce-N bonds improve the emission. • The tendency to bond with nitrogen ion for cations in YAG:Ce is (Y, Ce) > Si > Al. • The incomplete dissolution

  5. Quaternary germanides RE{sub 3}TRh{sub 4}Ge{sub 4} (RE = Ce, Pr, Nd; T = Nb, Ta) - a new coloring variant of the aristotype AlB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, Rolf-Dieter; Vosswinkel, Daniel; Poettgen, Rainer [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, 48149 Muenster (Germany); Matar, Samir F. [CNRS, Universite de Bordeaux, ICMCB, UPR 9048, 33600 Pessac (France)

    2016-09-15

    The quaternary germanides RE{sub 3}TRh{sub 4}Ge{sub 4} (RE = Ce, Pr, Nd; T = Nb, Ta) were synthesized from the elements by arc-melting and subsequent annealing in a muffle furnace. The structure of Ce{sub 3}TaRh{sub 4}Ge{sub 4} was refined from single-crystal X-ray diffractometer data: new type, Pbam, a = 719.9(2), b = 1495.0(3), c = 431.61(8), wR{sub 2} = 0.0678, 1004 F{sup 2} values, and 40 variables. Isotypy of the remaining phases was evident from X-ray powder patterns. Ce{sub 3}TaRh{sub 4}Ge{sub 4} is a new superstructure variant of the aristotype AlB{sub 2} with an ordering of cerium and tantalum on the aluminum site, whereas the honey-comb network is built up by a 1:1 ordering of rhodium and germanium. This crystal-chemical relationship is discussed based on a group-subgroup scheme. The distinctly different size of tantalum and cerium leads to a pronounced puckering of the [Rh{sub 4}Ge{sub 4}] network, which shows the shortest interatomic distances (253-271 pm Rh-Ge) within the Ce{sub 3}TaRh{sub 4}Ge{sub 4} structure. Another remarkable structural feature concerns the tantalum coordination with six shorter Ta-Rh bonds (265-266 pm) and six longer Ta-Ge bonds (294-295 pm). The [Rh{sub 4}Ge{sub 4}] network fully separates the tantalum and cerium atoms (Ce-Ce > 387 pm, Ta-Ta > 431 pm, and Ce-Ta > 359 pm). The electronic density of states DOS from DFT calculations show metallic behavior with large contributions of localized Ce 4f as well as itinerant ones from all constituents at the Fermi level but no significant magnetic polarization on Ce could be identified. The bonding characteristics described based on overlap populations illustrate further the crystal chemistry observations of the different coordination of Ce1 and Ce2 in Ce{sub 3}TaRh{sub 4}Ge{sub 4}. The Rh-Ge interactions within the network are highlighted as dominant. The bonding magnitudes follow the interatomic distances and identify differences of Ta bonding vs. Ce1/Ce2 bonding with the Rh and Ge

  6. Magnetic domains and frustration in metallic CePdAl

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, Stefan; Huesges, Zita; Huang, Chien-Lung; Stockert, Oliver [Max Planck Institute CPfS, Dresden (Germany); Fritsch, Veronika; Sakai, Akito [EP 6, Electronic Correlations and Magnetism, University of Augsburg (Germany); Grube, Kai; Taubenheim, Christian; Loehneysen, Hilbert von [Karlsruhe Institute of Technology (Germany)

    2016-07-01

    Magnetic frustration is an exciting topic in condensed matter physics, since it can lead to new ground states of materials, e.g. a spin liquid or spin glass state. Effects of magnetic frustration have been investigated intensively for insulating materials. However, the existence of magnetic frustration in metallic systems is still under debate. CePdAl is a metallic Kondo system, where geometric magnetic frustration arises from the formation of Ce ions on a distorted Kagome lattice. Neutron scattering experiments revealed, that only two thirds of the magnetic Ce moments order antiferromagnetically below T{sub N}=2.7 K, whereas the other third remains mainly disordered. Thermodynamic as well as neutron scattering measurements are presented to verify the existence of partial magnetic frustration in CePdAl. Recently neutron diffraction experiments under magnetic fields applied along two orthogonal directions in the magnetically hard basal plane were performed. They show opposite effects on the magnetic intensity of a selected magnetic domain depending on the field direction with respect to the propagation vector. If this is only an effect of different domain population or also due to a change in magnetic frustration shall be discussed.

  7. Preparation and properties of Pr /Ce :YAG phosphors using ...

    Indian Academy of Sciences (India)

    2015-09-01

    Sep 1, 2015 ... The relatively higher pH could decrease the loss of Ce and Pr in the precursors and increase the particle size of the obtained powders, which was beneficial to the enhancement of luminescent intensity. Therefore, the precursors directly converted to pure-phase YAG at 900◦C, and the phosphors calcined at ...

  8. Optical properties of CeO2 thin films

    Indian Academy of Sciences (India)

    TECS

    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.

  9. Antiferromagnetism and hot spots in CeIn3

    Science.gov (United States)

    Grigoriev, Pavel; Gor'kov, Lev

    2006-03-01

    Enormous mass enhancement at ``hot spots'' on the Fermi surface (FS) of the antiferromagnetic CeIn3 has been reported at strong magnetic field near its antiferromagnetic quantum critical point [T. Ebihara et al., Phys. Rev. Lett. 93, 246401 (2004)]. The effect was ascribed to anomalous spin fluctuations at these spots owing to peculiar strong many-body interactions. The ``hot spots'' lie at the positions on FS same as in non-magnetic LaIn3 where the narrow necks are protruded, thus, hinting on their possible relation. Assuming that in paramagnetic phase CeIn3 has similar spectrum, we study the influence of the antiferromagnetic ordering (AFM) on the energy spectrum of CeIn3 and show that its FS undergoes a topological change at the onset of AFM. The necks at the ``hot spots'' are truncated by the AFM, thus restoring the almost spherical d-part of the FS of CeIn3. Applied field suppresses the AFM and restores the necks on the FS (so-called 2.5-order phase transition) leading to logarithmic divergence of the dHvA effective mass when the electron trajectory passes near or through the restored necks. This effect fully explains the observed dHvA mass enhancement in the ``hot spots'' in the frameworks of one-particle approximation and leads to the predictions concerning the spin-dependence of the effective electron mass.

  10. Preparation and properties of Pr /Ce :YAG phosphors using ...

    Indian Academy of Sciences (India)

    2015-09-01

    Sep 1, 2015 ... 3+. :YAG phosphors using triethanolamine as dispersant and pH regulator. SHIHONG TONG. ∗. , JUNYAN ZHAO and XIU WEN. College of Sciences of Southwest Petroleum .... were weighted in the molar ratio of 0.015:0.06:2.925:5 and ... Pr3+/Ce3+:YAG powders were investigated by X-ray diffrac-.

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

    International Nuclear Information System (INIS)

    Lichtenstein, H.; Troubetzkoy, E.S.; Beer, M.

    1980-01-01

    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

  12. 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...

  13. 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.

  14. 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,...).

  15. Optical properties of CeO2 thin films

    Indian Academy of Sciences (India)

    TECS

    increase with increase in thickness. The values of absorp- tion coefficient, extinction coefficient, refractive index, dielectric constant, phase angle and loss angle were found to be in conformity with previous works. From the X-ray diffraction studies it is found that CeO2 thin film has crys- talline structure and a smaller crystallite ...

  16. Burstein Moss effect in nanocrystalline CaS: Ce

    Indian Academy of Sciences (India)

    Administrator

    Burstein Moss effect in nanocrystalline CaS: Ce. GEETA SHARMA*, PUJA CHAWLA, S P LOCHAB. † and NAFA SINGH. Department of Physics, Kurukshetra University, Kurukshetra 136 119, India. †. Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067, India. MS received 27 July 2009; revised 16 ...

  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...

  18. Ce que PMNT finance Promotion d'une alimentation saine

    International Development Research Centre (IDRC) Digital Library (Canada)

    Ce que PMNT finance. Promotion d'une alimentation saine. Comprendre le contexte d'élaboration des politiques. Analyses situationnelles portant sur les politiques relatives à une alimentation saine : analyse situationnelle du niveau de mesures de lutte sont mises en œuvre (contrôle exercé sur la disponibilité, le prix de ...

  19. Properties of polyamorphous Ce75Al25 metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Q.-S.; Struzhkin, Viktor V.; Fang, Y. Z.; Gao, C. X.; Luo, H. B.; Wang, X. D.; Lathe, C.; Mao, Wendy L.; Wu, F. M.; Mao, Ho-kwang; Jiang, J. Z.

    2010-08-17

    The thermal stability and electronic transport properties of polyamorphous Ce{sub 75} Al{sub 25} metallic glass (MG) have been investigated using in situ high-pressure, high-temperature, energy-dispersive synchrotron x-ray diffraction and in situ high-pressure and low-temperature, four-probe resistance measurements. The results are compared with the properties of La{sub 75} Al{sub 25} MG. The pressure dependence of the crystallization temperature and resistance of the Ce{sub 75} Al{sub 25} MG exhibited turning points at the polyamorphic transition pressure, 1.5 GPa, and they clearly presented different behaviors below and above 1.5 GPa. In contrast, no turning points were observed in the La{sub 75} Al{sub 25} MG (La has no 4f electron). Additionally, the pressure-tuned temperature coefficient of resistance of the Ce{sub 75} Al{sub 25} MG was observed. These results revealed switchable properties in the polyamorphous Ce{sub 75} Al{sub 25} MG that are linked with 4f electron delocalization.

  20. d-AO spherical aromaticity in Ce6O8.

    Science.gov (United States)

    Yu, Xiaohu; Oganov, Artem R; Popov, Ivan A; Boldyrev, Alexander I

    2016-01-05

    After the first introduction of π aromaticity in chemistry to explain the bonding, structure, and reactivity of benzene and its derivatives, this concept was further applied to many other compounds featuring other types of aromaticity (i.e., σ, δ). Thus far, there have been no reports on d-AO-based spherical σ aromaticity. Here, we predict a highly stable bare Ce6O8 cluster of a spherical shape using evolutionary algorithm USPEX and DFT + U calculations. Natural bond orbital analysis, adaptive natural density partitioning algorithm, electron localization function, and partial charge plots demonstrate that bare Ce6O8 cluster exhibits d-AO spherical σ aromaticity, thus explaining its exotic geometry and stability. Ce6O8 complex plays an important role in many reactions and is known to exist in many forms, such as in NH4[Ce6(μ(3)O)5(μ(3)OH)3(μ(2)-C6H5COO)9(NO3)3(DMF)3]*DMF*H2O compound, which is prepared under room temperature, and acts as an oxidizing agent. © 2015 Wiley Periodicals, Inc.

  1. Geometry modeling for SAM-CE Monte Carlo calculations

    International Nuclear Information System (INIS)

    Steinberg, H.A.; Troubetzkoy, E.S.

    1980-01-01

    Three geometry packages have been developed and incorporated into SAM-CE, for representing in three dimensions the transport medium. These are combinatorial geometry - a general (non-lattice) system, complex combinatorial geometry - a very general system with lattice capability, and special reactor geometry - a special purpose system for light water reactor geometries. Their different attributes are described

  2. Dynamical magnetic response of paramagnetic CeFe-2

    International Nuclear Information System (INIS)

    Rainford, B.D.; McK Paul, D.; Warwick Univ., Coventry

    1988-01-01

    Inelastic neutron scattering has been used to study the energy dependence of the paramagnetic response from CeFe 2 . Our results, when integrated over energy, are in excellent agreement with the polarised neutron experiments of Deportes et al., but the correlation length obtained by fitting the data to a double Lorentzian scattering function is significantly smaller than that derived previously

  3. Commensurate-commensurate magnetic phase transitions in CeSb

    DEFF Research Database (Denmark)

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

    1986-01-01

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

  4. Site Features

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset consists of various site features from multiple Superfund sites in U.S. EPA Region 8. These data were acquired from multiple sources at different times...

  5. POLLiCE (POLLen in the iCE): climate history from Adamello ice cores

    Science.gov (United States)

    Cristofori, Antonella; Festi, Daniela; Maggi, Valter; Casarotto, Christian; Bertoni, Elena; Vernesi, Cristiano

    2017-04-01

    Glaciers can be viewed as the most complete and effective past climate and environment archives severely threatened by climate change. These threats are particularly dramatic across European Alps. The Adamello glacier is the largest, 16.4 km2, and deepest, 270 m, Italian glacier. We aim at estimating biodiversity changes over the last centuries in relation to climate and human activities in the Adamello catchment area. We, therefore, recently launched the POLLiCE project (pollice.fmach.it) for specifically targeting the biological component (e.g. pollen, leaves, plant remains) trapped in ice cores. Classical morphological pollen analysis will be accompanied by DNA metabarcoding. This approach has the potential to provide a detailed taxonomical identification - at least genus level- thus circumventing the limitations of microscopic analysis such as time-consuming procedures and shared features of pollen grains among different taxa. Moreover, ice cores are subjected to chemical and physical analyses - stable isotopes, ions, hyperspectral imaging, etc.- for stratigraphic and climatic determination of seasonality. A pilot drilling was conducted on March 2015 and the resulting 5 m core has been analysed in terms of pollen spectrum, stable isotopes and ions in order to demonstrate the feasibility of the study. The first encouraging results showed that even in this superficial core a stratigraphy is evident with indication of seasonality as highlighted by both by pollen taxa and stable isotopes. Finally, DNA has been successfully extracted and amplified with specific DNA barcodes. A medium drilling was performed on April 2016 with the extraction of a 45 m ice core. The analysis of this core constitutes the subject of a specific research project, CALICE*, just funded by Euregio Science Fund (IPN57). The entire depth, 270 m, of the Adamello glacier is scheduled to be drilled in 2018 winter to secure the unique memory archived by the ice. * See EGU2017 poster by Festi et al

  6. 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.

  7. Effect of surface modification of CeO2 buffer layers on Jc and defect microstructures of large-area YBCO thin films

    International Nuclear Information System (INIS)

    Develos-Bagarinao, K; Yamasaki, H; Nakagawa, Y

    2006-01-01

    High-quality CeO 2 buffer layers are requisite for the successful growth of YBCO thin films with excellent properties on sapphire substrates. In this study, we evaluated the effect of surface modification of the CeO 2 layers on the properties of the YBCO thin films prepared by large-area pulsed laser deposition (PLD), in particular the critical current density J c and defect microstructure. High-temperature annealing (1050 deg. C ) has been found to significantly smoothen the very rough and granular surfaces of the as-grown CeO 2 layers (surface roughness rms∼5-10 nm) to atomic flatness (rms∼0.5 nm). However, a rather unique characteristic of the CeO 2 layers deposited by large-area PLD is the development of pores when subjected to prolonged high-temperature annealing. For very short annealing periods (10-20 min), the surface morphology becomes atomically flat, along with the appearance of a high density of 'nanopores' that are ∼40-100 nm in diameter and ∼3-5 nm in depth. Extending the annealing period to 60 min or more results in the development of a surface subtended with enlarged pores ∼0.2-0.5 μm in diameter. Compared with the YBCO thin films deposited on as-grown CeO 2 , YBCO thin films on annealed CeO 2 exhibited better homogeneity of J c and better crystalline texture. Among the YBCO thin films deposited on annealed CeO 2 , higher self-field and in-field J c was obtained for YBCO thin films deposited on CeO 2 with smooth surfaces but interspersed with nanopores. Investigation of the defect microstructure via the etch pit method in conjunction with atomic force microscopy (AFM) of the YBCO thin films revealed a high density of linear defects in the form of screw and edge dislocations, which correlated well with a high density of nanopores on annealed CeO 2 . Transmission electron microscopy (TEM) further confirmed the presence of threading dislocations clearly emanating from the nanopore sites. Angular dependence of J c revealed enhanced flux

  8. Enhanced luminescence of Tb3+ due to efficient energy transfer from Ce3+ in a nanocrystalline Lu2Si2O7 host lattice

    International Nuclear Information System (INIS)

    Sokolnicki, J

    2010-01-01

    Nanocrystalline lutetium pyrosilicate Lu 2 Si 2 O 7 (LPS) doped with Tb 3+ (LPS:Tb) or Ce 3+ /Tb 3+ (LPS:Ce, Tb) was obtained at 1250 0 C by the reaction of nanostructured Lu 2 O 3 and colloidal SiO 2 . X-ray diffraction analysis confirmed the crystallization of a single phase of LPS at the indicated temperature. Different concentrations of active ions allowed us to study the influence of Ce 3+ co-doping on Tb 3+ emission. Tb 3+ -doped LPS yields both the blue emission 5 D 3 → 7 F J (J = 3, 4, 5, 6) and the green emission 5 D 4 → 7 F J (J = 3, 4, 5, 6) of Tb 3+ . The green emission of Tb 3+ is enhanced remarkably in both the cathodoluminescence and photoluminescence spectra because of energy transfer from Ce 3+ to Tb 3+ ions, both of which are present in the host lattice. Based on the optical luminescence and luminescence excitation spectra, the optimal Tb 3+ doping level for maximum light output was established to be 9 mol% and the highest enhancement of Tb 3+ luminescence by Ce 3+ co-doping was detected using a 1:3 ratio of Ce 3+ /Tb 3+ concentration. Two different crystallographic sites of Tb 3+ in the LPS lattice were detected in the luminescence and excitation spectra of samples with higher Tb 3+ concentrations (6-9 mol%). The single-exponential decay profile of 5 D 4 emission for the less concentrated samples and the double-exponential decay for the higher doping level are in agreement with this observation. Calculation of colour coordinates shows that LPS:Ce(0.25%)Tb(3%) emits white light.

  9. Structural and magnetic investigation of Ca2MnReO6 doped with Ce

    Directory of Open Access Journals (Sweden)

    J. B. Depianti

    2013-06-01

    Full Text Available We have studied the properties of Ce doping in Ca-site of Ca2MnReO6 double perovskite up to 10%. These compounds have presented a monoclinic cell with P2(1/n space group. A small increase of lattice parameters in doped sample were observed through Rietveld refinement of X-ray diffraction pattern. The spectra at the Mn K-edge and Re L3-edge showed a mixed valence for Mn and Re in both samples. We do not observed any variation on Mn K-edge valence in XANES measurements under pressure. However a change was observed for Re L3-edge as a function of applied pressure. The Ce-doped sample showed a magnetic geometric frustration and a small decrease of the temperature frustration as compared with Ca2MnReO6 sample. The decrease of temperature frustration can be related to the MnO6 and ReO6 octahedral distortion.

  10. The 1997 Excavations at the Big Eddy Site (23CE426) in Southwest Missouri

    Science.gov (United States)

    1998-11-24

    Paleolithic , pre-Projectile Point, or pre-Clovis (e.g., Alsoszatai-Petheo 1986; Bryan 1986), they have cor- rectly emphasized the need for caution...Spiess et al. 1985), but good subsistence data are lacking. The traditional " diet -centered" model of Early Paleoindian adaptation is of highly...the Advancement of Sci- ence 37:293-315. 1892 Paleolithic Man in America. Science 20:270-271. Adovasio, James M., Jack Donahue, and Robert

  11. Site decontamination

    International Nuclear Information System (INIS)

    Bicker, A.E.

    1981-01-01

    Among the several DOE sites that have been radiologically decontaminated under the auspices of the Nevada Operations Office are three whose physical characteristics are unique. These are the Tatum Dome Test Site (TDTS) near Hattiesburg, Mississippi; a location of mountainous terrain (Pahute Mesa) on the Nevada Test Site; and the GNOME site near Carlsbad, New Mexico. In each case the contamination, the terrain, and the climate conditions were different. This presentation includes a brief description of each site, the methods used to perform radiological surveys, the logistics required to support the decontamination (including health physics and sample analysis), and the specific techniques used to reduce or remove the contamination

  12. Crystal growth and scintillation properties of multi-component oxide single crystals: Ce:GGAG and Ce:La-GPS

    Czech Academy of Sciences Publication Activity Database

    Yoshikawa, A.; Kamada, K.; Kurosawa, S.; Shoji, Y.; Yokota, Y.; Chani, V.I.; Nikl, Martin

    2016-01-01

    Roč. 169, Jan (2016), s. 387-393 ISSN 0022-2313. [International Conference on Luminescence and Optical Spectroscopy of Condensed Matter /17./. Wroclaw, 13.07.2014-18.07.2014] Institutional support: RVO:68378271 Keywords : scintillator * luminescent materials * Ce 3+ * radioluminescence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.686, year: 2016

  13. ETUDE PAR DFT+U DE L’INTERACTION Ni-CeO2

    Directory of Open Access Journals (Sweden)

    Z CHAFI

    2010-12-01

    Full Text Available L’étude de l’interaction Ni-CeO2 a été entreprise en utilisant une méthode ab initio basée sur la DFT+U. Dans une première étape, les valeurs du paramètre d’Hubbard, Ueff, ont été déterminées après ajustement du paramètre de maille et de l’énergie de gap du volume de l’oxyde de cérium. Elles sont respectivement de 3 et 5 eV pour les approximations GGA et LDA. Nous avons ensuite étudié d’une part la possibilité d’insérer le nickel atomique dans le volume de CeO2. D’autre part, nous avons testé les effets de l’insertion et l’adsorption de Ni dans les surfaces les plus stables (111 et (110 de CeO2. Les résultats des calculs DFT+U sont en bon accord avec ceux que nous avons précédemment trouvé en utilisant un calcul DFT concernant les sites favorables de l’atome de nickel et le nombre de liaisons. Toutefois, l’approximation LDA+5 eV, a permis d’obtenir des énergies plus favorables ainsi que des distances comparables à celles observées expérimentalement à l’interface métal/oxyde dans les catalyseurs Ni/CeO2 synthétisés sous irradiation. Une expansion du volume est observée lors de l’insertion du nickel dans le volume de l’oxyde de cérium. Concernant l’adsorption sur les surfaces, la meilleure énergie est trouvée dans le cas où l’atome de nickel est situé en position bridge entre deux atomes d’oxygène sur la surface (110. Finalement, les calculs montrent que le nickel s’insère plus facilement dans la surface (110 avec une meilleure énergie d’insertion, obtenue par l’approximation LDA+5 eV, de 4,071 eV.

  14. Influence of two-electrode montages on the level-specific (LS) CE-Chirp auditory brainstem response (ABR) at multiple intensity levels.

    Science.gov (United States)

    Dzulkarnain, Ahmad Aidil Arafat; Noor Ibrahim, Siti Hajra Mu'minah; Anuar, Nur Farah Aida; Abdullah, Siti Aisyah; Tengku Zam Zam, Tengku Zulaila Hasma; Rahmat, Sarah; Mohd Ruzai, Muhammad Amar

    2017-10-01

    To investigate the influence of two different electrode montages (ipsilateral: reference to mastoid and vertical: reference to nape of neck) to the ABR results recorded using a level-specific (LS)-CE-Chirp® in normally hearing subjects at multiple intensities levels. Quasi-experimental and repeated measure study designs were applied in this study. Two different stopping criteria were used, (1) a fixed-signal averaging 4000 sweeps and, (2) a minimum quality indicator of Fmp = 3.1 with a minimum of 800 sweeps. Twenty-nine normally hearing adults (18 females, 11 male) participated. Wave V amplitudes were significantly larger in the LS CE-Chirp® recorded from the vertical montage than the ipsilateral montage. Waves I and III amplitudes were significantly larger from the ipsilateral LS CE-Chirp® than from the other montages and stimulus combinations. The differences in the quality of the ABR recording between the vertical and ipsilateral montages were marginal. Overall, the result suggested that the vertical LS CE-Chirp® ABR had a high potential for a threshold-seeking application, because it produced a higher wave V amplitude. The Ipsilateral LS CE-Chirp® ABR, on the other hand, might also have a high potential for the site of lesion application, because it produced larger waves I and III amplitudes.

  15. Nitrate storage behavior of Ba/MnOx-CeO2 catalyst and its activity for soot oxidation with heat transfer limitations.

    Science.gov (United States)

    Wu, Xiaodong; Liu, Shuang; Lin, Fan; Weng, Duan

    2010-09-15

    A BaMnCe ternary catalyst was prepared by impregnating barium acetate on MnO(x)-CeO(2) mixed oxides, with the monoxide supported catalysts and the solid solution support as references. The activities of the catalysts for soot oxidation were evaluated in the presence of NO under an energy transference controlled regime. BaMnCe presented the lowest maximal soot oxidation rate temperature at 393 degrees C among the catalysts investigated. Although BaMnCe experienced a loss in the specific surface area and low-temperature redox property due to blocking of the support pores by barium carbonate, its superior soot oxidation activity highlighted the importance of relatively stable bidentate/monodentate nitrates coordinated to Mn(x+) and Ce(x+) sites and more stable ionic barium nitrate. About half of the nitrates stored on this catalyst decomposed within the temperature interval of 350-450 degrees C, and the ignition temperature of soot decreased significantly with involvement of the nitrates or NO(2) released. Copyright 2010 Elsevier B.V. All rights reserved.

  16. Electronic and optical properties of layered RE{sub 2}Ti{sub 2}O{sub 7} (RE = Ce and Pr) from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Sayede, A. [Universite Lille Nord de France, F-59000 Lille (France); Khenata, R. [Laboratoire de Physique Quantique et de Modlisation Mathmatique, Universite de Mascara, Mascara, 29000 (Algeria); Chahed, A.; Benhelal, O. [Condensed Matter and Sustainable Development Laboratory, Djillali Liabes University of Sidi Bel-Abbes, Sidi Bel-Abbes 22000 (Algeria)

    2013-05-07

    We have studied the structural and electronic properties of Ce{sub 2}Ti{sub 2}O{sub 7} (CeTO) and Pr{sub 2}Ti{sub 2}O{sub 7} (PrTO) by first-principles density functional theory calculations. The computed structural parameters are in fairly good agreement with the available experimental findings. Band structure calculations using the GGA+U approach predict an insulating ground state for the herein studied compounds. The insulating band gaps of 2.00 eV and 2.83 eV are found for CeTO and PrTO, respectively. The analysis of the density of states reveals that the strongly localized RE 4f levels act as charge-trapping sites, predicting a lower photocatalytic activity for CeTO. We have also calculated the optical properties for both CeTO and PrTO. Based on these properties, it is predicted that these titanates are insensitive to ultra-violet radiation, while they are more sensitive to frequencies of the radiation in visible and early UV regions.

  17. Road repair works on the Meyrin site

    CERN Multimedia

    2003-01-01

    ST Division will proceed, as from Monday 15th of September, in repairing some parts of roads on the Meyrin site (see drawing). This work will last for three weeks depending on the weather conditions and will cause some traffic hold ups during this period. Please follow the indications on the temporary road signs. Thanking you in advance for your comprehension. ST-CE and ST-FM Groups GSM 160224 - 163976

  18. Site organization and site arrangement

    International Nuclear Information System (INIS)

    Boissonnet, B.; Macqueron, J.F.

    1976-01-01

    The present paper deals with criteria for the choice of a production unit or power plant site, the organization and development of a site in terms of its particular characteristics and takes into account personnel considerations in site organizations as well as the problem of integrating the architecture into the environment. (RW) [de

  19. Asia Rice Crop Estimation and Monitoring (Asia-RiCE) for GEOGLAM

    Science.gov (United States)

    Oyoshi, K.; Tomiyama, N.; Okumura, T.; Sobue, S.

    2013-12-01

    other regions. The methodology for rice crop monitoring is different from that for other crops, and these characteristics make rice crop monitoring by Earth observation data more difficult and complicated. Now, Asian-RiCE team has selected four technical demonstration sites, Indonesia, Thailand, Vietnam (North and South) for Phase1A implementation (June 2013 to November 2014) to verify methodologies that estimate multi-season crop calendar, rice planted area, yield and production by the blending of Earth observation data including satellite data from SAR or optical sensor and in-situ data. We already developed some prototype systems for rice planed area mapping by SAR and agro-weather monitoring including soil moisture or drought index by microwave and optical data. These technologies would be contribute to the development of rice crop monitoring framework for Asia-RiCE. In this presentation, we introduce the framework and ongoing activities of Asia-RiCE component for GEOGLAM and developed systems for rice crop and agro-weather monitoring.

  20. Solid-solution stability and preferential site-occupancy in (R-R')2Fe14B compounds

    Science.gov (United States)

    Colin, C. V.; Ito, M.; Yano, M.; Dempsey, N. M.; Suard, E.; Givord, D.

    2016-06-01

    The rare-earth (R) uniaxial anisotropy of R2Fe14B compounds with magnetic R atoms (e.g., Nd or Pr) is at the origin of the exceptional hard magnetic properties achieved in magnets based on these compounds. The uniaxial anisotropy found in Ce2Fe14B is attributed mainly to the magnetism of Fe. Ce is the most abundant R element and there has been much recent effort to fabricate magnets in which Ce is partially substituted for Nd. In the present neutron study of (R1-xCex)2Fe14B (R = La or Nd), Ce is found to enter the R2Fe14B phase over the entire composition range. The crystallographic parameters decrease with increasing Ce content and the Ce atoms preferentially occupy the smaller 4f sites. It is concluded that Ce in these (RR')2Fe14B compounds essentially maintains the intermediate valence character found in Ce2Fe14B. It is proposed that, in this intermediate valence state, Ce weakly contributes to uniaxial anisotropy, thus making a link with the fact that significant coercivity is preserved in Ce-substituted NdFeB magnets.

  1. The investigation of Ce doped ZnO crystal: The electronic, optical and magnetic properties

    Science.gov (United States)

    Wen, Jun-Qing; Zhang, Jian-Min; Qiu, Ze-Gang; Yang, Xu; Li, Zhi-Qin

    2018-04-01

    The electronic, optical and magnetic properties of Ce doped ZnO crystal have been studied by using first principles method. The research of formation energies show that Ce doped ZnO is energetically stable, and the formation energies reduce from 6.25% to 12.5% for Ce molar percentage. The energy band is still direct band gap after Ce doped, and band gap increases with the increase of Cesbnd Ce distance. The Fermi level moves upward into conduction band and the DOS moves to lower energy with the increase of Ce concentration, which showing the properties of n-type semiconductor. The calculated optical properties imply that Ce doped causes a red-shift of absorption peaks, and enhances the absorption of the visible light. The transition from ferromagnetic to antiferromagnetic has been found in Ce doped ZnO.

  2. Ce3+ įtaka α-pusvandenio gipso susidarymui

    Directory of Open Access Journals (Sweden)

    Nora KYBARTIENĖ

    2012-12-01

    Full Text Available Lietuvoje gamtinio dvivandenio gipso, tinkamo gipsinių rišamųjų medžiagų gamybai, nėra. Jį galima būtų pakeisti fosfogipsu (pusvandeniu ar dvivandeniu, kuris susidaro fosforo rūgšties gamybos metu, skaidant fosfatines žaliavas sieros rūgštimi. Priklausomai nuo fosfatinėje žaliavoje esančių priemaišų susidaręs fosfogipsas skiriasi kristalų morfologija ir savybėmis. Fosfogipsas yra daugiakomponentis junginys. Siekiant atsiriboti nuo kitų junginių ir įvertinti Ln3+ įtaką pusvandenio fosfogipso kristalų morfologijai, tikslinga sudaryti modelinę dvikomponentę sistemą: dvivandenis gipsas – lantanoidai. Darbe tirta Ce3+ įtaka α-pusvandenio gipso susidarymui. Sudaryta modelinė sistema: CaSO4·2H2O–Ce2(SO43×8H2O. Į sistemą įmaišytas toks Ce2(SO43×8H2O kiekis, kad Ce2O3 koncentracija būtų 0,1; 0,5 ir 1 % ir būtų artima fosfatinėse žaliavose esančiam jų kiekiui. Sistema apdorota hidroterminėmis sąlygomis 128 oC ir 138 oC temperatūroje, izoterminio išlaikymo trukmė – 3 h. Produktas gautas iškaitinus 400 °C temperatūroje. Atlikta produkto rentgeno spinduliuotės difrakcinė analizė, FT-IR spektrinė analizė ir mikroskopinė analizė (SEM. Gauti rezultatai parodė, kad kuo didesnis Ce3+ kiekis yra sistemoje, tuo daugiau nedehidratavusio dvivandenio gipso lieka gautame produkte, o susidariusio α- pusvandenio gipso kristalai yra smulkūs, neaiškios, neapibrėžtos formos. Taigi, galima teigti, kad Ce3+ turi neigiamą įtaką dvivandenio gipso dehidratacijai, t. y. α- pusvandenio gipso susidarymui, ir pusvandenio gipso kristalų morfologijai.DOI: http://dx.doi.org/10.5755/j01.ms.18.4.3102

  3. Yb and Er co-doped Y2Ce2O7 nanoparticles: synthesis and ...

    Indian Academy of Sciences (India)

    Xu et al 2010). In addition, Er3+ ion has abundant energy level structure, so green and red upconversion emissions can be realized in Er3+-doped materials. .... Ce. Count. Engergy (KeV). Ce. O Y. Yb. Ce. Cu. Er. Figure 2. Energy dispersive spectra of Yb3+ and Er3+ co-doped. Y2Ce2O7 nanoparticles prepared for 4 h at ...

  4. Structure and phase composition of Al-Ce-Cu system alloys in range of quasi-binary Al-Al8CeCu4 section

    International Nuclear Information System (INIS)

    Belov, N.A.; Khvan, A.V.

    2007-01-01

    The phase diagram of the Al-Cu-Ce system in the quasibinary section area of Al-Al 8 CeCu 4 has been investigated by metallographic, thermal, micro-X-ray spectral and X-ray structural analyses. The parameters of the eutectic reaction L→(Al)+CeCu 4 Al 8 : T=610 Deg C were found out; the composition was 14% Cu and 7% Ce. This eutectics is of a disperse structure and the ternary compound contained is capable of fragmentation and spheroidizing in the heating process (starting from 540 Deg C). It was demonstrated that the area of optimal (Al)+CeCu 4 Al 8 eutectics-based alloy compositions was within the narrow limits. That is related to the fact that at a comparatively little variation of the Cu:Ce=2 ratio solidus sharply decreases and, as a result, the crystallization interval considerably extends [ru

  5. Energy transfer from Ce3+ to Eu3+ through Tb3+ chain in YPO4:Ce3+/Tb3+/Eu3+ phosphors

    Science.gov (United States)

    Yang, Yuguo; Lv, Xianshun; Wei, Lei; Xu, Jianhua; Yu, Huajian; Hu, Yanyan; Zhang, Huadi; Liu, Bing; Wang, Xuping; Li, Qinggang

    2018-01-01

    We synthesized a series of YPO4:Ce3+/Tb3+/Eu3+ phosphors by a solid state reaction. All of phosphors have a single phase, showing that the doping ions could not change the phase of YPO4 host. The emission intensities of Ce3+, Tb3+ and Eu3+ ions clearly depend on the Tb3+ concentrations in YPO4:Ce3+/Tb3+/Eu3+ phosphors. The emission intensity of Ce3+ emission decreases gradually but the emission intensity of Eu3+ emission increases continuously with the increasing Tb3+ concentration because of the energy transfer from Ce3+ to Eu3+ through Tb3+. On the basis of the luminescent properties of YPO4:Ce3+/Tb3+/Eu3+ phosphors, the possible energy transfer mechanism was speculated.

  6. Site assessment

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Gómez Arranz, Paula

    This report describes the site assessment of given position in a given site, for a wind turbine with a well-defined hub height and rotor diameter. The analysis is carried out in accordance to IEC 61400-12-1 [1], and both an obstacle assessment and a terrain assessment are performed.......This report describes the site assessment of given position in a given site, for a wind turbine with a well-defined hub height and rotor diameter. The analysis is carried out in accordance to IEC 61400-12-1 [1], and both an obstacle assessment and a terrain assessment are performed....

  7. Site assessment

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Vesth, Allan

    This report describes the site assessment of given position in a given site, for a wind turbine with a well-defined hub height and rotor diameter. The analysis is carried out in accordance to IEC 61400-12-1 [1], and both an obstacle assessment and a terrain assessment are performed......This report describes the site assessment of given position in a given site, for a wind turbine with a well-defined hub height and rotor diameter. The analysis is carried out in accordance to IEC 61400-12-1 [1], and both an obstacle assessment and a terrain assessment are performed...

  8. Effect of Ce on solidification and mechanical properties of A360 alloy

    International Nuclear Information System (INIS)

    Voncina, Maja; Kores, Stanislav; Mrvar, Primoz; Medved, Jozef

    2011-01-01

    Highlights: → We investigated the effect of Ce addition on the AA A360 alloy. → The purpose is to study the variations that occur during solidification and precipitation with different Ce additions, as well as their effect on the mechanical properties. → Ce addition decreases the eutectic (α Al + Mg 2 Si) temperature and eutectic recalescence and also solidus temperature. → The precipitation enthalpy decreases with the Ce addition, while precipitation takes place more rapidly and intensively, indicating increased reaction kinetics. → The mechanical properties like hardness and tensile strength also increase with the Ce addition. - Abstract: The effect of Ce addition on the AA A360 (Al-10%Si-0.5%Mg) alloy was investigated using equilibrium thermodynamic calculation, thermal analysis, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The purpose is to study the variations that occur during solidification and precipitation with different Ce additions, as well as their effect on the mechanical properties. The results show that the Ce addition decreases the eutectic (α Al + Mg 2 Si) temperature. The solidus temperature also decreases with the increasing Ce addition. The precipitation enthalpy determined using DSC decreases with the Ce addition, while precipitation takes place more rapidly and intensively, indicating increased reaction kinetics. The mechanical properties like hardness and tensile strength also increase with the Ce addition. The phase that contributed to the hardness of the investigated alloy was composed of Al, Ce, Mg and Si.

  9. Laser-excited spectra of Lu2SiO5:Ce scintillator

    International Nuclear Information System (INIS)

    Liu Bo; Gu Mu; Qi Zeming; Shi Chaoshu; Yin, Min; Ren Guohao

    2007-01-01

    The emission spectra of Lu 2 SiO 5 :Ce single crystal under the excitation of 266 nm laser were investigated. The emission spectra of LSO single crystal show no temperature quenching from 20 to 300 K, under the excitation of 266 nm laser with 2 mJ pulse energy. With rising temperature, the Ce1 emission is slightly decreased, while the Ce2 emission is slightly increased. These results show the emissions of Ce1 and Ce2 is not only dependent on the concentration ratio but also influenced by the possible energy transfer processes, including Ce1 to Ce2, intrinsic STHs to Ce2 and the phonon-assisted transfer processes. The spectral thermal broadening and the spectral overlap become evident at high temperature, leading to the enhancement of energy transfer. When the excitation power lowers, the ratio of Ce1 and Ce2 emission increases, and is close to the Xe lamp ultraviolet (UV) excitation, suggesting that the energy transfer from Ce1 center to Ce2 center may be also dependent on the excitation power

  10. Study of structural and electronic transport properties of Ce-doped ...

    Indian Academy of Sciences (India)

    The structural and electronic transport properties of La1-CeMnO3 (=0.0-1.0) have been studied. All the samples exhibit orthorhombic crystal symmetry and the unit cell volume decreases with Ce doping. They also make a metal–insulator transition (MIT) and transition temperature increases with increase in Ce ...

  11. Redox enzyme-mimicking activities of CeO2nanostructures: Intrinsic influence of exposed facets.

    Science.gov (United States)

    Yang, Yushi; Mao, Zhou; Huang, Wenjie; Liu, Lihua; Li, Junli; Li, Jialiang; Wu, Qingzhi

    2016-10-17

    CeO 2 nanoparticles (NPs) have been well demonstrated as an antioxidant in protecting against oxidative stress-induced cellular damages and a potential therapeutic agent for various diseases thanks to their redox enzyme-mimicking activities. The Ce 3+ /Ce 4+ ratio and oxygen vacancies on the surface have been considered as the major originations responsible for the redox enzyme-mimicking activities of CeO 2 NPs. Herein, CeO 2 nanostructures (nanocubes and nanorods) exposed different facets were synthesized via a facile hydrothermal method. The characterizations by X-ray photoelectron spectroscopy, Raman spectroscopy, and UV-Vis spectroscopy show that the Ce 3+ /Ce 4+ ratio and oxygen vacancy content on the surfaces of as-synthesized CeO 2 nanostructures are nearly at the same levels. Meanwhile, the enzymatic activity measurements indicate that the redox enzyme-mimicking activities of as-synthesized CeO 2 nanostructures are greatly dependent on their exposed facets. CeO 2 nanocubes with exposed {100} facets exhibit a higher peroxidase but lower superoxide dismutase activity than those of the CeO 2 nanorods with exposed {110} facets. Our results provide new insights into the redox enzyme-mimicking activities of CeO 2 nanostructures, as well as the design and synthesis of inorganic nanomaterials-based artificial enzymes.

  12. Heteroaggregation, transformation and fate of CeO2 nanoparticles in wastewater treatment

    International Nuclear Information System (INIS)

    Barton, Lauren E.; Auffan, Melanie; Olivi, Luca; Bottero, Jean-Yves; Wiesner, Mark R.

    2015-01-01

    Wastewater Treatment Plants (WWTPs) are a key pathway by which nanoparticles (NPs) enter the environment following release from NP-enabled products. This work considers the fate and exposure of CeO 2 NPs in WWTPs in a two-step process of heteroaggregation with bacteria followed by the subsequent reduction of Ce(IV) to Ce(III). Measurements of NP association with solids in sludge were combined with experimental estimates of reduction rate constants for CeO 2 NPs in Monte Carlo simulations to predict the concentrations and speciation of Ce in WWTP effluents and biosolids. Experiments indicated preferential accumulation of CeO 2 NPs in biosolids where reductive transformation would occur. Surface functionalization was observed to impact both the distribution coefficient and the rates of transformation. The relative affinity of CeO 2 NPs for bacterial suspensions in sludge appears to explain differences in the observed rates of Ce reduction for the two types of CeO 2 NPs studied. - Highlights: • We combine experimental and computational methods to track CeO 2 NPs through WWTPs. • We investigate the importance of environmental transformations on NP exposure. • We estimate the concentrations of CeO 2 NPs and reductive transformation byproducts. - CeO 2 nanoparticles that are released to the waste stream will preferentially associate with the solid phase (∼96%), where they will undergo significant transformation (∼50%)

  13. Novel nanostructured CeO2 as efficient catalyst for energy and ...

    Indian Academy of Sciences (India)

    CeO2 and CeO2 based hetero-nanocomposites for their suitability to important catalytic and energy-related applications. Keywords. CeO2; morphology; catalysis; soot oxidation; CO oxidation; ethanol electro-oxidation. 1. Introduction .... glycol)-poly(propylene glycol)-poly(ethylene glycol). (P123, Sigma-Aldrich) with a ...

  14. Homogeneously dispersed CeO2 nanoparticles on exfoliated hexaniobate nanosheets

    Science.gov (United States)

    Marques, Thalles M. F.; Strayer, Megan E.; Ghosh, Anupama; Silva, Alexandre; Ferreira, Odair P.; Fujisawa, Kazunori; Alves da Cunha, Jose R.; Abreu, Guilherme J. P.; Terrones, Mauricio; Mallouk, Thomas E.; Viana, Bartolomeu C.

    2017-12-01

    Hexaniobate nanosheets derived from the parent compound K4Nb6O17 have been decorated with CeO2 nanoparticles by ion exchange with aqueous cerium (IV) solution. Very homogeneous CeO2 nanoparticle decoration of the hexaniobate sheets can be achieved by this method and the resulting composites may absorb visible light. HRTEM images show that ∼3.0 nm diameter CeO2 nanoparticles adhere to hexaniobate nanosheets that are exfoliated and then restacked prior to Ce deposition. The interfacial interaction between CeO2 nanoparticles and nanosheets would be due to an electrostatic attraction mechanism. Raman and XRD measurements have given strong evidence that CeO2 nanoparticles have fluorite structure. EDS, FTIR and XPS results suggest almost complete exchange of TBA+ and K+ by Ce4+. Cerium ion exchange on the acid exchanged parent compound, H2.9K1.1Nb6O17, revealed that the extent of Ce ion exchange is much greater in case of nanosheets, which may be rationalized by the larger surface area available after exfoliation. XPS measurements show that the ratio of Ce4+/Ce3+ is around 4.4, in agreement with the formation of fluorite structure (CeO2). Thus, these CeO2 nanoparticle/nanosheet composites may be useful for catalytic processes.

  15. AstroNomical Information System at CeSAM

    Science.gov (United States)

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

    2014-05-01

    AstroNomical Information System (ANIS), developed by the Centre de donnéeS Astrophysique de Marseille (CeSAM), is a generic tool aimed at facilitating and homogenizing the implementation of astronomical data of various kinds and in dedicated Information Systems. ANIS provides high level services like: 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, as well as download of catalogs and complete datasets. With ANIS, the CeSAM offers web access to VO compliant Information Systems for different projects VVDS, HeDAM, ExoDat, HST-COSMOS, etc.), including ancillary data that are cross-matched before ingestion.

  16. Gamma-ray relative energy response of Ce: YAG crystal

    International Nuclear Information System (INIS)

    Zhang Jianhua; Zhang Chuanfei; Hu Mengchun; Peng Taiping; Wang Zhentong; Tang Dengpan; Zhao Guangjun

    2010-01-01

    Gamma-ray relative energy response of Ce: YAG crystal, which is important for pulsed γ-ray measurement, was studied in this work.The Ce: YAG crystal, which was developed at Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, was aligned point by point with γ-rays scattered from an industrial 60 Co line source. The γ-ray relative energy response was calculated using the mass attenuation coefficient. The results show that the numerical calculation method of γ-ray relative energy response is reliable, and the experimental method with multi-energy point γ-ray by Compton scattering is also feasible, that can be used for checking up correctness of the numerical calculation results. (authors)

  17. 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.

  18. Ru 4 ion in CeO 2 (Ce 0.95 Ru 0.05 O 2− ): A non-deactivating ...

    Indian Academy of Sciences (India)

    A new WGS catalyst, Ce1−RuO2− (0 ≤ ≤ 0.1) was prepared by hydrothermal method using melamine as a complexing agent. The Catalyst does not require any pre-treatment. Among the several compositions prepared and tested, Ce0.95Ru0.05O2− (5% Ru4+ ion substituted in CeO2) showed very high WGS ...

  19. Nouvelle espèce des Syntomides (Lepidoptera Heterocera)

    NARCIS (Netherlands)

    Snellen, P.C.T.

    1886-01-01

    Quatre mâles frais et bien conservés de 58—64 millim. d’envergure. Cette nouvelle espèce, gigantesque pour une Syntomide, appartient au genre Automolis, tel qu’il a été défini par Herrich-Schäffer, dans son ouvrage »Sammlung aussereuropäischer Schmetterlinge” (p. 21); le nom est emprunté au bien

  20. Identification and Quality Assessment of Chrysanthemum Buds by CE Fingerprinting

    OpenAIRE

    Xing, Xiaoping; Li, Dan

    2015-01-01

    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 ...

  1. Optical spectroscopy of the Ce-doped multicomponent garnets

    International Nuclear Information System (INIS)

    Canimoglu, A.; Karabulut, Y.; Ayvacikli, M.; Muresan, L.E.; Perhaita, I.; Barbu-Tudoran, L.; Garcia Guinea, J.; Karali, T.; Can, N.

    2016-01-01

    Here, we report our results referring to the preparation of Ce doped Y 2.22 MgGa 2 Al 2 SiO 12 , Y 1.93 MgAl 4 SiO 12 and Y 2.22 Gd 0.75 Ga 2 Al 3 O 12 using solid state reaction at high temperature. Several complementary methods (i.e. powder x-ray diffraction (XRPD), energy dispersive analysis of X-rays (EDX), scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR)) were studied to examine the effects of the synthesis procedure on the morphology and structure. XRD analyses revealed that all compounds include yttrium aluminate phase with garnet structure. Cathodoluminescence (CL), radioluminescence (RL) and photoluminescence (PL) measurements were carried out for clarification of relationship between host lattice defects and the spectral luminescence emissions. Luminescence emission of phosphors is peaked at 530 nm assigned to 5d-4f transitions of the dopant Ce 3+ ions with a broad emission band in 400–700 nm range. Under electron irradiation, the emission spectrum of Ce doped (YGd) 3 Ga 2 Al 3 O 12 is well defined and has a characteristic fairly narrow and sharp emission band peaking at 312 nm and 624 nm corresponding to transition of 6 P 7/2 → 8 S 7/2 and 6 G J → 6 P J (Gd 3+ ), respectively. We suggest some of phosphors might be excellent phototherapy phosphor materials under electron excitation. - Highlights: • Ce-doped Multicomponent Garnets were prepared solid state reaction method. • The shape and size of phosphor particles were examined. • The narrow band UV B emission due to Gd 3+ ions were observed.

  2. 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.

  3. CeDAMar global database of abyssal biological sampling

    OpenAIRE

    Stuart, Carol T.; Arbizu, Pedro Martinez; Smith, Craig R.; Molodtsova, Tina; Brandt, Angelika; Etter, Ron J.; Escobar-briones, Elva; Fabri, Marie-claire; Rex, Michael A.

    2008-01-01

    The Census of the Diversity of Abyssal Marine Life (CeDAMar), a division of the Census of Marine Life, has compiled the first comprehensive global database of biological samples taken in the abyssal plains of the world ocean. It is an essential resource for planning future exploration of the abyss, for synthesizing patterns of biogeography and biodiversity, and for environmentally safe exploitation of natural resources. The database is described in this article, and made available to investig...

  4. Qu'est-ce que l'Univers ?

    CERN Document Server

    2001-01-01

    Les plus grans spécialistes français sont réunis dans ce quatrième volume. Ils éclairent les grandes questions que pose la cosmologie, le Système solaire, les étoiles et les galaxies, la Terre, les océans et le climat, la matière et son organisation, l'évolution des mathématiques, la complexité, les transformations chimiques.

  5. Temperature-independent photoluminescence response in ZnO:Ce ...

    Indian Academy of Sciences (India)

    2017-12-06

    Dec 6, 2017 ... tion of rare-earth ions. Nowadays, rare-earth-doped ZnO semiconductor is an interesting field of study because of its unique optical properties and promising applications in optoelectronic devices [13–19]. Since cerium oxide (CeO2) has a band gap of ∼3 eV and shows interesting prop- erties similar to that ...

  6. Scintillation properties of the Ce-doped multicomponent garnetepitaxial films

    Czech Academy of Sciences Publication Activity Database

    Průša, Petr; Kučera, M.; Mareš, Jiří A.; Hanuš, M.; Beitlerová, Alena; Onderišinová, Z.; Nikl, Martin

    2013-01-01

    Roč. 35, č. 12 (2013), s. 2444-2448 ISSN 0925-3467 R&D Projects: GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : scintillator * liquid phase epitaxy method * photoelectron yield * garnet * Ce 3+ Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.075, year: 2013 http://dx.doi.org/10.1016/j.optmat.2013.06.051

  7. Role of Ce-Mn substitution on structural, electrical and magnetic properties of W-type strontium hexaferrites

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Imran; Sadiq, Imran [Department of Physics, Bahauddin Zakariya University, Multan-60800 (Pakistan); Ashiq, Muhammad Naeem [Department of Chemistry, Bahauddin Zakariya University, Multan-60800 (Pakistan); Rana, Mazhar-Ud-Din, E-mail: mazharrana@bzu.edu.pk [Department of Physics, Bahauddin Zakariya University, Multan-60800 (Pakistan)

    2011-08-04

    Graphical abstract: The saturation magnetization and remanence increase with the Ce-Mn content and the maximum value is found for the sample Sr{sub 0.98}Ce{sub 0.02}Co{sub 2}Mn{sub 0.2}Fe{sub 15.8}O{sub 27} which suggest that this material can be used for high density recording media. Highlights: > The pure W-type hexaferrites materials are synthesized by the simple co-precipitation method and crystallite size is found in the range of 22.5-30 nm. The synthesized materials are in single magnetic domain as suggested by value of squareness ratio. The substitution of Ce-Mn increases the saturation magnetization and remanence which suggest that the synthesized materials can be used in high density recording media. - Abstract: W-type hexaferrites with nominal composition Sr{sub 1-x}Ce{sub x}Co{sub 2}Mn{sub y}Fe{sub 16-y}O{sub 27} (x = 0.00, 0.02, 0.04, 0.06 and y = 0.0, 0.2, 0.4, 0.6) has been synthesized by the chemical co-precipitation method. The effect of substitution of Ce at Sr and Mn at Fe site on the structural, magnetic and electrical properties has been investigated. The XRD patterns confirm single W-type hexaferrite phase and various parameters such as lattice constants (a and c), cell volume (V), crystallite size (D), X-ray density (d{sub x}), bulk density (d{sub b}) and porosity (P) were calculated from XRD data. The crystallite size is found in the range of 22.5-30 nm and this size is small enough to obtained suitable signal-to-noise ratio in high density recording media. The magnetic properties such as saturation magnetization, remanence, squareness ratio and coercivity were calculated from hysteresis loops and were observed to increase with increase in Ce-Mn concentration up to a certain substitution level. The resistivity showed interesting behavior with temperature, showing metal-to-semiconductor transition temperature. The increase in saturation and remanence suggest that the synthesized materials can be used in the high density recording media.

  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. F-centre luminescence in nanocrystalline CeO2

    International Nuclear Information System (INIS)

    Aškrabić, S; Dohčević-Mitrović, Z D; Araújo, V D; Ionita, G; De Lima, M M Jr; Cantarero, A

    2013-01-01

    Nanocrystalline CeO 2 powders were synthesized by two cost-effective methods: the self-propagating room temperature (SPRT) method and the precipitation method. Differently prepared samples exhibited different temperature-dependent photoluminescence (PL) in the ultraviolet and visible regions. The PL signals originated from different kinds of oxygen-deficient defect centres with or without trapped electrons (F 0 , F + or F ++ centres). The temperature-dependent PL spectra were measured using different excitation lines, below (457, 488 and 514 nm) or comparable (325 nm) to the ceria optical band gap energy, in order to investigate the positions of intragap localized defect states. Evidence for the presence of F + centres was supported by the signals observed in electron paramagnetic resonance (EPR) measurements. Based on PL and EPR measurements it was shown that F + centres dominate in the CeO 2 sample synthesized by the SPRT method, whereas F 0 centres are the major defects in the CeO 2 sample synthesized by the precipitation method. The luminescence from F ++ states, as shallow trap states, was registered in both samples. Energy level positions of these defect states in the ceria band gap were proposed. (paper)

  10. F-centre luminescence in nanocrystalline CeO2

    Science.gov (United States)

    Aškrabić, S.; Dohčević-Mitrović, Z. D.; Araújo, V. D.; Ionita, G.; de Lima, M. M., Jr.; Cantarero, A.

    2013-12-01

    Nanocrystalline CeO2 powders were synthesized by two cost-effective methods: the self-propagating room temperature (SPRT) method and the precipitation method. Differently prepared samples exhibited different temperature-dependent photoluminescence (PL) in the ultraviolet and visible regions. The PL signals originated from different kinds of oxygen-deficient defect centres with or without trapped electrons (F0, F+ or F++ centres). The temperature-dependent PL spectra were measured using different excitation lines, below (457, 488 and 514 nm) or comparable (325 nm) to the ceria optical band gap energy, in order to investigate the positions of intragap localized defect states. Evidence for the presence of F+ centres was supported by the signals observed in electron paramagnetic resonance (EPR) measurements. Based on PL and EPR measurements it was shown that F+ centres dominate in the CeO2 sample synthesized by the SPRT method, whereas F0 centres are the major defects in the CeO2 sample synthesized by the precipitation method. The luminescence from F++ states, as shallow trap states, was registered in both samples. Energy level positions of these defect states in the ceria band gap were proposed.

  11. Determination of the differences in oxidation potentials for the Pr3+/Pr2+ and Ce3+/Ce2+ pairs in halide melts

    International Nuclear Information System (INIS)

    Mikheev, N.B.; Auerman, L.N.; Rumer, I.A.; D'yachkova, R.A.

    1983-01-01

    Cocrystallization has been used with the (PrOCl)/sub s. ph/ - (PrCl 2 , PrCl 3 , SrCl 2 ) melt system to examine the dependence of the cerium(III) cocrystallization coefficient on the X/sub Pr 2+ /X/sub Pr 3+ / ratio in the melt. Measurement has been made in this way of the difference in oxidation potentials for the pairs Pr 3+ /Pr 2+ and Ce 3+ /Ce 2+ : ΔE/sub Pr 3+ /Pr 2+0 -E/sub Ce 3+ /Ce 2+ / 0 , which is 0.08 +/- 0.04 V for chloride

  12. Characteristics of CeCoIn5/Al/AlOx/Nb and CeCoIn5/Al/AlOx/Al tunnel junctions

    International Nuclear Information System (INIS)

    Nevirkovets, I.P.; Chernyashevskyy, O.; Petrovic, C.; Hu Rongwei; Ketterson, J.B.; Sarma, Bimal K.

    2009-01-01

    We report characteristics of CeCoIn 5 /Al/AlO x /Nb and CeCoIn 5 /Al/AlO x /Al tunnel junctions fabricated on the (0 0 1) surface of CeCoIn 5 crystal platelets. The main result of this work is the observation of a low Josephson current (as compared with that expected from the Ambegaokar-Baratoff formula), which is consistent with idea that the order parameter in the heavy-fermion superconductor CeCoIn 5 has unconventional pairing symmetry.

  13. 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.

  14. Solid-solution stability and preferential site-occupancy in (R-R′){sub 2}Fe{sub 14}B compounds

    Energy Technology Data Exchange (ETDEWEB)

    Colin, C. V.; Dempsey, N. M. [CNRS, Inst NEEL, F-38000 Grenoble (France); Univ. Grenoble Alpes, Inst NEEL, F-38000 Grenoble (France); Ito, M. [CNRS, Inst NEEL, F-38000 Grenoble (France); Univ. Grenoble Alpes, Inst NEEL, F-38000 Grenoble (France); Advanced Material Engineering Div., Toyota Motor Corporation, Susono 410-1193 (Japan); Yano, M. [Advanced Material Engineering Div., Toyota Motor Corporation, Susono 410-1193 (Japan); Suard, E. [Institut Laue-Langevin, CS 20156-38042 Grenoble cedex 9 (France); Givord, D. [CNRS, Inst NEEL, F-38000 Grenoble (France); Univ. Grenoble Alpes, Inst NEEL, F-38000 Grenoble (France); Instituto de Fisica, Universidade Federal do Rio de Janeiro, 21941-972 Rio de Janeiro (Brazil)

    2016-06-13

    The rare-earth (R) uniaxial anisotropy of R{sub 2}Fe{sub 14}B compounds with magnetic R atoms (e.g., Nd or Pr) is at the origin of the exceptional hard magnetic properties achieved in magnets based on these compounds. The uniaxial anisotropy found in Ce{sub 2}Fe{sub 14}B is attributed mainly to the magnetism of Fe. Ce is the most abundant R element and there has been much recent effort to fabricate magnets in which Ce is partially substituted for Nd. In the present neutron study of (R{sub 1−x}Ce{sub x}){sub 2}Fe{sub 14}B (R = La or Nd), Ce is found to enter the R{sub 2}Fe{sub 14}B phase over the entire composition range. The crystallographic parameters decrease with increasing Ce content and the Ce atoms preferentially occupy the smaller 4f sites. It is concluded that Ce in these (RR′){sub 2}Fe{sub 14}B compounds essentially maintains the intermediate valence character found in Ce{sub 2}Fe{sub 14}B. It is proposed that, in this intermediate valence state, Ce weakly contributes to uniaxial anisotropy, thus making a link with the fact that significant coercivity is preserved in Ce-substituted NdFeB magnets.

  15. miRSponge: a manually curated database for experimentally supported miRNA sponges and ceRNAs.

    Science.gov (United States)

    Wang, Peng; Zhi, Hui; Zhang, Yunpeng; Liu, Yue; Zhang, Jizhou; Gao, Yue; Guo, Maoni; Ning, Shangwei; Li, Xia

    2015-01-01

    In this study, we describe miRSponge, a manually curated database, which aims at providing an experimentally supported resource for microRNA (miRNA) sponges. Recent evidence suggests that miRNAs are themselves regulated by competing endogenous RNAs (ceRNAs) or 'miRNA sponges' that contain miRNA binding sites. These competitive molecules can sequester miRNAs to prevent them interacting with their natural targets to play critical roles in various biological and pathological processes. It has become increasingly important to develop a high quality database to record and store ceRNA data to support future studies. To this end, we have established the experimentally supported miRSponge database that contains data on 599 miRNA-sponge interactions and 463 ceRNA relationships from 11 species following manual curating from nearly 1200 published articles. Database classes include endogenously generated molecules including coding genes, pseudogenes, long non-coding RNAs and circular RNAs, along with exogenously introduced molecules including viral RNAs and artificial engineered sponges. Approximately 70% of the interactions were identified experimentally in disease states. miRSponge provides a user-friendly interface for convenient browsing, retrieval and downloading of dataset. A submission page is also included to allow researchers to submit newly validated miRNA sponge data. Database URL: http://www.bio-bigdata.net/miRSponge. © The Author(s) 2015. Published by Oxford University Press.

  16. Photocatalytic degradation of dye using CeO2/SCB composite catalysts

    Science.gov (United States)

    Channei, Duangdao; Nakaruk, Auppatham; Phanichphant, Sukon

    2017-08-01

    The main task of the present work is to enhance the photocatalytic degradation efficiency of methylene blue (MB) by using CeO2/sugarcane bagasse (SCB) composite catalysts. Homogeneous precipitation method was used to synthesis CeO2-SCB composite catalysts by adding SCB powder to precursor solution of Ce base-metal. The structural analytical data indicated the pure cubic fluorite structure of CeO2. Morphological images revealed the coating of CeO2 layer on high surface area of SCB core-shell. The chemical analysis presented spectrum of the Ce 3d in CeO2/SCB sample existed in the form of the Ce3 + and Ce4 + mixed- valence states. Optical spectra showed the shift of absorption edge towards longer visible region upon supporting CeO2 with SCB. The main chemical composition of the SCB was K, Ca, and Si. Furthermore, recombination of the photogenerated electrons and holes was identified by photoluminescence techniques (PL), the data suggested inhibition of electron-hole pairs recombination by the cations from SCB loaded in CeO2/SCB composite. Photocatalytic activity of CeO2/SCB catalyst was investigated via the degradation of MB under UV-A irradiation. Experimental kinetic data followed the pseudo-first order model. CeO2 supported with SCB adsorbent had higher photocatalytic activity in dye wastewater treatment compared to the pure CeO2. The proposed mechanism explaining the high photocatalytic efficiency of CeO2/SCB was associated with high surface properties and the suppression of recombination of the photogenerated electron-hole pairs by the SCB adsorbent.

  17. Microstructures and luminescent properties of Ce-doped transparent mica glass-ceramics

    International Nuclear Information System (INIS)

    Taruta, Seiichi; Iwasaki, Yoshitomo; Nishikiori, Hiromasa; Yamakami, Tomohiko; Yamaguchi, Tomohiro; Kitajima, Kunio; Okada, Kiyoshi

    2012-01-01

    Highlights: ► Ce-doped transparent glass-ceramics and their parent glasses. ► TEM and STEM images for the microstructures. ► Each mica crystal did not contain Ce uniformly. ► Emission due to Ce 3+ ions in the glass phase and/or Ce 3+ ions in the mica crystals. - Abstract: Transparent mica glass-ceramics were prepared by heating parent glasses that had been doped with 0.5–15 mol% CeO 2 . During the melting and heat treatment, Ce 4+ ions in the specimens were reduced to Ce 3+ ions, and one or both of these ion species were then replaced with Li + ions in the interlayers of the separated mica crystals. However, scanning transmission electron microscope (STEM) and Z-contrast imaging revealed that the mica crystals did not contain the same amount of Ce. On excitation at 254 nm, the parent glasses and glass-ceramics emitted blue light, which originated from the 5d to 4f transition of the Ce 3+ ions. The emission of the glass-ceramic containing a smaller amount of Ce was attributed to the Ce 3+ ions in both the glass phase and the mica crystals, whereas that of the glass-ceramics containing a larger amount of Ce was caused mainly by Ce 3+ ions in the mica crystals. The dependence of the emission band of the parent glasses on the amount of Ce was a unique feature of the Ce-doped transparent mica glass-ceramics and was not observed in previous studies of Eu-doped parent glasses and mica glass-ceramics.

  18. 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. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Site Calibration

    DEFF Research Database (Denmark)

    Kock, Carsten Weber; Vesth, Allan

    This Site Calibration report is describing the results of a measured site calibration for a site in Denmark. The calibration is carried out by DTU Wind Energy in accordance with Ref.[3] and Ref.[4]. The measurement period is given. The site calibration is carried out before a power performance...... measurement on a given turbine to clarify the influence from the terrain on the ratio between the wind speed at the center of the turbine hub and at the met mast. The wind speed at the turbine is measured by a temporary mast placed at the foundation for the turbine. The site and measurement equipment...... is detailed described in [1] and [2]. All parts of the sensors and the measurement system have been installed by DTU Wind Energy....

  20. Touristes, tourismes : ce que des sciences sociales en disent (et ce que j’en pense.

    Directory of Open Access Journals (Sweden)

    Éric Boutouyrie

    2005-04-01

    Full Text Available Dernièrement, un ouvrage de l’équipe de géographes Mit (Équipe Mit , 2003 de l’Université de Paris 7 s’est fait l’écho d’un texte du philosophe et urbaniste Thierry Paquot publié en juillet 2001 dans le numéro 568 du Monde Diplomatique . Ce texte, intitulé « La tyrannie douce de l’air conditionné », se présentait comme une courte et dense réflexion sur le tourisme et le touriste. Les membres de l’Équipe Mit l’épinglent dans un chapitre consacré à ce ...

  1. CeBr3 as a room-temperature, high-resolution gamma-ray detector

    International Nuclear Information System (INIS)

    Guss, Paul; Reed, Michael; Yuan Ding; Reed, Alexis; Mukhopadhyay, Sanjoy

    2009-01-01

    Cerium bromide (CeBr 3 ) has become a material of interest in the race for high-resolution gamma-ray spectroscopy at room temperature. This investigation quantified the potential of CeBr 3 as a room-temperature, high-resolution gamma-ray detector. The performance of CeBr 3 crystals was compared to other scintillation crystals of similar dimensions and detection environments. Comparison of self-activity of CeBr 3 to cerium-doped lanthanum tribromide (LaBr 3 :Ce) was performed. Energy resolution and relative intrinsic efficiency were measured and are presented.

  2. The γ rays sensitivity measurement of CeF3 scintillator detector

    International Nuclear Information System (INIS)

    Hu Mengchun; Zhou Dianzhong; Li Rurong; Wang Zhentong; Yang Hongqiong; Zhang Jianhua; Hu Qingyuan; Peng Taiping

    2003-01-01

    The CeF 3 is an abio-scintillator developed in recent years, which are insensitive to neutron and sensitive to gamma rays and respond quickness. The relationship of CeF 3 scintillation detector gamma rays sensitivity with the change of crystal thickness was measured. The CeF 3 scintillation detector is composed by high liner current photomultiplier tube of CHφT3, CHφT5 and CeF 3 scintillator. The detector gamma rays sensitivity of purple photocell and common photocell with CeF 3 scintillator were measured too

  3. Controlled hydrothermal synthesis of CeO{sub 2} nanospheres and their excellent magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Xiaofei [Suzhou University, Anhui Key Laboratory of Spintronics and Nanomaterials Research, Suzhou, Anhui (China)

    2017-04-15

    Monodisperse spherical CeO{sub 2} nanostructures with irregular and rough surfaces have successfully been synthesized via a facile hydrothermal technology. XRD, SEM, XPS, Raman scattering, and M-H curves were employed to characterize the samples. The results showed that the spherical CeO{sub 2} nanostructures have a cubic fluorite structure and that there are Ce{sup 3+} ions and oxygen vacancies in the surface of the samples. The M-H curve of CeO{sub 2} nanospheres exhibits excellent room-temperature ferromagnetism (RT-FM), which is likely ascribed to the effects of the Ce{sup 3+} ions and oxygen vacancies. (orig.)

  4. Controlled hydrothermal synthesis of CeO2 nanospheres and their excellent magnetic properties

    Science.gov (United States)

    Niu, Xiaofei

    2017-04-01

    Monodisperse spherical CeO2 nanostructures with irregular and rough surfaces have successfully been synthesized via a facile hydrothermal technology. XRD, SEM, XPS, Raman scattering, and M-H curves were employed to characterize the samples. The results showed that the spherical CeO2 nanostructures have a cubic fluorite structure and that there are Ce3+ ions and oxygen vacancies in the surface of the samples. The M-H curve of CeO2 nanospheres exhibits excellent room-temperature ferromagnetism (RT-FM), which is likely ascribed to the effects of the Ce3+ ions and oxygen vacancies.

  5. The stable Ce.sup.4+./sup. center: a new tool to optimize Ce-doped oxide scintillators

    Czech Academy of Sciences Publication Activity Database

    Nikl, Martin; Babin, Vladimir; Pejchal, Jan; Laguta, Valentyn; Buryi, Maksym; Mareš, Jiří A.; Kamada, K.; Kurosawa, S.; Yoshikawa, A.; Pánek, D.; Parkman, T.; Brůža, Petr; Mann, K.; Müller, M.

    2016-01-01

    Roč. 63, č. 2 (2016), s. 433-438 ISSN 0018-9499 R&D Projects: GA ČR GJ15-18300Y; GA MŠk(CZ) LG13029 Institutional support: RVO:68378271 Keywords : Ce 4+ * gamma-ray detection * LuAG * scintillator * X-ray detection Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.171, year: 2016

  6. Diclofenac degradation in water by FeCeOx catalyzed H2O2: Influencing factors, mechanism and pathways.

    Science.gov (United States)

    Chong, Shan; Zhang, Guangming; Zhang, Nan; Liu, Yucan; Huang, Ting; Chang, Huazhen

    2017-07-15

    The degradation of diclofenac in a like Fenton system, FeCeO x -H 2 O 2 , was studied in details. The influencing factors, reaction kinetics, reaction mechanism and degradation pathways of diclofenac were investigated. The optimum conditions were at a solution pH of 5.0, H 2 O 2 concentration of 3.0mmol/L, diclofenac initial concentration of 0.07mmol/L, FeCeO x dosage of 0.5g/L, and 84% degradation of diclofenac was achieved within 40min. The kinetics of FeCeO x catalyzed H 2 O 2 process involved adsorption-dominating and degradation-dominating stages and fitted pseudo-second order model and pseudo-first order model, respectively. Singlet oxygen 1 O 2 was the primary intermediate oxidative species in the degradation process; superoxide radical anion O 2 - also participated in the reaction. The surface cerium and iron sites and the oxygen vacancies in the FeCeO x catalyst were proposed to play an important role in H 2 O 2 decomposition and active species generation. The detected intermediates were identified as hydroxylated derivatives (m/z of 310, 326 and 298), quinone imine compounds (m/z of 308, 278 and 264) and hydroxyl phenylamine (m/z of 178). The majority intermediates were hydroxylated derivatives and the minority was hydroxyl phenylamine. The degradation pathways were proposed to involve hydroxylation, decarboxylation, dehydrogenation and CN bond cleavage. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Nanocrystalline Mn-Mo-Ce Oxide Anode Doped Rare Earth Ce and Its Selective Electro-catalytic Performance

    Directory of Open Access Journals (Sweden)

    SHI Yan-hua

    2017-09-01

    Full Text Available The anode oxide of nanocrystalline Mn-Mo-Ce was prepared by anode electro-deposition technology, and its nanostructure and selective electro-catalytic performance were investigated using the SEM, EDS, XRD, HRTEM, electrochemical technology and oxygen evolution efficiency testing. Furthermore, the selective electro-catalytic mechanism of oxygen evolution and chlorine depression was discussed. The results show that the mesh-like nanostructure Mn-Mo-Ce oxide anode with little cerium doped is obtained, and the oxygen evolution efficiency for the anode in the seawater is 99.51%, which means a high efficiency for the selective electro-catalytic for the oxygen evolution. Due to the structural characteristics of γ-MnO2, the OH- ion is preferentially absorbed, while Cl- absorption is depressed. OH- accomplishes the oxygen evolution process during the valence transition electrocatalysis of Mn4+/Mn3+, completing the selective electro-catalysis process. Ce doping greatly increases the reaction activity, and promotes the absorption and discharge; the rising interplanar spacing between active (100 crystalline plane promotes OH- motion and the escape of newborn O2, so that the selective electro-catalytic property with high efficient oxygen evolution and chlorine depression is achieved from the nano morphology effect.

  8. Tetragonal Ce-based Ce-Sm(Fe, Co, Ti){sub 12} alloys for permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Cid, Andres; Salazar, Daniel [BCMaterials, Bizkaia Science and Tecnology Park, 48160 Derio (Spain); Gabay, Aleksandr M.; Hadjipanayis, George C. [Department of Physics and Astronomy, University of Delaware, Newark, DE, 19716 (United States); Barandiaran, Jose Manuel [BCMaterials, Bizkaia Science and Tecnology Park, 48160 Derio (Spain); Department of Electricity and Electronics, University Basque Country (UPV/EHU), 48080 Bilbao (Spain)

    2016-12-15

    Abundance and relatively low cost of Ce provide a great incentive for its use in rare-earth permanent magnets. It has been recently reported that the tetragonal Ce(Fe,Co,Ti)12 compounds may exhibit application-worthy intrinsic magnetic properties. In this work the effect of the α-Fe phase formation due to the evaporation of Sm during alloy fabrication has been studied, as a previous step in the attempt to convert the intrinsic magnetic properties into functional properties of a permanent magnet. Ce{sub 0.5}Sm{sub 0.5}Fe{sub 9}Co{sub 2}Ti alloys based on the ThMn12-type crystal structure have been synthesized via melt-spinning with different Sm content. Coercive fields between 2.8 and 1.4 kOe have been found for α-Fe phase contents between 8 and 46% in volume, showing the influence of the α-Fe phase on the coercivity and exchange coupling between the hard and soft phase. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Effect of cerium on the corrosion behaviour of sintered (Nd,Ce)FeB magnet

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lijing [CAS Key Laboratory of Magnetic Materials and Devices, Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Bi, Mengxue [CAS Key Laboratory of Magnetic Materials and Devices, Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Nano Science and Technology Institute, University of Science and Technology of China, Hefei 230026 (China); Jiang, Jianjun; Ding, Xuefeng [CAS Key Laboratory of Magnetic Materials and Devices, Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Zhu, Minggang; Li, Wei [Functional Materials Research Institute, Central Iron & Steel Research Institute, Beijing 100081 (China); Lv, Zhongshan [Ningbo Shuo Teng new material Co., Ltd., Cixi 315301 (China); Song, Zhenlun, E-mail: songzhenlun@nimte.ac.cn [CAS Key Laboratory of Magnetic Materials and Devices, Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2017-06-15

    Highlights: • A little Ce could promote the magnets for a better corrosion resistance. • With increased Ce contents, the corrosion resistances of magnets decrease. • As the corrosion developed, the magnetic properties decreased. - Abstract: For the balanced consumption of rare-earth elements, cerium (Ce) was partially used for NdFeB magnets instead of Nd. The corrosion behaviour of the (Nd,Ce)FeB magnet with different Ce contents in 3.5% NaCl solution was investigated by SEM, XRD, EDS and electrochemical tests. After immersion, the weight loss was calculated and the magnetic properties of the samples were measured. Results showed that Ce affected the corrosion of the (Nd,Ce)FeB magnet. Compared with the NdFeB magnet without Ce but of the same grade as the magnetic energy product, (Nd,Ce)FeB magnet showed better corrosion resistance. With increased Ce content, the corrosion resistances and magnetic properties of (Nd,Ce)FeB magnets were investigated.

  10. Numerical simulation of the geometrical-optics reduction of CE2 and comparisons to quasilinear dynamics

    Science.gov (United States)

    Parker, Jeffrey B.

    2018-05-01

    Zonal flows have been observed to appear spontaneously from turbulence in a number of physical settings. A complete theory for their behavior is still lacking. Recently, a number of studies have investigated the dynamics of zonal flows using quasilinear (QL) theories and the statistical framework of a second-order cumulant expansion (CE2). A geometrical-optics (GO) reduction of CE2, derived under an assumption of separation of scales between the fluctuations and the zonal flow, is studied here numerically. The reduced model, CE2-GO, has a similar phase-space mathematical structure to the traditional wave-kinetic equation, but that wave-kinetic equation has been shown to fail to preserve enstrophy conservation and to exhibit an ultraviolet catastrophe. CE2-GO, in contrast, preserves nonlinear conservation of both energy and enstrophy. We show here how to retain these conservation properties in a pseudospectral simulation of CE2-GO. We then present nonlinear simulations of CE2-GO and compare with direct simulations of quasilinear (QL) dynamics. We find that CE2-GO retains some similarities to QL. The partitioning of energy that resides in the zonal flow is in good quantitative agreement between CE2-GO and QL. On the other hand, the length scale of the zonal flow does not follow the same qualitative trend in the two models. Overall, these simulations indicate that CE2-GO provides a simpler and more tractable statistical paradigm than CE2, but CE2-GO is missing important physics.

  11. Luminescent and scintillation properties of the Ce3+ doped Y3−xLuxAl5O12:Ce single crystalline films

    International Nuclear Information System (INIS)

    Zorenko, Yu.; Gorbenko, V.; Zorenko, T.; Popielarski, P.; Mosińska, L.; Fedorov, A.

    2016-01-01

    The work is related to the investigation of scintillation and luminescent properties of single crystalline films (SCF) of solid solutions of Ce 3+ doped Y 3−x Lu x Al 5 O 12 :Ce garnets with x value in the 0–3 range. We have shown a possibility of realization of high-energy shift of the Ce 3+ ion emission spectrum in these garnets up to 22 nm. We have also found that the light yield of the radioluminescence under α-particle excitation of LuAG:Ce SCF can exceed by 1.3 times the corresponding values for the YAG:Ce SCF counterpart. For investigation of the luminescent properties of Y 3−x Lu x Al 5 O 12 :Ce SCF at different x values the luminescent spectroscopy of these SCFs under excitation by synchrotron radiation in the VUV range was performed. - Highlights: • Single crystalline films of Y 3−x Lu x Al 5 O 12 garnets at x=0–3.0 were grown by LPE method onto YAG substrates. • Lattice constant of Y 3−x Lu x Al 5 O 12 :Ce film and the film/substrate misfit changed linearly with increasing of Lu content in the x=0–3.0 range. • High-energy shift of the Ce 3+ emission up to 22 nm in Y 3−x Lu x Al 5 O 12 film with increasing of Lu content in the x=0–3.0 range. • Light yield of Y 3−x Lu x Al 5 O 12 :Ce film decreases in the x=0–1.8 range and increases in the x=1.8–3.0 range. • Scintillation LY of Lu 3 Al 5 O 12 :Ce film can exceed by 1.3 times the LY for YAG:Ce film counterpart.

  12. Study of Ce-Cu mixed oxide catalysts by in situ electrical conductivity measurements.

    Science.gov (United States)

    Popescu, Ionel; Piumetti, Marco; Bensaid, Samir; Marcu, Ioan-Cezar

    2017-12-06

    Three Ce-Cu mixed oxides, namely Ce 0.95 Cu 0.05 , Ce 0.6 Cu 0.4 and Ce 0.15 Cu 0.85 , along with pure CeO 2 and CuO were characterized by in situ electrical conductivity measurements. Their electrical conductivity was studied as a function of temperature and oxygen partial pressure, and was followed with time during successive exposure to air, nitrogen and different gaseous mixtures containing propane as a VOC model molecule, under conditions close to those of their catalytic applications. CeO 2 and CuO appeared to be n-type and p-type semiconductors, respectively, while the semiconducting behavior of the Ce-Cu mixed oxides depended on the oxide composition. The semiconductive and redox properties of the samples were correlated with their catalytic behavior in CO oxidation, ethene total oxidation and soot combustion.

  13. Method for removing trace contaminants from multicurie amounts of 144Ce

    International Nuclear Information System (INIS)

    Wagner, J.A.; Kanapilly, G.M.

    1976-01-01

    Removal of contaminants from stock solutions of 144 Ce(III) was required for large quantities of 144 Ce prior to incorporation into fused aluminosilicate particles for inhalation toxicology studies. Since available procedures for purification of 144 Ce could not be readily adapted to our laboratory conditions and requirements, a simple procedure was developed to purify 144 Ce in multicurie quantities of 144 Ce(III). This procedure consists of separation of 144 Ce from contaminants by precipitation and filtrations at different pH. Its simplicity and efficacy in providing a stock solution that would readily exchange into montmorillonite clay was demonstrated when it was used during the preparation of large amounts of 144 Ce in fused aluminosilicate particles

  14. Facile preparation of self-healing superhydrophobic CeO2 surface by electrochemical processes

    Science.gov (United States)

    Nakayama, Katsutoshi; Hiraga, Takuya; Zhu, Chunyu; Tsuji, Etsushi; Aoki, Yoshitaka; Habazaki, Hiroki

    2017-11-01

    Herein we report simple electrochemical processes to fabricate a self-healing superhydrophobic CeO2 coating on Type 304 stainless steel. The CeO2 surface anodically deposited on flat stainless steel surface is hydrophilic, although high temperature-sintered and sputter-deposited CeO2 surface was reported to be hydrophobic. The anodically deposited hydrophilic CeO2 surface is transformed to hydrophobic during air exposure. Specific accumulation of contaminant hydrocarbon on the CeO2 surface is responsible for the transformation to hydrophobic state. The deposition of CeO2 on hierarchically rough stainless steel surface produces superhydrophobic CeO2 surface, which also shows self-healing ability; the surface changes to superhydrophilic after oxygen plasma treatment but superhydrophobic state is recovered repeatedly by air exposure. This work provides a facile method for preparing a self-healing superhydrophobic surface using practical electrochemical processes.

  15. Construction of g-C3N4/CeO2/ZnO ternary photocatalysts with enhanced photocatalytic performance

    Science.gov (United States)

    Yuan, Yuan; Huang, Gui-Fang; Hu, Wang-Yu; Xiong, Dan-Ni; Zhou, Bing-Xin; Chang, Shengli; Huang, Wei-Qing

    2017-07-01

    Promoting the spatial separation of photoexcited charge carriers is of paramount significance for photocatalysis. In this work, binary g-C3N4/CeO2 nanosheets are first prepared by pyrolysis and subsequent exfoliation method, then decorated with ZnO nanoparticles to construct g-C3N4/CeO2/ZnO ternary nanocomposites with multi-heterointerfaces. Notably, the type-II staggered band alignments existing between any two of the constituents, as well as the efficient three-level transfer of electron-holes in unique g-C3N4/CeO2/ZnO ternary composites, leads to the robust separation of photoexcited charge carriers, as verified by its photocurrent increased by 8 times under visible light irradiation. The resulting g-C3N4/CeO2/ZnO ternary nanocomposites unveil appreciably increased photocatalytic activity, faster than that of pure g-C3N4, ZnO and g-C3N4/CeO2 by a factor of 11, 4.6 and 3.7, respectively, and good stability toward methylene blue (MB) degradation. The remarkably enhanced photocatalytic activity of g-C3N4/CeO2/ZnO ternary heterostructures can be interpreted in terms of lots of active sites of nanosheet shapes and the efficient charge separation owing to the resulting type-II band alignment with more than one heterointerface and the efficient three-level electron-hole transfer. A plausible mechanism is also elucidated via active species trapping experiments with various scavengers, which indicating that the photogenerated holes and •OH radicals play a crucial role in photodegradation reaction under visible light irradiation. This work suggest that the rational design and construction of type II multi-heterostructures is powerful for developing highly efficient and reusable visible-light photocatalysts for environmental purification and energy conversion.

  16. Manganese/cerium clusters spanning a range of oxidation levels and CeMn(8), Ce(2)Mn(4), and Ce(6)Mn(4) nuclearities: structural, magnetic, and EPR properties.

    Science.gov (United States)

    Lampropoulos, Christos; Thuijs, Annaliese E; Mitchell, Kylie J; Abboud, Khalil A; Christou, George

    2014-07-07

    The syntheses, structures, and magnetic properties are reported for three new Ce/Mn clusters with different Ce/Mn ratios: [Ce6Mn4O12(O2CMe)10(NO3)4(py)4] (py = pyridine) (1), [CeMn8O8(O2CCH2(t)Bu)12(DMF)14] (DMF = dimethylformamide) (2), and [Ce2Mn4O2(O2CMe)6(NO3)4(hmp)4] (3; hmp(-) is the anion of 2-(hydroxymethyl)pyridine). 1 and 2 were obtained from the reaction of Ce(IV) with [Mn12O12(O2CMe)16(H2O)4] (Mn(III)8Mn(IV)4) and [Mn8O2(O2CCH2(t)Bu)14((t)BuCH2CO2H)4] (Mn(II)6Mn(III)2), respectively, whereas 3 resulted from the oxidation of Mn(II) acetate with Ce(IV) in the presence of hmpH. Cluster 1 possesses an unusual [Ce6Mn4O12](14+) core topology consisting of a [Ce6O8] face-capped octahedron, which is face-fused at each end to a [Ce(IV)2Mn(III)Mn(IV)O4] cubane. Cluster 2 possesses a nonplanar, saddlelike loop of eight Mn(III) atoms bridged by eight μ3-O(2-) ions to a central Ce(IV) atom. Cluster 3 is similar to 1 in possessing an octahedral core, but this is now a [Ce2Mn4] octahedron consisting of a Ce(III) atom on either side of a Mn4 parallelogram, with the metal atoms bridged by two μ4-O(2-) ions, the alkoxide arms of four hmp(-) groups, and six acetates. Clusters 1, 2, and 3 are thus at the Ce(IV)6Mn(III)2Mn(IV)2, Ce(IV)Mn(III)8, and Ce(III)2Mn(III)4 oxidation levels, respectively. Variable-temperature, solid-state direct current (DC) and alternating current (AC) magnetization studies on 1-3 in the 5.0-300 K range revealed predominantly antiferromagnetic exchange interactions within the complexes. For 1, fitting of the DC data to the theoretical expression for a dinuclear Mn(III)Mn(IV) complex derived using the Van Vleck equation and an isotropic spin Hamiltonian (ℋ = -2JŜi·Ŝj convention) gave a value for the exchange coupling parameter (J) of -60.4(7) cm(-1) and a Landé factor g = 2.00(1), indicating an S = 1/2 ground state. For 2, both DC and AC data indicate an S = 0 ground state, which is unprecedented for a member of the CeMn8 family and now

  17. Phase Equilibria and Magnetic Phases in the Ce-Fe-Co-B System

    Directory of Open Access Journals (Sweden)

    Tian Wang

    2016-12-01

    Full Text Available Ce-Fe-Co-B is a promising system for permanent magnets. A high-throughput screening method combining diffusion couples, key alloys, Scanning Electron Microscope/Wavelength Dispersive X-ray Spectroscope (SEM/WDS, and Magnetic Force Microscope (MFM is used in this research to understand the phase equilibria and to explore promising magnetic phases in this system. Three magnetic phases were detected and their homogeneity ranges were determined at 900 °C, which were presented by the formulae: Ce2Fe14−xCoxB (0 ≤ x ≤ 4.76, CeCo4−xFexB (0 ≤ x ≤ 3.18, and Ce3Co11−x FexB4 (0 ≤ x ≤ 6.66. The phase relations among the magnetic phases in this system have been studied. Ce2(Fe, Co14B appears to have stronger magnetization than Ce(Co, Fe4B and Ce3(Co, Fe11B4 from MFM analysis when comparing the magnetic interactions of selected key alloys. Also, a non-magnetic CeCo12−xFexB6 (0 ≤ x ≤ 8.74 phase was detected in this system. A boron-rich solid solution with Ce13FexCoyB45 (32 ≤ x ≤ 39, 3 ≤ y ≤ 10 chemical composition was also observed. However, the crystal structure of this phase could not be found in the literature. Moreover, ternary solid solutions ε1 (Ce2Fe17−xCox (0 ≤ x ≤ 12.35 and ε2 (Ce2Co17−xFex (0 ≤ x ≤ 3.57 were found to form between Ce2Fe17 and Ce2Co17 in the Ce-Fe-Co ternary system at 900 °C.

  18. Ultraviolet and near-infrared luminescence of LaBO3:Ce3+,Yb3+

    Science.gov (United States)

    Wei, Heng-Wei; Shao, Li-Ming; Jiao, Huan; Jing, Xi-Ping

    2018-01-01

    Ce3+ or Yb3+ singly doped LaBO3 and Ce3+-Yb3+ co-doped LaBO3 were prepared by conventional solid state reactions at 1100 °C and their photoluminescence (PL) properties were investigated. The emission spectrum of LaBO3:Ce3+,Yb3+ contains both the Ce3+ ultraviolet (UV) emissions (355 nm and 380 nm) and the Yb3+ near infrared (NIR) emission (975 nm) when excited by the UV light at 270 nm. By using the data of the Ce3+ decay curves and the PL intensities of both Ce3+ and Yb3+, the energy transfer efficiency (η) from Ce3+ to Yb3+, the actual energy transfer efficiency (AE) and the quantum efficiency (Q) of the Yb3+ emission were calculated. In the Ce3+-Yb3+ co-doped LaBO3, Ce3+ can transfer its absorbed energy to Yb3+ efficiently (η can be over 60%), and Yb3+ shows the Q value over 50% when it accepts the energy from Ce3+, which results in the low AE value ∼30%. The energy transfer process from Ce3+ to Yb3+ may be understood by the charge transfer mechanism: Ce3+ + Yb3+ ↔ Ce4+ + Yb2+. Particularly the Ce3+-Yb3+ co-doped LaBO3 phosphor gives the emissions mainly in the UV range and the NIR range with a portion of visible emissions in eye-insensitive range. This unique property may be suitable for applications in anti-counterfeiting techniques and public security affairs.

  19. Site development

    International Nuclear Information System (INIS)

    Noack, J.

    1975-01-01

    The subject of this paper is a general view over all necessary considerations to develop the site after it has been chosen and before starting with the construction of a nuclear power plant. (orig./RW) [de

  20. Site selection

    International Nuclear Information System (INIS)

    Olsen, C.W.

    1983-07-01

    The conditions and criteria for selecting a site for a nuclear weapons test at the Nevada Test Site are summarized. Factors considered are: (1) scheduling of drill rigs, (2) scheduling of site preparation (dirt work, auger hole, surface casing, cementing), (3) schedule of event (when are drill hole data needed), (4) depth range of proposed W.P., (5) geologic structure (faults, Pz contact, etc.), (6) stratigraphy (alluvium, location of Grouse Canyon Tuff, etc.), (7) material properties (particularly montmorillonite and CO 2 content), (8) water table depth, (9) potential drilling problems (caving), (10) adjacent collapse craters and chimneys, (11) adjacent expended but uncollapsed sites, (12) adjacent post-shot or other small diameter holes, (13) adjacent stockpile emplacement holes, (14) adjacent planned events (including LANL), (15) projected needs of Test Program for various DOB's and operational separations, and (16) optimal use of NTS real estate

  1. Superfund Sites

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This layer represents active Superfund Sites published by the Environmental Protection Agency (EPA). These data were extracted from the Superfund Enterprise...

  2. Thermoelectric transport properties of nanostructured FeSb 2 and Ce-based heavy-fermions CeCu and CeAl 3

    Science.gov (United States)

    Pokharel, Mani R.

    Thermoelectric (TE) energy conversion is an all-solid-state technology which can convert waste thermal energy into useful electric power and cool ambience without using harmful gases like CFC. Due to their several advantages over traditional energy conversion technologies, thermoelectric generators (TEG) and coolers (TEC) have drawn enormous research efforts. The objective of this work is to find promising materials for thermoelectric cooling applications and optimize their thermoelectric performances. Finding a material with a good value for the thermoelectric figure-of-merit (ZT) at cryogenic temperatures, specifically below 77 K, has been of great interest. This work demonstrates that FeSb2 1, CeCu6 2 and CeAl3 3, all belonging to a class of materials with strongly correlated electron behavior; exhibit promising thermoelectric properties below 77 K. In general, ZT of a TE material can be increased using two basic approaches: lattice thermal conductivity reduction and power factor (PF) enhancement. The results of this study indicate that nanostructuring effectively decreases the thermal conductivity of FeSb2, CeCu6 and CeAl 3 leading to improved ZT. The approach of introducing point-defect scattering to further reduce the thermal conductivity is successfully implemented for Te-substituted FeSb2 nanostructured samples 4. A semiconductor/metal interface has long been proposed to exhibit enhanced thermoelectric properties. We use this technique by introducing Ag-nanoparticles in the host FeSb2 which further increases ZT by 70% 5. Additionally, a detailed investigation is made on the phonon-drag effect as a possible mechanism responsible for the large value of the Seebeck coefficient of FeSb2 6. We show that the phonon-drag mechanism contributes significantly to the large Seebeck effect in FeSb2 and hence this effect cannot be minor as was proposed in literatures previously. A model based on Kapitza-resistance and effective medium approach (EMA) is used to analyze

  3. Effects of Ce3+ concentration, beam voltage and current on the cathodoluminescence intensity of SiO2: Pr3+–Ce3+ nanophosphor

    CSIR Research Space (South Africa)

    Mhlongo, GH

    2011-02-01

    Full Text Available SiO2:Pr3+–Ce3+ phosphor powders were successfully prepared using a sol–gel process. The concentration of Pr3+ was fixed at 0.2 mol% while that of Ce3+ was varied in the range of 0.2–2 mol%. High resolution transmission electron microscopy (HRTEM...

  4. Abnormal variation of magnetic properties with Ce content in (PrNdCe)2Fe14B sintered magnets prepared by dual alloy method

    Science.gov (United States)

    Xue-Feng, Zhang; Jian-Ting, Lan; Zhu-Bai, Li; Yan-Li, Liu; Le-Le, Zhang; Yong-Feng, Li; Qian, Zhao

    2016-05-01

    Resource-saving (PrNdCe)2Fe14B sintered magnets with nominal composition (PrNd)15-x Ce x Fe77B8 (x = 0-10) were prepared using a dual alloy method by mixing (PrNd)5Ce10Fe77B8 with (PrNd)15Fe77B8 powders. For Ce atomic percent of 1% and 2%, coercivity decreases dramatically. With further increase of Ce atomic percent, the coercivity increases, peaks at 6.38 kOe in (PrNd)11Ce4Fe77B8, and then declines gradually. The abnormal dependence of coercivity is likely related to the inhomogeneity of rare earth chemical composition in the intergranular phase, where PrNd concentration is strongly dependent on the additive amount of (PrNd)5Ce10Fe77B8 powders. In addition, for Ce atomic percent of 8%, 7%, and 6% the coercivity is higher than that of magnets prepared by the conventional method, which shows the advantage of the dual alloy method in preparing high abundant rare earth magnets. Project supported by the National Natural Science Foundation of China (Grant Nos. 51461033, 51571126, 51541105, and 11547032), the Natural Science Foundation of Inner Mongolia, China (Grant No. 2013MS0110), and the Inner Mongolia University of Science and Technology Innovation Fund, China.

  5. H2 production through steam reforming of ethanol over Pt/ZrO2, Pt/CeO2 and Pt/CeZrO2 catalysts

    OpenAIRE

    Noronha, Fábio Bellot; Silva, Adriana Maria da; Lima, Sonia M. de; Mattos, Lisiane Veiga; Cruz, Ivna O. da; Jacobs, Gary; Davis, Burtron H

    2008-01-01

    The effect of the support nature and metal dispersion on the performance of Pt catalysts during steam reforming of ethanol was studied. H2 and CO production was facilitated over Pt/CeO2 and Pt/CeZrO2, whereas the acetaldehyde and ethene formation was favored on Pt/ZrO2.

  6. Glass forming ability of the Al-Ce-Ni system; Avaliacao da capacidade de formacao vitrea do sistema Al-Ce-Ni

    Energy Technology Data Exchange (ETDEWEB)

    Triveno Rios, C. [Engenharia Mecanica, Universidade Federal de Mato Grosso, Rondonopolis, MT (Brazil)], e-mail: triveno@ufmt.br; Surinach, S.; Baro, M.D. [Departamento de Engenharia de Materiais - Universidade Federal de Sao Carlos, SP (Brazil); Bolfarini, C.; Botta, W.J.; Kiminami, C.S. [Departamento de Fisica da Universidade Autonoma de Barcelona, Bellaterra (Spain)

    2010-07-01

    In the present work, the glass forming ability (GFA) and its compositional dependence on Al-Ni-Ce system alloys were investigated in function of several thermal parameters. Rapidly quenched Al{sub 85}Ni{sub 15}-{sub X}Ce{sub X} (X=4,5,6,7,10), Al{sub 90}Ni{sub 5}Ce{sub 5}, Al{sub 89}Ni{sub 2}.{sub 4}Ce{sub 8}.{sub 6}, Al{sub 80}Ni{sub 15.6}Ce{sub 4}.{sub 4} and Al{sub 78}Ni{sub 18.5}Ce{sub 3.5} amorphous ribbons were produced by melt-spinning and the structural transformation during heating was studied using a combination of X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results showed that the GFA and the thermal stability in the Al-rich corner of Al- Ni-Ce system alloys were enhanced by increasing the solute content and specifically the Ce content (author)

  7. Neutron-diffraction study of the crystal structure of the superconductor TiSr2(Eu0.8Ce0.2)2Cu2Oz

    International Nuclear Information System (INIS)

    Ishigaki, T.; Ogasawara, Y.; Oikawa, K.; Hoshikawa, A.; Kamiyama, T.

    2004-01-01

    TiSr 2 (RE 1-x Ce x ) 2 Cu 2 O z superconductors (T c ∼20 K) have a 1222-structure with fluorite blocks. Neutron diffraction has been performed on the Eu-containing compound TiSr 2 (Eu 0.8 Ce 0.2 ) 2 Cu 2 O z , with natural Eu, and its crystal structure was refined. The neutron powder diffraction experiment was carried out on the VEGA diffractometer at KENS. The sample was contained in a thin flat cell of 0.5 mm thickness in order to reduce the large absorption effects of natural Eu. The absorption correction for the flat sample was taken into account in the Rietveld refinement. The results show that the O(1) atom in the Ti-layer is shifted from the 4c-site to the split site (8j), and that the concentration is deficient (g∼0.19)

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

    Science.gov (United States)

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

    2015-05-01

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

  9. Analyse du site Tour du monde (Flenet

    Directory of Open Access Journals (Sweden)

    Laurence Jeannot

    2005-09-01

    Full Text Available 1. Introduction Flenet, Français langue étrangère et Internet, a été conçu par Mario Tomé, à l'université de León en Espagne. Ce site s'insère dans le cadre d'un projet de recherche consacré à l'utilisation d'Internet pour apprendre et enseigner le FLE. Des cours de "Phonétique française FLE", de grammaire, présentés dans ce dernier cas comme un projet en cours de réalisation d'après l'intitulé choisi [], sur le lexique, la culture et la civilisation, ainsi que des "Leçons" pour étudiants...

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    if results on a several-fold activity increase of a series of Pt/rare-earth alloys hold also for Pd rare-earth alloys. Pd5Ce crystallizes in two phases, a so-called low-temperature phase, L-Pd5Ce, which has a cubic symmetry, and a high-temperature phase, H-Pd5Ce, with a hexagonal symmetry. In both cases......, in agreement with DFT results for the L-Pd5Ce phase. Although we did not discover a new promising Pd-based catalyst, we have shown that the activity for oxygen reduction is strongly influenced by the alloy crystal structure. Furthermore, we have qualitatively demonstrated that transformation from H-Pd5Ce to L...

  11. Fast humidity sensors based on CeO2 nanowires

    International Nuclear Information System (INIS)

    Fu, X Q; Wang, C; Yu, H C; Wang, Y G; Wang, T H

    2007-01-01

    Fast humidity sensors are reported that are based on CeO 2 nanowires synthesized by a hydrothermal method. Both the response and recovery time are about 3 s, and are independent of the humidity. The sensitivity increases gradually as the humidity increases, and is up to 85 at 97% RH. The resistance decreases exponentially with increasing humidity, implying ion-type conductivity as the humidity sensing mechanism. A model based on the morphology and surface energy of the nanowires is given to explain these results further. Our experimental results indicate a pathway to improving the performance of humidity sensors

  12. espèce de tilapia Sarotherodon melanotheron melanothero

    African Journals Online (AJOL)

    Sci-Nat

    melanotheron, objet du présent travail, dont l'aire de répartition s'étend de la Côte d'Ivoire au. Cameroun. En Côte d'Ivoire, ce poisson se rencontre dans les estuaires et eaux saumâtres, depuis le fleuve Cavally (à l'Ouest) à la lagune. Aby (à l'Est) mais aussi en amont du lac de barrage du fleuve Bia (Gourène et al., 1999).

  13. Decay pattern of the Pygmy Dipole Resonance in 140Ce

    Directory of Open Access Journals (Sweden)

    Isaak J.

    2015-01-01

    Full Text Available The decay behavior of low-lying dipole states in 140Ce was investigated exploiting the γ3-setup at the HIγS facility using quasi-monochromatic photon beams. Branching ratios of individual excited states as well as average branching ratios to low-lying states have been extracted using γ – γ coincidence measurements. The comparison of the average branching ratios to QPM calculations shows a remarkable agreement between experiment and theory in the energy range from 5.0 to 8.5 MeV.

  14. Is Auger-free luminescence present in CeF₃?

    OpenAIRE

    Itoh, Minoru; Iri, Daisuke; Kitaura, Mamoru

    2009-01-01

    It is well known that Auger-free luminescence (AFL) is observable when the condition E-g>E-vc is satisfied, where E-g is the band-gap energy between the lowest unoccupied band and the highest occupied band and E-vc the energy difference between the top of the highest occupied band and the top of the next lower occupied band. From measurements of reflection and X-ray photoelectron spectra, CeF₃ is demonstrated to really satisfy this condition. No evidence for AFL is found, nevertheless. The ab...

  15. Programming Windows® Embedded CE 60 Developer Reference

    CERN Document Server

    Boling, Douglas

    2010-01-01

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

  16. Catalytic reforming of toluene as tar model compound: effect of Ce and Ce-Mg promoter using Ni/olivine catalyst.

    Science.gov (United States)

    Zhang, Ruiqin; Wang, Huajian; Hou, Xiaoxue

    2014-02-01

    Tar produced by biomass gasification as a route of renewable energy must be removed before the gas can be used. This study was undertaken using toluene as a model tar compound for evaluating its steam reforming conversion with three Ni-based catalysts, Ni/olivine, Ni-Ce/olivine and Ni-Ce-Mg/olivine. Effects of Ce and Mg promoters on the reaction activity and coke deposition were studied. Overall the performance of Ce and Mg promoted Ni/olivine catalysts is better than that of only Ce promoter and Ni/olivine alone. The experimental results indicate that Ni-Ce-Mg/olivine catalysts could improve the resistance to carbon deposition, enhance energy gases yield and resist 10ppm H2S poison at 100mLmin(-1) for up to 400min. Furthermore, the activity of catalysts was related to the steam/carbon (S/C) ratios; at S/C ratio=5, T=790°C, space velocity=782h(-1) and t=2h, the Ni-Ce-Mg/olivine system yielded 89% toluene conversion, 5.6Lh(-1) product gas rate, 62.6mol% H2 content and 10% (mol useful gas mol(-1) toluene) energy yield. Moreover, at low S/C ratio, it had higher reaction activity and better ability to prevent coking. There is a small amount of carbon deposition in the form of amorphous carbon after 7h. Various characterization techniques such as XRD, FTIR and thermogravimetric were performed to investigate the coke deposition of Ni/olivine, Ni-Ce/olivine and Ni-Ce-Mg/olivine. It is suggested that 3% Ni-1% Ce-1% Mg/olivine was the most promising catalyst due to its minimum coke amount and the lower activation energy of coke burning. Copyright © 2014. Published by Elsevier Ltd.

  17. Scientific Objectives of China Chang E 4 CE-4 Lunar Far-side Exploration Mission

    Science.gov (United States)

    Zhang, Hongbo; Zeng, Xingguo; Chen, Wangli

    2017-10-01

    China has achieved great success in the recently CE-1~CE-3 lunar missions, and in the year of 2018, China Lunar Exploration Program (CLEP) is going to launch the CE-4 mission. CE-4 satellite is the backup satellite of CE-3, so that it also consists of a Lander and a Rover. However, CE-4 is the first mission designed to detect the far side of the Moon in human lunar exploration history. So the biggest difference between CE-4 and CE-3 is that it will be equipped with a relay satellite in Earth-Moon-L2 Point for Earth-Moon Communication. And the scientific payloads carried on the Lander and Rover will also be different. It has been announced by the Chinese government that CE-4 mission will be equipped with some new international cooperated scientific payloads, such as the Low Frequency Radio Detector from Holland, Lunar Neutron and Radiation Dose Detector from Germany, Neutral Atom Detector from Sweden, and Lunar Miniature Optical Imaging Sounder from Saudi Arabia. The main scientific objective of CE-4 is to provide scientific data for lunar far side research, including: 1)general spatial environmental study of lunar far side;2)general research on the surface, shallow layer and deep layer of lunar far side;3)detection of low frequency radio on lunar far side using Low Frequency Radio Detector, which would be the first time of using such frequency band in lunar exploration history .

  18. Effects of Ce on Inclusions, Microstructure, Mechanical Properties, and Corrosion Behavior of AISI 202 Stainless Steel

    Science.gov (United States)

    Cai, Guojun; Li, Changsheng

    2015-10-01

    The sizes and morphologies of nonmetallic inclusions, microhardness, tensile strength, and Charpy impact toughness in AISI 202 stainless steel with different Ce contents were synthetically analyzed by means of SEM, TEM, microhardness tester, and tensile and Charpy impact tests. Effects of Ce addition on the corrosion behavior were investigated in 5 wt.% H2SO4 solution for different periods of time through measuring AC impedance. The EIS measurements indicate that the steels with Ce addition exhibit higher R p values than those without Ce, which illustrates the relative resistance to uniform corrosion is accompanied by an increasing Ce addition. Ce addition to AISI 202 stainless steel improves its uniform corrosion resistance owing to metamorphic inclusions and the improvement of electrode potential in matrix. Upon increasing Ce addition, the indentation morphology of samples transfers from sink-in types to pile-up types, explaining good machinability of steels containing Ce. It is witnessed from the fracture mode that Ce refines the grain size of steels, significantly increasing the strength; in the meantime, its plasticity is improved, thereby solving the contradiction between the strength and the plasticity of steels. It is concluded that AISI 202 stainless steel with 0.016 wt.% Ce addition in the mass fraction has the best mechanical properties and the uniform corrosion resistance.

  19. Microstructures and mechanical properties in B{sub 4}C-CeO{sub 2} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sun Shuchen, E-mail: sunsc@smm.neu.edu.cn [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Sakamoto, Tatsuaki; Nakai, Kiyomichi [Department of Materials Science and Biotechnology, Ehime University, 3Bunkyo-cho, Matsuyama 790-8577 (Japan); Kurishita, Hiroaki [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Kobayashi, Sengo [Department of Materials Science and Biotechnology, Ehime University, 3Bunkyo-cho, Matsuyama 790-8577 (Japan); Xu Jingyu; Cao Hui; Gao Bo; Bianxue; Wu Wenyuan; Tu Ganfeng [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Matsuda, Seiji [Department of Anatomy and Embryology, Ehime University, Shizugawa, Toon 791-0295 (Japan)

    2011-10-01

    B{sub 4}C-CeO{sub 2} composite ceramics with various concentrations of CeO{sub 2} were fabricated by hot press. The effects of CeO{sub 2} on the microstructures and mechanical properties of the B{sub 4}C-CeO{sub 2} ceramics have been investigated. During hot press, CeB{sub 6} was formed by the reaction between CeO{sub 2} and B{sub 4}C. The B{sub 4}C-CeO{sub 2} ceramics had higher levels of density, fracture toughness, flexural strength and Vickers hardness than those in monolithic B{sub 4}C. The microstructures of the B{sub 4}C-CeO{sub 2} ceramics were observed and analyzed by transmission electron microscopy. In-situ synthesized CeB{sub 6} indicated whisker-like shape and grew along the interface with B{sub 4}C, and different boron carbides with different content of C existed at/around the interface of CeB{sub 6} with B{sub 4}C in the composite ceramics. It made mechanical properties greatly improved.

  20. Systematic study of rotational energy formulae for superdeformed bands in La and Ce isotopes

    Science.gov (United States)

    Sharma, Honey; Mittal, H. M.

    2017-12-01

    The experimental rotational spectra of superdeformed (SD) bands of 130La, 131Ce(1,2), 132Ce(1,2,3) and 133Ce(1,2,3) in the A ∼ 130 mass region are systematically analyzed with the four parameter formula, power index formula, nuclear softness formula, and VMI model. It is observed that out of all the formulae, the four parameter formula suits best for the study of the 130La, 131Ce(1,2), 132Ce(2,3) and 133Ce(1,2,3) SD bands. The four parameter formula works efficiently in determining the band head spin of the 130La, 131Ce(1,2) 132Ce(2,3) and 133Ce(1,2,3) SD bands. Good agreement is seen between the calculated and observed transition energies whenever the accurate spin is assigned. In 132Ce(1), the power index formula is found to work better than the other three formulae. The dynamic moment of inertia is also calculated for all the formulae and its variation with the rotational frequency is investigated.

  1. Sonocatalytic degradation of diclofenac with FeCeOx particles in water.

    Science.gov (United States)

    Chong, Shan; Zhang, Guangming; Wei, Zhongheng; Zhang, Nan; Huang, Ting; Liu, Yucan

    2017-01-01

    This paper studies the sonocatalytic degradation of diclofenac in water using FeCeO x -catalyzed ultrasound. The effects of pre-adsorption and gas addition were investigated. Nitrogen adsorption/desorption, SEM, XRD, Raman and XPS analyses of FeCeO x before and after sonication were characterized. The proposed mechanism was based on the microstructure changes of FeCeO x and reactive-species-scavenging performances. The results show that FeCeO x has excellent performance in catalyzing an ultrasonic system in water, and 80% of diclofenac was removed in 30min ([Diclofenac]=20mg/L, FeCeO x amount=0.5g/L, pH=6, ultrasonic density=3.0W/cm 3 , ultrasonic frequency=20kHz, temperature=298K). The Fe, Ce, and O elements remained highly dispersed in the structure of FeCeO x , and the solid solution structure of FeCeO x remained stable after the reaction. Ce (III) was gradually oxidized to Ce (IV) and Fe (III) was gradually reduced to Fe (II) after the reaction, which indicates that Fe and Ce ions with different valences coexisted in dynamic equilibrium. The amount of oxygen vacancies in FeCeO x significantly decreased after the reaction, which indicates that oxygen vacancy participated in the ultrasonic process. Singlet oxygen 1 O 2 was the primary reactive species in the degradation process, and the hydroxyl radicals OH and superoxide radical anion O 2 - also participated in the reaction. FeCeO x had excellent chemical stability with negligible leaching ions in the ultrasonic process. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Synthesis, characterization, and ecotoxicity of CeO2 nanoparticles with differing properties

    Science.gov (United States)

    Alam, Bushra; Philippe, Allan; Rosenfeldt, Ricki R.; Seitz, Frank; Dey, Sonal; Bundschuh, Mirco; Schaumann, Gabriele E.; Brenner, Sara A.

    2016-10-01

    CeO2 nanoparticles with various characteristics find an increasing number of applications in the electronic, medical, and other industries and are therefore likely released in the environment. This calls for investigations linking the physicochemical properties of these particles with their potential environmental impacts. In this study, CeO2 nanoparticle powders were prepared using three different precursors [Ce(NO3)3, CeCl3, and Ce(CH3COO)3] and annealing temperatures (300, 500, and 700 °C). This procedure resulted in nine different types of nanoparticles with differing size (5-90 nm), morphology, surface Ce3+/Ce4+ ratio, and slightly different crystal structures as characterized using transmission electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy, and X-ray diffraction measurements with Rietveld refinement. These CeO2 nanoparticles underwent toxicity testing at concentrations up to 64 mg L-1 using Daphnia magna. Toxic effects were observed for three particle types with EC50 values between 5 and 64 mg L-1. No clear correlation was observed between the physicochemical properties (size, shape, oxygen occupancy, Ce3+/Ce4+ ratio) of the nanoparticles and their toxicity. However, toxicity was correlated with the amount of Ce remaining suspended in the test medium after 24 h. This indicated that toxic effects may depend on the colloidal stability of CeO2 nanoparticles during the first day of exposure. Therefore, being readily suspended and remaining stable for several days in the aquatic media increases the likelihood that CeO2 nanoparticles will cause unwanted adverse effects.

  3. Highly active and durable Ca-doped Ce-SBA-15 catalyst for biodiesel production

    International Nuclear Information System (INIS)

    Thitsartarn, Warintorn; Maneerung, Thawatchai; Kawi, Sibudjing

    2015-01-01

    In this work, Ca-doped Ce-incorporated SBA-15 (Ca/CeS) catalyst was successfully synthesized by using direct synthesis of Ce-incorporated SBA-15 followed by impregnation of CaO (calcium oxide). The maximum Si/Ce molar ratio that Ce atoms can be incorporated successfully into the mesoporous framework was found to be 5 (CeS-5). After the impregnation of 30 wt. % Ca, the obtained 30Ca/CeS-5 catalysts showed the superior catalytic performance for transesterification reaction of palm oil with methanol and also the higher catalytic activity as compared to other supported catalysts, i.e. CaO/CeO 2 and CaO–CeO 2 /SBA-15. This can be attributed to the well-dispersion of CaO on the CeS-5 support surface. Furthermore, it was found that the leaching of Si, Ce and Ca from the catalyst into biodiesel produced was negligible (i.e. <1 ppm after 7 cycles), indicating the strong interaction between CaO and CeS-5 support. As a result, the 30Ca/CeS-5 catalyst can be reused at least 15 cycles with insignificant decrease in catalytic activity, offering the efficient CaO-based catalyst for biodiesel production. - Highlights: • Mesoporous Ca-based catalyst was successfully developed for biodiesel production. • Catalyst exhibited high activity towards transesterification (FAME yield > 98%). • Catalyst can be effectively re-used at least 15 cycles. • Extremely low catalyst contaminant (<1 ppm) was presented

  4. Hydrothermal synthesis of hexagonal CeO{sub 2} nanosheets and their room temperature ferromagnetism

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Fanming, E-mail: mrmeng@ahu.edu.cn [School of Physics and Materials Science, Anhui University, Hefei 230601 (China); Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China); Zhang, Cheng; Fan, Zhenghua; Gong, Jinfeng; Li, Aixia; Ding, Zongling; Tang, Huaibao; Zhang, Miao; Wu, Guifang [School of Physics and Materials Science, Anhui University, Hefei 230601 (China)

    2015-10-25

    Hexagonal CeO{sub 2} nanosheets of 40–50 nm in thickness and 300–400 nm in side-length have been successfully synthesized via controlling the morphology of CeCO{sub 3}OH precursors by a facile hydrothermal technique using CeCl{sub 3}·7H{sub 2}O as cerium source, ammonium hydrogen carbonate as precipitants, and ethylenediamine as complexant. The reaction time and the amount of CeCl{sub 3}·7H{sub 2}O and ethylenediamine were systematically investigated. The as-synthesized hexagonal CeO{sub 2} nanosheets were examined by XRD, SEM, TEM, XPS, Raman scattering and magnetization measurements. It is found that the amount of CeCl{sub 3}·7H{sub 2}O and ethylenediamine are key parameters for controlling the final morphology. The hexagonal CeO{sub 2} nanosheets have a fluorite cubic structure and there are Ce{sup 3+} ions and oxygen vacancies in surface of samples. The synthesized CeO{sub 2} shows excellent room temperature optical properties. M–H curve exhibits excellent room-temperature ferromagnetism (RTFM) with saturation magnetization (M{sub s}) of 3.02 × 10{sup −2} emu/g, residual magnetization (M{sub r}) of 0.68 × 10{sup −2} emu/g and coercivity (H{sub c}) of 210 Oe, which is likely attributed to the effects of the Ce{sup 3+} ions and oxygen vacancies. - Highlights: • Hexagonal CeO{sub 2} nanosheets with superexerllent RTFM are synthesized by a facile hydrothermal method. • RTFM mechanism of CeO{sub 2} nanosheets can be attributed to the influences of oxygen vacancies and Ce{sup 3+} ions. • A defect driven dissolution–recrystallization mechanism is suggested to explain the transformation from nanowires to nanosheets.

  5. Synthesis, characterization, and ecotoxicity of CeO{sub 2} nanoparticles with differing properties

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Bushra [Aero Shade Technologies Inc (United States); Philippe, Allan, E-mail: philippe@uni-landau.de; Rosenfeldt, Ricki R.; Seitz, Frank [University of Koblenz-Landau, Group of Environmental and Soil Chemistry, Institute for Environmental Sciences (Germany); Dey, Sonal [SUNY Polytechnic Institute, Colleges of Nanoscale Science and Engineering (United States); Bundschuh, Mirco; Schaumann, Gabriele E. [University of Koblenz-Landau, Group of Environmental and Soil Chemistry, Institute for Environmental Sciences (Germany); Brenner, Sara A. [SUNY Polytechnic Institute, Colleges of Nanoscale Science and Engineering (United States)

    2016-10-15

    CeO{sub 2} nanoparticles with various characteristics find an increasing number of applications in the electronic, medical, and other industries and are therefore likely released in the environment. This calls for investigations linking the physicochemical properties of these particles with their potential environmental impacts. In this study, CeO{sub 2} nanoparticle powders were prepared using three different precursors [Ce(NO{sub 3}){sub 3}, CeCl{sub 3}, and Ce(CH{sub 3}COO){sub 3}] and annealing temperatures (300, 500, and 700 °C). This procedure resulted in nine different types of nanoparticles with differing size (5–90 nm), morphology, surface Ce{sup 3+}/Ce{sup 4+} ratio, and slightly different crystal structures as characterized using transmission electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy, and X-ray diffraction measurements with Rietveld refinement. These CeO{sub 2} nanoparticles underwent toxicity testing at concentrations up to 64 mg L{sup −1} using Daphnia magna. Toxic effects were observed for three particle types with EC50 values between 5 and 64 mg L{sup −1}. No clear correlation was observed between the physicochemical properties (size, shape, oxygen occupancy, Ce{sup 3+}/Ce{sup 4+} ratio) of the nanoparticles and their toxicity. However, toxicity was correlated with the amount of Ce remaining suspended in the test medium after 24 h. This indicated that toxic effects may depend on the colloidal stability of CeO{sub 2} nanoparticles during the first day of exposure. Therefore, being readily suspended and remaining stable for several days in the aquatic media increases the likelihood that CeO{sub 2} nanoparticles will cause unwanted adverse effects.

  6. Investigation of the physical, optical, and photocatalytic properties of CeO2/Fe-doped InVO4 composite

    Science.gov (United States)

    Chaison, Jindaporn; Wetchakun, Khatcharin; Wetchakun, Natda

    2017-12-01

    The CeO2/Fe-doped InVO4 composites with various Fe concentrations (0.5, 1.0, 2.0, 5.0 and 6.0 mol%) was synthesized by homogeneous precipitation and hydrothermal methods. The as-synthesized samples were characterized by powder X-ray diffraction (XRD), Brunauer Emmett and Teller (BET)-specific surface area, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and UV-visible diffuse reflectance spectroscopy (DRS). Fe-doping into InVO4 crystal induces the distortion of the crystalline structure, the transformation of InVO4 morphology, and the new energy subband level generation of Fe between the CB and VB edge of InVO4. The electron excitation from the VB to Fe orbitals results in the decreased band gap and the extended absorption of visible-light, and thus enhances its photocatalytic performance. Visible-light-driven photocatalytic degradation of Rhodamine B (RhB) dye in water was used to evaluate the photocatalytic performance of CeO2/Fe-doped InVO4 composites. The results revealed that there is an optimum Fe (5.0 mol %) doping level. The composite with the optimum doping level obtains high photocatalytic activity of CeO2/Fe-doped InVO4 composite compared to pure CeO2 and pure InVO4 host. The increase of photocatalytic activity of CeO2/Fe-doped InVO4 composite was ascribed to the surface area, crystal defect, and band gap energy. Moreover, the photocatalytic enhancement is also because iron ions act as a trapping site, which results in the higher separation efficiency of photogenerated electrons and holes pairs in the CeO2/InVO4 composite. The evaluation of radical scavengers confirmed that hydroxyl radical was the main active species during the photodegradation of RhB. These synergistic effects are responsible for the enhanced photocatalytic activity of CeO2/Fe-doped InVO4 composite. Furthermore, the possible enhanced photocatalytic mechanism

  7. A DNAzyme requiring two different metal ions at two distinct sites.

    Science.gov (United States)

    Zhou, Wenhu; Zhang, Yupei; Huang, Po-Jung Jimmy; Ding, Jinsong; Liu, Juewen

    2016-01-08

    Most previously reported RNA-cleaving DNAzymes require only a single divalent metal ion for catalysis. We recently reported a general trivalent lanthanide-dependent DNAzyme named Ce13d. This work shows that Ce13d requires both Na(+) and a trivalent lanthanide (e.g. Ce(3+)), simultaneously. This discovery is facilitated by the sequence similarity between Ce13d and a recently reported Na(+)-specific DNAzyme, NaA43. The Ce13d cleavage rate linearly depends on the concentration of both metal ions. Sensitized Tb(3+) luminescence and DMS footprinting experiments indicate that the guanines in the enzyme loop are important for Na(+)-binding. The Na(+) dissociation constants of Ce13d measured from the cleavage activity assay, Tb(3+) luminescence and DMS footprinting are 24.6, 16.3 and 47 mM, respectively. Mutation studies indicate that the role of Ce(3+) might be replaced by G23 in NaA43. Ce(3+) functions by stabilizing the transition state phosphorane, thus promoting cleavage. G23 competes favorably with low concentration Ce(3+) (below 1 μM). The G23-to-hypoxanthine mutation suggests the N1 position of the guanine as a hydrogen bond donor. Together, Ce13d has two distinct metal binding sites, each fulfilling a different role. DNAzymes can be quite sophisticated in utilizing metal ions for catalysis and molecular recognition, similar to protein metalloenzymes. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  8. Hydrogen Production from Methanol Steam Reforming over TiO2 and CeO2 Pillared Clay Supported Au Catalysts

    Directory of Open Access Journals (Sweden)

    Rongbin Zhang

    2018-01-01

    Full Text Available Abstract: Methanol steam reforming is a promising process for the generation of hydrogen. In this study, Au catalysts supported on modified montmorillonite were prepared and their catalytic activity for methanol steam reforming was investigated at 250–500 °C. The physical and chemical properties of the as-prepared catalysts were characterized by Brunauer–Emmet–Teller method (BET, X-ray diffraction (XRD, transmission electron microscopic (TEM, scanning electron microscopy (SEM, X-ray photoelectron spectroscopy (XPS, Inductively Coupled Plasma (ICP, and thermogravimetrc analysis (TGA. For the catalysts examined, Au-Ti-Ce/Na-ABen exhibits the best catalytic performance with methanol conversion of 72% and H2 selectivity of 99% at 350 °C. This could be attributed to Au, Ce, and Ti species which form a solid solution and move into the interlayer space of the bentonite leading to a high surface area, large average pore volume, large average pore diameter, and small Au particle size. We considered that the synergistic effect of the crosslinking agent, the Ce species, and the Au active sites were responsible for the high activity of Au-Ti-Ce/Na-ABen catalyst for methanol steam reforming.

  9. CeO2-CuO/Cu2O/Cu monolithic catalysts with three-kind morphologies Cu2O layers for preferential CO oxidation

    Science.gov (United States)

    Jing, Guojuan; Zhang, Xuejiao; Zhang, Aiai; Li, Meng; Zeng, Shanghong; Xu, Changjin; Su, Haiquan

    2018-03-01

    The supports of copper slices with three-kind morphologies Cu2O layers were prepared by the hydrothermal method. The Cu2O layers are rod-like structure, three-dimensional reticular and porous morphology as well as flower-like morphology, respectively. The CeO2-CuO/Cu2O/Cu monolithic catalysts present porous and network structure or foam morphology after loading CeO2 and CuO. Cu and Ce elements are uniformly dispersed onto the support surface. It is found that the monolithic catalyst with flower-like Cu2O layer displays better low-temperature activity because of highly-dispersed CuO and high Olatt concentration. The monolithic catalysts with rod-like or reticular-morphology Cu2O layers present high-temperature activity due to larger CuO crystallite sizes and good synergistic effect at copper-ceria interfacial sites. The as-prepared CeO2-CuO/Cu2O/Cu monolithic catalysts show good performance in the CO-PROX reaction. The generation of Cu2O layers with three-kind morphologies is beneficial to the loading and dispersion of copper oxides and ceria.

  10. Effects of (LiCe) co-substitution on the structural and electrical properties of CaBi2Nb2O9 ceramics

    Science.gov (United States)

    Tian, Xiao-Xia; Qu, Shao-Bo; Du, Hong-Liang; Li, Ye; Xu, Zhuo

    2012-03-01

    The piezoelectric, dielectric, and ferroelectric properties of the (LiCe) co-substituted calcium bismuth niobate (CaBi2Nb2O9, CBNO) are investigated. The piezoelectric properties of CBNO ceramics are significantly enhanced and the dielectric loss tan δ decreased. This makes poling using (LiCe) co-substitution easier. The ceramics (where □ represents A-site Ca2+ vacancies, possess a pure layered structure phase and no other phases can be found. The Ca0.88(LiCe)0.04□0.04Bi2Nb2O9 ceramics possess optimal piezoelectric properties, with piezoelectric coefficient (d33) and Curie temperature (TC) found to be 13.3 pC/N and 960 °C, respectively. The dielectric and piezoelectric properties of the (LiCe) co-substituted CBNO ceramics exhibit very stable temperature behaviours. This demonstrates that the CBNO ceramics are a promising candidate for ultrahigh temperature applications.

  11. Luminescence properties of single-phase color-tunable CeZn1-x(B5O10):xMn2+ phosphor

    Science.gov (United States)

    Lu, Yixuan; Li, Chenxia; Deng, Degang; Hua, Yu; Wang, Le; Jin, Leisheng; Xu, Shiqing

    2017-12-01

    In this work, a transition metal doped Ce3+-based borate CeZn1-x(B5O10):Mn2+ was synthesized by utilizing conventional solid-state reaction method. The lattice structure and particularly the luminescence properties of the synthesized phosphors were carefully studied. By analyzing the results, it is revealed that Mn2+ only occupies Zn sites, and it only contributes the light emitting peaked at 615 nm under the excitation of 371 nm. While the emitting peak at 437 nm under the same excitation is verified to be caused by the 5d-4f (2F5/2 and 2F7/2) transitions of Ce3+-based. Furthermore, by conducting a comprehensive investigation on overlap of emission, excitation spectra and variation of fluorescence decay lifetimes, we make it clear that the energy transfer from Ce3+ to Mn2+ is virtually via a resonance-type mechanism. Last but not the least, we can realize color-tunable light emitting by adjusting the concentration of Mn2+ in our proposed phosphor and using excitation of ultraviolet (UV) light. In addition, close to white light can be realized when doping the Mn2+ ions to a certain extent.

  12. Intrinsic Activity of MnOx-CeO2 Catalysts in Ethanol Oxidation

    Directory of Open Access Journals (Sweden)

    Dimitrios Delimaris

    2017-11-01

    Full Text Available MnOx-CeO2 mixed oxides are considered efficient oxidation catalysts superior to the corresponding single oxides. Although these oxides have been the subject of numerous studies, their fundamental performance indicators, such as turnover frequency (TOF or specific activity, are scarcely reported. The purpose of the present work is to investigate the effect of catalyst composition on the concentration of active sites and intrinsic activity in ethanol oxidation by the employment of temperature-programmed desorption and oxidation of isotopically-labelled ethanol, 12CH313CH2OH. The transformation pathways of preadsorbed ethanol in the absence of gaseous oxygen refer to dehydrogenation to acetaldehyde followed by its dissociation combined with oxidation by lattice oxygen. In the presence of gaseous oxygen, lattice oxygen is rapidly restored and the main products are acetaldehyde, CO2, and water. CO2 forms less easily on mixed oxides than on pure MnOx. The TOF of ethanol oxidation has been calculated assuming that the amount of adsorbed ethanol and CO2 produced during temperature-programmed oxidation (TPO is a reliable indicator of the concentration of the active sites.

  13. Native American depopulation, reforestation, and fire regimes in the Southwest United States, 1492-1900 CE.

    Science.gov (United States)

    Liebmann, Matthew J; Farella, Joshua; Roos, Christopher I; Stack, Adam; Martini, Sarah; Swetnam, Thomas W

    2016-02-09

    Native American populations declined between 1492 and 1900 CE, instigated by the European colonization of the Americas. However, the magnitude, tempo, and ecological effects of this depopulation remain the source of enduring debates. Recently, scholars have linked indigenous demographic decline, Neotropical reforestation, and shifting fire regimes to global changes in climate, atmosphere, and the Early Anthropocene hypothesis. In light of these studies, we assess these processes in conifer-dominated forests of the Southwest United States. We compare light detection and ranging data, archaeology, dendrochronology, and historical records from the Jemez Province of New Mexico to quantify population losses, establish dates of depopulation events, and determine the extent and timing of forest regrowth and fire regimes between 1492 and 1900. We present a new formula for the estimation of Pueblo population based on architectural remains and apply this formula to 18 archaeological sites in the Jemez Province. A dendrochronological study of remnant wood establishes dates of terminal occupation at these sites. By combining our results with historical records, we report a model of pre- and post-Columbian population dynamics in the Jemez Province. Our results indicate that the indigenous population of the Jemez Province declined by 87% following European colonization but that this reduction occurred nearly a century after initial contact. Depopulation also triggered an increase in the frequency of extensive surface fires between 1640 and 1900. Ultimately, this study illustrates the quality of integrated archaeological and paleoecological data needed to assess the links between Native American population decline and ecological change after European contact.

  14. Easy peak tracking in CE-UV and CE-UV-ESI-MS by incorporating temperature-correlated mobility scaling

    DEFF Research Database (Denmark)

    Li, Bin; Petersen, Nickolaj Jacob; Andersen, Line Hvass

    2013-01-01

    resistance of the buffer-filled capillary. The temperature-correlated mobility calculation eliminates the peak shifts due to the viscosity changes, improves the precision of peak identification using the observed temperature-correlated mobilities and allows a direct comparison of signals from different......A simple data reconstruction technique in capillary electrophoresis - ultraviolet - electrospray ionization - mass spectrometry (CE-UV-ESI-MS) is presented to overcome the drift in mobilities caused by various factors compromising the reproducibility of such data, e.g. Joule heating effects...

  15. Structural aspects of the new quasi-2-D heavy fermion materials CeIrIns and CeRhIns

    International Nuclear Information System (INIS)

    Moshopoulou, E.G.; Moshopoulou, E.G.; Fisk, Z.; Sarrao, J.L.; Thompson, J.D.; Fisk, Z.

    2002-01-01

    The title compounds are new heavy fermion materials. They adopt a quasi two-dimensional crystal structure and exhibit unusual (for a heavy fermion system) low temperature properties. Although the study of their physical and structural behaviour at low temperatures and/or high pressures is still in progress, we present here some results concerning their average crystal structure, and we discuss very briefly their similarities and differences with the compounds CeIn3 and UTGa 5 (T: Co, Ni, Ir, Pd, Cu, Ru). (authors)

  16. La vérite sur ce qui nous motive

    CERN Document Server

    Pink, Daniel H

    2011-01-01

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

  17. CE-4 Mission and Future Journey to Lunar

    Science.gov (United States)

    Zou, Yongliao; Wang, Qin; Liu, Xiaoqun

    2016-07-01

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

  18. Gapless Fermi surfaces in superconducting CeCoIn5

    Science.gov (United States)

    Barzykin, Victor; Gor'Kov, L. P.

    2007-07-01

    According to Tanatar [Phys. Rev. Lett. 95, 067002 (2005)], the low-temperature thermal conductivity in Ce1-xLaxCoIn5 , a multiband d -wave superconductor, reveals unexpected dependence on the concentration of defects as if one or more Fermi surface sheets remained ungapped below superconducting transition. The interior gap superfluidity mechanism, or unbalanced pairing, recently proposed by Liu and Wilczek [Phys. Rev. Lett. 90, 047002 (2003)] has been invoked as a possible origin of gaplessness. We indicate that the Fermi surface anisotropy in the real CeCoIn5 makes this explanation highly implausible. We emphasize the fundamental difference between unbalanced pairing of different Fermi entities and the formation of superconducting gaps on Fermi surfaces belonging to different bands. We also argue that interband interactions between electrons always induce a finite order parameter on all Fermi surfaces below the temperature of a superconducting transition. We calculate specific heat and thermal conductivity in a two-band model for a d -wave superconductor in the presence of defects. In our simple model, superconductivity originates on one Fermi surface, inducing a smaller gap on the other one. Impurities diminish the induced gap and increase the density of states, restoring rapidly the Wiedemann-Franz law for this Fermi surface. Our calculations are in agreement with experiment.

  19. Magnetoresistance and magnetization anomalies in CeB6

    International Nuclear Information System (INIS)

    Bogach, A.V.; Glushkov, V.V.; Demishev, S.V.; Samarin, N.A.; Paderno, Yu.B.; Dukhnenko, A.V.; Shitsevalova, N.Yu.; Sluchanko, N.E.

    2006-01-01

    High precision magnetoresistance (MR) Δρ/ρ(H,T) and magnetization M(H,T) measurements have been carried out for well known and typical strongly correlated electron system-cerium hexaboride. The detailed measurements have been fulfilled on single crystalline samples of CeB 6 over a wide temperature range T>=1.8K in magnetic fields up to 70kOe. It was shown that the MR anomalies in the magnetic heavy fermion compound under investigation can be consistently interpreted in the frameworks of a simple relation between resistivity and magnetization-Δρ/ρ∼M 2 obtained by Yosida [Phys. Rev. 107(1957)396]. A local magnetic susceptibility χ loc (T,H)=(1/H*(d(Δρ/ρ)/dH)) 1/2 was deduced directly from the MR Δρ(H,T) measurements and compared with the experimental data of magnetization M(H,T). The magnetic susceptibility dependences χ loc (T,H) and χ(T,H) obtained in this study for CeB 6 allow us to analyze the complicated H-T magnetic phase diagram of this so-called dense Kondo-system

  20. Ceļa servitūts

    OpenAIRE

    Livdāns, Dāvis

    2016-01-01

    Bakalaura darba tēma ir “Ceļa servitūts.” Bakalaura darba mērķis ir izpētīt ceļa servitūta nodibināšanas kārtību, iespējamās kļūdas, praksē nodibināto servitūtu problēmjautājumus un to risinājumus. Bakalaura darba tapšanas stadijā autors izmantoja zinātnisko literatūru, normatīvos aktus, kā arīi ar to tapšanu saistītos dokumentus un juridiskās prakses materiālus. Darbā ir apskatīti gan Civillikumā noteiktie servitūtu nodibināšanas pamati, gan citi iespējamie nodibināšanas pamati, pēc kā ir an...

  1. Otology at the Academy of Gondishapur 200-600 CE.

    Science.gov (United States)

    Ruben, Robert J

    2017-12-01

    To investigate the way in which otology was practiced at the Academy of Gondishapur in ancient Persia from 200 to 600 CE. The pertinent literature, using German and English translations of Latin, Greek, Arabic, and Sanskrit documents, was identified and reviewed through the indices of available books and through a PDF search for the following topics: auricle, deaf, deafness, dizziness, ear, hearing, medicine, otitis, pinna, punishment-ear, speech, surgery, vertigo, and voice. The medical school at the Academy of Gondishapur followed the medical and surgical practices of Greece and Rome and, in the 6th century, incorporated those from India as detailed in the Shutra Samhita. This shutra, which originated during the first millennium BCE, detailed many interventions, among which one of the most unusual was the use of a pedicle cheek flap to restore the pinnae. The use of the pedicle flap for pinna restoration appears not have been reported in literature again until 1931, by Jacque Joseph. During the period of late antiquity, medical knowledge of both the east and west was preserved and taught in Persia. Among surgical interventions used during the first millennium BCE in India, knowledge of which passed, through the shutra, to the Sasanian Empire in the 6th century CE, was use of the pedicle cheek flap for pinna reconstruction. Even as late as the Renaissance, the pedicle flap was not known to surgeons in the West, and a pedicle flap, though not a cheek flap, was first incorporated into Western medical practice during the 1930s.

  2. Irradiation effects in UO2 and CeO2

    International Nuclear Information System (INIS)

    Ye, Bei; Oaks, Aaron; Kirk, Mark; Yun, Di; Chen, Wei-Ying; Holtzman, Benjamin; Stubbins, James F.

    2013-01-01

    Single crystal CeO 2 , as a surrogate material to UO 2 , was irradiated with 500 keV xenon ions at 800 °C while being observed using in situ transmission electron microscopy (TEM). Experimental results show the formation and growth of defect clusters including dislocation loops and cavities as a function of increasing atomic displacement dose. At high dose, the dislocation loop structure evolves into an extended dislocation line structure, which appears to remain stable to the high dose levels examined in this study. A high concentration of cavities was also present in the microstructure. Despite high atomic displacement doses, the specimen remained crystalline to a cumulated dose of 5 × 10 15 ions/cm 2 , which is consistent with the known stability of the fluorite structure under high dose irradiation. Kinetic Monte Carlo calculations show that oxygen mobility is substantially higher in hypo-stoichiometric UO 2 /CeO 2 than hyper-stoichiometric systems. This result is consistent with the ability of irradiation damage to recover even at intermediate irradiation temperatures

  3. Genome Mining in Sorangium cellulosum So ce56

    Science.gov (United States)

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

    2009-01-01

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

  4. Microstructures, magnetic properties and coercivity mechanisms of Nd-Ce-Fe-B based alloys by Zr substitution

    Science.gov (United States)

    Wang, Lei; Quan, Qichen; Zhang, Lili; Hu, Xianjun; Ur Rehman, Sajjad; Jiang, Qingzheng; Du, Junfeng; Zhong, Zhenchen

    2018-03-01

    In this paper, the effects of Zr addition on microstructures, magnetic properties, exchange coupling, and coercivity mechanisms of Nd-Ce-Fe-B alloys fabricated by melt-spinning technique are investigated. It is found that the coercivity Hcj is enhanced significantly by Zr substitution in the (Nd0.8Ce0.2)13Fe82-xZrxB5 alloys, while the remanence Jr is reduced slightly. The Hcj increases from 12.2 to 13.7 kOe by adding Zr up to 1.5 at. %, whereas Hcj is decreased with a further increase in Zr content. The larger lattice constants and unit cell volumes of the matrix phase indicate that Zr atoms enter into the hard magnetic phase by substituting Fe sites. The reduction of Tc implies the attenuation of the exchange interaction in the 2:14:1 phase with Zr occupying the Fe sites. The weakened intergranular exchange coupling of the Zr added alloy may be attributed to the formation of a non-magnetic intergranular phase. It is worth noting that the coercivity is dominated by the pinning of domain walls at defect positions even though the nucleation of reversal domains still exists. The synergistic function between the pinning effect and the exchange coupling leads to improved magnetic properties.

  5. Site selection

    CERN Multimedia

    CERN PhotoLab

    1968-01-01

    To help resolve the problem of site selection for the proposed 300 GeV machine, the Council selected "three wise men" (left to right, J H Bannier of the Netherlands, A Chavanne of Switzerland and L K Boggild of Denmark).

  6. Site Restoration

    Energy Technology Data Exchange (ETDEWEB)

    Noynaert, L.; Bruggeman, A.; Cornelissen, R.; Massaut, V.; Rahier, A

    2001-04-01

    The objectives, the programme, and the achievements of the Site Restoration Department of SCK-CEN in 2000 are summarised. Main activities include the decommissioning of the BR3 PWR-reactor as well as other clean-up activities, projects on waste minimisation and activities related to the management of decommissioning projects. The department provides consultancy and services to external organisations.

  7. Site Restoration

    International Nuclear Information System (INIS)

    Noynaert, L.; Bruggeman, A.; Cornelissen, R.; Massaut, V.; Rahier, A.

    2001-01-01

    The objectives, the programme, and the achievements of the Site Restoration Department of SCK-CEN in 2000 are summarised. Main activities include the decommissioning of the BR3 PWR-reactor as well as other clean-up activities, projects on waste minimisation and activities related to the management of decommissioning projects. The department provides consultancy and services to external organisations

  8. Site calibration

    DEFF Research Database (Denmark)

    Gómez Arranz, Paula; Georgieva Yankova, Ginka

    between the wind speed at the center of the turbine hub and at the met mast. The wind speed at the turbine is measured by a temporary mast placed at the foundation for the turbine. The site and measurement equipment is detailed described in [2]. The possible measurement sector for power performance...

  9. Effect of nano-CeO2 on microstructure properties of TiC/TiN+TiCN ...

    Indian Academy of Sciences (India)

    TiC/TiN+TiCN-reinforced composite coatings were fabricated on Ti–6Al–4V alloy by laser cladding, ... Ce was able to refine the microstructure of laser-cladded .... According to the report by Tian et al. (2006), during the cladding process, a portion of CeO2 was decomposed as follows: CeO2 →Ce + O2 ↑. (2). Then, Ce was ...

  10. Particle-specific toxicity and bioavailability of cerium oxide (CeO{sub 2}) nanoparticles to Arabidopsis thaliana

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xinping; Pan, Haopeng [College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Wang, Peng, E-mail: p.wang3@uq.edu.au [College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China); The University of Queensland, School of Agriculture and Food Sciences, St. Lucia, Queensland 4072 (Australia); Zhao, Fang-Jie [College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom)

    2017-01-15

    Highlights: • The phytotoxicity and uptake of CeO{sub 2} NPs were examined in Arabidopsis. • CeO{sub 2} NPs stimulated plant growth at low doses but were toxic at high doses. • The toxicity was due to the NPs per se, rather than from the dissolved Ce ions. • A similar up-translocation factor was found for CeO{sub 2} NPs, bulk CeO{sub 2} and Ce ions. - Abstract: The use of manufactured cerium oxide nanoparticles (CeO{sub 2}-NPs) in consumer products has increased markedly over the past decade, and their release into natural ecosystems is unavoidable. This study investigated the phytotoxicity and uptake of CeO{sub 2}-NPs in Arabidopsis thaliana grown in an agar medium. Although low concentrations of CeO{sub 2}-NPs had stimulatory effects on plant growth, at higher concentrations, CeO{sub 2}-NPs reduced growth and had adverse effects on the antioxidant systems and photosystem. Importantly, the toxicity resulted from the nanoparticles per se, rather than from the dissolved Ce ions. CeO{sub 2}-NPs were taken up and subsequently translocated to shoot tissues, and transmission electron microscopy (TEM) showed the presence of a large number of needle-like particle aggregations in the intercellular regions and the cytoplasm of leaf cells. The up-translocation factor to shoots was independent of the concentrations of Ce in the roots and the supplied forms of Ce (i.e. CeO{sub 2}-NPs, CeO{sub 2}-bulk, and ionic Ce), suggesting that endocytosis is likely to be a general mechanism responsible for the translocation of these Ce compounds. These findings provide important information regarding the toxicity and uptake of CeO{sub 2}-NPs in plants, which needs to be considered in environmental risk assessment for the safe use and disposal of CeO{sub 2}-NPs.

  11. Excitation light source dependence of emission in Sn2+-Ce3+ codoped ZnO-P2O5 glasses

    OpenAIRE

    Masai, Hirokazu; Hino, Yusuke; Yanagida, Takayuki; Fujimoto, Yutaka; Fukuda, Kentaro; Yoko, Toshinobu

    2013-01-01

    Correlation between excitation light source and the emission property of Sn^{2+}-Ce^{3+} co-doped zinc phosphate glasses is examined. Although photoluminescence (PL) peaks of both Sn^{2+}and Ce^{3+} shifted with increasing amount of Ce^{3+}, there was little energy resonance between Sn^{2+} and Ce^{3+} emission centers. On the other hand, radioluminescence (RL) spectra excited by X-ray was independent of the Ce concentration, indicating that emission was mainly observed from Sn^{2+} emission ...

  12. Anisotropy of the Kondo insulator CeRu4Sn6

    International Nuclear Information System (INIS)

    Paschen, S; Winkler, H; Nezu, T; Kriegisch, M; Hilscher, G; Custers, J; Prokofiev, A; Strydom, A

    2010-01-01

    The intermetallic compound CeRu 4 Sn 6 has tentatively been classified as Kondo insulator. Its tetragonal crystal structure places it inbetween the archetypal Kondo insulators like YbB 12 or Ce 3 Bi 4 Pt 3 , which are cubic, and the orthorhombic 'Kondo semimetals' CeNiSn and CeRhSb. It is of great interest to investigate possible anisotropies - or even nodes - of the Kondo insulating gap in CeRu 4 Sn 6 . We have succeeded, for the first time, to grow single crystals of this compound. Interestingly, we could not only reveal anisotropy between the tetragonal c direction and the tetragonal a-a plane but even within a quasi-cubic cell which happens to be formed in CeRu 4 Sn 6 because the length of the diagonal of the tetragonal plane c' = √2a differs from c by only 0.2%.

  13. Adsorption process of fluoride from drinking water with magnetic core-shell Ce-Ti@Fe3O4 and Ce-Ti oxide nanoparticles.

    Science.gov (United States)

    Abo Markeb, Ahmad; Alonso, Amanda; Sánchez, Antoni; Font, Xavier

    2017-11-15

    Synthesized magnetic core-shell Ce-Ti@Fe 3 O 4 nanoparticles were tested, as an adsorbent, for fluoride removal and the adsorption studies were optimized. Adsorption capacity was compared with the synthesized Ce-Ti oxide nanoparticles. The adsorption equilibrium for the Ce-Ti@Fe 3 O 4 adsorbent was found to occur in Ti oxides and Ce-Ti@Fe 3 O 4 nanoparticles, respectively. The physical sorption mechanism was estimated using the Dubinin-Radushkevich model. An anionic exchange process between the OH - group on the surface of the Ce-Ti@Fe 3 O 4 nanomaterial and the F - was involved in the adsorption. Moreover, thermodynamic parameters proved the spontaneous process for the adsorption of fluoride on Ce-Ti@Fe 3 O 4 nanoparticles. The reusability of the material through magnetic recovery was demonstrated for five cycles of adsorption-desorption. Although the nanoparticles suffer slight structure modifications after their reusability, they keep their adsorption capacity. Likewise, the efficiency of the Ce-Ti@Fe 3 O 4 was demonstrated when applied to real water to obtain a residual concentration of F - below the maximum contaminated level, 1.5mg/L (WHO, 2006). Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Influence of synthesis conditions on the crystal structure of the powder formed in the ZrO2 - Ce2O3/CeO2 system

    International Nuclear Information System (INIS)

    Popov, V V; Menushenkov, A P; Khubbutdinov, R M; Sharapov, A S; Svetogorov, R D; Zubavichus, Ya V; Kurilkin, V V

    2016-01-01

    Influence of synthesis conditions (type of atmosphere, reduction and oxidation, annealing temperature) on the chemical composition and structure of the compounds formed in the “ZrO 2 - Ce 2 O 3 / CeO 2 ” system has been investigated by X-ray absorption fine structure (XAFS) spectroscopy combined with X-ray diffraction (XRD) and thermogravimetric analysis (TGA). It is revealed that isothermal annealing of precursor at temperatures less than 1000 °C in air leads to formation of Ce 0.5 Zr 0.5 O 2 powders with cubic fluorite-type structure (Fm-3m). Further increase of annealing temperatures above 1000 °C causes decomposition of formed crystal structure into two phases: cubic and tetragonal. Annealing in reduction hydrogen atmosphere causes formation of Ce 4 + 2xCe 3 + 2-2xZr 2 O 7 + x compounds with intermediate valency of cerium, where value of x depends on the reducing conditions and treatment parameters of precursor. Annealing in vacuum at 1400 °C strongly reduces the content of Ce 4 + in a powder samples and leads to formation of pyrochlore structure (space group Fd-3 m ) with practically Ce 3+ valence state. (paper)

  15. 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.

  16. Laser clad Ni-base alloy added nano- and micron-size CeO 2 composites

    Science.gov (United States)

    Zhang, Shi Hong; Li, Ming Xi; Cho, Tong Yul; Yoon, Jae Hong; Lee, Chan Gyu; He, Yi Zhu

    2008-07-01

    Micron-size Ni-base alloy (NBA) powders are mixed with both 1.5 wt% (%) micron-CeO 2 (m-CeO 2) and also 1.0-3.0% nano-CeO 2 (n-CeO 2) powders. These mixtures are coated on low carbon steel (Q235) by 2.0 kW CO 2 laser cladding. The effects on microstructures, microhardness and wear resistance of the coating by the addition of m- and n-CeO 2 powders to NBA (m- and n-CeO 2/NBA) have been investigated. Addition to the primary phases of γ-Ni, Cr 23C 6 and Ni 3B of NBA coating, CeNi 3 shows up both in m- and n-CeO 2/NBA coatings and CeNi 5 appears only in n-CeO 2/NBA coating. Directional dendrite and coarse equiaxed dendrite are grown in m-CeO 2/NBA coating from interface to central zone, whereas multi-oriented dendrite and fine equiaxed dendrite growth by addition of n-CeO 2. The microhardness and wear resistance of coatings are greatly improved by CeO 2 powder addition, and compared to the addition of 1.0% and 3.0%, 1.5% n-CeO 2/NBA is the best. Hardness and wear resistance of the coating improves with decreasing CeO 2 size from micron to nano.

  17. Loparite, a rare-earth ore (Ce, Na, Sr, Ca)(Ti, Nb, Ta, Fe+3)O3

    Science.gov (United States)

    Hedrick, James B.; Sinha, Shyama P.; Kosynkin, Valery D.

    1997-01-01

    The mineral loparite (Ce, NA, Sr, Ca)(Ti, Nb, Ta, Fe+3)O3 is the principal ore of the light-group rare-earth elements (LREE) in Russia. The complex oxide has a perovskite (ABO3) structure with coupled substitutions, polymorphism, defect chemistry and a tendency to become metamict. The A site generally contains weakly bonded, easily exchanged cations of the LREE, Na and Ca. The B site generally contains smaller, highly charged cations of Ti, Nb or Fe+3. Mine production is from Russia's Kola Peninsula. Ore is beneficiated to produce a 95% loparite concentrate containing 30% rare-earth oxides. Loparite concentrate is refined by either a chlorination process or acid decomposition process to recover rare-earths, titanium, niobium and tantalum. Rare-earths are separated by solvent extraction and selective precipitation/dissolution. The concentrate is processed at plants in Russia, Estonia and Kazakstan.

  18. Macracanthorhynchus hirudinaceus Eggs in Canine Coprolite from the Sasanian Era in Iran (4(th/5(th Century CE.

    Directory of Open Access Journals (Sweden)

    Gholamreza Mowlavi

    2015-06-01

    Full Text Available Present paper is the second publication introducing the paleoparasitological findings from animal coprolites obtained from archeological site of Chehrabad salt mine in northwestern Iran. The current archeological site is located in northwest of Iran, dated to the Sassanian Era (4(th/5(th century CE. In the summer 2012 the carnivore coprolite was obtained within the layers in the mine and were thoroughly analyzed for parasites using TSP rehydration technique. Eggs of 0 were successfully retrieved from the examined coprolite and were confidently identified based on reliable references. Identifying of M. hirudinaceus eggs in paleofeces with clear appearance as demonstrated herein, is much due to appropriate preservation condition has been existed in the salt mine .The present finding could be regarded as the oldest acanthocephalan infection in Iran.

  19. Paramagnetic Ce3 + optical emitters in garnets: Optically detected magnetic resonance study and evidence of Gd-Ce cross-relaxation effects

    Science.gov (United States)

    Tolmachev, D. O.; Gurin, A. S.; Uspenskaya, Yu. A.; Asatryan, G. R.; Badalyan, A. G.; Romanov, N. G.; Petrosyan, A. G.; Baranov, P. G.; Wieczorek, H.; Ronda, C.

    2017-06-01

    Paramagnetic Ce3 +optical emitters have been studied by means of optically detected magnetic resonance (ODMR) via Ce3 + spin-dependent emission in cerium-doped garnet crystals which were both gadolinium free and contain gadolinium in a concentration from the lowest (0.1%) to 100%, i.e., to the superparamagnetic state. It has been shown that the intensity of photoluminescence excited by circularly polarized light into Ce3 + absorption bands can be used for selective monitoring the population of the Ce3 + ground-state spin sublevels. Direct evidence of the cross-relaxation effects in garnet crystals containing two electron spin systems, i.e., the simplest one of Ce3 + ions with the effective spin S =1/2 and the system of Gd3 + ions with the maximum spin S =7/2 , has been demonstrated. Magnetic resonance of Gd3 + has been found by monitoring Ce3 + emission in cerium-doped garnet crystals with gadolinium concentrations of 0.1 at. %, 4%-8%, and 100%, which implies the impact of the Gd3 + spin polarization on the optical properties of Ce3 +. Strong internal magnetic fields in superparamagnetic crystals were shown to modify the processes of recombination between UV-radiation-induced electron and hole centers that lead to the recombination-induced Ce3 + emission. Observation of spikes and subsequent decay in the cross-relaxation-induced ODMR signals under pulsed microwave excitation is suggested to be an informative method to investigate transient processes in the many-spin system of Ce3 +, Gd3 +, and electron and hole radiation-induced centers.

  20. Eu and Sr2CeO4 : Eu phosphors suitable for near ultraviolet excitation

    Indian Academy of Sciences (India)

    Administrator

    et al 2009). It absorbs ultraviolet radiation and emits white light, when activated by Eu2+ ions. It is anticipated that the dual behaviour of Sr2CeO4 : Eu3+ and Sr2CeO4 : Eu2+ phosphors ... in stoichiometric proportions (Sr : Ce is 2 : 1) and Eu2O3. (National ..... Zhang C X, Jiang W J and Yang X J 2009 J. Alloys Compd. 474.

  1. Electrical resistivity of CeTIn{sub 5} (T=Rh, Ir) under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Muramatsu, Takaki; Kobayashi, Tatsuo C.; Shimizu, Katsuya; Amaya, Kiichi; Aoki, Dai; Haga, Yoshinori; Onuki, Yoshichika

    2003-05-15

    We have studied the superconducting properties of CeTIn{sub 5} (T=Rh, Ir) under high pressures by means of electrical resistivity measurements and determined the pressure-temperature phase diagrams for the superconducting transition. For both systems, the superconductivity exists in a wide pressure range, 1.5{<=}P{<=}6.5 GPa for CeRhIn{sub 5} and 0{<=}P{<=}5.2 GPa for CeIrIn{sub 5}.

  2. Scintillation response comparison among Ce-doped aluminum gartnes, perovskites and orthosilicates

    Czech Academy of Sciences Publication Activity Database

    Mareš, Jiří A.; Nikl, Martin; Mihóková, Eva; Vedda, A.; D´Ambrosio, C.

    2008-01-01

    Roč. 55, č. 3 (2008), s. 1142-1147 ISSN 0018-9499 R&D Projects: GA AV ČR 1QS100100506 Institutional research plan: CEZ:AV0Z10100521 Keywords : scintillation response * Ce 3+ -doped aluminum perovskites * Ce 3+ -doped garnets, * Ce 3+ -doped orthosilicates Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.518, year: 2008

  3. Spray deposited CeO2–TiO2 counter electrode for electrochromic ...

    Indian Academy of Sciences (India)

    Abstract. Optically passive thin films of CeO2–TiO2 mixed oxides with molar ratio of Ce/Ti of 0.05 were deposited by the spray pyrolysis technique (SPT) on a glass and fluorine-doped tin oxide (FTO)-coated glass substrates. Precur- sor solution containing cerium nitrate hexahydrate (Ce(NO3)2·6H2O) and titanium ...

  4. Incommensurate antiferromagnetism and magnetic correlations in CeCu6-xAux

    DEFF Research Database (Denmark)

    Stockert, O.; Lohneysen, H. von; Schröder, A.

    1997-01-01

    Magnetic ordering and correlations in single crystals of the heavy-fermion alloys CeCu5.8Au0.2 and CeCu5.9Au0.1 were investigated by elastic and inelastic neutron scattering. CeCu5.8Au0.2 orders with an incommensurate magnetic structure and a wave vector q = (+/- 0.79 0 0). Only dynamic...

  5. Nanocrystalline Ce1- x La x O2- δ Solid Solutions Synthesized by Hydrolyzing and Oxidizing

    Science.gov (United States)

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

    2016-05-01

    We undertook a novel batch production approach for the synthesis of CeO2 nanopowders doped with rare earth elements. Solid solution nanopowders of Ce1- x La x O2- δ ( x = 0.15) were successfully synthesized in a large-scale and low-cost production by hydrolyzing and oxidizing Ce-La-C alloys at room temperature and subsequent calcining of their powders at different temperatures (873-1073 K) for 1 h. The Ce-La-C alloys were prepared in a vacuum induction melting furnace. The final products were characterized by x-ray diffraction, transmission electron microscopy, Brunner-Emmet-Teller (BET) surface area analyzer, and Raman spectroscopy. The calculated lattice parameters of the cubic fluorite-type phase of CeO2 tended to increase when La3+ was incorporated into CeO2. The F 2g band shift and the absence of a peak corresponding to La2O3 in the Raman spectra consistently confirmed the incorporation of the La3+ ion into CeO2, and the formation of Ce1- x La x O2- δ solid solutions as manifested by increased oxygen vacancy defects. High-quality Ce1- x La x O2- δ nanopowders of ~10-15 nm diameter with a high BET surface area of ~77 m2 g-1 were obtained. The average crystallite size of Ce1- x La x O2- δ was found to be smaller than that of CeO2 for the same calcination temperature of 1073 K, demonstrating that the introduction of La3+ into CeO2 can stabilize the host lattice and refine the grain size at high temperatures.

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

    International Nuclear Information System (INIS)

    Coupland, Daniel David Schechtman; Budden, Brent Scott; Stonehill, Laura Catherine

    2015-01-01

    We perform an investigation into the scintillation processes and performance of elpasolites Cs 2 LiLaBr 6-x Cl x :Ce (CLLBC) and Cs 2 LiYBr 6 :Ce (CLYB) using a thermal cycle over a range of -20 to +50°C. At 10° increments, we acquire data with both a waveform digitizer and charge-integrating electronics. We identify decay components and evaluate decay times, thermal neutron gamma-equivalent energy (GEE), and pulse shape discrimination (PSD) performance. Results are compared to common Cs 2 LiYCl 6 :Ce (CLYC).

  7. Study of the magnetic properties of CeCu{sub 2}(Si{sub 1-x}Ge{sub x}){sub 2} by means of neutron scattering; Untersuchung der magnetischen Eigenschaften von CeCu{sub 2}(Si{sub 1-x}Ge{sub x}){sub 2} mittels Neutronenstreuung

    Energy Technology Data Exchange (ETDEWEB)

    Faulhaber, Enrico

    2008-07-01

    In 1979 the first heavy-fermion superconductor CeCu{sub 2}Si{sub 2} was discovered by Steglich et al. The system is near a quantum critical point (QCP), where the magnetic order is just suppressed. The distance to the QCP can be varied with hydrostatic pressure as well as by germanium substitution on the silicon site. Next to the superconductivity in CeCu{sub 2}Si{sub 2} one finds distinct magnetic phases while increasing the germanium content. CeCu{sub 2}Si{sub 2} shows a magnetic order of a spin-density-type below T{sub N}-0.8 K, whereas the heavy fermion system CeCu{sub 2}Ge{sub 2} orders below T{sub N}=4.1 K as an antiferromagnet. The focus of this thesis is on neutron-diffraction in the system CeCu{sub 2}(Si{sub 1-x}Ge{sub x}){sub 2}. Starting with a sample with a high germanium content of x=0.45, the magnetic structures are investigated in detail. Following a step-by-step approach, samples with reduced x are investigated subsequently to figure out the properties of pure CeCu{sub 2}Si{sub 2}, which were not accessible before. Furthermore, the complex interaction between magnetism and superconductivity is investigated in detail. Using a specially designed setup, the ac-susceptibility could be recorded simultaneously during the neutron diffraction experiments. Due to the direct correlation between antiferromagnetic signals and diamagnetic features, the microscopic coexistence of superconductivity and magnetic order can be ruled out. Instead, a phase separation on the microscopic scale is found. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-07-01

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

  9. Untangling the cerium and iron contributions to the magnetism of Ce-doped yttrium iron garnet

    Science.gov (United States)

    Herranz, G.; Casals, B.; Cichelero, R.; Fontcuberta, J.; Vasili, H. B.; Gargiani, P.; Valvidares, M.; Herrero-Martin, J.; Pellegrin, E.; Geshev, J.

    Due to their large magneto-optic responses, rare-earth-doped yttrium iron garnets, Y3Fe5O12 (YIG), are highly regarded for their potential in photonics and magnonics. Here we consider the case of Ce-doped YIG (Ce-YIG), in which substitutional Ce3+ ions are magnetic because of their 4f1 ground state. Hence, it is expected that Ce substitution can remarkably impact on the magnetization of YIG. However, it is not completely understood how exactly the Ce ions contribute to the macroscopic magnetic properties. Having this in mind, we have carried out magneto-optical and soft x-ray spectroscopy measurements on Ce-YIG thin films. In particular, we have used the element-specificity of XMCD to extract the individual magnetic hysteresis loops linked to Ce3+ and Fe3+ ions, respectively. Our results show that the doping of YIG with Ce causes a disruption of the electronic and magnetic properties of the parent compound, which results into a reduction of the magnetic coupling between the Ce and Fe magnetic moments, especially at low magnetic fields. Our results are relevant for the understanding of magnetism in rare-earth doped YIG and, eventually, may enable a quantitative evaluation of the magneto-optic properties of rare earth incorporation into YIG.

  10. Ce doped NiO nanoparticles as selective NO2 gas sensor

    Science.gov (United States)

    Gawali, Swati R.; Patil, Vithoba L.; Deonikar, Virendrakumar G.; Patil, Santosh S.; Patil, Deepak R.; Patil, Pramod S.; Pant, Jayashree

    2018-03-01

    Metal oxide gas sensors are promising portable gas detection devices because of their advantages such as low cost, easy production and compact size. The performance of such sensors is strongly dependent on material properties such as morphology, structure and doping. In the present study, we report the effect of cerium (Ce) doping on nickel oxide (NiO) nano-structured thin film sensors towards various gases. Bare NiO and Ce doped NiO nanoparticles (Ce:NiO) were synthesized by sol-gel method. To understand the effect of Ce doping in nickel oxide, various molar percentages of Ce with respect to nickel were incorporated. The structure, phase, morphology and band-gap energy of as-synthesized nanoparticles were studied by XRD, SEM, EDAX and UV-vis spectroscopy. Thin film gas sensors of all the samples were prepared and subjected to various gases such as LPG, NH3, CH3COCH3 and NO2. A systematic and comparative study reveals an enhanced gas sensing performance of Ce:NiO sensors towards NO2 gas. The maximum sensitivity for NO2 gas is around 0.719% per ppm at moderate operating temperature of 150 °C for 0.5% Ce:NiO thin film gas sensor. The enhanced gas sensing performance for Ce:NiO is attributed to the distortion of crystal lattice caused by doping of Ce into NiO.

  11. Fabrication, optical and scintillation properties of transparent YAG:Ce ceramics

    Science.gov (United States)

    Osipov, V. V.; Ishchenko, A. V.; Shitov, V. A.; Maksimov, R. N.; Lukyashin, K. E.; Platonov, V. V.; Orlov, A. N.; Osipov, S. N.; Yagodin, V. V.; Viktorov, L. V.; Shulgin, B. V.

    2017-09-01

    Highly transparent YAG:Ce ceramics (transmission of 72-82% for 2-mm-thick samples in 550-900 nm wavelength range) were fabricated by solid-state reactive sintering using a mixture of Ce2xY2-2xO3 (x = 0.001, 0.01, 0.03, and 0.05) and Al2O3 nanopowders synthesized by laser ablation with an additional round of pre-calcining before compaction. The synthesized YAG:Ce ceramic materials showed intense luminescence with a maximum at 525-545 nm. The measured absolute light yields of the synthesized YAG:Ce ceramics were 18-21 photon/MeV for 1-5 at.% Ce and 5 photon/MeV for 0.1 at.% Ce. The energy resolutions of the fabricated thin ceramic samples (2 mm) under 662 keV gamma ray were measured to be 10-15%. The decay curves of scintillations consisted of two components with the decay times depending on the Ce3+ concentration. The sample doped with 5 at.% of Ce exhibited the main fast component with 26 ns decay time. The measured data was compared to that of YAG:Ce and well-known CsI:Tl single crystal scintillators. The influence of dopant concentration on the optical, luminescence and scintillation properties was discussed.

  12. Investigation of the 600 C isothermal section of the Fe-Al-Ce ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Huiyun; Yin, Fucheng [Xiangtan Univ., Hunan (China). School of Materials Science and Engineering; Xiangtan Univ., Hunan (China). Key Laboratory of Materials Design and Preparation Technology of Hunan Province; Li, Zhi [Xiangtan Univ., Hunan (China). School of Materials Science and Engineering; Xiangtan Univ., Hunan (China). Key Laboratory of Materials Design and Preparation Technology of Hunan Province; Xiangtan Univ., Hunan (China). Key Laboratory of Key Film Materials and Application for Equipment (Hunan province); Ji, Li [South China University of Technology, Guangdong (China). School of Materials Science and Engineering

    2017-01-15

    The isothermal section of the Fe-Al-Ce system at 600 C was determined by means of scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray powder diffraction. Twenty three-phase regions were confirmed experimentally, and two three-phase regions could be deduced in this section. Five ternary compounds, i. e., τ{sub 1}, τ{sub 2}, τ{sub 3}, τ{sub 5}, and τ{sub 6}, exist at 600 C. The Fe{sub 2}Ce phase contains 6.6 at.% Al in the Fe-Al-Ce system. The Fe solubility in α-Al, αAl{sub 11}Ce{sub 3}, αAl{sub 3}Ce, Al{sub 2}Ce, AlCe, and AlCe{sub 3} is approximately 1.7 at.%, 1.1 at.%, 1.2 at.%, 1.3 at.%, 5.8 at.%, and 0.1 at.%, respectively, and the solubility of Ce in α-Al, FeAl{sub 3}, Fe{sub 2}Al{sub 5}, FeAl{sub 2}, and FeAl is approximately 0.1 at.%, 1.2 at.%, 1.9 at.%, 0.9 at.%, and 3.7 at.%, respectively.

  13. Effects of Ce, La and Ba addition on the electrochemical behavior of super duplex stainless steels

    International Nuclear Information System (INIS)

    Yoo, Yun-Ha; Choi, Yoon-Seok; Kim, Jung-Gu; Park, Yong-Soo

    2010-01-01

    The effects of rare earth metal (REM: Ce, La) and Ba addition on aqueous corrosion properties of super duplex stainless steels (SDSS) were investigated by electrochemical tests and surface analyses. The results of potentiodynamic test indicated that the passive range increased by the addition of Ce, La, and Ba, indicating increased relative resistance to localized corrosion. The EIS measurements showed that the Ce-La-Ba-bearing alloys exhibited higher R ct and R p values than the Ce-La-Ba-free alloy at the passive and breakdown states. Furthermore, the additions of REMs and Ba together promoted the formation of dense chromium-enriched passive film.

  14. Complex impedance study on nano-CeO2 coating TiO2

    International Nuclear Information System (INIS)

    Zhang Mei; Wang Honglian; Wang Xidong; Li Wenchao

    2006-01-01

    Titanium dioxide (TiO 2 ) nanoparticles and cerium dioxide (CeO 2 ) nanoparticles coated titanium dioxide (TiO 2 ) nanoparticles (CeO 2 -TiO 2 nanoparticles) have been successfully synthesized by sol-gel method. The complex impedance of the materials was investigated. The grain resistance, boundary resistance and activation energy of the nanoparticles were calculated according to Arrhenius equation. According to calculating results, the active capacity of pure TiO 2 nanoparticles has been improved because of nano-CeO 2 coating. An optimal CeO 2 content of 4.9 mol% was achieved. The high resolution electron microscopy images of CeO 2 -TiO 2 nanoparticles showed that TiO 2 nanoparticles, as a core, were covered by CeO 2 nanoparticles. The average size of CeO 2 coating TiO 2 nanoparticles was about 70 nm. Scanning electron microscopy observation indicted that CeO 2 nanoparticle coating improved the separation, insulation, and stability the CeO 2 -TiO 2 nanoparticles, which was benefit to the activity of materials

  15. Thermopower studies of doped CeAl sub 2 and UAl sub 2

    CERN Document Server

    Park, J G

    1997-01-01

    We have studied the thermopower of U doped CeAl sub 2 and Ce and La doped UAl sub 2. Despite different ground state properties of CeAl sub 2 and UAl sub 2 , the former being an antiferromagnetic heavy-fermion compound and the latter non-magnetic, we have found that not only thermopower data for pure CeAl sub 2 and UAl sub 2 are similar but also the thermopower results of doped samples behave similarly. Although the similarity seen in pure systems is yet to be understood, we interpret the doping effects as the results of changes in energy dependent relaxation time with doping. (author)

  16. Nuclear magnetic resonance investigation of the heavy fermion system Ce2CoAl7Ge4

    Science.gov (United States)

    Dioguardi, A. P.; Guzman, P.; Rosa, P. F. S.; Ghimire, N. J.; Eley, S.; Brown, S. E.; Thompson, J. D.; Bauer, E. D.; Ronning, F.

    2017-12-01

    We present nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements performed on single crystalline Ce2CoAl7Ge4 , a member of a recently discovered family of heavy fermion materials Ce2M Al7Ge4 (M =Co , Ir, Ni, or Pd). Previous measurements indicated a strong Kondo interaction as well as magnetic order below TM=1.8 K . Our NMR spectral measurements show that the Knight shift K is proportional to the bulk magnetic susceptibility χ at high temperatures. A clear Knight shift anomaly (K ¬∝χ ) is observed at coherence temperatures T*˜17.5 K for H0∥c ̂ and 10 K for H0∥a ̂ at the 59Co site, and T*˜12.5 K at the 27Al(3) site for H0∥a ̂ characteristic of the heavy fermion nature of this compound. At high temperatures, the 59Co NMR spin-lattice relaxation rate T1-1 is dominated by spin fluctuations of the 4 f local moments with a weak metallic background. The spin fluctuations probed by 59Co NMR are anisotropic and larger in the basal plane than in the c direction. Furthermore, we find (T1T K ) -1∝T-1 /2 at the 59Co site as expected for a Kondo system for T >T* and T >TK . 59Co NQR T1-1 measurements at low temperatures indicate slowing down of spin fluctuations above the magnetic ordering temperature TM˜1.8 K . A weak ferromagnetic character of fluctuations around q =0 is evidenced by an increase of χ T versus T above the magnetic ordering temperature. We also find good agreement between the observed and calculated electric field gradients at all observed sites.

  17. Site Practice

    DEFF Research Database (Denmark)

    Wahedi, Haseebullah

    2016-01-01

    that the construction phase comprises several communities and practices, leading to various uses of the drawings. The results indicated that the craftsmen used drawings to position themselves in the correct location, and that the site managers and contract managers used them as management tools and legal documents...... different practices in the construction phase. The research is based on an ethnographic study of a case in Denmark. The empirical data were collected through direct observations and semi-structured interviews with site managers, contract managers, foremen and craftsmen. Findings revealed....... It is concluded that the drawings and the physical building play a vital role in relation to coordination within and across the various communities that are in play within the construction phas...

  18. Fermiology of Ce2 Rh3 Ge5

    Science.gov (United States)

    Wartenbe, Mark

    The competition between localized and delocalized f electrons in heavy fermion materials produces a wide variety of interesting physical phenomena. Among these compounds is Ce2Rh3Ge5. This heavy-fermion system undergoes an antiferromagnetic transition below 4K and exhibits an angle dependent magnetic phase transition around 25 tesla. In addition, RF conductivity measurements in pulsed field (65T) have revealed quantum oscillations. Temperature dependence at fixed angle indicates relatively heavy effective masses of values ranging from ~3me on up to ~10me. This indicates that the narrow f-electron density of states is partially hybridized close to the Fermi energy, but also places strict cryogenic constraints upon the measurement (3Helium temperatures are required). Fermi surface calculations have produced complex figures which lend validation to such rich behavior. Presented are updated measurements including magnetization and revised theoretical calculations..

  19. Qu'est-ce que la relativité ?

    CERN Document Server

    Vannucci, François

    2005-01-01

    Publiée en 1905 par Albert Einstein, la théorie de la relativité marqua profondément le XXe siècle. Ce que tout un chacun sait… sans jamais avoir bien compris pourquoi ! François Vannucci commence donc par nous décrypter E=mc2. Car cette fameuse formule résume la révolution qu’apporta la théorie : énergie et masse ne sont plus des quantités indépendantes, elles sont reliées par la vitesse de la lumière. Il nous explique alors en quoi la théorie de la relativité, en établissant le cadre d’une théorie globale de l’univers - une cosmologie -, a révolutionné notre compréhension de l’univers…

  20. Two-orbital model for CeB6

    Science.gov (United States)

    Singh, Dheeraj Kumar

    2017-05-01

    We describe a two-orbital tight-binding model with bases belonging to the Γ8 quartet. It captures several characteristics of the Fermiology unravelled by the recent angle-resolved photoemission spectroscopic (ARPES) measurements on cerium hexaboride CeB6 samples cleaved along different high-symmetry crystallographic directions, which includes the ellipsoid-like Fermi surfaces (FSs) with major axes directed along Γ-X. We calculate various multipolar susceptibilities within the model and identify the susceptibility that shows the strongest divergence in the presence of standard onsite Coulomb interactions and discuss its possible implication and relevance with regard to the signature of strong ferromagnetic correlations existent in various phases as shown by the recent experiments.

  1. Table incremental slow injection CE-CT in lung cancer

    International Nuclear Information System (INIS)

    Yoshida, Shoji; Maeda, Tomoho; Morita, Masaru

    1988-01-01

    The purpose of this study is to evaluate tumor enhancement in lung cancer under the table incremental study with slow injection of contrast media. The early serial 8 sliced images during the slow injection (1.5 ml/sec) of contrant media were obtained. Following the early images, delayed 8 same sliced images were taken in 2 minutes later. Chacteristic enhanced patterns of the primary cancer and metastatic mediastinal lymphnode were recognized in this study. Enhancement of the primary lesion was classified in 4 patterns, irregular geographic pattern, heterogeneous pattern, homogeneous pattern and rim-enhanced pattern. In mediastinal metastatic lymphadenopathy, three enhanced patterns were obtained, heterogeneous, homogeneous and ring enhanced pattern. Some characteristic enhancement patterns according to the histopathological finding of the lung cancer were obtained. With using this incremental slow injection CE-CT, precise information about the relationship between lung cancer and adjacent mediastinal structure, and obvious staining patterns of the tumor and mediastinal lymphnode were recognized. (author)

  2. New limits on 2ε, εβ{sup +} and 2β{sup +} decay of {sup 136}Ce and {sup 138}Ce with deeply purified cerium sample

    Energy Technology Data Exchange (ETDEWEB)

    Belli, P.; Bernabei, R. [INFN Sezione Roma ' ' Tor Vergata' ' , Rome (Italy); Universita di Roma ' ' Tor Vergata' ' , Dipartimento di Fisica, Rome (Italy); Boiko, R.S. [Institute for Nuclear Research, Kyiv (Ukraine); National University of Life and Environmental Sciences of Ukraine, Kyiv (Ukraine); Cappella, F. [INFN Sezione Roma, Rome (Italy); Cerulli, R.; Laubenstein, M. [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Danevich, F.A.; Kropivyansky, B.N.; Polischuk, O.G.; Tretyak, V.I. [Institute for Nuclear Research, Kyiv (Ukraine); Incicchitti, A. [INFN Sezione Roma, Rome (Italy); Universita di Roma ' ' La Sapienza' ' , Dipartimento di Fisica, Rome (Italy); Mokina, V.M. [Institute for Nuclear Research, Kyiv (Ukraine); INFN Sezione Roma, Rome (Italy)

    2017-08-15

    A search for double electron capture (2ε), electron capture with positron emission (εβ{sup +}), and double positron emission (2β{sup +}) in {sup 136}Ce and {sup 138}Ce was realized with a 465 cm{sup 3} ultra-low background HP Ge γ spectrometer over 2299 h at the Gran Sasso underground laboratory. A 627 g sample of cerium oxide deeply purified by liquid-liquid extraction method was used as a source of γ quanta expected in double β decay of the cerium isotopes. New improved half-life limits were set on different modes and channels of double β decay of {sup 136}Ce and {sup 138}Ce at the level of T{sub 1/2} > 10{sup 17}-10{sup 18} yr. (orig.)

  3. Effect of Al deoxidation on the formation behavior of inclusions in Ce-added stainless steel melts

    Science.gov (United States)

    Kwon, Sun Kuk; Kong, Young-Min; Park, Joo Hyun

    2014-09-01

    The effect of Al deoxidation on the oxygen content and the inclusion properties (composition, size and morphology) of Ce-added stainless steel melts at 1873 K was investigated. The total oxygen content was about 310(±40) ppm before Al addition and slightly decreases with holding time when Al content was lower than 0.01%, whereas the oxygen content drastically decreased when Al content was greater than about 0.05%. Al content initially decreased, followed by an increase by addition of Ce, which originates from the reduction of Al2O3 in the refractory and/or inclusions by added Ce. The initial inclusions before Al addition were mainly Mn(Cr)-silicates. When Ce was added without Al deoxidation, small amounts of Ce oxide were detected after Ce addition. However, the content of Ce oxide decreased with holding time, and the inclusion composition reverted to the MnO-SiO2-Cr2O3 system. The initial Mn(Cr)-silicate inclusions transformed to Al2O3-rich inclusions by Al addition, and then Ce2O3 was enriched by Ce addition due to local enrichment of Ce around Al2O3 particles, resulting in the formation of AlCeO3-type inclusions. However, the Ce2O3 in the inclusions was continuously reduced by Al due to higher chemical potential of Al than Ce, finally forming the Al2O3-CeAl11O18 complex inclusions.

  4. Scintillation properties of Ce-doped LuLiF{sub 4} and LuScBO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Yanagida, Takayuki, E-mail: t_yanagi@tagen.tohoku.ac.jp [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Fujimoto, Yutaka [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Kawaguchi, Noriaki [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Tokuyama Corporation, Shibuya 3-chome, Shibuya-ku, Tokyo 150-8383 (Japan); Yokota, Yuui [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Kamada, Kei [Materials Research Laboratory, Furukawa, Co. Ltd., 1-25-13 Kannondai, Tsukuba, Ibaragi 305-0856 (Japan); Totsuka, Daisuke [Nihon Kessho Kogaku Co., Ltd., 810-5 Nobe-cho, Tatebayashi, Gunma 374-0047 (Japan); Hatamoto, Shun-Ichi [Corporate Research and Development Center, Mitsui Mining and Smelting Co., Ltd., 1333-2 Haraichi, Ageo Saitama 362-0023 (Japan); Yoshikawa, Akira; Chani, Valery [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

    2011-10-01

    The crystals of 1 mol% Ce-doped LuLiF{sub 4} (Ce:LLF) grown by the micro-pulling down ({mu}-PD) method and 1 mol% Ce-doped LuScBO{sub 3} (Ce:LSBO) grown by the conventional Czochralski (Cz) method were examined for their scintillation properties. Ce:LLF and Ce:LSBO demonstrated {approx}80% transparency at wavelengths longer than 300 and 400 nm, respectively. When excited by {sup 241}Am {alpha}-ray to obtain radioactive luminescence spectra, Ce{sup 3+} 5d-4f emission peaks were detected at around 320 nm for Ce:LLF and at around 380 nm for Ce:LSBO. In Ce:LSBO, the host luminescence was also observed at 260 nm. By recording pulse height spectra under {gamma}-ray irradiation, the absolute light yield of Ce:LLF and Ce:LSBO was measured to be 3600{+-}400 and 4200{+-}400 ph/MeV, respectively. Decay time kinetics was also investigated using a pulse X-ray equipped streak camera system. The main component of Ce:LLF was {approx}320 ns and that of Ce:LSBO was {approx}31 ns. In addition, the light yield non-proportionality and energy resolution against the {gamma}-ray energy were evaluated.

  5. Photoluminescence properties and energy-level diagrams in (Ce3+, Tb3+)-codoped KCl green phosphor

    International Nuclear Information System (INIS)

    Tosaka, Yuki; Adachi, Sadao

    2014-01-01

    KCl:Ce 3+ , Tb 3+ green phosphor was synthesized from an aqueous solution of KCl–CeCl 3 –TbCl 3 . The synthesized phosphor was investigated using X-ray diffraction analysis, electron probe microanalysis, diffuse reflectance measurements, photoluminescence (PL) analysis, PL excitation spectroscopy, and PL decay measurements. The KCl:Ce 3+ , Tb 3+ phosphor showed a strong Tb 3+ -related emission in the 480–700 nm spectral region. The Tb 3+ -related emission intensity in the codoped phosphor was enhanced more than 300 times compared to that in the Tb 3+ singly doped phosphor. This enhancement in the PL intensity could be attributed to an efficient energy transfer from Ce 3+ to Tb 3+ in the KCl host. The maximum transfer efficiency was η ∼92% for the sample synthesized at a solution of KCl:CeCl 3 :TbCl 3 =1:0.01:0.05 in molar ratio. The (Ce 3+ , Tb 3+ ) concentration dependences of the Ce 3+ - and Tb 3+ -emission decay times were determined. The temperature dependence of the Tb 3+ -related emission intensity was also measured and analyzed from T=20–450 K. - Highlights: • Simple method was developed for synthesizing KCl:Ce 3+ , Tb 3+ green phosphor. • Ce 3+ and Tb 3+ concentrations were optimized to obtain high efficient phosphor. • An efficient energy transfer was observed from Ce 3+ to Tb 3+ in KCl. • Detailed energy-level schemes for Ce 3+ and Tb 3+ ions in KCl were proposed

  6. Exposure of agricultural crops to nanoparticle CeO2in biochar-amended soil.

    Science.gov (United States)

    Servin, Alia D; De la Torre-Roche, Roberto; Castillo-Michel, Hiram; Pagano, Luca; Hawthorne, Joseph; Musante, Craig; Pignatello, Joseph; Uchimiya, Minori; White, Jason C

    2017-01-01

    Biochar is seeing increased usage as an amendment in agricultural soils but the significance of nanoscale interactions between this additive and engineered nanoparticles (ENP) remains unknown. Corn, lettuce, soybean and zucchini were grown for 28 d in two different soils (agricultural, residential) amended with 0-2000 mg engineered nanoparticle (ENP) CeO 2  kg -1 and biochar (350 °C or 600 °C) at application rates of 0-5% (w/w). At harvest, plants were analyzed for biomass, Ce content, chlorophyll and lipid peroxidation. Biomass from the four species grown in residential soil varied with species and biochar type. However, biomass in the agricultural soil amended with biochar 600 °C was largely unaffected. Biochar co-exposure had minimal impact on Ce accumulation, with reduced or increased Ce content occurring at the highest (5%) biochar level. Soil-specific and biochar-specific effects on Ce accumulation were observed in the four species. For example, zucchini grown in agricultural soil with 2000 mg CeO 2  kg -1 and 350 °C biochar (0.5-5%) accumulated greater Ce than the control. However, for the 600 °C biochar, the opposite effect was evident, with decreased Ce content as biochar increased. A principal component analysis showed that biochar type accounted for 56-99% of the variance in chlorophyll and lipid peroxidation across the plants. SEM and μ-XRF showed Ce association with specific biochar and soil components, while μ-XANES analysis confirmed that after 28 d in soil, the Ce remained largely as CeO 2 . The current study demonstrates that biochar synthesis conditions significantly impact interactions with ENP, with subsequent effects on particle fate and effects. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  7. Active species of CeAl(4) in the CeCl(3)-doped sodium aluminium hydride and its enhancement on reversible hydrogen storage performance.

    Science.gov (United States)

    Fan, Xiulin; Xiao, Xuezhang; Chen, Lixin; Yu, Kairong; Wu, Zhe; Li, Shouquan; Wang, Qidong

    2009-11-28

    By directly doping CeAl(4) into sodium aluminium hydride, which probably serves as the active species in the hydriding and dehydriding processes of CeCl(3)-doped NaAlH(4), a high reversible hydrogen capacity of 4.77-4.92 wt% (close to expected capacity of 5.13 wt%) can be achieved in less than 20 min under moderate conditions.

  8. In Situ STM Observation of Nonmagnetic Impurity Effect in MBE-grown CeCoIn5 Films

    Science.gov (United States)

    Haze, Masahiro; Torii, Yohei; Peters, Robert; Kasahara, Shigeru; Kasahara, Yuichi; Shibauchi, Takasada; Terashima, Takahito; Matsuda, Yuji

    2018-03-01

    Local electronic effects in the vicinity of an impurity provide pivotal insight into the origin of unconventional superconductivity, especially when the materials are located on the edge of magnetic instability. In high-temperature cuprate superconductors, a strong suppression of superconductivity and appearance of low-energy bound states are clearly observed near nonmagnetic impurities. However, whether these features are common to other strongly correlated superconductors has not been established experimentally. Here, we report the in situ scanning tunneling microscopy observation of electronic structure around a nonmagnetic Zn impurity in heavy-fermion CeCo(In1-xZnx)5 films, which are epitaxially grown by the state-of-the-art molecular beam epitaxy technique. The films have very wide atomically flat terraces and Zn atoms residing on two different In sites are clearly resolved. Remarkably, no discernible change is observed for the superconducting gap at and around the Zn atoms. Moreover, the local density of states around Zn atoms shows little change inside the c-f hybridization gap, which is consistent with calculations for a periodic Anderson model without local magnetic order. These results indicate that no nonsuperconducting region is induced around a Zn impurity and do not support the scenario of antiferromagnetic droplet formation suggested by indirect measurements in Cd-doped CeCoIn5. These results also highlight a significant difference of the impurity effect between cuprates and CeCoIn5, in both of which d-wave superconductivity arises from the non-Fermi liquid normal state near antiferromagnetic instabilities.

  9. Flux synthesis, modulated crystal structures, and physical properties of REMn0.5SeO (RE = La, Ce)

    International Nuclear Information System (INIS)

    Peschke, Simon; Johrendt, Dirk; Nitsche, Fabian

    2015-01-01

    The selenide oxides REMn 0.5 SeO (RE = La, Ce) were synthesized by heating RE 2 O 3 , RE, Mn, and Se in a NaI/KI flux at 800 C, and their modulated crystal structures determined by X-ray single crystal and powder diffraction {P 1 1 2/n(αβ1/2)0s, Z = 2, LaMn 0.5 SeO: a = 405.7(1), b = 405.7(1), c = 915.2(1) pm, γ = 90 , q = [1/10, -1/10, 1/2]; CeMn 0.5 SeO: a = 402.0(1), b = 401.8(1), c = 910.7(1) pm, γ = 90.000(4) , q = [0.0789(2), -0.0783(2), 1/2]}. The structures are related to the ZrCuSiAs-type structure with ordered vacancies at the manganese sites. The resulting modulations of the checkerboard pattern in the [Mn 0.5 Se] layers can be approximated by 10a x 10b x 2c and 51a x 51b x 2c supercells in LaMn 0.5 SeO and CeMn 0.5 SeO, respectively. Both compounds are insulators. The optical bandgap of LaMn 0.5 SeO was determined to 2.13 eV from the Kubelka-Munk function. Magnetic measurements indicate antiferromagnetic ordering of the Mn 2+ moments with Neel points well above room temperature, as known from related manganese compounds. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Kinetics of oxygen exchange over CeO2-ZrO2 fluorite-based catalysts.

    Science.gov (United States)

    Sadovskaya, Ekaterina M; Ivanova, Yulia A; Pinaeva, Larisa G; Grasso, Giacomo; Kuznetsova, Tatiana G; van Veen, Andre; Sadykov, Vladislav A; Mirodatos, Claude

    2007-05-24

    The kinetics of 18O/16O isotopic exchange over CeO2-ZrO2-La2O3 and Pt/CeO2-ZrO2 catalysts have been investigated under the conditions of dynamic adsorption-desorption equilibrium at atmospheric pressure and a temperature range of 650-850 degrees C. The rates of oxygen adsorption-desorption on Pt sites, support surface, oxygen transfer (spillover) from Pt to the support as well as the amount of oxygen accumulated in the oxide bulk, and oxygen diffusion coefficient were estimated. The nanocrystalline structure of lanthana-doped ceria-zirconia prepared via the Pechini route with a developed network of domain boundaries and specific defects guarantees a high oxygen mobility in the oxide bulk (D = (1.5 / 2.0).10-18 m2 s-1 at 650 degrees C) and allows accumulation of over-stoichiometric/excess oxygen. For Pt/CeO2-ZrO2, oxygen transfer from Pt to support (characteristic time surface. The rate of direct exchange between the gas phase and surface oxygen is increased as well due to the increased concentration (up to 2 monolayers) of surface/near subsurface oxygen species accumulated on the oxygen vacancies (originated from the incorporation of highly dispersed Pt atoms). The characteristic time of diffusion of the oxygen localized in the subsurface layers is about 1 s. The overall quantity of over-stoichiometric oxygen and/or hydroxyl groups accumulated in the bulk can reach the equivalent of 10 monolayers, and characteristic time of oxygen diffusion within the bulk is about 20 s. All these kinetic data are required for the further step of modeling partial oxidation of hydrocarbons under steady- and unsteady-state conditions.

  11. A facile synthesis of high quality nanostructured CeO2 and Gd2O3-doped CeO2 solid electrolytes for improved electrochemical performance.

    Science.gov (United States)

    Kuo, Yu-Lin; Su, Yu-Ming; Chou, Hung-Lung

    2015-06-07

    This study describes the use of a composite nitrate salt solution as a precursor to synthesize CeO2 and Gd2O3-doped CeO2 (GDC) nanoparticles (NPs) using an atmospheric pressure plasma jet (APPJ). The microstructures of CeO2 and GDC NPs were found to be cubical and spherical shaped nanocrystallites with average particle sizes of 10.5 and 6.7 nm, respectively. Reactive oxygen species, detected by optical emission spectroscopy (OES), are believed to be the major oxidative agents for the formation of oxide materials in the APPJ process. Based on the material characterization and OES observations, the study effectively demonstrated the feasibility of preparing well-crystallized GDC NPs by the APPJ system as well as the gas-to-particle mechanism. Notably, the Bader charge of CeO2 and Ce0.9Gd0.1O2 characterized by density function theory (DFT) simulation and AC impedance measurements shows that Gd helps in increasing the charge on Ce0.9Gd0.1O2 NPs, thus improving their conductivity and making them candidate materials for electrolytes in solid oxide fuel cells.

  12. Photocatalytic activity of Ce-modified SBA-15 for the degradation of ...

    Indian Academy of Sciences (India)

    als. Photocatalytic activity evaluation studies are made on all the samples for the degradation of isoproturon. Among them, 0.3 (wt%) Ce-modified Al-SBA-15 catalyst has shown a maximum activity in comparison with Ce-modified. SBA-15. The better activity is attributed to the synergistic effect of mesoporosity and the ...

  13. Toxicity of 144Ce inhaled in a relatively insoluble form by beagle dogs

    International Nuclear Information System (INIS)

    Boecker, B.B.; Hahn, F.F.; Muggenburg, B.A.; Mauderly, J.L.; McClellan, R.O.; Pickrell, J.A.

    1980-01-01

    The metabolism, dosimetry and effects of 144 Ce inhaled in fused aluminosilicate particles are being investigated in the beagle dog to assess the long-term biological consequences of release of relatively insoluble aerosol forms of 144 Ce that could occur in nuclear accidents. The effects resulting from the relatively protracted radiation dose patterns to the lung from this form of 144 Ce are being compared with effects of other radiation dose patterns to the lung. One hundred eleven dogs were exposed to aerosols of 144 Ce in fused aluminosilicate particles to yield initial lung burdens of 0.0024 to 210 μCi/kg body weight and 15 control dogs were exposed to nonradioactive fused aluminosilicate particles. To date, 65 144 Ce-exposed and 2 control dogs have died or were euthanized at 143 to 4578 days after inhalation of 144 Ce. Prominent findings in the 144 Ce-exposed dogs were radiation pneumonitis in 17 dogs that died at early times and neoplastic disease in 39 of the 48 dogs that died 750 days or later. Observations are continuing on the 46 144 Ce-exposed and 13 control dogs remaining alive at this time, at least 3337 days after exposure

  14. Toxicity of 144Ce inhaled in a relatively insoluble form by aged beagle dogs

    International Nuclear Information System (INIS)

    Boecker, B.B.; Hahn, F.F.; Muggenburg, B.A.; Mauderly, J.L.; McClellan, R.O.; Pickrell, J.A.

    1980-01-01

    The toxicity of relatively insoluble 144 Ce inhaled by 8- to 10.5-year-old beagle dogs is being investigated to provide information on possible age-related differences in the resulting long-term biological responses. Forty-two dogs were exposed, nose-only, to aerosols of 144 Ce in fused aluminosilicate particles to yield initial lung burdens of 2.2 to 75 μCi 144 Ce/kg body weight, and 12 control dogs were exposed to nonradioactive fused aluminosilicate particles. To date, 38 144 Ce-exposed dogs and 10 control dogs have died or were euthanized between 197 and 2375 days after inhalation of the 144 Ce. Prominent findings in the 144 Ce-exposed dogs were radiation pneumonitis in 19 dogs that died during the first 943 days post-exposure and neoplastic disease in seven of the 15 dogs. However, only one of these tumors killed the dog. No hemangiosarcomas have been observed in this study, although they were a prominent finding in immature or young adult dogs exposed to 144 Ce. Observations are continuing on the four surviving 144 Ce-exposed and two control dogs

  15. The influence of age on the retention of 141Ce in rats

    International Nuclear Information System (INIS)

    Kargachin, B.; Kostial, K.

    1988-01-01

    The influence of age on 141 Ce retention after oral and intraperitoneal administration was studied in 1 and 6-7 week-old rats. Older rats received 141 Ce orally by stomach tube while sucklings received it by the method of artificial feeding with a dropper. Retention of 141 Ce was determined in the whole body, carcass and organs (liver, bone, kidneys, brain, skin) 6, 12 and 18 days after 141 Ce intraperitoneal application, 6 and 12 days after oral application in sucklings and 1 day after oral application in older rats. Present results show higher values of retention in younger than in older rats both after oral and intraperitoneal 141 Ce administration. The whole body retention in sucklings 18 days after 141 Ce intraperitoneal administration was 1.4 times higher than in older animals. Retention was also significantly higher in skin, brain, bone, and kidneys. Age-related difference in retention was even more pronounced after 141 Ce oral administration. 141 Ce retention in younger animals was 2-3 orders of magnitude higher than in older ones. Present study once again indicates the importance of age in radionuclide metabolism. (author). 4 refs.; 1 tab

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  19. Charge dynamics in the Kondo insulator Ce3Bi4Pt3

    International Nuclear Information System (INIS)

    Bucher, B.; Schlesinger, Z.; Canfield, P.C.; Fisk, Z.

    1994-01-01

    We report the reflectivity and optical conductivity of the Kondo insulator Ce 3 Bi 4 Pt 3 . For temperatures less than 100 K, depletion of the conductivity below about 300 cm -1 signifies the development of a charge gap. The temperature dependence of the disappearance of the spectral weight scales with the quenching of the Ce 4f moments. ((orig.))

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  1. Ce que nous faisons | Page 132 | CRDI - Centre de recherches pour ...

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  2. Spin-glass, antiferromagnetism and Kondo behavior in Ce2Au1 ...

    Indian Academy of Sciences (India)

    report high pressure electrical resistivity of Ce2AuSi3, ac susceptibility (χ) and magnetoresistance of various alloys of this solid solution in order to gain better knowledge of the magnetism of these alloys. High pressure resistivity behavior is consistent with the proposal that Ce2AuSi3 lies at the left-hand side of the maximum ...

  3. Structure of negative parity yrast bands in odd mass 125−131Ce ...

    Indian Academy of Sciences (India)

    4. — journal of. April 2010 physics pp. 525–539. Structure of negative parity yrast bands in odd mass 125−131Ce nuclei. ARUN BHARTI∗, SURAM SINGH and S K KHOSA. Department of ... in 125Ce have been extensively studied up to very high spins in recent years [3,4]. ... The detailed theory of PSM is given in [12].

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  7. Optical properties of pure and Ce3+ doped gadolinium gallium garnet crystals and epitaxial layers

    International Nuclear Information System (INIS)

    Syvorotka, I.I.; Sugak, D.; Wierzbicka, A.; Wittlin, A.; Przybylińska, H.; Barzowska, J.; Barcz, A.; Berkowski, M.; Domagała, J.; Mahlik, S.; Grinberg, M.; Ma, Chong-Geng

    2015-01-01

    Results of X-ray diffraction and low temperature optical absorption measurements of cerium doped gadolinium gallium garnet single crystals and epitaxial layers are reported. In the region of intra-configurational 4f–4f transitions the spectra of the bulk crystals exhibit the signatures of several different Ce 3+ related centers. Apart from the dominant center, associated with Ce substituting gadolinium, at least three other centers are found, some of them attributed to the so-called antisite locations of rare-earth ions in the garnet host, i.e., in the Ga positions. X-ray diffraction data prove lattice expansion of bulk GGG crystals due to the presence of rare-earth antisites. The concentration of the additional Ce-related centers in epitaxial layers is much lower than in the bulk crystals. However, the Ce-doped layers incorporate a large amount of Pb from flux, which is the most probable source of nonradiative quenching of Ce luminescence, not observed in crystals grown by the Czochralski method. - Highlights: • Ce 3+ multicenters found in Gadolinium Gallium Garnet crystals and epitaxial layers. • High quality epitaxial layers of pure and Ce-doped GGG were grown. • Luminescence quenching of Ce 3+ by Pb ions from flux detected in GGG epitaxial layers. • X-ray diffraction allows measuring the amount of the rare-earth antisites in GGG

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  9. Recent advances in CE-MS: Synergy of wet chemistry and instrumentation innovations.

    Science.gov (United States)

    Pantůčková, Pavla; Gebauer, Petr; Boček, Petr; Křivánková, Ludmila

    2011-01-01

    CE with MS detection is a hyphenated technique which greatly improves the ability of CE to deal with real samples, especially with those coming from biology and medicine, where the target analytes are present as trace amounts in very complex matrices. CE-MS is now almost a routine technique performed on commercially available instruments. It faces currently a tremendous development of the technique itself as well as of its wide application area. Great interest in CE-MS is reflected in the scientific literature by many original research articles and also by numerous reviews. The review presented here has a general scope and belongs to a series of regularly published reviews on the topic. It covers the literature from the last 2 years, since January 2008 till June 2010. It brings a critical selection of related literature sorted into groups reflecting the main topics of actual scientific interest: (i) innovations in CE-ESI-MS, (ii) use of alternative interfaces, and (iii) ways to enhance sensitivity. Special attention is paid to novel electrolyte systems amenable to CE-MS including nonvolatile BGEs, to advanced CE separation principles such as MEKC, MEEKC, chiral CE, and to the use of preconcentration techniques. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Novel nanostructured CeO 2 as efficient catalyst for energy and ...

    Indian Academy of Sciences (India)

    We report here versatile methods to engineer the microstructure and understand the fundamental physicochemical properties of CeO2 to improve its catalytic viability for practical applications. In this context, different morphologies of CeO2 are synthesized using tailored homogeneous precipitation methods and ...

  11. Alteration of steenstrupine-(Ce) from the Ilímaussaq alkaline complex, South Greenland

    DEFF Research Database (Denmark)

    Karup-Møller, Sven; Rose-Hansen, John

    2017-01-01

    Steenstrupine-(Ce) from two localities, Taseq and Mellemelv, both in the Ilímaussaq complex of South Greenland has been studied. At Taseq ussingite veins contain idiomorphic steenstrupine-(Ce) crystals with decomposed central parts, marginal zones of very thin rhythmically/oscillatory precipitate...

  12. Data of evolutionary structure change: 1CE7A-1OBSA [Confc[Archive

    Lifescience Database Archive (English)

    Full Text Available 1CE7A-1OBSA 1CE7 1OBS A A YERGDLDVTAQTTGAGYFSFITLLRDYVSSG-SFSNAIP...>1OBS A 1OBSA RLTTGADVRHE GLN CA 246 1OBS A 1OBSA...in>A 1OBSA ALYYYSTGGTQLPT ...n14> 1OBS A 1OBSA

  13. A novel sensitive sheathless CE-MS device for peptide and protein analysis

    DEFF Research Database (Denmark)

    Nguyen, Tam T. T. N.; Petersen, Nickolaj J.; Rand, Kasper Dyrberg

    on the generation of an electric contact for both CE and ESI voltage through a narrow fracture close to the end of the CE capillary. The interface was mounted on a Nano ESI source of a hybrid Q-TOF instrument. To eliminate unwanted surface adsorption and/or interactions between polypeptide analytes and the inner...

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  16. How BenMAP-CE Estimates the Health and Economic Effects of Air Pollution

    Science.gov (United States)

    The BenMAP-CE tool estimates the number and economic value of health impacts resulting from changes in air quality - specifically, ground-level ozone and fine particles. Learn what data BenMAP-CE uses and how the estimates are calculated.

  17. Facile synthesis of ferromagnetic Ni doped CeO2 nanoparticles with enhanced anticancer activity

    Science.gov (United States)

    Abbas, Fazal; Jan, Tariq; Iqbal, Javed; Ahmad, Ishaq; Naqvi, M. Sajjad H.; Malik, Maaza

    2015-12-01

    NixCe1-xO2 (where x = 0, 0.01, 0.03, 0.05 and 0.07) nanoparticles were synthesized by soft chemical method and were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman, UV-vis absorption spectroscopy and vibrating sample magnetometer (VSM). XRD and Raman results indicated the formation of single phase cubic fluorite structure for the synthesized nanoparticles. Ni dopant induced excessive structural changes such as decrease in crystallite size as well as lattice constants and enhancement in oxygen vacancies in CeO2 crystal structure. These structural variations significantly influenced the optical and magnetic properties of CeO2 nanoparticles. The synthesized NixCe1-xO2 nanoparticles exhibited room temperature ferromagnetic behavior. Ni doping induced effects on the cytotoxicity of CeO2 nanoparticles were examined against HEK-293 healthy cell line and SH-SY5Y neuroblastoma cancer cell line. The prepared NixCe1-xO2 nanoparticles demonstrated differential cytotoxicity. Furthermore, anticancer activity of CeO2 nanoparticles observed to be significantly enhanced with Ni doping which was found to be strongly correlated with the level of reactive oxygen species (ROS) production. The prepared ferromagnetic NixCe1-xO2 nanoparticles with differential cytotoxic nature may be potential for future targeted cancer therapy.

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  19. Synthesis of Mn-doped CeO2 nanorods and their application as ...

    Indian Academy of Sciences (India)

    as humidity sensors. C H HU, C H XIA. ∗. , F WANG, M ZHOU, P F YIN and X Y HAN. Science College of Chongqing Jiaotong University, Chongqing 400074, PR China. MS received 10 October 2010; revised 21 December 2010. Abstract. Mn-doped CeO2 nanorods have been prepared from CeO2 particles through a facile ...

  20. Preparation and properties of Pr 3/Ce 3: YAG phosphors using ...

    Indian Academy of Sciences (India)

    Keywords. Co-precipitation; YAG powder; phosphor; white-light LED; ceramic. Abstract. Pr 3 + /Ce 3 + :YAG precursors were co-precipitated using triethanolamine as dispersant and pH regulator. The different dosages of triethanolamine (D) vs. the properties of Pr 3 + /Ce 3 + :YAG phosphors were discussed. When D = 0.5 ...

  1. Ce que nous faisons | Page 47 | CRDI - Centre de recherches pour ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Le CRDI appuie des travaux de recherche dans les pays en voie de développement en vue de produire un changement réel et durable. Ce savoir peut servir d'outil pour résoudre des problèmes mondiaux urgents. Nous partageons ce savoir avec les autres en :

  2. Preparation and characterization of Ce-doped HfO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gálvez-Barboza, S. [Centro de Investigación en Química Aplicada, Departamento de Materiales Avanzados, Blvd. Enrique Reyna Hermosillo #140, C.P. 25294 Saltillo, Coahuila (Mexico); Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. Industria Metalúrgica # 1062 Parque Industrial, C.P. 25900 Ramos Arizpe, Coahuila (Mexico); González, L.A. [Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. Industria Metalúrgica # 1062 Parque Industrial, C.P. 25900 Ramos Arizpe, Coahuila (Mexico); Puente-Urbina, B.A.; Saucedo-Salazar, E.M. [Centro de Investigación en Química Aplicada, Departamento de Materiales Avanzados, Blvd. Enrique Reyna Hermosillo #140, C.P. 25294 Saltillo, Coahuila (Mexico); García-Cerda, L.A., E-mail: luis.garcia@ciqa.edu.mx [Centro de Investigación en Química Aplicada, Departamento de Materiales Avanzados, Blvd. Enrique Reyna Hermosillo #140, C.P. 25294 Saltillo, Coahuila (Mexico)

    2015-09-15

    Highlights: • Ce-doped HfO{sub 2} nanoparticles were prepared by a modified solgel method. • Ce-doped HfO{sub 2} nanoparticles have a semispherical shape with sizes between 6 and 11.5 nm. • The samples doped with 10% in weight of Ce directly crystallized in a cubic structure. • A quick, straightforward and effective route for the preparation of Ce-doped nanoparticles. - Abstract: A modified solgel method to synthesize Ce-doped HfO{sub 2} nanoparticles was carried out using a precursor material prepared with cerium nitrate, hafnium chloride, citric acid and ethylene glycol. The obtained precursor material was calcined at 500 and 700 °C for 2 h in air. The influence of the concentration of Ce and the calcination temperature was studied to observe the structural and morphological changes of the obtained materials. For the characterization, X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman scattering (RS) were employed. The XRD patterns shown that the Ce-doped HfO{sub 2} undergoes a structural transformation from monoclinic to cubic phase, which is significantly dependent on the Ce content and calcination temperature. TEM images have also confirmed the existence of semispherical nanoparticles with sizes between 6 and 11.5 nm.

  3. Ce que nous faisons | Page 145 | CRDI - Centre de recherches pour ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Le CRDI appuie des travaux de recherche dans les pays en voie de développement en vue de produire un changement réel et durable. Ce savoir peut servir d'outil pour résoudre des problèmes mondiaux urgents. Nous partageons ce savoir avec les autres en :

  4. Ce3+-sensitized red Mn2+ luminescence in calcium aluminoborate phosphor material

    Science.gov (United States)

    Puchalska, M.; Zych, E.

    2017-12-01

    Ce3+ doped and Ce3+,Mn2+ co-doped calcium aluminoborate (CAB) phosphors were synthesised by solid-state reaction method and their optical properties were studied. X-ray powder diffraction, SEM and TEM studies indicated the crystallization of the main trigonal CaAl2B2O7 phase and the presence of an additional non-crystalline phase. It was also observed that increasing dopant concentration promotes phase separation. Hence, both series of phosphors demonstrated the changes in luminescence properties via activator concentration variation. Upon UV excitation (λex = 310 nm) Ce3+ doped and Ce3+,Mn2+ co-doped materials yielded intensive blue and pinkish luminescence, respectively. The spectra of CAB:Ce3+ samples showed a broad emission band due to 5d→4f transition of Ce3+, which broadened and shifted to longer wavelengths with increasing dopant content. Mn2+ co-doping caused appearance of another broad-band emission with a maximum of 680 nm, resulting from the 4T1(4G) →6A1(6S) transition of Mn2+. Detailed analysis of the emission and excitation spectra as well as decay time traces as a function of dopant concentration showed that efficient resonant energy transfer mainly occurs between Ce3+ and Mn2+ incorporated in the non-crystalline phase in CAB material. The estimated values of energy transfer efficiency of CAB:Ce3+(3%),Mn2+(4%) is close to 52%.

  5. Influence of microgravity on Ce-doped Bi12 SiO20 crystal defect

    Indian Academy of Sciences (India)

    TECS

    Abstract. Space grown BSO crystal doped with Ce was characterized by means of X-ray fluorescence spectra,. X-ray topography, dislocation density etc. Influence of microgravity on Ce-doped BSO crystal defect was studied by comparing space grown BSO crystal with ground grown one. These results show that composi-.

  6. Ordering and Fluctuation of Quantum Multipoles in CeB6

    International Nuclear Information System (INIS)

    Shiina, R.

    2003-01-01

    The effect of multipolar fluctuations on the quadrupolar phase transition in CeB 6 is investigated theoretically. It is shown that the fluctuations become strong and field-dependent, reflecting the competition of coupled multipolar interactions. Some unusual phenomena around the transition in CeB 6 are shown to be reasonably explained within the RKKY model. (author)

  7. Ce que nous faisons | Page 125 | CRDI - Centre de recherches pour ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Le CRDI appuie des travaux de recherche dans les pays en voie de développement en vue de produire un changement réel et durable. Ce savoir peut servir d'outil pour résoudre des problèmes mondiaux urgents. Nous partageons ce savoir avec les autres en :

  8. Scintillation and optical stimulated luminescence of Ce-doped CaF2

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Fujimoto, Yutaka; Watanabe, Kenichi; Fukuda, Kentaro; Kawaguchi, Noriaki; Miyamoto, Yuka; Nanto, Hidehito

    2014-01-01

    Scintillation and optical stimulated luminescence of Ce 0.1–20% doped CaF 2 crystals prepared by Tokuyama Corp. were investigated. In X-ray induced scintillation spectra, luminescence due to Ce 3+ 5d–4f transition appeared around 320 nm with typically 40 ns decay time. By 241 Am 5.5 MeV α-ray irradiation, 0.1% doped one showed the highest scintillation light yield and the light yield monotonically decreased with Ce concentrations. Optically stimulated luminescence after X-ray irradiation was observed around 320 nm under 550 or 830 nm stimulation in all samples. As a result, intensities of optically stimulated luminescence were proportional to Ce concentrations. Consequently, scintillation and optically stimulated luminescence resulted to have a complementary relation in Ce-doped CaF 2 system. - Highlights: • Optical, scintillation, and OSL properties of Ce 0.1–20% doped CaF 2 were studied. • Scintillation light yield exhibited inverse proportionality to Ce concentrations. • OSL intensities showed proportionality to Ce concentrations. • Complementary relation of scintillation and OSL was experimentally confirmed

  9. Influence of microgravity on Ce-doped Bi12 SiO20 crystal defect

    Indian Academy of Sciences (India)

    Space grown BSO crystal doped with Ce was characterized by means of X-ray fluorescence spectra, X-ray topography, dislocation density etc. Influence of microgravity on Ce-doped BSO crystal defect was studied by comparing space grown BSO crystal with ground grown one. These results show that compositional ...

  10. Nuclear magnetic resonance of Ce(Co sub 1 sub - sub x Fe sub x) sub 4 B (0 <= x <= 0.20)

    CERN Document Server

    Yoshie, H; Honda, H; Takahashi, W; Amako, Y; Nagai, H; Wada, H; Shiga, M; Yoshimura, K

    2002-01-01

    The nuclear magnetic resonance of sup 5 sup 9 Co nuclei in magnetic domains of Ce(Co sub 1 sub - sub x Fe sub x) sub 4 B (0 <= x <= 0.20) has been measured under external magnetic fields up to 5T at 4.2K. Spin reorientation was observed, which is a change in the magnetization direction from that parallel to the c-axis below Fe concentration x=0.1 to that perpendicular to the c axis above x=0.20. The sup 5 sup 9 Co hyperfine field at the 6i site in Ce(Co sub 1 sub - sub x Fe sub x) sub 4 B is divided into two above x=0.20 associated with the spin reorientation.

  11. Session 6: Diesel exhaust abatement: effect of SO{sub 2} and water on Ba,K, Co/CeO{sub 2} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Peralta, M.A.; Cornaglia, L.C.; Miro, E.E.; Querini, C.A. [INCAPE (CONICET-UNL), Santa Fe (Argentina)

    2004-07-01

    In this paper, the stability of Ba,K,Co/CeO{sub 2} catalysts is studied. The Ba,K/CeO{sub 2} catalysts display very good activity for soot oxidation, being able to fully remove it at temperatures below 400 C. The stability to thermal treatment is very good up to 700 C, even in the presence of water in the gas phase. Water does not modify the surface composition. However, the SO{sub 2} strongly affect the ability of this catalyst to oxidize the soot. The formation of barium and potassium sulfate is the reason, by a twofold effect: the spread of the barium sulfate that covers the ceria oxide, and the poisoning of the basic sites provided by potassium, thus removing the reaction paths via a CO{sub 2}-type intermediate. (authors)

  12. On the mechanism of nanoparticulate CeO{sub 2} toxicity to freshwater algae

    Energy Technology Data Exchange (ETDEWEB)

    Angel, Brad M., E-mail: Brad.Angel@csiro.au [Centre for Environmental Contaminants Research, CSIRO Land and Water Flagship, Locked Bag 2007, Kirrawee, NSW 2232 (Australia); Vallotton, Pascal [Digital Productivity Flagship, CSIRO, North Ryde, NSW 1670 (Australia); Apte, Simon C. [Centre for Environmental Contaminants Research, CSIRO Land and Water Flagship, Locked Bag 2007, Kirrawee, NSW 2232 (Australia)

    2015-11-15

    Highlights: • Nanoparticulate CeO{sub 2} less toxic than micron-sized CeO{sub 2}. • UV light filters prevented ROS generation by CeO{sub 2}. • ROS not toxic mechanism: CeO{sub 2} toxicity was similar in presence and absence of ROS. • Strong sorption of nanoparticulate CeO{sub 2} to Pseudokirchneriella subcapitata in synthetic fresh water. • CeO{sub 2} sorption to cells was prevented and toxicity mitigated in the presence of DOC. - Abstract: The factors affecting the chronic (72-h) toxicity of three nanoparticulate (10–34 nm) and one micron-sized form of CeO{sub 2} to the green alga, Pseudokirchneriella subcapitata were investigated. To characterise transformations in solution, hydrodynamic diameters (HDD) were measured by dynamic light scatter, zeta potential values by electrophoretic mobility, and dissolution by equilibrium dialysis. The protective effects of humic and fulvic dissolved organic carbon (DOC) on toxicity were also assessed. To investigate the mechanisms of algal toxicity, the CytoViva hyperspectral imaging system was used to visualise algal–CeO{sub 2} interactions in the presence and absence of DOC, and the role of reactive oxygen species (ROS) was investigated by ‘switching off’ ROS production using UV-filtered lighting conditions. The nanoparticulate CeO{sub 2} immediately aggregated in solution to HDDs measured in the range 113–193 nm, whereas the HDD and zeta potential values were significantly lower in the presence of DOC. Negligible CeO{sub 2} dissolution over the time course of the bioassay ruled out potential toxicity from dissolved cerium. The nanoparticulate CeO{sub 2} concentration that caused 50% inhibition of algal growth rate (IC50) was in the range 7.6–28 mg/L compared with 59 mg/L for micron-sized ceria, indicating that smaller particles were more toxic. The presence of DOC mitigated toxicity, with IC50s increasing to greater than 100 mg/L. Significant ROS were generated in the nanoparticulate CeO{sub 2

  13. CeCo5 thin films with perpendicular anisotropy grown by molecular beam epitaxy

    Science.gov (United States)

    Sharma, S.; Hildebrandt, E.; Major, M.; Komissinskiy, P.; Radulov, I.; Alff, L.

    2018-04-01

    Buffer-free, highly textured (0 0 1) oriented CeCo5 thin films showing perpendicular magnetic anisotropy were synthesized on (0 0 1) Al2O3 substrates by molecular beam epitaxy. Ce exists in a mixture of Ce3+ and Ce4+ valence states as shown by X-ray photoelectron spectroscopy. The first anisotropy constant, K1, as measured by torque magnetometry was 0.82 MJ/m3 (8.2 ×106erg /cm3) . A maximum coercivity of 5.16 kOe with a negative temperature coefficient of -0.304%K-1 and a magnetization of 527.30 emu/cm3 was measured perpendicular to the film plane at 5 K. In addition, a large anisotropy of the magnetic moment of 15.5% was observed. These magnetic parameters make CeCo5 a potential candidate material for spintronic and magnetic recording applications.

  14. The magnetic properties of Ce/Pd surface alloys investigated using DFT

    KAUST Repository

    Shuttleworth, I.G.

    2014-06-01

    The surface alloys that form between Ce and Pd(1 1 1), Pd(1 0 0) and both unreconstructed and missing-row type Pd(1 1 0) at low Ce coverage ( θCe=19ML) have shown permanent magnetism that is mediated in part by an RKKY-like delocalized Ce 6s-Pd 5s interaction. The Pd 4d states are significantly affected by alloying and their behavior cannot be explained by a purely spin-dependent Hamiltonian. Experimental observations of changes to the Pd 4d states are explained and the implications of Ce/Pd magnetism in reforming catalysis are discussed. © 2014 Elsevier B.V. All rights reserved.

  15. Numerical simulation of shock wave dynamics and detonation phenomena with using improved CE/SE method

    International Nuclear Information System (INIS)

    Zhang, D.-L.

    2005-01-01

    The space-time conservation element and solution element (CE/SE) method is a new numerical method to solve the equations of conservation laws in fluid dynamics. It differs substantially in both concept and methodology from the current numerical methods. It has some marked advantages: generality, simple, high efficiency, high resolution and enforcing flux conservation strictly in space and time. In this paper the CE/SE method has been improved. The improved CE/SE method was applied into the interaction of shock wave and detonation with vortex. Several numerical examples were given. Numerical results of improved CE/SE method were compared with the results of experiments and other computational method. The compared results have showed that the improved CE/SE method is a more prospective scheme. (author)

  16. Theoretical study of Ce2+ cubic centres in alkaline earth fluoride crystals

    International Nuclear Information System (INIS)

    Popov, N.; Mysovsky, A.; Shendrik, R.; Radzhabov, E.

    2016-01-01

    In this paper we present theoretical study of Ce 2+ impurity centres in alkaline earth fluoride crystals (CaF 2 , SrF 2 ). Only cubic configurations of centres were considered. Electronic levels and related properties were studied using CASSCF/CASPT2 approach within embedded-cluster formalism including scalar relativistic corrections and spin-orbital interaction. Calculated absorption spectra for Ce 2+ in CaF 2 and SrF 2 are in good agreement with experimental data. For both crystals the ground state of Ce 2+ ion has predominantly 4f 1 5d 1 singlet character. - Highlights: • Ab inito study of Ce 2+ impurity centres in alkaline earth fluoride crystals. • Calculated Ce 2+ ground state in CaF 2 and SrF 2 is predominantly 4f 1 5d 1 singlet. • Calculated absorption spectra are in good agreement width experimental data.

  17. Preparation of nanosized yttrium doped CeO2 catalyst used for photocatalytic application

    Directory of Open Access Journals (Sweden)

    A. Akbari-Fakhrabadi

    2015-09-01

    Full Text Available In the present work, the pure CeO2 and yttrium doped CeO2 nanopowders were synthesized by the nitrate-fuel self-sustaining combustion method and calcined at 700 °C for 2 h. X-ray diffraction (XRD and high resolution electron transmission microscopy (HRTEM results demonstrated a cubic fluorite with high purity and the crystallite sizes less than 20 nm calculated from Scherrer’s formula. The BET specific surface area of yttrium doped CeO2 samples showed high values than those of pure CeO2. The photocatalytic activity of yttrium doped CeO2 showed high degradation of Rhodamine B solution under visible light illumination.

  18. Relationship between Microstructure and Properties of Cu-Cr-Ag-(Ce) Alloy Using Microscopic Investigation.

    Science.gov (United States)

    Chen, Huiming; Yuan, Dawei; Wu, Shanjiang; Wang, Hang; Xie, Weibin; Yang, Bin

    2017-01-01

    Microstructure, precipitation hardening response, and mechanical and physical properties of Cu-Cr-Ag alloy and Cu-Cr-Ag-Ce alloy have been investigated using transmission electron microscopy, scanning electron microscope, optical microscope, electrical conductivity analysis, and tensile test. The influence of element Ce on the matrix refinement, impurity removal, and precipitation in the Cu-Cr-Ag alloys has been analyzed. The experimental results show that the strength and electrical conductivity of Ce containing alloys are greater than those of Ce-free alloys after each processing step. Improvement of strength and electrical conductivity of the Cu-Cr-Ag alloy by adding Ce element is attributed to removing oxygen and sulfur from as-cast alloy.

  19. Site Restoration

    International Nuclear Information System (INIS)

    Noynaert, L.; Bruggeman, A.; Cornelissen, R.; Massaut, V.; Rahier, A.

    2002-01-01

    The objectives, the programme, and the achievements of SCK-CEN's Site Restoration Department for 2001 are described. Main activities include the decommissioning of the BR3 PWR-reactor as well as other clean-up activities, projects on waste minimisation and the management of spent fuel and the flow of dismantled materials and the recycling of materials from decommissioning activities based on the smelting of metallic materials in specialised foundries. The department provides consultancy and services to external organisations and performs R and D on new techniques including processes for the treatment of various waste components including the reprocessing of spent fuel, the treatment of tritium, the treatment of liquid alkali metals into cabonates through oxidation, the treatment of radioactive organic waste and the reconditioning of bituminised waste products

  20. Site Restoration

    Energy Technology Data Exchange (ETDEWEB)

    Noynaert, L.; Bruggeman, A.; Cornelissen, R.; Massaut, V.; Rahier, A

    2002-04-01

    The objectives, the programme, and the achievements of SCK-CEN's Site Restoration Department for 2001 are described. Main activities include the decommissioning of the BR3 PWR-reactor as well as other clean-up activities, projects on waste minimisation and the management of spent fuel and the flow of dismantled materials and the recycling of materials from decommissioning activities based on the smelting of metallic materials in specialised foundries. The department provides consultancy and services to external organisations and performs R and D on new techniques including processes for the treatment of various waste components including the reprocessing of spent fuel, the treatment of tritium, the treatment of liquid alkali metals into cabonates through oxidation, the treatment of radioactive organic waste and the reconditioning of bituminised waste products.

  1. Mochovce site

    International Nuclear Information System (INIS)

    1997-01-01

    In Mochovce site the construction of four units of WWER 440 NPP with V-213 type of reactor is being carried out. The financing of Mochovce units completion was resolved in April 1996. The completion work commenced at the construction site under leadership of SKODA Prague, the general supplier. The completion work on building part and tests of constructional electric distributions and lightning constructors started. The revisions in technological part were finished, and final protocols from revisions are the basis for starting of completion work. The assembly of transport container anchorage,ventilation system in hermetic areas and hermetic coverage of pools for stored spent nuclear fuel is being carried out. The pre-completion tests of instrumentation and control of ventilation systems, individual dosimetric control in medical station, and tests of nuclear programme according to commissioning and assembling work schedule at the equipment for physical protection of the NPP area started. Inspection activities at Mochovce were performed in accordance with inspection plan for 1996. Evaluation of routine inspections was performed by means of quarterly protocols. Main findings from the inspections performed in Mochovce were in the following areas: (a) deficiencies in the knowledge of the respective regulation and conditions from the Resolution of the state regulatory body, concerning selected employees; (b) training of the selected employees; (c) aim of the measures imposes by inspectors is to eliminate deficiencies in preparation of programmes for pre-completion and completion testing. NRA SR assessment activities at Mochovce NPP were focused mainly on approving and inspecting of design modification to approving programmes for pre-completion and completion testing of system s and equipment and on approving quality assurance programmes. The suggestions of international missions, which reviewed Mochovce safety in the years, were taken into consideration in the programme

  2. Inverse CeO2sbnd Fe2O3 catalyst for superior low-temperature CO conversion efficiency

    Science.gov (United States)

    Luo, Yongming; Chen, Ran; Peng, Wen; Tang, Guangbei; Gao, Xiaoya

    2017-09-01

    The paper presents a rational design of highly efficient and affordable catalysts for CO oxidation with a low operating temperature. A series of ceria-iron catalysts were inversely built via a co-precipitation method. The catalytic activity of low-temperature CO oxidation was much higher with CeO2-modified Fe2O3 (CeO2sbnd Fe2O3) than with Fe2O3-modified CeO2 (Fe2O3sbnd CeO2). In particular, the 7.5% CeO2sbnd Fe2O3 catalyst had the highest activity, reaching 96.17% CO conversion at just 25 °C. Catalyst characterization was carried out to explore the cause of the significantly different CO conversion efficiencies between the Fe2O3sbnd CeO2 and Fe2O3sbnd CeO2 catalysts. HRTEM showed a significant inhomogeneous phase in 7.5% CeO2sbnd Fe2O3 with small CeO2 nanoparticles highly dispersed on the rod-shaped Fe2O3 surface. Furthermore, the 7.5% CeO2sbnd Fe2O3 composite catalyst exhibited the highest ratios of Fe2+/Fe3+ and Ce3+/Ce4+ as well as the largest pore volume. These properties are believed to benefit the CO conversion in 7.5% CeO2sbnd Fe2O3.

  3. Luminescent properties of Y3Al5−xGaxO12:Ce crystals

    International Nuclear Information System (INIS)

    Zorenko, Yu.; Zorenko, T.; Malinowski, P.; Sidletskiy, O.; Neicheva, S.

    2014-01-01

    Absorption, luminescent and scintillation properties of Ce 3+ doped Y 3 Al 5−x Ga x O 12 crystals with Ga content in the x=1–5 range were investigated in this work and compared with the properties of YAG:Ce crystals. Apart from the traditional spectral methods (absorption, cathodoluminescence and light yield measurements), the intrinsic and Ce 3+ related luminescence of Y 3 Al 5−x Ga x O 12 :Ce solid-solution were also investigated using the luminescent spectroscopy under excitation by synchrotron radiation in the 3.7–25 eV range. We show that the optical properties Y 3 Al 5−x Ga x O 12 :Ce garnets monotonically change with increasing the Ga content in the x=0–3 range due to preferable localization of Ga ions in the tetrahedral position of the garnet lattice. At the highest Ga concentration (x>3) the deviation of the optical properties of Y 3 Al 5−x Ga x O 12 :Ce garnets is observed from the respective properties of these crystals with Ga content in the x=0–3 range due to occupation by Ga ions of the octahedral position in the garnet host. - Highlights: • Different dependence of optical properties of Y 3 Al 5−x Ga x O 12 :Ce crystals on Ga content in x=0–3 and 3–5 ranges. • Elimination of the luminescence of Y Al antisite defects in Y 3 Al 5−x Ga x O 12 :Ce crystals at x>2. • Significant improvement of the scintillation properties of Y 3 Al 5−x Ga x O 12 :Ce crystals at x=2 and 3 in comparison with YAG:Ce

  4. Incommensurate and commensurate magnetic structures of the ternary germanide CeNiGe3

    International Nuclear Information System (INIS)

    Durivault, L; Bouree, F; Chevalier, B; Andre, G; Weill, F; Etourneau, J; Martinez-Samper, P; Rodrigo, J G; Suderow, H; Vieira, S

    2003-01-01

    The structural properties of CeNiGe 3 have been investigated via electron diffraction and neutron powder diffraction (NPD). This ternary germanide crystallizes in the orthorhombic SmNiGe 3 -type structure (Cmmm space group). Electrical resistivity, ac- and dc-magnetization measurements show that CeNiGe 3 orders antiferromagnetically below T N = 5.5(2) K and exclude the occurrence at low temperatures of a spin-glass state for CeNiGe 3 as previously reported. Specific heat measurements and NPD both reveal two magnetic transitions, observed at T N1 = 5.9(2) K and T N2 = 5.0(2) K. Between T N1 and T N2 , the Ce magnetic moments in CeNiGe 3 are ordered in a collinear antiferromagnetic structure associated with the k 1 = (100) wavevector and showing a relationship with the magnetic structure of the Ce 3 Ni 2 Ge 7 ternary germanide. Below T N2 , this k 1 = (100) commensurate magnetic structure coexists with an incommensurate helicoidal magnetic structure associated with k 2 = (00.409(1)1/2). This last magnetic structure is highly preponderant below T N2 (93(5)% in volume). At 1.5 K, the Ce atoms in CeNiGe 3 carry a reduced ordered magnetic moment (0.8(2) μ B ). This value, smaller than that obtained in Ce 3 Ni 2 Ge 7 , results from an important hybridization of the 4f(Ce) orbitals with those of the Ni and Ge ligands

  5. Facile synthesis of ferromagnetic Ni doped CeO{sub 2} nanoparticles with enhanced anticancer activity

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, Fazal; Jan, Tariq [Laboratory of Nanoscience and Technology, Department of Physics, International Islamic University Islamabad (Pakistan); Iqbal, Javed, E-mail: javed.saggu@iiu.edu.pk [Laboratory of Nanoscience and Technology, Department of Physics, International Islamic University Islamabad (Pakistan); Ahmad, Ishaq [Experimental Physics Labs, National Center for Physics, Islamabad (Pakistan); Naqvi, M. Sajjad H. [Department of Biochemistry, University of Karachi, Karachi (Pakistan); Malik, Maaza [UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa)

    2015-12-01

    Highlights: • The synthesized undoped and Ni doped CeO{sub 2} nanoparticles exhibited RTFM. • Oxygen vacancies and magnetic ions both were believed to be responsible for RTFM. • The prepared nanoparticles exhibited selective cytotoxicity. • Ni doping enhanced the anticancer activity of CeO{sub 2} nanoparticles. • Differential ROS generation was observed to control their cytotoxicity. - Abstract: Ni{sub x}Ce{sub 1−x}O{sub 2} (where x = 0, 0.01, 0.03, 0.05 and 0.07) nanoparticles were synthesized by soft chemical method and were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman, UV–vis absorption spectroscopy and vibrating sample magnetometer (VSM). XRD and Raman results indicated the formation of single phase cubic fluorite structure for the synthesized nanoparticles. Ni dopant induced excessive structural changes such as decrease in crystallite size as well as lattice constants and enhancement in oxygen vacancies in CeO{sub 2} crystal structure. These structural variations significantly influenced the optical and magnetic properties of CeO{sub 2} nanoparticles. The synthesized Ni{sub x}Ce{sub 1−x}O{sub 2} nanoparticles exhibited room temperature ferromagnetic behavior. Ni doping induced effects on the cytotoxicity of CeO{sub 2} nanoparticles were examined against HEK-293 healthy cell line and SH-SY5Y neuroblastoma cancer cell line. The prepared Ni{sub x}Ce{sub 1−x}O{sub 2} nanoparticles demonstrated differential cytotoxicity. Furthermore, anticancer activity of CeO{sub 2} nanoparticles observed to be significantly enhanced with Ni doping which was found to be strongly correlated with the level of reactive oxygen species (ROS) production. The prepared ferromagnetic Ni{sub x}Ce{sub 1−x}O{sub 2} nanoparticles with differential cytotoxic nature may be potential for future targeted cancer therapy.

  6. Electronic structure and magnetism in the layered triangular lattice compound CeAuAl4Ge2

    Science.gov (United States)

    Zhang, S.; Aryal, N.; Huang, K.; Chen, K.-W.; Lai, Y.; Graf, D.; Besara, T.; Siegrist, T.; Manousakis, E.; Baumbach, R. E.

    2017-09-01

    Results are reported for the f -electron intermetallic CeAuAl4Ge2 , where the atomic arrangement of the cerium ions creates the conditions for possible geometric frustration. The magnetic susceptibility follows a Curie-Weiss temperature dependence at elevated temperatures, revealing that the cerium ions are trivalent. At lower temperatures the crystal electric field splits the Hund's rule multiplet, resulting in a weak low-temperature magnetic exchange interaction and ordering near TM≈1.4 K . This occurs within a metallic Kondo lattice, where electrical resistivity and heat capacity measurements show that the Kondo-driven electronic correlations are negligible. Quantum oscillations are detected in ac-magnetic susceptibility measurements and uncover small charge carrier effective masses. Electronic structure calculations reveal that inclusion of an on-f -site Coulomb repulsion (Hubbard) U results in antiferromagnetic order and causes the f -electron bands to move away from the Fermi level, resulting in electronic behavior that is dominated by the s ,p , and d bands, which are all characterized by light electron masses. Thus, CeAuAl4Ge2 may provide a starting point for investigating geometric magnetic frustration in a cerium lattice without strong Kondo hybridization, where calculations provide useful guidance.

  7. The effect of Ce ion substituted OMS-2 nanostructure in catalytic activity for benzene oxidation

    Science.gov (United States)

    Hou, Jingtao; Li, Yuanzhi; Mao, Mingyang; Zhao, Xiujian; Yue, Yuanzheng

    2014-11-01

    The nanostructure of Ce doped OMS-2 plays a very important role in its catalytic property. We demonstrate by density functional theory (DFT) calculations that the unique nanostructure of the Ce ion substituted OMS-2 with Mn vacancy in the framework is beneficial for the improvement of catalytic activity, while the nanostructure of the Ce ion substituted OMS-2 without defects are detrimental to the catalytic activity. We establish a novel and facile strategy of synthesizing these unique Ce ion substituted OMS-2 nanostructure with Mn vacancies in the framework by hydrothermal redox reaction between Ce(NO3)3 and KMnO4 with KMnO4/Ce(NO3)3 at a molar ratio of 3 : 1 at 120 °C. Compared to pure OMS-2, the produced catalyst of Ce ion substituted OMS-2 ultrathin nanorods exhibits an enormous enhancement in the catalytic activity for benzene oxidation, which is evidenced by a significant decrease (ΔT50 = 100 °C, ΔT90 = 129 °C) in the reaction temperature of T50 and T90 (corresponding to the benzene conversion = 50% and 90%), which is considerably more efficient than the expensive supported noble metal catalyst (Pt/Al2O3). We combine both theoretical and experimental evidence to provide a new physical insight into the significant effect due to the defects induced by the Ce ion substitution on the catalytic activity of OMS-2. The formation of unique Ce ion substituted OMS-2 nanostructure with Mn vacancies in the framework leads to a significant enhancement of the lattice oxygen activity, thus tremendously increasing the catalytic activity.The nanostructure of Ce doped OMS-2 plays a very important role in its catalytic property. We demonstrate by density functional theory (DFT) calculations that the unique nanostructure of the Ce ion substituted OMS-2 with Mn vacancy in the framework is beneficial for the improvement of catalytic activity, while the nanostructure of the Ce ion substituted OMS-2 without defects are detrimental to the catalytic activity. We establish a novel

  8. Native American depopulation, reforestation, and fire regimes in the Southwest United States, 1492–1900 CE

    Science.gov (United States)

    Liebmann, Matthew J.; Farella, Joshua; Roos, Christopher I.; Stack, Adam; Martini, Sarah

    2016-01-01

    Native American populations declined between 1492 and 1900 CE, instigated by the European colonization of the Americas. However, the magnitude, tempo, and ecological effects of this depopulation remain the source of enduring debates. Recently, scholars have linked indigenous demographic decline, Neotropical reforestation, and shifting fire regimes to global changes in climate, atmosphere, and the Early Anthropocene hypothesis. In light of these studies, we assess these processes in conifer-dominated forests of the Southwest United States. We compare light detection and ranging data, archaeology, dendrochronology, and historical records from the Jemez Province of New Mexico to quantify population losses, establish dates of depopulation events, and determine the extent and timing of forest regrowth and fire regimes between 1492 and 1900. We present a new formula for the estimation of Pueblo population based on architectural remains and apply this formula to 18 archaeological sites in the Jemez Province. A dendrochronological study of remnant wood establishes dates of terminal occupation at these sites. By combining our results with historical records, we report a model of pre- and post-Columbian population dynamics in the Jemez Province. Our results indicate that the indigenous population of the Jemez Province declined by 87% following European colonization but that this reduction occurred nearly a century after initial contact. Depopulation also triggered an increase in the frequency of extensive surface fires between 1640 and 1900. Ultimately, this study illustrates the quality of integrated archaeological and paleoecological data needed to assess the links between Native American population decline and ecological change after European contact. PMID:26811459

  9. Aqueous and Surface Chemistries of Photocatalytic Fe-Doped CeO2 Nanoparticles

    Directory of Open Access Journals (Sweden)

    Duangdao Channei

    2017-01-01

    Full Text Available The present work describes the effects of water on Fe-doped nanoparticulate CeO2, produced by flame spray pyrolysis, which is a critical environmental issue because CeO2 is not stable in typical atmospheric conditions. It is hygroscopic and absorbs ~29 wt % water in the bulk when exposed to water vapor but, more importantly, it forms a hydrated and passivating surface layer when immersed in liquid water. In the latter case, CeO2 initially undergoes direct and/or reductive dissolution, followed by the establishment of a passivating layer calculated to consist of ~69 mol % solid CeO2·2H2O and ~30 mol % gelled Ce(OH4. Under static flow conditions, a saturated boundary layer also forms but, under turbulent flow conditions, this is removed. While the passivating hydrated surface layer, which is coherent probably owing to the continuous Ce(OH4 gel, would be expected to eliminate the photoactivity, this does not occur. This apparent anomaly is explained by the calculation of (a the thermodynamic stability diagrams for Ce and Fe; (b the speciation diagrams for the Ce4+-H2O, Ce3+-H2O, Fe3+-H2O, and Fe2+-H2O systems; and (c the Pourbaix diagrams for the Ce-H2O and Fe-H2O systems. Furthermore, consideration of the probable effects of the localized chemical and redox equilibria owing to the establishment of a very low pH (<0 at the liquid-solid interface also is important to the interpretation of the phenomena. These factors highlight the critical importance of the establishment of the passivating surface layer and its role in photocatalysis. A model for the mechanism of photocatalysis by the CeO2 component of the hydrated phase CeO2·2H2O is proposed, explaining the observation of the retention of photocatalysis following the apparent alteration of the surface of CeO2 upon hydration. The model involves the generation of charge carriers at the outer surface of the hydrated surface layer, followed by the formation of radicals, which decompose organic

  10. DOTA-functionalized polylysine: a high number of DOTA chelates positively influences the biodistribution of enzymatic conjugated anti-tumor antibody chCE7agl.

    Directory of Open Access Journals (Sweden)

    Jürgen Grünberg

    Full Text Available Site-specific enzymatic reactions with microbial transglutaminase (mTGase lead to a homogenous species of immunoconjugates with a defined ligand/antibody ratio. In the present study, we have investigated the influence of different numbers of 1,4,7,10-tetraazacyclododecane-N-N'-N''-N'''-tetraacetic acid (DOTA chelats coupled to a decalysine backbone on the in vivo behavior of the chimeric monoclonal anti-L1CAM antibody chCE7agl. The enzymatic conjugation of (DOTA1-decalysine, (DOTA3-decalysine or (DOTA5-decalysine to the antibody heavy chain (via Gln295/297 gave rise to immunoconjugates containing two, six or ten DOTA moieties respectively. Radiolabeling of the immunoconjugates with (177Lu yielded specific activities of approximately 70 MBq/mg, 400 MBq/mg and 700 MBq/mg with increasing numbers of DOTA chelates. Biodistribution experiments in SKOV3ip human ovarian cancer cell xenografts demonstrated a high and specific accumulation of radioactivity at the tumor site for all antibody derivatives with a maximal tumor accumulation of 43.6±4.3% ID/g at 24 h for chCE7agl-[(DOTA-decalysine]2, 30.6±12.0% ID/g at 24 h for chCE7agl-[(DOTA3-decalysine]2 and 49.9±3.1% ID/g at 48 h for chCE7agl-[(DOTA5-decalysine]2. The rapid elimination from the blood of chCE7agl-[(DOTA-decalysine]2 (1.0±0.1% ID/g at 24 h is associated with a high liver accumulation (23.2±4.6% ID/g at 24 h. This behavior changed depending on the numbers of DOTA moieties coupled to the decalysine peptide with a slower blood clearance (5.1±1.0 (DOTA3 versus 11.7±1.4% ID/g (DOTA5, p<0.005 at 24 h and lower radioactivity levels in the liver (21.4±3.4 (DOTA3 versus 5.8±0.7 (DOTA5, p<0.005 at 24 h. We conclude that the site-specific and stoichiometric uniform conjugation of the highly DOTA-substituted decalysine ((DOTA5-decalysine to an anti-tumor antibody leads to the formation of immunoconjugates with high specific activity and excellent in vivo behavior and is a valuable option for

  11. ExoDat Information System at CeSAM

    Science.gov (United States)

    Agneray, F.; Moreau, C.; Chabaud, P.; Damiani, C.; Deleuil, M.

    2014-05-01

    CoRoT (Convection Rotation and planetary transits) is a space based mission led by French space agency (CNES) in association with French and international laboratories. One of CoRoT's goal is to detect exoplanets by the transit method. The Exoplanet Database (Exodat) is a VO compliant information system for the CoRoT exoplanet program. The main functions of ExoDat are to provide a source catalog for the observation fields and targets selection; to characterize the CoRoT targets (spectral type, variability , contamination...);and to support follow up programs. ExoDat is built using the AstroNomical Information System (ANIS) developed by the CeSAM (Centre de donneeS Astrophysique de Marseille). It offers download of observation catalogs and additional services like: search, extract and display data by using a combination of criteria, object list, and cone-search interfaces. Web services have been developed to provide easy access for user's softwares and pipelines.

  12. Superconductivity without inversion symmetry in CePt3Si

    International Nuclear Information System (INIS)

    Frigeri, P.A.; Agterberg, D.F.; Koga, A.; Sigrist, M.

    2005-01-01

    Based on symmetry arguments by Anderson, the following conditions are necessary for the formation of Cooper pairs: spin-singlet pairing relies on time-reversal symmetry, while spin-triplet pairing requires parity in addition. The rather general formulation of this rule has led to the common belief that the lack of an inversion center in a material would prevent spin-triplet pairing indiscriminately. In this presentation, we discuss symmetry aspects of superconductivity in a class of systems without inversion symmetry which is connected with spin-orbit coupling. We can show that, not only spin singlet pairing, but also certain spin triplet states remain unaffected by the loss of inversion symmetry. Moreover, the absence of an inversion center reduces the effect of paramagnetic limiting for spin-singlet pairing states in an external magnetic field. Based on this symmetry analysis, we examine the recently discovered heavy Fermion superconductor CePt 3 Si, where a missing inversion plane leads to the well-known Rashba-type of spin-orbit coupling. In particular, the problem of the pairing symmetry will be addressed as well as several properties of the superconducting phase which appears close to a quantum phase transition between a paramagnetic and antiferromagnetic phase. The same kind of analysis will also be done for another example UIr

  13. Microchips for CE: breakthroughs in real-world food analysis.

    Science.gov (United States)

    Escarpa, Alberto; González, María Cristina; López Gil, Miguel Angel; Crevillén, Agustín G; Hervás, Miriam; García, Miguel

    2008-12-01

    The well-known complexity of food matrices is approached using CE microchips with different strategies to improve the selectivity and sensitivity of the analysis by avoiding and/or making the sample preparation as simple as possible: (i) enhancing the peak capacity in order to perform direct injection, (ii) using the microchip platform to measure one target analyte/group of analytes with or without separating other related interferences, (iii) integrating sample preparation steps on the microchip platform, and (iv) integrating new analytical tools from nanotechnology in the detection stage. New analyte separations of food significance involving DNA probes, biogenic amines, vanilla flavors, and dyes have been reported as successfully breaking new barriers in areas of high impact in the market, such as transgenic food analysis, as well as the detection of frauds and toxins. Simple microchip layouts are still the most common designs used, though sophisticated new ones are emerging. In contrast to other application areas, electrochemical detection continues to be the most common detection route, followed by LIF, though non-conventional detection routes are also emerging, such as chemiluminescence or UV. In terms of analytical performance, the integration of calibration and quality control on a microchip platform, and remarkable accuracy and precision are being obtained using creative analytical methodologies that enhance the analytical potency of microfluidic chips for their future commercialization. This review critically states the most important advances derived from work done in the field over the past 2-3 years.

  14. Breastfeeding practices in the city of Iguatu-CE

    Directory of Open Access Journals (Sweden)

    Lúcia Vanda Teixeira de Freitas Cavalcante

    2012-12-01

    Full Text Available Objective: To assess breastfeeding practices in Family Health Strategy. Methods: A descriptive cross-sectional quantitative study conducted in Family Health Units of the urban area of Iguatu-CE, Brazil, from August 2008 to May 2009. Participants were 402 mothers with children under six months of age who underwent prenatal consultations. We used a form with questions regarding breastfeeding, breastfeeding difficulties, introducing other foods, infant nutrition, consultations prenatal and postpartum visits undertaken by staff. The data were entered into SPSS 16.0 and analyzed descriptively. Results: Among the mothers interviewed (402, most said that was breastfeeding babies (N = 343, 85.3%, but introduced other food (N = 252, 62.6%, verifying low prevalence of exclusive breastfeeding. Of the 252 women who reported offering other food to baby, 158 (62.7% offered on their own, followed by those who chose to follow the indication of relatives and neighbors (N = 63, 25%. Conclusions: The study revealed that mothers of the Family Health Units from Iguatu-EC did not breastfeed their children exclusively, but with the introduction of other foods (other milk, porridge, thereby demonstrating the low prevalence of exclusive breastfeeding.

  15. Development of microcolumnar LaBr3:Ce scintillator

    Science.gov (United States)

    Nagarkar, Vivek V.; Miller, Stuart; Singh, Bipin; Thacker, Samta; Gaysinskiy, Valeriy; Miller, Brian W.; Barber, H. Bradford; Wilson, Donald

    2009-08-01

    While a wide variety of new scintillators are now available, new cerium-doped lanthanide halide scintillators have shown a strong potential to move beyond their familiar role in conventional gamma ray spectroscopy, toward fulfilling the needs of highly demanding applications such as radioisotope identification at room temperature, homeland security, and quantitative molecular imaging for medical diagnostics, staging and research. Despite their extraordinary advantages, however, issues related to reliable, large volume manufacturing of these high light yield materials in a rapid and economic manner have not been resolved or purposefully addressed. Also, if microcolumnar films of this material could be fabricated, it would find widespread use in a multitude of high-speed imaging/nuclear medicine applications. Here we report on synthesizing LaBr3:Ce scintillators using a thermal evaporation technique, which permits the fabrication of high spatial resolution microcolumnar films and holds a potential to synthesize large volumes of high quality material in a time efficient and cost effective manner. Performance evaluation of the fabricated films and their application for SPECT imaging are also discussed.

  16. Utilisation du site Web | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Ce site Web fournit des espaces de discussion et donne accès à divers mécanismes de communication. L'utilisateur s'engage à en faire un usage approprié et pertinent à l'objet des discussions. Il s'engage en outre à ne diffuser aucun message diffamatoire, illégal, obscène ou menaçant et à ne pas télécharger ou joindre ...

  17. Studies on Ca2+-Doped CeBr3 Scintillating Materials

    Energy Technology Data Exchange (ETDEWEB)

    Guss, P. [NSTec; Foster, M. E. [SNL; Wong, B. M. [SNL; Doty, F. P. [SNL; Shah, K. [RMD; Squillante, M. [RMD; Glodo, J. [RMD; Yuan, D. [NSTec

    2013-07-03

    Despite the outstanding scintillation performance characteristics of cerium tribromide (CeBr3) and cerium-activated lanthanum tribromide (LaBr3:Ce), their commercial availability and application is limited due to the difficulties of growing large, crack-free single crystals from these fragile materials. The objective of this investigation was to employ aliovalent doping to increase crystal strength while maintaining the optical properties of the crystal. One divalent dopant (Ca2+) was investigated as a dopant to strengthen CeBr3 without negatively impacting scintillation performance. Ingots containing nominal concentrations of 1.9% of the Ca2+ dopant were grown. Preliminary scintillation measurements are presented for this aliovalently doped scintillator. Ca2+-doped CeBr3 exhibited little or no change in the peak fluorescence emission for 371 nm optical excitation for CeBr3. The structural, electronic, and optical properties of CeBr3 crystals were investigated using the density functional theory within generalized gradient approximation. The calculated lattice parameters are in good agreement with the experimental data. The energy band structures and density of states were obtained. The optical properties of CeBr3, including the dielectric function, were calculated.

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

    Energy Technology Data Exchange (ETDEWEB)

    T Chen; D Mullins

    2011-12-31

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

  19. Development of accident tolerant FeCrAl-ODS steels utilizing Ce-oxide particles dispersion

    Science.gov (United States)

    Shibata, Hiroki; Ukai, Shigeharu; Oono, Naoko H.; Sakamoto, Kan; Hirai, Mutsumi

    2018-04-01

    FeCrAl-ODS ferritic steels with Ce-oxide dispersion instead of Y-oxide were produced for the accident tolerant fuel cladding of the light water reactor. Excess oxygen (Ex.O) was added to improve the mechanical property. The tensile strength at Ex.O = 0 is around 200 MPa at 700 °C, mainly owing to dispersed Ce2O3 particles in less than 10 nm size. The formation of the fine Ce2O3 particles is dominated by a coherent interface with ferritic matrix. With increasing Ex.O, an increased of number density of coarser Ce-Al type oxide particles over 10 nm size is responsible for the improvement of the tensile strength. Change of the type of oxide particle, CeO2, Ce2O3, CeAlO3, Al2O3, in FeCrAl-ODS steel was thermodynamically analyzed as a parameter of Ex.O.

  20. Bio diesel synthesis from pongamia pinnata oil over modified CeO2 catalysts

    International Nuclear Information System (INIS)

    Venkatesh; Sathgatta Z, M. S.; Manjunatha, S.; Thammannigowda V, V.

    2014-01-01

    This study investigates the use of CeO 2 , ZrO 2 , Mg O and CeO 2 -ZrO 2 , CeO 2 -Mg O, CeO 2 -ZrO 2 -Mg O mixed oxides as solid base catalysts for the transesterification of Pongamia pinnata oil with methanol to produce bio diesel. SO 4 2- /CeO 2 and SO 4 2- /CeO 2 -ZrO 2 were also prepared and used as solid acid catalysts for esterification of Pongamia pinnata oil (P-oil) to reduce the % of free fatty acid (FFA) in P-oil. The oxide catalysts were prepared by an incipient wetness impregnation method and characterized by techniques such as NH 3 -Tpd for surface acidity, CO 2 -Tpd for surface basicity and powder X-ray diffraction for crystallinity. The effect of nature of the catalyst, methanol to P-oil molar ratio and reaction time in esterification as well as in transesterification was investigated. The catalytic materials were reactive d and reused for five reaction cycles and the results showed that the ceria based catalysts have reasonably good reusability both in esterification and transesterification reaction. The test results also revealed that the CeO 2 -ZrO 2 modified with Mg O could have potential for use in the large scale bio diesel production. (Author)

  1. Effects of Surfactants on the Performance of CeO2 Humidity Sensor

    Directory of Open Access Journals (Sweden)

    Chunjie Wang

    2014-01-01

    Full Text Available Nanosized CeO2 powders were synthesized via hydrothermal method with different types of surfactants (polyethylene glycol (PEG, cetyltrimethylammonium bromide (CTAB, and sodium dodecylbenzenesulfonate (SDBS. X-ray diffraction, Raman spectroscopy, and transmission electron microscopy were utilized to characterize the phase structures and morphologies of the products. The sample with CTAB as surfactant (CeO2-C has the largest specific surface area and the smallest particle size among these three samples. The humidity sensor fabricated by CeO2-C shows higher performance than those used CeO2-P and CeO2-S. The impedance of the CeO2-C sensor decreases by about five orders of magnitude with relative humidity (RH changing from 15.7 to 95%. The response and recovery time are 7 and 7 s, respectively. These results indicate that the performance of CeO2 humidity sensors can be improved effectively by the addition of cationic surfactant.

  2. Enhanced multiferroic properties in La and Ce co-doped BiFeO3 nanoparticles

    Science.gov (United States)

    Priyadharsini, P.; Pradeep, A.; Sathyamoorthy, B.; Chandrasekaran, G.

    2014-07-01

    Room temperature multiferroic properties of BiFeO3 (BFO), Bi0.9La0.1FeO3 ((La)BFO) and Bi0.9La0.075Ce0.025FeO3 ((La,Ce)BFO) nanoparticles have been reported in this paper. XRD (X-ray diffraction) analyses of the nanoparticles show a decrease in the lattice constants and cell volume with the substitution of La and Ce. It is evident from the SEM (scanning electron microscope) micrographs that the (La,Ce) co-doped sample possesses dense microstructure made of smaller particles. Raman study accounts for the weakening of the strong hybridization between Bi-O by the substitution of La and Ce ions. This is also accompanied by an increase in the remanent magnetization, dielectric constant, and ferroelectric polarization. BFO nanoparticles show exchange bias effect under an applied magnetic field while the (La)BFO and (La,Ce)BFO samples show no trace of such effect. Ac-conductivity of (La,Ce) co-doped sample is observed to be several orders lesser in magnitude than bulk BFO ceramics. These results are interpreted by means of the subtle change in the structure, suppression of the spin cycloid and reduction of oxygen vacancies in the doped samples.

  3. Effect of Ce ions on MOX codeposition in oxide-electrowinning reprocessing

    Science.gov (United States)

    Sato, F.; Fukushima, M.; Myochin, M.; Namba, T.; Kormilitsyn, M. V.; Ishunin, V. S.; Bychkov, A. V.; Inagaki, T.

    2005-02-01

    An experiment of MOX codeposition from U Pu Ce containing molten salt in oxide -electrowinning reprocessing was performed. Composition of O2/Cl2/Ar mixed gas, Ce concentration and U/Pu concentration in the salt were chosen as variable parameters. Ten tests were performed in this experiment. Current efficiency in each test was about 60 99%, and apparent dependence of the current efficiency on concentration of Ce in the salt was not seen in this experiment. Recovered MOX deposits contained about 5 19 wt% of Pu and 0.5 2 wt% of Ce. Concentration of Pu and Ce in the MOX deposit was influenced by O2/Cl2/Ar mixed gas composition and Ce concentration in the salt, respectively. Microphotographs of cross-section show that the MOX deposit was a complex of small columnar crystals. Some parts of the cross-section were analyzed by EPMA. These results indicated that a U rich region (concentration of U: about 80 wt%) exists in central part of the crystal and Pu rich regions (concentration of Pu: about 80 wt%) scatter on its surface and Ce is distributed rather uniformly.

  4. Design of high quality doped CeO2 solid electrolytes with nanohetero structure

    International Nuclear Information System (INIS)

    Mori, T.; Ou, D.R.; Ye, F.; Drennan, J.

    2006-01-01

    Doped cerium (CeO 2 ) compounds are fluorite related oxides which show oxide ionic conductivity higher than yttria-stabilized zirconia in oxidizing atmosphere. As a consequence of this, a considerable interest has been shown in application of these materials for low (400-650 o C) temperature operation of solid oxide fuel cells (SOFCs). In this paper, our experimental data about the influence of microstructure at the atomic level on electrochemical properties were reviewed in order to develop high quality doped CeO 2 electrolytes in fuel cell applications. Using this data in the present paper, our original idea for a design of nanodomain structure in doped CeO 2 electrolytes was suggested. The nanosized powders and dense sintered bodies of M doped CeO 2 (M:Sm,Gd,La,Y,Yb, and Dy) compounds were fabricated. Also nanostructural features in these specimens were introduced for conclusion of relationship between electrolytic properties and domain structure in doped CeO 2 . It is essential that the electrolytic properties in doped CeO 2 solid electrolytes reflect in changes of microstructure even down to the atomic scale. Accordingly, a combined approach of nanostructure fabrication, electrical measurement and structure characterization was required to develop superior quality doped CeO 2 electrolytes in the fuel cells. (author)

  5. Surface electrochemistry of CO2 reduction and CO oxidation on Sm-doped CeO(2-x): coupling between Ce(3+) and carbonate adsorbates.

    Science.gov (United States)

    Feng, Zhuoluo A; Machala, Michael L; Chueh, William C

    2015-05-14

    The efficient electro-reduction of CO2 to chemical fuels and the electro-oxidation of hydrocarbons for generating electricity are critical toward a carbon-neutral energy cycle. The simplest reactions involving carbon species in solid-oxide fuel cells and electrolyzer cells are CO oxidation and CO2 reduction, respectively. In catalyzing these reactions, doped ceria exhibits a mixed valence of Ce(3+) and Ce(4+), and has been employed as a highly active and coking-resistant electrode. Here we report an operando investigation of the surface reaction mechanism on a ceria-based electrochemical cell using ambient pressure X-ray photoelectron spectroscopy. We show that the reaction proceeds via a stable carbonate intermediate, the coverage of which is coupled to the surface Ce(3+) concentration. Under CO oxidation polarization, both the carbonate and surface Ce(3+) concentration decrease with overpotential. Under CO2 reduction polarization, on the other hand, the carbonate coverage saturates whereas the surface Ce(3+) concentration increases with overpotential. The evolution of these reaction intermediates was analyzed using a simplified two-electron reaction scheme. We propose that the strong adsorbate-adsorbate interaction explains the coverage-dependent reaction mechanism. These new insights into the surface electrochemistry of ceria shed light on the optimization strategies for better fuel cell electrocatalysts.

  6. Static magnetic ordering of CeCu2.1Si2 found by muon spin relaxation

    Science.gov (United States)

    Uemura, Y. J.; Kossler, W. J.; Yu, X. H.; Schone, H. E.; Kempton, J. R.; Stronach, C. E.; Barth, S.; Gygax, F. N.; Hitti, B.; Schenck, A.

    1988-01-01

    Zero- and longitudinal-field muon spin relaxation measurements on a polycrystal sample of a heavy fermion superconductor CeCu2.1 Si2 (T(c) = 0.7 K) have revealed an onset of static magnetic ordering below T approximately 0.8 K. The line shapes of the observed spectra in zero field indicate a wide distribution of static random local fields at muon sites, suggesting that the ordering is either spin glass or incommensurate spin-density-wave state. The observed width of the random local field at T = 0.05 K corresponds to a small averaged static moment of the order of 0.1 micro-B per formula unit.

  7. Synthesis and characterization of charge-substituted garnets YCaLnGa5O12 (Ln = Ce,Pr,Tb)

    International Nuclear Information System (INIS)

    Gramsch, S.A.

    1993-01-01

    A low temperature method is described for the preparation of the new garnet compounds YCaLnGa 5 O l2 (Ln=Ce, Pr, Th). In this set of compounds (Ca 2+ + Ln 4+ ) replaces 2 Y 3+ in the parent gallium based garnet Y 3 Ga 5 O l2 in order to stabilize as effectively as possible the Ln 4+ species in the eight-coordinate ''A'' site of the garnet structure. Characterization of the oxides by x-ray powder diffraction and thermogravimetric analysis is discussed with regard to the structural relationship of the substituted compound to the parent material. The tetravalent ions Pr 4+ and Tb 4+ exhibit increased thermal stability in reducing conditions as compared to the Ln 4+ states in the fluorite (LnO 2 ) and perovskite (BaLnO 3 ) type structures. This result is discussed with reference to the complex crystal chemistry of these systems

  8. Crystal growth, crystal structure and physical characterization of CeMo/sub 6/S/sub 8/

    International Nuclear Information System (INIS)

    Pena, O.; Geantet, C.; Hortyn, R.; Potel, M.; Padiou, J.; Sergent, M.

    1987-01-01

    Single crystals of Ce/sub x/Mo/sub 6/S/sub 8/ were grown using two methods of crystal growth. Refinement of the crystal structure shows an upper stoichiometry of x = 1.0. The cerium atom occupies the origin site of the hexagonal-rhombohedral unit-cell, with no visible delocalization. Crystals were characterized through their susceptibility and transport properties. A.c. susceptibility shows a smooth ''shoulder'' at 2.4 K, due to a magnetic order. The resistivity of a single crystal presents a minimum at 19 K, followed by a small logarithmic increase with decreasing temperature, and a sharp decrease between 2.7 and 2.4 K. These results on single crystals are discussed in comparison with previous reports on sintered powder

  9. Enhanced catalytic properties of Pt-based electrode by doped Cu and Ce

    Science.gov (United States)

    Yue, Dehuai; Yang, Bin

    2017-08-01

    Novel PtCuCeO x composite membrane electrode materials were fabricated on the surface of graphite fibrous cloth by ion beam sputtering (IBS). The cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were used to analyze the influence of doped Cu and Ce on the membrane electrocatalysis performance in a tri-electrode system. The phase composition, surface structure, interfacial structure and catalytic performance of PtCuCeO x membrane were studied by x-ray diffraction (XRD) and high resolution transmission electron microscope (HR-TEM&STEM). The results indicate that surface particles of membrane electrode are made up of PtCu alloy grains and a few CeO x grains, and the interface structure of oxide metal is formed between them. The crystal plane spacing between PtCu alloy grain is reduced by about 1.11% after the corrosion, which helps increase the electron density on Pt atom. As a result, the catalysis capability of PtCu alloy is enhanced. When the content of Ce is less than or equal to 0.28 wt.%, CeO x exists in the form of amorphous. It is exciting to demonstrate that the existence of CeO x enhances the dispersion of PtCuCeO x catalyst particles. The experimental results reveal that the synthesized material possesses the best electrochemical activity surface area (ESA) and exchange current density (i 0). Compared to pure Pt catalyst, this PtCuCeO x catalyst contains much less Pt content (only 42% of Pt catalyst). However, the electrochemical performance is enhanced by 71.8% compared with pure Pt.

  10. A DFT study of phenol adsorption on a low doping Mn–Ce composite oxide model

    Energy Technology Data Exchange (ETDEWEB)

    D́Alessandro, Oriana [CINDECA – Fac. Cs. Ex. UNLP, CCT – CONICET, Calle 47 Nro. 257, (1900) La Plata (Argentina); Pintos, Delfina García [ITHES–UBA, Pabellón de Industrias, (1428) Buenos Aires (Argentina); Juan, Alfredo, E-mail: cajuan@uns.edu.ar [Departamento de Física & IFISUR – UNS, Avda. Alem 1253, (8000) Bahía Blanca (Argentina); Irigoyen, Beatriz [ITHES–UBA, Pabellón de Industrias, (1428) Buenos Aires (Argentina); Sambeth, Jorge [CINDECA – Fac. Cs. Ex. UNLP, CCT – CONICET, Calle 47 Nro. 257, (1900) La Plata (Argentina)

    2015-12-30

    Graphical abstract: - Highlights: • Phenol is adsorbed on the structural-oxygen-deficient Ce-Mn-O(1 1 1) surface interacting with the Ce cation first neighbor to Mn dopant. • The O–H of the phenol group bond is stretched up to 1.69 Å. • Phenol interaction with the hydroxylated H–OH/Ce{sub 0.875}Mn{sub 0.125}O{sub 1.9375}(1 1 1) surface is 0.51 eV stronger than on the clean surface. • The C{sub 6}H{sub 5}–O fraction is adsorbed in a bridge position between Mn and Ce cations with a tilt angle of 69.62° in agreement with IR data. - Abstract: Density functional theory calculations (DFT + U) were performed on a low doping Mn–Ce composite oxide prepared from experimental data, including X-ray diffraction (XRD) and temperature-programmed reduction (TPR). We considered a 12.5% Mn-doped CeO{sub 2} solid solution with fluorite-type structure, where Mn replaces Ce{sup 4+} leading to an oxygen-deficient bulk structure. Then, we modeled the adsorption of phenol on the bare Ce{sub 0.875}Mn{sub 0.125}O{sub 1.9375}(1 1 1) surface. We also studied the effect of water adsorption and dissociation on phenol adsorption on this surface, and compared the predictions of DFT + U calculations with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements. The experimental results allowed us to both build a realistic model of the low doping Mn–Ce composite oxide and support the prediction that phenol is adsorbed as a phenoxy group with a tilt angle of about 70° with respect to the surface.

  11. Study of the defect structure of ''pure'' and doped nonstoichiometric CeO2

    International Nuclear Information System (INIS)

    Blumenthal, R.N.

    1975-09-01

    Electrical conductivity and thermogravimetric measurements were made on Ta 2 O 5 -doped nonstoichiometric CeO 2 (i.e. Ce/sub 1-y/Ta/sub y/O/sub 2-x/ ) as a function of temperature and oxygen partial pressure. Over a limited range of temperature and nonstoichiometry, the isothermal dependence of the electrical conductivity on nonstoichiometry may be described by the equation sigma = A + Bx, where A is the electronic conductivity associated with the electronic defects produced by doping CeO 2 with Ta 2 O 5 . The electronic conductivity resulting from the nonstoichiometric defect reaction O/sup x/ + 2Ce/sub Ce//sup x/ = V 0 + 2Ce'sub Ce/ + 1 / 2 O 2 (g) is equal to Bx. The ionic conductivity may be described by the relation sigma/sub i/ = B[y+x]eμ'/sub V 0 / exp (--E/sub i//kT), and the electronic conductivity by the isothermal expressions sigma/sub e/ proportional to P/sub O 2 //sup -1/4/ and sigma/sub e/ proportional to x; x less than 3 x 10 -2 . These results are consistent with defect models involving doubly ionized oxygen vacancies. An empirical expression (i.e. Δ anti H/sub O 2 / proportional to y/2 or z/4) was obtained relating the dependence of Δ anti H/sub O 2 / on the dopant concentration of lower valent foreign cations (e.g. y/2 for Ce/sub 1-y/M/sub y/O/sub 2-y-x/ and z/4 for Ce/sub 1-z/M/sub z/O/sub 2-z/2-x/ where M = Ca, Sr and M' = Y, La). (auth)

  12. Transport, thermal, and magnetic properties in heavy-fermion superconductor Ce2CoIn8

    International Nuclear Information System (INIS)

    Yamashita, Tetsuro; Ohara, Shigeo; Sakamoto, Isao

    2011-01-01

    We have grown high purity single crystals of Ce 2 CoIn 8 . We investigated its transport, thermal, and magnetic properties. Ce 2 CoIn 8 has a superconducting ground state with a distinct non-Fermi liquid character. We propose one of the CEF level schemes of Ce 2 CoIn 8 . We have grown high purity single crystals of Ce 2 CoIn 8 using the self-flux technique, and have investigated its transport, thermal, and magnetic properties, including the anisotropic features. Single crystals of Ce 2 CoIn 8 were grown in the lower temperature region to avoid the formation of un-wanted phases such as CeCoIn 5 and CeIn 3 impurities. The results of the structural and physical measurements imply that the present single crystals have high purity. The electrical resistivity and specific heat measurements demonstrate that Ce 2 CoIn 8 has a superconducting ground state with a distinct non-Fermi liquid character. This indicates that the superconductivity in Ce 2 CoIn 8 arises out of the verge of the underlying quantum critical instability mediated by the antiferromagnetic correlations. Additionally, we investigate the crystalline electric field (CEF) energy scheme based on the temperature dependence of the specific heat and the anisotropic features in the susceptibility. We propose one of the CEF level schemes calculated on the basis of the CEF model that the first and second CEF states are located at Δ 1 = 82 K and Δ 2 = 102 K above the ground state doublet, respectively.

  13. The effects of binding type on luminescence LED phosphor based on GGG/Ce3+

    Science.gov (United States)

    Mikhailov, M. M.; Neshchimenko, V. V.; Shavlyuk, V. V.

    2014-12-01

    Luminescence and reflectance spectra of coatings based on gadolinium gallium garnet doped by cerium (GGG/Ce3+) with silicone resin or potassium liquid glass compound were analyzed depending on concentration. It was established that the maximum emissions of the coatings at 75 wt.% compound concentration have luminescence band at 570 nm and absorption band at 470 nm. Both bands were detected by absorption or emission of cerium ions in gadolinium gallium garnet. Ce3+ ion transition into Ce4+ ion was observed upon quantum absorption, and the reverse transition was observed upon quantum emission.

  14. CeO2 based catalysts for the treatment of propylene in motorcycle's exhaust gases

    OpenAIRE

    Pham, Phuong Thi Mai; Minh, Thang Le; Nguyen, Tien The; Van Driessche, Isabel

    2014-01-01

    In this work, the catalytic activities of several single metallic oxides were studied for the treatment of propylene, a component in motorcycles? exhaust gases, under oxygen deficient conditions. Amongst them, CeO2 is one of the materials that exhibit the highest activity for the oxidation of C3H6. Therefore, several mixtures of CeO2 with other oxides (SnO2, ZrO2, Co3O4) were tested to investigate the changes in catalytic activity (both propylene conversion and CO2 selectivity). Ce0.9Zr0.1O2,...

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

    International Nuclear Information System (INIS)

    Andrade Nono, M.C. de

    1992-01-01

    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 O 2 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)

  16. Room-temperature synthesis and photoluminescence of hexagonal CePO4 nanorods

    Science.gov (United States)

    Zhu, J.; Zhang, K.; Zhao, H. Y.

    2018-01-01

    Hexagonal CePO4 nanorods were synthesized via a simple chemical precipitation route at room-temperature without the presence of surfactants and then characterized by powder X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectrometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible (UV–vis) absorption and photoluminescence (PL) spectroscopy. Hexagonal CePO4 nanorods exhibit strong ultraviolet absorption and ultraviolet luminescence, which correspond to the electronic transitions between 4f and 5d state of Ce3+ ions.

  17. Thermodynamical study of boron doped CeX{sub 3} (X=Pd, Rh)

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Ramesh [Dept. of Physics, Mewar University, Chittorgarh Rajasthan-India (India); Dwivedi, Shalini; Sharma, Yamini, E-mail: sharma.yamini62@gmail.com [Theoretical Condensed Matter Physics Laboratory, Dept. of Physics, Feroze Gandhi College, Raebareli-229001 U.P (India)

    2016-05-06

    The structural, electronic, thermal, and optical properties of cubic non magnetic CeX{sub 3}(X=Pd, Rh) compounds which crystallize in the Au{sub 3}Cu structure have been studied using the projected augmented wave (PAW) method within the density functional theory (DFT) with generalized gradient approximation (GGA) for exchange correlation potential. In this paper we have calculated the band structure which are interpreted using the density of states. The optical properties such as extinction coefficients clearly illustrate the changes in CeX{sub 3} due to intercalation of boron. Lattice instability is observed in CePd{sub 3}B from the calculated dynamical properties.

  18. Ab initio investigation of the noncollinear magnetic structure of CeFeAsO

    Science.gov (United States)

    Liu, Juan; Luo, Bo; Sun, Zhaoyu; Fu, Huahua; Yao, Kailun

    2011-09-01

    The noncollinear magnetic ground state in CeFeAsO has been investigated using the density-functional theory. When the spin-orbit coupling is discarded, the magnitude of the Ce-magnetic moment (0.87μB) is independent of the spin direction and is in accordance with the experimental value of 0.83(2)μB. However, when the spin-orbit coupling is considered, the Ce-orbital moments change with the internal magnetic field and affect the total magnetic moment of Ce. One type of Ce ions has a magnetic moment of 0.909μB, which is very close to the experimental value. The other type of Ce ions has a magnetic moment of 0.488μB, which has not been previously reported. The magnetic moments of the rare-earth metals in NdFeAsO and PrFeAsO are also twice those of experimental observations. The difference between the rare earth magnetic-moment errors of the three compounds imply that magnetism is related to the onset of the superconducting critical temperature. At the same time, the calculated Fe-magnetic moments in all solutions are over 2.0μB. From the band structure and density of states (DOS), the Ce 4f and Fe 3d orbits are shown to have major contributions to the Fermi level. Four bands in CeFeAsO cross the Fermi level at the Γ (0, 0, 0) point and form four hole-like pockets. The superexchange interaction between the Ce 4f and Fe 3d electrons via oxygen ions is discussed. Furthermore the results show that the Fermi surface shape varies with the Ce spin direction, revealing that electroconductibility is directly affected by the Ce-spin direction. If the Ce spin is perpendicular to the FeAs plane, the electronic field gradient (EFG) changes from a negative value into a positive value.

  19. RESPONSE OF SOIL MICROBIAL BIOMASS TO CeO2 NANOPARTICLES

    Directory of Open Access Journals (Sweden)

    Livia Vittori Antisari

    2011-12-01

    Full Text Available Aim of this work was to assess the impact of the chronic exposure of CeO2 nanoparticles (NPs (50 to 105 nm nominal size on soil microbial biomass.To evaluate if the CeO2 NPs can affect the soil quality, they were mixed to an A1 and A2 horizon of Epileptic Cambisols at a concentrations of 100 ppm and incubated in lab for short and medium (7 and 60 days times, at a constant temperature (25°C and moisture (60% WHC.The preliminary results of the soil physicochemical analyses have showed an insolubility of the CeO2 NPs at short-term incubation in water, EDTA and aqua regia. The biological assays detect a storing of Ce-CeO2 in the microbial biomass at short time that decreases in the C amount. An increment of the basal respiration and a decrease in the amount of carbon soil microbial biomass determined a higher metabolic quotient (qCO2 than the control test, that identifies a stressful situation, most evident in the short term condition.Physical-chemical characterization of the CeO2 NPs and of the soil before and after the NPs addition, was carried out by means of Environmental Scanning Electron Microscope (ESEM and an Energy Dispersive Spectroscopy (EDS. The investigations showed Ce-NPs and Ce-compounds in both- incubation-condition samples. The control soil showed the presence of cerium associated with other elements, like P, Nd, La, Th e Si. From literature, it appears that these elements identify Monazite-Ce/Nd minerals, whose chemical formulas are respectively (Ce, La, Nd, Th PO4 and (Nd, Ce, La (P, Si O4. The presence of CeO2 NPs was clearly detected in soil and recognized by ESEM morphological observations coupled with EDS characterization. The NPs chemical composition appears unaltered, while the size can be modified by NPs aggregation and clustering.The results contribute to setting reference baseline values of cerium in soil and indicate an impact on the amount of carbon soil microbial biomass due to a higher metabolic quotient (qCO2 that

  20. Data and analyses of phase relations in the Ce-Fe-Sb ternary system.

    Science.gov (United States)

    Zhu, Daiman; Xu, Chengliang; Li, Changrong; Guo, Cuiping; Zheng, Raowen; Du, Zhenmin; Li, Junqin

    2018-02-01

    These data and analyses support the research article "Experimental study on phase relations in the Ce-Fe-Sb ternary system" Zhu et al. (2017) [1]. The data and analyses presented here include the experimental results of XRD, SEM and EPMA for the determination of the whole liquidus projection and the isothermal section at 823 K in the Ce-Fe-Sb system. All the results enable the understanding of the constituent phases and the solidification processes of the as-cast alloys as well as the phase relations and the equilibrium regions at 823 K in the Ce-Fe-Sb ternary system over the entire composition.

  1. The exceptional behaviour of Pr, Ce and Tb in high-Tc superconductors

    International Nuclear Information System (INIS)

    Staub, U.

    1999-01-01

    X-ray absorption and diffraction, elastic and inelastic neutron scattering and magnetization measurements are used to study the electronic, structural and magnetic properties of two series of high-T c superconductors containing Ce, Tb and Pr. These results are interpreted with regard to the well known valence instabilities often shown by these rare earth ions. Ce is found to be non-magnetic, in contrast to Tb, which exhibits complex 2D magnetic properties. Although the measurements provide detailed understanding of the behaviour of Ce and Tb, there is still no consensus why Pr suppresses superconductivity in particular cuprates. (orig.)

  2. Magnetic properties of the layered oxypnictides (LnOMnAs (Ln = La, Ce, Pr, Nd

    Directory of Open Access Journals (Sweden)

    Morosawa Y.

    2014-07-01

    Full Text Available We have investigated the rare earth elements dependence on the magnetism to understand the contribution to physical properties of the 4f electrons of (LnOMnAs (Pn = La, Ce, Pr, Nd. (CeOMnAs, (PrOMnAs and (NdOMnAs shows the antiferromagnetic behaviors at low temperature. (CeOMnAs and (NdOMnAs have the magnetic anomalies around 34 K and 24 K, respectively. So, it is speculated that the anomalies depend on the Mn -Mn distance directly

  3. Tumour targeting with monovalent fragments of anti-neuroblastoma antibody chCE7

    International Nuclear Information System (INIS)

    Carrel, F.; Novak-Hofer, I.; Ruch, C.; Zimmermann, K.; Amstutz, H.

    1997-01-01

    The in vitro and in vivo behaviour of the monovalent single chain (scFv) and Fab-fragments derived from anti-neuroblastoma antibody chCE7 is reported. When comparing tumour uptake and -retention of radioactivity of 67 Cu-labelled monovalent chCE7 with divalent chCE7 F(ab') 2 the advantage of the radiocopper label over the radioiodine label was more pronounced with the divalent (internalising) F(ab') 2 fragments. (author) 1 fig., 1 ref

  4. Positivity-preserving space-time CE/SE scheme for high speed flows

    KAUST Repository

    Shen, Hua

    2017-03-02

    We develop a space-time conservation element and solution element (CE/SE) scheme using a simple slope limiter to preserve the positivity of the density and pressure in computations of inviscid and viscous high-speed flows. In general, the limiter works with all existing CE/SE schemes. Here, we test the limiter on a central Courant number insensitive (CNI) CE/SE scheme implemented on hybrid unstructured meshes. Numerical examples show that the proposed limiter preserves the positivity of the density and pressure without disrupting the conservation law; it also improves robustness without losing accuracy in solving high-speed flows.

  5. Dynamique de spin dans le supraconducteur non conventionnel CeCoIn¥

    OpenAIRE

    Panarin , Justin

    2012-01-01

    In this thesis, the spin dynamics of CeCoIn5 has been studied by inelastic neutron scattering. CeCoIn5 presents the highest critical temperature ( Tc = 2.3 K) among heavy fermion Ce-based compounds and shows an unconventionnal supraconductivity with a $d_{x^2-y^2}$-wave gap. The magnetic excitation spectra is radically changed in the supraconducting state with the apparition of an intense excitation named "Spin resonance". This kind of excitation has already been discovered in high-Tc superco...

  6. Energy transfer and luminescent properties of Ce{sup 3+}, Cr{sup 3+} co-doped Y{sub 3}Al{sub 5}O{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Shao Liming [Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Jing Xiping, E-mail: xpjing@pku.edu.c [Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

    2011-06-15

    The phosphors in the system Y{sub 3-x}Al{sub 5-y}O{sub 12}:xCe{sup 3+},yCr{sup 3+} were synthesized by solid-state reactions and their photoluminescence properties were investigated. These phosphors have absorption in the visible light region and give luminescence in the far-red region ({approx}688 nm), which are suitable for the application in the device of luminescent solar concentrator (LSC). In these phosphors, Ce{sup 3+} located at Y{sup 3+} site can effectively transfer its absorbed energy to Cr{sup 3+} at Al{sup 3+} site. - Research highlights: {yields} Ce{sup 3+}-Cr{sup 3+} co-doped Y{sub 3}Al{sub 5}O{sub 12} can absorb UV/visible light and give far-red emission. {yields} Energy transfer from Ce{sup 3+} to Cr{sup 3+} occurs with efficiency {approx}0.8. {yields} The studied material may be used to improve the efficiency of Si solar cell.

  7. Low-temperature carbon monoxide oxidation over zirconia-supported CuO–CeO{sub 2} catalysts: Effect of zirconia support properties

    Energy Technology Data Exchange (ETDEWEB)

    Moretti, Elisa, E-mail: elisa.moretti@unive.it [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, INSTM Venice Research Unit, Via Torino 155/B, 30172 Mestre Venezia (Italy); Molina, Antonia Infantes [Departamento de Química Inorgánica, Cristalografía y Mineralogía, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071 Málaga (Spain); Sponchia, Gabriele; Talon, Aldo; Frattini, Romana [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, INSTM Venice Research Unit, Via Torino 155/B, 30172 Mestre Venezia (Italy); Rodriguez-Castellon, Enrique [Departamento de Química Inorgánica, Cristalografía y Mineralogía, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071 Málaga (Spain); Storaro, Loretta [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, INSTM Venice Research Unit, Via Torino 155/B, 30172 Mestre Venezia (Italy)

    2017-05-01

    Highlights: • CuO-CeO{sub 2}/ZrO{sub 2} materials were investigated in the low temperature CO oxidation. • High surface area ZrO{sub 2} synthetized by sol-gel method. • Low ZrO{sub 2} surface area synthetized by fast precipitation. • Sol-gel samples showed, after impregnation, a severe decrease of surface area. • CuO-CeO{sub 2}/ZrO{sub 2} with precipitated ZrO{sub 2} led to a very active catalyst. - Abstract: A study was conducted to investigate the effect of the preparation route of ZrO{sub 2} in CuO–CeO{sub 2}/ZrO{sub 2} catalysts for the oxidation of carbon monoxide at low temperature (COX). Four ZrO{sub 2} supports were synthetized via either type sol-gel methodology or precipitation. The final Cu-Ce-Zr oxide catalysts were prepared by incipient wetness co-impregnation with copper and cerium solutions (with a loading of 6 wt% of CuO and 20 wt% of CeO{sub 2}). The catalyst crystalline phases, texture and active species reducibility were determined by XRD, N{sub 2} physisorption at −196 °C and H{sub 2}-TPR, respectively; meanwhile the surface composition and copper-cerium electronic states were studied by XPS. The catalytic activity was evaluated in the oxidation of CO to CO{sub 2}, in the 40–215 °C temperature range. Catalytic results evidenced that the samples prepared by a sol-gel methodology showed, after the impregnation, a severe decrease of specific surface area and pore volume attributable to a wide degree of pore blockage caused by the presence of metal oxide particles and a collapse of the structure partially burying the active sites. A simple co-impregnation of a zirconia support, obtained through facile and fast precipitation, provided instead a catalyst with very good redox properties and high dispersion of the active phases, which completely oxidizes CO in the range 115–215 °C with T{sub 50} of 65 °C. This higher observed activity was ascribed to the formation of a larger fraction of highly dispersed and easily reducible Cu

  8. Reaction mechanisms for the CO oxidation on Au/CeO(2) catalysts: activity of substitutional Au(3+)/Au(+) cations and deactivation of supported Au(+) adatoms.

    Science.gov (United States)

    Camellone, Matteo Farnesi; Fabris, Stefano

    2009-08-05

    Density functional theory calculations that account for the on-site Coulomb interaction via a Hubbard term (DFT+U) reveal the mechanisms for the oxidation of CO catalyzed by isolated Au atoms as well as small clusters in Au/CeO(2) catalysts. Ceria (111) surfaces containing positively charged Au ions, either as supported Au(+) adatoms or as substitutional Au(3+) ions, are shown to activate molecular CO and to catalyze its oxidation to CO(2). In the case of supported single Au(+) adatoms, the limiting rate for the CO oxidation is determined by the adsorbate spillover from the adatom to the oxide support. The reaction then proceeds with the CO oxidation via lattice oxygen and O vacancy formation. These vacancies are shown to readily attract the supported Au(+) adatoms and to turn them into negatively charged Au(delta-) adspecies that deactivate the catalyst, preventing further CO adsorption. Au(3+) ions dispersed into the ceria lattice as substitutional point defects can instead sustain a full catalytic cycle consisting of three individual steps maintaining their activity along the reaction process: Au cations in Au(x)Ce(1-x)O(2) systems promote multiple oxidations of CO without any activation energy via formation of surface O vacancies. Molecular oxygen adsorbs at these vacancies and forms O adspecies that then catalyze the oxidation of molecular CO, closing the catalytic cycle and recovering the stoichiometric Au(x)Ce(1-x)O(2) system. The interplay between the reversible Ce(4+)/Ce(3+) and Au(3+)/Au(+) reductions underpins the high catalytic activity of dispersed Au atoms into the ceria substrate. It is shown that the positive oxidation state of the substitutional Au ions is retained along the catalytic cycle, thus preventing the deactivation of Au(x)Ce(1-x)O(2) catalysts in operation conditions. Finally, although a single Au(+) adatom bound to an O vacancy is shown to deactivate during CO oxidation, the calculations predict that the reactivity of gold nanoparticles

  9. Preparations and characterizations of γ-Ce2S3 red pigments from Pr-doped CeO2 with improved thermal stabilities

    Science.gov (United States)

    Gao, Y. Q.; Li, Y. M.; Wang, Z. M.; Shen, Z. Y.; Xie, Z. X.

    2018-02-01

    The Pr-doped γ-Ce2S3 red pigment was prepared by a hydrothermal combine sulfurize process. CeCl3·7H2O, Pr6O11, and CS2 were used as cerium source, dopant source, and sulfur source, respectively. Pr-doped CeO2 precursor was prepared at 180 °C with hydrothermal method, followed by sulfurize treatment 150 min at 900 °C. The effect of doped proportion, sulfurize condition to phase composition of red pigment was observed. Furthermore, the thermal stabilities and chromaticity of as-prepared pigment were investigated. Results of calcinations in the air and color measure indicated that Pr-doping enhances the resistant temperature for oxidization of pigment. A red color ( L* = 25.58, a* = 29.47, b* = 17.27) was still remained after heated at 470 °C in the air.

  10. CE-PA: A user's manual for determination of controlling earthquakes and development of seismic hazard information data base for the central and eastern United States

    International Nuclear Information System (INIS)

    Short, C.

    1995-05-01

    The CE-PA, Controlling Earthquake(s) through Probabilistic Analysis, software package developed at Lawrence Livermore National Laboratory (LLNL) is a research program used as part of a study performed for the US Office of Nuclear Regulatory Research Division Engineering project on Geosciences Issues in the revision of geological siting criteria. The objectives of this study were to explore ways on how to use results from probabilistic seismic hazard characterization (PSHC) to determine hazard-consistent scenario earthquakes and to develop design ground motion. The purpose of this document is to describe the CE-PA software to users. The software includes two operating system and process controllers plus several fortran routines and input decks. This manual gives an overview of the methodology to estimate controlling earthquakes in Section I. A descriptive overview of the procedures and the organization of the program modules used in CE-PA is provided in Section II. Section III contains four example executions with comments and a graphical display of each execution path, plus an overview of the directory/file structure. Section IV provides some general observations regarding the model

  11. Band-gap narrowing and magnetic behavior of Ni-doped Ba(Ti0.875Ce0.125)O3 thin films

    Science.gov (United States)

    Zhou, Wenliang; Deng, Hongmei; Yu, Lu; Yang, Pingxiong; Chu, Junhao

    2015-11-01

    Band-gap narrowing and magnetic effects have been observed in a Ni-doped Ba(Ti0.875Ce0.125)O3 (BTC) thin film. Structural characterizations and microstructural analysis show that the as-prepared Ba(Ti0.75Ce0.125Ni0.125)O3-δ (BTCN) thin film exhibits a cubic perovskite structure with an average grain size of 25 nm. The Ce doping at the Ti-site results in an increasing perovskite volume to favour an O-vacancy-stabilized Ni2+ substitution. Raman spectroscopy, however, shows the cubic symmetry of crystalline structures is locally lowered by the presence of dopants, significantly deviating from the ideal Pm3m space group. Moreover, BTCN presents a narrowed band-gap, much smaller than that of BaTiO3 and BTC, due to new states of both the highest occupied molecular orbital and the lowest unoccupied molecular orbital in an electronic structure with the presence of Ni. Also, magnetic enhancement driven by co-doping has been confirmed in the films, which mainly stems from the exchange interaction of Ni2+ ions via an electron trapped in a bridging oxygen vacancy. These findings may open an avenue to discover and design optimal perovskite compounds for solar-energy devices and information storage.

  12. [Requirements for CE-marking of apps and wearables].

    Science.gov (United States)

    Berensmann, Michael; Gratzfeld, Markus

    2018-03-01

    Depending on the intended use, apps and wearables can be medical devices. In such cases, the manufacturer has to provide evidence that the requirements stated in directive 93/42/EWG are fulfilled. Depending on the classification of the medical device, several so-called conformity assessment procedures are possible. Once the conformity assessment procedure has been finished successfully, the manufacturer attaches the CE-marking to the product. This assures that all requirements of the directive have been fulfilled and the manufacturer is therefore authorized to put the product onto the market in all member states of the European union. In this article, the possible and practical conformity assessment procedures for apps and wearables are described and their implementation is outlined.For medical devices with sufficiently high-risk classification, the manufacturer has to involve a Notified Body. For the conformity assessment procedure according to annex II, the manufacturer implements a full quality management system and compiles technical documentation. These are supervised and evaluated by Notified Body audits. Especially for startups, it is important for the development of apps and wearables to implement a quality management system early and to fulfill the regulatory requirements, for example, related to the software life-cycle model. This also includes considering accompanying processes during development like risk management, usability engineering, and clinical evaluation.Additionally, it should be pointed out, that according to the new medical device regulation almost all apps will fall at least into class IIa. Thus, the involvement of a Notified Body in the related conformity assessment procedures would be required. Apps that have already been put onto the market as class I devices, and are now upgraded to a higher class, need the approval of a notified body starting from 26 May 2020.

  13. Heavy fermions and quantum critical behavior in CeCu6-xAux (x=0-0.2) and CeAl3

    International Nuclear Information System (INIS)

    Sluchanko, D.N.; Glushkov, V.V.; Demishev, S.V.; Ignatov, M.I.; Samarin, N.A.; Burkhanov, G.S.; Chistyakov, O.D.; Sluchanko, N.E.

    2006-01-01

    Precision magnetoresistance (MR) Δρ/ρ(H,T) and Hall coefficient R H measurements have been carried out for archetypal Ce-based heavy fermion compounds-CeCu 6-x Au x (x=0, 0.1 and 0.2) and CeAl 3 on high quality polycrystalline samples over a wide temperature range 1.8-300K in magnetic fields up to 70kOe. It was found the Brillouin-type component of MR Δρ/ρ(H,T)∼H 2 that can be consistently interpreted in the frameworks of a simple relation between resistivity and magnetization -Δρ/ρ∼M 2 obtained by K. Yosida (Phys. Rev. 107 (1957) 396). A local magnetic susceptibility χ loc (T,H)=(1/H(d(Δρ/ρ)/dH)) 1/2 deduced from the data obtained is compared with the data of bulk susceptibility measurements χ(T,H). The study of anomalous Hall effect allows us to establish for the first time a complicated activation type behavior of R H and estimate the bound energies E a1,2 of many body states at E F for CeAl 3 and CeCu 6 heavy fermion compounds. Microscopic parameters of charge carriers transport (effective masses, relaxation time) and localization radius a p1,2 * of these heavy quasiparticles (a p1 * (T>50K)∼1.5A and a p2 * (T 6 and CeAl 3 ) were also estimated

  14. On the response of Y3Al5O12: Ce (YAG: Ce) powder scintillating screens to medical imaging X-rays

    International Nuclear Information System (INIS)

    Kandarakis, I.; Cavouras, D.; Sianoudis, I.; Nikolopoulos, D.; Episkopakis, A.; Linardatos, D.; Margetis, D.; Nirgianaki, E.; Roussou, M.; Melissaropoulos, P.; Kalivas, N.; Kalatzis, I.; Kourkoutas, K.; Dimitropoulos, N.; Louizi, A.; Nomicos, C.; Panayiotakis, G.

    2005-01-01

    The aim of this study was to examine Y 3 Al 5 O 12 :Ce (also known as YAG:Ce) powder scintillator under X-ray imaging conditions. This material shows a very fast scintillation decay time and it has never been used in X-ray medical imaging. In the present study various scintillator layers (screens) with coating thickness ranging from 13 to 166mg/cm 2 were prepared in our laboratory by sedimentation of Y 3 Al 5 O 12 : Ce powder. Optical emission spectra and light emission efficiency (spectrum area over X-ray exposure) of the layers were measured under X-ray excitation using X-ray tube voltages (80-120kVp) often employed in general medical radiography and fluoroscopy. Spectral compatibility with various optical photon detectors (photodiodes, photocathodes, charge coupled devices, films) and intrinsic conversion efficiency values were determined using emission spectrum data. In addition, parameters related to X-ray detection, energy absorption efficiency and K-fluorescence characteristic emission were calculated. A theoretical model describing radiation and light transfer through scattering media was used to fit experimental data. Intrinsic conversion efficiency (ηC ∼0.03-0.05) and light attenuation coefficients (σ∼26.5cm 2 /g) were derived through this fitting. Y 3 Al 5 O 12 :Ce showed peak emission in the wavelength range 530-550nm. The light emission efficiency was found to be maximum for the 107mg/cm 2 layer. Due to its 'green' emission spectrum, Y 3 Al 5 O 12 :Ce showed excellent compatibility (of the order of 0.9) with the sensitivity of many currently used photodetectors. Taking into account its very fast response Y 3 Al 5 O 12 :Ce could be considered for application in X-ray imaging especially in various digital detectors

  15. Qu’est-ce que le naturalisme ?

    Directory of Open Access Journals (Sweden)

    Olivier Morin

    2012-01-01

    Full Text Available Cet article répond aux critiques récemment adressées aux tenants du « naturalisme social » dans les pages de la revue SociologieS. Il le fait en défendant un naturalisme minimal, bâti sur trois idées : l’interdisciplinarité est permise ; la pensée est un processus causal qui a lieu dans un monde matériel ; l’humanité est une espèce animale. Ces idées pourront sembler triviales ; le débat auquel nous assistons montre qu’il n’en est rien. Je passerai en revue les arguments les plus fréquemment opposés à ce naturalisme. Le dialogue entre sciences cognitives et sciences sociales ne prélude pas à une O.P.A. de la neurobiologie sur les autres disciplines. Aucun chercheur sérieux ne voit la cognition humaine comme un assemblage de modules à l’architecture entièrement fixée dès la naissance et incapables d’interagir avec leur environnement. Le fait que les processus mentaux n’aient pas lieu uniquement dans nos têtes est aujourd’hui un lieu commun des sciences cognitives. Enfin, l’étude de l’évolution de l’humanité, vue comme une espèce biologique, est porteuse de conclusions qui pour être très générales, n’en sont pas moins pertinentes pour les sciences sociales.What is Naturalism?This article responds to recent critics addressed to the advocates of « social naturalism » in the journal SociologieS. It does so by defending a minimal naturalism structured around three ideas: interdisciplinarity is allowed; thought is a causal process that occurs in a material world; humanity is a species. These ideas may seem trivial; the debate we’re assisting to shows us otherwise. I will go through the arguments that most frequently oppose naturalism. The dialogue between cognitive and social sciences is not a prelude to the takeover of neurobiology on other disciplines. No serious researcher sees human cognition as an assembly of architectural modules entirely fixed from birth and incapable of

  16. Experimental evidence for self-assembly of CeO2 particles in solution: Formation of single-crystalline porous CeO2 nanocrystals

    DEFF Research Database (Denmark)

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

    2012-01-01

    Single-crystalline porous CeO2 nanocrystals, with sizes of ∼20 nm and pore diameters of 1-2 nm, were synthesized successfully using a hydrothermal method. Using electron tomography, we imaged the three-dimensional structure of the pores in the nanocrystals and found that the oriented aggregation ...... energy-loss spectroscopy. The oxygen vacancies might play an important role in oxygen diffusion in the crystals and the catalytic activities of single-crystalline porous CeO 2 structures. © 2011 American Chemical Society....

  17. A comparative study of LaBr3(Ce(3+)) and CeBr3 based gamma-ray spectrometers for planetary remote sensing applications.

    Science.gov (United States)

    Kozyrev, A; Mitrofanov, I; Owens, A; Quarati, F; Benkhoff, J; Bakhtin, B; Fedosov, F; Golovin, D; Litvak, M; Malakhov, A; Mokrousov, M; Nuzhdin, I; Sanin, A; Tretyakov, V; Vostrukhin, A; Timoshenko, G; Shvetsov, V; Granja, C; Slavicek, T; Pospisil, S

    2016-08-01

    The recent availability of large volume cerium bromide crystals raises the possibility of substantially improving gamma-ray spectrometer limiting flux sensitivities over current systems based on the lanthanum tri-halides, e.g., lanthanum bromide and lanthanum chloride, especially for remote sensing, low-level counting applications or any type of measurement characterized by poor signal to noise ratios. The Russian Space Research Institute has developed and manufactured a highly sensitive gamma-ray spectrometer for remote sensing observations of the planet Mercury from the Mercury Polar Orbiter (MPO), which forms part of ESA's BepiColombo mission. The Flight Model (FM) gamma-ray spectrometer is based on a 3-in. single crystal of LaBr3(Ce(3+)) produced in a separate crystal development programme specifically for this mission. During the spectrometers development, manufacturing, and qualification phases, large crystals of CeBr3 became available in a subsequent phase of the same crystal development programme. Consequently, the Flight Spare Model (FSM) gamma-ray spectrometer was retrofitted with a 3-in. CeBr3 crystal and qualified for space. Except for the crystals, the two systems are essentially identical. In this paper, we report on a comparative assessment of the two systems, in terms of their respective spectral properties, as well as their suitability for use in planetary mission with respect to radiation tolerance and their propensity for activation. We also contrast their performance with a Ge detector representative of that flown on MESSENGER and show that: (a) both LaBr3(Ce(3+)) and CeBr3 provide superior detection systems over HPGe in the context of minimally resourced spacecraft and (b) CeBr3 is a more attractive system than LaBr3(Ce(3+)) in terms of sensitivities at lower gamma fluxes. Based on the tests, the FM has now been replaced by the FSM on the BepiColombo spacecraft. Thus, CeBr3 now forms the central gamma-ray detection element on the MPO spacecraft.

  18. A New Cerium-Based Ternary Oxide Slurry, CeTi2O6, for Chemical-Mechanical Polishing

    Science.gov (United States)

    Yoshida, Masato; Koyama, Naoyuki; Ashizawa, Toranosuke; Sakata, Yoshihisa; Imamura, Hayao

    2007-03-01

    A new ternary oxide slurry, CeTi2O6 containing Ce4+ ions, was found to be effective as an abrasive in chemical-mechanical polishing (CMP). The ternary oxide was synthesized by the Pechini polymerizable complex (PC) method. X-ray diffraction (XRD) Rietveld analysis indicated that the oxide possesses a single CeTi2O6 phase of a brannerite structure (C2/m, No. 12). When CeTi2O6 was used as an abrasive slurry for polishing thin oxide film, the removal rate was as high as that of ceria (CeO2) slurry.

  19. Structural effects in the interstitial solid solution system (La,Ce)(Fe,Si)13Cx-H: Correlation with hydrogenation kinetics

    Science.gov (United States)

    Hai, X.; Porcher, F.; Mayer, C.; Miraglia, S.

    2018-02-01

    Steady state and in-situ neutron powder diffraction on selected compositions of the magneto-caloric (La,Ce)(Fe,Si)13CxHy compounds has been used to locate the sites accommodated by the interstitial species and to reveal the structural modifications (breathing) that occur upon metal substitution and/or interstitial insertion. The latter type of measurement in which the sequential filling of interstitial sites is followed allows one to extract some useful hydrogenation kinetics data. This structural investigation has allowed to precise the deformations undergone by the complex metallic alloys La(Fe,Si)13 when subjected to light interstitial insertion or rare earth substitution at the cation site of the NaZn13-structure type. We attempt to correlate hydrogenation kinetics variations (depression or enhancement of the hydrogen absorption rate) with a particular inhomogeneous cell variation (breathing) and bonding of the NaZn13 structure-type.

  20. Low-temperature carbon monoxide oxidation over zirconia-supported CuO-CeO2 catalysts: Effect of zirconia support properties

    Science.gov (United States)

    Moretti, Elisa; Molina, Antonia Infantes; Sponchia, Gabriele; Talon, Aldo; Frattini, Romana; Rodriguez-Castellon, Enrique; Storaro, Loretta

    2017-05-01

    A study was conducted to investigate the effect of the preparation route of ZrO2 in CuO-CeO2/ZrO2 catalysts for the oxidation of carbon monoxide at low temperature (COX). Four ZrO2 supports were synthetized via either type sol-gel methodology or precipitation. The final Cu-Ce-Zr oxide catalysts were prepared by incipient wetness co-impregnation with copper and cerium solutions (with a loading of 6 wt% of CuO and 20 wt% of CeO2). The catalyst crystalline phases, texture and active species reducibility were determined by XRD, N2 physisorption at -196 °C and H2-TPR, respectively; meanwhile the surface composition and copper-cerium electronic states were studied by XPS. The catalytic activity was evaluated in the oxidation of CO to CO2, in the 40-215 °C temperature range. Catalytic results evidenced that the samples prepared by a sol-gel methodology showed, after the impregnation, a severe decrease of specific surface area and pore volume attributable to a wide degree of pore blockage caused by the presence of metal oxide particles and a collapse of the structure partially burying the active sites. A simple co-impregnation of a zirconia support, obtained through facile and fast precipitation, provided instead a catalyst with very good redox properties and high dispersion of the active phases, which completely oxidizes CO in the range 115-215 °C with T50 of 65 °C. This higher observed activity was ascribed to the formation of a larger fraction of highly dispersed and easily reducible Cu species and ceria nanocrystallites, mainly present as Ce(IV), with an average size of 5 nm.