WorldWideScience

Sample records for cerium tellurides

  1. Oxidation of chromium telluride

    International Nuclear Information System (INIS)

    The authors study the interaction between chromium telluride and oxygen at elevated temperatures in view of its application in semiconductor technology. Thermodynamic analysis of the oxidation process and experimental data showed that the alloys of chromium telluride suffer oxidation in the presence of even traces of oxygen in a gaseous medium. Chromium telluride oxidation is a complex process that gives rise to various oxides and is accompanied by partial sublimation

  2. Oxidation of chromium telluride

    Energy Technology Data Exchange (ETDEWEB)

    Pakhomovskaya, N.S.; Iorga, E.V.; Sheveleva, T.F.; Solov' eva, A.E.

    1986-03-01

    The authors study the interaction between chromium telluride and oxygen at elevated temperatures in view of its application in semiconductor technology. Thermodynamic analysis of the oxidation process and experimental data showed that the alloys of chromium telluride suffer oxidation in the presence of even traces of oxygen in a gaseous medium. Chromium telluride oxidation is a complex process that gives rise to various oxides and is accompanied by partial sublimation.

  3. Far infrared properties of PbTe doped with cerium

    Energy Technology Data Exchange (ETDEWEB)

    Nikolic, P.M. [Institute of Technical Sciences SASA, Knez Mihailova 35/IV, 11000 Belgrade (Serbia)]. E-mail: nikolic@sanu.ac.yu; Koenig, W. [Max Planck Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 7000 Stuttgart 80 (Germany); Vujatovic, S.S. [Institute of Technical Sciences SASA, Knez Mihailova 35/IV, 11000 Belgrade (Serbia); Blagojevic, V. [Faculty of Electronic Engineering, University of Belgrade, Bulevar Kralja Aleksandra 73, 11000 Belgrade (Serbia); Lukovic, D. [Institute of Technical Sciences SASA, Knez Mihailova 35/IV, 11000 Belgrade (Serbia); Savic, S. [Institute of Technical Sciences SASA, Knez Mihailova 35/IV, 11000 Belgrade (Serbia); Radulovic, K. [Institute of Technical Sciences SASA, Knez Mihailova 35/IV, 11000 Belgrade (Serbia); Urosevic, D. [Mathematical Institute SASA, Knez Mihailova 35/I, 11000 Belgrade (Serbia); Nikolic, M.V. [Center for Multidisciplinary Studies of the University of Belgrade, Kneza Viseslava 1, Belgrade (Serbia)

    2007-05-16

    Single crystal samples of lead telluride doped with cerium were made using the Bridgman method. Far infrared reflectivity spectra in the temperature range from 10 to 300 K are presented. The experimental data were numerically analyzed using a fitting procedure based on the plasmon-phonon interaction model and optical parameters were determined. Two additional local modes were observed at about 138 and 337 cm{sup -1}. The origin of these local vibrational impurity modes was discussed.

  4. Chalcogenide Cobalt telluride nanotubes

    Science.gov (United States)

    Dahal, Bishnu; Dulal, Rajendra; Pegg, Ian L.; Philip, John

    Cobalt telluride nanotubes are grown using wet chemical and hydrothermal syntheses. Wet chemical synthesized nanotubes display nearly 1: 1 Co to Te ratio. On the other hand, CoTe nanotubes synthesized using hydrothermal method show excess Co content leading to the compound Co58Te42. Both CoTe and Co58Te42 display magnetic properties, but with totally different characteristics. The Curie temperature of CoTe is higher than 400 K. However, the Tc of Co58Te42 is below 50 K. Transport properties of cobalt telluride (CoTe) nanotube devices show that they exhibit p-type semiconducting behavior. The magnetoresistance measured at 10 K show a magnetoresistance of 54%. . National Science Foundation under ECCS-0845501 and NSF-MRI, DMR-0922997.

  5. Reaction chemistry of cerium

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-01

    It is truly ironic that a synthetic organic chemist likely has far greater knowledge of the reaction chemistry of cerium(IV) than an inorganic colleague. Cerium(IV) reagents have long since been employed as oxidants in effecting a wide variety of organic transformations. Conversely, prior to the late 1980s, the number of well characterized cerium(IV) complexes did not extend past a handful of known species. Though in many other areas, interest in the molecular chemistry of the 4f-elements has undergone an explosive growth over the last twenty years, the chemistry of cerium(IV) has for the most part been overlooked. This report describes reactions of cerium complexes and structure.

  6. Probing the cerium/cerium hydride interface using nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Brierley, Martin, E-mail: martin.brierley@awe.co.uk [Atomic Weapons Establishment, Aldermaston, Berkshire RG7 4PR (United Kingdom); University of Manchester, Manchester M13 9PL (United Kingdom); Knowles, John, E-mail: john.knowles@awe.co.uk [Atomic Weapons Establishment, Aldermaston, Berkshire RG7 4PR (United Kingdom)

    2015-10-05

    Highlights: • A disparity exists between the minimum energy and actual shape of a cerium hydride. • Cerium hydride is found to be harder than cerium metal by a ratio of 1.7:1. • A zone of material under compressive stress was identified surrounding the hydride. • No distribution of hardness was apparent within the hydride. - Abstract: A cerium hydride site was sectioned and the mechanical properties of the exposed phases (cerium metal, cerium hydride, oxidised cerium hydride) were measured using nanoindentation. An interfacial region under compressive stress was observed in the cerium metal surrounding a surface hydride that formed as a consequence of strain energy generated by the volume expansion associated with precipitation of the hydride phase.

  7. Probing the cerium/cerium hydride interface using nanoindentation

    International Nuclear Information System (INIS)

    Highlights: • A disparity exists between the minimum energy and actual shape of a cerium hydride. • Cerium hydride is found to be harder than cerium metal by a ratio of 1.7:1. • A zone of material under compressive stress was identified surrounding the hydride. • No distribution of hardness was apparent within the hydride. - Abstract: A cerium hydride site was sectioned and the mechanical properties of the exposed phases (cerium metal, cerium hydride, oxidised cerium hydride) were measured using nanoindentation. An interfacial region under compressive stress was observed in the cerium metal surrounding a surface hydride that formed as a consequence of strain energy generated by the volume expansion associated with precipitation of the hydride phase

  8. Cadmium telluride nuclear radiation detectors

    International Nuclear Information System (INIS)

    The characteristics and performance of undoped high resistivity cadmium telluride detectors are compared to chlorine lifted counters. It is shown, in particular, that Undodep CdTe is in fact aluminium doped and that compensation occurs, as an silicon or germanium, by pair and triplet formation between the group III donor and the doubly charged cadmium vacancy acceptor. Furthermore, in chlorine doped samples, the polarization effect results from the unpaired level at Esub(c)-0,6eV

  9. Hydrated cerium(3) vanadates

    International Nuclear Information System (INIS)

    It has been ascertained by the methods of chemical, thermal and X-ray phase analyses, IR spectroscopy that in the system LiVO3-Ce(NO3)3-HNO3-LiOH-H2O in equilibrium conditions the following compounds are precipitated: cerium dodecavanadate Ce2(V12O31)3·3nH2O, where 11.0 5O13)2·nH2O, where 6.5 2V10O28·19H2O; vanadates Ce(VO3)3·4H2O and CeVO4·H2O. Cerium orthovanadate is crystallized in tetragonal crystal system with zircon structure and crystal lattice parameters as follows: a=7.3726(14) and c=6.4939(23) A

  10. Method of making a thin film cadmium telluride solar cell

    International Nuclear Information System (INIS)

    A method for making a photovoltaic cell is described comprising the steps of: (a) depositing a transparent or semi-transparent conductive window layer onto a substrate; (b) depositing a layer of cadmium telluride including phosphorus onto the window layer; (c) depositing a layer of lead telluride onto the layer of cadmium telluride; and (d) depositing a metallic electrode onto the lead telluride layer

  11. Thin film cadmium telluride, zinc telluride, and mercury zinc telluride solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Chu, T.L. (University of South Florida, Tampa, FL (United States))

    1992-04-01

    This report describes research to demonstrate (1) thin film cadmium telluride solar cells with a quantum efficiency of 75% or higher at 0. 44 {mu}m and a photovoltaic efficiency of 11.5% or greater, and (2) thin film zinc telluride and mercury zinc telluride solar cells with a transparency to sub-band-gap radiation of 65% and a photovoltaic conversion efficiency of 5% and 8%, respectively. Work was directed at (1) depositing transparent conducting semiconductor films by solution growth and metal-organic chemical vapor deposition (MOCVD) technique, (2) depositing CdTe films by close-spaced sublimation (CSS) and MOCVD techniques, (3) preparing and evaluating thin film CdTe solar cells, and (4) preparing and characterizing thin film ZnTe, CD{sub 1-x}Zn{sub 1-x}Te, and Hg{sub 1-x}Zn{sub x}Te solar cells. The deposition of CdS films from aqueous solutions was investigated in detail, and their crystallographic, optical, and electrical properties were characterized. CdTe films were deposited from DMCd and DIPTe at 400{degrees}C using TEGa and AsH{sub 3} as dopants. CdTe films deposited by CSS had significantly better microstructures than those deposited by MOCVD. Deep energy states in CdTe films deposited by CSS and MOCVD were investigated. Thin films of ZnTe, Cd{sub 1- x}Zn{sub x}Te, and Hg{sub 1-x}Zn{sub x}Te were deposited by MOCVD, and their crystallographic, optical, and electrical properties were characterized. 67 refs.

  12. Thermodynamic properties of cerium oxide

    International Nuclear Information System (INIS)

    Thermodynamic properties of cerium oxides in the CeO2-CeO1.5 composition range are studied. For this purpose method of electromotive force with solid electrolyte is used, equilibrium constants of reduction of cerium oxides by hydrogen are measured. Necessity of using atmosphere of argon or purified nitrogen to work with pyrophoric cerium oxides is stressed. The obtained results and the earlier known literary data on CeO2 and Ce2O3 thermodynamic properties are tabulated. 14 refs.; 5 tabs

  13. Ellipsometric Studies on Silver Telluride Thin Films

    Directory of Open Access Journals (Sweden)

    M. Pandiaraman

    2011-01-01

    Full Text Available Silver telluride thin films of thickness between 45 nm and 145 nm were thermally evaporated on well cleaned glass substrates at high vacuum better than 10 – 5 mbar. Silver telluride thin films are polycrystalline with monoclinic structure was confirmed by X-ray diffractogram studies. AFM and SEM images of these films are also recorded. The phase ratio and amplitude ratio of these films were recorded in the wavelength range between 300 nm and 700 nm using spectroscopic ellipsometry and analysed to determine its optical band gap, refractive index, extinction coefficient, and dielectric functions. High absorption coefficient determined from the analysis of recorded spectra indicates the presence of direct band transition. The optical band gap of silver telluride thin films is thickness dependent and proportional to square of reciprocal of thickness. The dependence of optical band gap of silver telluride thin films on film thickness has been explained through quantum size effect.

  14. Cadmium zinc telluride spectral modeling

    International Nuclear Information System (INIS)

    Cadmium zinc telluride (CZT) detectors are the highest resolution room temperature gamma-ray detectors available for isotopic analysis. As with germanium detectors, accurate isotopic analysis using spectra requires peak deconvolution. The CZT peak shapes are asymmetric, with a long low energy tail. The asymmetry is a result of the physics of the electron/hole transport in the semiconductor. An accurate model of the physics of the electron/hole transport through an electric field will allow the parameterization of the peak shapes as a function of energy. In turn this leads to the ability to perform accurate spectral deconvolution and therefore accurate isotopic analysis. The model and the peak-shape parameterization as a function of energy will be presented

  15. Preparation of cerium halide solvate complexes

    Science.gov (United States)

    Vasudevan, Kalyan V; Smith, Nickolaus A; Gordon, John C; McKigney, Edward A; Muenchaussen, Ross E

    2013-08-06

    Crystals of a solvated cerium(III) halide solvate complex resulted from a process of forming a paste of a cerium(III) halide in an ionic liquid, adding a solvent to the paste, removing any undissolved solid, and then cooling the liquid phase. Diffusing a solvent vapor into the liquid phase also resulted in crystals of a solvated cerium(III) halide complex.

  16. Electrodeposition and Characterization of Bismuth Telluride Nanowires

    Science.gov (United States)

    Frantz, C.; Stein, N.; Gravier, L.; Granville, S.; Boulanger, C.

    2010-09-01

    In this work, we report thermoelectric measurements on electroplated bismuth telluride nanowires. Porous polycarbonate membranes, obtained by ion-track irradiation lithography, were chosen as electroplating templates. Bismuth telluride nanowires were achieved in acidic media under potentiostatic conditions at -100 mV versus saturated silver chloride electrode. The filling ratio of the pores was increased to 80% by adding dimethyl sulfoxide to the electrolyte. Whatever the experimental conditions, the nanowires were polycrystalline in the rhombohedral phase of Bi2Te3. Finally, the power output of arrays of bismuth telluride nanowires was analyzed as a function of load resistance. The results were strongly dependent on the internal resistance, which can be significantly reduced by the presence of dimethyl sulfoxide during electroplating.

  17. Cadmium telluride quantum dots advances and applications

    CERN Document Server

    Donegan, John

    2013-01-01

    Optical Properties of Bulk and Nanocrystalline Cadmium Telluride, Núñez Fernández and M.I. VasilevskiyAqueous Synthesis of Colloidal CdTe Nanocrystals, V. Lesnyak, N. Gaponik, and A. EychmüllerAssemblies of Thiol-Capped CdTe Nanocrystals, N. GaponikFörster Resonant Energy Transfer in CdTe Nanocrystal Quantum Dot Structures, M. Lunz and A.L. BradleyEmission of CdTe Nanocrystals Coupled to Microcavities, Y.P. Rakovich and J.F. DoneganBiological Applications of Cadmium Telluride Semiconductor Quantum Dots, A. Le Cign

  18. Valence instabilities in cerium intermetallics

    International Nuclear Information System (INIS)

    The primary purpose of this investigation was to study the magnetic behaviour of cerium in intermetallic compounds, that show an IV behaviour, e.g. CeSn3. In the progress of the investigations, it became of interest to study the effect of changes in the lattice of the IV compound by substituting La or Y for Ce, thus constituting the Cesub(1-x)Lasub(x)Sn3 and Cesub(1-x)Ysub(x)Sn3 quasibinary systems. A second purpose was to examine the possibility of introducing instabilities in the valency of a trivalent intermetallic cerium compound: CeIn3, also by La and Y-substitutions in the lattice. Measurements on the resulting Cesub(1-x)Lasub(x)In3 and Cesub(1-x)Ysub(x)In3 quasibinaries are described. A third purpose was to study the (gradual) transition from a trivalent cerium compound into an IV cerium compound. This was done by examining the magnetic properties of the CeInsub(x)Snsub(3-x) and CePbsub(x)Snsub(3-x) systems. Finally a new possibility was investigated: that of the occurrence of IV behaviour in CeSi2, CeSi, and in CeGa2. (Auth.)

  19. Physicochemical properties of a cadmium telluride surface

    International Nuclear Information System (INIS)

    Change of chemical state of cadmium telluride surface is investigated after different treatments (exposure in air, vacuum, gaseous media, γ- and IR-irradiation). The results of these investigations are of great interest for clarifying the nature of active surface of diamond-like semiconductors, the mechanism of its interaction with different media and the possibilities of surface properties regulation

  20. Improvements in or relating to cerium compounds

    International Nuclear Information System (INIS)

    A process for the preparation of a dispersible cerium compound comprises heating a substantially dry cerium (IV) oxide hydrate in the presence of a deaggregating agent to cause deaggregation of aggregated crystallites in the cerium (IV) oxide hydrate and produce a dry dispersible cerium compound. The deaggregating agent is an acid species e.g. NO3-, Cl- or ClO4-. The dry dispersible product may be mixed with an aqueous medium to form a colloidal dispersion and if the dispersion is allowed to dry, a gel. (author)

  1. Radiative lifetimes of neutral cerium

    International Nuclear Information System (INIS)

    Radiative lifetimes, accurate to ±5%, have been measured for 153 levels of neutral cerium using time-resolved laser-induced fluorescence (TRLIF) on a slow beam of cerium atoms. Of the 153 levels studied, 150 are even parity and 3 are odd parity. The levels range in energy from 16 869 to 28 557 cm-1. This set of Ce I lifetimes is much more extensive than others published to date, and will provide the absolute calibration for a very large set of measured Ce I transition probabilities. Accurate transition probabilities for lines in the visible and ultraviolet are needed both in astrophysics, for the determination of elemental abundances, and by the lighting community, for research and development of metal halide high-intensity discharge lamps.

  2. Radiative lifetimes of neutral cerium

    Energy Technology Data Exchange (ETDEWEB)

    Den Hartog, E A; Buettner, K P; Lawler, J E [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)], E-mail: eadenhar@wisc.edu, E-mail: Kevin.Buettner@usma.edu, E-mail: jelawler@wisc.edu

    2009-04-28

    Radiative lifetimes, accurate to {+-}5%, have been measured for 153 levels of neutral cerium using time-resolved laser-induced fluorescence (TRLIF) on a slow beam of cerium atoms. Of the 153 levels studied, 150 are even parity and 3 are odd parity. The levels range in energy from 16 869 to 28 557 cm{sup -1}. This set of Ce I lifetimes is much more extensive than others published to date, and will provide the absolute calibration for a very large set of measured Ce I transition probabilities. Accurate transition probabilities for lines in the visible and ultraviolet are needed both in astrophysics, for the determination of elemental abundances, and by the lighting community, for research and development of metal halide high-intensity discharge lamps.

  3. Electron mobility in mercury cadmium telluride

    Science.gov (United States)

    Patterson, James D.

    1988-01-01

    A previously developed program, which includes all electronic interactions thought to be important, does not correctly predict the value of electron mobility in mercury cadmium telluride particularly near room temperature. Part of the reason for this discrepancy is thought to be the way screening is handled. It seems likely that there are a number of contributors to errors in the calculation. The objective is to survey the calculation, locate reasons for differences between experiment and calculation, and suggest improvements.

  4. Thermal conductivity of bulk nanostructured lead telluride

    International Nuclear Information System (INIS)

    Thermal conductivity of lead telluride with embedded nanoinclusions was studied using Monte Carlo simulations with intrinsic phonon transport properties obtained from first-principles-based lattice dynamics. The nanoinclusion/matrix interfaces were set to completely reflect phonons to model the maximum interface-phonon-scattering scenario. The simulations with the geometrical cross section and volume fraction of the nanoinclusions matched to those of the experiment show that the experiment has already reached the theoretical limit of thermal conductivity. The frequency-dependent analysis further identifies that the thermal conductivity reduction is dominantly attributed to scattering of low frequency phonons and demonstrates mutual adaptability of nanostructuring and local disordering

  5. Thermal conductivity of bulk nanostructured lead telluride

    Energy Technology Data Exchange (ETDEWEB)

    Hori, Takuma [Department of Mechanical Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); Chen, Gang [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Shiomi, Junichiro, E-mail: shiomi@photon.t.u-tokyo.ac.jp [Department of Mechanical Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 (Japan)

    2014-01-13

    Thermal conductivity of lead telluride with embedded nanoinclusions was studied using Monte Carlo simulations with intrinsic phonon transport properties obtained from first-principles-based lattice dynamics. The nanoinclusion/matrix interfaces were set to completely reflect phonons to model the maximum interface-phonon-scattering scenario. The simulations with the geometrical cross section and volume fraction of the nanoinclusions matched to those of the experiment show that the experiment has already reached the theoretical limit of thermal conductivity. The frequency-dependent analysis further identifies that the thermal conductivity reduction is dominantly attributed to scattering of low frequency phonons and demonstrates mutual adaptability of nanostructuring and local disordering.

  6. Inhibited oxidation of polymethylsiloxane, containing cerium

    International Nuclear Information System (INIS)

    The kinetics of oxidation of oligomeric polydimethylsiloxane in the presence of cerium-containing organosilicon antioxidant at 285-310 deg was investigated. High energy of activation for initiation process (around 272 kJ/mole) was established as a feature specific for chain oxidation of polydimethylsiloxane. It was found that cerium-containing antioxidant, as well as the iron-containing one, based on iron capronate, is of the ''depleting'' inhibitors, i.e. it looses its inhibiting ability during oxidation

  7. Electrodeposition of Oriented Cerium Oxide Films

    OpenAIRE

    Golden, Teresa D.; Adele Qi Wang

    2013-01-01

    Cerium oxide films of preferred orientation are electrodeposited under anodic conditions. A complexing ligand, acetate, was used to stabilize the cerium (III) ion in solution for deposition of the thin films. Fourier transform infrared spectroscopy showed that the ligand and metal tended to bind as a weakly bidentate complex. The crystallite size of the films was in the nanometer range as shown by Raman spectroscopy and was calculated from X-ray diffraction data. Crystallite sizes from 6 to 2...

  8. Ionic flotation of cerium, praseodymium and neodymium

    International Nuclear Information System (INIS)

    The possibility of practically complete flotation extraction of cerium, praseodymium and neodymium ions collected with the help of potassium abietate is shown. It is established that the most complete flotation extraction of cerium, praseodymium and neodymium ions takes place from solutions having 6-8 pH value in the presence of 1.5-2.5 multiple collector surplus. Solution temperature increase from 20 to 80 deg influences positively the flotation process

  9. Pharmacological potential of cerium oxidenanoparticles

    Science.gov (United States)

    Celardo, Ivana; Pedersen, Jens Z.; Traversa, Enrico; Ghibelli, Lina

    2011-04-01

    Nanotechnology promises a revolution in pharmacology to improve or create ex novo therapies. Cerium oxidenanoparticles (nanoceria), well-known as catalysts, possess an astonishing pharmacological potential due to their antioxidant properties, deriving from a fraction of Ce3+ ions present in CeO2. These defects, compensated by oxygen vacancies, are enriched at the surface and therefore in nanosized particles. Reactions involving redox cycles between the Ce3+ and Ce4+oxidation states allow nanoceria to react catalytically with superoxide and hydrogen peroxide, mimicking the behavior of two key antioxidant enzymes, superoxide dismutase and catalase, potentially abating all noxious intracellularreactive oxygen species (ROS) via a self-regenerating mechanism. Hence nanoceria, apparently well tolerated by the organism, might fight chronic inflammation and the pathologies associated with oxidative stress, which include cancer and neurodegeneration. Here we review the biological effects of nanoceria as they emerge from in vitro and in vivo studies, considering biocompatibility and the peculiar antioxidant mechanisms.

  10. New Layered Ternary Transition-Metal Tellurides

    Science.gov (United States)

    Mar, Arthur

    Several new ternary transition-metal tellurides, a class of compounds hitherto largely unexplored, have been synthesized and characterized. These are layered materials whose structures have been determined by single -crystal X-ray diffraction methods. The successful preparation of the compound TaPtTe_5 was crucial in developing an understanding of the MM'Te_5 (M = Nb, Ta; M' = Ni, Pd, Pt) series of compounds, which adopt either of two possible closely-related layered structures. Interestingly, the compound TaPdTe _5 remains unknown. Instead, the compound Ta_4Pd_3Te _{16} has been prepared. Its structure is closely related to that of the previously prepared compound Ta_3Pd _3Te_{14}. The physical properties of these compounds have been measured and correlated with the metal substitutions and interlayer separations. A new series of compounds, MM'Te _4 (M = Nb, Ta; M' = Ru, Os, Rh, Ir), has been discovered. The structure of NbIrTe_4 serves as a prototype: it is an ordered variant of the binary telluride WTe_2. Electronic band-structure calculations have been performed in order to rationalize the trends in metal-metal and tellurium -tellurium bonding observed in WTe_2 and the MM'Te_4 phases. Extension of these studies to include main-group metals has resulted in the synthesis of the new layered ternary germanium tellurides TiGeTe_6, ZrGeTe_4 , and HfGeTe_4. Because germanium can behave ambiguously in its role as a metalloid element, it serves as an anion by capping the metal-centered trigonal prisms and also as a cation in being coordinated in turn by other tellurium atoms in a trigonal pyramidal fashion. Structural relationships among these compounds are illustrated through the use of bicapped trigonal prisms and trigonal pyramids as the basic structural building blocks. The electrical and magnetic properties of these compounds have been measured. Insight into the unusual bonding and physical properties of these germanium-containing compounds has been gained through

  11. Effect of gamma radiation on cadmium telluride surface properties

    International Nuclear Information System (INIS)

    The effect of γ-irradiation on the surface properties of cadmium telluride is studied. The possibility of oriented modification of surface properties for increasing the adsorption activity and obtaining the materials, suited for the sensor transducer production, is shown

  12. Kelvin Probe Studies of Cesium Telluride Photocathode for AWA Photoinjector

    OpenAIRE

    Wisniewski, Eric; Velazquez, Daniel; Yusof, Zikri; Spentzouris, Linda; Terry, Jeff; Harkay, Katherine

    2012-01-01

    Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for a new Argonne Wakefield Accelerator (AWA) beamline to produce high charge per bunch (~50 nC) in a long bunch train. Here, we present a study of the work function of cesium telluride photocathode using the Kelvin Probe technique. The study incl...

  13. Avalanche multiplication of electrons and holes in cadmium telluride

    CERN Document Server

    Demich, N V

    2001-01-01

    Determination of the ratio of the coefficients of the electrons and holes of the diode structures impact ionization is carried out with the purpose of optimizing the parameters of the avalanche diodes from the cadmium telluride. It is shown experimentally, that the process of the impact ionization in the cadmium telluride is stimulated by holes. The ratio of the coefficients of the holes and electrons impact ionization constitutes approx = 30-40

  14. Optimization of process efficiency in cerium electrorefining

    International Nuclear Information System (INIS)

    Reactive metal electrorefining presents a number of problems that pose daunting obstacles to commercial operation. Typical reduction of reactive metal oxides or halide can introduce a variety of impurities such as iron, nickel, chromium, silicon, aluminum and various other metals which must be removed. This research program has addressed the various parameters of molten salt electrorefining of cerium metal to provide insight to this extremely important process. Cerium has been chosen as the surrogate for certain reactive metals on account of its similar electrochemical characteristics. The justification for such a choice has been investigated. The cell components and configuration, current efficiency of the process, purity of the cathodically deposited metal and the power requirement of the system have been optimized in a molten calcium chloride salt electrolyte using a molten, stirred impure metal anode. Various refractory crucible design and electrode materials have been studied to improve the process reliability. The equimolar NaKCl2 salt used in the electrorefining of some reactive metals is found to be inappropriate as a relatively high temperature is required to electrorefine cerium, i.e. melting point of Ce [798 C]. The homogeneity of the anode is controlled by the stirring at an optimized rate. This paper highlights the validity of cerium oxide and intermetallics of cerium as a surrogate for other reactive metal oxides or the respective intermetallics

  15. Anisotropy of thermal expansion and electric resistance of cermet germanium telluride

    International Nuclear Information System (INIS)

    Anisotropies of thermal expansion α and electric resistance ρ of cermet germanium telluride were investigated depending on pressing conditions. It is shown that anisotropy of cermet germanium telluride depends sufficiently on pressing conditions with respect to thermal expansion and electric resistance. It was established that anisotropy of the cermet germanium telluride was strongly affected by pressing force and temperature. Anisotropy of the cermet germanium telluride also depends with respect to α and ρ on the material and size of the mould

  16. Scanning tunneling microscope study of cadmium telluride

    International Nuclear Information System (INIS)

    Layered samples of cadmium telluride grown epitaxially on gallium arsenide substrates have been investigated by means of scanning tunneling microscopy (STM). The surface geometric and electronic structures are both of interest. Techniques were developed to remove the native oxide by etching, or to create a fresh surface by cleaving, and to protect them from oxidation by employing mineral or paraffin oil media. STM studies were conducted within the protective medium. These techniques were adapted and tested for both etched and cleaved samples of Si, CdTe and HgTe. The current-voltage characteristics of the CdTe surface were investigated during dynamic changes of the tunnel current and barrier height while the probe-to-sample separation (gap) was static. Recorded values are shown for current versus bias for several constant gap values. A range of bias values has been employed to test a possible solution for the problem of interference between the contributions from geometric and electronic structure factors

  17. Thin-film cadmium telluride solar cells

    Science.gov (United States)

    Chu, T. L.

    1987-10-01

    Cadmium telluride, with a room-temperature band-gap energy of 1.5 eV, is a promising thin-film photovoltaic material. The major objective of this research has been to demonstrate thin-film CdTe heterojunction solar cells with a total area greater than 1 sq cm and photovoltaic efficiencies of 13 percent or more. Thin-film p-CdTe/CdS/SnO2:F/glass solar cells with an AM1.5 efficiency of 10.5 percent have been reported previously. This report contains results of work done on: (1) the deposition, resistivity control, and characterization of p-CdTe films by the close-spaced sublimation process; (2) the deposition of large-band-gap window materials; (3) the electrical properties of CdS/CdTe heterojunctions; (4) the formation of stable, reproducible, ohmic contacts (such as p-HgTe) to p-CdTe; and (5) the preparation and evaluation of heterojunction solar cells.

  18. Study of the discharge ionization of cerium at a solid-paste graphite electrode

    International Nuclear Information System (INIS)

    The discharge ionization of cerium(3) at a solid-paste graphite electrode was studied by stripping voltametry. The optimal conditions for the concentration and following determination of cerium in 1 x 10-4 - 1 x 10-6 M cerium(3) solutions were found. The conditional constant of cerium(4) reduction to cerium(3) was also calculated

  19. New layered functionalized cerium(IV) phenylphosphonates

    Czech Academy of Sciences Publication Activity Database

    Melánová, Klára; Beneš, L.; Svoboda, Jan; Zima, Vítězslav; Vlček, Milan

    Lille: European Materials Research Society, 2014. Q.PI-20. [E- MRS 2014 Spring Meeting. 26.05.2014-30.05.2014, Lille] R&D Projects: GA ČR(CZ) GA14-13368S Institutional support: RVO:61389013 Keywords : cerium * layered phosphonates * thermogravimetry Subject RIV: CA - Inorganic Chemistry

  20. The Archaean gold-telluride-sulphide and gold-telluride mineralisation of a multiple stage hydrothermal vein deposit at the Commoner Mine, Zimbabwe

    International Nuclear Information System (INIS)

    The Commoner Mine is situated on the western edge of the Midlands greenstone belt, 50 km west-southwest of Kadoma, Zimbabwe. Current geological interest in this deposit was initiated by the presence of coarse grained telluride minerals in ore exposed on 21 level in 1978. The deposit is a hydrothermal quartz-calcite vein. It was found that coarse grained gold-silver tellurides fill fractures which transect the telluride breccia. Comparison of the physical and mineralogical characteristics of the Commoner orebody with those of the Tertiary gold-telluride deposits of the Circum Pacific Belt and the Archaean deposits of Canada and Australia indicates that this mineralisation was probably deposited in a near-surface environment. It was found that the gold-telluride ores of the Commoner Mine display features characteristic of both plutonic-hydrothermal and volcanic-hydrothermal styles of telluride mineralisation

  1. High-temperature thermoelectric behavior of lead telluride

    Indian Academy of Sciences (India)

    M P Singh; C M Bhandari

    2004-06-01

    Usefulness of a material in thermoelectric devices is temperature specific. The central problem in thermoelectric material research is the selection of materials with high figure-of-merit in the given temperature range of operation. It is of considerable interest to know the utility range of the material, which is decided by the degrading effect of minority carrier conduction. Lead telluride is among the best-known materials for use in the temperature range 400—900 K. This paper presents a detailed theoretical investigation of the role of minority carriers in degrading the thermoelectric properties of lead telluride and outlines the temperature range for optimal performance.

  2. Lead telluride with increased mechanical stability for cylindrical thermoelectric generators

    International Nuclear Information System (INIS)

    The aim of this work is to improve the mechanical stability of lead telluride (PbTe), trying to vary its mechanical properties independently from its thermoelectric properties. Thus the influence of material preparation as well as different dopants on the mechanical and thermoelectric properties of lead telluride is being analysed. When using appropriately set process parameters, milling and sintering of lead telluride increases the material's hardness. With sintering temperatures exceeding 300 C stable material of high relative density can be achieved. Milling lead telluride generates lattice defects leading to a reduction of the material's charge carrier density. These defects can be reduced by increased sintering temperatures. Contamination of the powder due to the milling process leads to bloating during thermal cycling and thus reduced density of the sintered material. In addition to that, evaporation of tellurium at elevated temperatures causes instability of the material's thermoelectric properties. Based on the experimental results obtained in this work, the best thermoelectric and mechanical properties can be obtained by sintering coarse powders at around 400 C. Within this work a concept was developed to vary the mechanical properties of lead telluride via synthesis of PbTe with electrically nondoping elements, which thus may keep the thermoelectric properties unchanged. Therefore, the mechanical and thermoelectric properties of Pb1-xCaxTe were investigated. Doping pure PbTe with calcium causes a significant increase of the material's hardness while only slightly decreasing the charge carrier density and thus keeping the thermoelectric properties apart from a slight reduction of the electrical conductivity nearly unchanged. The abovementioned concept is proven using sodium doped lead telluride, as it is used for thermoelectric generators: The additional doping with calcium again increases the material's hardness while its thermoelectric properties remain

  3. Uptake and accumulation of bulk and nanosized cerium oxide particles and ionic cerium by radish (Raphanus sativus L.).

    Science.gov (United States)

    Zhang, Weilan; Ebbs, Stephen D; Musante, Craig; White, Jason C; Gao, Cunmei; Ma, Xingmao

    2015-01-21

    The potential toxicity and accumulation of engineered nanomaterials (ENMs) in agricultural crops has become an area of great concern and intense investigation. Interestingly, although below-ground vegetables are most likely to accumulate the highest concentrations of ENMs, little work has been done investigating the potential uptake and accumulation of ENMs for this plant group. The overall objective of this study was to evaluate how different forms of cerium (bulk cerium oxide, cerium oxide nanoparticles, and the cerium ion) affected the growth of radish (Raphanus sativus L.) and accumulation of cerium in radish tissues. Ionic cerium (Ce(3+)) had a negative effect on radish growth at 10 mg CeCl3/L, whereas bulk cerium oxide (CeO2) enhanced plant biomass at the same concentration. Treatment with 10 mg/L cerium oxide nanoparticles (CeO2 NPs) had no significant effect on radish growth. Exposure to all forms of cerium resulted in the accumulation of this element in radish tissues, including the edible storage root. However, the accumulation patterns and their effect on plant growth and physiological processes varied with the characteristics of cerium. This study provides a critical frame of reference on the effects of CeO2 NPs versus their bulk and ionic counterparts on radish growth. PMID:25531028

  4. Thin films and solar cells of cadmium telluride and cadmium zinc telluride

    Energy Technology Data Exchange (ETDEWEB)

    Ferekides, C.S.

    1991-01-01

    The objectives of this dissertation are to investigate (1) the metalorganic chemical vapor deposition (MOCVD) and properties of cadmium telluride (CdTe) and cadmium zinc telluride (Cd(1-x)Zn(z)Te) films and junctions, and their potential application to solar cells, and (2) the fabrication and characterization of CdTe solar cells by the close spaced sublimation (CSS) technique. CdTe and Cd(1-x)Zn(x)Te films have been deposited by MOCVD on a variety of substrates at 300-400 C.The effect of the deposition parameters and post deposition heat treatments on the electrical, optical, and structural properties have been investigated. Heterojunctions of the configuration CdTe/transparent conducting semiconductor (TCS) and Cd(1-x)Zn(x)Te/TCS have been prepared and characterized. CdTe(MOCVD)/CdS and Cd(1-x)Zn(x)Te(E sub g = 1.65eV)/Cd(1-x)Zn(x)S solar cells with efficiencies of 9.9 percent and 2.4 percent, respectively have been fabricated. The as-deposited CdTe(MOCVD)/CdS junctions exhibited high dark current densities due to deflects at the interface associated with small grain size. No effective post-deposition heat treatment has been developed. CdTe/CdS solar cells have also been fabricated by the close spaced sublimation (CSS). Significant improvements in material and processing have been made, and in collaboration with fellow researchers an AM1.5 conversion efficiency of 13.4 percent has been demonstrated, the highest efficiency ever measured for such devices. The highest conversion efficiency for the CdTe(CSS)/CdS solar cell was achieved by reaching high open-circuit voltages and fill factors, while the short-circuit current densities were moderate. These results indicate that further improvements to increase the short-circuit current densities can result in conversion efficiencies over 15 percent.

  5. Ultrasonication of Bismuth Telluride Nanocrystals Fabricated by Solvothermal Method

    Science.gov (United States)

    Chu, Sang-Hyon; Choi, Sang H.; Kim, Jae-Woo; King, Glen C.; Elliott, James R.

    2006-01-01

    The objective of this study is to evaluate the effect of ultrasonication on bismuth telluride nanocrystals prepared by solvothermal method. In this study, a low dimensional nanocrystal of bismuth telluride (Bi2Te3) was synthesized by a solvothermal process in an autoclave at 180 C and 200 psi. During the solvothermal reaction, organic surfactants effectively prevented unwanted aggregation of nanocrystals in a selected solvent while controlling the shape of the nanocrystal. The atomic ratio of bismuth and tellurium was determined by energy dispersive spectroscopy (EDS). The cavitational energy created by the ultrasonic probe was varied by the ultrasonication process time, while power amplitude remained constant. The nanocrystal size and its size distribution were measured by field emission scanning electron microscopy (FESEM) and a dynamic light scattering system. When the ultrasonication time increased, the average size of bismuth telluride nanocrystal gradually increased due to the direct collision of nanocrystals. The polydispersity of the nanocrystals showed a minimum when the ultrasonication was applied for 5 min. Keywords: bismuth telluride, nanocrystal, low-dimensional, ultrasonication, solvothermal

  6. Photovoltaic materials based on telluride of transient metals

    Czech Academy of Sciences Publication Activity Database

    Štengl, Václav; Ecorchard, Petra; Schelonka, Darina; Bludská, Jana

    Stow cum Quy: Zing Conferences, 2014. s. 59. [Nanocrystals Conference. 13.6.2014–16.6.2014, Punta Cana] R&D Projects: GA MPO FR-TI4/399 Institutional support: RVO:61388980 Keywords : telluride * ultrasound Subject RIV: CA - Inorganic Chemistry

  7. Understanding the Meaning of the Entrance Image: The Telluride Process.

    Science.gov (United States)

    Garnham, Harry L.; Garnham, Penny

    1989-01-01

    Describes a project to define the images of Telluride (Colorado) held by its residents and tourists and contributing to sense of place. Discusses the design of the town's entry points and efforts to maintain their visual environments in harmony with the town's defined character during ongoing community development. (SV)

  8. Phase transition of bismuth telluride thin films grown by MBE

    DEFF Research Database (Denmark)

    Fülöp, Attila; Song, Yuxin; Charpentier, Sophie;

    2014-01-01

    A previously unreported phase transition between Bi2Te3 and Bi4Te3 in bismuth telluride grown by molecular beam epitaxy is recorded via XRD, AFM, and SIMS observations. This transition is found to be related to the Te/Bi beam equivalent pressure (BEP) ratio. BEP ratios below 17 favor the formatio...

  9. Thermodynamic studies in the system cerium-gadolinium-oxygen

    International Nuclear Information System (INIS)

    Two independent measuring methods have been applied to studying the phase relations of the system cerium-gadolinium. The calorimetric measurements have been done in a high-temperature calorimeter with cerium dioxide doped with 10 mole % of Gd2O3. Further thermodynamic quantities have been obtained by the electrochemical method and e.m.f. measurements, yielding additional information on disorders in doped cerium dioxide. (orig./BBR)

  10. Electrochemical reduction of cerium oxide into metal

    International Nuclear Information System (INIS)

    The Fray Farthing and Chen (FFC) and Ono and Suzuki (OS) processes were developed for the reduction of titanium oxide to titanium metal by electrolysis in high temperature molten alkali chloride salts. The possible transposition to CeO2 reduction is considered in this study. Present work clarifies, by electro-analytical techniques, the reduction pathway leading to the metal. The reduction of CeO2 into metal was feasible via an indirect mechanism. Electrolyses on 10 g of CeO2 were carried out to evaluate the electrochemical process efficiency. Ca metal is electrodeposited at the cathode from CaCl2-KCl solvent and reacts chemically with ceria to form not only metallic cerium, but also cerium oxychloride.

  11. Electrochemical reduction of cerium oxide into metal

    Energy Technology Data Exchange (ETDEWEB)

    Claux, Benoit [CEA, Valduc, F-21120 Is-sur-Tille (France); Universite de Grenoble, LEPMI-ENSEEG, 1130 rue de la Piscine, BP75, F-38402 St Martin d' Heres Cedex (France); Serp, Jerome, E-mail: jerome.serp@cea.f [CEA, Valduc, F-21120 Is-sur-Tille (France); Fouletier, Jacques [Universite de Grenoble, LEPMI-ENSEEG, 1130 rue de la Piscine, BP75, F-38402 St Martin d' Heres Cedex (France)

    2011-02-28

    The Fray Farthing and Chen (FFC) and Ono and Suzuki (OS) processes were developed for the reduction of titanium oxide to titanium metal by electrolysis in high temperature molten alkali chloride salts. The possible transposition to CeO{sub 2} reduction is considered in this study. Present work clarifies, by electro-analytical techniques, the reduction pathway leading to the metal. The reduction of CeO{sub 2} into metal was feasible via an indirect mechanism. Electrolyses on 10 g of CeO{sub 2} were carried out to evaluate the electrochemical process efficiency. Ca metal is electrodeposited at the cathode from CaCl{sub 2}-KCl solvent and reacts chemically with ceria to form not only metallic cerium, but also cerium oxychloride.

  12. Cerium and jojoba in engines?; Cerium et jojoba dans les moteurs?

    Energy Technology Data Exchange (ETDEWEB)

    Massy-Delhotel, E.

    1996-10-01

    The Belgium company CreaTel proposes a new system, called Forac, which can lead to a 10% reduction of fuel consumption in thermal engines together with a quasi-complete reduction of CO, HC, NOx pollutants and CO{sub 2} particulates emission. The system comprises a steam production device and an admission pipe with a cerium alloy whorl inside. The steam produced is mixed with the admission air and tears cerium particles from the inside of the admission pipe to the combustion chamber. The cerium particles act as a catalyst which favours the complete combustion of the fuel. The same company proposes also lubricant additives made from liquid jojoba wax which allow the reduction of pollutant emissions, fuel consumption and noise emissions of diesel engines. (J.S.)

  13. Structural, optical, morphological and dielectric properties of cerium oxide nanoparticles

    International Nuclear Information System (INIS)

    Cerium oxide (CeO2) nanoparticles were prepared by the precipitation method. The average crystallite size of cerium oxide nanoparticles was calculated from the X-ray diffraction (XRD) pattern and found to be 11 nm. The FT-IR spectrum clearly indicated the strong presence of cerium oxide nanoparticles. Raman spectrum confirmed the cubic nature of the cerium oxide nanoparticles. The Scanning Electron Microscopy (SEM) analysis showed that the nanoparticles agglomerated forming spherical-shaped particles. The Transmission Electron Microscopic (TEM) analysis confirmed the prepared cerium oxide nanoparticles with the particle size being found to be 16 nm. The optical absorption spectrum showed a blue shift by the cerium oxide nanoparticles due to the quantum confinement effect. The dielectric properties of cerium oxide nanoparticles were studied for different frequencies at different temperatures. The dielectric constant and the dielectric loss of the cerium oxide nanoparticles decreased with increase in frequency. The AC electrical conductivity study revealed that the conduction depended on both the frequency and the temperature. (author)

  14. Structural, optical, morphological and dielectric properties of cerium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Prabaharan, Devadoss Mangalam Durai Manoharadoss [Department of Physics, NPR College of Engineering and Technology, Natham, Dindigul, Tamil Nadu (India); Sadaiyandi, Karuppasamy [Department of Physics, Alagappa Government Arts College, Karaikudi, Sivaganga, Tamil Nadu (India); Mahendran, Manickam [Department of Physics, Thiagarajar College of Engineering, Madurai, Tamil Nadu (India); Sagadevan, Suresh, E-mail: duraiphysics2011@gmail.com [Department of Physics, AMET University (India)

    2016-03-15

    Cerium oxide (CeO{sub 2}) nanoparticles were prepared by the precipitation method. The average crystallite size of cerium oxide nanoparticles was calculated from the X-ray diffraction (XRD) pattern and found to be 11 nm. The FT-IR spectrum clearly indicated the strong presence of cerium oxide nanoparticles. Raman spectrum confirmed the cubic nature of the cerium oxide nanoparticles. The Scanning Electron Microscopy (SEM) analysis showed that the nanoparticles agglomerated forming spherical-shaped particles. The Transmission Electron Microscopic (TEM) analysis confirmed the prepared cerium oxide nanoparticles with the particle size being found to be 16 nm. The optical absorption spectrum showed a blue shift by the cerium oxide nanoparticles due to the quantum confinement effect. The dielectric properties of cerium oxide nanoparticles were studied for different frequencies at different temperatures. The dielectric constant and the dielectric loss of the cerium oxide nanoparticles decreased with increase in frequency. The AC electrical conductivity study revealed that the conduction depended on both the frequency and the temperature. (author)

  15. Radiation induced color centers in cerium-doped and cerium-free multicomponent silicate glasses

    Institute of Scientific and Technical Information of China (English)

    傅鑫杰; 宋力昕; 李家成

    2014-01-01

    The effect of doped cerium on the radiation-resistance behavior of silicate glass was investigated in our work. The ultra-violet-visible absorption spectra and electron paramagnetic resonance (EPR) spectra were obtained after the cerium-rich and ce-rium-free multicomponent silicate glasses (K509 and K9) were irradiated by gamma rays with a dose range from 10 to 1000 kGy. The results showed that E’ center, oxygen deficient center (ODC) and non-bridging oxygen hole center (HC1 and HC2) were induced in K9 and K509 glasses after radiation. The concentrations of all color centers presented an exponential growth with the increase of the gamma dose. Moreover, the concentration of HC1 and HC2 in cerium-doped K509 glass was much lower than that in cerium-free K9 glass at the same dose of radiation, which could be attributed to the following mechanism:Ce3+ions capturing holes then forming Ce3++centers inhibited the formation of hole trapped color centers (HC1 and HC2) and Ce4+ions capturing electrons to form Ce3+centers suppressed the formation of electron trapped color centers like E’ center.

  16. The Cadmium Zinc Telluride Imager on AstroSat

    CERN Document Server

    Bhalerao, V; Vibhute, A; Pawar, P; Rao, A R; Hingar, M K; Khanna, Rakesh; Kutty, A P K; Malkar, J P; Patil, M H; Arora, Y K; Sinha, S; Priya, P; Samuel, Essy; Sreekumar, S; Vinod, P; Mithun, N P S; Vadawale, S V; Vagshette, N; Navalgund, K H; Sarma, K S; Pandiyan, R; Seetha, S; Subbarao, K

    2016-01-01

    The Cadmium Zinc Telluride Imager (CZTI) is a high energy, wide-field imaging instrument on AstroSat. CZT's namesake Cadmium Zinc Telluride detectors cover an energy range from 20 keV to > 200 keV, with 11% energy resolution at 60 keV. The coded aperture mask attains an angular resolution of 17' over a 4.6 deg x 4.6 deg (FWHM) field of view. CZTI functions as an open detector above 100 keV, continuously sensitive to GRBs and other transients in about 30% of the sky. The pixellated detectors are sensitive to polarisation above ~100 keV, with exciting possibilities for polarisation studies of transients and bright persistent sources. In this paper, we provide details of the complete CZTI instrument, detectors, coded aperture mask, mechanical and electronic configuration, as well as data and products.

  17. Kelvin Probe Studies of Cesium Telluride Photocathode for AWA Photoinjector

    CERN Document Server

    Wisniewski, Eric; Yusof, Zikri; Spentzouris, Linda; Terry, Jeff; Harkay, Katherine

    2012-01-01

    Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for a new Argonne Wakefield Accelerator (AWA) beamline to produce high charge per bunch (~50 nC) in a long bunch train. Here, we present a study of the work function of cesium telluride photocathode using the Kelvin Probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the effect of UV exposure on the work function, and the evolution of the work function during and after photocathode rejuvenation via heating.

  18. Thin film cadmium telluride, zinc telluride, and mercury zinc telluride solar cells. Final subcontract report, 1 July 1988--31 December 1991

    Energy Technology Data Exchange (ETDEWEB)

    Chu, T.L. [University of South Florida, Tampa, FL (United States)

    1992-04-01

    This report describes research to demonstrate (1) thin film cadmium telluride solar cells with a quantum efficiency of 75% or higher at 0. 44 {mu}m and a photovoltaic efficiency of 11.5% or greater, and (2) thin film zinc telluride and mercury zinc telluride solar cells with a transparency to sub-band-gap radiation of 65% and a photovoltaic conversion efficiency of 5% and 8%, respectively. Work was directed at (1) depositing transparent conducting semiconductor films by solution growth and metal-organic chemical vapor deposition (MOCVD) technique, (2) depositing CdTe films by close-spaced sublimation (CSS) and MOCVD techniques, (3) preparing and evaluating thin film CdTe solar cells, and (4) preparing and characterizing thin film ZnTe, CD{sub 1-x}Zn{sub 1-x}Te, and Hg{sub 1-x}Zn{sub x}Te solar cells. The deposition of CdS films from aqueous solutions was investigated in detail, and their crystallographic, optical, and electrical properties were characterized. CdTe films were deposited from DMCd and DIPTe at 400{degrees}C using TEGa and AsH{sub 3} as dopants. CdTe films deposited by CSS had significantly better microstructures than those deposited by MOCVD. Deep energy states in CdTe films deposited by CSS and MOCVD were investigated. Thin films of ZnTe, Cd{sub 1- x}Zn{sub x}Te, and Hg{sub 1-x}Zn{sub x}Te were deposited by MOCVD, and their crystallographic, optical, and electrical properties were characterized. 67 refs.

  19. Tunneling behavior of bismuth telluride nanoplates in electrical transport

    OpenAIRE

    Eginligil, Mustafa; Zhang, Weiqing; Kalitsov, Alan; Lu, Xianmao; Yang, Hyunsoo

    2012-01-01

    We study the electrical transport properties of ensembles of bismuth telluride (Bi2Te3) nanoplates grown by solution based chemical synthesis. Devices consisting of Bi2Te3 nanoplates are fabricated by surface treatment after dropping the solution on the structured gold plates and the temperature dependence of resistance shows a nonmetallic behavior. Symmetric tunneling behavior in I-V was observed in both our experimental results and theoretical calculation of surface conductance based on a s...

  20. Microscopic mechanism of low thermal conductivity in lead-telluride

    OpenAIRE

    Shiga, Takuma; Shiomi, Junichiro; Ma, Jie; Delaire, Olivier; Radzynski, Tomasz; Lusakowski, Andrzej; Esfarjani, Keivan; Chen, Gang

    2012-01-01

    The microscopic physics behind low lattice thermal conductivity of single crystal rocksalt lead telluride (PbTe) is investigated. Mode-dependent phonon (normal and umklapp) scattering rates and their impact on thermal conductivity were quantified by the first-principles-based anharmonic lattice dynamics calculations that accurately reproduce thermal conductivity in a wide temperature range. The low thermal conductivity of PbTe is attributed to the scattering of longitudinal acoustic phonons b...

  1. Transient Response of Cadmium Telluride Modules to Light Exposure: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Deline, C.; del Cueto, J.; Albin, D. S.; Petersen, C.; Tyler, L.; TamizhMani, G.

    2011-07-01

    Commercial cadmium telluride (CdTe) photovoltaic (PV) modules from three different manufacturers were monitored for performance changes during indoor and outdoor light-exposure. Short-term transients in Voc were recorded on some modules, with characteristic times of ~1.1 hours. Outdoor performance data shows a similar drop in Voc after early morning light exposure. Preliminary analysis of FF changes show light-induced changes on multiple time scales, including a long time scale.

  2. Growth rate and crystal habit of germanium telluride

    International Nuclear Information System (INIS)

    Controlling steps of GeTe crystal growth under different experimental conditions were determined. Diffusion coefficient of GeTe molecules in argon was found, and condensation coefficient was evaluated. Influence of mass transfer rate in a gas on crystal habit was studied: crystals have round faces at low rates and dendritic growth is observed at high rates. Optimal conditions of growing edged crystals of germanium telluride of α-3 mm size were determined

  3. Fission-product tellurium and cesium telluride chemistry revisited

    International Nuclear Information System (INIS)

    The chemistry of fission-product tellurium is discussed with a focus on conditions in an operating CANDU reactor and in an accident scenario, i.e., a loss of coolant accident (LOCA). Cesium telluride, Cs2Te, is likely to be one of the most abundant tellurium species released to containment. Available thermodynamic data on gas phase Cs2Te is not complete; hence the volatility of cesium telluride was studied by Knudsen-cell mass spectrometry. Cesium telluride was found to vapourize incongruently, becoming more tellurium-rich in the condensed phase as vapourization progressed. Vapour-phase species that were observed were elemental cesium and tellurium, CsTe, Cs2Te, Cs2Te2 and Cs2Te3. Second-law enthalpies and entropies were obtained for many of these species, and a third-law value, ΔH298o, of 186 ± 2 kJ·mol-1 was obtained for Cs2Te. (author)

  4. Ultrathin, epitaxial cerium dioxide on silicon

    International Nuclear Information System (INIS)

    It is shown that ultrathin, highly ordered, continuous films of cerium dioxide may be prepared on silicon following substrate prepassivation using an atomic layer of chlorine. The as-deposited, few-nanometer-thin Ce2O3 film may very effectively be converted at room temperature to almost fully oxidized CeO2 by simple exposure to air, as demonstrated by hard X-ray photoemission spectroscopy and X-ray diffraction. This post-oxidation process essentially results in a negligible loss in film crystallinity and interface abruptness

  5. Ultrathin, epitaxial cerium dioxide on silicon

    OpenAIRE

    Flege, Jan Ingo; Kaemena, Björn; Höcker, Jan; Bertram, Florian; Wollschläger, Joachim; Schmidt, Thomas; Falta, Jens

    2014-01-01

    It is shown that ultrathin, highly ordered, continuous films of cerium dioxide may be prepared on silicon following substrate prepassivation using an atomic layer of chlorine. The as-deposited, few-nanometer-thin Ce2O3 film may very effectively be converted at room temperature to almost fully oxidized CeO2 by simple exposure to air, as demonstrated by hard X-ray photoemission spectroscopy and X-ray diffraction. This post-oxidation process essentially results in a negligible loss in film cryst...

  6. Radiative lifetimes of singly ionized cerium

    International Nuclear Information System (INIS)

    Radiative lifetimes accurate to ±5% have been measured for 74 levels in Ce II using time-resolved laser-induced fluorescence on a slow beam of cerium ions. The 17 odd-parity and 57 even-parity levels studied here lie in the energy range 24 000-36 000 cm-1. This new set of lifetimes in Ce II is substantially more extensive than previously published sets, to which a detailed comparison is made. The present lifetime results will provide the absolute calibration for a very large set of measured transition probabilities for Ce II. These are needed for research in astrophysics and lighting

  7. Radiative lifetimes of singly ionized cerium

    Energy Technology Data Exchange (ETDEWEB)

    Hartog, E A Den; Lawler, J E [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)], E-mail: eadenhar@wisc.edu, E-mail: jelawler@wisc.edu

    2008-02-28

    Radiative lifetimes accurate to {+-}5% have been measured for 74 levels in Ce II using time-resolved laser-induced fluorescence on a slow beam of cerium ions. The 17 odd-parity and 57 even-parity levels studied here lie in the energy range 24 000-36 000 cm{sup -1}. This new set of lifetimes in Ce II is substantially more extensive than previously published sets, to which a detailed comparison is made. The present lifetime results will provide the absolute calibration for a very large set of measured transition probabilities for Ce II. These are needed for research in astrophysics and lighting.

  8. Crystal structure of cerium(4) - dicesium trisulfate

    International Nuclear Information System (INIS)

    Cerium(4) - dicesium trisulfate is investigated by the X-ray diffraction method. Parameters of a monoclinic cell equal: a = 9.772(2), b = 16.797(2), c = 14.812(1)A, β 96.40(1), sp.gr. P21. The structure is formed by interchanging of anion [Ce4(SO4)128-]∞ and cation (Cs+) layers arranged parallel (101). Atoms Ce and Cs are arranged according to the law of a cubic close packing. Coordination polyhedron Ce1 and Ce2 is the two-hat trigonal prism, nine vertices Ce3 and Ce4 are one-hat antiprism

  9. Photodissociation of Cerium Oxide Nanocluster Cations.

    Science.gov (United States)

    Akin, S T; Ard, S G; Dye, B E; Schaefer, H F; Duncan, M A

    2016-04-21

    Cerium oxide cluster cations, CexOy(+), are produced via laser vaporization in a pulsed nozzle source and detected with time-of-flight mass spectrometry. The mass spectrum displays a strongly preferred oxide stoichiometry for each cluster with a specific number of metal atoms x, with x ≤ y. Specifically, the most prominent clusters correspond to the formula CeO(CeO2)n(+). The cluster cations are mass selected and photodissociated with a Nd:YAG laser at either 532 or 355 nm. The prominent clusters dissociate to produce smaller species also having a similar CeO(CeO2)n(+) formula, always with apparent leaving groups of (CeO2). The production of CeO(CeO2)n(+) from the dissociation of many cluster sizes establishes the relative stability of these clusters. Furthermore, the consistent loss of neutral CeO2 shows that the smallest neutral clusters adopt the same oxidation state (IV) as the most common form of bulk cerium oxide. Clusters with higher oxygen content than the CeO(CeO2)n(+) masses are present with much lower abundance. These species dissociate by the loss of O2, leaving surviving clusters with the CeO(CeO2)n(+) formula. Density functional theory calculations on these clusters suggest structures composed of stable CeO(CeO2)n(+) cores with excess oxygen bound to the surface as a superoxide unit (O2(-)). PMID:27035210

  10. Low soluble cerium compounds in salt melts

    International Nuclear Information System (INIS)

    The behaviour of cerium tungstate NaCe(WO4)2 and cerium phosphate Na3Ce2(PO4)3 in high-temperature salt melts has been investigated. The solubility in the NaCe(WO4)2-NaWO4-NaCl(1) and Na3Ce2(PO4)3-Na2WO4-NaCl(2) systems at 700-800 deg C has been studied. It is shown, that with the increase of the Na2WO4 part in systems (1), (2) the solubility increases in the following way: for NaCe(WO4)2 from 1.3x10-3 m in NaCl melt to 4.9x10-3 m in NaWO4 melt, for Na3Ce2(PO4)3 from 0.4x10-3 m in NaCl melt to 5.7x10-3 m in NaWO4 melt. With an increase in the Na2WO4 part in system (2) the formation of a new phase - NaCe(WO4)2 is observed. The melting enthalpy of NaCe(WO4)2 is 19+-3 kJ/mol

  11. Predeposition ultraviolet treatment for adhesion improvement of thin films on mercury cadmium telluride

    International Nuclear Information System (INIS)

    Poor film adhesion to mercury cadmium telluride is a problem of general concern because of the low film deposition temperatures (11 cm-2 and slow interface state densities of 4x1010 cm-2 were obtained at 100 K for aluminum nitiride/mercury cadmium telluride metal-insulator-semiconductor structures which had undergone the treatment

  12. Bordoni relaxation and magnetic transformation in cerium and cerium-lanthanum alloys

    International Nuclear Information System (INIS)

    The internal friction in pure cerium and cerium-base alloys with 2.5 and 12 weight percent of lanthanum added at temperature ranging from 4.2 deg up to 77 deg K is described. Amplitude-independent internal friction has been measured with an inverse torsion pendulum with a specimen oscillation frequency of 1-30 hz in vacuum not less than 1.10-5 torr. A temperature of the specimen has been determined with a capacitance-type sensor and a gas gauge. A curve showing the dependence of internal friction upon a temperature of pure cerium has two distinct peaks; the first at 12.5 deg K, the second at 45 deg K. The 12.5 deg K peak is accounted for by a transition of antiferromagnetic β-Ce into a paramagnetic state. The 45 deg K peak is a Bordoni maximum. The paper describes an influence of additions, specimen oscillation frequency variations, deformation and annealing upon the peak behaviour. Added lanthanum reduces not only a peak temperature but a height as well. Studies of the 45 deg K peak have shown that its temperature location depends upon the specimen oscillation frequency. As the frequency increases the peak tends to a range of high temperatures which confirms its relaxation nature

  13. Effect of FGMs on thermoelectric cooling properties of bismuth telluride

    International Nuclear Information System (INIS)

    Every thermoelectric material shows high performance at a specific narrow temperature range. The temperature range with high performance can be expanded by joining the materials with different peak temperature. This is the concept of an FGM. The FGMs for Peltier cooling materials have never been reported though the FGMs for thermoelectric power generation were reported to enhance conversion efficiency. Bismuth telluride is the best material for cooling devices at around room temperature. Then we investigated the thermoelectric cooling properties for bismuth telluride with two steps graded structure FGM. Two kinds of melt-grown materials of p-type bismuth telluride (hereafter, sample 1 and sample 2) were used. The samples 1 and 2 of 3 mm square x 2.5 mm were joined to form an FGM of 3 mm square x 5 mm in length by soldering with ultrasonic vibration. Thermoelectric cooling properties were evaluated by observing the maximum temperature drop to electric current when the high temperature side was kept constant. When the high temperature side is kept at 370 K, the temperature drop of the monolithic sample 1 was 34.6 K, and 39.7 K for sample 2, because of the difference of the carrier density. In the case of the FGM, the temperature drop was 45.2 K when the sample 1 was placed at the high temperature side. On the other hand, the temperature drop was only 27.6 K when the sample 2 was placed at the high temperature side. From these results, it is clear that high performance can be obtained by forming an FGM when the proper material arrangement is performed along the temperature gradient. (orig.)

  14. Preparing Process of Cerium Acetate and Rare Earth Acetate

    Institute of Scientific and Technical Information of China (English)

    Qiao Jun; Ma Ying; Xu Yanhui; Zhang Jun; Chang Shu; Hao Xianku

    2004-01-01

    Preparing process was presented and the influences of concentration of acetic acid, reaction temperature, the ratio of cerium carbonate and acetic acid, heat preservation time to the yield of cerium acetate were discussed.The crystalline cerium acetate and rare earth acetate such as ( La, Ce, Pr, Nd) (Ac) 3, ( Ce, Pr, Nd) (Ac) 3, ( Pr, Nd, Er,Y) (Ac) 3 and yttrium acetate were prepared under this condition.The shape, structure and composition of the crystals were determined by the methods of SEM, TG-DTA, X-ray diffraction and chemical analysis.The optimum prepared conditions of cerium acetate were described.This prepared process has characteristics such as simple process route, low cost, high yield, good quality, no pollution to environment, etc.

  15. Adsorption of Some Hazardous Radionuclides on Cerium(IV) Antimonate

    International Nuclear Information System (INIS)

    Cerium(IV) antimonate had been prepared by the dropwise addition of 0.6 M antimony pentachloride and 0.6 M cerium ammonium nitrate solutions by a molar radio of Ce/Sb 0.75. Exchange isotherms for H+/Co2+ , H+/Cs+, H+/Zn2+ , H+/Sr2+ and H+/Eu3+ have been determined at 25, 40 and 60 degree. Besides it was proved that europium is physically adsorbed while zinc, strontium, cobalt and cesium are chemically adsorbed. Moreover, the heat of adsorption of zinc, strontium, cobalt and cesium on cerium(IV) antimonate had been calculated and indicated that cerium(IV) antimonate is of endothermic behaviour towards these ions. Also the distribution coefficients of these ions were determined and it was found that the selectivity in the order: Eu3+ >Sr2+ > Cs+>Na+

  16. A contribution to the radiologic findings in cerium pneumoconiosis

    International Nuclear Information System (INIS)

    Report on a 69 year old man, who had been employed as photographer in the printing industry and who had been exposed to Cerium for 40 years. The chest X-ray which was performed 9 years after the end of the exposure displayes striate densities of the lungs, which must be considered as a late stage of Cerium-pneumoconiosis. The changes which were found fulfill the code 't 1/0 RO, RM, RU, LO, LM, LU, p 0/1 RO, RM, LO, LM, em, tbu' according to the 'ILO U/C 1971 classification of pneumoconiosis'. The diagnosis could be substantiated by measureing Cerium in the lung parenchyma qualitatively and quantitatively using neutrone activating analysis. The radiolgic findings of the Cerium pneumoconiosis are discussed. (orig.)

  17. Hopping conduction in evaporated cadmium telluride thin films

    International Nuclear Information System (INIS)

    Hopping conduction was observed in cadmium telluride thin films. At low temperature there is insufficient energy to excite electrons into the conduction band hence the dominant conduction mechanism is probably hopping. The activation energy ΔE, was found to be approximately 0.05 eV (thickness=400nm) and 0.08 eV (thickness=267nm). As the temperature was increased activation energy more widely spread levels became possible until kt∼0.4 eV, when free conduction was dominant

  18. The photocorrosion of n-cadmium telluride and its suppression

    Science.gov (United States)

    Curran, J. S.

    1980-09-01

    The photoelectrochemical properties of n-type cadmium telluride were studied in water and five other organic solvents, with a view to suppression of the photocorrosion reaction which prevents this and other n-type small bandgap semiconductors from being used in a practical semiconductor-electrolyte junction solar cell. Only the low donicity organic solvents propylene carbonate and methyl nitrate reduce the corrosion rate significantly. A stable photocurrent can be obtained using a solution of ferrocene in these two solvents but analysis of photoelectrolyzed solutions revealed a slow photocorrosion. The dependence of the flatband potential and of the practical significance with respect to solar cell applications considered.

  19. Study of rectification at the metal-cadmium telluride contact

    International Nuclear Information System (INIS)

    The barrier heights at the contact between metals and N or P type cadmium telluride have been determined. Various surface treatments have been used for the semiconductor: lapping, polishing and etching in a bromine in methanol solution. Depending on these preparation differences of about 0.1 eV have been observed for the barrier height which in any case was no more than 0.9 - 1.0 eV. These results can not be explained by only considering the Schottky theory of rectification

  20. An evaluation of cadmium telluride detectors for computer assisted tomography.

    Science.gov (United States)

    Chu, D; Kaufman, L; Hosier, K; Hoenninger, J

    1978-11-01

    Cadmium telluride (CdTe) presents a set of extremely attractive features as an X-ray detector for computer assisted tomography (CAT). It is stable and easily handled; has a high detection efficiency and very efficient conversion of energy to charge; and permits a high element density in a compact configuration. Unfortunately, effects due to "polarization," "tailing," high and variable leakage currents, and long "memory" are incompatible with the needs of CAT instrumentation. Pulse-processing techniques have allowed us to eliminate these problems in positive-sensitive detectors, thus opening the way for utilization of CdTe in CAT. PMID:711945

  1. Surface Passivation of Mercury-Cadmium-Telluride Infrared Detectors

    Directory of Open Access Journals (Sweden)

    R. Singh

    1991-07-01

    Full Text Available The theoretical considerations and practical aspects of passivating insulator films, in the context of their use on high-performance mercury cadmium telluride (MCT infrared detectors are reviewed. The methods of growth, the interface properties and the applications of both native and deposited passivant films have been discussed. Native films include anodic, chemical, photochemical, and plasma oxides as well as anodic sulphides and fluoro-oxides. Deposited films include ZnS, photo-CVD-grown SiO2, CDTe, and SiN/sub x/. The properties of all these passivant films on MCT have been summarized.

  2. Antibacterial Activity of Polymer Coated Cerium Oxide Nanoparticles

    OpenAIRE

    Shah, Vishal; Shah, Shreya; Shah, Hirsh; Rispoli, Fred J.; McDonnell, Kevin T.; Workeneh, Selam; Karakoti, Ajay; Kumar, Amit; Seal, Sudipta

    2012-01-01

    Cerium oxide nanoparticles have found numerous applications in the biomedical industry due to their strong antioxidant properties. In the current study, we report the influence of nine different physical and chemical parameters: pH, aeration and, concentrations of MgSO4, CaCl2, KCl, natural organic matter, fructose, nanoparticles and Escherichia coli, on the antibacterial activity of dextran coated cerium oxide nanoparticles. A least-squares quadratic regression model was developed to underst...

  3. Cerium intermetallics CeTX. Review III

    International Nuclear Information System (INIS)

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

  4. Cerium fluoride crystals for calorimetry at LHC

    International Nuclear Information System (INIS)

    High-resolution homogeneous calorimetry is fully justified for part of the physics program at the Large Hadron Collider (LHC). The main design features of proposed CeF3 crystals for calorimetry for LHC are discussed. The severe constraints LHC imposes on detectors make the use of 'classical' crystals impossible. Therefore, a large R and D effort has been undertaken by the 'Crystal Clear' collaboration in order to find new, dense, fast and radiation hard crystals. A good candidate, cerium fluoride, has been identified and studied. It is interesting at this stage to review the specifications of scintillators for LHC and to see how well available data on CeF3 luminescence, decay time, light yield, optical transmission and resistance to radiation meet them. Milestones to reach before starting a large scale crystal production in view of the eventual construction of a calorimeter, are also discussed. (author) 15 refs., 15 figs., 1 tab

  5. Further results on cerium fluoride crystals

    International Nuclear Information System (INIS)

    A systematic investigation of the properties of cerium fluoride monocrystals has been performed by the 'Crystal Clear' collaboration in view of a possible use of such crystals for the construction of high precision electromagnetic calorimeters for the future generation of high luminosity accelerators. A large sample of different crystals grown by several producers has been studied. The spectroscopic characteristics, the transmission, luminescence and excitation spectra and the decay time curves are analysed. The light yield of the different crystals is measured with photomultipliers and Si photodiodes and compared to reference standards like BGO and NaI(Tl). The radiation damage behaviour is then presented for γ and neutron irradiations, at different doses and dose rates, including thermal and optical bleaching. (orig.)

  6. Further results on cerium fluoride crystals

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S.; Auffray, E.; Aziz, T.; Baccaro, S.; Banerjee, S.; Bareyre, P.; Barone, L.E.; Borgia, B.; Boutet, D.; Burq, J.P.; Chemarin, M.; Chipaux, R.; Dafinei, I.; D' Atanasio, P.; De Notaristefani, F.; Dezillie, B.; Dujardin, C.; Dutta, S.; Faure, J.L.; Fay, J.; Ferrere, D.; Francescangeli, O.; Fuchs, B.A.; Ganguli, S.N.; Gillespie, G.; Goyot, M.; Gupta, S.K.; Gurtu, A.; Heck, J.; Herve, A.; Hillemanns, H.; Holdener, F.; Ille, B.; Joensson, L.; Kierstead, J.; Krenz, W.; Kway, W.; Le Goff, J.M.; Lebeau, M.; Lebrun, P.; Lecoq, P.; Lemoigne, Y.; Loomis, G.; Lubelsmeyer, K.; Madjar, N.; Majni, G.; El Mamouni, H.; Mangla, S.; Mares, J.A.; Martin, J.P.; Mattioli, M.; Mauger, G.J.; Mazumdar, K.; Mengucci, P.; Merlo, J.P.; Moine, B.; Nikl, N.; Pansart, J.P.; Pedrini, C.; Poinsignon, J.; Polak, K.; Raghavan, R.; Rebourgeard, P.; Rinaldi, D.; Rosa, J.; Rosowsky, A.; Sahuc, P.; Samsonov, V.; Sarkar, S.; Schegelski, V.; Schmitz, D.; Schneegans, M.; Seliverstov, D.; Stoll, S.; Sudhakar, K.; Sven; Crystal Clear Collaboration

    1993-08-15

    A systematic investigation of the properties of cerium fluoride monocrystals has been performed by the 'Crystal Clear' collaboration in view of a possible use of such crystals for the construction of high precision electromagnetic calorimeters for the future generation of high luminosity accelerators. A large sample of different crystals grown by several producers has been studied. The spectroscopic characteristics, the transmission, luminescence and excitation spectra and the decay time curves are analysed. The light yield of the different crystals is measured with photomultipliers and Si photodiodes and compared to reference standards like BGO and NaI(Tl). The radiation damage behaviour is then presented for [gamma] and neutron irradiations, at different doses and dose rates, including thermal and optical bleaching. (orig.)

  7. Mechanical and Thermophysical Properties of Cerium Monopnictides

    Science.gov (United States)

    Bhalla, Vyoma; Singh, Devraj; Jain, S. K.

    2016-03-01

    The ultrasonic attenuation due to phonon-phonon interaction, thermoelastic relaxation and dislocation damping mechanisms has been investigated in cerium monopnictides CeX (X: N, P, As, Sb and Bi) for longitudinal and shear waves along {linearity parameters, Zener anisotropy, ultrasonic velocity, ultrasonic Grüneisen parameter, thermal relaxation time, acoustic coupling constants and ultrasonic attenuation. The fracture/toughness ratio is less than 1.75, which shows that the chosen materials are brittle in nature as found for other monopnictides. The drag coefficient acting on the motion of screw and edge dislocations due to shear and compressional phonon viscosities of the lattice have also been evaluated for both the longitudinal and shear waves. The thermoelastic loss and dislocation damping loss are negligible in comparison to loss due to Akhieser damping (phonon-phonon interaction). The obtained results for CeX are in qualitative agreement with other semi-metallic monopnictides.

  8. Cerium intermetallics CeTX. Review III

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-01

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

  9. Comparison of Titration ICP and XRF Spectrometry Methods in Determination of Cerium in Lens Polishing Powder

    International Nuclear Information System (INIS)

    Three analytical methods in determination of cerium in cerium oxide separated from monazite ore for producing lens polishing powder were compared. These methods are titration ICP and XRF spectrometry techniques. The cerium oxide sample with estimated 45% cerium content needed to be digested and converted into solution before the analysis. The analytical results shown significantly no difference between each method. However, the titration method was found to be more convenient and suitable for quality control in the production of cerium oxide as it does not require standard cerium and the complicated analytical instruments

  10. The study and development of cadmium telluride detectors for gamma ray spectrometry

    International Nuclear Information System (INIS)

    The purpose of this work is the study of possibility of cadmium telluride's utilisation in gamma ray spectroscopy. This material has some superiorities in comparison with germanium which is utilised in (Ge Li) structures. In a first chapter we study the interaction of rays with matter in the particular case of cadmium telluride. The range of α and β rays in the some way as the effect cross section of gamma ray versus energy are deducted from data tabulated for tin which has a density and an atomic weight very near. The problems related with creation and collection of charges in a cadmium telluride structure are discussed in the same way as the resolution in nuclear spectroscopy, acting the different parameters characterising the detector. In the second chapter, after some indications in the metallurgy of cadmium telluride, we describe the realisation of several structures types, evaporation of a cadmium telluride's layer, diffusion of gold or copper, metal semiconductor contact. Measures of current-voltage characteristics and capacity allow the determination of possibility of nuclear detection with this structures and state precisely some parameters. In the third chapter range's measures of α rays are compared with the first chapter's theoretical results. Results of α ray spectroscopy obtained with three detectors are described and show the possibility of cadmium telluride in this way. Detection of gamma ray at last justify the choice of this material, but the results obtained here show the progress to do in cadmium telluride metallurgy. (author)

  11. Kelvin probe studies of cesium telluride photocathode for AWA photoinjector

    International Nuclear Information System (INIS)

    Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for a new Argonne Wakefield Accelerator (AWA) beamline to produce high charge per bunch (≈50nC) in a long bunch train. Here, we present a study of the work function of cesium telluride photocathode using the Kelvin probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the effect of UV exposure on the work function, and the evolution of the work function during and after photocathode rejuvenation via heating. -- Highlights: ► The correlation between Quantum Efficiency (QE) and work function. ► How QE and work function evolve together. ► Rejuvenation of the photocathode via heating and the effect on work function. ► The effects on the work function due to exposure to UV light

  12. TOP as ligand and solvent to synthesize silver telluride nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shutang, E-mail: shutang.chen@uconn.edu [Division of Energy Systems Research, Ajou University, Suwon 443-749 (Korea, Republic of); Department of Chemistry, University of Connecticut, Storrs 06269 (United States); Lee, Soonil, E-mail: soonil@ajou.ac.kr [Division of Energy Systems Research, Ajou University, Suwon 443-749 (Korea, Republic of)

    2015-11-15

    Highlights: • Silver telluride nanosheets were prepared through one-pot synthetic strategy. • TOP as both ligand and solvent favors silver telluride nanosheets growth. • The I–V curve of an Ag{sub 2}Te-nanosheet film indicates that as-prepared Ag{sub 2}Te nanosheets have good electric conductivity. - Abstract: Ag{sub 2}Te nanosheets are synthesized by a simple one-pot route using trioctylphosphine (TOP) as both solvent and stabilizer. Various controlling parameters were examined, such as molar ratios of AgNO{sub 3} to tellurium powder, reaction temperature and time, and precursor concentration. The morphology and composition of the products were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. On the basis of a series of synthesis and characterizations, the formation mechanism of the Ag{sub 2}Te nanosheets are discussed. The I–V curve of an Ag{sub 2}Te-nan osheet film indicates that as-prepared Ag{sub 2}Te nanosheets have good electric conductivity.

  13. Kelvin probe studies of cesium telluride photocathode for AWA photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Wisniewski, Eric E., E-mail: ewisniew@anl.gov [High Energy Physics Division, Argonne National Laboratory, 9700 S. Cass, Lemont, IL 60439 (United States); Physics Department, Illinois Institute of Technology, 3300 South Federal Street, Chicago, IL 60616 (United States); Velazquez, Daniel [High Energy Physics Division, Argonne National Laboratory, 9700 S. Cass, Lemont, IL 60439 (United States); Physics Department, Illinois Institute of Technology, 3300 South Federal Street, Chicago, IL 60616 (United States); Yusof, Zikri, E-mail: zyusof@hawk.iit.edu [High Energy Physics Division, Argonne National Laboratory, 9700 S. Cass, Lemont, IL 60439 (United States); Physics Department, Illinois Institute of Technology, 3300 South Federal Street, Chicago, IL 60616 (United States); Spentzouris, Linda; Terry, Jeff [Physics Department, Illinois Institute of Technology, 3300 South Federal Street, Chicago, IL 60616 (United States); Sarkar, Tapash J. [Rice University, 6100 Main, Houston, TX 77005 (United States); Harkay, Katherine [Accelerator Science Division, Argonne National Laboratory, 9700 S. Cass, Lemont, IL 60439 (United States)

    2013-05-21

    Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for a new Argonne Wakefield Accelerator (AWA) beamline to produce high charge per bunch (≈50nC) in a long bunch train. Here, we present a study of the work function of cesium telluride photocathode using the Kelvin probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the effect of UV exposure on the work function, and the evolution of the work function during and after photocathode rejuvenation via heating. -- Highlights: ► The correlation between Quantum Efficiency (QE) and work function. ► How QE and work function evolve together. ► Rejuvenation of the photocathode via heating and the effect on work function. ► The effects on the work function due to exposure to UV light.

  14. Superconductivity in oxygen doped iron telluride by molecular beam epitaxy

    Science.gov (United States)

    Zheng, Mao

    Iron base superconductor have gained much attention in the research community. They offer great potentials to improve our understanding of the subject of superconductivity by having another family of high temperature superconductors to compare and contrast to the cuprates. Practically, the iron based superconductors seems to be even better candidates for applications in power generation and power transmission. Iron telluride is regarded as the parent compound of the "11" family, the family of iron chalcogenide that has the simplest structure. Iron telluride itself is not a superconductor, by can become one when doped with oxygen. In this investigation, we developed the growth recipe of thin film iron telluride by Molecular Beam Epitaxy (MBE). We found the growth to be self-regulated, similar to that of GaAs. The initial layers of growth seem to experience a spontaneous crystallization, as the film quickly go from the initial polycrystalline phase to highly crystalline in just a few unit cells. We studied oxygen doping to the iron telluride thin films and the resultant superconductivity. We characterized the sample with AFM, XRD, transport, and STEM-EELS, and we found that interfacial strain is not an essential ingredient of superconductivity in this particular case. We investigated the doping conditions for two candidate oxygen doping modes: substitution and interstitial. We found that substitution occurs when the film grown in oxygen, while interstitial oxygen is primarily incorporated during annealing after growth. The substitutional oxygen are concentrated in small local regions where substitution is around 100%, but does not contribute to superconductivity. We estimated substitutional oxygen to be about 5%, and is the proximate cause of superconductivity. Hall experiment on our sample showed a shift of dominant carrier type from holes to electrons around 35 K, but the transition was set in motion as early as the structural phase transition around 70 K. We

  15. Abnormal physics of group-II telluride system:valence contribution of d electrons

    Institute of Scientific and Technical Information of China (English)

    Duan He; Dong You-Zhong; Huang Yan; Chen Xiao-Shuang

    2011-01-01

    The physical trend of group-II tellurides is unexpected and contrary to the conventional wisdom. The present firstprinciples calculations give fundamental insights into the extent to which group-II telluride compounds present special properties upon mixing the d valence character.Our results provide explanations for the unexpected experimental observations based on the abnormal binding ordering of metal d electrons and their strong perturbation to the band edge states. The insights into the binary tellurides are useful for the study and control of the structural and chemical perturbation in their ternary alloys and heterostructures.

  16. Effect of metallic coatings on thermoelectric properties of lead telluride films

    International Nuclear Information System (INIS)

    Effect of sprayed coatings of different metals on thermoelectric properties of lead telluride films was investigated. The basic films were prepared by the method of vacuum thermal evaporation of sample of stoichiometric lead telluride at 5x10-4 Pa residual pressure on mica (muscovite) sublayer at 330-350 deg C and approximately 10 nm/s deposition rate. It was established that fine coatings of copper, silver and gold modify sufficiently electric properties of lead telluride films. The effect is conditioned mainly by decoration and electric shunting of grain boundaries by metal island, which removes the contribution of grain boundaries to film electric conductivity

  17. Inhibition of pH fronts in corrosion cells due to the formation of cerium hydroxide

    NARCIS (Netherlands)

    Soestbergen, M. van; Erich, S.J.F.; Huinink, H.P.; Adan, O.C.G.

    2013-01-01

    The effect of cerium-based corrosion inhibitors on the pH front between the alkaline cathode and acidic anode in corrosion cells has been studied. The cerium component of these inhibitors can affect the pH front since it precipitates in an alkaline environment as cerium hydroxide, which is important

  18. Cerium as a Surrogate in the Plutonium Immobilized Form

    International Nuclear Information System (INIS)

    The Department of Energy (DOE) plans to immobilize a portion of the excess weapons useable plutonium in a ceramic form for final geologic disposal. The proposed immobilization form is a titanate based ceramic consisting primarily of a pyrochlore phase with lesser amounts of brannerite, rutile, zirconolite, vitreous phases and/or other minor phases depending on the impurities present in the feed. The ceramic formulation is cold-pressed and then densified via a reactive sintering process. Cerium has been used as a surrogate for plutonium to facilitate formulation development and process testing. The use of cerium vs. plutonium results in differences in behavior during sintering of the ceramic form. The phase development progression and final phase assemblage is different when cerium is substituted for the actinides in the form. However, the physical behavior of cerium oxide powder and the formation of a pyrochlore-rich ceramic of similar density to the actinide-bearing material make cerium an adequate surrogate for formulation and process development studies

  19. Electrodeposited cerium film as chromate replacement for tinplate

    International Nuclear Information System (INIS)

    The cerium film was prepared on tinplate by electrodeposition method. Sulfide-stain resistance of the Ce-passivated, unpassivated and Cr-passivated tinplates was evaluated using a cysteine tarnish test. Corrosion behavior of these tinplates in contact with 3.5% NaCl solution and 0.1 M citric-citrate buffer solution was investigated using Tafel measurement and electrochemical impedance spectroscopy measurement, respectively. The adhesion of epoxyphenolic lacquer to the Ce-passivated tinplate was checked using a cross hatch cutter. The morphology, composition and thickness of the cerium film were studied by atomic force microscopy, X-ray photoelectron spectroscopy and X-ray fluorescence spectrometry. According to the results, the Ce-passivated tinplate shows the best sulfide-stain resistance and the best corrosion protection property compared with the unpassivated and Cr-passivated tinplates. The adhesion of epoxyphenolic lacquer to the Ce-passivated tinplate is good. The cerium film is composed of the closely packed particles of about 50-200 nm in diameter. The film mainly consists of cerium and oxygen, which mainly exist as CeO2, Ce2O3 and their hydrates such as Ce(OH)4, Ce(OH)3. The total cerium amount of the film is about 0.110 g/m2

  20. Potential for recovery of cerium contained in automotive catalytic converters

    Science.gov (United States)

    Bleiwas, Donald I.

    2013-01-01

    Catalytic converters (CATCONs) are required by Federal law to be installed in nearly all gasoline- and diesel-fueled onroad vehicles used in the United States. About 85 percent of the light-duty vehicles and trucks manufactured worldwide are equipped with CATCONs. Portions of the CATCONs (called monoliths) are recycled for their platinum-group metal (PGM) content and for the value of the stainless steel they contain. The cerium contained in the monoliths, however, is disposed of along with the slag produced from the recycling process. Although there is some smelter capacity in the United States to treat the monoliths in order to recover the PGMs, a great percentage of monoliths is exported to Europe and South Africa for recycling, and a lesser amount is exported to Japan. There is presently no commercial-scale capacity in place domestically to recover cerium from the monoliths. Recycling of cerium or cerium compounds from the monoliths could help ensure against possible global supply shortages by increasing the amount that is available in the supply chain as well as the number and geographic distribution of the suppliers. It could also reduce the amount of material that goes into landfills. Also, the additional supply could lower the price of the commodity. This report analyzes how much cerium oxide is contained in CATCONs and how much could be recovered from used CATCONs.

  1. Megapixel mercury cadmium telluride focal plane arrays for infrared imaging out to 12 microns Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose the fabrication of large format, long wave infrared (LWIR) mercury cadmium telluride (HgCdTe or MCT) detector arrays where the cutoff wavelength is...

  2. Characterization of cerium fluoride nanocomposite scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Stange, Sy [Los Alamos National Laboratory; Esch, Ernst I [Los Alamos National Laboratory; Brown, Leif O [Los Alamos National Laboratory; Couture, Aaron J [Los Alamos National Laboratory; Mckigney, Edward A [Los Alamos National Laboratory; Muenchausen, Ross E [Los Alamos National Laboratory; Del Sesto, Rico E [Los Alamos National Laboratory; Gilbertson, Robert D [Los Alamos National Laboratory; Mccleskey, T Mark [Los Alamos National Laboratory; Reifarth, Rene [Los Alamos National Laboratory

    2009-01-01

    Measurement of the neutron capture cross-sections of a number of short-lived isotopes would advance both pure and applied scientific research. These cross-sections are needed for calculation of criticality and waste production estimates for the Advanced Fuel Cycle Initiative, for analysis of data from nuclear weapons tests, and to improve understanding of nucleosynthesis. However, measurement of these cross-sections would require a detector with a faster signal decay time than those used in existing neutron capture experiments. Crystals of faster detector materials are not available in sufficient sizes and quantities to supply these large-scale experiments. Instead, we propose to use nanocomposite detectors, consisting of nanoscale particles of a scintillating material dispersed in a matrix material. We have successfully fabricated cerium fluoride (CeF{sub 3}) nanoparticles and dispersed them in a liquid matrix. We have characterized this scintillator and have measured its response to neutron capture. Results of the optical, structural, and radiation characterization will be presented.

  3. Characterization of cerium fluoride nanocomposite scintillators

    International Nuclear Information System (INIS)

    Measurement of the neutron capture cross-sections of a number of short-lived isotopes would advance both pure and applied scientific research. These cross-sections are needed for calculation of criticality and waste production estimates for the Advanced Fuel Cycle Initiative, for analysis of data from nuclear weapons tests, and to improve understanding of nucleosynthesis. However, measurement of these cross-sections would require a detector with a faster signal decay time than those used in existing neutron capture experiments. Crystals of faster detector materials are not available in sufficient sizes and quantities to supply these large-scale experiments. Instead, we propose to use nanocomposite detectors, consisting of nanoscale particles of a scintillating material dispersed in a matrix material. We have successfully fabricated cerium fluoride (CeF3) nanoparticles and dispersed them in a liquid matrix. We have characterized this scintillator and have measured its response to neutron capture. Results of the optical, structural, and radiation characterization will be presented.

  4. Stabilized zirconia with cerium and neodymium addition

    International Nuclear Information System (INIS)

    Zr0,9 Ce0,05 Nd0,05 O1,975 system was synthesized with the use of the Pechini method. The polymeric resin was calcined at 350 deg C/3 h and analysed by FTIR that show bands relative to organic. Radicals esther type. The TGA curve indicated the polymeric decomposition occurring from 30 deg C to 740 deg C. DTA analysis show a exothermic peak in 100 deg C due to loss of water of material. From 500 deg C to 800 deg C was observed a intense peak due to polymer decomposition and the zirconia crystallization. The calcined powder from 350 deg C/3 h e 30 min to 900 deg/3 h were analysed by XRD that show the crystalline phase formation with the increase of temperature. The X-ray diffraction pattern show the presence of two phases, such as tetragonal and cubic of zirconia demonstrating that neodymium and cerium additions led to zirconia stabilization. (author)

  5. Cerium Dioxide Thin Films Using Spin Coating

    Directory of Open Access Journals (Sweden)

    D. Channei

    2013-01-01

    Full Text Available Cerium dioxide (CeO2 thin films with varying Ce concentrations (0.1 to 0.9 M, metal basis were deposited on soda-lime-silica glass substrates using spin coating. It was found that all films exhibited the cubic fluorite structure after annealing at 500°C for 5 h. The laser Raman microspectroscopy and GAXRD analyses revealed that increasing concentrations of Ce resulted in an increase in the degree of crystallinity. FIB and FESEM images confirmed the laser Raman and GAXRD analyses results owing to the predicted increase in film thickness with increasing Ce concentration. However, porosity and shrinkage (drying cracking of the films also increased significantly with increasing Ce concentrations. UV-VIS spectrophotometry data showed that the transmission of the films decreased with increasing Ce concentrations due to the increasing crack formation. Furthermore, a red shift was observed with increasing Ce concentrations, which resulted in a decrease in the optical indirect band gap.

  6. Chlorination and Carbochlorination of Cerium Oxide

    International Nuclear Information System (INIS)

    The chlorination and carbochlorination of cerium oxide were studied by thermogravimetry under controlled atmosphere (TG) in the 7000C 9500C temperature range.Both reactants and products were analyzed by X-ray diffraction (RX), scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS). Thermodynamic calculations were performed by computer assisted software.The chlorination starts at a temperature close to 8000C.This reaction involves the simultaneous formation and evaporation of CeCl3.Both processes control the reaction rate and their kinetic may not be easily separated.The apparent chlorination activation energy in the 8500C-9500C temperature range is 172 to 5 kJ/ mole.Carbon transforms the CeO2-Cl2 into a more reactive system: CeO2-C-Cl2, where the effects of the carbon content, total flow rate and temperature were analyzed.The carbochlorination starting temperature is 7000C.This reaction is completed in one step controlled by mass transfer with an apparent activation energy of 56 to 5 kJ/mole in the 8500C-9500C temperature range

  7. Environmental Geochemistry of Cerium: Applications and Toxicology of Cerium Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Jessica T. Dahle

    2015-01-01

    Full Text Available Cerium is the most abundant of rare-earth metals found in the Earth’s crust. Several Ce-carbonate, -phosphate, -silicate, and -(hydroxide minerals have been historically mined and processed for pharmaceutical uses and industrial applications. Of all Ce minerals, cerium dioxide has received much attention in the global nanotechnology market due to their useful applications for catalysts, fuel cells, and fuel additives. A recent mass flow modeling study predicted that a major source of CeO2 nanoparticles from industrial processing plants (e.g., electronics and optics manufactures is likely to reach the terrestrial environment such as landfills and soils. The environmental fate of CeO2 nanoparticles is highly dependent on its physcochemical properties in low temperature geochemical environment. Though there are needs in improving the analytical method in detecting/quantifying CeO2 nanoparticles in different environmental media, it is clear that aquatic and terrestrial organisms have been exposed to CeO2 NPs, potentially yielding in negative impact on human and ecosystem health. Interestingly, there has been contradicting reports about the toxicological effects of CeO2 nanoparticles, acting as either an antioxidant or reactive oxygen species production-inducing agent. This poses a challenge in future regulations for the CeO2 nanoparticle application and the risk assessment in the environment.

  8. Cerium luminescence in borate glass and effect of aluminium on blue green emission of cerium ions

    International Nuclear Information System (INIS)

    CeO2 doped lead borate (CE) and lead alumino borate (CEA) glasses are prepared by melt quench method at high temperature. The main luminescence band of 5d–4f transition of Ce3+ ions with maxima at around 489 nm of Ce3+ ions in these glasses has been observed, along with red shift and larger stokes shift, which shows that the covalency of the rare earth to oxygen bond increases with the increase in CeO2 content at the expense of Al2O3. Shifting of UV absorption edge towards longer wavelength and a decrease in band gap with increase in CeO2 concentration in both the glass systems has been observed. Moreover densification and stabilization of glass network has been observed which is due to conversion of BO3 units to more compact and stable BO4 units. This covalency effect and the formation of BO4 groups with addition of CeO2 and incorporation of Al2O3 content are responsible for clear effect on luminescence of the present glass system. Moreover the optical basicity values were theoretically determined along with density and molar volume. -- Highlights: • Aluminium incorporation assists in dispersing the clusters of cerium ions and thus enhancing luminescence response. • Decrease of optical band gap energy with an increase of cerium concentration shows the semiconducting behavior. • Larger stokes shift shows that the covalency of rare earth to oxygen bond increases with increase in CeO2

  9. Cerium, manganese and cerium/manganese ceramic monolithic catalysts. Study of VOCs and PM removal

    Institute of Scientific and Technical Information of China (English)

    COLMAN-LERNER Esteban; PELUSO Miguel Andrs; SAMBETH Jorge; THOMAS Horacio

    2016-01-01

    Ceramic supported cerium, manganese and cerium-manganese catalysts were prepared by direct impregnation of aqueous precursor, and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller method (BET), temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) acidity measurements and electrical conductivity. The catalytic activity was evaluated for volatile organic compounds (VOC) (ethanol, methyl ethyl ketone and toluene) oxidation. Additionally, catalysts were tested in particulate matter (PM) combustion. The characterization results indicated that Ce was in the form of Ce4+ and Ce3+, and Mn existed in the form of Mn4+and Mn3+on the surface of the Mn/AC sample and in the form of Mn4+ in the Ce/Mn/AC monolith. VOC oxidation results revealed that the Ce/Mn/AC sample showed an excellent performance compared with ceramic supported CeO2 (Ce/AC) and MnOx (Mn/AC) samples. The PM combustion was also higher on Ce/Mn/AC monoliths. The enhanced catalytic activity was mainly attributed to the Ce and Mn interaction which enhanced the acidity, conductiv-ity and the reducibility of the oxides.

  10. Ion implantation of erbium into polycrystalline cadmium telluride

    International Nuclear Information System (INIS)

    The specific features of the ion implantation of polycrystalline cadmium telluride with grains 20–1000 μm in dimensions are studied. The choice of erbium is motivated by the possibility of using rare-earth elements as luminescent “probes” in studies of the defect and impurity composition of materials and modification of the composition by various technological treatments. From the microphotoluminescence data, it is found that, with decreasing crystal-grain dimensions, the degree of radiation stability of the material is increased. Microphotoluminescence topography of the samples shows the efficiency of the rare-earth probe in detecting regions with higher impurity and defect concentrations, including regions of intergrain boundaries

  11. Study of oxide films on the surface of cadmium telluride

    International Nuclear Information System (INIS)

    Study of oxide films on surfaces of CdTe monocrystals is continued by methods of ellipsometry and by absorption in IR-spectral range. Index values of refruction of oxide films, produced by cadmium telluride oxidation in hydrogen peroxide solutions, in oxigen flow at 673 K and by anode oxidation, as a rule, differ essentially in dependence on method of production, that gives evidence of differences in these films composition. Oxide films, produced in oxygen flow, as opposed to films, produced by two other methods, have intensive absorption, characteristic for tellurite group. Film thickness, produced by oxidation in hydrogen peroxide and in oxygen flow, varies within rather wide limits with observance of externally similar conditions of production. By contrast to it, thickness of anode films is regulated reliably by anode potential

  12. Mercury Cadmium Telluride Photoconductive Long Wave Infrared Linear Array Detectors

    Directory of Open Access Journals (Sweden)

    Risal Singh

    2003-07-01

    Full Text Available Mercury cadmium telluride (Hg1-x, CdxTe (MCT photoconductive long wave infrared linear arrays are still in demand due to several advantages. The linear array technology is well established, easier, economical and is quite relevant to thermal imaging even today. The scan thermal imaging systems based on this technology offer wider field of view coverage and capacity for higher resolution in the scan direction relative to staring systems that use expensive and yet to mature focal plane array detector technology. A critical review on photoconductive n-Hg1-x CdxTe linear array detector technology for the long wave infrared range has been presented. The emphasis lies on detector design and processing technology. The critical issues of diffusion and drift effects, Hi-Lo and heterostructure blocking contacts, surface passivation, and other related aspects have been considered from the detector design angle. The device processing technology aspects are of vital importance

  13. Optical properties of thermally evaporated cadmium telluride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Khairnar, U.P.; Bhavsar, D.S.; Vaidya, R.U.; Bhavsar, G.P

    2003-05-26

    Polycrystalline CdTe films have been deposited onto glass substrates at 373 K by vacuum evaporation technique. The transmittance and reflectance have been measured at normal and near normal incidence, respectively, in the spectral range 200-2500 nm. The dependence of absorption coefficient, {alpha} on the photon energy have been determined. Analysis of the result showed that for CdTe films of different thicknesses, direct transition occurs with band gap energies in the range 1.45-1.52 eV. Refractive indices and extinction coefficients have been evaluated in the above spectral range. The XRD analysis confirmed that CdTe films are polycrystalline having hexagonal structure. The lattice parameters of thin films are almost matching with the JCPDS 82-0474 data for cadmium telluride.

  14. Study on thermal annealing of cadmium zinc telluride (CZT) crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yang, G.; Bolotnikov, A.E.; Fochuk, P.M.; Camarda, G.S.; Cui, Y.; Hossain, A.; Kim, K.; Horace, J.; McCall, B.; Gul, R.; Xu, L.; Kopach, O.V.; and James, R.B.

    2010-08-01

    Cadmium Zinc Telluride (CZT) has attracted increasing interest with its promising potential as a room-temperature nuclear-radiation-detector material. However, different defects in CZT crystals, especially Te inclusions and dislocations, can degrade the performance of CZT detectors. Post-growth annealing is a good approach potentially to eliminate the deleterious influence of these defects. At Brookhaven National Laboratory (BNL), we built up different facilities for investigating post-growth annealing of CZT. Here, we report our latest experimental results. Cd-vapor annealing reduces the density of Te inclusions, while large temperature gradient promotes the migration of small-size Te inclusions. Simultaneously, the annealing lowers the density of dislocations. However, only-Cd-vapor annealing decreases the resistivity, possibly reflecting the introduction of extra Cd in the lattice. Subsequent Te-vapor annealing is needed to ensure the recovery of the resistivity after removing the Te inclusions.

  15. Process dependent thermoelectric properties of EDTA assisted bismuth telluride

    Science.gov (United States)

    Kulsi, Chiranjit; Kargupta, Kajari; Banerjee, Dipali

    2016-04-01

    Comparison between the structure and thermoelectric properties of EDTA (Ethylene-diamine-tetra-acetic acid) assisted bismuth telluride prepared by electrochemical deposition and hydrothermal route is reported in the present work. The prepared samples have been structurally characterized by high resolution X-ray diffraction spectra (HRXRD), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopic images (HRTEM). Crystallite size and strain have been determined from Williamson-Hall plot of XRD which is in conformity with TEM images. Measurement of transport properties show sample in the pellet form (S1) prepared via hydrothermal route has higher value of thermoelectric power (S) than the electrodeposited film (S2). But due to a substantial increase in the electrical conductivity (σ) of the film (S2) over the pellet (S1), the power factor and the figure of merit is higher for sample S2 than the sample S1 at room temperature.

  16. Electrochemical Studies of Lead Telluride Behavior in Acidic Nitrate Solutions

    Directory of Open Access Journals (Sweden)

    Rudnik E.

    2015-04-01

    Full Text Available Electrochemistry of lead telluride stationary electrode was studied in nitric acid solutions of pH 1.5-3.0. E-pH diagram for Pb-Te-H2O system was calculated. Results of cyclic voltammetry of Pb, Te and PbTe were discussed in correlation with thermodynamic predictions. Anodic dissolution of PbTe electrode at potential approx. -100÷50 mV (SCE resulted in tellurium formation, while above 300 mV TeO2 was mainly produced. The latter could dissolve to HTeO+2 under acidic electrolyte, but it was inhibited by increased pH of the bath.

  17. a dislocation loops in electron irradiated cadmium telluride

    International Nuclear Information System (INIS)

    In order to observe the radiation damage in undoped cadmium telluride created by an electron beam, irradiation experiments have been carried out in a high voltage electron microscope. After exposure to the electron beam during 15 min dislocation loops can be observed. The nature of these agglomerates has been determined by diffraction analysis and computer simulations. The loops have generally a Burgers vector parallel to (111) or (110) directions. Some rare specimens whose Burgers vector is a (100) and which are of interstitial type have also been characterized. A direct comparison of experimental micrographs with calculated intensities has been made based on the two-beam dynamical theory of electron diffraction in the case of the isotropic elasticity

  18. Cadmium Telluride Solar Cells with PEDOT:PSS Back Contact

    Science.gov (United States)

    Mount, Michael; Duarte, Fernanda; Paudel, Naba; Yan, Yanfa; Wang, Weining

    Cadmium Telluride (CdTe) solar cell is one of the most promising thin film solar cells and its highest efficiency has reached 21%. To keep improving the efficiency of CdTe solar cells, a few issues need to be addressed, one of which is the back contact. The back contact of CdTe solar cells are mostly Cu-base, and the problem with Cu-based back contact is that Cu diffuses into the grain boundary and into the CdS/CdTe junction, causing degradation problem at high temperature and under illumination. To continue improving the efficiency of CdTe/CdS solar cells, a good ohmic back contact with high work function and long term stability is needed. In this work, we report our studies on the potential of conducting polymer being used as the back contact of CdTe/CdS solar cells. Conducting polymers are good candidates because they have high work functions and high conductivities, are easy to process, and cost less, meeting all the requirements of a good ohmic back contact for CdTe. In our studies, we used poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) with different conductivities and compared them with traditional Cu-based back contact. It was observed that the CdTe solar cell performance improves as the conductivity of the PEDOT:PSS increase, and the efficiency (9.1%) is approaching those with traditional Cu/Au back contact (12.5%). Cadmium Telluride Solar Cells with PEDOT:PSS Back Contact.

  19. Elaboration and characterization of thin solid films containing cerium

    Science.gov (United States)

    Hamdi, S.; Guerfi, S.; Siab, R.

    2009-11-01

    Cerium oxide films are widely studied as a promising alternative to Cr(VI) based pre-treatments for the corrosion protection of different metals and alloys. Cathodic electrodeposition of Cerium containing thin films was realised on TA6V substrates from a Ce(NO3)3, 6H2O and mixed water-ethyl alcohol solutions at 0.01 M. Experimental conditions to obtain homogeneous and crack free thin films were determined. The deposited cerium quantity appears proportional to the quantity of electricity used, as indicated by the Faraday law. Subsequent thermal treatment lead to a CeO2 coating, expected to provide an increase of TA6V oxidation resistance at high temperatures. The deposits were characterized by differential scanning calorimetry (DSC), optical and scanning electron microscopies.

  20. Cerium uptake by zeolite A synthesized from natural clinoptilolite tuffs

    International Nuclear Information System (INIS)

    Natural clinoptilolite tuffs from the Semnan region in Iran was used for the synthesis of zeolite A. The tuffs and synthesized zeolites were characterized by XRD and XRF. The sorption behavior of the synthesized zeolite toward cerium was studied. Using the Lagergren's equation, the absorption constant was calculated. The measured distribution coefficient values (Kd) indicated that cerium uptake is higher in lower initial concentrations, higher temperature and higher pH values. Thermodynamic parameters of the exchange were calculated through construction of ion-exchange isotherms at three temperatures of 298, 323 and 343 K. The dynamic absorption of cerium was also studied by passing the solution through a column in the presence and absence of sodium ions. (author)

  1. Synthesis and characterization of magnesium doped cerium oxide for the fuel cell application

    Science.gov (United States)

    Kumar, Amit; Kumari, Monika; Kumar, Mintu; Kumar, Sacheen; Kumar, Dinesh

    2016-05-01

    Cerium oxide has attained much attentions in global nanotechnology market due to valuable application for catalytic, fuel additive, and widely as electrolyte in solid oxide fuel cell. Doped cerium oxide has large oxygen vacancies that allow for greater reactivity and faster ion transport. These properties make cerium oxide suitable material for SOFCs application. Cerium oxide electrolyte requires lower operation temperature which shows improvement in processing and the fabrication technique. In our work, we synthesized magnesium doped cerium oxide by the co-precipitation method. With the magnesium doping catalytic reactivity of CeO2 was increased. Synthesized nanoparticle were characterized by the XRD and UV absorption techniques.

  2. The PL "violet shift" of cerium dioxide on silicon

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    CeO2 thin film was fabricated by dual ion beam epitaxial technique. The phenomenon of PL violet shift at room temperature was observed, and the distance of shift was about 65 nm. After the analysis of crystal structure and valence in the compound were carried out by XRD and XPS technique, it was concluded that the PL shift was related with valence of cerium ion in the oxides. When the valence of cerium ion varied from tetravalence to trivalence, the PL peak position would move from blue region to violet region and the phenomenon of "violet shift" was observed.

  3. Photo-assisted reduction in nanostructured cerium-based coatings

    International Nuclear Information System (INIS)

    Nanostructured cerium-based coatings on AZ31 Mg alloy substrates exposed to sunlight under ambient conditions had an ∼30% increase in Ce(III) species compared to unexposed coatings as measured by X-ray photoelectron spectroscopy. A decrease in film cracks and shift in bandgap from 2.5 eV to 2.7 eV were also measured. Visible changes in color, from yellow to translucent, with exposure were also observed and suggest that cerium-based coatings are reduced by light exposure in humid environments

  4. Membrane assisted liquid-liquid extraction of cerium

    International Nuclear Information System (INIS)

    Membrane assisted liquid-liquid extraction of cerium was investigated, with emphasis placed on the study of the reaction chemistry and the kinetics of non-dispersive solvent extraction and stripping with microporous membranes. A bulk liquid membrane process was developed for the purification of cerium(IV) from sulfate solutions containing other rare earth elements. The cerium process was studied in both a flat sheet contained liquid membrane configuration and with hollow fibre contactors. Di-2-ethylhexyl phosphoric acid (DEHPA) was identified as a suitable extractant for cerium(IV) from sulfuric acid solution, with due consideration of factors such as extraction ability, resistance to degradation, solvent selectivity and potential for sulfate transfer into a strip solution. A detailed study of the extraction of cerium(IV) with DEHPA defined the extraction reaction chemistry. The Ce/DEHPA/sulfate system was also investigated with a flat sheet bulk liquid membrane configuration, using both sulfuric and hydrochloric acid as receiver solutions. These tests identified that hydrophobic membranes provide better mass transfer for extraction and hydrophilic membranes are better for stripping. The presence of an impurity, mono 2-ethylhexyl phosphoric acid (MEHPA), was found to have a dramatic accelerating effect on the rate of the chemical extraction reaction. This was attributed to its higher interfacial activity and population compared to DEHPA, and the fact that MEHPA was also found to be an active carrier for cerium(IV). The mass transfer rate of membrane assisted extraction and stripping of cerium, using hydrophobic and hydrophilic microporous membranes, respectively, was investigated using a modified Lewis-type cell. It was quantitatively demonstrated that the extraction process was mainly controlled by membrane diffusion and the stripping process was controlled by the chemical reaction rate, with membrane diffusion becoming important at low distribution coefficients

  5. Optical and electrical studies of cerium mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Sherly, T. R., E-mail: trsherly@gmail.com [Post Graduate Department of Physics, Sanathana Dharma College, Alappuzha, Kerala (India); Raveendran, R. [Nanoscience Research Laboratory, Sree Narayana College, Kollam, Kerala 691001 (India)

    2014-10-15

    The fast development in nanotechnology makes enthusiastic interest in developing nanomaterials having tailor made properties. Cerium mixed oxide materials have received great attention due to their UV absorption property, high reactivity, stability at high temperature, good electrical property etc and these materials find wide applications in solid oxide fuel cells, solar control films, cosmetics, display units, gas sensors etc. In this study cerium mixed oxide compounds were prepared by co-precipitation method. All the samples were doped with Zn (II) and Fe (II). Preliminary characterizations such as XRD, SEM / EDS, TEM were done. UV - Vis, Diffuse reflectance, PL, FT-IR, Raman and ac conductivity studies of the samples were performed.

  6. Electrical, thermal and infrared studies of cerium(III) orthovanadate

    International Nuclear Information System (INIS)

    Cerium(III) orthovandate with a small deviation from stoichiometric composition is a p-type semiconductor between 30 and 800 degC. The electrical conduction in cerium(III) orthovanadate is due to thermally activated hopping of holes on equivalent Ce3+ -Ce4+ lattice sites. The DTA result of CeVO4 indicated a possible phase transition at about 70 degC. The IR spectrum of the sample showed bands at 865 and 810 cm-1, typical of VO4 group of orthovanadates. (author). 10 refs., 3 figs

  7. Stepwise hydrochloric acid extraction of monazite hydroxides for the recovery of cerium lean rare earths, cerium, uranium and thorium

    International Nuclear Information System (INIS)

    Monazite sand is normally processed by the caustic soda route to produce mixed rare earth chloride, thorium hydroxide and trisodium phosphate. Bulk of the mixed rare earth chloride is used for the preparation of FC catalysts. Recently some of the catalyst producers have shown preference to cerium depleted (lanthanum enriched) rare earth chloride rather than the natural rare earth chloride obtained from monazite. Therefore, a process for producing cerium depleted rare earth chloride, cerium, thorium and uranium from rare earth + thorium hydroxide obtained by treating monazite, based on stepwise hydrochloric acid extraction, was developed in the authors laboratory. The process involves drying of the mixed rare earth-thorium hydroxide cake obtained by monazite-caustic soda process followed by stepwise extraction of the dried cake with hydrochloric acid under specified conditions

  8. Properties of Cerium Containing Lead Free Solder

    Science.gov (United States)

    Xie, Huxiao

    With increasing concerns of the intrinsic toxicity of lead (Pb) in electronics, a series of tin (Sn) based alloys involving silver (Ag) and copper (Cu) have been proposed as replacements for Pb-Sn solder and widely accepted by industry. However, they have a higher melting point and often exhibit poorer damage tolerance than Pb-Sn alloys. Recently, a new class of alloys with trace amount of rare-earth (RE) elements has been discovered and investigated. In previous work from Prof. Chawla's group, it has been shown that cerium (Ce)-based Pb-free solder are less prone to oxidation and Sn whiskering, and exhibit desirable attributes of microstructural refinement and enhanced ductility relative to lanthanum (La)-based Sn-3.9Ag-0.7Cu (SAC) alloy. Although the formation of RESn3 was believed to be directly responsible for the enhanced ductility in RE-containing SAC solder by allowing microscopic voids to nucleate throughout the solder volume, this cavitation-based mechanism needs to be validated experimentally and numerically. Additionally, since the previous study has exhibited the realistic feasibility of Ce-based SAC lead-free solder alloy as a replacement to conventional SAC alloys, in this study, the proposed objective focuses on the in in-depth understanding of mechanism of enhanced ductility in Ce-based SAC alloy and possible issues associated with integration of this new class of solder into electronic industry, including: (a) study of long-term thermal and mechanical stability on industrial metallization, (b) examine the role of solder volume and wetting behavior of the new solder, relative to Sn-3.9Ag-0.7Cu alloys, (c) conduct experiments of new solder alloys in the form of mechanical shock and electromigration. The research of this new class alloys will be conducted in industrially relevant conditions, and the results would serve as the first step toward integration of these new, next generation solders into the industry.

  9. Modulated structures in oxidized cerium niobates

    International Nuclear Information System (INIS)

    Three previously reported oxidized cerium niobate phases CeNbO4+x (x = 0.08, 0.25, and 0.33) have been synthesized and characterized by X-ray powder and electron diffraction. All three phases display structures which are modulated variants of a parent fergusonite-type CeIIINbO4 structure (I2/a, a = 5.5342(2) angstrom, b = 11.4016(6) angstrom, c = 5.1583(3) angstrom, β = 94.600(5)degree). The x = 0.08 phase with parent unit cell (I2/a, a = 5.3029(8) angstrom, b = 11.483(2) angstrom, c = 5.2515(8) angstrom, β = 91.32(2)degree) is a two-dimensional, incommensurately modulated phase characterized by incommensurate primary modulation wavevectors q1 ∼ [0.345, 0, 0.138]p* and q2 ∼ [-0.069, 0, 0.172]p* (p for parent). The x = 0.25 phase with parent unit cell (I2/a, a = 5.3522(8) angstrom, b = 11.374(3) angstrom, c = 5.116(1) angstrom, β = 93.34(2)degree) is a commensurately modulated superstructure phase characterized by the reciprocal space unit cell ar* = 1/12[402]p*, br* = 1/4[020]p*, and cr* = 1/3[101]p* (r for resultant). The x = 0.33 phase with parent unit cell (I1, a = 5.4374(8) angstrom, b = 11.189(2) angstrom, c = 5.1458(8) angstrom, α = 90.56(1), β = 94.37(1), γ = 88.19(1)degree) is again commensurately modulated with q = 1/3[101]p*. The close structural relationship between the three oxidized phases and possible interstitial oxygen sites in the CeIIINbO4 structure are discussed

  10. Cerium Oxyhydroxide Clusters: Formation, Structure and Reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Frederic Aubriet; Jean-Jacques Gaumet; Wibe A de Jong; Groenewold, Gary S (058000); Gianotto, Anita K (057404); McIlwain, Michael E (051783); Michael J. Van Stipdonk; Christopher M. Leavitt

    2009-06-01

    Cerium oxyhydroxide cluster anions were produced by irradiating ceric oxide particles using 355 nm laser pulses that were synchronized with pulses of nitrogen gas admitted to the irradiation chamber. The gas pulse stabilized the nascent clusters that are largely anhydrous [CexOy] ions and neutrals. These initially-formed species react with water, principally forming closed-shell (c-s) oxohydroxy species that are described by the general formula [CexOy(OH)z]-. In general, the extent of hydroxylation varies from a value of 3 OH per Ce atom when x = 1 to a value slightly greater than 1 for x > 8. The Ce3 and Ce6 species deviate significantly from this trend: the x = 3 cluster accommodates more hydroxyl moieties compared to neighboring congeners at x = 2 and x = 4. Conversely, the x = 6 cluster is significantly less hydroxylated. Density functional theory (DFT) modeling of the cluster structures show that the hydrated clusters are hydrolyzed, and contain one-to-multiple hydroxide moieties, but not datively bound water. DFT also predicts an energetic preference for formation of highly symmetric structures as the size of the clusters increases. The calculated structures indicate that the ability of the Ce3 oxyhydroxide to accommodate more extensive hydroxylation is due to a more open, hexagonal structure in which the Ce atoms can participate in multiple hydrolysis reactions. Conversely the Ce6 oxyhydroxide has an octahedral structure that is not conducive to hydrolysis. In addition to the c-s clusters, open-shell (o-s) oxyhydroxides and superoxides are also formed, and they become more prominent as the size of the clusters increases, suggesting that the larger ceria clusters have an increased ability to stabilize a non-bonding electron. The overall intensity of the clusters tends to monotonically decrease as the cluster size increases, however this trend is interrupted at Ce13, which is significantly more stable compared to neighboring congeners, suggesting formation of

  11. Cerium Oxyhydroxide Clusters: Formation, Structure and Reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Aubriet, F.; Gaumet, Jean-Jacques; De Jong, Wibe A.; Groenewold, G. S.; Gianotto, Anita K.; McIIwain, Michael E.; Van Stipdonk, Michael J.; Leavitt, Christopher M.

    2009-05-11

    Cerium oxyhydroxide cluster anions were produced by irradiating ceric oxide particles using 355 nm laser pulses that were synchronized with pulses of nitrogen gas admitted to the irradiation chamber. The gas pulse stabilized the nascent clusters that are largely anhydrous [CexOy] ions and neutrals. These initially-formed species react with water, principally forming closed-shell (c-s) oxohydroxy species that are described by the general formula [CexOy(OH)z]-. In general, the extent of hydroxylation varies from a value of 3 OH per Ce atom when x = 1 to a value slightly greater than 1 for x > 8. The Ce3 and Ce6 species deviate significantly from this trend: the x = 3 cluster accommodates more hydroxyl moieties compared to neighboring congeners at x = 2 and x = 4. Conversely, the x = 6 cluster is significantly less hydroxylated. Density functional theory (DFT) modeling of the cluster structures show that the hydrated clusters are hydrolyzed, and contain one-to-multiple hydroxide moieties, but not datively bound water. DFT also predicts an energetic preference for formation of highly symmetric structures as the size of the clusters increases. The calculated structures indicate that the ability of the Ce3 oxyhydroxide to accommodate more extensive hydroxylation is due to a more open, hexagonal structure in which the Ce atoms can participate in multiple hydrolysis reactions. Conversely the Ce6 oxyhydroxide has an octahedral structure that is not conducive to hydrolysis. In addition to the c-s clusters, open-shell (o-s) oxyhydroxides and superoxides are also formed, and they become more prominent as the size of the clusters increases, suggesting that the larger ceria clusters have an increased ability to stabilize a non-bonding electron. The overall intensity of the clusters tends to monotonically decrease as the cluster size increases, however this trend is interrupted at Ce13, which is significantly more stable compared to neighboring congeners, suggesting formation of

  12. Cerium tartrate as a corrosion inhibitor for AA 2024-T3

    International Nuclear Information System (INIS)

    Highlights: • Cerium tartrate was found to be an effective inhibitor for AA 2024-T3. • Both anodic and cathodic inhibitions were present during the corrosion process. • The corrosion of Al2CuMg phase was well inhibited by cerium tartrate. - Abstract: A new corrosion inhibitor, cerium tartrate, was synthetized. The inhibition behavior of cerium tartrate for 2024-T3 aluminum alloy was investigated in 0.05 M NaCl solution. The immersion tests indicate that the corrosion of Al2CuMg phase was well inhibited. The electrochemical results show that both anodic and cathodic inhibitions are present during the corrosion process. The surface characterizations reveal that the protective film of cerium tartrate inhibits the dealloying of Al2CuMg phase in the initial stage, and then cerium ions transform to cerium oxide/hydroxides and appear at the Al2CuMg phase, blocking the further corrosion at those corrosion sites

  13. Nanoparticulate cerium dioxide and cerium dioxide-titanium dioxide composite thin films on glass by aerosol assisted chemical vapour deposition

    International Nuclear Information System (INIS)

    Two series of composite thin films were deposited on glass by aerosol assisted chemical vapour deposition (AACVD)-nanoparticulate cerium dioxide and nanoparticulate cerium dioxide embedded in a titanium dioxide matrix. The films were analysed by a range of techniques including UV-visible absorption spectroscopy, X-ray diffraction, scanning electron microscopy and energy dispersive analysis by X-rays. The AACVD prepared films showed the functional properties of photocatalysis and super-hydrophilicity. The CeO2 nanoparticle thin films displaying photocatalysis and photo-induced hydrophilicity almost comparable to that of anatase titania.

  14. Cathodic electrodeposition of cerium-based oxides on carbon steel from concentrated cerium nitrate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Hamlaoui, Y. [Laboratoire d' Etudes des Materiaux en Milieux Agressifs (LEMMA), Pole Sciences et Technologie, Universite de La Rochelle, Avenue Michel Crepeau, 17042 La Rochelle Cedex 1 (France); Pedraza, F. [Laboratoire d' Etudes des Materiaux en Milieux Agressifs (LEMMA), Pole Sciences et Technologie, Universite de La Rochelle, Avenue Michel Crepeau, 17042 La Rochelle Cedex 1 (France)], E-mail: fpedraza@univ-lr.fr; Remazeilles, C.; Cohendoz, S.; Rebere, C. [Laboratoire d' Etudes des Materiaux en Milieux Agressifs (LEMMA), Pole Sciences et Technologie, Universite de La Rochelle, Avenue Michel Crepeau, 17042 La Rochelle Cedex 1 (France); Tifouti, L. [Laboratoire de Genie de l' Environnement, Universite Badji Mokhtar, BP 1223, 23020 El Hadjar-Annaba (Algeria); Creus, J. [Laboratoire d' Etudes des Materiaux en Milieux Agressifs (LEMMA), Pole Sciences et Technologie, Universite de La Rochelle, Avenue Michel Crepeau, 17042 La Rochelle Cedex 1 (France)

    2009-02-15

    In this work the elaboration by cathodic electrodeposition of cerium-based oxides on carbon steel from relatively concentrated cerium nitrate solutions is investigated. In particular, the study presented here (Part I) focuses on the electrochemical and analytical characterisation of the films and on the correlations between the electrochemical features and the characteristics of the layers. The effect of other parameters such as concentration, temperature, pH and additives to improve the behaviour of the film against corrosion will be investigated in part II of the study. The electrochemical characterisation will reveal that Ce(IV)-steel interactions can be responsible for some weak electrochemical waves appearing in the cyclic voltammograms that often are attributed to oxygen or nitrates reduction. This results from the oxidation of Ce(III) solutions to Ce(IV) in contact with air. Furthermore, the deposits strongly depend on the applied current density. Low current densities do not render fully covering deposits on the steel and a carbonated green rust will appear. On the contrary, the increase of the current density leads to denser layers of relatively small crystallite size that readily covers the steel surface. The deposits have a needle-like morphology and the Ce content achieves a plateau of about 20-22 at.%. However, a significant network of cracks appears probably occurring during the deposition process itself. The differential scanning calorimetry (DSC) results indicate that the deposits are not fully crystalline after 550 deg. C in contrast with the X-ray diffraction (XRD) patterns that unambiguously show a fluorite-type CeO{sub 2} phase whose crystallite size decreases with increasing the current density. The rinsing medium also brings about different features of the films. Rinsing with water allows to incorporate more nitrates and to adsorb CO{sub 2} than when rinsing with ethanol. However, R-OH bonds will be trapped in the latter.

  15. Cathodic electrodeposition of cerium-based oxides on carbon steel from concentrated cerium nitrate solutions

    International Nuclear Information System (INIS)

    In this work the elaboration by cathodic electrodeposition of cerium-based oxides on carbon steel from relatively concentrated cerium nitrate solutions is investigated. In particular, the study presented here (Part I) focuses on the electrochemical and analytical characterisation of the films and on the correlations between the electrochemical features and the characteristics of the layers. The effect of other parameters such as concentration, temperature, pH and additives to improve the behaviour of the film against corrosion will be investigated in part II of the study. The electrochemical characterisation will reveal that Ce(IV)-steel interactions can be responsible for some weak electrochemical waves appearing in the cyclic voltammograms that often are attributed to oxygen or nitrates reduction. This results from the oxidation of Ce(III) solutions to Ce(IV) in contact with air. Furthermore, the deposits strongly depend on the applied current density. Low current densities do not render fully covering deposits on the steel and a carbonated green rust will appear. On the contrary, the increase of the current density leads to denser layers of relatively small crystallite size that readily covers the steel surface. The deposits have a needle-like morphology and the Ce content achieves a plateau of about 20-22 at.%. However, a significant network of cracks appears probably occurring during the deposition process itself. The differential scanning calorimetry (DSC) results indicate that the deposits are not fully crystalline after 550 deg. C in contrast with the X-ray diffraction (XRD) patterns that unambiguously show a fluorite-type CeO2 phase whose crystallite size decreases with increasing the current density. The rinsing medium also brings about different features of the films. Rinsing with water allows to incorporate more nitrates and to adsorb CO2 than when rinsing with ethanol. However, R-OH bonds will be trapped in the latter

  16. Electrorheological Effects of Cerium-Doped TiO2

    Institute of Scientific and Technical Information of China (English)

    尹剑波; 赵晓鹏

    2001-01-01

    It is found that the doping of cerium ion into anatase TiO2 can improve the electrorheological (ER) effects of TiO2 and broaden the operational temperature range. Especially, the substitution of 7-11 mol% of the cerium dopant for Ti can obtain a relatively high shear stress, t-7.4kPa (at 4kV/mm), which is ten times larger than that of pure TiO2 ER fluid. Also, the typical Ce-doped TiO2 ER fluid shows the highest shear stress at 80℃, but 40℃ for pure TiO2 ER fluid. The dielectric loss and dielectric constant at a low frequency of TiO2 is improved by the doping of cerium, and the temperature dependence of the dielectric properties shows an obvious differnce between pure and doped TiO2 ER fluids. These can well explain the ER behaviour of doped TiO2. Furthermore, the change of rheological and dielectric properties is discussed on the basis of the lattice distortion and defects in TiO2 arising from the doping of cerium.

  17. Purification of cerium, neodymium and gadolinium for low background experiments

    Directory of Open Access Journals (Sweden)

    Boiko R.S.

    2014-01-01

    Full Text Available Cerium, neodymium and gadolinium contain double beta active isotopes. The most interesting are 150Nd and 160Gd (promising for 0ν2β search, 136Ce (2β+ candidate with one of the highest Q2β. The main problem of compounds containing lanthanide elements is their high radioactive contamination by uranium, radium, actinium and thorium. The new generation 2β experiments require development of methods for a deep purification of lanthanides from the radioactive elements. A combination of physical and chemical methods was applied to purify cerium, neodymium and gadolinium. Liquid-liquid extraction technique was used to remove traces of Th and U from neodymium, gadolinium and for purification of cerium from Th, U, Ra and K. Co-precipitation and recrystallization methods were utilized for further reduction of the impurities. The radioactive contamination of the samples before and after the purification was tested by using ultra-low-background HPGe gamma spectrometry. As a result of the purification procedure the radioactive contamination of gadolinium oxide (a similar purification efficiency was reached also with cerium and neodymium oxides was decreased from 0.12 Bq/kg to 0.007 Bq/kg in 228Th, from 0.04 Bq/kg to <0.006 Bq/kg in 226Ra, and from 0.9 Bq/kg to 0.04 Bq/kg in 40K. The purification methods are much less efficient for chemically very similar radioactive elements like actinium, lanthanum and lutetium.

  18. Enhanced K-edge angiography utilizing cerium-target diode

    International Nuclear Information System (INIS)

    The cerium-target x-ray tube is useful in order to perform cone-beam K-edge angiography because Kα rays from the cerium target are absorbed effectively by iodine-based contrast mediums. The x-ray generator consists of a main controller, an x-ray tube unit with a high-voltage circuit and an insulation transformer, and a personal computer. The tube is a glass-enclosed diode with a cerium target and a 0.5-mm-thick beryllium window. The maximum tube voltage and current were 65 kV and 0.4 mA, respectively, and the focal-spot sizes were approximately 1 x 1 mm. Sharp cerium Kα lines were left using a barium sulfate filter, and the x-ray intensity was 16.8 μGy/s at 1.0 m from the source with a tube voltage of 60 kV and a current of 0.40 mA. Angiography was performed with an x-ray film (Fuji IX 100) using iodine-based microspheres 15 μm in diameter. In angiography of non-living animals, we observed fine blood vessels of 100 μm or less with high contrasts. (author)

  19. Electrodeposition of cerium from aqueous cerous chloride solutions

    International Nuclear Information System (INIS)

    Cerium was plated as a grey, metallic, adherent deposit from aqueous cerous chloride baths containing certain organic addition agents. The cathodic current efficiency was determined for each case. Chemical analysis indicates that the purity of the metal is better than 99.0 per cent. (author). 7 refs

  20. 40 CFR 721.8657 - Cerium, hydroxy oleate propionate complexes.

    Science.gov (United States)

    2010-07-01

    ... complexes. 721.8657 Section 721.8657 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.8657 Cerium, hydroxy oleate propionate complexes. (a) Chemical substance..., hydroxy oleate propionate complexes (PMN P-99-0026) is subject to reporting under this section for...

  1. Thermoluminescence studies in cerium doped NaCl crystals

    International Nuclear Information System (INIS)

    Cerium is known to enter substitutionally in trivalent state when doped in alkali halides. Cerium doped NaCl crystals exhibit greatly enhanced thermoluminescence output upon X-irradiation at RT, the intensity of emission being about 10 times that in undoped crystals for similar dosage of irradiation. The cerium doped crystals give upon X-irradiation a very intense glow peak at 145degC with shoulders at 120degC and 210degC. Upon partially bleaching the crystal with F-light, the peak at 120degC becomes prominent probably due to faster bleaching of the glow at 145degC. From further optical bleaching studies, it is concluded that the glow peak at around 120degC is due to cerium centres in the irradiated crystal and the 145degC peak due to F centres. This F centre emission occurs at lower temperature, compared to that in the undoped crystals where it occurs at around 180degC. The spectral emission in the Ce doped crystals is in the blue-green region as compared to the emission in the blue region in undoped crystals. The trap depth and other parameters of the 120degC glow peak are estimated by the total curve fitting method. (author)

  2. Competition between magnetic order and Kondo effect in cerium compounds

    International Nuclear Information System (INIS)

    We present a mean-field analysis of the competition between magnetic order and Kondo effect in a Kondo-lattice model usually employed to discuss properties of certain cerium compounds. A phase diagram is obtained showing an antiferromagnetic phase and a Kondo-compensated regime, in agreement with the Doniach diagram. A general discussion of the mean-field approach is also presented

  3. Electrical measurements in the cerium oxide doped samples

    International Nuclear Information System (INIS)

    Electrical behaviour of an interface formed by cerium oxide doped system has been studied. The system was (Ce O2)1-0,005 (Y O 1,5)0,005/(Ce O2)1-0,14(Y O 1,5)0,14. This work relates results of impedance analysis, and curves U(I) at different temperatures and polarizations conditions. (author)

  4. Purification of cerium, neodymium and gadolinium for low background experiments

    Science.gov (United States)

    Boiko, R. S.; Barabash, A. S.; Belli, P.; Bernabei, R.; Cappella, F.; Cerulli, R.; Danevich, F. A.; Incicchitti, A.; Laubenstein, M.; Mokina, V. M.; Nisi, S.; Poda, D. V.; Polischuk, O. G.; Tretyak, V. I.

    2014-01-01

    Cerium, neodymium and gadolinium contain double beta active isotopes. The most interesting are 150Nd and 160Gd (promising for 0ν2β search), 136Ce (2β+ candidate with one of the highest Q2β). The main problem of compounds containing lanthanide elements is their high radioactive contamination by uranium, radium, actinium and thorium. The new generation 2β experiments require development of methods for a deep purification of lanthanides from the radioactive elements. A combination of physical and chemical methods was applied to purify cerium, neodymium and gadolinium. Liquid-liquid extraction technique was used to remove traces of Th and U from neodymium, gadolinium and for purification of cerium from Th, U, Ra and K. Co-precipitation and recrystallization methods were utilized for further reduction of the impurities. The radioactive contamination of the samples before and after the purification was tested by using ultra-low-background HPGe gamma spectrometry. As a result of the purification procedure the radioactive contamination of gadolinium oxide (a similar purification efficiency was reached also with cerium and neodymium oxides) was decreased from 0.12 Bq/kg to 0.007 Bq/kg in 228Th, from 0.04 Bq/kg to <0.006 Bq/kg in 226Ra, and from 0.9 Bq/kg to 0.04 Bq/kg in 40K. The purification methods are much less efficient for chemically very similar radioactive elements like actinium, lanthanum and lutetium.

  5. Cerium as a surrogate in the plutonium immobilization waste form

    Science.gov (United States)

    Marra, James Christopher

    In the aftermath of the Cold War, approximately 50 tonnes (MT) of weapons useable plutonium (Pu) has been identified as excess. The U.S. Department of Energy (DOE) has decided that at least a portion of this material will be immobilized in a titanate-based ceramic for final disposal in a geologic repository. The baseline formulation was designed to produce a ceramic consisting primarily of a highly substituted pyrochlore with minor amounts of brannerite and hafnia-substituted rutile. Since development studies with actual actinide materials is difficult, surrogates have been used to facilitate testing. Cerium has routinely been used as an actinide surrogate in actinide chemistry and processing studies. Although cerium appeared as an adequate physical surrogate for powder handling and general processing studies, cerium was found to act significantly different from a chemical perspective in the Pu ceramic form. The reduction of cerium at elevated temperatures caused different reaction paths toward densification of the respective forms resulting in different phase assemblages and microstructural features. Single-phase fabrication studies and cerium oxidation state analyses were performed to further quantify these behavioral differences. These studies indicated that the major phases in the final phase assemblages contained point defects likely leading to their stability. Additionally, thermochemical arguments predicted that the predominant pyrochlore phase in the ceramic was metastable. The apparent metastabilty associated with primary phase in the Pu ceramic form indicated that additional studies must be performed to evaluate the thermodynamic properties of these compounds. Moreover, the metastability of this predominant phase must be considered in assessment of long-term behavior (e.g. radiation stability) of this ceramic.

  6. Preparation, Characterization and Antibacterial Property of Cerium Substituted Hydroxyapatite Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Lin Yingguang; Yang Zhuoru; Cheng Jiang

    2007-01-01

    Nanoparticles of hydroxyapatite (HAP) and cerium substituted hydroxyapatite (CeHAP) with the atomic ratio of Ce/[Ca+Ce] (xCe) from 0 to 0.2 were prepared by sol-gel-supercritical fluid drying (SCFD) method. The nanoparticles were characterized by TEM, XRD, and FT-IR, and the effects of cerium on crystal structure, crystallinity, and particle shape were discussed. With the tests of bacterial inhibition zone and antibacterial ratio, the antibacterial property of HAP and CeHAP nanoparticles on Escherichia coli, Staphylococcus aureus, Lactobacillus were researched. Results showed that the nanoparticles of HAP and CeHAP could be made by sol-gel-SCFD, cerium could partially substitute for calcium and enter the structure of HAP. After substitution, the crystallinity, the IR wavenumbers of bonds in CeHAP decreased gradually with increase of cerium substitution, and the morphology of the nanoparticles changed from the short rod-shaped HAP to the needle-shaped CeHAP. The nanoparticles of HAP and CeHAP with xCe below 0.08 had antibacterial property only forcibly contacting with the test bacteria at the test concentration of 0.1 g·ml-1, however, the CeHAP nanoparticles had antibacterial ability at that concentration no matter statically or dynamically contacting with the test bacteria when xCe was above 0.08, and the antibacterial ability gets better with the increase of xCe, indicating that the antibacterial property was improved after calcium was partially substituted by cerium. The improved antibacterial effects of CeHAP nanoparticle on Lactobacillus showed its potential ability to anticaries.

  7. Magnetic properties of Cr telluride-selenide alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mankovsky, Sergey; Polesya, Svetlana; Ebert, Hubert [Dept. Chemie und Biochemie, Universitaet Muenchen, Butenandtstr. 5-13, D-81377 Muenchen (Germany); Huang, Zhong-Le; Bensch, Wolfgang [Institute for Anorganic Chemistry, Olshausenstr. 40, D-24098, Kiel (Germany)

    2007-07-01

    Results of a theoretical study of the magnetic properties of Cr telluride-selenide alloys having trigonal crystal structure are presented in comparison with experimental results. Both ground state and temperature-dependent magnetic properties of Cr{sub 1-{delta}}Te and Cr{sub x}(Te{sub {alpha}}Se{sub {beta}}){sub 2} (with ratio {alpha}:{beta}=7:1,6:2,5:3) have been investigated in a wide region of chromium content. For the alloys Cr{sub x}(Te{sub {alpha}}Se{sub {beta}}){sub 2} a transition to the state with antiferromagnetic order in a fully occupied sub-lattice and with no order in a partially occupied sub-lattice was obtained. For the alloys Li{sub x}Cr{sub 0.5}Ti{sub 0.75}Se{sub 2}, a non-monotonic dependence of structural and magnetic properties have been found upon increase of Li concentration x, that is in agreement with experimental results. The ground state properties have been studied on the basis of electronic structure calculations using the Korringa-Kohn-Rostoker (KKR) band structure method combined with the CPA alloy theory. Using Monte Carlo simulations we obtained the magnetic configuration at T=0 K and studied the magnetic properties at T>0 K as well. The required exchange coupling parameters were obtained from our ab-initio electronic structure calculations.

  8. Brief review of cadmium telluride-based photovoltaic technologies

    Science.gov (United States)

    Başol, Bülent M.; McCandless, Brian

    2014-01-01

    Cadmium telluride (CdTe) is the most commercially successful thin-film photovoltaic technology. Development of CdTe as a solar cell material dates back to the early 1980s when ˜10% efficient devices were demonstrated. Implementation of better quality glass, more transparent conductive oxides, introduction of a high-resistivity transparent film under the CdS junction-partner, higher deposition temperatures, and improved Cl-treatment, doping, and contacting approaches yielded >16% efficient cells in the early 2000s. Around the same time period, use of a photoresist plug monolithic integration process facilitated the demonstration of the first 11% efficient module. The most dramatic advancements in CdTe device efficiencies were made during the 2013 to 2014 time frame when small-area cell conversion efficiency was raised to 20% range and a champion module efficiency of 17% was reported. CdTe technology is attractive in terms of its limited life-cycle greenhouse gas and heavy metal emissions, small carbon footprint, and short energy payback times. Limited Te availability is a challenge for the growth of this technology unless Te utilization rates are greatly enhanced along with device efficiencies.

  9. Review of the field performance of one cadmium telluride module

    Energy Technology Data Exchange (ETDEWEB)

    Cueto, J.A. del [National Renewable Energy Lab., Golden, CO (United States)

    1998-12-01

    Performance data gathered in situ from a large-area cadmium telluride (CdTe) thin-film photovoltaic (PV) module that has been deployed outdoors since February 1995 are investigated. It appears that the module's performance has been stable over the last 2 years but it exhibits a semi-cyclical variation whereby the efficiency appears to peak between the autumnal equinox and winter solstice. Analyses are performed that dissect module current-voltage parameters by irradiance and examine their dependence on temperature. The temperature coefficient of the efficiency is quite small and negative from 80% of 1-sun intensity and upwards. Its meager value is the outcome of the sizes and opposite sings of the temperature coefficients of the open-circuit voltage and fill factor. Average module series resistance is quantified and shown to be a determinant in power loss of 11% at 1-sun intensity. It is demonstrated to constrain the fill factor at illumination intensities above 60% of 1-sun, which occurs in the same range of illumination intensities that the temperature coefficients of the fill factor exhibit positive values. Evidence is presented that points to some spectrally-induced variations in the efficiency. (Author)

  10. Using atomistic simulations to model cadmium telluride thin film growth

    Science.gov (United States)

    Yu, Miao; Kenny, Steven D.

    2016-03-01

    Cadmium telluride (CdTe) is an excellent material for low-cost, high efficiency thin film solar cells. It is important to conduct research on how defects are formed during the growth process, since defects lower the efficiency of solar cells. In this work we use computer simulation to predict the growth of a sputter deposited CdTe thin film. On-the-fly kinetic Monte Carlo technique is used to simulate the CdTe thin film growth on the (1 1 1) surfaces. The results show that on the (1 1 1) surfaces the growth mechanisms on surfaces which are terminated by Cd or Te are quite different, regardless of the deposition energy (0.1∼ 10 eV). On the Te-terminated (1 1 1) surface the deposited clusters first form a single mixed species layer, then the Te atoms in the mixed layer moved up to form a new layer. Whilst on the Cd-terminated (1 1 1) surface the new Cd and Te layers are formed at the same time. Such differences are probably caused by stronger bonding between ad-atoms and surface atoms on the Te layer than on the Cd layer.

  11. Preliminary uranium enrichment analysis results using cadmium zinc telluride detectors

    International Nuclear Information System (INIS)

    Lawrence Livermore National Laboratory (LLNL) and EG ampersand G ORTEC have jointly developed a portable ambient-temperature detection system that can be used in a number of application scenarios. The detection system uses a planar cadmium zinc telluride (CZT) detector with custom-designed detector support electronics developed at LLNL and is based on the recently released MicroNOMAD multichannel analyzer (MCA) produced by ORTEC. Spectral analysis is performed using software developed at LLNL that was originally designed for use with high-purity germanium (HPGe) detector systems. In one application, the CZT detection system determines uranium enrichments ranging from less than 3% to over 75% to within accuracies of 20%. The analysis was performed using sample sizes of 200 g or larger and acquisition times of 30 min. The authors have demonstrated the capabilities of this system by analyzing the spectra gathered by the CZT detection system from uranium sources of several enrichments. These experiments demonstrate that current CZT detectors can, in some cases, approach performance criteria that were previously the exclusive domain of larger HPGe detector systems

  12. Induced Positron Annihiliation Investigation of Cadmium Zinc Telluride Crystal Microstructures

    Energy Technology Data Exchange (ETDEWEB)

    D. W. Akers

    2005-06-01

    Cadmium-Zinc-Telluride (CZT) crystals are used in semiconductor radiation detectors for the detection of x-ray and gamma radiation. However, production of detector grade crystals is difficult as small variations in compositional uniformity and primarily the zinc content can significantly affect the ability of the CZT crystal to function as a radiation detector. Currently there are no known nondestructive methods that can be used to identify detector grade crystals. The current test method is to fabricate and test the detector to determine if the crystal is sufficiently uniform and of the correct composition to be considered a detector grade crystal. Consequently, nondestructive detection methods are needed to identify detector grade crystals prior to the fabrication process. The purpose of this feasibility study was to perform a preliminary assessment of the ability of several new, nondestructive technologies based on Induced Positron Annihilation (IPA) to determine if detector grade CZT crystals can be identified. Results of measurements performed on specimens from Fisk University and EV Products, Inc. indicate that both the near surface Distributed Source Positron Annihilation (up to 3 mm penetration) and the volumetric Photon Induced Positron Annihilation methods may be suitable for determining CZT crystal quality. Further work on CZT crystals with a broader range of compositions and detector characteristics is needed to provide a well defined, calibrated, method for assessing CZT crystal quality.

  13. Self-Organization and Ovonic Switching in Telluride Glasses

    Science.gov (United States)

    Liuchun, Cai; Boolchand, P.

    2003-03-01

    Self-organization [1] in glasses raises the interesting possibility to look for such effects in Telluride glasses where Ovonic switching is observed [2]. Ternary Al20 (As or Ge)xTe80-x glasses have been synthesized in 0MDSC. In As based glasses Tgs increase monotonically with x in the 140 0C < Tg < 216 0C range. And the non-reversing enthalpy [1], DHnr, shows a broad but shallow minimum in the 0.15 < x < 0.25 range. In the same range, the threshold electric field for switching, Ec, shows [2] a mild reduction from a monotonic behavior. In Ge based glasses, Tg displays a global maximum near x = 0.075, to decrease at higher x. Here Ec also displays a global maximum near x=0.075. As-based glasses may be self-organized in 0.15

  14. Preliminary uranium enrichment analysis results using cadmium zinc telluride detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lavietes, A.D.; McQuaid, J.H. [Lawrence Livermore National Lab., CA (United States); Paulus, T.J. [EG& G ORTEC, Oak Ridge, TN (United States)

    1995-09-08

    Lawrence Livermore National Laboratory (LLNL) and EG&G ORTEC have jointly developed a portable ambient-temperature detection system that can be used in a number of application scenarios. The detection system uses a planar cadmium zinc telluride (CZT) detector with custom-designed detector support electronics developed at LLNL and is based on the recently released MicroNOMAD multichannel analyzer (MCA) produced by ORTEC. Spectral analysis is performed using software developed at LLNL that was originally designed for use with high-purity germanium (HPGe) detector systems. In one application, the CZT detection system determines uranium enrichments ranging from less than 3% to over 75% to within accuracies of 20%. The analysis was performed using sample sizes of 200 g or larger and acquisition times of 30 min. The authors have demonstrated the capabilities of this system by analyzing the spectra gathered by the CZT detection system from uranium sources of several enrichments. These experiments demonstrate that current CZT detectors can, in some cases, approach performance criteria that were previously the exclusive domain of larger HPGe detector systems.

  15. Ambient temperature cadmium zinc telluride radiation detector and amplifier circuit

    International Nuclear Information System (INIS)

    A low noise, low power consumption, compact, ambient temperature signal amplifier for a Cadmium Zinc Telluride (CZT) radiation detector is disclosed. The amplifier can be used within a larger system (e.g., including a multi-channel analyzer) to allow isotopic analysis of radionuclides in the field. In one embodiment, the circuit stages of the low power, low noise amplifier are constructed using integrated circuit (IC) amplifiers , rather than discrete components, and include a very low noise, high gain, high bandwidth dual part preamplification stage, an amplification stage, and an filter stage. The low noise, low power consumption, compact, ambient temperature amplifier enables the CZT detector to achieve both the efficiency required to determine the presence of radionuclides and the resolution necessary to perform isotopic analysis to perform nuclear material identification. The present low noise, low power, compact, ambient temperature amplifier enables a CZT detector to achieve resolution of less than 3% full width at half maximum at 122 keV for a Cobalt-57 isotope source. By using IC circuits and using only a single 12 volt supply and ground, the novel amplifier provides significant power savings and is well suited for prolonged portable in-field use and does not require heavy, bulky power supply components. 9 figs

  16. Determination of silver and cerium in the liver and the kidney from a severely burned infant treated with silver sulfadiazine and cerium nitrate

    International Nuclear Information System (INIS)

    Silver and cerium in the liver and the kidney from severely burned infant were analyzed by neutron activation method. The patient was treated topically with cerium nitrate/silver sulfadiazine cream and cerium nitrate solution for 3 months. Then, the treatment with these drugs was stopped because o f abdominal distention. The patient died 1 month after the cessation of the treatment with these drugs. The tissue specimens, blank liver sample and reference standards were irradiated with TRIGA MARK II Reactor of Rikkyo University. About 1 month after the irradiation, the activities were measured with a Ge(Li) detector coupled to a 4096 channel pulse height analyzer. A large amount of silver was detected both in the liver and in the kidney and a trace of cerium only in the liver. A considerable amount of silver was detected in the liver and its quantity was about 1600 times more than that of normal livers reported by Hamilton, Minski and Cleary (1972 -- 73). Neither silver nor cerium were detected in the blank liver. These results suggest that prolonged topical chemotherapy of cerium nitrate/silver sulfadiazine cream and cerium nitrate solution for the extensive burn injuries causes considerable absorption of silver and cerium into the liver and the kidney. (author)

  17. [Determination of silver and cerium in the liver and the kidney from a severely burned infant treated with silver sulfadiazine and cerium nitrate].

    Science.gov (United States)

    Hirakawa, K

    1983-02-01

    Silver and cerium in the liver and the kidney from severely burned infant were analyzed by neutron activation method. The patient was treated topically with cerium nitrate/silver sulfadiazine cream and cerium nitrate solution for 3 months. Then, the treatment with these drugs was stopped because of abdominal distention. The patient died 1 month after the cessation of the treatment with these drugs. The tissue specimens, blank liver sample and reference standards were irradiated with TRIGA MARK II Reactor of Rikkyo University. About 1 month after the irradiation, the activities were measured with a Ge(Li) detector coupled to a 4096 channel pulse height analyzer. A large amount of silver was detected both in the liver and in the kidney and a trace of cerium only in the liver. A considerable amount of silver was detected in the liver and its quantity was about 1600 times more than that of normal livers reported by Hamilton, Minski and Cleary (1972-73). Neither silver nor cerium were detected in the blank liver. These results suggest that prolonged topical chemotherapy of cerium nitrate/silver sulfadiazine cream and cerium nitrate solution for the extensive burn injuries causes considerable absorption of silver and cerium into the liver and the kidney. PMID:6867381

  18. Determination of silver and cerium in the liver and the kidney from a severely burned infant treated with silver sulfadiazine and cerium nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Hirakawa, Keiko (Nippon Medical School, Tokyo)

    1983-02-01

    Silver and cerium in the liver and the kidney from severely burned infant were analyzed by neutron activation method. The patient was treated topically with cerium nitrate/silver sulfadiazine cream and cerium nitrate solution for 3 months. Then, the treatment with these drugs was stopped because of abdominal distention. The patient died 1 month after the cessation of the treatment with these drugs. The tissue specimens, blank liver sample and reference standards were irradiated with TRIGA MARK II Reactor of Rikkyo University. About 1 month after the irradiation, the activities were measured with a Ge(Li) detector coupled to a 4096 channel pulse height analyzer. A large amount of silver was detected both in the liver and in the kidney and a trace of cerium only in the liver. A considerable amount of silver was detected in the liver and its quantity was about 1600 times more than that of normal livers reported by Hamilton, Minski and Cleary (1972 -- 73). Neither silver nor cerium were detected in the blank liver. These results suggest that prolonged topical chemotherapy of cerium nitrate/silver sulfadiazine cream and cerium nitrate solution for the extensive burn injuries causes considerable absorption of silver and cerium into the liver and the kidney.

  19. Fundamental aspects of regenerative cerium oxide nanoparticles and their applications in nanobiotechnology

    Science.gov (United States)

    Patil, Swanand D.

    Cerium oxide has been used extensively for various applications over the past two decades. The use of cerium oxide nanoparticles is beneficial in present applications and can open avenues for future applications. The present study utilizes the microemulsion technique to synthesize uniformly distributed cerium oxide nanoparticles. The same technique was also used to synthesize cerium oxide nanoparticles doped with trivalent elements (La and Nd). The fundamental study of cerium oxide nanoparticles identified variations in properties as a function of particle size and also due to doping with trivalent elements (La and Nd). It was found that the lattice parameter of cerium oxide nanoparticles increases with decrease in particle size. Also Raman allowed mode shift to lower energies and the peak at 464 cm-1 becomes broader and asymmetric. The size dependent changes in cerium oxide were correlated to increase in oxygen vacancy concentration in the cerium oxide lattice. The doping of cerium oxide nanoparticles with trivalent elements introduces more oxygen vacancies and expands the cerium oxide lattice further (in addition to the lattice expansion due to the size effect). The lattice expansion is greater for La-doped cerium oxide nanoparticles compared to Nd-doping due to the larger ionic radius of La compared to Nd, the lattice expansion is directly proportional to the dopant concentration. The synthesized cerium oxide nanoparticles were used to develop an electrochemical biosensor of hydrogen peroxide (H2O2). The sensor was useful to detect H2O2 concentrations as low as 1muM in water. Also the preliminary testing of the sensor on tomato stem and leaf extracts indicated that the sensor can be used in practical applications such as plant physiological studies etc. The nanomolar concentrations of cerium oxide nanoparticles were also found to be useful in decreasing ROS (reactive oxygen species) mediated cellular damages in various in vitro cell cultures. Cerium oxide

  20. Process for obtaining oxygen doped zinc telluride monocrystals and scintillator crystals obtained by this process

    International Nuclear Information System (INIS)

    A process is described for obtaining oxygen doped zinc telluride monocrystals, for use as scintillator crystals for ionising radiation detectors. The following operations are carried out in succession: one or several zinc telluride crystals are introduced into a silica ampoule together with a ternary mixture of zinc tellurium and oxygen, as an oxide or hydroxide of these elements; the ampoule is pumped down to a high vacuum and sealed; the sealed ampoule containing the mixture and monocrystals is placed in a kiln and brought to a uniform temperature sufficient to make the mixture three-phased, depending on its composition; the zinc telluride crystalline compound remains solid; the ampoule is then tempered to bring it quickly back to ambient temperature

  1. Synthesis and crystal kinetics of cerium oxide nanocrystallites prepared by co-precipitation process

    Energy Technology Data Exchange (ETDEWEB)

    Shih, C.J., E-mail: cjshih@kmu.edu.tw [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100 Shi-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Chen, Y.J. [Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Hon, M.H. [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)

    2010-05-15

    Cerium oxide nanocrystallites were synthesized at a relatively low temperature using cerium nitrate as starting materials in a water solution by a co-precipitation process. Effect of calcination temperature on the crystallite growth of cerium oxide nano-powders was investigated by X-ray diffraction, transmission electron microscopy and electron diffraction. The crystallization temperature of the cerium oxide powders was estimated to be about 273 K by XRD analysis. When calcined from 473 to 1273 K, the crystallization of the face-centered cubic phase was observed by XRD. The crystallite size of the cerium oxide increased from 10.0 to 43.8 nm with calcining temperature increasing from 673 to 1273 K. The activation energy for growth of cerium oxide nanoparticles was found to be 16.0 kJ mol{sup -1}.

  2. Synthesis and crystal kinetics of cerium oxide nanocrystallites prepared by co-precipitation process

    International Nuclear Information System (INIS)

    Cerium oxide nanocrystallites were synthesized at a relatively low temperature using cerium nitrate as starting materials in a water solution by a co-precipitation process. Effect of calcination temperature on the crystallite growth of cerium oxide nano-powders was investigated by X-ray diffraction, transmission electron microscopy and electron diffraction. The crystallization temperature of the cerium oxide powders was estimated to be about 273 K by XRD analysis. When calcined from 473 to 1273 K, the crystallization of the face-centered cubic phase was observed by XRD. The crystallite size of the cerium oxide increased from 10.0 to 43.8 nm with calcining temperature increasing from 673 to 1273 K. The activation energy for growth of cerium oxide nanoparticles was found to be 16.0 kJ mol-1.

  3. Effect of cerium modification on microstructure and properties of hypereutectic high chromium cast iron

    Energy Technology Data Exchange (ETDEWEB)

    Zhi, Xiaohui, E-mail: mkmkzxh@hotmail.com [School of Mechanical Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, Hebei Province (China); Liu, Jinzhi [School of Mechanical Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, Hebei Province (China); Xing, Jiandong; Ma, Shengqiang [State Key Laboratory Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi' an Jiaotong University, Xi' an 710049, Shaanxi Province (China)

    2014-05-01

    The effect of cerium modification on the microstructure and properties of hypereutectic high chromium cast iron primarily containing 4.0 wt% C and 20.0 wt% Cr was studied by means of optical microscopy, transmission electron microscope, scanning electron microscope, and energy dispersive X-ray spectrometry. The primary M{sub 7}C{sub 3} carbides were refined obviously when cerium was added in the melt. Ce{sub 2}S{sub 3} was found in the primary M{sub 7}C{sub 3} carbides and acted as the heterogeneous substrate of M{sub 7}C{sub 3} carbides. The impact toughness of the specimen modified with 0.5 wt% cerium increased by 50% compared with the specimen without cerium modification. The hardness of the alloy modified with cerium increased slightly compared with the specimen without cerium modification.

  4. Critical indices for reversible gamma-alpha phase transformation in metallic cerium

    Science.gov (United States)

    Soldatova, E. D.; Tkachenko, T. B.

    1980-08-01

    Critical indices for cerium have been determined within the framework of the pseudobinary solution theory along the phase equilibrium curve, the critical isotherm, and the critical isobar. The results obtained verify the validity of relationships proposed by Rushbrook (1963), Griffiths (1965), and Coopersmith (1968). It is concluded that reversible gamma-alpha transformation in metallic cerium is a critical-type transformation, and cerium has a critical point on the phase diagram similar to the critical point of the liquid-vapor system.

  5. X-ray computed tomography system utilizing a cadmium telluride detector

    OpenAIRE

    佐藤, 英一; 野宮, 聖一郎; 人見, 啓太朗; 尾鍋, 秀明; 河合, 敏明; 小川, 彰; 佐藤, 成大; 市丸, 俊夫; サトウ, エイイチ; ノミヤ, セイイチロウ; ヒトミ, ケイタロウ; オナベ, ヒデアキ; カワイ, トシアキ; オガワ, アキラ; サトウ, シゲヒロ

    2007-01-01

    A simple x-ray computed tomography(CT) system utilizing a cadmium telluride detector is described. The CT system is of the first generation type and consists of an x-ray generator, a turn table, a translation table, a motor drive unit, a cadmium telluride detector, an interface unit for the detector, and a personal computer(PC). Tomography was performed by the repetition of the translation and rotation of an object. The maximum values of the tube voltage and the tube current were 110kV and 2....

  6. On the potentialities of cadmium telluride using for pulsed X-radiation detection in medical tomographs

    International Nuclear Information System (INIS)

    The possibility of usage of cadmium telluride as detectors for pulsed x-radiation detection in tomographic systems are considered. Experimental results of photoelectric characteristics of detectors of M-P-M structures on the base of semi- isolating CdTe(Cl) crystals are presented. The dependences of dark current and photocurrent on a bias voltage, detector lux-ampere characteristics and dependence of the induced current in the cadmium telluride detector on x-radiation flux intensity are presented. The determining effect of crystal purity on all detector characteristics is pointed out

  7. The effect of cerium valence states at cerium oxide nanoparticle surfaces on cell proliferation

    KAUST Repository

    Naganuma, Tamaki

    2014-05-01

    Understanding and controlling cell proliferation on biomaterial surfaces is critical for scaffold/artificial-niche design in tissue engineering. The mechanism by which underlying integrin ligates with functionalized biomaterials to induce cell proliferation is still not completely understood. In this study, poly-l-lactide (PL) scaffold surfaces were functionalized using layers of cerium oxide nanoparticles (CNPs), which have recently attracted attention for use in therapeutic application due to their catalytic ability of Ce4+ and Ce3+ sites. To isolate the influence of Ce valance states of CNPs on cell proliferation, human mesenchymal stem cells (hMSCs) and osteoblast-like cells (MG63) were cultured on the PL/CNP surfaces with dominant Ce4+ and Ce3+ regions. Despite cell type (hMSCs and MG63 cells), different surface features of Ce4+ and Ce3+ regions clearly promoted and inhibited cell spreading, migration and adhesion behavior, resulting in rapid and slow cell proliferation, respectively. Cell proliferation results of various modified CNPs with different surface charge and hydrophobicity/hydrophilicity, indicate that Ce valence states closely correlated with the specific cell morphologies and cell-material interactions that trigger cell proliferation. This finding suggests that the cell-material interactions, which influence cell proliferation, may be controlled by introduction of metal elements with different valence states onto the biomaterial surface. © 2014 Elsevier Ltd.

  8. Dental x-ray spectrometry with cadmium telluride detectors

    International Nuclear Information System (INIS)

    Cadmium telluride (CdTe) semiconductor detectors provide high detection efficiency for use in the diagnostic x-rays energy range, due to the high atomic number and density of the crystal. This kind of detector has been utilized in diagnostic x-ray spectroscopy, mainly in the mammography energy range, but only scarce information about its use in dental x-ray beams has been published. In this way, a portable 3x3x1 mm3 CdTe solid state detector (XR-100T CdTe, Amptek, Inc.) with electronic system, tungsten pinhole collimators, alignment device and associated software was utilized in this work. A single-phase dental unit with adjustable kVp and mA was employed and the x-ray spectra were experimentally determined at 50, 60 and 70 kVp with a tube current of 0.5 mA and 1.5mm Al additional filtration. An experimental setup was developed to guarantee a perfect alignment between the detector and the focal spot. The detector to focal spot distance was 3.0 m. Two 2mm thick tungsten pinholes (Amptek EXVC kit) with 0.4 mm and 1.0 mm collimator aperture diameters were positioned close to the detector in order to reduce the pulse pile-up events at high counting rates. A stripping procedure was implemented to correct the pulse height distribution in order to determine the photon spectra. The calculation of the CdTe response, used to correct the measured spectra, was simulated using the GEANT4 Monte Carlo toolkit. The x-ray spectra were compared with the spectra obtained with a high-purity germanium detector (EGP200-13-TR, Eurisys Mesures) with associated electronic devices and software. The reasonable agreement between the results obtained with both detectors shows that CdTe detectors can be successfully utilized for dental x-ray spectrometry. (author)

  9. Cadmium zinc telluride detector for low photon energy applications

    Science.gov (United States)

    Shin, Kyung-Wook; Wang, Kai; Reznic, Alla; Karim, Karim S.

    2010-04-01

    Cadmium Zinc Telluride (CdZnTe or CZT) is a polycrystalline radiation detector that has been investigated over the years for a variety of applications including Constellation X-ray space mission [1] and direct-conversion medical imaging such as digital mammography [2]. Due to its high conversion gain and low electron-hole pair creation energy (~4.43 eV) [3], it has found use in high end, photon counting medical imaging applications including positron emission tomography (PET), computed tomography (CT) and single photon emission computed tomography (SPECT). However, its potential in low photon energy applications has not been fully explored. In this work, we explore the capacity of the CZT material to count low photon energies (6 keV - 20 keV). These energies are of direct relevance to applications in gamma ray breast brachytheraphy and mammography, X-ray protein crystallography, X-ray mammography and mammography tomosynthesis. We also present a design that integrates the CZT direct conversion detector with an inhouse fabricated amorphous silicon (a-Si:H) thin film transistor (TFT) passive pixel sensor (PPS) array. A CZT photoconductor (2 cm x 2 cm size, 5-mm-thick) prepared by the traveling heat method (THM) from RedlenTM is characterized. The current-voltage characteristics reveal a resistivity of 3.3 x 1011 Ω•cm and a steady state dark current in the range of nA. Photocurrent transients under different biases and illumination pulses are studied to investigate photogeneration and the charge trapping process. It is found that charge trapping plays a more significant role in transient behavior at low biases and low frequency.

  10. Study of cerium diffusion in undoped lithium-6 enriched glass with Rutherford backscattering spectrometry

    Science.gov (United States)

    Zhang, Xiaodong; Moore, Michael E.; Lee, Kyung-Min; Lukosi, Eric D.; Hayward, Jason P.

    2016-07-01

    Undoped lithium-6 enriched glasses coated with pure cerium (99.9%) with a gold protection layer on top were heated at three different temperatures (500, 550, and 600 °C) for varied durations (1, 2, and 4 h). Diffusion profiles of cerium in such glasses were obtained with the conventional Rutherford backscattering technique. Through fitting the diffusion profiles with the thin-film solution of Fick's second law, diffusion coefficients of cerium with different annealing temperatures and durations were solved. Then, the activation energy of cerium for the diffusion process in the studied glasses was found to be 114 kJ/mol with the Arrhenius equation.

  11. Doping of KDP single crystals with cerium: Growth and optical properties

    International Nuclear Information System (INIS)

    The features of doping of KDP crystals with cerium ions and organocerium complexes with alizarin complexon and arsenazo III have been investigated. It is established that 'direct' doping by introducing cerium salts into the initial solution cannot be implemented. The effect of organometallic complexes of cerium on the crystal growth has been studied. Organocerium complexes predominantly enter the prismatic or pyramidal growth sectors. It is shown that the complex arsenazo III + Ce blocks the growth of the prismatic sector. Cerium-doped KDP crystals exhibit a photoluminescence band peaking at the wavelength λmax= 350 nm.

  12. Fabrication of mesoporous cerium dioxide films by cathodic electrodeposition.

    Science.gov (United States)

    Kim, Young-Soo; Lee, Jin-Kyu; Ahn, Jae-Hoon; Park, Eun-Kyung; Kim, Gil-Pyo; Baeck, Sung-Hyeon

    2007-11-01

    Mesoporous cerium dioxide (Ceria, CeO2) thin films have been successfully electrodeposited onto ITO-coated glass substrates from an aqueous solution of cerium nitrate using CTAB (Cetyltrimethylammonium Bromide) as a templating agent. The synthesized films underwent detailed characterizations. The crystallinity of synthesized CeO2 film was confirmed by XRD analysis and HR-TEM analysis, and surface morphology was investigated by SEM analysis. The presence of mesoporosity in fabricated films was confirmed by TEM and small angle X-ray analysis. As-synthesized film was observed from XRD analysis and HR-TEM image to have well-crystallized structure of cubic phase CeO2. Transmission electron microscopy and small angle X-ray analysis revealed the presence of uniform mesoporosity with a well-ordered lamellar phase in the CeO2 films electrodeposited with CTAB templating. PMID:18047150

  13. Antioxidant activity of levan coated cerium oxide nanoparticles.

    Science.gov (United States)

    Kim, Sun-Jung; Chung, Bong Hyun

    2016-10-01

    Levan coated cerium oxide nanoparticles (LCNPs) with the enhanced antioxidant activity were successfully synthesized and characterized. Levan and their derivatives are attractive for biomedical applications attributable to their antioxidant, anti-inflammation and anti-tumor properties. LCNPs were synthesized using the one-pot and green synthesis system with levan. For production of nanoparticles, levan plays a role as a stabilizing and reducing agent. Fourier transform infrared spectroscopy (FT-IR) analysis showed that LCNPs successfully synthesized. The morphology and size of nanoparticles were confirmed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). LCNPs have good water solubility and stability. The conjugation of levan with cerium oxide nanoparticles improved antioxidant activity. Moreover the level of ROS was reduced after treatment of LCNPs to H2O2 stimulated NIH3T3 cells. These results demonstrate that the LCNPs are useful for applying of treatment of ROS induced diseases. PMID:27312651

  14. Adsorption of Fluoride Ion by Inorganic Cerium Based Adsorbent

    Institute of Scientific and Technical Information of China (English)

    Jiao Zhongzhi(焦中志); Chen Zhonglin; Yang Min; Zhang Yu; Li Guibai

    2004-01-01

    Excess of fluoride in drinking water is harmful to human health, the concentration of F- ions must be maintained in the range of 0.5 to 1.5 mg/L. An inorganic cerium based adsorbent (CTA) is developed on the basis of research of adsorption of fluoride on cerium oxide hydrate. Some adsorption of fluoride by CTA adsorbent experiments were carried out, and results showed that CTA adsorbent has a quick adsorption speed and a large adsorption capacity. Adsorption follows Freundlich isotherm, and low pH value helps fluoride removal. Some physical-chemical characteristics of CTA adsorbent were experimented, fluoride removal mechanism was explored, and results showed that hydroxyl group of CTA adsorbent played an important role in the fluoride removal.

  15. Development of a zinc-cerium redox flow battery

    OpenAIRE

    Leung, P. K.

    2011-01-01

    Redox flow batteries (RFBs) can be used to store energy on the large and medium scale (kW – MW), particularly in applications such as load levelling of electrical power supplies, power quality control application and facilitating renewable energy deployment. In this thesis, the development of a divided and undivided zinc-cerium redox flow battery from its fundamental chemistry in aqueous methanesulfonic acid has been described. This comprehensive investigation has focused on th...

  16. Purification of cerium, neodymium and gadolinium for low background experiments

    OpenAIRE

    Boiko R.S.; Barabash A.S.; Belli P.; Bernabei R.; Cappella F.; Cerulli R.; Danevich F.A.; Incicchitti A.; Laubenstein M.; Mokina V.M.; Nisi S.; Poda D.V.; Polischuk O.G.; Tretyak V.I.

    2014-01-01

    Cerium, neodymium and gadolinium contain double beta active isotopes. The most interesting are 150Nd and 160Gd (promising for 0ν2β search), 136Ce (2β+ candidate with one of the highest Q2β). The main problem of compounds containing lanthanide elements is their high radioactive contamination by uranium, radium, actinium and thorium. The new generation 2β experiments require development of methods for a deep purification of lanthanides from the radioactive elements. A combination of physical an...

  17. Properties of ceramics based on cerium dioxide with crystalline filaments

    International Nuclear Information System (INIS)

    Problems of the increase of thermal resistance of ceramics on the basis of cerium dioxide with the interduction of filamentous crystals (FC) of CeO2 and MgO have been considered. It is established that FC of MgO and CeO2 are dissolved in the matrix, foAming fine oblong pores, promoting relaxation of thermal strains and preventing crack propagation, which increases the material thermal resistance

  18. Antioxidant Cerium Oxide Nanoparticles in Biology and Medicine

    OpenAIRE

    Nelson, Bryant C.; Monique E. Johnson; Walker, Marlon L.; Riley, Kathryn R.; Christopher M. Sims

    2016-01-01

    Previously, catalytic cerium oxide nanoparticles (CNPs, nanoceria, CeO2-x NPs) have been widely utilized for chemical mechanical planarization in the semiconductor industry and for reducing harmful emissions and improving fuel combustion efficiency in the automobile industry. Researchers are now harnessing the catalytic repertoire of CNPs to develop potential new treatment modalities for both oxidative- and nitrosative-stress induced disorders and diseases. In order to reach the point where o...

  19. Monomers, Dimers, and Helices: Complexities of Cerium and Plutonium Phenanthrolinecarboxylates.

    Science.gov (United States)

    Cary, Samantha K; Ferrier, Maryline G; Baumbach, Ryan E; Silver, Mark A; Lezama Pacheco, Juan; Kozimor, Stosh A; La Pierre, Henry S; Stein, Benjamin W; Arico, Alexandra A; Gray, Danielle L; Albrecht-Schmitt, Thomas E

    2016-05-01

    The reaction of Ce(III) or Pu(III) with 1,10-phenanthroline-2,9-dicarboxylic acid (PDAH2) results in the formation of new f-element coordination complexes. In the case of cerium, Ce(PDA)(H2O)2Cl·H2O (1) or [Ce(PDAH)(PDA)]2[Ce(PDAH)(PDA)] (2) was isolated depending on the Ce/ligand ratio in the reaction. The structure of 2 is composed of two distinct substructures that are constructed from the same monomer. This monomer is composed of a Ce(III) cation bound by one PDA(2-) dianionic ligand and one PDAH(-) monoanionic ligand, both of which are tetradentate. Bridging by the carboxylate moieties leads to either [Ce(PDAH)(PDA)]2 dimers or [Ce(PDAH)(PDA)]1∞ helical chains. For plutonium, Pu(PDA)2 (3) was the only product isolated regardless of the Pu/ligand ratio employed in the reaction. During the reaction of plutonium with PDAH2, Pu(III) is oxidized to Pu(IV), generating 3. This assignment is consistent with structural metrics and the optical absorption spectrum. Ambiguity in the assignment of the oxidation state of cerium in 1 and 2 from UV-vis-near-IR spectra invoked the use of Ce L3,2-edge X-ray absorption near-edge spectroscopy, magnetic susceptibility, and heat capacity measurements. These experiments support the assignment of Ce(III) in both compounds. The bond distances and coordination numbers are also consistent with these assignments. 3 contains 8-coordinate Pu(IV), whereas the cerium centers in 1 and 2 are 9- and/or 10-coordinate, which correlates with the increased size of Ce(III) versus Pu(IV). Taken together, these data provide an example of a system where the differences in the redox behavior between these f elements creates more complex chemistry with cerium than with plutonium. PMID:27070401

  20. Fungus mediated synthesis of biomedically important cerium oxide nanoparticles

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • First time biological synthesis of cerium oxide oxide nanoparticles using fungus Humicola sp. • Complete characterization of cerium oxide nanoparticles. • Biosynthesis of naturally protein capped, luminescent and water dispersible CeO2 nanoparticles. • Biosynthesized CeO2 nanoparticles can be used for many biomedical applications. - Abstract: Nanomaterials can be synthesized by chemical, physical and the more recently discovered biological routes. The biological routes are advantageous over the chemical and physical ones as unlike these, the biological synthesis protocols occur at ambient conditions, are cheap, non-toxic and eco-friendly. Although purely biological and bioinspired methods for the synthesis of nanomaterials are environmentally benign and energy conserving processes, their true potential has not been explored yet and attempts are being made to extend the formation of technologically important nanoparticles using microorganisms like fungi. Though there have been reports on the biosynthesis of oxide nanoparticles by our group in the past, no attempts have been made to employ fungi for the synthesis of nanoparticles of rare earth metals or lanthanides. Here we report for the first time, the bio-inspired synthesis of biomedically important cerium oxide (CeO2) nanoparticles using the thermophilic fungus Humicola sp. The fungus Humicola sp. when exposed to aqueous solutions of oxide precursor cerium (III) nitrate hexahydrate (CeN3O9·6H2O) results in the extracellular formation of CeO2 nanoparticles containing Ce (III) and Ce (IV) mixed oxidation states, confirmed by X-ray Photoemission Spectroscopy (XPS). The formed nanoparticles are naturally capped by proteins secreted by the fungus and thus do not agglomerate, are highly stable, water dispersible and are highly fluorescent as well. The biosynthesized nanoparticles were characterized by UV–vis spectroscopy, Photoluminescence spectroscopy (PL), Transmission

  1. Post-CMOS FinFET integration of bismuth telluride and antimony telluride thin-film-based thermoelectric devices on SoI substrate

    KAUST Repository

    Aktakka, Ethem Erkan

    2013-10-01

    This letter reports, for the first time, heterogeneous integration of bismuth telluride (Bi2Te3) and antimony telluride (Sb 2Te3) thin-film-based thermoelectric ffect transistors) via a characterized TE-film coevaporationand shadow-mask patterning process using predeposition surface treatment methods for reduced TE-metal contact resistance. As a demonstration vehicle, a 2 × 2 mm2-sized integrated planar thermoelectric generator (TEG) is shown to harvest 0.7 μ W from 21-K temperature gradient. Transistor performance showed no significant change upon post-CMOS TEG integration, indicating, for the first time, the CMOS compatibility of the Bi2Te3 and Sb2Te3 thin films, which could be leveraged for realization of high-performance integrated micro-TE harvesters and coolers. © 2013 IEEE.

  2. Jet formation in cerium metal to examine material strength

    International Nuclear Information System (INIS)

    Examining the evolution of material properties at extreme conditions advances our understanding of numerous high-pressure phenomena from natural events like meteorite impacts to general solid mechanics and fluid flow behavior. Recent advances in synchrotron diagnostics coupled with dynamic compression platforms have introduced new possibilities for examining in-situ, spatially resolved material response with nanosecond time resolution. In this work, we examined jet formation from a Richtmyer-Meshkov instability in cerium initially shocked into a transient, high-pressure phase, and then released to a low-pressure, higher-temperature state. Cerium's rich phase diagram allows us to study the yield stress following a shock induced solid-solid phase transition. X-ray imaging was used to obtain images of jet formation and evolution with 2–3 μm spatial resolution. From these images, an analytic method was used to estimate the post-shock yield stress, and these results were compared to continuum calculations that incorporated an experimentally validated equation-of-state (EOS) for cerium coupled with a deviatoric strength model. Reasonable agreement was observed between the calculations and the data illustrating the sensitivity of jet formation on the yield stress values. The data and analysis shown here provide insight into material strength during dynamic loading which is expected to aid in the development of strength aware multi-phase EOS required to predict the response of matter at extreme conditions

  3. Enhancing cerium and plutonium solubility by reduction in borosilicate glass

    Science.gov (United States)

    Cachia, J.-N.; Deschanels, X.; Den Auwer, C.; Pinet, O.; Phalippou, J.; Hennig, C.; Scheinost, A.

    2006-06-01

    High-level radioactive wastes produced by spent fuel reprocessing containing fission and activation products as well as actinides are incorporated in a borosilicate glass. To ensure optimum radionuclide containment, the resulting glass must be as homogeneous as possible. Microscopic heterogeneity can arise from various processes including the excess loading of an element above its solubility limit. The current actinide loading limit is 0.4 wt%. Work is in progress to assess the actinide solubility in these glasses, especially for plutonium. Initially the actinides were simulated by lanthanides and hafnium. The results show that trivalent elements (La, Gd) exhibit greater solubility than tetravalent elements (Pu, Hf). Cerium is an interesting element because its oxidation state varies from IV to III depending on the process conditions, such as the temperature and redox potential of the melt. In order to quantify the solubility increase, cerium-doped glass samples were melted under reducing conditions by adding a reducing agent. The solubility observed at 1473 K increased significantly from 0.95 to 13.00 wt%. Several reducing compounds have been tested. This paper deals with this study and the application to reduce Pu(IV) to Pu(III). The reduction state was characterized by X-ray absorption spectroscopy (XANES) for plutonium and by chemical analysis for cerium. The material homogeneity was verified by optical and scanning electron microscopy. Preliminary findings concerning the reduction of Pu-doped glasses fabricated in hot cells are also discussed.

  4. Dissolution of cerium from cerium-based conversion coatings on Al 7075-T6 in 0.1 M NaCl solutions

    International Nuclear Information System (INIS)

    Highlights: ► Dissolution of cerium from cerium-based conversion coatings (CeCCs) on Al 7075-T6. ► Immersion of CeCCs in 0.1 M NaCl showed dissolution only possible at pH ⩽ 2. ► Corrosion protection of CeCCs is not provided by dissolution of cerium species. ► CeCCs corrosion protection mechanism differ from chromate-based conversion coatings. - Abstract: Cerium-based conversion coatings (CeCCs) were immersed in 0.1 M NaCl for ∼500 h over a range of pH (2.0–5.7) to investigate the dissolution of cerium species. Dissolution was detected by UV–vis spectroscopy only in the pH 2 solution. Similar cerium concentrations were detected from the dissolution of as-deposited and phosphate post-treated CeCCs. Solubility diagrams for Ce(OH)3, Ce(OH)4, CeO2, and CePO4 showed that only Ce(OH)3 was soluble in acidic conditions. Although pKsp(CePO4) ≈ pKsp(Ce(OH)3), the dissolution of the post-treated CeCCs was slightly higher than the as-deposited CeCCs. Thus, corrosion protection of CeCCs is not provided solely by dissolution of cerium species.

  5. The developments and challenges of cerium half-cell in zinc–cerium redox flow battery for energy storage

    International Nuclear Information System (INIS)

    Zinc–cerium redox flow batteries (ZCBs) are emerging as a very promising new technology with the potential to store a large amount of energy economically and efficiently, thanking to its highest thermodynamic open-circuit cell voltage among all the currently studied aqueous redox flow batteries. However, there are numerous scientific and technical challenges that must be overcome if this alluring promise is to turn into reality, from designing the battery structure, to optimizing the electrolyte compositions and elucidating the complex chemical reactions that occur during charge and discharge. This review article is the first summary of the most significant developments and challenges of cerium half-cell and the current understanding of their chemistry. We are certain that this review will be of great interest to audience over a broad range, especially in fields of energy storage, electrochemistry, and chemical engineering

  6. Induction of pulmonary fibrosis by cerium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Jane Y., E-mail: jym1@cdc.gov [Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505 (United States); Mercer, Robert R.; Barger, Mark; Schwegler-Berry, Diane; Scabilloni, James [Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505 (United States); Ma, Joseph K. [School of Pharmacy, West Virginia University, Morgantown, WV 26506 (United States); Castranova, Vincent [Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505 (United States)

    2012-08-01

    Cerium compounds have been used as a diesel engine catalyst to lower the mass of diesel exhaust particles, but are emitted as cerium oxide (CeO{sub 2}) nanoparticles in the diesel exhaust. In a previous study, we have demonstrated a wide range of CeO{sub 2}-induced lung responses including sustained pulmonary inflammation and cellular signaling that could lead to pulmonary fibrosis. In this study, we investigated the fibrogenic responses induced by CeO{sub 2} in a rat model at various time points up to 84 days post-exposure. Male Sprague Dawley rats were exposed to CeO{sub 2} by a single intratracheal instillation. Alveolar macrophages (AM) were isolated by bronchial alveolar lavage (BAL). AM-mediated cellular responses, osteopontin (OPN) and transform growth factor (TGF)-β1 in the fibrotic process were investigated. The results showed that CeO{sub 2} exposure significantly increased fibrotic cytokine TGF-β1 and OPN production by AM above controls. The collagen degradation enzymes, matrix metalloproteinase (MMP)-2 and -9 and the tissue inhibitor of MMP were markedly increased in the BAL fluid at 1 day- and subsequently declined at 28 days after exposure, but remained much higher than the controls. CeO{sub 2} induced elevated phospholipids in BAL fluid and increased hydroxyproline content in lung tissue in a dose- and time-dependent manner. Immunohistochemical analysis showed MMP-2, MMP-9 and MMP-10 expressions in fibrotic regions. Morphological analysis noted increased collagen fibers in the lungs exposed to a single dose of 3.5 mg/kg CeO{sub 2} and euthanized at 28 days post-exposure. Collectively, our studies show that CeO{sub 2} induced fibrotic lung injury in rats, suggesting it may cause potential health effects. -- Highlights: ► Cerium oxide exposure significantly affected the following parameters in the lung. ► Induced fibrotic cytokine OPN and TGF-β1 production and phospholipidosis. ► Caused imbalance of the MMP-9/ TIMP-1 ratio that favors fibrosis

  7. Induction of pulmonary fibrosis by cerium oxide nanoparticles

    International Nuclear Information System (INIS)

    Cerium compounds have been used as a diesel engine catalyst to lower the mass of diesel exhaust particles, but are emitted as cerium oxide (CeO2) nanoparticles in the diesel exhaust. In a previous study, we have demonstrated a wide range of CeO2-induced lung responses including sustained pulmonary inflammation and cellular signaling that could lead to pulmonary fibrosis. In this study, we investigated the fibrogenic responses induced by CeO2 in a rat model at various time points up to 84 days post-exposure. Male Sprague Dawley rats were exposed to CeO2 by a single intratracheal instillation. Alveolar macrophages (AM) were isolated by bronchial alveolar lavage (BAL). AM-mediated cellular responses, osteopontin (OPN) and transform growth factor (TGF)-β1 in the fibrotic process were investigated. The results showed that CeO2 exposure significantly increased fibrotic cytokine TGF-β1 and OPN production by AM above controls. The collagen degradation enzymes, matrix metalloproteinase (MMP)-2 and -9 and the tissue inhibitor of MMP were markedly increased in the BAL fluid at 1 day- and subsequently declined at 28 days after exposure, but remained much higher than the controls. CeO2 induced elevated phospholipids in BAL fluid and increased hydroxyproline content in lung tissue in a dose- and time-dependent manner. Immunohistochemical analysis showed MMP-2, MMP-9 and MMP-10 expressions in fibrotic regions. Morphological analysis noted increased collagen fibers in the lungs exposed to a single dose of 3.5 mg/kg CeO2 and euthanized at 28 days post-exposure. Collectively, our studies show that CeO2 induced fibrotic lung injury in rats, suggesting it may cause potential health effects. -- Highlights: ► Cerium oxide exposure significantly affected the following parameters in the lung. ► Induced fibrotic cytokine OPN and TGF-β1 production and phospholipidosis. ► Caused imbalance of the MMP-9/ TIMP-1 ratio that favors fibrosis. ► Cerium oxide particles were detected in

  8. Electrochemical behavior of carbon paper on cerium methanesulfonate electrolytes for zinc-cerium flow battery

    International Nuclear Information System (INIS)

    The voltammetric behavior of the Ce(III)/(IV) half-cell reaction in various electrolytes containing 0.6 M Ce was investigated on both pristine and metal-modified carbon paper (CP) electrodes at three different temperatures (25, 40 and 55 °C) in order to find the most favorable electrochemical conditions. The pristine CP displayed robust electrochemical performance for up to 200 repetitive CV cycles while the Pt loaded electrode’s performance was stable for only 70 cycles, even though the latter exhibited a more reversible behavior, moving from a quasi-reversible to a reversible system (Dox. = 4.0 × 10−6 cm2 s−1 and Dred. = 2.5 × 10−6 cm2 s−1). The In and La metal modified electrodes did not show any improvement with regard to the kinetics or reversibility of the reaction. The addition of 1 M H2SO4 to the base electrolyte enhanced the cerium reduction reaction by a factor of 3, (−7.2 × 10−3 A cm−2). The highest exchange current densities (jo) were achieved at 40 °C for the CP-Pt (1 × 10−3 A cm−2) attributable to the presence of the catalytic Pt. Elevated temperatures (40 and 55 °C) improved D and ΔEp. while also the mass transport parameters a) dynamic viscosity (∼1.5 mPa·s) and b) electrolytic conductivity (∼265 mS cm−1) of the Ce(III)/(IV) half-cell reaction. Overall, pristine CP and to a lesser extent CP-Pt demonstrated good stability with prolonged cycling and kinetics comparable with the ones of Pt and Pt based electrodes

  9. Thin-film cadmium telluride photovoltaics: ES and H issues, solutions, and perspectives

    International Nuclear Information System (INIS)

    Photovoltaics (PV) is a growing business worldwide, with new technologies evolving towards potentially large-volume production. PV use produces no emissions, thus offsetting many potential environmental problems. However, the new PV technologies also bring unfamiliar environment, safety, and health (ES and H) challenges that require innovative solutions. This is a summary of the issues, solutions, and perspectives associated with the use of cadmium in one of the new and important PV technologies: thin-film, cadmium telluride (CdTe) PV, which is being developed and commercialized by several companies including Solar Cells Inc. (Toledo, Ohio), BP Solar (Fairfield, California), and Matsushita (Japan). The principal ES and H issue for thin-film cadmium telluride PV is the potential introduction of cadmium--a toxic heavy metal--into the air or water. The amount of cadmium in thin-film PV, however, is quite small--one nickel cadmium flashlight battery has about as much cadmium (7 g) as a square meter of PV module using current technology--and a typical cordless power tool will have 5--10 batteries. CdTe modules are also very well sealed, limiting the chance of release. Nonetheless, minimizing the amount of cadmium in cadmium telluride modules and preventing the introduction of that cadmium into the environment is a top priority for National Renewable Energy Laboratory researchers and cadmium telluride PV manufacturers

  10. Stable, high efficiency thin film solar cells produced by electrodeposition of cadmium telluride

    Energy Technology Data Exchange (ETDEWEB)

    Turner, A.K.; Woodcock, J.M.; Ozsan, M.E.; Summers, J.G.; Barker, J.; Binns, S.; Buchanan, K.; Chai, C.; Dennison, S.; Hart, R.; Johnson, D.; Marshall, R.; Oktik, S.; Patterson, M.; Perks, R.; Roberts, S.; Sadeghi, M.; Sherborne, J.; Szubert, J.; Webster, S. (BP Solar, Solar House, Leatherhead (United Kingdom))

    1991-12-01

    The highest known efficiency of 9.5% for a 300x300 mm series interconnected cadmium telluride solar cell is reported. In addition, efficiencies of up to 13% have been measured for small cells based on electrodeposited CdTe. The stability of modules in outdoor tests is discussed and an outline is given of the device fabrication procedure. (orig.).

  11. IR Laser-Induced Synthesis of Nanostructured Gemanium Telluride in the Gas Phase

    Czech Academy of Sciences Publication Activity Database

    Pola, Josef; Pokorná, Dana; Diánez, M.J.; Sayagués, M.J.; Bastl, Zdeněk; Vorlíček, Vladimír

    2005-01-01

    Roč. 19, č. 7 (2005), s. 854-858. ISSN 0268-2605 R&D Projects: GA AV ČR(CZ) IAA4072107 Institutional research plan: CEZ:AV0Z40720504 Keywords : laser-induced decomposition * germanium telluride * pyrolysis Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 1.190, year: 2005

  12. Electrodeposition of bismuth telluride thermoelectric films from a nonaqueous electrolyte using ethylene glycol

    NARCIS (Netherlands)

    Nguyen, H.P.; Wu, M.; Su, J.; Vullers, R.J.M.; Vereecken, P.M.; Fransaer, J.

    2012-01-01

    Ethylene glycol was studied as an electrolyte for the electrodeposition of thermoelectric bismuth telluride films by cyclic voltammetry, rotating ring disk electrode and electrochemical quartz crystal microbalance (EQCM). The reduction of both Bi3+ and Te4+ ions proceeds in one step without the form

  13. Structural Engineering of Vacancy Defected Bismuth Tellurides for Thermo-electric Applications

    Directory of Open Access Journals (Sweden)

    Chumakov Y.

    2012-10-01

    Full Text Available Molecular Dynamics and ab-initio simulations are used to find the most stable stoichiometries of Bismuth Tellurides with vacancy defects. The interest is to decrease the thermal conductivity of these compounds a key point to achieve high figure of merits. A reduction of 70% of the thermal conductivity is observed with Te vacancies of only 5%.

  14. Direct growth of cerium oxide nanorods on diverse substrates for superhydrophobicity and corrosion resistance

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Cerium oxide nanorods were uniformly grown on diverse substrates. • Changes in growth conditions led to morphology evolution of cerium oxide nanostructures. • The grown cerium oxide nanostructures were single or poly crystalline. • Direct growth of cerium oxide nanorods made the diverse substrates superhydrophobic and anti-corrosive without any surface modifiers. - Abstract: Superhydrophobic surfaces with anti-corrosion properties have attracted great interest in many industrial fields, particularly to enhance the thermal performance of offshore applications such as heat exchangers, pipelines, power plants, and platform structures. Nanostructures with hydrophobic materials have been widely utilized to realize superhydrophobicity of surfaces, and cerium oxide has been highlighted due to its good corrosion resistive and intrinsically hydrophobic properties. However, few studies of direct growth of cerium oxide nanostructures on diverse substrates have been reported. Herein we report a facile hydrothermal method to directly grow cerium oxide nanorods on diverse substrates, such as aluminum alloy, stainless steel, titanium, and silicon. Diverse substrates with cerium oxide nanorods exhibited superhydrophobicity with no hydrophobic modifiers on their surfaces, and showed good corrosion resistive properties in corrosive medium. We believe our method could pave the way for realization of scalable and sustainable corrosion resistive superhydrophobic surfaces in many industrial fields

  15. EIS study of nano crystalline Ni-cerium oxide coating electrodeposition mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Hasannejad, H. [Department of Materials Science and Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Shahrabi, T., E-mail: Tshahrabi34@modares.ac.ir [Department of Materials Science and Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Jafarian, M. [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of); Rouhaghdam, A. Sabour [Department of Materials Science and Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

    2011-02-03

    Research highlights: > In this study a new procedure was used for electrodeposition of Ni-cerium oxide amorphous-nano crystalline composite coatings. The innovation of this method is that the metal and oxides are deposited simultaneously on the samples from the plating bath solution containing Ni ions and Ce ions with no powder added. - Abstract: In this study a novel procedure was used for the electrodeposition of Ni-cerium oxide nano crystalline composite coatings. The novelty of this method lies in the fact that the metal and the oxide are both deposited simultaneously on the substrate, directly from the plating bath containing Ni and Ce ions with no oxide powder addition. Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) were used to study the mechanisms of Ni-CeO{sub 2} nanocomposite coating deposition. The results indicated that the morphology of Ni-cerium oxide coatings varied based on the Ni:Ce ion ratio. When this ratio exceeds 100, sporadic distribution of cerium oxide in the Ni matrix occurred. On the other hand, when the aforementioned ratio was less than 100, it was found that Ni species were dispersed in a continuous film of cerium oxide. Furthermore, it was observed that Ni in Ni-cerium oxide composite coating was nanocrystalline, while cerium oxide was amorphous. Introduction of the cerium ions to the plating bath resulted in the reduction of the Ni grains average size.

  16. Electrodeposition of cerium from fused mixture of CeCl sub(3)+NaCl-KCl

    International Nuclear Information System (INIS)

    Metallic cerium has been prepared by fused salt electrolysis of 30% CeCl sub(3)+ NaCl-KCl (equimolar) mixture, in the temperature ranged 650-850 sup(0)C, in argon atmosphere. The metal nodules were collected from solidified salts bath. Analysis of these nodules has been done and a 97,3% metallic cerium was obtained. (author)

  17. EIS study of nano crystalline Ni-cerium oxide coating electrodeposition mechanism

    International Nuclear Information System (INIS)

    Research highlights: → In this study a new procedure was used for electrodeposition of Ni-cerium oxide amorphous-nano crystalline composite coatings. The innovation of this method is that the metal and oxides are deposited simultaneously on the samples from the plating bath solution containing Ni ions and Ce ions with no powder added. - Abstract: In this study a novel procedure was used for the electrodeposition of Ni-cerium oxide nano crystalline composite coatings. The novelty of this method lies in the fact that the metal and the oxide are both deposited simultaneously on the substrate, directly from the plating bath containing Ni and Ce ions with no oxide powder addition. Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) were used to study the mechanisms of Ni-CeO2 nanocomposite coating deposition. The results indicated that the morphology of Ni-cerium oxide coatings varied based on the Ni:Ce ion ratio. When this ratio exceeds 100, sporadic distribution of cerium oxide in the Ni matrix occurred. On the other hand, when the aforementioned ratio was less than 100, it was found that Ni species were dispersed in a continuous film of cerium oxide. Furthermore, it was observed that Ni in Ni-cerium oxide composite coating was nanocrystalline, while cerium oxide was amorphous. Introduction of the cerium ions to the plating bath resulted in the reduction of the Ni grains average size.

  18. Direct growth of cerium oxide nanorods on diverse substrates for superhydrophobicity and corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Young Jun; Jang, Hanmin; Lee, Kwan-Soo [School of Mechanical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Dong Rip, E-mail: dongrip@hanyang.ac.kr [School of Mechanical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Institute of Nano Science and Technology, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2015-06-15

    Graphical abstract: - Highlights: • Cerium oxide nanorods were uniformly grown on diverse substrates. • Changes in growth conditions led to morphology evolution of cerium oxide nanostructures. • The grown cerium oxide nanostructures were single or poly crystalline. • Direct growth of cerium oxide nanorods made the diverse substrates superhydrophobic and anti-corrosive without any surface modifiers. - Abstract: Superhydrophobic surfaces with anti-corrosion properties have attracted great interest in many industrial fields, particularly to enhance the thermal performance of offshore applications such as heat exchangers, pipelines, power plants, and platform structures. Nanostructures with hydrophobic materials have been widely utilized to realize superhydrophobicity of surfaces, and cerium oxide has been highlighted due to its good corrosion resistive and intrinsically hydrophobic properties. However, few studies of direct growth of cerium oxide nanostructures on diverse substrates have been reported. Herein we report a facile hydrothermal method to directly grow cerium oxide nanorods on diverse substrates, such as aluminum alloy, stainless steel, titanium, and silicon. Diverse substrates with cerium oxide nanorods exhibited superhydrophobicity with no hydrophobic modifiers on their surfaces, and showed good corrosion resistive properties in corrosive medium. We believe our method could pave the way for realization of scalable and sustainable corrosion resistive superhydrophobic surfaces in many industrial fields.

  19. Cerium doped red mud catalytic ozonation for bezafibrate degradation in wastewater: Efficiency, intermediates, and toxicity.

    Science.gov (United States)

    Xu, Bingbing; Qi, Fei; Sun, Dezhi; Chen, Zhonglin; Robert, Didier

    2016-03-01

    In this study, the performance of bezafibrate (BZF) degradation and detoxification in the aqueous phase using cerium-modified red mud (RM) catalysts prepared using different cerium sources and synthesis methods were evaluated. Experimental results showed that the surface cerium modification was responsible for the development of the catalytic activity of RM and this was influenced by the cerium source and the synthesis method. Catalyst prepared from cerium (IV) by precipitation was found to show the best catalytic activity in BZF degradation and detoxification. Reactive oxygen species including peroxides, hydroxyl radicals, and super oxide ions were identified in all reactions and we proposed the corresponding catalytic reaction mechanism for each catalyst that prepared from different cerium source and method. This was supported by the intermediates profiles that were generated upon BZF degradation. The surface and the structural properties of cerium-modified RM were characterized in detail by several analytical methods. Two interesting findings were made: (1) the surface texture (specific surface area and mesoporous volume) influenced the catalytic reaction pathway; and (2) Ce(III) species and oxygen vacancies were generated on the surface of the catalyst after cerium modification. This plays an important role in the development of the catalytic activity. PMID:26706928

  20. Tuning Reactivity and Electronic Properties through Ligand Reorganization within a Cerium Heterobimetallic Framework

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Jerome R.; Gordon, Zachary; Booth, Corwin H.; Carroll, Patrick J.; Walsh, Patrick J.; Schelter, Eric J.

    2014-06-24

    Cerium compounds have played vital roles in organic, inorganic, and materials chemistry due to their reversible redox chemistry between trivalent and tetravalent oxidation states. However, attempts to rationally access molecular cerium complexes in both oxidation states have been frustrated by unpredictable reactivity in cerium(III) oxidation chemistry. Such oxidation reactions are limited by steric saturation at the metal ion, which can result in high energy activation barriers for electron transfer. An alternative approach has been realized using a rare earth/alkali metal/1,1'-BINOLate (REMB) heterobimetallic framework, which uses redox-inactive metals within the secondary coordination sphere to control ligand reorganization. The rational syntheses of functionalized cerium(IV) products and a mechanistic examination of the role of ligand reorganization in cerium(III) oxidation are presented.

  1. The recrystallization and texture of magnesium-zinc-cerium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mackenzie, L.W.F. [Novelis Global Technology Centre, 945 Princess Street, Kingston, Ontario, K7L 5L9 (Canada); Department of Mining and Materials Engineering, McGill University, 3610 University, Montreal, Quebec, H3A 2B2 (Canada)], E-mail: luke.mackenzie@novelis.com; Pekguleryuz, M.O. [Department of Mining and Materials Engineering, McGill University, 3610 University, Montreal, Quebec, H3A 2B2 (Canada)

    2008-09-15

    Optical microscopy, electron backscatter diffraction and X-ray diffraction are employed to characterize the microstructures and textures of as-rolled and annealed Mg-1Zn and Mg-1Zn-xCe. Mg-1Zn exhibited 'basal' textures: the basal poles aligned with the sheet normal direction. With the addition of cerium, the texture was basal when recrystallization was limited; during recrystallization, the basal texture component weakened, to be replaced by a component with basal poles rotated {approx}45 deg. towards the transverse direction. Deformation, recrystallization and texture are discussed.

  2. The recrystallization and texture of magnesium-zinc-cerium alloys

    International Nuclear Information System (INIS)

    Optical microscopy, electron backscatter diffraction and X-ray diffraction are employed to characterize the microstructures and textures of as-rolled and annealed Mg-1Zn and Mg-1Zn-xCe. Mg-1Zn exhibited 'basal' textures: the basal poles aligned with the sheet normal direction. With the addition of cerium, the texture was basal when recrystallization was limited; during recrystallization, the basal texture component weakened, to be replaced by a component with basal poles rotated ∼45 deg. towards the transverse direction. Deformation, recrystallization and texture are discussed

  3. Soil organic matter influences cerium translocation and physiological processes in kidney bean plants exposed to cerium oxide nanoparticles.

    Science.gov (United States)

    Majumdar, Sanghamitra; Peralta-Videa, Jose R; Trujillo-Reyes, Jesica; Sun, Youping; Barrios, Ana C; Niu, Genhua; Margez, Juan P Flores-; Gardea-Torresdey, Jorge L

    2016-11-01

    Soil organic matter plays a major role in determining the fate of the engineered nanomaterials (ENMs) in the soil matrix and effects on the residing plants. In this study, kidney bean plants were grown in soils varying in organic matter content and amended with 0-500mg/kg cerium oxide nanoparticles (nano-CeO2) under greenhouse condition. After 52days of exposure, cerium accumulation in tissues, plant growth and physiological parameters including photosynthetic pigments (chlorophylls and carotenoids), net photosynthesis rate, transpiration rate, and stomatal conductance were recorded. Additionally, catalase and ascorbate peroxidase activities were measured to evaluate oxidative stress in the tissues. The translocation factor of cerium in the nano-CeO2 exposed plants grown in organic matter enriched soil (OMES) was twice as the plants grown in low organic matter soil (LOMS). Although the leaf cover area increased by 65-111% with increasing nano-CeO2 concentration in LOMS, the effect on the physiological processes were inconsequential. In OMES leaves, exposure to 62.5-250mg/kg nano-CeO2 led to an enhancement in the transpiration rate and stomatal conductance, but to a simultaneous decrease in carotenoid contents by 25-28%. Chlorophyll a in the OMES leaves also decreased by 27 and 18% on exposure to 125 and 250mg/kg nano-CeO2. In addition, catalase activity increased in LOMS stems, and ascorbate peroxidase increased in OMES leaves of nano-CeO2 exposed plants, with respect to control. Thus, this study provides clear evidence that the properties of the complex soil matrix play decisive roles in determining the fate, bioavailability, and biological transport of ENMs in the environment. PMID:27343939

  4. Hydrothermal synthesis of cerium titanate nanorods and its application in visible light photocatalysis

    International Nuclear Information System (INIS)

    Highlights: • Cerium titanate nanorods have been synthesized by a simple hydrothermal process. • The size of the cerium titanate nanorods can be controlled by growth conditions. • Cerium titanate nanorods exhibit good photocatalytic activities for methyl blue. - Abstract: Cerium titanate nanorods have been prepared via a hydrothermal process using sodium dodecyl sulfate (SDS) as the surfactant. The cerium titanate nanorods have been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and ultraviolet–visible (UV–vis) diffuse reflectance spectrum. XRD shows that the nanorods are composed of CeTi21O38 phase. Electron microscopy observations indicate that the nanorods have good single crystalline nature. The diameter and length of the nanorods are about 50–200 nm and 1–2 μm, respectively. Cerium titanate nanorods have a band gap of 2.65 eV. The photocatalytic activities of the nanorods have been investigated by degrading methylene blue (MB) under visible light irradiation. MB solution with the concentration of 10 mg L−1 can be degraded totally with the irradiation time increasing to 240 min. Cerium titanate nanorods exhibit great potential in photocatalytic degradation of MB under visible light irradiation

  5. An environmentally compliant cerium-based conversion coating for aluminum protection

    Science.gov (United States)

    Lin, Xuan

    Chromate conversion coatings have been extensively used in the aircraft industry for the corrosion protection of aluminum alloys. Unfortunately, hexavalent chromium, which is a primary component in the chromating process, is a confirmed carcinogen. Because of rising remediation and disposal costs caused by increasingly strict regulations, the replacement of the traditional chromate conversion process is becoming a top priority in the metal finishing industry. This research focused on the electrodeposition of cerium-based coatings on 7075-T6 aluminum alloy in an electrolyte containing a cerium salt, an oxidizing agent and an organic solvent. The cerium-rich deposits were characterized by phase composition, oxidation state, coating thickness, surface morphology, deposition mechanism and polarization behavior. Chemical and electrochemical tests were utilized to compare the corrosion resistance between cerium-based coatings and chromate conversion coatings. To characterize and simulate the deposition process, a variety of approaches were utilized to study the oxidation states of cerium in various soluble and precipitated forms as a function of hydrogen peroxide and electrolyte pH. The pH ranges where the oxidation and reduction reactions dominate were determined. Further studies were performed to optimize the corrosion performance of cerium-based coatings and to understand the effects of electrolyte constituents and deposition parameters. The optimum levels for these variables were identified. A patent disclosure on the cerium-based coating process was made to the University of Missouri-Rolla and has now been officially filed with the U.S. Patent Office.

  6. X-ray absorption study of cerium in the passive film on aluminum

    International Nuclear Information System (INIS)

    The corrosion-resistance of aluminum-based alloys and metal-matrix composites can be increased by treatment with cerium compounds. Immersion in a 1000 ppm solution of Ce Cl3 for periods of several days has been shown to increase the pitting potential and reduce the corrosion rate. Such treatment is being considered as an alternative to the use of chromate conversion coatings. The protective action of cerium is considered to be due to the formation of a film containing cerium oxide/hydroxide with cerium in the oxidation states 3 and 4. This occurs by precipitation of cerium compounds onto cathodic sites due to the increase of pH associated with oxygen reduction. Cerium compounds are considerably less soluble than aluminum compounds at high pH. It is proposed that the cerium oxide/hydroxide creates a barrier to the reduction of oxygen stifling cathodic reaction with a corresponding reduction in corrosion rate and open circuit potential. Glancing angle x-ray techniques are well-suited to studying the composition and structure of surface layers on materials. X-rays incident at very small angles (of the order of milliradians) below the critical angle do not penetrate beyond the surface layers of the material. With the extremely high brightness beams of x-rays provided by synchrotron sources the authors detect and characterize the chemical state of elements present in low concentrations in the surface of materials

  7. The solubility of cerium in La2Ti2O7 by DFT + U calculations

    International Nuclear Information System (INIS)

    To investigate the solubility of cerium in La2Ti2O7, the density functional theory plus Hubbard U correction (DFT + U) approach is employed. The geometrical structure, solution energy and electronic structure of La2−yCeyTi2O7 (0 ≤ y ≤ 2) have been analyzed. The results reveal that the La2Ti2O7–Ce2Ti2O7 solid solution exits over the entire range of cerium content. The calculated increase in the O48f positional parameter, x, with increasing cerium content, may indicate the increased radiation resistance. The results of the density of states distribution and the Bader charge for each ion in La2Ti2O7–Ce2Ti2O7 solid solution suggest that cerium exhibits a reduced charge state in the solid solution. - Highlights: • La2Ti2O7–Ce2Ti2O7 solid solution exits over the entire range of cerium content from 0 to 2. • Cerium incorporation in La2Ti2O7 may lead to increased radiation resistance of La2−yCeyTi2O7 (0 ≤ y ≤ 2) . • Cerium in the solid solution of La2−yCeyTi2O7 (0 ≤ y ≤ 2) exhibits a reduced charge state

  8. Novel in situ coordinated cerium salt/acrylonitrile-butadiene rubber composite

    International Nuclear Information System (INIS)

    A novel rubber composite of acrylonitrile-butadiene rubber (NBR) filled with cerium salt particles was vulcanized via in situ coordination for the first time. The resulting materials exhibit good mechanical properties. Curing characteristics analysis, differential scanning calorimetry, X-ray photoelectron spectroscopy, tensile testing, and an equilibrium swelling method were used for the characterization of the composite. The results in this paper indicate that the composite is a kind of elastomer based on the in situ coordination crosslinking interactions between the nitrile groups (–CN) of NBR and cerium ions. The mechanical properties of vulcanized cerium salt/ NBR rubber are altered when changing the sorts of cerium salt. Moreover, these materials show good irradiation resistance because of the introduction of the cerium salt. -- Highlights: ► Cerium salts were firstly used to vulcanize the acrylonitrile-butadiene rubber. ► Cerium salts act as not only crosslink agents but also reinforcing fillers in the matrix. ► These materials show good irradiation resistance and mechanical properties at same time.

  9. Characterization of microstructure and catalytic of cerium oxide obtained by colloidal solution

    International Nuclear Information System (INIS)

    This study investigated to obtain particles of cerium oxide, for use as catalysts for the combustion of methane using the technique of through polymeric colloidal solution. Obtaining the colloidal system is based on hydrolysis of salts such as cerium acetylacetonate, cerium nitrate in the presence of additives such as polyvinylbutyral (PVB), polyvinylpyrrolidone (PVP) and polyvinyl acetate (PVA), at concentrations of 5, 10 and 15% in aqueous or alcoholic medium. These solutions containing ions of interest were subjected to a heat treatment at 650° C for 30 minutes, with heating rate of 2 ° C/ min. After heat treatment, the fibers were characterized according to their morphology, surface area, crystallinity, weight loss and catalytic activity. Samples obtained from cerium acetylacetonate were more reactive than the cerium nitrate to the combustion of methane, as showed greater conversions and higher temperatures reached during the process, which is of utmost importance since the combustion catalytic methane is used for generating thermal energy. After the reaction with methane, the samples underwent significant change in surface area, probably due to the intensity of combustion reactions of the nitrate and the generation of heat involved in this reaction, which gave rise to coarse particles. During the combustion process using the obtained from particles of cerium acetylacetonate, there was the release of large quantities of nitrogen compared to the results of assays with the particles obtained with cerium nitrate. (author)

  10. Mesoscopic structure of cerium waste loaded hydrated cement by SANS

    International Nuclear Information System (INIS)

    Cementation is one of the most commonly used methods for conditioning radioactive wastes. It provides a cost-effective solution for encapsulation of low and intermediate level radioactive wastes into suitable solid form for long term safety storage. Cerium is used for decontamination of alpha contaminated metallic waste and after this decontamination process, secondary wastes with corrosion products are created, which must be managed properly and cemented for near surface disposal. In the present work, modification of mesoscopic structure in hydrated cement due to addition of simulated cerium waste at different concentrations has been investigated by small-angle neutron scattering (SANS). Structural modifications, in mesoscopic length scale, have been observed. The scattering profiles for three kinds of cement blocks (virgin, 10 g/l and 20 g/l of corrosion product (C.P.) with 4 mm thickness) are shown. Data have been analyzed in the light of polydisperse spherical particles model assuming a log-normal distribution. Widely separated bimodal particle size distributions best represent the present data. Further, it has been observed that the scattering profile obeys power-law (Q-n) behaviour in two domains of Q, which reflects the self-similar/self-affined morphology of the inhomogeneities. Estimated parameters from SANS data are tabulated. A comparison is shown mentioning the value of scattering radius of gyration, exponent values (η) and average particle size for each kind of hydrated cement sample. (author)

  11. Cerium fluoride nanoparticles protect cells against oxidative stress

    Energy Technology Data Exchange (ETDEWEB)

    Shcherbakov, Alexander B.; Zholobak, Nadezhda M. [Zabolotny Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, Kyiv D0368 (Ukraine); Baranchikov, Alexander E. [Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, Moscow 119991 (Russian Federation); Ryabova, Anastasia V. [Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow 119991 (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow 115409 (Russian Federation); Ivanov, Vladimir K., E-mail: van@igic.ras.ru [Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, Moscow 119991 (Russian Federation); National Research Tomsk State University, Tomsk 634050 (Russian Federation)

    2015-05-01

    A novel facile method of non-doped and fluorescent terbium-doped cerium fluoride stable aqueous sols synthesis is proposed. Intense green luminescence of CeF{sub 3}:Tb nanoparticles can be used to visualize these nanoparticles' accumulation in cells using confocal laser scanning microscopy. Cerium fluoride nanoparticles are shown for the first time to protect both organic molecules and living cells from the oxidative action of hydrogen peroxide. Both non-doped and terbium-doped CeF{sub 3} nanoparticles are shown to provide noteworthy protection to cells against the vesicular stomatitis virus. - Highlights: • Facile method of CeF{sub 3} and CeF{sub 3}:Tb stable aqueous sols synthesis is proposed. • Naked CeF{sub 3} nanoparticles are shown to be non-toxic and to protect cells from the action of H{sub 2}O{sub 2}. • CeF{sub 3} and CeF{sub 3}:Tb nanoparticles are shown to protect living cells against the vesicular stomatitis virus.

  12. Sorption removal of arsenic by cerium-exchanged zeolite P

    International Nuclear Information System (INIS)

    Modification of zeolite P was performed by exchanged of its sodium with cerium(III). The resulting cerium-exchanged zeolite P, (CeZP) did not change in its crystallinity compared to original zeolite. The CeZP was subsequently used to sorb As(V) from aqueous solution. Maximum sorption of As(V) by CeZP occurred at pH range 3-10. In addition, the sorption capacity increased with increasing initial As(V) concentrations. The sorption follows Langmuir model with maximum sorption capacity of 8.72 mg g-1 at 25 deg. C and increased to 23.42 mg g-1 at 90 deg. C, indicating an endothermic process. The arsenic sorption by CeZP was not affected by the present of nitrate, chloride, sulphate, carbonate and bromide but was reduced significantly in the presence of phosphate. This study shows that the as prepared CeZP was found effective for the removal of arsenic from wastewater sample of wood treatment industry

  13. New sunscreen materials based on amorphous cerium and titanium phosphate

    International Nuclear Information System (INIS)

    Cerium-titanium pyrophosphates Ce1-xTi xP2O7 (with x = 0, 0.50, and 1.0), which are novel phosphate materials developed as UV-shielding agents for use in cosmetics, were characterized by X-ray diffraction, X-ray fluorescent analysis, UV-vis reflectance, and Raman spectroscopy. Since the optical reflectance shifted to lower wavelengths by the crystallization of the phosphates and the stabilization of the amorphous state of the cerium-titanium pyrophosphates was carried out by doping niobium (Nb). Raman spectroscopic study of the phosphate showed that P-O-P bending and stretching modes decreased with the loading of Nb, accompanying with the formation of Nb-O stretching mode. Therefore, the increase in the amount of the non-bridging oxygen in the amorphous phosphate should be the reason for the inhibition of the crystallization. This stabilization is a significant improvement, which enables to apply these amorphous phosphates not only to cosmetics and paints, but also plastics and films

  14. Altering properties of cerium oxide thin films by Rh doping

    International Nuclear Information System (INIS)

    Highlights: • Thin films of ceria doped by rhodium deposited by RF magnetron sputtering. • Concentration of rhodium has great impact on properties of Rh–CeOx thin films. • Intensive oxygen migration in films with low concentration of rhodium. • Oxygen migration suppressed in films with high amount of Rh dopants. - Abstract: Ceria containing highly dispersed ions of rhodium is a promising material for catalytic applications. The Rh–CeOx thin films with different concentrations of rhodium were deposited by RF magnetron sputtering and were studied by soft and hard X-ray photoelectron spectroscopies, Temperature programmed reaction and X-ray powder diffraction techniques. The sputtered films consist of rhodium–cerium mixed oxide where cerium exhibits a mixed valency of Ce4+ and Ce3+ and rhodium occurs in two oxidation states, Rh3+ and Rhn+. We show that the concentration of rhodium has a great influence on the chemical composition, structure and reducibility of the Rh–CeOx thin films. The films with low concentrations of rhodium are polycrystalline, while the films with higher amount of Rh dopants are amorphous. The morphology of the films strongly influences the mobility of oxygen in the material. Therefore, varying the concentration of rhodium in Rh–CeOx thin films leads to preparing materials with different properties

  15. Cerium compounds in the fashion of the light actinides

    International Nuclear Information System (INIS)

    Researchers familiar with the light actinides easily recognize in cerium compounds a microcosm of the rich variety of properties seen in the light actinides. The parallelism seen between comparable cerium and actinide compounds strongly suggests that the same physical models are applicable. The most significant is the relative size of the f-orbital. Localization is generally tighter in Ce compounds than uranium compounds, making Ce roughly analogous to Np through Am. A way to see the actinide parallelism is to compare Hill plots. Compounds in the different regions of the plots (representing different physics) are isostructural compounds with the same companion (B) elements. The most common materials exhibiting a direct f-f interaction are the cubic Laves compounds. Accordingly, we have determined the band structures of CeRu2, CeRh2, CeIr2, CeOs2, and CeNi2. Compounds illustrative of the interaction of f-orbitals with ligand orbitals are the Cu3Au structured materials. Materials calculated in this class are CeRh3, CePd3, and CeSn3 - the materials of much interest as mixed valent. Although the focus is on the Ce compounds, calculations performed on uranium isomorphs are used to highlight the interesting physics

  16. Spectrophotometric determination of Cerium from Monazite Bangka using Tiron reagent

    International Nuclear Information System (INIS)

    To anticipate the analysis of individual rare earth element from monazite processing which have done at PTPBGN division and samples from other division of P2BGN, and to develop the Ce analysis method by spectrophotometric using tiron reagent. The purpose of the experiment is to find out the method and the condition of Ce analysis with high accuracy and applicable. The variable observation were cerium-tiron spectrum, pH, ligand concentration, buffer concentration, linearity, anion influence, limit detection, impurities of elements and complex stability. The complex of cerium-tiron produce the maximum absorption at 497.5 nm and stable until 8 hours. The optimum conditions of this method was : tiron concentration is 0.25 %, pH 8.5 with buffer solution sodium acetate is 0.3 M. Detection limit is 1.00 ppm and area of linearity between 1 - 100 ppm, and PO4, Fe, U and Ti was influence to this method. The content of Ce from 2 samples of monazite Bangka which determine by this method was 18%

  17. Cerium fluoride nanoparticles protect cells against oxidative stress

    International Nuclear Information System (INIS)

    A novel facile method of non-doped and fluorescent terbium-doped cerium fluoride stable aqueous sols synthesis is proposed. Intense green luminescence of CeF3:Tb nanoparticles can be used to visualize these nanoparticles' accumulation in cells using confocal laser scanning microscopy. Cerium fluoride nanoparticles are shown for the first time to protect both organic molecules and living cells from the oxidative action of hydrogen peroxide. Both non-doped and terbium-doped CeF3 nanoparticles are shown to provide noteworthy protection to cells against the vesicular stomatitis virus. - Highlights: • Facile method of CeF3 and CeF3:Tb stable aqueous sols synthesis is proposed. • Naked CeF3 nanoparticles are shown to be non-toxic and to protect cells from the action of H2O2. • CeF3 and CeF3:Tb nanoparticles are shown to protect living cells against the vesicular stomatitis virus

  18. The van Hemmen-Kondo model for disordered cerium systems

    International Nuclear Information System (INIS)

    The interplay between disorder and strong correlations has been observed experimentally in disordered cerium alloys such as Ce(Ni, Cu) or Ce(Pd, Rh). In the case of Ce(Ni, Cu) alloys with a Cu concentration x between 0.6 and 0.3, the first studies have shown a smooth transition with decreasing temperature from a spin glass phase to ferromagnetism; for x smaller than 0.2, a Kondo phase has been observed. The situation is more complicated now due to the recent observation of magnetic clusters. The competition between the Kondo effect, the spin glass (SG) and the ferromagnetic (FE) ordering has been extensively studied theoretically. The Kondo effect is described by the usual mean-field approximation; we have treated the SG behavior successively by the Sherrington-Kirkpatrick model, then by the Mattis model and finally by the van Hemmen model, which takes both a ferromagnetic part and a site-disorder random part for the intersite exchange interaction. We present here the results obtained by the van Hemmen-Kondo model: for a large Kondo exchange JK, a Kondo phase is obtained while, for smaller JK, the succession of an SG phase, a mixed SG-FE one and finally an FE one has been obtained with decreasing temperature. This model improves the theoretical description of disordered Kondo systems by providing a simpler approach for further calculations of magnetic clusters and can, therefore, account for recent experimental data on disordered cerium systems.

  19. New sunscreen materials based on amorphous cerium and titanium phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Masui, Toshiyuki [Department of Applied Chemistry, Faculty of Engineering and Handai Frontier Research Center, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Hirai, Hidekazu [Department of Applied Chemistry, Faculty of Engineering and Handai Frontier Research Center, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Imanaka, Nobuhito [Department of Applied Chemistry, Faculty of Engineering and Handai Frontier Research Center, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)]. E-mail: imanaka@chem.eng.osaka-u.ac.jp; Adachi, Gin-ya [Juri Institute for Environmental Science and Chemistry, College of Analytical Chemistry, 2-1-8 Temma, Kita-ku, Osaka 530-0043 (Japan)

    2006-02-09

    Cerium-titanium pyrophosphates Ce{sub 1-x}Ti {sub x}P{sub 2}O{sub 7} (with x = 0, 0.50, and 1.0), which are novel phosphate materials developed as UV-shielding agents for use in cosmetics, were characterized by X-ray diffraction, X-ray fluorescent analysis, UV-vis reflectance, and Raman spectroscopy. Since the optical reflectance shifted to lower wavelengths by the crystallization of the phosphates and the stabilization of the amorphous state of the cerium-titanium pyrophosphates was carried out by doping niobium (Nb). Raman spectroscopic study of the phosphate showed that P-O-P bending and stretching modes decreased with the loading of Nb, accompanying with the formation of Nb-O stretching mode. Therefore, the increase in the amount of the non-bridging oxygen in the amorphous phosphate should be the reason for the inhibition of the crystallization. This stabilization is a significant improvement, which enables to apply these amorphous phosphates not only to cosmetics and paints, but also plastics and films.

  20. GEOLOGY OF THE FLORENCIA GOLD – TELLURIDE DEPOSIT (CAMAGÜEY, CUBA AND SOME METALLURGICAL CONSIDERATIONS

    Directory of Open Access Journals (Sweden)

    López K Jesús M.

    2006-12-01

    Full Text Available This paper describes the results from a study of the Florencia gold-telluride deposit in Central Cuba, including mineralogical, petrographical, microprobe and chemical analysis. Valuable information is provided for the exploration, mining and processing of gold ores from other nearby deposits with similar characteristics. Results highlight changes in the mineralogical composition of the ores between the north and south sectors of the deposit, as reflected in metallurgical concentrates after beneficiation and flotation of samples from these sectors.
    It is shown that gold deposits of the Cretaceous Volcanic Arc of Cuba largely consist of native gold, telluride and pyrite, where arsenopyrite is almost absent. Traces of lead, zinc and cadmium are present in the periphery of the main ore zones.

  1. Synthesis of copper telluride nanowires using template-based electrodeposition method as chemical sensor

    Indian Academy of Sciences (India)

    Sandeep Arya; Saleem Khan; Suresh Kumar; Rajnikant Verma; Parveen Lehana

    2013-08-01

    Copper telluride (CuTe) nanowires were synthesized electrochemically from aqueous acidic solution of copper (II) sulphate (CuSO4.5H2O) and tellurium oxide (TeO2) on a copper substrate by template-assisted electrodeposition method. The electrodeposition was conducted at 30 °C and the length of nanowires was controlled by adjusting deposition time. Structural characteristics were examined using X-ray diffraction and scanning electron microscope which confirm the formation of CuTe nanowires. Investigation for chemical sensing was carried out using air and chloroform, acetone, ethanol, glycerol, distilled water as liquids having dielectric constants 1, 4.81, 8.93, 21, 24.55, 42.5 and 80.1, respectively. The results unequivocally prove that copper telluride nanowires can be fabricated as chemical sensors with enhanced sensitivity and reliability.

  2. Kelvin probe studies of cesium telluride photocathode for the AWA photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Velazquez, D.; Wisniewski, E. E.; Yusof, Z.; Harkay, K.; Spentzouris, L.; Terry, J. [Physics Department at Illinois Institute of Technology, Chicago, IL 60616 and High Energy Physics Division at Argonne National Laboratory, Lemont, IL 60439 (United States); High Energy Physics Division at Argonne National Laboratory, Lemont, IL 60439 (United States); Accelerator Science Division at Argonne National Laboratory, Lemont, IL 60439 (United States); Physics Department at Illinois Institute of Technology, Chicago, IL 60616 (United States)

    2012-12-21

    Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (> 1%), is robust in a photoinjector, and long lifetime. This photocathode is fabricated in-house for a new Argonne Wakefield Accelerator (AWA) beamline to produce high charge per bunch ({approx}50 nC) in a long bunch train. We present some results from a study of the work function of cesium telluride photocathode using the Kelvin Probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the effect of UV light exposure on the work function, and the evolution of the work function during and after photocathode rejuvenation via heating.

  3. Ab initio lattice dynamics and thermochemistry of layered bismuth telluride (Bi2Te3)

    Science.gov (United States)

    Zurhelle, Alexander F.; Deringer, Volker L.; Stoffel, Ralf P.; Dronskowski, Richard

    2016-03-01

    We present density-functional theory calculations of the lattice dynamics of bismuth telluride, yielding force constants, mean-square displacements and partial densities of phonon states which corroborate and complement previous nuclear inelastic scattering experiments. From these data, we derive an element- and energy-resolved view of the vibrational anharmonicity, quantified by the macroscopic Grüneisen parameter γ which results in 1.56. Finally, we calculate thermochemical properties in the quasiharmonic approximation, especially the heat capacity at constant pressure and the enthalpy of formation for bismuth telluride; the latter arrives at ▵H f (Bi2Te3)  =  -102 kJ mol-1 at 298 K.

  4. Transport properties of silver telluride in the solid and liquid states

    International Nuclear Information System (INIS)

    Measurements of the electrical resistivity, Hall coefficient and thermoelectric power have been carried out for silver telluride over a large temperature range including both solid and liquid states. The analysis of the experimental data shows that in the solid state the transport properties are governed by an ambipolar process with an electron mobility much higher than the hole mobility (μn = 10*μp). It is found that the temperature dependence of the electron mobility can be represented by a T-3 law. Deviations from the stoichiometric composition Ag2Te have been studied. For all specimens, melting is accompanied by discontinuous variations in the transport properties. Above the melting point, the magnitude of the measured parameters and their temperature dependence show that liquid silver telluride behaves as a semiconductor. The contribution of Ag+ ions to transport phenomena is suggested to account for the behaviour of the electrical properties. Experimental data have been analysed in terms of conventional theories. (author)

  5. [Ion chromatography of L-ascorbic acid, sulfite and thiosulfate using their postcolumn reactions with cerium (IV) and fluorescence detection of cerium (III)].

    Science.gov (United States)

    Chen, Q; Hu, K; Miura, Y

    1999-09-01

    An ion chromatographic method was used to separate the species of L-ascorbic acid, sulfite and thiosulfate in their mixtures. This method is based on the separation of each anion in their mixtures by using a separation column, and then on the fluorimetric measurement of cerium (III) formed by a postcolumn reaction of cerium (IV) with the species of L-ascorbic acid, sulfite and thiosulfate in the effluent. The optimal conditions for separating and determining the above three species have been established. By using a 3 mmol/L carbonate eluent, the species of L-ascorbic acid, sulfite and thiosulfate could be eluted at the proper retention times of 1.7, 2.6 and 5.0 min, respectively, and these three anions could be separated completely. The effects of the concentrations of cerium (IV) and sulfuric acid in the postcolumn reaction solution on the chromatographic peak-height were tested in order to obtain the optimal peak-height. It was found that the peak-height at first increases rapidly with an increase in the concentration of cerium (IV) and sulfuric acid respectively up to a certain concertation, then increases slowly. These critical concentrations of cerium (IV) and sulfuric acid also depend on the amount of the analyte injected. Meanwhile the baseline signals of the sepectra increase with an increase in the concentration of cerium (IV). Some concentrations above the critical concentration of sulfuric acid could be selected as the optimal concentration of sulfuric acid, but the concentration of cerium (IV) should be optimized by establishing a compromise between the higher peak-height and the lower baseline signal. The detection limit of this method was found to be 1 mumol/L for thiosulfate when an amount of 100 microL analyte was injected. PMID:12552889

  6. Evaluation of Fully 3-D Emission Mammotomography With a Compact Cadmium Zinc Telluride Detector

    OpenAIRE

    Brzymialkiewicz, Caryl N.; Martin P. Tornai; McKinley, Randolph L.; Bowsher, James E.

    2005-01-01

    A compact, dedicated cadmium zinc telluride (CZT) gamma camera coupled with a fully three-dimensional (3-D) acquisition system may serve as a secondary diagnostic tool for volumetric molecular imaging of breast cancers, particularly in cases when mammographic findings are inconclusive. The developed emission mammotomography system comprises a medium field-of-view, quantized CZT detector and 3-D positioning gantry. The intrinsic energy resolution, sensitivity and spatial resolution of the dete...

  7. Mitochondrial Toxicity of Cadmium Telluride Quantum Dot Nanoparticles in Mammalian Hepatocytes

    OpenAIRE

    Nguyen, Kathy C; Rippstein, Peter; Tayabali, Azam F.; Willmore, William G.

    2015-01-01

    There are an increasing number of studies indicating that mitochondria are relevant targets in nanomaterial-induced toxicity. However, the underlying mechanisms by which nanoparticles (NPs) interact with these organelles and affect their functions are unknown. The aim of this study was to investigate the effects of cadmium telluride quantum dot (CdTe-QD) NPs on mitochondria in human hepatocellular carcinoma HepG2 cells. CdTe-QD treatment resulted in the enlargement of mitochondria as examined...

  8. On the active volume of cadmium zinc telluride gamma-ray spectrometers

    International Nuclear Information System (INIS)

    In this paper the authors develop quantitative models to predict the active volume of cadmium zinc telluride (CZT) detectors operated as gamma-ray pulse height spectrometers. Three cases are considered: a conventional planar detector, a unipolar device, and a detector in which electronic signal processing has been applied to correct for charge trapping effects. The find that existing detectors are very limited in their maximum attainable active volume, but unipolar devices with charge correction show promise for producing large active volume devices

  9. The first trialkylphosphane telluride complexes of Ag(I): molecular, ionic and supramolecular structural alternatives.

    Science.gov (United States)

    Daniliuc, Constantin; Druckenbrodt, Christian; Hrib, Cristian G; Ruthe, Frank; Blaschette, Armand; Jones, Peter G; du Mont, Wolf-W

    2007-05-28

    The structures of the first phosphane telluride complexes of silver(I), obtained from i-Pr3PTe (1) with AgNMs2 [Ms = SO2CH3] and with AgSbF6, reveal the superior coordinating ability of 1, particularly as a bridging ligand, compared with related i-Pr3PS and i-Pr3PSe ligands. PMID:17713078

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

    Science.gov (United States)

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

    2016-05-01

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

  11. Violet/blue emission from epitaxial cerium oxide films on silicon substrates

    International Nuclear Information System (INIS)

    Violet/blue photoluminescence was observed from epitaxial cerium oxide films on silicon substrates. The films were deposited on silicon (111) substrates under ultrahigh vacuum conditions using pulsed laser ablation of a cerium oxide target and treated by rapid thermal annealing in argon. High resolution transmission electron microscopy and x-ray diffraction measurements indicated the formation of a single crystal cerium oxide phase Ce6O11 different from CeO2 in the annealed films. The emission might be due to charge transfer transitions from the 4f band to the valence band of the oxide. copyright 1997 American Institute of Physics

  12. The study on preparation of high dispersion and pure cerium dioxide for producing automotive exhaust catalysts

    International Nuclear Information System (INIS)

    The multi-stage counter-current solvent extraction process using TBP as the solvent has been carried out for purifying cerium and the ammonium carbonate precipitation method has been used to produce the cerium oxide of high dispersion and pure. The flow sheet of extraction system includes 3 extraction stages with O/A = 0.7,2 stripping stages and 4 scrubbing stages with O/A = 5. The condition for ammonium carbonate precipitation, drying and calcination have been investigated and a procedure that seem to be practically suitable to prepare cerium dioxide powder with great specific surface area for producing automotive exhaust catalyst has been proposed. (LMT)

  13. Effect of Cerium on Mechanical Properties and Morphology of ZZn4-1 Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Effect of the addition of cerium in appropriate amount on the mechanical properties and morphology of ZZn4-1 alloy was investigated. In the case of samples collected from metal mould, the results show that the addition of cerium in appropriate amount can increase tensile strength and HB hardness, and can refine the microstructure of ZZn4-1 alloy considerably. In the case of samples collected from pressure die-casting, the addition of cerium in appropriate amount can refine the primary η-phase and the eutectic structure of pressure die-casting and improve mechanical and processing properties of the alloy.

  14. Ion exchange reactions in amorphous and crystalline aluminium silicates from solution of cerium salts

    International Nuclear Information System (INIS)

    Reactions of ion-exchange of Na+ by Ce3+ and NH4+ on the zeolite containing catalyst, amorphous silica alumina and zeolite Y have been studied. The cerium cations are shown to be exchanged by the Na+ cations with more selectivity than the anmonia cations. In the case of the zeolite containing catalyst and amorphous silica alumina the region of the staggered ion-exchange from the mixture of the solutions of cerium and ammonium sulphates was been detected. This is explained by the formation fo cerium complexes with the sulphate ions

  15. Electronic characterization of defects in narrow gap semiconductors: Comparison of electronic energy levels and formation energies in mercury cadmium telluride, mercury zinc telluride, and mercury zinc selenide

    Science.gov (United States)

    Patterson, James D.; Li, Wei-Gang

    1995-01-01

    The project has evolved to that of using Green's functions to predict properties of deep defects in narrow gap materials. Deep defects are now defined as originating from short range potentials and are often located near the middle of the energy gap. They are important because they affect the lifetime of charge carriers and hence the switching time of transistors. We are now moving into the arena of predicting formation energies of deep defects. This will also allow us to make predictions about the relative concentrations of the defects that could be expected at a given temperature. The narrow gap materials mercury cadmium telluride (MCT), mercury zinc telluride (MZT), and mercury zinc selenide (MZS) are of interest to NASA because they have commercial value for infrared detecting materials, and because there is a good possibility that they can be grown better in a microgravity environment. The uniform growth of these crystals on earth is difficult because of convection (caused by solute depletion just ahead of the growing interface, and also due to thermal gradients). In general it is very difficult to grow crystals with both radial and axial homogeneity.

  16. Studies of solution deposited cerium oxide thin films on textured Ni-alloy substrates for YBCO superconductor

    International Nuclear Information System (INIS)

    Cerium oxide (CeO2) buffer layers play an important role for the development of YBa2Cu3O7-x (YBCO) based superconducting tapes using the rolling assisted biaxially textured substrates (RABiTS) approach. The chemical solution deposition (CSD) approach has been used to grow epitaxial CeO2 films on textured Ni-3 at.% W alloy substrates with various starting precursors of ceria. Precursors such as cerium acetate, cerium acetylacetonate, cerium 2-ethylhexanoate, cerium nitrate, and cerium trifluoroacetate were prepared in suitable solvents. The optimum growth conditions for these cerium precursors were Ar-4% H2 gas processing atmosphere, solution concentration levels of 0.2-0.5 M, a dwell time of 15 min, and a process temperature range of 1050-1150 deg. C. X-ray diffraction, AFM, SEM, and optical microscopy were used to characterize the CeO2 films. Highly textured CeO2 layers were obtained on Ni-W substrates with both cerium acetate and cerium acetylacetonate as starting precursors. YBCO films with a J c of 1.5 MA/cm2 were obtained on cerium acetylacetonate-based CeO2 films with sputtered YSZ and CeO2 cap layers

  17. The effect of different annealing temperatures on tin and cadmium telluride phases obtained by a modified chemical route

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted Highlights: ► Synthesis of cadmium and tin telluride. ► Chemical route to obtain pure crystalline cadmium and tin telluride. ► Effect of the annealing temperature on the crystalline phases. ► Removal of tin oxide as side product through thermal treatment. -- Abstract: In this work tin and cadmium telluride were prepared by a modification of a chemical route reported in the literature to obtain metallacycles formed by oxidative addition of tin-tellurium bonds to platinum (II). Through this procedure it was possible to obtain tin and cadmium telluride. X-ray diffraction and X-ray photoelectron spectroscopy were used to identify the crystalline phases obtained as well as the presence of side products. In the case of tin telluride it was identified potassium chloride, metallic tellurium and tin oxide as contaminants. The tin oxidation states were also monitored by 119Sn Mössbauer spectroscopy. The annealing in hydrogen atmosphere was chosen as a strategy to reduce the tin oxide and promote its reaction with the excess of tellurium present in the medium. The evolution of this tin oxide phase was studied through the annealing of the sample at different temperatures. Cadmium telluride was obtained with high degree of purity (98.5% relative weight fraction) according to the Rietveld refinement of X-ray diffraction data. The modified procedure showed to be very effective to obtain amorphous tin and cadmium telluride and the annealing at 450 °C has proven to be useful to reduce the amount of oxide produced as side product.

  18. Coulometric microdetermination of organic compounds with manganese(III) and cerium(IV)

    International Nuclear Information System (INIS)

    The oxidation of compounds such as hydroquinon, p-aminophenol, paracetamol and phenacetin was performed using cerium(IV) and manganese(III) coulometrically electrogenerated. Quantitative results obtained are excellent even at the microscale level. (author)

  19. Immobilization of simulated radioactive soil waste containing cerium by self-propagating high-temperature synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Xianhe, E-mail: maoxianhe@hotmail.com; Qin, Zhigui; Yuan, Xiaoning; Wang, Chunming; Cai, Xinan; Zhao, Weixia; Zhao, Kang; Yang, Ping; Fan, Xiaoling

    2013-11-15

    A simulated radioactive soil waste containing cerium as an imitator element has been immobilized by a thermite self-propagating high-temperature synthesis (SHS) process. The compositions, structures, and element leaching rates of products with different cerium contents have been characterized. To investigate the influence of iron on the chemical stability of the immobilized products, leaching tests of samples with different iron contents with different leaching solutions were carried out. The results showed that the imitator element cerium mainly forms the crystalline phases CeAl{sub 11}O{sub 18} and Ce{sub 2}SiO{sub 5}. The leaching rate of cerium over a period of 28 days was 10{sup −5}–10{sup −6} g/(m{sup 2} day). Iron in the reactants, the reaction products, and the environment has no significant effect on the chemical stability of the immobilized SHS products.

  20. Immobilization of simulated radioactive soil waste containing cerium by self-propagating high-temperature synthesis

    Science.gov (United States)

    Mao, Xianhe; Qin, Zhigui; Yuan, Xiaoning; Wang, Chunming; Cai, Xinan; Zhao, Weixia; Zhao, Kang; Yang, Ping; Fan, Xiaoling

    2013-11-01

    A simulated radioactive soil waste containing cerium as an imitator element has been immobilized by a thermite self-propagating high-temperature synthesis (SHS) process. The compositions, structures, and element leaching rates of products with different cerium contents have been characterized. To investigate the influence of iron on the chemical stability of the immobilized products, leaching tests of samples with different iron contents with different leaching solutions were carried out. The results showed that the imitator element cerium mainly forms the crystalline phases CeAl11O18 and Ce2SiO5. The leaching rate of cerium over a period of 28 days was 10-5-10-6 g/(m2 day). Iron in the reactants, the reaction products, and the environment has no significant effect on the chemical stability of the immobilized SHS products.

  1. Electroreduction of cerium ions on silver electrode in halide melts at 973 K

    International Nuclear Information System (INIS)

    The mechanism of electroreduction of cerium ions in equimolar KCl-NaCl melt is explored at 973 K. The effect of the anionic composition of the melt on the electroreduction of cerium ions is studied. It is shown that the electrodeposition of cerium metal from halide melts on a silver electrode is the primary electrochemical process that occurs at potentials more positive than those corresponding to the supporting-electrolyte decomposition. The electroreduction of chloride complexes of cerium on a silver electrode in the melt in both steady- and non-steady-state polarization modes at rates below V≤0.5 V/s is controlled by the diffusion delivery; at higher polarization rates, the charge-transfer stage predominates

  2. Electrochemical separation of uranium and cerium in molten LiCl-KCl

    International Nuclear Information System (INIS)

    The electrochemical separation of uranium from cerium in LiCl–KCl eutectic and the electrochemical behavior of Ce(III) were studied. According to the cyclic voltammogram of Ce(III) and the former result of U(III), electrodeposition potential was determined at -1.65 V (vs Ag/AgCl). The uranium metal was successfully deposited and separated from cerium. The morphology of deposit and cross section of electrode were investigated by SEM, firstly uranium deposit alloys with stainless steel and forms a thin transition layer, and secondly the uranium metal layer grows from the transition layer. The separation factors of uranium/cerium on different recovery ratios were determined through a series of steps. It was found that the content of cerium in the deposit and separation factors declined with increasing the initial concentration of U3+ in molten salts; the separation factors remained stable at around 20 in different uranium recovery ratios. (author)

  3. Synergistic extraction of uranium (VI), thorium (IV) and cerium (III) by thenoyltri-fluoroacetone and phenanthroline

    International Nuclear Information System (INIS)

    The synergistic extraction of uranium(VI), thorium(IV) and cerium(III) with thenoyltrifluoroacetone (HTTA) and phenanthroline (phen) is studied. The extraction equilibrium constants are calculated and the mechanism of the synergistic extraction has been discussed

  4. The low gas flow rate foam separation of cerium(III) from dilute aqueous solutions

    International Nuclear Information System (INIS)

    Two low gas flow rate foam separation techniques, ion and precipitate flotation, have been investigated for the separation of trivalent cerium from solutions with initial cerium concentrations ranging from 1 x 10-8 to 1 x 10-4M in the pH range of 1.8 to 12 using the anionic collector sodium lauryl sulphate and the cationic surfactant cetyl trymethyl ammonium bromide. In addition to the type of collector, the pH and the cerium ion concentration, and other factors which can affect flotation results, viz. the time period of bubbling, the rate of gas flow, the ageing of both the cerium and the collector ions, the ionic strength, and the concentration of the collector ions have been investigated and optimum conditions have been established. Under optimum conditions removals as high a 98.5% can be achieved. (author)

  5. Cerium-based conversion coatings to improve the corrosion resistance of aluminium alloy 6061-T6

    International Nuclear Information System (INIS)

    Highlights: • Cerium-based conversion coatings. • Cerium salt sources assisted with hydrogen peroxide. • Protective properties of the conversion coating. - Abstract: Cerium-based conversion coatings were deposited on aluminium alloy 6061-T6 by immersion in two cerium salt sources (chloride- and nitrate-based) assisted with hydrogen peroxide (H2O2). The morphology and composition of the coatings were analysed using scanning electron microscopy and energy dispersive X-ray spectroscopy. Electrochemical measurements to assess corrosion behaviour were performed using free corrosion potential, polarisation and electrochemical impedance spectroscopy with a 3% NaCl solution. The influence of H2O2 on the generation of the coating was studied by cyclic voltammetry tests. The protective properties of the coating generated are heavily dependent upon the chelating effect, chaotropic anion, the pH and H2O2 content

  6. Synergistic inhibition of carbon steel corrosion in seawater by cerium chloride and sodium gluconate

    International Nuclear Information System (INIS)

    Highlights: • Significant synergistic effect was determined for cerium and gluconate. • The mixture showed significant corrosion inhibition of carbon steel in seawater. • Predominant anodic inhibition mechanism was observed. • The presence of cerium ions incorporated in the protective layer was confirmed. - Abstract: In this research the effect of cerium (III) chloride heptahydrate (CC) and sodium gluconate (SG) on the corrosion inhibition of carbon steel C45 (1531) in natural seawater has been evaluated using electrochemical methods and scanning electron microscopy (SEM). The results show that substantial corrosion inhibition (94.98%) using CC and SG can be obtained in synergistic manner. Surface analysis confirmed the presence of cerium ions incorporated in the protective layer of carbon steel specimen. SG acts predominantly as anodic inhibitor whereas CC acts as a mixed type inhibitor. Using both inhibitors predominant mechanism of anodic inhibition is observed

  7. Cerium oxide for the destruction of chemical warfare agents: A comparison of synthetic routes

    Czech Academy of Sciences Publication Activity Database

    Janos, P.; Henych, Jiří; Pelant, O.; Pilařová, V.; Vrtoch, L.; Kormunda, M.; Mazanec, K.; Štengl, Václav

    2016-01-01

    Roč. 304, MAR (2016), s. 259-268. ISSN 0304-3894 Institutional support: RVO:61388980 Keywords : Cerium oxide * Chemical warfare agents * Organophosphate compounds * Decontamination Subject RIV: CA - Inorganic Chemistry Impact factor: 4.529, year: 2014

  8. Direct growth of cerium oxide nanorods on diverse substrates for superhydrophobicity and corrosion resistance

    Science.gov (United States)

    Cho, Young Jun; Jang, Hanmin; Lee, Kwan-Soo; Kim, Dong Rip

    2015-06-01

    Superhydrophobic surfaces with anti-corrosion properties have attracted great interest in many industrial fields, particularly to enhance the thermal performance of offshore applications such as heat exchangers, pipelines, power plants, and platform structures. Nanostructures with hydrophobic materials have been widely utilized to realize superhydrophobicity of surfaces, and cerium oxide has been highlighted due to its good corrosion resistive and intrinsically hydrophobic properties. However, few studies of direct growth of cerium oxide nanostructures on diverse substrates have been reported. Herein we report a facile hydrothermal method to directly grow cerium oxide nanorods on diverse substrates, such as aluminum alloy, stainless steel, titanium, and silicon. Diverse substrates with cerium oxide nanorods exhibited superhydrophobicity with no hydrophobic modifiers on their surfaces, and showed good corrosion resistive properties in corrosive medium. We believe our method could pave the way for realization of scalable and sustainable corrosion resistive superhydrophobic surfaces in many industrial fields.

  9. Inhibition of pH fronts in corrosion cells due to the formation of cerium hydroxide

    International Nuclear Information System (INIS)

    The effect of cerium-based corrosion inhibitors on the pH front between the alkaline cathode and acidic anode in corrosion cells has been studied. The cerium component of these inhibitors can affect the pH front since it precipitates in an alkaline environment as cerium hydroxide, which is important since the corrosion inhibition mechanism of the cerium component is a result of its deposition as a highly electrical resistive (passivation) layer on the cathode. It is studied whether the cerium can reach the cathode when fed into the corrosion cell from an external source after the onset of corrosion. To this end a simulation model was set up that includes the Poisson–Nernst–Planck theory to describe ion transport and the Frumkin–Butler–Volmer equation to describe charge transfer at the electrodes. In this model both the self-dissociation of water and the formation of cerium hydroxide are taken into account. To support our findings experimentally a corrosion cell consisting of an aluminum and copper electrode was used, in which the pH fronts were visualized using a pH-indicator. Two types of inhibitors were used; namely, highly soluble CeCl3 and sparsely soluble cerium dibutylphosphate, Ce(dbp)3. The results show that CeCl3 can reduce the size of the alkaline region and reach the cathode to form a passivation layer, whereas the solubility in case of Ce(dbp)3 is too low to supply sufficient amounts of trivalent cerium cations to penetrate the alkaline region. This behavior can be explained by the simulation results, which reveal a threshold for the corrosion inhibitor solubility below which no passivation of the cathode occurs

  10. Construction of heterocyclic structures by trivalent cerium salts promoted bond forming reactions.

    Science.gov (United States)

    Properzi, Roberta; Marcantoni, Enrico

    2014-02-01

    Cerium(III) salts have recently gained increasing attention in the synthetic community, owing to the powerful features that are reviewed in detail in this tutorial. This review reports significant examples of cerium(III) promoted synthesis of heterocyclic structures, initially dealing with the synthesis of five- and six-membered ring nitrogen containing heterocycles, then describing the preparation of their oxygenated analogues and finally discussing the achievement of seven-membered rings and mixed heterocyclic motifs. PMID:24217370

  11. Protein adsorption and cellular uptake of cerium oxide nanoparticles as a function of zeta potential

    OpenAIRE

    Patil, Swanand; Sandberg, Amanda; Heckert, Eric; Self, William; Seal, Sudipta

    2007-01-01

    The surface chemistry of biomaterials can have a significant impact on their performance in biological applications. Our recent work suggests that cerium oxide nanoparticles are potent antioxidants in cell culture models and we have evaluated several therapeutic applications of these nanoparticles in different biological systems. Knowledge of protein adsorption and cellular uptake will be very useful in improving the beneficial effects of cerium oxide nanoparticles in biology. In the present ...

  12. Effects of Morphology of Cerium Oxide Catalysts for Reverse Water Gas Shift Reaction

    OpenAIRE

    Kovasevic, M.; Mojet, B.L.; Ommen, van, B.; Lefferts, L.

    2016-01-01

    Reverse water gas shift reaction (RWGS) was investigated over cerium oxide catalysts of distinct morphologies: cubes, rods and particles. Catalysts were characterized by X-ray diffraction, Raman spectroscopy and temperature programmed reduction (TPR) in hydrogen. Nanoshapes with high concentration of oxygen vacancies contain less surface oxygen removable in TPR. Cerium oxide cubes exhibited two times higher activity per surface area as compared to rods and particles. Catalytic activity of the...

  13. Catalysts with Cerium in a Membrane Reactor for the Removal of Formaldehyde Pollutant from Water Effluents

    OpenAIRE

    Mirella Gutiérrez-Arzaluz; Luis Noreña-Franco; Saúl Ángel-Cuevas; Violeta Mugica-Álvarez; Miguel Torres-Rodríguez

    2016-01-01

    We report the synthesis of cerium oxide, cobalt oxide, mixed cerium, and cobalt oxides and a Ce–Co/Al2O3 membrane, which are employed as catalysts for the catalytic wet oxidation (CWO) reaction process and the removal of formaldehyde from industrial effluents. Formaldehyde is present in numerous waste streams from the chemical industry in a concentration low enough to make its recovery not economically justified but high enough to create an environmental hazard. Common biological degradation ...

  14. Energy-dispersive X-ray fluorescence analysis of cerium in ferrosilicon

    International Nuclear Information System (INIS)

    The cerium was determined in ferrosilicon samples by energy-dispersive X-ray fluorescence techniques (XRF) techniques, with a secondary target of gadolinium. The methods employed were: comparison and linear regression with reference materials with cerium concentration between 0.4 and 1.0%. The samples were prepared in the form of pellets and the analytical results are reported as an average of five determinations with a confidence limits at 95% probability. (Author)

  15. Imidazolium ionic liquids as solvents for cerium(IV)-mediated oxidation reactions

    OpenAIRE

    Mehdi, Hasan; Bodor, Andrea; Lantos, Diana; Horváth, István T; De Vos, Dirk; Binnemans, Koen

    2007-01-01

    Use of imidazolium ionic liquids as solvents for organic transformations with tetravalent cerium salts as oxidizing agents was evaluated. Good solubility was found for ammonium hexanitratocerate(IV) (ceric ammonium nitrate, CAN) and cerium(IV) triflate in 1-alkyl-3-methylimidazolium triflate ionic liquids. Oxidation of benzyl alcohol to benzaldehyde in 1-ethyl-3-methylimidazolium triflate was studied by in-situ FTIR spectroscopy and 13C NMR spectroscopy on carbon-13-labeled benzyl alcohol. Ca...

  16. A chemical cleaning process with Cerium (IV)-sulfuric acid

    International Nuclear Information System (INIS)

    A chemical cleaning process with a high decontamination factor (DF) is requested for decommissioning. Usually, the process should be qualified with the features, such as the feasibility of treating large or complicated form waste, the minimization of secondary waste. Therefore, a powerful technique of redox decontamination process with Ce+4/Ce+3 has been studied at INER. First, the redox of cerium ion with electrolytic method was developed. Two kinds of home-made electrolyzer were used. One is with an ion-exchange membrane, and the other one is with a ceramic separator. Second, factors influencing the decontamination efficiency, such as the concentration of Ce+4, regeneration current density, temperature, acidity of solution were all studied experimentally, and the optimum conditions were specified too. Third, the liquid waste recycling and treatment were developed with electrodialysis and ion-exchange absorption methods. Finally, the hot test was proceeded with the contaminated metals from DCR of nuclear facility. (author)

  17. Extraction behavior of cerium by tetraoctyldiglycolamide from nitric acid solutions

    International Nuclear Information System (INIS)

    The diamide N,N,N',N'-tetraoctyldiglycolamide (TODGA) was synthesized and characterized. The prepared TODGA was applied for extraction of Ce(III) from nitric acid solutions. The equilibrium studies included the dependencies of cerium distribution ratio on nitric acid, TODGA, nitrate ion, hydrogen ion and cerous ion concentrations. Analysis of the results indicates that the main extracted species is Ce(TODGA)2(NO3)3HNO3. The capacity of Ce loading is approximately 45 mmol/L for 0.1 M solution of TODGA in n-hexane. Finally, the thermodynamic parameters were calculated: K (25 deg C) = 3.8 x 103, ΔH = -36.7 ± 1.0 kJ/mol, ΔS = -54.6 ± 3.0 J/K mol, and ΔG = -20.4 ± 0.1 kJ/mol. (author)

  18. Deposition and investigation of lanthanum cerium hexaboride thin films

    Science.gov (United States)

    Kuzanyan, A. S.; Harutyunyan, S. R.; Vardanyan, V. O.; Badalyan, G. R.; Petrosyan, V. A.; Kuzanyan, V. S.; Petrosyan, S. I.; Karapetyan, V. E.; Wood, K. S.; Wu, H.-D.; Gulian, A. M.

    2006-09-01

    Thin films of lanthanum-cerium hexaboride, the promising thermoelectric material for low-temperature applications, are deposited on various substrates by the electron-beam evaporation, pulsed laser deposition and magnetron sputtering. The influence of the deposition conditions on the films X-ray characteristics, composition, microstructure and physical properties, such as the resistivity and Seebeck coefficient, is studied. The preferred (100) orientation of all films is obtained from XRD traces. In the range of 780-800 °C deposition temperature the highest intensity of diffractions peaks and the highest degree of the preferred orientation are observed. The temperature dependence of the resistivity and the Seebeck coefficient of films are investigated in the temperature range of 4-300 K. The features appropriate to Kondo effect in the dependences ρ( T) and S( T) are detected at temperatures below 20 K. Interplay between the value of the Seebeck coefficient, metallic parameters and Kondo scattering of investigated films is discussed.

  19. Structure and activity of tellurium-cerium oxide acrylonitrile catalysts

    International Nuclear Information System (INIS)

    Ammoxidation of propylene to acrylonitrile (ACN) was investigated over various silica-supported (Te,Ce)O catalysts at 360 and 4400C. The binary oxide system used consists of a single nonstoichiometric fluorite-type phase α-(Ce,Te)O2 up to about 80 mole% TeO2 and a tellurium-saturated solid solution β-(Ce,Te)O2 at higher tellurium concentrations. The ACN yield varies almost linearly with the tellurium content of (Ce,Te)O2. The β-(Ce,Te)O2 phase is the most active component of the system (propylene conversion and ACN selectivity at 440 C of 76.7 and 74%, respectively) and is slightly more selective to ACN than α-Te02. Tellurium reduces the overoxidation properties of cerium and selective oxidation occurs through Te(IV)-bonded oxygen

  20. Effect of Surface Modification on Behaviors of Cerium Oxide Nanopowders

    Institute of Scientific and Technical Information of China (English)

    Li Mei; Shi Zhenxue; Liu Zhaogang; Hu Yanhong; Wang Mitang; Li Hangquan

    2007-01-01

    Study was made on the effect of surface modification on the behaviors of cerium oxide nanopowders. A surfactant-sodium dodecyl sulfate(C12H25SO4Na) was used to modify the surface of CeO2 powder particles. The unmodified and modified CeO2 powders were characterized by using a powder comprehensive characteristic tester, laser particle size analyzer, specific surface area tester, X-ray diffraction tester, and a scanning electron microscope. The testing and analysis results showed that C12H25SO4Na surface modification might increase the flowability and dispersity, and decrease the specific surface area and agglomeration of CeO2 powders. The mechanism of the surface modification of CeO2 powder particles was also discussed.

  1. Management of decontamination solution arising from Cerium redox process

    International Nuclear Information System (INIS)

    This paper describes the recovery of Pu from decontamination stream generated from Cerium Redox Process meant for decontamination of contaminated metallic wastes. Extraction of Pu is carried out using PUREX solvent after reducing it to tetravalent state which is subsequently stripped using hydroxylamine nitrate and nitric acid mixture. Raffinate from this step containing Ce3+, 241Am and corrosion products is subjected to ozonisation wherein Ce3+ is oxidized to Ce4+. Quantitative extraction of Ce is achieved by PUREX solvent in second cycle which is stripped using a mixture of NaNO2 and HNO3. Raffinate from this step contains 241Am and corrosion product which is removed by solvent extraction using TEHDGA. The final alpha lean waste can be managed by cementation. (author)

  2. Modification mechanism of cerium on the Al-18Si alloy

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The effect of the rare earth cerium (Ce) on the hypereutectic Al-Si alloy under different casting states have been studied by optical microscope and quantitative image analysis. It is found that the size and the quantity of primary silicon in castings decrease with the increase of added Ce in the melt. Meanwhile primary silicon changes from branched shape to fine facetted shape. Although the modification on eutectic silicon in castings also improves with the increase of added Ce in the melt, the effect of modification on eutectic silicon away from primary silicon is more obvious than that on eutectic silicon close to primary silicon. The modification mechanism was analyzed in detail by means of scanning electron microscope equipped with energy dispersive analysis of X-ray and thermodynamics analysis, which included the analysis on the change in standard Gibbs energy of reaction and reaction equilibrium.

  3. Mechanochemical synthesis and spark plasma sintering of the cerium silicides

    International Nuclear Information System (INIS)

    Highlights: • Ce5Si3, Ce3Si2, CeSi, CeSi2−x and CeSi2 were mechanochemically synthesized. • Temperature and pressure were monitored to investigate reaction progress. • All syntheses proceeded through a MSR event followed by rapid solid-state diffusion. • Milling time before MSR correlates well with effective heat of formation. • Some synthesized material was densified by spark plasma sintering. - Abstract: The cerium silicides, Ce5Si3, Ce3Si2, CeSi, CeSi2−y, and CeSi2−x, have been prepared from the elements by mechanochemical processing in a planetary ball mill. Preparation of the cerium silicide Ce5Si4 was unsuccessfully attempted and potential reasons for this are discussed. Temperature and pressure of the milling vial were monitored in situ to gain insight into the mechanochemical reaction kinetics, which include a mechanically-induced self-propagating reaction (MSR). Some prepared powders were consolidated by spark plasma sintering to high density. Starting materials, as-milled powders, and consolidated samples were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results obtained help elucidate key questions in mechanochemical processing of intermetallics, showing first phase formation similar to thin films, MSR ignition times that are composition- and milling speed-dependent, and sensitivity of stable compound formation on the impact pressure. The results demonstrate mechanochemical synthesis as a viable technique for rare earth silicides

  4. Mechanochemical synthesis and spark plasma sintering of the cerium silicides

    Energy Technology Data Exchange (ETDEWEB)

    Alanko, Gordon A.; Jaques, Brian; Bateman, Allyssa [Department of Materials Science and Engineering, College of Engineering, Boise State University, 1910 University Drive, Boise, ID 83725 (United States); Butt, Darryl P., E-mail: darrylbutt@boisestate.edu [Department of Materials Science and Engineering, College of Engineering, Boise State University, 1910 University Drive, Boise, ID 83725 (United States); Center for Advanced Energy Studies, 995 University Boulevard, Idaho Falls, ID 83401 (United States)

    2014-12-15

    Highlights: • Ce{sub 5}Si{sub 3}, Ce{sub 3}Si{sub 2}, CeSi, CeSi{sub 2−x} and CeSi{sub 2} were mechanochemically synthesized. • Temperature and pressure were monitored to investigate reaction progress. • All syntheses proceeded through a MSR event followed by rapid solid-state diffusion. • Milling time before MSR correlates well with effective heat of formation. • Some synthesized material was densified by spark plasma sintering. - Abstract: The cerium silicides, Ce{sub 5}Si{sub 3}, Ce{sub 3}Si{sub 2}, CeSi, CeSi{sub 2−y}, and CeSi{sub 2−x}, have been prepared from the elements by mechanochemical processing in a planetary ball mill. Preparation of the cerium silicide Ce{sub 5}Si{sub 4} was unsuccessfully attempted and potential reasons for this are discussed. Temperature and pressure of the milling vial were monitored in situ to gain insight into the mechanochemical reaction kinetics, which include a mechanically-induced self-propagating reaction (MSR). Some prepared powders were consolidated by spark plasma sintering to high density. Starting materials, as-milled powders, and consolidated samples were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results obtained help elucidate key questions in mechanochemical processing of intermetallics, showing first phase formation similar to thin films, MSR ignition times that are composition- and milling speed-dependent, and sensitivity of stable compound formation on the impact pressure. The results demonstrate mechanochemical synthesis as a viable technique for rare earth silicides.

  5. Study on the uranium-cerium extraction and his application to the treatment of irradiated uranium

    International Nuclear Information System (INIS)

    It was made a study on the behavior of uranium and cerium(IV) extraction, using the latter element as a plutonium simulator in a flowsheet of the treatment of irradiated uranium. Cerium(IV) was used under the same conditions as a plutonium in the Purex process because the admitted similar properties. An experimental work was initiated to determine the equilibrium curves of uranium, under the following conditions: concentration of 1 to 20 g U/1 and acidity varying from 1 to 5M in HNO3. Other parameters studied were the volumetric ratio of the phases and the influence of the concentration of TBP (tri-n-butyl phosphate). To guarantee the cerium(IV) extraction, the diluent (varsol) was previously treated with 10% potassium dichromate in perchloric acid, potassium permanganate in 1M sulphuric acid and concentrated sulphuric acid at 70 deg to eliminate reducing compounds. The results obtained for cerium extraction, allowed a better understanding of its behavior in solution. The results permitted to conclude that the decontamination for cerium are very high in the first Purex extraction cycle. The easy as cerium(IV) is reduced to the trivalent state contributes a great deal to its decontamination. (author)

  6. Extraction of tetravalent berkelium and cerium by aliquate-336-S-NO3 quaternary ammonium salt

    International Nuclear Information System (INIS)

    Extraction of tetravalent berkelium and cerium by aliquate-336-S-NO3 quaternary ammonium salt from nitric acid solutions is investigated. The effect of concentrations of nitric acid and extracting agent, nature of an oxidant (potassium bromate, potassium bichromate, mixture of AgNO3 and (NH4)2S2O8) and solvent on the distribution coefficient of berkelium(4) and cerium(4) is studied. It is established that solutions of aliquate-336-S-NO3 in carbon tetrachloride and dichloroethane extract quantitatively tetravalent berkelium from 10-12 M nitric acid solutions and cerium - from 1-10 M nitric acid solutions containing potassium bichromate as an oxidant. It is shown that the value of distribution coefficient for berkelium and cerium depends on the nature of an oxidant and extracting agent concentration. It is established that in the case of extraction by quaternary ammonium salt with one berkelium(4) mole four aliquate-336-SNO3 moles are associated and 1.5-1.6 mole of extracting agent are associated with one cerium(4) mole. It permits to make a conclusion that stoichiometry of extraction reactions by quaternary ammonium salt is not the same for tetravalent berkelium and cerium. It is shown that trivalent transplutonium and rare earth elements are not practically extracted by aliquate-336-S-NO3 from nitric acid solutions

  7. Effects of chemical intermixing on electrical and thermal contact conductances at metallized bismuth and antimony telluride interfaces

    International Nuclear Information System (INIS)

    Tailoring electrical and thermal contact conductivities (Σc and Γc) across metallized pnictogen chalcogenide interfaces is key for realizing efficient thermoelectric devices. The authors report that Cu, Ni, Ti, and Ta diffusion and interfacial telluride formation with n-Bi2Te3 and p-Sb2Te3 influence both Σc and Γc. Cu metallization yields the highest Γc and the lowest Σc, correlating with maximal metal diffusion and copper telluride formation. Ni diffuses less and yields the highest Σc with Sb2Te3 due to p-type nickel telluride formation, which diminishes Σc improvement with n-Bi2Te3 interfaces. Ta and Ti contacts yield the lowest properties similar to that in Ni-metallized structures. These correlations between interfacial diffusion and phase formation on electronic and thermal transport properties will be important for devising suitable metallization for thermoelectric devices

  8. Electronic Characterization of Defects in Narrow Gap Semiconductors-Comparison of Electronic Energy Levels and Formation Energies in Mercury Cadmium Telluride, Mercury Zinc Telluride, and Mercury Zinc Selenide

    Science.gov (United States)

    Patterson, James D.

    1996-01-01

    We have used a Green's function technique to calculate the energy levels and formation energy of deep defects in the narrow gap semiconductors mercury cadmium telluride (MCT), mercury zinc telluride (MZT) and mercury zinc selenide (MZS). The formation energy is calculated from the difference between the total energy with an impurity cluster and the total energy for the perfect crystal. Substitutional (including antisite), interstitial (self and foreign), and vacancy deep defects are considered. Relaxation effects are calculated (with molecular dynamics). By use of a pseudopotential, we generalize the ideal vacancy model so as to be able to consider relaxation for vacancies. Different charge states are considered and the charged state energy shift (as computed by a modified Haldane-Anderson model) can be twice that due to relaxation. Different charged states for vacancies were not calculated to have much effect on the formation energy. For all cases we find deep defects in the energy gap only for cation site s-like orbitals or anion site p-like orbitals, and for the substitutional case only the latter are appreciably effected by relaxation. For most cases for MCT, MZT, MZS, we consider x (the concentration of Cd or Zn) in the range appropriate for a band gap of 0.1 eV. For defect energy levels, the absolute accuracy of our results is limited, but the precision is good, and hence chemical trends are accurately predicted. For the same reason, defect formation energies are more accurately predicted than energy level position. We attempt, in Appendix B, to calculate vacancy formation energies using relatively simple chemical bonding ideas due to Harrison. However, these results are only marginally accurate for estimating vacancy binding energies. Appendix C lists all written reports and publications produced for the grant. We include abstracts and a complete paper that summarizes our work which is not yet available.

  9. Feasibility of preparing patterned molybdenum coatings on bismuth telluride thermoelectric modules.

    Energy Technology Data Exchange (ETDEWEB)

    Sarobol, Pylin; Hall, Aaron Christopher; Miller, Stephen Samuel; Knight, Marlene E.; LePage, William S.; Sobczak, Catherine Elizabeth.; Wesolowski, Daniel Edward

    2013-09-01

    Molybdenum electrical interconnects for thermoelectric modules were produced by air plasma spraying a 30%CE%BCm size molybdenum powder through a laser-cut Kapton tape mask. Initial feasibility demonstrations showed that the molybdenum coating exhibited excellent feature and spacing retention (~170%CE%BCm), adhered to bismuth-telluride, and exhibited electrical conductivity appropriate for use as a thermoelectric module interconnect. A design of experiments approach was used to optimize air plasma spray process conditions to produce a molybdenum coating with low electrical resistivity. Finally, a molybdenum coating was successfully produced on a fullscale thermoelectric module. After the addition of a final titanium/gold layer deposited on top of the molybdenum coating, the full scale module exhibited an electrical resistivity of 128%CE%A9, approaching the theoretical resistivity value for the 6mm module leg of 112%CE%A9. Importantly, air plasma sprayed molybdenum did not show significant chemical reaction with bismuth-telluride substrate at the coating/substrate interface. The molybdenum coating microstructure consisted of lamellar splats containing columnar grains. Air plasma sprayed molybdenum embedded deeply (several microns) into the bismuth-telluride substrate, leading to good adhesion between the coating and the substrate. Clusters of round pores (and cracks radiating from the pores) were found immediately beneath the molybdenum coating. These pores are believed to result from tellurium vaporization during the spray process where the molten molybdenum droplets (2623%C2%B0C) transferred their heat of solidification to the substrate at the moment of impact. Substrate cooling during the molybdenum deposition process was recommended to mitigate tellurium vaporization in future studies.

  10. Lead telluride with increased mechanical stability for cylindrical thermoelectric generators; Bleitellurid mit erhoehter mechanischer Stabilitaet fuer zylindrische thermoelektrische Generatoren

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Andreas

    2013-04-30

    The aim of this work is to improve the mechanical stability of lead telluride (PbTe), trying to vary its mechanical properties independently from its thermoelectric properties. Thus the influence of material preparation as well as different dopants on the mechanical and thermoelectric properties of lead telluride is being analysed. When using appropriately set process parameters, milling and sintering of lead telluride increases the material's hardness. With sintering temperatures exceeding 300 C stable material of high relative density can be achieved. Milling lead telluride generates lattice defects leading to a reduction of the material's charge carrier density. These defects can be reduced by increased sintering temperatures. Contamination of the powder due to the milling process leads to bloating during thermal cycling and thus reduced density of the sintered material. In addition to that, evaporation of tellurium at elevated temperatures causes instability of the material's thermoelectric properties. Based on the experimental results obtained in this work, the best thermoelectric and mechanical properties can be obtained by sintering coarse powders at around 400 C. Within this work a concept was developed to vary the mechanical properties of lead telluride via synthesis of PbTe with electrically nondoping elements, which thus may keep the thermoelectric properties unchanged. Therefore, the mechanical and thermoelectric properties of Pb{sub 1-x}Ca{sub x}Te were investigated. Doping pure PbTe with calcium causes a significant increase of the material's hardness while only slightly decreasing the charge carrier density and thus keeping the thermoelectric properties apart from a slight reduction of the electrical conductivity nearly unchanged. The abovementioned concept is proven using sodium doped lead telluride, as it is used for thermoelectric generators: The additional doping with calcium again increases the material's hardness while

  11. Deformation and crack mechanisms of nanotwinned cadmium telluride under cyclic nanoindentations

    International Nuclear Information System (INIS)

    The surface energies of monocrystalline (mc) and nanotwinned (nt) cadmium telluride (CdTe or CT) crystals, calculated using molecular dynamics simulations, are 435.08 and 381.8 mJ m−2, respectively. A crack of mc-CT is induced at the second loading cycle, whereas nt-CT with both twin boundaries (TBs) shows a crack at the lower TB under the third unloading condition. However, nt-CT with three TBs is free from cracks after 10 cyclic loading–unloading indentations, due to the combined effect between the hardening and softening nanotwins

  12. Large-volume high-resolution cadmium zinc telluride radiation detectors: recent developments

    Science.gov (United States)

    Chen, H.; Awadalla, S. A.; Iniewski, K.; Lu, P. H.; Harris, F.; Mackenzie, J.; Hasanen, T.; Chen, W.; Redden, R.; Bindley, G.; Kuvvetli, Irfan; Budtz-Jørgensen, Carl; Luke, P.; Amman, M.; Lee, J. S.; Bolotnikov, A. E.; Camarda, G. S.; Cui, Y.; Hossain, A.; James, R. B.

    2007-09-01

    The excellent room temperature spectral performance of cadmium zinc telluride detectors grown via the Traveling Heater Method (THM) makes this approach suitable for the mass deployment of radiation detectors for applications in homeland security and medical imaging. This paper reports our progress in fabricating thicker and larger area detectors from THM grown CZT. We discuss the performance of such 20x20x10 mm 3, and 10x10x10 mm 3 monolithic pixellated detectors and virtual Frisch-Grid 4x4x12 mm3 devices, and describe the various physical properties of the materials.

  13. Specific features of the photoconductivity of semi-insulating cadmium telluride

    Energy Technology Data Exchange (ETDEWEB)

    Golubyatnikov, V. A.; Grigor’ev, F. I.; Lysenko, A. P., E-mail: aplysenko@hse.ru; Strogankova, N. I.; Shadov, M. B. [National Research University Higher School of Economics, Moscow Institute of Electronics and Mathematics (Russian Federation); Belov, A. G. [OAO GIREDMET State Research and Design Institute of the Rare-Metal Industry (Russian Federation)

    2014-12-15

    The effect of local illumination providing a high level of free-carrier injection on the conductivity of a sample of semi-insulating cadmium telluride and on the properties of ohmic contacts to the sample is studied. It is found that, irrespective of the illumination region, the contact resistance of ohmic contacts decreases and the concentration of majority carriers in the sample grows in proportion to the illumination intensity. It is shown that inherent heterogeneities in crystals of semi-insulating semiconductors can be studied by scanning with a light probe.

  14. Polarity and structure peculiarities of trialkylphosphine oxides, sulfides, selenides and tellurides

    International Nuclear Information System (INIS)

    Using the quantum-chemical calculations structural characteristics of trialkylphosphine oxides, sulfates, selenides and tellurides (Alk3P=X; X O, S, Se, Te) are obtained, which are in good agreement with literature X-ray structural analysis and gas-phase electron diffraction data. The P=X bonds polarity is determined in the framework of vector-additive scheme on the base of experimental data on components dipole moments and using different base series of molecules geometry parameters. It is shown that increasing of bond moment P=X in the X = O, S, Se, Te series takes place through dipole length increasing

  15. Thermal expansion and stability of cerium-doped Lu2SiO5

    International Nuclear Information System (INIS)

    In-situ X-ray diffraction, differential scanning calorimetry and dilatometry were used to measure the thermal expansion and thermal stability of cerium-doped Lu2SiO5. The thermal expansion of Lu2SiO5 was highly anisotropic, with expansion along the b- and c-axes 5-10 times greater than expansion along the a-axis. There were no measurable differences in the thermal expansion between undoped Lu2SiO5, cerium-doped Lu2SiO5 with high scintillation efficiency, cerium-doped Lu2SiO5 with low scintillation efficiency and annealed cerium-doped Lu2SiO5. Lu2SiO5 decomposed at temperatures as low as 1350 deg. C in 2, while the presence of 100-150 ppm O2 stabilized Lu2SiO5 at temperatures up to 1760 deg. C. No bulk defects were identified to account for the difference between high scintillation efficiency and low scintillation efficiency cerium-doped Lu2SiO5 samples

  16. Electrochemical deposition of cerium on porous silicon to improve photoluminescence properties

    International Nuclear Information System (INIS)

    In this work, we present results for Cerium (Ce) doping effects on photoluminescence (PL) properties of porous silicon (PS). Cerium was deposited using electrochemical deposition on porous silicon prepared by electrochemical anodization of P-type (100) Si. From the photoluminescence spectroscopy, it was shown that porous silicon treated with cerium can lead to an increase of photoluminescence when they are irradiated by light compared to the porous silicon layer without cerium. In order to understand the contribution of cerium to the enhanced photoluminescence, energy dispersive X-ray (EDX) spectroscopy, Fourier transmission infrared spectroscopy (FTIR), X-ray diffraction (XRD) and atomic force microscopy (AFM) were performed, and it was shown that the improved photoluminescence may be attributed to the change of Si–H bonds into Si–O–Ce bonds and to a newly formed PS layer during electrochemical Ce coating. - Highlights: ► Degradation of the surface structures and the PL properties of PS remains a key issue for industrial production. ► In order to solve this problem, the passivation of the PS surface by treating it with Ce is investigated. ► To understand the effects of Ce on PL properties, EDX, FTIR, XRD, AFM and UV–vis analysis were performed.

  17. Electrochemical deposition of cerium on porous silicon to improve photoluminescence properties

    Energy Technology Data Exchange (ETDEWEB)

    Atyaoui, Malek, E-mail: atyaoui.malek@yahoo.fr [Laboratoire de Photovoltaieque, Centre de Recherches et des Technologies de l' energie, PB:95, Hammam Lif 2050 (Tunisia); Dimassi, Wissem; Monther, Ghrib; Chtourou, Radhouane; Ezzaouia, Hatem [Laboratoire de Photovoltaieque, Centre de Recherches et des Technologies de l' energie, PB:95, Hammam Lif 2050 (Tunisia)

    2012-02-15

    In this work, we present results for Cerium (Ce) doping effects on photoluminescence (PL) properties of porous silicon (PS). Cerium was deposited using electrochemical deposition on porous silicon prepared by electrochemical anodization of P-type (100) Si. From the photoluminescence spectroscopy, it was shown that porous silicon treated with cerium can lead to an increase of photoluminescence when they are irradiated by light compared to the porous silicon layer without cerium. In order to understand the contribution of cerium to the enhanced photoluminescence, energy dispersive X-ray (EDX) spectroscopy, Fourier transmission infrared spectroscopy (FTIR), X-ray diffraction (XRD) and atomic force microscopy (AFM) were performed, and it was shown that the improved photoluminescence may be attributed to the change of Si-H bonds into Si-O-Ce bonds and to a newly formed PS layer during electrochemical Ce coating. - Highlights: Black-Right-Pointing-Pointer Degradation of the surface structures and the PL properties of PS remains a key issue for industrial production. Black-Right-Pointing-Pointer In order to solve this problem, the passivation of the PS surface by treating it with Ce is investigated. Black-Right-Pointing-Pointer To understand the effects of Ce on PL properties, EDX, FTIR, XRD, AFM and UV-vis analysis were performed.

  18. Catalysts with Cerium in a Membrane Reactor for the Removal of Formaldehyde Pollutant from Water Effluents

    Directory of Open Access Journals (Sweden)

    Mirella Gutiérrez-Arzaluz

    2016-05-01

    Full Text Available We report the synthesis of cerium oxide, cobalt oxide, mixed cerium, and cobalt oxides and a Ce–Co/Al2O3 membrane, which are employed as catalysts for the catalytic wet oxidation (CWO reaction process and the removal of formaldehyde from industrial effluents. Formaldehyde is present in numerous waste streams from the chemical industry in a concentration low enough to make its recovery not economically justified but high enough to create an environmental hazard. Common biological degradation methods do not work for formaldehyde, a highly toxic but refractory, low biodegradability substance. The CWO reaction is a recent, promising alternative that also permits much lower temperature and pressure conditions than other oxidation processes, resulting in economic benefits. The CWO reaction employing Ce- and Co-containing catalysts was carried out inside a slurry batch reactor and a membrane reactor. Experimental results are reported. Next, a mixed Ce–Co oxide film was supported on an γ-alumina membrane used in a catalytic membrane reactor to compare formaldehyde removal between both types of systems. Catalytic materials with cerium and with a relatively large amount of cerium favored the transformation of formaldehyde. Cerium was present as cerianite in the catalytic materials, as indicated by X-ray diffraction patterns.

  19. Catalysts with Cerium in a Membrane Reactor for the Removal of Formaldehyde Pollutant from Water Effluents.

    Science.gov (United States)

    Gutiérrez-Arzaluz, Mirella; Noreña-Franco, Luis; Ángel-Cuevas, Saúl; Mugica-Álvarez, Violeta; Torres-Rodríguez, Miguel

    2016-01-01

    We report the synthesis of cerium oxide, cobalt oxide, mixed cerium, and cobalt oxides and a Ce-Co/Al₂O₃ membrane, which are employed as catalysts for the catalytic wet oxidation (CWO) reaction process and the removal of formaldehyde from industrial effluents. Formaldehyde is present in numerous waste streams from the chemical industry in a concentration low enough to make its recovery not economically justified but high enough to create an environmental hazard. Common biological degradation methods do not work for formaldehyde, a highly toxic but refractory, low biodegradability substance. The CWO reaction is a recent, promising alternative that also permits much lower temperature and pressure conditions than other oxidation processes, resulting in economic benefits. The CWO reaction employing Ce- and Co-containing catalysts was carried out inside a slurry batch reactor and a membrane reactor. Experimental results are reported. Next, a mixed Ce-Co oxide film was supported on an γ-alumina membrane used in a catalytic membrane reactor to compare formaldehyde removal between both types of systems. Catalytic materials with cerium and with a relatively large amount of cerium favored the transformation of formaldehyde. Cerium was present as cerianite in the catalytic materials, as indicated by X-ray diffraction patterns. PMID:27231888

  20. The kinetics of bromate-cerium(III) and -iron(II) reactions

    International Nuclear Information System (INIS)

    The bromate-cerium(III) and -iron(II) reactions in acidic media were examined with special reference to their induction periods and reaction rates. In the bromate-cerium(III)reaction, the induction period is followed by a burst of cerium (IV) formation and then a gradual formation of cerium(IV). In the bromate-iron(II) reaction, a slow decrease occurs only in acidic media, even without bromate, so it may differ from the decrease in the tris(1, 10-phenanthroline)iron(II) concentration based on the oxidation by bromate. Itwas interpreted as the dissociation from ( Fe(phen)3 ) 2+ to ( Fe(phen)2 ) 2+ and phen. This is the induction period for iron(III) formation, which follows as the burst. The induction period and the rates of cerium(IV) or iron(III) formation can be interpreted on the basis of the mechanism for the Belousov oscillatory and the present redox reactions proposed by Noyes and his co-workers. (author)

  1. Effect of cerium loading on structure and morphology of modified Ce-USY zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Fillipe A.C.; Araujo, Daniel R.; Silva, Junia C.M.; Macedo, Julio L. de; Dias, Silvia C.L.; Dias, Jose A., E-mail: scdias@unb.br, E-mail: jdias@unb.br [Laboratorio de Catalise, Instituto de Quimica, Faculdade UnB-Gama, Universidade de Brasilia, DF (Brazil); Ghesti, Grace F. [Engenharia de Energia, Faculdade UnB-Gama, Universidade de Brasilia, DF (Brazil); Filho, Geraldo N.R. [Centro de Ciencias Exatas e Naturais, Universidade Federal do Para, Belem, PA (Brazil)

    2011-09-15

    This work describes comprehensibly the effect of cerium loading on the structure and morphology of NH{sub 4}USY zeolite. The Ce-USY (2-25 wt.% of CeO{sub 2}) was obtained by wet impregnation of CeCl{sub 3} followed by calcination at 550 deg C for 8 h. At low loadings (2-10%), cerium species are mainly located at ion exchange positions in the framework, whereas at higher loadings (15.25%), small aggregates were formed on the HUSY surface. X-ray diffractograms (XRD) exhibited only the reflections related to HUSY, demonstrating the high dispersion of cerium species, but Fourier transform Raman spectroscopy (FT-Raman) detected CeO{sub x} for the materials above 10%. Reaction of CeCl{sub 3} with NH{sub 4}USY produced NH{sub 4}Cl, which decomposed to form HCl, leading to framework dealumination. The materials showed an increased Lewis/Bronsted ratio with increasing cerium loadings due to the interaction between the excess cerium and the OH groups of USY, and the consequent formation of CeO{sub x} species. (author)

  2. In-house SAD phasing with surface-bound cerium ions

    International Nuclear Information System (INIS)

    Cerium was used to enhance the anomalous signal in hen egg-white lysozyme crystals and led to successful in-house SAD phasing. The anomalous signal of cerium(III) ions present in a derivative of hen egg-white lysozyme (HEWL) crystals obtained by the addition of 0.025 M cerium chloride to the crystallization medium was used for phasing. X-ray intensity data were collected to 2 Å resolution using an in-house Cu Kα radiation data-collection facility. Phasing of a single-wavelength data set purely based on its f′′ led to a clearly interpretable electron-density map. Automated substructure solution by AutoSol in PHENIX resulted in four highest peaks corresponding to cerium(III) ions with data limited to 3 Å resolution, and about 90% of the residues were built automatically by AutoBuild in PHENIX. Cerium(III) ions bound on the surface of the enzyme are found to interact mainly with the main-chain and side-chain carbonyl groups of Asn, Glu, Tyr and Asp and with water molecules. Ce3+ ions were used as potential anomalous scatterers for the in-house single-wavelength anomalous scattering technique, and this is proposed as a tool for macromolecular phasing and for the study of the interactions of trivalent metal ions with proteins and other macromolecules

  3. Synthesis and catalytic properties of microemulsion-derived cerium oxide nanoparticles

    Science.gov (United States)

    Kockrick, Emanuel; Schrage, Christian; Grigas, Anett; Geiger, Dorin; Kaskel, Stefan

    2008-07-01

    The synthesis of cerium dioxide nanoparticles using an inverse microemulsion technique and precipitation method was investigated. Cerium hydroxide nanoparticles were synthesized by adding diluted ammonia to n-heptane-surfactant-cerium nitrate system. The micelle and particle size in the range of 5-12 nm were controlled by varying the molar water to surfactant ratio and analyzed by dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (HRTEM). Cerium hydroxide nanoparticles were isolated and subsequently treated at 100-600 °C to obtain nanoscale ceria. Crystallite sizes of cerium dioxide in the range of 6-16 nm were estimated by Scherrer analysis by X-ray diffraction (XRD) and HRTEM. The catalytic activity of particles annealed at 400 and 600 °C in soot combustion reactions was characterized by temperature-programmed oxidation (TPO) indicating a size-dependant activity. Crystallite sizes and catalytic stability of elevated ceria systems were tested in second combustion cycles.

  4. Effect of electronic contribution on temperature-dependent thermal transport of antimony telluride thin film

    International Nuclear Information System (INIS)

    Highlights: • We investigated thermal transport of the antimony telluride thin films. • The contribution of the electronic thermal conductivity increased up to ∼77% at 300 K. • We theoretically analyze and explain the high contribution of electronic component. - Abstract: We study the theoretical and experimental characteristics of thermal transport of 100 nm and 500 nm-thick antimony telluride (Sb2Te3) thin films prepared by radio frequency magnetron sputtering. The thermal conductivity was measured at temperatures ranging from 20 to 300 K, using four-point-probe 3-ω method. Out-of-plane thermal conductivity of the Sb2Te3 thin film was much lesser in comparison to the bulk material in the entire temperature range, confirming that the phonon- and electron-boundary scattering are enhanced in thin films. Moreover, we found that the contribution of the electronic thermal conductivity (κe) in total thermal conductivity (κ) linearly increased up to ∼77% at 300 K with increasing temperature. We theoretically analyze and explain the high contribution of electronic component of thermal conductivity towards the total thermal conductivity of the film by a modified Callaway model. Further, we find the theoretical model predictions to correspond well with the experimental results

  5. Facile production of thermoelectric bismuth telluride thick films in the presence of polyvinyl alcohol.

    Science.gov (United States)

    Lei, C; Burton, M R; Nandhakumar, I S

    2016-06-01

    Bismuth telluride is currently the best performing thermoelectric material for room temperature operations in commercial thermoelectric devices. We report the reproducible and facile production of 600 micron thick bismuth telluride (Bi2Te3) layers by low cost and room temperature pulsed and potentiostatic electrodeposition from a solution containing bismuth and tellurium dioxide in 2 M nitric acid onto nickel in the presence of polyvinyl alcohol (PVA). This was added to the electrolyte to promote thick layer formation and its effect on the structure, morphology and composition of the electrodeposits was investigated by SEM and EDX. Well adherent, uniform, compact and stoichiometric n-type Bi2Te3 films with a high Seebeck coefficient of up to -200 μV K(-1) and a high electrical conductivity of up to 400 S cm(-1) resulting in a power factor of 1.6 × 10(-3) W m(-1) K(-2) at film growth rates of 100 μm h(-1) for potentiostatic electrodeposition were obtained. The films also exhibited a well defined hexagonal structure as determined by XRD. PMID:27166737

  6. Thermoelectric properties and micro-structure characteristics of annealed N-type bismuth telluride thin film

    International Nuclear Information System (INIS)

    N-type bismuth telluride (Bi2Te3) thermoelectric thin films were deposited by co-sputtering simple substance Te and Bi targets. The deposited films were annealed under various temperatures. The composition ratio, micro-structure and thermoelectric properties of the prepared films were systematically investigated by energy dispersive spectrometer, X-ray diffraction, four-probe method and Seebeck coefficient measurement system. When the annealing temperature is 400 °C, the stoichiometric N-type Bi2Te3 film is achieved, which has a maximum thermoelectric power factor of 0.821 × 10−3 W m−1 K−2. Furthermore, the dependence of Seebeck coefficient, electrical conductivity and power factor of the stoichiometric N-type Bi2Te3 film annealed at film 400 °C on the applied temperature ranging from 25 °C to 315 °C was investigated. The results show that a highest power factor of 3.288 × 10−3 W m−1 K−2 is obtained at the applied temperature of 275 °C. The structural and thermoelectric properties of the deposited bismuth telluride thin films are greatly improved by annealing and the Seebeck coefficient, electrical conductivity and power factor increase with the applied temperature rising, which are helpful and could be guidance for preparing the high-performance thin film thermoelectric materials for thermoelectric application.

  7. Characterization of large cadmium zinc telluride crystals grown by traveling heater method

    DEFF Research Database (Denmark)

    Chen, H.; Awadalla, S.A.; Iniewski, K.;

    2008-01-01

    The focus of this paper is to evaluate thick, 20 X 20 X 10 and 10 X 10 X 10 mm(3), cadmium zinc telluride (CZT), Cd0.9Zn0.1Te, crystals grown using the traveling heater method (THIM). The phenomenal spectral performance and small size and low concentration of Te inclusions/precipitates of these c......The focus of this paper is to evaluate thick, 20 X 20 X 10 and 10 X 10 X 10 mm(3), cadmium zinc telluride (CZT), Cd0.9Zn0.1Te, crystals grown using the traveling heater method (THIM). The phenomenal spectral performance and small size and low concentration of Te inclusions....../precipitates of these crystals indicate that the THM is suitable for the mass production of CZT radiation detectors that can be used in a variety of applications. Our result also proves that with careful material selection using IR and high-quality fabrication processes, the theoretical energy resolution limit can be achieved....

  8. Telluride buried channel waveguides operating from 6 to 20 μm for photonic applications

    Science.gov (United States)

    Vigreux, C.; Escalier, R.; Pradel, A.; Bastard, L.; Broquin, J.-E.; Zhang, X.; Billeton, T.; Parent, G.; Barillot, M.; Kirschner, V.

    2015-11-01

    One of the technological challenges of direct observation of extra-solar planets by nulling interferometry is the development of a modal filter operating from 6 to 20 μm. In the present paper a candidate technology for the fabrication of such modal filters is presented: Integrated Optics. A solution based on all-telluride buried channel waveguides is considered. In the proposed waveguides, vertical guiding of light is achieved by a 15 μm-thick Te83Ge17 core film deposited onto a lower-index Te75Ge15Ga10 substrate, and covered by a 15 μm-thick Te76Ge24 superstrate. Horizontal guiding of light is obtained by modifying the geometry of the core layer by ion beam etching. As this stage, all-telluride buried channel waveguide prototypes demonstrate light guiding and transmission from 2 to 20 μm. The validity of the technology and the good quality of the fabrication process, in particular the input and output facets surface finish are thus confirmed. These results consolidate the potential of Te-based integrated optics components for nulling interferometry.

  9. Electrodeposition of bismuth telluride nanowires with controlled composition in polycarbonate membranes

    International Nuclear Information System (INIS)

    Bismuth telluride nanowires were potentiostatically deposited from a water/DMSO 50%, v/v electrolyte within polycarbonate etched ion-track membranes covered by a platinum substrate. The presence of DMSO shifts the potentials to more negative values and slows down the cation diffusion. Cyclic voltammetries on recessed Pt nanoelectrodes using polycarbonate membranes highlight a complex electrochemical behavior through several cathodic and anodic peaks which are not observed onto platinum discs macroelectrodes. Analytical investigations enabled the determination of appropriate deposition conditions to finely tune the average composition of the nanowires. Calibrated TEM-EDX analyses evidence high aspect ratio nanowires, whose composition is strongly dependent on the deposition potential. In the same manner as for bismuth telluride film electroplating, bismuth enrichment occurs at more cathodic deposition potential whereas tellurium enrichment is observed at low cathodic potentials. Stoichiometric nanowires of 60 nm diameter were obtained at −100 mV vs Ag/AgCl from an electrolyte which contains [Bi3+] = 1.5[HTeO2+] = 15 mM. The composition is homogeneous along the nanowire except at both edges: the cap is rich in bismuth whereas the base is rich in tellurium. The composition at the nanowire base is adjusted by setting a short initial voltage step (Ui = −300 mV vs Ag/AgCl, ti = 2 s). In the case of stoichiometric compounds, the resulting nanostructures were found to be polycrystalline with a preferential orientation along the direction perpendicular to the planes (0 1 5).

  10. Effect of Cerium(IV)-Surfactant Reaction in Foam Decontamination

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Han Beom; Jung, Chong-Hun; Yoon, In-Ho; Kim, Chorong; Choi, Wang-Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Using foams allows the decommissioning of complex shaped facilities. The decontamination foam comprises at least one surfactant to generate the foam and one or more chemical reactants to achieve the dissolution of the contaminants at the solid surface. In order to improve the efficiency of decontamination foam, the present study attempts to find the optimum condition of chemical reagents to the foaming solution. The corrosion rate of radioactive nuclides contaminated stainless steel metal is very important factor for the foam decontamination process. The goal of this study is to develop the decontamination process for contaminated stainless steel in medium of nitric acid. Stainless steel needs a strong oxidizing agent such as Ce(IV) ion and the effects of cerium(IV). Surfactant interaction involved in foam decontamination and finally the improvement brought by formulation science. The formulation of foams loaded with strong oxidizing reagents such as Ce(IV) is an important factor. The enhanced decontamination properties of nitric acid with Ce(IV) additive on stainless steel is well known in liquid mediums. stainless steel metal is an important aspect in the foam decontamination process.

  11. Antioxidant Cerium Oxide Nanoparticles in Biology and Medicine

    Science.gov (United States)

    Nelson, Bryant C.; Johnson, Monique E.; Walker, Marlon L.; Riley, Kathryn R.; Sims, Christopher M.

    2016-01-01

    Previously, catalytic cerium oxide nanoparticles (CNPs, nanoceria, CeO2-x NPs) have been widely utilized for chemical mechanical planarization in the semiconductor industry and for reducing harmful emissions and improving fuel combustion efficiency in the automobile industry. Researchers are now harnessing the catalytic repertoire of CNPs to develop potential new treatment modalities for both oxidative- and nitrosative-stress induced disorders and diseases. In order to reach the point where our experimental understanding of the antioxidant activity of CNPs can be translated into useful therapeutics in the clinic, it is necessary to evaluate the most current evidence that supports CNP antioxidant activity in biological systems. Accordingly, the aims of this review are three-fold: (1) To describe the putative reaction mechanisms and physicochemical surface properties that enable CNPs to both scavenge reactive oxygen species (ROS) and to act as antioxidant enzyme-like mimetics in solution; (2) To provide an overview, with commentary, regarding the most robust design and synthesis pathways for preparing CNPs with catalytic antioxidant activity; (3) To provide the reader with the most up-to-date in vitro and in vivo experimental evidence supporting the ROS-scavenging potential of CNPs in biology and medicine. PMID:27196936

  12. Deposition and investigation of lanthanum-cerium hexaboride thin films

    International Nuclear Information System (INIS)

    Thin films of lanthanum-cerium hexaboride, the promising thermoelectric material for low-temperature applications, are deposited on various substrates by the electron-beam evaporation, pulsed laser deposition and magnetron sputtering. The influence of the deposition conditions on the films X-ray characteristics, composition, microstructure and physical properties, such as the resistivity and Seebeck coefficient, is studied. The preferred (100) orientation of all films is obtained from XRD traces. In the range of 780-800 deg. C deposition temperature the highest intensity of diffractions peaks and the highest degree of the preferred orientation are observed. The temperature dependence of the resistivity and the Seebeck coefficient of films are investigated in the temperature range of 4-300 K. The features appropriate to Kondo effect in the dependences ρ(T) and S(T) are detected at temperatures below 20 K. Interplay between the value of the Seebeck coefficient, metallic parameters and Kondo scattering of investigated films is discussed. - Graphical abstract: Kondo scattering in (La,Ce)B6 films: temperature dependence of the resistivity of (La,Ce)B6 films on various substrates and the ceramics La0.99Ce0.01B6

  13. Synthesis and characterization of cerium oxide by electrochemical methods

    International Nuclear Information System (INIS)

    Ceria-based materials have been synthesized by electrochemical process. Electrodeposition is an interesting cheap method which can be performed at ambient pressure and rather low temperature (less than 100 C). Moreover, it is easy to control in situ the film thickness. Ceria coatings were obtained by an indirect electrodeposition method. A potentiostatic technique (-0.7 V/SCE) was used to first reduce a hydroxide precursor (O2 or NO3-) before leading to the formation of cerium oxide after 2h of deposition time. This work focused on the characterization of ceria films deposited onto stainless steel in view of high temperature fuel cell applications. The chosen deposition conditions lead to quite adherent, homogenous and covering films. The microstructure and the crystallinity of the ceria thin layers were characterized by SEM, TEM and XRD measurements. Electrochemical microscopy (SECM) was also used to locally study the conductive properties of ceria layers and the homogeneity of the deposited films. Finally, electrochemical characterizations such as impedance spectroscopy were performed under air atmosphere. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Synthesis and characterization of cerium oxide by electrochemical methods

    Energy Technology Data Exchange (ETDEWEB)

    Lair, V.; Ringuede, A. [LECA CNRS UMR 7575-ENSCP-Paris 6, Paris (France); Vermaut, P. [Groupe Metallurgie Structurale LPCS UMR CNRS, ENSCP-Paris 6, Paris (France); Griveau, S. [Ecole Nationale Superieure de Chimie de Paris, Faculty of Pharmacy, Chemical and Genetic Pharmacology Laboratory, Paris (France)

    2008-07-01

    Ceria-based materials have been synthesized by electrochemical process. Electrodeposition is an interesting cheap method which can be performed at ambient pressure and rather low temperature (less than 100 C). Moreover, it is easy to control in situ the film thickness. Ceria coatings were obtained by an indirect electrodeposition method. A potentiostatic technique (-0.7 V/SCE) was used to first reduce a hydroxide precursor (O{sub 2} or NO{sub 3}{sup -}) before leading to the formation of cerium oxide after 2h of deposition time. This work focused on the characterization of ceria films deposited onto stainless steel in view of high temperature fuel cell applications. The chosen deposition conditions lead to quite adherent, homogenous and covering films. The microstructure and the crystallinity of the ceria thin layers were characterized by SEM, TEM and XRD measurements. Electrochemical microscopy (SECM) was also used to locally study the conductive properties of ceria layers and the homogeneity of the deposited films. Finally, electrochemical characterizations such as impedance spectroscopy were performed under air atmosphere. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Electron inelastic mean free paths in cerium dioxide

    Science.gov (United States)

    Krawczyk, M.; Holdynski, M.; Lisowski, W.; Sobczak, J. W.; Jablonski, A.

    2015-06-01

    Electron transport properties in CeO2 powder samples were studied by elastic-peak electron spectroscopy (EPES). Prior to EPES measurements, the CeO2 sample surface was pre-sputtered by 0.5 keV Ar ion etching. As a result, an altered layer with thickness of 1.3 nm was created. X-ray photoelectron spectroscopy (XPS) analysis revealed two chemical states of cerium Ce4+ (68%) and Ce3+ (32%) at the surface region of CeO2 sample after such treatment. The inelastic mean free path (IMFP), characterizing electron transport, was evaluated as a function of energy within the 0.5-2 keV range. Experimental IMFPs were corrected for surface excitations and approximated by the simple function λ = kEp, where λ was the IMFP, E denoted the energy (in eV), and k = 0.207 and p = 0.6343 were the fitted parameters. The IMFPs measured here were compared with IMFPs resulting from the TPP-2M predictive equation for the measured composition of oxide surface. The measured IMFPs were found to be from 3.1% to 20.3% smaller than the IMFPs obtained from the predictive formula in the energy range of 0.5-2 keV. The EPES IMFP value at 500 eV was related to the altered layer of sputtered CeO2 samples.

  16. Catalytic properties and biomedical applications of cerium oxide nanoparticles

    KAUST Repository

    Walkey, Carl D.

    2014-11-10

    Cerium oxide nanoparticles (nanoceria) have shown promise as catalytic antioxidants in the test tube, cell culture models and animal models of disease. However given the reactivity that is well established at the surface of these nanoparticles, the biological utilization of nanoceria as a therapeutic still poses many challenges. Moreover the form that these particles take in a biological environment, such as the changes that can occur due to a protein corona, are not well established. This review aims to summarize the existing literature on biological use of nanoceria, and to raise questions about what further study is needed to apply this interesting catalytic material to biomedical applications. These questions include: 1) How does preparation, exposure dose, route and experimental model influence the reported effects of nanoceria in animal studies? 2) What are the considerations to develop nanoceria as a therapeutic agent in regards to these parameters? 3) What biological targets of reactive oxygen species (ROS) and reactive nitrogen species (RNS) are relevant to this targeting, and how do these properties also influence the safety of these nanomaterials?

  17. Antioxidant Cerium Oxide Nanoparticles in Biology and Medicine.

    Science.gov (United States)

    Nelson, Bryant C; Johnson, Monique E; Walker, Marlon L; Riley, Kathryn R; Sims, Christopher M

    2016-01-01

    Previously, catalytic cerium oxide nanoparticles (CNPs, nanoceria, CeO2-x NPs) have been widely utilized for chemical mechanical planarization in the semiconductor industry and for reducing harmful emissions and improving fuel combustion efficiency in the automobile industry. Researchers are now harnessing the catalytic repertoire of CNPs to develop potential new treatment modalities for both oxidative- and nitrosative-stress induced disorders and diseases. In order to reach the point where our experimental understanding of the antioxidant activity of CNPs can be translated into useful therapeutics in the clinic, it is necessary to evaluate the most current evidence that supports CNP antioxidant activity in biological systems. Accordingly, the aims of this review are three-fold: (1) To describe the putative reaction mechanisms and physicochemical surface properties that enable CNPs to both scavenge reactive oxygen species (ROS) and to act as antioxidant enzyme-like mimetics in solution; (2) To provide an overview, with commentary, regarding the most robust design and synthesis pathways for preparing CNPs with catalytic antioxidant activity; (3) To provide the reader with the most up-to-date in vitro and in vivo experimental evidence supporting the ROS-scavenging potential of CNPs in biology and medicine. PMID:27196936

  18. Cerium doped lanthanum halides: fast scintillators for medical imaging

    International Nuclear Information System (INIS)

    This work is dedicated to two recently discovered scintillating crystals: cerium doped lanthanum halides (LaCl3:Ce3+ and LaBr3:Ce3+).These scintillators exhibit interesting properties for gamma detection, more particularly in the field of medical imaging: a short decay time, a high light yield and an excellent energy resolution. The strong hygroscopicity of these materials requires adapting the usual experimental methods for determining physico-chemical properties. Once determined, these can be used for the development of the industrial manufacturing process of the crystals. A proper comprehension of the scintillation mechanism and of the effect of defects within the material lead to new possible ways for optimizing the scintillator performance. Therefore, different techniques are used (EPR, radioluminescence, laser excitation, thermally stimulated luminescence). Alongside Ce3+ ions, self-trapped excitons are involved in the scintillation mechanism. Their nature and their role are detailed. The knowledge of the different processes involved in the scintillation mechanism leads to the prediction of the effect of temperature and doping level on the performance of the scintillator. A mechanism is proposed to explain the thermally stimulated luminescence processes that cause slow components in the light emission and a loss of light yield. Eventually the study of afterglow reveals a charge transfer to deep traps involved in the high temperature thermally stimulated luminescence. (author)

  19. Cerium toxicity, uptake and translocation in Arabidopsis thaliana seedlings

    Institute of Scientific and Technical Information of China (English)

    WANG Xue; LIN Yousheng; LIU Dongwu; XU Hengjian; LIU Tao; ZHAO Fengyun

    2012-01-01

    Arabidopsis thaliana seedlings were cultivated in 0-500 μmol/L of extraneous cerium (Ce) for 7 d to investigate the toxicity,uptake and translocation of rare earth elements (REEs).The results showed that Ce could be largely absorbed by the roots of A.thaliana and translocated to the shoots.But the uptake rates of Ce by the roots were much higher than the translocation rates from roots to shoots.Ultrastructural analysis revealed that Ce was mainly distributed on the cell wall.At higher concentration,Ce could also enter cell,destroy the ultrastructure of cells and disturb the intrinsic balance of nutrient elements of A.thaliana.Addition of Ce (50-500 μmol/L) to the culture medium significantly inhibited the elongation of primary roots,decreased chlorophyll content,rosette diameter and fresh mass of plants.The damage increased with the increase of Ce concentration in culture medium,although primary root elongation,chlorophyll content,and rosette diameter were stimulated by relatively low concentration (0.5 μmol/L) of Ce.Thus,it is speculated that REEs may become a new type contamination if we don't well control the release of REEs into the environment.

  20. Effect of Cerium(IV)-Surfactant Reaction in Foam Decontamination

    International Nuclear Information System (INIS)

    Using foams allows the decommissioning of complex shaped facilities. The decontamination foam comprises at least one surfactant to generate the foam and one or more chemical reactants to achieve the dissolution of the contaminants at the solid surface. In order to improve the efficiency of decontamination foam, the present study attempts to find the optimum condition of chemical reagents to the foaming solution. The corrosion rate of radioactive nuclides contaminated stainless steel metal is very important factor for the foam decontamination process. The goal of this study is to develop the decontamination process for contaminated stainless steel in medium of nitric acid. Stainless steel needs a strong oxidizing agent such as Ce(IV) ion and the effects of cerium(IV). Surfactant interaction involved in foam decontamination and finally the improvement brought by formulation science. The formulation of foams loaded with strong oxidizing reagents such as Ce(IV) is an important factor. The enhanced decontamination properties of nitric acid with Ce(IV) additive on stainless steel is well known in liquid mediums. stainless steel metal is an important aspect in the foam decontamination process

  1. Toenail cerium levels and risk of a first acute myocardial infarction: The EURAMIC and heavy metals study

    NARCIS (Netherlands)

    Gomez-Aracena, J.; Riemersma, R.A.; Veer, van 't P.; Kok, F.J.

    2006-01-01

    The association between cerium status and risk of first acute myocardial infarction (AMI) was examined in a case-control study in 10 centres from Europe and Israel. Cerium in toenails was assessed by neutron activation analysis in 684 cases and 724 controls aged 70years or younger. Mean concentratio

  2. Effect of Annealing on the Properties of Antimony Telluride Thin Films and Their Applications in CdTe Solar Cells

    Directory of Open Access Journals (Sweden)

    Zhouling Wang

    2014-01-01

    Full Text Available Antimony telluride alloy thin films were deposited at room temperature by using the vacuum coevaporation method. The films were annealed at different temperatures in N2 ambient, and then the compositional, structural, and electrical properties of antimony telluride thin films were characterized by X-ray fluorescence, X-ray diffraction, differential thermal analysis, and Hall measurements. The results indicate that single phase antimony telluride existed when the annealing temperature was higher than 488 K. All thin films exhibited p-type conductivity with high carrier concentrations. Cell performance was greatly improved when the antimony telluride thin films were used as the back contact layer for CdTe thin film solar cells. The dark current voltage and capacitance voltage measurements were performed to investigate the formation of the back contacts for the cells with or without Sb2Te3 buffer layers. CdTe solar cells with the buffer layers can reduce the series resistance and eliminate the reverse junction between CdTe and metal electrodes.

  3. Oxochloroalkoxide of the Cerium (IV and Titanium (IV as oxides precursor

    Directory of Open Access Journals (Sweden)

    Machado Luiz Carlos

    2002-01-01

    Full Text Available The Cerium (IV and Titanium (IV oxides mixture (CeO2-3TiO2 was prepared by thermal treatment of the oxochloroisopropoxide of Cerium (IV and Titanium (IV. The chemical route utilizing the Cerium (III chloride alcoholic complex and Titanium (IV isopropoxide is presented. The compound Ce5Ti15Cl16O30 (iOPr4(OH-Et15 was characterized by elemental analysis, FTIR and TG/DTG. The X-ray diffraction patterns of the oxides resulting from the thermal decomposition of the precursor at 1000 degreesC for 36 h indicated the formation of cubic cerianite (a = 5.417Å and tetragonal rutile (a = 4.592Å and (c = 2.962 Å, with apparent crystallite sizes around 38 and 55nm, respectively.

  4. Mesoporous cerium oxide nanospheres for the visible-light driven photocatalytic degradation of dyes

    Directory of Open Access Journals (Sweden)

    Subas K. Muduli

    2014-04-01

    Full Text Available A facile, solvothermal synthesis of mesoporous cerium oxide nanospheres is reported for the purpose of the photocatalytic degradation of organic dyes and future applications in sustainable energy research. The earth-abundant, relatively affordable, mixed valence cerium oxide sample, which consists of predominantly Ce7O12, has been characterized by powder X-ray diffraction, X-ray photoelectron and UV–vis spectroscopy, and transmission electron microscopy. Together with N2 sorption experiments, the data confirms that the new cerium oxide material is mesoporous and absorbs visible light. The photocatalytic degradation of rhodamin B is investigated with a series of radical scavengers, suggesting that the mechanism of photocatalytic activity under visible-light irradiation involves predominantly hydroxyl radicals as the active species.

  5. Kinetics of deso/sub x/ reaction on copper and cerium-based sorbent-catalysts

    International Nuclear Information System (INIS)

    Kinetics of SO/sub 2/ removal using a copper-based sorbent CuO/gamma-AI/sub 2/O/sub 3/ and a cerium modified copper sorbent CuO-CeO/sub 2/gamma-AI/sub 2/O, were measured on a TGA and their kinetics behaviors were simulated with a proposed empirical rate model (ERM). The purpose of cerium addition to the copper sorbent was to study the difference of sorbent's kinetics. The cerium modified copper sorbent showed a higher reaction rate on initial sulfation than the regular copper sorbent. Both sorbents however had similar calculated activation energy. The proposed ERM model appeared to describe the SO/sub 2/ removal kinetics well in the temperature range 250-400 degree C. (author)

  6. Magnetic ordering in the static intermediate-valent cerium compound Ce2RuZn4

    Science.gov (United States)

    Eyert, Volker; Scheidt, Ernst-Wilhelm; Scherer, Wolfgang; Hermes, Wilfried; Pöttgen, Rainer

    2008-12-01

    The low-temperature behavior of Ce2RuZn4 has been investigated. Specific-heat and magnetic-susceptibility data reveal an antiferromagnetic transition at a Néel temperature of 2 K. Ce2RuZn4 is a static intermediate-valent compound with two crystallographically independent cerium atoms. The magnetic data clearly show that only one cerium site is magnetic (Ce3+) , while the second one carries no magnetic moment. The experimental data are interpreted with the help of first-principles electronic structure calculations using density-functional theory and the augmented spherical wave method. The calculations reveal the occurrence of two different cerium sites, which are characterized by strongly localized magnetic moments and strong Ce-Ru bonding.

  7. Electro-deposition of cerium thin film compound, elaboration and characterisation

    International Nuclear Information System (INIS)

    Cerium oxide films are widely studied as a promising alternative to the toxic hexavalent Chromium Cr(VI) based pre-treatments for the corrosion protection of different metals and alloys. Cathodic electro-deposition of Cerium compound thin films was realised on Ti alloy (TA6V) substrates from a Ce(NO3)3, 6H2O in water-ethyl alcohol solutions at 0.01 M. Experimental conditions to obtain homogeneous and crack free thin films were determined. The deposited cerium quantity, as expected, is proportional to the used electric charge, following the Faraday law. Subsequent thermal treatment led to a CeO2 coating, which is expected to increase the TA6V oxidation resistance at high temperatures. The deposits were characterized by Differential Scanning Calorimetry (DSC), optical and scanning electron microscopies.(author)

  8. Effect of Impurities and Cerium on Stress Concentration Sensitivity of Al-Li Based Alloys

    Institute of Scientific and Technical Information of China (English)

    孟亮; 田丽

    2002-01-01

    A notch sensitivity factor was derived in order to evaluate the stress concentration sensitivity of Al-Li based alloys. The factor values for the Al-Li alloy sheets containing various contents of impurities and cerium addition were evaluated by determining the mechanical properties. It is found that the impurities Fe, Si, Na and K significantly enhance the stress concentration sensitivity of the alloys 2090 and 8090, whereas cerium addition reduces the stress concentration sensitivity to a certain degree for the high strength alloys. However, an excess amount of cerium addition in the high ductility alloy 1420 can significantly increase the stress concentration sensitivity. As compared with conventional aluminum alloys, the Al-Li based alloys generally show high stress concentration sensitivity. Therefore, a special attention must be paid to this problem in the practical application of Al-Li based alloys.

  9. Self-Correction of Lanthanum-Cerium Halide Gamma Spectra (pre-print)

    Energy Technology Data Exchange (ETDEWEB)

    Ding Yuan, Paul Guss, and Sanjoy Mukhopadhyay

    2009-04-01

    Lanthanum-cerium halide detectors generally exhibit superior energy resolutions for gamma radiation detection compared with conventional sodium iodide detectors. However, they are also subject to self-activities due to lanthanum-138 decay and contamination due to beta decay in the low-energy region and alpha decay in the high-energy region. The detector’s self-activity and crystal contamination jointly contribute a significant amount of uncertainties to the gamma spectral measurement and affect the precision of the nuclide identification process. This paper demonstrates a self-correction procedure for self-activity and contamination reduction from spectra collected by lanthanum-cerium halide detectors. It can be implemented as an automatic self-correction module for the future gamma radiation detector made of lanthanum-cerium halide crystals.

  10. Self-Correction of Lanthanum-Cerium Halide Gamma Spectra (pre-print)

    International Nuclear Information System (INIS)

    Lanthanum-cerium halide detectors generally exhibit superior energy resolutions for gamma radiation detection compared with conventional sodium iodide detectors. However, they are also subject to self-activities due to lanthanum-138 decay and contamination due to beta decay in the low-energy region and alpha decay in the high-energy region. The detector's self-activity and crystal contamination jointly contribute a significant amount of uncertainties to the gamma spectral measurement and affect the precision of the nuclide identification process. This paper demonstrates a self-correction procedure for self-activity and contamination reduction from spectra collected by lanthanum-cerium halide detectors. It can be implemented as an automatic self-correction module for the future gamma radiation detector made of lanthanum-cerium halide crystals.

  11. Electrolytic technique for the chemical decontamination process with sulfuric acid-cerium (IV) for decommissioning

    International Nuclear Information System (INIS)

    An electrolyzer with an ion-exchange membrane as the separator has been used to study the electrolytic redox reaction of Ce4+ / Ce3+ in sulfuric acid solution, which is a reagent for predismantling system decontamination. Influencing factors such as current density, cerium concentration, acidity, electrolyte flow rate, membrane type and electrode material were studied experimentally. The results indicate that the redox can be achieved with high conversion even as the cerium concentration is below 0.005 M. However, the current efficiency strongly depends on the cerium concentration. In addition, the acid content and the electrolyte flow rate show little influence on the redox reaction. Both cation and anion membrane are feasible for this process. Therefore, the operation conditions are widely applicable. Moreover, two different electrode materials, platinized titanium meshes and graphite, were used. The results show that the platinized titanium meshes is preferable to the graphite for higher current efficiency. (author)

  12. Cathodic electrolysis method of depositing cerium conversion films on industrial pure aluminum

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Two two-step techniques, called TS2/TS7 and TS3/TS7, respectively, have been developed to form cerium conversion films on the surface of industrial pure aluminum. The tested material was cathodically electrolyzed in the alkaline solution containing cerium salt, and uniform films containing cerium were obtained after the two-step treatment. It is found that the films obtained by TS2/TS7 and TS3/TS7 techniques are about 4.0 and 3.0 m in thickness, respectively. The material has better corrosion resistance in the chloride solution after the two-step electrolysis treatment compared with the one-step treated and naked specimens.

  13. Fabrication of Cerium Oxide and Uranium Oxide Microspheres for Space Nuclear Power Applications

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey A. Katalenich; Michael R. Hartman; Robert C. O' Brien

    2013-02-01

    Cerium oxide and uranium oxide microspheres are being produced via an internal gelation sol-gel method to investigate alternative fabrication routes for space nuclear fuels. Depleted uranium and non-radioactive cerium are being utilized as surrogates for plutonium-238 (Pu-238) used in radioisotope thermoelectric generators and for enriched uranium required by nuclear thermal rockets. While current methods used to produce Pu-238 fuels at Los Alamos National Laboratory (LANL) involve the generation of fine powders that pose a respiratory hazard and have a propensity to contaminate glove boxes, the sol-gel route allows for the generation of oxide microsphere fuels through an aqueous route. The sol-gel method does not generate fine powders and may require fewer processing steps than the LANL method with less operator handling. High-quality cerium dioxide microspheres have been fabricated in the desired size range and equipment is being prepared to establish a uranium dioxide microsphere production capability.

  14. Excitation induced spectroscopic study and quenching effect in cerium samarium codoped lithium aluminoborate glasses

    Science.gov (United States)

    Kaur, Parvinder; Kaur, Simranpreet; Singh, Gurinder Pal; Arora, Deepawali; Kumar, Sunil; Singh, D. P.

    2016-08-01

    Lithium aluminium borate host has been codoped with cerium and samarium to prepare glass by conventional melt quench technique. Their structural and spectroscopic investigation has been carried out using XRD, FTIR and density measurements. The UV-Vis absorption spectra and fluorescence spectra (λexc.=380 nm and 400 nm) have been studied for spectroscopic analysis. The amorphous nature of the prepared samples is shown by XRD. The density is increasing with addition of cerium at the expense of aluminium, keeping other components constant. FTIR study also shows the presence of compact and stable tetrahedral BO4 units thus supporting the density results. The UV- Vis absorption spectra show a shift of optical absorption edge towards longer wavelength along with an increase in intensity of peaks with rising samarium concentration. The fluorescence spectra show a blue shift and subsequent suppression of cerium peaks with addition of samarium.

  15. Catalytic spectrophotometric determination of cerium by ion exchange separation coupled to a flow injection system

    International Nuclear Information System (INIS)

    A flow injection method is described intended for the determination of cerium based on its catalytic effect on the oxidation of gallocyanine by peroxydisulfate in acidic media. The proposed flow injection manifold incorporates a ion exchange separation system in the carrier stream. The decolorisation of gallocyanine due to its oxidation was used to monitor the reaction by spectrophotometry at 524 nm. The variables which affected the reaction rate were fully investigated. By this method cerium(4) can be determined in the range of 0.30-10.0 μg with a limit of detection of 0.25 μg. The relative standard deviation for ten replicate determinations of 1.0 μg of cerium(4) was 1.8 %

  16. Protection against corrosion in marine environments of AA6060 aluminium alloy by cerium chlorides

    International Nuclear Information System (INIS)

    Lanthanide salts are being considered as an environmentally friendly alternative to the classic systems based on chromates. The addition of small concentrations of cerium chloride to aerated aqueous 3.5% NaCl solution inhibits uniform and pitting corrosion processes of AA6060. Full immersion tests combined with different electrochemical techniques were involved to determine the protection degree and the inhibition character supplied by the cerium ion. Their microscopic and compositional features have been analyzed using SEM and EDS spectra. The results obtained show that the protective layer has heterogeneous composition. An alumina layer covers the aluminium matrix while dispersed cerium-rich islands deposited over the cathodic sites of the alloy. In the case of AA6060, α-Al(Fe,Mn)Si acts as permanent cathodic sites.

  17. Exposure of cerium oxide nanoparticles to kidney bean shows disturbance in the plant defense mechanisms

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Kidney bean roots uptake nCeO2 primarily without biotransformation. • Cerium reached the root vascular tissues through gaps in the Casparian strip. • On longer exposure to high concentration, roots demonstrate stress response. • In leaves, guaiacol peroxidase plays a major role in ROS scavenging. - Abstract: Overwhelming use of engineered nanoparticles demands rapid assessment of their environmental impacts. The transport of cerium oxide nanoparticles (nCeO2) in plants and their impact on cellular homeostasis as a function of exposure duration is not well understood. In this study, kidney bean plants were exposed to suspensions of ∼8 ± 1 nm nCeO2 (62.5 to 500 mg/L) for 15 days in hydroponic conditions. Plant parts were analyzed for cerium accumulation after one, seven, and 15 days of nCeO2 exposure. The primary indicators of stress like lipid peroxidation, antioxidant enzyme activities, total soluble protein and chlorophyll contents were studied. Cerium in tissues was localized using scanning electron microscopy and synchrotron μ-XRF mapping, and the chemical forms were identified using μ-XANES. In the root epidermis, cerium was primarily shown to exist as nCeO2, although a small fraction (12%) was biotransformed to Ce(III) compound. Cerium was found to reach the root vascular tissues and translocate to aerial parts with time. Upon prolonged exposure to 500 mg nCeO2/L, the root antioxidant enzyme activities were significantly reduced, simultaneously increasing the root soluble protein by 204%. In addition, leaf's guaiacol peroxidase activity was enhanced with nCeO2 exposure in order to maintain cellular homeostasis

  18. Exposure of cerium oxide nanoparticles to kidney bean shows disturbance in the plant defense mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Majumdar, Sanghamitra [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Peralta-Videa, Jose R. [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Bandyopadhyay, Susmita [Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Castillo-Michel, Hiram [European Synchrotron Radiation Facility, B.P. 220-38043 Grenoble, Cedex (France); Hernandez-Viezcas, Jose-Angel [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Sahi, Shivendra [Department of Biology, Western Kentucky University, Bowling Green, KY 42101 (United States); Gardea-Torresdey, Jorge L., E-mail: jgardea@utep.edu [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States)

    2014-08-15

    Graphical abstract: - Highlights: • Kidney bean roots uptake nCeO{sub 2} primarily without biotransformation. • Cerium reached the root vascular tissues through gaps in the Casparian strip. • On longer exposure to high concentration, roots demonstrate stress response. • In leaves, guaiacol peroxidase plays a major role in ROS scavenging. - Abstract: Overwhelming use of engineered nanoparticles demands rapid assessment of their environmental impacts. The transport of cerium oxide nanoparticles (nCeO{sub 2}) in plants and their impact on cellular homeostasis as a function of exposure duration is not well understood. In this study, kidney bean plants were exposed to suspensions of ∼8 ± 1 nm nCeO{sub 2} (62.5 to 500 mg/L) for 15 days in hydroponic conditions. Plant parts were analyzed for cerium accumulation after one, seven, and 15 days of nCeO{sub 2} exposure. The primary indicators of stress like lipid peroxidation, antioxidant enzyme activities, total soluble protein and chlorophyll contents were studied. Cerium in tissues was localized using scanning electron microscopy and synchrotron μ-XRF mapping, and the chemical forms were identified using μ-XANES. In the root epidermis, cerium was primarily shown to exist as nCeO{sub 2}, although a small fraction (12%) was biotransformed to Ce(III) compound. Cerium was found to reach the root vascular tissues and translocate to aerial parts with time. Upon prolonged exposure to 500 mg nCeO{sub 2}/L, the root antioxidant enzyme activities were significantly reduced, simultaneously increasing the root soluble protein by 204%. In addition, leaf's guaiacol peroxidase activity was enhanced with nCeO{sub 2} exposure in order to maintain cellular homeostasis.

  19. The solvent extraction of cerium from sulphate solution - mini plant trials

    International Nuclear Information System (INIS)

    Full text: The Mt. Weld deposit in Western Australia has a complex rare earth mineralisation. The rare earth phosphate minerals, which include monazite, are amenable to conventional caustic cracking followed by hydrochloric acid dissolution of the trivalent rare earths. The presence of the mineral cerianite in the ore, which is unaffected by the alkali attack, results in rejection of a considerable proportion of the cerium to the acid leach residue. The recovery of cerium from a sulphate solution, resulting from the processing of such a residue, is the subject of the current paper. The liquor treated by solvent extraction contained 63 g L-1 rare earths and the cerium to total rare earth ratio was 75%. Other impurities, including Fe and Th, totalled 2000 ppm. A solvent mixture of commercially available extractants in a low aromatic content diluent was used to extract Ce4+ selectively over the trivalent rare earths. Partial co-extraction of Fe and Th occurred but it was found that these elements were not easily stripped and therefore selective back extraction of cerium was possible. The cerium was stripped from the organic phase by hydrochloric acid and hydrogen peroxide. In continuous counter-current trials two extraction stages and three strip stages were used. In order to produce two grades of strip liquor, stripping was divided into two circuits. The first strip circuit consisting of a single stage, contained proportionally more of the trivalent rare earths. The second strip circuit, consisting of two stages, removed the remaining cerium with proportionally less of the rare earths. A bleed solvent stream was treated for removal of impurities to prevent build-up in the solvent. In the continuous counter current trials, 95% Ce4+ extraction was achieved and the Ce to total rare earth ratio was upgraded to > 99%

  20. Luminescence properties and decay kinetics of nano ZnO powder doped with cerium ions

    Energy Technology Data Exchange (ETDEWEB)

    Panda, Nihar Ranjan, E-mail: nihar@iitbbs.ac.in [Indian Institute of Technology Bhubaneswar, Bhubaneswar 751013, Orissa (India); Acharya, B.S., E-mail: bsacharya1950@gmail.com [Department of Physics, C.V. Raman College of Engineering, Bhubaneswar 752054, Orissa (India); Singh, Th. Basanta [Luminescence Dating Laboratory, Manipur University, Imphal 795003 (India); Gartia, R.K. [Department of Physics, Manipur University, Imphal 795003 (India)

    2013-04-15

    ZnO nanopowders doped with cerium ions (1.2 and 1.5 at. wt.%) were synthesized through soft solution route using ultrasound. Sonication has been found to be an effective way for doping rare earth ions like cerium into ZnO. This was confirmed from energy dispersive analysis of X-rays (EDAX) measurement. Further, optical absorption and photoluminescence (PL) measurements corroborate this finding. X-ray diffraction (XRD) studies show the increase of crystallite size and unit cell volume with doping of cerium ions. Formation of fibrous structure of ZnO:Ce was observed from the transmission electron microscopy (TEM) measurements. Although the structural measurements indicate Ce{sup 4+} ion occupying substitutional site in ZnO, PL and absorption studies confirmed the presence of Ce{sup 3+} ion in the powder. The coexistence of Ce{sup 3+} and Ce{sup 4+} ions has been explained on the basis of conversion of Ce{sup 3+} to Ce{sup 4+} in the oxidizing environment. Thermoluminescence (TL) and photo-stimulated decay of luminescence (PSDL) decay studies give an idea of various trapping levels present in the band gap of ZnO. These traps release electrons during optical stimulation to give bimolecular kinetics in nano ZnO:Ce powders. -- Highlights: ► Sonication: an effective way of incorporation of cerium ions into ZnO. ► Site dependent characteristic emission of cerium. ► Energy transfer from host lattice to cerium ions. ► Mono and bimolecular kinetics of ZnO:Ce.

  1. Ultraviolet Laser Induced Photochromic Centers in Cerium Doped Calcium-Fluoride

    Science.gov (United States)

    Pogatshnik, Gerald Joseph

    The optical excitation of the lowest 4f to 5d transition in Ce('3+):CaF(,2) using the 308 nm output of a XeCl excimer laser results in a strong coloration of the sample. The centers created by the UV laser irradiation were identified, using low temperature absorption spectroscopy, and were found to be divalent cerium ions at cubic sites in the crystal. The system exhibits photochromic properties in that the crystal can be returned to the original transparent state by illuminating it with light which is absorbed by the divalent cerium ions. The creation process for these photochromic centers involves a resonant two-photon transition from the 4f ground state of the cerium ion to the conduction band of the CaF(,2) host. The lowest 5d level of the cerium ion serves as the real intermediate state for this transition. The photoionized electron can be trapped by another trivalent cerium ion at a site of cubic symmetry. These impurity sites with O(,h) symmetry result when the charge compensator associated with the rare earth ion is somewhat removed from the cerium ion site. The charge compensator is needed to maintain charge neutrality in the crystal when a trivalent rare earth is substituted for a Ca ion in the host lattice. The absence of a local charge compensator at a Ce('3+) site with O(,h) symmetry, provides a net positive Coulombic potential, which aids in the trapping of electrons from the conduction band. The capture of an electron by a cerium ion at cubic site, changes the valence state of the ion to Ce('2+). The presence of divalent cerium, with its broad absorption bands in the visible region of the spectrum, accounts for the coloration of the crystal after illumination with UV laser light. A model for the production of the photochromic centers, based on a rate equation is presented. This model reflects the two-photon nature of the photoionization process, as well as the optical bleaching characteristics of the photochromic center, and accurately reproduces the

  2. [Laser resonance ionization spectroscopy of even-parity autoionization states of cerium atom].

    Science.gov (United States)

    Li, Zhi-ming; Zhu, Feng-rong; Zhang, Zi-bin; Ren, Xiang-jun; Deng, Hu; Zhai, Li-hua; Zhang, Li-xing

    2004-12-01

    This paper describes the investigation of even-parity autoionization states of cerium atoms by three-step three-color resonance ionization spectroscopy (RIS). Twenty-seven odd-parity highly excited levels, whose transition probability is high, were used in this research. One hundred and forty-one autoionization states were found by these channels with the third-step laser scanning in the wavelength range of 634-670 nm. The ionization probabilities of different channels, which had higher cross sections, were compared. On the basis of this, eight optimal photoionization schemes of cerium atom have been given. PMID:15828309

  3. Photocatalytic action of cerium molybdate and iron-titanium oxide hollow nanospheres on Escherichia coli

    International Nuclear Information System (INIS)

    This study is focused on the production of hollow nanospheres that reveal antibacterial action. Cerium molybdate and iron-titanium oxide hollow nanospheres with a diameter of 175 ± 15 and 221 ± 10 nm, respectively, were synthesized using emulsion polymerization and the sol–gel process. Their morphology characterization was accomplished using scanning electron microscopy. Their antibacterial action was examined on pure culture of Escherichia coli considering the loss of their viability. Both hollow nanospheres presented photocatalytic action after illumination with blue–black light, but those of cerium molybdate also demonstrated photocatalytic action in the dark. Therefore, the produced nanospheres can be used for antibacterial applications.

  4. METHOD OF SEPARATING TETRAVALENT PLUTONIUM VALUES FROM CERIUM SUB-GROUP RARE EARTH VALUES

    Science.gov (United States)

    Duffield, R.B.; Stoughton, R.W.

    1959-02-01

    A method is presented for separating plutonium from the cerium sub-group of rare earths when both are present in an aqueous solution. The method consists in adding an excess of alkali metal carbonate to the solution, which causes the formation of a soluble plutonium carbonate precipitate and at the same time forms an insoluble cerium-group rare earth carbonate. The pH value must be adjusted to bctween 5.5 and 7.5, and prior to the precipitation step the plutonium must be reduced to the tetravalent state since only tetravalent plutonium will form the soluble carbonate complex.

  5. Cerium Binding Activity of Pectins Isolated from the Seagrasses Zostera marina and Phyllospadix iwatensis

    OpenAIRE

    Valeri Kovalev; Maxim Khotimchenko; Yuri Khotimchenko; Elena Khozhaenko

    2012-01-01

    Cerium binding activity of three different water soluble pectin compounds of different origin was studied in a batch sorption system. The Langmuir, Freundlich and BET sorption models were adopted to describe the binding reactions between metal ions and pectin molecules. The Langmuir model provided the best fit. Within the pH range from 4.0 to 6.0, the largest amount of the cerium ions was bound by pectin isolated from the seagrass Phylospadix iwatensis in comparison to pectin extracted from t...

  6. Synthesis and characterization of two dimensional metal organic framework of cerium with tetraaza macrocyclic

    Energy Technology Data Exchange (ETDEWEB)

    Bt Safiin, Nurul Atikah; Yarmo, Ambar; Yamin, Bohari M. [School of Chemical Science and Food Technology. Faculty Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan (Malaysia)

    2013-11-27

    A two dimensional metal organic framework containing cerium sufate layers and ethylenediaminium between layers was obtained by refluxing the mixture of cerium sulphate and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7, 14-diene bromide. The complex was characterized by infrared spectroscopy and microelemental analysis. X-ray study showed that the complex adopts eleven coordination environments about the central atom. Thermogravimetric study showed the removal of water molecules at about 70°C followed by a gradual mass loss until the whole structure collapsed at about 400°C.

  7. Thin film growth of epitaxial gadolinium oxide, gadolinium yttrium oxide, and gadolinium cerium oxide by electrodeposition

    International Nuclear Information System (INIS)

    Thin films of gadolinium oxide, gadolinium yttrium oxide, and gadolinium cerium oxide were electrodeposited from non-aqueous baths. The films were on the order of 15 nm thick, and were grown epitaxially on textured nickel-tungsten substrates. The effect of deposition rate, annealing temperature and secondary metals on crystallinity and crystal orientation was investigated by X-ray diffraction and transmission electron microscopy. Slower rates, higher temperatures and low concentrations of yttrium improve the crystallinity of gadolinium oxide films, whereas the introduction of cerium induced polycrystallinity.

  8. A corrosion resistant cerium oxide based coating on aluminum alloy 2024 prepared by brush plating

    International Nuclear Information System (INIS)

    Cerium oxide based coatings were prepared on AA2024 Al alloy by brush plating. The characteristic of this technology is that hydrogen peroxide, which usually causes the plating solution to be unstable, is not necessary in the plating electrolyte. The coating showed laminated structures and good adhesive strength with the substrate. X-ray diffraction and X-ray photoelectron spectroscopy analysis showed that the coatings were composed of Ce(III) and Ce(IV) oxides. The brush plated coatings on Al alloys improved corrosion resistance. The influence of plating parameters on structure and corrosion resistance of the cerium oxide based coating was studied.

  9. Plasma-electrolytic formation of cerium-containing surface structures on titanium and aluminum

    International Nuclear Information System (INIS)

    The possibility of obtaining cerium-containing structures on aluminum and titanium by the plasma-electrolytic method with the use of aqueous solutions of electrolytes containing Ce3+ polyphosphate complexes was demonstrated. The amount of cerium in the films obtained depended on the molar ratio n [polyphosphate]/[Ce3+] in the electrolyte. The films contained crystalline CePO4. The growth of films on titanium was characterized by the formation of secondary layers by the mechanism involving the appearance of new phase nuclei followed by their expansion

  10. Thin film growth of epitaxial gadolinium oxide, gadolinium yttrium oxide, and gadolinium cerium oxide by electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Mann, Jonathan R., E-mail: jonathan.mann@nrel.gov; Bhattacharya, Raghu N.

    2010-10-29

    Thin films of gadolinium oxide, gadolinium yttrium oxide, and gadolinium cerium oxide were electrodeposited from non-aqueous baths. The films were on the order of 15 nm thick, and were grown epitaxially on textured nickel-tungsten substrates. The effect of deposition rate, annealing temperature and secondary metals on crystallinity and crystal orientation was investigated by X-ray diffraction and transmission electron microscopy. Slower rates, higher temperatures and low concentrations of yttrium improve the crystallinity of gadolinium oxide films, whereas the introduction of cerium induced polycrystallinity.

  11. Synthesis and characterization of platinum supported on alumina doped with cerium catalyst

    International Nuclear Information System (INIS)

    The synthesis and characterization of gamma-alumina doped with cerium as platinum support for the automobile exhaust catalyst are described. Platinum/alumina/ceria catalyst were prepared by impregnation of hexachloroplatinic acid and sintered at 500 degree Celsius to obtain metal dispersions of 1.0 wt%. Catalyst distribution inside the powder and the effects of the addition of cerium to alumina were analyzed by the scanning electron microscopy (SEM) and x-ray fluorescence spectroscopy (XRF). The results showed that the alumina - supported catalysts contained well dispersion of the noble metal

  12. Electronic interaction in oxide copper-cerium catalysts according to exoemission data

    International Nuclear Information System (INIS)

    The electronic properties of the oxide copper-cerium catalysts with different copper content are studied through the exoemission methods. It is shown, that the introduction of the copper increases the CeO2 emission activity and the number of the electrons, emitted from the catalysts surface, as compared to the surface of the CeO2 and CuO initial oxides. It is concluded, that the event of synergism in the exoemission from the studied systems surface is conditioned through the electronic interactions, including the electronic transitions on the cerium oxide - copper oxide boundary

  13. A corrosion resistant cerium oxide based coating on aluminum alloy 2024 prepared by brush plating

    Energy Technology Data Exchange (ETDEWEB)

    Tang Junlei; Han Zhongzhi [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zuo Yu, E-mail: zuoy@mail.buct.edu.cn [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Tang Yuming [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2011-01-15

    Cerium oxide based coatings were prepared on AA2024 Al alloy by brush plating. The characteristic of this technology is that hydrogen peroxide, which usually causes the plating solution to be unstable, is not necessary in the plating electrolyte. The coating showed laminated structures and good adhesive strength with the substrate. X-ray diffraction and X-ray photoelectron spectroscopy analysis showed that the coatings were composed of Ce(III) and Ce(IV) oxides. The brush plated coatings on Al alloys improved corrosion resistance. The influence of plating parameters on structure and corrosion resistance of the cerium oxide based coating was studied.

  14. Evaluation of Antiproliferative Potential of Cerium Oxide Nanoparticles on HeLa Human Cervical Tumor Cell

    Directory of Open Access Journals (Sweden)

    Zoriţa Diaconeasa

    2015-05-01

    Full Text Available Cerium oxide nanoparticles (CeO2 nanoparticles as nanomaterials have promising biomedical applications. In this paper, the cytotoxicity induced by CONPs human cervical tumor cells was investigated. Cerium oxide nanoparticles were synthesized using the precipitation method. The nanoparticles were found to inhibit the proliferation of HeLa human cervical tumor cells in a dose dependent manner but did not showed to be cytotoxic as analyzed by MTT assay. The administrated treatment decreased the HeLa cell viability cells from 100% to 65% at the dose of 100 μg/mL.

  15. XPS study of cerium conversion coating on the anodized 2024 aluminum alloy

    International Nuclear Information System (INIS)

    Cerium-rich conversion coating was deposited on anodized aluminum alloy 2024 in a solution containing Ce(NO3)3. X-ray photoelectron spectroscopy (XPS) was used as the analysis method. The composition of the Ce conversion coating deposited on the anodized 2024 alloy was investigated using this method. It was revealed that the coating predominately consisted of three-valent state cerium compound. Some of the CeIII was oxidized to CeIV in the outer layer coating

  16. Synthesis and characterization of two dimensional metal organic framework of cerium with tetraaza macrocyclic

    International Nuclear Information System (INIS)

    A two dimensional metal organic framework containing cerium sufate layers and ethylenediaminium between layers was obtained by refluxing the mixture of cerium sulphate and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7, 14-diene bromide. The complex was characterized by infrared spectroscopy and microelemental analysis. X-ray study showed that the complex adopts eleven coordination environments about the central atom. Thermogravimetric study showed the removal of water molecules at about 70°C followed by a gradual mass loss until the whole structure collapsed at about 400°C

  17. Decontamination of alpha contaminated metallic waste by cerium IV redox process

    International Nuclear Information System (INIS)

    Decontamination of alpha contaminated metallic waste is an important aspect in the management of waste generated during dismantling and decommissioning of nuclear facilities. Present work on cerium redox process targets decontamination of alpha contaminated metallic waste till it qualifies for the non alpha waste category for disposal in near surface disposal facility. Recovery of the alpha radio nuclides and cerium from aqueous secondary waste streams was also studied deploying solvent extraction process and established. The alpha-lean secondary waste stream has been immobilised in cement based matrix for final disposal. (author)

  18. Dissociation of outer membrane for Escherichia coli cell caused by cerium nitrate

    Institute of Scientific and Technical Information of China (English)

    陈爱美; 施庆珊; 冯劲; 欧阳友生; 陈仪本; 谭绍早

    2010-01-01

    The biological effect of cerium nitrate on the outer membrane(OM) of Escherichia coli(E.coli) cell was studied,and the antim-icrobial mechanism of rare earth elements was explored.The antimicrobial effect of cerium nitrate on E.coli cell was valued by plate count method,and the morphology change of E.coli cell was observed with scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results showed that the E.coli cell suspension was flocculated when the concentration of Ce(NO3)3?6H2O...

  19. Comparative Study of Magnetic Instabilities in Cerium Compounds

    International Nuclear Information System (INIS)

    The variety of new phases and physical phenomena discovered in intermetallic compounds containing Rare Earths or Actinides has motivated, during the last four decades, the sustained study of their magnetic phase diagrams.The current interest is focused on the investigation of the region of the phase diagram where the magnetic order of Cerium, Ytterbium and Uranium based systems is destabilized.In this region different behaviours have been detected, such as non conventional superconductivity and the anomalous dependencies of the thermal, magnetic and transport properties at very low temperatures, associated to non-Fermi liquid behaviour.A simple model, the Doniach diagram, has guided the interpretation of the destabilization of the magnetic order in the previously mentioned systems.However, most of the systems that have been studied so far cannot be described within this model.This fact has motivated the development of a phenomenological classification of phase diagrams that has been mostly applied to cerium based compounds.This classification defines three types of phase diagrams, that can be distinguished by the way in which the magnetic transition is suppressed when a control parameter (such as doping or pressure) is driven towards its critical value.Within this scenario, we study the suppression of the antiferromagnetic order of the intermetallic compounds CeIn3, CeRh2Si2 and CePd2Al3 as a function of Ce-ligand alloying.The resulting systems, CeIn3-xSnx, Ce(CuxRh1-x)2Si2 and CePd2-xNixAl3, present different crystalline structures and the effects produced by the alloying process are different in each case.We analyse the resulting magnetic phase diagrams, and compare them with the above mentioned phenomenological classification.With such a purpose, we study in detail the region in which the magnetic instability takes place, in the proximity of the respective critical concentrations.Taking into account both our results and those reported in the literature, we

  20. Fate of cerium dioxide nanoparticles in endothelial cells: exocytosis

    International Nuclear Information System (INIS)

    Although cytotoxicity and endocytosis of nanoparticles have been the subject of numerous studies, investigations regarding exocytosis as an important mechanism to reduce intracellular nanoparticle accumulation are rather rare and there is a distinct lack of knowledge. The current study investigated the behavior of human microvascular endothelial cells to exocytose cerium dioxide (CeO2) nanoparticles (18.8 nm) by utilization of specific inhibitors [brefeldin A; nocodazole; methyl-β-cyclodextrin (MβcD)] and different analytical methods (flow cytometry, transmission electron microscopy, inductively coupled plasma mass spectrometry). Overall, it was found that endothelial cells were able to release CeO2 nanoparticles via exocytosis after the migration of nanoparticle containing endosomes toward the plasma membrane. The exocytosis process occurred mainly by fusion of vesicular membranes with plasma membrane resulting in the discharge of vesicular content to extracellular environment. Nevertheless, it seems to be likely that nanoparticles present in the cytosol could leave the cells in a direct manner. MβcD treatment led to the strongest inhibition of the nanoparticle exocytosis indicating a significant role of the plasma membrane cholesterol content in the exocytosis process. Brefeldin A (inhibitor of Golgi-to-cell-surface-transport) caused a higher inhibitory effect on exocytosis than nocodazole (inhibitor of microtubules). Thus, the transfer from distal Golgi compartments to the cell surface influenced the exocytosis process of the CeO2 nanoparticles more than the microtubule-associated transport. In conclusion, endothelial cells, which came in contact with nanoparticles, e.g., after intravenously applied nano-based drugs, can regulate their intracellular nanoparticle amount, which is necessary to avoid adverse nanoparticle effects on cells

  1. Thermoluminescence of cerium and terbium -doped calcium pyrophosphate

    Energy Technology Data Exchange (ETDEWEB)

    Roman L, J.; Cruz Z, E. [UNAM, Instituto de Ciencias Nucleares, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Lozano R, I. B.; Diaz G, J. A. I., E-mail: jesus.roman@nucleares.unam.mx [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria No. 694, 11500 Mexico D. F. (Mexico)

    2015-10-15

    The aim of this work is to report the thermoluminescence (Tl) response of Calcium Pyrophosphate phosphor doped with Cerium and Terbium impurities (Ca{sub 2}P{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+}). The phosphors were synthesized using the co-precipitation method and annealed at 900 degrees C by two hours for obtain the β phase. The intentional doping with Ce and Tb ions was 1 at.% and 0.1 at.%, whereas in the EDS results the concentration of impurities was 0.39 at.% and 0.05 at.%, respectively. The superficial morphology of phosphor is mainly composed by thin wafers of different size. All samples were exposed to gamma rays from {sup 60}Co in the Gammacell-200 irradiator. The Tl response of the phosphor was measured from Rt up to 350 degrees C and under nitrogen atmosphere in a Harshaw TLD 3500 reader. The glow curves of the Ca{sub 2}P{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+} powders showed a broad intense Tl peak centered at 165 degrees C and a shoulder at approximate 260 degrees C was observed. A linear Tl response in the range of absorbed dose of 0.2 to 10 Gy was obtained. Tl glow curves were analyzed using the initial rise (IR)and computerized glow curve deconvolution methods to evaluate the kinetics parameters such as activation energy (E), frequency factor (s) and kinetic order (b). (Author)

  2. Fate of cerium dioxide nanoparticles in endothelial cells: exocytosis

    Energy Technology Data Exchange (ETDEWEB)

    Strobel, Claudia, E-mail: Claudia.Strobel@med.uni-jena.de [Jena University Hospital – Friedrich Schiller University Jena, Department of Experimental Radiology, Institute of Diagnostic and Interventional Radiology (Germany); Oehring, Hartmut [Jena University Hospital – Friedrich Schiller University Jena, Institute of Anatomy II (Germany); Herrmann, Rudolf [University of Augsburg, Department of Physics (Germany); Förster, Martin [Jena University Hospital – Friedrich Schiller University Jena, Department of Internal Medicine I, Division of Pulmonary Medicine and Allergy/Immunology (Germany); Reller, Armin [University of Augsburg, Department of Physics (Germany); Hilger, Ingrid, E-mail: ingrid.hilger@med.uni-jena.de [Jena University Hospital – Friedrich Schiller University Jena, Department of Experimental Radiology, Institute of Diagnostic and Interventional Radiology (Germany)

    2015-05-15

    Although cytotoxicity and endocytosis of nanoparticles have been the subject of numerous studies, investigations regarding exocytosis as an important mechanism to reduce intracellular nanoparticle accumulation are rather rare and there is a distinct lack of knowledge. The current study investigated the behavior of human microvascular endothelial cells to exocytose cerium dioxide (CeO{sub 2}) nanoparticles (18.8 nm) by utilization of specific inhibitors [brefeldin A; nocodazole; methyl-β-cyclodextrin (MβcD)] and different analytical methods (flow cytometry, transmission electron microscopy, inductively coupled plasma mass spectrometry). Overall, it was found that endothelial cells were able to release CeO{sub 2} nanoparticles via exocytosis after the migration of nanoparticle containing endosomes toward the plasma membrane. The exocytosis process occurred mainly by fusion of vesicular membranes with plasma membrane resulting in the discharge of vesicular content to extracellular environment. Nevertheless, it seems to be likely that nanoparticles present in the cytosol could leave the cells in a direct manner. MβcD treatment led to the strongest inhibition of the nanoparticle exocytosis indicating a significant role of the plasma membrane cholesterol content in the exocytosis process. Brefeldin A (inhibitor of Golgi-to-cell-surface-transport) caused a higher inhibitory effect on exocytosis than nocodazole (inhibitor of microtubules). Thus, the transfer from distal Golgi compartments to the cell surface influenced the exocytosis process of the CeO{sub 2} nanoparticles more than the microtubule-associated transport. In conclusion, endothelial cells, which came in contact with nanoparticles, e.g., after intravenously applied nano-based drugs, can regulate their intracellular nanoparticle amount, which is necessary to avoid adverse nanoparticle effects on cells.

  3. Effects of Cerium Oxide Nanoparticles on Sorghum Plant Traits

    Science.gov (United States)

    Mu, L.; Chen, Y.; Darnault, C. J. G.; Rauh, B.; Kresovich, S.; Korte, C.

    2015-12-01

    Nanotechnology and nanomaterials are considered as the development of the modern science. However, besides with that wide application, nanoparticles arouse to the side effects on the environment and human health. As the catalyst of ceramics and fuel industry, Cerium (IV) oxide nanoparticles (CeO2 NPs) can be found in the environment following their use and life-cycle. Therefore, it is critical to assess the potential effects that CeO2 NPs found in soils may have on plants. In this study, CeO2 NPs were analyzed for the potential influence on the sorghum [Sorghum bicolor (L.) Moench] (Reg. no. 126) (PI 154844) growth and traits. The objectives of this research were to determine whether CeO2 NPs impact the sorghum germination and growth characteristics. The sorghum was grown in the greenhouse located at Biosystems Research Complex, Clemson University under different CeO2 NPs treatments (0mg; 100mg; 500mg; 1000mg CeO2 NPs/Kg soil) and harvested around each month. At the end of the each growing period, above ground vegetative tissue was air-dried, ground to 2mm particle size and compositional traits estimated using near-infrared spectroscopy. Also, the NPK value of the sorghum tissue was tested by Clemson Agriculture Center. After the first harvest, the result showed that the height of above ground biomass under the nanoparticles stress was higher than that of control group. This difference between the control and the nanoparticles treatments was significant (F>F0.05; LSD). Our results also indicated that some of the compositional traits were impacted by the different treatments, including the presence and/or concentrations of the nanoparticles.

  4. Contribution to research on the metabolism of fission product. Studies on the physico-chemical state and the metabolic fate of radio-cerium solution

    International Nuclear Information System (INIS)

    This paper describes a study of the physico-chemical state of radio-cerium in dilute solutions on the tracer scale, as a function of the pH of the solution. The way in which this radioelement is transported in the blood is studied in vitro and in vivo, with reference to the ionic or colloidal state of the radio-cerium used. The distribution of cerium amongst the various components of the blood is studied by a new method of blood fractionation and by paper electrophoresis. Evidence of a cerium globulin connection is shown in the case of ionic cerium. A study of the initial distribution of radio-cerium in rats, after intravenous administration of ionic or colloidal solutions, shows considerable differences according to the physico-chemical state of the cerium injected. (author)

  5. Transport properties of lithium- lead-vanadium-telluride glass and glass ceramics

    International Nuclear Information System (INIS)

    Glasses with the chemical composition 35Li2O-(45-x)V2O5−20PbO-xTeO2 (where x = 2.5, 5, 7.5, 10, 15 mol %) have prepared by conventional melt quenching method. The electrical conductivity of Li+ ion conducting lead vanadium telluride glass samples has been carried out both as a function of temperature and frequency in the temperature range 503K-563K and over frequencies 40 Hz to 10 MHz. The electronic conduction has been observed in the present systems. When these samples annealed around 400°C for 2hour become the glass ceramic, which also shows increase tendency of conductivity. SEM confines glass and glass ceramic nature of the prepared samples

  6. Synthesis of the titanium phosphide telluride Ti 2PTe 2: A thermochemical approach

    Science.gov (United States)

    Philipp, Frauke; Schmidt, Peer; Milke, Edgar; Binnewies, Michael; Hoffmann, Stefan

    2008-04-01

    The phosphide telluride Ti 2PTe 2 can be synthesised from the elements or from oxides in a thermite type reaction. Both ways have been optimised by consideration of the thermodynamic behaviour of the compound. Hence, the investigation of phase equilibria in the ternary system Ti/P/Te and of the thermal decomposition of Ti 2PTe 2 was necessary. This investigation was performed by using different experimental approaches as total pressure measurements, thermal analysis and mass spectrometry. The results were supported and further analysed by thermodynamic modelling of the ternary system. It was shown that Ti 2PTe 2(s) decomposes to Ti 2P (s) and Te 2(g) in six consecutive steps. The growth of single crystals of Ti 2PTe 2 is thermodynamically described as a chemical vapour transport with TiCl 4(g) acting as the transport agent.

  7. Evaluation of DAST and zinc telluride nonlinear crystals for efficient terahertz generation

    International Nuclear Information System (INIS)

    Terahertz (THz) signal is generated from 4-N, N-dimethylamino-4’-N’-methyl-stilbazolium tosylate (i.e. DAST Crystal) and Zinc telluride (ZnTe) nonlinear crystals by employing 140 fs laser pulses at 800 nm with 80 MHz repetition rate. The semi insulating gallium arsenide photoconductive stripline antennas (gap =5 µm, length = 20 µm) is used as a Terahertz detector. The detected temporal profile of Terahertz radiation generated from DAST crystal is high as compared to ZnTe crystal in terms of amplitude. THz effective bandwidths of these crystals are extended up to 1.1 THz range. The potential of THz generation of DAST and ZnTe crystals are evaluated with respect to incident laser power

  8. The use of cadmium telluride detectors for the qualitative analysis of diagnostic x-ray spectra.

    Science.gov (United States)

    Di Castro, E; Pani, R; Pellegrini, R; Bacci, C

    1984-09-01

    A method is introduced for the evaluation of x-ray spectra from x-ray machines operating in the range 50-100 kVp using a cadmium telluride (CdTe) detector with low detection efficiency. The pulse height distribution obtained with this kind of detector does not represent the true photon spectra owing to the presence of K-escape, Compton scattering, etc.; these effects were evaluated using a Monte Carlo method. A stripping procedure is described for implementation on a Univac 1100/82 computer. The validity of our method was finally tested by comparison with experimental results obtained with a Ge detector and with data from the literature; the results are in good agreement with published data. PMID:6483976

  9. Ion Beam Induced Charge Collection (IBICC) Studies of Cadmium Zinc Telluride (CZT) Radiation Detectors

    International Nuclear Information System (INIS)

    Cadmium Zinc Telluride is an emerging material for room temperature radiation detectors. In order to optimize the performance of these detectors, it is important to determine how the electronic properties of CZT are related to the presence of impurities and defects that are introduced during the crystal growth and detector fabrication. At the Sandia microbeam facility IBICC and Time Resolved IBICC (TRIBICC) were used to image electronic properties of various CZT detectors. Two-dimensional areal maps of charge collection efficiency were deduced from the measurements. In order to determine radiation damage to the detectors, we measured the deterioration of the IBICC signal as the function of dose. A model to explain quantitatively the pattern observed in the charge collection efficiency maps of the damaged detectors has been developed and will be discussed in the paper

  10. Electronic properties of chlorine doped cadmium telluride used as high energy photoconductive detector

    International Nuclear Information System (INIS)

    A new high energy X-ray chlorine doped Cadmium Telluride (CdTe:Cl) photoconductor is described. We discuss different deposition techniques (Sputtering, Evaporation, Electroless) to realize ohmic contacts which have low leakage current and which allow high applied electric field. The temperature dependence of the dark current give an activation energy of 0.6 eV for standard CdTe:Cl. The transient response of photoconductors under high X-ray energy beams has been characterized using three different pulse duration 150 ps, 30 ns and 4 μs. Sensitivity and speed of response are studied as a function of neutron pre-irradiated doses (0, 1014, 1015, 1016 n/cm2): neutron irradiations reduce the carrier lifetime at the expense of a lower sensitivity

  11. First operation of cesium telluride photocathodes in the TTF injector RF gun

    CERN Document Server

    Sertore, D; Flöttmann, K; Stephan, F; Zapfe, K; Michelato, P

    2000-01-01

    During the run 1998/1999 a new injector based on a laser-driven RF gun was brought in operation at the TESLA Test Facility (TTF) linac at DESY, in order to produce the beam structure and quality required either by TeV collider and SASE FEL experiments. High quantum efficiency cesium telluride photocathodes, prepared at Milano and transferred to DESY, have been successfully operated in the RF gun. A bunch charge of 50 nC, only limited by space charge effects, was achieved. The photocathodes have shown an operative lifetime of several months. A new cathode surface finishing has showed a promising decrease of the photocathode dark current. Measurements of dark current, quantum efficiency and lifetime are reported.

  12. Cadmium telluride quantum dots as pH-sensitive probes for tiopronin determination

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yunqing; Ye Chao; Zhu Zhenghui [Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009 (China); Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China); Hu Yuzhu [Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009 (China) and Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China)], E-mail: njhuyuzu@126.com

    2008-03-03

    The pH-sensitive cadmium telluride (CdTe) quantum dots (QDs) were used as proton probes for tiopronin determination. Based on the fluorescence quenching of CdTe QDs caused by tiopronin, a simple, rapid and specific quantitative method was proposed. Under the optimal conditions, the calibration plot of ln(F{sub 0}/F) with concentration of tiopronin was linear in the range of 0.15-20 {mu}g mL{sup -1}(0.92-122.5 {mu}mol L{sup -1}) with correlation coefficient of 0.998. The limit of detection (LOD) (3{sigma}/k) was 0.15 {mu}g mL{sup -1}(0.92 {mu}mol mL{sup -1}). The content of tiopronin in pharmaceutical tablet was determined by the proposed method and the result agreed with that obtained from the oxidation-reduction titration method and the claimed value.

  13. Cadmium telluride quantum dots as pH-sensitive probes for tiopronin determination

    International Nuclear Information System (INIS)

    The pH-sensitive cadmium telluride (CdTe) quantum dots (QDs) were used as proton probes for tiopronin determination. Based on the fluorescence quenching of CdTe QDs caused by tiopronin, a simple, rapid and specific quantitative method was proposed. Under the optimal conditions, the calibration plot of ln(F0/F) with concentration of tiopronin was linear in the range of 0.15-20 μg mL-1(0.92-122.5 μmol L-1) with correlation coefficient of 0.998. The limit of detection (LOD) (3σ/k) was 0.15 μg mL-1(0.92 μmol mL-1). The content of tiopronin in pharmaceutical tablet was determined by the proposed method and the result agreed with that obtained from the oxidation-reduction titration method and the claimed value

  14. Effect of different surfactants and thicknesses on electrodeposited films of bismuth telluride and its thermoelectric performance

    Science.gov (United States)

    Kulsi, Chiranjit; Mitra, Mousumi; Kargupta, Kajari; Ganguly, Saibal; Banerjee, Dipali; Goswami, Shyamaprosad

    2015-10-01

    Thin films of bismuth telluride using various surfactants such as sodium dodecyl sulfate (SDS) and polyvinylpyrrolidone (PVP) have been electrochemically deposited. The influence of different surfactants on crystal orientation and morphology was investigated and correlated with the thermoelectric performance of the electrodeposited films. Since thickness affects the thermoelectric performance compared to the surfactant, thickness- dependent thermoelectric performance has also been investigated. The carrier mobilities of the films obtained are significantly enhanced due to improved surface morphology using different surfactants. Between the two surfactants, films with SDS exhibited the higher value of thermoelectric power, power factor, and figure of merit, which is due to the effect of micelle formation. The XRD pattern of all the films, which are electrodeposited without surfactant or using SDS and PVP, showed preferred crystal orientation along the (018) direction. The roles of organic molecules in the development of nanoparticles with improved thermoelectric properties have been investigated.

  15. Chemical pressure and hidden one-dimensional behavior in rare earth tri-telluride

    Energy Technology Data Exchange (ETDEWEB)

    Sacchetti, A.; Degiorgi, L.; /Zurich, ETH; Giamarchi, T.; /Geneva U.; Ru, N.; Fisher, I.R.; /Stanford U., Geballe Lab.

    2009-12-14

    We report on the first optical measurements of the rare-earth tri-telluride charge-density-wave systems. Our data, collected over an extremely broad spectral range, allow us to observe both the Drude component and the single-particle peak, ascribed to the contributions due to the free charge carriers and to the charge-density-wave gap excitation, respectively. The data analysis displays a diminishing impact of the charge-density-wave condensate on the electronic properties with decreasing lattice constant across the rare-earth series. We propose a possible mechanism describing this behavior and we suggest the presence of a one-dimensional character in these two-dimensional compounds. We also envisage that interactions and umklapp processes might play a relevant role in the formation of the charge-density-wave state in these compounds.

  16. Nucleation and growth of noble metals on transition-metal di-tellurides

    Science.gov (United States)

    Hla, S. W.; Marinković, V.; Prodan, A.

    1997-04-01

    Transition-metal di-tellurides (α- and β-MoTe 2 and WTe 2) were used as substrates for nucleation and growth studies of noble metals. They represent a group of chemically closely related compounds with different surface topographies. Nucleation and growth of Ag and Au at room temperature were studied by means of UHV-STM, AFM and TEM. The results revealed that the growth and orientation of these metals are influenced by the topography of the substrate surfaces. Contrary to the growth on atomically flat α-MoTe 2, there is an enhanced diffusion and nucleation along the periodic surface troughs on β-MoTe 2 and WTe 2. The topography of their (001) surfaces is responsible for the orientation of metal (112) planes being parallel to the substrate surface.)

  17. Study of transport properties co - evaporated lead telluride (PbTe) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Khairnar, U.P.; Bhavsar, G.P. [Thin film laboratory, Physics Department Pratap College, Amalner (India); Pawar, P.H. [Department of Electronics, Jai-Hind College, Dhule (India)

    2002-07-01

    Thin films of lead telluride (PbTe) of thicknesses ranging from 1000 A to 2500 A have been prepared by co-evaporation (three temperature) technique, onto precleaned amorphous glass substrates at various temperatures. The deposited samples were annealed and annealed samples were used for characterization. Resistivity of these samples was measured by four-probe technique as a function of thickness and temperature. Activation energy for charge transport have been evaluated and found in the range of 0.09 to 0.106 eV. Thermoelectric power has been measured and found to be positive indicating that the samples are p-type semiconducting material. Mobility variation with temperature has been estimated (evaluated) and correlated with scattering mechanism in the entire range of temperature studied. The X-ray diffraction analysis confirmed that films are polycrystalline having cubic structure cell and lattice parameters are reported. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  18. Feasibility of using cadmium-zinc-telluride detectors in electronically collimated SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Singh, M. [Univ. of Southern California, Los Angeles, CA (United States). Dept. of Radiology; Doty, F.P.; Friesenhahn, S.J.; Butler, J.F. [Aurora Technologies Inc., San Diego, CA (United States)

    1995-08-01

    Replacing cryogenically cooled germanium (Ge) with room-temperature operable cadmium-zinc-telluride (CZT) semiconducting detectors as the first detector of an electronically collimated SPECT system would have certain practical advantages. To determine the feasibility of this approach, the authors have performed a theoretical and experimental study comparing the resolution and detection efficiency of a Ge based system to that of a CZT based system. The results indicate that the detection efficiency of a CZT based system would be a factor of 2.5 lower than a comparable Ge based system at 140keV and the spatial resolution would also be approximately a factor of two worse. However, at higher energies, the difference between CZT and Ge would decrease, and at 662keV, for example, the CZT and the Ge systems could have nearly equal detection efficiency and resolution.

  19. Feasibility of using cadmium-zinc-telluride detectors in electronically collimated SPECT

    International Nuclear Information System (INIS)

    Replacing cryogenically cooled germanium (Ge) with room-temperature operable cadmium-zinc-telluride (CZT) semiconducting detectors as the first detector of an electronically collimated SPECT system would have certain practical advantages. To determine the feasibility of this approach, the authors have performed a theoretical and experimental study comparing the resolution and detection efficiency of a Ge based system to that of a CZT based system. The results indicate that the detection efficiency of a CZT based system would be a factor of 2.5 lower than a comparable Ge based system at 140keV and the spatial resolution would also be approximately a factor of two worse. However, at higher energies, the difference between CZT and Ge would decrease, and at 662keV, for example, the CZT and the Ge systems could have nearly equal detection efficiency and resolution

  20. First experience DaTSCAN imaging using cadmium-zinc-telluride gamma camera SPECT.

    Science.gov (United States)

    Farid, Karim; Queneau, Mathieu; Guernou, Mohamed; Lussato, David; Poullias, Xavier; Petras, Slavomir; Caillat-Vigneron, Nadine; Songy, Bernard

    2012-08-01

    We report our first experience of brain DaTSCAN SPECT imaging using cadmium-zinc-telluride gamma camera (CZT-GC) in 2 cases: a 64-year-old patient suffering from essential tremor and a 73-year-old patient presenting with atypical bilateral extrapyramidal syndrome. In both cases, 2 different acquisitions were performed and compared, using a double-head Anger-GC, followed immediately by a second acquisition on CZT-GC. There were no significant visual differences between images generated by different GC. Our first result suggests that DaTSCAN SPECT is feasible on CZT-GC, allowing both injected dose and acquisition time reductions without compromising image quality. This experience needs to be evaluated in larger series. PMID:22785531

  1. Simple routes to synthesis and characterization of nanosized tin telluride compounds

    Energy Technology Data Exchange (ETDEWEB)

    Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box. 87317-51167 (Iran, Islamic Republic of); Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P.O. Box. 87317-51167 (Iran, Islamic Republic of); Bazarganipour, Mehdi [Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P.O. Box. 87317-51167 (Iran, Islamic Republic of); Davar, Fatemeh [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box. 87317-51167 (Iran, Islamic Republic of); Fazl, Alireza Amini [Institute for Colorants, Paint and Coatings (ICPC), Tehran, P.O. Box. 16765/654 (Iran, Islamic Republic of)

    2010-11-15

    Nanosized tin telluride compounds were prepared by chemical reduction process and hydrothermal methods. The nanosized SnTe compounds were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SnTe nanoalloy prepared by chemical reduction process presented quasi-spherical morphology with aggregation. The sizes of particle were 40-50 nm. The powder prepared by hydrothermal process was nearly nanospheres, and the particle sizes were 30-40 nm with narrow distribution. The effect of capping agent, reductant sort, and reaction temperature on the morphology, the particle sizes and the phase of SnTe alloys have been investigated. Experimental results indicated that N{sub 2}H{sub 4}.H{sub 2}O plays a crucial role in the formation of nanosized rode-like SnTe compounds.

  2. Internal Electric Field Behavior of Cadmium Zinc Telluride Radiation Detectors Under High Carrier Injection

    International Nuclear Information System (INIS)

    The behavior of the internal electric-field of nuclear-radiation detectors substantially affects the detector's performance. We investigated the distribution of the internal field in cadmium zinc telluride (CZT) detectors under high carrier injection. We noted the build-up of a space charge region near the cathode that produces a built-in field opposing the applied field. Its presence entails the collapse of the electric field in the rest of detector, other than the portion near the cathode. Such a space-charge region originates from serious hole-trapping in CZT. The device's operating temperature greatly affects the width of the space-charge region. With increasing temperature from 5 C to 35 C, its width expanded from about 1/6 to 1/2 of the total depth of the detector.

  3. Preparation of bismuth telluride thin film by electrochemical atomic layer epitaxy(ECALE)

    Institute of Scientific and Technical Information of China (English)

    ZHU Wen; YANG Junyou; GAO Xianhui; HOU Jie; BAO Siqian; FAN Xian

    2007-01-01

    Thin-layer electrochemical studies of the underpotential deposition(UPD)of Bi and Te on cold rolled silver substrate have been performed.The voltammetric analysis of underpotential shift demonstrates that the initial Te UPD on Bi-covered Ag and Bi UPD on Te-covered Ag fitted UPD dynamics mechanism.A thin film of bismuth telluride was formed by alternately depositing Te and Bi via an automated flow deposition system.X-ray diffraction indicated the deposits of Bi2Te3.Energy Dispersive X-ray Detector quantitative analysis gave a 2:3 stoichiornetric ratio of Bi to Te,which was consistent with X-ray Diffraction results.Electron probe microanalysis of the deposits showed a network structure that results from the surface defects of the cold rolled Ag substrate and the lattice mismatch between substrate and deposit.

  4. Cd-rich and Te-rich low-temperature photoluminescence in cadmium telluride

    International Nuclear Information System (INIS)

    Low-temperature photoluminescence emission spectra were measured in cadmium telluride (CdTe) samples in which composition was varied to promote either Cd or Te-rich stoichiometry. The ability to monitor stoichiometry is important, since it has been shown to impact carrier recombination. Te-rich samples show transitions corresponding to acceptor-bound excitons (∼1.58 eV) and free-electron to acceptor transitions (∼1.547 eV). In addition to acceptor-bound excitons, Cd-rich samples show transitions assigned to donor-bound excitons (1.591 eV) and Te vacancies at 1.552 eV. Photoluminescence is a noninvasive way to monitor stoichiometric shifts induced by post-deposition anneals in polycrystalline CdTe thin films deposited by close-spaced sublimation

  5. Degradation of nitrobenzene using titania photocatalyst co-doped with nitrogen and cerium under visible light illumination

    International Nuclear Information System (INIS)

    A type of nitrogen and cerium co-doped titania photocatalyst, which could degrade nitrobenzene under visible light irradiation, was prepared by the sol-gel route. Titanium isopropoxide, ammonium nitrate, and cerium nitrate were used as the sources of titanium, nitrogen, and cerium, respectively. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis diffusive reflectance spectroscopy (DRS), scanning electron microscopy (SEM), and N2 adsorption-desorption isotherm were employed to characterize the as-prepared photocatalyst. The degradation of nitrobenzene under visible light illumination was taken as probe reaction to evaluate the photoactivity of the co-doped photocatalyst. The commercial TiO2 photocatalyst (Degussa P25), which was thought as a high active photocatalyst, was chosen as standard photocatalyst to contrast the photoactivity of the nitrogen and cerium co-doped titania photocatalyst. The results showed that the photocatalytic performance of the nitrogen and cerium co-doped titania was related with the calcination temperature and the component. The nitrogen atoms were incorporated into the crystal of titania and could narrow the band gap energy. The doping cerium atoms existed in the forms of Ce2O3 and dispersed on the surface of TiO2. The improvement of the photocatalytic activity was ascribed to the synergistic effects of the nitrogen and cerium co-doping

  6. Cerium Oxide Nanoparticles and Bulk Cerium Oxide Leading to Different Physiological and Biochemical Responses in Brassica rapa.

    Science.gov (United States)

    Ma, Xingmao; Wang, Qiang; Rossi, Lorenzo; Zhang, Weilan

    2016-07-01

    Cerium oxide nanoparticles (CeO2NPs) have been incorporated into many commercial products, and their potential release into the environment through the use and disposal of these products has caused serious concerns. Despite the previous efforts and rapid progress on elucidating the environmental impact of CeO2NPs, the long-term impact of CeO2NPs to plants, a key component of the ecosystem, is still not well understood. The potentially different impact of CeO2NPs and their bulk counterparts to plants is also unclear. The main objectives of this study were (1) to investigate whether continued irrigation with solutions containing different concentrations of CeO2NPs (0, 10, and 100 mg/L) would induce physiological and biochemical adjustments in Brassica rapa in soil growing conditions and (2) to determine whether CeO2NPs and bulk CeO2 particles exert different impacts on plants. The results indicated that bulk CeO2 at 10 and 100 mg/L enhanced plant biomass by 28% and 35%, respectively, while CeO2NPs at equivalent concentrations did not. While the bulk CeO2 treatment resulted in significantly higher concentrations of hydrogen peroxide (H2O2) in plant tissues at the vegetative stage, CeO2NPs led to significantly higher H2O2 levels in plant tissues at the floral stage. The activity of superoxide dismutase (SOD) in Brassica rapa also displayed a growth-stage dependent response to different sizes of CeO2 while catalase (CAT) activity was not affected by either size of CeO2 throughout the life cycle of Brassica rapa. Altogether, the results demonstrated that plant responses to CeO2 exposure varied with the particle sizes and the growth stages of plants. PMID:26691446

  7. Improved performance of silicon nanowire/cadmium telluride quantum dots/organic hybrid solar cells

    International Nuclear Information System (INIS)

    Highlights: • We introduce an intermediate cadmium telluride quantum dots (CdTe QDs) layer between the organic with silicon nanowires of hybrid solar cells as a down-shifting layer. • The hybrid solar cell got the maximum short circuit current density of 33.5 mA/cm2, getting an increase of 15.1% comparing to solar cell without CdTe QDs. • The PCE of the hybrid solar cells with CdTe QDs layer increases 28.8%. - Abstract: We fabricated silicon nanowire/cadmium telluride quantum dots (CdTe QDs)/organic hybrid solar cells and investigated their structure and electrical properties. Transmission electron microscope revealed that CdTe QDs were uniformly distributed on the surface of the silicon nanowires, which made PEDOT:PSS easily filled the space between SiNWs. The current density–voltage (J–V) characteristics of hybrid solar cells were investigated both in dark and under illumination. The result shows that the performance of the hybrid solar cells with CdTe QDs layer has an obvious improvement. The optimal short-circuit current density (Jsc) of solar cells with CdTe QDs layer can reach 33.5 mA/cm2. Compared with the solar cells without CdTe QDs, Jsc has an increase of 15.1%. Power conversion efficiency of solar cells also increases by 28.8%. The enhanced performance of the hybrid solar cells with CdTe QDs layers are ascribed to down-shifting effect of CdTe QDs and the modification of the silicon nanowires surface with CdTe QDs. The result of our experiments suggests that hybrid solar cells with CdTe QDs modified are promising candidates for solar cell application

  8. Cathodic electrodeposition of cerium based oxides on carbon steel from concentrated cerium nitrate. Part II: Influence of electrodeposition parameters and of the addition of PEG

    Energy Technology Data Exchange (ETDEWEB)

    Hamlaoui, Y. [Laboratoire d' Etudes des Materiaux en Milieux Agressifs (LEMMA), Pole Sciences et Technologie, Universite de La Rochelle, Avenue Michel Crepeau, 17042 La Rochelle Cedex 1 (France); Institut des Sciences et Sciences de l' Ingenieur, Centre Universitaire de Souk-Ahras, BP 1553, 41000 Souk-Ahras (Algeria); Tifouti, L. [Laboratoire de Genie de l' Environnement, Universite Badji Mokhtar, BP 1223, 23020, El Hadjar-Annaba (Algeria); Remazeilles, C. [Laboratoire d' Etudes des Materiaux en Milieux Agressifs (LEMMA), Pole Sciences et Technologie, Universite de La Rochelle, Avenue Michel Crepeau, 17042 La Rochelle Cedex 1 (France); Pedraza, F., E-mail: fpedraza@univ-lr.fr [Laboratoire d' Etudes des Materiaux en Milieux Agressifs (LEMMA), Pole Sciences et Technologie, Universite de La Rochelle, Avenue Michel Crepeau, 17042 La Rochelle Cedex 1 (France)

    2010-03-15

    The mechanisms of formation of cerium based oxides on carbon steel by cathodic electrodeposition from relatively concentrated cerium nitrate solutions were investigated in a previous work (Part I). It was shown that some corrosion products developed on the steel upon and soon after coating, thereby suggesting the films were not protective. This work (Part II) focuses on the influence of various elaboration parameters on the composition and morphology of the deposits likely to improve the corrosion resistance of carbon steel. It will be shown that an increase of the precursor concentration increases the Ce(OH){sub 3} content of the deposits and brings about larger crystallite sizes at low to moderate applied current densities. As a result, the formation of the carbonated green rust corrosion product is not hindered. The kinetics of formation of the film follows a polynomial law in which concurrent deposition and dissolution steps are combined. However, an increase of the deposition time results in a reduced content of Ce(OH){sub 3} in the layers, hence in an evolution of the colour of the deposits. Similarly, the increase of the temperature of the bath brings about significant modifications of the surface morphology, of the crystallite size and of the content of oxygen vacancies that are suspected not to confer adequate protection. In contrast, the addition of 10 g L{sup -1} of PEG to the 0.1 M cerium nitrate solutions will be shown to inhibit the development of the carbonated green rust.

  9. Cathodic electrodeposition of cerium based oxides on carbon steel from concentrated cerium nitrate. Part II: Influence of electrodeposition parameters and of the addition of PEG

    International Nuclear Information System (INIS)

    The mechanisms of formation of cerium based oxides on carbon steel by cathodic electrodeposition from relatively concentrated cerium nitrate solutions were investigated in a previous work (Part I). It was shown that some corrosion products developed on the steel upon and soon after coating, thereby suggesting the films were not protective. This work (Part II) focuses on the influence of various elaboration parameters on the composition and morphology of the deposits likely to improve the corrosion resistance of carbon steel. It will be shown that an increase of the precursor concentration increases the Ce(OH)3 content of the deposits and brings about larger crystallite sizes at low to moderate applied current densities. As a result, the formation of the carbonated green rust corrosion product is not hindered. The kinetics of formation of the film follows a polynomial law in which concurrent deposition and dissolution steps are combined. However, an increase of the deposition time results in a reduced content of Ce(OH)3 in the layers, hence in an evolution of the colour of the deposits. Similarly, the increase of the temperature of the bath brings about significant modifications of the surface morphology, of the crystallite size and of the content of oxygen vacancies that are suspected not to confer adequate protection. In contrast, the addition of 10 g L-1 of PEG to the 0.1 M cerium nitrate solutions will be shown to inhibit the development of the carbonated green rust.

  10. The effects of cerium doping on the size, morphology, and optical properties of α-hematite nanoparticles for ultraviolet filtration

    International Nuclear Information System (INIS)

    Highlights: • Possible application of cerium-doped α-hematite as ultraviolet filter. • Nanoparticles obtained through co-precipitation technique using various cerium doping levels followed by annealing. • Comprehensive materials characterisation utilizing XRD, DSC/TGA, STEM, UV–vis spectroscopy. • Increasing cerium content reduces particle sizing and alters morphology. • Solubility of cerium in hematite seen between 5 and 10% doping, 10% cerium doping greatly enhances attenuation in ultraviolet region and increases optical bandgap. - Abstract: Metal oxide nanoparticles have potential use in energy storage, electrode materials, as catalysts and in the emerging field of nanomedicine. Being able to accurately tailor the desirable properties of these nanoceramic materials, such as particle size, morphology and optical bandgap (Eg) is integral in the feasibility of their use. In this study we investigate the altering of both the structure and physical properties through the doping of hematite (α-Fe2O3) nanocrystals with cerium at a range of concentrations, synthesised using a one-pot co-precipitation method. This extremely simple synthesis followed by thermal treatment results in stable Fe2−xCexOy nanoceramics resulting from the burning of any unreacted precursors and transformation of goethite-cerium doped nanoparticle intermediate. The inclusion of Ce into the crystal lattice of these α-Fe2O3 nanoparticles causes a significantly large reduction in mean crystalline size and alteration in particle morphology with increasing cerium content. Finally we report an increase optical semiconductor bandgap, along with a substantial increase in the ultraviolet attenuation found for a 10% Ce-doping concentration which shows the potential application of cerium-doped hematite nanocrystals to be used as a pigmented ultraviolet filter for cosmetic products

  11. Evolution of the local environment of cerium and neodymium during simplified SON68 glass alteration

    Energy Technology Data Exchange (ETDEWEB)

    Jollivet, Patrick [Commissariat a l' Energie Atomique (CEA), Rhone Valley Research Center, BP 17171, 30207 Bagnols-sur-Ceze (France)]. E-mail: patrick.jollivet@cea.fr; Lopez, Christophe [Commissariat a l' Energie Atomique (CEA), Rhone Valley Research Center, BP 17171, 30207 Bagnols-sur-Ceze (France); Auwer, Christophe Den [Commissariat a l' Energie Atomique (CEA), Rhone Valley Research Center, BP 17171, 30207 Bagnols-sur-Ceze (France); Simoni, Eric [Institut de Physique Nucleaire, Batiment 100, 91406 Orsay cedex (France)

    2005-11-15

    The evolution of the sites occupied by cerium and neodymium (coordination numbers and Ce, Nd-O distances) during alteration of simplified SON68 glass specimens was determined by L{sub III}-edge XAS. Cerium and neodymium are situated in a silicate environment in the glass, surrounded by eight oxygen atoms at an average distance of 2.44 and 2.48 A, respectively. These two rare earth elements exhibit different leaching behavior, however. The main environment of cerium becomes a silicate (d {sub Ce-O} = 2.19 A) with a second oxide or more probably oxyhydroxide site (d {sub Ce-O} = 2.32 A). The cerium coordination number increases by 1 to 3 compared with the glass, depending on the leaching conditions. Neodymium is found mainly in a hydroxycarbonate environment (d {sub Nd-O} = 2.46 A); the second site is a silicate (d {sub Nd-O} = 2.54 A). The neodymium coordination number increases by 1 compared with the glass. When glass containing neodymium is doped with phosphorus, Nd is situated in a phosphate environment; this change is also reflected in the coordination number and Nd-O distance (seven oxygen atoms at 2.42 A). During glass leaching, neodymium is present at two different sites, phosphate (d {sub Nd-O} = 2.52 A) and hydroxycarbonate (d {sub Nd-O} = 2.40 A)

  12. XPS and factor analysis study of initial stages of cerium oxide growth on polycrystalline tungsten

    Czech Academy of Sciences Publication Activity Database

    Polyak, Yaroslav; Bastl, Zdeněk

    2015-01-01

    Roč. 47, č. 6 (2015), s. 663-671. ISSN 0142-2421 Institutional support: RVO:68378271 ; RVO:61388955 Keywords : XPS * FA * PLD * cerium oxide * WO 3 * Ce (3d) Subject RIV: BM - Solid Matter Physics ; Magnetism; CF - Physical ; Theoretical Chemistry (UFCH-W) Impact factor: 1.245, year: 2014

  13. Demonstration of enhanced K-edge angiography using a cerium target x-ray generator

    International Nuclear Information System (INIS)

    The cerium target x-ray generator is useful in order to perform enhanced K-edge angiography using a cone beam because K-series characteristic x rays from the cerium target are absorbed effectively by iodine-based contrast mediums. The x-ray generator consists of a main controller, a unit with a Cockcroft-Walton circuit and a fixed anode x-ray tube, and a personal computer. The tube is a glass-enclosed diode with a cerium target and a 0.5-mm-thick beryllium window. The maximum tube voltage and current were 65 kV and 0.4 mA, respectively, and the focal-spot sizes were 1.0x1.3 mm. Cerium Kα lines were left using a barium sulfate filter, and the x-ray intensity was 0.48 μC/kg at 1.0 m from the source with a tube voltage of 60 kV, a current of 0.40 mA, and an exposure time of 1.0 s. Angiography was performed with a computed radiography system using iodine-based microspheres. In coronary angiography of nonliving animals, we observed fine blood vessels of approximately 100 μm with high contrasts

  14. Influences of the main anodic electroplating parameters on cerium oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yang; Yang, Yumeng; Du, Xiaoqing; Chen, Yu [Department of Chemistry, Zhejiang University, Hangzhou 310027, Zhejiang (China); Zhang, Zhao, E-mail: eaglezzy@zjuem.zju.edu.cn [Department of Chemistry, Zhejiang University, Hangzhou 310027, Zhejiang (China); Zhang, Jianqing [Department of Chemistry, Zhejiang University, Hangzhou 310027, Zhejiang (China); State Key Laboratory for Corrosion and Protection of Metals, Shenyang 110016 (China)

    2014-06-01

    Cerium oxide thin films were fabricated onto 316 L stainless steel via a potentiostatically anodic electrodeposition approach in the solutions containing cerium(III) nitrate (0.05 M), ammonia acetate (0.1 M) and ethanol (10% V/V). The electrochemical behaviors and deposition parameters (applied potential, bath temperature, dissolving O{sub 2} and bath pH) have been investigated. Results show that, the electrochemical oxidation of Ce{sup 3+} goes through one electrochemical step, which is under charge transfer control. The optimum applied potential for film deposition is 0.8 V. Bath temperature plays a significant effect on the deposition rate, composition (different colors of the film) and surface morphology of the deposits. Due to the hydrolysis of Ce{sup 3+}, cerous hydroxide is facility to form when the bath temperature is higher than 60 °C. The electroplating bath pH is another key role for the anodic deposition of cerium oxide thin films, and the best bath pH is around 6.20. N{sub 2} or O{sub 2} purged into the bath will result in film porosities and O{sub 2} favors cerium oxide particles and film generation.

  15. Influences of the main anodic electroplating parameters on cerium oxide films

    International Nuclear Information System (INIS)

    Cerium oxide thin films were fabricated onto 316 L stainless steel via a potentiostatically anodic electrodeposition approach in the solutions containing cerium(III) nitrate (0.05 M), ammonia acetate (0.1 M) and ethanol (10% V/V). The electrochemical behaviors and deposition parameters (applied potential, bath temperature, dissolving O2 and bath pH) have been investigated. Results show that, the electrochemical oxidation of Ce3+ goes through one electrochemical step, which is under charge transfer control. The optimum applied potential for film deposition is 0.8 V. Bath temperature plays a significant effect on the deposition rate, composition (different colors of the film) and surface morphology of the deposits. Due to the hydrolysis of Ce3+, cerous hydroxide is facility to form when the bath temperature is higher than 60 °C. The electroplating bath pH is another key role for the anodic deposition of cerium oxide thin films, and the best bath pH is around 6.20. N2 or O2 purged into the bath will result in film porosities and O2 favors cerium oxide particles and film generation.

  16. Influences of the main anodic electroplating parameters on cerium oxide films

    Science.gov (United States)

    Yang, Yang; Yang, Yumeng; Du, Xiaoqing; Chen, Yu; Zhang, Zhao; Zhang, Jianqing

    2014-06-01

    Cerium oxide thin films were fabricated onto 316 L stainless steel via a potentiostatically anodic electrodeposition approach in the solutions containing cerium(III) nitrate (0.05 M), ammonia acetate (0.1 M) and ethanol (10% V/V). The electrochemical behaviors and deposition parameters (applied potential, bath temperature, dissolving O2 and bath pH) have been investigated. Results show that, the electrochemical oxidation of Ce3+ goes through one electrochemical step, which is under charge transfer control. The optimum applied potential for film deposition is 0.8 V. Bath temperature plays a significant effect on the deposition rate, composition (different colors of the film) and surface morphology of the deposits. Due to the hydrolysis of Ce3+, cerous hydroxide is facility to form when the bath temperature is higher than 60 °C. The electroplating bath pH is another key role for the anodic deposition of cerium oxide thin films, and the best bath pH is around 6.20. N2 or O2 purged into the bath will result in film porosities and O2 favors cerium oxide particles and film generation.

  17. Photochemical precipitation of thorium and cerium and their separation from other ions in aqueous solution.

    Science.gov (United States)

    Das, M; Heyn, A H; Hoffman, M Z; Agarwal, R P

    1970-10-01

    Thorium was precipitated from homogeneous solution by exposing solutions of thorium and periodate in dilute perchloric acid to 253.7 nm radiation from a low-pressure mercury lamp. Periodate is reduced photochemically to iodate which causes the formation of a dense precipitate of the basic iodate of thorium(IV). The precipitate was redissolved, the iodate reduced, the thorium precipitated first as the hydroxide, then as the oxalate and ignited to the dioxide for weighing. Thorium(IV) solutions containing 8-200 mg of ThO(2) gave quantitative results with a standard deviation (s) of 0.2 mg. Separations from 25 mg each of iron, calcium, magnesium, 50 mg of yttrium and up to 500 mg of uranium(VI) were quantitative (s = 0.25 mg). Separations from rare earths, except cerium, were accomplished by using hexamethylenetetramine rather than ammonia for the precipitation of the hydroxide. Cerium(III) was similarly precipitated and converted into CeO(2) for weighing. Quantitative results were obtained for 13-150 mg of CeO(2) with a standard deviation of 0.2 mg. Separations from 200 mg of uranium were quantitative. Other rare earths and yttrium interfered seriously. The precipitates of the basic cerium(IV) and thorium iodates obtained are more compact than those obtained by direct precipitation and can be handled easily. Attempts to duplicate Suzuki's method for separating cerium from neodymium and yttrium were not successful. PMID:18960820

  18. Excimer Laser Deposition and Characterization of Cerium Doped TiO2

    Czech Academy of Sciences Publication Activity Database

    Fajgar, Radek; Dřínek, Vladislav; Kupčík, Jaroslav; Šubrt, Jan; Murafa, Nataliya

    - : -, 2011, s. 131. ISSN N. [EuroCVD 18. Kinsale, Co. Cork (IE), 04.09.2011-09.09.2011] Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40320502 Keywords : laser deposition * TiO2 * cerium Subject RIV: CH - Nuclear ; Quantum Chemistry

  19. Transient Dynamics of Fluoride-Based High Concentration Erbium/Cerium Co-Doped Fiber Amplifier

    Institute of Scientific and Technical Information of China (English)

    S. S-H. Yam; Y. Akasaka; Y. Kubota; R. Huang; D. L. Harris; J. Pan

    2003-01-01

    We designed and evaluated a fluoride-based high concentration erbium/ cerium co-doped fiber amplifier. It is suitable for Metropolitan Area Networks due to faster transient, flatter (unfiltered) gain, smaller footprint and gain excursion than its silica-based counterpart.

  20. Separation of cerium from high level waste solution of Purex origin

    International Nuclear Information System (INIS)

    A simple solvent extraction procedure for the separation of 144Ce from Purex high level waste (HLW) is described. 2-ethylhexyl 2-ethylhexyl phosphonic acid (KSM-17) has been used as extractant. About 10 mCi of cerium was separated from HLW using this technique. This method is amenable for automation and scale up. (author)

  1. Cerium oxide coated anodes for aluminum electrowinning: Topical report, October 1, 1986-June 30, 1987

    Energy Technology Data Exchange (ETDEWEB)

    Walker, J. K.

    1987-12-01

    Because of the cost of building and maintaining a carbon anode plant and the energy penalties associated with the use of carbon anodes in the production of aluminum, the use of inert anodes has long been proposed. Various cermet anodes have been investigated. In this paper, tests on a material, cerium oxyfluoride (CEROX), deposited in situ as an anode, are reported. (JDH)

  2. Growth and characterization of Sm3+ doped cerium oxalate single crystals

    Directory of Open Access Journals (Sweden)

    Minu Mary C

    2016-07-01

    Full Text Available Single crystals of Sm3+ doped cerium oxalate decahydrate were synthesized using single diffusion gel technique and the conditions influencing the size, morphology, nucleation density and quality of the crystals were optimized. Highly transparent single crystals of average size 3 mm × 2 mm × 1 mm with well-defined hexagonal morphology were grown during a time period of two weeks. X-ray powder diffraction analysis revealed that the grown crystals crystallize in the monoclinic system with space group P21/c as identical with the pure cerium oxalate. The various functional groups of the oxalate ligand and the water of crystallization were identified by Fourier transform infrared spectroscopy. The photoluminescence spectrum of the Sm3+ doped cerium oxalate indicated that the Sm3+ ions are optically active in the cerium oxalate matrix. The crystal has a strong and efficient orange red emission with a wavelength peak at 595 nm and hence can be effectively used for optical amplification. Microhardness measurements of the crystal revealed that they belong to the soft material category.

  3. EXAFS and XANES analysis of plutonium and cerium edges from titanate ceramics for fissile materials disposal

    International Nuclear Information System (INIS)

    We report x-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) spectra from the plutonium LIII edge and XANES from the cerium LII edge in prototype titanate ceramic hosts. The titanate ceramics studied are based upon the hafnium-pyrochlore and zirconolite mineral structures and will serve as an immobilization host for surplus fissile materials, containing as much as 10 weight % fissile plutonium and 20 weight % (natural or depleted) uranium. Three ceramic formulations were studied: one employed cerium as a ''surrogate'' element, replacing both plutonium and uranium in the ceramic matrix, another formulation contained plutonium in a ''baseline'' ceramic formulation, and a third contained plutonium in a formulation representing a high-impurity plutonium stream. The cerium XANES from the surrogate ceramic clearly indicates a mixed III-IV oxidation state for the cerium. In contrast, XANES analysis of the two plutonium-bearing ceramics shows that the plutonium is present almost entirely as Pu(IV) and occupies the calcium site in the zirconolite and pyrochlore phases. The plutonium EXAFS real-space structure shows a strong second-shell peak, clearly distinct from that of PuO2, with remarkably little difference in the plutonium crystal chemistry indicated between the baseline and high-impurity formulations

  4. Cerium oxide nanoparticles inhibit lipopolysaccharide induced MAP kinase/NF-kB mediated severe sepsis

    Directory of Open Access Journals (Sweden)

    Vellaisamy Selvaraj

    2015-09-01

    Full Text Available The life threatening disease of sepsis is associated with high mortality. Septic patient survivability with currently available treatments has failed to improve. The purpose of this study was to evaluate whether lipopolysaccharide (LPS induced sepsis mortality and associated hepatic dysfunction can be prevented by cerium oxide nanoparticles (CeO2NPs treatment in male Sprague Dawley rats. Here we provide the information about the methods processing of raw data related to our study published in Biomaterials (Selvaraj et al., Biomaterials, 2015, In press and Data in Brief (Selvaraj et al., Data in Brief, 2015, In Press. The data present here provides confirmation of cerium oxide nanoparticle treatments ability to prevent the LPS induced sepsis associated changes in physiological, blood cell count, inflammatory protein and growth factors in vivo. In vitro assays investigation the treated of macrophages cells with different concentrations of cerium oxide nanoparticle demonstrate that concentration of cerium oxide nanoparticles below 1 µg/ml did not significantly influence cell survival as determined by the MTT assay.

  5. Cerium oxide nanoparticles inhibit lipopolysaccharide induced MAP kinase/NF-kB mediated severe sepsis.

    Science.gov (United States)

    Selvaraj, Vellaisamy; Nepal, Niraj; Rogers, Steven; Manne, Nandini D P K; Arvapalli, Ravikumar; Rice, Kevin M; Asano, Shinichi; Fankenhanel, Erin; Ma, J Y; Shokuhfar, Tolou; Maheshwari, Mani; Blough, Eric R

    2015-09-01

    The life threatening disease of sepsis is associated with high mortality. Septic patient survivability with currently available treatments has failed to improve. The purpose of this study was to evaluate whether lipopolysaccharide (LPS) induced sepsis mortality and associated hepatic dysfunction can be prevented by cerium oxide nanoparticles (CeO2NPs) treatment in male Sprague Dawley rats. Here we provide the information about the methods processing of raw data related to our study published in Biomaterials (Selvaraj et al., Biomaterials, 2015, In press) and Data in Brief (Selvaraj et al., Data in Brief, 2015, In Press). The data present here provides confirmation of cerium oxide nanoparticle treatments ability to prevent the LPS induced sepsis associated changes in physiological, blood cell count, inflammatory protein and growth factors in vivo. In vitro assays investigation the treated of macrophages cells with different concentrations of cerium oxide nanoparticle demonstrate that concentration of cerium oxide nanoparticles below 1 µg/ml did not significantly influence cell survival as determined by the MTT assay. PMID:26217772

  6. Phenotypic and genomic responses to titanium dioxide and cerium oxide nanoparticles in Arabidopsis germinants

    Science.gov (United States)

    The effects of exposure to two nanoparticles (NPs) -titanium dioxide (nano-titania) and cerium oxide (nano-ceria) at 500 mg NPs L-1 on gene expression and growth in Arabidopsis thaliana germinants were studied using microarrays and phenotype studies. After 12 days post treatment,...

  7. Magnetic hysteresis of cerium doped bismuth ferrite thin films

    International Nuclear Information System (INIS)

    The influence of Cerium doping on the structural and magnetic properties of BiFeO3 thin films have been investigated. Rietveld refinement of X-ray diffraction data and successive de-convolution of Raman scattering spectra of Bi1−xCexFeO3 (BCFO) thin films with x=0–0.20 reflect the single phase rhombohedral (R3c) formation for x<0.08, whereas concentration-driven gradual structural phase transition from rhombohedral (R3c) to partial tetragonal (P4mm) phase follows for x≥0.08. All low wavenumber Raman modes (<300 cm−1) showed a noticeable shift towards higher wavenumber with increase in doping concentration, except Raman E-1 mode (71 cm−1), shows a minor shift. Sudden evolution of Raman mode at 668 cm−1, manifested as A1-tetragonal mode, accompanied by the shift to higher wavenumber with increase in doping concentration (x) affirm partial structural phase transition. Anomalous wasp waist shaped (M–H) hysteresis curves with improved saturation magnetization (Ms) for BCFO thin films is attributed to antiferromagnetic interaction/hybridization between Ce 4f and Fe 3d electronic states. The contribution of both hard and soft phase to the total coercivity is calculated. Polycrystalline Bi0.88Ce0.12FeO3 thin film found to exhibit better magnetic properties with Ms=15.9 emu/g without any impure phase. - Highlights: • Synthesis of single phase Bi1−xCexFeO3 thin films with (x=0–0.2) on cost effective corning glass and silicon substrates using CSD technique. • Structural modification studies using Rietveld refinement of XRD and de-convolution of Raman spectra revealed partial phase transition from rhombohedral (R3c) to tetragonal (P4mm) phase. • Possible reasons for origin of pinched magnetic behavior of BCFO thin films are identified. • Contribution of both hard and soft magnetic phase in coercivity of BCFO thin films is calculated and practical applications of such materials exhibiting pinching behavior are conferred

  8. Magnetic hysteresis of cerium doped bismuth ferrite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Surbhi [Department of Physics and Astrophysics, University of Delhi (India); Tomar, Monika [Physics Department, Miranda House, University of Delhi (India); Gupta, Vinay, E-mail: drguptavinay@gmail.com [Department of Physics and Astrophysics, University of Delhi (India)

    2015-03-15

    The influence of Cerium doping on the structural and magnetic properties of BiFeO{sub 3} thin films have been investigated. Rietveld refinement of X-ray diffraction data and successive de-convolution of Raman scattering spectra of Bi{sub 1−x}Ce{sub x}FeO{sub 3} (BCFO) thin films with x=0–0.20 reflect the single phase rhombohedral (R3c) formation for x<0.08, whereas concentration-driven gradual structural phase transition from rhombohedral (R3c) to partial tetragonal (P4mm) phase follows for x≥0.08. All low wavenumber Raman modes (<300 cm{sup −1}) showed a noticeable shift towards higher wavenumber with increase in doping concentration, except Raman E-1 mode (71 cm{sup −1}), shows a minor shift. Sudden evolution of Raman mode at 668 cm{sup −1}, manifested as A{sub 1}-tetragonal mode, accompanied by the shift to higher wavenumber with increase in doping concentration (x) affirm partial structural phase transition. Anomalous wasp waist shaped (M–H) hysteresis curves with improved saturation magnetization (M{sub s}) for BCFO thin films is attributed to antiferromagnetic interaction/hybridization between Ce 4f and Fe 3d electronic states. The contribution of both hard and soft phase to the total coercivity is calculated. Polycrystalline Bi{sub 0.88}Ce{sub 0.12}FeO{sub 3} thin film found to exhibit better magnetic properties with M{sub s}=15.9 emu/g without any impure phase. - Highlights: • Synthesis of single phase Bi{sub 1−x}Ce{sub x}FeO{sub 3} thin films with (x=0–0.2) on cost effective corning glass and silicon substrates using CSD technique. • Structural modification studies using Rietveld refinement of XRD and de-convolution of Raman spectra revealed partial phase transition from rhombohedral (R3c) to tetragonal (P4mm) phase. • Possible reasons for origin of pinched magnetic behavior of BCFO thin films are identified. • Contribution of both hard and soft magnetic phase in coercivity of BCFO thin films is calculated and practical

  9. Band structure, cohesive properties, and Compton profile of γ- and α-cerium

    Science.gov (United States)

    Podloucky, R.; Glötzel, D.

    1983-03-01

    Recent Compton scattering experiments on the high-volume (γ) and low-volume (α) phases of fcc cerium and their interpretation in terms of the renormalized-free-atom model cast severe doubts on the promotional model of Pauling and Zachariasen for the γ-α transition. Stimulated by these results, we have extended a previous self-consistent local-density band-structure investigation to study the Compton profiles of γ- and α-cerium. For the band structure, Bloch functions, and their Fourier transforms we use the linear muffin-tin orbital method in the atomic-sphere approximation. We analyze the calculated Compton profiles in terms of band structure and local angular momentum character of the wave functions. The change in band structure and wave functions under compression (with approximately one electron per atom in the 4f band of both phases) accounts well for the observed change in the Compton profile. This provides further evidence against the promotional model in agreement with the analysis of Kornstädt et al. In addition, we study the cohesive energy of fcc cerium as a function of volume in the local-density approximation. For α-cerium in the 4f1(5d 6s)3 configuration we find a cohesive energy of 5.4 eV/atom in good agreement with experiment, whereas the "promotional" 4f0(5d 6s)4 state yields a binding energy of 0.6 eV/atom only. Therefore the fourth valence electron has to be a 4f electron, and α-cerium has to be regarded as an f-band metal.

  10. High temperature condensation and thermal radiation properties of cerium dioxide in solid and liquid states

    International Nuclear Information System (INIS)

    Full Text: Measuring thermal radiation properties of cerium dioxide at high temperatures is very complicated problem from experimental point of view. It is connected with high evaporation of this material at high temperatures. In order to solve this problem with a subsecond laser technique the excess pressure of inert atmosphere is maintained in the working chamber to suppress surface evaporation in the focal area of the sample. In this paper it is shown that in this case the dense vapor phase formed above the investigated sample actively interacts with the sample surface and the laser radiation and distorts the experimental results. The developed polychromatic reflectometer with laser heating enabled one to discover the interesting phenomenon of the interaction of the vapor, liquid and solid phases in cerium dioxide under CO2 laser irradiation. This phenomenon is exhibited in the form of the exothermic peak of the condensation on the cooling curves moreover the temperature level of this transition is regulated by experimental parameters. The possibility of the change of the position of this floating phase transition on the temperature scale permits one to model the interaction of liquid-vapor and solid-vapor to estimate the contribution of the dense vapor phase formed above the sample to the thermal radiation properties of cerium dioxide at high temperatures. The experimental data on thermal radiation properties of stoichiometric cerium dioxide in the spectral range 0.4-1.1 μm and in the temperature region 2000-3500 K measured by the method developed are presented. Reflectivity and emissivity measurement error does not exceed ±3 %. The experimental results obtained are compared with the data of other authors and the recommended values for spectral reflectivity and emissivity of cerium dioxide at high temperatures are given. (author)

  11. The importance of cerium substituted phosphates as cation exchanger some unique properties and related application potentials

    International Nuclear Information System (INIS)

    Seven different samples of an inorganic ion exchanger, cerium phosphate, suitable for column use have been prepared under varying conditions. The property of these exchangers has been characterized by Inductively Coupled Plasma Spectroscopy. These exchangers are stable in water, dilute mineral acids, ethanol, methanol, acetone and ether. However, in concentrated HCl and HNO3 they decompose. They retain about 50% of their exchange value after drying at 80 degC, and can be regenerated twice without any decrease in exchange capacity. The distribution coefficient measurements for alkaline earth metals, tellurium, iodine and molybdenum using these seven ion exchangers were studied. This revealed the relative affinity for each exchanger, where the sorption in general was most effective at P H 6-8. The titration curves of cerium phosphate (disodium) with alkaline earth metals showed that the selectivity sequence Ba2+>Sr2+>CA2+>Mg2+ is observed. Furthermore, it could be deduced that the adsorption of alkaline earth metal cations greatly depends on the cation. These studies have also shown that cerium phosphates with divalent ions are strongly preferred to monovalent ones. Therefore, as for the cerium phosphates with large monovalent ions, the lack of exchange for Ba2+, Mg2+ or other alkaline earth metal ions should be essentially due to steric hindrance and this could include any one of the following: the large crystalline radius of metal ions or large hydrated ionic radius and high energy of hydration for other divalent ions. Three binary separations of TeIV - MoIV, TeIV -I1 has been developed and the recovery ranging from 90 to 100% has been achieved on cerium phosphate (disodium) columns

  12. Using cerium anomaly as an indicator of redox reactions in constructed wetland

    Science.gov (United States)

    Liang, R.

    2013-12-01

    The study area, Chiayi County located in southern Taiwan, has highly developed livestock. The surface water has very low dissolved oxygen and high NH4. Under the situation, constructed wetland becomes the most effective and economic choice to treat the wastewater in the natural waterways. Hebao Island free surface constructed wetland started to operate in late 2006. It covers an area of 0.28 km2 and is subdivided into 3 major cells, which are sedimentation cell, 1st aeration cell with rooted plants and 2nd aeration cell with float plants. The water depth of cells ranges from 0.6 m to 1.2 m. The total hydraulic retention time is about a half day. In this study, the water samples were sequentially collected along the flow path. The results of hydrochemical analysis show that the untreated inflow water can be characterized with enriched NH4 (11 ppm), sulfate (6 ppm) and arsenic (50 ppb). The removal efficiency of NH4 in the first two cells is pollutants from the wastewater; therefore, dissolved oxygen is traditionally considered as an important indicator to evaluate the operation efficiency of wetland. However, it would need longer time to achieve equilibrium state of redox reaction involving dissolved oxygen due to the slower reaction rate. For example, the input water in this study has fairly high dissolved oxygen (5 ppm) but the NH4 content is still high, which indicates a non-equilibrium condition. In this study, the cerium anomaly is alternatively utilized to evaluate the water redox state. The results demonstrate that the input water has the negative cerium anomaly of -0.16. Along the flow path, the cerium negative anomaly does not change in the first two cells and dramatically becomes -0.23 in cell 3. The trend of cerium anomaly is more close to the removal efficiency of NH4 rather than dissolve oxygen. Accordingly, cerium anomaly could become a better indicator of removal efficiency of constructed wetland.

  13. Effects of chemical intermixing on electrical and thermal contact conductances at metallized bismuth and antimony telluride interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Devender,; Mehta, Rutvik J.; Ramanath, Ganpati, E-mail: Ramanath@rpi.edu [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Lofgreen, Kelly; Mahajan, Ravi [Intel Corporation, Assembly Test and Technology Development, Chandler, Arizona 85226 (United States); Yamaguchi, Masashi [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Borca-Tasciuc, Theodorian [Department of Mechanical Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2015-03-15

    Tailoring electrical and thermal contact conductivities (Σ{sub c} and Γ{sub c}) across metallized pnictogen chalcogenide interfaces is key for realizing efficient thermoelectric devices. The authors report that Cu, Ni, Ti, and Ta diffusion and interfacial telluride formation with n-Bi{sub 2}Te{sub 3} and p-Sb{sub 2}Te{sub 3} influence both Σ{sub c} and Γ{sub c}. Cu metallization yields the highest Γ{sub c} and the lowest Σ{sub c}, correlating with maximal metal diffusion and copper telluride formation. Ni diffuses less and yields the highest Σ{sub c} with Sb{sub 2}Te{sub 3} due to p-type nickel telluride formation, which diminishes Σ{sub c} improvement with n-Bi{sub 2}Te{sub 3} interfaces. Ta and Ti contacts yield the lowest properties similar to that in Ni-metallized structures. These correlations between interfacial diffusion and phase formation on electronic and thermal transport properties will be important for devising suitable metallization for thermoelectric devices.

  14. Enhanced thermoelectric properties of phase-separating bismuth selenium telluride thin films via a two-step method

    International Nuclear Information System (INIS)

    A two-step method that combines homogeneous electron beam (EB) irradiation and thermal annealing has been developed to enhance the thermoelectric properties of nanocrystalline bismuth selenium telluride thin films. The thin films, prepared using a flash evaporation method, were treated with EB irradiation in a N2 atmosphere at room temperature and an acceleration voltage of 0.17 MeV. Thermal annealing was performed under Ar/H2 (5%) at 300 °C for 60 min. X-ray diffraction was used to determine that compositional phase separation between bismuth telluride and bismuth selenium telluride developed in the thin films exposed to higher EB doses and thermal annealing. We propose that the phase separation was induced by fluctuations in the distribution of selenium atoms after EB irradiation, followed by the migration of selenium atoms to more stable sites during thermal annealing. As a result, thin film crystallinity improved and mobility was significantly enhanced. This indicates that the phase separation resulting from the two-step method enhanced, rather than disturbed, the electron transport. Both the electrical conductivity and the Seebeck coefficient were improved following the two-step method. Consequently, the power factor of thin films that underwent the two-step method was enhanced to 20 times (from 0.96 to 21.0 μW/(cm K2) that of the thin films treated with EB irradiation alone

  15. Enhanced thermoelectric properties of phase-separating bismuth selenium telluride thin films via a two-step method

    Energy Technology Data Exchange (ETDEWEB)

    Takashiri, Masayuki, E-mail: takashiri@tokai-u.jp; Kurita, Kensuke [Department of Materials Science, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Hagino, Harutoshi; Miyazaki, Koji [Department of Mechanical and Control Engineering, Kyushu Institute of Technology, 1-1 Sensui, Tobata-ku, Kitakyushu 804-8550 (Japan); Tanaka, Saburo [Department of Mechanical Engineering, College of Engineering, Nihon University, 1 Nakagawara, Tokusada, Tamuramachi, Koriyama, Fukushima 963-8642 (Japan)

    2015-08-14

    A two-step method that combines homogeneous electron beam (EB) irradiation and thermal annealing has been developed to enhance the thermoelectric properties of nanocrystalline bismuth selenium telluride thin films. The thin films, prepared using a flash evaporation method, were treated with EB irradiation in a N{sub 2} atmosphere at room temperature and an acceleration voltage of 0.17 MeV. Thermal annealing was performed under Ar/H{sub 2} (5%) at 300 °C for 60 min. X-ray diffraction was used to determine that compositional phase separation between bismuth telluride and bismuth selenium telluride developed in the thin films exposed to higher EB doses and thermal annealing. We propose that the phase separation was induced by fluctuations in the distribution of selenium atoms after EB irradiation, followed by the migration of selenium atoms to more stable sites during thermal annealing. As a result, thin film crystallinity improved and mobility was significantly enhanced. This indicates that the phase separation resulting from the two-step method enhanced, rather than disturbed, the electron transport. Both the electrical conductivity and the Seebeck coefficient were improved following the two-step method. Consequently, the power factor of thin films that underwent the two-step method was enhanced to 20 times (from 0.96 to 21.0 μW/(cm K{sup 2}) that of the thin films treated with EB irradiation alone.

  16. Equation of state measurements by radiography provide evidence for a liquid-liquid phase transition in cerium

    Science.gov (United States)

    Lipp, M. J.; Jenei, Zs; Ruddle, D.; Aracne-Ruddle, C.; Cynn, H.; Evans, W. J.; Kono, Y.; Kenney-Benson, C.; Park, C.

    2014-05-01

    A pressure-volume isotherm in cerium metal at 1100 K was measured in a large volume press of the Paris-Edinburgh type up to 6 GPa. The volume was determined by imaging a rectangular shape of the sample via white X-ray radiography. Energy dispersive x-ray diffraction spectra were recorded to ensure that the highly reactive cerium in the cell assembly remained pure at this temperature. Even at 1100 K the p-V equation of state of liquid cerium shows a pronounced decrease of the bulk modulus above the y-phase region similar to the 775 K isotherm in the solid that also shows an inflection point between y- and a-type cerium. The inflection point in the 1100 K isotherm indicating the minimum in the bulk modulus separating the γ- from the α-type liquid is located at approximately 3.5 GPa.

  17. Effect of HCl pre-treatment on corrosion resistance of cerium-based conversion coatings on magnesium and magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Brunelli, Katya [Department of Mechanical Innovation and Management, University of Padua, Via Marzolo 9, 35131 Padua (Italy); Dabala, Manuele [Department of Mechanical Innovation and Management, University of Padua, Via Marzolo 9, 35131 Padua (Italy)]. E-mail: manuele.dabala@unipd.it; Calliari, Irene [Department of Mechanical Innovation and Management, University of Padua, Via Marzolo 9, 35131 Padua (Italy); Magrini, Maurizio [Department of Mechanical Innovation and Management, University of Padua, Via Marzolo 9, 35131 Padua (Italy)

    2005-04-01

    The corrosion protection afforded by a cerium conversion coating, formed by immersion in a solution containing rare earth salt and hydrogen peroxide, on pure magnesium and two magnesium alloys, AZ91 and AM50, has been studied. The effect of HCl pre-treatments on the morphology and on the corrosion resistance of the cerium conversion layer was investigated. A thicker and more homogeneous distribution of the conversion coating was obtained when the sample surface was pre-treated with acid. Higher amounts of cerium on the surface of the pre-treated samples were detected. The cerium conversion coating increased the corrosion resistance of the alloys because it ennobled the corrosion potential and decreased both the anodic and cathodic current. The acid pre-treatment further increased the corrosion resistance of the coated alloys. After five days of immersion in chloride environment the untreated samples showed localized corrosion while the chemical conversion coated samples appeared unaffected.

  18. Titrimetric and Spectrophotometric Assay of Ganciclovir in Pharmaceuticals Using Cerium(IV) Sulphate as the Oxidimetric Agent

    OpenAIRE

    Pavagada J. Ramesh; Kanakapura Basavaiah; Cijo M. Xavier; Prashanth, Kudige N.; Raghu, Madihalli S.; Kanakapura B. Vinay

    2012-01-01

    Titrimetric and spectrophotometric assay of ganciclovir (GNC) is described using cerium(IV) sulphate as the oxidimetric reagent. The methods are based on the oxidation of GNC with a measured excess of cerium(IV) sulphate in acid medium followed by determination of the unreacted oxidant by two different reaction schemes. In titrimetry, the unreacted oxidant was determined by back titration with ferrous ammonium sulphate (FAS) in sulphuric acid medium, and spectrophotometry involves the reactio...

  19. Reactions between cerium(IV) and methyl-6-x-derivatives of aniline in perchloric acid solutions

    International Nuclear Information System (INIS)

    The oxidation of 2,6-dimethyl-, 2-isopropyl-6-methyl, 2-chloro-6-methyl-and 2-methyl-6-nitro aniline with cerium(IV) in perchloric acid solutions has been examined. It has been found that the concentration of hydrogen ions and the basicity of nitrogen atom in the amine group decide about the resultant intermediate products. Some of these products can be practically prepared using cerium(IV) as an oxidizing agent. (author). 16 refs, 1 tab

  20. The dissolution and formation enthalpy of alloys and intermetallics of aluminium-lanthanum and aluminium-cerium systems

    International Nuclear Information System (INIS)

    Present article is devoted to dissolution and formation enthalpy of alloys and intermetallics of aluminium-lanthanum and aluminium-cerium systems. Therefore the dissolution temperatures of alloys and intermetallics of aluminium-lanthanum and aluminium-cerium systems were defined by means of calorimetry method. The enthalpy of formation of intermetallics of Al-Ce system was defined as well. The regularities in changes of dissolution and formation enthalpy of alloys and intermetallics depending on composition were studied.

  1. Analysis of single and binary phases in cerium doped sodium bismuth titanate -inorganic materials Na0.5Bi(0.5-x)CexTiO3

    International Nuclear Information System (INIS)

    The pure and cerium doped sodium bismuth titanate (NBT) inorganic powders were synthesized by solid-state reaction method. The presence of rhombohedral phase was observed in cerium doped NBT compounds. When x= 0.05 of cerium doped NBT is heat treated at 1200 degree centigrade, the compound forms single perovskite phase. The samples of x = 0.10 and 0.15 were heat treated up to 1350 degree centigrade, the binary phases with cerium and bismuth oxides were observed. The X-ray diffraction, Fourier transform infrared spectroscopy, reflectance spectra, differential thermal analysis and thermogravimetric analysis were used to analyze the various properties of samples. Moreover, the effects of cerium doping and calcining temperature on NBT samples were investigated. In this work, we present our recent results on the synthesis and characterization of cerium doped sodium bismuth titanate materials. (Author)

  2. Chromatographic separation of cerium(Ⅲ) in L-valine medium using poly[dibenzo-18-crown-6

    Institute of Scientific and Technical Information of China (English)

    SABALE Sandip R; MOHITE Baburao S

    2009-01-01

    A column chromatographic method has been developed for the separation and determination of cerium(Ⅲ) using poly[dibenzo-18-crown-6]. The separation was carried out in L-valine medium. The adsorption of cerium(Ⅲ) was quantitative from 1×10-1 to 1×10-4 mol/L L-valine. Amongst the various eluents, 1.0-8.0 mol/L hydrochloric acid, 1.0-8.0 mol/L hydrobromic acid, 1.0-8.0 mol/L perchloric acid, 1.0-2.0 mol/L sulfuric acid and 4.0-5.0 mol/L acetic acid, were found to be the efficient eluents for cerium(Ⅲ). The capacity of poly[dibenzo-18-crown-6] for cerium(Ⅲ) was (0.428±0.01) mmol/g. The method was applied to the separation of cerium(Ⅲ) from associated elements link uranium(Ⅵ) and thorium(Ⅳ). It was also applied for the determination of cerium(Ⅲ) in geological samples. The method is simple, rapid and selective with good reproducibility (approximately±2% ).

  3. Enhanced thermoelectric properties of bismuth telluride-organic hybrid films via graphene doping

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Airul Azha Abd [Universiti Kebangsaan Malaysia UKM, Institute of Microengineering and Nanoelectronics, Bangi, Selangor (Malaysia); Technology Park Malaysia, Malaysia Institute of Microelectronics and System, Kuala Lumpur (Malaysia); Umar, Akrajas Ali; Salleh, Muhamad Mat [Universiti Kebangsaan Malaysia UKM, Institute of Microengineering and Nanoelectronics, Bangi, Selangor (Malaysia); Chen, Xiaomei [Jimei University, College of Food and Biological Engineering, Jimei, Xiamen (China); Oyama, Munetaka [Kyoto University, Graduate School of Engineering, Nishikyoku, Kyoto (Japan)

    2016-02-15

    The thermoelectric properties of graphene-doped bismuth telluride-PEDOT:PSS-glycerol (hybrid) films were investigated. Prior to the study, p-type and n-type hybrid films were prepared by doping the PEDOT:PSS-glycerol with the p- and n-type bismuth telluride. Graphene-doped hybrid films were prepared by adding graphene particles of concentration ranging from 0.02 to 0.1 wt% into the hybrid films. Films of graphene-doped hybrid system were then prepared on a glass substrate using a spin-coating technique. It was found that the electrical conductivity of the hybrid films increases with the increasing of the graphene-dopant concentration and optimum at 0.08 wt% for both p- and n-type films, namely 400 and 195 S/cm, respectively. Further increasing in the concentration caused a decreasing in the electrical conductivity. Analysis of the thermoelectric properties of the films obtained that the p-type film exhibited significant improvement in its thermoelectric properties, where the thermoelectric properties increased with the increasing of the doping concentration. Meanwhile, for the case of n-type film, graphene doping showed a negative effect to the thermoelectrical properties, where the thermoelectric properties decreased with the increasing of doping concentration. Seebeck coefficient (and power factor) for optimum p-type and n-type hybrid thin films, i.e., doped with 0.08 wt% of graphene, is 20 μV/K (and 160 μW m{sup -1} K{sup -2}) and 10 μV/K (and 19.5 μW m{sup -1} K{sup -2}), respectively. The obtained electrical conductivity and thermoelectric properties of graphene-doped hybrid film are interestingly several orders higher than the pristine hybrid films. A thermocouple device fabricated utilizing the p- and n-type graphene-doped hybrid films can generate an electric voltage as high as 2.2 mV under a temperature difference between the hot-side and the cold-side terminal as only low as 55 K. This is equivalent to the output power as high as 24.2 nW (for output

  4. Enhanced thermoelectric properties of bismuth telluride-organic hybrid films via graphene doping

    International Nuclear Information System (INIS)

    The thermoelectric properties of graphene-doped bismuth telluride-PEDOT:PSS-glycerol (hybrid) films were investigated. Prior to the study, p-type and n-type hybrid films were prepared by doping the PEDOT:PSS-glycerol with the p- and n-type bismuth telluride. Graphene-doped hybrid films were prepared by adding graphene particles of concentration ranging from 0.02 to 0.1 wt% into the hybrid films. Films of graphene-doped hybrid system were then prepared on a glass substrate using a spin-coating technique. It was found that the electrical conductivity of the hybrid films increases with the increasing of the graphene-dopant concentration and optimum at 0.08 wt% for both p- and n-type films, namely 400 and 195 S/cm, respectively. Further increasing in the concentration caused a decreasing in the electrical conductivity. Analysis of the thermoelectric properties of the films obtained that the p-type film exhibited significant improvement in its thermoelectric properties, where the thermoelectric properties increased with the increasing of the doping concentration. Meanwhile, for the case of n-type film, graphene doping showed a negative effect to the thermoelectrical properties, where the thermoelectric properties decreased with the increasing of doping concentration. Seebeck coefficient (and power factor) for optimum p-type and n-type hybrid thin films, i.e., doped with 0.08 wt% of graphene, is 20 μV/K (and 160 μW m-1 K-2) and 10 μV/K (and 19.5 μW m-1 K-2), respectively. The obtained electrical conductivity and thermoelectric properties of graphene-doped hybrid film are interestingly several orders higher than the pristine hybrid films. A thermocouple device fabricated utilizing the p- and n-type graphene-doped hybrid films can generate an electric voltage as high as 2.2 mV under a temperature difference between the hot-side and the cold-side terminal as only low as 55 K. This is equivalent to the output power as high as 24.2 nW (for output load as high as 50

  5. Thermodynamic studies in the system cerium-gadolinium-oxygen. Thermodynamische Untersuchungen am System Cer-Gadolinium-Sauerstoff; Kalorimetrische und elektrochemische Methoden

    Energy Technology Data Exchange (ETDEWEB)

    Stelzer, N.

    1993-01-01

    Two independent measuring methods have been applied to studying the phase relations of the system cerium-gadolinium. The calorimetric measurements have been done in a high-temperature calorimeter with cerium dioxide doped with 10 mole % of Gd[sub 2]O[sub 3]. Further thermodynamic quantities have been obtained by the electrochemical method and e.m.f. measurements, yielding additional information on disorders in doped cerium dioxide. (orig./BBR)

  6. Recovery of Cerium Dioxide from Spent Glass-Polishing Slurry and Its Utilization as a Reactive Sorbent for Fast Degradation of Toxic Organophosphates

    OpenAIRE

    Pavel Janoš; Pavel Kuráň; Jakub Ederer; Martin Šťastný; Luboš Vrtoch; Martin Pšenička; Jiří Henych; Karel Mazanec; Miroslav Skoumal

    2015-01-01

    The recovery of cerium (and possibly other rare earth elements) from the spent glass-polishing slurries is rather difficult because of a high resistance of polishing-grade cerium oxide toward common digestion agents. It was shown that cerium may be extracted from the spent polishing slurries by leaching with strong mineral acids in the presence of reducing agents; the solution may be used directly for the preparation of a ceria-based reactive sorbent. A mixture of concentrated nitric acid and...

  7. Synthesis of mesoporous cerium-zirconium mixed oxides by hydrothermal templating method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Mesoporous cerium-zirconium mixed oxides were prepared by hydrothermal method using cetyl trimethyl ammonium bromide (CTAB) as template.The effects of amount of template,pH value of solution and hydrothermal temperature on mesostructure of samples were systematically investigated.The final products were characterized by XRD,TEM,FT-IR,and BET.The results indicate that all the cerium-zirconium mixed oxides present a meso-structure.At molar ratio of n(CTAB)/n((Ce)+(Zr))=0.15,pH value of 9,and hydrothermal temperature of 120 ℃,the samples obtained possess a specific surface area of 207.9 m2/g with pore diameter of 3.70 nm and pore volume of 0.19 cm3/g.

  8. Radioluminescence and phosphororescence in electron-tube glasses doped with tin and cerium oxides

    International Nuclear Information System (INIS)

    Cerium and tin additions effect upon radioluminescence and phosphorescence of glasses (basic components are: SiO2, Al2O-3, ZnO, B2O3, Na2O, K2O) exposed to gamma radiation is studied. It has been shown that the following small amounts of CeO2 and SnO2 additions cause a considerable change in radioluminescence (2 times) and phosphorescence (more than an order). Tin oxide concentration increase results in radioluminescence growth in the short-wave spectral region. The dependence of radioluminescence and phosphorescence on cerium oxide concentration as well as the dependence of phosphorescence on tin oxide concentration has its maximum at 0.5-0.7 mass% of these additions. Radiation and optical characteristics of the glass under study have been compared to those of industrial glasses

  9. Growth of monodisperse nanocrystals of cerium oxide during synthesis and annealing

    International Nuclear Information System (INIS)

    Monodisperse cerium oxide nanocrystals have been successfully synthesised using simple ammonia precipitation technique from cerium(III) nitrate solution at different temperatures in the range 35-80 oC. The activation energy for growth of CeO2 nanocrystals during the precipitation is calculated as 11.54 kJ/mol using Arrhenius plot. Average crystal diameter was obtained from XRD analysis, HR-TEM and light scattering (PCS). The analysis of size data from HR-TEM images and PCS clearly indicated the formation of highly crystalline CeO2 particles in narrow size range. CeO2 nanocrystals precipitated at 35 oC were further annealed at temperatures in the range 300-700 oC. The activation energy for crystal growth during annealing is also calculated and is close to the reported values. An effort is made to predict the mechanism of crystal growth during the precipitation and annealing.

  10. Improvement and analysis of the hydrogen-cerium redox flow cell

    Science.gov (United States)

    Tucker, Michael C.; Weiss, Alexandra; Weber, Adam Z.

    2016-09-01

    The H2-Ce redox flow cell is optimized using commercially-available cell materials. Cell performance is found to be sensitive to the upper charge cutoff voltage, membrane boiling pretreatment, methanesulfonic-acid concentration, (+) electrode surface area and flow pattern, and operating temperature. Performance is relatively insensitive to membrane thickness, Cerium concentration, and all features of the (-) electrode including hydrogen flow. Cell performance appears to be limited by mass transport and kinetics in the cerium (+) electrode. Maximum discharge power of 895 mW cm-2 was observed at 60 °C; an energy efficiency of 90% was achieved at 50 °C. The H2-Ce cell is promising for energy storage assuming one can optimize Ce reaction kinetics and electrolyte.

  11. Color-Fading Spectrophotometric Determination of Cerium with DBC-Arsenazo

    Institute of Scientific and Technical Information of China (English)

    翟庆洲; 张晓霞

    2004-01-01

    In the medium of 0.18~1.08 mol·L-1 sulfuric acid, cerium(Ⅳ) has the color-fading effect on DBC-arsenazo. The apparent molar absorptivity of the color-fading reaction is ε530 nm=1.03×104 L·mol-1·cm-1. Beer′s law is obeyed over the range of 1.20~12.0 μg·ml-1 of Ce (Ⅳ) which shows a linear relationship with the decrease in the absorbance of the colored solution. The effect of thirty-six coexisting ions was studied. The method was applied to the determination of the trace amount of cerium in water samples and has the advantage of high accuracy and good selectivity.

  12. A Novel Open-Framework Cerium Phosphate Fluoride: (NH 4)[Ce IVF 2(PO 4)

    Science.gov (United States)

    Yu, Ranbo; Wang, Dan; Takei, Takahiro; Koizumi, Hitoshi; Kumada, Nobuhiro; Kinomura, Nobukazu

    2001-02-01

    A novel open-framework cerium phosphate fluoride, (NH4)[CeIVF2(PO4)], has been synthesized under hydrothermal conditions and characterized by means of single-crystal X-ray diffraction, ion chromatography analysis, and thermal analysis. The compound crystallizes in the monoclinic space group P21/m(No. 11), with a=6.660(2), b=5.875(2), c=7.177(3) Å, β=114.31(2)°, and V=255.9(2) Å3 (R=0.039 and Rw=0.045). In this compound, the cerium-centered CeO4F4 polyhedra link via Ce2F2 rings to form corrugated chains along the b axis of the structure. These are tetrahedrally connected via PO4 groups to create the three-dimensional network with a one-dimensional channel. NH+4 cations are accommodated at the intersection of the channels.

  13. Monte Carlo radiative transfer simulation of a cavity solar reactor for the reduction of cerium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Villafan-Vidales, H.I.; Arancibia-Bulnes, C.A.; Dehesa-Carrasco, U. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Privada Xochicalco s/n, Col. Centro, A.P. 34, Temixco, Morelos 62580 (Mexico); Romero-Paredes, H. [Departamento de Ingenieria de Procesos e Hidraulica, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco No.186, Col. Vicentina, A.P. 55-534, Mexico D.F 09340 (Mexico)

    2009-01-15

    Radiative heat transfer in a solar thermochemical reactor for the thermal reduction of cerium oxide is simulated with the Monte Carlo method. The directional characteristics and the power distribution of the concentrated solar radiation that enters the cavity is obtained by carrying out a Monte Carlo ray tracing of a paraboloidal concentrator. It is considered that the reactor contains a gas/particle suspension directly exposed to concentrated solar radiation. The suspension is treated as a non-isothermal, non-gray, absorbing, emitting, and anisotropically scattering medium. The transport coefficients of the particles are obtained from Mie-scattering theory by using the optical properties of cerium oxide. From the simulations, the aperture radius and the particle concentration were optimized to match the characteristics of the considered concentrator. (author)

  14. Effect of cerium oxide addition on electrical and physical properties of alkali borosilicate glasses

    International Nuclear Information System (INIS)

    The study of electrical conductivity, density and coefficient of thermal expansion (CTE) of Na2O:K2O:B2O3:SiO2:BaO glass samples with addition of cerium oxide has been carried out. It has been observed that the addition of cerium oxide affects the electrical conductivity, density and CTE. The results have been explained on the basis of the variation in number of bridging oxygens (BOs) and non-bridging oxygens (NBOs) present in the glass. In general, the glass with more NBOs has a weak network which exhibits higher electrical conductivity. The weakening of the network has been supported by the observed decrease in density and increase in CTE for the glasses.

  15. Spectral tunability of cerium photoluminescence in nano sized LaF3:Ce3+

    International Nuclear Information System (INIS)

    Nano sized LaF3:Ce3+ was synthesized by adopting co-precipitation technique with nominal composition as well as with different molar ratio of reactants La3+ (Lanthanum) and F− (Fluoride). All the samples were subjected to X-ray diffraction (XRD), XRF, UV-Vis absorption, and PL characterizations. XRD analysis did not reveal any significant change in the diffraction profile. Particle size variations were observed with respect to change in lanthanum to fluoride molar ratio. An interesting and intense photoluminescence excitation peaks were observed for the samples prepared non-stoichiometrically. The effect of varying nominal reactant composition demonstrates a possibility of introducing tunability in cerium emission in the same host. Life time of cerium has been measured to be in the order of nano seconds

  16. Energy transfer and thermal studies of Pr3+ doped cerium oxalate crystals

    Indian Academy of Sciences (India)

    R Pragash; Gijo Jose; N V Unnikrishnan; C Sudarsanakumar

    2011-07-01

    Energy transfer process at room temperature for cerium (sensitizer) oxalate single crystals doped with different concentrations (10, 13, 15, 17 and 20%) of praseodymium ions (activator) grown by hydro silica gel method has been evaluated. The analysis of energy level diagrams of cerium and praseodymium ions indicates that the energy gap between the sensitizer and the activator ions varies in a small range suggesting a possible energy transfer from the Ce3+ to Pr3+. The emission and absorption spectra of these crystals were recorded. The overlapping of the absorption spectra of Pr3+ and emission spectra of Ce3+ at wavelengths 484 and 478 nm, respectively, strongly supports the possible energy transfer process in this system. From the absorption spectra, oscillator strength, electric dipole moment, branching ratio and Judd–Ofelt parameters of this system were evaluated by least square programming. The quantum efficiency, energy transfer probabilities and thermal properties have been studied.

  17. Macro-loading Effects in Inductively Coupled Plasma Etched Mercury Cadmium Telluride

    Science.gov (United States)

    Apte, Palash; Rybnicek, Kimon; Stoltz, Andrew

    2016-09-01

    This paper reports the effect of macro-loading on mercury cadmium telluride (Hg1- x Cd x Te) and Photoresist (PR) etched in an inductively coupled plasma (ICP). A significant macro-loading effect is observed, which affects the etch rates of both PR and Hg1- x Cd x Te. It is observed that the exposed silicon area has a significant effect on the PR etch rate, but not on the Hg1- x Cd x Te etch rate. It is also observed that the exposed Hg1- x Cd x Te area has a significant effect on the etch rate of the PR, but the exposed PR area does not seem to have an effect on the Hg1- x Cd x Te etch rate. Further, the exposed Hg1- x Cd x Te area is shown to affect the etch rate of the Hg1- x Cd x Te, but there does not seem to be a similar effect for the exposed PR area on the etch rate of the PR. Since the macro-loading affects the selectivity significantly, this effect can cause significant problems in the etching of deep trenches. A few techniques to reduce the effect of macro-loading on the etch rates of the PR and Hg1- x Cd x Te are listed, herein.

  18. The effects of surface treatments for low temperature silicon dioxide deposition on cadmium telluride

    International Nuclear Information System (INIS)

    The authors have successfully deposited thin films of SiO2 on a cadmium telluride substrate at low temperature (Ts = 100 degrees C-300 degrees C) by remote plasma enhanced chemical vapor deposition (remote PECVD). The native oxide on the CdTe substrate has been removed, prior to deposition by either chemical etching in methanol and 1% bromine, or by dissolution in deionized water. After removal of the native oxide, the CdTe was inserted into a UHV-compatible deposition chamber and a He+ plasma treatment was performed prior to deposition of an SiO2 film. This treatment promotes strong adhesion between the deposited SiO2 film and CdTe surface. The authors find that the initial oxide removal process does not influence SiO2 adhesion. They report on the effect of the He+ plasma treatment on the CdTe surface studied by Auger electron spectroscopy(AES), and reflection high energy electron diffraction (RHEED)

  19. Heart imaging by cadmium telluride gamma camera European Program 'BIOMED' consortium

    CERN Document Server

    Scheiber, C; Chambron, J; Prat, V; Kazandjan, A; Jahnke, A; Matz, R; Thomas, S; Warren, S; Hage-Hali, M; Regal, R; Siffert, P; Karman, M

    1999-01-01

    Cadmium telluride semiconductor detectors (CdTe) operating at room temperature are attractive for medical imaging because of their good energy resolution providing excellent spatial and contrast resolution. The compactness of the detection system allows the building of small light camera heads which can be used for bedside imaging. A mobile pixellated gamma camera based on 2304 CdTe (pixel size: 3x3 mm, field of view: 15 cmx15 cm) has been designed for cardiac imaging. A dedicated 16-channel integrated circuit has also been designed. The acquisition hardware is fully programmable (DSP card, personal computer-based system). Analytical calculations have shown that a commercial parallel hole collimator will fit the efficiency/resolution requirements for cardiac applications. Monte-Carlo simulations predict that the Moire effect can be reduced by a 15 deg. tilt of the collimator with respect to the detector grid. A 16x16 CdTe module has been built for the preliminary physical tests. The energy resolution was 6.16...

  20. Synthesis of the titanium phosphide telluride Ti2PTe2: A thermochemical approach

    International Nuclear Information System (INIS)

    The phosphide telluride Ti2PTe2 can be synthesised from the elements or from oxides in a thermite type reaction. Both ways have been optimised by consideration of the thermodynamic behaviour of the compound. Hence, the investigation of phase equilibria in the ternary system Ti/P/Te and of the thermal decomposition of Ti2PTe2 was necessary. This investigation was performed by using different experimental approaches as total pressure measurements, thermal analysis and mass spectrometry. The results were supported and further analysed by thermodynamic modelling of the ternary system. It was shown that Ti2PTe2(s) decomposes to Ti2P(s) and Te2(g) in six consecutive steps. The growth of single crystals of Ti2PTe2 is thermodynamically described as a chemical vapour transport with TiCl4(g) acting as the transport agent. - Graphical abstract: Oxygen partial pressure and electrochemical potential above the oxides of titanium, tellurium and phosphorus calculated at 1000 K, marked: level of equalisation of oxygen partial pressure

  1. Low-cost cadmium zinc telluride radiation detectors based on electron-transport-only designs

    International Nuclear Information System (INIS)

    The goal of this project was to utilize a novel device design to build a compact, high resolution, room temperature operated semiconductor gamma ray sensor. This sensor was constructed from a cadmium zinc telluride (CZT) crystal. It was able to both detect total radiation intensity and perform spectroscopy on the detected radiation. CZT detectors produced today have excellent electron charge carrier collection, but suffer from poor hole collection. For conventional gamma-ray spectrometers, both the electrons and holes must be collected with high efficiency to preserve energy resolution. The requirement to collect the hole carriers, which have relatively low lifetimes, limits the efficiency and performance of existing experimental devices. By implementing novel device designs such that the devices rely only on the electron signal for energy information, the sensitivity of the sensors for detecting radiation can be increased substantially. In this report the authors describe a project to develop a new type of electron-only CZT detector. They report on their successful efforts to design, implement and test these new radiation detectors. In addition to the design and construction of the sensors the authors also report, in considerable detail, on the electrical characteristics of the CZT crystals used to make their detectors

  2. Two-color detector: Mercury-cadmium-telluride as a terahertz and infrared detector

    Energy Technology Data Exchange (ETDEWEB)

    Sizov, F.; Zabudsky, V.; Petryakov, V.; Golenkov, A.; Andreyeva, K.; Tsybrii, Z. [Institute of Semiconductor Physics, 03028 Kiev (Ukraine); Dvoretskii, S. [Institute of Semiconductor Physics of SB RAS, 630090 Novosibirsk (Russian Federation)

    2015-02-23

    In this paper, issues associated with the development of infrared (IR) and terahertz (THz) radiation detectors based on HgCdTe are discussed. Two-color un-cooled and cooled to 78 K narrow-gap mercury-cadmium-telluride semiconductor thin layers with antennas were considered both as sub-THz (sub-THz) direct detection bolometers and 3–10 μm IR photoconductors. The noise equivalent power (NEP) for one of the detectors studied at ν ≈ 140 GHz reaches NEP{sub 300 K} ≈ 4.5 × 10{sup −10} W/Hz{sup 1/2} and NEP{sub 78 K} ≈ 5 × 10{sup −9} W/Hz{sup 1/2}. The same detector used as an IR photoconductor showed the responsivity at temperatures T = 78 K and 300 K with signal-to-noise ratio S/N ≈ 750 and 50, respectively, under illumination by using IR monochromator and globar as a thermal source.

  3. Heart imaging by cadmium telluride gamma cameraEuropean Program ``BIOMED'' consortium

    Science.gov (United States)

    Scheiber, Ch.; Eclancher, B.; Chambron, J.; Prat, V.; Kazandjan, A.; Jahnke, A.; Matz, R.; Thomas, S.; Warren, S.; Hage-Hali, M.; Regal, R.; Siffert, P.; Karman, M.

    1999-06-01

    Cadmium telluride semiconductor detectors (CdTe) operating at room temperature are attractive for medical imaging because of their good energy resolution providing excellent spatial and contrast resolution. The compactness of the detection system allows the building of small light camera heads which can be used for bedside imaging. A mobile pixellated gamma camera based on 2304 CdTe (pixel size: 3×3 mm, field of view: 15 cm×15 cm) has been designed for cardiac imaging. A dedicated 16-channel integrated circuit has also been designed. The acquisition hardware is fully programmable (DSP card, personal computer-based system). Analytical calculations have shown that a commercial parrallel hole collimator will fit the efficiency/resolution requirements for cardiac applications. Monte-Carlo simulations predict that the Moire effect can be reduced by a 15° tilt of the collimator with respect to the detector grid. A 16×16 CdTe module has been built for the preliminary physical tests. The energy resolution was 6.16±0.6 keV (mean ± standard deviation, n=30). Uniformity was ±10%, improving to ±1% when using a correction table. Test objects (emission data: letters 1.8 mm in width) and cold rods in scatter medium have been acquired. The CdTe images have been compared to those acquired with a conventionnal gamma camera.

  4. Thin film cadmium telluride solar cells by two chemical vapor deposition techniques

    Energy Technology Data Exchange (ETDEWEB)

    Chu, T.L.

    1988-01-15

    Cadmium telluride (CdTe) has long been recognized as a promising thin film photovoltaic material. In this work, polycrystalline p-CdTe films have been deposited by two chemical vapor deposition techniques, namely the combination of vapors of elements (CVE) and close-spaced sublimation (CSS). The CVE technique is more flexible in controlling the composition of deposited films while the CSS technique can provide very high deposition rates. The resistivity of p-CdTe films deposited by the CVE and CSS techniques can be controlled by intrinsic (cadmium vacancies) or extrinsic (arsenic or antimony) doping, and the lowest resistivity obtainable is about 200 ..cap omega.. cm. Both front-wall (CdTe/TCS/glass) and back-wall (TCS/CdTe/substrate) cells have been prepared. The back-wall cells are less efficient because of the high and irreproducible p-CdTe-substrate interface resistance. The CSS technique is superior to the CVE technique because of its simplicity and high deposition rates; however, the cleaning of the substrate in situ is more difficult. The interface cleanliness is an important factor determining the electrical and photovoltaic characteristics of the heterojunction. Heterojunction CdS/CdTe solar cells of area 1 cm/sup 2/ with conversion efficiencies higher than 10% have been prepared and junction properties characterized.

  5. Investigation of the Electronic Properties of Cadmium Zinc Telluride (CZT) Detectors using a Nuclear Microprobe

    International Nuclear Information System (INIS)

    The electronic transport properties of Cadmium Zinc Telluride (CZT) determine the charge collection efficiency (i.e. the signal quality) of CZT detectors. These properties vary on both macroscopic and microscopic scale and depend on the presence of impurities and defects introduced during the crystal growth. Ion Beam Induced Charge Collection (IBICC) is a proven method to measure the charge collection efficiency. Using an ion microbeam, the charge collection efficiency can be mapped with submicron resolution, and the map of electronic properties (such as drift length) can be calculated from the measurement. A more sophisticated version of IBICC, the Time Resolved IBICC (TRIBICC) allows them to determine the mobility and the life time of the charge carriers by recording and analyzing the transient waveform of the detector signal. Furthermore, lateral IBICC and TRIBICC can provide information how the charge collection efficiency depends on the depth where the charge carriers are generated. This allows one to deduce information on the distribution of the electric field and transport properties of the charge carriers along the detector axis. IBICC and TRIBICC were used at the Sandia microbeam facility to image electronic properties of several CZT detectors. From the lateral TRIBICC measurement the electron and hole drift length profiles were calculated

  6. Heart imaging by cadmium telluride gamma camera European Program 'BIOMED' consortium

    International Nuclear Information System (INIS)

    Cadmium telluride semiconductor detectors (CdTe) operating at room temperature are attractive for medical imaging because of their good energy resolution providing excellent spatial and contrast resolution. The compactness of the detection system allows the building of small light camera heads which can be used for bedside imaging. A mobile pixellated gamma camera based on 2304 CdTe (pixel size: 3x3 mm, field of view: 15 cmx15 cm) has been designed for cardiac imaging. A dedicated 16-channel integrated circuit has also been designed. The acquisition hardware is fully programmable (DSP card, personal computer-based system). Analytical calculations have shown that a commercial parallel hole collimator will fit the efficiency/resolution requirements for cardiac applications. Monte-Carlo simulations predict that the Moire effect can be reduced by a 15 deg. tilt of the collimator with respect to the detector grid. A 16x16 CdTe module has been built for the preliminary physical tests. The energy resolution was 6.16±0.6 keV (mean ± standard deviation, n=30). Uniformity was ±10%, improving to ±1% when using a correction table. Test objects (emission data: letters 1.8 mm in width) and cold rods in scatter medium have been acquired. The CdTe images have been compared to those acquired with a conventionnal gamma camera

  7. Inhibition of autophagy contributes to the toxicity of cadmium telluride quantum dots in Saccharomyces cerevisiae.

    Science.gov (United States)

    Fan, Junpeng; Shao, Ming; Lai, Lu; Liu, Yi; Xie, Zhixiong

    2016-01-01

    Cadmium telluride quantum dots (CdTe QDs) are used as near-infrared probes in biologic and medical applications, but their cytological effects and mechanism of potential toxicity are still unclear. In this study, we evaluated the toxicity of CdTe QDs of different sizes and investigated their mechanism of toxicity in the yeast Saccharomyces cerevisiae. A growth inhibition assay revealed that orange-emitting CdTe (O-CdTe) QDs (half inhibitory concentration [IC50] =59.44±12.02 nmol/L) were more toxic than green-emitting CdTe QDs (IC50 =186.61±19.74 nmol/L) to S. cerevisiae. Further studies on toxicity mechanisms using a transmission electron microscope and green fluorescent protein tagged Atg8 processing assay revealed that O-CdTe QDs could partially inhibit autophagy at a late stage, which differs from the results reported in mammalian cells. Moreover, autophagy inhibited at a late stage by O-CdTe QDs could be partially recovered by enhancing autophagy with rapamycin (an autophagy activator), combined with an increased number of living cells. These results indicate that inhibition of autophagy acts as a toxicity mechanism of CdTe QDs in S. cerevisiae. This work reports a novel toxicity mechanism of CdTe QDs in yeast and provides valuable information on the effect of CdTe QDs on the processes of living cells. PMID:27524895

  8. Two-color detector: Mercury-cadmium-telluride as a terahertz and infrared detector

    International Nuclear Information System (INIS)

    In this paper, issues associated with the development of infrared (IR) and terahertz (THz) radiation detectors based on HgCdTe are discussed. Two-color un-cooled and cooled to 78 K narrow-gap mercury-cadmium-telluride semiconductor thin layers with antennas were considered both as sub-THz (sub-THz) direct detection bolometers and 3–10 μm IR photoconductors. The noise equivalent power (NEP) for one of the detectors studied at ν ≈ 140 GHz reaches NEP300 K ≈ 4.5 × 10−10 W/Hz1/2 and NEP78 K ≈ 5 × 10−9 W/Hz1/2. The same detector used as an IR photoconductor showed the responsivity at temperatures T = 78 K and 300 K with signal-to-noise ratio S/N ≈ 750 and 50, respectively, under illumination by using IR monochromator and globar as a thermal source

  9. Investigation of the electrochemical deposition of thick layers of cadmium telluride

    International Nuclear Information System (INIS)

    This research thesis deals with the problem of electrochemical deposition of thick layers of cadmium telluride (CdTe) meeting the requirements of high energy radiation detection. The author first recalls the physicochemical properties of CdTe and the basic principles of radiology. He details the different criteria which define a material for X ray detection. He describes the experimental conditions, the nature and preparation of substrates, and the different electrochemical systems used in this research. He studies the impact of the applied potential on the material properties, and compares previously obtained results available in the literature with those obtained in the chosen pool conditions. He discusses the synthesis of CdTe thick layers for which different methods are tested: static in potential, static in intensity, pulsed. The coatings obtained with a given potential and then with a given current are investigated. Finally, the influence of a thermal treatment in presence or absence of a sintering agent on the morphology, the chemical composition, and the crystalline and electric properties of the deposited material is discussed, and the results of the behaviour under X rays of a electrodeposited layer are presented

  10. Theory of the electronic properties of mercury-cadmium-telluride alloys

    Science.gov (United States)

    Chen, A. B.; Sher, A.

    1984-02-01

    An accurate band-structure theory for semiconductor alloys was achieved. It has been successfully applied to Mercury-Cadmium-Telluride alloys (MCT), and is being extended to III-V and other II-VI semiconductor alloys. As a result of this research, ten papers have been published. Several other papers and one book are in progress. The most important finding was the origin of the major disorder and its effects on different parts of the band structure. The large s-energy fluctuation between the Hg and Cd sites was found to cause a large smearing in the density of states about 5 eV below the top of the valence band, but it produced very little bowing and scattering for the states near the band gap. A detailed study of these facts accounts for the lattice instability of MCT and its very high electron mobility. Another significant result is that, while Cd weakens a neighboring Hg-Te bond, Zn strengthens it. Such structural studies may help resolve the adverse structural difficulties affecting MCT as an infrared material.

  11. Solar Hydrogen Production from Zinc Telluride Photocathode Modified with Carbon and Molybdenum Sulfide.

    Science.gov (United States)

    Jang, Youn Jeong; Lee, Jaehyuk; Lee, Jinwoo; Lee, Jae Sung

    2016-03-30

    A zinc telluride (ZnTe) film modified with MoS2 and carbon has been studied as a new photocathode for solar hydrogen production from photoelectrochemical (PEC) water splitting. The modification enhances PEC activity and stability of the photocathode. Thus, the MoS2/C/ZnTe/ZnO electrode exhibits highly improved activity of -1.48 mA cm(-2) at 0 VRHE with a positively shifted onset potential up to 0.3 VRHE relative to bare ZnO/ZnTe electrode (-0.19 mA cm(-2), 0.18 VRHE) under the simulated 1 sun illumination. This represents the highest value ever reported for ZnTe-based electrodes in PEC water splitting. The carbon densely covers the surface of ZnTe to protect it against photocorrosion in aqueous electrolyte and improves charge separation. In addition, MoS2 further enhances the PEC performance as a hydrogen evolution co-catalyst. PMID:26909873

  12. Simulation study comparing high-purity germanium and cadmium zinc telluride detectors for breast imaging

    International Nuclear Information System (INIS)

    We conducted simulations to compare the potential imaging performance for breast cancer detection with High-Purity Germanium (HPGe) and Cadmium Zinc Telluride (CZT) systems with 1% and 3.8% energy resolution at 140 keV, respectively. Using the Monte Carlo N-Particle (MCNP5) simulation package, we modelled both 5 mm-thick CZT and 10 mm-thick HPGe detectors with the same parallel-hole collimator for the imaging of a breast/torso phantom. Simulated energy spectra were generated, and planar images were created for various energy windows around the 140 keV photopeak. Relative sensitivity and scatter and the torso fractions were calculated along with tumour contrast and signal-to-noise ratios (SNR). Simulations showed that utilizing a ±1.25% energy window with an HPGe system better suppressed torso background and small-angle scattered photons than a comparable CZT system using a −5%/+10% energy window. Both systems provided statistically similar contrast and SNR, with HPGe providing higher relative sensitivity. Lowering the counts of HPGe images to match CZT count density still yielded equivalent contrast between HPGe and CZT. Thus, an HPGe system may provide equivalent breast imaging capability at lower injected radioactivity levels when acquiring for equal imaging time. (paper)

  13. Thermal transport in bismuth telluride quintuple layer: mode-resolved phonon properties and substrate effects

    Science.gov (United States)

    Shao, Cheng; Bao, Hua

    2016-06-01

    The successful exfoliation of atomically-thin bismuth telluride (Bi2Te3) quintuple layer (QL) attracts tremendous research interest in this strongly anharmonic quasi-two-dimensional material. The thermal transport properties of this material are not well understood, especially the mode-wise properties and when it is coupled with a substrate. In this work, we have performed molecular dynamics simulations and normal mode analysis to study the mode-resolved thermal transport in freestanding and supported Bi2Te3 QL. The detailed mode-wise phonon properties are calculated and the accumulated thermal conductivities with respect to phonon mean free path (MFP) are constructed. It is shown that 60% of the thermal transport is contributed by phonons with MFP longer than 20 nm. Coupling with a-SiO2 substrate leads to about 60% reduction of thermal conductivity. Through varying the interfacial coupling strength and the atomic mass of substrate, we also find that phonon in Bi2Te3 QL is more strongly scattered by interfacial potential and its transport process is less affected by the dynamics of substrate. Our study provides an in-depth understanding of heat transport in Bi2Te3 QL and is helpful in further tailoring its thermal property through nanostructuring.

  14. Varying cadmium telluride growth temperature during deposition to increase solar cell reliability

    Energy Technology Data Exchange (ETDEWEB)

    Albin, David S.; Johnson, James Neil; Zhao, Yu; Korevaar, Bastiaan Arie

    2016-04-26

    A method for forming thin films or layers of cadmium telluride (CdTe) for use in photovoltaic modules or solar cells. The method includes varying the substrate temperature during the growth of the CdTe layer by preheating a substrate (e.g., a substrate with a cadmium sulfide (CdS) heterojunction or layer) suspended over a CdTe source to remove moisture to a relatively low preheat temperature. Then, the method includes directly heating only the CdTe source, which in turn indirectly heats the substrate upon which the CdTe is deposited. The method improves the resulting CdTe solar cell reliability. The resulting microstructure exhibits a distinct grain size distribution such that the initial region is composed of smaller grains than the bulk region portion of the deposited CdTe. Resulting devices exhibit a behavior suggesting a more n-like CdTe material near the CdS heterojunction than devices grown with substrate temperatures held constant during CdTe deposition.

  15. 3D Particle Track Reconstrution in a Single Layer Cadmium-Telluride Hybrid Active Pixel Detector

    CERN Document Server

    Filipenko, Mykhaylo; Anton, Gisela; Michel, Thilo

    2014-01-01

    In the past 20 years the search for neutrinoless double beta decay has driven many developements in all kind of detector technology. A new branch in this field are highly-pixelated semiconductor detectors - such as the CdTe-Timepix detectors. It compromises a cadmium-telluride sensor of 14 mm x 14 mm x 1 mm size with an ASIC which has 256 x 256 pixel of 55 \\textmu m pixel pitch and can be used to obtain either spectroscopic or timing information in every pixel. In regular operation it can provide a 2D projection of particle trajectories; however, three dimensional trajectories are desirable for neutrinoless double beta decay and other applications. In this paper we present a method to obtain such trajectories. The method was developed and tested with simulations that assume some minor modifications to the Timepix ASIC. Also, we were able to test the method experimentally and in the best case achieved a position resolution of about 90 \\textmu m with electrons of 4.4 GeV.

  16. Cadmium telluride nanoparticles loaded on activated carbon as adsorbent for removal of sunset yellow

    Science.gov (United States)

    Ghaedi, M.; Hekmati Jah, A.; Khodadoust, S.; Sahraei, R.; Daneshfar, A.; Mihandoost, A.; Purkait, M. K.

    2012-05-01

    Adsorption is a promising technique for decolorization of effluents of textile dyeing industries but its application is limited due to requirement of high amounts of adsorbent required. The objective of this study was to assess the potential of cadmium telluride nanoparticles loaded onto activated carbon (CdTN-AC) for the removal of sunset yellow (SY) dye from aqueous solution. Adsorption studies were conducted in a batch mode varying solution pH, contact time, initial dye concentration, CdTN-AC dose, and temperature. In order to investigate the efficiency of SY adsorption on CdTN-AC, pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion kinetic models were studied. It was observed that the pseudo-second-order kinetic model fits better than other kinetic models with good correlation coefficient. Equilibrium data were fitted to the Langmuir model. Thermodynamic parameters such as enthalpy, entropy, activation energy, and sticking probability were also calculated. It was found that the sorption of SY onto CdTN-AC was spontaneous and endothermic in nature. The proposed adsorbent is applicable for SY removal from waste of real effluents including pea-shooter, orange drink and jelly banana with efficiency more than 97%.

  17. Novel Cadmium Zinc Telluride Devices for Myocardial Perfusion Imaging-Technological Aspects and Clinical Applications.

    Science.gov (United States)

    Ben-Haim, Simona; Kennedy, John; Keidar, Zohar

    2016-07-01

    Myocardial perfusion imaging plays an important role in the assessment of patients with known or suspected coronary artery disease and is well established for diagnosis and for prognostic evaluation in these patients. The dedicated cardiac SPECT cameras with solid-state cadmium zinc telluride (CZT) detectors were first introduced a decade ago. A large body of evidence is building up, showing the superiority of the new technology compared with conventional gamma cameras. Not only the CZT detectors, but also new collimator geometries, the ability to perform focused imaging optimized for the heart and advances in data processing algorithms all contribute to the significantly improved sensitivity up to 8-10 times, as well as improved energy resolution and improved reconstructed spatial resolution compared with conventional technology. In this article, we provide an overview of the physical characteristics of the CZT cameras, as well as a review of the literature published so far, including validation studies in comparison with conventional myocardial perfusion imaging and with invasive coronary angiography, significant reduction in radiation dose, and new imaging protocols enabled by the new technology. PMID:27237438

  18. Influence of the Ion Coordination Number on Cation Exchange Reactions with Copper Telluride Nanocrystals

    CERN Document Server

    Tu, Renyong; Bertoni, Giovanni; Lak, Aidin; Gaspari, Roberto; Rapallo, Arnaldo; Cavalli, Andrea; De Trizio, Luca; Manna, Liberato

    2016-01-01

    Cu2-xTe nanocubes were used as starting seeds to access metal telluride nanocrystals by cation exchanges at room temperature. The coordination number of the entering cations was found to play an important role in dictating the reaction pathways. The exchanges with tetrahedrally coordinated cations (i.e. with coordination number 4), such as Cd2+ or Hg2+, yielded monocrystalline CdTe or HgTe nanocrystals with Cu2-xTe/CdTe or Cu2-xTe/HgTe Janus-like heterostructures as intermediates. The formation of Janus-like architectures was attributed to the high diffusion rate of the relatively small tetrahedrally coordinated cations, which could rapidly diffuse in the Cu2-xTe NCs and nucleate the CdTe (or HgTe) phase in a preferred region of the host structure. Also, with both Cd2+ and Hg2+ ions the exchange led to wurtzite CdTe and HgTe phases rather than the more stable zinc-blende ones, indicating that the anion framework of the starting Cu2- xTe particles could be more easily deformed to match the anion framework of t...

  19. Quantitative analysis of defect formation in cadmium telluride during high energy electron irradiation

    International Nuclear Information System (INIS)

    Single crystals of cadmium telluride have been irradiated in a high energy electron microscope. During exposure to the electron beam, extended defects which are interstitial type dislocation loops are created. The influence of experimental parameters on the loops characteristics has been investigated. Chemical Reaction Rate Theory has been developed in order to account for the kinetics of loop growth. In this way the elementary processes and their corresponding activation energies have been identified. It has been shown that the migration energy is modified around point defects and that, as a consequence, the interstitial-interstitial agglomeration energy Ei is different from the interstitial-vacancy annihilation energy Ev:Ei = 0.35 eV, Ev = 0.25 eV. The comparison between experimental and theoretical data has shown that small clusters are not stable and the dissociation energy of an atom from a low size aggregate is Ed 1.1 eV. The effects of surfaces have been considered and two different treatments have been developed. This investigation has allowed us to point out that the surface efficiency is not so high as predicted by diffusion theory and that screening effects have to be considered. These latter could be the local diffusion of interstitial towards the dislocation loops. (author)

  20. Influence of germanium nano-inclusions on the thermoelectric power factor of bulk bismuth telluride alloy

    Energy Technology Data Exchange (ETDEWEB)

    Satyala, Nikhil; Zamanipour, Zahra; Norouzzadeh, Payam; Krasinski, Jerzy S.; Vashaee, Daryoosh, E-mail: daryoosh.vashaee@okstate.edu [School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, Oklahoma 74106 (United States); Tahmasbi Rad, Armin [School of Material Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, Oklahoma 74106 (United States); Tayebi, Lobat, E-mail: daryoosh.vashaee@okstate.edu [School of Chemical Engineering, Oklahoma State University, Stillwater, Oklahoma 74078 (United States)

    2014-05-28

    Nanocomposite thermoelectric compound of bismuth telluride (Bi{sub 2}Te{sub 3}) with 5 at. % germanium nano-inclusions was prepared via mechanically alloying and sintering techniques. The influence of Ge nano-inclusions and long duration annealing on the thermoelectric properties of nanostructured Bi{sub 2}Te{sub 3} were investigated. It was found that annealing has significant effect on the carrier concentration, Seebeck coefficient, and the power factor of the thermoelectric compound. The systematic heat treatment also reduced the density of donor type defects thereby decreasing the electron concentration. While the as-pressed nanocomposite materials showed n-type properties, it was observed that with the increase of annealing time, the nanocomposite gradually transformed to an abundantly hole-dominated (p-type) sample. The long duration annealing (∼500 h) resulted in a significantly enhanced electrical conductivity pertaining to the augmentation in the density and the structural properties of the sample. Therefore, a simultaneous enhancement in both electrical and Seebeck coefficient characteristics resulted in a remarkable increase in the thermoelectric power factor.

  1. Energy-discriminating X-ray computed tomography system utilizing a cadmium telluride detector

    International Nuclear Information System (INIS)

    An energy-discriminating K-edge X-ray computed tomography (CT) system is useful for increasing contrast resolution of a target region utilizing contrast media and for reducing the absorbed dose for patients. The CT system is of the first-generation type with a cadmium telluride (CdTe) detector, and a projection curve is obtained by translation scanning using the CdTe detector in conjunction with an x-stage. An object is rotated by the rotation step angle using a turntable between the translation scans. Thus, CT is carried out by repeating the translation scanning and the rotation of an object. Penetrating X-ray photons from the object are detected by the CdTe detector, and event signals of X-ray photons are produced using charge-sensitive and shaping amplifiers. Both the photon energy and the energy width are selected by use of a multi-channel analyzer, and the number of photons is counted by a counter card. Demonstration of enhanced iodine K-edge X-ray CT was carried out by selecting photons with energies just beyond the iodine K-edge energy of 33.2 keV.

  2. Measurement and Modeling of Blocking Contacts for Cadmium Telluride Gamma Ray Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Patrick R. [California Polytechnic State Univ. (CalPoly), San Luis Obispo, CA (United States)

    2010-01-07

    Gamma ray detectors are important in national security applications, medicine, and astronomy. Semiconductor materials with high density and atomic number, such as Cadmium Telluride (CdTe), offer a small device footprint, but their performance is limited by noise at room temperature; however, improved device design can decrease detector noise by reducing leakage current. This thesis characterizes and models two unique Schottky devices: one with an argon ion sputter etch before Schottky contact deposition and one without. Analysis of current versus voltage characteristics shows that thermionic emission alone does not describe these devices. This analysis points to reverse bias generation current or leakage through an inhomogeneous barrier. Modeling the devices in reverse bias with thermionic field emission and a leaky Schottky barrier yields good agreement with measurements. Also numerical modeling with a finite-element physics-based simulator suggests that reverse bias current is a combination of thermionic emission and generation. This thesis proposes further experiments to determine the correct model for reverse bias conduction. Understanding conduction mechanisms in these devices will help develop more reproducible contacts, reduce leakage current, and ultimately improve detector performance.

  3. Effect of cerium addition on microstructure and texture of aluminum foil for electrolytic capacitors

    Institute of Scientific and Technical Information of China (English)

    王海燕; 李文学; 任慧平; 黄丽颖; 王向阳

    2010-01-01

    Anode foil of aluminum electrolytic capacitor,which requires large surface area for high capacitance,were prepared by rolling,annealing and electrochemical etching.Effects of cerium addition on the capacitance of aluminum electrolytic capacitors were investigated.Microstructure of the aluminum foil surface was observed by optical microscopy(OM) and scanning electron microscopy(SEM).Electron back scattered diffraction(EBSD) was also employed to reveal texture evolvement of cold-rolled aluminum foil after ann...

  4. Protection of the AZ31 magnesium alloy with cerium modified silane coatings

    International Nuclear Information System (INIS)

    Highlights: → Silane conversion coatings as possible alternative to Cr(VI) based pre-treatments. → 3-mercapto-propyl-trimethoxysilane (PropS-SH) tested on Mg alloys. → PropS-SH forms a porous conversion coating which allows a rapid electrolyte uptake. → Ce(NO3)3 addition to pre-treatment bath improves PropS-SH coating performance. → Ce3+ ions presence provides self-healing feature to the coating. - Abstract: This research investigates the effect of cerium ion addition on the efficiency of a 3-mercapto-propyl-trimethoxysilane (PropS-SH) coating formed on AZ31 magnesium alloy. The coating was obtained by dipping AZ31 coupons in a hydroalcoholic 3-mercapto-propyl-trimethoxysilane solution, added with cerium nitrate, in order to obtain a 5 x 10-3 or 5 x 10-4 M Ce+3 ion concentration. The silane baths were regulated at pH 4 and utilized for filming treatment after 48 h following their preparation. The treated specimens were finally cured for 1 h at 100 deg. C. The protective efficiency of cerium modified and unmodified PropS-SH coatings was evaluated by recording potentiodynamic polarization curves and electrochemical impedance spectra in a 0.1 M NaCl environment. In comparison to PropS-SH coating, cerium nitrate modified silane layer exhibited noticeably improved performances, in particular in presence of a 5 x 10-3 M Ce3+ concentration. The increased protectiveness and stability of the modified coatings were attributed to a lower porosity and defectiveness and to self-healing ability provided by Ce3+ ion presence.

  5. Theoretical modeling of heterogeneous catalysts based on platinum and cerium oxide

    OpenAIRE

    Bruix Fusté, Albert

    2014-01-01

    This thesis focuses on the computational study of models for platinum catalysts supported on cerium oxide (CeO2) which are of technological relevance. In these catalysts, ceria is often found acting as a non-inert support, leading to complex metal-support interactions (MSI) that modify the properties of both the oxide and the supported metal. First principles computational methods based on the Density functional Theory (DFT) have been used to study the nature of these interactions and their e...

  6. Effect of Pressure on the Ferromagnetic Cerium Compound CeCu9Sn4

    International Nuclear Information System (INIS)

    Electrical resistivity measurements under hydrostatic pressure up to 2.2 GPa was carried out for a ferromagnetic ternary cerium compound CeCu9Sn4. The ferromagnetic transition temperature increases with increasing pressure up to 0.8 GPa and then decreases with increasing pressure above 1 GPa. Origins of this pressure dependence may be the competition between magnetic interaction in the c-plane and along the c-direction. (author)

  7. A cerium glass fiber-optic active target for high energy physics experiments

    International Nuclear Information System (INIS)

    A fiber-optic plate imaging system has been developed for active target and tracking applications, in which the active element is Ce(3+) in a silicate glass. Particle tracks and interactions have been recorded with a hit density of greater than or equal to 4/mm for minimum ionizing particles and with a spatial resolution sigma approx. = 28μ m.) The properties of cerium scintillation glass are discussed

  8. Redox-active cerium oxide nanoparticles protect human dermal fibroblasts from PQ-induced damage

    OpenAIRE

    Claudia von Montfort; Lirija Alili; Sarah Teuber-Hanselmann; Peter Brenneisen

    2014-01-01

    Recently, it has been published that cerium (Ce) oxide nanoparticles (CNP; nanoceria) are able to downregulate tumor invasion in cancer cell lines. Redox-active CNP exhibit both selective pro-oxidative and antioxidative properties, the first being responsible for impairment of tumor growth and invasion. A non-toxic and even protective effect of CNP in human dermal fibroblasts (HDF) has already been observed. However, the effect on important parameters such as cell death, proliferation and red...

  9. Nanocrystalline cerium dioxide efficacy for gastrointestinal motility: potential for prokinetic treatment and prevention in elderly

    OpenAIRE

    Yefimenko, Olena Yu; Savchenko, Yuliya O; Tetyana M. Falalyeyeva; Beregova, Tetyana V; Zholobak, Nadiya M; Spivak, Mykola Ya; Shcherbakov, Oleksandr B; Bubnov, Rostyslav V

    2015-01-01

    Background Constipation is a common condition, with prevalence after 65 years, is a major colorectal cancer risk factor. Recent works have demonstrated advances in personalized, preventive nanomedicine, leading to the construction of new materials and nanodrugs, in particular, nanocrystalline cerium dioxide (NCD), having strong antioxidative prebiotic effect. The aim of our study was to investigate the influence of NCD on motor function of the stomach and colon in vivo and contractive activit...

  10. Untangling the biological effects of cerium oxide nanoparticles: the role of surface valence states

    OpenAIRE

    Gerardo Pulido-Reyes; Ismael Rodea-Palomares; Soumen Das; Tamil Selvan Sakthivel; Francisco Leganes; Roberto Rosal; Sudipta Seal; Francisca Fernández-Piñas

    2015-01-01

    Cerium oxide nanoparticles (nanoceria; CNPs) have been found to have both pro-oxidant and anti-oxidant effects on different cell systems or organisms. In order to untangle the mechanisms which underlie the biological activity of nanoceria, we have studied the effect of five different CNPs on a model relevant aquatic microorganism. Neither shape, concentration, synthesis method, surface charge (ζ-potential), nor nominal size had any influence in the observed biological activity. The main drive...

  11. One step hydrothermal synthesis of a carbon nanotube/cerium oxide nanocomposite and its electrochemical properties

    Science.gov (United States)

    Kalubarme, Ramchandra S.; Kim, Yong-Han; Park, Chan-Jin

    2013-09-01

    A carbon nanotube (CNT)/cerium oxide composite was prepared by a one-pot hydrothermal reaction in the presence of KOH and capping agent polyvinylpyrrolidone. The nanocomposite displayed pronounced capacitive behaviour with very small diffusion resistance. The electrochemical performance of the composite electrode in a symmetric supercapacitor displayed a high energy density of 35.9 Wh kg-1 corresponding to a specific capacitance of 289 F g-1. These composite electrodes also demonstrated a long cycle life with better capacity retention.

  12. Cerium regulates expression of alternative methanol dehydrogenases in Methylosinus trichosporium OB3b.

    Science.gov (United States)

    Farhan Ul Haque, Muhammad; Kalidass, Bhagyalakshmi; Bandow, Nathan; Turpin, Erick A; DiSpirito, Alan A; Semrau, Jeremy D

    2015-11-01

    Methanotrophs have multiple methane monooxygenases that are well known to be regulated by copper, i.e., a "copper switch." At low copper/biomass ratios the soluble methane monooxygenase (sMMO) is expressed while expression and activity of the particulate methane monooxygenase (pMMO) increases with increasing availability of copper. In many methanotrophs there are also multiple methanol dehydrogenases (MeDHs), one based on Mxa and another based on Xox. Mxa-MeDH is known to have calcium in its active site, while Xox-MeDHs have been shown to have rare earth elements in their active site. We show here that the expression levels of Mxa-MeDH and Xox-MeDH in Methylosinus trichosporium OB3b significantly decreased and increased, respectively, when grown in the presence of cerium but the absence of copper compared to the absence of both metals. Expression of sMMO and pMMO was not affected. In the presence of copper, the effect of cerium on gene expression was less significant, i.e., expression of Mxa-MeDH in the presence of copper and cerium was slightly lower than in the presence of copper alone, but Xox-MeDH was again found to increase significantly. As expected, the addition of copper caused sMMO and pMMO expression levels to significantly decrease and increase, respectively, but the simultaneous addition of cerium had no discernible effect on MMO expression. As a result, it appears Mxa-MeDH can be uncoupled from methane oxidation by sMMO in M. trichosporium OB3b but not from pMMO. PMID:26296730

  13. Development of Stable Cerium Zirconium Mixed Oxide Nanoparticle Additive for Emission Reduction in Biodiesel Blends

    Directory of Open Access Journals (Sweden)

    Sajith V

    2015-06-01

    Full Text Available Harmful emissions associated with the use of biodiesel is a serious issue and various fuel additives are being used for the reduction of emissions as well as for the improvement of engine performance. Use of cerium oxide nanoparticles as fuel additive is one of the methods for the reduction of emissions, due to its peculiar redox functionality and oxygen buffering capability. Doping of ceria with transition metals such as zirconium improves its Oxygen storage capacity and thermal stability, thereby enhancing simultaneous oxidation and reduction reactions. The present work focuses on the development of cerium zirconium mixed oxide nanoparticle based additive for the reduction of emissions from diesel engine fuelled with biodiesel - diesel blends. Cerium zirconium mixed oxide was synthesized by means of co precipitation method. The stability of the nanofluids was improved by the addition of surfactant, namely Oleic acid. The optimum concentration of surfactant was determined based on estimation of critical micelle concentration, by means of standard tests. Stability of catalytic nanoparticle in fuel was evaluated from the measurement of Zeta potential. Various properties were determined as per ASTM standards to investigate the effect of the nanoparticles on fuel properties. Addition of catalytic nanoparticle in diesel - biodiesel blends does not significantly affect the fuel properties. Engine performance and emission tests were conducted on single cylinder diesel engine to assess the potential of synthesized nanofuel and 15% average reduction of NO emissions was observed for B5 and B10 blends with 15 ppm of catalytic nanoparticle concentration.

  14. The role of hydrogen peroxide in the deposition of cerium-based conversion coatings

    International Nuclear Information System (INIS)

    Cerium-based conversion coatings are progressing as an effective alternative to hazardous chromate-based systems used in the treatment of metal surfaces. However, there is still considerable debate over the mechanism by which these coatings are formed. Here, titrations of cerium-based conversion coating solutions were carried out in order to model the reactions that occur at the metal-solution interface during coating, with a particular emphasis on investigating the role of hydrogen peroxide (H2O2). The titration curves obtained support the proposed formation of Ce(III) peroxo complexes such as Ce(H2O2)3+ as an initial step, followed by deprotonation, oxidation and precipitation to form peroxo-containing Ce(IV) species such as Ce(IV)(O2)(OH)2. The precipitates resulting from titrations were characterised by Raman spectroscopy, X-ray diffraction and thermogravimetric analysis, confirming the presence of peroxo bonds, and nano-sized CeO2 crystallites that decreased in size with increasing H2O2 concentration. Characterisation of cerium conversion coatings on aluminium alloy surfaces confirmed the presence of peroxo species in the coatings, thereby supporting the titration model

  15. Cerium, gallium and zinc containing mesoporous bioactive glass coating deposited on titanium alloy

    Science.gov (United States)

    Shruti, S.; Andreatta, F.; Furlani, E.; Marin, E.; Maschio, S.; Fedrizzi, L.

    2016-08-01

    Surface modification is one of the methods for improving the performance of medical implants in biological environment. In this study, cerium, gallium and zinc substituted 80%SiO2-15%CaO-5%P2O5 mesoporous bioactive glass (MBG) in combination with polycaprolactone (PCL) were coated over Ti6Al4 V substrates by dip-coating method in order to obtain an inorganic-organic hybrid coating (MBG-PCL). Structural characterization was performed using XRD, nitrogen adsorption, SEM-EDXS, FTIR. The MBG-PCL coating uniformly covered the substrate with the thickness found to be more than 1 μm. Glass and polymer phases were detected in the coating along with the presence of biologically potent elements cerium, gallium and zinc. In addition, in vitro bioactivity was investigated by soaking the coated samples in simulated body fluid (SBF) for up to 30 days at 37 °C. The apatite-like layer was monitored by FTIR, SEM-EDXS and ICP measurements and it formed in all the samples within 15 days except zinc samples. In this way, an attempt was made to develop a new biomaterial with improved in vitro bioactive response due to bioactive glass coating and good mechanical strength of Ti6Al4 V alloy along with inherent biological properties of cerium, gallium and zinc.

  16. Microstructure and electrochemical behavior of cerium conversion coating modified with silane agent on magnesium substrates

    Science.gov (United States)

    Lei, Li; Shi, Jing; Wang, Xin; Liu, Dan; Xu, Haigang

    2016-07-01

    The cerium conversion coating with and without different concentrations of silane agent bis-(γ-triethoxysilylpropyl)-tetrasulfide (BTESPT) modification is obtained on magnesium alloys. Detailed properties of the coatings and the role of BTESPT as an additive are studied and followed with careful discussion. The coating morphology, wettability, chemical composition and corrosion resistance are characterized by scanning electronic microscope (SEM), water contact-angle, X-ray photoelectron spectroscopy (XPS), potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). The electrochemical behavior of the coatings is investigated using EIS. The results indicate that the coating morphology and composition can be controlled by changing silane concentration. The combination of cerium ions and silane molecules could promote the formation of more homogenous and higher hydrophobic coating. The coating turns to be more compact and the adhesive strength between the coating and the magnesium substrate are strongly improved with the formation of Sisbnd Osbnd Si and Sisbnd Osbnd M chemical bonds. The optimum corrosion resistance of the coating in the corrosive media is obtained by 25 ml L-1 BTESPT modification. This whole study implies that the cerium conversion coating modified with certain silane agent deserves cautiousness before its application for corrosion resistance.

  17. Effect of cerium oxide addition on electrical properties of ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, D.M. [National Research Center, Dokki, Giza (Egypt). Dept. of Ceramics; Mounir, M. [Dept. of Physics, Cairo Univ., Giza (Egypt); Mahgoub, A.S. [Cairo Univ., Giza (Egypt). Dept. of Chemistry; Turky, G. [Dept. of Physics, National Research Center, Dokki, Giza (Egypt); El-Desouky, O.A. [Cer. Cleopatra Co., Ramadan City (Egypt)

    2002-07-01

    Mixtures of ZnO and Ce{sub 6} O{sub 11} as additive were prepared by solid state reaction from the calcined oxides with the following proportions: 0.03, 0.08, 0.1, 0.2 and 0.4 mole. Disc specimens 1.2 cm 5 cm in diameter and 0.3 cm thickness were processed under a force of 70 kN and fired at 1150 C/ 30 minutes. XRD revealed the presence of limited solid solution of cerium in ZnO, as evident from the shift in the peaks [0.03-0.04 A ] up to 0.1 mole addition and remains constant. SEM revealed the presence of inter-granular phase. EDAX showed it to be a mixture of ZnO and Ce{sub 6}O{sub 11}. Also cerium was detected in the ZnO grains confirming the XRD results. RCL circuit was used to measure the capacitance and resistance at different frequencies at room temperature. The dielectric constant and conductivity were calculated. The change in resistivity with temperature was followed up to 523 K. The change in dielectric strength with temperature at spot frequency of 10 kHz is demonstrated. The electrical conductivity was found to increase with the proportion of cerium oxide up to 0.2 mole then decreased. (orig.)

  18. Laser ablated plasma plume diagnostics of cerium oxide: effect of oxygen partial pressure

    International Nuclear Information System (INIS)

    This paper describes the spatial and temporal investigation of laser ablated plasma plume of cerium oxide target using Langmuir probe to measure the plasma parameters. Cerium oxide target was ablated using a KrF (λ ∼ 248 nm) gas laser at an energy of 300 mJ per pulse. Experimental studies confirmed that oxygen partial pressure of 2 x 10-2 mbar is sufficient enough to get good quality films of cerium oxide. At this pressure, plume was diagnosed for their spatial and temporal behaviour. The tungsten probe tip was inserted along the length of the plasma to collect the ions and electrons effectively. A thin probe tip (about 0.4 mm diameter) was used to avoid plasma perturbation during measurements. A variable voltage was applied to the tip and corresponding current due to electrons and ions was collected. Spatial distribution was investigated at a regular interval of 15 mm from the target up maximum distance 45 mm and the temporal behaviour was recorded in the range of 0 to 50 μS with an interval of 0.5 μS. The ion and average electron density are found to be maximum at 30 mm from the target position and the plasma current of ceria is found to be maximum at 22 μS. (author)

  19. Cerium Modified Pillared Montmorillonite Supported Cobalt Catalysts for Fischer Tropsch Synthesis

    International Nuclear Information System (INIS)

    Fischer-Tropsch (FT) synthesis was accomplished over Al-pillared Montmorillonite supported 20 wt% Co modified with different weight% of cerium catalysts. These catalysts were prepared by impregnation method while structural characterizations of the prepared samples were performed by XRD, TPR, NH/sub 3/TPD, TGA, BET, XRF and SEM techniques. The Fischer Tropsch reaction was studied in fixed bed micro catalytic reactor at temperature range of 220, 260 and 275 degree C and at different pressure (1, 5 and 10 bars). From the activity results, it was found that by pillaring NaMMT with Al higher catalytic activity and lower methane selectivity of NaMMT was achieved. Furthermore, the results of FT synthesis reaction revealed that cerium incorporation increased the dispersion of Co/sub 3/O/sub 4/ on the surface and consequently resulted in enhanced catalytic activity. Additionally, the C/sub 5/-C/sub 12/ hydrocarbons and methane selectivity increased while C/sub 22+/ hydrocarbons selectivity was decreased over cerium modified catalysts. Higher reaction temperature (>220 degree C) resulted in significant enhancement in CO conversion and methane selectivity. Though, increase in pressure from 1 to 10 bars eventually resulted in increase in C/sub 5+/ hydrocarbons and decrease in methane and C/sub 2/-C/sub 5/ hydrocarbons selectivity. (author)

  20. Cerium valence change in the solid solutions Ce(Rh1-xRux)Sn

    International Nuclear Information System (INIS)

    The solid solutions Ce(Rh1-xRux)Sn were investigated by means of susceptibility measurements, specific heat, electrical resistivity, X-ray absorption spectroscopy (XAS), and 119Sn Moessbauer spectroscopy. Magnetic measurements as well as XAS data show a cerium valence change in dependence on the ruthenium content. Higher ruthenium content causes an increase from 3.22 to 3.45 at 300 K. Furthermore χ and χ-1 data indicate valence fluctuation for cerium as a function of temperature. For example, Ce(Rh0.8Ru0.2)Sn exhibits valence fluctuations between 3.42 and 3.32 in the temperature range of 10 to 300 K. This could be proven by using the interconfiguration fluctuation (ICF) model introduced by Sales and Wohlleben. Cerium valence change does not influence the tin atoms as proven by 119Sn Moessbauer spectroscopy, but it influences the electrical properties. Ce(Rh0.9Ru0.1)Sn behaves like a typical valence fluctuating compound, and higher ruthenium content causes an increase of the metallic behavior. (orig.)

  1. Thermal decomposition study of uranyl nitrate and cerium hydroxide in a spray dryer

    International Nuclear Information System (INIS)

    A study, in a spray dryer system based on drying and thermal decomposition of uranyl nitrate solutions aiming the production of uranium trioxide adequate for the use in posterior steps of reduction and hydro fluorination in nuclear fuel cycle; and cerium hydroxide suspensions for the production of cerium oxide with high surface area is presented. Thus, the project and construction of a countercurrent spray dryer was elaborated for capacity of 10 Kg U O3/h and 3,5 k Ce O2/h. The methodology used in these experiments consisted in the analysis of several parameters (concentration and flow rate of the feed, atomization pressure and inlet temperature of the dryer) over the physical and chemical properties of the products. Using the obtained results, with the help of a mathematical model, it was developed the project of a continuous pilot unity for the production of uranium trioxide or cerium oxide, with capacity of 20 Kg U O3/h or 10 Kg Ce O2/h, respectively. (author)

  2. Effect of coating parameters on the microstructure of cerium oxide conversion coatings

    International Nuclear Information System (INIS)

    The microstructure and morphology of cerium oxide conversion coatings prepared under different deposition conditions were characterized by transmission electron microscopy (TEM). The coatings were formed by a spontaneous reaction between a water-based solution containing CeCl3 and aluminum alloy 7075-T6 substrates. Microstructural characterization was performed to determine the crystallinity of the coatings and to obtain a better understanding of the deposition parameters on coating microstructure. The results of TEM imaging and electron diffraction analysis indicated that the as-deposited coating was composed of nanocrystalline particles of a previously unreported cerium compound. The particles of the coatings produced using glycerol as an additive were found to be much finer than those of the coatings prepared in the absence of glycerol. This indicates that glycerol may act as a grain refiner and/or growth inhibitor during coating deposition. After deposition, the coated panels were treated for 5 min in a phosphate sealing solution. The sealing treatment converted the as-deposited coating into hydrated cerium phosphate. Panels coated from solutions containing no glycerol followed by phosphate sealing performed poorly in salt fog tests. With glycerol addition, the corrosion resistance of the coatings that were phosphate sealed improved considerably, achieving an average passing rate of 85%

  3. Basic study on decontamination of TRU waste with cerium-mediated electrolytic oxidation method

    International Nuclear Information System (INIS)

    It is important to decrease the radioactivity of transuranium (TRU) waste arising from reprocessing plants by the decontamination for its disposal. In order to dispose TRU waste safely and rationally, a decontamination technology is required to be developed. For this purpose, the Japan Atomic Energy Agency has conducted a basic study focusing on the cerium-mediated electrolytic oxidation (CeMEX) method. In this study, two series of tests were performed to confirm the sufficient corrosion rate for the decontamination of metallic waste with the CeMEX method. One is the pre-corrosion test to survey an optimum solution condition for the generation of cerium(IV) ion under different conditions in concentration of cerium(III) ion and nitric acid. The other is the corrosion test to evaluate the corrosion rate of stainless steel as simulating waste under the optimized solution condition. It was confirmed that the average corrosion rate of stainless steel was 3.3 μm/h for 90 hours. This means that the decontamination can be completed within 6 hours and that the decontamination solution can be recycled 15 times, assuming that the decontamination to the clearance-level needs corrosion depth of 20 μm. From the results, the CeMEX method is sufficiently applicable to the decontamination of TRU waste. (author)

  4. Cerium Biomagnification in a Terrestrial Food Chain: Influence of Particle Size and Growth Stage.

    Science.gov (United States)

    Majumdar, Sanghamitra; Trujillo-Reyes, Jesica; Hernandez-Viezcas, Jose A; White, Jason C; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L

    2016-07-01

    Mass-flow modeling of engineered nanomaterials (ENMs) indicates that a major fraction of released particles partition into soils and sediments. This has aggravated the risk of contaminating agricultural fields, potentially threatening associated food webs. To assess possible ENM trophic transfer, cerium accumulation from cerium oxide nanoparticles (nano-CeO2) and their bulk equivalent (bulk-CeO2) was investigated in producers and consumers from a terrestrial food chain. Kidney bean plants (Phaseolus vulgaris var. red hawk) grown in soil contaminated with 1000-2000 mg/kg nano-CeO2 or 1000 mg/kg bulk-CeO2 were presented to Mexican bean beetles (Epilachna varivestis), which were then consumed by spined soldier bugs (Podisus maculiventris). Cerium accumulation in plant and insects was independent of particle size. After 36 days of exposure to 1000 mg/kg nano- and bulk-CeO2, roots accumulated 26 and 19 μg/g Ce, respectively, and translocated 1.02 and 1.3 μg/g Ce, respectively, to shoots. The beetle larvae feeding on nano-CeO2 exposed leaves accumulated low levels of Ce since ∼98% of Ce was excreted in contrast to bulk-CeO2. However, in nano-CeO2 exposed adults, Ce in tissues was higher than Ce excreted. Additionally, Ce content in tissues was biomagnified by a factor of 5.3 from the plants to adult beetles and further to bugs. PMID:26690677

  5. Synthesis and Characterization of Cerium Doped Titanium Catalyst for the Degradation of Nitrobenzene Using Visible Light

    Directory of Open Access Journals (Sweden)

    Padmini Ellappan

    2014-01-01

    Full Text Available Cerium doped catalyst was synthesized using Titanium isopropoxide as the Titanium source. The metal doped nanoparticles semiconductor catalyst was prepared by sol-sol method with the sol of Cerium. The synthesized catalyst samples were characterized by powder X-ray diffraction, BET surface area, thermogravimetric analysis (TGA, scanning electron microscopy (SEM, and UV-vis diffuse reflectance measurements (DRS and compared with undoped TiO2 catalyst. The photocatalytic activity of the sample was investigated for the decomposition of nitrobenzene (NB using visible light as the artificial light source. Cerium doped catalyst was found to have better degradation of nitrobenzene owing to its shift in the band gap from UV to visible region as compared to undoped TiO2 catalyst. The operational parameters were optimized with catalyst dosage of 0.1 g L−1, pH of 9, and light intensity of 500 W. The degradation mechanism followed the Langmuir Hinshelwood kinetic model with the rate constant depending nonlinearly on the operational parameters as given by the relationship Kapp (theoretical = 2.29 * 10−4 * Intensity0.584 * Concentration−0.230 * Dosage0.425 * pH0.336.

  6. Specifics of new phase crystal nucleation during isostructural γ↔α transformation in cerium

    International Nuclear Information System (INIS)

    Specifics of new phase nucleation and subsequent growth under γ-α-transformation in cerium near the surface of the sample is suggested. It is assumed that this specifics can effect mechanical behaviour of a laminar sample under transition at three-point bend. Measurement of deflection of cerium samples at the sensitivity of ∼ 10-6 m at three-point loading was carried out in the 4.2-300 K temperature range at p=10-4 GPa as well as in a chamber of high pressure (in the range of hydrostatic pressures up to 1.0 GPa at T=293 K). It is shown that the effects of change in the form experimentally discovered in the given paper and accompanying isostructural γ-α-transformation in cerium may be explained by the fact that crystal nucleation of γ- and α-phases differing by the volume takes place mainly from the surface of the sample and not in its volume

  7. Chromium VI adsorption on cerium oxide nanoparticles and morphology changes during the process

    International Nuclear Information System (INIS)

    In this study, suspended cerium oxide nanoparticles stabilized with hexamethylenetetramine were used for the removal of dissolved chromium VI in pure water. Several concentrations of adsorbent and adsorbate were tested, trying to cover a large range of possible real conditions. Results showed that the Freundlich isotherm represented well the adsorption equilibrium reached between nanoparticles and chromium, whereas adsorption kinetics could be modeled by a pseudo-second-order expression. The separation of chromium-cerium nanoparticles from the medium and the desorption of chromium using sodium hydroxide without cerium losses was obtained. Nanoparticles agglomeration and morphological changes during the adsorption-desorption process were observed by TEM. Another remarkable result obtained in this study is the low toxicity in the water treated by nanoparticles measured by the Microtox commercial method. These results can be used to propose this treatment sequence for a clean and simple removal of drinking water or wastewater re-use when a high toxicity heavy metal such as chromium VI is the responsible for water pollution.

  8. Cerium-based coating for enhancing the corrosion resistance of bio-degradable Mg implants

    International Nuclear Information System (INIS)

    Recently there has been interest in employing degradable metallic implants for internal fixation in bone fracture healing. The major purpose of using degradable implants is to avoid a second surgery for implant removal when bone healing has completed. However, the corrosion rate of Mg in vivo is too high. Thus increasing the corrosion resistance of Mg is the key problem to address in the development of degradable Mg implants. One possible route is by way of surface treatment, which would lower the corrosion rate at the initial phase of bone healing, the period during which the implant provides mechanical support for the broken bone. In the present study cerium oxide coating was prepared on pure Mg by cathodic deposition in cerium nitrate solution followed by hydrothermal treatment. The coated samples were characterized by SEM, EDS and XRD. The corrosion resistance in Hanks' solution (a simulated body fluid) was studied using polarization method and electrochemical impedance spectroscopy (EIS). The corrosion resistance of cerium oxide coated Mg in Hanks' solution at 37 deg. C and pH 7.4 was higher than that of bare Mg by about two orders of magnitude.

  9. Influence of agglomeration of cerium oxide nanoparticles and speciation of cerium(III) on short term effects to the green algae Chlamydomonas reinhardtii

    International Nuclear Information System (INIS)

    Highlights: • Phosphate-dispersed CeO2 NP did not affect photosynthetic yield in C. reinhardtii. • Agglomerated CeO2 NP slightly decreased photosynthetic yield. • Cerium(III) was shown to affect photosynthetic yield and intracellular ROS level. • Slight effects of CeO2 NP were caused by dissolved Ce3+ ions present in suspensions. • Wild type and cell wall free mutant of C. reinhardtii showed the same sensitivity. - Abstract: Cerium oxide nanoparticles (CeO2 NP) are increasingly used in industrial applications and may be released to the aquatic environment. The fate of CeO2 NP and effects on algae are largely unknown. In this study, the short term effects of CeO2 NP in two different agglomeration states on the green algae Chlamydomonas reinhardtii were examined. The role of dissolved cerium(III) on toxicity, its speciation and the dissolution of CeO2 NP were considered. The role of cell wall of C. reinhardtii as a barrier and its influence on the sensitivity to CeO2 NP and cerium(III) was evaluated by testing both, the wild type and the cell wall free mutant of C. reinhardtii. Characterization showed that CeO2 NP had a surface charge of ∼0 mV at physiological pH and agglomerated in exposure media. Phosphate stabilized CeO2 NP at pH 7.5 over 24 h. This effect was exploited to test CeO2 NP dispersed in phosphate with a mean size of 140 nm and agglomerated in absence of phosphate with a mean size of 2000 nm. The level of dissolved cerium(III) in CeO2 NP suspensions was very low and between 0.1 and 27 nM in all tested media. Exposure of C. reinhardtii to Ce(NO3)3 decreased the photosynthetic yield in a concentration dependent manner with EC50 of 7.5 ± 0.84 μM for wild type and EC50 of 6.3 ± 0.53 μM for the cell wall free mutant. The intracellular level of reactive oxygen species (ROS) increased upon exposure to Ce(NO3)3 with effective concentrations similar to those inhibiting photosynthesis. The agglomerated CeO2 NP caused a slight decrease of

  10. Influence of agglomeration of cerium oxide nanoparticles and speciation of cerium(III) on short term effects to the green algae Chlamydomonas reinhardtii

    Energy Technology Data Exchange (ETDEWEB)

    Röhder, Lena A. [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); ETH-Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zürich 8092 (Switzerland); Brandt, Tanja [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); Sigg, Laura [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); ETH-Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zürich 8092 (Switzerland); Behra, Renata, E-mail: Renata.behra@eawag.ch [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland)

    2014-07-01

    Highlights: • Phosphate-dispersed CeO₂ NP did not affect photosynthetic yield in C. reinhardtii. • Agglomerated CeO₂ NP slightly decreased photosynthetic yield. • Cerium(III) was shown to affect photosynthetic yield and intracellular ROS level. • Slight effects of CeO₂ NP were caused by dissolved Ce³⁺ ions present in suspensions. • Wild type and cell wall free mutant of C. reinhardtii showed the same sensitivity. - Abstract: Cerium oxide nanoparticles (CeO₂ NP) are increasingly used in industrial applications and may be released to the aquatic environment. The fate of CeO₂ NP and effects on algae are largely unknown. In this study, the short term effects of CeO₂ NP in two different agglomeration states on the green algae Chlamydomonas reinhardtii were examined. The role of dissolved cerium(III) on toxicity, its speciation and the dissolution of CeO₂ NP were considered. The role of cell wall of C. reinhardtii as a barrier and its influence on the sensitivity to CeO₂ NP and cerium(III) was evaluated by testing both, the wild type and the cell wall free mutant of C. reinhardtii. Characterization showed that CeO₂ NP had a surface charge of ~0 mV at physiological pH and agglomerated in exposure media. Phosphate stabilized CeO₂ NP at pH 7.5 over 24 h. This effect was exploited to test CeO₂ NP dispersed in phosphate with a mean size of 140 nm and agglomerated in absence of phosphate with a mean size of 2000 nm. The level of dissolved cerium(III) in CeO₂ NP suspensions was very low and between 0.1 and 27 nM in all tested media. Exposure of C. reinhardtii to Ce(NO₃)₃ decreased the photosynthetic yield in a concentration dependent manner with EC₅₀ of 7.5 ± 0.84 μM for wild type and EC₅₀ of 6.3 ± 0.53 μM for the cell wall free mutant. The intracellular level of reactive oxygen species (ROS) increased upon exposure to Ce(NO₃)₃ with effective concentrations similar to those inhibiting photosynthesis. The agglomerated Ce

  11. A totally phosphine-free synthesis of metal telluride nanocrystals by employing alkylamides to replace alkylphosphines for preparing highly reactive tellurium precursors.

    Science.gov (United States)

    Yao, Dong; Liu, Yi; Zhao, Wujun; Wei, Haotong; Luo, Xintao; Wu, Zhennan; Dong, Chunwei; Zhang, Hao; Yang, Bai

    2013-10-21

    Despite the developments in the wet chemical synthesis of high-quality semiconductor nanocrystals (NCs) with diverse elemental compositions, telluride NCs are still irreplaceable materials owing to their excellent photovoltaic and thermoelectric performances. Herein we demonstrate the dissolution of elemental tellurium (Te) in a series of alkylamides by sodium borohydride (NaBH4) reduction at relatively low temperature to produce highly reactive precursors for hot-injection synthesis of telluride NCs. The capability to tune the reactivity of Te precursors by selecting injection temperature permits control of NC size over a broad range. The current preparation of Te precursors is simple, economical, and totally phosphine-free, which will promote the commercial synthesis and applications of telluride NCs. PMID:24056800

  12. Evaluation of mechanically treated cerium (IV) oxides as corrosion inhibitors for galvanized steel

    International Nuclear Information System (INIS)

    The use of cerium salts as corrosion inhibitors for hot dip galvanized steel has been object of a numerous studies in the last few years. The role of cerium ions as corrosion inhibitors was proved: cerium is able to block the cathodic sites of the metal, forming insoluble hydroxides and oxides on the zinc surface. This fact leads to a dramatic decrease of the cathodic current densities and, therefore, to a reduction the overall corrosion processes. On the other hand, the potential of cerium oxides as corrosion inhibitors was also proposed. However, the real effectiveness of this kind of anticorrosive pigments has not been clarified yet. In this work cerium (IV) oxides are considered as corrosion inhibitors for galvanized steel. The corrosion inhibition mechanism of mechanically treated (milled) CeO2 alone and in combination with milled SiO2 nanoparticles was investigated. For this purpose milled CeO2, CeO2 and SiO2 milled together and milled SiO2 particles were studied as corrosion inhibitors in water solution. Therefore, the different mechanically treated particles were dispersed in 0.1 M NaCl solution to test their effectiveness as corrosion inhibitors for galvanized steel. The galvanized steel was immersed in the different solutions and the corrosion inhibition efficiency of the different particles was measured by means of electrochemical techniques. For this purpose, electrochemical impedance spectroscopy (EIS) measurements were carried out, monitoring the evolution of the corrosion processes occurring at the metal surface with the immersion time in the solution. The effect of the different pigments was also investigated by carrying out anodic and cathodic polarization measurements. The polarization curves were acquired under conditions of varied pH. The experimental measurements suggest that the mechanical treatment performed on the SiO2 and CeO2 particles promote the formation of an effective corrosion pigment. The tests evidence also the beneficial effect of

  13. Tellurides, selenides and Bi-mineral assemblages from the Río Narcea Gold Belt, Asturias, Spain: genetic implications in Cu-Au and Au skarns

    Science.gov (United States)

    Cepedal, A.; Fuertes-Fuente, M.; Martín-Izard, A.; González-Nistal, S.; Rodríguez-Pevida, L.

    2006-07-01

    Gold ores in skarns from the Río Narcea Gold Belt are associated with Bi-Te(-Se)-bearing minerals. These mineral assemblages have been used to compare two different skarns from this belt, a Cu-Au skarn (calcic and magnesian) from the El Valle deposit, and a Au-reduced calcic skarn from the Ortosa deposit. In the former, gold mineralization occurs associated with Cu-(Fe)-sulfides (chalcopyrite, bornite, chalcocite-digenite), commonly in the presence of magnetite. Gold occurs mainly as native gold and electrum. Au-tellurides (petzite, sylvanite, calaverite) are locally present; other tellurides are hessite, clausthalite and coloradoite. The Bi-bearing minerals related to gold are Bi-sulfosalts (wittichenite, emplectite, aikinite, bismuthinite), native bismuth, and Bi-tellurides and selenides (tetradymite, kawazulite, tsumoite). The speciation of Bi-tellurides with Bi/Te(Se + S) ≤ 1, the presence of magnetite and the abundance of precious metal tellurides and clausthalite indicate fO2 conditions within the magnetite stability field that locally overlap the magnetite-hematite buffer. In Ortosa deposit, gold essentially occurs as native gold and maldonite and is commonly related to pyrrhotite and to the replacement of löllingite by arsenopyrite, indicating lower fO2 conditions for gold mineralization than those for El Valle deposit. This fact is confirmed by the speciation of Bi-tellurides and selenides (hedleyite, joséite-B, joséite-A, ikunolite-laitakarite) with Bi/Te(+ Se + S) ≥ 1.

  14. The Lattice Compatibility Theory: Arguments for Recorded I-III-O2 Ternary Oxide Ceramics Instability at Low Temperatures beside Ternary Telluride and Sulphide Ceramics

    Directory of Open Access Journals (Sweden)

    K. Boubaker

    2013-01-01

    Full Text Available Some recorded behaviours differences between chalcopyrite ternary oxide ceramics and telluride and sulphides are investigated in the framework of the recently proposed Lattice Compatibility Theory (LCT. Alterations have been evaluated in terms of Urbach tailing and atomic valence shell electrons orbital eigenvalues, which were calculated through several approximations. The aim of the study was mainly an attempt to explain the intriguing problem of difficulties of elaborating chalcopyrite ternary oxide ceramics (I-III-O2 at relatively low temperatures under conditions which allowed crystallization of ternary telluride and sulphides.

  15. The effects of nanoparticle inclusions upon the microstructure and thermoelectric transport properties of bismuth telluride-based composites

    Science.gov (United States)

    Gothard, Nicholas Wesley

    Research into materials that have high efficiencies of thermoelectric heat-energy conversion has been at a plateau since the middle of the last century. During this time, efficiencies have been engineered high enough for several interesting niche applications but not high enough for widespread adaptation into traditional power generation or refrigeration technologies. The past decade has seen considerable advancement, as a number of theoretical works have suggested that lower dimensional structures could hold the key for enhanced efficiency, and several experiments have provided the proof of principle needed to inspire just such a research direction. The benefit of low dimensional structures for thermoelectric efficiency comes from both the potential enhancement of the electronic properties due to quantum confinement effects as well as from the potential for increased scattering of heat-carrying phonons. Widespread application of these principles for technological application requires the creation of composites of nanostructures that can be manufactured easily with dimensions on the bulk materials scale. A good starting point for such materials research is to manufacture composites of materials that are currently known to have high thermoelectric efficiencies by incorporating nanostructures into a bulk matrix. The goal of this project is to create nanocomposites using bismuth telluride, a compound known to have one of the highest thermoelectric efficiencies at room temperature, as a matrix material. Various methods of synthesizing sufficient quantities of bismuth telluride nanostructures were attempted, including pulsed laser vaporization, chemical vapor deposition, and solvothermal synthesis. The method of solvothermal synthesis was found to be the simplest approach for producing high yields of bismuth telluride nanostructures. In the initial stages of the project, cold pressing was tested as a means of compaction, but in the end a uniaxial hot pressing technique

  16. Chemiluminescence studies between aqueous phase synthesized mercaptosuccinic acid capped cadmium telluride quantum dots and luminol-H2O2

    Science.gov (United States)

    Kaviyarasan, Kulandaivelu; Anandan, Sambandam; Mangalaraja, Ramalinga Viswanathan; Asiri, Abdullah M.; Wu, Jerry J.

    2016-08-01

    Mercaptosuccinic acid capped Cadmium telluride quantum dots have been successfully synthesized via aqueous phase method. The products were well characterized by a number of analytical techniques, including FT-IR, XRD, HRTEM, and a corrected particle size analysis by the statistical treatment of several AFM measurements. Chemiluminescence experiments were performed to explore the resonance energy transfer between chemiluminescence donor (luminol-H2O2 system) and acceptor CdTe QDs. The combination of such donor and acceptor dramatically reduce the fluorescence while compared to pristine CdTe QDs without any exciting light source, which is due to the occurrence of chemiluminescence resonance energy transfer (CRET) processes.

  17. On the possible role played by tunnel recombination in the loss processes of excess current carriers in cadmium telluride

    Science.gov (United States)

    Novikov, G. F.; Marinin, A. A.; Gapanovich, M. V.; Rabenok, E. V.

    2010-05-01

    The microwave photoconductivity method was used to study the kinetics of the decay of current carriers generated by nitrogen laser pulses in n- and p-type cadmium telluride. The dependences of the shape and amplitude of photoresponse decays on temperature and light intensity were studied. Photoresponse decays contained "fast" (at t 50 ns) components. At long times, the dependence of photoresponse on the logarithm of time was linear. The shape of slow component decays was almost independent of temperature. The slow component of photoresponse decay could correspond to the loss process of entrapped charges in tunnel recombination.

  18. Characterization of cadmium manganese telluride (Cd1-xMnxTe) crystals grown by floating zone method

    Science.gov (United States)

    Hossain, A.; Gu, G. D.; Bolotnikov, A. E.; Camarda, G. S.; Cui, Y.; Gul, R.; Roy, U. N.; Yang, G.; Liu, T.; Zhong, R.; Schneeloch, J.; James, R. B.

    2014-09-01

    Recently, Cadmium Manganese Telluride (CMT) emerged as a promising material for roomtemperature X- and gamma-ray detectors. However, our studies revealed several material defects primarily related to growth processes that are impeding the production of large single crystals with high resistivity and high mobility-lifetime product. In this work, we characterized various defects in materials grown by the floating zone method, including twins, Te inclusions, and dislocations, using our unique facilities. We also fabricated detectors from selected CMT crystals and tested their performance. This paper discusses our detailed findings on the material's properties and the performance of fabricated CMT detectors.

  19. Internal Electric Field Investigations of a Cadmium Zinc Telluride Detector Using Synchrotron X-ray Mapping and Pockels Effect Measurements

    International Nuclear Information System (INIS)

    Cadmium zinc telluride (CZT) has remained a major focus of research due to its promising application as a room-temperature nuclear radiation detector material. Among the several parameters that substantially affect the detectors' performance, an important one is the distribution of the internal electric field. Brookhaven National Laboratory (BNL) employed synchrotron x-ray microscale mapping and measurements of the Pockels effect to investigate the distribution of the internal electric field in a CZT strip detector. Direct evidence that dislocations can distort the internal electric field of the detector was obtained. Furthermore, it was found that 'star' defects in the CZT crystal, possibly ascribed to dislocation loop punching, cause charge trapping.

  20. Chemiluminescence studies between aqueous phase synthesized mercaptosuccinic acid capped cadmium telluride quantum dots and luminol-H2O2.

    Science.gov (United States)

    Kaviyarasan, Kulandaivelu; Anandan, Sambandam; Mangalaraja, Ramalinga Viswanathan; Asiri, Abdullah M; Wu, Jerry J

    2016-08-01

    Mercaptosuccinic acid capped Cadmium telluride quantum dots have been successfully synthesized via aqueous phase method. The products were well characterized by a number of analytical techniques, including FT-IR, XRD, HRTEM, and a corrected particle size analysis by the statistical treatment of several AFM measurements. Chemiluminescence experiments were performed to explore the resonance energy transfer between chemiluminescence donor (luminol-H2O2 system) and acceptor CdTe QDs. The combination of such donor and acceptor dramatically reduce the fluorescence while compared to pristine CdTe QDs without any exciting light source, which is due to the occurrence of chemiluminescence resonance energy transfer (CRET) processes. PMID:27131144

  1. Nuclear myocardial perfusion imaging with a cadmium-zinc-telluride detector technique: optimized protocol for scan time reduction

    OpenAIRE

    Herzog, B A; Buechel, R R; Katz, R.; Brueckner, M; Husmann, L; Burger, I A; Pazhenkottil, A P; Valenta, I; Gaemperli, O; Treyer, V.; Kaufmann, P A

    2009-01-01

    We aimed at establishing the optimal scan time for nuclear myocardial perfusion imaging (MPI) on an ultrafast cardiac gamma-camera using a novel cadmium-zinc-telluride (CZT) solid-state detector technology. METHODS: Twenty patients (17 male; BMI range, 21.7-35.5 kg/m(2)) underwent 1-d (99m)Tc-tetrofosmin adenosine stress and rest MPI protocols, each with a 15-min acquisition on a standard dual-detector SPECT camera. All scans were immediately repeated on an ultrafast CZT camera over a 6-min a...

  2. Preparation of magnetron sputtered thin cerium oxide films with a large surface on silicon substrates using carbonaceous interlayers.

    Science.gov (United States)

    Dubau, Martin; Lavková, Jaroslava; Khalakhan, Ivan; Haviar, Stanislav; Potin, Valerie; Matolín, Vladimír; Matolínová, Iva

    2014-01-22

    The study focuses on preparation of thin cerium oxide films with a porous structure prepared by rf magnetron sputtering on a silicon wafer substrate using amorphous carbon (a-C) and nitrogenated amorphous carbon films (CNx) as an interlayer. We show that the structure and morphology of the deposited layers depend on the oxygen concentration in working gas used for cerium oxide deposition. Considerable erosion of the carbonaceous interlayer accompanied by the formation of highly porous carbon/cerium oxide bilayer systems is reported. Etching of the carbon interlayer with oxygen species occurring simultaneously with cerium oxide film growth is considered to be the driving force for this effect resulting in the formation of nanostructured cerium oxide films with large surface. In this regard, results of oxygen plasma treatment of a-C and CNx films are presented. Gradual material erosion with increasing duration of plasma impact accompanied by modification of the surface roughness is reported for both types of films. The CNx films were found to be much less resistant to oxygen etching than the a-C film. PMID:24372305

  3. Effects of cerium microalloying on the structure and properties of heat resistant steel of 4Kh4VMFS

    International Nuclear Information System (INIS)

    It is attempted to follow the peculiarity of structural-physical changes under high-temperature heating in subcritical region and on this base possible mechanisms of cerium effect on heat resistance increase of instrumental compos ition (0.42% C; 0.80% Si; 0.37% Mn; 4.0% Cr; 0.98% W; 1.55% Mo; 1.22% V; 0.01% Ca including the variant with 0.08% Ce) is chosen for investigation. Cerium microalloying is shown to result in advisability of precipitations in the 400-500 deg C tempering temperature range of cementite carbides on the boundaries and in the centre of matrix grains that is associated with liquating inhomogeneity by cerium and carbon. The noted inhomogeneity is levelled with the increase of tempering temperature above 500 deg C. Cerium inhibits the process of Fesub(α)-solid solution decomposition under tempering and its depletion by tungsten and molybdenum. Cerium microalloying of 4Kh4VMFS steel restrains carbide phase coagulation at high temperatures of tempering, it promotes inhibiting the recrystallization processes, assures increased fracture toughness

  4. Friction Consolidation Processing of n-Type Bismuth-Telluride Thermoelectric Material

    Science.gov (United States)

    Whalen, Scott; Jana, Saumyadeep; Catalini, David; Overman, Nicole; Sharp, Jeffrey

    2016-07-01

    Refined grain sizes and texture alignment have been shown to improve transport properties in bismuth-telluride (Bi2Te3) based thermoelectric materials. In this work we demonstrate a new approach, called friction consolidation processing (FCP), for consolidating Bi2Te3 thermoelectric powders into bulk form with a high degree of grain refinement and texture alignment. FCP is a solid-state process wherein a rotating tool is used to generate severe plastic deformation within the Bi2Te3 powder, resulting in a recrystallizing flow of material. Upon cooling, the far-from-equilibrium microstructure within the flow can be retained in the material. FCP was demonstrated on n-type Bi2Te3 feedstock powder having a -325 mesh size to form pucks with a diameter of 25.4 mm and thickness of 4.2 mm. Microstructural analysis confirmed that FCP can achieve highly textured bulk materials, with sub-micrometer grain size, directly from coarse feedstock powders in a single process. An average grain size of 0.8 μm was determined for regions of one sample and a multiple of uniform distribution (MUD) value of 15.49 was calculated for the (0001) pole figure of another sample. These results indicate that FCP can yield ultra-fine grains and textural alignment of the (0001) basal planes in Bi2Te3. ZT = 0.37 at 336 K was achieved for undoped stoichiometric Bi2Te3, which approximates literature values of ZT = 0.4-0.5. These results point toward the ability to fabricate bulk thermoelectric materials with refined microstructure and desirable texture using far-from-equilibrium FCP solid-state processing.

  5. Development and evaluation of polycrystalline cadmium telluride dosimeters for accurate quality assurance in radiation therapy

    Science.gov (United States)

    Oh, K.; Han, M.; Kim, K.; Heo, Y.; Moon, C.; Park, S.; Nam, S.

    2016-02-01

    For quality assurance in radiation therapy, several types of dosimeters are used such as ionization chambers, radiographic films, thermo-luminescent dosimeter (TLD), and semiconductor dosimeters. Among them, semiconductor dosimeters are particularly useful for in vivo dosimeters or high dose gradient area such as the penumbra region because they are more sensitive and smaller in size compared to typical dosimeters. In this study, we developed and evaluated Cadmium Telluride (CdTe) dosimeters, one of the most promising semiconductor dosimeters due to their high quantum efficiency and charge collection efficiency. Such CdTe dosimeters include single crystal form and polycrystalline form depending upon the fabrication process. Both types of CdTe dosimeters are commercially available, but only the polycrystalline form is suitable for radiation dosimeters, since it is less affected by volumetric effect and energy dependence. To develop and evaluate polycrystalline CdTe dosimeters, polycrystalline CdTe films were prepared by thermal evaporation. After that, CdTeO3 layer, thin oxide layer, was deposited on top of the CdTe film by RF sputtering to improve charge carrier transport properties and to reduce leakage current. Also, the CdTeO3 layer which acts as a passivation layer help the dosimeter to reduce their sensitivity changes with repeated use due to radiation damage. Finally, the top and bottom electrodes, In/Ti and Pt, were used to have Schottky contact. Subsequently, the electrical properties under high energy photon beams from linear accelerator (LINAC), such as response coincidence, dose linearity, dose rate dependence, reproducibility, and percentage depth dose, were measured to evaluate polycrystalline CdTe dosimeters. In addition, we compared the experimental data of the dosimeter fabricated in this study with those of the silicon diode dosimeter and Thimble ionization chamber which widely used in routine dosimetry system and dose measurements for radiation

  6. Spark plasma sintered bismuth telluride-based thermoelectric materials incorporating dispersed boron carbide

    Energy Technology Data Exchange (ETDEWEB)

    Williams, H.R., E-mail: hugo.williams@leicester.ac.uk [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Ambrosi, R.M. [Space Research Centre, Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Chen, K. [School of Engineering and Materials Science, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Friedman, U. [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Ning, H.; Reece, M.J. [School of Engineering and Materials Science, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Robbins, M.C.; Simpson, K. [European Thermodynamics Ltd., 8 Priory Business Park, Wistow Road, Kibworth LE8 0R (United Kingdom); Stephenson, K. [European Space Agency, ESTEC TEC-EP, Keplerlaan 1, 2201AZ Noordwijk (Netherlands)

    2015-03-25

    Highlights: • Nano-B{sub 4}C reinforced Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} p-type thermoelectric produced by SPS. • Addition of B{sub 4}C up to 0.2 vol% to SPS’d material has little effect on zT. • Vickers hardness improved by 27% by adding 0.2 vol% B{sub 4}C. • Fracture toughness of SPS material: K{sub IC} = 0.80 MPa m{sup 1/2} by SEVNB. • Mechanical properties much better than commercial directionally solidified material. - Abstract: The mechanical properties of bismuth telluride based thermoelectric materials have received much less attention in the literature than their thermoelectric properties. Polycrystalline p-type Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} materials were produced from powder using spark plasma sintering (SPS). The effects of nano-B{sub 4}C addition on the thermoelectric performance, Vickers hardness and fracture toughness were measured. Addition of 0.2 vol% B{sub 4}C was found to have little effect on zT but increased hardness by approximately 27% when compared to polycrystalline material without B{sub 4}C. The K{sub IC} fracture toughness of these compositions was measured as 0.80 MPa m{sup 1/2} by Single-Edge V-Notched Beam (SEVNB). The machinability of polycrystalline materials produced by SPS was significantly better than commercially available directionally solidified materials because the latter is limited by cleavage along the crystallographic plane parallel to the direction of solidification.

  7. Mercury-Cadmium-Telluride Focal Plane Array Performance Under Non-Standard Operating Conditions

    Science.gov (United States)

    Richardson, Brandon S.; Eastwood, Michael L.; Bruce, Carl F.; Green, Robert O.; Coles, J. B.

    2011-01-01

    This paper highlights a new technique that allows the Teledyne Scientific & Imaging LLC TCM6604A Mercury-Cadmium-Telluride (MCT) Focal Plane Array (FPA) to operate at room temperature. The Teledyne MCT FPA has been a standard in Imaging Spectroscopy since its creation in the 1980's. This FPA has been used in applications ranging from space instruments such as CRISM, M3 and ARTEMIS to airborne instruments such as MaRS and the Next Generation AVIRIS Instruments1. Precise focal plane alignment is always a challenge for such instruments. The current FPA alignment process results in multiple cold cycles requiring week-long durations, thereby increasing the risk and cost of a project. These alignment cycles are necessary because optimal alignment is approached incrementally and can only be measured with the FPA and Optics at standard operating conditions, requiring a cold instrument. Instruments using this FPA are normally cooled to temperatures below 150K for the MCT FPA to properly function. When the FPA is run at higher temperatures the dark current increases saturating the output. This paper covers the prospect of warm MCT FPA operation from a theoretical and experimental perspective. We discuss the empirical models and physical laws that govern MCT material properties and predict the optimal settings that will result in the best MCT PA performance at 300K. Theoretical results are then calculated for the proposed settings. We finally present the images and data obtained using the actual system with the warm MCT FPA settings. The paper concludes by emphasizing the strong positive correlation between the measured values and the theoretical results.

  8. Development and evaluation of polycrystalline cadmium telluride dosimeters for accurate quality assurance in radiation therapy

    International Nuclear Information System (INIS)

    For quality assurance in radiation therapy, several types of dosimeters are used such as ionization chambers, radiographic films, thermo-luminescent dosimeter (TLD), and semiconductor dosimeters. Among them, semiconductor dosimeters are particularly useful for in vivo dosimeters or high dose gradient area such as the penumbra region because they are more sensitive and smaller in size compared to typical dosimeters. In this study, we developed and evaluated Cadmium Telluride (CdTe) dosimeters, one of the most promising semiconductor dosimeters due to their high quantum efficiency and charge collection efficiency. Such CdTe dosimeters include single crystal form and polycrystalline form depending upon the fabrication process. Both types of CdTe dosimeters are commercially available, but only the polycrystalline form is suitable for radiation dosimeters, since it is less affected by volumetric effect and energy dependence. To develop and evaluate polycrystalline CdTe dosimeters, polycrystalline CdTe films were prepared by thermal evaporation. After that, CdTeO3 layer, thin oxide layer, was deposited on top of the CdTe film by RF sputtering to improve charge carrier transport properties and to reduce leakage current. Also, the CdTeO3 layer which acts as a passivation layer help the dosimeter to reduce their sensitivity changes with repeated use due to radiation damage. Finally, the top and bottom electrodes, In/Ti and Pt, were used to have Schottky contact. Subsequently, the electrical properties under high energy photon beams from linear accelerator (LINAC), such as response coincidence, dose linearity, dose rate dependence, reproducibility, and percentage depth dose, were measured to evaluate polycrystalline CdTe dosimeters. In addition, we compared the experimental data of the dosimeter fabricated in this study with those of the silicon diode dosimeter and Thimble ionization chamber which widely used in routine dosimetry system and dose measurements for radiation

  9. Spectroscopic, microscopic, and internal stress analysis in cadmium telluride grown by close-space sublimation

    Energy Technology Data Exchange (ETDEWEB)

    Manciu, Felicia S., E-mail: fsmanciu@utep.edu [Department of Physics, The University of Texas at El Paso, El Paso, TX 79968 (United States); Salazar, Jessica G. [Department of Physics, The University of Texas at El Paso, El Paso, TX 79968 (United States); Diaz, Aryzbe; Quinones, Stella A. [Department of Electrical and Computer Engineering, The University of Texas at El Paso, El Paso, TX 79968 (United States)

    2015-08-31

    High quality materials with excellent ordered structure are needed for developing photovoltaic and infrared devices. With this end in mind, the results of our research prove the importance of a detailed, comprehensive spectroscopic and microscopic analysis in assessing cadmium telluride (CdTe) characteristics. The goal of this work is to examine not only material crystallinity and morphology, but also induced stress in the deposit material. A uniform, selective growth of polycrystalline CdTe by close-space sublimation on patterned Si(111) and Si(211) substrates is demonstrated by scanning electron microscopy images. Besides good crystallinity of the samples, as revealed by both Raman scattering and Fourier transform infrared absorption investigations, the far-infrared transmission data also show the presence of surface optical phonon modes, which is direct evidence of confinement in such a material. The qualitative identification of the induced stress was achieved by performing confocal Raman mapping microscopy on sample surfaces and by monitoring the existence of the rock-salt and zinc-blende structural phases of CdTe, which were associated with strained and unstrained morphologies, respectively. Although the induced stress in the material is still largely due to the high lattice mismatch between CdTe and the Si substrate, the current results provide a direct visualization of its partial release through the relaxation effect at crystallite boundaries and of preferential growth directions of less strain. Our study, thus offers significant value for improvement of material properties, by targeting the needed adjustments in the growth processes. - Highlights: • Assessing the characteristics of CdTe deposited on patterned Si substrates • Proving the utility of confocal Raman microscopy in monitoring the induced stress • Confirming the partial stress release through the grain boundary relaxation effect • Demonstrating the phonon confinement effect in low

  10. Selenide and telluride glasses for mid-infrared bio-sensing

    Science.gov (United States)

    Cui, Shuo; Chahal, Radwan; Shpotyuk, Yaroslav; Boussard, Catherine; Lucas, Jacques; Charpentier, Frederic; Tariel, Hugues; Loréal, Olivier; Nazabal, Virginie; Sire, Olivier; Monbet, Valérie; Yang, Zhiyong; Lucas, Pierre; Bureau, Bruno

    2014-02-01

    Fiber Evanescent Wave Spectroscopy (FEWS) is an efficient way to collect optical spectra in situ, in real time and even, hopefully, in vivo. Thanks to selenide glass fibers, it is possible to get such spectra over the whole mid-infrared range from 2 to 12 μm. This working window gives access to the fundamental vibration band of most of biological molecules. Moreover selenide glasses are stable and easy to handle, and it is possible to shape the fiber and create a tapered sensing head to drastically increase the sensitivity. Within the past decades, numerous multi-disciplinary studies have been conducted in collaboration with the City Hospital of Rennes. Clinical trials have provided very promising results in biology and medicine which have led to the creation in 2011 of the DIAFIR Company dedicated to the commercialization of fiber-based infrared biosensors. In addition, new glasses based on tellurium only have been recently developed, initially in the framework of the Darwin mission led by the European Space Agency (ESA). These glasses transmit light further into the far-infrared and could also be very useful for medical applications in the near future. Indeed, they permit to reach the vibrational bands of biomolecules laying from 12 to 16 μm where selenide glasses do not transmit light anymore. However, while Se is a very good glass former, telluride glasses tend to crystallize easily due to the metallic nature of Te bonds. Hence, further work is under way to stabilize the glass composition for fibers drawing and to lower the optical losses for improving their sensitivity as bio-sensors.

  11. Cadmium zinc telluride based infrared interferometry for X-ray detection

    International Nuclear Information System (INIS)

    Cadmium Zinc Telluride (CZT) is a wide band gap semiconductor for room temperature radiation detection. The electro-optic Pockels effect of the material has been exploited in the past to study electric field non-uniformities and their consequence on conventional detector signals in CZT, by imaging the intensity distribution of infrared (IR) light transmitted through a device placed between crossed polarizers. Recently, quantitative monitoring of extremely high intensity neutron pulses through the change of transmitted IR intensity was demonstrated, offering the advantage to place sensitive electronics outside the measured radiation field. In this work, we demonstrate that X-ray intensity can be deduced directly from measuring the change in phase of 1550 nm laser light transmitted through a 7 × 7 × 2 mm3 CZT based Pockels cell in a simple Mach Zehnder interferometer. X-rays produced by a 50 kVp Mo X-ray tube incident on the CZT cathode surface placed at 7 mm distance cause a linearly increasing phase shift above 0.3 mA tube current, with 1.58 ± 0.02 rad per mA for an applied bias of 500 V across the 2 mm thick device. Pockels images confirm that the sample properties are in agreement with the literature, exhibiting electric field enhancement near the cathode under irradiation, which may cause the non-linearity at low X-ray tube anode current settings. The laser used to probe the X-ray intensity causes itself some space charge, whose spatial distribution does not seem to be exclusively determined by the incident laser position, i.e., charge carrier generation location, with respect to the electrodes

  12. Investigations of portable cadmium telluride (CdTe(Cl)) detectors for clinical studies with radioactive indicators

    International Nuclear Information System (INIS)

    The combination of small, portable γ-radiation-sensitive Cadmium Telluride (CdTE(Cl)) crystal detectors and portable solid state data storage memories makes it feasible to extend the measuring period in a number of clinical investigations based on the use of various radioisotopes and external detection. Blood sampling can be avoided in some cases. Continuous ambulatory monitoring of relevant physiological parameters is practicable, e.g. kidney function (GFR), left ventricular ejection fraction, subcutaneous blood flow, muscle blood flow and insulin absorption in diabetic patients. In the present methodological study the applicability of the 133-Xe washout technique to subcutaneous (s.c.) adipose tissue blood flow (SBF) has been investigated and adapted to the use of CdTe(Cl) detectors attached to the skin surface for the measurement of local 133-Xe-disappearance rate constants (k). Physical characterization of CdTe(Cl) detectors as γ-sensitive devices has been performed, and adequate counting sensitivities were found without detector energy-resolution properties. The CdTe(Cl) detectors are therefore suitable for single indicator studies. The measuring geometry of CdTe(Cl) detectors was studied and compared with that of stationary Sodium Iodide (NaI(Tl)) detectors in both phantom and in vivo investigations. The spatial properties of CdTe(Cl) detectors could to some extent be adjusted by pulse height discrimination and lead collimation. When long-term measurements were complicated by for instance physical activity of the patients, the small CdTe(Cl) detectors in general showed equal or better performance than the heavy and voluminous NaI(Tl) detectors. The free movement of the ambulatory patient and the avoidance of cable connections to stationary data-collecting systems gave improved possibilities for measurements of the relevant parameters. From this point of view, portable CdTe(Cl) detectors must be considered an important advance for radioactivity studies in

  13. Spectroscopic, microscopic, and internal stress analysis in cadmium telluride grown by close-space sublimation

    International Nuclear Information System (INIS)

    High quality materials with excellent ordered structure are needed for developing photovoltaic and infrared devices. With this end in mind, the results of our research prove the importance of a detailed, comprehensive spectroscopic and microscopic analysis in assessing cadmium telluride (CdTe) characteristics. The goal of this work is to examine not only material crystallinity and morphology, but also induced stress in the deposit material. A uniform, selective growth of polycrystalline CdTe by close-space sublimation on patterned Si(111) and Si(211) substrates is demonstrated by scanning electron microscopy images. Besides good crystallinity of the samples, as revealed by both Raman scattering and Fourier transform infrared absorption investigations, the far-infrared transmission data also show the presence of surface optical phonon modes, which is direct evidence of confinement in such a material. The qualitative identification of the induced stress was achieved by performing confocal Raman mapping microscopy on sample surfaces and by monitoring the existence of the rock-salt and zinc-blende structural phases of CdTe, which were associated with strained and unstrained morphologies, respectively. Although the induced stress in the material is still largely due to the high lattice mismatch between CdTe and the Si substrate, the current results provide a direct visualization of its partial release through the relaxation effect at crystallite boundaries and of preferential growth directions of less strain. Our study, thus offers significant value for improvement of material properties, by targeting the needed adjustments in the growth processes. - Highlights: • Assessing the characteristics of CdTe deposited on patterned Si substrates • Proving the utility of confocal Raman microscopy in monitoring the induced stress • Confirming the partial stress release through the grain boundary relaxation effect • Demonstrating the phonon confinement effect in low

  14. Effect of cerium additive and secondary phase analysis on Ag0.5Bi0.5TiO3 ceramics

    Indian Academy of Sciences (India)

    S Supriya; Antonio J Dos Santos-García; F Fernández-Martinez

    2016-02-01

    Cerium-doped silver bismuth titanate—Ag0.5Bi0.5TiO3 (ABT) ceramics have been synthesized by the high-temperature solid-state reaction method. The structure and elemental examination of the prepared ceramic was analysed by X-ray diffraction (XRD), Fourier transform infrared, scanning electron microscopy and energydispersive spectroscopy. XRD analysis showed the presence of pyrochlore structure and secondary phase when more than 5 mol% cerium was added. The impact of temperature on cerium-doped silver bismuth titanate samples was analysed by differential thermal analysis and differential scanning calorimetry. Cerium doping caused the flaky morphology comparing with undoped sample. The homogeneity of all the samples was discussed in detail by diffuse reflectance spectrum. This is the first time the reflection process is analysed for the cerium-doped ABT system to the best of our knowledge.

  15. Preparation of cerium-doped TiO2 film on 304 stainless steel and its bactericidal effect in the presence of sulfate-reducing bacteria (SRB)

    International Nuclear Information System (INIS)

    Cerium-doped TiO2 film with bactericidal activity was prepared on 304 stainless steel by a sol-gel process. The doped cerium ions were identified to have retarding effect on the phase transition from amorphous TiO2 to anatase TiO2. This effect was interpreted as the distortion of crystal lattice, due to the introduction of cerium ions into the crystal structure of TiO2. The absorption band edge of cerium-doped TiO2 film has a red shift compared with that of pure TiO2 film in UV-vis spectra. The films covered with sulfate-reducing bacteria (SRB) medium were exposed to sunlight for 6 h and the bactericidal efficiency was evaluated with most probable number technique. It was found that the bactericidal efficiency of cerium-doped TiO2 film and pure TiO2 film were 95% and 85%, respectively.

  16. Ab initio molecular dynamics study of the properties of cerium in liquid sodium at 1000 K temperature

    International Nuclear Information System (INIS)

    For liquid-sodium-cooled fast nuclear reactor systems, it is crucial to understand the behavior of lanthanides and other potential fission products in liquid sodium or other liquid metal solutions such as liquid cesium-sodium. In this study, we focus on lanthanide behavior in liquid sodium. Using ab initio molecular dynamics, we found that the solubility of cerium in liquid sodium at 1000 K was less than 0.78 at. %, and the diffusion coefficient of cerium in liquid sodium was calculated to be 5.57 × 10−9 m2/s. Furthermore, it was found that cerium in small amounts may significantly alter the heat capacity of the liquid sodium system. Our results are consistent with the experimental results for similar materials under similar conditions

  17. Ab initio molecular dynamics study of the properties of cerium in liquid sodium at 1000 K temperature

    Energy Technology Data Exchange (ETDEWEB)

    Samin, Adib; Li, Xiang; Zhang, Jinsuo [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19th Avenue, Columbus, Ohio 43210 (United States); Mariani, R. D. [Idaho National Laboratory, Materials and Fuels Complex, Idaho Falls, Idaho 83415 (United States); Unal, Cetin [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States)

    2015-12-21

    For liquid-sodium-cooled fast nuclear reactor systems, it is crucial to understand the behavior of lanthanides and other potential fission products in liquid sodium or other liquid metal solutions such as liquid cesium-sodium. In this study, we focus on lanthanide behavior in liquid sodium. Using ab initio molecular dynamics, we found that the solubility of cerium in liquid sodium at 1000 K was less than 0.78 at. %, and the diffusion coefficient of cerium in liquid sodium was calculated to be 5.57 × 10{sup −9} m{sup 2}/s. Furthermore, it was found that cerium in small amounts may significantly alter the heat capacity of the liquid sodium system. Our results are consistent with the experimental results for similar materials under similar conditions.

  18. Ab initio molecular dynamics study of the properties of cerium in liquid sodium at 1000 K temperature

    Science.gov (United States)

    Samin, Adib; Li, Xiang; Zhang, Jinsuo; Mariani, R. D.; Unal, Cetin

    2015-12-01

    For liquid-sodium-cooled fast nuclear reactor systems, it is crucial to understand the behavior of lanthanides and other potential fission products in liquid sodium or other liquid metal solutions such as liquid cesium-sodium. In this study, we focus on lanthanide behavior in liquid sodium. Using ab initio molecular dynamics, we found that the solubility of cerium in liquid sodium at 1000 K was less than 0.78 at. %, and the diffusion coefficient of cerium in liquid sodium was calculated to be 5.57 × 10-9 m2/s. Furthermore, it was found that cerium in small amounts may significantly alter the heat capacity of the liquid sodium system. Our results are consistent with the experimental results for similar materials under similar conditions.

  19. An application of secondary ion mass spectrometry (SIMS) in studies of internal contamination micro localization of cerium

    International Nuclear Information System (INIS)

    Secondary Ion Mass Spectrometry (SIMS) permits the detection of stable and radioactive elements in micro volume. Based on the ablation of specimens by ion bombardment, this mass spectrometry method allows a rapid assessment of trace elements in biological samples. Its resolving mass power provides an efficient analytical method and, in particular, it makes possible accurate isotopic ratio determination. In this work, a particular example is presented on the basis of results obtained as a result of analyses of duodenal tissue sections from rats contaminated with cerium. Tests were performed with SIMS to localize cerium in tissue sections obtained from rats 12, 24 and 48 hours after contamination with this element. In all specimens groups, cerium was found in apical region of micro villus, with the exception of those obtained 48 h after contamination. In this report, strengths and limitations of SIMS are pointed out as well as the potential of SIMS in biological research. (author)

  20. A study of quantitative chemical state analysis on cerium surface by using auger electron spectroscopy and factor analysis

    International Nuclear Information System (INIS)

    A reaction with oxygen during oxygen exposure to Cerium metal surface under ultra high vacuum condition and depth profiling on formed Cerium oxide layer were investigated in term of chemical state analysis by Auger electron spectroscopy (AES) and by factor analysis. Principal component analysis (PCA) on Ce NON Auger spectra suggested that three physically meaningful components existed from the analyzed data in both cases. After the PCA, three spectra were extracted from the data and these showed significant peak shape changes in each spectrum which were corresponding to different chemical states. In addition, the profiles constructed by factor analysis showed the chemical state changes on the Cerium metal surface during oxidation or chemical depth distributions in the oxide layer. (author)