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Sample records for anodic polarization

  1. Three-Dimensional Simulation of SOFC Anode Polarization Characteristics Based on Sub-Grid Scale Model

    OpenAIRE

    Kishimoto, Masashi; Iwai, Hiroshi; Saito, Motohiro; Yoshida, Hideo

    2011-01-01

    Three-dimensional numerical simulation of SOFC anode polarization is conducted with a structure obtained by a focused ion beam and scanning electron microscope (FIB-SEM). Electronic, ionic and gaseous transports with electrochemical reaction are considered. A sub-grid scale model is newly developed and effectively used to evaluate the transport flux in the porous structure. The proposed SGS model shows its potential to reasonably evaluate the transport flux considering the microstructure smal...

  2. Effect of anodic polarization on the free-floating parts at Pt/YSZ catalyst electrode

    Energy Technology Data Exchange (ETDEWEB)

    Toghan, Arafat, E-mail: arafat.toghan@yahoo.com [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, D-91058 Erlangen (Germany); Chemistry Department, Faculty of Science, South Valley University, 83523 Qena (Egypt); Institut für Physikalische Chemie und Elektrochemie, Leibniz-Universität Hannover, Callinstrasse 3-3a, D-30167 Hannover (Germany); Imbihl, R. [Institut für Physikalische Chemie und Elektrochemie, Leibniz-Universität Hannover, Callinstrasse 3-3a, D-30167 Hannover (Germany)

    2015-09-30

    Photoemission electron microscopy (PEEM) was used as spatially resolving method to explore the effect of electrochemical pumping with a positive voltage to porous platinum electrodes interfaced as working electrode to yttrium stabilized zirconia (YSZ). The experiments were conducted under UHV conditions (p ≈ 10{sup −9} mbar). In PEEM a uniform rapid darkening of the Pt surface was observed during anodic polarization followed by the appearance of bright spots on a dark background. The bright spots observed in PEEM images are due to zirconia reduction around electrically isolated Pt islands.

  3. Three-Dimensional Simulation of SOFC Anode Polarization Characteristics Based on Sub-Grid Scale Modeling of Microstructure

    OpenAIRE

    Kishimoto, Masashi; Iwai, Hiroshi; Saito, Motohiro; Yoshida, Hideo

    2012-01-01

    Three-dimensional numerical analysis of solid oxide fuel cell (SOFC) anode polarization is conducted with a microstructure obtained by a focused ion beam and scanning electron microscope (FIB-SEM). Electronic, ionic and gaseous transports with electrochemical reaction are considered in the porous anode. A sub-grid scale (SGS) model is newly developed and effectively used to consider the structural information whose characteristic scale is smaller than calculation grid size. The proposed SGS m...

  4. An in vitro investigation of the anodic polarization and capacitance behavior of 316-L stainless steel.

    Science.gov (United States)

    Sutow, E J; Pollack, S R; Korostoff, E

    1976-09-01

    Determinations were made of how the corrosion-resistant properties of the passive film on 316-L stainless steel are influenced by the material's mechanical and surface states, and the variable pH and PO2 conditions of the interstitial fluid. Cold-rolled and annealed specimens were surface-prepared, commercially and in the laboratory, respectively, as if for orthopedic implantation. Passive film behavior was studied by the anodic polarization and pulse-potentiostatic capacitance methods. The pH and PO2 of the Ringer's test solution were varied to include interstitial fluid values occurring postoperatively and onto recovery. The anodic polarization behavior of all specimens was found to be pH- and PO2-independent. Breakdown potentials of annealed specimens were 800-950 mV (SCE), in contrast to previously reported values of approximately 350 mV. This substantial increase is related to the influence of surface preparation and, in particular, to the optimization of electropolishing time which acts to produce a microscopically smooth surface, free of debris and disarrayed material. Capacitance behavior of annealed material for potentials greater than 400 mV was consistent with a model involving the entry of chloride and metal ions (mostly Fe) into the passive film. This entry is related to the onset of pitting. PMID:10307

  5. Sacrificial anode stability and polarization potential variation in a ternary Al-xZn-xMg alloy in a seawater-marine environment

    Science.gov (United States)

    Muazu, Abubakar; Aliyu, Yaro Shehu; Abdulwahab, Malik; Idowu Popoola, Abimbola Patricia

    2016-06-01

    In this paper, the effects of zinc (Zn) and magnesium (Mg) addition on the performance of an aluminum-based sacrificial anode in seawater were investigated using a potential measurement method. Anodic efficiency, protection efficiency, and polarized potential were the parameters used. The percentages of Zn and Mg in the anodes were varied from 2% to 8% Zn and 1% to 4% Mg. The alloys produced were tested as sacrificial anodes for the protection of mild steel in seawater at room temperature. Current efficiency as high as 88.36% was obtained in alloys containing 6% Zn and 1% Mg. The polarized potentials obtained for the coupled (steel/Al-based alloys) are as given in the Pourbaix diagrams, with steel lying within the immunity region/cathodic region and the sacrificial anodes within the anodic region. The protection offered by the sacrificial anodes to the steel after the 7th and 8th week was measured and protection efficiency values as high as 99.66% and 99.47% were achieved for the Al-6%Zn-1%Mg cast anode. The microstructures of the cast anodes comprise of intermetallic structures of hexagonal Mg3Zn2 and body-centered cubic Al2Mg3Zn3. These are probably responsible for the breakdown of the passive alumina film, thus enhancing the anode efficiency.

  6. Anodic polarization curves of austenitic steel Super304H in sulphuric acid solution

    OpenAIRE

    Chmela T.

    2016-01-01

    Polarization curves measured in a sufficiently aggressive environment (e.g. 0.5 mol dm−3 of H2SO4) may help to assess corrosion resistance of stainless steels. New phases precipitate in steel exposed long-term to high temperatures, which may affect the corrosion resistance. Potentiostatic polarization curves were measured on austenitic steel Super304H in a solution annealed state (from the producer) and in a state aged for 15 000 hours at temperatures of 650, 675 and 700 °C. The higher level ...

  7. Corrosion rate of construction materials in hot phosphoric acid with the contribution of anodic polarization

    DEFF Research Database (Denmark)

    Kouril, M.; Christensen, Erik; Eriksen, S.;

    2011-01-01

    ). Several grades of stainless steels were tested as well as tantalum, niobium, titanium, nickel alloys and silicon carbide. The corrosion rate was evaluated by means of mass loss at free corrosion potential as well as under various levels of polarization. The only corrosion resistant material in 85...

  8. The passive film characterization and anodic polarization behavior of 11% Cr ferritic/martensitic and 15% Cr oxide dispersion strengthened steels in different electrolytic solutions

    International Nuclear Information System (INIS)

    The ferritic/martensitic (F/M) and oxide dispersion strengthened (ODS) steels are the most promising candidate materials for future nuclear power plants. In the present work, the passive film compositions and its correlation with anodic polarization behavior of 11% Cr F/M and 15% Cr ODS steels was examined in different electrolytic solutions of borate buffer, acidic, acidified chloride and in chloride solution. The X-ray photoelectron spectroscopy analysis of the passive film reveals the existence of the layers of Cr2O3 and Fe2O3 and in 15% Cr ODS steel along with Y2O3. The open circuit potential and potentiodynamic anodic polarization measurements show that pitting corrosion resistance is strongly dependent on electrolytic solutions and passive film compositions. The ODS steel indicated increased breakdown potential and wider passive range as compared to F/M steel in chloride containing media. In a non-chloride environment, this difference is not prominent. However, low pitting corrosion resistance of both steels in chloride solutions was attributable to Cl− and microstructural inhomogeneity. The SEM micrographs of surface morphology of corrosion attack showed severe pitting corrosion attack in chloride solutions. The anodic polarization behavior of F/M and ODS steels in different electrolytic solutions was studied for this work in relation to passive film compositions.

  9. Effect of Pore Thickness and the State of Polarization on the Optical Properties of Hexagonal Nanoarray of Au/Nanoporous Anodic Alumina Membrane

    Directory of Open Access Journals (Sweden)

    Mohamed Shaban

    2015-01-01

    Full Text Available Hexagonal nanoarrays of Au particles were deposited on nanoporous anodic alumina membrane (NAAM utilizing r.f. magnetron sputtering. The thickness of the NAAMs is adjusted by changing the second anodization time from 5 min to 20 min. The surface morphology, composition, and optical properties are characterized by using SEM, EDX, and spectrophotometer, respectively. The effects of the NAAM thickness and state of polarization on the morphological changes and on the optical properties of the fabricated nanoarrays were addressed. According to the measured optical spectra, the rate of decrease of NAAMs refractive index was found to be 3.825 × 10−4 nm−1. Using the modified Kubelka-Munk radiative transfer model, the energy gap of NAAMs was calculated from diffused reflectance and was decreased from 1.682 to 1.376 as the anodization time increased from 5 to 20 min. Also, the saturation of interference fringes is substantially enhanced, and field enhancement can be achieved due to the excitation and constructive interference of surface plasmon waves by coating NAAMs with the hexagonal nanoarrays of Au. Based on the advantages of the fabrication approach and the enhanced and controlled properties, this new generation of samples can be used as promising building blocks for nanophotonic and nanoelectronics devices.

  10. Detection of divalent europium, ytterbium, and samarium ions in aqueous solution during anodic polarization of the corresponding amalgam

    International Nuclear Information System (INIS)

    Amalgams of europium, ytterbium, and samarium are oxidized both at constant current and at constant potential. It was found experimentally that the potential of the indicator electrode moved to negative values when the circuit was closed and anodic current (1.0 to 60.0 mA) or potential (of the starting wave, half wave, or limiting current) applied. The potential of the microelectrode was 0.05 V, and remained unchanged during the entire electrolysis time, when pure mercury was used as the anode. The data reported for europium, ytterbium, and samarium amalgam confirm the results otained previously. By measuring the redox potentials of couples Sm3+-Sm2, Yb3+-Yb2+ and Eu3+-Eu2+ directly at the electrode surface the authors have established the formation of divalent samarium, ytterbium, and europium ions during anodic oxidation of the corresponding amalgams

  11. Anodic oxidation

    CERN Document Server

    Ross, Sidney D; Rudd, Eric J; Blomquist, Alfred T; Wasserman, Harry H

    2013-01-01

    Anodic Oxidation covers the application of the concept, principles, and methods of electrochemistry to organic reactions. This book is composed of two parts encompassing 12 chapters that consider the mechanism of anodic oxidation. Part I surveys the theory and methods of electrochemistry as applied to organic reactions. These parts also present the mathematical equations to describe the kinetics of electrode reactions using both polarographic and steady-state conditions. Part II examines the anodic oxidation of organic substrates by the functional group initially attacked. This part particular

  12. Galvanic aspects of aluminum sacrificial anode alloys in seawater.

    OpenAIRE

    Cummings, Jon Richard

    2012-01-01

    Galvanic aspects of aluminum sacrificial anode alloys in artificial seawater were investigated. Specifically, two mercury-bearing alloys and one tin-bearing alloy were studied. The polarization behavior of the aluminum sacrificial anode alloys coupled to HY-80 steel is discussed. Current versus time curves were obtained for aluminum/steel galvanic couples immersed in artificial seawater for specific intervals. Scanning elecron microscopy was used to characterize the anode dissolution patt...

  13. XPS, time-of-flight-SIMS and polarization modulation IRRAS study of Cr{sub 2}O{sub 3} thin film materials as anode for lithium ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Li Juntao [Laboratoire de Physico-Chimie des Surfaces, CNRS (UMR 7045), Ecole Nationale Superieure de Chimie de Paris, Universite Pierre et Marie Curie, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Maurice, Vincent [Laboratoire de Physico-Chimie des Surfaces, CNRS (UMR 7045), Ecole Nationale Superieure de Chimie de Paris, Universite Pierre et Marie Curie, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France)], E-mail: vincent-maurice@enscp.fr; Swiatowska-Mrowiecka, Jolanta; Seyeux, Antoine; Zanna, Sandrine; Klein, Lorena [Laboratoire de Physico-Chimie des Surfaces, CNRS (UMR 7045), Ecole Nationale Superieure de Chimie de Paris, Universite Pierre et Marie Curie, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Sun Shigang [State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China)], E-mail: sgsun@xmu.edu.cn; Marcus, Philippe [Laboratoire de Physico-Chimie des Surfaces, CNRS (UMR 7045), Ecole Nationale Superieure de Chimie de Paris, Universite Pierre et Marie Curie, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France)], E-mail: philippe-marcus@enscp.fr

    2009-05-30

    Ultra-thin Cr{sub 2}O{sub 3} films (12.0, 17.3 and 29.6 nm thick) were produced on Cr metal by thermal oxidation, and their electrochemical properties in 1 M LiClO{sub 4} in propylene carbonate (PC) were investigated by cyclic voltammetry and chronopotentiometry. The reductive electrolyte decomposition and the conversion/deconversion process were observed and analyzed by X-ray photoelectron spectroscopy (XPS), polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The initial irreversible capacity due to the reduction of electrolyte and the incomplete deconversion process during the first cycle is 70% of the first discharge capacity. A stable charge/discharge capacity of 460 mAh g{sup -1} was obtained in the 3rd to 10th cycles. XPS and PM-IRRAS evidenced the growth of a solid electrolyte interphase (SEI) layer that is constituted of Li{sub 2}CO{sub 3} formed by reductive decomposition of the electrolyte. The SEI layer thickness and/or density is modified by the conversion/deconversion reaction. ToF-SIMS evidenced the volume expansion/shrink resulting from the conversion/deconversion reaction. ToF-SIMS also revealed an incomplete conversion process limited by mass transport, which partitions the oxide into a converted outer part assigned to Li{sub 2}O containing Cr traces and an unconverted inner part ascribed to Cr{sub 2}O{sub 3} or lower Cr oxide containing Li. It was found that the deconversion re-homogenizes the oxide film in a single layer but with lithium trapped in it. The present study provides a detailed understanding of the interfacial reaction on the oxide anode undergoing a conversion/deconversion reaction.

  14. Improving Efficiency of Aluminium Sacrificial Anode Using Cold Work Process

    Science.gov (United States)

    Asmara, Y. P.; Siregar, J. P.; Tezara, C.; Ann, Chang Tai

    2016-02-01

    Aluminium is one of the preferred materials to be used as sacrificial anode for carbon steel protection. The efficiency of these can be low due to the formation of oxide layer which passivate the anodes. Currently, to improve its efficiency, there are efforts using a new technique called surface modifications. The objective of this research is to study corrosion mechanism of aluminium sacrificial anode which has been processed by cold work. The cold works are applied by reducing the thickness of aluminium sacrificial anodes at 20% and 40% of thickness reduction. The cathodic protection experiments were performed by immersion of aluminium connected to carbon steel cylinder in 3% NaCl solutions. Visual inspections using SEM had been conducted during the experiments and corrosion rate data were taken in every week for 8 weeks of immersion time. Corrosion rate data were measured using weight loss and linear polarization technique (LPR). From the results, it is observed that cold worked aluminium sacrificial anode have a better corrosion performance. It shows higher corrosion rate and lower corrosion potential. The anodes also provided a long functional for sacrificial anode before it stop working. From SEM investigation, it is shown that cold works have changed the microstructure of anodes which is suspected in increasing corrosion rate and cause de-passivate of the surface anodes.

  15. Effect of intermetallic phases on the anodic oxidation and corrosion of 5A06 aluminum alloy

    Science.gov (United States)

    Li, Song-mei; Li, Ying-dong; Zhang, You; Liu, Jian-hua; Yu, Mei

    2015-02-01

    Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered intermetallic particles were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) after pretreatment. The anodic film was investigated by transmission electron microscopy (TEM), and its corrosion resistance was analyzed by electrochemical impedance spectroscopy (EIS) and Tafel polarization in NaCl solution. The results show that the size of Al-Fe-Mg-Mn particles gradually decreases with the iron content. During anodizing, these intermetallic particles are gradually dissolved, leading to the complex porosity in the anodic film beneath the particles. After anodizing, the residual particles are mainly silicon-containing phases, which are embedded in the anodic film. Electrochemical measurements indicate that the porous anodic film layer is easily penetrated, and the barrier plays a dominant role in the overall protection. Meanwhile, self-healing behavior is observed during the long immersion time.

  16. Fabrication of independent nickel microstructures with anodizing of aluminum,laser irradiation, and electrodeposition

    Institute of Scientific and Technical Information of China (English)

    T. Kikuchi; M. Sakairi; H. Takahashi

    2003-01-01

    Independent microstructures made of Ni metal were fabricated by five sequential processes: porous anodic oxide film for-mation, pore sealing, laser irradiation, Ni electroplating, and removal of the aluminum substrate and anodic oxide films. Aluminumplates and rods were anodized in an oxalic acid solution to form porous type anodic oxide films, and then immersed in boiling dis-tilled water for pore sealing. The anodized and pore-sealed specimens were irradiated with a pulsed neodymium-doped yttrium alu-minum garnet (Nd-YAG) laser beam in a Ni plating solution to remove anodic oxide film locally by rotating and moving up / downwith an XYZθ-stage. Nickel was deposited at the area where film had been removed by cathodic polarization in the solution beforeremoving the aluminum substrate and anodic oxide films in NaOH solutions. Cylindrical or plain network structures were fabricated successfully.

  17. Preparation and Properties of Al-Ni Composite Anodic Films on Aluminum Surface

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xuhui; YE Hao; ZHANG Xiaofeng; ZUO Yu

    2012-01-01

    Ni element was introduced to aluminum surface by a simple chemical immersion method,and Al-Ni composite anodic films were obtained by following anodizing.The morphology,structure and composition of the Al-Ni anodic films were examined by scanning electron microscopy (SEM),energy disperse spectroscopy (EDS) and atomic force microscopy(AFM).The electrochemical behaviors of the films were studied by means of polarization measurement and electrochemical impedance spectroscopy (EIS).The experimental results show that the A1-Ni composite anodic film is more compact with smaller pore diameters than that of the Al anodic film.The introduction of nickel increases the impedances of both the barrier layer and the porous layer of the anodic films.In NaCl solutions,the Al-Ni composite anodic films show higher impedance values and better corrosion resistance.

  18. The effect of grain size on aluminum anodes for Al-air batteries in alkaline electrolytes

    Science.gov (United States)

    Fan, Liang; Lu, Huimin

    2015-06-01

    Aluminum is an ideal material for metallic fuel cells. In this research, different grain sizes of aluminum anodes are prepared by equal channel angular pressing (ECAP) at room temperature. Microstructure of the anodes is examined by electron backscatter diffraction (EBSD) in scanning electron microscope (SEM). Hydrogen corrosion rates of the Al anodes in 4 mol L-1 NaOH are determined by hydrogen collection method. The electrochemical properties of the aluminum anodes are investigated in the same electrolyte using electrochemical impedance spectroscopy (EIS) and polarization curves. Battery performance is also tested by constant current discharge at different current densities. Results confirm that the electrochemical properties of the aluminum anodes are related to grain size. Finer grain size anode restrains hydrogen evolution, improves electrochemical activity and increases anodic utilization rate. The proposed method is shown to effectively improve the performance of Al-air batteries.

  19. Nickel/Yttria-stabilised zirconia cermet anodes for solid oxide fuel cells

    NARCIS (Netherlands)

    Primdahl, Søren

    1999-01-01

    This thesis deals with the porous Ni/yttria-stabilized zirconia (YSZ) cermet anode on a YSZ electrolyte for solid oxide fuel cells (SOFC). Such anodes are predominantly operated in moist hydrogen at 700°C to 1000°C, and the most important technological parameters are the polarization resistance and

  20. Pulsed diode source of polarized ions

    International Nuclear Information System (INIS)

    The advantages of polarized nuclei for fusion reactors have recently been described. We propose a pulsed source of polarized nuclei that consists of an ion diode with a polarized anode. With magnetic resonance techniques the nuclear spins of the protons of solid NH3 can be made about 90 to 95% polarized. This material would be used for the anode. The diode would be pulsed with a voltage of 1-200K-volts for 1-2 μ sec. Flashover of the anode produces a surface plasma from which the polarized protons would be extracted to form a beam. Depolarization could be detected by comparing reaction cross sections and/or distribution of reaction products with similar results for unpolarized beams

  1. Energy transfer in porous anodic alumina/rhodamine 110 nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Elhouichet, H., E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire de Physico-Chimie des Materiaux Mineraux et leurs Applications, Centre National de Recherches en Sciences des Materiaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Departement de Physique, Faculte des Sciences de Tunis, University of Tunis Elmanar 2092 Tunis (Tunisia); Harima, N.; Koyama, H. [Hyogo University of Teacher Education, Kato, Hyogo 673-1494 (Japan); Gaponenko, N.V. [Belarusian State University of Informatics and Radioelectronics, P. Browki St. 6, 220013 Minsk (Belarus)

    2012-09-15

    We have used porous anodic alumina (PAA) films as templates for embedding rhodamine 110 (Rh110) molecules and examined their photoluminescence (PL) properties in detail. The analysis of the polarization memory (PM) of PL strongly suggests that there is a significant energy transfer from PAA to Rh110 molecules. The effect of annealing the PAA layer on the PL properties of the nanocomposite has been studied. The results show that the energy transfer becomes more efficient in annealed PAA. - Highlights: Black-Right-Pointing-Pointer Porous anodic alumina-rhodamine 110 nanocomposites are elaborated. Black-Right-Pointing-Pointer Efficient energy transfer from the host to Rh110 molecules is evidenced from measurements of photoluminescence and degree of polarization memory spectra. Black-Right-Pointing-Pointer Thermal annealing of porous anodic alumina can improve the process of excitation transfer.

  2. Surface Modification of a MCFC Anode by Electrochemical Alloying

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Considering the properties of the valve metal alloys with specific corrosion resistance and electrocatalytic ac tivity, an investigation was made to examine if nickel-niobium alloy could serve as the anode material for molten carbo nate fuel cell (MCFC). An attempt was made to produce nickel-niobium surface alloy by an electrochemical process in the molten fluorides and to testify its performance required by the MCFC anode. Experimental results indicated that the corrosion resistance as well as polarization performance of the nickel electrode was improved by the surface alloying.As far as the corrosion resistance and polarization performance is concerned, the nickel-niobium surface alloy can be considered as a candidate material for the anode of MCFC.

  3. Double anodization experiments in tantalum

    Energy Technology Data Exchange (ETDEWEB)

    Albella, J.M.; Fernandez, M.; Gomez-Aleixandre, C.; Martinez-Duart, J.M.; Montero, I.

    1985-10-01

    Based on our previous model of anodization, a new formula is given for the relation between the breakdown voltage V /SUB B/ during the anodic oxidation of tantalum and the anodization parameters. The formula predicts the well known diminution of V /SUB B/ with the logarithm of the electrolyte concentration. The model also explains the experimentally-observed fact that V /SUB B/ is solely determined by the latter electrolyte in double anodization experiments.

  4. Anodes for alkaline electrolysis

    Science.gov (United States)

    Soloveichik, Grigorii Lev

    2011-02-01

    A method of making an anode for alkaline electrolysis cells includes adsorption of precursor material on a carbonaceous material, conversion of the precursor material to hydroxide form and conversion of precursor material from hydroxide form to oxy-hydroxide form within the alkaline electrolysis cell.

  5. Inert Anode Report

    Energy Technology Data Exchange (ETDEWEB)

    none,

    1999-07-01

    This ASME report provides a broad assessment of open literature and patents that exist in the area of inert anodes and their related cathode systems and cell designs, technologies that are relevant for the advanced smelting of aluminum. The report also discusses the opportunities, barriers, and issues associated with these technologies from a technical, environmental, and economic viewpoint.

  6. Direct methanol utilization in intermediate temperature liquid-tin anode solid oxide fuel cells

    International Nuclear Information System (INIS)

    Highlights: • Modification of Sn-based anode with Cu/SDC improves power density. • Cu and SDC improve wetting of Sn on YSZ and reduce anode polarization resistance. • Carbon formation has not been observed in SOFCs containing tin-based anodes. • Micro-channel structure in the anode reduces gas conversion resistance. - Abstract: Direct utilization of methanol in liquid tin anode solid oxide fuel cells has been experimentally demonstrated at 1023 K. A Cu and SDC modified Sn anode solid oxide fuel cell had a maximum power density of 259.2 mW/cm2 during operation on methanol. Carbon deposition was not observed in the Raman spectra of the post-test anodes. Electrochemical impedance spectroscopy indicated that gas conversion resistance increased when using methanol instead of hydrogen. The micro-channel architecture of the electrode mitigated the increase. Scanning electron microscopy images showed that addition of Cu and Sn improved wetting of Sn on YSZ and reduced anode polarization resistance. The anode gases were analyzed by mass spectroscopy and a mechanism for electrochemical oxidation of methanol has been proposed

  7. Anodization of AZ91 magnesium alloy in alkaline solution containing silicate and corrosion properties of anodized films

    Institute of Scientific and Technical Information of China (English)

    LI Ling-ling; CHENG Ying-liang; WANG Hui-min; ZHANG Zhao

    2008-01-01

    The anodization of AZ91 magnesium alloy in an alkaline electrolyte of 100g/L NaOH+20g/L Na2B4O7·10H2O+50g/L C6H5Na3O7·2H2O+60g/L Na2SiO3·9H2O was studied.The corrosion resistance of the anodized films was studied by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques.The microstructure of the films was examined with scanning electronic microscope (SEM) and X-ray diffractometer (XRD).The results show that,under the experimental conditions,the optimum anodizing time and the optimum anodizing current density are 40min and 20mA/cm2 respectively for obtaining the anodic film with high corrosion resistance.The XRD pattern shows that the components of the anodized film consist of MgO and Mg2 (SiO4).

  8. 3D Microstructure Effects in Ni-YSZ Anodes: Influence of TPB Lengths on the Electrochemical Performance

    OpenAIRE

    Omar M. Pecho; Andreas Mai; Beat Münch; Thomas Hocker; Robert J. Flatt; Lorenz Holzer

    2015-01-01

    3D microstructure-performance relationships in Ni-YSZ anodes for electrolyte-supported cells are investigated in terms of the correlation between the triple phase boundary (TPB) length and polarization resistance (Rpol). Three different Ni-YSZ anodes of varying microstructure are subjected to eight reduction-oxidation (redox) cycles at 950 °C. In general the TPB lengths correlate with anode performance. However, the quantitative results also show that there is no simplistic relationship betwe...

  9. Photoelectrochemical cell with nondissolving anode

    Science.gov (United States)

    Ellis, A. B.; Kaiser, S. W.; Wrighton, M. S.

    1980-01-01

    Improved electrolytic cells have efficiencies comparable to those of best silicon solar cells but are potentially less expensive to manufacture. Cells consist of light-sensitive n-type semiconductor anode and metallic cathode immersed in electrolytic solution. Reversible redox cells produce no chemical change in electrolyte and stabilize anode against dissolving. Cell can produce more than 500 mW of power per square centimeter of anode area at output voltage of 0.4 V.

  10. Anodes for Solid Oxide Fuel Cells Operating at Low Temperatures

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain

    . On the other hand, low-temperature operation poses serious challenges to the electrode performance. Effective catalysts, redox stable electrodes with improved microstructures are the prime requisite for the development of efficient SOFC anodes. The performance of Nb-doped SrT iO3 (STN) ceramic anodes......An important issue that has limited the potential of Solid Oxide Fuel Cells (SOFCs) for portable applications is its high operating temperatures (800-1000 ºC). Lowering the operating temperature of SOFCs to 400-600 ºC enable a wider material selection, reduced degradation and increased lifetime......, an investigation on the effect of application of cathodic polarization on Ni-YSZ anodes is described....

  11. Screened Anode N2 Laser

    OpenAIRE

    Sabry, M. Montaser Foad

    1985-01-01

    An experimental study of the effect of screening the discharge channel on the output energy is presented. It has been found that a screened anode nitrogen laser generates higher output energy than that of a screened cathode, and also higher than that when both cathode and anode are unshielded at higher pressures.

  12. Mesoporous Silicon-Based Anodes

    Science.gov (United States)

    Peramunage, Dharmasena

    2015-01-01

    For high-capacity, high-performance lithium-ion batteries. A new high-capacity anode composite based on mesoporous silicon is being developed. With a structure that resembles a pseudo one-dimensional phase, the active anode material will accommodate significant volume changes expected upon alloying and dealloying with lithium (Li).

  13. Electrochemical cell design for the impedance studies of chlorine evolution at DSA anodes

    Science.gov (United States)

    Silva, J. F.; Dias, A. C.; Araújo, P.; Brett, C. M. A.; Mendes, A.

    2016-08-01

    A new electrochemical cell design suitable for the electrochemical impedance spectroscopy (EIS) studies of chlorine evolution on Dimensionally Stable Anodes (DSA®) has been developed. Despite being considered a powerful tool, EIS has rarely been used to study the kinetics of chlorine evolution at DSA anodes. Cell designs in the open literature are unsuitable for the EIS analysis at high DSA anode current densities for chlorine evolution because they allow gas accumulation at the electrode surface. Using the new cell, the impedance spectra of the DSA anode during chlorine evolution at high sodium chloride concentration (5 mol dm-3 NaCl) and high current densities (up to 140 mA cm-2) were recorded. Additionally, polarization curves and voltammograms were obtained showing little or no noise. EIS and polarization curves evidence the role of the adsorption step in the chlorine evolution reaction, compatible with the Volmer-Heyrovsky and Volmer-Tafel mechanisms.

  14. Electrochemical cell design for the impedance studies of chlorine evolution at DSA(®) anodes.

    Science.gov (United States)

    Silva, J F; Dias, A C; Araújo, P; Brett, C M A; Mendes, A

    2016-08-01

    A new electrochemical cell design suitable for the electrochemical impedance spectroscopy (EIS) studies of chlorine evolution on Dimensionally Stable Anodes (DSA(®)) has been developed. Despite being considered a powerful tool, EIS has rarely been used to study the kinetics of chlorine evolution at DSA anodes. Cell designs in the open literature are unsuitable for the EIS analysis at high DSA anode current densities for chlorine evolution because they allow gas accumulation at the electrode surface. Using the new cell, the impedance spectra of the DSA anode during chlorine evolution at high sodium chloride concentration (5 mol dm(-3) NaCl) and high current densities (up to 140 mA cm(-2)) were recorded. Additionally, polarization curves and voltammograms were obtained showing little or no noise. EIS and polarization curves evidence the role of the adsorption step in the chlorine evolution reaction, compatible with the Volmer-Heyrovsky and Volmer-Tafel mechanisms.

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

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

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

  16. Assessment of the cathode contribution to the degradation of anode-supported solid oxide fuel cells

    DEFF Research Database (Denmark)

    Hagen, Anke; Liu, Yi-Lin; Barfod, Rasmus;

    2008-01-01

    The degradation of anode-supported cells was studied over 1500 h as a function of cell polarization either in air or oxygen on the cathode side. Based on impedance analysis, contributions of the anode and cathode to the increase of total resistance were assigned. Accordingly, the degradation rate......-stabilized zirconia electrolyte and consequently a reduced three-phase boundary length. (C) 2008 The Electrochemical Society....

  17. The electrochemical oxidation of H{sub 2} and CO at patterned Ni anodes of SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Utz, Annika

    2011-07-01

    In this work, a deeper understanding of the electrochemical oxidation at SOFC anodes was gained by the experimental characterization of patterned Ni anodes in H{sub 2}-H{sub 2}O and CO-CO{sub 2} atmosphere. By high resolution data analysis, the Line Specific Resistance attributed to charge transfer and its dependencies on gas composition, temperature and polarization voltage were identified. Furthermore, the comparison of the performance of patterned and cermet anodes was enabled using a transmission line model. (orig.)

  18. Multi-anode ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Bolotnikov, Aleksey E. (South Setauket, NY); Smith, Graham (Port Jefferson, NY); Mahler, George J. (Rocky Point, NY); Vanier, Peter E. (Setauket, NY)

    2010-12-28

    The present invention includes a high-energy detector having a cathode chamber, a support member, and anode segments. The cathode chamber extends along a longitudinal axis. The support member is fixed within the cathode chamber and extends from the first end of the cathode chamber to the second end of the cathode chamber. The anode segments are supported by the support member and are spaced along the longitudinal surface of the support member. The anode segments are configured to generate at least a first electrical signal in response to electrons impinging thereon.

  19. Effect of anodization on corrosion behaviour and biocompatibility of Cp-titanium in simulated body fluid

    Indian Academy of Sciences (India)

    Archana Singh; B P Singh; Mohan R Wani; Dinesh Kumar; J K Singh; Vakil Singh

    2013-10-01

    The objective of this investigation is to study the effectiveness of anodized surface of commercial purity titanium (Cp-Ti) on its corrosion behaviour in simulated body fluid (SBF) and proliferation of osteoblast cells on it, to assess its potentiality as a process of surface modification in enhancing corrosion resistance and osseointegration of dental implants. Highly ordered nano-porous oxide layer, with nano-sized pores, is developed on the surface of Cp-Ti through electrochemical anodization in the electrolyte of aqueous solution of 0.5% HF at 15 V for 30 min at 24 °C. The nano-porous feature of the anodized surface is characterized by field-emission scanning electron microscope (FESEM). Pores of some anodized samples are sealed by exposing the anodized surface in boiling water. Corrosion behaviour of the anodized specimen is studied in Ringer’s solution at 30 ± 2 °C, using electrochemical impedance and cyclic polarization technique. Biocompatibility of the anodized surface is accessed using MG63 osteoblast cells. Both corrosion as well as pitting resistance of Cp-Ti in simulated body fluid are found to be highest in the anodized and sealed condition and followed in decreasing order by those of anodized and unanodized ones. Significantly higher MG63 osteoblast cell proliferations are found on the anodized surface than that on the unanodized one. Anodized Cp-Ti develops nano-size surface pores, like that of natural bone. It enhances corrosion and pitting resistance and also the process of osteoblast cell proliferation on Cp-Ti.

  20. Alternative Anodes for the Electrolytic Reduction of Uranium Dioxide

    Science.gov (United States)

    Merwin, Augustus

    Reprocessing of spent nuclear fuel is an essential step in closing the nuclear fuel cycle. In order to consume current stockpiles, ceramic uranium dioxide spent nuclear fuel will be subjected to an electrolytic reduction process. The current reduction process employs a platinum anode and a stainless steel alloy 316 cathode in a molten salt bath consisting of LiCl-2wt% Li 2O and occurs at 700°C. A major shortcoming of the existing process is the degradation of the platinum anode under the severely oxidizing conditions encountered during electrolytic reduction. This work investigates alternative anode materials for the electrolytic reduction of uranium oxide. The high temperature and extreme oxidizing conditions encountered in these studies necessitated a unique set of design constraints on the system. Thus, a customized experimental apparatus was designed and constructed. The electrochemical experiments were performed in an electrochemical reactor placed inside a furnace. This entire setup was housed inside a glove box, in order to maintain an inert atmosphere. This study investigates alternative anode materials through accelerated corrosion testing. Surface morphology was studied using scanning electron microscopy. Surface chemistry was characterized using energy dispersive spectroscopy and Raman spectroscopy. Electrochemical behavior of candidate materials was evaluated using potentiodynamic polarization characteristics. After narrowing the number of candidate electrode materials, ferrous stainless steel alloy 316, nickel based Inconel 718 and elemental tungsten were chosen for further investigation. Of these materials only tungsten was found to be sufficiently stable at the anodic potential required for electrolysis of uranium dioxide in molten salt. The tungsten anode and stainless steel alloy 316 cathode electrode system was studied at the required reduction potential for UO2 with varying lithium oxide concentrations. Electrochemical impedance spectroscopy

  1. Nano structural anodes for radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cordaro, Joseph V.; Serkiz, Steven M.; McWhorter, Christopher S.; Sexton, Lindsay T.; Retterer, Scott T.

    2015-07-07

    Anodes for proportional radiation counters and a process of making the anodes is provided. The nano-sized anodes when present within an anode array provide: significantly higher detection efficiencies due to the inherently higher electric field, are amenable to miniaturization, have low power requirements, and exhibit a small electromagnetic field signal. The nano-sized anodes with the incorporation of neutron absorbing elements (e.g., .sup.10B) allow the use of neutron detectors that do not use .sup.3He.

  2. Anodic oxide growth on Zr in neutral aqueous solution

    Indian Academy of Sciences (India)

    Z Tun; J J Noël; D W Shoesmith

    2008-10-01

    Anodization and subsequent cathodic reactions on a thin-film sample of Zr were studied with in-situ neutron reflectometry (NR) and electrochemical impedance spectroscopy (EIS). The NR results during anodization showed the originally 485 Å thick Zr film generally behaved similar to a bulk electrode in neutral solution. The anodization ratio measured at applied potentials increased in steps of 0.5 V was somewhat higher than the value determined by coulometry, while the Pilling Bedworth ratio is in good agreement with published data. Thickening of the oxide layer, accelerated immediately after each potential increase, gradually decreased over several hours, but remained non-zero even after ∼ 12 h. The thickened oxide eventually cracked when its thickness reached ∼ 120 Å, causing loss of passivation. Surprisingly, neither the anodization ratio nor the Pilling Bedworth ratio showed any discontinuity at the time of oxide cracking, and the EIS behaviour remained qualitatively as before. This observation is taken as the evidence that the cracked and intact regions of the electrode behave more or less independently as parallel electrodes. When the potential was eventually switched to cathodic polarity, NR shows, as expected, that the effects of oxide cracking were irreversible. However, the electrode resistance recovered partially suggesting the cracks were rapidly plugged with newly formed oxide.

  3. Alternate Anodes for the Electrolytic Reduction of UO2

    Science.gov (United States)

    Merwin, Augustus; Chidambaram, Dev

    2015-01-01

    The electrolytic reduction process of UO2 employs a platinum anode and a stainless steel cathode in molten LiCl-LiO2 maintained at 973 K (700 °C). The degradation of platinum under the severely oxidizing conditions encountered during the process is an issue of concern. In this study, Inconel 600 and 718, stainless steel alloy 316, tungsten, nickel, molybdenum, and titanium, were investigated though electrochemical polarization techniques, electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy to serve as potential anode materials. Of the various materials investigated, only tungsten exhibited sufficient stability at the required potential in the molten electrolyte. Tungsten anodes were further studied in molten LiCl-LiO2 electrolyte containing 2, 4, and 6 wt pct of Li2O. In LiCl-2 wt pct Li2O tungsten was found to be sufficiently stable to both oxidation and microstructural changes and the stability is attributed to the formation of a lithium-intercalated tungsten oxide surface film. Increase in the concentration of Li2O was found to lead to accelerated corrosion of the anode, in conjunction with the formation of a peroxotungstate oxide film.

  4. The kinetics of anodic dissolution of rhenium in aqueous electrolyte solutions

    International Nuclear Information System (INIS)

    The kinetics of anodic rhenium dissolution was investigated by means of potentiodynamic and potentiostatic polarization curves recorded at temperature from 293 to 333 K in different media (NaOH, KOH, NaCl, NaBr, HCl, H2SO4) using the rotating disc technique. It is shown that the kinetics of anodic rhenium dissolution and effective activation energy depend not only on the composition and pH value of the solutions but also on the structure of the dissolving rhenium surface. The investigation of the anodic behaviour of the rhenium monocrystal revealed the existence of anisotropy of the monocrystal electrochemical properties. The experimental results point to an important role of adsorption processes in anodic rhenium dissolution. Rhenium dissolution proceeds with formation of intermediate surface adsorption complexes between the metal and the components of the solution

  5. The influence of Ti and Sr alloying elements on electrochemical properties of aluminum sacrificial anodes

    Energy Technology Data Exchange (ETDEWEB)

    Saremi, M.; Sina, H.; Keyvani, A.; Emamy, M. [Metallurgy and Materials Department, University of Tehran, P.O. Box 11365/4563, Tehran (Iran)

    2004-07-01

    Aluminum sacrificial anodes are widely used in cathodic protection of alloys in seawater. The interesting properties due to low specific weight, low electrode potential and high current capacity are often hindered by the presence of a passive oxide film which causes several difficulties in their practical application. In this investigation, the electrochemical behavior of Al- 5Zn-0.02In sacrificial anode is studied in 3 wt. % sodium chloride solution. The experiments focused on the influence of Ti and Sr as alloying elements on electrochemical behavior of aluminum sacrificial anode. Ti and Sr are used in different concentrations from 0.03 to 0.1 wt.% 0.01 to 0.05 wt.%, respectively. NACE efficiency and polarization tests are used in this case. It is shown that by using 0.03 wt.% Ti and 0.01 wt.% Sr as the alloying elements to investigate the anodic behavior of the anodes, homogeneous microstructures are obtained which results in improvement of electrochemical properties of aluminum sacrificial anode such as current capacity and anode efficiency. (authors)

  6. Ni3Mo3C as anode catalyst for high-performance microbial fuel cells.

    Science.gov (United States)

    Zeng, Li-Zhen; Zhao, Shao-Fei; Li, Wei-Shan

    2015-03-01

    Ni3Mo3C was prepared by a modified organic colloid method and explored as anode catalyst for high-performance microbial fuel cell (MFC) based on Klebsiella pneumoniae (K. pneumoniae). The prepared sample was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET). The activity of the sample as anode catalyst for MFC based on K. pneumoniae was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and polarization curve measurement. The results show that the adding of nickel in Mo2C increases the BET surface area of Mo2C and improves the electrocatalytic activity of Mo2C towards the oxidation of microbial fermentation products. The power density of MFC with 3 mg cm(-2) Ni3Mo3C anode is far higher than that of the MFC with carbon felt as anode without any catalyst, which is 19 % higher than that of Mo2C anode and produced 62 % as much as that of Pt anode, indicating that Ni3Mo3C is comparative to noble metal platinum as anode electrocatalyst for MFCs by increasing the loading.

  7. Composite corrosion inhibitors for secondary alkaline zinc anodes

    Institute of Scientific and Technical Information of China (English)

    JIA Zheng; ZHOU De-rui; ZHANG Cui-fen

    2005-01-01

    The corrosion inhibition property of PEG600 and In(OH)3 as composite corrosion inhibitors for secondary alkaline zinc electrodes was studied,and the inhibition efficiency was determined as 81.9%.The research focused on the mechanism by the methods of electrochemical impedance spectroscopy,polarization curves and IR spectroscopy.The results indicate that the corrosion inhibition effectiveness is attributed to the joint inhibition of anodic zinc dissolution and cathodic hydrogen evolution.And the anodic process is depressed to a greater extent than the cathodic process.The synergistic mechanism of the composite inhinbitors proves to be the enhancement of adsorption of PEG600 by In(OH)3.Potentiostatic experiment results and SEM images verify the inhibition of dendritic growth by the composite inhibitors.

  8. Anodic behavior and microstructure of Al/Pb-Ag anode during zinc electrowinning%Al/Pb-Ag阳极在锌电积过程中的阳极行为和微观结构

    Institute of Scientific and Technical Information of China (English)

    张永春; 陈步明; 杨海涛; 郭忠诚; 徐瑞东

    2014-01-01

    Anodic behaviors and oxygen evolution kinetics of Pb-0.8%Ag and Al/Pb-0.8%Ag anodes during the initial 24 h zinc electrowinning were investigated with cyclic voltammetry (CV) curves and electrochemical impedance spectroscopy (EIS). The results reveal that the anodic behaviors and reaction kinetics of the two anodes vary a lot during the anodic polarization which indicate the formation and stabilization of anodic layer. Compared with conventional Pb-0.8%Ag anode, Al/Pb-0.8%Ag anode has longer time of anodic polarization. At the very beginning of anodic polarization, the two anodes all exhibit higher potential of oxygen evolution reaction (OER) since the reaction is controlled by the transformation step of intermediates. Then, its OER potential is largely diminished and OER rate is deduced from the formation and adsorption of the first intermediate (S-OHads). In the prolonged anodic polarization, the anodic potential of Al/Pb-0.8%Ag gradually decreases and the final value is more stable than that of conventional Pb-0.8%Ag anode. On the anodic layer after 24 h of anodic polarization, the OER potential is controlled by the formation and adsorption of intermediate. The microstructures of Al/Pb-0.8%Ag and Pb-0.8%Ag anodes after 24 h of anodic polarization were analyzed by scanning electron microscope (SEM).%采用循环伏安曲线(CV)和电化学交流阻抗谱(EIS)研究Pb-0.8%Ag 和Al/Pb-0.8%Ag阳极在最初24 h锌电积过程中的阳极行为和析氧动力学。结果表明:2种阳极材料在阳极极化过程中的阳极行为和动力学的多种变化表明阳极表面膜的形成和稳定。与传统的Pb-0.8%Ag阳极相比,Al/Pb-0.8%Ag阳极具有较长的极化时间。在最初的电积过程中,阳极表面中间产物的转变使2种阳极都表现出较高的析氧电位。随着析氧电位降低,析氧反应速率可以由阳极表面最初的生成物和中间产物S-OHads推断。随着电积的持续进行,Al/Pb-0.8%Ag阳极的析

  9. Relation of bacterial settlement patterns to anodic activity on stainless steel weldments

    Energy Technology Data Exchange (ETDEWEB)

    Eashwar, M.; Dexter, S.C. [Univ. of Delaware, Lewes, DE (United States). Coll. of Marine Studies

    1999-11-01

    Bacterial settlement on welded stainless steel samples exposed to seawater occurred more rapidly in the heat-affected zone (HAZ) and the root of the weld as compared to the parent metal. Preferential attachment of bacteria to a network of surface cracks was an occasional feature, which became more conspicuous during mild anodic polarization of the samples. In a less corrosive fresh water system, bacterial settlement was more random, until application of anodic polarization which triggered bacterial settlement patterns analogous to the sea water system. Supplementary experiments on bacterial response to pre-initiated corrosion sites in the form of pits and scratches reinforced the idea that bacteria preferentially colonize areas of anodic electrochemical activity and/or metal ion release.

  10. Effect of heat treatment on anodic activation of aluminium by trace element indium

    Energy Technology Data Exchange (ETDEWEB)

    Graver, Brit [Department of Materials Science and Engineering, Norwegian University of Science and Technology, N-7491 Trondheim (Norway); Helvoort, Antonius T.J. van [Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim (Norway); Nisancioglu, Kemal, E-mail: kemal.nisancioglu@material.ntnu.n [Department of Materials Science and Engineering, Norwegian University of Science and Technology, N-7491 Trondheim (Norway)

    2010-11-15

    Research highlights: {yields} Indium segregation activates AlIn alloy surface anodically in chloride solution. {yields} Enrichment of In on Al surface can occur thermally by heat treatment at 300 {sup o}C. {yields} Increasing temperature homogenises indium in aluminium reducing anodic activation. {yields} Indium can activate AlIn surface by segregating through dealloying of aluminium. {yields} Anodic activation is caused by AlIn amalgam formation at aluminium surface. - Abstract: The presence of trace elements in Group IIIA-VA is known to activate aluminium anodically in chloride environment. The purpose of this paper is to investigate the surface segregation of trace element In by heat treatment and resulting surface activation. Model binary AlIn alloys, containing 20 and 1000 ppm by weight of In, were characterized after heat treatment at various temperatures by use of glow discharge optical emission spectroscopy, electron microscopy and electrochemical polarization. Heat treatment for 1 h at 300 {sup o}C gave significant segregation of discrete In particles (thermal segregation), which activated the surface. Indium in solid solution with aluminium, obtained by 1 h heat treatment at 600 {sup o}C, also activated by surface segregation of In on alloy containing 1000 ppm In, resulting from the selective dissolution of the aluminium component during anodic oxidation (anodic segregation). The effect of anodic segregation was reduced by decreasing indium concentration in solid solution; it had negligible effect at the 20 ppm level. The segregated particles were thought to form a liquid phase alloy with aluminium during anodic polarization, which in turn, together with the chloride in the solution destabilized the oxide.

  11. Porous Yttria-Stabilized Zirconia Microstructures for SOFC Anode Fabrication

    Science.gov (United States)

    Palakkathodi Kammampata, Sanoop

    Solid oxide fuel cells (SOFCs) are electrochemical devices that convert fuels, such as hydrogen and natural gas, to electricity at high efficiencies, e.g., up to 90 %. SOFCs are emerging as a key technology for energy production that also minimize greenhouse gas emissions compared to conventional thermal power generation. SOFCs, which are normally based on nickel-yttria stabilized zirconia (YSZ) anodes, undergo degradation with time due to their high operating temperatures and their susceptibility to damage due to anode oxidation (redox cycling) and poisoning. Ni infiltration into porous YSZ scaffolds is considered to be a promising approach for overcoming some of these problems and enhancing their redox tolerance. However, long-term instability of the morphology of these types of anodes is an important problem. The focus of this thesis was therefore to develop methods to form porous YSZ scaffolds and attempt to construct stable Ni-YSZ anodes with reasonable electrochemical performance by infiltration. In this work, the issue of long-term instability was considered to originate from both the porous YSZ scaffold microstructure and the Ni infiltration precursor employed. To study this more closely, two different porous YSZ scaffold microstructures were developed by using tape casting, followed by Ni infiltration using a polymeric precursor, known to form a continuous Ni phase, rather than electrically separated Ni particles. Ni infiltration into porous YSZ scaffolds with large grains (0.5 microm) and large pores (two types of pores: ˜0.5 microm and 5 microm) resulted in extensive Ni particle growth that resulted in poor stability and poor electrochemical performance (0.5 Ω cm2 per electrode at 800°C). Ni infiltration into a scaffold having finer grains and pores (˜200 nm each) resulted in anodes with a much lower polarization resistance of 0.11 Ω cm2 per electrode at 800°C, increasing by ˜5 % after 108 hours at this temperature.

  12. Aluminum oxide as a dual-functional modifier of Ni-based anodes of solid oxide fuel cells for operation on simulated biogas

    Science.gov (United States)

    Wang, Feng; Wang, Wei; Ran, Ran; Tade, Moses O.; Shao, Zongping

    2014-12-01

    Al2O3 and SnO2 additives are introduced into the Ni-YSZ cermet anode of solid oxide fuel cells (SOFCs) for operation on simulated biogas. The effects of incorporating Al2O3/SnO2 on the electrical conductivity, morphology, coking resistance and catalytic activity for biogas reforming of the cermet anode are systematically studied. The electrochemical performance of the internal reforming SOFC is enhanced by introducing an appropriate amount of Al2O3 into the anode, but it becomes worse with excess alumina addition. For SnO2, a negative effect on the electrochemical performance is demonstrated, although the coking resistance of the anode is improved. For fuel cells operating on biogas, stable operation under a polarization current for 130 h at 750 °C is achieved for a cell with an Al2O3-modified anode, while cells with unmodified or SnO2-modified Ni-YSZ anodes show much poorer stability under the same conditions. The improved performance of the cell with the Al2O3-modified anode mainly results from the suppressed coking and sintering of the anode and from the formation of NiAl2O4 in the unreduced anode. In sum, modifying the anode with Al2O3 may be a useful and facile way to improve the coking resistance and electrochemical performance of the nickel-based cermet anodes for SOFCs.

  13. The function of microporous layers and the interaction between the anode and cathode in DMFCs

    DEFF Research Database (Denmark)

    Zhang, H. F.; Wang, SY; Pei, PC;

    2008-01-01

    A combined effect of microporous layers (MPLs) on direct methanol fuel cells (DMFCs) is investigated. From the distribution of the outstanding carbon loading combinations of the cathode MPL and anode MPL as well as the evolutions of polarization curves, a combined effect in which the contribution...

  14. Ellipsometry of anodic film growth

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.G.

    1978-08-01

    An automated computer interpretation of ellisometer measurements of anodic film growth was developed. Continuous mass and charge balances were used to utilize more fully the time dependence of the ellipsometer data and the current and potential measurements. A multiple-film model was used to characterize the growth of films which proceeds via a dissolution--precipitation mechanism; the model also applies to film growth by adsorption and nucleation mechanisms. The characteristic parameters for film growth describe homogeneous and heterogeneous crystallization rates, film porosities and degree of hydration, and the supersaturation of ionic species in the electrolyte. Additional descriptions which may be chosen are patchwise film formation, nonstoichiometry of the anodic film, and statistical variations in the size and orientation of secondary crystals. Theories were developed to describe the optical effects of these processes. An automatic, self-compensating ellipsometer was used to study the growth in alkaline solution of anodic films on silver, cadmium, and zinc. Mass-transport conditions included stagnant electrolyte and forced convection in a flow channel. Multiple films were needed to characterize the optical properties of these films. Anodic films grew from an electrolyte supersatuated in the solution-phase dissolution product. The degree of supersaturation depended on transport conditions and had a major effect on the structure of the film. Anodic reaction rates were limited by the transport of charge carriers through a primary surface layer. The primary layers on silver, zinc, and cadmium all appeared to be nonstoichiometric, containing excess metal. Diffusion coefficients, transference numbers, and the free energy of adsorption of zinc oxide were derived from ellipsometer measurements. 97 figures, 13 tables, 198 references.

  15. Anode sheath transition in an anodic arc for synthesis of nanomaterials

    Science.gov (United States)

    Nemchinsky, V. A.; Raitses, Y.

    2016-06-01

    The arc discharge with ablating anode or so-called anodic arc is widely used for synthesis of nanomaterials, including carbon nanotubes and fullerens, metal nanoparticles etc. We present the model of this arc, which confirms the existence of the two different modes of the arc operation with two different anode sheath regimes, namely, with negative anode sheath and with positive anode sheath. It was previously suggested that these regimes are associated with two different anode ablating modes—low ablation mode with constant ablation rate and the enhanced ablation mode (Fetterman et al 2008 Carbon 46 1322). The transition of the arc operation from low ablation mode to high ablation mode is determined by the current density at the anode. The model can be used to self-consistently determine the distribution of the electric field, electron density and electron temperature in the near-anode region of the arc discharge. Simulations of the carbon arc predict that for low arc ablating modes, the current is driven mainly by the electron diffusion to the anode. For positive anode sheath, the anode voltage is close to the ionization potential of anode material, while for negative anode sheath, the anode voltage is an order of magnitude smaller. It is also shown that the near-anode plasma, is far from the ionization equilibrium.

  16. [Vernier Anode Design and Image Simulation].

    Science.gov (United States)

    Zhao, Ai-rong; Ni, Qi-liang; Song, Ke-fei

    2015-12-01

    Based-MCP position-sensitive anode photon-counting imaging detector is good at detecting extremely faint light, which includes micro-channel plate (MCP), position-sensitive anode and readout, and the performances of these detectors are mainly decided by the position-sensitive anode. As a charge division anode, Vernier anode using cyclically varying electrode areas which replaces the linearly varying electrodes of wedge-strip anode can get better resolution and greater electrode dynamic range. Simulation and design of the Vernier anode based on Vernier's decode principle are given here. Firstly, we introduce the decode and design principle of Vernier anode with nine electrodes in vector way, and get the design parameters which are the pitch, amplitude and the coarse wavelength of electrode. Secondly, we analyze the effect of every design parameters to the imaging of the detector. We simulate the electron cloud, the Vernier anode and the detector imaging using Labview software and get the relationship between the pitch and the coarse wavelength of the anode. Simultaneously, we get the corresponding electron cloud for the designing parameters. Based on the result of the simulation and the practical machining demand, a nine electrodes Vernier anode was designed and fabricated which has a pitch of 891 µm, insulation width of 25 µm, amplitude of 50 µm, coarse pixel numbers of 5. PMID:26964205

  17. Electrocatalysis of carbon anode in aluminium electrolysis

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The anodic overvoltage of the carbon anode in aluminum electrolysis isof the order of 0.6 V at normal current densities. However, it can be reduced somewhat by doping the anode carbon with various inorganic compounds. A new apparatus was designed to improve the precision of overvoltage measurements. Anodes were doped with MgAl2O4 and AlF3 both by impregnation of the coke and by adding powder, and the measured overvoltage was compared with that of undoped samples. For prebake type anodes baked at around 1150 oC, the anodic overvoltage was reduced by 40-60 mV, and for Soderberg type anodes, baked at 950 oC, by 60-80 mV.

  18. Improvement of the current capacity of Al-Zn-In anode by casting parameters and magnesium addition

    Energy Technology Data Exchange (ETDEWEB)

    Saremi, M.; Keyvani, A.; Sina, H.; Emamy, M. [Metallurgy and Materials Department, University of Tehran, P.O.Box 11365/4563, Tehran (Iran)

    2004-07-01

    In the present work the effects of mold temperature and casting temperature have been studied on the potential and current capacity of Al-Zn-In anodes. Electrochemical polarization and NACE standard methods were used to evaluate the anodic behavior, potential and current capacity of the anodes. It is shown that metallic molds having higher temperatures could provide better condition for obtaining homogenous structures with minor inclusions. The optimum condition of anode operation may be provided where mold and pouring temperatures equal to 400 and 710 deg. C respectively, in which a fine structure, phase distribution and lack of casting faults are obtained. Some alloying elements such as Mg, Mn, Ti, Zr, Sr are added to the base alloy in order to improve its efficiency together with its capacity. In this study the anodic behavior of influence of mold temperature and Al-Zn-In alloy at different concentration of magnesium of 1 to 4 wt. %, is studied. The result of experiments of this anode shows that 2 wt. % Mg, casting and mold temperature at 730 and 350 deg. C are obtained the consumption decrease from about 3.8 to 3.3 Kg.Ay{sup -1}. Anode capacity also increases and potential of this anode stands to about -1045 mV. (author)

  19. Plasmonic properties of gold-coated nanoporous anodic alumina with linearly organized pores

    Indian Academy of Sciences (India)

    Dheeraj Pratap; P Mandal; S Anantha Ramakrishna

    2014-12-01

    Anodization of aluminium surfaces containing linearly oriented scratches leads to the formation of nanoporous anodic alumina (NAA) with the nanopores arranged preferentially along the scratch marks. NAA, when coated with a thin gold film, support plasmonic resonances. Dark-field spectroscopy revealed that gold-coated NAA with such linearly arranged pores shows a polarization-dependent scattering, that is larger when the incident light is polarized parallel to the scratch direction than when polarized perpendicular to the scratch direction. Fluorescence studies from rhodamine-6G (R6G) molecules dissolved in polymethylmethacrylate (PMMA) and deposited on these NAA templates showed that fluorescence can be strongly enhanced with the bare NAA due to multiple light scattering in the NAA, while fluorescence from the molecules deposited on gold-coated NAA is strongly quenched due to the strong plasmonic coupling.

  20. Reactions on carbon anodes in aluminium electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Eidet, Trygve

    1997-12-31

    The consumption of carbon anodes and energy in aluminium electrolysis is higher than what is required theoretically. This thesis studies the most important of the reactions that consume anode materials. These reactions are the electrochemical anode reaction and the airburn and carboxy reactions. The first part of the thesis deals with the kinetics and mechanism of the electrochemical anode reaction using electrochemical impedance spectroscopy. The second part deals with air and carboxy reactivity of carbon anodes and studies the effects of inorganic impurities on the reactivity of carbon anodes in the aluminium industry. Special attention is given to sulphur since its effect on the carbon gasification is not well understood. Sulphur is always present in anodes, and it is expected that the sulphur content of available anode cokes will increase in the future. It has also been suggested that sulphur poisons catalyzing impurities in the anodes. Other impurities that were investigated are iron, nickel and vanadium, which are common impurities in anodes which have been reported to catalyze carbon gasification. 88 refs., 92 figs., 24 tabs.

  1. Rare Earth Application in Sealing Anodized Al-Based Metal Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new method for corrosion protection of Al-based metal matrixcomposites (MMC) was developed using two-step process, which involves anodizing in H2SO4 solution and sealing in rare earth solution. Corrosion resistance of the treated surface was evaluated with polarization curves.The results showed that the effect of the protection using rare earth sealing is equivalent to that using chromate sealing for Al6061/SiCp. The rare earth metal salt can be an alternative to the toxic chromate for sealing anodized Al MMC.

  2. Polarization, political

    NARCIS (Netherlands)

    M. Wojcieszak

    2015-01-01

    Polarization has been studied in three different forms: on a social, group, and individual level. This entry first focuses on the undisputed phenomenon of elite polarization (i.e., increasing adherence of policy positions among the elites) and also outlines different approaches to assessing mass pol

  3. A highly active anode functional layer for solid oxide fuel cells based on proton-conducting electrolyte BaZr0.1Ce0.7Y0.2O3-δ

    Science.gov (United States)

    Zhang, Xiuling; Qiu, Yu'e.; Jin, Feng; Guo, Feng; Song, Yulan; Zhu, Baoyong

    2013-11-01

    Extensive works have been performed to diminish cathode polarization for proton-conducting electrolyte based solid oxide fuel cells (SOFCs) while not much attention is paid to functional anode for improving electrochemical reaction at three-phase-boundaries (TPB). In this work, a highly active anode functional layer (FL) synthesized by a modified combustion method was employed to significantly elevate the cell performance at intermediate operation temperatures (550-650 °C). The effects of anode structure configuration, FL powder size and thickness on power outputs and electrode polarization were investigated. A maximum power density of 489 mW cm-2 and a low electrode polarization resistance of 0.37 Ω cm2 were achieved at 650 °C, indicating fuel gas transport and hydrogen oxidation reaction at TPB sites largely contribute to total cell resistance which could be effectively diminished by optimization of anodic interface environment with the adoption of highly active anode powders.

  4. Tailoring of anodic surface layer properties on titanium and its implant alloys for biomedical purposes

    Directory of Open Access Journals (Sweden)

    E. Krasicka-Cydzik

    2010-11-01

    Full Text Available and nanostructural titania and alloy component oxides. Evaluation of their properties for various biomedical applications in implantology and biosensing.Design/methodology/approach: Samples of titanium and its alloys were anodized in phosphoric acid solutions at different concentrations (0.5 ~ 4 M with or without additions according to appropriate polarization regimes. Anodized samples were characterized by SED+EDS, electrochemical and impedance (EIS tests and biocompability examination. Titanium and its alloys (Ti6Al4V and Ti6Al7Nb samples were also used to form the nanostructural layer (nanotubes by anodizing. The latter was used as a platform for glucose biosensing.Findings: Anodizing of titanium materials in phosphoric acid solutions allowed to obtain surface layers of various morphology and topography. They differ in porosity, thickness and chemical composition and according to their specific properties can be used in various biomedical applications. The development of gel-like layer and formation of nanotube layer was observed while anodizing in higher concentration of electrolyte or anodizing in the presence of fluorides. Both surface layers are much more bioactive than anodic barrier oxide layers on titanium. The primary tests to use nanostructured layer as platform for the third generation biosensors were promising.Practical implications: Use of medical implants covered with porous and nanostructural anodic layers tailored to particular biomedical purposes enables new practical applications in implantology and biosensing.Originality/value: Phosphate gel-like layer over surface oxide layer on titanium materials and nanostructural surface layer rich in both: phosphates and fluorides, are highly bioactive, which is the desirable property of implant materials.

  5. Polarization holography

    DEFF Research Database (Denmark)

    Nikolova, L.; Ramanujam, P.S.

    Current research into holography is concerned with applications in optically storing, retrieving, and processing information. Polarization holography has many unique properties compared to conventional holography. It gives results in high efficiency, achromaticity, and special polarization...... properties. This books reviews the research carried out in this field over the last 15 years. The authors provide basic concepts in polarization and the propagation of light through anisotropic materials, before presenting a sound theoretical basis for polarization holography. The fabrication and...... characterization of azobenzene based materials, which remain the most efficient for the purpose, is described in detail. This is followed by a description of other materials that are used in polarization holography. An in-depth description of various applications, including display holography and optical storage...

  6. Anode Sheath Switching in a Carbon Nanotube Arc Plasma

    International Nuclear Information System (INIS)

    The anode ablation rate is investigated as a function of anode diameter for a carbon nanotube arc plasma. It is found that anomalously high ablation occurs for small anode diameters. This result is explained by the formation of a positive anode sheath. The increased ablation rate due to this positive anode sheath could imply greater production rate for carbon nanotubes.

  7. Anode Sheath Switching in a Carbon Nanotube Arc Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Abe Fetterman, Yevgeny Raitses, and Michael Keidar

    2008-04-08

    The anode ablation rate is investigated as a function of anode diameter for a carbon nanotube arc plasma. It is found that anomalously high ablation occurs for small anode diameters. This result is explained by the formation of a positive anode sheath. The increased ablation rate due to this positive anode sheath could imply greater production rate for carbon nanotubes.

  8. Anodic Materials for Electrocatalytic Ozone Generation

    OpenAIRE

    Yun-Hai Wang; Qing-Yun Chen

    2013-01-01

    Ozone has wide applications in various fields. Electrocatalytic ozone generation technology as an alternative method to produce ozone is attractive. Anodic materials have significant effect on the ozone generation efficiency. The research progress on anodic materials for electrocatalytic ozone generation including the cell configuration and mechanism is addressed in this review. The lead dioxide and nickel-antimony-doped tin dioxide anode materials are introduced in detail, including their st...

  9. Modulation of Transmission Spectra of Anodized Alumina Membrane Distributed Bragg Reflector by Controlling Anodization Temperature

    OpenAIRE

    Zheng WenJun; Fei GuangTao; Wang Biao; Zhang Li

    2009-01-01

    Abstract We have successfully prepared anodized alumina membrane distributed Bragg reflector (DBR) using electrochemical anodization method. The transmission peak of this distributed Bragg reflector could be easily and effectively modulated to cover almost any wavelength range of the whole visible spectrum by adjusting anodization temperature.

  10. Modulation of Transmission Spectra of Anodized Alumina Membrane Distributed Bragg Reflector by Controlling Anodization Temperature

    Directory of Open Access Journals (Sweden)

    Zheng WenJun

    2009-01-01

    Full Text Available Abstract We have successfully prepared anodized alumina membrane distributed Bragg reflector (DBR using electrochemical anodization method. The transmission peak of this distributed Bragg reflector could be easily and effectively modulated to cover almost any wavelength range of the whole visible spectrum by adjusting anodization temperature.

  11. Enhanced corrosion resistance and biocompatibility of β-type Ti–25Nb–25Zr alloy by electrochemical anodization

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Her-Hsiung [Department of Dentistry, National Yang-Ming University, Taipei, 112 Taiwan (China); Graduate Institute of Basic Medical Science, China Medical University, Taichung, 404 Taiwan (China); Department of Biomedical Informatics, Asia University, Taichung, 413 Taiwan (China); Department of Stomatology, Taipei Veterans General Hospital, Taipei, 112 Taiwan (China); Wu, Chia-Ping; Sun, Ying-Sui; Huang, Hsun-Miao [Institute of Oral Biology, National Yang-Ming University, Taipei, 112 Taiwan (China); Lee, Tzu-Hsin, E-mail: biomaterials@hotmail.com [School of Dentistry, Chung Shan Medical University, Taichung, 402 Taiwan (China); Oral Medicine Center, Chung Shan Medical University Hospital, Taichung, 402 Taiwan (China)

    2013-12-31

    The biocompatibility of implants is largely determined by their surface characteristics. This study presents a novel method for performing electrochemical anodization on β-type Ti–25Nb–25Zr alloy with a low elastic modulus (approximately 70 GPa). This method results in a thin hybrid layer capable of enhancing the surface characteristics of the implants. We investigated the surface topography and microstructure of the resulting Ti–25Nb–25Zr alloy. The corrosion resistance was evaluated using potentiodynamic polarization curve measurements in simulated body fluid. The cytotoxicity was evaluated according to International Organization for Standardization 10993–5 specification. Cell adhesion of human bone marrow mesenchymal stem cells on the test specimens was observed using scanning electron microscopy and fluorescence microscopy. The anodization produced a thin (approximately 40 nm-thick) hybrid oxide layer with a nanoporous outer sublayer (pore size < 15 nm) and a dense inner layer. The thin hybrid oxide layer increased the corrosion resistance of the Ti–25Nb–25Zr alloy by increasing the corrosion potential and decreasing both the corrosion rate and passive current. Ti–25Nb–25Zr alloys with and without anodization treatment were non-toxic. Surface nanotopography on the anodized Ti–25Nb–25Zr alloy enhanced protein adsorption and cell adhesion. Our results demonstrate that electrochemical anodization increases the corrosion resistance and cell adhesion of β-type Ti–25Nb–25Zr alloy while providing a lower elastic modulus suitable for implant applications. - Highlights: • An electrochemical anodization was applied to β-type Ti–25Nb–25Zr alloy surface. • Anodized surface had nanoscale hybrid oxide layer. • Anodized surface increased corrosion resistance due to dense inner sublayer. • Anodized surface enhanced cell adhesion due to nanoporous outer sublayer. • Electrochemical anodization has potential as implant surface treatment.

  12. Enhanced corrosion resistance and biocompatibility of β-type Ti–25Nb–25Zr alloy by electrochemical anodization

    International Nuclear Information System (INIS)

    The biocompatibility of implants is largely determined by their surface characteristics. This study presents a novel method for performing electrochemical anodization on β-type Ti–25Nb–25Zr alloy with a low elastic modulus (approximately 70 GPa). This method results in a thin hybrid layer capable of enhancing the surface characteristics of the implants. We investigated the surface topography and microstructure of the resulting Ti–25Nb–25Zr alloy. The corrosion resistance was evaluated using potentiodynamic polarization curve measurements in simulated body fluid. The cytotoxicity was evaluated according to International Organization for Standardization 10993–5 specification. Cell adhesion of human bone marrow mesenchymal stem cells on the test specimens was observed using scanning electron microscopy and fluorescence microscopy. The anodization produced a thin (approximately 40 nm-thick) hybrid oxide layer with a nanoporous outer sublayer (pore size < 15 nm) and a dense inner layer. The thin hybrid oxide layer increased the corrosion resistance of the Ti–25Nb–25Zr alloy by increasing the corrosion potential and decreasing both the corrosion rate and passive current. Ti–25Nb–25Zr alloys with and without anodization treatment were non-toxic. Surface nanotopography on the anodized Ti–25Nb–25Zr alloy enhanced protein adsorption and cell adhesion. Our results demonstrate that electrochemical anodization increases the corrosion resistance and cell adhesion of β-type Ti–25Nb–25Zr alloy while providing a lower elastic modulus suitable for implant applications. - Highlights: • An electrochemical anodization was applied to β-type Ti–25Nb–25Zr alloy surface. • Anodized surface had nanoscale hybrid oxide layer. • Anodized surface increased corrosion resistance due to dense inner sublayer. • Anodized surface enhanced cell adhesion due to nanoporous outer sublayer. • Electrochemical anodization has potential as implant surface treatment

  13. Anodic corrosion of lead, tin and lead-tin alloys in sulphuric acid solutions. Doctoral thesis

    Energy Technology Data Exchange (ETDEWEB)

    Salmi, K.

    1993-01-01

    The electrochemical behavior of lead and tin and the effect of tin on the anodic behavior of lead in sulfuric acid solutions has been studied in relation to the corrosion of the positive grid of the lead acid battery. The release of soluble Pb(IV) species into sulfuric acid during the anodic polarization of lead has been mapped using the ring-disk electrode technique and their role in the electrochemistry of lead is discussed. Part of the tetravalent products formed on lead are reduced only at high negative potentials. The usefulness of the rotating ring-disk electrode for the determination of different soluble corrosion products has been demonstrated. Mechanisms for tin dissolution in different regions (open circuit, active dissolution and passive region) have been proposed. Ex situ surface analysis of the anodic layer formed on the tin electrode showed this to be mainly SnO.

  14. Performance of laboratory polymer electrolyte membrane hydrogen generator with sputtered iridium oxide anode

    Science.gov (United States)

    Labou, D.; Slavcheva, E.; Schnakenberg, U.; Neophytides, S.

    The continuous improvement of the anode materials constitutes a major challenge for the future commercial use of polymer electrolyte membranes (PEM) electrolyzers for hydrogen production. In accordance to this direction, iridium/titanium films deposited directly on carbon substrates via magnetron sputtering are operated as electrodes for the oxygen evolution reaction interfaced with Nafion 115 electrolyte in a laboratory single cell PEM hydrogen generator. The anode with 0.2 mg cm -2 Ir catalyst loading was electrochemically activated by cycling its potential value between 0 and 1.2 V (vs. RHE). The water electrolysis cell was operated at 90 °C with current density 1 A cm -2 at 1.51 V without the ohmic contribution. The corresponding current density per mgr of Ir catalyst is 5 A mg -1. The achieved high efficiency is combined with sufficient electrode stability since the oxidation of the carbon substrate during the anodic polarization is almost negligible.

  15. Performance Factors and Sulfur Tolerance of Metal Supported Solid Oxide Fuel Cells with Nanostructured Ni:GDC Infiltrated Anodes

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Sudireddy, Bhaskar Reddy; Hagen, Anke;

    2016-01-01

    Two metal supported solid oxide fuel cells (active area 16 cm2) with nanostructured Ni:GDC infiltrated anodes, possessing different anode and support microstructures were studied in respect to sulfur tolerance at an operating temperature of 650°C. The studied MS-SOFCs are based on ferretic...... stainless steel (FeCr) and showed excellent performance characteristics at 650°C with fuel utilization corrected area specific resistances of 0.35 Ωcm2 and 0.7 Ωcm2 respectively. The sulfur tolerance testing was performed by periodic addition of 2, 5, and 10 ppm H2S in hydrogen based fuel under...... galvanostatic operation at a current load of 0.25 Acm−2. The results were compared with literature on the sulfur tolerance of conventional SOFC Ni/YSZ cermet anode. The comparison in terms of absolute cell resistance increase and relative anode polarization resistance increase indicates, that the nanostructured...

  16. Structured SiCu thin films in LiB as anodes

    International Nuclear Information System (INIS)

    Both helical and inclined columnar Si–10 at.% Cu structured thin films were deposited on Cu substrates using glancing angle deposition (GLAD) technique. In order to deposit Cu and Si two evaporation sources were used. Ion assistance was utilized in the first 5 min of the GLAD to enhance the adhesion and the density of the films. These films were characterized by thin film XRD, GDOES, SEM, and EDS. Electrochemical characterizations were made by testing the thin films as anodes in half-cells for 100 cycles. The results showed that the columnar SiCu thin film delivered 2200 mAh g−1, where the helical one exhibited 2600 mAh g−1, and, their initial coulombic efficiencies were found to be 38%–50% respectively. For the columnar and the helical thin film anodes, sustainable 520 and 800 mAh g−1 with 90% and 99% coulombic efficiencies were achieved for 100 cycles. These sustainable capacities showed the importance of the thin film structure having nano-sized crystals and amorphous particles. The higher surface area of the helices increases the capacity of the electrode because the contact area of the thin film anode with Li ions is increased, and the polarization which otherwise forms on the anode surface due to SEI formation is decreased. In addition, because of larger interspaces between the helices the ability of the anode to accommodate the volumetric changes is improved, which results in a higher coulombic efficiency and capacity retention during cycling test. - Highlights: • Cu and Si atoms were co-evaporated to form composite thin film. • GLAD is an alternative method to form new electrodes for LIB. • Uses of the composite helices and nanocolumns as anodes were shown experimentally. • IAD was used to improve the adhesion of the structured thin films. • High surface area, porosities and Cu presence improve the Si anode performance

  17. High-performance anode-supported solid oxide fuel cell with impregnated electrodes

    Science.gov (United States)

    Osinkin, D. A.; Bogdanovich, N. M.; Beresnev, S. M.; Zhuravlev, V. D.

    2015-08-01

    The 61%NiO + 39%Zr0.84Y0.16O1.92 (NiO-YSZ) and 56%NiO + 44%Zr0.83Sc0.16Ce0.01O1.92 (NiO-CeSSZ) composite powders have been prepared using two-steps and one-step combustion synthesis, respectively. The Ni-YSZ anode substrate with a low level of electrical resistance (less than 1 mOhm cm) and porosity of about 53% in the reduced state was fabricated. The functional layer of the anode with the high level of electrochemical activity was made of NiO-CeSSZ. The single anode-supported solid oxide fuel cell with the bi-layer Ni-cermet anode, Zr0.84Sc0.16O1.92 film electrolyte and the Pt + 3% Zr0.84Y0.16O1.92 cathode was fabricated. The power density and the U-I curves of the fuel cell at initial state and after impregnation of the cathode and anode by praseodymium and cerium oxides, respectively, have been measured at different temperatures. The maximum of power density of the initial fuel cell was 0.35 W cm-2 at conditions of wet hydrogen (air) supply to the anode (cathode) at 900 °C. After the electrodes were impregnated, the value of power density increased by seven times and was approximately 2.4 W cm-2 at 0.6 V. It was suggested that after the electrodes impregnation the polarization resistance of the fuel cell was determined by the gas diffusion in the supported anode.

  18. Facile incorporation of hydroxyapatite onto an anodized Ti surface via a mussel inspired polydopamine coating

    Science.gov (United States)

    Zhe, Wang; Dong, Chaofang; Sefei, Yang; Dawei, Zhang; Kui, Xiao; Xiaogang, Li

    2016-08-01

    Inspired by the porous morphology of anodized Ti and the adhesive versatility of polydopamine (PDA), which can induce apatite mineralization, we fabricated a novel interface by coating a porous anodized TiO2 layer with PDA to rapidly immobilize HA on Ti-based substrates. It was found that the as-prepared PDA/anodized (HD) surface exhibited nanoscale roughness, which possessed an excellent ability to form apatite when immersed in 1.5× simulated body fluid (SBF), as observed by AFM and FE-SEM. The morphology and composition of each layer were further confirmed by XPS, XRD and FTIR. The corrosion resistance of the multilayer was investigated using potentiodynamic polarization curve and electrochemical impedance spectra (EIS) measurements in a 0.9 wt% NaCl solution, the results suggested that the HA/PDA/anodized (HDA) layer increased the corrosion resistance of pure Ti with higher corrosion potential and lower passive current, the surface wettability was also enhanced with the incorporation of HA. In vitro cellular assays showed that the HDA layer stimulated cell attachment and improved the alkaline phosphate (ALP) activity. Overall, the PDA/anodized treatment provided a viable method to quickly integrate HA, and the obtained HDA layer improved both corrosion resistance and biocompatibility of the Ti surface.

  19. Effects Of Anodic Protection On SCC Behavior Of X80 Pipeline Steel In High-pH Carbonate-Bicarbonate Solution

    Directory of Open Access Journals (Sweden)

    Zhao W.

    2015-06-01

    Full Text Available The potentiodynamic polarization test and slow strain rate tensile tests of X80 pipeline steel were performed in 0.5M Na2CO3-1M NaHCO3 solution to study the electrochemical and stress corrosion cracking properties. The results of potentiodynamic polarization test show that there is an obvious stable passive region, about from 0v to 0.8V (SCE, indicating that anodic protection is feasible. The results of slow strain rate tensile tests show that the stress corrosion cracking sensibility is high and cathodic protection effect is restricted due to the hydrogen permeation. However, the elongation, yielding strength and tensile strength all increase with anodic protection. The higher anodic protection potential in the stable passive region is benefit to improve tensile strength and yielding strength. However, the higher elongation is obtained at 0.5V (SCE anodic protection potential.

  20. Application of in situ digital holography to the study of the effect of a magnetic field on the anodic dissolution of iron in thichloroacetic acid

    Directory of Open Access Journals (Sweden)

    XUEGENG YANG

    2006-01-01

    Full Text Available The effect of a magnetic field on the anodic dissolution of iron in 1.0 mol dm-3 trichloroacetic acid solution was studied by the potentiodynamic polarization method and in situ digital holography. It was found that the magnetohydrodynamic force increased the mass transport, which resulted in a faster anodic dissolution of iron. The effect of the magnetic field was analyzed by holograms and is discussed in terms of the magnetohydrodynamic force.

  1. The Nitrogen-Nitride Anode.

    Energy Technology Data Exchange (ETDEWEB)

    Delnick, Frank M.

    2014-10-01

    Nitrogen gas N 2 can be reduced to nitride N -3 in molten LiCl-KCl eutectic salt electrolyte. However, the direct oxidation of N -3 back to N 2 is kinetically slow and only occurs at high overvoltage. The overvoltage for N -3 oxidation can be eliminated by coordinating the N -3 with BN to form the dinitridoborate (BN 2 -3 ) anion which forms a 1-D conjugated linear inorganic polymer with -Li-N-B-N- repeating units. This polymer precipitates out of solution as Li 3 BN 2 which becomes a metallic conductor upon delithiation. Li 3 BN 2 is oxidized to Li + + N 2 + BN at about the N 2 /N -3 redox potential with very little overvoltage. In this report we evaluate the N 2 /N -3 redox couple as a battery anode for energy storage.

  2. Characterization of native and anodic oxide films formed on commercial pure titanium using electrochemical properties and morphology techniques

    International Nuclear Information System (INIS)

    Potentiostatically anodized oxide films on the surface of commercial pure titanium (cp-Ti) formed in sulfuric (0.5 M H2SO4) and in phosphoric (1.4 M H3PO4) acid solutions under variables anodizing voltages were investigated and compared with the native oxide film. Potentiodynamic polarization and electrochemical impedance spectroscopy, EIS, were used to predicate the different in corrosion behavior of the oxide film samples. Scanning electron microscope, SEM, and electron diffraction X-ray analysis, EDX, were used to investigate the difference in the morphology between different types of oxide films. The electrochemical characteristics were examined in phosphate saline buffer solution, PSB (pH 7.4) at 25 deg. C. Results have been shown that the nature of the native oxide film is thin and amorphous, while the process of anodization of Ti in both acid solutions plays an important role in changing the properties of passive oxide films. Significant increase in the corrosion resistance of the anodized surface film was recorded after 3 h of electrode immersion in PSB. On the other side, the coverage (θ) of film formed on cp-Ti was differed by changing the anodized acid solution. Impedance results showed that both the native film and anodized film formed on cp-Ti consist of two layers. The resistance of the anodized film has reached to the highest value by anodization of cp-Ti in H3PO4 and the inner layer in the anodized film formed in both acid solutions is also porous.

  3. Conductive Anodic Filament (CAF) Formation

    Science.gov (United States)

    Caputo, Antonio

    Conductive anodic filament (CAF) is a failure mode in printed wiring boards (PWBs) which occurs under high humidity and high voltage gradient conditions. The filament, a copper salt, grows from anode to cathode along the epoxy-glass interface. Ready and Turbini (2000) identified this copper salt as the Cu 2(OH)3Cl, atacamite compound. This work has investigated the influence of polyethylene glycol (PEG) and polyethylene propylene glycol (PEPG) fluxing agents on the chemical nature of CAF. For coupons processed with PEPG flux, with and without chloride, a copper-chloride containing compound was formed in the polymer matrix. This compound was characterized using x-ray photoelectron spectroscopy (XPS) as CuCl and an electrochemical mechanism for the formation of the chloride-containing CAF has been proposed. For PEG flux, with and without chloride, it has been shown that CAF only formed, but no copper containing compound formed in the matrix. It appears for PEG fluxed coupons, a PEG-Cu-Cl complex forms, binds the available Cu and acts as a barrier to the formation of CuCl in the polymer matrix. Meeker and Lu Valle (1995) have previously proposed that CAF failure is best represented by two competing reactions -- the formation of a copper chloride corrosion compound (now identified as Cu2(OH)3Cl) and the formation of innocuous trapped chlorine compounds. Since no evidence of any trapped chloride compounds has been found, we propose that the formation of CAF is best represented by a single non-reversible reaction. For coupons processed with a high bromide-containing flux, bromide containing CAF was created and characterized using transmission electron microscopy (TEM) to be Cu2(OH)3Br. In addition, a copper-containing compound was formed in the polymer matrix and characterized using XPS as CuBr. An electrochemical mechanism for the formation of bromide-containing CAF has been proposed based on the XPS data.

  4. Corrosion Behavior of the Rare Earth Sealing Anodized Coating on Aluminum Alloy LY12

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Technological process of rare earth sealing anodized LY12 (2024) alloy is introduced. Corrosion behavior of the filmwas studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results showed that thecoating remained passivity at the potential range from the open circuit potential (-780 mV) to -250 mV in NaClsolution. When the potential exceeded -200 mV, corrosion reaction happened on the coating. the results of ElSanalysis was consistent with the results of polarization curves.

  5. Anodic behaviour of the stainless steel AISI 430 in aqueous solutions of chloride and sulphate ions

    International Nuclear Information System (INIS)

    The kinetics of the dissolution of stainless steel AISI 430 in the presence of chloride and sulphate ions has been studied in terms of the ion concentration, the pH variation, and the velocity of the working electrode. The experimental method utilized was the potentiostatic anodic polarization, and the reactants used were NaCl and Na2 SO4 at room temperature. Atomic Absorption spectrophotometry and Auger Electrons spectroscopy (AES) analyses were made in order to support the interpretation of results obtained by means of the potentiostatic polarization method. (author)

  6. Polar Stratigraphy

    Science.gov (United States)

    1999-01-01

    These three images were taken on three different orbits over the north polar cap in April 1999. Each shows a different part of the same ice-free trough. The left and right images are separated by a distance of more than 100 kilometers (62 miles). Note the similar layers in each image.

  7. A novel CZT detector using strengthened electric field line anode

    Science.gov (United States)

    Fu, Jian-Qiang; Li, Yu-Lan; Zhang, Lan; Niu, Li-Bo; Jiang, Hao; Li, Yuan-Jing

    2014-12-01

    In this paper, we report on the design, simulation and testing of a novel CZT detector with an electrode named the Strengthened Electric Field Line Anode (SEFLA). The Strengthened Electric Field (SEF) technique and Single Polarity Charge Sensing (SPCS) technique are implemented. It could achieve the same performance as Coplanar Grid, Pixel Array CZT detectors but requires only a simple readout system. Geant4, Ansoft Maxwell and a self-developed Induced Current Calculator (ICC) package are used to develop an understanding of how the energy spectrum is formed, and the parameters of the detector are optimized. A prototype is fabricated. Experimental results demonstrate the effectiveness of this design. The test shows that the SEFLA detector achieves a FWHM of 6.0% @59.5 keV and 1.6% @662 keV, which matches well with the simulations.

  8. Chemo-mechanical softening during in situ nanoindentation of anodic porous alumina with anodization processing

    OpenAIRE

    Cheng, C; Ngan, AHW

    2013-01-01

    Simultaneous application of mechanical stresses on a material as it undergoes an electrochemical reaction can result in interesting coupling effects between the chemical and mechanical responses of the material. In this work, anodic porous alumina supported on Al is found to exhibit significant softening during in situ nanoindentation with anodization processing. Compared with ex situ nanoindentation without anodization processing, the in situ hardness measured on the alumina is found to be m...

  9. Macrokinetic relationships between anodic processes in chlorine electrolysis on ruthenium-titanium oxide anodes

    International Nuclear Information System (INIS)

    Effect of porosity on kinetics of the main (chlorine evolution) and side (oxygen evolution and anodic dissolution of ruthenium dioxide) reactions for chlorine electrolysis conditions has been analyzed. Making allowance for chlorine hydrolysis secondary reaction, the distribution of chlorine concentration, solution pH and current densities of the main and side processes over the porous anode depth, have been found. It is shown that solution acidification in the anode pores due to chlorine hydrolysis can bring about replacement of oxygen evolution and ruthenium dioxide dissolution side reactions toward the porous anode external sides thus affecting its selectivity and corrosion resistance

  10. Electrochemically exfoliated graphene anodes with enhanced biocurrent production in single-chamber air-breathing microbial fuel cells.

    Science.gov (United States)

    Najafabadi, Amin Taheri; Ng, Norvin; Gyenge, Előd

    2016-07-15

    Microbial fuel cells (MFCs) present promising options for environmentally sustainable power generation especially in conjunction with waste water treatment. However, major challenges remain including low power density, difficult scale-up, and durability of the cell components. This study reports enhanced biocurrent production in a membrane-free MFC, using graphene microsheets (GNs) as anode and MnOx catalyzed air cathode. The GNs are produced by ionic liquid assisted simultaneous anodic and cathodic electrochemical exfoliation of iso-molded graphite electrodes. The GNs produced by anodic exfoliation increase the MFC peak power density by over 300% compared to plain carbon cloth (i.e., 2.85Wm(-2) vs 0.66Wm(-2), respectively), and by 90% compared to conventional carbon black (i.e., Vulcan XC-72) anode. These results exceed previously reported power densities for graphene-containing MFC anodes. The fuel cell polarization results are corroborated by electrochemical impedance spectroscopy indicating three times lower charge transfer resistance for the GN anode. Material characterizations suggest that the best performing GN samples were of relatively smaller size (~500nm), with higher levels of ionic liquid induced surface functionalization during the electrochemical exfoliation process.

  11. Electrochemically exfoliated graphene anodes with enhanced biocurrent production in single-chamber air-breathing microbial fuel cells.

    Science.gov (United States)

    Najafabadi, Amin Taheri; Ng, Norvin; Gyenge, Előd

    2016-07-15

    Microbial fuel cells (MFCs) present promising options for environmentally sustainable power generation especially in conjunction with waste water treatment. However, major challenges remain including low power density, difficult scale-up, and durability of the cell components. This study reports enhanced biocurrent production in a membrane-free MFC, using graphene microsheets (GNs) as anode and MnOx catalyzed air cathode. The GNs are produced by ionic liquid assisted simultaneous anodic and cathodic electrochemical exfoliation of iso-molded graphite electrodes. The GNs produced by anodic exfoliation increase the MFC peak power density by over 300% compared to plain carbon cloth (i.e., 2.85Wm(-2) vs 0.66Wm(-2), respectively), and by 90% compared to conventional carbon black (i.e., Vulcan XC-72) anode. These results exceed previously reported power densities for graphene-containing MFC anodes. The fuel cell polarization results are corroborated by electrochemical impedance spectroscopy indicating three times lower charge transfer resistance for the GN anode. Material characterizations suggest that the best performing GN samples were of relatively smaller size (~500nm), with higher levels of ionic liquid induced surface functionalization during the electrochemical exfoliation process. PMID:26926591

  12. Ultraviolet photoluminescence of porous anodic alumina films

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Photoluminescence (PL) properties of porous anodic alumina (PAA) films prepared by using electrochemical anodization technique in a mixed solution of oxalic and sulfuric acid have been investigated. The PAA films have an intensive ultraviolet PL emission around 350 nm, of which a possible PL mechanism has been proposed. It was found that the incorporated oxalic ions, which could transform into PL centers and exist in the PAA films, are responsible for this ultraviolet PL emission.

  13. Lithium Ion Battery Anode Aging Mechanisms

    Directory of Open Access Journals (Sweden)

    Victor Agubra

    2013-03-01

    Full Text Available Degradation mechanisms such as lithium plating, growth of the passivated surface film layer on the electrodes and loss of both recyclable lithium ions and electrode material adversely affect the longevity of the lithium ion battery. The anode electrode is very vulnerable to these degradation mechanisms. In this paper, the most common aging mechanisms occurring at the anode during the operation of the lithium battery, as well as some approaches for minimizing the degradation are reviewed.

  14. Improvement of rate capability of spinel lithium titanate anodes using microwave-assisted zinc nanocoating

    International Nuclear Information System (INIS)

    Highlights: ► Microwave-assisted Zn layers onto Li4Ti5O12 crystals serves as superior anode materials. ► Microwave heating is capable of depositing Zn layers over the surface of spinel Li4Ti5O12 within 6 min. ► The thickness of Zn layer is an increasing function of zinc nitrate concentration. ► The deposition of Zn coating shows a positive effect on the rate-capability improvement of anodes. - Abstract: In this study, the deposition of microwave-assisted Zn layers onto spinel lithium titanate (Li4Ti5O12) crystals as superior anode materials for Li-ion batteries has been investigated. Microwave heating is capable of rapidly depositing Zn layers over the surface of spinel Li4Ti5O12 within 6 min. The thickness of Zn layer (i.e., 1–10 nm) is an increasing function of zinc nitrate concentration under the microwave irradiation. The charge–discharge curve of Zn–Li4Ti5O12 anode still maintains the plateau at 1.5 V, contributing to the major portion in the overall specific capacity. The presence of Zn coating significantly facilitates the capacity retention (78.1% at 10 C/0.2 C) of the composite anodes with high Coulombic efficiency (>99.9%), indicating an excellent reversibility of insertion/de-insertion of Li ions. This can be ascribed to the fact that well-dispersed Zn layer offers an electronic pathway over the Li4Ti5O12 powder, thus imparting electronic conduction and reducing cell polarization. Accordingly, the deposition of Zn coating, prepared by the rapid microwave heating, shows a positive effect on the rate-capability improvement of Li4Ti5O12 anodes.

  15. Solar Polar Rays Are Not Polar

    Science.gov (United States)

    Li, J.; Jewitt, D.; Labonte, B.; Acton, L.

    In this poster we discuss the nature of polar rays, based on limb synoptic images constructed from Yohkoh/SXT and SOHO/EIT data. In the literature, polar rays and polar plumes are often mentioned interchangably. We find that polar rays are projection effects caused by hot plasma from equatorial active areas and are not physically associated with the coronal polar holes. Instead, the rise in number and strength of polar rays toward solar activity maximum is responsible for hiding the polar holes and polar plumes. We will present the limb synoptic maps and simple physical models to lead to this result.

  16. Electrical and Mechanical Performance of Carbon Fiber-Reinforced Polymer Used as the Impressed Current Anode Material

    Directory of Open Access Journals (Sweden)

    Ji-Hua Zhu

    2014-07-01

    Full Text Available An investigation was performed by using carbon fiber-reinforced polymer (CFRP as the anode material in the impressed current cathodic protection (ICCP system of steel reinforced concrete structures. The service life and performance of CFRP were investigated in simulated ICCP systems with various configurations. Constant current densities were maintained during the tests. No significant degradation in electrical and mechanical properties was found for CFRP subjected to anodic polarization with the selected applied current densities. The service life of the CFRP-based ICCP system was discussed based on the practical reinforced concrete structure layout.

  17. Spectrophotometric study of the anodic corrosion of Ti/RuO{sub 2} electrode in acid sulfate solution

    Energy Technology Data Exchange (ETDEWEB)

    Gajic-Krstajic, Lj.M.; Trisovic, T.Lj.; Krstajic, N.V

    2004-01-01

    Electrochemical properties of RuO{sub 2}-based electrode, particularly the oxygen evolution and anodic dissolution of RuO{sub 2} have been investigated in 0.5 mol dm{sup -3} H{sub 2}SO{sub 4} solution by means of polarization measurements and product analysis. It has been demonstrated that it is possible to determine very low concentration of dissolved ruthenium species (8 x 10{sup -10} mol dm{sup -3} Ru) by a sensitive spectrophotometric method based on the ruthenium-catalyzed ceric-arsenite reaction. Finally, the probable mechanism of anodic dissolution of RuO{sub 2}-based electrode, has been proposed.

  18. Improvement of corrosion resistance of AZ31 Mg alloy by anodizing with co-precipitation of cerium oxide

    Institute of Scientific and Technical Information of China (English)

    Salah Abdelghany SALMAN; Ryoichi ICHINO; Masazumi OKIDO

    2009-01-01

    Anodizing of AZ31 Mg alloy in NaOH solution by co-precipitation of cerium oxide was investigated. The chemical composition and phase structure of the coating film were determined via optical microscopy, SEM and XRD. The corrosion properties of the anodic film were characterized by using potentiodynamic polarization curves in 17 mmol/L NaCl and 0.1 mol/L Na2SO4 solution at 298 K. The corrosion resistance of AZ31 magnesium alloy is significantly improved by adding cerium oxide to alkaline solution. In addition, the surface properties are enhanced and the film contains no crack.

  19. Synthesis, Characterization, and Optimization of Novel Solid Oxide Fuel Cell Anodes

    Science.gov (United States)

    Miller, Elizabeth C.

    (SLT) anode supports, thin La1--xSr x Ga0.8Mg0.2O3 (x = 0.1, 0.2) dense electrolytes, and porous LSGM anode functional layers. The SLT support and the LSGM functional layer are infiltrated with nanoscale Ni, creating extensive electrochemically active triple phase boundary area. The scope of the work presented here encompasses every step of cell development including powder synthesis, optimization of firing conditions, and long-term stability testing. Using an optimized fabrication process, cells with power density > 1.2 W cm-2 were fabricated. Dry pressing and colloidal de-position were used to make the first generation of these cells, and once suitable times and temperatures were determined, the process was shifted to tape casting to make larger batches of uniform cells. After obtaining initial results of low anode polarization resistance and high power density, the long-term stability of the Ni-infiltrated anodes was examined. A coarsening model was developed using the data from accelerated degradation tests to predict cell performance over a typical device lifetime. This thesis encompasses a broad range of novel SOFC anode materials, each of which has its own strengths and weaknesses. Presenting several possible avenues for SOFC development provides a complete picture of the ?eld and its current focuses. The wide scope of this work offers multiple solutions for the SOFC community and demonstrates that SOFCs are a strong candidate for meeting the United States' need for energy conversion and storage.

  20. New High-Energy Nanofiber Anode Materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiangwu; Fedkiw, Peter; Khan, Saad; Huang, Alex; Fan, Jiang

    2013-11-15

    The overall goal of the proposed work was to use electrospinning technology to integrate dissimilar materials (lithium alloy and carbon) into novel composite nanofiber anodes, which simultaneously had high energy density, reduced cost, and improved abuse tolerance. The nanofiber structure allowed the anodes to withstand repeated cycles of expansion and contraction. These composite nanofibers were electrospun into nonwoven fabrics with thickness of 50 μm or more, and then directly used as anodes in a lithium-ion battery. This eliminated the presence of non-active materials (e.g., conducting carbon black and polymer binder) and resulted in high energy and power densities. The nonwoven anode structure also provided a large electrode-electrolyte interface and, hence, high rate capacity and good lowtemperature performance capability. Following are detailed objectives for three proposed project periods. • During the first six months: Obtain anodes capable of initial specific capacities of 650 mAh/g and achieve ~50 full charge/discharge cycles in small laboratory scale cells (50 to 100 mAh) at the 1C rate with less than 20 percent capacity fade; • In the middle of project period: Assemble, cycle, and evaluate 18650 cells using proposed anode materials, and demonstrate practical and useful cycle life (750 cycles of ~70% state of charge swing with less than 20% capacity fade) in 18650 cells with at least twice improvement in the specific capacity than that of conventional graphite electrodes; • At the end of project period: Deliver 18650 cells containing proposed anode materials, and achieve specific capacities greater than 1200 mAh/g and cycle life longer than 5000 cycles of ~70% state of charge swing with less than 20% capacity fade.

  1. Controlling the occurrence of power overshoot by adapting microbial fuel cells to high anode potentials

    KAUST Repository

    Zhu, Xiuping

    2013-04-01

    Power density curves for microbial fuel cells (MFCs) often show power overshoot, resulting in inaccurate estimation of MFC performance at high current densities. The reasons for power overshoot are not well understood, but biofilm acclimation and development are known factors. In order to better explore the reasons for power overshoot, exoelectrogenic biofilms were developed at four different anode potentials (-0.46 V, -0.24 V, 0 V, and 0.50 V vs. Ag/AgCl), and then the properties of the biofilms were examined using polarization tests and cyclic voltammetry (CV). The maximum power density of the MFCs was 1200±100 mW/m2. Power overshoot was observed in MFCs incubated at -0.46 V, but not those acclimated atmore positive potentials, indicating that bacterial activitywas significantly influenced by the anode acclimation potential. CV results further indicated that power overshoot of MFCs incubated at the lowest anode potential was associatedwith a decreasing electroactivity of the anodic biofilm in the high potential region,which resulted from a lack of sufficient electron transfer components to shuttle electrons at rates needed for these more positive potentials. © 2012 Elsevier B.V.

  2. Air-Impregnated Nanoporous Anodic Aluminum Oxide Layers for Enhancing the Corrosion Resistance of Aluminum.

    Science.gov (United States)

    Jeong, Chanyoung; Lee, Junghoon; Sheppard, Keith; Choi, Chang-Hwan

    2015-10-13

    Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance. PMID:26393523

  3. Hierarchically ordered self-lubricating superhydrophobic anodized aluminum surfaces with enhanced corrosion resistance.

    Science.gov (United States)

    Vengatesh, Panneerselvam; Kulandainathan, Manickam Anbu

    2015-01-28

    Herein, we report a facile method for the fabrication of self-lubricating superhydrophobic hierarchical anodic aluminum oxide (AAO) surfaces with improved corrosion protection, which is greatly anticipated to have a high impact in catalysis, aerospace, and the shipping industries. This method involves chemical grafting of as-formed AAO using low surface free energy molecules like long chain saturated fatty acids, perfluorinated fatty acid (perfluorooctadecanoic acid, PFODA), and perfluorosulfonicacid-polytetrafluoroethylene copolymer. The pre and post treatment processes in the anodization of aluminum (Al) play a vital role in the grafting of fatty acids. Wettability and surface free energy were analyzed using a contact angle meter and achieved 161.5° for PFODA grafted anodized aluminum (PFODA-Al). This study was also aimed at evaluating the surface for corrosion resistance by Tafel polarization and self-lubricating properties by tribological studies using a pin-on-disc tribometer. The collective results showed that chemically grafted AAO nanostructures exhibit high corrosion resistance toward seawater and low frictional coefficient due to low surface energy and self-lubricating property of fatty acids covalently linked to anodized Al surfaces. PMID:25529561

  4. Air-Impregnated Nanoporous Anodic Aluminum Oxide Layers for Enhancing the Corrosion Resistance of Aluminum.

    Science.gov (United States)

    Jeong, Chanyoung; Lee, Junghoon; Sheppard, Keith; Choi, Chang-Hwan

    2015-10-13

    Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance.

  5. Analysis of carbon fiber brush loading in anodes on startup and performance of microbial fuel cells

    KAUST Repository

    Hutchinson, Adam J.

    2011-11-01

    Flat carbon anodes placed near a cathode in a microbial fuel cell (MFC) are adversely affected by oxygen crossover, but graphite fiber brush anodes placed near the cathode produce high power densities. The impact of the brush size and electrode spacing was examined by varying the distance of the brush end from the cathode and solution conductivity in multiple MFCs. The startup time was increased from 8 ± 1 days with full brushes (all buffer concentrations) to 13 days (50 mM), 14 days (25 mM) and 21 days (8 mM) when 75% of the brush anode was removed. When MFCs were all first acclimated with a full brush, up to 65% of the brush material could be removed without appreciably altering maximum power. Electrochemical impedance spectroscopy (EIS) showed that the main source of internal resistance (IR) was diffusion resistance, which together with solution resistance reached 100 Ω. The IR using EIS compared well with that obtained using the polarization data slope method, indicating no major components of IR were missed. These results show that using full brush anodes avoids adverse effects of oxygen crossover during startup, although brushes are much larger than needed to sustain high power. © 2011 Elsevier B.V.

  6. Investigation of residual anode material after electrorefining uranium in molten chloride salt

    Science.gov (United States)

    Rose, M. A.; Williamson, M. A.; Willit, J.

    2015-12-01

    A buildup of material at uranium anodes during uranium electrorefining in molten chloride salts has been observed. Potentiodynamic testing has been conducted using a three electrode cell, with a uranium working electrode in both LiCl/KCl eutectic and LiCl each containing ∼5 mol% UCl3. The anodic current response was observed at 50° intervals between 450 °C and 650 °C in the eutectic salt. These tests revealed a buildup of material at the anode in LiCl/KCl salt, which was sampled at room temperature, and analyzed using ICP-MS, XRD and SEM techniques. Examination of the analytical data, current response curves and published phase diagrams has established that as the uranium anode dissolves, the U3+ ion concentration in the diffusion layer surrounding the electrode rises precipitously to levels, which may at low temperatures exceed the solubility limit for UCl3 or in the case of the eutectic salt for K2UCl5. The reduction in current response observed at low temperature in eutectic salt is eliminated at 650 °C, where K2UCl5 is absent due to its congruent melting and only simple concentration polarization effects are seen. In LiCl similar concentration effects are seen though significantly longer time at applied potential is required to effect a reduction in the current response as compared to the eutectic salt.

  7. Porous and mesh alumina formed by anodization of high purity aluminum films at low anodizing voltage

    Energy Technology Data Exchange (ETDEWEB)

    Abd-Elnaiem, Alaa M., E-mail: alaa.abd-elnaiem@science.au.edu.eg [KACST-Intel Consortium Center of Excellence in Nano-manufacturing Applications (CENA), Riyadh (Saudi Arabia); Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Mebed, A.M. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Department of Physics, Faculty of Science, Al-Jouf University, Sakaka 2014 (Saudi Arabia); El-Said, Waleed Ahmed [Department of Chemistry, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Abdel-Rahim, M.A. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt)

    2014-11-03

    Electrochemical oxidation of high-purity aluminum (Al) films under low anodizing voltages (1–10) V has been conducted to obtain anodic aluminum oxide (AAO) with ultra-small pore size and inter-pore distance. Different structures of AAO have been obtained e.g. nanoporous and mesh structures. Highly regular pore arrays with small pore size and inter-pore distance have been formed in oxalic or sulfuric acids at different temperatures (22–50 °C). It is found that the pore diameter, inter-pore distance and the barrier layer thickness are independent of the anodizing parameters, which is very different from the rules of general AAO fabrication. The brand formation mechanism has been revealed by the scanning electron microscope study. Regular nanopores are formed under 10 V at the beginning of the anodization and then serve as a template layer dominating the formation of ultra-small nanopores. Anodization that is performed at voltages less than 5 V leads to mesh structured alumina. In addition, we have introduced a simple one-pot synthesis method to develop thin walls of oxide containing lithium (Li) ions that could be used for battery application based on anodization of Al films in a supersaturated mixture of lithium phosphate and phosphoric acid as matrix for Li-composite electrolyte. - Highlights: • We develop anodic aluminum oxide (AAO) with small pore size and inter-pore distance. • Applying low anodizing voltages onto aluminum film leads to form mesh structures. • The value of anodizing voltage (1–10 V) has no effect on pore size or inter-pore distance. • Applying anodizing voltage less than 5 V leads to mesh structured AAO. • AAO can be used as a matrix for Li-composite electrolytes.

  8. Influence of Polarization of the Incident Beam on Integrated Intensities in X-Ray Energy-Dispersive Diffractometry

    DEFF Research Database (Denmark)

    Olsen, J. Staun; Buras, B.; Jensen, T.;

    1978-01-01

    Polarization measurements of the primary X-ray beam produced by thick copper and tungsten anodes are reported and formulas derived for integrated intensities of Bragg reflections in energy-dispersive diffractometry with the polarization of the primary beam taken into account. It was found that for...... photon energies and at scattering angles close to 90...

  9. Electric current characteristic of anodic bonding

    International Nuclear Information System (INIS)

    In this paper, a novel current–time model of anodic bonding is proposed and verified experimentally in order to investigate underlying mechanisms of anodic bonding and to achieve real-time monitoring of bonding procedure. The proposed model provides a thorough explanation for the electric current characteristic of anodic bonding. More significantly, it explains two issues which other models cannot explain. One is the sharp rise in current when a voltage is initially applied during anodic bonding. The other is the unexpected large width of depletion layers. In addition, enlargement of the intimately contacted area during anodic bonding can be obtained from the proposed model, which can be utilized to monitor the bonding process. To verify the proposed model, Borofloat33 glass and silicon wafers were adopted in bonding experiments in SUSS SB6 with five different bonding conditions (350 °C 1200 V; 370 °C 1200 V; 380 °C 1200 V; 380 °C 1000 V; and 380 °C 1400 V). The results indicate that the observed current data highly coincide with the proposed current-time model. For widths of depletion layers, depth profiling using secondary ion mass spectrometry demonstrates that the calculated values by the model are basically consistent with the experimental values as well. (paper)

  10. Anode current density distribution in a cusped field thruster

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Huan, E-mail: wuhuan58@qq.com; Liu, Hui, E-mail: hlying@gmail.com; Meng, Yingchao; Zhang, Junyou; Yang, Siyu; Hu, Peng; Chen, Pengbo; Yu, Daren [Mail Box 458, Harbin Institute of Technology (HIT), Harbin 150001 (China)

    2015-12-15

    The cusped field thruster is a new electric propulsion device that is expected to have a non-uniform radial current density at the anode. To further study the anode current density distribution, a multi-annulus anode is designed to directly measure the anode current density for the first time. The anode current density decreases sharply at larger radii; the magnitude of collected current density at the center is far higher compared with the outer annuli. The anode current density non-uniformity does not demonstrate a significant change with varying working conditions.

  11. Effect of surface state of type 18-10 stainless steel on the authenticity and reproducibility of potentiodynamic polarization curves

    International Nuclear Information System (INIS)

    The effect of mechanic and electrochemical methods of finishing the surface of the 18-10 stainless steel (polishing, electropolishing) and its oxidation in air at room temperature on the authenticity and reproducibility of anode polarization curves is investigated. It is established that the behaviour of anode potentiodynamic polarization curves, both in active and passive range of potentials, depends on microgeometry and on the oxidation degree of initial electrode surface as well. An optimal method of preparing surfaces of the 18-10 steel for polarization measurements is suggested

  12. Synthesis of á-aminonitrile through Anodic Cyanation of N-benzylpiperidine

    Institute of Scientific and Technical Information of China (English)

    Zhao Ping; Yin Ying-wu

    2004-01-01

    Electrochemistry behaviors including linear sweep voltammetry and cyclic voltammetry of tertiary cyclic amines with different substituted group were studied. The effect of different substituted group of the nitrogen on the oxidation potential was analyzed. The most suited potential used in αα-aminonitrile synthesis through potentiostatic anodic cyanation of cyclic teritary amines was found. The anodic cyanation of N-alkyl-substituted cyclic six-membered amines including N-benzylpiperidine and N-ethylpiperidine has been investigated. The reaction gives the corresponding á-aminonitrile and carried out at a platinum anode in methanolic solution of the amine, containing 2.5 equivalents of sodium cyanide per mol of substrate. In all the selected amines the introduction of the cyanide group occurs in the position α to the nitrogen atom. We obtained two α-aminonitrile isomers. One is cyanated in the ring, the other is cyanated in the side chain. 1 The reaction mechanism is analyzedt brough analyzing the product of the constant current electrolysis and potentiostatic electrolysis and explained why the difference in the relative amount of isomers of tertiary cyclic amines and in the reactivities of the alkyl group between the ring and the side chain.The amount of isomers could not affect by the anode potential, and decided by the adsorption status at the anode surface and stability of the intermediate.The intermediate formed in anodic cyanation of N-benzylpiperidine is a parallel reaction, so the yield of α-aminonitrile can be increased but the selectivity of the two isomers cannot be increased in the potentiostatic electrolysis.The mechanism of the anode cyanation of N-benzylpiperidine was studied In methanol-water solution, anode cyanation of N-benzylpiperidine gives not only monocyanation product α-cyanoamine but also dicyanation product α, α-dicyanoamine and other byproduct because of overoxidation of N-benzylpiperidine caused by polarization of the anode under

  13. Polar Shapelets

    CERN Document Server

    Massey, R; Massey, Richard; Refregier, Alexandre

    2004-01-01

    The shapelets method for astronomical image analysis is based around the decomposition of localised objects into a series of orthogonal components with particularly convenient mathematical properties. We extend the "Cartesian shapelet" formalism from earlier work, and construct "polar shapelet" basis functions that separate an image into components with explicit rotational symmetries. This provides a more compact representation of typical galaxy shapes, and its physical interpretation is frequently more intuitive. Linear coordinate transformations can be simply expressed using this basis set, and shape measures (including object photometry, astrometry and galaxy morphology estimators) take a naturally elegant form. Particular attention is paid to the analysis of astronomical survey images, and we test shapelet techniques with real data from the Hubble Space Telescope. We present a practical method to automatically optimise the quality of an arbitrary shapelet decomposition in the presence of noise, pixellisat...

  14. Microwave processing of tantalum capacitor anodes

    Energy Technology Data Exchange (ETDEWEB)

    Lauf, R J; Hamby, C; Holcombe, C E [Oak Ridge National Lab., TN (United States); Vierow, W F [AVX Tantalum Corp., Biddeford, ME (United States)

    1992-08-01

    Porous tantalum anodes were sintered at temperatures from 1600 to 1900{degrees}C using a conventional high-vacuum furnace as well as both 2.45 GHz fixed-frequency and 4--8 GHz variable-frequency microwave furnaces. Various insulation and casketing techniques were used to couple the microwave power to the tantalum compacts. Several types of tantalum powder were used to assess the effect of microwave processing on sintered surface area and impurity levels. Some microwave sintered anodes have an unusual surface rippling not seen on conventionally fired parts. The rippling suggests that a microscopic arcing or plasma might have been generated. Two important effects could be exploited if this phenomenon can be controlled. First, the effective tantalum surface area could be increased, yielding higher capacitance per volume. Second, surface impurities might be cleaned away, allowing the formation of a better dielectric film during the anodization process and, ultimately, higher working voltage.

  15. An Insoluble Titanium-Lead Anode for Sulfate Electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Ferdman, Alla

    2005-05-11

    The project is devoted to the development of novel insoluble anodes for copper electrowinning and electrolytic manganese dioxide (EMD) production. The anodes are made of titanium-lead composite material produced by techniques of powder metallurgy, compaction of titanium powder, sintering and subsequent lead infiltration. The titanium-lead anode combines beneficial electrochemical behavior of a lead anode with high mechanical properties and corrosion resistance of a titanium anode. In the titanium-lead anode, the titanium stabilizes the lead, preventing it from spalling, and the lead sheathes the titanium, protecting it from passivation. Interconnections between manufacturing process, structure, composition and properties of the titanium-lead composite material were investigated. The material containing 20-30 vol.% of lead had optimal combination of mechanical and electrochemical properties. Optimal process parameters to manufacture the anodes were identified. Prototypes having optimized composition and structure were produced for testing in operating conditions of copper electrowinning and EMD production. Bench-scale, mini-pilot scale and pilot scale tests were performed. The test anodes were of both a plate design and a flow-through cylindrical design. The cylindrical anodes were composed of cylinders containing titanium inner rods and fitting over titanium-lead bushings. The cylindrical design allows the electrolyte to flow through the anode, which enhances diffusion of the electrolyte reactants. The cylindrical anodes demonstrate higher mass transport capabilities and increased electrical efficiency compared to the plate anodes. Copper electrowinning represents the primary target market for the titanium-lead anode. A full-size cylindrical anode performance in copper electrowinning conditions was monitored over a year. The test anode to cathode voltage was stable in the 1.8 to 2.0 volt range. Copper cathode morphology was very smooth and uniform. There was no

  16. Optical Polarization Properties of Metal Nanowire Array Film Synthesized by Electrodeposition Technology

    Institute of Scientific and Technical Information of China (English)

    梁燕萍; 史启祯; 吴振森; 王尧宇; 高胜利

    2005-01-01

    Metal nanowire array films were prepared by electrodepositing Cu, Ag, Ni, Co and Cu-Ag on porous anodic alumina film. Optical transmittance of both the porous anodic alumina film and metal nanowire array film was measured in the wavelength range of 400---2600 nm under an obliquely incident light. The experimental results show that metal nanowire array films exhibit a prominent polarization function. It was found that optical polarization properties can be improved by choosing suitable kinds of electrodepositing metal, controlling the shape and length of nanowire, and changing the incident angle.

  17. Realistic simulation of the Space-borne Compton Polarimeter POLAR

    Science.gov (United States)

    Xiao, Hualin

    2016-07-01

    POLAR is a compact wide field space-borne detector dedicated for precise measurements of the linear polarization of hard x-rays emitted by transient sources. Its energy range sensitivity is optimized for the detection of the prompt emission of Gamma-ray bursts (GRBs). POLAR is developed by an international collaboration of China, Switzerland and Poland. It is planned to be launched into space in 2016 onboard the Chinese space laboratory TG2. The energy range of POLAR spans between 50 keV and 500 keV. POLAR detects gamma rays with an array of 1600 plastic scintillator bars read out by 25 muti-anode PMTs (MAPMTs). Polarization measurements use Compton scattering process and are based on detection of energy depositions in the scintillator bars. Reconstruction of the polarization degree and polarization angle of GRBs requires comparison of experimental modulation curves with realistic simulations of the full instrument response. In this paper we present a method to model and parameterize the detector response including efficiency of the light collection, contributions from crosstalk and non-uniformity of MAPMTs as well as dependency on low energy detection thresholds and noise from readout electronics. The performance of POLAR for determination of polarization is predicted with such realistic simulations and carefully cross-checked with dedicated laboratory tests.

  18. Improving the Performance of SOFC Anodes by Decorating Perovskite with Ni Nanoparticles

    KAUST Repository

    Boulfrad, S.

    2013-10-07

    In this work (La0.75Sr0.25)0.97Cr0.5Mn0.5O3 (LSCM) perovskite powders were pre-coated with 5 wt% nickel and mixed with different amounts of CGO for testing as anode materials under 3% wet H2. By using scanning transmission electron microscopy (STEM) with X-ray energy dispersive spectroscopy (EDS), we demonstrated that Ni forms a solid solution in the perovkite phase under oxidizing atmosphere and exsolves in form of nanoparticles under reducing atmospheres. The presence of the catalyst nanoparticles led to a decrease in the anodic activation energy by half and thus the polarization resistance was dropped by 60% at 800¢ªC. The effect of CGO amount will be also discussed.

  19. Micropolarizer of Ordered Ni Nanowire Arrays Embedded in Porous Anodic Alumina Membrane

    Institute of Scientific and Technical Information of China (English)

    PANG Yan-Tao; MENG Guo-Wen; SHAN Wen-Jun; FANG Qi; ZHANG Li-De

    2003-01-01

    A micropolarizer of nickel nanowire arrays within an anodic alumina membrane (AAM) was fabricated by an-odization of pure Al and electrodeposition of Ni, respectively. X-ray diffraction, scanning electron microscopy and transmission-electron microscopy reveal that the nanowires are polycrystal and have an average diameter of 70 nm. Spectrophotometer measurements show that the nickel nanowire arrays embedded in the AAM can only transmit polarized light vertical to the wires. An extinction ratio of 25 to 30 dB and an average insertion loss of 1.07dB in the wavelength range of l-2.5fj.rn were obtained, respectively. Thus, Ni nanowire/AAM can be used as a wire grid type micropolarizer.

  20. Some regularities of metal anodic dissolution in voltammetry with pressed two-electrode cell

    International Nuclear Information System (INIS)

    Mathematical expressions for the distribution of ion concentration of anode-solving metal in the near-electrode layer of a solution for the conditions of a clamp-type two-electrode electrolytic cell have been obtained. A possibility is shown of theoretical calculation of critical parameters of polarographic curves measured during operation according to the given technique. The obtained dependences are suggested to be taken as the basis in the choice of the optimum polarization conditions of the working electrode for determining the thickness of metal coatings using voltametry method. The calculated results have been experimentally tested on the example of anode dissolution of copper, cadmium and silver in the clamp-type cell. 1MNaSO4 (for Cu and Cd), 2MNH4F (for silver) at I=2.5 mA served as background electrolytes

  1. Anodic dissolution of metals in ionic liquids

    OpenAIRE

    Abbott, Andrew P.; Gero Frisch; Jennifer Hartley; Wrya O. Karim; Ryder, Karl S.

    2015-01-01

    The anodic dissolution of metals is an important topic for battery design, material finishing and metal digestion. Ionic liquids are being used in all of these areas but the research on the anodic dissolution is relatively few in these media. This study investigates the behaviour of 9 metals in an ionic liquid [C4mim][Cl] and a deep eutectic solvent, Ethaline, which is a 1:2 mol ratio mixture of choline chloride and ethylene glycol. It is shown that for the majority of metals studied a quasi-...

  2. Silicon Whisker and Carbon Nanofiber Composite Anode

    Science.gov (United States)

    Lang, Christopher M.

    2015-01-01

    Phase II Objectives: Demonstrate production levels of grams per batch; Achieve full cell anode capacity of greater than 1,000 mAh/g at a charge rate of 10 (C/10) and 0 degree C; Establish a full cell cycle life of over 300 cycles; Display an operating temperature of negative 30 degrees C to plus 30 degrees C; Demonstrate a rate capability of C/5 or higher; Deliver to NASA three 2.5 Ah cells (energy density greater than 220 Wh/kg); Exhibit the safety features of the anode and full cells; Design a 1 kWh prismatic battery pack.

  3. Electrode Reaction Pathway in Oxide Anode for Solid Oxide Fuel Cells

    Science.gov (United States)

    Li, Wenyuan

    Oxide anodes for solid oxide fuel cells (SOFC) with the advantage of fuel flexibility, resistance to coarsening, small chemical expansion and etc. have been attracting increasing interest. Good performance has been reported with a few of perovskite structure anodes, such as (LaSr)(CrMn)O3. However, more improvements need to be made before meeting the application requirement. Understanding the oxidation mechanism is crucial for a directed optimization, but it is still on the early stage of investigation. In this study, reaction mechanism of oxide anodes is investigated on doped YCrO 3 with H2 fuel, in terms of the origin of electrochemical activity, rate-determining steps (RDS), extension of reactive zone, and the impact from overpotential under service condition to those properties. H2 oxidation on the YCs anodes is found to be limited by charge transfer and H surface diffusion. A model is presented to describe the elementary steps in H2 oxidation. From the reaction order results, it is suggested that any models without taking H into the charge transfer step are invalid. The nature of B site element determines the H2 oxidation kinetics primarily. Ni displays better adsorption ability than Co. However, H adsorption ability of such oxide anode is inferior to that of Ni metal anode. In addition, the charge transfer step is directly associated with the activity of electrons in the anode; therefore it can be significantly promoted by enhancement of the electron activity. It is found that A site Ca doping improves the polarization resistance about 10 times, by increasing the activity of electrons to promote the charge transfer process. For the active area in the oxide anode, besides the traditional three-phase boundary (3PB), the internal anode surface as two-phase boundary (2PB) is proven to be capable of catalytically oxidizing the H2 fuel also when the bulk lattice is activated depending on the B site elements. The contribution from each part is estimated by switching

  4. Silicon Whisker and Carbon Nanofiber Composite Anode Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Physical Sciences Inc. (PSI) proposes to develop a silicon whisker and carbon nanofiber composite anode for lithium ion batteries on a Phase I program. This anode...

  5. Carbon foam anode modified by urea and its higher electrochemical performance in marine benthic microbial fuel cell

    Science.gov (United States)

    Fu, Yubin; Lu, Zhikai; Zai, Xuerong; Wang, Jian

    2015-08-01

    Electrode materials have an important effect on the property of microbial fuel cell (MFC). Carbon foam is utilized as an anode and further modified by urea to improve its performance in marine benthic microbial fuel cell (BMFC) with higher voltage and output power. The electrochemical properties of plain carbon foam (PC) and urea-modified carbon foam (UC) are measured respectively. Results show that the UC obtains better wettability after its modification and higher anti-polarization ability than the PC. A novel phenomenon has been found that the electrical potential of the modified UC anode is nearly 100 mV lower than that of the PC, reaching -570 ±10 mV ( vs. SCE), and that it also has a much higher electron transfer kinetic activity, reaching 9399.4 mW m-2, which is 566.2-fold higher than that from plain graphite anode (PG). The fuel cell containing the UC anode has the maximum power density (256.0 mW m-2) among the three different BMFCs. Urea would enhance the bacteria biofilm formation with a more diverse microbial community and maintain more electrons, leading to a lower anodic redox potential and higher power output. The paper primarily analyzes why the electrical potential of the modified anode becomes much lower than that of others after urea modification. These results can be utilized to construct a novel BMFC with higher output power and to design the conditioner of voltage booster with a higher conversion ratio. Finally, the carbon foam with a bigger pore size would be a potential anodic material in conventional MFC.

  6. Direct reforming of biogas on Ni-based SOFC anodes: Modelling of heterogeneous reactions and validation with experiments

    Science.gov (United States)

    Santarelli, Massimo; Quesito, Francesco; Novaresio, Valerio; Guerra, Cosimo; Lanzini, Andrea; Beretta, Davide

    2013-11-01

    This work focuses on the heterogeneous reactions taking place in a tubular anode-supported solid oxide fuel cell (SOFC) when the designated fuel is biogas from anaerobic digestion directly feeding the fuel cell. Operational maps of the fuel cell running on direct reforming of biogas were first obtained. Hence a mathematical model incorporating the kinetics of reforming reactions on Ni catalyst was used to predict the gas composition profile along the fuel channel. The model was validated against experimental data based on polarization curves. Also, the anode off-gas composition was collected and analyzed through a gas chromatograph. Finally, the model has been used to predict and analyze the gas composition change along the anode channel to evaluate effectiveness of the direct steam reforming when varying cell temperature, inlet fuel composition and the type of reforming process. The simulations results confirmed that thermodynamic-equilibrium conditions are not fully achieved inside the anode channel. It also outlines that a direct biogas utilization in an anode-supported SOFC is able to provide good performance and to ensure a good conversion of the methane even though when the cell temperature is far from the nominal value.

  7. The effect of crystal orientation on the aluminum anodes of the aluminum-air batteries in alkaline electrolytes

    Science.gov (United States)

    Fan, Liang; Lu, Huimin; Leng, Jing; Sun, Zegao; Chen, Chunbo

    2015-12-01

    Recently, aluminum-air (Al-air) batteries have received attention from researchers as an exciting option for safe and efficient batteries. The electrochemical performance of Aluminum anode remains an active area of investigation. In this paper, the electrochemical properties of polycrystalline Al, Al (001), (110) and (111) single crystals are investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 4 M NaOH and KOH. Hydrogen corrosion rates of the Al anodes are determined by hydrogen collection. Battery performance using the anodes is tested by constant current discharge at 10 mA cm-2. This is the first report showing that the electrochemical properties of Al are closely related to the crystallographic orientation in alkaline electrolytes. The (001) crystallographic plane has good corrosion resistance but (110) is more sensitive. Al (001) single crystals display higher anode efficiency and capacity density. Controlling the crystallographic orientation of the Al anode is another way to improve the performance of Al-air batteries in alkaline electrolytes.

  8. Improved activity and stability of Ni-Ce0.8Sm0.2O1.9 anode for solid oxide fuel cells fed with methanol through addition of molybdenum

    Science.gov (United States)

    Li, Ping; Yu, Baolong; Li, Jiang; Yao, Xueli; Zhao, Yicheng; Li, Yongdan

    2016-07-01

    Ni-Mo-Ce0.8Sm0.2O1.9 (SDC) composites are prepared and investigated as anodes of solid oxide fuel cells with methanol as fuel. The addition of Mo improves the catalytic activity for methanol pyrolysis and the resistance to carbon deposition of Ni-SDC anode. The anode with a mole ratio of Mo to Ni of 0.03:1 exhibits the lowest polarization resistance. The cell with that anode and SDC-carbonate composite electrolyte shows a maximum power density of 680 mW cm-2 at 700 °C. The stability of the cell is enhanced with the increase of the content of Mo in the anode, which is mainly attributed to the decreased amount of carbon deposits with a high graphitization degree.

  9. The effect of the presence of alcohol in the dispersing phase of oxide sols on the properties of RuO2-TiO2/Ti anodes obtained by the sol–gel procedure

    Directory of Open Access Journals (Sweden)

    R. ATANASOSKI

    2000-09-01

    Full Text Available The effect of the addition of ethanol and 2-propanol to the dispersing phase of TiO2 and RuO2 sols mixture on the morphology and, consequently, on the electrochemical properties of the sol-gel obtained activated titanium anodes was investigated. The properties of the obtained anodes were compared to those obtained by the thermal decomposition of appropriate chloride salts. The morphology of the anode coatings was examined by scanning tunneling microscopy. The electrochemical behaviour was investigated by cyclic voltammetry and by polarization measurements. An accelerated stability test was used for the examination of the stability of the anodes under simultaneous oxygen and chlorine evolution reaction. A dependence of the anode stability on the type of added alcohol is indicated.

  10. Preparation of Porosity-Graded SOFC Anode Substrates

    NARCIS (Netherlands)

    Holtappels, P.; Sorof, C.; Verbraeken, M.C.; Rambert, S.; Vogt, U.

    2006-01-01

    Porosity graded anode substrates for solid oxide fuel cells are considered to optimise the gas transport through the substrate by maintaining a high electrochemical activity for fuel oxidation at the anode/solid electrolyte interface. In this work, the fabrication of porosity graded anode substrates

  11. Anodic Stripping Voltammetry: An Instrumental Analysis Experiment.

    Science.gov (United States)

    Wang, Joseph

    1983-01-01

    Describes an experiment designed to acquaint students with the theory and applications of anodic stripping voltammetry (ASV) as well as such ASV problems as contamination associated with trace analysis. The experimental procedure, instrumentation, and materials discussed are designed to minimize cost and keep procedures as simple as possible. (JM)

  12. Basic Principles of Anodic Stripping Voltammetry (ASV)

    OpenAIRE

    2012-01-01

    In this interactive exercise, the basic principles of Anodic Stripping Voltammetry are shown. Each step of the voltammetric process is described using simulated animations. This activity illustrates what takes place in the voltammetric cell when this technique is applied to the determination of cadmium as well as to the simultaneous determination of copper and cadmium.

  13. Study on selenium extraction from anode slime

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Taking a copper anode slime as the raw material, a novel process for selenium extraction was studied. The primary selenium recovery can reach above 88.5 % and the quality index of selenium product can be up to 99.5 %. The economic benefit resulted is remarkable and environment has been protected.

  14. Characterization of nanopores ordering in anodic alumina

    DEFF Research Database (Denmark)

    Mátéfi-Tempfli, Stefan; Mátéfi-Tempfli, M.; Piraux, L.

    2008-01-01

    A simple characterization method of the ordering of the nanopores is described for nanoporous anodized aluminium oxides. The method starts with image analysis on scanning electron microscopy representations for the purpose to find repetitive shapes and their centres, i.e. nanopores. Then triangle...... sensitive on ordering. © 2007 Elsevier B.V. All rights reserved....

  15. Low temperature anodic bonding to silicon nitride

    DEFF Research Database (Denmark)

    Weichel, Steen; Reus, Roger De; Bouaidat, Salim;

    2000-01-01

    Low-temperature anodic bonding to stoichiometric silicon nitride surfaces has been performed in the temperature range from 3508C to 4008C. It is shown that the bonding is improved considerably if the nitride surfaces are either oxidized or exposed to an oxygen plasma prior to the bonding. Both bulk...

  16. Silicon Whisker and Carbon Nanofiber Composite Anode

    Science.gov (United States)

    Ma, Junqing (Inventor); Newman, Aron (Inventor); Lennhoff, John (Inventor)

    2015-01-01

    A carbon nanofiber can have a surface and include at least one crystalline whisker extending from the surface of the carbon nanofiber. A battery anode composition can be formed from a plurality of carbon nanofibers each including a plurality of crystalline whiskers.

  17. Hybrid anode for semiconductor radiation detectors

    Science.gov (United States)

    Yang, Ge; Bolotnikov, Aleksey E; Camarda, Guiseppe; Cui, Yonggang; Hossain, Anwar; Kim, Ki Hyun; James, Ralph B

    2013-11-19

    The present invention relates to a novel hybrid anode configuration for a radiation detector that effectively reduces the edge effect of surface defects on the internal electric field in compound semiconductor detectors by focusing the internal electric field of the detector and redirecting drifting carriers away from the side surfaces of the semiconductor toward the collection electrode(s).

  18. An inert metal anode for magnesium electrowinning

    Energy Technology Data Exchange (ETDEWEB)

    Moore, J. F.; Hryn, J. N.; Pellin, M. J.; Calaway, W. F.; Watson, K.

    1999-12-01

    Results from the development of a novel type of anode for electrowinning Mg are reported. A tailored alloy system based on the binary Cu-Al can be made to form a thin alumina layer on its surface that is relatively impervious to attack by the molten chloride melt at high temperature. This barrier is thin enough (5--50 nm) to conduct electrical current without significant IR loss. As the layer slowly dissolves, the chemical potential developed at the surface drives the diffusion of aluminum from the bulk alloy to reform (heal) the protective alumina layer. In this way, an anode that generates Cl{sub 2} (melt electrolysis) and O{sub 2} (wet feed hydrolysis) and no chlorocarbons can be realized. Further, the authors expect the rate of loss of the anode to be dramatically less than the coke-derived carbon anodes typically in use for this technology, leading to substantial cost savings and ancillary pollution control by eliminating coke plant emissions, as well as eliminating chlorinated hydrocarbon emissions from Mg electrowinning cells.

  19. Self-ordering behavior of nanoporous anodic aluminum oxide (AAO) in malonic acid anodization

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W; Nielsch, K; Goesele, U [Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Germany)

    2007-11-28

    The self-ordering behavior of anodic aluminum oxide (AAO) has been investigated for anodization of aluminum in malonic acid (H{sub 4}C{sub 3}O{sub 4}) solution. In the present study it is found that a porous oxide layer formed on the surface of aluminum can effectively suppress catastrophic local events (such as breakdown of the oxide film and plastic deformation of the aluminum substrate), and enables stable fast anodic oxidation under a high electric field of 110-140 V and {approx}100 mA cm{sup -2}. Studies on the self-ordering behavior of AAO indicated that the cell homogeneity of AAO increases dramatically as the anodization voltage gets higher than 120 V. Highly ordered AAO with a hexagonal arrangement of the nanopores could be obtained in a voltage range 125-140 V. The current density (i.e., the electric field strength (E) at the bottom of a pore) is an important parameter governing the self-ordering of the nanopores as well as the interpore distance (D{sub int}) for a given anodization potential (U) during malonic acid anodization.

  20. Multilayer tape cast SOFC – Effect of anode sintering temperature

    DEFF Research Database (Denmark)

    Hauch, Anne; Birkl, Christoph; Brodersen, Karen;

    2012-01-01

    Multilayer tape casting (MTC) is considered a promising, cost-efficient, up-scalable shaping process for production of planar anode supported solid oxide fuel cells (SOFC). Multilayer tape casting of the three layers comprising the half cell (anode support/active anode/electrolyte) can potentially...... be cost-efficient and simplify the half-cell manufacturing process. Fewer sintering steps (co-sintering), as well as fewer handling efforts, will be advantageous for up-scaled production. Previous reports have shown that our laboratory produces mechanically strong, high performing anode supported SOFC......, with high reproducibility, by tape casting of the anode support [1]. Recent initial results obtained on SOFC with half-cells produced by successive tape casting (MTC) of anode support, anode and electrolyte layers, followed by cosintering of the half-cell, showed increased performance and stability upon FC...

  1. Further observations on the operation of a GaAs polarized electron source

    Energy Technology Data Exchange (ETDEWEB)

    Guo, X.Q.; Crowe, D.M.; Lubell, M.S.; Tang, F.C.; Vasilakis, A. (Department of Physics, The City College of CUNY, New York, New York 10031 (USA)); Eminyan, M. (Laboratoire de Physique Atomique, Tour 24, Universite Paris VII, F-75251 Paris (France)); Slevin, J. (Department of Experimental Physics, St. Patrick' s College, Maynooth, County Kildare (Ireland))

    1990-07-01

    We report on several important features of GaAs polarized electron source operation. Specifically we point out the beneficial effect on crystal lifetime produced by the constant low-level application of cesium from a dispenser embedded in an extraction anode. Using our experience in low-energy polarized electron-atom scattering as a reference, we also discuss the importance of frequent energy calibrations of GaAs electron beams for high-resolution investigations.

  2. Further observations on the operation of a GaAs polarized electron source

    International Nuclear Information System (INIS)

    We report on several important features of GaAs polarized electron source operation. Specifically we point out the beneficial effect on crystal lifetime produced by the constant low-level application of cesium from a dispenser embedded in an extraction anode. Using our experience in low-energy polarized electron-atom scattering as a reference, we also discuss the importance of frequent energy calibrations of GaAs electron beams for high-resolution investigations

  3. Anodized Nanoporous Titania Thin Films for Dental Application: Structure’ Effect on Corrosion Behavior

    Directory of Open Access Journals (Sweden)

    A. Boucheham

    2016-06-01

    Full Text Available Nanostructured Titania layers formed on the surface of titanium and titanium alloys by anodic oxidation play an important role in the enhancement of their biocompatibility and osseointegration in the human body. For this purpose, we aimed to study in the current work the structural and electrochemical properties of amorphous and crystallized nanostructured TiO2 thin films elaborated on Ti6Al4V substrate by electrochemical anodization in fluoride ions (F– containing electrolyte at 10 V during 15 min and heat treated in air at 550 °C for 2 h. The morphology, chemical composition and phase composition of synthesized layers were investigated using field emission scanning electron microscopy (FE-SEM and X-ray diffraction (XRD. The corrosion resistance improvement of both as-anodized and annealed titania layers was evaluated in 0.9 wt. % NaCl solution with pH = 6.4 at room temperature by means of open circuit potential (Eoc,potentiodynamic polarization (PDYN and electrochemical impedance spectroscopy (EIS.

  4. Effect of various de-anodizing techniques on the surface stability of non-colored and colored nanoporous AAO films in acidic solution

    Science.gov (United States)

    Awad, Ahmed M.; Shehata, Omnia S.; Heakal, Fakiha El-Taib

    2015-12-01

    Anodic aluminum oxide (AAO) is well known as an important nanostructured material, and a useful template in the fabrication of nanostructures. Nanoporous anodic alumina (PAA) with high open porosity was prepared by adopting three de-anodizing regimes following the first anodizing step and preceding the second one. The de-anodizing methods include electrolytic etching (EE) and chemical etching using either phosphoric acid (PE) or sodium hydroxide (HE) solutions. Three of the obtained AAO samples were black colored by electrodeposition of copper nanoparticles in their pores. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques were used to characterize the electrochemical performance of the two sets of the prepared samples. In general, the data obtained in aggressive aerated 0.5 M HCl solution demonstrated dissimilar behavior for the three prepared samples despite that the second anodizing step was the same for all of them. The data indicated that the resistance and thickness of the inner barrier part of nano-PAA film, are the main controlling factors determining its stability. On the other hand, coloring the film decreased its stability due to the galvanic effect. The difference in the electrochemical behavior of the three colored samples was discussed based on the difference in both the pore size and thickness of the outer porous part of PAA film as supported by SEM, TEM and cross-sectional micrographs. These results can thus contribute for better engineering applications of nanoporous AAO.

  5. Research of nickel’s electrochemical property in sulfuric acid solution by using potentiodynamic polarization curve.

    Directory of Open Access Journals (Sweden)

    Bekenova Gulmira

    2015-03-01

    Full Text Available In the presented work in order to deeply study the mechanism of electrode processes that take place while polarizing the nickel electrode in acid solutions by alternating current, potentiodynamic polarization curves were obtained.The detailed study of shapes of polarization curves; their dependence on concentration, temperature, and other physical and chemical parameters, gives opportunity to obtain full information on the nature and kinesthetic of processes taking place on electrode surface. The electrochemical properties of nickel electrode were researched by estimating cyclic potentiodynamic polarization curves in sulfuric acid medium; and the influence of electrolyte concentration, potential giving speed, the temperature of solution on anodic and cathode processes were also studied. The meanings of transfer number (an and diffusion (D coefficient, the reaction order of metal ions during the process of nickel electrode’s anode corrosion in sulfuric acid solution, and the activation energy is estimated. Result of the calculations showed that nickel’s melting process goes in mixed, diffusion-kinetic regime. It was found that the raising of solution’s temperature increases the height of corrosion current. The results of the experiments done during the application of cyclic polarization curves showed that the electrochemical processes that take place in polarization by industrial alternating current in anode and cathode half periods is different from those done in stable current and with more complex mechanism.

  6. Investigation of mechanism of anode plasma formation in ion diode with dielectric anode

    Science.gov (United States)

    Pushkarev, A.

    2015-10-01

    The results of investigation of the anode plasma formation in a diode with a passive anode in magnetic insulation mode are presented. The experiments have been conducted using the BIPPAB-450 ion accelerator (350-400 kV, 6-8 kA, 80 ns) with a focusing conical diode with Br external magnetic field (a barrel diode). For analysis of plasma formation at the anode and the distribution of the ions beam energy density, infrared imaging diagnostics (spatial resolution of 1-2 mm) is used. For analysis of the ion beam composition, time-of-flight diagnostics (temporal resolution of 1 ns) were used. Our studies have shown that when the magnetic induction in the A-C gap is much larger than the critical value, the ion beam energy density is close to the one-dimensional Child-Langmuir limit on the entire working surface of the diode. Formation of anode plasma takes place only by the flashover of the dielectric anode surface. In this mode, the ion beam consists primarily of singly ionized carbon ions, and the delay of the start of formation of the anode plasma is 10-15 ns. By reducing the magnetic induction in the A-C gap to a value close to the critical one, the ion beam energy density is 3-6 times higher than that calculated by the one-dimensional Child-Langmuir limit, but the energy density of the ion beam is non-uniform in cross-section. In this mode, the anode plasma formation occurs due to ionization of the anode material with accelerated electrons. In this mode, also, the delay in the start of the formation of the anode plasma is much smaller and the degree of ionization of carbon ions is higher. In all modes occurred effective suppression of the electronic component of the total current, and the diode impedance was 20-30 times higher than the values calculated for the mode without magnetic insulation of the electrons. The divergence of the ion beam was 4.5°-6°.

  7. High performance anode for advanced Li batteries

    Energy Technology Data Exchange (ETDEWEB)

    Lake, Carla [Applied Sciences, Inc., Cedarville, OH (United States)

    2015-11-02

    The overall objective of this Phase I SBIR effort was to advance the manufacturing technology for ASI’s Si-CNF high-performance anode by creating a framework for large volume production and utilization of low-cost Si-coated carbon nanofibers (Si-CNF) for the battery industry. This project explores the use of nano-structured silicon which is deposited on a nano-scale carbon filament to achieve the benefits of high cycle life and high charge capacity without the consequent fading of, or failure in the capacity resulting from stress-induced fracturing of the Si particles and de-coupling from the electrode. ASI’s patented coating process distinguishes itself from others, in that it is highly reproducible, readily scalable and results in a Si-CNF composite structure containing 25-30% silicon, with a compositionally graded interface at the Si-CNF interface that significantly improve cycling stability and enhances adhesion of silicon to the carbon fiber support. In Phase I, the team demonstrated the production of the Si-CNF anode material can successfully be transitioned from a static bench-scale reactor into a fluidized bed reactor. In addition, ASI made significant progress in the development of low cost, quick testing methods which can be performed on silicon coated CNFs as a means of quality control. To date, weight change, density, and cycling performance were the key metrics used to validate the high performance anode material. Under this effort, ASI made strides to establish a quality control protocol for the large volume production of Si-CNFs and has identified several key technical thrusts for future work. Using the results of this Phase I effort as a foundation, ASI has defined a path forward to commercialize and deliver high volume and low-cost production of SI-CNF material for anodes in Li-ion batteries.

  8. Analysis of bio-anode performance through electrochemical impedance spectroscopy.

    Science.gov (United States)

    ter Heijne, Annemiek; Schaetzle, Olivier; Gimenez, Sixto; Navarro, Lucia; Hamelers, Bert; Fabregat-Santiago, Francisco

    2015-12-01

    In this paper we studied the performance of bioanodes under different experimental conditions using polarization curves and impedance spectroscopy. We have identified that the large capacitances of up to 1 mF·cm(-2) for graphite anodes have their origin in the nature of the carbonaceous electrode, rather than the microbial culture. In some cases, the separate contributions of charge transfer and diffusion resistance were clearly visible, while in other cases their contribution was masked by the high capacitance of 1 mF·cm(-2). The impedance data were analyzed using the basic Randles model to analyze ohmic, charge transfer and diffusion resistances. Increasing buffer concentration from 0 to 50mM and increasing pH from 6 to 8 resulted in decreased charge transfer and diffusion resistances; lowest values being 144 Ω·cm(2) and 34 Ω·cm(2), respectively. At acetate concentrations below 1 mM, current generation was limited by acetate. We show a linear relationship between inverse charge transfer resistance at potentials close to open circuit and saturation (maximum) current, associated to the Butler-Volmer relationship that needs further exploration.

  9. Polarization-balanced beamsplitter

    Science.gov (United States)

    Decker, D.E.

    1998-02-17

    A beamsplitter assembly is disclosed that includes several beamsplitter cubes arranged to define a plurality of polarization-balanced light paths. Each polarization-balanced light path contains one or more balanced pairs of light paths, where each balanced pair of light paths includes either two transmission light paths with orthogonal polarization effects or two reflection light paths with orthogonal polarization effects. The orthogonal pairing of said transmission and reflection light paths cancels polarization effects otherwise caused by beamsplitting. 10 figs.

  10. Improvement in direct methanol fuel cell performance by treating the anode at high anodic potential

    Science.gov (United States)

    Joghee, Prabhuram; Pylypenko, Svitlana; Wood, Kevin; Corpuz, April; Bender, Guido; Dinh, Huyen N.; O'Hayre, Ryan

    2014-01-01

    This work investigates the effect of a high anodic potential treatment protocol on the performance of a direct methanol fuel cell (DMFC). DMFC membrane electrode assemblies (MEAs) with PtRu/C (Hi-spec 5000) anode catalyst are subjected to anodic treatment (AT) at 0.8 V vs. DHE using potentiostatic method. Despite causing a slight decrease in the electrochemical surface area (ECSA) of the anode, associated with ruthenium dissolution, AT results in significant improvement in DMFC performance in the ohmic and mass transfer regions and increases the maximum power density by ∼15%. Furthermore, AT improves the long-term DMFC stability by reducing the degradation of the anode catalyst. From XPS investigation, it is hypothesized that the improved performance of AT-treated MEAs is related to an improved interface between the catalyst and Nafion ionomer. Among potential explanations, this improvement may be caused by incorporation of the ionomer within the secondary pores of PtRu/C agglomerates, which generates a percolating network of ionomer between PtRu/C agglomerates in the catalyst layer. Furthermore, the decreased concentration of hydrophobic CF2 groups may help to enhance the hydrophilicity of the catalyst layer, thereby increasing the accessibility of methanol and resulting in better performance in the high current density region.

  11. Anodic stripping voltammetry of technetium alkaline media

    International Nuclear Information System (INIS)

    A method of direct determination of technetium in 0.1 M NaOH by anodic stripping voltametry at glassy carbon electrode has been elaborated. The peak height of anodic TcO2(OH)2 dissolution was found to be linearly dependent on preconcentration time, and the concentration of technetium in the range 5.0 * 10-8 -6 M. The detection limit for the Tc determination by ASV technique under study was found to be 5.0 * 10-8 M with standard deviation 5-7% (p2(OH)2 anodic dissolution peak current. Addition of 1.0* 10-6 M U(UI) to the sample solution was found to shift the peak of the TcO2(OH)2 100 mV towards negative direction and disturb the linearity of the calibration curve. Therefore; for a successful application of the developed ASV technique for Tc determination in the alkaline media, uranium should be removed from the analyte before determination

  12. Protection of MOS capacitors during anodic bonding

    Science.gov (United States)

    Schjølberg-Henriksen, K.; Plaza, J. A.; Rafí, J. M.; Esteve, J.; Campabadal, F.; Santander, J.; Jensen, G. U.; Hanneborg, A.

    2002-07-01

    We have investigated the electrical damage by anodic bonding on CMOS-quality gate oxide and methods to prevent this damage. n-type and p-type MOS capacitors were characterized by quasi-static and high-frequency CV-curves before and after anodic bonding. Capacitors that were bonded to a Pyrex wafer with 10 μm deep cavities enclosing the capacitors exhibited increased leakage current and interface trap density after bonding. Two different methods were successful in protecting the capacitors from such damage. Our first approach was to increase the cavity depth from 10 μm to 50 μm, thus reducing the electric field across the gate oxide during bonding from approximately 2 × 105 V cm-1 to 4 × 104 V cm-1. The second protection method was to coat the inside of a 10 μm deep Pyrex glass cavity with aluminium, forming a Faraday cage that removed the electric field across the cavity during anodic bonding. Both methods resulted in capacitors with decreased interface trap density and unchanged leakage current after bonding. No change in effective oxide charge or mobile ion contamination was observed on any of the capacitors in the study.

  13. Anodic Dissolution of API X70 Pipeline Steel in Arabian Gulf Seawater after Different Exposure Intervals

    Directory of Open Access Journals (Sweden)

    El-Sayed M. Sherif

    2014-01-01

    Full Text Available The anodic dissolution of API X70 pipeline steel in Arabian Gulf seawater (AGSW was investigated using open-circuit potential (OCP, electrochemical impedance spectroscopy (EIS, cyclic potentiodynamic polarization (CPP, and current-time measurements. The electrochemical experiments revealed that the X70 pipeline steel suffers both general and pitting corrosion in the AGSW solution. It was found that the general corrosion decreases as a result of decreasing the corrosion current density (jcorr, corrosion rate (Rcorr and absolute currents as well as the increase of polarization resistance of X70 with increasing the exposure time. On the other hand, the pitting corrosion was found to increase with increasing the immersion time. This was confirmed by the increase of current with time and by the SEM images that were obtained on the steel surface after 20 h immersion before applying an amount of 0–.35 V versus Ag/AgCl for 1 h.

  14. Improvement of rate capability of spinel lithium titanate anodes using microwave-assisted zinc nanocoating

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Chien-Te, E-mail: cthsieh@saturn.yzu.edu.tw [Department of Chemical Engineering and Materials Science, Yuan Ze Fuel Cell Center, Yuan Ze University, Taoyuan 320, Taiwan (China); Chang, Bi-Sheng; Lin, Jia-Yi; Juang, Ruey-Shin [Department of Chemical Engineering and Materials Science, Yuan Ze Fuel Cell Center, Yuan Ze University, Taoyuan 320, Taiwan (China)

    2012-02-05

    Highlights: Black-Right-Pointing-Pointer Microwave-assisted Zn layers onto Li{sub 4}Ti{sub 5}O{sub 12} crystals serves as superior anode materials. Black-Right-Pointing-Pointer Microwave heating is capable of depositing Zn layers over the surface of spinel Li{sub 4}Ti{sub 5}O{sub 12} within 6 min. Black-Right-Pointing-Pointer The thickness of Zn layer is an increasing function of zinc nitrate concentration. Black-Right-Pointing-Pointer The deposition of Zn coating shows a positive effect on the rate-capability improvement of anodes. - Abstract: In this study, the deposition of microwave-assisted Zn layers onto spinel lithium titanate (Li{sub 4}Ti{sub 5}O{sub 12}) crystals as superior anode materials for Li-ion batteries has been investigated. Microwave heating is capable of rapidly depositing Zn layers over the surface of spinel Li{sub 4}Ti{sub 5}O{sub 12} within 6 min. The thickness of Zn layer (i.e., 1-10 nm) is an increasing function of zinc nitrate concentration under the microwave irradiation. The charge-discharge curve of Zn-Li{sub 4}Ti{sub 5}O{sub 12} anode still maintains the plateau at 1.5 V, contributing to the major portion in the overall specific capacity. The presence of Zn coating significantly facilitates the capacity retention (78.1% at 10 C/0.2 C) of the composite anodes with high Coulombic efficiency (>99.9%), indicating an excellent reversibility of insertion/de-insertion of Li ions. This can be ascribed to the fact that well-dispersed Zn layer offers an electronic pathway over the Li{sub 4}Ti{sub 5}O{sub 12} powder, thus imparting electronic conduction and reducing cell polarization. Accordingly, the deposition of Zn coating, prepared by the rapid microwave heating, shows a positive effect on the rate-capability improvement of Li{sub 4}Ti{sub 5}O{sub 12} anodes.

  15. Metasurface polarization splitter

    CERN Document Server

    Slovick, Brian A; Yu, Zhi Gang; Kravchenckou, Ivan I; Briggs, Dayrl P; Moitra, Parikshit; Krishnamurthy, Srini; Valentine, Jason

    2016-01-01

    Polarization beam splitters, devices that separate the two orthogonal polarizations of light into different propagation directions, are one of the most ubiquitous optical elements. However, traditionally polarization splitters rely on bulky optical materials, while emerging optoelectronic and photonic circuits require compact, chip-scale polarization splitters. Here we show that a subwavelength rectangular lattice of cylindrical silicon Mie resonators functions as a polarization splitter, efficiently reflecting one polarization while transmitting the other. We show that the polarization splitting arises from the anisotropic permittivity and permeability of the metasurface due to the two-fold rotational symmetry of the rectangular unit cell. The high polarization efficiency, low loss, and low profile make these metasurface polarization splitters ideally suited for monolithic integration with optoelectronic and photonic circuits.

  16. Polarized targets and beams

    International Nuclear Information System (INIS)

    First the experimental situation of the single-pion photoproduction and the photodisintegration of the deuteron is briefly discussed. Then a description of the Bonn polarization facilities is given. The point of main effort is put on the polarized target which plays a vital role in the program. A facility for photon induced double polarization experiments at ELSA will be presented in section 4. Properties of a tensor polarized deuteron target are discussed in section 5. The development in the field of polarized targets, especially on new target materials, enables a new generation of polarized target experiments with (polarized) electrons. Some comments on the use of a polarized target in combination with electron beams will be discussed in section 6. Electron deuteron scattering from a tensor polarized deuteron target is considered and compared with other experimental possibilities. (orig./HSI)

  17. Redox Stable Anodes for Solid Oxide Fuel Cells

    Directory of Open Access Journals (Sweden)

    Guoliang eXiao

    2014-06-01

    Full Text Available Solid oxide fuel cells (SOFCs can convert chemical energy from the fuel directly to electrical energy with high efficiency and fuel flexibility. Ni-based cermets have been the most widely adopted anode for SOFCs. However, the conventional Ni-based anode has low tolerance to sulfur-contamination, is vulnerable to deactivation by carbon build-up (coking from direct oxidation of hydrocarbon fuels, and suffers volume instability upon redox cycling. Among these limitations, the redox instability of the anode is particularly important and has been intensively studied since the SOFC anode may experience redox cycling during fuel cell operations even with the ideal pure hydrogen as the fuel. This review aims to highlight recent progresses on improving redox stability of the conventional Ni-based anode through microstructure optimization and exploration of alternative ceramic-based anode materials.

  18. Materials characterization of cermet anodes tested in a pilot cell

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, C.F. Jr.; Strachan, D.M.; Henager, C.H. Jr. (Pacific Northwest Lab., Richland, WA (United States)); Alcorn, T.R.; Tabereaux, A.T.; Richards, N.E. (Reynolds Metals Co., Muscle Shoals, AL (United States). Mfg. Technology Lab.)

    1993-02-01

    Cermet anodes were evaluated as nonconsumable substitutes for carbon anodes using a pilot-scale reduction cell at the Reynolds Manufacturing Technology Laboratory. After pilot cell testing, tile anodes were subjected to extensive materials characterization and physical properties measurements at the Pacific Northwest Laboratory. Significant changes in the composition of the cermet anodes were observed including the growth of a reaction layer and penetration of electrolyte deep into the cermet matrix. Fracture strength and toughness were measured as a function of temperature and the ductile-brittle transition wasreduced by 500C following pilot cell testing. These results imply difficulties with anode material and control of operating conditions in the pilot cell, and suggest that additional development work be performed before the cermet anodes are used in commercial reduction cells. The results also highlight specific fabrication and operational considerations that should be addressed in future testing.

  19. Fundamental Investigation of Si Anode in Li-Ion Cells

    Science.gov (United States)

    Wu, James J.; Bennett, William R.

    2012-01-01

    Silicon is a promising and attractive anode material to replace graphite for high capacity lithium ion cells since its theoretical capacity is approximately 10 times of graphite and it is an abundant element on earth. However, there are challenges associated with using silicon as Li-ion anode due to the significant first cycle irreversible capacity loss and subsequent rapid capacity fade during cycling. In this paper, cyclic voltammetry and electrochemical impedance spectroscopy are used to build a fundamental understanding of silicon anodes. The results show that it is difficult to form the SEI film on the surface of Si anode during the first cycle, the lithium ion insertion and de-insertion kinetics for Si are sluggish, and the cell internal resistance changes with the state of lithiation after electrochemical cycling. These results are compared with those for extensively studied graphite anodes. The understanding gained from this study will help to design better Si anodes.

  20. Anodes Stimulate Anaerobic Toluene Degradation via Sulfur Cycling in Marine Sediments

    Science.gov (United States)

    Daghio, Matteo; Vaiopoulou, Eleni; Patil, Sunil A.; Suárez-Suárez, Ana; Head, Ian M.

    2015-01-01

    Hydrocarbons released during oil spills are persistent in marine sediments due to the absence of suitable electron acceptors below the oxic zone. Here, we investigated an alternative bioremediation strategy to remove toluene, a model monoaromatic hydrocarbon, using a bioanode. Bioelectrochemical reactors were inoculated with sediment collected from a hydrocarbon-contaminated marine site, and anodes were polarized at 0 mV and +300 mV (versus an Ag/AgCl [3 M KCl] reference electrode). The degradation of toluene was directly linked to current generation of up to 301 mA m−2 and 431 mA m−2 for the bioanodes polarized at 0 mV and +300 mV, respectively. Peak currents decreased over time even after periodic spiking with toluene. The monitoring of sulfate concentrations during bioelectrochemical experiments suggested that sulfur metabolism was involved in toluene degradation at bioanodes. 16S rRNA gene-based Illumina sequencing of the bulk anolyte and anode samples revealed enrichment with electrocatalytically active microorganisms, toluene degraders, and sulfate-reducing microorganisms. Quantitative PCR targeting the α-subunit of the dissimilatory sulfite reductase (encoded by dsrA) and the α-subunit of the benzylsuccinate synthase (encoded by bssA) confirmed these findings. In particular, members of the family Desulfobulbaceae were enriched concomitantly with current production and toluene degradation. Based on these observations, we propose two mechanisms for bioelectrochemical toluene degradation: (i) direct electron transfer to the anode and/or (ii) sulfide-mediated electron transfer. PMID:26497463

  1. Microstructural degradation of Ni-YSZ anodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Thyden, K.

    2008-03-15

    Ni-YSZ cermets have been used as anode materials in SOFCs for more than 20 years. Despite this fact, the major cause of degradation within the Ni-YSZ anode, namely Ni sintering / coarsening, is still not fully understood. Even if microstructural studies of anodes in tested cells are of technological relevance, it is difficult to identify the effect from isolated parameters such as temperature, fuel gas composition and polarization. Model studies of high temperature aged Ni-YSZ cermets are generally performed in atmospheres containing relatively low concentrations of H2O. In this work, the microstructural degradation in both electrochemically longterm tested cells and high-temperature aged model materials are studied. Since Ni particle sintering / coarsening is attributed to be the major cause of anode degradation, this subject attains the primary focus. A large part of the work is focused on improving microstructural techniques and shows that the application of low acceleration voltages (<= 1 kV) in a FE-SEM makes it possible to obtain two useful types of contrast between the phases in Ni-YSZ composites. By changing between the ordinary lateral SE detector and the inlens detector, using similar microscope settings, two very different sample characteristics are probed: 1) The difference in secondary emission coefficient, delta, between the percolating and non-percolating Ni is maximized in the low-voltage range due to a high delta for the former and the suppression of delta by a positive charge for the latter. This difference yields a contrast between the two phases which is picked up by an inlens secondary electron detector. 2) The difference in backscatter coefficient, eta, between Ni and YSZ is shown to increase with decreasing voltage. The contrast is illustrated in images collected by the normal secondary detector since parts of the secondary signals are generated by backscattered electrons. High temperature aging experiments of model Ni-YSZ anode cermets show

  2. Effective pulsed-repetitive vircator with double anode grid

    International Nuclear Information System (INIS)

    In this paper we present investigation results of a vircator characteristics with a double anode grid operating in pulsed-repetitive regime. Electrons were emitted with a plain graphite cathode and injected to a parabolic drift chamber of the vircator through the anode, made of tungsten wire. Experimentally it was shown that use of the anode on the form of double grid provides significant increase of the generated microwave radiation in comparison with a traditional single-grid variant

  3. Battery, especially for portable devices, has an anode containing silicon

    OpenAIRE

    S. Y. Kan

    2002-01-01

    The anode (2) contains silicon. A battery with a silicon-containing anode is claimed. An Independent claim is also included for a method used to make the battery, comprising the doping of a silicon substrate (1) with charge capacity-increasing material (preferably boron, phosphorous or arsenic), etching the doped substrate layer in order to increase its porosity, and applying a cathode (3) in the form of a lithium oxide compound onto the resulting anode and applying an electrolyte (4) to the ...

  4. Effects of Anodic Voltages on Microstructure and Properties of Plasma Electrolytic Oxidation Coatings on Biomedical NiTi Alloy

    Institute of Scientific and Technical Information of China (English)

    Jilin Xu; Fu Liu; Junming Luo; Liancheng Zhao

    2013-01-01

    Plasma electrolytic oxidation (PEO) coatings,formed under various anodic voltages (320-440 V) on biomedical NiTi alloy,are mainly composed of γ-Al2O3 crystal phase.The evolution of discharging sparks during the PEO process under different anodic voltages was observed.The surface and cross-sectional morphologies,composition,bonding strength,wear resistance and corrosion resistance of the coatings were investigated by scanning electron microscopy (SEM),thin-film X-ray diffraction (TF-XRD),energy dispersive X-ray spectrometry (EDS),surface roughness,direct pull-off test,ball-on-disk friction and wear test and potentiodynamic polarization test,respectively.The results showed that the evolution of discharging sparks during the PEO process directly influenced the microstructure of the PEO coatings and further influences the properties.When the anodic voltage increased from 320 V to 400 V,the corrosion resistance and wear resistance of the coatings slowly increased,and all the bonding strength was higher than 60 MPa; further increasing the anodic voltages,especially up to 440 V,although the thickness and γ-Al2O3 crystallinity of the coatings further increased,the microstructure and properties of the coatings were obviously deteriorated.

  5. The Performance of Electron-Mediator Modified Activated Carbon as Anode for Direct Glucose Alkaline Fuel Cell

    Directory of Open Access Journals (Sweden)

    Zi Li

    2016-06-01

    Full Text Available Six different electron mediators were immobilized on the activated carbon (AC anode and their effects on performance of a direct glucose alkaline fuel cell were explored. 2-hydroxy-1, 4-naphthoquinone (NQ, methyl viologen (MV, neutral red (NR, methylene blue (MB, 1, 5-dichloroanthraquinone (DA and anthraquinone (AQ were doped in activated carbon (AC, respectively, and pressed on nickel foam to fabricate the anodes. NQ shows comparable performance with MV, but with much lower cost and environmental impact. With NQ-AC anode, the fuel cell attained a peak power density of 16.10 Wm−2, peak current density of 48.09 Am−2, and open circuit voltage of 0.76 V under the condition of 1 M glucose, 3 M KOH, and ambient temperature. Polarization curve, EIS and Tafel measurements were also conducted to explore the mechanism of performance enhancement. The high performance is likely due to the enhanced charge transfer and more reactive sites provided on the anode.

  6. Anodization of Aluminium using a fast two-step process

    Indian Academy of Sciences (India)

    Murugaiya Sridar Ilango; Amruta Mutalikdesai; Sheela K Ramasesha

    2016-01-01

    Ultra-fast two-step anodization method is developed for obtaining ordered nano-pores on aluminium (Al) foil. First anodization was carried out for 10 min, followed by 3 min of second anodization at high voltage (150 V) compared to previous reports of anodization times of 12 h (40-60 V). The pore dimensions on anodized alumina are 180 nm for pore diameter and 130 nm for inter-pore distance. It was evident that by increasing the anodization voltage to 150 V, the diameter of the pores formed was above 150 nm. The electrolyte and its temperature affect the shape and size of the pore formation. At lower anodization temperature, controlled pore formation was observed. The anodized samples were characterized using the field emission scanning electron microscope (FE-SEM) to determine the pore diameter and inter-pore distance. Using UVVisible spectroscopy, the reflectance spectra of anodized samples were measured. The alumina (Al2O3) peaks were identified by x-ray diffraction (XRD) technique. The x-ray photo electron spectroscopy (XPS) analysis confirmed the Al 2p peak at 73.1 eV along with the oxygen O 1s at 530.9 eV and carbon traces C 1s at 283.6 eV.

  7. The corrosion protection of 2219-T87 aluminum by anodizing

    Science.gov (United States)

    Danford, M. D.

    1991-01-01

    Various types of anodizing coatings were studied for 2219-T87 aluminum. These include both type II and type III anodized coats which were water sealed and a newly developed and proprietary Magnaplate HCR (TM) coat. Results indicate that type II anodizing is not much superior to type II anodizing as far as corrosion protection for 2219-T87 aluminum is concerned. Magnaplate HCR (TM) coatings should provide superior corrosion protection over an extended period of time using a coating thickness of 51 microns (2.0 mils).

  8. Generation of high brightness ion beam from insulated anode PED

    International Nuclear Information System (INIS)

    Generation and focusing of a high density ion beam with high brightness from a organic center part of anode of a PED was reported previously. Mass, charge and energy distribution of this beam were analyzed. Three kind of anode were tried. Many highly ionized medium mass ions (up to C4+, O6+) accelarated to several times of voltage difference between anode and cathode were observed. In the case of all insulator anode the current carried by the medium mass ions is about half of that carried by protons. (author)

  9. Aluminium anode for biogalvanic metal--oxygen -cells

    Energy Technology Data Exchange (ETDEWEB)

    Weidlich, E.

    1975-02-20

    The invention deals with an aluminium anode for biogalvanic metal--oxygen cells. The object of the invention is to improve further an aluminium anode for biogalvanic metal--oxygen cells. In particular, the lifetime is to be increased and the Faraday degree of efficiency is to be improved by suppressing an excessive hydrogen development. The anode is thus constructed so as to have a metal net on both sides with aluminium layers, and the surfaces of the aluminium layers not facing the metal net are lapped or sand-blasted and have an anodized layer on their boundary regions.

  10. Testing and Characterization of Anode Current in Aluminum Reduction Cells

    Science.gov (United States)

    Wang, Yongliang; Tie, Jun; Sun, Shuchen; Tu, Ganfeng; Zhang, Zhifang; Zhao, Rentao

    2016-06-01

    Anode current is an important parameter in the aluminum reduction process, but to test the anode current accurately is difficult at present. This study tested the individual anode current using the fiber-optic current sensor. The testing results show that this method can effectively avoid the interference of the electromagnetic field, and the current is measured with high precision which error is less than 1 pct. In the paper, the test currents under different cell conditions, including anode changing, metal tapping, abnormal current, and anode effect, are investigated using the method of time-domain and frequency-domain analysis, and the simulation method is also combined to investigate the cell conditions. The results prove that different cell conditions will show different anode current characteristics, and the individual current can monitor the cell conditions, especially the localized cell conditions. Some abnormal cell conditions can be found through anode current rather than cell voltage. The anode current can also be used for early detection of anode effect.

  11. Effect of natural marine biofilms on galvanic corrosion predicted using potentiodynamic polarization curves

    Energy Technology Data Exchange (ETDEWEB)

    Dexter, S.C.; LaFontaine, J.P. [Univ. of Delaware, Lewes, DE (United States). Coll. of Marine Studies

    1998-12-31

    Galvanic corrosion of copper, 1018 steel, 3003 aluminum and zinc coupled in turn to cathodes of stainless steel alloy N08367 was tested with and without natural marine biofilms on the cathode surface. Weight losses were significantly higher, and corrosion currents were up to two decades higher with a biofilm on the cathode surface for anodes of copper, steel and aluminum, but there was no difference for zinc. Results indicate that, in any case where biofilms on the cathodic member of a galvanic couple result in a systematic and significant increase in the reduction current at the mixed potential of the couple, an increase in consumption of the anodic material should be expected. Cathodic reduction currents (vs. controls with no biofilm) were increased at all potentials down to about {minus}900 mV{sub SCE}, resulting in an elevated current capacity capable of increasing the weight loss of anodic materials over a sustained period of at least two months. Biofilms, however, did not increase consumption of sacrificial anodes with potentials equal to, or more active than zinc. Potentiodynamic polarization curves taken from the corroded samples were used successfully to predict the effect of biofilms on galvanic corrosion rates for the materials tested. Weight loss values calculated by Faraday`s law using corrosion currents from the polarization curves agreed well with actual measured values for anodes of steel, aluminum and zinc, although there were some discrepancies for copper.

  12. NESDIS VIIRS Polar Winds

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains the Level 3 Polar Winds Northern and Southern Hemisphere datasets. The Level 3 Polar Winds data from VIIRS for the Arctic and Antarctic from...

  13. Synthesis and characterization of new ternary transition metal sulfide anodes for H 2S-powered solid oxide fuel cell

    Science.gov (United States)

    Vorontsov, V.; Luo, J. L.; Sanger, A. R.; Chuang, K. T.

    A number of ternary transition metal sulfides with general composition AB 2S 4 (where A and B are different transition metal atoms) have been prepared and investigated as potential anode catalysts for use in H 2S-powered solid oxide fuel cells (SOFCs). For the initial screening, polarization resistance of the materials was measured in a two electrode symmetrical cell at 700-850 °C. Vanadium-based materials showed the lowest polarization resistance, and so were chosen for subsequent full cell tests using the configuration [H 2S, AV 2S 4/YSZ/Pt, air] (where A = Ni, Cr, Mo). MoV 2S 4 anode had superior activity and performance in the full cell setup, consistent with results from symmetrical cell tests. Polarization curves showed MoV 2S 4 had the lowest potential drop, with up to a 200 mA cm -2 current density at 800 °C. The highest power density of ca. 275 mW cm -2 at 800 °C was obtained with a pure H 2S stream. Polarization resistance of materials was a strong function of current density, and showed a sharp change of slope attributable to a change in the rate-limiting step of the anode reaction mechanism. MoV 2S 4 was chemically stable during prolonged (10 days) exposure to H 2S at 850 °C, and fuel cell performance was stable during continuous 3-day operation at 370 mA cm -2 current density.

  14. Results from some anode wire aging tests

    International Nuclear Information System (INIS)

    Using twin setups to test anode wire aging in small gas avalanche tubes, a variety of different gas mixtures were tried and other parameters were varied to study their effects upon the gain drop, nomalized to charge transfer: - 1/Q dI/I. This was found to be quite sensitive to the purity of the gases, and also sensitive to the nominal gain and the gas flow rate. The wire surface material can also significantly affect the aging, as can additives, such as ethanol or water vapor. Certain gas mixtures have been found to be consistent with zero aging at the sensitivity level of this technique

  15. STUDY ON COMPOSITION IN NIOBIUM ANODE

    Institute of Scientific and Technical Information of China (English)

    Li Chunguang; Gao Yong; Dong Ningli

    2004-01-01

    Niobium capacitor uses electrolytic Nb2O5 as dielectric layer formed on surface of porous niobium anode through electrolytic reaction. Analysis of Scanning Electronics Microscope (SEM) combined with X-ray Photoemission Spectrum(XPS) shows that the formed niobium oxide dielectric consists of not only Nb2O5, but also two kinds of low valence niobium NbO2 and NbO oxide. When using different electrolytic reaction conditions, different valence niobium oxide shows different relative content. The fact provides an important basis for analyzing and improving performances of niobium capacitor.

  16. Nanotube Arrays in Porous Anodic Alumina Membranes

    Institute of Scientific and Technical Information of China (English)

    Liang LI; Naoto KOSHIZAKI; Guanghai LI

    2008-01-01

    This review summarizes the various techniques developed for fabricating nanotube arrays in porous anodic alumina membranes (AAMs). After a brief introduction to the fabrication process of AAMs, taking carbons, metals, semiconductors, organics, biomoleculars, and heterojunctions as typical examples, attention will be focused on the recently established methods to fabricate nanotubes in AAM, including electrochemical deposition, surface sol-gel, modified chemical vapor deposition, atomic layer deposition, and layer-by-layer growth. Every method is demonstrated by one or two reported results. Finally, this review is concluded with some perspectives on the research directions and focuses on the AAM-based nanotubes fields.

  17. Bumblebees Learn Polarization Patterns

    OpenAIRE

    Foster, James J.; Sharkey, Camilla R.; Gaworska, Alicia V.A.; Roberts, Nicholas W.; Whitney, Heather M.; Partridge, Julian C.

    2014-01-01

    Summary Foraging insect pollinators such as bees must find and identify flowers in a complex visual environment. Bees use skylight polarization patterns for navigation [1–3], a capacity mediated by the polarization-sensitive dorsal rim area (DRA) of their eye [4, 5]. While other insects use polarization sensitivity to identify appropriate habitats [6], oviposition sites, and food sources [7], to date no nonnavigational functions of polarization vision have been identified in bees. Here we inv...

  18. Performance and life-time behaviour of NiCu-CGO anodes for the direct electro-oxidation of methane in IT-SOFCs

    Science.gov (United States)

    Sin, A.; Kopnin, E.; Dubitsky, Y.; Zaopo, A.; Aricò, A. S.; La Rosa, D.; Gullo, L. R.; Antonucci, V.

    An anodic cermet of NiCu alloy and gadolinia doped ceria has been investigated for CH 4 electro-oxidation in IT-SOFCs. Polarization curves have been recorded in the temperature range from 650 to 800 °C. A maximum power density of 320 mW cm -2 at 800 °C has been obtained in the presence of dry methane in an electrolyte-supported cell. The electrochemical behaviour during 1300 h operation in dry methane and in the presence of redox-cycles has been investigated at 750 °C; variation of the electrochemical properties during these experiments have been interpreted in terms of anode morphology modifications. The methane cracking process at the anode catalyst has been investigated by analysing the oxidative stripping of deposited carbon species.

  19. Performance and life-time behaviour of NiCu-CGO anodes for the direct electro-oxidation of methane in IT-SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Sin, A.; Kopnin, E.; Dubitsky, Y.; Zaopo, A. [Pirelli Labs S.p.A., Viale Sarca 222, I-20126 Milan (Italy); Arico, A.S.; La Rosa, D.; Gullo, L.R.; Antonucci, V. [CNR-ITAE, Via Salita Santa Lucia Sopra Contesse 5, I-98125 Messina (Italy)

    2007-01-10

    An anodic cermet of NiCu alloy and gadolinia doped ceria has been investigated for CH{sub 4} electro-oxidation in IT-SOFCs. Polarization curves have been recorded in the temperature range from 650 to 800{sup o}C. A maximum power density of 320mWcm{sup -2} at 800{sup o}C has been obtained in the presence of dry methane in an electrolyte-supported cell. The electrochemical behaviour during 1300h operation in dry methane and in the presence of redox-cycles has been investigated at 750{sup o}C; variation of the electrochemical properties during these experiments have been interpreted in terms of anode morphology modifications. The methane cracking process at the anode catalyst has been investigated by analysing the oxidative stripping of deposited carbon species. (author)

  20. Preparation of IrO2+MnO2 coating anodes and their application in NaClO production

    Institute of Scientific and Technical Information of China (English)

    Yongle Ni; Huimin Meng; Dong Chen; Dongbai Sun; Hongying Yu

    2008-01-01

    To improve the durability as well as to reduce the cost of anodes, the IrO2+MnO2 composite coating anodes for NaC10 production were prepared by thermal decomposition. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction analysis (XRD) were carried out to investigate the morphologies, element distribution, and microstructure. The anodic polarization curves were employed to study the effect of sintering temperature on the C12 evolution reaction (CER) of the electrodes. The accelerated life tests (ALT) and electrochemical impedance spectroscopy measurement (EIS) were utilized to investigate the stability. The rules of NaC10 production were also studied by the static electrolysis experiment. The results indicate that sintering temperature has a significant influence on the CER properties as well as the ALT values of the electrodes. The electrode prepared at 400℃ has the best CER properties and the longest ALT value.

  1. Graphing Polar Curves

    Science.gov (United States)

    Lawes, Jonathan F.

    2013-01-01

    Graphing polar curves typically involves a combination of three traditional techniques, all of which can be time-consuming and tedious. However, an alternative method--graphing the polar function on a rectangular plane--simplifies graphing, increases student understanding of the polar coordinate system, and reinforces graphing techniques learned…

  2. Polarized triplet production by circularly polarized photons

    CERN Document Server

    Bytev, V V; Galynsky, M V; Potylitsin, A P

    2002-01-01

    A process of the pair production by a circularly polarized photon in the field of unpolarized atomic electron has been considered in the Weizaecker-Williams approximation. The degree of longitudinal polarization of positron and electron has been calculated. An exclusive cross-section as well as a spectral distribution are obtained. We estimate the accuracy of our calculations at the level of a few percent. We show the identity of the positron polarization for considered process and for process of pair production in the screened Coulomb field of nucleus.

  3. CO tolerance of proton exchange membrane fuel cells with Pt/C and PtMo/C anodes operating at high temperatures: A mass spectrometry investigation

    International Nuclear Information System (INIS)

    Highlights: ► CO tolerance of Pt/C and PtMo/C PEMFC anodes is investigated by on line mass spectrometry. ► High CO tolerance is observed for high PEMFC temperatures. ► Increase of tolerance for Pt/C is due to thermal desorption, reduced CO oxidation potentials, and CO oxidation by O2 crossover. ► PtMo/C presents increased CO tolerance due the occurrence of a MoOx-mediated was gas shift reaction. -- Abstract: The performance of proton exchange membrane fuel cells (PEMFC) with Pt/C and PtMo/C anodes has been investigated using single cell polarization and on line mass spectrometry (OLMS) measurements in a wide range of temperature (70–105 °C) for the system supplied with hydrogen containing different amounts of CO. As expected a higher CO tolerance is observed at higher temperatures for both catalysts. The anode exit gas analysis revealed that CO2 is produced already at the cell open circuit potential, and it increases with the increase of the anode overpotential. The CO tolerance phenomena are assigned to different processes depending on the catalyst nature. For the Pt/C containing anodes, at temperatures above 80 °C, thermal desorption, reduced CO oxidation potential and CO oxidation by O2 crossover are responsible for enhanced tolerance, whilst PtMo/C shows greater tolerance due the occurrence of a MoOx-mediated water gas shift reaction (WGS), which is activated at high temperatures. Although the occurrence of WGS leads to the anode poisoning in the presence of CO2, the polarization results show that only small additive contamination effect occurs by the combined presence of CO + CO2 in the hydrogen stream

  4. Anodic dissolution of metals in ionic liquids

    Directory of Open Access Journals (Sweden)

    Andrew P. Abbott

    2015-12-01

    Full Text Available The anodic dissolution of metals is an important topic for battery design, material finishing and metal digestion. Ionic liquids are being used in all of these areas but the research on the anodic dissolution is relatively few in these media. This study investigates the behaviour of 9 metals in an ionic liquid [C4mim][Cl] and a deep eutectic solvent, Ethaline, which is a 1:2 mol ratio mixture of choline chloride and ethylene glycol. It is shown that for the majority of metals studied a quasi-passivation of the metal surface occurs, primarily due to the formation of insoluble films on the electrode surface. The behaviour of most metals is different in [C4mim][Cl] to that in Ethaline due in part to the differences in viscosity. The formation of passivating salt films can be decreased with stirring or by increasing the electrolyte temperature, thereby increasing ligand transport to the electrode surface.

  5. Wideband film polarizer design

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The reflection and transmittance of s- and p-polarized lights should be treated separately at nonzero angle incidence.By choosing two special film materials whose refractive indices meet the Brewster condition in a given incident angle,the reflection of p-polarized light can be eliminated.When the two materials are fabricated into multilayer stacks,the reflection of s-polarized light can be largely increased while the reflection of p-polarized light keeps low.According to this principle,a film polarizer with bandwidth of 198 nm or even more is designed.

  6. Etude de l'anode pour la pile à combustible directe aux borohydrures

    OpenAIRE

    Olu, Pierre-Yves

    2015-01-01

    The present work focuses on direct borohydride fuel cell (DBFC) anodes. A first approach to develop a suitable anode design for the DBFC consists in the study of the anode within the real DBFC system. In that frame, carbon-supported platinum and palladium nanoparticles are characterized and compared as anode electrocatalyst in DBFC configuration. Other variables such as the morphology of the anode and the stability of the catalyst nanoparticles are considered.The ideal DBFC anode catalyst sho...

  7. New development of anodizing process of magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    BAI Li-qun; LI Di

    2004-01-01

    Magnesium alloy, a kind of environment-friendly material with promising and excellent properties, is a good choice for a number of applications. The research and development of anodizing on magnesium alloys and its application situation are reviewed, and the anodizing development trend on magnesium alloys is summarized.

  8. Battery, especially for portable devices, has an anode containing silicon

    NARCIS (Netherlands)

    Kan, S.Y.

    2002-01-01

    The anode (2) contains silicon. A battery with a silicon-containing anode is claimed. An Independent claim is also included for a method used to make the battery, comprising the doping of a silicon substrate (1) with charge capacity-increasing material (preferably boron, phosphorous or arsenic), etc

  9. Fundamental Investigation of Silicon Anode in Lithium-Ion Cells

    Science.gov (United States)

    Wu, James J.; Bennett, William R.

    2012-01-01

    Silicon is a promising and attractive anode material to replace graphite for high capacity lithium ion cells since its theoretical capacity is 10 times of graphite and it is an abundant element on Earth. However, there are challenges associated with using silicon as Li-ion anode due to the significant first cycle irreversible capacity loss and subsequent rapid capacity fade during cycling. Understanding solid electrolyte interphase (SEI) formation along with the lithium ion insertion/de-insertion kinetics in silicon anodes will provide greater insight into overcoming these issues, thereby lead to better cycle performance. In this paper, cyclic voltammetry and electrochemical impedance spectroscopy are used to build a fundamental understanding of silicon anodes. The results show that it is difficult to form the SEI film on the surface of a Si anode during the first cycle; the lithium ion insertion and de-insertion kinetics for Si are sluggish, and the cell internal resistance changes with the state of lithiation after electrochemical cycling. These results are compared with those for extensively studied graphite anodes. The understanding gained from this study will help to design better Si anodes, and the combination of cyclic voltammetry with impedance spectroscopy provides a useful tool to evaluate the effectiveness of the design modifications on the Si anode performance.

  10. Optimal Conditions for Fast Charging and Long Cycling Stability of Silicon Microwire Anodes for Lithium Ion Batteries, and Comparison with the Performance of Other Si Anode Concepts

    OpenAIRE

    Enrique Quiroga-González; Jürgen Carstensen; Helmut Föll

    2013-01-01

    Cycling tests under various conditions have been performed for lithium ion battery anodes made from free-standing silicon microwires embedded at one end in a copper current collector. Optimum charging/discharging conditions have been found for which the anode shows negligible fading (< 0.001%) over 80 cycles; an outstanding result for this kind of anodes. Several performance parameters of the anode have been compared to the ones of other Si anode concepts, showing that especially the capacity...

  11. Polarity inversion in polar-nonpolar-polar heterostructures.

    Science.gov (United States)

    Cho, S; Youn, S J; Kim, Y; DiVenere, A; Wong, G K; Freeman, A J; Ketterson, J B

    2001-09-17

    We have observed an epilayer-thickness-dependent polarity inversion for the growth of CdTe on Sb(Bi)/CdTe(111)B. For films with Sb(Bi) thicknesses of less than 40 A (15 A), the CdTe layer shows a B (Te-terminated) face, but it switches to an A (Cd-terminated) face for thicker layers. On the other hand, a CdTe layer grown on Bi(Sb)/CdTe(111)A always shows the A face regardless of Sb or Bi layer thicknesses. In order to address the observations we have performed ab initio calculations, which suggest that the polarity of a polar material on a nonpolar one results from the binding energy difference between the two possible surface configurations.

  12. Development of Planar Metal Supported SOFC with Novel Cermet Anode

    DEFF Research Database (Denmark)

    Blennow Tullmar, Peter; Hjelm, Johan; Klemensø, Trine;

    2009-01-01

    SOFC, electrode material from the active anode layer may interdiffuse with the metallic support during sintering. The purpose of this work is to illustrate how the interdiffusion problem can be circumvented by using an alternative anode design based on porous and electronically conducting layers......Metal-supported solid oxide fuel cells are expected to offer several potential advantages over conventional anode (Ni-YSZ) supported cells, such as increased resistance against mechanical and thermal stresses and a reduction in materials cost. When Ni-YSZ based anodes are used in metal supported......, into which electrocatalytically active materials are infiltrated after sintering. The paper presents the recent results on the electrochemical performance and durability of the novel planar metal-supported SOFC design. The results presented in the paper show that the novel cell and anode design has...

  13. Growth of anatase titanium dioxide nanotubes via anodization

    Directory of Open Access Journals (Sweden)

    Ed Adrian Dilla

    2012-06-01

    Full Text Available In this work, titanium dioxide nanotubes were grown via anodization of sputtered titanium thin films using different anodization parameters in order to formulate a method of producing long anatase titanium dioxide nanotubes intended for solar cell applications. The morphological features of the nanotubes grown via anodization were explored using a Philips XL30 Field Emission Scanning Electron Microscope. Furthermore, the grown nanotubes were also subjected to X-ray diffraction and Raman spectroscopy in order to investigate the effect of the predominant crystal orientation of the parent titanium thin film on the crystal phase of the nanotubes. After optimizing the anodization parameters, nanotubes with anatase TiO2 crystal phase and tube length more than 2 microns was produced from parent titanium thin films with predominant Ti(010 crystal orientation and using ammonium fluoride in ethylene glycol as an electrolyte with a working voltage equal to 60V during 1-hour anodization runs.

  14. Natural gas anodes for aluminium electrolysis in molten fluorides.

    Science.gov (United States)

    Haarberg, Geir Martin; Khalaghi, Babak; Mokkelbost, Tommy

    2016-08-15

    Industrial primary production of aluminium has been developed and improved over more than 100 years. The molten salt electrolysis process is still suffering from low energy efficiency and considerable emissions of greenhouse gases (CO2 and PFC). A new concept has been suggested where methane is supplied through the anode so that the CO2 emissions may be reduced significantly, the PFC emissions may be eliminated and the energy consumption may decrease significantly. Porous carbon anodes made from different graphite grades were studied in controlled laboratory experiments. The anode potential, the anode carbon consumption and the level of HF gas above the electrolyte were measured during electrolysis. In some cases it was found that the methane oxidation was effectively participating in the anode process. PMID:27210046

  15. Interfacial chemistry of zinc anodes for reinforced concrete structures

    Energy Technology Data Exchange (ETDEWEB)

    Covino, B.S. Jr.; Bullard, S.J.; Cramer, S.D.; Holcomb, G.R. [Dept. of Energy, Albany, OR (United States). Albany Research Center; McGill, G.E.; Cryer, C.B. [Oregon Dept. of Transportation, Salem, OR (United States); Stoneman, A. [International Lead Zinc Research Organization, Research Triangle Park, NC (United States); Carter, R.R. [California Dept. of Transportation, Sacramento, CA (United States)

    1997-12-01

    Thermally-sprayed zinc anodes are used in both galvanic and impressed current cathodic protection systems for reinforced concrete structures. The Albany Research Center, in collaboration with the Oregon Department of Transportation, has been studying the effect of electrochemical aging on the bond strength of zinc anodes for bridge cathodic protection systems. Changes in anode bond strength and other anode properties can be explained by the chemistry of the zinc-concrete interface. The chemistry of the zinc-concrete interface in laboratory electrochemical aging studies is compared with that of several bridges with thermal-sprayed zinc anodes and which have been in service for 5 to 10 years using both galvanic and impressed current cathodic protection systems. The bridges are the Cape Creek Bridge on the Oregon coast and the East Camino Undercrossing near Placerville, CA. Also reported are interfacial chemistry results for galvanized steel rebar from the 48 year old Longbird Bridge in Bermuda.

  16. Investigation of Anode Striation in 34VGA Shadow Mask PDP

    Institute of Scientific and Technical Information of China (English)

    TU Yan; JIANG Youyan; YANG Lanlan; ZHANG Xiong; WANG Baoping

    2007-01-01

    A macro-cell was used to study the phenomenon of anode striation on a 34 VGA Shadow Mask Plasma Display Panel(SMPDP).The breakdown process in the sustaining period of the macro-cell was taken by an Intensified Charge Coupled Device(ICCD)with narrow band filters.The mechanism of formation and evolution of the anode striation on SMPDP were investigated.The influence of the width of the electrode,the sustaining voltage,sustaining frequency and the voltage of the shadow mask on the anode striation was also studied.The results showed that the width of the electrodes,the sustaining voltage and frequency had a strong influence on the anode striation.The voltage of the shadow mask,however,hardly affected the anode striation,the firing voltage or the sustaining voltage.

  17. Recovery of plutonium from electrorefining anode heels at Savannah River

    International Nuclear Information System (INIS)

    In a joint effort, the Savannah River Laboratory (SRL), Savannah River Plant (SRP), and the Rocky Flats Plant (RFP) have developed two processes to recover plutonium from electrorefining anode heel residues. Aqueous dissolution of anode heel metal was demonstrated at SRL on a laboratory scale and on a larger pilot scale using either sulfamic acid or nitric acid-hydrazine-fluoride solutions. This direct anode heel metal dissolution requires the use of a geometrically favorable dissolver. The second process developed involves first diluting the plutonium in the anode heel residues by alloying with aluminum. The alloyed anode heel plutonium can then be dissolved using a nitric acid-fluoride-mercury(II) solution in large non-geometrically favorable equipment where nuclear safety is ensured by concentration control

  18. Mechanically stable insoluble titanium-lead anodes for sulfate electrolytes

    Directory of Open Access Journals (Sweden)

    Chmiola J.

    2003-01-01

    Full Text Available Different formulations of a new material to be used as an insoluble anode for copper electrowinning, a Ti-Pb composite, were investigated for both mechanical and electrochemical properties. Mechanical and metallographic characteristic tests, as well as short-term deposition tests were used to study the effect of the Ti/Pb ratio on anode performance. Yield strength and elastic modulus, obtained through tensile testing, significantly exceed that of lead. Metallographic procedures were used to assess the uniformity of lead distribution in the material, as well as porosity, which would be decreased below 1 % for most of the compositions under study. Short-term deposition tests were used to determine power consumption, deposit quality current efficiency and weight loss characteristics of the new anode material. The material with only 30 vol.% lead shows approximately the same electrochemical performance as a pure lead anode, but has much higher mechanical properties which prevent warping and extend the lifetime of the anode.

  19. Focused cathode design to reduce anode heating during vircator operation

    Science.gov (United States)

    Lynn, Curtis F.; Dickens, James C.; Neuber, Andreas A.

    2013-10-01

    Virtual cathode oscillators, or vircators, are a type of high power microwave device which operates based on the instability of a virtual cathode, or cloud of electrons, which forms when electron current injected into the drift tube exceeds the space charge limited current within the drift tube. Anode heating by the electron beam during vircator operation ultimately limits achievable pulse lengths, repetition rates, and the duration of burst mode operation. This article discusses a novel cathode design that focuses electrons through holes in the anode, thus significantly reducing anode heating by the electrons emitted from the cathode during the first transit through the A-K gap. Reflexing electrons continue to deposit energy on the anode; however, the discussed minimization of anode heating by main beam electrons has the potential to enable higher repetition rates as well as efficiency and longer diode lifetime. A simulation study of this type of cathode design illustrates possible advantages.

  20. Focused cathode design to reduce anode heating during vircator operation

    Energy Technology Data Exchange (ETDEWEB)

    Lynn, Curtis F.; Dickens, James C.; Neuber, Andreas A. [Center for Pulsed Power and Power Electronics, Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States)

    2013-10-15

    Virtual cathode oscillators, or vircators, are a type of high power microwave device which operates based on the instability of a virtual cathode, or cloud of electrons, which forms when electron current injected into the drift tube exceeds the space charge limited current within the drift tube. Anode heating by the electron beam during vircator operation ultimately limits achievable pulse lengths, repetition rates, and the duration of burst mode operation. This article discusses a novel cathode design that focuses electrons through holes in the anode, thus significantly reducing anode heating by the electrons emitted from the cathode during the first transit through the A-K gap. Reflexing electrons continue to deposit energy on the anode; however, the discussed minimization of anode heating by main beam electrons has the potential to enable higher repetition rates as well as efficiency and longer diode lifetime. A simulation study of this type of cathode design illustrates possible advantages.

  1. Focused cathode design to reduce anode heating during vircator operation

    International Nuclear Information System (INIS)

    Virtual cathode oscillators, or vircators, are a type of high power microwave device which operates based on the instability of a virtual cathode, or cloud of electrons, which forms when electron current injected into the drift tube exceeds the space charge limited current within the drift tube. Anode heating by the electron beam during vircator operation ultimately limits achievable pulse lengths, repetition rates, and the duration of burst mode operation. This article discusses a novel cathode design that focuses electrons through holes in the anode, thus significantly reducing anode heating by the electrons emitted from the cathode during the first transit through the A-K gap. Reflexing electrons continue to deposit energy on the anode; however, the discussed minimization of anode heating by main beam electrons has the potential to enable higher repetition rates as well as efficiency and longer diode lifetime. A simulation study of this type of cathode design illustrates possible advantages

  2. Modeling of gas transport with electrochemical reaction in nickel-yttria-stabilized zirconia anode during thermal cycling by Lattice Boltzmann method

    Science.gov (United States)

    Guo, Pengfei; Guan, Yong; Liu, Gang; Liang, Zhiting; Liu, Jianhong; Zhang, Xiaobo; Xiong, Ying; Tian, Yangchao

    2016-09-01

    This work reports an investigation of the impact of microstructure on the performance of solid oxide fuel cells (SOFC) composed of nickel yttria-stabilized zirconia (Ni YSZ). X-ray nano computed tomography (nano-CT) was used to obtain three-dimensional (3D) models of Ni-YSZ composite anode samples subjected to different thermal cycles. Key parameters, such as triple phase boundary (TPB) density, were calculated using 3D reconstructions. The electrochemical reaction occurring at active-TPB was modeled by the Lattice Boltzmann Method for simulation of multi-component mass transfer in porous anodes. The effect of different electrode geometries on the mass transfer and the electrochemical reaction in anodes was studied by TPB distributions measured by nano CT for samples subjected to different thermal cycles. The concentration polarization and the activation polarization were estimated respectively. The results demonstrate that a combined approach involving nano-CT experiments in conjunction with simulations of gas transport and electrochemical reactions using the Lattice Boltzmann method can be used to better understand the relationship between electrode microstructure and performance of nickel yttria-stabilized zirconia anodes.

  3. Effect of RuCl{sub 3} Concentration on the Lifespan of Insoluble Anode for Cathodic Protection on PCCP

    Energy Technology Data Exchange (ETDEWEB)

    Cho, H. W.; Kim, Y. S. [Materials Research Center for Energy and Clean Technology, School of Materials Science and Engineering, Andong National University, Andong (Korea, Republic of); Chang, H. Y.; Lim, B. T.; Park, H. B. [Power Engineering Research Institute, KEPCO Engineering and Construction Company, Seongnam (Korea, Republic of)

    2015-08-15

    Prestressed Concrete steel Cylinder Pipe (PCCP) is extensively used as seawater pipes for cooling in nuclear power plants. The internal surface of PCCP is exposed to seawater, while the external surface is in direct contact with underground soil. Therefore, materials and strategies that would reduce the corrosion of its cylindrical steel body and external steel wiring need to be employed. To prevent against the failure of PCCP, operators provided a cathodic protection to the pre-stressing wires. The efficiency of cathodic protection is governed by the anodic performance of the system. A mixed metal oxide (MMO) electrode was developed to meet criteria of low over potential and high corrosion resistance. Increasing coating cycles improved the performance of the anode, but cycling should be minimized due to high materials cost. In this work, the effects of RuCl{sub 3} concentration on the electrochemical properties and lifespan of MMO anode were evaluated. With increasing concentration of RuCl{sub 3}, the oxygen evolution potential lowered and polarization resistance were also reduced but demonstrated an increase in passive current density and oxygen evolution current density. To improve the electrochemical properties of the MMO anode, RuCl{sub 3} concentration was increased. As a result, the number of required coating cycles were reduced substantially and the MMO anode achieved an excellent lifespan of over 80 years. Thus, we concluded that the relationship between RuCl{sub 3} concentration and coating cycles can be summarized as follows: No. of coating cycle = 0.48{sup *}[RuCl{sub 3} concentration, M]{sup -0.97}.

  4. Device For Viewing Polarized Light

    Science.gov (United States)

    Noever, David A.

    1995-01-01

    Technique for detection of polarized light based on observation of scene through two stacked polarizing disks. No need to rotate polarizers to create flicker indicative of polarization. Implemented by relatively simple, lightweight apparatus. Polarization seen as bow-tie rainbow pattern. Advantageous for detecting polarization in variety of meteorological, geological, astronomical, and related applications.

  5. Electrical Resistance Measurements and Microstructural Characterization of the Anode/Interconnect Contact in Simulated Anode-Side SOFC Conditions

    DEFF Research Database (Denmark)

    Harthøj, Anders; Alimadadi, Hossein; Holt, Tobias;

    2015-01-01

    in phase transformation of the steel and in formation of oxides with a poor electrical conductivity in the anode. In this study, the area specific resistance (ASR) of the steel Crofer 22 APU, in contact with a Ni/YSZ anode with and without a tape casted CeO2 barrier layer was measured in simulated SOFC...

  6. Calibration of Gamma-ray Burst Polarimeter POLAR

    CERN Document Server

    Xiao, H L; Bao, T W; Batsch, T; Bernasconi, T; Cernuda, I; Chai, J Y; Dong, Y W; Gauvin, N; Kole, M; Kong, M N; Kong, S W; Li, L; Liu, J T; Liu, X; Marcinkowski, R; Orsi, S; Pohl, M; Produit, N; Rapin, D; Rutczynska, A; Rybka, D; Shi, H L; Song, L M; Sun, J C; Szabelski, J; Wu, B B; Wang, R J; Wen, X; Xu, H H; Zhang, L; Zhang, L Y; Zhang, S N; Zhang, X F; Zhang, Y J; Zwolinska, A

    2015-01-01

    Gamma Ray Bursts (GRBs) are the strongest explosions in the universe which might be associated with creation of black holes. Magnetic field structure and burst dynamics may influence polarization of the emitted gamma-rays. Precise polarization detection can be an ultimate tool to unveil the true GRB mechanism. POLAR is a space-borne Compton scattering detector for precise measurements of the GRB polarization. It consists of a 40$\\times$40 array of plastic scintillator bars read out by 25 multi-anode PMTs (MaPMTs). It is scheduled to be launched into space in 2016 onboard of the Chinese space laboratory TG2. We present a dedicated methodology for POLAR calibration and some calibration results based on the combined use of the laboratory radioactive sources and polarized X-ray beams from the European Synchrotron Radiation Facility. They include calibration of the energy response, computation of the energy conversion factor vs. high voltage as well as determination of the threshold values, crosstalk contributions...

  7. Development of anode zone using dual-anode system to reduce organic matter crossover in membraneless microbial fuel cells.

    Science.gov (United States)

    Kim, Jisu; Kim, Bongkyu; An, Junyeong; Lee, Yoo Seok; Chang, In Seop

    2016-08-01

    To prevent the occurrence of the organic crossover in membraneless microbial fuel cells (ML-MFCs), dual-anode MFC (DA-MFC) was designed from multi-anode concept to ensure anode zone. The anode zone addressed increase the utilization of organic matter in ML-MFCs, as the result, the organic crossover was prevented and performance of MFCs were enhanced. The maximum power of the DA-MFC was 0.46mW, which is about 1.56 times higher than the ML-MFC (0.29mW). Furthermore, the DA-MFC had advantage in correlation of organic substance concentration and dissolved oxygen concentration, and even electric over-potential. In addition, in terms of cathode fouling, the DA-MFC showed clearer surface. Hence, the anode zone should be considered in the advanced ML-MFC for practically use in wastewater treatment process, and also for scale-up of MFCs.

  8. Development of anode zone using dual-anode system to reduce organic matter crossover in membraneless microbial fuel cells.

    Science.gov (United States)

    Kim, Jisu; Kim, Bongkyu; An, Junyeong; Lee, Yoo Seok; Chang, In Seop

    2016-08-01

    To prevent the occurrence of the organic crossover in membraneless microbial fuel cells (ML-MFCs), dual-anode MFC (DA-MFC) was designed from multi-anode concept to ensure anode zone. The anode zone addressed increase the utilization of organic matter in ML-MFCs, as the result, the organic crossover was prevented and performance of MFCs were enhanced. The maximum power of the DA-MFC was 0.46mW, which is about 1.56 times higher than the ML-MFC (0.29mW). Furthermore, the DA-MFC had advantage in correlation of organic substance concentration and dissolved oxygen concentration, and even electric over-potential. In addition, in terms of cathode fouling, the DA-MFC showed clearer surface. Hence, the anode zone should be considered in the advanced ML-MFC for practically use in wastewater treatment process, and also for scale-up of MFCs. PMID:26972026

  9. Synthesis of iridescent Ni-containing anodic aluminum oxide films by anodization in oxalic acid

    Science.gov (United States)

    Xu, Qin; Ma, Hong-Mei; Zhang, Yan-Jun; Li, Ru-Song; Sun, Hui-Yuan

    2016-02-01

    Ni-containing anodic aluminum oxide films with highly saturated colors were synthesized using an ac electrodeposition method, and the optical and magnetic characteristics of the films were characterized. Precisely controllable color tuning could be obtained using wet-chemical etching to thin and widen the anodic aluminum oxide films pores isotropically before Ni deposition. Magnetic measurements indicate that such colored composite films not exhibit obvious easy magnetization direction. The resulted short (200 nm in length) and wide (50 nm in diameter) Ni nanowires present only fcc phase. The magnetization reversal mechanism is in good agreement with the symmetric fanning reversal mode which is discussed in detail. Such films may find applications in decoration, display and multifunctional anti-counterfeiting applications.

  10. Electrochemical modification process of anodic alumina membrane

    Institute of Scientific and Technical Information of China (English)

    YU Mei; LIU Jian-hua; LI Song-mei

    2006-01-01

    The modification procedure of anodic alumina membrane(AAM) was studied. The AAM structure after modification was characterized by nickel nanowires prepared in AAM. Scanning electron microscopy was used to characterize the topography and structure properties of the AAM and nickel nanowires. The transformation of the current during the voltage reduction was studied. The mechanism of current and structure change during modification was discussed. The results show that a root structure produces after the AAM modification. The length of the root structure depends on the velocity of the voltage reduction. Slow voltage reduction leads to a large length of the root structure,otherwise,a short length of the root structure. At the end of the modification,the barrier layer is thin enough to be passed by electrons. Hence,the direct electrodeposition of one-dimensional nanowires can be carried out on the AAM with barrier layer and aluminum matrix successfully without any other treatments.

  11. Bacterial adherence to anodized titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Peremarch, C Perez-Jorge; Tanoira, R Perez; Arenas, M A; Matykina, E; Conde, A; De Damborenea, J J; Gomez Barrena, E; Esteban, J, E-mail: cperemarch@fjd.es

    2010-11-01

    The aim of this study was to evaluate Staphylococcus sp adhesion to modified surfaces of anodized titanium alloy (Ti-6Al-4V). Surface modification involved generation of fluoride-containing titanium oxide nanotube films. Specimens of Ti-6Al-4V alloy 6-4 ELI-grade 23- meets the requirements of ASTM F136 2002A (AMS 2631B class A1) were anodized in a mixture of sulphuric/hydrofluoric acid at 20 V for 5 and 60 min to form a 100 nm-thick porous film of 20 nm pore diameter and 230 nm-thick nanotube films of 100 nm in diameter. The amount of fluorine in the oxide films was of 6% and of 4%, respectively. Collection strains and six clinical strains each of Staphylococcus aureus and Staphylococcus epidermidis were studied. The adherence study was performed using a previously published protocol by Kinnari et al. The experiments were performed in triplicates. As a result, lower adherence was detected for collection strains in modified materials than in unmodified controls. Differences between clinical strains were detected for both species (p<0.0001, Kruskal-Wallis test), although global data showed similar results to that of collection strains (p<0.0001, Kruskal-Wallis test). Adherence of bacteria to modified surfaces was decreased for both species. The results also reflect a difference in the adherence between S. aureus and S. epidermidis to the modified material. As a conclusion, not only we were able to confirm the decrease of adherence in the modified surface, but also the need to test multiple clinical strains to obtain more realistic microbiological results due to intraspecies differences.

  12. Decay of Polarized Delta

    OpenAIRE

    Ramachandran, G.; Venkataraya; Vidya, M. S.; Balasubramanyam, J.; Padmanabha, G.

    2009-01-01

    The resonance $\\Delta(1232)$ with spin-parity ${3 \\over 2}^+$, which contributes dominantly to the reactions like $\\gamma N \\to \\pi N$ and $NN \\to NN\\pi$ at intermediate energies, may be expected to be produced in characteristically different polarized spin states. As such an analysis of the decay of polarized delta is presented, which may be utilized to probe empirically the production mechanism. It is shown that measurements of the angular distributions of the pion and the polarization of t...

  13. High-capacity nanocarbon anodes for lithium-ion batteries

    International Nuclear Information System (INIS)

    Highlights: • The nanocarbon anodes in lithium-ion batteries deliver a high capacity of ∼1100 mA h g−1. • The nanocarbon anodes exhibit excellent cyclic stability. • A novel structure of carbon materials, hollow carbon nanoboxes, has potential application in lithium-ion batteries. - Abstract: High energy and power density of secondary cells like lithium-ion batteries become much more important in today’s society. However, lithium-ion battery anodes based on graphite material have theoretical capacity of 372 mA h g−1 and low charging-discharging rate. Here, we report that nanocarbons including mesoporous graphene (MPG), carbon tubular nanostructures (CTN), and hollow carbon nanoboxes (HCB) are good candidate for lithium-ion battery anodes. The nanocarbon anodes have high capacity of ∼1100, ∼600, and ∼500 mA h g−1 at 0.1 A g−1 for MPG, CTN, and HCB, respectively. The capacity of 181, 141, and 139 mA h g−1 at 4 A g−1 for MPG, CTN, and HCB anodes is retained. Besides, nanocarbon anodes show high cycling stability during 1000 cycles, indicating formation of a passivating layer—solid electrolyte interphase, which support long-term cycling. Nanocarbons, constructed with graphene layers which fulfill lithiation/delithiation process, high ratio of graphite edge structure, and high surface area which facilitates capacitive behavior, deliver high capacity and improved rate-capability

  14. Studies of a liquid anode for plutonium electrorefining

    International Nuclear Information System (INIS)

    They are developing a solvent anode as an alternate method for producing plutonium metal of high purity by an electrorefining process. The goals are to produce metal of 99.98% purity with an anode residue containing less than 2% of the plutonium in the feed material. If they are successful, they will design and demonstrate a system utilizing semi-continuous and remotely controlled operations. Establishing a solvent anode method should lead to improved yields and a substantial reduction in the amount of residues generated by the electrorefining process. The new method should be a viable pyrochemical technique for recovering both plutonium and uranium from spent reactor fuel. Initially, the anode consists of a tantalum rod immersed in a pool of liquid cadmium at 7400C. Impure plutonium or a solid anode residue is in contact with the cadmium. As current passes through the anode, plutonium in the cadmium is oxidized and transfers into the molten salt as tripositive plutonium. More plutonium dissolves into the cadmium and the oxidation continues. The tri-positive plutonium is carried through the salt to the cathode, where it is reduced to pure, liquid metal. This metal, which is heavier than the salt, drips from the cathode into an annulus between the anode and cathode compartments and forms a product ring

  15. Atmospheric pressure arc discharge with ablating graphite anode

    Energy Technology Data Exchange (ETDEWEB)

    Nemchinsky, V. A. [Keiser University, Fort Lauderdale Campus, FL, 33309, USA; Raitses, Y. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

    2015-05-18

    The anodic carbon arc discharge is used to produce carbon nanoparticles. Recent experiments with the carbon arc at atmospheric pressure helium demonstrated the enhanced ablation rate for narrow graphite anodes resulting in high deposition rates of carbonaceous products on the copper cathode (Fetterman et al 2008 Carbon 46 1322–6). The proposed model explains these results with interconnected steady-state models of the cathode and the anode processes. When considering cathode functioning, the model predicts circulation of the particles in the near-cathode region: evaporation of the cathode material, ionization of evaporated atoms and molecules in the near-cathode plasma, return of the resulting ions to the cathode, surface recombination of ions and electrons followed again by cathode evaporation etc. In the case of the low anode ablation rate, the ion acceleration in the cathode sheath provides the major cathode heating mechanism. In the case of an intensive anode ablation, an additional cathode heating is due to latent fusion heat of the atomic species evaporated from the anode and depositing at the cathode. Using the experimental arc voltage as the only input discharge parameter, the model allows us to calculate the anode ablation rate. A comparison of the results of calculations with the available experimental data shows reasonable agreement.

  16. Interconnected hollow carbon nanospheres for stable lithium metal anodes.

    Science.gov (United States)

    Zheng, Guangyuan; Lee, Seok Woo; Liang, Zheng; Lee, Hyun-Wook; Yan, Kai; Yao, Hongbin; Wang, Haotian; Li, Weiyang; Chu, Steven; Cui, Yi

    2014-08-01

    For future applications in portable electronics, electric vehicles and grid storage, batteries with higher energy storage density than existing lithium ion batteries need to be developed. Recent efforts in this direction have focused on high-capacity electrode materials such as lithium metal, silicon and tin as anodes, and sulphur and oxygen as cathodes. Lithium metal would be the optimal choice as an anode material, because it has the highest specific capacity (3,860 mAh g(-1)) and the lowest anode potential of all. However, the lithium anode forms dendritic and mossy metal deposits, leading to serious safety concerns and low Coulombic efficiency during charge/discharge cycles. Although advanced characterization techniques have helped shed light on the lithium growth process, effective strategies to improve lithium metal anode cycling remain elusive. Here, we show that coating the lithium metal anode with a monolayer of interconnected amorphous hollow carbon nanospheres helps isolate the lithium metal depositions and facilitates the formation of a stable solid electrolyte interphase. We show that lithium dendrites do not form up to a practical current density of 1 mA cm(-2). The Coulombic efficiency improves to ∼ 99% for more than 150 cycles. This is significantly better than the bare unmodified samples, which usually show rapid Coulombic efficiency decay in fewer than 100 cycles. Our results indicate that nanoscale interfacial engineering could be a promising strategy to tackle the intrinsic problems of lithium metal anodes. PMID:25064396

  17. Polarized negative ions

    Energy Technology Data Exchange (ETDEWEB)

    Haeberli, W.

    1981-04-01

    This paper presents a survey of methods, commonly in use or under development, to produce beams of polarized negative ions for injection into accelerators. A short summary recalls how the hyperfine interaction is used to obtain nuclear polarization in beams of atoms. Atomic-beam sources for light ions are discussed. If the best presently known techniques are incorporated in all stages of the source, polarized H/sup -/ and D/sup -/ beams in excess of 10 ..mu..A can probably be achieved. Production of polarized ions from fast (keV) beams of polarized atoms is treated separately for atoms in the H(25) excited state (Lamb-Shift source) and atoms in the H(1S) ground state. The negative ion beam from Lamb-Shift sources has reached a plateau just above 1 ..mu..A, but this beam current is adequate for many applications and the somewhat lower beam current is compensated by other desirable characteristics. Sources using fast polarized ground state atoms are in a stage of intense development. The next sections summarize production of polarized heavy ions by the atomic beam method, which is well established, and by optical pumping, which has recently been demonstrated to yield very large nuclear polarization. A short discussion of proposed ion sources for polarized /sup 3/He/sup -/ ions is followed by some concluding remarks.

  18. Polarized negative ions

    International Nuclear Information System (INIS)

    This paper presents a survey of methods, commonly in use or under development, to produce beams of polarized negative ions for injection into accelerators. A short summary recalls how the hyperfine interaction is used to obtain nuclear polarization in beams of atoms. Atomic-beam sources for light ions are discussed. If the best presently known techniques are incorporated in all stages of the source, polarized H- and D- beams in excess of 10 μA can probably be achieved. Production of polarized ions from fast (keV) beams of polarized atoms is treated separately for atoms in the H(25) excited state (Lamb-Shift source) and atoms in the H(1S) ground state. The negative ion beam from Lamb-Shift sources has reached a plateau just above 1 μA, but this beam current is adequate for many applications and the somewhat lower beam current is compensated by other desirable characteristics. Sources using fast polarized ground state atoms are in a stage of intense development. The next sections summarize production of polarized heavy ions by the atomic beam method, which is well established, and by optical pumping, which has recently been demonstrated to yield very large nuclear polarization. A short discussion of proposed ion sources for polarized 3He- ions is followed by some concluding remarks

  19. Effects Of Anodic Protection On SCC Behavior Of X80 Pipeline Steel In High-pH Carbonate-Bicarbonate Solution

    OpenAIRE

    Zhao W; Zou Y.; Xia D.X.; Zou Z.D.

    2015-01-01

    The potentiodynamic polarization test and slow strain rate tensile tests of X80 pipeline steel were performed in 0.5M Na2CO3-1M NaHCO3 solution to study the electrochemical and stress corrosion cracking properties. The results of potentiodynamic polarization test show that there is an obvious stable passive region, about from 0v to 0.8V (SCE), indicating that anodic protection is feasible. The results of slow strain rate tensile tests show that the stress corrosion cracking sensibility is hig...

  20. Transformation and removal of arsenic in groundwater by sequential anodic oxidation and electrocoagulation

    Science.gov (United States)

    Zhang, Peng; Tong, Man; Yuan, Songhu; Liao, Peng

    2014-08-01

    Oxidation of As(III) to As(V) is generally essential for the efficient remediation of As(III)-contaminated groundwater. The performance and mechanisms of As(III) oxidation by an as-synthesized active anode, SnO2 loaded onto Ti-based TiO2 nanotubes (Ti/TiO2NTs/Sb-SnO2), were investigated. The subsequent removal of total arsenic by electrocoagulation (EC) was further tested. The Ti/TiO2NTs/Sb-SnO2 anode showed a high and lasting electrochemical activity for As(III) oxidation. 6.67 μM As(III) in synthetic groundwater was completely oxidized to As(V) within 60 min at 50 mA. Direct electron transfer was mainly responsible at the current below 30 mA, while hydroxyl radicals contributed increasingly with the increase in the current above 30 mA. As(III) oxidation was moderately inhibited by the presence of bicarbonate (20 mM), while was dramatically increased with increasing the concentration of chloride (0-10 mM). After the complete oxidation of As(III) to As(V), total arsenic was efficiently removed by EC in the same reactor by reversing electrode polarity. The removal efficiency increased with increasing the current but decreased by the presence of phosphate and silica. Anodic oxidation represents an effective pretreatment approach to increasing EC removal of As(III) in groundwater under O2-limited conditions.

  1. Inert Anode Life in Low Temperature Reduction Process

    Energy Technology Data Exchange (ETDEWEB)

    Bradford, Donald R.

    2005-06-30

    The production of aluminum metal by low temperature electrolysis utilizing metal non-consumable anodes and ceramic cathodes was extensively investigated. Tests were performed with traditional sodium fluoride--aluminum fluoride composition electrolytes, potassium fluoride-- aluminum fluoride electrolytes, and potassium fluoride--sodium fluoride--aluminum fluoride electrolytes. All of the Essential First-Tier Requirements of the joint DOE-Aluminum Industry Inert Anode Road Map were achieved and those items yet to be resolved for commercialization of this technology were identified. Methods for the fabrication and welding of metal alloy anodes were developed and tested. The potential savings of energy and energy costs were determined and potential environmental benefits verified.

  2. Unstable behavior of anodic arc discharge for synthesis of nanomaterials

    Science.gov (United States)

    Gershman, Sophia; Raitses, Yevgeny

    2016-09-01

    A short carbon arc operating with a high ablation rate of the graphite anode exhibits a combined motion of the arc and the arc attachment to the anode. A characteristic time scale of this motion is in a 10‑3 s range. The arc exhibits a negative differential resistance before the arc motion occurs. Thermal processes in the arc plasma region interacting with the ablating anode are considered as possible causes of this unstable arc behavior. It is also hypothesized that the arc motion could potentially cause mixing of the various nanoparticles synthesized in the arc in the high ablation regime.

  3. Cu-Ni-Fe anodes having improved microstructure

    Science.gov (United States)

    Bergsma, S. Craig; Brown, Craig W.

    2004-04-20

    A method of producing aluminum in a low temperature electrolytic cell containing alumina dissolved in an electrolyte. The method comprises the steps of providing a molten electrolyte having alumina dissolved therein in an electrolytic cell containing the electrolyte. A non-consumable anode and cathode is disposed in the electrolyte, the anode comprised of Cu--Ni--Fe alloys having single metallurgical phase. Electric current is passed from the anode, through the electrolyte to the cathode thereby depositing aluminum on the cathode, and molten aluminum is collected from the cathode.

  4. Study on spinel-based inert anode for aluminium electrolysis

    Institute of Scientific and Technical Information of China (English)

    WANG; Zhao-wen; HU; Xian-wei; LUO; Tao; GAO; Bing-liang; SHI; Zhong-ning; QIU; Zhu-xian

    2005-01-01

    Hot press-sintering was adopted to fabricate inert cermets anodes based on the nickel aluminate and nickel ferrite for use in aluminum electrolysis research. The density of samples, fabricated by hot pressing, is close to the theoretic density. At 900℃, the electrical conductivity of the periments. Effect of anode current on nickel ferrite-based and the reason for it were studied. A theory is that a more uniform metal distribution by improving the hot pressing process gives increased corrosion resistance of the anode.

  5. Na-Ion Battery Anodes: Materials and Electrochemistry.

    Science.gov (United States)

    Luo, Wei; Shen, Fei; Bommier, Clement; Zhu, Hongli; Ji, Xiulei; Hu, Liangbing

    2016-02-16

    The intermittent nature of renewable energy sources, such as solar and wind, calls for sustainable electrical energy storage (EES) technologies for stationary applications. Li will be simply too rare for Li-ion batteries (LIBs) to be used for large-scale storage purposes. In contrast, Na-ion batteries (NIBs) are highly promising to meet the demand of grid-level storage because Na is truly earth abundant and ubiquitous around the globe. Furthermore, NIBs share a similar rocking-chair operation mechanism with LIBs, which potentially provides high reversibility and long cycling life. It would be most efficient to transfer knowledge learned on LIBs during the last three decades to the development of NIBs. Following this logic, rapid progress has been made in NIB cathode materials, where layered metal oxides and polyanionic compounds exhibit encouraging results. On the anode side, pure graphite as the standard anode for LIBs can only form NaC64 in NIBs if solvent co-intercalation does not occur due to the unfavorable thermodynamics. In fact, it was the utilization of a carbon anode in LIBs that enabled the commercial successes. Anodes of metal-ion batteries determine key characteristics, such as safety and cycling life; thus, it is indispensable to identify suitable anode materials for NIBs. In this Account, we review recent development on anode materials for NIBs. Due to the limited space, we will mainly discuss carbon-based and alloy-based anodes and highlight progress made in our groups in this field. We first present what is known about the failure mechanism of graphite anode in NIBs. We then go on to discuss studies on hard carbon anodes, alloy-type anodes, and organic anodes. Especially, the multiple functions of natural cellulose that is used as a low-cost carbon precursor for mass production and as a soft substrate for tin anodes are highlighted. The strategies of minimizing the surface area of carbon anodes for improving the first-cycle Coulombic efficiency are

  6. Na-Ion Battery Anodes: Materials and Electrochemistry.

    Science.gov (United States)

    Luo, Wei; Shen, Fei; Bommier, Clement; Zhu, Hongli; Ji, Xiulei; Hu, Liangbing

    2016-02-16

    The intermittent nature of renewable energy sources, such as solar and wind, calls for sustainable electrical energy storage (EES) technologies for stationary applications. Li will be simply too rare for Li-ion batteries (LIBs) to be used for large-scale storage purposes. In contrast, Na-ion batteries (NIBs) are highly promising to meet the demand of grid-level storage because Na is truly earth abundant and ubiquitous around the globe. Furthermore, NIBs share a similar rocking-chair operation mechanism with LIBs, which potentially provides high reversibility and long cycling life. It would be most efficient to transfer knowledge learned on LIBs during the last three decades to the development of NIBs. Following this logic, rapid progress has been made in NIB cathode materials, where layered metal oxides and polyanionic compounds exhibit encouraging results. On the anode side, pure graphite as the standard anode for LIBs can only form NaC64 in NIBs if solvent co-intercalation does not occur due to the unfavorable thermodynamics. In fact, it was the utilization of a carbon anode in LIBs that enabled the commercial successes. Anodes of metal-ion batteries determine key characteristics, such as safety and cycling life; thus, it is indispensable to identify suitable anode materials for NIBs. In this Account, we review recent development on anode materials for NIBs. Due to the limited space, we will mainly discuss carbon-based and alloy-based anodes and highlight progress made in our groups in this field. We first present what is known about the failure mechanism of graphite anode in NIBs. We then go on to discuss studies on hard carbon anodes, alloy-type anodes, and organic anodes. Especially, the multiple functions of natural cellulose that is used as a low-cost carbon precursor for mass production and as a soft substrate for tin anodes are highlighted. The strategies of minimizing the surface area of carbon anodes for improving the first-cycle Coulombic efficiency are

  7. The impact of the inclination of the anode bottom on anode gas covering in the Hall-Heroult cell

    Energy Technology Data Exchange (ETDEWEB)

    Poncsak, S.; Kiss, L.I.; Perron, A. [Quebec Univ., Chicoutimi, PQ (Canada). Dept. des Sciences Appliquees; Perron, S. [Alcan Arvida Research and Development Centre, Jonquiere, PQ (Canada)

    2006-07-01

    The electrical efficiency and the energy consumption of aluminium electrolysis cells is influenced by carbon dioxide bubbles generated at the anode-bath interface. Electrically isolating these carbon-dioxide bubbles increases the ohmic resistance and ultimately, the energy consumption of the aluminium reduction cell. This study examined the impact of the anode inclination and current density on gas coverings and bath velocity for both carbon dioxide-cryolite and air-water systems. A bubble layer simulator based on a Lagrangian description of the bubble layer was constructed to examine these effect. Since the rate of gas production is determined by the applied current density, anode covering can be decreased only by a faster evacuation of the gas from the inter-electrode space. The curvature of the anode bottom promotes the release of the bubbles thereby decreasing the mean value of the covering. New anodes have a square shape with a flat, horizontal bottom. Inhomogeneous current distribution results in non-uniform anode consumption and the corners become progressively rounded during electrolysis. The curvature increases the interelectrode distance around the corner. Results illustrating the effect of the anode curvature on gas covering were obtained through the use of the bubble layer simulator based on the Lagrangian description.14 refs., 2 tabs., 4 figs.

  8. Effect of the ethanol concentration in the anode on the direct ethanol fuel cell performance

    Energy Technology Data Exchange (ETDEWEB)

    Belchor, Pablo Martins; Loeser, Neiva; Forte, Maria Madalena de Camargo [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil); Carpenter, Deyse [Fundacao Universidade Regional de Blumenau (FURB), Blumenau, SC (Brazil)], Email: rafarstv@hotmail.com

    2010-07-01

    Changes in the climate, sources and development of renewable energy are issues that have gain greater importance, and fuel cells have been investigated as an alternative source to produce energy through electrochemical reactions. Among the fuel cells types the Proton Exchange Membrane (PEMFC), fed with pure hydrogen at the anode and oxygen at the cathode, seen be the more promising ones as an electrolyte for portable, mobile and stationary applications due to its low emissions, low operating temperature, high power density and quick configuration. To avoid inconvenience of storage and transportation of pure hydrogen a PEMFC fed with alcohols has been developed, named Direct Alcohol Fuel Cells (DAFC). One way to increase the performance of DAFC is added water in the alcohol inserted into the anode, because the water keeps the membrane hydrated. In this work, the performance of a DAFC was evaluated by following the loss in the polarization curve and cell power by varying the ethanol/water ratio. The aim of this study was determine the optimal water/ethanol ratio to be feed in a DEFC prototype mounted in the lab. By the results it was possible to point that the best concentration of ethanol aqueous solution for the DEFC tested was around 1 mol.L-1. (author)

  9. Pre-coating of LSCM perovskite with metal catalyst for scalable high performance anodes

    KAUST Repository

    Boulfrad, Samir

    2013-07-01

    In this work, a highly scalable technique is proposed as an alternative to the lab-scale impregnation method. LSCM-CGO powders were pre-coated with 5 wt% of Ni from nitrates. After appropriate mixing and adequate heat treatment, coated powders were then dispersed into organic based vehicles to form a screen-printable ink which was deposited and fired to form SOFC anode layers. Electrochemical tests show a considerable enhancement of the pre-coated anode performances under 50 ml/min wet H2 flow with polarization resistance decreased from about 0.60cm2 to 0.38 cm2 at 900 C and from 6.70 cm2 to 1.37 cm2 at 700 C. This is most likely due to the pre-coating process resulting in nano-scaled Ni particles with two typical sizes; from 50 to 200 nm and from 10 to 40 nm. Converging indications suggest that the latter type of particle comes from solid state solution of Ni in LSCM phase under oxidizing conditions and exsolution as nanoparticles under reducing atmospheres. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  10. RHIC Polarized proton operation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H.; Ahrens, L.; Alekseev, I.G.; Aschenauer, E.; Atoian, G.; Bai, M.; Bazilevsky, A.; Blaskiewicz, M.; Brennan, J.M.; Brown, K.A.; Bruno, D.; Connolly, R.; Dion, A.; D' Ottavio, T.; Drees, K.A.; Fischer, W.; Gardner, C.; Glenn, J.W.; Gu, X.; Harvey, M.; Hayes, T.; Hoff, L.; Hulsart, R.L.; Laster, J.; Liu, C.; Luo, Y.; MacKay, W.W.; Makdisi, Y.; Marr, G.J.; Marusic, A.; Meot, F.; Mernick, K.; Michnoff, R,; Minty, M.; Montag, C.; Morris, J.; Nemesure, S.; Poblaguev, A.; Ptitsyn, V.; Ranjibar, V.; Robert-Demolaize, G.; Roser, T.; J.; Severino, F.; Schmidke, B.; Schoefer, V.; Severino, F.; Smirnov, D.; Smith, K.; Steski, D.; Svirida, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J. Wang, G.; Wilinski, M.; Yip, K.; Zaltsman, A.; Zelenski, A.; Zeno, K.; Zhang, S.Y.

    2011-03-28

    The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP{sup 4}. A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the store to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above

  11. RHIC Polarized proton operation

    International Nuclear Information System (INIS)

    The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP4. A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the store to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above injection

  12. Optical appearance of AC anodized Al/TiO2 composite coatings

    DEFF Research Database (Denmark)

    Bordo, Kirill; Gudla, Visweswara Chakravarthy; Ambat, Rajan;

    2014-01-01

    AC anodization of Friction Stir Processed (FSP) surface composites of Al/TiO2 was systematically investigated with an aim to understand the effect of the anodization parameters on the optical appearance of the anodic layer. FSP-treated Al samples were anodized at different frequencies and voltage...

  13. Ohmic resistance affects microbial community and electrochemical kinetics in a multi-anode microbial electrochemical cell

    Science.gov (United States)

    Dhar, Bipro Ranjan; Ryu, Hodon; Santo Domingo, Jorge W.; Lee, Hyung-Sool

    2016-11-01

    Multi-anode microbial electrochemical cells (MxCs) are considered as one of the most promising configurations for scale-up of MxCs, but understanding of anode kinetics in multiple anodes is limited in the MxCs. In this study we assessed microbial community and electrochemical kinetic parameters for biofilms on individual anodes in a multi-anode MxC to better comprehend anode fundamentals. Microbial community analysis targeting 16S rRNA Illumina sequencing showed that Geobacter genus was abundant (87%) only on the biofilm anode closest to a reference electrode (low ohmic energy loss) in which current density was the highest among three anodes. In comparison, Geobacter populations were less than 1% for biofilms on other two anodes distant from the reference electrode (high ohmic energy loss), generating small current density. Half-saturation anode potential (EKA) was the lowest at -0.251 to -0.242 V (vs. standard hydrogen electrode) for the closest biofilm anode to the reference electrode, while EKA was as high as -0.134 V for the farthest anode. Our study proves that electric potential of individual anodes changed by ohmic energy loss shifts biofilm communities on individual anodes and consequently influences electron transfer kinetics on each anode in the multi-anode MxC.

  14. Our Polar Past

    Science.gov (United States)

    Clary, Renee; Wandersee, James

    2009-01-01

    The study of polar exploration is fascinating and offers students insights into the history, culture, and politics that affect the developing sciences at the farthest ends of Earth. Therefore, the authors think there is value in incorporating polar exploration accounts within modern science classrooms, and so they conducted research to test their…

  15. Polar Science Is Cool!

    Science.gov (United States)

    Weeks, Sophie

    2012-01-01

    Children are fascinated by the fact that polar scientists do research in extremely cold and dangerous places. In the Arctic they might be viewed as lunch by a polar bear. In the Antarctic, they could lose toes and fingers to frostbite and the wind is so fast it can rip skin off. They camp on ice in continuous daylight, weeks from any form of…

  16. Lambda polarization at HERMES

    Energy Technology Data Exchange (ETDEWEB)

    Belostotski, S. [Petersburg Nuclear Physics Institute RAS Gatchina, Leningrad district 188300 (Russian Federation); Naryshkin, Yu., E-mail: naryshk@mail.desy.d [Petersburg Nuclear Physics Institute RAS Gatchina, Leningrad district 188300 (Russian Federation); Veretennikov, D. [Petersburg Nuclear Physics Institute RAS Gatchina, Leningrad district 188300 (Russian Federation)

    2011-01-15

    Transverse polarization of {Lambda} and {Lambda}-bar hyperons produced inclusively in quasi-real photon-nucleon scattering has been studied for several nuclear targets in a wide range of atomic-mass numbers A. A strong A-dependence of the {Lambda} polarization is observed.

  17. Corrosion protection of AZ91 magnesium alloy by anodizing in niobium and zirconium-containing electrolytes

    International Nuclear Information System (INIS)

    A new Nb + Zr-based anodized coating was designed for the corrosion protection of AZ91 magnesium alloy. Polarization curves and electrochemical impedance diagrams plotted in Na2SO4 electrolyte showed its high protective effect. Analysis of the chemical composition by X-ray photoelectron spectroscopy indicated that the coating mainly consisted of (i) magnesium metaborate and metaphosphate, (ii) MgF2 and ZrF4, and (iii) Nb2O5, ZrO2 and MgO. A higher concentration of fluorine at both interfaces and an enrichment in Zr compared to Nb were revealed by SEM and EDS analyses. Thus, Zr-based compounds and MgF2 play a key role in the anti-corrosion ability of the coating.

  18. Microstructural degradation of Ni-YSZ anodes for solid oxide fuel cells

    DEFF Research Database (Denmark)

    Thydén, Karl Tor Sune

    2008-01-01

    are of technological relevance, it is difficult to identify the effect from isolated parameters such as temperature, fuel gas composition and polarization. Model studies of high temperature aged Ni-YSZ cermets are generally performed in atmospheres containing relatively low concentrations of H2O. In this work......, the microstructural degradation in both electrochemically longterm tested cells and high-temperature aged model materials are studied. Since Ni particle sintering / coarsening is attributed to be the major cause of anode degradation, this subject attains the primary focus. A large part of the work is focused......-reforming catalysis. In the context of electrochemically tested and technologically relevant cells, the majority of the microstructural work is performed on a cell tested at 850°C under relatively severe conditions for 17,500 hours. It is demonstrated that the major Ni rearrangements take place at the interface...

  19. The effect of antimony presence in anodic copper on kinetics and mechanism of anodic dissolution and cathodic deposition of copper

    Directory of Open Access Journals (Sweden)

    Stanković Z.D.

    2008-01-01

    Full Text Available The influence of the presence of Sb atoms, as foreign metal atoms in anode copper, on kinetics, and, on the mechanism of anodic dissolution and cathodic deposition of copper in acidic sulfate solution has been investigated. The galvanostatic single-pulse method has been used. Results indicate that presence of Sb atoms in anode copper increase the exchange current density as determined from the Tafel analysis of the electrode reaction. It is attributed to the increase of the crystal lattice parameter determined from XRD analysis of the electrode material.

  20. Anodic slimes formation in copper electrowinning

    Directory of Open Access Journals (Sweden)

    Ipinza, J.

    2004-02-01

    Full Text Available The slime formation in acidic electrolytes of copper with several metallic impurities has been studied. On Pb-Ca-Sn anode surface firstly the formation of PbSO4 takes place, then, it is transformed in PbO2, which covers the anode surface. It was experimentally established the formation of a manganese dioxide double layer at the anode. This layer was always composed of a thick external layer of non-adhering and easily removable scales, and of a thin internal layer, which adheres relatively well to the surface of the electrode. It was found that the manganese dioxide present in the slime is of different nature: a non-adhering layer produced by electrolysis (ε-MnO2 on the PbO2 surface and a pure chemical precipitate in the solution (β- MnO2. Lead sulfate was found on the β-MnO2layer when iron was in the electrolyte. When arsenic or antimony was present in the electrolyte, the slime was lead sulfate and amorphous compounds of those ions. Slime of Chilean electrowinning (EW plants is also discussed.

    Se estudió la formación de borras anódicas debido a la presencia de varias impurezas metálicas en electrólitos de cobre. Sobre la superficie de un ánodo de Pb-Ca-Sn se forma primero PbSO4 y luego se transforma en PbO2, el cual cubre la superficie del ánodo. Se estableció experimentalmente la formación de una doble capa de dióxido de manganeso en el ánodo. Esta estuvo siempre compuesta por una capa externa gruesa, no adherente y de fácil remoción, y otra interna delgada y adherida a la superficie del electrodo. Se encontró que los óxidos de manganeso en las borras eran de distinta naturaleza: una capa no adherente producida por electrólisis sobre la superficie de PbO2 (ε-MnO2 y una producida sólo por precipitación química en la solución (β-MnO2. A1 existir hierro en el electrólito se encontró sulfato de

  1. Determination of beam polarization from integrated Borrmann intensities

    International Nuclear Information System (INIS)

    The Borrmann effect can be used to determine the extent of beam polarization of any x-ray beam. The method is applicable, without any modification, to any diffractometer equipped with a partial or full Eulerian cradle. It consists of rocking a perfect crystal, in a thick crystal Laue transmission geometry, through the Bragg angle at various values of the azimuthal angle /sub chi/. If the thickness of the perfect crystal is such that μT/sub 0/>10, then it measures directly the polarization of the incident beam. Three different Ge perfect crystals were used to study the amount of polarization of x-rays produced by a MO and a W source, followed by a double crystal graphite monochromator. A 1800 periodicity in the integrated intensity, as a function of /sub chi/, is observed; the periodic extremes show the extent of beam polarization. Anomalously transmitted integrated intensity ratios between parallel (σ-component) and perpendicular (π-component) scanning directions, with respect to the scattering plane, are used to characterize the polarization since they are quite insensitive to beam divergences, whereas the corresponding peak height radius show very important beam divergence effects. Also, the polarization properties of graphite monochromators can be related to those of a perfect crystal if the (002) lattice planes are used for any excitation line of the W-anode. This is due to the polarization contribution of the intense white radiation spectrum superimposed on that of the line. On the other hand, the same spectrum impinging on the (004) lattice planes produce polarization properties closer to that of the ideally mosaic crystal

  2. Polarization Optics in Telecommunications

    CERN Document Server

    Damask, Jay N

    2005-01-01

    The strong investments into optical telecommunications in the late 1990s resulted in a wealth of new research, techniques, component designs, and understanding of polarization effects in fiber. Polarization Optics in Telecommunications brings together recent advances in the field to create a standard, practical reference for component designers and optical fiber communication engineers. Beginning with a sound foundation in electromagnetism, the author offers a dissertation of the spin-vector formalism of polarization and the interaction of light with media. Applications discussed include optical isolators, optical circulators, fiber collimators, and a variety of applied waveplate and prism combinations. Also included in an extended discussion of polarization-mode dispersion (PMD) and polarization-dependent loss (PDL), their representation, behavior, statistical properties, and measurement. This book draws extensively from the technical and patent literature and is an up-to-date reference for researchers and c...

  3. Parallel Polarization State Generation.

    Science.gov (United States)

    She, Alan; Capasso, Federico

    2016-01-01

    The control of polarization, an essential property of light, is of wide scientific and technological interest. The general problem of generating arbitrary time-varying states of polarization (SOP) has always been mathematically formulated by a series of linear transformations, i.e. a product of matrices, imposing a serial architecture. Here we show a parallel architecture described by a sum of matrices. The theory is experimentally demonstrated by modulating spatially-separated polarization components of a laser using a digital micromirror device that are subsequently beam combined. This method greatly expands the parameter space for engineering devices that control polarization. Consequently, performance characteristics, such as speed, stability, and spectral range, are entirely dictated by the technologies of optical intensity modulation, including absorption, reflection, emission, and scattering. This opens up important prospects for polarization state generation (PSG) with unique performance characteristics with applications in spectroscopic ellipsometry, spectropolarimetry, communications, imaging, and security. PMID:27184813

  4. Polarization Mode Dispersion

    CERN Document Server

    Galtarossa, Andrea

    2005-01-01

    This book contains a series of tutorial essays on polarization mode dispersion (PMD) by the leading experts in the field. It starts with an introductory review of the basic concepts and continues with more advanced topics, including a thorough review of PMD mitigation techniques. Topics covered include mathematical representation of PMD, how to properly model PMD in numerical simulations, how to accurately measure PMD and other related polarization effects, and how to infer fiber properties from polarization measurements. It includes discussions of other polarization effects such as polarization-dependent loss and the interaction of PMD with fiber nonlinearity. It additionally covers systems issues like the impact of PMD on wavelength division multiplexed systems. This book is intended for research scientists or engineers who wish to become familiar with PMD and its system impacts.

  5. Parallel Polarization State Generation

    CERN Document Server

    She, Alan

    2016-01-01

    The control of polarization, an essential property of light, is of wide scientific and technological interest. The general problem of generating arbitrary time-varying states of polarization (SOP) has always been mathematically formulated by a series of linear transformations, i.e. a product of matrices, imposing a serial architecture. Here we show a parallel architecture described by a sum of matrices. The theory is experimentally demonstrated by modulating spatially-separated polarization components of a laser using a digital micromirror device that are subsequently beam combined. This method greatly expands the parameter space for engineering devices that control polarization. Consequently, performance characteristics, such as speed, stability, and spectral range, are entirely dictated by the technologies of optical intensity modulation, including absorption, reflection, emission, and scattering. This opens up important prospects for polarization state generation (PSG) with unique performance characteristi...

  6. Parallel Polarization State Generation

    Science.gov (United States)

    She, Alan; Capasso, Federico

    2016-05-01

    The control of polarization, an essential property of light, is of wide scientific and technological interest. The general problem of generating arbitrary time-varying states of polarization (SOP) has always been mathematically formulated by a series of linear transformations, i.e. a product of matrices, imposing a serial architecture. Here we show a parallel architecture described by a sum of matrices. The theory is experimentally demonstrated by modulating spatially-separated polarization components of a laser using a digital micromirror device that are subsequently beam combined. This method greatly expands the parameter space for engineering devices that control polarization. Consequently, performance characteristics, such as speed, stability, and spectral range, are entirely dictated by the technologies of optical intensity modulation, including absorption, reflection, emission, and scattering. This opens up important prospects for polarization state generation (PSG) with unique performance characteristics with applications in spectroscopic ellipsometry, spectropolarimetry, communications, imaging, and security.

  7. The Evolution of Solid Oxide Fuel Cell Nickel-Yttria Stabilized Zirconia Anodes Studied Using Electrochemical and Three-Dimensional Microstructural Characterizations

    Science.gov (United States)

    Kennouche, David O.

    This thesis focuses on Solid Oxide Fuel Cells (SOFCs). The 21st century will see major changes in the way energy is produced, stored, and used around the world. SOFCs, which provide an efficient, scalable, and low-pollution alternative method for electricity generation, are expected to play an important role. SOFCs can also be operated in electrolysis mode for energy storage, important since health and economic reasons are causing a shift towards intermittent renewable energy resources. However, multiple limitations mainly linked to cost and durability have prevented the expansion of this technology to mass markets. This work focuses on the Nickel - Yttria Stabilized Zirconia (Ni-YSZ) anode that is widely used in SOFCs. Coarsening of Ni in the Ni-YSZ anode has been widely cited as a primary cause of long-term SOFC degradation. While there have been numerous studies of Ni coarsening reported, these have typically only tracked the evolution of Ni particle size, not the entire microstructure, and have typically not been correlated directly with electrochemical performance. In this thesis, the advanced tomography techniques Focused Ion Beam - Scanning Electron Microscopy (FIB-SEM) tomography and Trans- mission X-ray Microscopy (TXM) have been utilized to enable insight into the evolution of Ni-YSZ structure and how it relates to performance degradation. Extensive anode aging studies were done for relatively short times using temperatures higher than in normal SOFC operation in order to accelerate microstructural evolution. In addition the microstructure changes were correlated with changes in anode polarization resistance. While most of the measurements were done by comparing different anodes aged under different conditions, the first example of a "pseudo in situ" measurement where the same anode was 3D imaged repeatedly with intervening aging steps, was also demonstrated. A microstructural evolution model that focuses on the active three-phase boundary density was

  8. ANODE CATALYST MATERIALS FOR USE IN FUEL CELLS

    DEFF Research Database (Denmark)

    2002-01-01

    a substrate material selected from Ru and Os; the respective components being present within specific ranges, display improved properties for use inanodes for low-temperature fuel cell anodes for PENFC fuel cells and direct methanol fuel cells....

  9. Topics in Chemical Instrumentation: CII. Automated Anodic Stripping Voltammetry.

    Science.gov (United States)

    Stock, John T.; Ewing, Galen W., Ed.

    1980-01-01

    Presents details of anodic stripping analysis (ASV) in college chemistry laboratory experiments. Provides block diagrams of the analyzer system, circuitry and power supplies of the automated stripping analyzer, and instructions for implementing microcomputer control of the ASV. (CS)

  10. Blue fluorescent organic light emitting diodes with multilayered graphene anode

    International Nuclear Information System (INIS)

    As an innovative anode for organic light emitting devices (OLEDs), we have investigated graphene films. Graphene has importance due to its huge potential in flexible OLED applications. In this work, graphene films have been catalytically grown and transferred to the glass substrate for OLED fabrications. We have successfully fabricated 2 mm × 2 mm device area blue fluorescent OLEDs with graphene anodes which showed 2.1% of external quantum efficiency at 1000 cd/m2. This is the highest value reported among fluorescent OLEDs using graphene anodes. Oxygen plasma treatment on graphene has been found to improve hole injections in low voltage regime, which has been interpreted as oxygen plasma induced work function modification. However, plasma treatment also increases the sheet resistance of graphene, limiting the maximum luminance. In summary, our works demonstrate the practical possibility of graphene as an anode material for OLEDs and suggest a processing route which can be applied to various graphene related devices.

  11. Digital simulation of anodic stripping voltammetry from thin film electrodes

    International Nuclear Information System (INIS)

    The anodic stripping voltammetry (ASV) is routinely applied to control of Cu(II) in heavy water in the primary cooling loop of the Nuclear Power Reactor. The anodic stripping voltammetry (ASV) is a very well-known technique in electroanalytical chemistry. However, due to the complexity of the phenomena, it is practised with the fundamentals of empiric considerations. A geometric model for the anodic stripping voltammetry (ASV) from thin film electrodes which can be calculated by explicit digital simulation method is proposed as a possibility of solving the electrochemically reversible, cuasi-reversible and irreversible reactions under linear potential scan and multiple potential scans. (Until now the analytical mathematical method was applied to reversible reactions). All the results are compared with analytical solutions and experimental results and it permits to conclude that the anodic stripping voltammetry (ASV) can be studied with the simplicity and potentialities of explicit digital simulation methods. (M.E.L.)

  12. Formation of complex anodic films on porous alumina matrices

    Indian Academy of Sciences (India)

    Alexander Zahariev; Assen Girginov

    2003-04-01

    The kinetics of growth of complex anodic alumina films was investigated. These films were formed by filling porous oxide films (matrices) having deep pores. The porous films (matrices) were obtained voltastatically in (COOH)2 aqueous solution under various voltages. The filling was done by re-anodization in an electrolyte solution not dissolving the film. Data about the kinetics of re-anodization depending on the porosity of the matrices were obtained. On the other hand, the slopes of the kinetic curves during reanodization were calculated by two equations expressing the dependence of these slopes on the ionic current density. A discrepancy was ascertained between the values of the calculated slopes and those experimentally found. For this discrepancy a possible explanation is proposed, related to the temperature increase in the film, because of that the real current density significantly increases during re-anodization.

  13. Silicon Whisker and Carbon Nanofiber Composite Anode Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Physical Sciences Inc. (PSI) has successfully developed a silicon whisker and carbon nanofiber composite anode for lithium ion batteries on a Phase I program. PSI...

  14. Nanocomposite anode materials for sodium-ion batteries

    Science.gov (United States)

    Manthiram, Arumugam; Kim Il, Tae; Allcorn, Eric

    2016-06-14

    The disclosure relates to an anode material for a sodium-ion battery having the general formula AO.sub.x--C or AC.sub.x--C, where A is aluminum (Al), magnesium (Mg), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), zirconium (Zr), molybdenum (Mo), tungsten (W), niobium (Nb), tantalum (Ta), silicon (Si), or any combinations thereof. The anode material also contains an electrochemically active nanoparticles within the matrix. The nanoparticle may react with sodium ion (Na.sup.+) when placed in the anode of a sodium-ion battery. In more specific embodiments, the anode material may have the general formula M.sub.ySb-M'O.sub.x--C, Sb-MO.sub.x--C, M.sub.ySn-M'C.sub.x--C, or Sn-MC.sub.x--C. The disclosure also relates to rechargeable sodium-ion batteries containing these materials and methods of making these materials.

  15. A method to localize gamma-ray bursts using POLAR

    CERN Document Server

    Suarez-Garcia, E; Hajdas, W; Lamanna, G; Lechanoine-Leluc, C; Marcinkowski, R; Mtchedlishvili, A; Orsi, S; Pohl, M; Produit, N; Rapin, D; Rybka, D; Vialle, J -P; 10.1016/j.nima.2010.10.006

    2010-01-01

    The hard X-ray polarimeter POLAR aims to measure the linear polarization of the 50-500 keV photons arriving from the prompt emission of gamma-ray bursts (GRBs). The position in the sky of the detected GRBs is needed to determine their level of polarization. We present here a method by which, despite of the polarimeter incapability of taking images, GRBs can be roughly localized using POLAR alone. For this purpose scalers are attached to the output of the 25 multi-anode photomultipliers (MAPMs) that collect the light from the POLAR scintillator target. Each scaler measures how many GRB photons produce at least one energy deposition above 50 keV in the corresponding MAPM. Simulations show that the relative outputs of the 25 scalers depend on the GRB position. A database of very strong GRBs simulated at 10201 positions has been produced. When a GRB is detected, its location is calculated searching the minimum of the chi2 obtained in the comparison between the measured scaler pattern and the database. This GRB lo...

  16. Two-phase flow in anode flow field of a small direct methanol fuel cell in different gravities

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    An in-situ visualization of two-phase flow inside anode flow bed of a small liquid fed direct methanol fuel cells in normal and reduced gravity has been conducted in a drop tower.The anode flow bed con-sists of 11 parallel straight channels.The length,width and depth of single channel,which had rec-tangular cross section,are 48.0,2.5 and 2.0mm,respectively.The rib width was 2.0mm.The experi-mental results indicated that when the fuel cell orientation is vertical,two-phase flow pattern in anode channels can evolve from bubbly flow in normal gravity into slug flow in microgravity.The size of bub-bles in the reduced gravity is also bigger.In microgravity,the bubbles rising speed in vertical channels is obviously slower than that in normal gravity.When the fuel cell orientation is horizontal,the slug flow in the reduced gravity has almost the same characteristic with that in normal gravity.It implies that the effect of gravity on two-phase flow is small and the bubbles removal is governed by viscous drag.When the gas slugs or gas columns occupy channels,the performance of liquid fed direct methanol fuel cells is failing rapidly.It infers that in long-term microgravity,flow bed and operating condition should be optimized to avoid concentration polarization of fuel cells.

  17. Two-phase flow in anode flow field of a small direct methanol fuel cell in different gravities

    Institute of Scientific and Technical Information of China (English)

    GUO Hang; WU Feng; YE Fang; ZHAO JianFu; WAN ShiXin; L(U) CuiPing; MA ChongFang

    2009-01-01

    An in-situ visualization of two-phase flow inside anode flow bed of a small liquid fed direct methanol fuel cells in normal and reduced gravity has been conducted in a drop tower. The anode flow bed con-sists of 11 parallel straight channels. The length, width and depth of single channel, which had rec-tangular cross section, are 48.0, 2.5 and 2.0 mm, respectively. The rib width was 2.0 ram. The experi-mental results indicated that when the fuel cell orientation is vertical, two-phase flow pattern in anode channels can evolve from bubbly flow in normal gravity into slug flow in microgravity. The size of bub-bles in the reduced gravity is also bigger. In microgravity, the bubbles rising speed in vertical channels is obviously slower than that in normal gravity. When the fuel cell orientation is horizontal, the slug flow in the reduced gravity has almost the same characteristic with that in normal gravity. It implies that the effect of gravity on two-phase flow is small and the bubbles removal is governed by viscous drag. When the gas slugs or gas columns occupy channels, the performance of liquid fed direct methanol fuel cells is failing rapidly. It infers that in long-term microgravity, flow bed and operating condition should be optimized to avoid concentration polarization of fuel cells.

  18. Performance evaluation of a liquid tin anode solid oxide fuel cell operating under hydrogen, argon and coal

    Science.gov (United States)

    Khurana, Sanchit; LaBarbera, Mark; Fedkin, Mark V.; Lvov, Serguei N.; Abernathy, Harry; Gerdes, Kirk

    2015-01-01

    A liquid tin anode solid oxide fuel cell is constructed and investigated under different operating conditions. Electrochemical Impedance Spectroscopy (EIS) is used to reflect the effect of fuel feed as the EIS spectra changes significantly on switching the fuel from argon to hydrogen. A cathode symmetric cell is used to separate the impedance from the two electrodes, and the results indicate that a major contribution to the charge-transfer and mass-transfer impedance arises from the anode. The OCP of 0.841 V for the cell operating under argon as a metal-air battery indicates the formation of a SnO2 layer at the electrolyte/anode interface. The increase in the OCP to 1.1 V for the hydrogen fueled cell shows that H2 reduces the SnO2 film effectively. The effective diffusion coefficients are calculated using the Warburg element in the equivalent circuit model for the experimental EIS data, and the values of 1.9 10-3 cm2 s-1 at 700 °C, 2.3 10-3 cm2 s-1 at 800 °C and 3.5 10-3 cm2 s-1 at 900 °C indicate the system was influenced by diffusion of hydrogen in the system. Further, the performance degradation over time is attributed to the irreversible conversion of Sn to SnO2 resulting from galvanic polarization.

  19. Modified strontium titanates: From defect chemistry to SOFC anodes

    DEFF Research Database (Denmark)

    Verbraeken, M.C.; Ramos, Tania; Agersted, Karsten;

    2015-01-01

    Modified strontium titanates have received much attention recently for their potential as anode material in solid oxide fuel cells (SOFC). Their inherent redox stability and superior tolerance to sulphur poisoning and coking as compared to Ni based cermet anodes could improve durability of SOFC...... systems dramatically. Various substitution strategies can be deployed to optimise materials properties in these strontium titanates, such as electronic conductivity, electrocatalytic activity, chemical stability and sinterability, and thus mechanical strength. Substitution strategies not only cover choice...

  20. Metal-Supported SOFC with Ceramic-Based Anode

    DEFF Research Database (Denmark)

    Blennow Tullmar, Peter; Klemensø, Trine; Persson, Åsa Helen;

    2011-01-01

    Metal-supported solid oxide fuel cells have shown promise to offer several potential advantages over conventional anode (Ni-YSZ) supported cells, such as increased resistance against mechanical and thermal stresses and a reduction in materials cost. The purpose of this work is to illustrate how......), zirconia-free anode, in a planar metal-supported SOFC concept is discussed. ©2011 COPYRIGHT ECS - The Electrochemical Society...

  1. Note: Anodic bonding with cooling of heat-sensitive areas

    DEFF Research Database (Denmark)

    Vesborg, Peter Christian Kjærgaard; Olsen, Jakob Lind; Henriksen, Toke Riishøj;

    2010-01-01

    Anodic bonding of silicon to glass always involves heating the glass and device to high temperatures so that cations become mobile in the electric field. We present a simple way of bonding thin silicon samples to borosilicate glass by means of heating from the glass side while locally cooling heat......-sensitive areas from the silicon side. Despite the high thermal conductivity of silicon, this method allows a strong anodic bond to form just millimeters away from areas essentially at room temperature....

  2. Anodic Activation of Aluminum by Trace Element Tin

    OpenAIRE

    Tan, Juan

    2011-01-01

    Anodic activation of commercial and model aluminum alloys in chloride solution became of practical importance in connection with filiform corrosion of painted aluminum sheet in architectural application and aluminum components of brazed heat exchangers. Activation in chloride solution manifests itself in the form of a significant negative shift in the pitting potential relative to pure aluminum and a significant increase in the anodic current output at potentials where aluminum is normally ex...

  3. Mechanism for SOFC anode degradation from hydrogen sulfide exposure

    Energy Technology Data Exchange (ETDEWEB)

    Lussier, A.; Dvorak, J.; Idzerda, Y.U. [Department of Physics, Montana State University, EPS Building, Room 264, Bozeman, MT 59717 (United States); Sofie, S. [Department of Mechanical and Industrial Engineering, Montana State University, 201E Roberts Hall, Bozeman, MT 59717 (United States)

    2008-07-15

    Recent results on solid oxide fuel cells with Ni/YSZ and Ni/GDC anodes reveal a mechanism for permanent performance degradation due to hydrogen sulfide exposure. Our results confirm the temporary performance decline observed by others but also reveal a mechanism for the long term permanent degradation. We find that hydrogen sulfide leads to nickel migration and depletion in the anode, thereby compromising electrical conductivity and cell performance. (author)

  4. Formation and Morphology of Anodic Oxide Films of Ti

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The morphology and structure of the oxide films of Ti in H3PO4 were investigated by galvanostatic anodization, SEM and XRD. The oxide film grew from some pores in the grooves to layered microdomains as increasing anodizing voltage. The crystallinity of the oxide films decreased with the increase of the concentration of the electrolyte. The model has been proposed for the growth of the oxide films by two steps, i.e. by uniform thickening and by local deposition.

  5. The Temperature Stage Which Used At Anode Paste Doughing Process In Green Plant PT Inalum

    OpenAIRE

    Simatupang, Dian Christian

    2011-01-01

    Anode is raw material which used in electrolyse process aluminium smelting, where anode is form mixed of cokes and coal tar pitch, containing carbon element which required in smelting process of alumina to produce aluminium. PT INALUM has been able to produce anode it self, while cathode is still be imported from other countries. Aluminium smelter process which taking place continiously require many of anode, good quality and durable, especially temperature at doughing process of anode paste ...

  6. Stainless steel anodes for alkaline water electrolysis and methods of making

    Science.gov (United States)

    Soloveichik, Grigorii Lev

    2014-01-21

    The corrosion resistance of stainless steel anodes for use in alkaline water electrolysis was increased by immersion of the stainless steel anode into a caustic solution prior to electrolysis. Also disclosed herein are electrolyzers employing the so-treated stainless steel anodes. The pre-treatment process provides a stainless steel anode that has a higher corrosion resistance than an untreated stainless steel anode of the same composition.

  7. Preparation of Porous Alumina Film on Aluminum Substrate by Anodization in Oxalic Acid

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Self-ordering of the cell arrangement of the anodic porous alumina was prepared in oxalic acid solution at a constant potential of 40V and at a temperature of 20°C. The honeycomb structure made by one step anodization method and two step anodization method is different.Pores in the alumina film prepared by two step anodization method were more ordered than those by one step anodization method.

  8. Microbial community composition is unaffected by anode potential

    KAUST Repository

    Zhu, Xiuping

    2014-01-21

    There is great controversy on how different set anode potentials affect the performance of a bioelectrochemical system (BES). It is often reported that more positive potentials improve acclimation and performance of exoelectrogenic biofilms, and alter microbial community structure, while in other studies relatively more negative potentials were needed to achieve higher current densities. To address this issue, the biomass, electroactivity, and community structure of anodic biofilms were examined over a wide range of set anode potentials (-0.25, -0.09, 0.21, 0.51, and 0.81 V vs a standard hydrogen electrode, SHE) in single-chamber microbial electrolysis cells. Maximum currents produced using a wastewater inoculum increased with anode potentials in the range of -0.25 to 0.21 V, but decreased at 0.51 and 0.81 V. The maximum currents were positively correlated with increasing biofilm biomass. Pyrosequencing indicated biofilm communities were all similar and dominated by bacteria most similar to Geobacter sulfurreducens. Differences in anode performance with various set potentials suggest that the exoelectrogenic communities self-regulate their exocellular electron transfer pathways to adapt to different anode potentials. © 2013 American Chemical Society.

  9. Copper anode corrosion affects power generation in microbial fuel cells

    KAUST Repository

    Zhu, Xiuping

    2013-07-16

    Non-corrosive, carbon-based materials are usually used as anodes in microbial fuel cells (MFCs). In some cases, however, metals have been used that can corrode (e.g. copper) or that are corrosion resistant (e.g. stainless steel, SS). Corrosion could increase current through galvanic (abiotic) current production or by increasing exposed surface area, or decrease current due to generation of toxic products from corrosion. In order to directly examine the effects of using corrodible metal anodes, MFCs with Cu were compared with reactors using SS and carbon cloth anodes. MFCs with Cu anodes initially showed high current generation similar to abiotic controls, but subsequently they produced little power (2 mW m-2). Higher power was produced with microbes using SS (12 mW m-2) or carbon cloth (880 mW m-2) anodes, with no power generated by abiotic controls. These results demonstrate that copper is an unsuitable anode material, due to corrosion and likely copper toxicity to microorganisms. © 2013 Society of Chemical Industry.

  10. Formation of Anodic Aluminum Oxide with Branched and Meshed Pores.

    Science.gov (United States)

    Kim, Byeol; Lee, Jin Seok

    2016-06-01

    Anodic aluminum oxide (AAO), with a self-ordered hexagonal array, is important for various applications in nanofabrication including as the fabrication of nanotemplates and other nanostructures. With the consideration, there have been many efforts to control the characteristic parameters of porous anodic alumina by adjustment of the anodizing conditions such as the electrolyte, temperature, applied potential, and Al purity. In particular, impurities in Al are changing the morphology of an alumina film; however, the formation mechanism has not yet been explained. In this work, we anodized a high purity (99.999%, Al(high)) and low purity (99.8%, Al(low)) aluminum foil by a two-step anodization process in an oxalic acid solution or phosphoric acid. It was found that the purity of aluminum foil has influenced the morphology of the alumina film resulting in branched and meshed pores. Also, electrochemical analysis indicated that the branched and meshed pores in the low-purity Al foil formed by the presence of impurities. Impurities act as defects and change the general growth mechanism for pore formation by inducing an electric field imbalance during anodization. This work contributes to the research field of topographical chemistry and applied fields including nanofabrication. PMID:27427755

  11. Superhydrophobicity of Bionic Alumina Surfaces Fabricated by Hard Anodizing

    Institute of Scientific and Technical Information of China (English)

    Jing Li; Feng Du; Xianli Liu; Zhonghao Jiang; Luquan Ren

    2011-01-01

    Bionic alumina samples were fabricated on convex dome type aluminum alloy substrate using hard anodizing technique.The convex domes on the bionic sample were fabricated by compression molding under a compressive stress of 92.5 MPa.The water contact angles of the as-anodized bionic samples were measured using a contact angle meter (JC2000A) with the 3 μL water drop at room temperature.The measurement of the wetting property showed that the water contact angle of the unmodified as-anodized bionic alumina samples increases from 90° to 137° with the anodizing time.The increase in water contract angle with anodizing time arises from the gradual formation of hierarchical structure or composite structure.The structure is composed of the micro-scaled alumina columns and pores.The height of columns and the depth of pores depend on the anodizing time.The water contact angle increases significantly from 96° to 152° when the samples were modified with self-assembled monolayer of octadecanethiol (ODT),showing a change in the wettability from hydrophobicity to super-hydrophobicity.This improvement in the wetting property is attributed to the decrease in the surface energy caused by the chemical modification.

  12. Ceria-Based Anodes for Next Generation Solid Oxide Fuel Cells

    Science.gov (United States)

    Mirfakhraei, Behzad

    Mixed ionic and electronic conducting materials (MIECs) have been suggested to represent the next generation of solid oxide fuel cell (SOFC) anodes, primarily due to their significantly enhanced active surface area and their tolerance to fuel components. In this thesis, the main focus has been on determining and tuning the physicochemical and electrochemical properties of ceria-based MIECs in the versatile perovskite or fluorite crystal structures. In one direction, BaZr0.1Ce0.7Y0.1 M0.1O3-delta (M = Fe, Ni, Co and Yb) (BZCY-M) perovskites were synthesized using solid-state or wet citric acid combustion methods and the effect of various transition metal dopants on the sintering behavior, crystal structure, chemical stability under CO2 and H 2S, and electrical conductivity, was investigated. BZCY-Ni, synthesized using the wet combustion method, was the best performing anode, giving a polarization resistance (RP) of 0.4 O.cm2 at 800 °C. Scanning electron microscopy and X-ray diffraction analysis showed that this was due to the exsolution of catalytic Ni nanoparticles onto the oxide surface. Evolving from this promising result, the effect of Mo-doped CeO 2 (nCMO) or Ni nanoparticle infiltration into a porous Gd-doped CeO 2 (GDC) anode (in the fluorite structure) was studied. While 3 wt. % Ni infiltration lowered RP by up to 90 %, giving 0.09 O.cm2 at 800 °C and exhibiting a ca. 5 times higher tolerance towards 10 ppm H2, nCMO infiltration enhanced the H2 stability by ca. 3 times, but had no influence on RP. In parallel work, a first-time study of the Ce3+ and Ce 4+ redox process (pseudocapacitance) within GDC anode materials was carried out using cyclic voltammetry (CV) in wet H2 at high temperatures. It was concluded that, at 500-600 °C, the Ce3+/Ce 4+ reaction is diffusion controlled, probably due to O2- transport limitations in the outer 5-10 layers of the GDC particles, giving a very high capacitance of ca. 70 F/g. Increasing the temperature ultimately

  13. Anode Supported Solid Oxide Fuel Cells - Deconvolution of Degradation into Cathode and Anode Contributions

    DEFF Research Database (Denmark)

    Hagen, Anke; Liu, Yi-Lin; Barfod, Rasmus;

    2007-01-01

    of the cathode were strongly dependent on the pO(2); they were significantly smaller when testing in oxygen compared to air. Microstructural analysis of the cathode/electrolyte interface of a not-tested reference cell carried out after removal of the cathode showed sharp craters on the electrolyte surface where...... the LSM particles had been located. After testing in air, these craters flattened out and decreased in size, indicating the decrease of three phase boundary length. In contrast, they remained almost unchanged after testing in oxygen giving an explanation for the observed smaller - mainly anode related...

  14. Optimal Conditions for Fast Charging and Long Cycling Stability of Silicon Microwire Anodes for Lithium Ion Batteries, and Comparison with the Performance of Other Si Anode Concepts

    Directory of Open Access Journals (Sweden)

    Enrique Quiroga-González

    2013-10-01

    Full Text Available Cycling tests under various conditions have been performed for lithium ion battery anodes made from free-standing silicon microwires embedded at one end in a copper current collector. Optimum charging/discharging conditions have been found for which the anode shows negligible fading (< 0.001% over 80 cycles; an outstanding result for this kind of anodes. Several performance parameters of the anode have been compared to the ones of other Si anode concepts, showing that especially the capacity as well as the rates of charge flow per nominal area of anode are the highest for the present anode. With regard to applications, the specific parameters per area are more important than the specific gravimetric parameters like the gravimetric capacity, which is good for comparing the capacity between materials but not enough for comparing between anodes.

  15. Porous Anodic Aluminum Oxide with Serrated Nanochannels

    Science.gov (United States)

    Li, Dongdong; Zhao, Liang; Lu, Jia G.

    2010-03-01

    Self-assembled nanoporous anodic aluminum oxide (AAO) membrane with straight channels has long been an important tool in synthesizing highly ordered and vertically aligned quasi-1D nanostructures for various applications. Recently shape-selective nanomaterials have been achieved using AAO as a template. It is envisioned that nanowires with multi-branches will significantly increase the active functional sites for applications as sensors, catalysts, chemical cells, etc. Here AAO membranes with serrated nanochannels have been successfully fabricated via a two-step annodization method. The serrated channels with periodic intervals are aligned at an angle of ˜25^circ along the stem channels. The formation of the serrated channels is attributed to the evolution of oxygen gas bubbles and the resulted plastic deformation in oxide membrane. In order to reveal the inside channel structure, Platinum are electrodeposited into the AAO template. The as-synthesized serrated Pt nanowires demonstrate a superior electrocatalytic activity. This is attributed to the enhanced electric field strength around serrated tips as shown in the electric field simulation by COMOSL. Moreover, hierarchical serrated/straight hybrid structures can be constructed using this simple and novel self assembly technique.

  16. Review of Polarized Ion Sources

    Science.gov (United States)

    Zelenski, A.

    2016-02-01

    Recent progress in polarized ion sources development is reviewed. New techniques for production of polarized H‑ ion (proton), D‑ (D+) and 3He++ ion beams will be discussed. A novel polarization technique was successfully implemented for the upgrade of the RHIC polarized H‑ ion source to higher intensity and polarization. In this technique, a proton beam inside the high magnetic field solenoid is produced by ionization of the atomic hydrogen beam (from an external source) in the He-gas ionizer cell. Polarized electron capture from the optically-pumped Rb vapor further produces proton polarization (Optically Pumped Polarized Ion Source technique). The upgraded source reliably delivered beam for the 2013 polarized run in RHIC at S = 510 GeV. This was a major factor contributing to RHIC polarization increase to over 60 % for colliding beams. Feasibility studies of a new polarization technique for polarized 3He++ source based on BNL Electron Beam Ion Source is also discussed.

  17. The behaviour of amalgams of some d-metals during cathodic polarization in solutions

    International Nuclear Information System (INIS)

    Results of electrochemical investigation of rhenium, molybdenum and tungsten amalgams during cathodic polarization in alkali and acid solutions are presented. A variant of electrolysis with sodium amalgam as anode is used for the investigation. On the basis of experimental data on potentials of amalgam cathodes (under current and after switching off one), as well as redox-potentials of solutions near the cathode surface, formation of negative ions of metals (rhenium, molybdenum and tungsten) is established

  18. Effect of ionic conductivity of zirconia electrolytes on polarization properties of various electrodes in SOFC

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Masahiro; Uchida, Hiroyuki; Yoshida, Manabu [Yamanashi Univ., Kofu (Japan)

    1996-12-31

    Solid oxide fuel cells (SOFCs) have been intensively investigated because, in principle, their energy conversion efficiency is fairly high. Lowering the operating temperature of SOFCs from 1000{degrees}C to around 800{degrees}C is desirable for reducing serious problems such as physical and chemical degradation of the constructing materials. The object of a series of the studies is to find a clue for achieving higher electrode performances at a low operating temperature than those of the present level. Although the polarization loss at electrodes can be reduced by using mixed-conducting ceria electrolytes, or introducing the mixed-conducting (reduced zirconia or ceria) laver on the conventional zirconia electrolyte surface, no reports are available on the effect of such an ionic conductivity of electrolytes on electrode polarizations. High ionic conductivity of the electrolyte, of course, reduces the ohmic loss. However, we have found that the IR-free polarization of a platinum anode attached to zirconia electrolytes is greatly influenced by the ionic conductivity, {sigma}{sub ion}, of the electrolytes used. The higher the {sigma}{sub ion}, the higher the exchange current density, j{sub 0}, for the Pt anode in H{sub 2} at 800 {approximately} 1000{degrees}C. It was indicated that the H{sub 2} oxidation reaction rate was controlled by the supply rate of oxide ions through the Pt/zirconia interface which is proportional to the {sigma}{sub ion}. Recently, we have proposed a new concept of the catalyzed-reaction layers which realizes both high-performances of anodes and cathodes for medium-temperature operating SOFCs. We present the interesting dependence of the polarization properties of various electrodes (the SDC anodes with and without Ru microcatalysts, Pt cathode, La(Sr)MnO{sub 3} cathodes with and without Pt microcatalysts) on the {sigma}{sub ion} of various zirconia electrolytes at 800 {approximately} 1000{degrees}C.

  19. GUIDE FOR POLARIZED NEUTRONS

    Science.gov (United States)

    Sailor, V.L.; Aichroth, R.W.

    1962-12-01

    The plane of polarization of a beam of polarized neutrons is changed by this invention, and the plane can be flipped back and forth quicitly in two directions in a trouble-free manner. The invention comprises a guide having a plurality of oppositely directed magnets forming a gap for the neutron beam and the gaps are spaced longitudinally in a spiral along the beam at small stepped angles. When it is desired to flip the plane of polarization the magnets are suitably rotated to change the direction of the spiral of the gaps. (AEC)

  20. Kinetics of enhanced adsorption by polarization for organic pollutants on activated carbon fiber

    Institute of Scientific and Technical Information of China (English)

    HAN Yanhe; QUAN Xie; ZHAO Huimin; CHEN Shuo; ZHAO Yazhi

    2007-01-01

    The adsorption kinetics for model pollutants on activated carbon fiber(ACF)by polarization was investigated in this work.Kinetics data obtained for the adsorption of these model pollutants at open-circuit.400 mV,and -400 mV polarization were applied to the Lagergren equation,and adsorption rate constants(Ka)were determined.With the anodic polarization of 400 mV,the capacity of sodium phenoxide was increased from 0.0083 mmol/g at open circuit to 0.18 mmol/g,and a 17-fold enhancement was achieved;however,the capacity of p-nitrophenol was decreased from 2.93 mmol/g at open-circuit to 2.65 mmol/g.With the cathodal polarization of -400 mV,the capacity of aniline was improved from 3.60 mmol/g at open-circuit to 3.88 mmol/g;however,the capacity of sodium dodecylben zene sulfonate was reduced from 2.20 mmol/g at open-circuit to 1.59 mmol/g.The enhancement for electrosorption changed with different groups substituting.Anodic polarization enhances the adsorption of benzene with the electron donating group.But whether anodic or not,cathodal polarization had less effect on the adsorption of electron-accepting aromatic compounds,and decreased the adsorption capacity of benzene-bearing donor-conjugate bridge-acceptor,while increasing its adsorption rate.Electrostatic interaction played a very important role in the electrosorption of ion-pollutants.

  1. Polarized atomic beams for targets

    International Nuclear Information System (INIS)

    The basic principle of the production of polarized atomic hydrogen and deuterium beams are reviewed. The status of the present available polarization, density and intensity are presented. The improvement of atomic beam density by cooling the hydrogen atoms to low velocity is discussed. The possible use of polarized atomic beams as targets in storage rings is shown. It is proposed that polarized atomic beams can be used to produce polarized gas targets with high polarization and greatly improved density

  2. Ni/YSZ pattern anodes fabrication and their microstructure and electrochemical behavior changes in H2-H2O environments

    Science.gov (United States)

    Yao, W.; Croiset, E.

    2013-03-01

    An effective photolithographic process was investigated to fabricate Ni/YSZ pattern anodes using a bi-layer lift-off resist method. Suitable undercut size was found critical for successful pattern fabrication. Effects of Ni thickness, temperature and H2O content on Ni pattern microstructure were evaluated. Ni/YSZ pattern anodes with 0.5 μm thick Ni was tested in dry H2 at 550 °C without significantly changing the TPB line. Ni/YSZ pattern anodes with Ni thickness of 0.8 μm were tested at 550 °C under dry and humidified H2 (3-50% H2O) conditions without TPB line change. At 700 °C, and for 0.8 μm thick patterns, the TPB length showed pronounced change in H2 with 10-50% H2O. Significant increase in TPB length due to holes formation was observed at 800 °C with 3% and 10% H2O. Ni/YSZ pattern anodes with 1.0 μm thick Ni was stable in H2 with 3% H2O in the range 550-800 °C, with TPB line only slightly modified. However, distinct change of TPB line and Ni microstructure was observed with 10-70% H2O above 700 °C. Stabilization of the polarization resistance depends on temperature. To accelerate stabilization of the cell, pre-treatment of the cell in H2 with 3% H2O at 750 °C or 800 °C could be performed.

  3. Formation of Nanoporous Anodic Alumina by Anodization of Aluminum Films on Glass Substrates.

    Science.gov (United States)

    Lebyedyeva, Tetyana; Kryvyi, Serhii; Lytvyn, Petro; Skoryk, Mykola; Shpylovyy, Pavlo

    2016-12-01

    Our research was aimed at the study of aluminum films and porous anodic alumina (PAA) films in thin-film РАА/Al structures for optical sensors, based on metal-clad waveguides (MCWG). The results of the scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies of the structure of Al films, deposited by DC magnetron sputtering, and of PAA films, formed on them, are presented in this work.The study showed that the structure of the Al films is defined by the deposition rate of aluminum and the thickness of the film. We saw that under anodization in 0.3 M aqueous oxalic acid solution at a voltage of 40 V, the PAA film with a disordered array of pores was formed on aluminum films 200-600 nm thick, which were deposited on glass substrates with an ultra-thin adhesive Nb layer. The research revealed the formation of two differently sized types of pores. The first type of pores is formed on the grain boundaries of aluminum film, and the pores are directed perpendicularly to the surface of aluminum. The second type of pores is formed directly on the grains of aluminum. They are directed perpendicularly to the grain plains. There is a clear tendency to self-ordering in this type of pores. PMID:27083584

  4. Dynamic nuclear spin polarization

    Energy Technology Data Exchange (ETDEWEB)

    Stuhrmann, H.B. [GKSS-Forschungszentrum Geesthacht GmbH (Germany)

    1996-11-01

    Polarized neutron scattering from dynamic polarized targets has been applied to various hydrogenous materials at different laboratories. In situ structures of macromolecular components have been determined by nuclear spin contrast variation with an unprecedented precision. The experiments of selective nuclear spin depolarisation not only opened a new dimension to structural studies but also revealed phenomena related to propagation of nuclear spin polarization and the interplay of nuclear polarisation with the electronic spin system. The observation of electron spin label dependent nuclear spin polarisation domains by NMR and polarized neutron scattering opens a way to generalize the method of nuclear spin contrast variation and most importantly it avoids precontrasting by specific deuteration. It also likely might tell us more about the mechanism of dynamic nuclear spin polarisation. (author) 4 figs., refs.

  5. Polarization Dependence of Emissivity

    OpenAIRE

    J, David; Strozzi,, A.G.; McDonald, Kirk T.

    2000-01-01

    We deduce the emissivity of radiation from a metallic surface as a function of angle and polarization. This effect has found application in the calibration of detectors for cosmic microwave background radiation.

  6. Time Domain Induced Polarization

    DEFF Research Database (Denmark)

    Fiandaca, Gianluca; Auken, Esben; Christiansen, Anders Vest;

    2012-01-01

    of time-domaininduced polarization for wider purposes. For these reasons, a new forward code and inversion algorithm have been developed using the full-time decay of the induced polarization response, together with an accurate description of the transmitter waveform and of the receiver transfer function...... laterally constrained inversion algorithm that extracts the spectral content of the induced polarization phenomenon in terms of the Cole- Cole parameters. Synthetic examples and field examples from Denmark showed a significant improvement in the resolution of the parameters that control the induced...... polarization response when compared to traditional integral chargeability inversion. The quality of the inversion results has been assessed by a complete uncertainty analysis of the model parameters; furthermore, borehole information confirm the outcomes of the field interpretations. With this new accurate...

  7. Polar-bulge galaxies

    CERN Document Server

    Reshetnikov, V P; Mosenkov, A V; Sotnikova, N Ya; Bizyaev, D V

    2015-01-01

    Based on SDSS data, we have selected a sample of nine edge-on spiral galaxies with bulges whose major axes show a high inclination to the disk plane. Such objects are called polar-bulge galaxies. They are similar in their morphology to polar-ring galaxies, but the central objects in them have small size and low luminosity. We have performed a photometric analysis of the galaxies in the g and r bands and determined the main characteristics of their bulges and disks. We show that the disks of such galaxies are typical for the disks of spiral galaxies of late morphological types. The integrated characteristics of their bulges are similar to the parameters of normal bulges. The stellar disks of polar-bulge galaxies often show large-scale warps, which can be explained by their interaction with neighboring galaxies or external accretion from outside.

  8. EDITORIAL: Polarization Optics

    Science.gov (United States)

    Turunen, Jari; Friesem, Asher A.; Friberg, Ari T.

    2004-03-01

    This special issue on Polarization Optics contains one review article and 23 research papers, many of which are based on presentations at the International Commission for Optics Topical Meeting on Polarization Optics, held in Polvijärvi, Finland, between 30 June and 3 July 2003. While this issue should not in any sense be considered as a `proceedings' of this meeting, the possibility of submitting papers to it was widely advertised during the meeting, which was attended by a large fraction of prominent scientists in the field of polarization optics. Thus the quality of papers in this special issue is high. In announcing both the meeting and this special issue, we emphasized that the concept of `polarization optics' should be understood in a wide sense. In fact, all contributions dealing with the vectorial nature of light were welcome. As a result, the papers included here cover a wide range of different aspects of linear and nonlinear polarization optics. Both theoretical and experimental features are discussed. We are pleased to see that the conference and this special issue both reflect the wide diversity of important and novel polarization phenomena in optics. The papers in this special issue, and other recently published works, demonstrate that even though polarization is a fundamental property of electromagnetic fields, interest in it is rapidly increasing. The fundamental relations between partial coherence and partial polarization are currently under vigorous research in electromagnetic coherence theory. In diffractive optics it has been found that the exploitation of the vectorial nature of light can be of great benefit. Fabrication of sophisticated, spatially variable polarization-control elements is becoming possible with the aid of nanolithography. Polarization singularities and the interplay of bulk properties and topology in nanoscale systems have created much enthusiasm. In nonlinear optics, the second harmonic waves generated on reflection and

  9. No More Polarization, Please!

    OpenAIRE

    Reinholt, Mia

    2006-01-01

    The organizational science literature on motivation has for long been polarized into two main positions; the organizational economic position focusing on extrinsic motivation and the organizational behavior position emphasizing intrinsic motivation. With the rise of the knowledge economy and the increasing levels of complexities it entails, such polarization is not fruitful in the attempt to explain motivation of organizational members. This paper claims that a more nuanced perspective on mot...

  10. Polarized protons and RHIC

    International Nuclear Information System (INIS)

    RHIC, the heavy ion collider being built at Brookhaven, offers an exciting opportunity to collide highly polarized protons at high energy and luminosity. This new facility would combine the existing AGS polarized proton capability with the new Booster/Accumulator and spin rotators to achieve collisions between intense beams of polarized protons at a collision energy of 500 GeV. At this energy and the expected luminosity of 2 x 1032 cm2/second physics probes will include high PT jets, direct photons, Drell-Yan, W±, and heavy quarks. The accessible physics includes study of the spin content of the proton, particularly gluon and antiquark polarization, study of large PQCD-predicted asymmetries for parton-parton subprocesses, and parity violation studies and searches. The proton spin direction at a RHIC crossing can be longitudinal or transverse and can alternate bunch-to-bunch giving exquisite control of systematic errors. At RHIC double spin experiments can be done with pure beams and the energy and luminosity open a new domain for probing the physics of spin. An international collaboration is forming which proposes to exploit the unique physics available from a polarized RHIC. Important steps, leading to a polarized RHIC, have been taken. The AGS has already accelerated polarized protons. A new Booster/Accumulator has been commissioned. A beautiful series of machine experiments at Indian University have verified that spin rotators indeed remove spin resonance behavior, which is the key to achieving polarized proton acceleration to high energy. E880, an accelerator experiment which will build, install, and test a Siberian Snake in the AGS, was approved by the Brookhaven PAC in August 1991. The snake will be installed in the AGS in the summer of 1993. RHIC construction has started, with heavy ion experiments to begin in 1997

  11. Polar Warming Drivers

    Science.gov (United States)

    McDunn, T. L.; Bougher, S. W.; Mischna, M. A.; Murphy, J. R.

    2012-12-01

    Polar warming is a dynamically induced temperature enhancement over mid-to-high latitudes that results in a reversed (poleward) meridional temperature gradient. This phenomenon was recently characterized over the 40-90 km altitude region [1] based on nearly three martian years of Mars Climate Sounder observations [2, 3]. Here we investigate which forcing mechanisms affect the magnitude and distribution of the observed polar warming by conducting simulations with the Mars Weather Research and Forecasting General Circulation Model [4, 5]. We present simulations confirming the influence topography [6] and dust loading [e.g., 7] have upon polar warming. We then present simulations illustrating the modulating influence gravity wave momentum deposition exerts upon polar warming, consistent with previous modeling studies [e.g., 8]. The results of this investigation suggest the magnitude and distribution of polar warming in the martian middle atmosphere is modified by gravity wave activity and that the characteristics of the gravity waves that most significantly affect polar warming vary with season. References: [1] McDunn, et al., 2012 (JGR), [2]Kleinböhl, et al., 2009 (JGR), [3] Kleinböhl, et al., 2011 (JQSRT), [4] Richardson, et al., 2007 (JGR), [5] Mischna, et al., 2011 (Planet. Space Sci.), [6] Richardson and Wilson, 2002 (Nature), [7] Haberle, et al., 1982 (Icarus), [8] Barnes, 1990 (JGR).

  12. In situ characterization of nanoscale catalysts during anodic redox processes

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Renu [National Institute of Standards and Technology; Crozier, Peter [Arizona State University; Adams, James [Arizona State University

    2013-09-19

    Controlling the structure and composition of the anode is critical to achieving high efficiency and good long-term performance. In addition to being a mixed electronic and ionic conductor, the ideal anode material should act as an efficient catalyst for oxidizing hydrogen, carbon monoxide and dry hydrocarbons without de-activating through either sintering or coking. It is also important to develop novel anode materials that can operate at lower temperatures to reduce costs and minimized materials failure associated with high temperature cycling. We proposed to synthesize and characterize novel anode cermets materials based on ceria doped with Pr and/or Gd together with either a Ni or Cu metallic components. Ceria is a good oxidation catalyst and is an ionic conductor at room temperature. Doping it with trivalent rare earths such as Pr or Gd retards sintering and makes it a mixed ion conductor (ionic and electronic). We have developed a fundamental scientific understanding of the behavior of the cermet material under reaction conditions by following the catalytic oxidation process at the atomic scale using a powerful Environmental Scanning Transmission Electron Microscope (ESTEM). The ESTEM allowed in situ monitoring of structural, chemical and morphological changes occurring at the cermet under conditions approximating that of typical fuel-cell operation. Density functional calculations were employed to determine the underlying mechanisms and reaction pathways during anode oxidation reactions. The dynamic behavior of nanoscale catalytic oxidation of hydrogen and methane were used to determine: ? Fundamental processes during anodic reactions in hydrogen and carbonaceous atmospheres ? Interfacial effects between metal particles and doped ceria ? Kinetics of redox reaction in the anode material

  13. Conductive Polymeric Binder for Lithium-Ion Battery Anode

    Science.gov (United States)

    Gao, Tianxiang

    Tin (Sn) has a high-specific capacity (993 mAhg-1) as an anode material for Li-ion batteries. To overcome the poor cycling performance issue caused by its large volume expansion and pulverization during the charging and discharging process, many researchers put efforts into it. Most of the strategies are through nanostructured material design and introducing conductive polymer binders that serve as matrix of the active material in anode. This thesis aims for developing a novel method for preparing the anode to improve the capacity retention rate. This would require the anode to have high electrical conductivity, high ionic conductivity, and good mechanical properties, especially elasticity. Here the incorporation of a conducting polymer and a conductive hydrogel in Sn-based anodes using a one-step electrochemical deposition via a 3-electrode cell method is reported: the Sn particles and conductive component can be electrochemically synthesized and simultaneously deposited into a hybrid thin film onto the working electrode directly forming the anode. A well-defined three dimensional network structure consisting of Sn nanoparticles coated by conducting polymers is achieved. Such a conductive polymer-hydrogel network has multiple advantageous features: meshporous polymeric structure can offer the pathway for lithium ion transfer between the anode and electrolyte; the continuous electrically conductive polypyrrole network, with the electrostatic interaction with elastic, porous hydrogel, poly (2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylonitrile) (PAMPS) as both the crosslinker and doping anion for polypyrrole (PPy) can decrease the volume expansion by creating porous scaffold and softening the system itself. Furthermore, by increasing the amount of PAMPS and creating an interval can improve the cycling performance, resulting in improved capacity retention about 80% after 20 cycles, compared with only 54% of that of the control sample without PAMPS. The cycle

  14. Corrosion Behaviour of Titanium Anodized Film in Different Corrosive Environments

    Directory of Open Access Journals (Sweden)

    Mr. Sunil D. Kahar

    2014-07-01

    Full Text Available Anodizing is an electrochemical process in which thickness of the natural oxide layer is increased and converted it into a decorative, durable, corrosion-resistant film. Titanium is used as a biocompatible material in human implants due to its excellent corrosion and wears resistance. Stable, continuous, highly adherent, and protective oxide films can be developed on titanium using various acid or alkaline baths. Anodizing of titanium generates a spectrum of different color without use of dyes. This spectrum of color dependent on the thickness of the oxide, voltage ranges, interference of light reflecting off the oxide surface and reflecting off the underlying metal surface. The anodized film of Titanium is mainly consists of TiO2 or mixtures of TiO2 & Ti2O3 etc. In the present work, Pure Titanium plate has been anodized using bath of Chromic Acid at different voltage range. The anodized film is characterized by visual observation, SEM & EDAX analysis & A.C Impedance Spectroscopy, while the corrosion studies were performed using Potentiodynamic studies were performed in 3.5% NaCl & 0.1N H2SO4. The Results show that the anodized film of Titanium show different spectrum of colors from Brown-Violet-Tea or Peacock. SEM & EDAX analyses show that the anodized film of Titanium is mainly made up of TiO2 and Ti2O3. Potentiodynamic study implies that the film developed on Titanium using the bath of Chromic Acid exhibits good corrosion resistance. The A.C. Impedance study shows that the film is more compact, adherent and more uniform in chromic acid bath.

  15. Neuromodulation of conditioned placebo/nocebo in heat pain: anodal vs cathodal transcranial direct current stimulation to the right dorsolateral prefrontal cortex.

    Science.gov (United States)

    Egorova, Natalia; Yu, Rongjun; Kaur, Navneet; Vangel, Mark; Gollub, Randy L; Dougherty, Darin D; Kong, Jian; Camprodon, Joan A

    2015-07-01

    Placebo and nocebo play an important role in clinical practice and medical research. Modulating placebo/nocebo responses using noninvasive brain stimulation methods, such as transcranial direct current stimulation (tDCS), has the potential to harness these effects to therapeutic benefit in a clinical setting. In this study, we assessed the effect of anodal and cathodal tDCS over the right dorsolateral prefrontal cortex (rDLPFC) on conditioned placebo/nocebo cue response to heat pain. Two matched groups of healthy volunteers were subjected to an identical session of conditioning, during which low and high cues (abstract images) were associated with low and high pain levels, respectively. Twenty-minute 2-mA tDCS (either anodal or cathodal) over the rDLPFC was applied. The influence of tDCS current polarity (anodal vs cathodal) on placebo and nocebo was assessed, using subjects' pain ratings in response to identical pain preceded by the conditioned high or low cues. The duration of cue presentation varied to allow either fully conscious or subliminal processing. Significant placebo and nocebo effects in the anodal but not the cathodal group were elicited with the conditioning paradigm. This study provides evidence of a possibility to modulate the conditioned placebo and nocebo effect by changing the excitability of the rDLPFC using tDCS. PMID:25806605

  16. Polarization properties of linearly polarized parabolic scaling Bessel beams

    Science.gov (United States)

    Guo, Mengwen; Zhao, Daomu

    2016-10-01

    The intensity profiles for the dominant polarization, cross polarization, and longitudinal components of modified parabolic scaling Bessel beams with linear polarization are investigated theoretically. The transverse intensity distributions of the three electric components are intimately connected to the topological charge. In particular, the intensity patterns of the cross polarization and longitudinal components near the apodization plane reflect the sign of the topological charge.

  17. Rectilinear lattices of polarization vortices with various spatial polarization distributions.

    Science.gov (United States)

    Fu, Shiyao; Zhang, Shikun; Wang, Tonglu; Gao, Chunqing

    2016-08-01

    In this paper, we propose a type of rectilinear lattices of polarization vortices, each spot in which has mutually independent, and controllable spatial polarization distributions. The lattices are generated by two holograms under special design. In the experiment, the holograms are encoded on two spatial light modulators, and the results fit very well with theory. Our scheme makes it possible to generate multiple polarization vortices with various polarization distributions simultaneously, for instance, radially and azimuthally polarized beams, and can be used in the domains as polarization-based data transmission system, optical manufacture, polarization detection and so on. PMID:27505812

  18. Polarized nuclear target based on parahydrogen induced polarization

    Energy Technology Data Exchange (ETDEWEB)

    D. Budker, M.P. Ledbetter, S. Appelt, L.S. Bouchard, B. Wojtsekhowski

    2012-12-01

    We discuss a novel concept of a polarized nuclear target for accelerator fixed-target scattering experiments, which is based on parahydrogen induced polarization (PHIP). One may be able to reach a 33% free-proton polarization in the ethane molecule. The potential advantages of such a target include operation at zero magnetic field, fast ({approx}100 HZ) polarization oscillation (akin to polarization reversal), and operation with large intensity of an electron beam.

  19. Removal of organic contaminants from secondary effluent by anodic oxidation with a boron-doped diamond anode as tertiary treatment

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Segura, Sergi, E-mail: sergigarcia@ub.edu [Advanced Water Management Centre, The University of Queensland, Level 4, Gehrmann Bld. (60), St Lucia, QLD 072 (Australia); Laboratori d’Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona (Spain); Keller, Jürg [Advanced Water Management Centre, The University of Queensland, Level 4, Gehrmann Bld. (60), St Lucia, QLD 072 (Australia); Brillas, Enric [Laboratori d’Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona (Spain); Radjenovic, Jelena, E-mail: j.radjenovic@awmc.uq.edu.au [Advanced Water Management Centre, The University of Queensland, Level 4, Gehrmann Bld. (60), St Lucia, QLD 072 (Australia)

    2015-02-11

    Graphical abstract: - Highlights: • Mineralization of secondary effluent by anodic oxidation with BDD anode. • Complete removal of 29 pharmaceuticals and pesticides at trace level concentrations. • Organochlorine and organobromine byproducts were formed at low μM concentrations. • Chlorine species evolution assessed to evaluate the anodic oxidation applicability. - Abstract: Electrochemical advanced oxidation processes (EAOPs) have been widely investigated as promising technologies to remove trace organic contaminants from water, but have rarely been used for the treatment of real waste streams. Anodic oxidation with a boron-doped diamond (BDD) anode was applied for the treatment of secondary effluent from a municipal sewage treatment plant containing 29 target pharmaceuticals and pesticides. The effectiveness of the treatment was assessed from the contaminants decay, dissolved organic carbon and chemical oxygen demand removal. The effect of applied current and pH was evaluated. Almost complete mineralization of effluent organic matter and trace contaminants can be obtained by this EAOP primarily due to the action of hydroxyl radicals formed at the BDD surface. The oxidation of Cl{sup −} ions present in the wastewater at the BDD anode gave rise to active chlorine species (Cl{sub 2}/HClO/ClO{sup −}), which are competitive oxidizing agents yielding chloramines and organohalogen byproducts, quantified as adsorbable organic halogen. However, further anodic oxidation of HClO/ClO{sup −} species led to the production of ClO{sub 3}{sup −} and ClO{sub 4}{sup −} ions. The formation of these species hampers the application as a single-stage tertiary treatment, but posterior cathodic reduction of chlorate and perchlorate species may reduce the risks associated to their presence in the environment.

  20. Removal of organic contaminants from secondary effluent by anodic oxidation with a boron-doped diamond anode as tertiary treatment

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Mineralization of secondary effluent by anodic oxidation with BDD anode. • Complete removal of 29 pharmaceuticals and pesticides at trace level concentrations. • Organochlorine and organobromine byproducts were formed at low μM concentrations. • Chlorine species evolution assessed to evaluate the anodic oxidation applicability. - Abstract: Electrochemical advanced oxidation processes (EAOPs) have been widely investigated as promising technologies to remove trace organic contaminants from water, but have rarely been used for the treatment of real waste streams. Anodic oxidation with a boron-doped diamond (BDD) anode was applied for the treatment of secondary effluent from a municipal sewage treatment plant containing 29 target pharmaceuticals and pesticides. The effectiveness of the treatment was assessed from the contaminants decay, dissolved organic carbon and chemical oxygen demand removal. The effect of applied current and pH was evaluated. Almost complete mineralization of effluent organic matter and trace contaminants can be obtained by this EAOP primarily due to the action of hydroxyl radicals formed at the BDD surface. The oxidation of Cl− ions present in the wastewater at the BDD anode gave rise to active chlorine species (Cl2/HClO/ClO−), which are competitive oxidizing agents yielding chloramines and organohalogen byproducts, quantified as adsorbable organic halogen. However, further anodic oxidation of HClO/ClO− species led to the production of ClO3− and ClO4− ions. The formation of these species hampers the application as a single-stage tertiary treatment, but posterior cathodic reduction of chlorate and perchlorate species may reduce the risks associated to their presence in the environment

  1. Hybrid intelligent PID control design for PEMFC anode system

    Institute of Scientific and Technical Information of China (English)

    Rui-min WANG; Ying-ying ZHANG; Guang-yi CAO

    2008-01-01

    Control design is important for proton exchange membrane fuel cell (PEMFC) generator. This work researched the anode system of a 60-kW PEMFC generator. Both anode pressure and humidity must he maintained at ideal levels during steady operation. In view of characteristics and requirements of the system, a hybrid intelligent PID controller is designed specifically based on dynamic simulation. A single neuron PI controller is used for anode humidity by adjusting the water injection to the hydrogen cell. Another incremental PID controller, based on the diagonal recurrent neural network (DRNN) dynamic identification, is used to control anode pressure to be more stable and exact by adjusting the hydrogen flow rate. This control strategy can avoid the coupling problem of the PEMFC and achieve a more adaptive ability. Simulation results showed that the control strategy can maintain both anode humidity and pressure at ideal levels regardless of variable load, nonlinear dynamic and coupling characteristics of the system. This work will give some guides for further control design and applications of the total PEMFC generator.

  2. Studies on black anodic coatings for spacecraft thermal control applications

    Energy Technology Data Exchange (ETDEWEB)

    Uma Rani, R.; Subba Rao, Y.; Sharma, A.K. [ISRO Satellite Centre, Bangalore (India). Thermal Systems Group

    2011-10-15

    An inorganic black colouring process using nickel sulphate and sodium sulphide was investigated on anodized aluminium alloy 6061 to provide a flat absorber black coating for spacecraft thermal control applications. Influence of colouring process parameters (concentration, pH) on the physico-optical properties of black anodic film was investigated. The nature of black anodic film was evaluated by the measurement of film thickness, micro hardness and scanning electron microscopy (SEM). Energy dispersive X-ray spectroscopy studies confirmed the presence of nickel and sulphur in the black anodic coating. Electrochemical impedance spectroscopy (EIS) was used to evaluate the corrosion resistance of the coating. The environmental tests, namely, humidity, corrosion resistance, thermal cycling and thermo vacuum performance tests were used to evaluate the space worthiness of the coating. Optical properties of the film were measured before and after each environmental test to ascertain its stability in harsh space environment. The black anodic films provide higher thermal emittance ({proportional_to} 0.90) and solar absorptance ({proportional_to} 0.96) and their high stability during the environmental tests indicated their suitability for space and allied applications. (orig.)

  3. Surface characterization of anodized zirconium for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, A. Gomez [Division corrosion - INTEMA, Universidad Nacional del Mar del Plata - CONICET, Juan B. Justo 4302, (7600) Mar del Plata (Argentina); Schreiner, W. [LSI - LANSEN, Departamento de Fisica, UFPR, Curitiba (Brazil); Duffo, G. [Departamento de Materiales, Comision Nacional de Energia Atomica - CONICET, Av. Gral. Paz 1499, (1650) San Martin, Buenos Aires (Argentina); Universidad Nacional de Gral. San Martin, Av. Gral. Paz 1499, (1650) San Martin, Buenos Aires (Argentina); Cere, S., E-mail: smcere@fi.mdp.edu.ar [Division corrosion - INTEMA, Universidad Nacional del Mar del Plata - CONICET, Juan B. Justo 4302, (7600) Mar del Plata (Argentina)

    2011-05-15

    Mechanical properties and corrosion resistance of zirconium make this material suitable for biomedical implants. Its good in vivo performance is mainly due to the presence of a protective oxide layer that minimizes corrosion rate, diminishes the amount of metallic ions released to the biological media and facilitates the osseointegration process. Since the implant surface is the region in contact with living tissues, the characteristics of the surface film are of great interest. Surface modification is a route to enhance both biocompatibility and corrosion resistance of permanent implant materials. Anodizing is presented as an interesting process to modify metal surfaces with good reproducibility and independence of the geometry. In this work the surface of zirconium before and after anodizing in 1 mol/L phosphoric acid solution at a fixed potential between 3 and 30 V, was characterized by means of several surface techniques. It was found that during anodization the surface oxide grows with an inhomogeneous coverage on zirconium surface, modifying the topography. The incorporation of P from the electrolyte to the surface oxide during the anodizing process changes the surface chemistry. After 30 days of immersion in Simulated Body Fluid (SBF) solution, Ca-P rich compounds were present on anodized zirconium.

  4. A Thermally Conductive Separator for Stable Li Metal Anodes.

    Science.gov (United States)

    Luo, Wei; Zhou, Lihui; Fu, Kun; Yang, Zhi; Wan, Jiayu; Manno, Michael; Yao, Yonggang; Zhu, Hongli; Yang, Bao; Hu, Liangbing

    2015-09-01

    Li metal anodes have attracted considerable research interest due to their low redox potential (-3.04 V vs standard hydrogen electrode) and high theoretical gravimetric capacity of 3861 mAh/g. Battery technologies using Li metal anodes have shown much higher energy density than current Li-ion batteries (LIBs) such as Li-O2 and Li-S systems. However, issues related to dendritic Li formation and low Coulombic efficiency have prevented the use of Li metal anode technology in many practical applications. In this paper, a thermally conductive separator coated with boron-nitride (BN) nanosheets has been developed to improve the stability of the Li metal anodes. It is found that using the BN-coated separator in a conventional organic carbonate-based electrolyte results in the Coulombic efficiency stabilizing at 92% over 100 cycles at a current rate of 0.5 mA/cm(2) and 88% at 1.0 mA/cm(2). The improved Coulombic efficiency and reliability of the Li metal anodes is due to the more homogeneous thermal distribution resulting from the thermally conductive BN coating and to the smaller surface area of initial Li deposition. PMID:26237519

  5. Plant-scale anodic dissolution of unirradiated IFR fuel pins

    International Nuclear Information System (INIS)

    This report discusses anodic dissolution which is a major operation in the pyrometallurgical process for recycling spent metal fuels from the Integral Fast Reactor (IFR), an advanced reactor design developed at Argonne National Laboratory. This process involves electrorefining the heavy metals (uranium and plutonium) from chopped, steel-clad fuel segments. The heavy metals are electrotransported from anodic dissolution baskets to solid and liquid cathodes in a molten salt electrolyte (LiCl-KCI) at 500 degrees C. Uranium is recovered on a solid cathode mandrel, while a uranium-plutonium mixture is recovered in a liquid cadmium cathode. The anode configuration consists of four baskets mounted on an anode shaft. These baskets provide parallel circuits in the electrolyte and salt flow through the chopped fuelbed as the baskets are rotated. The baskets for the engineering-scale tests were sized to contain up to 2.5 kg of heavy metal. Anodic dissolution of 10 kg batches of chopped, steel-clad simulated tuel (U-10% Zr and U-Zr-Fs alloy) was demonstrated

  6. Low cost fuel cell diffusion layer configured for optimized anode water management

    Science.gov (United States)

    Owejan, Jon P; Nicotera, Paul D; Mench, Matthew M; Evans, Robert E

    2013-08-27

    A fuel cell comprises a cathode gas diffusion layer, a cathode catalyst layer, an anode gas diffusion layer, an anode catalyst layer and an electrolyte. The diffusion resistance of the anode gas diffusion layer when operated with anode fuel is higher than the diffusion resistance of the cathode gas diffusion layer. The anode gas diffusion layer may comprise filler particles having in-plane platelet geometries and be made of lower cost materials and manufacturing processes than currently available commercial carbon fiber substrates. The diffusion resistance difference between the anode gas diffusion layer and the cathode gas diffusion layer may allow for passive water balance control.

  7. The surface treatment on oxide film of pure titanium Part 1. The effect of Anodic oxidation

    Institute of Scientific and Technical Information of China (English)

    Ge Wang; Xiangrong Cheng

    2006-01-01

    that the open circuit potential (OCP) of the anodic oxide was very stable at 0mV. Natural oxide increased quickly from -50 mV to -40mV and plateaued 350s later at -40mV. The curve of anodic polarization in the same liquid showed that the polarized current was 100 times lower than that of natural oxide film. In artificial seawater (ASW) the OCP of the anodic oxide was stable at -90mV. Natural oxide in ASW did not stop rising from -480mV to -310mV during 1000s. The active current appeared to be much greater than that of the anodic oxide film. Conclusion: The color of the oxide film may be related to the thickness and influenced the future prosthetics as an implant. So gold was chosen as the ideal color. The reason was not clear why the rule of altering at peak 2.55 and 2.34 below the surface titanium oxides. The stability and corrosive-resistance of the anodic oxide film was much higher than that of natural oxide film. Anodic oxidation was a good way to enhance the pure titanium corrosive-resistance in vitro.

  8. High performance single step co-fired solid oxide fuel cells (SOFC): Polarization measurements and analysis

    Science.gov (United States)

    Yoon, Kyung Joong

    At present, one of the major obstacles for the commercialization of solid oxide fuel cell (SOFC) power systems is their high manufacturing costs expressed in terms of SOFC system cost per unit power ($/kW). In this work, anode-supported planar SOFCs were fabricated by a cost-competitive single step co-firing process. The cells were comprised of a porous Ni + yittria-stabilized zirconia (YSZ) anode support, a porous-fine-grained Ni + YSZ anode active layer for some experiments, a dense YSZ electrolyte, a porous-fine-grained Ca-doped LaMnO3 (LCM) + YSZ cathode active layer, and a porous LCM cathode current collector layer. The fabrication process involved tape casting or high shear compaction (HSC) of the anode support followed by screen printing of the remaining component layers. The cells were then co-fired at 1300˜1340°C for 2 hours. The performance of the cell fabricated with the tape casting anode was improved by minimizing various polarization losses through experimental and theoretical modeling approaches, and the maximum power density of 1.5 W/cm 2 was obtained at 800°C with humidified hydrogen (3% H2O) and air. The cells were also tested with various compositions of humidified hydrogen (3˜70% H2O) to simulate the effect of practical fuel utilization on the cell performance. Based on these measurements, an analytical model describing anodic reactions was developed to understand reaction kinetics and rate limiting steps. The cell performance at high fuel utilization was significantly improved by increasing the number of the reaction sites near the anode-electrolyte interface. For anode substrate fabrication, the HSC process offers many advantages such as low fabrication costs, high production throughput, and good control of shrinkage and thickness over the conventional tape casting process. HSC process was successfully employed in single step co-firing process, and SOFCs fabricated with HSC anodes showed adequate performance both at low and high fuel

  9. Polar low monitoring

    Science.gov (United States)

    Bobylev, Leonid; Zabolotskikh, Elizaveta; Mitnik, Leonid

    2010-05-01

    Polar lows are intense mesoscale atmospheric low pressure weather systems, developing poleward of the main baroclinic zone and associated with high surface wind speeds. Small size and short lifetime, sparse in-situ observations in the regions of their development complicate polar low study. Our knowledge of polar lows and mesocyclones has come almost entirely during the period of satellite remote sensing since, by virtue of their small horizontal scale, it was rarely possible to analyse these lows on conventional weather charts using only the data from the synoptic observing network. However, the effects of intense polar lows have been felt by coastal communities and seafarers since the earliest times. These weather systems are thought to be responsible for the loss of many small vessels over the centuries, although the nature of the storms was not understood and their arrival could not be predicted. The actuality of the polar low research is stipulated by their high destructive power: they are a threat to such businesses as oil and gas exploration, fisheries and shipping. They could worsen because of global warming: a shrinking of sea ice around the North Pole, which thawed to its record minimum in the summer of 2007, is likely to give rise to more powerful storms that form only over open water and can cause hurricane-strength winds. Therefore, study of polar lows, their timely detection, tracking and forecasting represents a challenge for today meteorology. Satellite passive microwave data, starting from Special Sensor Microwave Imager (SSM/I) onboard Defense Meteorological Satellite Program (DMSP) satellite, remain invaluable source of regularly available remotely sensed data to study polar lows. The sounding in this spectral range has several advantages in comparison with observations in visible and infrared ranges and Synthetic Aperture Radar (SAR) data: independence on day time and clouds, regularity and high temporal resolution in Polar Regions. Satellite

  10. Polarization twist in perovskite ferrielectrics.

    Science.gov (United States)

    Kitanaka, Yuuki; Hirano, Kiyotaka; Ogino, Motohiro; Noguchi, Yuji; Miyayama, Masaru; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2016-09-02

    Because the functions of polar materials are governed primarily by their polarization response to external stimuli, the majority of studies have focused on controlling polar lattice distortions. In some perovskite oxides, polar distortions coexist with nonpolar tilts and rotations of oxygen octahedra. The interplay between nonpolar and polar instabilities appears to play a crucial role, raising the question of how to design materials by exploiting their coupling. Here, we introduce the concept of 'polarization twist', which offers enhanced control over piezoelectric responses in polar materials. Our experimental and theoretical studies provide direct evidence that a ferrielectric perovskite exhibits a large piezoelectric response because of extended polar distortion, accompanied by nonpolar octahedral rotations, as if twisted polarization relaxes under electric fields. The concept underlying the polarization twist opens new possibilities for developing alternative materials in bulk and thin-film forms.

  11. Polarization twist in perovskite ferrielectrics

    Science.gov (United States)

    Kitanaka, Yuuki; Hirano, Kiyotaka; Ogino, Motohiro; Noguchi, Yuji; Miyayama, Masaru; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2016-01-01

    Because the functions of polar materials are governed primarily by their polarization response to external stimuli, the majority of studies have focused on controlling polar lattice distortions. In some perovskite oxides, polar distortions coexist with nonpolar tilts and rotations of oxygen octahedra. The interplay between nonpolar and polar instabilities appears to play a crucial role, raising the question of how to design materials by exploiting their coupling. Here, we introduce the concept of ‘polarization twist’, which offers enhanced control over piezoelectric responses in polar materials. Our experimental and theoretical studies provide direct evidence that a ferrielectric perovskite exhibits a large piezoelectric response because of extended polar distortion, accompanied by nonpolar octahedral rotations, as if twisted polarization relaxes under electric fields. The concept underlying the polarization twist opens new possibilities for developing alternative materials in bulk and thin-film forms. PMID:27586824

  12. Polarized protons at RHIC

    International Nuclear Information System (INIS)

    The approval for construction of the Relativistic Heavy Ion Collider (RHIC) provides a potential opportunity to collide polarized proton beams at energies up to 500 GeV in the center of mass and high luminosities approaching 2 x 1032/cm2/sec. This capability is enhanced by the fact that the AGS has already accelerated polarized protons and relies on the newly completed Accumulator/Booster for providing the required polarized proton intensity and a system of spin rotators (Siberian snakes) to retain the polarization. The RHIC Spin Collaboration was formed and submitted a Letter of Intent to construct this polarized collider capability and utilize its physics opportunities. In this presentation, I will discuss the plans to upgrade the AGS, the proposed layout of the RHIC siberian snakes, and timetables. The physics focus is the measurement of the spin dependent parton distributions with such accessible probes including high p(t) jets, direct photons, and Drell Yan. The attainable sensitivities and the progress that has been reached in defining the detector requirements will be outlined

  13. POLAR: A Space-borne X-Ray Polarimeter for Transient Sources

    CERN Document Server

    ,

    2010-01-01

    POLAR is a novel compact Compton X-ray polarimeter designed to measure the linear polarization of the prompt emission of Gamma Ray Bursts (GRB) and other strong transient sources such as soft gamma repeaters and solar flares in the energy range 50-500 keV. A detailed measurement of the polarization from astrophysical sources will lead to a better understanding of the source geometry and emission mechanisms. POLAR is expected to observe every year several GRBs with a minimum detectable polarization smaller than 10%, thanks to its large modulation factor, effective area, and field of view. POLAR consists of 1600 low-Z plastic scintillator bars, divided in 25 independent modular units, each read out by one flat-panel multi-anode photomultiplier. The design of POLAR is reviewed, and results of tests of one modular unit of the engineering and qualification model (EQM) of POLAR with synchrotron radiation are presented. After construction and testing of the full EQM, we will start building the flight model in 2011, ...

  14. Polarization analysis of optical systems

    Science.gov (United States)

    Chipman, Russell A.

    1989-01-01

    For most optical systems it is typically assumed that the transmitted wavefront has uniform (or Gaussian) amplitude and constant polarization state. This is the default assumption of geometrical optics. This paper considers methods suitable for analyzing systems for which this assumption is not valid. Such methods of polarization analysis include polarization ray tracing and polarization aberration theory. Definitions of the basic classes of polarization phenomena and a review of the Jones calculus are included to form a basis for the discussion.

  15. Effect of heat treatment on bioactivity of anodic titania films

    International Nuclear Information System (INIS)

    Anodic oxidation could be employed to produce crystalline titania films on Ti6Al4 V surfaces for inducing apatite formation in simulated body fluid (SBF). In this work, the effect of further heat treatment on the bioactivity of anodic titania films was researched. The surface constitution, morphology, crystal structure and apatite-forming ability of titania films were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicated the apatite formation on the Ti6Al4 V surfaces could be attributed to abundance of Ti-OH groups formed via anodic oxidation, but subsequent heat treatment would decrease the amount of surface hydroxyl (OH) groups and result in the loss of the apatite-forming ability.

  16. Tunable structural color of anodic tantalum oxide films

    Institute of Scientific and Technical Information of China (English)

    Sheng Cui-Cui; Cai Yun-Yu; Dai En-Mei; Liang Chang-Hao

    2012-01-01

    Tantalum (Ta) oxide films with tunable structural color were fabricated easily using anodic oxidation.The structure,components,and surface valence states of the oxide filns were investigated by using gazing incidence X-ray diffractometry,X-ray photoelectron microscopy,and surface analytical techniques.Their thickness and optical properties were studied by using spectroscopic ellipsometry and total reflectance spectrum.Color was accurately defined using L*a*b* scale.The thickness of compact Ta2O5 films was linearly dependent on anodizing voltage.The film color was tunable by adjusting the anodic voltage.The difference in color appearance resulted from the interference behavior between the interfaces of air-oxide and oxide-metal.

  17. Surface of Alumina Films after Prolonged Breakdowns in Galvanostatic Anodization

    Directory of Open Access Journals (Sweden)

    Christian Girginov

    2011-01-01

    Full Text Available Breakdown phenomena are investigated at continuous isothermal (20∘C and galvanostatic (0.2–5 mA cm−2 anodizing of aluminum in ammonium salicylate in dimethylformamide (1 M AS/DMF electrolyte. From the kinetic (-curves, the breakdown voltage ( values are estimated, as well as the frequency and amplitude of oscillations of formation voltage ( at different current densities. The surface of the aluminum specimens was studied using atomic force microscopy (AFM. Data on topography and surface roughness parameters of the electrode after electric breakdowns are obtained as a function of anodization time. The electrode surface of anodic films, formed with different current densities until the same charge density has passed (2.5 C cm−2, was assessed. Results are discussed on the basis of perceptions of avalanche mechanism of the breakdown phenomena, due to the injection of electrons and their multiplication in the volume of the film.

  18. Tin nanoparticles as an effective conductive additive in silicon anodes

    Science.gov (United States)

    Zhong, L.; Beaudette, C.; Guo, J.; Bozhilov, K.; Mangolini, L.

    2016-08-01

    We have found that the addition of tin nanoparticles to a silicon-based anode provides dramatic improvements in performance in terms of both charge capacity and cycling stability. Using a simple procedure and off-the-shelf additives and precursors, we developed a structure in which the tin nanoparticles are segregated at the interface between the silicon-containing active layer and the solid electrolyte interface. Even a minor addition of tin, as small as ∼2% by weight, results in a significant decrease in the anode resistance, as confirmed by electrochemical impedance spectroscopy. This leads to a decrease in charge transfer resistance, which prevents the formation of electrically inactive “dead spots” in the anode structure and enables the effective participation of silicon in the lithiation reaction.

  19. Progress in Nano-Engineered Anodic Aluminum Oxide Membrane Development

    Directory of Open Access Journals (Sweden)

    Gerrard Eddy Jai Poinern

    2011-02-01

    Full Text Available The anodization of aluminum is an electro-chemical process that changes the surface chemistry of the metal, via oxidation, to produce an anodic oxide layer. During this process a self organized, highly ordered array of cylindrical shaped pores can be produced with controllable pore diameters, periodicity and density distribution. This enables anodic aluminum oxide (AAO membranes to be used as templates in a variety of nanotechnology applications without the need for expensive lithographical techniques. This review article is an overview of the current state of research on AAO membranes and the various applications of nanotechnology that use them in the manufacture of nano-materials and devices or incorporate them into specific applications such as biological/chemical sensors, nano-electronic devices, filter membranes and medical scaffolds for tissue engineering.

  20. Tin nanoparticles as an effective conductive additive in silicon anodes

    Science.gov (United States)

    Zhong, L.; Beaudette, C.; Guo, J.; Bozhilov, K.; Mangolini, L.

    2016-01-01

    We have found that the addition of tin nanoparticles to a silicon-based anode provides dramatic improvements in performance in terms of both charge capacity and cycling stability. Using a simple procedure and off-the-shelf additives and precursors, we developed a structure in which the tin nanoparticles are segregated at the interface between the silicon-containing active layer and the solid electrolyte interface. Even a minor addition of tin, as small as ∼2% by weight, results in a significant decrease in the anode resistance, as confirmed by electrochemical impedance spectroscopy. This leads to a decrease in charge transfer resistance, which prevents the formation of electrically inactive “dead spots” in the anode structure and enables the effective participation of silicon in the lithiation reaction. PMID:27484849

  1. Magnetic field influence on pulsed air arc anode mass loss

    International Nuclear Information System (INIS)

    Anode mass loss was studied in pulsed air arcs between two electrode pairs, 99.99% Ni/Ni and 99.5% Cu/Cu, in a transverse magnetic field. In both cases the anode mass loss decreased (by a factor of 2 for Cu and by a factor of 6 for Ni) when the magnetic field was increased up to 15-20 Oe and then remained approximately constant for Cu and decreased weakly for Ni. The observed dependences of anode mass loss were explained by the published behaviour of an arc motion in a magnetic field. The lattice parameter was decreased by the discharge treatment. The decrease was attributed to residual tensile stress produced on the arced surface. The lattice parameter of Ni increased with magnetic field, while for Cu it did not change substantially. The different behaviour is attributed to the magneto-plastic effect on magnetic Ni, which increases the plasticity with magnetic field. (paper)

  2. Trends in Catalytic Activity for SOFC Anode materials

    DEFF Research Database (Denmark)

    Rossmeisl, Jan; Bessler, W. G.

    2008-01-01

    Quantum mechanical calculations on the level of density-functional theory are used to calculate the stability of surface-adsorbed hydrogen atoms, oxygen atoms, and hydroxyl radicals for a variety of metals (Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Pt, Au) that may be used as electrode materials...... for solid oxide fuel cell (SOFC) anodes. The reaction energies along the hydrogen oxidation pathway were quantified for both, oxygen spillover and hydrogen spillover mechanisms at the three-phase boundary. The ab initio results are compared to previously-obtained experimental anode activities measured...... that oxygen spillover, where adsorbed oxygen is a key intermediate, is the dominant reaction pathway under the conditions used in the experiments. In this way the activity is linked directly to the microscopic binding affinities of reaction intermediates, providing a new understanding of the anode reaction...

  3. Tin nanoparticles as an effective conductive additive in silicon anodes.

    Science.gov (United States)

    Zhong, L; Beaudette, C; Guo, J; Bozhilov, K; Mangolini, L

    2016-01-01

    We have found that the addition of tin nanoparticles to a silicon-based anode provides dramatic improvements in performance in terms of both charge capacity and cycling stability. Using a simple procedure and off-the-shelf additives and precursors, we developed a structure in which the tin nanoparticles are segregated at the interface between the silicon-containing active layer and the solid electrolyte interface. Even a minor addition of tin, as small as ∼2% by weight, results in a significant decrease in the anode resistance, as confirmed by electrochemical impedance spectroscopy. This leads to a decrease in charge transfer resistance, which prevents the formation of electrically inactive "dead spots" in the anode structure and enables the effective participation of silicon in the lithiation reaction. PMID:27484849

  4. Anodic passivation of Pb-Ag-Nd anode in fluoride-containing H2SO4 solution

    Institute of Scientific and Technical Information of China (English)

    钟晓聪; 蒋良兴; 刘芳洋; 李劼; 刘业翔

    2015-01-01

    An attempt was made to build up a thick and compact oxide layer rapidly by pre-treating the Pb-Ag-Nd anode in fluoride-containing H2SO4 solution. The passivation reaction of Pb-Ag-Nd anode during pre-treatment process was investigated using cyclic voltammetry, linear scanning voltammetry, environmental scanning electron microscopy and X-ray diffraction analysis. The results show that PbF2 and PbSO4 are formed near the potential of Pb/PbSO4 couple. The pre-treatment in fluoride-containing H2SO4 solution contributes to the formation of a thick, compact and adherent passive film. Furthermore, pre-treatment in fluoride-containing H2SO4 solution also facilitates the formation of PbO2 on the anodic layer, and the reason could be attributed to the formation of more PbF2 and PbSO4 during the pre-treatment which tend to transform to PbO2 during the following electrowinning process. In addition, the anodic layer on anode with pre-treatment in fluoride-containing H2SO4 solution is thick and compact, and its predominant composition isβ-PbO2. In summary, the pre-treatment in fluoride-containing H2SO4 solution benefits the formation of a desirable protective layer in a short time.

  5. Physics of polarized targets

    CERN Document Server

    Niinikoski, Tapio

    2014-01-01

    For developing, building and operating solid polarized targets we need to understand several fields of physics that have seen sub stantial advances during the last 50 years. W e shall briefly review a selection of those that are important today. These are: 1) quantum statistical methods to describe saturation and relaxation in magnetic resonance; 2) equal spin temperature model for dy namic nuclear polarization; 3 ) weak saturation during NMR polarization measurement; 4 ) refrigeration using the quantum fluid properties of helium isotopes. These, combined with superconducting magnet technologies, permit today to reach nearly complete pola rization of almost any nuclear spins. Targets can be operated in frozen spin mode in rather low and inhomogeneous field of any orientation, and in DNP mode in beams of high intensity. Beyond such experiments of nuclear and particle physics, applications a re also emerging in macromolecular chemistry and in magnetic resonance imaging. This talk is a tribute to Michel Borghini...

  6. Polarized atomic hydrogen beam

    Energy Technology Data Exchange (ETDEWEB)

    Chan, N.; Crowe, D.M.; Lubell, M.S.; Tang, F.C.; Vasilakis, A.; Mulligan, F.J.; Slevin, J.

    1988-12-01

    We describe the design and operating characteristics of a simple polarized atomic hydrogen beam particularly suitable for applications to crossed beams experiments. In addition to experimental measurements, we present the results of detailed computer models, using Monte-Carlo ray tracing techniques, optical analogs, and phase-space methods, that not only provide us with a confirmation of our measurement, but also allow us to characterize the density, polarization, and atomic fraction of the beam at all points along its path. As a subsidiary result, we also present measurements of the relative and absolute efficiencies of the V/G Supavac mass analyzer for masses 1 and 2.

  7. Microwave Frequency Polarizers

    Science.gov (United States)

    Ha, Vien The; Mirel, Paul; Kogut, Alan J.

    2013-01-01

    This article describes the fabrication and analysis of microwave frequency polarizing grids. The grids are designed to measure polarization from the cosmic microwave background. It is effective in the range of 500 to 1500 micron wavelength. It is cryogenic compatible and highly robust to high load impacts. Each grid is fabricated using an array of different assembly processes which vary in the types of tension mechanisms to the shape and size of the grids. We provide a comprehensive study on the analysis of the grids' wire heights, diameters, and spacing.

  8. Source of polarized electrons

    International Nuclear Information System (INIS)

    This paper reports on a source of polarized electrons based on photoemission of GaAsP-cathodes set up at the Mainz 300 MeV linear accelerator. It was successfully run in a measurement of parity violation in quasielastic electron beryllium scattering at 300 MeV and backwards angles. The source parameters are: Degree of polarization P=0.44, average beam current 1=28 μA, peak current 1p=140 mA, life time of cathode 200 h. A c.w. source for the Mainz race track microtron MAMI is designed using the same basic photoemission process

  9. Polarization encoded color camera.

    Science.gov (United States)

    Schonbrun, Ethan; Möller, Guðfríður; Di Caprio, Giuseppe

    2014-03-15

    Digital cameras would be colorblind if they did not have pixelated color filters integrated into their image sensors. Integration of conventional fixed filters, however, comes at the expense of an inability to modify the camera's spectral properties. Instead, we demonstrate a micropolarizer-based camera that can reconfigure its spectral response. Color is encoded into a linear polarization state by a chiral dispersive element and then read out in a single exposure. The polarization encoded color camera is capable of capturing three-color images at wavelengths spanning the visible to the near infrared. PMID:24690806

  10. Internal polarized targets

    Energy Technology Data Exchange (ETDEWEB)

    Kinney, E.R.; Coulter, K.; Gilman, R.; Holt, R.J.; Kowalczyk, R.S.; Napolitano, J.; Potterveld, D.H.; Young, L. (Argonne National Lab., IL (USA)); Mishnev, S.I.; Nikolenko, D.M.; Popov, S.G.; Rachek, I.A.; Temnykh, A.B.; Toporkov, D.K.; Tsentalovich, E.P.; Wojtsekhowski, B.B. (AN SSSR, Novosibirsk (USSR). Inst. Yadernoj Fiziki)

    1989-01-01

    Internal polarized targets offer a number of advantages over external targets. After a brief review of the basic motivation and principles behind internal polarized targets, the technical aspects of the atomic storage cell will be discussed in particular. Sources of depolarization and the means by which their effects can be ameliorated will be described, especially depolarization by the intense magnetic fields arising from the circulating particle beam. The experience of the Argonne Novosibirsk collaboration with the use of a storage cell in a 2 GeV electron storage ring will be the focus of this technical discussion. 17 refs., 11 figs.

  11. Anodic Aluminum Oxide Templates for Nano wires Array Fabrication

    International Nuclear Information System (INIS)

    This paper reports on the process developed to fabricate anodic aluminium oxide (AAO) templates suitable for the fabrication of nano wire arrays. Anodization process has been used to fabricate the AAO templates with pore diameters ranging from 15 nm to 30 nm. Electrodeposition of parallel arrays of high aspect ratio nickel nano wires were demonstrated using these fabricated AAO templates. The nano wires produced were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that the orientations of the electrodeposited nickel nano wires were governed by the deposition current and electrolyte conditions. (author)

  12. Tin-phosphate glass anode for sodium ion batteries

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Honma

    2013-11-01

    Full Text Available The electrochemical property of tin-phosphate (designate as GSPO glass anode for the sodium ion battery was studied. During the first charge process, sodium ion diffused into GSPO glass matrix and due to the reduction of Sn2+ to Sn0 state sodiated tin metal nano-size particles are formed in oxide glass matrix. After the second cycle, we confirmed the steady reversible reaction ∼320 mAh/g at 0–1 V cutoff voltage condition by alloying process in NaxSn4. The tin-phosphate glass is a promising candidate of new anode active material that realizes high energy density sodium ion batteries.

  13. Overview of SOFC Anode Interactions with Coal Gas Impurities

    Energy Technology Data Exchange (ETDEWEB)

    O. A. Marina; L. R. Pederson; R. Gemmen; K. Gerdes; H. Finklea; I. B. Celik

    2010-03-01

    An overview of the results of SOFC anode interactions with phosphorus, arsenic, selenium, sulfur, antimony, and hydrogen chloride as single contaminants or in combinations is discussed. Tests were performed using both anode- and electrolyte-supported cells in synthetic and actual coal gas for periods greater than 1000 hours. Post-test analyses were performed to identify reaction products formed and their distribution, and compared to phases expected from thermochemical modeling. The ultimate purpose of this work is to establish maximum permissible concentrations for impurities in coal gas, to aid in the selection of appropriate coal gas clean-up technologies.

  14. Oxygen-producing inert anodes for SOM process

    Science.gov (United States)

    Pal, Uday B

    2014-02-25

    An electrolysis system for generating a metal and molecular oxygen includes a container for receiving a metal oxide containing a metallic species to be extracted, a cathode positioned to contact a metal oxide housed within the container; an oxygen-ion-conducting membrane positioned to contact a metal oxide housed within the container; an anode in contact with the oxygen-ion-conducting membrane and spaced apart from a metal oxide housed within the container, said anode selected from the group consisting of liquid metal silver, oxygen stable electronic oxides, oxygen stable crucible cermets, and stabilized zirconia composites with oxygen stable electronic oxides.

  15. The approach curve method for large anode-cathode distances

    Energy Technology Data Exchange (ETDEWEB)

    Mammana, Victor P.; Monteiro, Othon R.; Fonseca, Leo R.C.

    2003-09-20

    An important technique used to characterize field emission is the measurement of the emitted current against electric field (IxE). In this work we discuss a procedure for obtaining IxE data based on multiple approach curves. We show that the simulated features obtained for an idealized uniform surface matches available experimental data for small anode-cathode distances, while for large distances the simulation predicts a departure from the linear regime. We also discuss the shape of the approach curves for large anode-cathode distances for a cathode made of carbon nanotubes.

  16. Composite anodes for lithium-ion batteries: status and trends

    Directory of Open Access Journals (Sweden)

    Alain Mauger

    2016-07-01

    Full Text Available Presently, the negative electrodes of lithium-ion batteries (LIBs is constituted by carbon-based materials that exhibit a limited specific capacity 372 mAh g−1 associated with the cycle between C and LiC6. Therefore, many efforts are currently made towards the technological development nanostructured materials in which the electrochemical processes occurs as intercalation, alloying or conversion reactions with a good accommodation of dilatation/contraction during cycling. In this review, attention is focused on advanced anode composite materials based on carbon, silicon, germanium, tin, titanium and conversion anode composite based on transition-metal oxides.

  17. Simultaneous Use Of Zr And Mg Anodes In XPS

    Science.gov (United States)

    Allgeyer, D. F.; Pratz, E. H.

    1996-01-01

    Improved x-ray source for x-ray photoelectron spectroscopy (XPS) contains both zirconium anode with beryllium window and magnesium anode with aluminum window. Previously unresolvable peaks of electron-energy spectrum become resolvable. Developed specifically for use in analyzing distributions of chemical constituents in surface layers of specimens of 2219 aluminum alloy and in determining the depths of surface oxide layers and relative proportions of aluminum and oxide in layers. Also used to study chemical constituents of surface layers in other material systems - for example, thin oxide films on silicon-based semiconductor devices, oxide films on alloys, and surface layers affecting adhesion of paints or bonding materials.

  18. Inward lithium-ion breathing of hierarchically porous silicon anodes

    OpenAIRE

    Xiao, Qiangfeng; Gu, Meng; Yang, Hui; Li, Bing; Zhang, Cunman; Liu, Yang; Liu, Fang; Dai, Fang; Yang, Li; Liu, Zhongyi; Xiao, Xingcheng; Liu, Gao; Zhao, Peng; Zhang, Sulin; Wang, Chongmin

    2015-01-01

    Silicon has been identified as a highly promising anode for next-generation lithium-ion batteries (LIBs). The key challenge for Si anodes is large volume change during the lithiation/delithiation cycle that results in chemomechanical degradation and subsequent rapid capacity fading. Here we report a novel fabrication method for hierarchically porous Si nanospheres (hp-SiNSs), which consist of a porous shell and a hollow core. On charge/discharge cycling, the hp-SiNSs accommodate the volume ch...

  19. Gas-discharge particle detector with ball-tipped anodes

    International Nuclear Information System (INIS)

    A new gas-discharge particle detector, whose anode is a set of balls 2mm in diameter is investigated. The chamber is blowing down by the argon-methane-methylal gas mixture with the ratio 3:1:1. The detector operates in the self-quenching streamer mode, has high efficiency and a wide counting characteristic plateau. The maximum counting rate of particles at one ball is ∼ 2.5x104 s-1. The ball-tipped anodes allow making reliable complex-shaped detectors. Two-coordinate detection of multiparticle events can be naturally organized in detectors like that

  20. Impact de la preparation des anodes crues et des conditions de cuisson sur la fissuration dans des anodes denses

    Science.gov (United States)

    Amrani, Salah

    La fabrication de l'aluminium est realisee dans une cellule d'electrolyse, et cette operation utilise des anodes en carbone. L'evaluation de la qualite de ces anodes reste indispensable avant leur utilisation. La presence des fissures dans les anodes provoque une perturbation du procede l'electrolyse et une diminution de sa performance. Ce projet a ete entrepris pour determiner l'impact des differents parametres de procedes de fabrication des anodes sur la fissuration des anodes denses. Ces parametres incluent ceux de la fabrication des anodes crues, des proprietes des matieres premieres et de la cuisson. Une recherche bibliographique a ete effectuee sur tous les aspects de la fissuration des anodes en carbone pour compiler les travaux anterieurs. Une methodologie detaillee a ete mise au point pour faciliter le deroulement des travaux et atteindre les objectifs vises. La majorite de ce document est reservee pour la discussion des resultats obtenus au laboratoire de l'UQAC et au niveau industriel. Concernant les etudes realisees a l'UQAC, une partie des travaux experimentaux est reservee a la recherche des differents mecanismes de fissuration dans les anodes denses utilisees dans l'industrie d'aluminium. L'approche etait d'abord basee sur la caracterisation qualitative du mecanisme de la fissuration en surface et en profondeur. Puis, une caracterisation quantitative a ete realisee pour la determination de la distribution de la largeur de la fissure sur toute sa longueur, ainsi que le pourcentage de sa surface par rapport a la surface totale de l'echantillon. Cette etude a ete realisee par le biais de la technique d'analyse d'image utilisee pour caracteriser la fissuration d'un echantillon d'anode cuite. L'analyse surfacique et en profondeur de cet echantillon a permis de voir clairement la formation des fissures sur une grande partie de la surface analysee. L'autre partie des travaux est basee sur la caracterisation des defauts dans des echantillons d'anodes crues

  1. Anode materials for hydrogen sulfide containing feeds in a solid oxide fuel cell

    Science.gov (United States)

    Roushanafshar, Milad

    SOFCs which can directly operate under high concentration of H2S would be economically beneficial as this reduces the cost of gas purification. H2S is highly reactive gas specie which can poison most of the conventional catalysts. As a result, developing anode materials which can tolerate high concentrations of H2S and also display high activity toward electrochemical oxidation of feed is crucial and challenging for this application. The performance of La0.4Sr0.6TiO3+/-delta -Y0.2Ce0.8O2-delta (LST-YDC) composite anodes in solid oxide fuel cells significantly improved when 0.5% H2 S was present in syngas (40% H2, 60% CO) or hydrogen. Gas chromatography and mass spectrometry analyses revealed that the rate of electrochemical oxidation of all fuel components improved when H2S containing syngas was present in the fuel. Electrochemical stability tests performed under potentiostatic condition showed that there was no power degradation for different feeds, and that there was power enhancement when 0.5% H2S was present in various feeds. The mechanism of performance improvement by H2S was discussed. Active anodes were synthesized via wet chemical impregnation of different amounts of La0.4Ce0.6O1.8 (LDC) and La 0.4Sr0.6TiO3 (L4ST) into porous yttria-stabilized zirconia (YSZ). Co-impregnation of LDC with LS4T significantly improved the performance of the cell from 48 mW.cm-2 (L4ST) to 161 mW.cm -2 (LDC-L4ST) using hydrogen as fuel at 900 °C. The contribution of LDC to this improvement was investigated using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM). EIS measurements using symmetrical cells showed that the polarization resistance decreased from 3.1¦O.cm 2 to 0.5 O.cm2 when LDC was co-impregnated with LST, characterized in humidified H2 (3% H2O) at 900 °C. In addition, the microstructure of the cell was modified when LDC was impregnated prior to L4ST into the porous YSZ. TEM and SEM

  2. Effects of sodium tartrate anodizing on fatigue life of TA15 titanium alloy

    Directory of Open Access Journals (Sweden)

    Fu Chunjuan

    2015-08-01

    Full Text Available Anodizing is always used as an effective surface modification method to improve the corrosion resistance and wear resistance of titanium alloy. The sodium tartrate anodizing is a new kind of environmental anodizing method. In this work, the effects of sodium tartrate anodizing on mechanical property were studied. The oxide film was performed on the TA15 titanium alloy using sodium tartrate as the film former. The effects of this anodizing and the traditional acid anodizing on the fatigue life of TA15 alloy were compared. The results show that the sodium tartrate anodizing just caused a slight increase of hydrogen content in the alloy, and had a slight effect on the fatigue life. While, the traditional acid anodizing caused a significant increase of hydrogen content in the substrate and reduced the fatigue life of the alloy significantly.

  3. Polarized Proton Collisions at RHIC

    CERN Document Server

    Bai, Mei; Alekseev, Igor G; Alessi, James; Beebe-Wang, Joanne; Blaskiewicz, Michael; Bravar, Alessandro; Brennan, Joseph M; Bruno, Donald; Bunce, Gerry; Butler, John J; Cameron, Peter; Connolly, Roger; De Long, Joseph; Drees, Angelika; Fischer, Wolfram; Ganetis, George; Gardner, Chris J; Glenn, Joseph; Hayes, Thomas; Hseuh Hsiao Chaun; Huang, Haixin; Ingrassia, Peter; Iriso, Ubaldo; Laster, Jonathan S; Lee, Roger C; Luccio, Alfredo U; Luo, Yun; MacKay, William W; Makdisi, Yousef; Marr, Gregory J; Marusic, Al; McIntyre, Gary; Michnoff, Robert; Montag, Christoph; Morris, John; Nicoletti, Tony; Oddo, Peter; Oerter, Brian; Osamu, Jinnouchi; Pilat, Fulvia Caterina; Ptitsyn, Vadim; Roser, Thomas; Satogata, Todd; Smith, Kevin T; Svirida, Dima; Tepikian, Steven; Tomas, Rogelio; Trbojevic, Dejan; Tsoupas, Nicholaos; Tuozzolo, Joseph; Vetter, Kurt; Wilinski, Michelle; Zaltsman, Alex; Zelenski, Anatoli; Zeno, Keith; Zhang, S Y

    2005-01-01

    The Relativistic Heavy Ion Collider~(RHIC) provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC to avoid depolarizing resonances. In 2003, polarized proton beams were accelerated to 100~GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. RHIC polarized proton run experience demonstrates that optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limite...

  4. Corrosion Behavior of Anodic Oxidized TiO2 Film in Seawater

    Institute of Scientific and Technical Information of China (English)

    WANG Min; WANG Wei; HE Benlin; SUN Mingliang; YIN Yansheng; LIU Lan; ZOU Wuyuan; XU Xuefei

    2010-01-01

    TiO2 films were formed on metallic titanium substrates by the anodic oxidation method in H2SO4 solution under the 80V D.C..Phase component and microstructure were characterized by X-ray diffraction(XRD)and scanning electron microscopy(SEM).Water contact angles on titanium oxide film surface were measured under both dark and sunlight illumination conditions.Corrosion tests were carried out in seawater under different illumination conditions by electrochemistry impedance spectrum(EIS)and polarization curves.The result showed that the TiO2 film prepared by the anodic oxidation method was anatase with a uniform structure and without obvious pores or cracks on its surface.The average water contact angle of the film was 116.4 ° in dark,in contrast to an angle of 42.7 ° under the UV illumination for 2 hours,which demonstrates good hydrophobic property.The anti-corrosion behavior of the TiO2 film was declining with the extended immersion time.Under dark conditions,however,the hydrophobic TiO2 film retarded the water infiltrating into the substrate.The impedance changed slowly and the corrosion current density was 2 orders of magnitude lower than that with the film illuminated by sunlight.All of those mentioned above indicate that the TiO2 film possesses much better performance under dark condition,and it can be applied as an engineering material under dark seawater environment.

  5. Impact of nanostructured anode on low-temperature performance of thin-film-based anode-supported solid oxide fuel cells

    Science.gov (United States)

    Park, Jung Hoon; Han, Seung Min; Yoon, Kyung Joong; Kim, Hyoungchul; Hong, Jongsup; Kim, Byung-Kook; Lee, Jong-Ho; Son, Ji-Won

    2016-05-01

    The impact of a nanostructured Ni-yttria-stabilized zirconia (Ni-YSZ) anode on low-temperature solid oxide fuel cell (LT-SOFC) performance is investigated. By modifying processing techniques for the anode support, anode-supported SOFCs based on thin-film (∼1 μm) electrolytes (TF-SOFCs) with and without the nanostructured Ni-YSZ (grain size ∼100 nm) anode are fabricated and a direct comparison of the TF-SOFCs to reveal the role of the nanostructured anode at low temperature is made. The cell performance of the nanostructured Ni-YSZ anode significantly increases as compared to that of the cell without it, especially at low temperatures (500 °C). The electrochemical analyses confirm that increasing the triple-phase boundary (TPB) density near the electrolyte and anode interface by the particle-size reduction of the anode increases the number of sites available for charge transfer. Thus, the nanostructured anode not only secures the structural integrity of the thin-film components over it, it is also essential for lowering the operating temperature of the TF-SOFC. Although it is widely considered that the cathode is the main factor that determines the performance of LT-SOFCs, this study directly proves that anode performance also significantly affects the low-temperature performance.

  6. Building Self-Healing Alloy Architecture for Stable Sodium-Ion Battery Anodes: A Case Study of Tin Anode Materials.

    Science.gov (United States)

    Mao, Jianfeng; Fan, Xiulin; Luo, Chao; Wang, Chunsheng

    2016-03-23

    The rational design of anode materials is a challenge in developing sodium ion batteries. Alloy anodes provide high gravimetric and volumetric capacities but suffer the short cycle life as a result of the continuous and accumulated pulverization, resulting from a large volume change during the cycling process. Herein, using pure Sn, an irreversible conversion reaction combined with an alloy reaction (SnO), and a reversible conversion reaction combined with an alloy reaction (Sn4P3) as samples, we demonstrate that the pulverization and aggregation of the alloy anode can be partially recovered and the accumulation of pulverization and aggregation during charge/discharge cycles can be terminated using a reversible conversion reaction combined with an alloy reaction. The cycling stability of three Sn-based anodes increases in order of Sn4P3 > SnO > Sn. The enhancement in Sn4P3 can be attributed to a reversible reaction of Sn4P3 + 9Na ↔ 4Sn + 3Na3P, which repairs the cracks, damage, and aggregation of Sn particles that occurred in the alloy process of 4Sn + 15Na ↔ Na15Sn4 during cycling and, hence, terminates the pulverization. The repair mechanism looks like the self-healing feature in nature, where the damage can be healed by itself. Therefore, the suggested mechanism can be called self-healing, while the repaired anode can be termed as the self-healing anode. The use of self-healing strategies to build an electrode architecture is new and highly desirable because it can increase the cycle life and provide a general approach toward stable electrode materials. PMID:26937998

  7. Facile one-step forming of NiO and yttrium-stabilized zirconia composite anodes with straight open pores for planar solid oxide fuel cell using phase-inversion tape casting method

    Science.gov (United States)

    Huang, Hua; Lin, Jie; Wang, Yunlong; Wang, Shaorong; Xia, Changrong; Chen, Chusheng

    2015-01-01

    The anode of NiO and yttria-stabilized zirconia (YSZ) with straight open pores is prepared by phase-inversion tape casting method. In the as-prepared green tape, its top and middle layers are derived from a slurry of NiO and YSZ, while the bottom layer from a slurry of graphite. The graphite layer is eliminated by calcination at elevated temperatures, leaving the finger-like porous layer exposed to the gas phase. A cell supported on the as-prepared anode substrate exhibits satisfactory electrochemical performances with a maximum power density of 780 mW cm-2 at 800 °C. The cell dose not show a convex-up curvature in I-V plots at high current density as often observed for most anode-supported cells, indicating the absence of concentration polarization which is in turn attributed to the open pore structure of the phase-inversion derived anode. The phase inversion tape casting technique explored in the present study involves almost the same equipments as and similar procedures to the conventional tape casting, and after further optimization it may become a simple and effective technique for mass production of anodes for SOFCs.

  8. Graphics of polar figure

    International Nuclear Information System (INIS)

    The objective of this work, is that starting from a data file coming from a spectra that has been softened, and of the one that have been generated its coordinates to project it in stereographic form, to create the corresponding polar figure making use of the Cyber computer of the ININ by means of the GRAPHOS package. This work only requires a Beta, Fi and Intensity (I) enter data file. It starts of the existence of a softened spectra of which have been generated already with these data, making use of some language that in this case was FORTRAN for the Cyber computer, a program is generated supported in the Graphos package that allows starting of a reading of the Beta, Fi, I file, to generate the points in a stereographic projection and that it culminates with the graph of the corresponding polar figure. The program will request the pertinent information that is wanted to capture in the polar figure just as: date, name of the enter file, indexes of the polar figure, number of levels, radio of the stereographic projection (cms.), crystalline system to which belongs the sample, name the neuter graph file by create and to add the own general data. (Author)

  9. Political Competition and Polarization

    DEFF Research Database (Denmark)

    Schultz, Christian

    This paper considers political competition and the consequences of political polarization when parties are better informed about how the economy functions than voters are. Specifically, parties know the cost producing a public good, voters do not. An incumbent's choice of policy acts like a signal...

  10. Polarized Neutron Scattering

    OpenAIRE

    Roessli, B.; Böni, P.

    2000-01-01

    The technique of polarized neutron scattering is reviewed with emphasis on applications. Many examples of the usefulness of the method in various fields of physics are given like the determination of spin density maps, measurement of complex magnetic structures with spherical neutron polarimetry, inelastic neutron scattering and separation of coherent and incoherent scattering with help of the generalized XYZ method.

  11. No More Polarization, Please!

    DEFF Research Database (Denmark)

    Hansen, Mia Reinholt

    and the increasing levels of complexities it entails, such polarization is not fruitful in the attempt to explain motivation of organizational members. This paper claims that a more nuanced perspective on motivation, acknowledging the co-existence of intrinsic and extrinsic motivation, the possible interaction...

  12. The Description of Polarization

    OpenAIRE

    Mweene, Habatwa V.

    2005-01-01

    In this paper, we extend to polarization the method we have recently employed to treat spin. We are led to a generalization of its treatment. Thus, we are able to connect its matrix treatment to first principles, and we obtain the most generalized probability amplitudes and operators for its description.

  13. Saturn's Polar Atmosphere

    CERN Document Server

    Sayanagi, Kunio M; Dyudina, Ulyana A; Fletcher, Leigh N; Sánchez-Lavega, Agustin; West, Robert A

    2016-01-01

    This book chapter, Saturn's Polar Atmosphere, is to be published by Cambridge University Press as part of a multi-volume work edited by Kevin Baines, Michael Flasar, Norbert Krupp, and Thomas Stallard, entitled "Saturn in the 21st Century." This chapter reviews the state of our knowledge about Saturn's polar atmosphere that has been revealed through Earth- and space-based observation as well as theoretical and numerical modeling. In particular, the Cassini mission to Saturn, which has been in orbit around the ringed planet since 2004, has revolutionized our understanding of the planet. The current review updates a previous review by Del Genio et al (2009; Saturn Atmospheric Structure and Dynamics, Chapter 7 of "Saturn from Cassini-Huygens"), written after Cassini's primary mission phase that ended in 2008, by focusing on the north polar region of Saturn and comparing it to the southern high latitudes. Two prominent features in the northern high latitudes are the northern hexagon and the north polar vortex; we...

  14. Polarized parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    de Florian, D.; Epele, L.N.; Fanchiotti, H.; Garcia Canal, C.A.; Sassot, R. (Laboratorio de Fisica Teorica, Departamento de Fisica, Universidad Nacional de La Plata, C.C. 67-1900 La Plata (Argentina))

    1995-01-01

    We analyze spin-dependent parton distributions consistent with the most recent measurements of the spin-dependent deep inelastic scattering structure functions and obtained in the framework of the spin dilution model. Predictions for the doubly polarized proton-proton Drell-Yan asymmetry, for the high [ital p][sub [ital T

  15. Coordenadas polares: curvas maravillosas

    Directory of Open Access Journals (Sweden)

    Norberto Jaime Chau Pérez

    2010-07-01

    Full Text Available Se presenta una actividad colaborativa en la que se trabaja el tema coordenadas polares. Se presentan los objetivos de aprendizaje, el desarrollo de la actividad, los conocimientos previos necesarios y recomendaciones para una aplicación posterior.

  16. Aluminum/MoO3 anode thin films: an effective anode structure for highperformance flexible organic optoelectronics

    Institute of Scientific and Technical Information of China (English)

    Ding Lei; Zhang Fanghui; Ma Ying; Zhang Maili

    2012-01-01

    We report Al/MoO3 thin film used as a complex anode in high-performance OLEDs.The unique efficacy of the device was found to result from the enhanced injection of holes into the commonly used hole-transporting molecules due to a large reduction in the interface dipole at the anode/organic interface.The superior optical characteristics are attributed to a strong cavity effect,Due to the ease of processing Al/MoO3 we successfully demonstrated large-area flexible OLEDs on plastic substrates with uniform emission.

  17. Polarized light and optical measurement

    CERN Document Server

    Clarke, D N; Ter Haar, D

    2013-01-01

    Polarized Light and Optical Measurement is a five-chapter book that begins with a self-consistent conceptual picture of the phenomenon of polarization. Chapter 2 describes a number of interactions of light and matter used in devising optical elements in polarization studies. Specific optical elements are given in Chapter 3. The last two chapters explore the measurement of the state of polarization and the various roles played in optical instrumentation by polarization and polarization-sensitive elements. This book will provide useful information in this field of interest for research workers,

  18. Lunar Polar Coring Lander

    Science.gov (United States)

    Angell, David; Bealmear, David; Benarroche, Patrice; Henry, Alan; Hudson, Raymond; Rivellini, Tommaso; Tolmachoff, Alex

    1990-01-01

    Plans to build a lunar base are presently being studied with a number of considerations. One of the most important considerations is qualifying the presence of water on the Moon. The existence of water on the Moon implies that future lunar settlements may be able to use this resource to produce things such as drinking water and rocket fuel. Due to the very high cost of transporting these materials to the Moon, in situ production could save billions of dollars in operating costs of the lunar base. Scientists have suggested that the polar regions of the Moon may contain some amounts of water ice in the regolith. Six possible mission scenarios are suggested which would allow lunar polar soil samples to be collected for analysis. The options presented are: remote sensing satellite, two unmanned robotic lunar coring missions (one is a sample return and one is a data return only), two combined manned and robotic polar coring missions, and one fully manned core retrieval mission. One of the combined manned and robotic missions has been singled out for detailed analysis. This mission proposes sending at least three unmanned robotic landers to the lunar pole to take core samples as deep as 15 meters. Upon successful completion of the coring operations, a manned mission would be sent to retrieve the samples and perform extensive experiments of the polar region. Man's first step in returning to the Moon is recommended to investigate the issue of lunar polar water. The potential benefits of lunar water more than warrant sending either astronauts, robots or both to the Moon before any permanent facility is constructed.

  19. 46 CFR 35.01-25 - Sacrificial anode installations-TB/ALL.

    Science.gov (United States)

    2010-10-01

    ... submitted for approval. The anode should be magnesium free and the silicon content limited to trace amounts... 46 Shipping 1 2010-10-01 2010-10-01 false Sacrificial anode installations-TB/ALL. 35.01-25 Section... Operating Requirements § 35.01-25 Sacrificial anode installations—TB/ALL. (a) The installation of...

  20. Polarized nuclear target based on parahydrogen induced polarization

    Energy Technology Data Exchange (ETDEWEB)

    Budker, D., E-mail: dbudker@gmail.com [Department of Physics, University of California at Berkeley, Berkeley, CA 94720-7300 (United States); Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Ledbetter, M.P. [Department of Physics, University of California at Berkeley, Berkeley, CA 94720-7300 (United States); Appelt, S. [Central Institute for Electronics, Research Center Juelich, D-52425 Juelich (Germany); Bouchard, L.S. [Department of Chemistry and Biochemistry, California NanoSystems Institute, Biomedical Engineering IDP, Jonsson Comprehensive Cancer Center, University of California, Los Angeles, CA 90095 (United States); Wojtsekhowski, B. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States)

    2012-12-01

    We discuss a novel concept of a polarized nuclear target for accelerator fixed-target scattering experiments, which is based on parahydrogen induced polarization (PHIP). One may be able to reach a 33% free-proton polarization in the ethane molecule. The potential advantages of such a target include operation at zero magnetic field, fast ({approx}100Hz) polarization oscillation (akin to polarization reversal), and operation with large intensity of an electron beam. -- Highlights: Black-Right-Pointing-Pointer Novel concept for polarized nuclear targets. Black-Right-Pointing-Pointer The target features fast reversal and operates at near-zero magnetic field. Black-Right-Pointing-Pointer Based on the technique of parahydrogen induced polarization that is revolutionizing NMR and enables NMR/MRI without magnets. Black-Right-Pointing-Pointer Competitive figure-of-merit for polarized targets.

  1. Polarity Specific Suppression Effects of Transcranial Direct Current Stimulation for Tinnitus

    Directory of Open Access Journals (Sweden)

    Kathleen Joos

    2014-01-01

    Full Text Available Tinnitus is the perception of a sound in the absence of an external auditory stimulus and affects 10–15% of the Western population. Previous studies have demonstrated the therapeutic effect of anodal transcranial direct current stimulation (tDCS over the left auditory cortex on tinnitus loudness, but the effect of this presumed excitatory stimulation contradicts with the underlying pathophysiological model of tinnitus. Therefore, we included 175 patients with chronic tinnitus to study polarity specific effects of a single tDCS session over the auditory cortex (39 anodal, 136 cathodal. To assess the effect of treatment, we used the numeric rating scale for tinnitus loudness and annoyance. Statistical analysis demonstrated a significant main effect for tinnitus loudness and annoyance, but for tinnitus annoyance anodal stimulation has a significantly more pronounced effect than cathodal stimulation. We hypothesize that the suppressive effect of tDCS on tinnitus loudness may be attributed to a disrupting effect of ongoing neural hyperactivity, independent of the inhibitory or excitatory effects and that the reduction of annoyance may be induced by influencing adjacent or functionally connected brain areas involved in the tinnitus related distress network. Further research is required to explain why only anodal stimulation has a suppressive effect on tinnitus annoyance.

  2. Global Geospace Science/Polar Plasma Laboratory: POLAR

    Science.gov (United States)

    1996-01-01

    The Global Geospace Science (GGS) Project is discussed as part of the International Solar-Terrestrial Physics (ISTP) Science Initiative. The objectives of Polar Plasma Laboratory (POLAR), one of the two spacecraft to be used by the Project to fill critical gaps in the scientific understanding of solar and plasma physics, are outlined. POLAR Laboratory is described, along with POLAR instrumentation, support subsystems, and orbits. Launch vehicle and injection into orbit are also addressed.

  3. Aerogel and xerogel composites for use as carbon anodes

    Science.gov (United States)

    Cooper, John F.; Tillotson, Thomas M.; Hrubesh, Lawrence W.

    2008-08-12

    Disclosed herein are aerogel and xerogel composite materials suitable for use as anodes in fuel cells and batteries. Precursors to the aerogel and xerogel compounds are infused with inorganic polymeric materials or carbon particles and then gelled. The gels are then pyrolyzed to form composites with internal structural support.

  4. Controlling the Electron Energy Distribution Function Using an Anode

    Science.gov (United States)

    Baalrud, Scott D.; Barnat, Edward V.; Hopkins, Mathew M.

    2014-10-01

    Positively biased electrodes inserted into plasmas influence the electron energy distribution function (EEDF) by providing a sink for low energy electrons that would otherwise be trapped by ion sheaths at the chamber walls. We develop a model for the EEDF in a hot filament generated discharge in the presence of positively biased electrodes of various surface areas, and compare the model results with experimental Langmuir probe measurements and particle-in-cell simulations. In the absence of an anode, the EEDF is characterized by a cool trapped population at energies below the sheath energy, and a comparatively warm tail population associated with the filament primaries. Anodes that are small enough to collect a negligible fraction of the electrons exiting the plasma have little affect on the EEDF, but as the anode area approaches √{me /mi }Aw , where Aw is the chamber wall area, the anode collects most of the electrons leaving the plasma. This drastically reduces the density of the otherwise trapped population, causing an effective heating of the electrons and a corresponding density decrease. A global model is developed based on the EEDF model and current balance, which shows the interconnected nature of the electron temperature, density and the plasma potential. This work was supported by the Office of Fusion Energy Science at the U.S. Department of Energy under Contract DE-AC04-94SL85000, and by the University of Iowa Old Gold Program.

  5. Vanadium-based anode catalysts for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Fu, X.Z.; Luo, J.L.; Chuang, K.T.; Sanger, A.R. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering; Tu, H.Y. [Shanghai Jiao Tong Univ., Shanghai (China). Inst. of Fuel Cell, School of Mechanical Engineering; Yang, Q.M. [Vale-Inco Ltd., Mississauga, ON (Canada)

    2010-07-01

    Solid oxide fuel cells (SOFCs) are considered as important electricity generators because they convert carbon-containing fuels from fossil sources to electricity without generating pollution. Syngas is more available and less expensive than highly purified hydrogen. However, when exposed to syngas at SOFC operating temperatures, conventional nickel anode catalysts result in carbon deposition, which compromises their performance. Syngas derived from conversion of hydrocarbon or coal resources normally also contain hydrogen sulphide, which poisons nickel anode catalysts. In order to use syngas, it is necessary to either stringently clean the feed, which is a costly process, or develop catalysts that can operate using impure feed and are not prone to carbon deposition. This paper discussed the development of a vanadium-based material (VOx) which is an active anode catalyst for SOFCs, that is not prone to coking and is sulfur resistant. The VOx material was obtained by decomposition and reduction of ammonium metavanadate (NH{sub 4}VO{sub 3}) at high temperature. Coking and sulfur resistance of as-prepared VOx and nickel were compared in hydrogen sulphide-containing syngas environments at 900 degrees Celsius. It was concluded that the VOx material had much higher coking resistance and sulfur tolerance than nickel. The SOFC with VOx anode catalyst demonstrated excellent performance using hydrogen sulphide-containing syngas as fuel. 3 refs.

  6. Use of tungsten anodes in microgap gas chambers

    International Nuclear Information System (INIS)

    In a continuation of the authors' earlier tests, tungsten has been used for anode strips in the fabrication of microgap gas chambers (MGCs) in an attempt to find a metallization suitable for gas avalanche microdetectors (MSGCs or MGCs) that will be both highly robust against sparking and yet have sufficiently low resistivity to permit use of detectors of relatively larger sizes. MGCs having about 5,500 and 7,500 angstrom thick tungsten anodes were fabricated using a sputtering technique, and the sheet resistances for these layers were measured as 0.42 and 0.27 Ω/□, respectively. The detectors were subjected to sparks having a range of energies, and the damage to the anode strips was assessed using optical and scanning electron microscope (SEM) photographs, and by measuring leakage current before and after sparking. In this paper, the spark damage test results of tungsten anodes in MGCs are reported, and an interpretation is made regarding the viability of use of this metal for larger sizes of detectors

  7. Nanocomposite anode materials for sodium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Manthiram, Arumugam; Kim Il, Tae; Allcorn, Eric

    2016-06-14

    The disclosure relates to an anode material for a sodium-ion battery having the general formula AO.sub.x--C or AC.sub.x--C, where A is aluminum (Al), magnesium (Mg), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), zirconium (Zr), molybdenum (Mo), tungsten (W), niobium (Nb), tantalum (Ta), silicon (Si), or any combinations thereof. The anode material also contains an electrochemically active nanoparticles within the matrix. The nanoparticle may react with sodium ion (Na.sup.+) when placed in the anode of a sodium-ion battery. In more specific embodiments, the anode material may have the general formula M.sub.ySb-M'O.sub.x--C, Sb-MO.sub.x--C, M.sub.ySn-M'C.sub.x--C, or Sn-MC.sub.x--C. The disclosure also relates to rechargeable sodium-ion batteries containing these materials and methods of making these materials.

  8. A multi-anode photomultiplier with position sensitivity

    International Nuclear Information System (INIS)

    We have measured the properties of a specially developed photomultiplier with proximity dynodes and 10 wire anodes. This design allows us to determine the position of emission of the photoelectrons from the cathode with an accuracy of 1.3 mm fwhm. This tube is also extremely fast due to the short transit time and the geometry of its dynodes. (orig.)

  9. Measurement of focal spot size in microfocus rod anode tubes

    International Nuclear Information System (INIS)

    This paper explains how focal spot size is measured in common microfocus rod anode tubes. Differences in beam geometry, beam angle and target arrangement make it necessary to define the measurement setup precisely. The author presents a measurement method using examples for explanation. The paper contains PowerPoint slides.

  10. High Performance SLED Fabricated by Pulsed Anodic Oxidation

    Institute of Scientific and Technical Information of China (English)

    GAO Xin; BO Bao-xue; ZHANG Jing; LI Hui; QU Yi

    2009-01-01

    InGaAs/AlGaAs MQW superluminescent LED (SLED) is fabricated by using pulsed anodic oxidation and molecular beam epitaxy (MBE). The power and spectral output characteristics of three kinds of device structures are investigated. An output power above 10mW with FWHM of 18nm is demonstrated at a current of 150mA.

  11. Effect of surface anodization on stability of orthodontic microimplant

    Science.gov (United States)

    Karmarker, Sanket; Yu, Wonjae

    2012-01-01

    Objective To determine the effect of surface anodization on the interfacial strength between an orthodontic microimplant (MI) and the rabbit tibial bone, particularly in the initial phase after placement. Methods A total of 36 MIs were driven into the tibias of 3 mature rabbits by using the self-drilling method and then removed after 6 weeks. Half the MIs were as-machined (n = 18; machined group), while the remaining had anodized surfaces (n = 18; anodized group). The peak insertion torque (PIT) and the peak removal torque (PRT) values were measured for the 2 groups of MIs. These values were then used to calculate the interfacial shear strength between the MI and cortical bone. Results There were no statistical differences in terms of PIT between the 2 groups. However, mean PRT was significantly greater for the anodized implants (3.79 ± 1.39 Ncm) than for the machined ones (2.05 ± 1.07 Ncm) (p orthodontic MIs may enhance their early-phase retention capability, thereby ensuring a more reliable source of absolute anchorage. PMID:23112925

  12. Fabrication of Porous Anodic Alumina with Ultrasmall Nanopores

    Directory of Open Access Journals (Sweden)

    Ding GuQiao

    2010-01-01

    Full Text Available Abstract Anodization of Al foil under low voltages of 1–10 V was conducted to obtain porous anodic aluminas (PAAs with ultrasmall nanopores. Regular nanopore arrays with pore diameter 6–10 nm were realized in four different electrolytes under 0–30°C according to the AFM, FESEM, TEM images and current evolution curves. It is found that the pore diameter and interpore distance, as well as the barrier layer thickness, are not sensitive to the applied potentials and electrolytes, which is totally different from the rules of general PAA fabrication. The brand-new formation mechanism has been revealed by the AFM study on the samples anodized for very short durations of 2–60 s. It is discovered for the first time that the regular nanoparticles come into being under 1–10 V at the beginning of the anodization and then serve as a template layer dominating the formation of ultrasmall nanopores. Under higher potentials from 10 to 40 V, the surface nanoparticles will be less and less and nanopores transform into general PAAs.

  13. A review of liquid metal anode solid oxide fuel cells

    Directory of Open Access Journals (Sweden)

    ALIYA TOLEUOVA

    2013-06-01

    Full Text Available This review discusses recent advances in a solid oxide fuel cell (SOFC variant that uses liquid metal electrodes (anodes with the advantage of greater fuel tolerance and the ability to operate on solid fuel. Key features of the approach are discussed along with the technological and research challenges that need to be overcome for scale-up and commercialisation.

  14. Current collection by high voltage anodes in near ionospheric conditions

    Science.gov (United States)

    Antoniades, John A.; Greaves, Rod G.; Boyd, D. A.; Ellis, R.

    1990-01-01

    The authors experimentally identified three distinct regimes with large differences in current collection in the presence of neutrals and weak magnetic fields. In magnetic field/anode voltage space the three regions are separated by very sharp transition boundaries. The authors performed a series of laboratory experiments to study the dependence of the region boundaries on several parameters, such as the ambient neutral density, plasma density, magnetic field strength, applied anode voltage, voltage pulsewidth, chamber material, chamber size and anode radius. The three observed regimes are: classical magnetic field limited collection; stable medium current toroidal discharge; and large scale, high current space glow discharge. There is as much as several orders of magnitude of difference in the amount of collected current upon any boundary crossing, particularly if one enters the space glow regime. They measured some of the properties of the plasma generated by the breakdown that is present in regimes II and III in the vicinity of the anode including the sheath modified electrostatic potential, I-V characteristics at high voltage as well as the local plasma density.

  15. Spark protection layers for CMOS pixel anode chips in MPGDs

    NARCIS (Netherlands)

    Bilevych, Y.; Blanco Carballo, V.M.; Chefdeville, M.A.; Colas, P.; Delagnes, E.; Fransen, M.; Graaff, van der H.; Koppert, W.J.C.; Melai, J.; Salm, C.; Schmitz, J.; Timmermans, J.; Wyrsch, N.

    2011-01-01

    In this work we have investigated the functioning of high resistivity amorphous silicon and silicon-rich nitride layers as a protection against discharges in Micro-Patterned Gaseous Detectors (MPGDs).When the anode is protected by a high resistivity layer, discharge signals are limited in charge. A

  16. Prelithiated Silicon Nanowires as an Anode for Lithium Ion Batteries

    KAUST Repository

    Liu, Nian

    2011-08-23

    Silicon is one of the most promising anode materials for the next-generation high-energy lithium ion battery (LIB), while sulfur and some other lithium-free materials have recently shown high promise as cathode materials. To make a full battery out of them, either the cathode or the anode needs to be prelithiated. Here, we present a method for prelithiating a silicon nanowire (SiNW) anode by a facile self-discharge mechanism. Through a time dependence study, we found that 20 min of prelithiation loads ∼50% of the full capacity into the SiNWs. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies show that the nanostructure of SiNWs is maintained after prelithiation. We constructed a full battery using our prelithiated SiNW anode with a sulfur cathode. Our work provides a protocol for pairing lithium-free electrodes to make the next-generation high-energy LIB. © 2011 American Chemical Society.

  17. Optimal Set Anode Potentials Vary in Bioelectrochemical Systems

    KAUST Repository

    Wagner, Rachel C.

    2010-08-15

    In bioelectrochemical systems (BESs), the anode potential can be set to a fixed voltage using a potentiostat, but there is no accepted method for defining an optimal potential. Microbes can theoretically gain more energy by reducing a terminal electron acceptor with a more positive potential, for example oxygen compared to nitrate. Therefore, more positive anode potentials should allow microbes to gain more energy per electron transferred than a lower potential, but this can only occur if the microbe has metabolic pathways capable of capturing the available energy. Our review of the literature shows that there is a general trend of improved performance using more positive potentials, but there are several notable cases where biofilm growth and current generation improved or only occurred at more negative potentials. This suggests that even with diverse microbial communities, it is primarily the potential of the terminal respiratory proteins used by certain exoelectrogenic bacteria, and to a lesser extent the anode potential, that determines the optimal growth conditions in the reactor. Our analysis suggests that additional bioelectrochemical investigations of both pure and mixed cultures, over a wide range of potentials, are needed to better understand how to set and evaluate optimal anode potentials for improving BES performance. © 2010 American Chemical Society.

  18. Detailed characterization of anode-supported SOFCs by impedance spectroscopy

    DEFF Research Database (Denmark)

    Barfod, R.; Mogensen, Mogens Bjerg; Klemensø, Trine;

    2007-01-01

    Anode-supported thin electrolyte cells are studied by electrochemical impedance spectroscopy (EIS). The aim is to describe how the losses of this type of cells are distributed at low current density (around open-circuit voltage) as a function of temperature. An equivalent circuit consisting...

  19. Probing anode degradation in automotive Li-ion batteries

    Science.gov (United States)

    Kwon, Ou Jung

    The lithium-ion battery is drawing attention as a power source for future clean and fuel-efficient vehicles. Although the Li-ion battery presently shows best performance for energy density and power density compared to other rechargeable batteries, some degradation problems still remain as key challenges for long-term durability in automotive applications. Among those problems, Li deposition is well known for causing permanent capacity loss. Fundamental mechanisms of Li deposition in the carbon anode are, however, not fully understood, especially at subzero temperature and/or under high rate charge. This dissertation introduces comprehensive study of Li deposition using automotive 18650 Li-ion cells. The mechanism and relevant diagnostic methods as well as preventive charging protocol are discussed. In part one, a new diagnostic tool is introduced utilizing 3-electrode cell system, which measures thermodynamic and kinetic parameters of cathode and anode, respectively, as a function of temperature and SOC (state of charge): open circuit potential (OCP); Li diffusion coefficient in active particles; and internal resistance. These data are employed to understand electrochemical reaction and its thermal interaction under charging conditions that result in Li deposition. Part two provides a threshold parameter for the onset of Li deposition, which is not commonly used anode potential but charge capacity, or more specifically the amount of Li+ ions participating in intercalation reaction without Li deposition at given charging circumstances. This is called the critical charge capacity in this thesis, beyond which capacity loss at normal operating condition is observed, which becomes more serious as temperature is lowered and/or charge C-rate increases. Based on these experimental results, the mechanism of Li deposition is proposed as the concept of anode particle surface saturation, meaning that once the anode particle surface is saturated with Li in any charging

  20. Analysis of polarization methods for elimination of power overshoot in microbial fuel cells

    KAUST Repository

    Watson, Valerie J.

    2011-01-01

    Polarization curves from microbial fuel cells (MFCs) often show an unexpectedly large drop in voltage with increased current densities, leading to a phenomenon in the power density curve referred to as "power overshoot". Linear sweep voltammetry (LSV, 1 mV s- 1) and variable external resistances (at fixed intervals of 20 min) over a single fed-batch cycle in an MFC both resulted in power overshoot in power density curves due to anode potentials. Increasing the anode enrichment time from 30 days to 100 days did not eliminate overshoot, suggesting that insufficient enrichment of the anode biofilm was not the primary cause. Running the reactor at a fixed resistance for a full fed-batch cycle (~ 1 to 2 days), however, completely eliminated the overshoot in the power density curve. These results show that long times at a fixed resistance are needed to stabilize current generation by bacteria in MFCs, and that even relatively slow LSV scan rates and long times between switching circuit loads during a fed-batch cycle may produce inaccurate polarization and power density results for these biological systems. © 2010 Elsevier B.V. All rights reserved.

  1. LONGSHOT operation with anode-side magnetic field coils

    International Nuclear Information System (INIS)

    The LONGSHOT experiment uses a radially magnetically-insulated ion diode to generate an annular ion beam for ion-ring formation studies. The insulating magnetic field had been produced by coils on the cathode side of the diode gap, and flux-shaping conducting surfaces on the anode side. In this configuration, the about 100 keV, about 50 A/cm2, 400 nsec proton beam showed at least 2.50 half-angle divergence 15 cm from the gap, after traversing the cross-magnetic field region of the return flux of the insulating field coils. We have recently eliminated this return flux by relocating the coils to the anode side of the gap so that the return flux is behind the anode and out of the beam path. With proper location and configuration of coils and anode surface and using a flux-excluding cathode tip we now get the same or greater ion current output, but the divergence 15 cm from the gap is reduced to 0 half-angle. Divergence is measured by apertures followed by damage targets. This improvement is presumably due to elimination of all magnetic field downstream of the gap. It is significant that the ion optics are not degraded by using a flux-excluding cathode, which gives highly distorted, curved applied magnetic field lines at the cathode. This gap, in both original and new configurations, gives ion current densities a factor of 30 or more above Child-Langmuir flow for the geometric gap, so the virtual cathode electron flow must be located very near the anode surface, and the diamagnetism of the electron flow must modify the magnetic field in such a way as to produce a flat effective cathode. Experimental results from the present diode, and also preliminary results from LONGSHOT II, a scaled-up version of this new configuration, are presented

  2. Silicon Based Anodes for Li-Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiguang; Wang, Wei; Xiao, Jie; Xu, Wu; Graff, Gordon L.; Yang, Zhenguo; Choi, Daiwon; Li, Xiaolin; Wang, Deyu; Liu, Jun

    2012-06-15

    Silicon is environmentally benign and ubiquitous. Because of its high specific capacity, it is considered one of the most promising candidates to replace the conventional graphite negative electrode used in today's Li ion batteries. Silicon has a theoretical specific capacity of nearly 4200 mAh/g (Li21Si5), which is 10 times larger than the specific capacity of graphite (LiC6, 372 mAh/g). However, the high capacity of silicon is associated with huge volume changes (more than 300 percent) when alloyed with lithium, which can cause severe cracking and pulverization of the electrode and lead to significant capacity loss. Significant scientific research has been conducted to circumvent the deterioration of silicon based anode materials during cycling. Various strategies, such as reduction of particle size, generation of active/inactive composites, fabrication of silicon based thin films, use of alternative binders, and the synthesis of 1-D silicon nanostructures have been implemented by a number of research groups. Fundamental mechanistic research has also been performed to better understand the electrochemical lithiation and delithiation process during cycling in terms of crystal structure, phase transitions, morphological changes, and reaction kinetics. Although efforts to date have not attained a commercially viable Si anode, further development is expected to produce anodes with three to five times the capacity of graphite. In this chapter, an overview of research on silicon based anodes used for lithium-ion battery applications will be presented. The overview covers electrochemical alloying of the silicon with lithium, mechanisms responsible for capacity fade, and methodologies adapted to overcome capacity degradation observed during cycling. The recent development of silicon nanowires and nanoparticles with significantly improved electrochemical performance will also be discussed relative to the mechanistic understanding. Finally, future directions on the

  3. Optimization and Domestic Sourcing of Lithium Ion Battery Anode Materials

    Energy Technology Data Exchange (ETDEWEB)

    Wood, III, D. L.; Yoon, S. [A123 Systems, Inc.

    2012-10-25

    The purpose of this Cooperative Research and Development Agreement (CRADA) between ORNL and A123Systems, Inc. was to develop a low-temperature heat treatment process for natural graphite based anode materials for high-capacity and long-cycle-life lithium ion batteries. Three major problems currently plague state-of-the-art lithium ion battery anode materials. The first is the cost of the artificial graphite, which is heat-treated well in excess of 2000°C. Because of this high-temperature heat treatment, the anode active material significantly contributes to the cost of a lithium ion battery. The second problem is the limited specific capacity of state-of-the-art anodes based on artificial graphites, which is only about 200-350 mAh/g. This value needs to be increased to achieve high energy density when used with the low cell-voltage nanoparticle LiFePO4 cathode. Thirdly, the rate capability under cycling conditions of natural graphite based materials must be improved to match that of the nanoparticle LiFePO4. Natural graphite materials contain inherent crystallinity and lithium intercalation activity. They hold particular appeal, as they offer huge potential for industrial energy savings with the energy costs essentially subsidized by geological processes. Natural graphites have been heat-treated to a substantially lower temperature (as low as 1000-1500°C) and used as anode active materials to address the problems described above. Finally, corresponding graphitization and post-treatment processes were developed that are amenable to scaling to automotive quantities.

  4. Defining the Polar Field Reversal

    Science.gov (United States)

    Upton, Lisa; Hathaway, David H.

    2013-01-01

    The polar fields on the Sun are directly related to solar cycle variability. Recently there has been interest in studying an important characteristic of the polar fields: the timing of the polar field reversals. However this characteristic has been poorly defined, mostly due to the limitations of early observations. In the past, the reversals have been calculated by averaging the flux above some latitude (i.e. 55deg or 75deg). Alternatively, the reversal could be defined by the time in which the previous polarity is completely canceled and replaced by the new polarity at 90de, precisely at the pole. We will use a surface flux transport model to illustrate the differences in the timing of the polar field reversal based on each of these definitions and propose standardization in the definition of the polar field reversal. The ability to predict the timing of the polar field reversal using a surface flux transport model will also be discussed.

  5. POLARIZED PROTON COLLISIONS AT RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    BAI, M.; AHRENS, L.; ALEKSEEV, I.G.; ALESSI, J.; ET AL.

    2005-05-16

    The Relativistic Heavy Ion Collider provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC. In 2002, polarized proton beams were first accelerated to 100 GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. Optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limited conditions are reported.

  6. Anode purge strategy optimization of the polymer electrode membrane fuel cell system under the dead-end anode operation

    Science.gov (United States)

    Hu, Zhe; Yu, Yi; Wang, Guangjin; Chen, Xuesong; Chen, Pei; Chen, Jun; Zhou, Su

    2016-07-01

    Dead-ended anode (DEA) mode is commonly applied in fuel cell vehicles for the hydrogen purge at the anode side, to reduce fuel waste and enhance fuel cell efficiency. Anode purge is necessary and is definitely important with respect to removing liquid water and accumulated nitrogen in the gas diffusion layer and the flow field of the DEA-mode fuel cell. In this paper, the effect of different purge strategies on the stack performance and system efficiency is investigated experimentally using fast data acquisition and advanced tools, such as the fast cell voltage measurement (CVM) system and the mass spectrum. From the fast data acquisition, the voltage stability, liquid water and nitrogen concentration measurement in the anode exhaust are compared and analyzed under different purge strategy designs and using different purge valves. The results show that under the optimal purge strategy, the DEA fuel cell stack can achieve the desired stability and system efficiency based on the analysis of the cell voltage and purge volume. Moreover, the diameter of the purge valve has a great impact on the voltage stability because a diameter change will result in a different pressure drop and purge volume when the purge valve is open.

  7. Polarization of a Helium-Neon Laser.

    Science.gov (United States)

    Jones, Edwin R.

    1996-01-01

    Describes an experiment that involves measuring the intensity of laser light passed by a linear polarizer. Discusses polarization effects, orthogonal polarizations, instrumentation, and further experiments. (JRH)

  8. Pilot study of mechanism of property-modified anode in aluminum electrolysis

    Institute of Scientific and Technical Information of China (English)

    肖劲; 杨建红; 胡国荣; 赖延清; 王先黔; 刘业翔

    2003-01-01

    On the basis of serial laboratory research and industrial test, the mechanism of saving energy and reducing carbon consumption of property-modified prebaked anode in aluminum electrolysis was discussed. It is considered that the anodic over voltage is affected by the concentration of carbon monoxide surrounding anode. The property-modified prebaked anode can restrain the production of carbon monoxide. The reason of reducing carbon consumption was also analyzed, the result shows that besides physical action, chemical action also exists in the process where additives change the reaction rate of anodes.

  9. Comparison of sulfuric and oxalic acid anodizing for preparation of thermal control coatings for spacecraft

    Science.gov (United States)

    Le, Huong G.; Watcher, John M.; Smith, Charles A.

    1988-01-01

    The development of thermal control surfaces, which maintain stable solar absorptivity and infrared emissivity over long periods, is challenging due to severe conditions in low-Earth orbit (LEO). Some candidate coatings are second-surface silver-coated Teflon; second-surface, silvered optical solar reflectors made of glass or quartz; and anodized aluminum. Sulfuric acid anodized and oxalic acid anodized aluminum was evaluated under simulated LEO conditions. Oxalic acid anodizing shows promise of greater stability in LEO over long missions, such as the 30 years planned for the Space Station. However, sulfuric acid anodizing shows lower solar absorptivity.

  10. The effect of compression on natural graphite anode performance and matrix conductivity

    OpenAIRE

    Striebel, K.A.; A. Sierra; Shim, J.; Wang, C.-W.; Sastry, A.M.

    2004-01-01

    Anodes for lithium-ion cells were constructed from three types of natural graphite, two coated spherical and one flaky. Anode samples were compressed from 0 to 300 kg/cm2 and studied in half-cells to study the relations between anode density, SEI formation and anode cyclability. The C/25 formation of the SEI layer was found to depend on the nature of the graphite and the anode density. Compression of the uncoated graphite lead to an increased conductivity, but only slight improvements i...

  11. Galactic Diffuse Polarized Emission

    Indian Academy of Sciences (India)

    Ettore Carretti

    2011-12-01

    Diffuse polarized emission by synchrotron is a key tool to investigate magnetic fields in the Milky Way, particularly the ordered component of the large scale structure. Key observables are the synchrotron emission itself and the RM is by Faraday rotation. In this paper the main properties of the radio polarized diffuse emission and its use to investigate magnetic fields will be reviewed along with our current understanding of the galactic magnetic field and the data sets available. We will then focus on the future perspective discussing RM-synthesis – the new powerful instrument devised to unlock the information encoded in such an emission – and the surveys currently in progress like S-PASS and GMIMS.

  12. Polarized electrogowdy spacetimes censored

    Energy Technology Data Exchange (ETDEWEB)

    Nungesser, Ernesto, E-mail: ernesto.nungesser@aei.mpg.d [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1, 14476 Potsdam (Germany)

    2010-05-01

    A sketch of the proof of strong cosmic censorship is presented for a class of solutions of the Einstein-Maxwell equations, those with polarized Gowdy symmetry. A key element of the argument is the observation that by means of a suitable choice of variables the central equations in this problem can be written in a form where they are identical to the central equations for general (i.e. non-polarized) vacuum Gowdy spacetimes. Using this it is seen that the results of Ringstroem on strong cosmic censorship in the vacuum case have implications for the Einstein-Maxwell case. Working out the geometrical meaning of these analytical results leads to the main conclusion.

  13. Polarization Diffusion from Spacetime Uncertainty

    CERN Document Server

    Contaldi, Carlo; Philpott, Lydia

    2010-01-01

    A model of Lorentz invariant random fluctuations in photon polarization is presented. The effects are frequency dependent and affect the polarization of photons as they propagate through space. We test for this effect by confronting the model with the latest measurements of polarization of Cosmic Microwave Background (CMB) photons.

  14. Polar Warming: An Opportune Inconvenience

    NARCIS (Netherlands)

    R. Lefeber

    2012-01-01

    The inaccessibility of the Polar Regions explains the relative pristine state of these regions to date. The human presence in these regions is presently limited by the extreme climatological circumstances. This will change as a result of polar warming. The ecological boundaries of the Polar Regions

  15. Polarization induced doped transistor

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Huili (Grace); Jena, Debdeep; Nomoto, Kazuki; Song, Bo; Zhu, Mingda; Hu, Zongyang

    2016-06-07

    A nitride-based field effect transistor (FET) comprises a compositionally graded and polarization induced doped p-layer underlying at least one gate contact and a compositionally graded and doped n-channel underlying a source contact. The n-channel is converted from the p-layer to the n-channel by ion implantation, a buffer underlies the doped p-layer and the n-channel, and a drain underlies the buffer.

  16. Transverse polarization in ; production

    Indian Academy of Sciences (India)

    Saurabh D Rindani

    2007-11-01

    With the use of transverse polarization (TP), a CP-odd and T-odd observable can be constructed when the final-state particles are self-conjugate. In the case of production, this observable can be used to probe a certain effective four-point + - CP-violating coupling, not accessible without TP. Effective CP-violating coupling does not contribute to this observable. A similar observable in production can be used to probe + - four-point couplings.

  17. Quark transverse polarization

    International Nuclear Information System (INIS)

    The distribution of h1(x) of quark transverse polarization can be measured by Deep Inelastic Scattering using Collins effect as quark polarimeter. We propose to calibrate this polarimeter in e+e- → 2 jets. We give an explanation of single spin asymmetries in inclusive meson production based on the Collins effect. We propose a proportionality between the electric dipole moment of the nucleon on its tensor charge. (authors)

  18. Performance of a plasma opening switch in positive polarity on Gamble I using flashboard plasma sources

    International Nuclear Information System (INIS)

    The successful development of the Plasma Opening Switch (POS) for inductive storage applications has been largely confined to negative polarity operation. Some models of POS behavior suggest that this is because in a positive polarity coaxial configuration, the weaker magnetic field at the cathode position retards the switch opening process. This article describes experiments in which both conductor radii in the POS region were significantly reduced. Anode- and cathode-side current monitors indicate that voltages greater than open-circuit are generated at the POS position, but there is a significant amount of electron flow out of the POS, depending upon load impedance. Flow impedance analysis indicates that a relatively small gap appears in the POS plasma after switch opening. Switch performance is also compared between flashboard and carbon gun plasma sources, with the latter operated both in positive and negative polarity

  19. PEPPo: Using a Polarized Electron Beam to Produce Polarized Positrons

    Energy Technology Data Exchange (ETDEWEB)

    Adeyemi, Adeleke H. [Hampton Univ., Hampton, VA (United States); et al.

    2015-09-01

    Polarized positron beams have been identified as either an essential or a significant ingredient for the experimental program of both the present and next generation of lepton accelerators (JLab, Super KEK B, ILC, CLIC). An experiment demonstrating a new method for producing polarized positrons has been performed at the Continuous Electron Beam Accelerator Facility at Jefferson Lab. The PEPPo (Polarized Electrons for Polarized Positrons) concept relies on the production of polarized e⁻/e⁺ pairs from the bremsstrahlung radiation of a longitudinally polarized electron beam interacting within a high-Z conversion target. PEPPo demonstrated the effective transfer of spin-polarization of an 8.2 MeV/c polarized (P~85%) electron beam to positrons produced in varying thickness tungsten production targets, and collected and measured in the range of 3.1 to 6.2 MeV/c. In comparison to other methods this technique reveals a new pathway for producing either high-energy or thermal polarized positron beams using a relatively low polarized electron beam energy (~10MeV) .This presentation will describe the PEPPo concept, the motivations of the experiment and high positron polarization achieved.

  20. Polar Business Design

    Directory of Open Access Journals (Sweden)

    Sébastien Caisse

    2014-02-01

    Full Text Available Polar business design aims to enable entrepreneurs, managers, consultants, researchers, and business students to better tackle model-based analysis, creation, and transformation of businesses, ventures, and, more generically, collective endeavors of any size and purpose. It is based on a systems-thinking approach that builds on a few interrelated core concepts to create holistic visual frameworks. These core concepts act as poles linked by meaningful dyads, flows, and faces arranged in geometric shapes. The article presents two such polar frameworks as key findings in an ongoing analytic autoethnography: the three-pole Value−Activity−Stakeholder (VAS triquetra and the four-pole Offer−Creation−Character−Stakeholder (OCCS tetrahedron. The VAS triquetra is a more aggregated model of collective endeavors. The OCCS tetrahedron makes a trade-off between a steeper learning curve and deeper, richer representation potential. This article discusses how to use these two frameworks as well as their limits, and explores the potential that polar business design offers for future research.

  1. Anode layer in a high-current arc in atmospheric pressure nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Nemchinsky, Valerian A [ESAB Welding and Cutting Products and Francis Marion University, Florence, SC 29501 (United States)

    2005-11-21

    An anode layer in a high-current atmospheric nitrogen arc was modelled. Calculations were made in a one-dimensional approximation at current densities in the range 500-3000 A cm{sup -2}. Two-temperature approximation was used. We calculated the distributions of both electron and heavy particle temperatures, the concentrations of charged and neutral particles and the electric field inside the anode layer. It was shown that for the conditions that exist in the anode layer of a high-current atmospheric pressure arc in nitrogen (a) the concentration of the molecular ions is negligible and (b) the concentration of atoms exceeds the concentration of molecules everywhere in the anode layer except in a narrow region close to the anode. Calculation showed that the electric field decreases towards the anode, and then close to the anode it rises again. Contrary to the situation in argon, the present calculations showed that in nitrogen the electric field in the anode layer is always accelerating. However, the average electric field in the anode layer is weaker than in the adjacent arc column (the so-called negative anode layer voltage). The voltage drop in the Langmuir sheath is also negative. It is shown that the main difference in anode layer voltages between an arc in nitrogen and an arc in argon is due to the high reactive thermal conductivity in nitrogen.

  2. Corrosion of cermet anodes during low temperature electrolysis of alumina. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kozarek, R.L.; Ray, S.P.; Dawless, R.K.; LaCamera, A.F.

    1997-09-26

    Successful development of inert anodes to replace carbon anodes in Hall cells has the potential benefits of lower energy consumption,lower operating costs, and reduced CO{sub 2} and CO emissions. Using inert anodes at reduced current density and reduced operating temperature (800 C) has potential for decreasing the corrosion rate of inert anodes. It may also permit the use of new materials for containment and insulation. This report describes the fabrication characteristics and the corrosion performance of 5324-17% Cu Cermet anodes in 100 hour tests. Although some good results were achieved, the corrosion rate at low temperature (800 C) is varied and not significantly lower than typical results at high temperature ({approximately} 960 C). This report also describes several attempts at 200 hour tests, with one anode achieving 177 hours of continuous operation and another achieving a total of 235 hours but requiring three separate tests of the same anode. The longest run did show a lower wear rate in the last test; but a high resistance layer developed on the anode surface and forced an unacceptably low current density. It is recommended that intermediate temperatures be explored as a more optimal environment for inert anodes. Other electrolyte chemistries and anode compositions (especially high conductivity anodes) should be considered to alleviate problems associated with lower temperature operation.

  3. Effect of electromagnetic force and anode gas on electrolyte flow in aluminum electrolysis cell

    Institute of Scientific and Technical Information of China (English)

    ZHOU Nai-jun; XIA Xiao-xia; BAO Sheng-zhong

    2006-01-01

    Based on the commercial computational fluid dynamics software CFX-4.3, electrolyte flow fields in a 156 kA pre-baked anode aluminum electrolysis cell were investigated in three different cases where the electrolyte melt was driven by different kinds of force, i.e. electromagnetic force only, the anode gas drag force only and both of the former two forces. The results show that when electromagnetic force was introduced only, most of the electrolyte moves horizontally; when anode gas drag force was introduced only, the electrolyte flows mainly around each anode with small circulation; when electromagnetic force and anode gas drag force were both introduced together, the structure of the electrolyte flow fields and the velocity of electrolyte are similar to that of the case where only anode gas drag force is used. The electrolyte flow fields are mainly determined by the anode gas drag force.

  4. Luminescence properties of oxide films formed by anodization of aluminum in 12-tungstophosphoric acid

    International Nuclear Information System (INIS)

    In this paper, we have investigated luminescence properties of oxide films formed by anodization of aluminum in 12-tungstophosphoric acid. For the first time we have measured weak luminescence during anodization of aluminum in this electrolyte (so-called galvanoluminescence GL) and showed that there are wide GL bands in the visible region of the spectrum and observed two dominant spectral peaks. The first one is at about 425 nm, and the second one shifts with anodization voltage. As the anodization voltage approaches the breakdown voltage, a large number of sparks appear superimposed on the anodic GL. Several intensive band peaks were observed under breakdown caused by electron transitions in W, P, Al, O, H atoms. Furthermore, photoluminescence (PL) of anodic oxide films and anodic-spark formed oxide coatings were performed. In both cases wide PL bands in the range from 320 nm to 600 nm were observed.

  5. Corrosion and Discharge Behaviors of Mg-Al-Zn and Mg-Al-Zn-In Alloys as Anode Materials

    Directory of Open Access Journals (Sweden)

    Jiarun Li

    2016-03-01

    Full Text Available The Mg-6%Al-3%Zn and Mg-6%Al-3%Zn-(1%, 1.5%, 2%In alloys were prepared by melting and casting. Their microstructures were investigated via metallographic and energy-dispersive X-ray spectroscopy (EDS analysis. Moreover, hydrogen evolution and electrochemical tests were carried out in 3.5 wt% NaCl solution aiming at identifying their corrosion mechanisms and discharge behaviors. The results suggested that indium exerts an improvement on both the corrosion rate and the discharge activity of Mg-Al-Zn alloy via the effects of grain refining, β-Mg17Al12 precipitation, dissolving-reprecipitation, and self-peeling. The Mg-6%Al-3%Zn-1.5%In alloy with the highest corrosion rate at free corrosion potential did not perform desirable discharge activity indicating that the barrier effect caused by the β-Mg17Al12 phase would have been enhanced under the conditions of anodic polarization. The Mg-6%Al-3%Zn-1.0%In alloy with a relative low corrosion rate and a high discharge activity is a promising anode material for both cathodic protection and chemical power source applications.

  6. Electrochemical Impedance Spectroscopy study in micro-grain structured amorphous silicon anodes for lithium-ion batteries

    Science.gov (United States)

    Paloukis, Fotis; Elmasides, Costas; Farmakis, Filippos; Selinis, Petros; Neophytides, Stylianos G.; Georgoulas, Nikolaos

    2016-11-01

    In this paper, a study of the lithiation mechanism of micro-grain structured silicon anode is presented. Micro-grain amorphous silicon was deposited on special copper foil and it is shown that after several decades of galvanostatic cycles, it preserves its granular nature with minor degradation. In order to shed light on the lithiation mechanisms of the micro-grain silicon, Electrochemical Impedance Spectroscopy (EIS) was conducted on silicon half-cells at various State-of-Charge (SoC) and various discharging current values and the Solid-Electrolyte Interphase (SEI) RSEI and polarization resistance Rpol were determined. Results reveal that Rpol highly increases for cell voltages lower than 0.2 V and it strongly depends on the discharging C-rate. From X-ray Photoelectron Spectroscopy (XPS) measurements combined with surface sputtering, the existence of a LixSiyOz interlayer between SEI and silicon is confirmed, which is believed to play an important role to the lithium kinetics. Finally, combining our results, a lithiation mechanism of the micro-grain silicon anode is proposed.

  7. Modeling of the anode surface deformation in high-current vacuum arcs with AMF contacts

    Science.gov (United States)

    Huang, Xiaolong; Wang, Lijun; Deng, Jie; Jia, Shenli; Qin, Kang; Shi, Zongqian

    2016-02-01

    A high-current vacuum arc subjected to an axial magnetic field is maintained in a diffuse status. With an increase in arc current, the energy carried by the arc column to the anode becomes larger and finally leads to the anode temperature exceeding the melting point of the anode material. When the anode melting pool is formed, and the rotational plasma of the arc column delivers its momentum to the melting pool, the anode melting pool starts to rotate and also flow outwards along the radial direction, which has been photographed by some researchers using high-speed cameras. In this paper, the anode temperature and melting status is calculated using the melting and solidification model. The swirl flow of the anode melting pool and deformation of the anode is calculated using the magneto-hydrodynamic (MHD) model with the volume of fraction (VOF) method. All the models are transient 2D axial-rotational symmetric models. The influence of the impaction force of the arc plasma, electromagnetic force, viscosity force, and surface tension of the liquid metal are all considered in the model. The heat flux density injected into the anode and the arc pressure are obtained from the 3D numerical simulation of the high-current vacuum arc using the MHD model, which gives more realistic parameters for the anode simulation. Simulation results show that the depth of the anode melting pool increases with an increase in the arc current. Some droplets sputter out from the anode surface, which is caused by the inertial centrifugal force of the rotational melting pool and strong plasma pressure. Compared with the previous anode melting model without consideration of anode deformation, when the deformation and swirl flow of the anode melting pool are considered, the anode temperature is relatively lower, and just a little more than the melting point of Cu. This is because of liquid droplets sputtering out of the anode surface taking much of the energy away from the anode surface. The

  8. Polarization: A must for fusion

    Directory of Open Access Journals (Sweden)

    Didelez J.-P.

    2013-11-01

    Full Text Available The complete polarization of DT fuel would increase the fusion reactivity by 50% in magnetic as well as in inertial confinements. The persistence of polarization in a fusion process could be tested, using a terawatt laser hitting a polarized HD target. The polarized deuterons heated in the plasma induced by the laser can fuse producing a 3He and a neutron in the final state. The angular distribution of the emitted neutrons and the change in the corresponding total Cross Section (CS can sign the polarization persistence. The polarization of solid H2, D2 or T2 Hydrogen isotopes is very difficult. However, it has been possible to polarize HD, a hetero-molecular form of Hydrogen, by static polarization, at very low temperature and very high field. The radioactivity of DT molecules forbids there high polarization by the static method, therefore one has to develop the Dynamic Nuclear Polarization (DNP by RF transitions. The DNP of HD has been investigated in the past. The magnetic properties of HD and DT molecules are very similar, it is therefore expected that any polarization result obtained with HD could be extrapolated to DT.

  9. Effect of nickel content on the anodic dissolution and passivation of zinc–nickel alloys in alkaline solutions by potentiodynamic and potentiostatic techniques

    Indian Academy of Sciences (India)

    Abdel-Rahman El-Sayed; Hany M Abd El-Lateef; Hossnia S Mohran

    2015-04-01

    The effect of systematic increase of Ni on the anodic dissolution and passivation of Zn–Ni alloys in various concentrations of KOH solution (0.1–1 M) was investigated. The anodic dissolution and passivation behaviour for each pure Zn and Ni in the same studied solutions was also investigated, and the obtained data were compared. Potentiodynamic and potentiostatic methods were used, and the corrosion layer formed on each electrode surface was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results of the anodic potentiodynamic measurements exhibited that the polarization curves showed active/passive transition in the case of Ni and active/pseudopassive in the case of both Zn and its alloys. The results showed that the increase in Ni content increases the activation energy (a) and decreases the dissolution rate of the alloys in KOH solution, and the lowest dissolution rate was obtained at 10% Ni. The results of both potentiodynamic and potentiostatic measurements exhibit sudden increase in current density which is observed at certain positive potential (+0.42 V .SCE) in the case of the investigated alloys. This indicates that the addition of Ni to Zn promotes the electrochemical reaction (in the passive region). However, the passivation potential shifted to more positive direction with the increase in Ni content in the alloy.

  10. Combined electrochemical and X-ray tomography study of the high temperature evolution of Nickel - Yttria Stabilized Zirconia solid oxide fuel cell anodes

    Science.gov (United States)

    Kennouche, David; Chen-Wiegart, Yu-chen Karen; Riscoe, Casey; Wang, Jun; Barnett, Scott A.

    2016-03-01

    Accelerated ageing of Ni-Yttria Stabilized Zirconia (YSZ) anode functional layers (AFLs) in solid oxide fuel cells (SOFCs) is carried out at 1000-1200 °C, the resulting morphological changes are investigated using transmission X-ray microscopy (TXM), and properties are characterized using electrochemical impedance spectroscopy (EIS). Prior to ageing, the as prepared NiO-YSZ AFLs are reduced to Ni-YSZ and then aged at 1100 °C for 100 h in order to eliminate early-stage morphological changes. Measured particle size and three phase boundary (TPB) density changes with ageing time and temperature are fit reasonably well using a power-law coarsening model. This model is also used in conjunction with an electrochemical model to predict changes in the anode charge-transfer polarization resistance. The models are used to make predictions of the structural and electrochemical performance evolution of these Ni-YSZ anodes, for cells operated long-term at normal (700-850 °C) operating temperatures. Additional experiments to verify the model predictions are suggested.

  11. Effects of anodic passivation on the constitution, stability and resistance to corrosion of passive film formed on an Fe-24Mn-4Al-5Cr alloy

    International Nuclear Information System (INIS)

    The effects of anodic aging time and potential on the corrosion resistance, stability and constitution of the passive film formed on an Fe-24Mn-4Al-5Cr alloy in 50% HNO3 solution were studied by using combined electrochemical measurements and Auger electron spectroscopic (AES)/X-ray photoelectron spectroscopic (XPS) analysis. In the anodic passive region, prolonged anodic aging time or increased passivating potential can induce better protective and stable properties of the passive film and better resistance to corrosion. With increasing aging time from 15 min to 5 h, the time required for the potential decay from the passive to active state increases from about 300 up to above 12,000 s, and the corrosion resistance in 1 mol l-1 Na2SO4 solution of Fe-24Mn-4Al-5Cr alloy, characterized by polarization curves, is superior to that of Fe-13% Cr-0.1% C stainless steel. AES and XPS analyses of the aging passive film show that these improvements of properties are related to modifications of the passive layer with time. The increase of resistance to corrosion is attributed to Al2O3 and Cr2O3 enrichment and oxides of Fe and Mn depletion in the passive film and a thickening of the effective barrier layer of oxides

  12. Vacuum Evaporation Technology for Treating Antimony-Rich Anode Slime

    Science.gov (United States)

    Qiu, Keqiang; Lin, Deqiang; Yang, Xuelin

    2012-11-01

    A vacuum evaporation technology for treating antimony-rich anode slime was developed in this work. Experiments were carried out at temperatures from 873 K to 1073 K and residual gas pressures from 50 Pa to 600 Pa. During vacuum evaporation, silver from the antimony-rich anode slime was left behind in the distilland in a silver alloy containing antimony and lead, and antimony trioxide was evaporated. The experimental results showed that 92% by weight of antimony can be removed, and the silver content in the alloy was up to 12.84%. The antimony trioxide content in the distillate was more than 99.7%, and the distillate can be used directly as zero-grade antimony trioxide (China standard).

  13. Research of the photovoltaic properties of anodized films of Sn

    Science.gov (United States)

    Afanasyev, D. A.; Ibrayev, N. Kh; Omarova, G. S.; Smagulov, Zh K.

    2015-04-01

    The results of studies of photovoltaic properties of solar cells based on porous tin oxide films, sensitized with an organic dye are presented. Porous films were prepared by electrochemical anodization of tin in alkaline electrolytes based on aqueous solution of NaOH and aqueous ammonia NH4OH. It was found that the time of anodizing of the Sn films affects on conversion efficiency of light energy into electrical energy. Increasing of the sorption time leads to an increase of the number of molecules on the surface of the porous film. For the solar cell based on tin oxide there is a strong dark current, which significantly reduces the efficiency of conversion of light energy into electrical energy.

  14. Corrosion-resistant iridium dioxide-based anodes

    International Nuclear Information System (INIS)

    The most important results on corrosion-electrochemical behaviour of metal oxide anodes with an active coating (AC) on the basis of RuO2 and/or IrO2 have been analyzed. Stationary rates of corrosion and oxygen content in chlorine gas on the electrodes under conditions of chloric electrolysis have been ascertained, being 300 g/l NaCl, pH 2, T-87 deg. It has been detected that AC from IrO2 excels by two orders AC from RuO2, as regards its corrosion resistance. In contrast to RuO2 the rate of IrO2 dissolution depends but slightly on solution acidity. The anodes 30 mol.% (IrO2+RuO2)+70 mol.% TiO2 have been produced. 40 refs., 4 figs

  15. Recent trends in binder pitches for reduction anodes

    Science.gov (United States)

    Turner, Nigel R.

    1993-11-01

    The properties of coal tar pitches have changed more in the last eight years than in the previous 40. Over the same period of time, the understanding of the influence of these properties on anodes has increased greatly. The definition of a good-quality pitch for the manufacture of anodes for the primary aluminum industry has changed radically. Pitches that would have been rejected 15 years ago are now preferred and are in high demand. Changes have been led in equal proportion by the pitch producers and by the primary aluminum industry. The increased pace of change will continue as the quest for higher performance is unending. Further advances will be achieved through closer cooperation between producer and user to define and redefine pitch quality in terms of what is the best compromise between what the customer wants and what the producer can practicably manufacture.

  16. Mineralization of aqueous pentachlorophenolate by anodic contact glow discharge electrolysis

    Institute of Scientific and Technical Information of China (English)

    Haiming Yang; Meguru Tezuka

    2011-01-01

    Exhaustive mineralization of pentachlorophenolate ion (PCP) in phosphate buffer was carried out using anodic contact glow discharge electrolysis (CGDE), in which plasma was sustained between the electrolyte and anode. During CGDE, PCP degraded smoothly. The amount of total organic carbon decreased significantly, indicating the eventual conversion of the carbon atoms of benzene nucleus to inorganic carbons. Furthermore, chlorine atoms in PCP were liberated as chloride ions. As a primary intermediate product, 2,3,5,6-tetrachloro-1,4-benzoquinone was detected, and oxalate and formate as byproducts were also found. It was revealed that disappearance of PCP obeyed first-order kinetics. The reaction rate was generally unaffected by both O2 and inert gases in the cell, although it decreased by raising initial pH of solution. In addition, a plausible reaction pathway involving hydroxyl radical was proposed.

  17. Novel trench gate field stop IGBT with trench shorted anode

    Science.gov (United States)

    Xudong, Chen; Jianbing, Cheng; Guobing, Teng; Houdong, Guo

    2016-05-01

    A novel trench field stop (FS) insulated gate bipolar transistor (IGBT) with a trench shorted anode (TSA) is proposed. By introducing a trench shorted anode, the TSA-FS-IGBT can obviously improve the breakdown voltage. As the simulation results show, the breakdown voltage is improved by a factor of 19.5% with a lower leakage current compared with the conventional FS-IGBT. The turn off time of the proposed structure is 50% lower than the conventional one with less than 9% voltage drop increased at a current density of 150 A/cm2. Additionally, there is no snapback observed. As a result, the TSA-FS-IGBT has a better trade-off relationship between the turn off loss and forward drop. Project supported by the National Natural Science Foundation of China (No. 61274080) and the Postdoctoral Science Foundation of China (No. 2013M541585).

  18. Si nanowire arrays as anodes in Li ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Foell, H.; Hartz, H.; Ossei-Wusu, E.; Carstensen, J.; Riemenschneider, O. [Institute for Materials Science, Christian-Albrechts-University of Kiel (Germany)

    2010-02-15

    Si nanowires can incorporate large amounts of Li without fracturing and are thus prime candidates for anodes in Li ion batteries. Anodes made from Si nanowires offer a specific capacity per gram more then 10 times larger than the present graphite standard. It is shown how optimized Si nanowire arrays embedded in Cu can be produced in a relatively simple way employing macropore etching in Si followed by chemical etching and Cu galvanic deposition. First tests of these arrays in half-cells and batteries demonstrated a substantially increased capacity, small irreversible losses and cycle stability. In particular more than 60 charge/discharge cycles could be realized without loss of capacity. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Multi-metallic anodes for solid oxide fuel cell applications

    International Nuclear Information System (INIS)

    A new method for direct preparation of materials for solid oxide fuel cell anode - Ni- YSZ cermets - based on mechanical alloying (MA) of the original powders is developed, allowing to admix homogeneously any component. Additive metals are selected from thermodynamic criteria, leading to compacts consolidation through sintering by activated surface (SAS). The combined process MA-SSA can reduce the sintering temperature by 300 deg C, yielding porous anodes. Densification mechanisms are discussed from quasi-isothermal sintering kinetics results. Doping with Ag, W, Cu, Mo, Nb, Ta, in descending order, promotes the densification of pellets through liquid phase sintering and evaporation of metals and oxides, which allow reducing the sintering temperature. Powders and pellets characterization by electronic microscopy and X-ray diffraction completes the result analyses. (author)

  20. Carbon Cryogel Silicon Composite Anode Materials for Lithium Ion Batteries

    Science.gov (United States)

    Woodworth James; Baldwin, Richard; Bennett, William

    2010-01-01

    A variety of materials are under investigation for use as anode materials in lithium-ion batteries, of which, the most promising are those containing silicon. 10 One such material is a composite formed via the dispersion of silicon in a resorcinol-formaldehyde (RF) gel followed by pyrolysis. Two silicon-carbon composite materials, carbon microspheres and nanofoams produced from nano-phase silicon impregnated RF gel precursors have been synthesized and investigated. Carbon microspheres are produced by forming the silicon-containing RF gel into microspheres whereas carbon nano-foams are produced by impregnating carbon fiber paper with the silicon containing RF gel to create a free standing electrode. 1-4,9 Both materials have demonstrated their ability to function as anodes and utilize the silicon present in the material. Stable reversible capacities above 400 mAh/g for the bulk material and above 1000 mAh/g of Si have been observed.

  1. Polar Lipid Extraction

    OpenAIRE

    sprotocols

    2014-01-01

    Author: Biotechniques Polar lipids are generally extracted from dry cell material using chloroform:methanol:0.3% NaCl (1:2:0.8 v/v/v). This may be carried out by adding 9.5 ml of this mixture to 100 mg of freeze dried cells, or by adding a suitable amount of chloroform, methanol and 0.3% NaCl to the cell material, or to the aqueous methanolic phase remaining from the lipoquinone extraction. 1. The aqueous methanolic phase (4 ml total volume), together with the cell material from the ...

  2. Circularly polarized antennas

    CERN Document Server

    Gao, Steven; Zhu, Fuguo

    2013-01-01

    This book presents a comprehensive insight into the design techniques for different types of CP antenna elements and arrays In this book, the authors address a broad range of topics on circularly polarized (CP) antennas. Firstly, it introduces to the reader basic principles, design techniques and characteristics of various types of CP antennas, such as CP patch antennas, CP helix antennas, quadrifilar helix antennas (QHA), printed quadrifilar helix antennas (PQHA), spiral antenna, CP slot antennas, CP dielectric resonator antennas, loop antennas, crossed dipoles, monopoles and CP horns. Adva

  3. Gluon polarization in nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Shahveh, Abolfazl [Physics Department, Tafresh University, Tafresh (Iran, Islamic Republic of); Taghavi-Shahri, Fatemeh [School of Particles and Accelerators, Institute for Research in Fundamental, Sciences (IPM) P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Arash, Firooz, E-mail: farash@cic.aut.ac.i [Physics Department, Tafresh University, Tafresh (Iran, Islamic Republic of)

    2010-07-12

    In the context of the so-called valon model, we calculate ({delta}g)/g and show that although it is small and compatible with the measured values, the gluon contribution to the spin of nucleon can be sizable. The smallness of ({delta}g)/g in the measured kinematical region should not be interpreted as {delta}g being small. In fact, {delta}g itself at small x, and the first moment of the polarized gluon distribution in the nucleon, {Delta}g(Q{sup 2}), are large.

  4. Gluon polarization in nucleon

    International Nuclear Information System (INIS)

    In the context of the so-called valon model, we calculate (δg)/g and show that although it is small and compatible with the measured values, the gluon contribution to the spin of nucleon can be sizable. The smallness of (δg)/g in the measured kinematical region should not be interpreted as δg being small. In fact, δg itself at small x, and the first moment of the polarized gluon distribution in the nucleon, Δg(Q2), are large.

  5. Gluon polarization in nucleon

    Science.gov (United States)

    Shahveh, Abolfazl; Taghavi-Shahri, Fatemeh; Arash, Firooz

    2010-07-01

    In the context of the so-called valon model, we calculate δg/g and show that although it is small and compatible with the measured values, the gluon contribution to the spin of nucleon can be sizable. The smallness of δg/g in the measured kinematical region should not be interpreted as δg being small. In fact, δg itself at small x, and the first moment of the polarized gluon distribution in the nucleon, Δg (Q2), are large.

  6. Novel Ceramic Materials for Polymer Electrolyte Membrane Water Electrolysers' Anodes

    DEFF Research Database (Denmark)

    Polonsky, J.; Bouzek, K.; Prag, Carsten Brorson;

    2012-01-01

    Tantalum carbide was evaluated as a possible new support for the IrO2 for use in anodes of polymer electrolyte membrane water electrolysers. A series of supported electrocatalysts varying in mass content of iridium oxide was prepared. XRD, powder conductivity measurements and cyclic and linear...... sweep voltammetry were used to characterise the electrocatalysts. The most performing composition was found to lie between 50 and 90 wt.% IrO2 on TaC...

  7. Excitation of anodized alumina films with a light source

    DEFF Research Database (Denmark)

    Aggerbeck, Martin; Canulescu, Stela; Rechendorff, K.;

    Optical properties of anodized aluminium alloys were determined by optical diffuse reflectance spectroscopy of such films. Samples with different concentrations of dopants were excited with a white-light source combined with an integrating sphere for fast determination of diffuse reflectance. The......, with doping are discussed. Using the Kubelka-Munk model on the diffuse reflectance spectra of such films, the bandgap Eg of the oxide alloys can be determined....

  8. Ordered Nanomaterials Thin Films via Supported Anodized Alumina Templates

    OpenAIRE

    Mohammed eES-SOUNI; Salah ehabouti

    2014-01-01

    Supported anodized alumina template films with highly ordered porosity are best suited for fabricating large area ordered nanostructures with tunable dimensions and aspect ratios. In this paper we first discuss important issues for the generation of such templates, including required properties of the Al/Ti/Au/Ti thin film heterostructure on a substrate for high quality templates. We then show examples of anisotropic nanostructure films consisting of noble metals using these templates, discus...

  9. Ordered Nanomaterial Thin Films via Supported Anodized Alumina Templates

    OpenAIRE

    Es-Souni, Mohammed; Habouti, Salah

    2014-01-01

    Supported anodized alumina template films with highly ordered porosity are best suited for fabricating large-area ordered nanostructures with tunable dimensions and aspect ratios. In this paper, we first discuss important issues for the generation of such templates, including required properties of the Al/Ti/Au/Ti thin-film heterostructure on a substrate for high-quality templates. We then show examples of anisotropic nanostructure films consisting of noble metals using these templates, discu...

  10. Accounting for the Dynamic Oxidative Behavior of Nickel Anodes.

    Science.gov (United States)

    Smith, Rodney D L; Berlinguette, Curtis P

    2016-02-10

    The dynamic behavior of the anodic peak for amorphous nickel oxy/hydroxide (a-NiOx) films in basic media was investigated. Chronocoulometry of films with known nickel concentrations reveals that a total of four electrons per nickel site comprise the signature anodic peak at 1.32 V during the first oxidative scan, and two electrons are passed through the associated cathodic peak on the reverse scan. The anodic and cathodic signals each contain two electrons on the successive scans. Catalytic oxygen evolution reaction (OER) was detected within the anodic peak, which is at a lower potential than is widely assumed. In order to rationalize these experimental results, we propose that the four-electron oxidation event is the conversion of the film from nickel(II) hydroxide ([Ni(II)-OH](-)) to a higher valent nickel peroxide species (e.g., Ni(IV)-OO or Ni(III)-OO·). The subsequent reduction of the nickel peroxide species is confined by a chemical step resulting in the accumulation of [Ni(II)-OOH](-), which is then oxidized by two electrons to form Ni(IV)-OO during the subsequent oxidative scan on the time scale of a cyclic voltammetric experiment. Our proposed mechanism and the experimental determination that each nickel site is oxidized by four electrons helps link the myriad of seemingly disparate literature data related to OER catalysis by nickel electrodes. The faster catalysis that occurs at higher oxidative potentials is derived from a minority species and is not elaborated here. PMID:26829375

  11. Niobium-doped strontium titanates as SOFC anodes

    DEFF Research Database (Denmark)

    Blennow Tullmar, Peter; Kammer Hansen, Kent; Wallenberg, L. Reine;

    2008-01-01

    Sr-vacancy compensated Nb-doped SrTiO(3) with the nominal composition Sr(0.94)Ti(0.9)Nb(0.1)O(3) has been evaluated as part of a solid oxide fuel cell (SOFC) anode material in terms of redox stability, electrical conductivity, as well as electrochemical properties. Sr(0.94)Ti(0.9)Nb(0.1)O(3) has ...

  12. Strain engineered nanomembranes as anodes for lithium ion batteries

    OpenAIRE

    Deng, Junwen

    2015-01-01

    Lithium ion batteries (LIBs) have attracted considerable interest due to their wide range of applications, such as portable electronics, electric vehicles (EVs) and aerospace applications. Particularly, the emergence of a variety of nanostructured materials has driven the development of LIBs towards the next generation, which is featured with high specific energy and large power density. Herein, rolled-up nanotechnology is introduced for the design of strain-released materials as anodes of...

  13. Differential Pulse Anodic Stripping Voltammetry for Mercury Determination

    OpenAIRE

    Vereștiuc Paul C.; Tucaliuc Oana-Maria; Breabăn Iuliana G.; Crețescu Igor; Nemțoi Gheorghe

    2015-01-01

    In the present work voltammetric investigations have been performed on HgCl2 aqueous solutions prepared from a Cz 9024 reagent. Carbon paste electrode (CPE), eriochrome black T modified carbon paste electrode (MCPE/EBT) and KCl 1M as background electrolyte, were involved within the experimental procedures. Cyclic voltammetry (CV) has been performed in order to compare the behaviour of the two electrodes in both K3[Fe(CN)6] and mercury calibration aqueous solution. Differential pulse anodic st...

  14. Hydroxyapatite electrodeposition on anodized titanium nanotubes for orthopedic applications

    Energy Technology Data Exchange (ETDEWEB)

    Parcharoen, Yardnapar [Department of Biological Engineering, Faculty of Engineering, King Mongkut' s University of Technology Thonburi, Bangkok (Thailand); Kajitvichyanukul, Puangrat [Center of Excellence on Environmental Research and Innovation, Faculty of Engineering, Naresuan University, Phitsanulok (Thailand); Sirivisoot, Sirinrath [Department of Biological Engineering, Faculty of Engineering, King Mongkut' s University of Technology Thonburi, Bangkok (Thailand); Termsuksawad, Preecha, E-mail: preecha.ter@kmutt.ac.th [Division of Materials Technology, School of Energy, Environment and Materials, King Mongkut' s University of Technology Thonburi, 126 Pracha Uthit Rd., Bang Mod, ThungKhru, Bangkok 10140 (Thailand)

    2014-08-30

    Highlights: • We found that different anodization time of titanium significantly effects on nanotube length which further impacts adhesion strength of hydroxyapatite coating layers. • Adhesion strength of Hydroxyapatite (HA) coated on titanium dioxide nanotubes is better than that of HA coated on titanium plate. • Hydroxyapatite coated on titanium dioxide nanotubes showed higher cell density and better spreading of MC3T3-E1 cells (bone-forming cells) than that coated on titanium plate surface. - Abstract: Nanotubes modification for orthopedic implants has shown interesting biological performances (such as improving cell adhesion, cell differentiation, and enhancing osseointegration). The purpose of this study is to investigate effect of titanium dioxide (TiO{sub 2}) nanotube feature on performance of hydroxyapatite-coated titanium (Ti) bone implants. TiO{sub 2} nanotubes were prepared by anodization using ammonium fluoride electrolyte (NH{sub 4}F) with and without modifiers (PEG400 and Glycerol) at various potential forms, and times. After anodization, the nanotubes were subsequently annealed. TiO{sub 2} nanotubes were characterized by scanning electron microscope and X-ray diffractometer. The amorphous to anatase transformation due to annealing was observed. Smooth and highly organized TiO{sub 2} nanotubes were found when high viscous electrolyte, NH{sub 4}F in glycerol, was used. Negative voltage (−4 V) during anodization was confirmed to increase nanotube thickness. Length of the TiO{sub 2} nanotubes was significantly increased by times. The TiO{sub 2} nanotube was electrodeposited with hydroxyapatite (HA) and its adhesion was estimated by adhesive tape test. The result showed that nanotubes with the tube length of 560 nm showed excellent adhesion. The coated HA were tested for biological test by live/dead cell straining. HA coated on TiO{sub 2} nanotubes showed higher cells density, higher live cells, and more spreading of MC3T3-E1 cells than that

  15. Nanocarbon-Coated Porous Anodic Alumina for Bionic Devices

    OpenAIRE

    Morteza Aramesh; Wei Tong; Kate Fox; Ann Turnley; Dong Han Seo; Steven Prawer; Kostya (Ken) Ostrikov

    2015-01-01

    A highly-stable and biocompatible nanoporous electrode is demonstrated herein. The electrode is based on a porous anodic alumina which is conformally coated with an ultra-thin layer of diamond-like carbon. The nanocarbon coating plays an essential role for the chemical stability and biocompatibility of the electrodes; thus, the coated electrodes are ideally suited for biomedical applications. The corrosion resistance of the proposed electrodes was tested under extreme chemical conditions, su...

  16. Investigation of Anode Materials for Lithium Ion Batteries

    OpenAIRE

    Zhong, Lanlan

    2016-01-01

    Lithium ion batteries, Lithium ion batteries (LIBs) have for several years dominated the market for cell phones, laptops, and several other portable electronic devices. In order to match the necessity of increasing need for higher energy density storage devices, for example, hybrid/electric vehicles. Higher energy density lithium ion batteries have to be investigated. Anode as one of the most important components of in LIBs has been intensively studied in recent years. Silicon, tin and metal...

  17. Breathing silicon anodes for durable high-power operations

    OpenAIRE

    Chihyun Hwang; Sehun Joo; Na-Ri Kang; Ungju Lee; Tae-Hee Kim; Yuju Jeon; Jieun Kim; Young-Jin Kim; Ju-Young Kim; Sang-Kyu Kwak; Hyun-Kon Song

    2015-01-01

    Silicon anode materials have been developed to achieve high capacity lithium ion batteries for operating smart phones and driving electric vehicles for longer time. Serious volume expansion induced by lithiation, which is the main drawback of silicon, has been challenged by multi-faceted approaches. Mechanically rigid and stiff polymers (e.g. alginate and carboxymethyl cellulose) were considered as the good choices of binders for silicon because they grab silicon particles in a tight and rigi...

  18. Coated Silicon Nanowires as Anodes in Lithium Ion Batteries

    OpenAIRE

    Watts, David James

    2014-01-01

    Even though it has the highest known theoretical specific capacity of any material (~3600 mAh/g), silicon has limited use as an anode in lithium ion batteries due to the mechanical instability caused by the large volume expansion that occurs upon Li insertion. This volume expansion not only contributes to mechanical instability in the active silicon, but it also contributes to mechanical instability in the solid electrolyte interphase (SEI), a film formed at the end of the first lithiation s...

  19. Anodic etching of p-type cubic silicon carbide

    Science.gov (United States)

    Harris, G. L.; Fekade, K.; Wongchotigul, K.

    1992-01-01

    p-Type cubic silicon carbide was anodically etched using an electrolyte of HF:HCl:H2O. The etching depth was determined versus time with a fixed current density of 96.4 mA/sq cm. It was found that the etching was very smooth and very uniform. An etch rate of 22.7 nm/s was obtained in a 1:1:50 HF:HCl:H2O electrolyte.

  20. Doped Polyaniline: A Possible Anode for Organic Electronics

    OpenAIRE

    Palai, Akshaya K.; Periasamy, N.; Patankar, Meghan P.; Narasimhan, K. L.

    2013-01-01

    Polymer based printable organic thin film transistor (OTFT) is a viable low cost alternative to amorphous silicon based thin film transistors and possesses light-weight and flexibility advantage. In this paper, we report on the hole injecting properties of doped PANI in OLED devices using it as an anode. From these results we conclude that hole doped PANI layers can be used as a low contact resistance source and drain electrode material for polymer OTFTs.

  1. Improvement of thermal stability and safety of lithium ion battery using SiO anode material

    Science.gov (United States)

    Liu, Yi-Hung; Okano, Miki; Mukai, Takashi; Inoue, Kenshi; Yanagida, Masahiro; Sakai, Tetsuo

    2016-02-01

    The thermal stability, in terms of cycle and rate performances at 80 °C, and its safety related to lithium ion batteries composed of a LiFePO4 cathode and SiO anode are investigated. Based on an STEM-EELS analysis, the SiO powder is found to have an amorphous structure, in which nanosized Si particles (Si-rich phase) are uniformly dispersed in the SiO2 matrix (SiO2-rich phase). During the charge/discharge cycling, the cell exhibits a satisfactory cycle performance with a discharge capacity retention of 93.6% and a voltage retention of 93.9% at the 1500th cycle. Also, the charge and discharge capacity retentions at 10 C are 97.5% and 94.7%, respectively, together with a limited polarization, demonstrating its high rate performance. Furthermore, a 1.16 Ah LiFePO4/SiO laminated cell shows negligible voltage and temperature changes during the nail penetration test. The Li concentration in the active material (Si-rich phase) is found to be almost the same as that in the SiO2-rich phase after the test. This high thermal stability and safety may be due to the formed layer from the SiO2 matrix, preventing any side reaction from occurring on the Si surface and isolating the internal current path during the nail penetration.

  2. Influence of polar cap currents on pulsar polarization

    CERN Document Server

    Kumar, D

    2012-01-01

    We have developed a model for the polarization of curvature radiation for pulsars by taking into account the polar cap induced perturbation on the nonrotating (slowly rotating) dipolar magnetic field, where the rotation effects such as aberration and retardation can be ignored. We have simulated a set of typical pulse profiles to understand the role of induced magnetic field on radio emission of pulsars, and found to be significantly influencing the profile structure and polarization. Our model indicates that the intensity components and the polarization angle inflection point can get shifted to either leading or trailing side depending upon the prevailing conditions in the viewing geometry, the non-uniformity in source distribution (modulation) and the polar cap current induced perturbation. Also, we find an evidence for the origin of symmetric type circular polarization in addition to antisymmetric type. Our model predicts for a stronger trailing component compared to that on leading side of a given cone.

  3. Influence of anodization parameters on the volume expansion of anodic aluminum oxide formed in mixed solution of phosphoric and oxalic acids

    Science.gov (United States)

    Kao, Tzung-Ta; Chang, Yao-Chung

    2014-01-01

    The growth of anodic alumina oxide was conducted in the mixed solution of phosphoric and oxalic acids. The influence of anodizing voltage, electrolyte temperature, and concentration of phosphoric and oxalic acids on the volume expansion of anodic aluminum oxide has been investigated. Either anodizing parameter is chosen to its full extent of range that allows the anodization process to be conducted without electric breakdown and to explore the highest possible volume expansion factor. The volume expansion factors were found to vary between 1.25 and 1.9 depending on the anodizing parameters. The variation is explained in connection with electric field, ion transport number, temperature effect, concentration, and activity of acids. The formation of anodic porous alumina at anodizing voltage 160 V in 1.1 M phosphoric acid mixed with 0.14 M oxalic acid at 2 °C showed the peak volume expansion factor of 1.9 and the corresponding moderate growth rate of 168 nm/min.

  4. Transparent anodes for polymer photovoltaics: Oxygen permeability of PEDOT

    DEFF Research Database (Denmark)

    Andersen, M.; Carlé, Jon Eggert; Cruys-Bagger, N.;

    2007-01-01

    The oxygen permeability of the transparent organic anode poly(3,4,-ethylene dioxythiophene) with paratoluenesulphonate as the anion (PEDOT:pTS) was determined to be 2.5 +/- 0.7 x 10(-15) cm(3) (STP) CM cm(-2) S-1 Pa-1, and is thus comparable in magnitude to the oxygen permeability of polyethylene......The oxygen permeability of the transparent organic anode poly(3,4,-ethylene dioxythiophene) with paratoluenesulphonate as the anion (PEDOT:pTS) was determined to be 2.5 +/- 0.7 x 10(-15) cm(3) (STP) CM cm(-2) S-1 Pa-1, and is thus comparable in magnitude to the oxygen permeability...... of polyethyleneterephthalate (PET). The oxygen diffusion through bilayers of polyethylene (PE) and PEDOT:pTS and bilayers of PET and PEDOT:pTS was established. The bilayer structures were applied as the carrier substrate and the transparent anode in polymer-based photovoltaic devices employing a mixture of poly(1-methoxy-4......-(2-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV) and [6,6]-phenyt-C-61-butanoicacidmethylester (PCBM) as the active layer and aluminium as the cathode. The oxygen permeability of the layers and the aluminium cathode was correlated with the lifetime of the solar cell devices. It was found that the performance...

  5. Struvite precipitation and phosphorus removal using magnesium sacrificial anode.

    Science.gov (United States)

    Kruk, Damian J; Elektorowicz, Maria; Oleszkiewicz, Jan A

    2014-04-01

    Struvite precipitation using magnesium sacrificial anode as the only source of magnesium is presented. High-purity magnesium alloy cast anode was found to be very effective in recovery of high-quality struvite from water solutions and from supernatant of fermented waste activated sludge from a wastewater treatment plant that does not practice enhanced biological phosphorus removal. Struvite purity was strongly dependent on the pH and the electric current density. Optimum pH of the 24 mM phosphorus and 46 mM ammonia solution (1:1.9 P:N ratio) was in the broad range between 7.5 and 9.3, with struvite purity exceeding 90%. Increasing the current density resulted in elevated struvite purity. No upper limits were observed in the studied current range of 0.05-0.2 A. Phosphorus removal rate was proportional to the current density and comparable for tests with water solutions and with the supernatant from fermented sludge. The highest P-removal rate achieved was 4.0 mg PO4-P cm(-2) h(-1) at electric current density of 45 A m(-2). Initial substrate concentrations affected the rate of phosphorus removal. The precipitated struvite accumulated in bulk liquid with significant portions attached to the anode surface from which regular detachment occurred. PMID:24387911

  6. Development of hollow anode penning ion source for laboratory application

    Science.gov (United States)

    Das, B. K.; Shyam, A.; Das, R.; Rao, A. D. P.

    2012-03-01

    The research work presented here focuses for the development of miniature penning type ion source. One hollow anode penning type ion source was developed in our laboratory. The size of the ion source is 38 mm diameter and 55 mm length. The ion source consists of two cathodes, a hollow anode and one piece of rare earth permanent magnet. The plasma was created in the plasma region between cathodes and the hollow anode. The J × B force in the region helps for efficient ionization of the gas even in the high vacuum region˜1×10 -5 Torr. The ions were extracted in the axial direction with help of the potential difference between the electrodes and the geometry of the extraction angle. The effect of the extraction electrode geometry for efficient extraction of the ions from the plasma region was examined. This ion source is a self extracted ion source. The self extracted phenomena reduce the cost and the size of the ion source. The extracted ion current was measured by a graphite probe. An ion current of more than 200 μA was observed at the probe placed 70 mm apart from the extraction electrode. In this paper, the structure of the ion source, effect of operating pressure, potential difference and the magnetic field on the extracted ion current is reported.

  7. A new short-anoded IGBT with high emission efficiency

    Science.gov (United States)

    Weizhong, Chen; Bo, Zhang; Zehong, Li; Min, Ren; Zhaoji, Li

    2012-11-01

    A novel short-anoded insulated-gate bipolar transistor (SA-IGBT) with double emitters is proposed. At the on-state, the new structure shows extraordinarily high emission efficiency. Moreover, with a short-contacted anode, it further enhances the hole emission efficiency because of the crowding of the electrons. The forward voltage drop VF of this structure is 1.74 V at a current density 100 of A/cm2. Compared to the conventional NPT IGBT (1.94 V), segment-anode IGBT (SA-NPN 2.1 V), and conventional SA-IGBT (2.33 V), VF decreased by 10%, 17% and 30%, respectively. Furthermore, no NDR has been detected comparing to the SA-IGBT. At the off-state, there is a channel for extracting excessive carriers in the drift region. The turn-off loss Eoff of this proposed structure is 8.64 mJ/cm2. Compared to the conventional NPT IGBT (15.3 mJ/cm2), SA-NPN IGBT (12.8 mJ/cm2), and SA-IGBT (12.1 mJ/cm2), Eoff decreased by 43.7%, 32% and 28%, respectively.

  8. A new short-anoded IGBT with high emission efficiency

    Institute of Scientific and Technical Information of China (English)

    Chen Weizhong; Zhang Bo; Li Zehong; Ren Min; Li Zhaoji

    2012-01-01

    A novel short-anoded insulated-gate bipolar transistor (SA-IGBT) with double emitters is proposed.At the on-state,the new structure shows extraordinarily high emission efficiency.Moreover,with a short-contacted anode,it further enhances the hole emission efficiency because of the crowding of the electrons.The forward voltage drop VF of this structure is 1.74 V at a current density 100 of A/cm2.Compared to the conventional NPT IGBT (1.94 V),segment-anode IGBT (SA-NPN 2.1 V),and conventional SA-IGBT (2.33 V),VF decreased by 10%,17% and 30%,respectively.Furthermore,no NDR has been detected comparing to the SA-IGBT.At the offstate,there is a channel for extracting excessive carriers in the drift region.The turn-off loss Eoff of this proposed structure is 8.64 mJ/cm2.Compared to the conventional NPT IGBT (15.3 mJ/cm2),SA-NPN IGBT (12.8 mJ/cm2),and SA-IGBT (12.1 mJ/cm2),Eoff decreased by 43.7%,32% and 28%,respectively.

  9. Development of hollow anode penning ion source for laboratory application

    International Nuclear Information System (INIS)

    The research work presented here focuses for the development of miniature penning type ion source. One hollow anode penning type ion source was developed in our laboratory. The size of the ion source is 38 mm diameter and 55 mm length. The ion source consists of two cathodes, a hollow anode and one piece of rare earth permanent magnet. The plasma was created in the plasma region between cathodes and the hollow anode. The J × B force in the region helps for efficient ionization of the gas even in the high vacuum region∼1×10-5 Torr. The ions were extracted in the axial direction with help of the potential difference between the electrodes and the geometry of the extraction angle. The effect of the extraction electrode geometry for efficient extraction of the ions from the plasma region was examined. This ion source is a self extracted ion source. The self extracted phenomena reduce the cost and the size of the ion source. The extracted ion current was measured by a graphite probe. An ion current of more than 200 μA was observed at the probe placed 70 mm apart from the extraction electrode. In this paper, the structure of the ion source, effect of operating pressure, potential difference and the magnetic field on the extracted ion current is reported.

  10. Modelling study of CO 2 poisoning on PEMFC anodes

    Science.gov (United States)

    Janssen, G. J. M.

    The CO 2 poisoning effect on anodes for the proton-exchange-membrane fuel cell (PEMFC) was examined by model studies. It was assumed that the reverse water gas shift reaction (RWGS) is the origin of the CO 2 poisoning effects. The relation between the anode polarisation losses and the catalytic properties of the catalyst was investigated with a kinetic model and with a fuel cell model including finite utilisation of the fuel. It was found that the main effect of the occurrence of the reverse water gas shift reaction is that a large part of the catalytic surface area becomes inactive for hydrogen dissociation. Desorption of CO formed by reduction of CO 2 followed by transport down the anode gas channel and subsequent re-adsorption on the catalyst was shown to play a minor role. In reformate gas, where besides CO 2 traces of CO are present, CO 2 poisoning will have the largest effect when the CO content is small and at relatively low current density.

  11. Recycled diesel carbon nanoparticles for nanostructured battery anodes

    Science.gov (United States)

    Chen, Yuming; Liu, Chang; Sun, Xiaoxuan; Ye, Han; Cheung, Chunshun; Zhou, Limin

    2015-02-01

    Considerable attention has been devoted to using rational nanostructure design to address critical carbonaceous anode material issues for next-generation lithium-ion batteries (LIBs). However, the fabrication of nanostructured carbonaceous anode materials often involves complex processes and expensive starting materials. Diesel engine is an important source of nanostructured carbon particles with diameters ranging 20 nm-60 nm suspended in air, resulting in a serious scourge of global climate and a series of diseases such as lung cancer, asthma, and cardiovascular disease. Here, we show that diesel carbon nanoparticles collected from diesel engines can be chemically activated to create a porous structure. The resulting nanostructured carbon electrodes have a high specific capacity of 936 mAh g-1 after 40 cycles at 0.05 A/g, and excellent cycle stability while retaining a capacity of ∼210 mAh g-1 after 1200 cycles at 5 A/g. As recycled diesel carbon nanoparticles are readily available due to the several billion tons of diesel fuel consumed every year by diesel engines, their use represents an exciting source for nanostructured carbonaceous anode materials for high-performance LIBs and improves our environment and health.

  12. Mixed conductor anodes: Ni as electrocatalyst for hydrogen conversion

    DEFF Research Database (Denmark)

    Primdahl, S.; Mogensen, Mogens Bjerg

    2002-01-01

    (0.6)Gd(0.4)O(1.8) (CG4) ceramic, a La(0.75)Sr(0.25)Cr(0.97)V(0.03)O(3) (LSCV) ceramic and a Ti(0.22) Y(0.16)Zr(0.92)O(2.52) (TiYSZ) ceramic, Addition of small amounts ( approximate to I w/o) of Ni to the electrode surface is found to improve electrode performance on mixed electronic and ionic......Five types of anodes for solid oxide fuel cells (SOFC) are examined on an yttria-stabilised zirconia (YSZ) electrolyte by impedance spectroscopy at 850 degreesC in hydrogen. The examined porous anodes are a Ni/Zr(0.92)Y(0.16)O(2.08) (Ni/YSZ) cermet, a Ni/Ce(0.9)Gd(0.1)O(1.95) (Ni/CGI) cermet, a Ce...... conductors (MIEC's), distinctly in the low-frequency part of the impedance spectra. An effect of isotope exchange (H(2)/H(2)O to D(2)/D(2)O) is observed for all anodes. The low-frequency limitation is suggested to be hydrogen adsorption and/or dissociation on the surface of MIEC electrodes, (C) 2002 Elsevier...

  13. Nanocarbon-Coated Porous Anodic Alumina for Bionic Devices

    Directory of Open Access Journals (Sweden)

    Morteza Aramesh

    2015-08-01

    Full Text Available A highly-stable and biocompatible nanoporous electrode is demonstrated herein. The electrode is based on a porous anodic alumina which is conformally coated with an ultra-thin layer of diamond-like carbon. The nanocarbon coating plays an essential role for the chemical stability and biocompatibility of the electrodes; thus, the coated electrodes are ideally suited for biomedical applications. The corrosion resistance of the proposed electrodes was tested under extreme chemical conditions, such as in boiling acidic/alkali environments. The nanostructured morphology and the surface chemistry of the electrodes were maintained after wet/dry chemical corrosion tests. The non-cytotoxicity of the electrodes was tested by standard toxicity tests using mouse fibroblasts and cortical neurons. Furthermore, the cell–electrode interaction of cortical neurons with nanocarbon coated nanoporous anodic alumina was studied in vitro. Cortical neurons were found to attach and spread to the nanocarbon coated electrodes without using additional biomolecules, whilst no cell attachment was observed on the surface of the bare anodic alumina. Neurite growth appeared to be sensitive to nanotopographical features of the electrodes. The proposed electrodes show a great promise for practical applications such as retinal prostheses and bionic implants in general.

  14. SCATTERING POLARIZATION IN SOLAR FLARES

    Energy Technology Data Exchange (ETDEWEB)

    Štěpán, Jiří; Heinzel, Petr [Astronomical Institute ASCR, Fričova 298, 251 65 Ondřejov (Czech Republic)

    2013-11-20

    There is ongoing debate about the origin and even the very existence of a high degree of linear polarization of some chromospheric spectral lines observed in solar flares. The standard explanation of these measurements is in terms of the impact polarization caused by non-thermal proton and/or electron beams. In this work, we study the possible role of resonance line polarization due to radiation anisotropy in the inhomogeneous medium of the flare ribbons. We consider a simple two-dimensional model of the flaring chromosphere and we self-consistently solve the non-LTE problem taking into account the role of resonant scattering polarization and of the Hanle effect. Our calculations show that the horizontal plasma inhomogeneities at the boundary of the flare ribbons can lead to a significant radiation anisotropy in the line formation region and, consequently, to a fractional linear polarization of the emergent radiation of the order of several percent. Neglecting the effects of impact polarization, our model can provide a clue for resolving some of the common observational findings, namely: (1) why a high degree of polarization appears mainly at the edges of the flare ribbons; (2) why polarization can also be observed during the gradual phase of a flare; and (3) why polarization is mostly radial or tangential. We conclude that radiation transfer in realistic multi-dimensional models of solar flares needs to be considered as an essential ingredient for understanding the observed spectral line polarization.

  15. Modelling of binary alloy (Al–Mg) anode evaporation in arc welding

    International Nuclear Information System (INIS)

    A simple analytical model of binary alloy anode evaporation in gas–tungsten arc and gas–metal arc welding is proposed. The model comprises the model of evaporation in convective and diffusive regimes, model of anode processes and allows one to calculate basic physical properties of multicomponent arc plasma near the anode surface as functions of the anode surface temperature, anode chemical composition, electron temperature and electric current density at the anode surface. Evaporation of binary Al–Mg alloys with different magnesium mass fraction into argon plasma is considered on the basis of the proposed model. The dependences of the alloy boiling temperature on the magnesium mass fraction and electron temperature are presented. Several physical parameters, which are important from the technological point of view (magnesium mass flux, heat loss due to evaporation, anode potential drop, anode heat flux), are calculated for a wide range of anode surface temperature and different values of the magnesium mass fraction. In addition, the influence of heat loss due to evaporation on the total heat flux coming to the anode surface is demonstrated. (paper)

  16. Polar drive on OMEGA

    International Nuclear Information System (INIS)

    High-convergence polar-drive experiments are being conducted on OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using triple-picket laser pulses. The goal of OMEGA experiments is to validate modeling of oblique laser deposition, heat conduction in the presence of nonradial thermal gradients in the corona, and implosion energetics in the presence of laser-plasma interactions such as crossed-beam energy transfer. Simulated shock velocities near the equator, where the beams are obliquely incident, are within 5% of experimentally inferred values in warm plastic shells, well within the required accuracy for ignition. High, near-one-dimensional areal density is obtained in warm-plastic-shell implosions. Simulated back-lit images of the compressing core are in good agreement with measured images. Outstanding questions that will be addressed in the future relate to the role of cross-beam transfer in polar drive irradiation and increasing the energy coupled into the target by decreasing beam obliquity. (authors)

  17. Transverse Neutrino Polarization in $\

    CERN Document Server

    Sobkow, W

    2000-01-01

    In this paper a scenario admitting the participation of right-handed $S_{R}$ and left-handed $S_{L}$ scalar couplings in addition to the left-handed standard $(V, A)_{L}$ couplings in the muonic neutrino-electron elastic scattering is considered. Muon-neutrinos can come from pion-decay. We consider this process at the level of the four-fermion point (contact) interaction. Muon-neutrinos are assumed to be massive and to be Dirac fermions. We assume also that the incoming neutrinos are polarized. The formula for the laboratory differential cross section (in the limit of vanishing neutrino mass) in which the non-standard contributions coming from the interference between the left-handed vector $V_{L}$ and right-handed $S_{R}$ scalar couplings appear is given. These are the transverse components of the incoming neutrino polarization, both T-odd and T-even. The non-zero values of such observables would be the proof of the participation of the right-handed neutrinos in a pure leptonic process. As far as T-odd trans...

  18. Facile synthesis of reduced graphene oxide-porous silicon composite as superior anode material for lithium-ion battery anodes

    Science.gov (United States)

    Jiao, Lian-Sheng; Liu, Jin-Yu; Li, Hong-Yan; Wu, Tong-Shun; Li, Fenghua; Wang, Hao-Yu; Niu, Li

    2016-05-01

    We report a new method for synthesizing reduced graphene oxide (rGO)-porous silicon composite for lithium-ion battery anodes. Rice husks were used as a as a raw material source for the synthesis of porous Si through magnesiothermic reduction process. The as-obtained composite exhibits good rate and cycling performance taking advantage of the porous structure of silicon inheriting from rice husks and the outstanding characteristic of graphene. A considerably high delithiation capacity of 907 mA h g-1 can be retained even at a rate of 16 A g-1. A discharge capacity of 830 mA h g-1 at a current density of 1 A g-1 was delivered after 200 cycles. This may contribute to the further advancement of Si-based composite anode design.

  19. Fabrication and Characterization of Graded Anodes for Anode-Supported Solid Oxide Fuel Cells by Tape Casting and Lamination

    DEFF Research Database (Denmark)

    Beltran-Lopez, J.F.; Laguna-Bercero, M.A.; Gurauskis, Jonas;

    2014-01-01

    Graded anodes for anode-supported solid oxide fuel cells (SOFCs) are fabricated by tape casting and subsequent cold lamination of plates using different compositions. Rheological parameters are adjusted to obtain stable suspensions for tape casting. The conditions for the tape casting...... and homogeneous distribution of nickel, zirconia, and pores. The laminated samples showed a total porosity of 18.7%(in vol%) and a bimodal pore size distribution centered in 20 and 150 nm, and the measured electrical resistivity of this sample was 120±12 μΩ cm. The novelty of the present work is the lamination...... of tapes at room temperature without using plasticizers. This is made by the combination of two different binders with varying Tg (glass transition temperature) which resulted in plastic deformation at room temperature. Those results indicate that the proposed process is a cost-effective method...

  20. Alliages intermétalliques du magnésium, anodes pour MAFC ? Magnesium intermetallic alloys, anodes for MAFC?

    Directory of Open Access Journals (Sweden)

    Montagné Pierre

    2013-11-01

    Full Text Available Des composés intermétalliques sélectionnés ont été étudiés en vue d'une utilisation en remplacement de l'anode métallique dans des batteries de type métal air. Ces composés présentent des structures cristallines très différentes : structure lamellaire pour MgB2, structure covalente simple pour Mg2Si et structure complexe basée sur un empilement compact de polyèdres pour Mg2Al3. Les meilleurs résultats sont obtenus pour ce dernier composé avec une réactivité vis-à-vis des électrolytes testés sensiblement inférieure à celle du magnésium et une cinétique de réaction plus lente. Le potentiel en fonctionnement au sein de la batterie est sensiblement plus faible que celui du magnésium mais il présente une stabilité remarquable au cours du temps. Selected intermetallic compounds have been studied as anodic materials in metal air fuel cells. These compounds have different structural types, MgB2 displays a lamellar structure, Mg2Si a simple covalent structure while Mg2Al3 has a complex structure based on compact polyhedral packing. Best electrochemical results are obtained for the latter, with a lower reactivity towards magnesium in the two electrolytes and with lower kinetics of reaction. The operating potential of the battery with a Mg2Al3 anode is noticeably lower than with a Mg anode, but it presents a very good stability over time.

  1. Polarization and Polarimetry: A Review

    CERN Document Server

    Trippe, S

    2014-01-01

    Polarization is a basic property of light and is fundamentally linked to the internal geometry of a source of radiation. Polarimetry complements photometric, spectroscopic, and imaging analyses of sources of radiation and has made possible multiple astrophysical discoveries. In this article I review (i) the physical basics of polarization: electromagnetic waves, photons, and parameterizations; (ii) astrophysical sources of polarization: scattering, synchrotron radiation, active media, and the Zeeman, Goldreich-Kylafis, and Hanle effects, as well as interactions between polarization and matter (like birefringence, Faraday rotation, or the Chandrasekhar-Fermi effect); (iii) observational methodology: on-sky geometry, influence of atmosphere and instrumental polarization, polarization statistics, and observational techniques for radio, optical, and X/gamma wavelengths; and (iv) science cases for astronomical polarimetry: solar and stellar physics, planetary system bodies, interstellar matter, astrobiology, astro...

  2. Polarization and relaxation of radon

    CERN Document Server

    Tardiff, E R; Chupp, T E; Gulyuz, K; Lefferts, R S; Lorenzon, W; Nuss-Warren, S R; Pearson, M R; Pietralla, N; Rainovski, G; Sell, J F; Sprouse, G D

    2006-01-01

    Investigations of the polarization and relaxation of $^{209}$Rn by spin exchange with laser optically pumped rubidium are reported. On the order of one million atoms per shot were collected in coated and uncoated glass cells. Gamma-ray anisotropies were measured as a signal of the alignment (second order moment of the polarization) resulting from the combination of polarization and quadrupole relaxation at the cell walls. The temperature dependence over the range 130$^\\circ$C to 220$^\\circ$C shows the anisotropies increasing with increasing temperature as the ratio of the spin exchange polarization rate to the wall relaxation rate increases faster than the rubidium polarization decreases. Polarization relaxation rates for coated and uncoated cells are presented. In addition, improved limits on the multipole mixing ratios of some of the main gamma-ray transitions have been extracted. These results are promising for electric dipole moment measurements of octupole-deformed $^{223}$Rn and other isotopes, provided...

  3. Polarized proton collider at RHIC

    International Nuclear Information System (INIS)

    In addition to heavy ion collisions (RHIC Design Manual, Brookhaven National Laboratory), RHIC will also collide intense beams of polarized protons (I. Alekseev, et al., Design Manual Polarized Proton Collider at RHIC, Brookhaven National Laboratory, 1998, reaching transverse energies where the protons scatter as beams of polarized quarks and gluons. The study of high energy polarized protons beams has been a long term part of the program at BNL with the development of polarized beams in the Booster and AGS rings for fixed target experiments. We have extended this capability to the RHIC machine. In this paper we describe the design and methods for achieving collisions of both longitudinal and transverse polarized protons in RHIC at energies up to √s=500 GeV

  4. Anodic luminescence, structural, photoluminescent, and photocatalytic properties of anodic oxide films grown on niobium in phosphoric acid

    Science.gov (United States)

    Stojadinović, Stevan; Tadić, Nenad; Radić, Nenad; Stefanov, Plamen; Grbić, Boško; Vasilić, Rastko

    2015-11-01

    This article reports on properties of oxide films obtained by anodization of niobium in phosphoric acid before and after the dielectric breakdown. Weak anodic luminescence of barrier oxide films formed during the anodization of niobium is correlated to the existence of morphological defects in the oxide layer. Small sized sparks generated by dielectric breakdown of formed oxide film cause rapid increase of luminescence intensity. The luminescence spectrum of obtained films on niobium under spark discharging is composed of continuum radiation and spectral lines caused by electronic spark discharging transitions in oxygen and hydrogen atoms. Oxide films formed before the breakdown are amorphous, while after the breakdown oxide films are partly crystalline and mainly composed of Nb2O5 hexagonal phase. The photocatalytic activity of obtained oxide films after the breakdown was investigated by monitoring the degradation of methyl orange. Increase of the photocatalytic activity with time is related to an increase of oxygen vacancy defects in oxide films formed during the process. Also, higher concentration of oxygen vacancy defects in oxide films results in higher photoluminescence intensity.

  5. Polarized Electrons for Linear Colliders

    CERN Document Server

    Clendenin, J E; Garwin, E L; Kirby, R E; Luh, D A; Maruyama, T; Prescott, C Y; Sheppard, J C; Turner, J; Prepost, R

    2005-01-01

    Future electron-positron linear colliders require a highly polarized electron beam with a pulse structure that depends primarily on whether the acceleration utilizes warm or superconducting rf structures. The International Linear Collider (ILC) will use cold structures for the main linac. It is shown that a dc-biased polarized photoelectron source such as successfully used for the SLC can meet the charge requirements for the ILC micropulse with a polarization approaching 90%.

  6. Bioelectric modulation of macrophage polarization

    OpenAIRE

    Chunmei Li; Michael Levin; Kaplan, David L.

    2016-01-01

    Macrophages play a critical role in regulating wound healing and tissue regeneration by changing their polarization state in response to local microenvironmental stimuli. The native roles of polarized macrophages encompass biomaterials and tissue remodeling needs, yet harnessing or directing the polarization response has been largely absent as a potential strategy to exploit in regenerative medicine to date. Recent data have revealed that specific alteration of cells’ resting potential (Vmem)...

  7. Majorization of quantum polarization distributions

    CERN Document Server

    Luis, Alfredo

    2016-01-01

    Majorization provides a rather powerful partial-order classification of probability distributions depending only on the spread of the statistics, and not on the actual numerical values of the variable being described. We propose to apply majorization as a meta-measure of quantum polarization fluctuations, this is to say of the degree of polarization. We compare the polarization fluctuations of the most relevant classes of quantum and classical-like states. In particular we test the Lieb's conjecture regarding classical-like states as the most polarized and a complementary conjecture that the most unpolarized pure states are the most nonclassical.

  8. The RHIC polarized source upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Zelenski, A.; Atoian, G.; Davydenko, V.; Ivanov, A.; Kolmogorov, A.; Ritter, J.; Steski, D.; Zubets, V.

    2010-09-27

    The RHIC polarized H{sup -} ion source is being upgraded to higher intensity (5-10 mA) and polarization for use in the RHIC polarization physics program at enhanced luminosity RHIC operation. The higher beam peak intensity will allow reduction of the transverse beam emittance at injection to AGS to reduce polarization losses in AGS. There is also a planned RHIC luminosity upgrade by using the electron beam lens to compensate the beam-beam interaction at collision points. This upgrade is also essential for future BNL plans for a high-luminosity electron - proton (ion) Collider eRHIC.

  9. Polarization signals in mantis shrimps

    Science.gov (United States)

    Cronin, Thomas W.; Chiou, Tsyr-Huei; Caldwell, Roy L.; Roberts, Nicholas; Marshall, Justin

    2009-08-01

    While color signals are well known as a form of animal communication, a number of animals communicate using signals based on patterns of polarized light reflected from specialized body parts or structures. Mantis shrimps, a group of marine crustaceans, have evolved a great diversity of such signals, several of which are based on photonic structures. These include resonant scattering devices, structures based on layered dichroic molecules, and structures that use birefringent layers to produce circular polarization. Such biological polarizers operate in different spectral regions ranging from the near-UV to medium wavelengths of visible light. In addition to the structures that are specialized for signal production, the eyes of many species of mantis shrimp are adapted to detect linearly polarized light in the ultraviolet and in the green, using specialized sets of photoreceptors with oriented, dichroic visual pigments. Finally, a few mantis shrimp species produce biophotonic retarders within their photoreceptors that permit the detection of circularly polarized light and are thus the only animals known to sense this form of polarization. Mantis shrimps use polarized light in species-specific signals related to mating and territorial defense, and their means of manipulating light's polarization can inspire designs for artificial polarizers and achromatic retarders.

  10. Elite Polarization and Public Opinion

    DEFF Research Database (Denmark)

    Robison, Joshua; Mullinix, Kevin

    2016-01-01

    Elite polarization has reshaped American politics and is an increasingly salient aspect of news coverage within the United States. As a consequence, a burgeoning body of research attempts to unravel the effects of elite polarization on the mass public. However, we know very little about how polar...... of the consequences of elite polarization—and how polarization is communicated—for public opinion and political behavior in democratic politics.......Elite polarization has reshaped American politics and is an increasingly salient aspect of news coverage within the United States. As a consequence, a burgeoning body of research attempts to unravel the effects of elite polarization on the mass public. However, we know very little about how...... polarization is communicated to the public by news media. We report the results of one of the first content analyses to delve into the nature of news coverage of elite polarization. We show that such coverage is predominantly critical of polarization. Moreover, we show that unlike coverage of politics focused...

  11. A polarized alkali ion source

    International Nuclear Information System (INIS)

    The beam foil technique has been applied to detect nuclear vector polarization of a 10 keV 23Na+ beam. The result was about 70% of the atomic beam polarization thus limiting the depolarization by the surface ionizer to at most 30%. In a Coulomb excitation experiment with a tensor polarized 42 MeV 23Na7+ beam an effect of 0.011 +- 0.003 was measured yielding a value of t20 approx. 0.04 for the beam polarization. The depolarization during the acceleration process can be estimated to be about 0.8. (orig.)

  12. Polarization-preserving holey fibers

    DEFF Research Database (Denmark)

    Broeng, Jes; Mogilevtsev, Dmitri; Libori, Stig E. Barkou;

    2001-01-01

    In this work we suggest and discuss a microstructure of air capillaries with elliptical cross-section in a tread of glass that gives opportunity for Creation of polarization-preserving fiber with very small beat length between the fundamental modes of different polarization......In this work we suggest and discuss a microstructure of air capillaries with elliptical cross-section in a tread of glass that gives opportunity for Creation of polarization-preserving fiber with very small beat length between the fundamental modes of different polarization...

  13. Investigation of carbon supported PtW catalysts as CO tolerant anodes at high temperature in proton exchange membrane fuel cell

    Science.gov (United States)

    Hassan, Ayaz; Paganin, Valdecir A.; Ticianelli, Edson A.

    2016-09-01

    The CO tolerance mechanism and the stability of carbon supported PtW electrocatalysts are evaluated in the anode of a proton exchange membrane fuel cell (PEMFC) at two different temperatures. The electrocatalysts are characterized by energy dispersive spectroscopy, X-ray diffraction, and transmission electron spectroscopy. Employed electrochemical techniques include cyclic voltammetry, CO stripping, fuel cell polarization, and online mass spectrometry. At a cell temperature of 85 °C, the PtW/C catalyst shows higher CO tolerance compared to Pt/C due an electronic effect of WOx in the Pt 5d band, which reduces the CO adsorption. An increase in hydrogen oxidation activity in the presence of CO is observed for both the catalysts at a higher temperature, due to the decrease of the Pt-CO coverage. A reduction in the current densities occurs for the PtW/C catalyst in both polarization curves and cyclic voltammograms after 5000 cycles of the anode in the range of 0.1-0.7 V vs. RHE at 50 mVs-1. This decrease in performance is assigned to the dissolution of W, with a consequent increase in the membrane resistivity. However, the observed decline of performance is small either in the presence of pure H2 or in the presence of H2/CO.

  14. Ralicon anodes for image photon counting fabricated by electron beam lithography

    International Nuclear Information System (INIS)

    The Anger wedge and strip anode event location system developed for microchannel plate image photon detectors at the Space Sciences Laboratory of the University of California, Berkeley, has been extended in the present work by the use of electron beam lithography (EBL). This method of fabrication can be used to produce optical patterns for the subsequent manufacture of anodes by conventional photo-etching methods and has also enabled anodes to be produced directly by EBL microfabrication techniques. Computer-aided design methods have been used to develop several types of RALICON (Readout Anodes of Lithographic Construction) for use in photon counting microchannel plate imaging detectors. These anodes are suitable for linear, two dimensional or radial position measurements and they incorporate novel design features made possible by the EBL fabrication technique which significantly extend their application relative to published wedge-strip anode designs. (author)

  15. An Analysis of Mechanical Properties of Anodized Aluminum Film at High Stress

    Science.gov (United States)

    Zhao, Xixi; Wei, Guoying; Yu, Yundan; Guo, Yuemei; Zhang, Ao

    2015-10-01

    In this paper, a new environmental-friendly electrolyte containing sulfuric acid and tartaric acid has been used as the substitute of chromic acid for anodization. The work discussed the influence of anodizing voltages on the fatigue life of anodized Al 2024-T3 by performing fatigue tests with 0.1 stress ratio (R) at 320 MPa. Meanwhile the fatigue cycles to failure, yield strength, tensile strength and fracture surface of anodic films at different conditions were investigated. The results showed that the fatigue life of anodized and sealed specimens reduced a lot compared to aluminum alloy, which can be attributed to the crack sites initiated at the oxide layer. The fracture surface analyses also revealed that the number of crack initiation sites enlarged with the increase of anodizing voltage.

  16. Features of the formation of anodic niobium oxide in a potassium nitrate melt

    Energy Technology Data Exchange (ETDEWEB)

    Skatkov, L.I.; Malyuk, Yu.I.

    1988-07-10

    This work is a further development of the investigations of the processes of the anodization of niobium in nitrate melts of salts at temperatures allowing recrystallization of the oxide. The anodic films of niobium formed in a nitrate melt consist of sandwiches of phases of Nb/sub 2/O/sub 5/, NbO/sub 2/, and NbO (from the outer surface of the anodic oxide film toward the niobium substrate), and high anodization temperatures cause the intense dissolution of oxygen in the niobium substrate. During the formation of an anodic oxide film, it becomes saturated with the anionic and cationic components of the electrolyte. The uptake of the anions is most significant in the initial stages of growth of the oxide layer, while saturation with potassium occurs in the final stages of anodization.

  17. Preparation of self-organized porous anodic niobium oxide microcones and their surface wettability

    International Nuclear Information System (INIS)

    Porous anodic niobium oxide with a pore size of ∼10 nm was formed at 10 V in glycerol electrolyte containing 0.6 mol dm-3 K2HPO4 and 0.2 mol dm-3 K3PO4 at 433 K. After prolonged anodizing for 5.4 ks, niobium oxide microcones develop on the surface. X-ray diffraction patterns of the anodized specimens revealed that the initially formed anodic oxide is amorphous, but an amorphous-to-crystalline transition occurs during anodizing. As a consequence of the preferential chemical dissolution of the initially formed amorphous oxide, due to different solubility of the amorphous and crystalline oxides, crystalline oxide microcones appear on the film surface after prolonged anodizing. The surface is superhydrophilic. After coating with fluorinated alkylsilane, the surface becomes superhydrophobic with a contact angle of 158o for water. The surface is also oil repellent, with a contact angle as high as 140o for salad oil.

  18. Formation of Porous Anodic Oxide Film on Titanium in Phosphoric Acid Electrolyte

    Science.gov (United States)

    Liu, Z.; Thompson, G. E.

    2015-01-01

    A sequential breakdown anodizing conditions on cp-Ti in phosphoric acid has been investigated in the present study. Anodic oxide films were formed at 100, 150, and 200 V, examined by scanning electron microscopy, Raman spectroscopy, glow discharge optical emission spectrometry, and electrochemical impedance spectroscopy. A porous oxide texture was formed at each voltage. The thickness of anodic porous oxide increased with the increase of anodic voltage. Nano-particulates were formed around and within the pores, and the size of pores increased with increased voltage due to the expansion of particulates. The amorphous-to-crystalline transition was initiated during the film growth. The degree of crystallinity in the anodic oxide film fabricated at 200 V is more abundant than 150 and 100 V. Increased content of the phosphorus species was incorporated into the porous film with the increase of anodic voltage, stabilizing for the nanocrystals developed within the oxide.

  19. Ultra-structural evaluation of an anodic oxidated titanium dental implant.

    Science.gov (United States)

    Yamagami, Akiyoshi; Nagaoka, Noriyuki; Yoshihara, Kumiko; Nakamura, Mariko; Shirai, Hajime; Matsumoto, Takuya; Suzuki, Kazuomi; Yoshida, Yasuhiro

    2014-01-01

    Anodic oxidation is used for the surface treatment of commercial implants to improve their functional properties for clinical success. Here we conducted ultrastructural and chemical investigations into the micro- and nanostructure of the anodic oxide film of a titanium implant. The anodic oxidized layer of a Ti6Al4V alloy implant was examined ultrastructurally by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). They were also analyzed using energy dispersive X-ray spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS). The TEM revealed that the oxide layer of the Ti6Al4V implant prepared through anodic oxidation was separated into two layers. Al and V were not present on the top surface of the anodic oxide. This can be attributed to the biocompatibility of the anodic oxidized Ti6Al4V alloy implant, because the release of harmful metal ions such as Al and V can be suppressed by the biocompatibility. PMID:25483382

  20. Photoelectrochemical evidence of nitrogen incorporation during anodizing sputtering--deposited Al-Ta alloys.

    Science.gov (United States)

    Zaffora, A; Santamaria, M; Di Franco, F; Habazaki, H; Di Quarto, F

    2016-01-01

    Anodic films were grown to 20 V on sputtering-deposited Al-Ta alloys in ammonium biborate and borate buffer solutions. According to glow discharge optical emission spectroscopy, anodizing in ammonium containing solution leads to the formation of N containing anodic layers. Impedance measurements did not evidence significant differences between the dielectric properties of the anodic films as a function of the anodizing electrolyte. Photoelectrochemical investigation allowed evidencing that N incorporation induces a red-shift in the light absorption threshold of the films due to the formation of allowed localized states inside their mobility gap. The estimated Fowler threshold for the internal photoemission processes of electrons resulted to be independent of the anodizing electrolyte confirming that N incorporation does not appreciably affect the density of states distribution close to the conduction band mobility edge. The transport of photogenerated carriers has been rationalized according to the Pai-Enck model of geminate recombination.

  1. Carbon Nanofibers Modified Graphite Felt for High Performance Anode in High Substrate Concentration Microbial Fuel Cells

    Directory of Open Access Journals (Sweden)

    Youliang Shen

    2014-01-01

    Full Text Available Carbon nanofibers modified graphite fibers (CNFs/GF composite electrode was prepared for anode in high substrate concentration microbial fuel cells. Electrochemical tests showed that the CNFs/GF anode generated a peak current density of 2.42 mA cm−2 at a low acetate concentration of 20 mM, which was 54% higher than that from bare GF. Increase of the acetate concentration to 80 mM, in which the peak current density of the CNFs/GF anode greatly increased and was up to 3.57 mA cm−2, was seven times as that of GF anode. Morphology characterization revealed that the biofilms in the CNFs/GF anode were much denser than those in the bare GF. This result revealed that the nanostructure in the anode not only enhanced current generation but also could tolerate high substrate concentration.

  2. Specific features of an electric discharge operating between an electrolytic anode and a metal cathode

    Energy Technology Data Exchange (ETDEWEB)

    Gaisin, A. F.; Sarimov, L. R. [Kazan State Technical University (Russian Federation)

    2011-06-15

    Results are presented from experimental studies of a high-current electric discharge operating between an St45 steel cathode and a service water anode in a wide range of air pressures. Peculiarities of discharge ignition and specific features of cathode and anode spots were revealed. The behavior of the current density on a service water anode was investigated for the first time. Comparison of the current densities j on the steel cathode and service water anode shows that, in the parameter range under study, Hehl's law is not satisfied on the water anode. The two-dimensional distribution of the potential inside and on the surface of the service water anode was measured.

  3. Specific features of an electric discharge operating between an electrolytic anode and a metal cathode

    Science.gov (United States)

    Gaisin, A. F.; Sarimov, L. R.

    2011-06-01

    Results are presented from experimental studies of a high-current electric discharge operating between an St45 steel cathode and a service water anode in a wide range of air pressures. Peculiarities of discharge ignition and specific features of cathode and anode spots were revealed. The behavior of the current density on a service water anode was investigated for the first time. Comparison of the current densities j on the steel cathode and service water anode shows that, in the parameter range under study, Hehl's law is not satisfied on the water anode. The two-dimensional distribution of the potential inside and on the surface of the service water anode was measured.

  4. Effect of Anode Floating Voltage and its Applications in Characterizing Silicon Drift Detectors

    Institute of Scientific and Technical Information of China (English)

    WU Guang-Guo; LI Hong-Ri; LIANG Kun; YANG Ru; CAO Xue-Lei; WANG Huan-Yu; AN Jun-Ming; HU Xiong-Wei; HAN De-Jun

    2009-01-01

    @@ Anode floating voltage is predicted and investigated for silicon drift detectors (SDDs) with an active area of 5 mm2 fabricated by a double-side parallel technology. It is demonstrated that the anode floating voltage increases with the increasing inner ring voltage, and is almost unchanged with the external ring voltage. The anode floating voltage will not be affected by the back electrode biased voltage until it reaches the full-depleted voltage (-50 V) of the SDD. Theoretical analysis and experimental results show that the anode floating voltage is equal to the sum of the inner ring voltage and the built-in potential between the p+ inner ring and the n+ anode. A fast checking method before detector encapsulation is proposed by employing the anode floating voltage along with checking the leakage current, potential distribution and drift properties.

  5. Engineering of highly ordered TiO2 nanopore arrays by anodization

    Science.gov (United States)

    Wang, Huijie; Huang, Zhennan; Zhang, Li; Ding, Jie; Ma, Zhaoxia; Liu, Yong; Kou, Shengzhong; Yang, Hangsheng

    2016-07-01

    Finite element analysis was used to simulate the current density distributions in the TiO2 barrier layer formed at the initial stage of Ti anodization. The morphology modification of the barrier layer was found to induce current density distribution change. By starting the anodization with proper TiO2 barrier layer morphology, the current density distribution can be adjusted to favor the formation of either nanotube arrays or nanopore arrays of anodic TiO2. We also found that the addition of sodium acetate into the electrolyte suppressed both the field-assisted chemical dissolution of TiO2 and the TiF62- hydrolysis induced TiO2 deposition during anodization, and thus further favored the nanopore formation. Accordingly, highly ordered anodic TiO2 nanopore arrays, similar to anodic aluminum oxide nanopore arrays, were successfully prepared.

  6. Study of the alloying additives and alkaline zincate solution effects on the commercial aluminum as galvanic anode for use in alkaline batteries

    Energy Technology Data Exchange (ETDEWEB)

    Rashvand avei, M. [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of); Jafarian, M., E-mail: mjafarian@kntu.ac.ir [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of); Moghanni Bavil Olyaei, H. [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of); Gobal, F. [Department of Chemistry, Sharif University of Technology, P.O. Box 11365-8516, Tehran (Iran, Islamic Republic of); Hosseini, S.M. [Jahad Organization – Science and Technology Center, Tehran (Iran, Islamic Republic of); Mahjani, M.G. [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of)

    2013-12-16

    The corrosion behavior of different grades of commercial aluminum such as AA1040, AA5083, AA6060 and AA7075 in ZnO-containing 4 M NaOH has been determined by using open circuit potential-time measurements (OCP), galvanostatic and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX) reveal that ZnO produces the inhibition effect by the formation of a zinc-containing deposit layer on the surface of aluminum electrodes. Although the influence of zincating on the performance of aluminum alloys and considering the amount of alloying elements such as zinc, magnesium and manganese in AA7075 and AA5083 alloys is much more than AA6060 one, the AA6060 aluminum exhibits negligible corrosion rate. Alloying aluminum with other elements and modifying the composition of the electrolyte is a necessary condition for reducing the self-corrosion of the aluminum anodes, whereas the proportion of the amount of additive elements is sufficient and important condition. As AA6060 with a low amount of Zn and Mg, but the high value of the ratio of (Mg/Zn) content (>400) can serve as a good galvanic anode in the alkaline media. - Highlights: • Decreasing the corrosion rate of tested alloys in 4 M NaOH solution specially AA6060. • Lowering the extent of anodic polarization at a current density of 50 mA cm{sup −2}. • High inhibitor efficiency about 97% for AA6060.

  7. A Kinetic Study on the Anodic Desorption of Interface Corrosion Inhibitor%缓蚀剂阳极脱附的动力学研究

    Institute of Scientific and Technical Information of China (English)

    汪的华; 江俊伟; 卜宪章; 甘复兴; 邹津耘

    2001-01-01

    The kinetics of inhibitor desorption on iron surface were investigated by potentiodynamic, differential polarization curve, cyclic polarization experiment, as well as potential step method. It was found that the anodic desorption exists an incubation time, and the measured kinetic curves of inhibitor desorption are “S” type, showing an autocatalytic process. The desorptin rate is depended on the desorption potential as well as the stability of inhibitor adsorption. The more stable the adsorption of inhibitoris, the more positive the Edes and the faster the desorption rateis. A new desorption mechanism was proposed on the basis of experimental results. According to this mechanism, the anodic desorption of inhibitor is more probably due to the competitive adsorption between inhibitor and intermediate produced in the anodic dissolution process of iron.%运用极化曲线、微分极化曲线、循环极化和恒电位暂态等方法研究了缓蚀剂阳极脱附的动力学行为,结果表明:缓蚀剂阳极脱附存在一个明显的诱导期,具有“S”型的脱附动力学曲线,呈自催化反应特征;外加电位越正,缓蚀剂脱附速度越快,脱附的诱导期越短;覆盖度高的稳定吸附层,脱附电位更正,脱附速度也更快.据此提出了缓蚀剂的阳极脱附是由于阳极极化条件下电极过程吸附态中间产物的竞争吸附使得缓蚀剂发生自加速脱附的新机制.

  8. Surface morphology and surface energy of anode materials influence power outputs in a multi-channel mediatorless bio-photovoltaic (BPV) system.

    Science.gov (United States)

    Bombelli, Paolo; Zarrouati, Marie; Thorne, Rebecca J; Schneider, Kenneth; Rowden, Stephen J L; Ali, Akin; Yunus, Kamran; Cameron, Petra J; Fisher, Adrian C; Ian Wilson, D; Howe, Christopher J; McCormick, Alistair J

    2012-09-21

    Bio-photovoltaic cells (BPVs) are a new photo-bio-electrochemical technology for harnessing solar energy using the photosynthetic activity of autotrophic organisms. Currently power outputs from BPVs are generally low and suffer from low efficiencies. However, a better understanding of the electrochemical interactions between the microbes and conductive materials will be likely to lead to increased power yields. In the current study, the fresh-water, filamentous cyanobacterium Pseudanabaena limnetica (also known as Oscillatoria limnetica) was investigated for exoelectrogenic activity. Biofilms of P. limnetica showed a significant photo response during light-dark cycling in BPVs under mediatorless conditions. A multi-channel BPV device was developed to compare quantitatively the performance of photosynthetic biofilms of this species using a variety of different anodic conductive materials: indium tin oxide-coated polyethylene terephthalate (ITO), stainless steel (SS), glass coated with a conductive polymer (PANI), and carbon paper (CP). Although biofilm growth rates were generally comparable on all materials tested, the amplitude of the photo response and achievable maximum power outputs were significantly different. ITO and SS demonstrated the largest photo responses, whereas CP showed the lowest power outputs under both light and dark conditions. Furthermore, differences in the ratios of light : dark power outputs indicated that the electrochemical interactions between photosynthetic microbes and the anode may differ under light and dark conditions depending on the anodic material used. Comparisons between BPV performances and material characteristics revealed that surface roughness and surface energy, particularly the ratio of non-polar to polar interactions (the CQ ratio), may be more important than available surface area in determining biocompatibility and maximum power outputs in microbial electrochemical systems. Notably, CP was readily outperformed by all

  9. The effect of polarity on dc arc development over an ice surface

    Energy Technology Data Exchange (ETDEWEB)

    Farokhi, S; Farzaneh, M; Fofana, I [NSERC/Hydro-Quebec/UQAC Industrial Chair on Atmospheric Icing of Power Network Equipment (CIGELE) and Canada Research Chair on Engineering of Power Network Atmospheric Icing (INGIVRE), Universite du Quebec a Chicoutimi, Quebec (Canada)

    2010-05-12

    Electrical/optical measurements have been carried out to study the dynamic behaviour of discharge on an ice surface. Significant differences in behaviour between positive and negative arcs have been revealed during discharge propagation. Also, its root structure, shape and velocity were found to be strongly polarity dependent. High-speed photography of the decays observed during discharge propagation showed two different patterns for dc positive and negative. Using simultaneous analysis of the captured pictures along with the current measurements at anode and cathode a mechanism describing the observed patterns is proposed. The effect of space charge regions observed around the main discharge channel is also discussed.

  10. Imaging with polarized neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, Martin; Manke, Ingo; Kardjilov, Nikolay; Hilger, Andre; Strobl, Markus; Banhart, John [Helmholtz Centre Berlin for Materials and Energy (Germany)], E-mail: manke@helmholtz-berlin.de

    2009-04-15

    Neutrons have zero net electrical charge and can thus penetrate deeply into matter, but their intrinsic magnetic moment makes them highly sensitive to magnetic fields. These properties have been combined with radiographic (2D) and tomographic (3D) imaging methods to provide a unique technique to probe macroscopic magnetic phenomena both within and around bulk matter. Based on the spin-rotation of a polarized neutron beam as it passes through a magnetic field, this method allows the direct, real-space visualization of magnetic field distributions. It has been used to investigate the Meissner effect in a type I (Pb) and a type II (YBCO) superconductor, flux trapping in a type I (Pb) superconductor, and the electromagnetic field associated with a direct current flowing in a solenoid. The latter results have been compared to predictions calculated using the Biot-Savart law and have been found to agree well.

  11. EUVE spectroscopy of polars

    Energy Technology Data Exchange (ETDEWEB)

    Mauche, C W

    1998-10-13

    An admittedly pedantic but hopefully useful and informative analysis is presented of the EUVE 70-180 Å spectra of nine polars. These spectra are fit with three different models - a blackbody, a pure-H stellar atmosphere, and a solar abundance stellar atmosphere|to reveal the presence of spectral features such as absorption lines and edges, and to investigate the sensitivity of the derived (kT, NH, solid angle) and inferred (fractional emitting area, bolometric luminosity) parameters to the model assumptions. Among the models tested, the blackbody model best describes the observed spectra, although the untested irradiated solar abundance stellar atmosphere model is likely a better overall description of the EUV/soft X-ray spectra

  12. Polarized Sources, Targets and Polarimetry

    Science.gov (United States)

    Ciullo, Guiseppe; Contalbrigo, Marco; Lenisa, P.

    2011-01-01

    Remarks on the history of workshops on "spin tools" / E. Steffens -- Polarized proton beams in RHIC / A. Zelenski -- The COSY/Julich polarized H[symbol] and D[symbol] ion source / O. Felden -- The new source of polarized ions for the JINR accelerator complex / V. V. Fimushkin -- Resonance effects in nuclear dichroism - an inexpensive source of tensor-polarized deuterons / H. Seyfarth -- Polarized electrons and positrons at the MESA accelerator / K. Aulenbacher -- Status report of the Darmstadt polarized electron injector / Y. Poltoratska -- The Mott polarimeter at MAMI / V. Tioukine -- Proton polarimetry at the relativistic heavy ion collider / Y. Makdisi -- Polarisation and polarimetry at HERA / B. Sobloher -- Polarisation measurement at the ILC with a Compton polarimeter / C. Bartels -- Time evolution of ground motion-dependent depolarisation at linear colliders / A. Hartin -- Electron beam polarimetry at low energies and its applications / R. Barday -- Polarized solid targets: recent progress and future prospects / C. D. Keith -- HD gas distillation and analysis for HD frozen spin targets / A. D'Angelo -- Electron spin resonance study of hydrogen and alkyl free radicals trapped in solid hydrogen aimed for dynamic nuclear polarization of solid HD / T. Kumada -- Change of ultrafast nuclear-spin polarization upon photoionization by a short laser pulse / T. Nakajima -- Radiation damage and recovery in polarized [symbol]NH[symbol] ammonia targets at Jefferson lab / J. D. Maxwell.Polarized solid proton target in low magnetic field and at high temperature / T. Uesaka -- Pulse structure dependence of the proton spin polarization rate / T. Kawahara -- Proton NMR in the large COMPASS [symbol]NH[symbol] target / J. Koivuniemi -- DNP with TEMPO and trityl radicals in deuterated polystyrene / L. Wang -- The CLIC electron and positron polarized sources / L. Rinolfi -- Status of high intensity polarized electron gun at MIT-Bates / E. Tsentalovich -- Target section for spin

  13. A field study of the effectiveness of sacrificial anodes in ballast tanks of merchant ships

    OpenAIRE

    De Baere, K.; Verstraelen, H; Lemmens, L.; Lenaerts, S.; Dewil, R; Van Ingelgem, Y.; Potters, G.

    2014-01-01

    Sacrificial anodes have become a standard practice for the protection of ballast tanks of merchant vessels against corrosive damage. A well protected tank should extend the life span of a ship and consequently enhances its economic value. An in situ survey comprising more than 100 merchant vessels provided the opportunity to measure the impact of these anodes on the life expectancy of these vessels. Contrary to the general belief of these anodes' beneficial effect, no significant difference w...

  14. The Silicon-To-Silicon Anodic Bonding Using Sputter Deposited Intermediate Glass Layer

    OpenAIRE

    TIWARI, R; Chandra, S.

    2011-01-01

    Glass-to-silicon anodic bonding is an attractive process for packaging of microelectronics devices and Micro-electro-mechanical Systems (MEMS). Silicon to silicon anodic bonding can also be accomplished by incorporating an intermediate glass layer. In the present work, silicon-to-silicon anodic bonding has been studied with an intermediate borosilicate glass layer deposited by RF magnetron sputtering process. The bonding was carried out at low dc voltage of about 48 V at 400 °C. Surface rough...

  15. 40 CFR Table 3 to Subpart Ll of... - Anode Bake Furnace Limits for Emission Averaging

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Anode Bake Furnace Limits for Emission... Reduction Plants Pt. 63, Subpt. LL, Table 3 Table 3 to Subpart LL of Part 63—Anode Bake Furnace Limits for Emission Averaging Number of furnaces Emission limit (lb/ton of anode) TF POM 2 0.11 0.17 3 0.090 0.17 4...

  16. Generation of soft X rays in a vircator with exploding anode foil

    Science.gov (United States)

    Dubinov, A. E.; Efimova, I. A.; Kargin, V. I.; Ryaslov, E. A.; Selemir, V. D.

    2007-06-01

    A soft X-ray generator is designed on the basis of a vircator the plasma anode of which is formed by electrical explosion of anode foil. The intensity of soft X-ray radiation (E γ > 20 eV) produced by vircators with a metal and plasma anode is measured. Microwave pulses indicating the presence of a virtual cathode in the plasma beam are detected.

  17. Pulsed laser deposited Si on multilayer graphene as anode material for lithium ion batteries

    OpenAIRE

    Gouri Radhakrishnan; Paul M. Adams; Brendan Foran; Michael V. Quinzio; Miles J. Brodie

    2013-01-01

    Pulsed laser deposition and chemical vapor deposition were used to deposit very thin silicon on multilayer graphene (MLG) on a nickel foam substrate for application as an anode material for lithium ion batteries. The as-grown material was directly fabricated into an anode without a binder, and tested in a half-cell configuration. Even under stressful voltage limits that accelerate degradation, the Si-MLG films displayed higher stability than Si-only electrodes. Post-cycling images of the anod...

  18. Carbon Fiber as Anode Material for Cathodic Prevention in Cementitious Materials

    OpenAIRE

    Zhang, Emma Qingnan; Tang, Luping; Zack, Thomas

    2016-01-01

    Cathodic prevention (CPre) technique is a promising method and has been used for the past two decades to prevent steel from corrosion in concrete structures. However, wide application of this technique has been restricted due to high costs of anode materials. In order to lower the cost and further improve this technique, carbon fiber composite anode has been introduced as an alternative anode material with affordable price and other outstanding properties. This paper presents the study of usi...

  19. Investigation of top-emitting OLEDs using molybdenum oxide as anode buffer layer

    Institute of Scientific and Technical Information of China (English)

    LIN Hui; YU Jun-sheng; ZHANG Wei

    2012-01-01

    A high-effective bottom anode is essential for high-performance top-emitting organic light-emitting devices (OLEDs).In this paper,Ag-based top-emitting OLEDs are investigated.Ag has the highest reflectivity for visible light among all metals,yet its hole-injection properties are not ideal for anodes of top-emitting OLED.The performance of the devices is significantly improved using the molybdenum oxide as anode buffer layer at the surface of Ag.By introducing the molybdenum oxide,the hole injection from Ag anodes into top-emitting OLED is largely enhanced with rather high reflectivity retained.

  20. Exploding metal film active anode source experiments on the LION extractor ion diode

    International Nuclear Information System (INIS)

    In this paper the authors report results using an extractor geometry magnetically insulated ion diode on the 0.5 TW LION accelerator. Experiments with an exploding metal film active anode plasma source (EMFAAPS) have shown that intense beams with significantly improved turn-on time compared to epoxy-filled-groove anodes can be produced. A new geometry, in which a plasma switch is used to provide the current path that explodes the thin film anode, has improved the ion efficiency (to typically 70%) compared with the previous scheme in which an electron collector on the anode provided this current. Leakage electron current is reduced when no collector is used