WorldWideScience

Sample records for alkali metal vapors

  1. Spill-Resistant Alkali-Metal-Vapor Dispenser

    Science.gov (United States)

    Klipstein, William

    2005-01-01

    A spill-resistant vessel has been developed for dispensing an alkali-metal vapor. Vapors of alkali metals (most commonly, cesium or rubidium, both of which melt at temperatures slightly above room temperature) are needed for atomic frequency standards, experiments in spectroscopy, and experiments in laser cooling. Although the present spill-resistant alkali-metal dispenser was originally intended for use in the low-gravity environment of outer space, it can also be used in normal Earth gravitation: indeed, its utility as a vapor source was confirmed by use of cesium in a ground apparatus. The vessel is made of copper. It consists of an assembly of cylinders and flanges, shown in the figure. The uppermost cylinder is a fill tube. Initially, the vessel is evacuated, the alkali metal charge is distilled into the bottom of the vessel, and then the fill tube is pinched closed to form a vacuum seal. The innermost cylinder serves as the outlet for the vapor, yet prevents spilling by protruding above the surface of the alkali metal, no matter which way or how far the vessel is tilted. In the event (unlikely in normal Earth gravitation) that any drops of molten alkali metal have been shaken loose by vibration and are floating freely, a mesh cap on top of the inner cylinder prevents the drops from drifting out with the vapor. Liquid containment of the equivalent of 1.2 grams of cesium was confirmed for all orientations with rubbing alcohol in one of the prototypes later used with cesium.

  2. On-chip fabrication of alkali-metal vapor cells utilizing an alkali-metal source tablet

    International Nuclear Information System (INIS)

    Tsujimoto, K; Hirai, Y; Sugano, K; Tsuchiya, T; Tabata, O; Ban, K; Mizutani, N

    2013-01-01

    We describe a novel on-chip microfabrication technique for the alkali-metal vapor cell of an optically pumped atomic magnetometer (OPAM), utilizing an alkali-metal source tablet (AMST). The newly proposed AMST is a millimeter-sized piece of porous alumina whose considerable surface area holds deposited alkali-metal chloride (KCl) and barium azide (BaN 6 ), source materials that effectively produce alkali-metal vapor at less than 400 °C. Our experiments indicated that the most effective pore size of the AMST is between 60 and 170 µm. The thickness of an insulating glass spacer holding the AMST was designed to confine generated alkali metal to the interior of the vapor cell during its production, and an integrated silicon heater was designed to seal the device using a glass frit, melted at an optimum temperature range of 460–490 °C that was determined by finite element method thermal simulation. The proposed design and AMST were used to successfully fabricate a K cell that was then operated as an OPAM with a measured sensitivity of 50 pT. These results demonstrate that the proposed concept for on-chip microfabrication of alkali-metal vapor cells may lead to effective replacement of conventional glassworking approaches. (paper)

  3. Electric conductivity of alkali metal vapors in the region of critical point

    International Nuclear Information System (INIS)

    Likal'ter, A.A.

    1982-01-01

    A behaviour of alkali metal conductivity in the vicinity of a critical point has been analyzed on the base of deVeloped representations on a vapor state. A phenomenological conductivity theory has been developed, which is in a good agreement with experimental data obtained

  4. Saturated vapor pressure over molten mixtures of GaCl3 and alkali metal chlorides

    International Nuclear Information System (INIS)

    Salyulev, A.B.; Smolenskij, V.V.; Moskalenko, N.I.

    2004-01-01

    Volatilities of GaCl 3 and alkali metal chlorides over diluted (up to 3 mol %) solutions of GaCl 3 in LiCl, NaCl, KCl, RbCl, and CsCl were measured at 1100 K by dynamic and indirect static methods. Chemical composition of saturated vapor over the mixed melts was determined. Partial pressures of the components were calculated. Their values depend essentially on specific alkali metal cation and on concentration of GaCl 3 ; their variation permits altering parameters of GaCl 3 distillation from the salt melt in a wide range [ru

  5. (abstract) Experimental and Modeling Studies of the Exchange Current at the Alkali Beta'-Alumina/Porous Electrode/Alkali Metal Vapor Three Phase Boundary

    Science.gov (United States)

    Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Underwood, M. L.; O'Connor, D.; Kikkert, S.

    1993-01-01

    The microscopic mechanism of the alkali ion-electron recombination reaction at the three phase boundary zone formed by a porous metal electrode in the alkali vapor on the surface of an alkali beta'-alumina solid electrolyte (BASE) ceramic has been studied by comparison of the expected rates for the three simplest reaction mechanisms with known temperature dependent rate data; and the physical parameters of typical porous metal electrode/BASE/alkali metal vapor reaction zones. The three simplest reactions are tunneling of electrons from the alkali coated electrode to a surface bound alkali metal ion; emission of an electron from the electrode with subsequent capture by a surface bound alkali metal ion; and thermal emission of an alkali cation from the BASE and its capture on the porous metal electrode surface where it may recombine with an electron. Only the first reaction adequately accounts for both the high observed rate and its temperature dependence. New results include crude modeling of simple, one step, three phase, solid/solid/gas electrochemical reaction.

  6. Investigation of anti-Relaxation coatings for alkali-metal vapor cells using surface science techniques

    Energy Technology Data Exchange (ETDEWEB)

    Seltzer, S. J.; Michalak, D. J.; Donaldson, M. H.; Balabas, M. V.; Barber, S. K.; Bernasek, S. L.; Bouchiat, M.-A.; Hexemer, A.; Hibberd, A. M.; Jackson Kimball, D. F.; Jaye, C.; Karaulanov, T.; Narducci, F. A.; Rangwala, S. A.; Robinson, H. G.; Shmakov, A. K.; Voronov, D. L.; Yashchuk, V. V.; Pines, A.; Budker, D.

    2010-10-11

    Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of antirelaxation surface coatings in order to preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an atom to experience up to 10?000 collisions with the walls of its container without depolarizing, but the details of its operation remain poorly understood. We apply modern surface and bulk techniques to the study of paraffin coatings in order to characterize the properties that enable the effective preservation of alkali spin polarization. These methods include Fourier transform infrared spectroscopy, differential scanning calorimetry, atomic force microscopy, near-edge x-ray absorption fine structure spectroscopy, and x-ray photoelectron spectroscopy. We also compare the light-induced atomic desorption yields of several different paraffin materials. Experimental results include the determination that crystallinity of the coating material is unnecessary, and the detection of C=C double bonds present within a particular class of effective paraffin coatings. Further study should lead to the development of more robust paraffin antirelaxation coatings, as well as the design and synthesis of new classes of coating materials.

  7. Mass-spectrometric study of ion clustering in alkali-metal hydroxide vapor: cluster-ion energy and structural characteristics

    International Nuclear Information System (INIS)

    Kudin, L.S.; Butman, M.F.; Krasnov, K.S.

    1986-01-01

    Various positive and negative ions have been recorded in the equilibrium vapors from alkali-metal hydroxides: M/sup +/-/, OH - , O - , MO - , MOH - , and X/sup +/-/ (MOH)/sub n/, where X = M/sup +/-/, OH - , n = 1-6. The equilibrium constants have been measured for X/sup +/-/(MOH)/sub n/ = x/sup +/-/ + nMOH(k), n = 1-3, and the enthalpies of reaction have been determined, from which the enthalpies of formation and dissociation energies of X/sup +/-/ (MOH)/sub n/ have been calculated. The relative stabilities of the ions in the series from Na to Cs are examined

  8. Alkali metal hydride formation

    International Nuclear Information System (INIS)

    1976-01-01

    The present invention relates to a method of producing alkali metal hydrides by absorbing hydrogen gas under pressure into a mixture of lower alkyl mono amines and alkali metal alkyl amides selected from sodium and potassium amides formed from said amines. The present invention also includes purification of a mixture of the amines and amides which contain impurities, such as is used as a catalytic exchange liquid in the enrichment of deuterium, involving the formation of the alkali metal hydride

  9. Methods of recovering alkali metals

    Science.gov (United States)

    Krumhansl, James L; Rigali, Mark J

    2014-03-04

    Approaches for alkali metal extraction, sequestration and recovery are described. For example, a method of recovering alkali metals includes providing a CST or CST-like (e.g., small pore zeolite) material. The alkali metal species is scavenged from the liquid mixture by the CST or CST-like material. The alkali metal species is extracted from the CST or CST-like material.

  10. Alkali metal ion battery with bimetallic electrode

    Science.gov (United States)

    Boysen, Dane A; Bradwell, David J; Jiang, Kai; Kim, Hojong; Ortiz, Luis A; Sadoway, Donald R; Tomaszowska, Alina A; Wei, Weifeng; Wang, Kangli

    2015-04-07

    Electrochemical cells having molten electrodes having an alkali metal provide receipt and delivery of power by transporting atoms of the alkali metal between electrode environments of disparate chemical potentials through an electrochemical pathway comprising a salt of the alkali metal. The chemical potential of the alkali metal is decreased when combined with one or more non-alkali metals, thus producing a voltage between an electrode comprising the molten the alkali metal and the electrode comprising the combined alkali/non-alkali metals.

  11. Terahertz radiation in alkali vapor plasmas

    International Nuclear Information System (INIS)

    Sun, Xuan; Zhang, X.-C.

    2014-01-01

    By taking advantage of low ionization potentials of alkali atoms, we demonstrate terahertz wave generation from cesium and rubidium vapor plasmas with an amplitude nearly one order of magnitude larger than that from nitrogen gas at low pressure (0.02–0.5 Torr). The observed phenomena are explained by the numerical modeling based upon electron tunneling ionization

  12. Upgrading platform using alkali metals

    Science.gov (United States)

    Gordon, John Howard

    2014-09-09

    A process for removing sulfur, nitrogen or metals from an oil feedstock (such as heavy oil, bitumen, shale oil, etc.) The method involves reacting the oil feedstock with an alkali metal and a radical capping substance. The alkali metal reacts with the metal, sulfur or nitrogen content to form one or more inorganic products and the radical capping substance reacts with the carbon and hydrogen content to form a hydrocarbon phase. The inorganic products may then be separated out from the hydrocarbon phase.

  13. Alkali metal and alkali earth metal gadolinium halide scintillators

    Science.gov (United States)

    Bourret-Courchesne, Edith; Derenzo, Stephen E.; Parms, Shameka; Porter-Chapman, Yetta D.; Wiggins, Latoria K.

    2016-08-02

    The present invention provides for a composition comprising an inorganic scintillator comprising a gadolinium halide, optionally cerium-doped, having the formula A.sub.nGdX.sub.m:Ce; wherein A is nothing, an alkali metal, such as Li or Na, or an alkali earth metal, such as Ba; X is F, Br, Cl, or I; n is an integer from 1 to 2; m is an integer from 4 to 7; and the molar percent of cerium is 0% to 100%. The gadolinium halides or alkali earth metal gadolinium halides are scintillators and produce a bright luminescence upon irradiation by a suitable radiation.

  14. Process for the disposal of alkali metals

    International Nuclear Information System (INIS)

    Lewis, L.C.

    1979-01-01

    The invention describes a method of disposing of alkali metals by forming a solid waste for storage. The method comprises preparing an aqueous disposal solution of at least 55 weight percent alkali metal hydroxide, heating the alkali metal to melting temperature to form a feed solution, and spraying the molten feed solution into the disposal solution. The alkali metal reacts with the water in the disposal solution in a controlled reaction which produces alkali metal hydroxide, hydrogen and heat and thereby forms a solution of alkali metal hydroxides. Water is added to the solution in amounts sufficient to maintain the concentration of alkali metal hydroxides in the solution at 70 to 90 weight percent, and to maintain the temperature of the solution at about the boiling point. Removing and cooling the alkali metal hydroxide solution thereby forms a solid waste for storage. The method is particularly applicable to radioactive alkali metal reactor coolant. (auth)

  15. Method of making alkali metal hydrides

    Science.gov (United States)

    Pecharsky, Vitalij K.; Gupta, Shalabh; Pruski, Marek; Hlova, Ihor; Castle, Andra

    2017-05-30

    A method is provided for making alkali metal hydrides by mechanochemically reacting alkali metal and hydrogen gas under mild temperature (e.g room temperature) and hydrogen pressure conditions without the need for catalyst, solvent, and intentional heating or cooling.

  16. Alkali Metal Thermal to Electric Converter (AMTEC) Technology Development for Potential Deep Space Scientific Missions

    Science.gov (United States)

    Mondt, J.; Sievers, R.

    1998-01-01

    This paper describes the alkali metal thermal to electric converter (AMTEC) technology development effort over the past year. The vapor-vapor AMTEC cell technology is being developed for use with either a solar or nuclear heat sources for space.

  17. Examination of Organic Vapor Adsorption onto Alkali Metal and Halide Atomic Ions by using Ion Mobility Mass Spectrometry.

    Science.gov (United States)

    Maiβer, Anne; Hogan, Christopher J

    2017-11-03

    We utilize ion mobility mass spectrometry with an atmospheric pressure differential mobility analyzer coupled to a time-of-flight mass spectrometer (DMA-MS) to examine the formation of ion-vapor molecule complexes with seed ions of K + , Rb + , Cs + , Br - , and I - exposed to n-butanol and n-nonane vapor under subsaturated conditions. Ion-vapor molecule complex formation is indicated by a shift in the apparent mobility of each ion. Measurement results are compared to predicted mobility shifts based upon the Kelvin-Thomson equation, which is commonly used in predicting rates of ion-induced nucleation. We find that n-butanol at saturation ratios as low as 0.03 readily binds to all seed ions, leading to mobility shifts in excess of 35 %. Conversely, the binding of n-nonane is not detectable for any ion for saturation ratios in the 0-0.27 range. An inverse correlation between the ionic radius of the initial seed and the extent of n-butanol uptake is observed, such that at elevated n-butanol concentrations, the smallest ion (K + ) has the smallest apparent mobility and the largest (I - ) has the largest apparent mobility. Though the differences in behavior of the two vapor molecules types examined and the observed effect of ionic seed radius are not accounted for by the Kelvin-Thomson equation, its predictions are in good agreement with measured mobility shifts for Rb + , Cs + , and Br - in the presence of n-butanol (typically within 10 % of measurements). © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  18. Stabilization of aqueous alkali metal aluminate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Allenson, S.J.

    1988-03-29

    A method of stabilizing an aqueous solution of alkali metal aluminate is described comprising: admixing an aqueous solution of alkali metal aluminate having a pH of at least 10 with a sufficient amount of vinyl polymer having pendant carboxylate groups to form a solution containing from 0.1 to 2.0 weight percent of an anionic vinyl polymer based on alkali metal aluminate solids. The anionic vinyl polymer has an average molecular weight of at least 500,000.

  19. Alkali-vapor laser-excimer pumped alkali laser

    International Nuclear Information System (INIS)

    Yue Desheng; Li Wenyu; Wang Hongyan; Yang Zining; Xu Xiaojun

    2012-01-01

    Based on the research internal and overseas, the principle of the excimer pumped alkali laser (XPAL) is explained, and the advantages and disadvantages of the XPAL are analyzed. Taking into consideration the difficulties that the diode pumped alkali laser (DPAL) meets on its development, the ability to solve or avoid these difficulties of XPAL is also analyzed. By summing up the achievements of the XPAL, the possible further prospect is proposed. The XPAL is of possibility to improve the performance of the DPAL. (authors)

  20. Alkali metal and alkali metal hydroxide intercalates of the layered transition metal disulfides

    International Nuclear Information System (INIS)

    Kanzaki, Y.; Konuma, M.; Matsumoto, O.

    1981-01-01

    The intercalation reaction of some layered transition metal disulfides with alkali metals, alkali metal hydroxides, and tetraalkylammonium hydroxides were investigated. The alkali metal intercalates were prepared in the respective metal-hexamethylphosphoric triamide solutions in vaccuo, and the hydroxide intercalates in aqueous hydroxide solutions. According to the intercalation reaction, the c-lattice parameter was increased, and the increase indicated the expansion of the interlayer distance. In the case of alkali metal intercalates, the expansion of the interlayer distance increased continuously, corresponding to the atomic radius of the alkali metal. On the other hand, the hydroxide intercalates showed discrete expansion corresponding to the effective ionic radius of the intercalated cation. All intercalates of TaS 2 amd NbS 2 were superconductors. The expansion of the interlayer distance tended to increase the superconducting transition temperature in the intercalates of TaS 2 and vice versa in those of NbS 2 . (orig.)

  1. The chemistry of the liquid alkali metals

    International Nuclear Information System (INIS)

    Addison, C.C.

    1984-01-01

    A study of liquid alkali metals. It encourages comparison with molecular solvents in chapter covering the nature and reactivity of dissolved species, solvation, solubility and electrical conductivity of solutions. It demonstrates lab techniques unique to liquid alkali metals. It discusses large-scale applications from storage batteries to sodium-cooled reactors and future fusion reactors, and associated technological problems. Contents: Some Basic Physical and Chemical Properties; Manipulation of the Liquids; The Chemistry of Purification Methods; Species Formed by Dissolved Elements; Solubilities and Analytical Methods; Alkali Metal Mixtures; Solvation in Liquid Metal; Reactions Between Liquid Alkali Metals and Water; Reactions of Nitrogen with Lithium and the Group II Metals in Liquid Sodium; The Formation, Dissociation and Stability of Heteronuclear Polyatomic Anions; Reactions of the Liquid Alkali Metals and Their Alloys with Simple Alipatic Hydrocarbons; Reactions of the Liquid Alkali Metals with Some Halogen Compounds; Hydrogen, Oxygen and Carbon Meters; Surface Chemistry and Wetting; Corrosion of Transition Metals by the Liquid Alkali Metals; Modern Applications of the Liquid Alkali Metals

  2. The alkali metals: 200 years of surprises.

    Science.gov (United States)

    Dye, James L

    2015-03-13

    Alkali metal compounds have been known since antiquity. In 1807, Sir Humphry Davy surprised everyone by electrolytically preparing (and naming) potassium and sodium metals. In 1808, he noted their interaction with ammonia, which, 100 years later, was attributed to solvated electrons. After 1960, pulse radiolysis of nearly any solvent produced solvated electrons, which became one of the most studied species in chemistry. In 1968, alkali metal solutions in amines and ethers were shown to contain alkali metal anions in addition to solvated electrons. The advent of crown ethers and cryptands as complexants for alkali cations greatly enhanced alkali metal solubilities. This permitted us to prepare a crystalline salt of Na(-) in 1974, followed by 30 other alkalides with Na(-), K(-), Rb(-) and Cs(-) anions. This firmly established the -1 oxidation state of alkali metals. The synthesis of alkalides led to the crystallization of electrides, with trapped electrons as the anions. Electrides have a variety of electronic and magnetic properties, depending on the geometries and connectivities of the trapping sites. In 2009, the final surprise was the experimental demonstration that alkali metals under high pressure lose their metallic character as the electrons are localized in voids between the alkali cations to become high-pressure electrides! © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  3. Process for the disposal of alkali metals

    International Nuclear Information System (INIS)

    Lewis, L.C.

    1977-01-01

    Large quantities of alkali metals may be safely reacted for ultimate disposal by contact with a hot concentrated caustic solution. The alkali metals react with water in the caustic solution in a controlled reaction while steam dilutes the hydrogen formed by the reaction to a safe level. 6 claims

  4. Method of handling radioactive alkali metal waste

    Science.gov (United States)

    Wolson, R.D.; McPheeters, C.C.

    Radioactive alkali metal is mixed with particulate silica in a rotary drum reactor in which the alkali metal is converted to the monoxide during rotation of the reactor to produce particulate silica coated with the alkali metal monoxide suitable as a feed material to make a glass for storing radioactive material. Silica particles, the majority of which pass through a 95 mesh screen or preferably through a 200 mesh screen, are employed in this process, and the preferred weight ratio of silica to alkali metal is 7 to 1 in order to produce a feed material for the final glass product having a silica to alkali metal monoxide ratio of about 5 to 1.

  5. Method of handling radioactive alkali metal waste

    International Nuclear Information System (INIS)

    Mcpheeters, C.C.; Wolson, R.D.

    1980-01-01

    Radioactive alkali metal is mixed with particulate silica in a rotary drum reactor in which the alkali metal is converted to the monoxide during rotation of the reactor to produce particulate silica coated with the alkali metal monoxide suitable as a feed material to make a glass for storing radioactive material. Silica particles, the majority of which pass through a 95 mesh screen or preferably through a 200 mesh screen, are employed in this process, and the preferred weight ratio of silica to alkali metal is 7 to 1 in order to produce a feed material for the final glass product having a silica to alkali metal monoxide ratio of about 5 to 1

  6. Process to separate alkali metal salts from alkali metal reacted hydrocarbons

    Science.gov (United States)

    Gordon, John Howard; Alvare, Javier; Larsen, Dennis; Killpack, Jeff

    2017-06-27

    A process to facilitate gravimetric separation of alkali metal salts, such as alkali metal sulfides and polysulfides, from alkali metal reacted hydrocarbons. The disclosed process is part of a method of upgrading a hydrocarbon feedstock by removing heteroatoms and/or one or more heavy metals from the hydrocarbon feedstock composition. This method reacts the oil feedstock with an alkali metal and an upgradant hydrocarbon. The alkali metal reacts with a portion of the heteroatoms and/or one or more heavy metals to form an inorganic phase containing alkali metal salts and reduced heavy metals, and an upgraded hydrocarbon feedstock. The inorganic phase may be gravimetrically separated from the upgraded hydrocarbon feedstock after mixing at a temperature between about 350.degree. C. to 400.degree. C. for a time period between about 15 minutes and 2 hours.

  7. Corrosion and compatibility in liquid alkali metals

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    The literature dealing with liquid alkali metal corrosion of vanadium and its alloys is reviewed in the following subsections. Attention is given to both lithium and sodium data. Preceding this review, a brief outline of the current state of understanding of liquid metal corrosion mechanisms is provided

  8. Density functional study of ferromagnetism in alkali metal thin films

    Indian Academy of Sciences (India)

    model (UJM), and it is argued that within LSDA or GGA, alkali metal thin films cannot be claimed to have an FM ground state. Relevance of these results to the experiments on transition metal-doped alkali metal thin films and bulk hosts are also discussed. Keywords. Alkali metal; thin films; magnetism; density functional ...

  9. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151) is...

  10. 40 CFR 721.4740 - Alkali metal nitrites.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject to reporting. (1) The category of chemical substances which are nitrites of the alkali metals (Group IA in the...

  11. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for the...

  12. Alkali element depletion by core formation and vaporization on the early Earth

    Science.gov (United States)

    Lodders, K.; Fegley, B., Jr.

    1994-01-01

    The depletion of Na, K, Rb, and Cs in the Earth's upper mantle and crust relative to their abundances in chondrites is a long standing problem in geochemistry. Here we consider two commonly invoked mechanisms, namely core formation, and vaporization, for producing the observed depletions. Our models predict that a significant percentage of the Earth's bulk alkali element inventory is in the core (30 percent for Na, 52 percent for K, 74 percent for Rb, and 92 percent for Cs). These predictions agree with independent estimates from nebular volatility trends and (for K) from terrestrial heat flow data. Our models also predict that vaporization and thermal escape during planetary accretion are unlikely to produce the observed alkali element depletion pattern. However, loss during the putative giant impact which formed the Moon cannot be ruled out. Experimental, observational, and theoretical tests of our predictions are also described. Alkali element partitioning into the Earth's core was modeled by assuming that alkali element partitioning during core formation on the aubrite parent body (APB) is analogous to that on the early Earth. The analogy is reasonable for three reasons. First, the enstatite meteorites are the only known meteorites with the same oxygen isotope systematics as the Earth-Moon system. Second, the large core size of the Earth and the V depletion in the mantle requires accretion from planetesimals as reduced as the enstatite chondrites. Third, experimental studies of K partitioning between silicate and metal plus sulfide show that more K goes into the metal plus sulfide at higher pressures than at one atmosphere pressure. Thus partitioning in the relatively low pressure natural laboratory of the APB is a good guide to alkali elemental partitioning during the growth of the Earth.

  13. Method for the safe disposal of alkali metal

    Science.gov (United States)

    Johnson, Terry R.

    1977-01-01

    Alkali metals such as those employed in liquid metal coolant systems can be safely reacted to form hydroxides by first dissolving the alkali metal in relatively inert metals such as lead or bismuth. The alloy thus formed is contacted with a molten salt including the alkali metal hydroxide and possibly the alkali metal carbonate in the presence of oxygen. This oxidizes the alkali metal to an oxide which is soluble within the molten salt. The salt is separated and contacted with steam or steam-CO.sub.2 mixture to convert the alkali metal oxide to the hydroxide. These reactions can be conducted with minimal hydrogen evolution and with the heat of reaction distributed between the several reaction steps.

  14. Method for the safe disposal of alkali metal

    International Nuclear Information System (INIS)

    Johnson, T.R.

    1977-01-01

    Alkali metals such as those employed in liquid metal coolant systems can be safely reacted to form hydroxides by first dissolving the alkali metal in relatively inert metals such as lead or bismuth. The alloy thus formed is contacted with a molten salt including the alkali metal hydroxide and possibly the alkali metal carbonate in the presence of oxygen. This oxidizes the alkali metal to an oxide which is soluble within the molten salt. The salt is separated and contacted with steam or steam--CO 2 mixture to convert the alkali metal oxide to the hydroxide. These reactions can be conducted with minimal hydrogen evolution and with the heat of reaction distributed between the several reaction steps. 5 claims, 1 figure

  15. Density functional study of ferromagnetism in alkali metal thin films

    Indian Academy of Sciences (India)

    thickness uniform jellium model (UJM), and it is argued that within LSDA or GGA, alkali metal thin films cannot be claimed to have an FM ground state. Relevance of these results to the experiments on transition metal-doped alkali metal thin films ...

  16. Coprecipitation of alkali metal ions with calcium carbonate

    International Nuclear Information System (INIS)

    Okumura, Minoru; Kitano, Yasushi

    1986-01-01

    The coprecipitation of alkali metal ions Li + , Na + , K + and Rb + with calcium carbonate has been studied experimentally and the following results have been obtained: (1) Alkali metal ions are more easily coprecipitated with aragonite than with calcite. (2) The relationship between the amounts of alkali metal ions coprecipitated with aragonite and their ionic radii shows a parabolic curve with a peak located at Na + which has approximately the same ionic radius as Ca 2+ . (3) However, the amounts of alkali metal ions coprecipitated with calcite decrease with increasing ionic radius of alkali metals. (4) Our results support the hypothesis that (a) alkali metals are in interstitial positions in the crystal structure of calcite and do not substitute for Ca 2+ in the lattice, but (b) in aragonite, alkali metals substitute for Ca 2+ in the crystal structure. (5) Magnesium ions in the parent solution increase the amounts of alkali metal ions (Li + , Na + , K + and Rb + ) coprecipitated with calcite but decrease those with aragonite. (6) Sodium-bearing aragonite decreases the incorporation of other alkali metal ions (Li + , K + and Rb + ) into the aragonite. (author)

  17. Vibrations of alkali metal overlayers on metal surfaces

    International Nuclear Information System (INIS)

    Rusina, G G; Eremeev, S V; Borisova, S D; Echenique, P M; Chulkov, E V; Benedek, G

    2008-01-01

    We review the current progress in the understanding of vibrations of alkalis adsorbed on metal surfaces. The analysis of alkali vibrations was made on the basis of available theoretical and experimental results. We also include in this discussion our recent calculations of vibrations in K/Pt(111) and Li(Na)/Cu(001) systems. The dependence of alkali adlayer localized modes on atomic mass, adsorption position and coverage as well as the dependence of vertical vibration frequency on the substrate orientation is discussed. The square root of atomic mass dependence of the vertical vibration energy has been confirmed by using computational data for alkalis on the Al(111) and Cu(001) substrates. We have confirmed that in a wide range of submonolayer coverages the stretch mode energy remains nearly constant while the energy of in-plane polarized modes increases with the increase of alkali coverage. It was shown that the spectrum of both stretch and in-plane vibrations can be very sensitive to the adsorption position of alkali atoms and substrate orientation

  18. Electric conductivity of alkali metal perchlorates

    International Nuclear Information System (INIS)

    Ulikhin, A.S.; Uvarov, N.F.

    2007-01-01

    Ionic conductivity of high-temperature phases of alkali metal perchlorates, MClO 4 , where M stands for Li-Cs, is studied. It is found that the conductivity passes through a minimum with increasing radius of cation, and KClO 4 exhibits the lowest conductivity. This is explained by a decrease in the relative size of conduction channel, which hampers the cation transfer, and an increase in the relative free volume. The free-volume increase promotes the perchlorate anion reorientation and reduces the activation energy for ion transfer by the paddle-wheel mechanism; as a result, the conductivity increases [ru

  19. Cathode architectures for alkali metal / oxygen batteries

    Science.gov (United States)

    Visco, Steven J; Nimon, Vitaliy; De Jonghe, Lutgard C; Volfkovich, Yury; Bograchev, Daniil

    2015-01-13

    Electrochemical energy storage devices, such as alkali metal-oxygen battery cells (e.g., non-aqueous lithium-air cells), have a cathode architecture with a porous structure and pore composition that is tailored to improve cell performance, especially as it pertains to one or more of the discharge/charge rate, cycle life, and delivered ampere-hour capacity. A porous cathode architecture having a pore volume that is derived from pores of varying radii wherein the pore size distribution is tailored as a function of the architecture thickness is one way to achieve one or more of the aforementioned cell performance improvements.

  20. Measurement of alkali-vapor emission from pressurized fluidized-bed combustion of Illinois coals

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.H.D.; Teats, F.G.; Swift, W.M. (Argonne National Lab., IL (United States)); Banerjee, D.D. (Illinois Clean Coal Inst., Carterville, IL (United States))

    1993-01-01

    Two Illinois Herrin No. 6 coals and one Illinois Springfield No. 5 coal were separately combusted in a laboratory-scale (15-cm dia) pressurized fluidized-bed combustor (PFBC) combined with an alkali sorber. These coals were combusted in a fluidized bed of Tymochtee dolomite at temperatures ranging from 910 to 950[degree]C and a system pressure of 9.2 atm absolute. Alkali-vapor emission (Na and K) in the PFBC flue gas was determined by the analytical activated-bauxite sorber bed technique developed at Argonne National Laboratory. The test results showed that sodium is the major alkali-vapor species present in the PFBC flue gas, and that the level of sodium-vapor emission increases linearly with both Na and Cl contents in the coals. This suggests that the sodium-vapor emission results from direct vaporization of NaCl present in the coals. The measured alkali-vapor concentration (Na + K), 67 to 190 ppbW, is more than 2.5 times greater than the allowable alkali limit of 24 ppb for an industrial gas turbine. Combusting these coals in a PFBC for power generation may require developing a method to control alkali vapors.

  1. Measurement of alkali-vapor emission from pressurized fluidized-bed combustion of Illinois coals

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.H.D.; Teats, F.G.; Swift, W.M. [Argonne National Lab., IL (United States); Banerjee, D.D. [Illinois Clean Coal Inst., Carterville, IL (United States)

    1993-04-01

    Two Illinois Herrin No. 6 coals and one Illinois Springfield No. 5 coal were separately combusted in a laboratory-scale (15-cm dia) pressurized fluidized-bed combustor (PFBC) combined with an alkali sorber. These coals were combusted in a fluidized bed of Tymochtee dolomite at temperatures ranging from 910 to 950{degree}C and a system pressure of 9.2 atm absolute. Alkali-vapor emission (Na and K) in the PFBC flue gas was determined by the analytical activated-bauxite sorber bed technique developed at Argonne National Laboratory. The test results showed that sodium is the major alkali-vapor species present in the PFBC flue gas, and that the level of sodium-vapor emission increases linearly with both Na and Cl contents in the coals. This suggests that the sodium-vapor emission results from direct vaporization of NaCl present in the coals. The measured alkali-vapor concentration (Na + K), 67 to 190 ppbW, is more than 2.5 times greater than the allowable alkali limit of 24 ppb for an industrial gas turbine. Combusting these coals in a PFBC for power generation may require developing a method to control alkali vapors.

  2. COMPLEX FLUORIDES OF PLUTONIUM AND AN ALKALI METAL

    Science.gov (United States)

    Seaborg, G.T.

    1960-08-01

    A method is given for precipitating alkali metal plutonium fluorides. such as KPuF/sub 5/, KPu/sub 2/F/sub 9/, NaPuF/sub 5/, and RbPuF/sub 5/, from an aqueous plutonium(IV) solution by adding hydrogen fluoride and alkali-metal- fluoride.

  3. IRMPD Action Spectroscopy of Alkali Metal Cation-Cytosine Complexes: Effects of Alkali Metal Cation Size on Gas Phase Conformation

    NARCIS (Netherlands)

    Yang, B.; Wu, R.R.; Polfer, N.C.; Berden, G.; Oomens, J.; Rodgers, M.T.

    2013-01-01

    The gas-phase structures of alkali metal cation-cytosine complexes generated by electrospray ionization are probed via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical calculations. IRMPD action spectra of five alkali metal cation-cytosine complexes exhibit both

  4. Alkali metal-refractory metal biphase electrode for AMTEC

    Science.gov (United States)

    Williams, Roger M. (Inventor); Bankston, Clyde P. (Inventor); Cole, Terry (Inventor); Khanna, Satish K. (Inventor); Jeffries-Nakamura, Barbara (Inventor); Wheeler, Bob L. (Inventor)

    1989-01-01

    An electrode having increased output with slower degradation is formed of a film applied to a beta-alumina solid electrolyte (BASE). The film comprises a refractory first metal M.sup.1 such as a platinum group metal, suitably platinum or rhodium, capable of forming a liquid or a strong surface adsorption phase with sodium at the operating temperature of an alkali metal thermoelectric converter (AMTEC) and a second refractory metal insoluble in sodium or the NaM.sup.1 liquid phase such as a Group IVB, VB or VIB metal, suitably tungsten, molybdenum, tantalum or niobium. The liquid phase or surface film provides fast transport through the electrode while the insoluble refractory metal provides a structural matrix for the electrode during operation. A trilayer structure that is stable and not subject to deadhesion comprises a first, thin layer of tungsten, an intermediate co-deposited layer of tungsten-platinum and a thin surface layer of platinum.

  5. Charge transfer in gold--alkali-metal systems

    International Nuclear Information System (INIS)

    Watson, R.E.; Weinert, M.

    1994-01-01

    Based on conventional electronegativity arguments, gold--alkali-metal compounds are expected to be among the most ''ionic'' of metallic compounds. The concepts of ionicity and charge transfer are difficult to quantify. However, the changes in bonding in the 50/50 Au--alkali-metal systems between the elemental metals and the compounds are so severe that observations can readily be made concerning their character. The results, as obtained from self-consistent electronic-structure calculations, lead to the apparently odd observation that the electron density at the alkali-metal sites in the compound increases significantly and this involves high l componennts in the charge density. This increase, however, can be attributed to Au-like orbitals spatially overlapping the alkali-metal sites. In a chemical sense, it is reasonable to consider the alkali-metal transferring charge to these Au orbitals. While normally the difference in heats of formation between muffin-tin and full-potential calculations for transition-metal--transition-metal and transition-metal--main-group (e.g., Al) compounds having high site symmetry are small, for the gold--alkali-metal systems, the changes in bonding in the compounds cause differences of ∼0.5 eV/atom between the two classes of potential. Any serious estimate of the electronic structure in these systems must account for these aspherical bonding charges. The origin of the semiconducting behavior of the heavy-alkali-metal Au compounds is shown to arise from a combination of the Au-Au separations and the ionic character of the compounds; the light-alkali-metal Au compounds, with their smaller Au-Au separations, do not have a semiconducting gap. Core-level shifts and isomer shifts are also briefly discussed

  6. Controlled in-situ dissolution of an alkali metal

    Science.gov (United States)

    Jones, Jeffrey Donald; Dooley, Kirk John; Tolman, David Donald

    2012-09-11

    A method for the controllable dissolution of one or more alkali metals from a vessel containing a one or more alkali metals and/or one or more partially passivated alkali metals. The vessel preferably comprising a sodium, NaK or other alkali metal-cooled nuclear reactor that has been used. The alkali metal, preferably sodium, potassium or a combination thereof, in the vessel is exposed to a treatment liquid, preferably an acidic liquid, more preferably citric acid. Preferably, the treatment liquid is maintained in continuous motion relative to any surface of unreacted alkali metal with which the treatment liquid is in contact. The treatment liquid is preferably pumped into the vessel containing the one or more alkali metals and the resulting fluid is extracted and optionally further processed. Preferably, the resulting off-gases are processed by an off-gas treatment system and the resulting liquids are processed by a liquid disposal system. In one preferred embodiment, an inert gas is pumped into the vessel along with the treatment liquid.

  7. Metal analyses of ash derived alkalis from banana and plantain ...

    African Journals Online (AJOL)

    The objective of this work was to determine the metal content of plantain and banana peels ash derived alkali and the possibility of using it as alternate and cheap source of alkali in soap industry. This was done by ashing the peels and dissolving it in de-ionised water to achieve the corresponding hydroxides with pH above ...

  8. Superconductivity and electrical resistivity in alkali metal doped ...

    Indian Academy of Sciences (India)

    Unknown

    Fullerenes; alkali-C60 phonon; on-ball-C60 phonon; pressure effect; electrical resistivity. 1. Introduction. Buckminsterfullerenes are known to make compounds with alkali metals intensively studied mainly due to superconductivity and the variation of compounds (Hebard et al 1991; Holczer et al 1991; Tanigaki et al 1991).

  9. Recent materials compatibility studies in refractory metal-alkali metal systems for space power applications.

    Science.gov (United States)

    Harrison, R. W.; Hoffman, E. E.; Davies, R. L.

    1972-01-01

    Advanced Rankine and other proposed space power systems utilize refractory metals in contact with both single-phase and two-phase alkali metals at elevated temperatures. A number of recent compatibility experiments are described which emphasize the excellent compatibility of refractory metals with the alkali metals, lithium, sodium, and potassium, under a variety of environmental conditions. The alkali metal compatibilities of tantalum-, columbium-, molybdenum-, and tungsten-base alloys are discussed.

  10. Graphite-based detectors of alkali metals for nuclear power plants

    International Nuclear Information System (INIS)

    Kalandarishvili, A.G.; Kuchukhidze, V.A.; Sordiya, T.D.; Shartava, Sh.Sh.; Stepennov, B.S.

    1993-01-01

    The coolants most commonly used in today's fast reactors are alkali metals or their alloys. A major problem in nuclear plant design is leakproofing of the liquid-metal cooling system, and many leak detection methods and safety specifications have been developed as a result. Whatever the safety standards adopted for nuclear plants in different countries, they all rely on the basic fact that control of the contamination and radiation hazards involved requires reliable monitoring equipment. Results are presented of trials with some leak detectors for the alkali-metal circuits of nuclear reactors. The principal component affecting the detector performance is the sensing element. In the detectors graphite was employed, whose laminar structure enables it to absorb efficiently alkali-metal vapors at high temperatures (320--500 K). This produces a continuous series of alkali-metal-graphite solid solutions with distinct electrical, thermal, and other physical properties. The principle of operation of the detectors resides in the characteristic reactions of the metal-graphite system. One detector type uses the change of electrical conductivity of the graphite-film sensor when it is exposed to alkali-metal vapor. In order to minimize the effect of temperature on the resistance the authors prepared composite layers of graphite intercalated with a donor impurity (cesium or barium), and a graphite-nickel material. The addition of a small percentage of cesium, barium, or nickel produces a material whose temperature coefficient of resistance is nearly zero. Used as a sensing element, such a material can eliminate the need for thermostatic control of the detector

  11. Closure plug for alkali-metal-bounded fuel rods

    International Nuclear Information System (INIS)

    Guettler, R.

    1974-01-01

    The fuel rod consists of a cladding tube containing an alkali metal which surrounds the fuel pellets. The alkali metal improves the heat transfer. The cladding tube is closed with an end cap at its front end which cap is welded to the cladding tube. Its outside diameter is smaller than the inside diameter of the cladding tube so that the gas can flow out over the alkali metal column during the filling process. The length of the cap is such that the alkali metal is not heated during the welding process. The weld proper is made on a welding collar following a forced fit of the end cap. The end cap may be hollow. (DG) [de

  12. Method for intercalating alkali metal ions into carbon electrodes

    Science.gov (United States)

    Doeff, Marca M.; Ma, Yanping; Visco, Steven J.; DeJonghe, Lutgard

    1995-01-01

    A low cost, relatively flexible, carbon electrode for use in a secondary battery is described. A method is provided for producing same, including intercalating alkali metal salts such as sodium and lithium into carbon.

  13. Ternary alkali-metal and transition metal or metalloid acetylides as alkali-metal intercalation electrodes for batteries

    Science.gov (United States)

    Nemeth, Karoly; Srajer, George; Harkay, Katherine C; Terdik, Joseph Z

    2015-02-10

    Novel intercalation electrode materials including ternary acetylides of chemical formula: A.sub.nMC.sub.2 where A is alkali or alkaline-earth element; M is transition metal or metalloid element; C.sub.2 is reference to the acetylide ion; n is an integer that is 0, 1, 2, 3 or 4 when A is alkali element and 0, 1, or 2 when A is alkaline-earth element. The alkali elements are Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs) and Francium (Fr). The alkaline-earth elements are Berilium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra). M is a transition metal that is any element in groups 3 through 12 inclusive on the Periodic Table of Elements (elements 21 (Sc) to element 30 (Zn)). In another exemplary embodiment, M is a metalloid element.

  14. Fundamental study on alkali metal thermoelectric converter

    International Nuclear Information System (INIS)

    Masuda, Toshihisa

    1989-01-01

    The alkali metal thermoelectric converter (AMTEC) utilizing the sodium ion conducting β''-alumina is a device to convert heat energy to electric energy directly. In this paper, the results of theoretical and experimental studies on AMTEC power generating characteristics, internal electrical resistances of single cell, and system analysis of AMTEC power generating systems are reported. This paper consists of 5 chapters, which are summarized as follows: In chapter 1, a theoretical explanation of AMTEC, a brief survey of the research and development history of AMTEC and a purpose of this paper are reported. In chapter 2, the properties of β''-alumina, preparations of thin film electrodes, and special attention points to be paid in handling of β''-alumina and film electrodes are reported. The AMTEC power generating characteristics of the tubular cells are also reported. In chapter 3, the experimental results of the disk type cells and the theoretical considerations about internal resistances are reported. The causes of electrode erosion are also reported. In chapter 4, the system analysis on AMTEC steam-turbine combined cycle for a dispersed power station and AMTEC power system for a aerospace power are reported. Chapter 5 summarizes major results achieved in the preceding four chapters as a concluding remark. (J.P.N.) 62 refs

  15. Two-phase alkali-metal experiments in reduced gravity

    International Nuclear Information System (INIS)

    Antoniak, Z.I.

    1986-06-01

    Future space missions envision the use of large nuclear reactors utilizing either a single or a two-phase alkali-metal working fluid. The design and analysis of such reactors require state-of-the-art computer codes that can properly treat alkali-metal flow and heat transfer in a reduced-gravity environment. A literature search of relevant experiments in reduced gravity is reported on here, and reveals a paucity of data for such correlations. The few ongoing experiments in reduced gravity are noted. General plans are put forth for the reduced-gravity experiments which will have to be performed, at NASA facilities, with benign fluids. A similar situation exists regarding two-phase alkali-metal flow and heat transfer, even in normal gravity. Existing data are conflicting and indequate for the task of modeling a space reactor using a two-phase alkali-metal coolant. The major features of past experiments are described here. Data from the reduced-gravity experiments with innocuous fluids are to be combined with normal gravity data from the two-phase alkali-metal experiments. Analyses undertaken here give every expectation that the correlations developed from this data base will provide a valid representation of alkali-metal heat transfer and pressure drop in reduced gravity

  16. Upgrading of petroleum oil feedstocks using alkali metals and hydrocarbons

    Science.gov (United States)

    Gordon, John Howard

    2014-09-09

    A method of upgrading an oil feedstock by removing heteroatoms and/or one or more heavy metals from the oil feedstock composition. This method reacts the oil feedstock with an alkali metal and an upgradant hydrocarbon. The alkali metal reacts with a portion of the heteroatoms and/or one or more heavy metals to form an inorganic phase separable from the organic oil feedstock material. The upgradant hydrocarbon bonds to the oil feedstock material and increases the number of carbon atoms in the product. This increase in the number of carbon atoms of the product increases the energy value of the resulting oil feedstock.

  17. High-purity, robust alkali vapor sources without vacuum feedthroughs

    Science.gov (United States)

    Kohn, Rudolph; Bigelow, Matthew; Imhof, Eric; Squires, Matthew; Olson, Spencer; Kasch, Brian; Hostutler, David

    2017-04-01

    The authors report the successful implementation of a method for producing rubidium vapor at sufficient purity and with sufficient quantity to load cold atom experiments. This method requires no vacuum feedthroughs and has measurable advantages in several parameters over commercial chromate dispensers, including vapor purity, required heating power, and capacity per unit volume. It is reasonably stable when exposed to air, allowing for easy handling. Currently, this method is being integrated into the authors' systems and its use in loading a basic 3D vapor cell magneto-optical trap (MOT) has been demonstrated, in addition to loading a 2D+ MOT which has been subsequently used to load a 3D MOT.

  18. Exploration of the catalytic use of alkali metal bases

    OpenAIRE

    Bao, Wei

    2017-01-01

    This PhD thesis project was concerned with the use of alkali metal amide Brønsted bases and alkali metal alkoxide Lewis bases in (asymmetric) catalysis. The first chapter deals with formal allylic C(sp3)–H bond activation of aromatic and functionalized alkenes for subsequent C–C and C–H bond formations. The second chapter is focused on C(sp3)–Si bond activation of fluorinated pro-nucleophiles in view of C–C bond formations. In the first chapter, a screening of various metal amides...

  19. Maternal exposure to alkali, alkali earth, transition and other metals: Concentrations and predictors of exposure

    International Nuclear Information System (INIS)

    Hinwood, A.L.; Stasinska, A.; Callan, A.C.; Heyworth, J.; Ramalingam, M.; Boyce, M.; McCafferty, P.; Odland, J.Ø.

    2015-01-01

    Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children. - This study has demonstrated exposure to alkali, alkali earth and transition metals in pregnant women with factors such as breastfeeding, fish oil use and diet affecting exposures

  20. Neuropsychiatric manifestations of alkali metal deficiency and excess

    Energy Technology Data Exchange (ETDEWEB)

    Yung, C.Y.

    1984-01-01

    The alkali metals from the Group IA of the periodic table (lithium, sodium, potassium, rubidium, cesium and francium) are reviewed. The neuropsychiatric aspects of alkali metal deficiencies and excesses (intoxications) are described. Emphasis was placed on lithium due to its clinical uses. The signs and symptoms of these conditions are characterized by features of an organic brain syndrome with delirium and encephalopathy prevailing. There are no clinically distinctive features that could be reliably used for diagnoses. Sodium and potassium are two essential alkali metals in man. Lithium is used as therapeutic agent in bipolar affective disorders. Rubidium has been investigated for its antidepressant effect in a group of psychiatric disorders. Cesium is under laboratory investigation for its role in carcinogenesis and in depressive illness. Very little is known of francium due to its great instability for experimental study.

  1. Survival probability in small angle scattering of low energy alkali ions from alkali covered metal surfaces

    International Nuclear Information System (INIS)

    Neskovic, N.; Ciric, D.; Perovic, B.

    1982-01-01

    The survival probability in small angle scattering of low energy alkali ions from alkali covered metal surfaces is considered. The model is based on the momentum approximation. The projectiles are K + ions and the target is the (001)Ni+K surface. The incident energy is 100 eV and the incident angle 5 0 . The interaction potential of the projectile and the target consists of the Born-Mayer, the dipole and the image charge potentials. The transition probability function corresponds to the resonant electron transition to the 4s projectile energy level. (orig.)

  2. Study of absorption spectra for alkali and alkaline earth metal salts in flameless atomic absorption spectrometry using a carbon tube atomizer

    International Nuclear Information System (INIS)

    Yasuda, Seiji; Kakiyama, Hitoo

    1975-01-01

    Absorption spectra of various salts such as alkali metal salts, alkaline earth dichlorides, and ammonium halides were investigated and absorptions of some molecular species produced in the carbon tube were identified. The aqueous solution (20 μl) containing 1.0 mg/ml of each salt was placed in the carbon tube atomizer and heated in a similar manner to usual flameless atomic absorption method. D 2 -lamp was used as a continuous light source and argon gas was employed as an inert sheath gas. The spectra were obtained over the range of wavelength 200 to 350 nm. When alkali halides were feeded, the absorption spectra agreed with those of alkali halide vapors. Therefore, in such cases vapors of the alkali halides were probably produced by the sublimation or vaporization in the atomizer. The spectra of alkali perchlorates were considered to be those of alkali chlorides produced by the pyrolysis of the perchlorates in the atomizer. The absorptions of alkaline earth chlorides below 250 nm were probably due to their gaseous states. Sulfur dioxide was found to be produced by the pyrolysis of alkali sulfates, bisulfates and sulfites in the atomizer, Alkali phosphates and pyrophosphates gave almost identical spectra below 300 nm. Gamma band spectrum of nitrogen monoxide was observed from 200 to 240 nm during ashing at bout 330 0 C for alkali nitrates and nitrites. Ammonia vapor was produced from ammonium halides during drying at about 170 0 C. Although the absorptions of alkali carbonates and hydroxides were almost undetectable, the same spectra as those of alkali halides were observed by the addition of ammonium halides to the solutions of alkali compounds. This shows that alkali halides are produced in the atomizer by the addition of halide ions. (auth.)

  3. The direct observation of alkali vapor species in biomass combustion and gasification

    Energy Technology Data Exchange (ETDEWEB)

    French, R J; Dayton, D C; Milne, T A

    1994-01-01

    This report summarizes new data from screening various feedstocks for alkali vapor release under combustion conditions. The successful development of a laboratory flow reactor and molecular beam, mass spectrometer interface is detailed. Its application to several herbaceous and woody feedstocks, as well as a fast-pyrolysis oil, under 800 and 1,100{degrees}C batch combustion, is documented. Chlorine seems to play a large role in the facile mobilization of potassium. Included in the report is a discussion of relevant literature on the alkali problem in combustors and turbines. Highlighted are the phenomena identified in studies on coal and methods that have been applied to alkali speciation. The nature of binding of alkali in coal versus biomass is discussed, together with the implications for the ease of release. Herbaceous species and many agricultural residues appear to pose significant problems in release of alkali species to the vapor at typical combustor temperatures. These problems could be especially acute in direct combustion fired turbines, but may be ameliorated in integrated gasification combined cycles.

  4. Heat transfer characteristics of alkali metals flowing across tube banks

    International Nuclear Information System (INIS)

    Sugiyama, K.; Ishiguro, R.; Kojima, Y.; Kanaoka, H.

    2004-01-01

    For the purpose of getting heat transfer coefficients of alkali metals flowing across tube banks at an acceptable level, we propose to use an inviscid-irrotational flow model, which is based on our flow visualization experiment. We show that the heat transfer coefficients obtained for the condition where only the test rod is heated in tube banks considerably differ from those obtained for the condition where all the rods are heated, because of interference between thick thermal boundary layers of alkali metals. We also confirm that the analytical values obtained by this flow model are in a reasonable agreement with experimental values. (author)

  5. Long-range interactions among three alkali-metal atoms

    International Nuclear Information System (INIS)

    Marinescu, M.; Starace, A.F.

    1996-01-01

    The long-range asymptotic form of the interaction potential surface for three neutral alkali-metal atoms in their ground states may be expressed as an expansion in inverse powers of inter-nuclear distances. The first leading powers are proportional to the dispersion coefficients for pairwise atomic interactions. They are followed by a term responsible for a three body dipole interaction. The authors results consist in evaluation of the three body dipole interaction coefficient between three alkali-metal atoms. The generalization to long-range n atom interaction terms will be discussed qualitatively

  6. Synthesis and structural characterization of alkali metal arsinoamides.

    Science.gov (United States)

    Chen, Xiao; Gamer, Michael T; Roesky, Peter W

    2017-12-20

    The aminoarsane Mes 2 AsN(H)Ph was prepared from Mes 2 AsCl and aniline in good yields. Deprotonation of Mes 2 AsN(H)Ph with suitable alkali metal bases resulted in the corresponding alkali metal derivatives. Thus, reaction of Mes 2 AsN(H)Ph with nBuLi, NaN(SiMe 3 ) 2 , or KH gave the metal complexes [(Mes 2 AsNPh){Li(OEt 2 ) 2 }], [(Mes 2 AsNPh){Na(OEt 2 )}] 2 , and [(Mes 2 AsNPh){K(THF)}] 2 . These are the first metal complexes ligated by an arsinoamide. All solid-state structures were established by single crystal X-ray diffraction. The lithium compounds form a monomer in the solid-state, whereas the sodium and the potassium derivatives are dimers. In the dimeric compounds intra- and intermolecular π-interaction of the aromatic rings with the metal atoms is observed.

  7. Maternal exposure to alkali, alkali earth, transition and other metals: Concentrations and predictors of exposure.

    Science.gov (United States)

    Hinwood, A L; Stasinska, A; Callan, A C; Heyworth, J; Ramalingam, M; Boyce, M; McCafferty, P; Odland, J Ø

    2015-09-01

    Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  8. A possible role of alkali metal ions in the synthesis of pure-silica molecular sieves

    OpenAIRE

    Goepper, Michelle; Li, Hong-Xin; Davis, Mark E.

    1992-01-01

    Pure-silica ZSM-12 is synthesized in the presence and absence of alkali metal ions; addition of alkali metal ions at constant hydroxide ion concentration increases the crystallization rate of ZSM-12, and it is suggested that alkali metal ions participate in both the nucleation and crystal growth processes.

  9. 40 CFR 721.5452 - Alkali metal salt of halogenated organoborate (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal salt of halogenated... Specific Chemical Substances § 721.5452 Alkali metal salt of halogenated organoborate (generic). (a... generically as alkali metal salt of halogenated organoborate (PMN P-00-0638) is subject to reporting under...

  10. 40 CFR 721.5985 - Fatty alkyl phosphate, alkali metal salt (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Fatty alkyl phosphate, alkali metal... Specific Chemical Substances § 721.5985 Fatty alkyl phosphate, alkali metal salt (generic). (a) Chemical... as a fatty alkyl phosphate, alkali metal salt (PMN P-99-0385) is subject to reporting under this...

  11. Structural properties of low-density liquid alkali metals

    Indian Academy of Sciences (India)

    The static structure factors of liquid alkali metals have been modelled at temperatures close to their melting points and a few higher temperatures using the reverse Monte Carlo (RMC) method. The positions of 5000 atoms in a box, with full periodicity, were altered until the experimental diffraction data of the structure factor ...

  12. Momentum densities and Compton profiles of alkali-metal atoms

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 60; Issue 3 ... Quantum defect theory; wave functions of alkali-metal atoms; momentum properties. ... to study the momentum properties of atoms from 3Li to 37Rb. The numerical results obtained for the momentum density, moments of momentum density and Compton ...

  13. Momentum densities and Compton profiles of alkali-metal atoms

    Indian Academy of Sciences (India)

    Abstract. It is assumed that the dynamics of valence electrons of alkali-metal atoms can be well accounted for by a quantum-defect theoretic model while the core electrons may be supposed to move in a self-consistent field. This model is used to study the momentum properties of atoms from. 3Li to 37Rb. The numerical ...

  14. Ion conducting fluoropolymer carbonates for alkali metal ion batteries

    Science.gov (United States)

    DeSimone, Joseph M.; Pandya, Ashish; Wong, Dominica; Balsara, Nitash P.; Thelen, Jacob; Devaux, Didier

    2017-09-05

    Liquid or solid electrolyte compositions are described that comprise a homogeneous solvent system and an alkali metal salt dissolved in said solvent system. The solvent system may comprise a fluoropolymer, having one or two terminal carbonate groups covalently coupled thereto. Batteries containing such electrolyte compositions are also described.

  15. Two-phonon states in alkali-metal clusters

    International Nuclear Information System (INIS)

    Abada, A.; Vautherin, D.

    1992-12-01

    Two phonon-states of alkali-metal clusters (treated as jellium spheres) are calculated by using a method based on a perturbative construction of periodic orbits of the time-dependent mean-field equations. Collective vibrations with various multipolarities in charged Na 21 + are considered. (author) 26 refs.; 2 figs.; 3 tabs

  16. Direct observation of the release of alkali vapor species in biofuel combustion and gasification

    Energy Technology Data Exchange (ETDEWEB)

    French, R.J.; Milne, T.A. [National Renewable Energy Lab., Golden, CO (United States)

    1993-12-31

    The largest present use of biomass for energy is in combustion for steam and electrical power. Biofuels have an acknowledged advantage over coal as a solid fuel because of their low sulfur and ash content. However, some forms of biomass have substantial quantities of alkali metals and chlorine. In addition, evidence indicates that the alkali in biomass is largely atomically dispersed, resulting in its facile mobilization into the gas-phase. Gaseous alkali compounds aggravate problems of slagging, fouling, and corrosion on heat transfer surfaces in present-day boilers. These problems can be particularly severe when mixed and variable agricultural residues are burned. Furthermore, the next generation of biomass-to-power systems will likely involve combined cycle gas turbines, where alkali tolerances are especially restrictive. In this paper, we report on laboratory studies in which biofuels are combusted under simulated turbine or boiler-firing conditions. Gaseous alkali, sulfur, nitrogen, and halogen-containing species are measured by direct extraction from the hot gases through molecular-beam mass spectrometry (MBMS). The experimental apparatus will be described and its capability illustrated with results of time-resolved evolution of species like K, KCl, KOH, SO{sub 2} and NO{sub x} from small samples of biomass in combustion environments. The nature and release of such species will be explicated by referring to thermodynamic equilibrium predictions and the form of alkali in solid, gaseous, and liquid biofuels.

  17. Electrospray droplet exposure to organic vapors: metal ion removal from proteins and protein complexes.

    Science.gov (United States)

    DeMuth, J Corinne; McLuckey, Scott A

    2015-01-20

    The exposure of aqueous nanoelectrospray droplets to various organic vapors can dramatically reduce sodium adduction on protein ions in positive ion mass spectra. Volatile alcohols, such as methanol, ethanol, and isopropanol lead to a significant reduction in sodium ion adduction but are not as effective as acetonitrile, acetone, and ethyl acetate. Organic vapor exposure in the negative ion mode, on the other hand, has essentially no effect on alkali ion adduction. Evidence is presented to suggest that the mechanism by which organic vapor exposure reduces alkali ion adduction in the positive mode involves the depletion of alkali metal ions via ion evaporation of metal ions solvated with organic molecules. The early generation of metal/organic cluster ions during the droplet desolvation process results in fewer metal ions available to condense on the protein ions formed via the charged residue mechanism. These effects are demonstrated with holomyoglobin ions to illustrate that the metal ion reduction takes place without detectable protein denaturation, which might be revealed by heme loss or an increase in charge state distribution. No evidence is observed for denaturation with exposure to any of the organic vapors evaluated in this work.

  18. 40 CFR 721.10097 - Disubstituted benzenesulfonic acid, alkali metal salt (generic).

    Science.gov (United States)

    2010-07-01

    ..., alkali metal salt (generic). 721.10097 Section 721.10097 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.10097 Disubstituted benzenesulfonic acid, alkali... chemical substance identified generically as disubstituted benzenesulfonic acid, alkali metal salt (PMN P...

  19. 40 CFR 721.10098 - Disubstituted benzoic acid, alkali metal salt (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Disubstituted benzoic acid, alkali... New Uses for Specific Chemical Substances § 721.10098 Disubstituted benzoic acid, alkali metal salt... identified generically as disubstituted benzoic acid, alkali metal salt (PMN P-03-643) is subject to...

  20. 40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Fluorinated carboxylic acid alkali... Specific Chemical Substances § 721.4663 Fluorinated carboxylic acid alkali metal salts. (a) Chemical... fluorinated carboxylic acid alkali metal salts (PMNs P-95-979/980/981) are subject to reporting under this...

  1. Chemical compatibility of structural materials in alkali metals

    International Nuclear Information System (INIS)

    Natesan, K.; Rink, D.L.; Haglund, R.

    1995-01-01

    The objectives of this task are to (a) evaluate the chemical compatibility of structural alloys such as V-5 wt.%Cr-5 wt.%Ti alloy and Type 316 stainless steel for application in liquid alkali metals such as lithium and sodium-78 wt.% potassium (NaK) at temperatures in the range that are of interest for International Thermonuclear Experimental Reactor (ITER); (b) evaluate the transfer of nonmetallic elements such as oxygen, nitrogen, carbon, and hydrogen between structural materials and liquid metals; and (c) evaluate the effects of such transfers on the mechanical and microstructural characteristics of the materials for long-term service in liquid-metal-environments

  2. Alkali Metal Coolants. Proceedings of the Symposium on Alkali Metal Coolants - Corrosion Studies and System Operating Experience

    International Nuclear Information System (INIS)

    1967-01-01

    Proceedings of a Symposium organized by the IAEA and held in Vienna, 28 November - 2 December 1966. The meeting was attended by 107 participants from 16 countries and two international organizations. Contents: Review papers (2 papers); Corrosion of steels and metal alloys (6 papers); Mass transfer in alkali metal systems, behaviour of carbon (5 papers); Effects of sodium environment on mechanical properties of materials (3 papers); Effect of water leakage into sodium systems (2 papers); Design-and operation of testing apparatus (6 papers); Control, measurements and removal of impurities (13 papers); Corrosion by other alkali metals: NaK, K, Li, Cs (6 papers); Behaviour of fission products (3 papers). Each paper is in its original language (32 English, 6 French and 8 Russian) and is preceded by an abstract in English and one in the original language if this is not English. Discussions are in English. (author)

  3. Excimer-pumped alkali vapor lasers: a new class of photoassociation lasers

    Science.gov (United States)

    Readle, J. D.; Wagner, C. J.; Verdeyen, J. T.; Spinka, T. M.; Carroll, D. L.; Eden, J. G.

    2010-02-01

    Excimer-pumped alkali vapor lasers (XPALs) are a new class of photoassociation lasers which take advantage of the spectrally broad absorption profiles of alkali-rare gas collision pairs. In these systems, transient alkali-rare gas molecules are photopumped from the thermal continuum to a dissociative X2Σ+ 1/2 interaction potential, subsequently populating the n2P3/2 state of the alkali. The absorption profiles >=5 nm and quantum efficiencies >98% have been observed in oscillator experiments, indicating XPAL compatibility with conventional high power laser diode arrays. An alternative technique for populating the n2P3/2 state is direct photoexcitation on the n2P3/2adjusted by altering the number densities of the lasing species and/or perturbers, a valuable asset in the design of large volume, high power lasers. We present an overview of XPAL lasers and their operation, including the characteristics of recently demonstrated systems photopumped with a pulsed dye laser. Lasing has been observed in Cs at both 894 nm and 852 nm by pumping CsAr or CsKr pairs as well as in Rb at 795 nm by pumping RbKr. These results highlight the important role of the perturbing species in determining the strength and position of the excimer absorption profile. It is expected that similar results may be obtained in other gas mixtures as similar collision pair characteristics have historically been observed in a wide variety of transient diatomic species.

  4. A study of corresponding states for the liquid alkali metals

    International Nuclear Information System (INIS)

    Mountain, R.D.

    1977-01-01

    The pseudopotential pair potentials developed by Price et al (Phys.Rev.;B2:2983(1970)) and by Dagens et al (Phys.Rev.;B11:2726(1975)) are used to investigate the microscopic basis for a law of corresponding states for the liquid alkali metals. Both sets of potential functions show small departures from corresponding states. Monte Carlo simulation is used to show that the temperature-dependent part of the equations of state for Na and K scale with an error of the order of 10%. The pair distribution functions for Na are in good agreement with the results of x-ray diffraction measurements. These studies suggest that corresponding states is a reasonable, but not completely accurate, way of describing the thermodynamic properties of the liquid alkali metals. (author)

  5. Polarizabilities and hyperpolarizabilities of the alkali metal atoms

    Energy Technology Data Exchange (ETDEWEB)

    Fuentealba, P. (Chile Univ., Santiago (Chile). Departamento de Fisica and Centro de Mecanica Cuantica Aplicada (CMCA)); Reyes, O. (Chile Univ., Santiago (Chile). Dept. de Fisica)

    1993-08-14

    The electric static dipole polarizability [alpha], quadrupole polarizability C, dipole-quadrupole polarizability B, and the second dipole hyperpolarizability [gamma] have been calculated for the alkali metal atoms in the ground state. The results are based on a pseudopotential which is able to incorporate the very important core-valence correlation effect through a core polarization potential, and, in an empirical way, the main relativistic effects. The calculated properties compare very well with more elaborated calculations for the Li atom, excepting the second hyperpolarizability [gamma]. For the other atoms, there is neither theoretical nor experimental information about most of the higher polarizabilities. Hence, the results of this paper should be seen as a first attempt to give a complete account of the series expansion of the interaction energy of an alkali metal atom and a static electric field. (author).

  6. Composition and thermodynamic properties of dense alkali metal plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Gabdullin, M.T. [NNLOT, al-Farabi Kazakh National University, 71 al-Farabi Str., Almaty 050035 (Kazakhstan); Ramazanov, T.S.; Dzhumagulova, K.N. [IETP, al-Farabi Kazakh National University, 71 al-Farabi Str., Almaty 050035 (Kazakhstan)

    2012-04-15

    In this work composition and thermodynamic properties of dense alkali metal plasmas (Li, Na) were investigated. Composition was derived by solving the Saha equations with corrections due to nonideality. The lowering of the ionization potentials was calculated on the basis of pseudopotentials by taking screening and quantum effects into account (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Synthesis and characterization of tetravalent actinide orthophosphates with alkali metals

    International Nuclear Information System (INIS)

    Volkov, Yu.F.; Melkaya, R.F.; Spiryakov, V.I.; Timofeev, G.A.

    1995-01-01

    A series of double phosphates of formula AM 2 (PO 4 ) 3 , where A = Li, Na, K, Rb, Cs; M = U, Np, Pu, is prepared by solid-state reactions. Various polymorphic modifications of AM 2 (PO 4 ) 3 are identified by using X-ray diffraction and IR spectroscopic analyses of the products from stepwise annealing. The crystal structure type, thermal stability of the modifications, and nature of the polymorphic transformations depend on the nature of the actinide and alkali metal

  8. Momentum densities and Compton profiles of alkali-metal atoms

    Indian Academy of Sciences (India)

    It is assumed that the dynamics of valence electrons of alkali-metal atoms can be well accounted for by a quantum-defect theoretic model while the core electrons may be supposed to move in a self-consistent field. This model is used to study the momentum properties of atoms from 3Li to 37Rb. The numerical results ...

  9. Alkali and heavy metal emissions of the PCFB-process; Alkali- ja raskasmetallipaeaestoet PCFB-prosessista

    Energy Technology Data Exchange (ETDEWEB)

    Kuivalainen, R.; Eriksson, T.; Lehtonen, P. [Foster Wheeler Energia Oy, Karhula (Finland)

    1997-10-01

    Pressurized Circulating Fluidized Bed (PCFB) combustion technology has been developed in Karhula R and D Center since 1986. As part of the development, 10 MW PCFB test facility was built in 1989. The test facility has been used for performance testing with different coal types through the years 1990-1995 in order to gain data for design and commercialization of the high-efficiency low-emission PCFB combustion technology. The main object of the project was to measure vapor phase Na and K concentrations in the PCFB flue gas after hot gas filter and investigate the effects of process conditions and sorbents on alkali release. The measurements were performed using plasma assisted method of TUT Laboratory of Plasma Technology and wet absorption method of VTT Energy. The measurements were carried out during three test campaigns at PCFB Test Facility in Karhula. In autumn 1995 both VTT and TUT methods were used. The measurements of the following test period in spring 1996 were performed by VTT, and during the last test segment in autumn 1996 TUT method was in use. During the last test period, the TUT instrument was used as semi-continuous (3 values/minute) alkali analyzer for part of the time. The measured Na concentrations were below 30 ppb(w) in all measured data points. The results of K were below 10 ppb(w). The accuracies of the both methods are about +50 % at this concentration range. The scatter of the data covers the effects of different process variables on the alkali emission. The measured emissions are at the same order of magnitude as the guideline emission limits estimated by gas turbine manufacturers

  10. Neutron Imaging of Alkali Metal Heat Pipes

    Science.gov (United States)

    Kihm, K.; Kirchoff, E.; Golden, M.; Rosenfeld, J.; Rawal, S.; Pratt, D.; Swanson, A.; Bilheux, H.; Walker, L.; Voisin, S.; Hussey, D. S.; Jacobson, D. L.

    High-temperature heat pipes are two-phase, capillary driven heat transfer devices capable of passively providing high thermal fluxes. Such a device using a liquid-metal coolant can be used as a solution for successful thermal management on hypersonic flight vehicles. Imaging of the liquid-metal coolant inside will provide valuable information in characterizing the detailed heat and mass transport. Neutron imaging possesses an inherent advantage from the fact that neutrons penetrate the heat pipe metal walls with very little attenuation, but are significantly attenuated by the liquid metal contained inside. Using the BT-2 beam line at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, preliminary efforts have been conducted on a nickel-sodium heat pipe. The contrast between the attenuated beam and the background is calculated to be approximately 3%. This low contrast requires sacrifice in spatial or temporal resolution so efforts have since been concentrated on lithium (Li) which has a substantially larger neutron attenuation cross section. Using the CG-1D beam line at the High Flux Isotope Reactor (HFIR) of Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, the first neutron images of high-temperature molybdenum (Mo)-Li heat pipes have been achieved. The relatively high neutron cross section of Li allows for the visualization of the Li working fluid inside the heat pipes. The evaporator region of a gravity assisted cylindrical heat pipe prototype 25 cm long was imaged from start-up to steady state operation up to approximately 900 °C. In each corner of the square bore inside, the capillary action raises the Li meniscus above the bulk Li pool in the evaporator region. As the operational temperature changes, the meniscus shapes and the bulk meniscus height also changes. Furthermore, a three-dimensional tomographic image is also reconstructed from the total of 128 projection images taken 1.4o apart in which the Li had

  11. Removal of toxic and alkali/alkaline earth metals during co-thermal treatment of two types of MSWI fly ashes in China.

    Science.gov (United States)

    Yu, Jie; Qiao, Yu; Jin, Limei; Ma, Chuan; Paterson, Nigel; Sun, Lushi

    2015-12-01

    This study aims to vaporize heavy metals and alkali/alkaline earth metals from two different types of fly ashes by thermal treatment method. Fly ash from a fluidized bed incinerator (HK fly ash) was mixed with one from a grate incinerator (HS fly ash) in various proportions and thermally treated under different temperatures. The melting of HS fly ash was avoided when treated with HK fly ash. Alkali/alkaline earth metals in HS fly ash served as Cl-donors to promote the vaporization of heavy metals during thermal treatment. With temperature increasing from 800 to 900°C, significant amounts of Cl, Na and K were vaporized. Up to 1000°C in air, less than 3% of Cl and Na and less than 5% of K were retained in ash. Under all conditions, Cd can be vaporized effectively. The vaporization of Pb was mildly improved when treated with HS fly ash, while the effect became less pronounced above 900°C. Alkali/alkaline earth metals can promote Cu vaporization by forming copper chlorides. Comparatively, Zn vaporization was low and only slightly improved by HS fly ash. The low vaporization of Zn could be caused by the formation of Zn2SiO4, ZnFe2O4 and ZnAl2O4. Under all conditions, less than 20% of Cr was vaporized. In a reductive atmosphere, the vaporization of Cd and Pb were as high as that in oxidative atmosphere. However, the vaporization of Zn was accelerated and that of Cu was hindered because the formation of Zn2SiO4, ZnFe2O4 and ZnAl2O4 and copper chloride was depressed in reductive atmosphere. Copyright © 2015. Published by Elsevier Ltd.

  12. Alkali Metal Backup Cooling for Stirling Systems - Experimental Results

    Science.gov (United States)

    Schwendeman, Carl; Tarau, Calin; Anderson, William G.; Cornell, Peggy A.

    2013-01-01

    In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor. In a previous NASA SBIR Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for Stirling RPS. The operation of these VCHPs was demonstrated using Stirling heater head simulators and GPHS simulators. In the most recent effort, a sodium VCHP with a stainless steel envelope was designed, fabricated and tested at NASA Glenn Research Center (GRC) with a Stirling convertor for two concepts; one for the Advanced Stirling Radioisotope Generator (ASRG) back up cooling system and one for the Long-lived Venus Lander thermal management system. The VCHP is designed to activate and remove heat from the stopped convertor at a 19 degC temperature increase from the nominal vapor temperature. The 19 degC temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the Multi-Layer Insulation (MLI). In addition, the same backup cooling system can be applied to the Stirling convertor used for the refrigeration system of the Long-lived Venus Lander. The VCHP will allow the refrigeration system to: 1) rest during transit at a lower temperature than nominal; 2) pre-cool the modules to an even lower temperature before the entry in Venus atmosphere; 3) work at nominal temperature on Venus surface; 4) briefly stop multiple times on the Venus surface to allow scientific measurements. This paper presents the experimental

  13. Dissolution of metallic uranium in alkalis

    International Nuclear Information System (INIS)

    Mondino, Angel V.; Wilkinson, Maria V.; Manzini, Alberto C.

    1999-01-01

    The dissolution of U metallic foils has been studied in the framework of the development of an improved 99 Mo-production process. The best conditions for the dissolution of uranium foils of approximately 150 μm are the following: a) NaClO concentrations of 0.20 and 0.23 M with NaOH of 0.27 and 0.31 M respectively; b) temperature of the solution, 70 C degrees; c) volume of the solution, 15 ml / cm 2 of uranium foil; d) dissolution time, 30 minutes. (author)

  14. Diffusion with chemical reaction: An attempt to explain number density anomalies in experiments involving alkali vapor

    Science.gov (United States)

    Snow, W. L.

    1974-01-01

    The mutual diffusion of two reacting gases is examined which takes place in a bath of inert gas atoms. Solutions are obtained between concentric spheres, each sphere acting as a source for one of the reactants. The calculational model is used to illustrate severe number density gradients observed in absorption experiments with alkali vapor. Severe gradients result when sq root k/D R is approximately 5 where k, D, and R are respectively the second order rate constant, the multicomponent diffusion constant, and the geometrical dimension of the experiment.

  15. Alkali and heavy metal emissions of the PCFB-process; Alkalipaeaestoet PCFB-prosessissa

    Energy Technology Data Exchange (ETDEWEB)

    Kuivalainen, R.; Eriksson, T.; Lehtonen, P. [Foster Wheeler Energia Oy, Karhula (Finland)

    1996-12-01

    Pressurized Circulating Fluidized Bed (PCFB) combustion technology has been developed in Karhula R and D Center since 1986. As a part of the development, 10 MW PCFB Test Facility was built in 1989. The Test Facility has been used for performance testing with different coal types through the years 1990-1995 in order to gain data for design and commercialization of the high-efficiency low-emission PCFB combustion technology. The project Y44 `Alkali and heavy metal emissions of the PCFB-process` was part of national LIEKKI 2 research program. The main object of the project was to measure vapor phase Na and K concentrations in the PCFB flue gas after hot gas filter and investigate the effects of process conditions and sorbents on alkali release. The measurements were performed using plasma assisted method by TUT Laboratory of Plasma Technology and wet absorption method of VTT Energy. The measured Na concentrations were below 30 ppb(w) in all measured data points. The results of K were below 10 ppb(w). The accuracies of the both methods are about + 50 % at this concentration range. The scatter of the data covers the effects of different process variables on the alkali emission. The measured emissions are at the same order of magnitude as the guideline emission limits estimated by gas turbine manufacturers. The measurements and development of the analyses methods are planned to be continued during PCFB test runs in spring 1996 for example within Joule II research program. (author)

  16. Efficient destruction of CF4 through in situ generation of alkali metals from heated alkali halide reducing mixtures.

    Science.gov (United States)

    Lee, Myung Churl; Choi, Wonyong

    2002-03-15

    Perfluorocarbons (PFCs) are the most potent green house gases that are very recalcitrant at destruction. An effective way of converting PFCs using hot solid reagents into safe products has been recently introduced. By investigating the thermal reductive destruction of tetrafluoromethane (CF4) we provided new insight and more physicochemical consideration on this novel process. The complete destruction of CF4was successfully achieved by flowing the gas through a heated reagent bed (400-950 degrees C) that contained powder mixtures of alkali halides, CaO, and Si. The silicon acted as a reducing agent of alkali halides for the in-situ production of alkali metals, and the calcium oxide played the role of a halide ion acceptor. The absence of any single component in this ternary mixture drastically reduced the destruction efficiency of CF4. The CF4 destruction efficiencies with the solid reagent containing the alkali halide, MX, increased in the order of Li approximately Na < K < Cs for alkali cations and I < Br < Cl < F for halide anions. This trend agreed with the endothermicity of the alkali metal generation reaction: the higher the endothermicity, the lower the destruction efficiency. Alkali metal generation was indirectly detected by monitoring H2 production from its reaction with water. The production of alkali metals increased with NaF, KF, and CsF in this order. The CsF/CaO/Si system exhibited the complete destruction of CF4 at as low as 600 degrees C. The solid product analysis by X-ray diffraction (XRD) showed the formation of CaF2 and the depletion of Si with black carbon particles formed in the solid reagent residue. No CO/CO2 and toxic HF and SiF4 formation were detected in the exhaust gas.

  17. Method for preparation of melts of alkali metal chlorides with highly volatile polyvalent metal chlorides

    International Nuclear Information System (INIS)

    Salyulev, A.B.; Kudyakov, V.Ya.

    1990-01-01

    A method for production of alkali metal (Cs, Rb, K) chloride melts with highly volatile polyvalent metal chlorides is suggested. The method consists, in saturation of alkali metal chlorides, preheated to the melting point, by volatile component vapours (titanium tetrachloride, molybdenum or tantalum pentachloride) in proportion, corresponding to the composition reguired. The saturation is realized in an evacuated vessel with two heating areas for 1-1.5 h. After gradual levelling of temperature in both areas the product is rapidly cooled. 1 fig.; 1 tab

  18. Corrosion resistance of metals and alloys in molten alkalies

    International Nuclear Information System (INIS)

    Zarubitskij, O.G.; Dmitruk, B.F.; Minets, L.A.

    1979-01-01

    Literature data on the corrosion of non-ferrous and noble metals, iron and steels in the molten alkalis and mixtures of their base are presented. It is shown that zirconium, niobium and tantalum are characterized by high corrosion stability in the molten NaOH. Additions of NaOH and KOH to the alkali chloride melts result in a 1000 time decrease of zirconium corrosion rate at 850 deg. The data testify to the characteristic passivating properties of OH - ions; Mo and W do not possess an ability to selfpassivation in hydroxide melts. Corrosion resistance of carbon and chromium-nickel steels in hydroxide melts depends considerably on the temperature, electrolyte composition and atmosphere over them. At the temperatures up to 600 deg C chromium-nickel steel is corrosion resistant in the molten alkali only in the inert atmosphere. Corrosion rate of chromium-nickel alloy is the lower the less chromium and the more nickel it contains. For the small installations the 4Kh18N25S2 and Kh23N28M3D3T steels can be recommended

  19. The removal of alkali metals from hot gas

    Energy Technology Data Exchange (ETDEWEB)

    Orjala, M.; Haukka, P. (Valtion Teknillinen Tutkimuskeskus, Jyvaeskylae (Finland). Polttoaine- ja Polttotekniikan Lab.)

    1990-01-01

    In investigations in progress at the Fuel and Combustion Laboratory of the Technical Research Centre of Finland, we have been studying in co-operation with A. Ahlstrom Boiler Works, the removal of alkali metals from flue gases of ash-rich fuel with a dense suspension particle cooler. The applications of the particle cooler can be found in combined cycles and in industrial gas cleaning and heat recovery. We have also developed a general mathematical model of heat and mass transfer as well as chemical and physical reactions in multiphase systems.

  20. The solvent extraction of alkali metal ions with β-diketones

    International Nuclear Information System (INIS)

    Munakata, Megumu; Niina, Syozo; Shimoji, Noboru

    1974-01-01

    This work was undertaken to investigate effects of solvent and chelating-agent on the solvent extraction of alkali metal ions by seven β-diketones, acetylacetone (Acac), benzoylacetone (BzA), dipivaloylmethane (DPM), dibenzoylmethane (DBM), thenoyltrifluoloacetone (TTA), benzoyltrifluoroacetone (BFA) and hexafluoroacetylacetone (HFA), and to separate lithium from alkali metals. The extraction of alkali metals increase with increasing donor power of the solvent: i.e., benzene Na>K>Rb>Cs, which is also the order in which the adduct formation of these β-diketone chelates with donor solvents increase. The adduct formations between β-diketone chelates of alkali metals and donor solvents markedly enhance the solubilities of the chelates in solvents and, consequently, the extractabilities of alkali metals with β-diketones. Lithium was extracted with TTA in ether at such a low base concentration that sodium, potassium, rubidium and cesium were hardly extracted, and this enabled to separate lithium from other metals by the use of rubidium hydroxide (0.02 M). An attempt has been made to isolate alkali metal β-diketone chelates and some chelates have been obtained as crystals. The infrared absorption bands arising from C=O and C.=C of TTA shift to lower frequencies in the alkali metal chelates with TTA, and consequently, β-diketones is suggested to coordinate to alkali metal as a bidentate ligand. (JPN)

  1. 3718-F Alkali Metal Treatment and Storage Facility Closure Plan

    International Nuclear Information System (INIS)

    1992-11-01

    The Hanford Site, located northwest of the city of Richland, Washington, houses reactors, chemical-separation systems, and related facilities used for the production of special nuclear materials, as well as for activities associated with nuclear energy development. The 300 Area of the Hanford Site contains reactor fuel manufacturing facilities and several research and development laboratories. The 3718-F Alkali Metal Treatment and Storage Facility (3718-F Facility), located in the 300 Area, was used to store and treat alkali metal wastes. Therefore, it is subject to the regulatory requirements for the storage and treatment of dangerous wastes. Closure will be conducted pursuant to the requirements of the Washington Administrative Code (WAC) 173-303-610 (Ecology 1989) and 40 CFR 270.1. Closure also will satisfy the thermal treatment facility closure requirements of 40 CFR 265.381. This closure plan presents a description of the 3718-F Facility, the history of wastes managed, and the approach that will be followed to close the facility. Only hazardous constituents derived from 3718-F Facility operations will be addressed

  2. Freezing of liquid alkali metals as screened ionic plasmas

    International Nuclear Information System (INIS)

    Badirkhan, Z.; Rovere, M.; Tosi, M.P.

    1990-08-01

    The relationship between Wigner crystallization of the classical ionic plasma and the liquid-solid transition of alkali metals is examined within the density wave theory of freezing. Freezing of the classical plasma on a rigid neutralizing background into the bcc structure is first re-evaluated, in view of recent progress in the determination of its thermodynamic functions by simulation and of the known difficulties of the theory relating to the order parameter at the (200) star of reciprocal lattice vectors. Freezing into the fcc structure is also considered in this context and found to be unfavoured. On allowing for long-wavelength deformability of the background, the ensuing appearance of a volume change on freezing into the bcc structure is accompanied by reduced stability of the fluid phase and by an increase in the entropy of melting. Freezing of alkali metals into the bcc structure is next evaluated, taking their ionic pair structure as that of an ionic plasma reference fluid screened by conduction electrons and asking that the correct ionic coupling strength at liquid-solid coexistence should be approximately reproduced. The ensuring values of the volume and entropy changes across the phase transition, as estimated from the theory by two alternative routes, are in reasonable agreement with experiment. The order parameters of the phase transition, excepting the (200) one, conform rather closely to a Gaussian behaviour and yield a Lindemann ratio in reasonable agreement with the empirical value for melting of bcc crystals. It is suggested that ionic ordering at the (200) star in the metal may be (i) assisted by medium range ordering in the conduction electrons, as indicated by differences in X-ray and neutron diffraction intensities from the liquid, and/or (ii) quite small in the hot bcc solid. Such a possible premelting behaviour of bcc metals should be worth testing experimentally by diffraction. (author). 48 refs, 1 fig., 1 tab

  3. 50 years of superbases made from organolithium compounds and heavier alkali metal alkoxides

    Czech Academy of Sciences Publication Activity Database

    Lochmann, Lubomír; Janata, Miroslav

    2014-01-01

    Roč. 12, č. 5 (2014), s. 537-548 ISSN 1895-1066 R&D Projects: GA ČR GAP106/12/0844 Institutional support: RVO:61389013 Keywords : superbases * heavier alkali metal compounds * lithium-heavier alkali metal interchange Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.329, year: 2013

  4. Selective Metal-vapor Deposition on Organic Surfaces.

    Science.gov (United States)

    Tsujioka, Tsuyoshi

    2016-02-01

    Selective metal-vapor deposition signifies that metal-vapor atoms are deposited on a hard organic surface, but not on a soft (low glass transition temperature, low Tg ) surface. In this paper, we introduce the origin, extension, and applications of selective metal-vapor deposition. An amorphous photochromic diarylethene film shows light-controlled selective metal-vapor deposition, which is caused by a large Tg change based on photoisomerization, but various organic surfaces, including organic crystal and polymers, can be utilized for achieving selective metal-vapor deposition. Various applications of selective metal-vapor deposition, including cathode patterning of organic light-emitting devices, micro-thin-film fuses, multifunctional diffraction gratings, in-plane electrical bistability for memory devices, and metal-vapor integration, have been demonstrated. © 2015 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Development of standardized air-blown coal gasifier/gas turbine concepts for future electric power systems. Volume 3, Appendix B: NO{sub x} and alkali vapor control strategies: Final report

    Energy Technology Data Exchange (ETDEWEB)

    1990-07-01

    CRS Sirrine (CRSS) is evaluating a novel IGCC process in which gases exiting the gasifier are burned in a gas turbine combustion system. The turbine exhaust gas is used to generate additional power in a conventional steam generator. This results in a significant increase in efficiency. However, the IGCC process requires development of novel approaches to control SO{sub 2} and NO{sub x} emissions and alkali vapors which can damage downstream turbine components. Ammonia is produced from the reaction of coal-bound nitrogen with steam in the reducing zone of any fixed bed coal gasifier. This ammonia can be partially oxidized to NO{sub x} when the product gas is oxidized in a gas turbine combustor. Alkali metals vaporize in the high-temperature combustion zone of the gasifier and laser condense on the surface of small char or ash particles or on cooled metal surfaces. It these alkali-coated materials reach the gas turbine combustor, the alkali will revaporize condense on turbine blades and cause rapid high temperature corrosion. Efficiency reduction will result. PSI Technology Company (PSIT) was contracted by CRSS to evaluate and recommend solutions for NO{sub x} emissions and for alkali metals deposition. Various methods for NO{sub x} emission control and the potential process and economic impacts were evaluated. This included estimates of process performance, heat and mass balances around the combustion and heat transfer units and a preliminary economic evaluation. The potential for alkali metal vaporization and condensation at various points in the system was also estimated. Several control processes and evaluated, including an order of magnitude cost for the control process.

  6. Assessment of alkali metal coolants for the ITER blanket

    International Nuclear Information System (INIS)

    Natesan, K.; Reed, C.B.; Mattas, R.F.

    1994-01-01

    The blanket system is one of the most important components of a fusion reactor because it has a major impact on both the economics and safety of fusion energy. The primary functions of the blanket in a deuterium/tritium-fueled fusion reactor are to convert the fusion energy into sensible heat and to breed tritium for the fuel cycle. The Blanket Comparison and Selection Study, conducted earlier, described the overall comparative performance of different blanket concepts, including liquid metal, molten salt, water, and helium. This paper will discuss the ITER requirements for a self-cooled blanket concept with liquid lithium and for indirectly cooled concepts that use other alkali metals such as NaK. The paper will address the thermodynamics of interactions between the liquid metals (i.e., lithium and NaK) and structural materials (e.g., V-base alloys), together with associated corrosion/compatibility issues. Available experimental data will be used to assess the long-term performance of the first wall in a liquid metal environment

  7. Examination of Solubility Models for the Determination of Transition Metals within Liquid Alkali Metals

    Directory of Open Access Journals (Sweden)

    Jeremy Isler

    2016-06-01

    Full Text Available The experimental solubility of transition metals in liquid alkali metal was compared to the modeled solubility calculated using various equations for solubility. These equations were modeled using the enthalpy calculations of the semi-empirical Miedema model and various entropy calculations. The accuracy of the predicted solubility compared to the experimental data is more dependent on which liquid alkali metal is being examined rather than the transition metal solute examined. For liquid lithium the calculated solubility by the model was generally larger than experimental values, while for liquid cesium the modeling solubility was significantly smaller than the experimental values. For liquid sodium, potassium, and rubidium the experimental solubilities were within the range calculated by this study. Few data approached the predicted temperature dependence of solubility and instead most data exhibited a less pronounced temperature dependence.

  8. An alternative picture of alkali-metal-mediated metallation: cleave and capture chemistry.

    Science.gov (United States)

    Mulvey, Robert E

    2013-05-21

    This perspective article takes an alternative look at alkali-metal-mediated chemistry (exchange of a relatively inert C-H bond for a more reactive C-metal bond by a multicomponent reagent usually containing an alkali metal and a less electropositive metal such as magnesium or zinc). It pictures that the cleavage of selected C-H bonds can be accompanied by the capturing of the generated anion by the multi (Lewis acid)-(Lewis base) character of the residue of the bimetallic base. In this way small atoms or molecules (hydrides, oxygen-based anions) as well as sensitive organic anions (of substituted aromatic compounds, ethers or alkenes) can be captured. Cleave and capture reactions which occur in special positions on the organic substrate are also included.

  9. Hydration number of alkali metal ions determined by insertion in a conducting polymer

    DEFF Research Database (Denmark)

    Skaarup, Steen

    2008-01-01

    In aqueous solutions, the alkali metals ions are associated with a number of H2O molecules. A distinction is made between a primary solvent shell, (or inner solvation shell), consisting of H2O molecules directly coordinated to the metal ion, and a secondary (or outer) solvation shell, consisting....... The solvation of alkali metal ions has been discussed for many years without a clear consensus. This work presents a systematic study of the hydration numbers of the 5 alkali metal ions, using the electrochemical insertion of the ions in a conducting polymer (polypyrrole containing the large immobile anion DBS...

  10. Chemical vapor deposition of group IIIB metals

    Science.gov (United States)

    Erbil, A.

    1989-11-21

    Coatings of Group IIIB metals and compounds thereof are formed by chemical vapor deposition, in which a heat decomposable organometallic compound of the formula given in the patent where M is a Group IIIB metal, such as lanthanum or yttrium and R is a lower alkyl or alkenyl radical containing from 2 to about 6 carbon atoms, with a heated substrate which is above the decomposition temperature of the organometallic compound. The pure metal is obtained when the compound of the formula 1 is the sole heat decomposable compound present and deposition is carried out under nonoxidizing conditions. Intermetallic compounds such as lanthanum telluride can be deposited from a lanthanum compound of formula 1 and a heat decomposable tellurium compound under nonoxidizing conditions.

  11. 3718-F Alkali Metal Treatment and Storage Facility Closure Plan

    Energy Technology Data Exchange (ETDEWEB)

    None

    1991-12-01

    Since 1987, Westinghouse Hanford Company has been a major contractor to the U.S. Department of Energy-Richland Operations Office and has served as co-operator of the 3718-F Alkali Metal Treatment and Storage Facility, the waste management unit addressed in this closure plan. The closure plan consists of a Part A Dangerous waste Permit Application and a RCRA Closure Plan. An explanation of the Part A Revision (Revision 1) submitted with this document is provided at the beginning of the Part A section. The closure plan consists of 9 chapters and 5 appendices. The chapters cover: introduction; facility description; process information; waste characteristics; groundwater; closure strategy and performance standards; closure activities; postclosure; and references.

  12. Studying thermal dehydration of double nickel alkali metal pyrophosphates

    International Nuclear Information System (INIS)

    Bykanova, T.A.; Lavrov, A.V.; AN SSSR, Moscow. Inst. Obshchej i Neorganicheskoj Khimii)

    1978-01-01

    The methods of thermogravimetry, paper chromatography, infrared spectroscopy and X-ray phase analysis were used in studying the process of thermal dehydration of pyrophosphates of the M 2 Ni 3 (P 2 O 7 ) 2 xnH 2 O type (where n=6, 10; M=Na, K, Rb, Cs, NH 4 ). The dehydration of Cs 2 Ni 3 (P 2 O 7 ) 2 x10H 2 O proceeds in a single stage (endothermal effect at 210 deg C). The exothermal effects at 730 and 690 deg C correspond to the crystallization of the amorphous dehydration products. It has been established that binary pyrophosphates of nickel with alkali metals decompose when heated into Ni 3 (PO 4 ) 2 +MPO 4

  13. 3718-F Alkali Metal Treatment and Storage Facility Closure Plan

    International Nuclear Information System (INIS)

    1991-12-01

    Since 1987, Westinghouse Hanford Company has been a major contractor to the U.S. Department of Energy-Richland Operations Office and has served as co-operator of the 3718-F Alkali Metal Treatment and Storage Facility, the waste management unit addressed in this closure plan. The closure plan consists of a Part A Dangerous waste Permit Application and a RCRA Closure Plan. An explanation of the Part A Revision (Revision 1) submitted with this document is provided at the beginning of the Part A section. The closure plan consists of 9 chapters and 5 appendices. The chapters cover: introduction; facility description; process information; waste characteristics; groundwater; closure strategy and performance standards; closure activities; postclosure; and references

  14. Surface free energy of alkali and transition metal nanoparticles

    International Nuclear Information System (INIS)

    Aqra, Fathi; Ayyad, Ahmed

    2014-01-01

    Graphical abstract: Size dependent surface free energy of spherical, cubic and disk Au nanoparticles. - Highlights: • A model to account for the surface free energy of metallic nanoparticles is described. • The model requires only the cohesive energy of the nanoparticle. • The surface free energy of a number of metallic nanoparticles has been calculated, and the obtained values agree well with existing data. • Surface energy falls down very fast when the number of atoms is less than hundred. • The model is applicable to any metallic nanoparticle. - Abstract: This paper addresses an interesting issue on the surface free energy of metallic nanoparticles as compared to the bulk material. Starting from a previously reported equation, a theoretical model, that involves a specific term for calculating the cohesive energy of nanoparticle, is established in a view to describe the behavior of surface free energy of metallic nanoparticles (using different shapes of particle: sphere, cube and disc). The results indicate that the behavior of surface energy is very appropriate for spherical nanoparticle, and thus, it is the most realistic shape of a nanoparticle. The surface energy of copper, silver, gold, platinum, tungsten, molybdenum, tantalum, paladium and alkali metallic nanoparticles is only prominent in the nanoscale size, and it decreases with the decrease of nanoparticle size. Thus, the surface free energy plays a more important role in determining the properties of nanoparticles than in bulk materials. It differs from shape to another, and falls down as the number of atoms (nanoparticle size) decreases. In the case of spherical nanoparticles, the onset of the sharp decrease in surface energy is observed at about 110 atom. A decrease of 16% and 45% in surface energy is found by moving from bulk to 110 atom and from bulk to 5 atom, respectively. The predictions are consistent with the reported data

  15. Release characteristics of alkali and alkaline earth metallic species during biomass pyrolysis and steam gasification process.

    Science.gov (United States)

    Long, Jiang; Song, Hu; Jun, Xiang; Sheng, Su; Lun-Shi, Sun; Kai, Xu; Yao, Yao

    2012-07-01

    Investigating the release characteristics of alkali and alkaline earth metallic species (AAEMs) is of potential interest because of AAEM's possible useful service as catalysts in biomass thermal conversion. In this study, three kinds of typical Chinese biomass were selected to pyrolyse and their chars were subsequently steam gasified in a designed quartz fixed-bed reactor to investigate the release characteristics of alkali and alkaline earth metallic species (AAEMs). The results indicate that 53-76% of alkali metal and 27-40% of alkaline earth metal release in pyrolysis process, as well as 12-34% of alkali metal and 12-16% of alkaline earth metal evaporate in char gasification process, and temperature is not the only factor to impact AAEMs emission. The releasing characteristics of AAEMs during pyrolysis and char gasification process of three kinds of biomass were discussed in this paper. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. [Measurement of atomic number of alkali vapor and pressure of buffer gas based on atomic absorption].

    Science.gov (United States)

    Zheng, Hui-jie; Quan, Wei; Liu, Xiang; Chen, Yao; Lu, Ji-xi

    2015-02-01

    High sensitivitymagnetic measurementscanbe achieved by utilizing atomic spinmanipulation in the spin-exchange-relaxation-free (SERF) regime, which uses an alkali cell as a sensing element. The atomic number density of the alkali vapor and the pressure of the buffer gasare among the most important parameters of the cell andrequire accurate measurement. A method has been proposed and developedto measure the atomic number density and the pressure based on absorption spectroscopy, by sweeping the absorption line and fittingthe experiment data with a Lorentzian profile to obtainboth parameters. Due to Doppler broadening and pressure broadening, which is mainly dominated by the temperature of the cell and the pressure of buffer gas respectively, this work demonstrates a simulation of the errorbetween the peaks of the Lorentzian profile and the Voigt profile caused by bothfactors. The results indicates that the Doppler broadening contribution is insignificant with an error less than 0.015% at 313-513 K for a 4He density of 2 amg, and an error of 0.1% in the presence of 0.6-5 amg at 393 K. We conclude that the Doppler broadening could be ignored under above conditions, and that the Lorentzianprofile is suitably applied to fit the absorption spectrumobtainingboth parameters simultaneously. In addition we discuss the resolution and the instability due to thelight source, wavelength and the temperature of the cell. We find that the cell temperature, whose uncertainty is two orders of magnitude larger than the instability of the light source and the wavelength, is one of the main factors which contributes to the error.

  17. Metal vapor vacuum arc ion sources

    International Nuclear Information System (INIS)

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

    1990-06-01

    We have developed a family of metal vapor vacuum are (MEVVA) high current metal ion sources. The sources were initially developed for the production of high current beams of metal ions for heavy ion synchrotron injection for basic nuclear physics research; more recently they have also been used for metal ion implantation. A number of different embodiments of the source have been developed for these specific applications. Presently the sources operate in a pulsed mode, with pulse width of order 1 ms and repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV, and since the ions produced in the vacuum arc plasma are in general multiply ionized the ion energy is up to several hundred keV. Beam current is up to several Amperes peak and around 10 mA time averaged delivered onto target. Nearly all of the solid metals of the Periodic Table have been use to produce beam. A number of novel features have been incorporated into the sources, including multiple cathodes and the ability to switch between up to 18 separate cathode materials simply and quickly, and a broad beam source version as well as miniature versions. here we review the source designs and their performance. 45 refs., 7 figs

  18. Tuning the electronic structure of graphene through alkali metal and halogen atom intercalation

    Science.gov (United States)

    Ahmad, Sohail; Miró, Pere; Audiffred, Martha; Heine, Thomas

    2018-04-01

    The deposition, intercalation and co-intercalation of heavy alkali metals and light halogens atoms in graphene mono- and bilayers have been studied using first principles density-functional calculations. Both the deposition and the intercalation of alkali metals gives rise to n-type doping due to the formation of M+-C- pairs. The co-intercalation of a 1:1 ratio of alkali metals and halogens derives into the formation of ionic pairs among the intercalated species, unaltering the electronic structure of the layered material.

  19. Method and composition for testing for the presence of an alkali metal

    Science.gov (United States)

    Guon, Jerold

    1981-01-01

    A method and composition for detecting the presence of an alkali metal on the surface of a body such as a metal plate, tank, pipe or the like is provided. The method comprises contacting the surface with a thin film of a liquid composition comprising a light-colored pigment, an acid-base indicator, and a nonionic wetting agent dispersed in a liquid carrier comprising a minor amount of water and a major amount of an organic solvent selected from the group consisting of the lower aliphatic alcohols, ketones and ethers. Any alkali metal present on the surface in elemental form or as an alkali metal hydroxide or alkali metal carbonate will react with the acid-base indicator to produce a contrasting color change in the thin film, which is readily discernible by visual observation or automatic techniques.

  20. Method and composition for testing for the presence of an alkali metal

    International Nuclear Information System (INIS)

    Guon, J.

    1981-01-01

    A method and composition for detecting the presence of an alkali metal on the surface of a body such as a metal plate, tank, pipe or the like is provided. The method comprises contacting the surface with a thin film of a liquid composition comprising a light-colored pigment, an acid-base indicator, and a nonionic wetting agent dispersed in a liquid carrier comprising a minor amount of water and a major amount of an organic solvent selected from the group consisting of the lower aliphatic alcohols, ketones and ethers. Any alkali metal present on the surface in elemental form or as an alkali metal hydroxide or alkali metal carbonate will react with the acid-base indicator to produce a contrasting color change in the thin film, which is readily discernible by visual observation or automatic techniques

  1. The alkali and alkaline earth metal doped ZnO nanotubes: DFT studies

    International Nuclear Information System (INIS)

    Peyghan, Ali Ahmadi; Noei, Maziar

    2014-01-01

    Doping of several alkali and alkaline earth metals into sidewall of an armchair ZnO nanotube has been investigated by employing the density functional theory in terms of energetic, geometric, and electronic properties. It has been found that doping processes of the alkali and alkaline metals are endothermic and exothermic, respectively. Based on the results, contrary to the alkaline metal doping, the electronic properties of the tube are much more sensitive to alkali metal doping so that it is transformed from intrinsic semiconductor with HOMO–LUMO energy gap of 3.77 eV to an extrinsic semiconductor with the energy gap of ∼1.11–1.95 eV. The doping of alkali and alkaline metals increases and decreases the work function of the tube, respectively, which may influence the electron emission from the tube surface

  2. Screen-printed electrode for alkali-metal thermoelectric converter

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, T.; Shibata, K.; Tsuchida, K.; Kato, A. (Kyushu Univ., Fukuoka (Japan). Faculty of Engineering)

    1992-06-01

    An alkali-metal thermoelectric converter (AMTEC) is a device for the direct conversion of thermal to electric energy. An AMTEC contains sodium as working fluid and is divided into a high-temperature region (900-1300 K) and a low-temperature region (400-800 K) by [beta]''-alumina solid electrolyte. A high-performance electrode for an AMTEC must have good electrical conductivity, make a strong physical bond with low contact resistance to [beta]''-alumina, be highly permeable to sodium vapour, resist corrosion by sodium and have a low rate of evaporation at the operating temperature of the AMTEC. We have previously investigated the interaction of nitrides and carbides of some transition-metals (groups IV, V and VI) with [beta],[beta]''-alumina or liquid sodium (about 700degC) with the objective of finding a better electrode material for an AMTEC. The results showed that TiN, TiC, NbN and NbC were good candidates for AMTEC electrodes. We also showed that porous TiN film with low resistance can be prepared by the screen-printing method. In the present work the porous NbN film was prepared by the screen-printing method and the performance as the electrode of an AMTEC was examined. For comparison, the performance of TiN and Mo electrodes prepared by the screen-printing method was also examined. (author).

  3. Electron core ionization in compressed alkali metal cesium

    Science.gov (United States)

    Degtyareva, V. F.

    2018-01-01

    Elements of groups I and II in the periodic table have valence electrons of s-type and are usually considered as simple metals. Crystal structures of these elements at ambient pressure are close-packed and high-symmetry of bcc and fcc-types, defined by electrostatic (Madelung) energy. Diverse structures were found under high pressure with decrease of the coordination number, packing fraction and symmetry. Formation of complex structures can be understood within the model of Fermi sphere-Brillouin zone interactions and supported by Hume-Rothery arguments. With the volume decrease there is a gain of band structure energy accompanied by a formation of many-faced Brillouin zone polyhedra. Under compression to less than a half of the initial volume the interatomic distances become close to or smaller than the ionic radius which should lead to the electron core ionization. At strong compression it is necessary to assume that for alkali metals the valence electron band overlaps with the upper core electrons, which increases the valence electron count under compression.

  4. Effect of charging on silicene with alkali metal atom adsorption

    Science.gov (United States)

    Li, Manman; Li, Zhongyao; Gong, Shi-Jing

    2018-02-01

    Based on first-principles calculations, we studied the effects of charging on the structure, binding energy and electronic properties of silicene with alkali metal (AM) atom (Li, Na or K) adsorption. In AMSi2, electron doping enlarges the lattice constant of silicene, while the influence of hole doping is non-monotonic. In AMSi8, the lattice constant increases/decreases almost linearly with the increase in electron/hole doping. In addition, the AM-Si vertical distance can be greatly enlarged by excessive hole doping in both AMSi2 and AMSi8 systems. When the hole doping is as large as  +e per unit cell, both AMSi2 and AMSi8 can be transformed from metal to semiconductor. However, the binding energy would be negative in the AM+ Si2 semiconductor. It suggests AM+ Si2 is unstable in this case. In addition, the electron doping and the AM-Si vertical distance would greatly influence the band gap of silicene in LiSi8 and NaSi8, while the band gap in KSi8 is relatively stable. Therefore, KSi8 may be a more practicable material in nanotechnology.

  5. In situ formation of coal gasification catalysts from low cost alkali metal salts

    Science.gov (United States)

    Wood, Bernard J.; Brittain, Robert D.; Sancier, Kenneth M.

    1985-01-01

    A carbonaceous material, such as crushed coal, is admixed or impregnated with an inexpensive alkali metal compound, such as sodium chloride, and then pretreated with a stream containing steam at a temperature of 350.degree. to 650.degree. C. to enhance the catalytic activity of the mixture in a subsequent gasification of the mixture. The treatment may result in the transformation of the alkali metal compound into another, more catalytically active, form.

  6. Enhancing Skin Permeation of Biphenylacetic Acid (BPA) Using Salt Formation with Organic and Alkali Metal Bases

    OpenAIRE

    PAWAR, Vijay; NAIK, Prashant; GIRIDHAR, Rajani; YADAV, Mange Ram

    2014-01-01

    In the present study, a series of organic and alkali metal salts of biphenylacetic acid (BPA) have been prepared and evaluated in vitro for percutaneous drug delivery. The physicochemical properties of BPA salts were determined using solubility measurements, DSC, and IR. The DSC thermogram and FTIR spectra confirmed the salt formation with organic and alkali metal bases. Among the series, salts with organic amines (ethanolamine, diethanolamine, triethanol-amine, and diethylamine) had lowered ...

  7. Removal of oxides from alkali metal melts by reductive titration to electrical resistance-change end points

    Science.gov (United States)

    Tsang, Floris Y.

    1980-01-01

    Alkali metal oxides dissolved in alkali metal melts are reduced with soluble metals which are converted to insoluble oxides. The end points of the reduction is detected as an increase in electrical resistance across an alkali metal ion-conductive membrane interposed between the oxide-containing melt and a material capable of accepting the alkali metal ions from the membrane when a difference in electrical potential, of the appropriate polarity, is established across it. The resistance increase results from blocking of the membrane face by ions of the excess reductant metal, to which the membrane is essentially non-conductive.

  8. Electrochemistry of ytterbium (III) in molten alkali metal chlorides

    Energy Technology Data Exchange (ETDEWEB)

    Smolenski, V.; Novoselova, A. [Institute of High-Temperature Electrochemistry, Ural Division, Russian Academy of Science, Ekaterinburg, 620219 (Russian Federation); Osipenko, A. [Research Institute of Atomic Reactors, Dimitrovgrad-10, Ulyanovsk Region, 433010 (Russian Federation); Caravaca, C. [High Level Waste Unit, Nuclear Fission Division, CIEMAT, Madrid, 28040 (Spain); Cordoba, G. de [High Level Waste Unit, Nuclear Fission Division, CIEMAT, Madrid, 28040 (Spain)], E-mail: g.cordoba@ciemat.es

    2008-12-30

    This work presents the electrochemical study of Yb(III) ions in molten alkali metal chlorides in the temperature range 723-1073 K. Transient electrochemical techniques such as linear sweep, cyclic and square wave voltammetry, and potentiometry at zero current have been used to investigate the reduction mechanism, transport parameters and thermodynamic properties of the reaction YbCl{sub 2} + 1/2Cl{sub 2} = YbCl{sub 3} The results obtained show that the reduction reaction Yb(III) + e{sup -} {r_reversible} Yb(II) is reversible being controlled by the rate of the mass transfer. The diffusion coefficient of [YbCl{sub 6}]{sup 3-} complex ions has been determined at different temperatures in the fused eutectic LiCl-KCl, the equimolar NaCl-KCl and the CsCl media. The apparent standard potential of the soluble-soluble redox system Yb(III)/Yb(II) has been obtained by cyclic voltammetry. The influence of the nature of the solvent on the electrochemical and thermodynamic properties of ytterbium compounds is discussed.

  9. Metabolic data and retention functions for the intracellular alkali metals

    International Nuclear Information System (INIS)

    Leggett, R.W.

    1983-05-01

    This report is a collection and discussion of the information needed for interpretation of bioassay results for the important radioelement cesium (Cs), as well as a comparison of the physiological behavior of Cs with that of potassium (K) and rubidium (Rb). This report is intended not only as an investigation of the metabolism of the intracellular alkali metals by humans, but also as a case study of the limitations inherent in applying ICRP 30 retention models in bioassay programs. In particular, the relationship between the mathematical components of the ICRP 30 retention model for Cs and actual physiological or anatomical entities is examined, and ways are suggested for modifying the ICRP 30 models for Cs, Rb, and K to yield better accuracy and to better account for biological variability among humans. Although the physiological behaviors of both Rb and Cs resemble that of K, quantitative differences arise because of differences in transport of K, Rb, and Cs by cell membranes. The resemblance is close enough, however, that total body K can be used as an index of whole-body retention times of Rb and Cs, and of compartmental fractions of Cs. The Cs half-time based on total body K appears to be within a factor of 1.5 for all adults. Total body K may be determined by whole-body gamma-ray counting techniques and hence is a reasonable index to use in many bioassay programs

  10. Structural and energetic characteristics of alkali metal hexachlorouranates (5)

    International Nuclear Information System (INIS)

    Kudryashov, V.L.; Suglobova, I.G.; Chirkst, D.Eh.

    1978-01-01

    Structure types and lattice parameters of alkali metal hexachlorouranates (5) have been determined by indicating the X-ray diffraction patterns of polycrystals. α-NaVCl 6 has a cubic structure of the Csub(s)PFsub(6) type; β-NaVCl 6 -trigonal lattice of the LiSbF 6 type; KVCl 6 and RbVCl 6 crystallize in the RbPaF 6 structure type; CsVCl 6 is isomorphous to CsPF 6 . Enthalpy values of hexachlorouranates (5) dissolution in 0.5% FeCl 3 solution and in 2% HCl have been measured and the standard enthalpy values of their formation have been calculated. The energies of crystal lattices and of the uranium-uranium-chlorine bonds have been calculated. When uranium coordination number is 6 the energy of the uranium-chlorine bond is 99.6+-0.5; when this number is 8 the energy equals 101.9+-0.5 kcal/mol

  11. Alkali Metal Variation and Twisting of the FeNNFe Core in Bridging Diiron Dinitrogen Complexes.

    Science.gov (United States)

    McWilliams, Sean F; Rodgers, Kenton R; Lukat-Rodgers, Gudrun; Mercado, Brandon Q; Grubel, Katarzyna; Holland, Patrick L

    2016-03-21

    Alkali metal cations can interact with Fe-N2 complexes, potentially enhancing back-bonding or influencing the geometry of the iron atom. These influences are relevant to large-scale N2 reduction by iron, such as in the FeMoco of nitrogenase and the alkali-promoted Haber-Bosch process. However, to our knowledge there have been no systematic studies of a large range of alkali metals regarding their influence on transition metal-dinitrogen complexes. In this work, we varied the alkali metal in [alkali cation]2[LFeNNFeL] complexes (L = bulky β-diketiminate ligand) through the size range from Na(+) to K(+), Rb(+), and Cs(+). The FeNNFe cores have similar Fe-N and N-N distances and N-N stretching frequencies despite the drastic change in alkali metal cation size. The two diketiminates twist relative to one another, with larger dihedral angles accommodating the larger cations. In order to explain why the twisting has so little influence on the core, we performed density functional theory calculations on a simplified LFeNNFeL model, which show that the two metals surprisingly do not compete for back-bonding to the same π* orbital of N2, even when the ligand planes are parallel. This diiron system can tolerate distortion of the ligand planes through compensating orbital energy changes, and thus, a range of ligand orientations can give very similar energies.

  12. Effects of Alkali-Metal Ions and Counter Ions in Sn-Beta-Catalyzed Carbohydrate Conversion.

    Science.gov (United States)

    Elliot, Samuel G; Tolborg, Søren; Madsen, Robert; Taarning, Esben; Meier, Sebastian

    2018-02-26

    Alkali-metal ions have recently been shown to strongly influence the catalytic behavior of stannosilicates in the conversion of carbohydrates. An effect of having alkali-metal ions present is a pronounced increase in selectivity towards methyl lactate. Mechanistic details of this effect have remained obscure and are herein addressed experimentally through kinetic experiments and isotope tracking. The presence of alkali-metal ions has a differential effect in competing reaction pathways and promotes the rate of carbon-carbon bond breakage of carbohydrate substrates, but decreases the rates of competing dehydration pathways. Further addition of alkali-metal ions inhibits the activity of Sn-Beta in all major reaction pathways. The alkali-metal effects on product distribution and on the rate of product formation are similar, thus pointing to a kinetic reaction control and to irreversible reaction steps in the main pathways. Additionally, an effect of the accompanying basic anions is shown, supposedly facilitating the cation exchange and eliciting a different concentration-dependent effect to that of neutral alkali-metal salts. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. On the origin of alkali metals in Europa exosphere

    Science.gov (United States)

    Ozgurel, Ozge; Pauzat, Françoise; Ellinger, Yves; Markovits, Alexis; Mousis, Olivier; LCT, LAM

    2016-10-01

    At a time when Europa is considered as a plausible habitat for the development of an early form of life, of particular concern is the origin of neutral sodium and potassium atoms already detected in its exosphere (together with magnesium though in smaller abundance), since these atoms are known to be crucial for building the necessary bricks of prebiotic species. However their origin and history are still poorly understood. The most likely sources could be exogenous and result from the contamination produced by Io's intense volcanism and/or by meteoritic bombardment. These sources could also be endogenous if these volatile elements originate directly from Europa's icy mantle. Here we explore the possibility that neutral sodium and potassium atoms were delivered to the satellite's surface via the upwelling of ices formed in contact with the hidden ocean. These metallic elements would have been transferred as ions to the ocean at early epochs after Europa's formation, by direct contact of water with the rocky core. During Europa's subsequent cooling, the icy layers formed at the top of the ocean would have kept trapped the sodium and potassium, allowing their future progression to the surface and final identification in the exosphere of the satellite. To support this scenario, we have used chemistry numerical models based on first principle periodic density functional theory (DFT). These models are shown to be well adapted to the description of compact ice and are capable to describe the trapping and neutralization of the initial ions in the ice matrix. The process is found relevant for all the elements considered, alkali metals like Na and K, as well as for Mg and probably for Ca, their respective abundances depending essentially of their solubility and chemical capabilities to blend with water ices.

  14. Properties of solvated electrons, alkali anions and other species in metal solutions and kinetics of cation and electron exchange reactions. Final report

    International Nuclear Information System (INIS)

    Dye, J.L.

    1979-01-01

    The properties of solutions of alkali metals in amine solvents were studied by optical, ETR, NMR and electrochemical methods. Complexation of the alkali cations by crown ethers and cryptands permitted the preparation of concentrated solutions of alkali metals in amine and ether solvents. Extensive alkali metal NMR studies of the exchange of M + with crown-ethers and cryptands and of the alkali metal anion, M - , were made. The first crystalline salt of an alkali metal anion, Na + Cryptand [2.2.2]Na - was synthesized and characterized and led to the preparation of other alkali metal anion salts. This research provided the foundation for continuing studies of crystalline alkalide salts

  15. Method for inhibiting alkali metal corrosion of nickel-containing alloys

    Science.gov (United States)

    DeVan, Jackson H.; Selle, James E.

    1983-01-01

    Structural components of nickel-containing alloys within molten alkali metal systems are protected against corrosion during the course of service by dissolving therein sufficient aluminum, silicon, or manganese to cause the formation and maintenance of a corrosion-resistant intermetallic reaction layer created by the interaction of the molten metal, selected metal, and alloy.

  16. Review of alkali metal and refractory alloy compatibility for Rankine cycle applications

    International Nuclear Information System (INIS)

    DiStefano, J.R.

    1989-01-01

    The principal corrosion mechanisms in refractory metal-alkali systems are dissolution, mass transfer, and impurity reactions. In general, niobium, tantalum, molybdenum, and tungsten have low solubilities in the alkali metals, even to very high temperatures, and static corrosion studies have verified that the systems are basically compatible. Loop studies with niobium and tantalum based alloys do not indicate any serious problems due to temperature gradient mass transfer. Above 1000 K, dissimilar metal mass transfer is noted between the refractory metals and iron or nickel based alloys. The most serious corrosion problems encountered are related to impurity reactions associated with oxygen

  17. Infrared multiple photon dissociation action spectroscopy of alkali metal cation-cyclen complexes: Effects of alkali metal cation size on gas-phase conformation

    NARCIS (Netherlands)

    Austin, C.A.; Chen, Y.; Kaczan, C.M.; Berden, G.; Oomens, J.; Rodgers, M.T.

    2013-01-01

    The gas-phase structures of alkali metal cationized complexes of cyclen (1,4,7,10-tetraazacyclododecane) are examined via infrared multiple photon dissociation (IRMPD) action spectroscopy and electronic structure theory calculations. The measured IRMPD action spectra of four M+(cyclen) complexes are

  18. Active stabilization of alkali-atom vapor density with a solid-state electrochemical alkali-atom source.

    Science.gov (United States)

    Kang, Songbai; Mott, Russell P; Mis, Allison V; Roper, Christopher S; Donley, Elizabeth A; Kitching, John

    2018-02-05

    We report a demonstration of vapor-phase Rubidium (Rb) density stabilization in a vapor cell using a solid-state electrochemical Rb source device. Clear Rb density stabilization is observed. Further demonstrations show that the temperature coefficient for Rb density can be reduced more than 100 times when locked and the device's power consumption is less than 10 mW. Preliminary investigation of the locking dynamic range shows that the Rb density is well stabilized when the initial density is five times higher (33 × 10 9 /cm 3 ) than the set point density (6 × 10 9 /cm 3 ). Active stabilization with this device is of high interest for portable cold-atom microsystems where large ambient temperature working ranges and low power consumption are required.

  19. Thorium valency in molten alkali halides in equilibrium with metallic thorium

    International Nuclear Information System (INIS)

    Smirnov, M.V.; Kudyakov, V.Ya.

    1983-01-01

    Metallic thorium is shown to corrode in molten alkali halides even in the absence of external oxidizing agents, alkali cations acting as oxidizing agents. Its corrosion rate grows in the series of alkali chlorides from LiCl to CsCl at constant temperature. Substituting halide anions for one another exerts a smaller influence, the rate rising slightly in going from chlorides to bromides and iodides, having the same alkali cations. Thorium valency is determined coulometrically, the metal being dissolved anodically in molten alkali halides and their mixtures. In fluoride melts it is equal to 4 but in chloride, bromide and iodide ones, as a rule, it has non-integral values between 4 and 2 which diminish as the temperature is raised, as the thorium concentration is lowered, as the radii of alkali cations decrease and those of halide anions increase. The emf of cells Th/N ThHlsub(n) + (1-N) MHl/MHl/C, Hlsub(2(g)) where Hl is Cl, Br or I, M is Li, Na, K, Cs or Na + K, and N < 0.05, is measured as a function of concentration at several temperatures. Expressions are obtained for its concentration dependence. The emf grows in the series of alkali chlorides from LiCl to CsCl, other conditions being equal. (author)

  20. Coordination chemistry insights into the role of alkali metal promoters in dinitrogen reduction.

    Science.gov (United States)

    Connor, Gannon P; Holland, Patrick L

    2017-05-15

    The Haber-Bosch process is a major contributor to fixed nitrogen that supports the world's nutritional needs and is one of the largest-scale industrial processes known. It has also served as a testing ground for chemists' understanding of surface chemistry. Thus, it is significant that the most thoroughly developed catalysts for N 2 reduction use potassium as an electronic promoter. In this review, we discuss the literature on alkali metal cations as promoters for N 2 reduction, in the context of the growing knowledge about cooperative interactions between N 2 , transition metals, and alkali metals in coordination compounds. Because the structures and properties are easier to characterize in these compounds, they give useful information on alkali metal interactions with N 2 . Here, we review a variety of interactions, with emphasis on recent work on iron complexes by the authors. Finally, we draw conclusions about the nature of these interactions and areas for future research.

  1. Gas phase hydrogen/deuterium exchange of arginine and arginine dipeptides complexed with alkali metals.

    Science.gov (United States)

    Mertens, Laura A; Marzluff, Elaine M

    2011-08-25

    The hydrogen/deuterium (H/D) exchange of protonated and alkali-metal cationized Arg-Gly and Gly-Arg peptides with D(2)O in the gas phase was studied using electrospray ionization quadropole ion trap mass spectrometry. The Arg-Gly and Gly-Arg alkali metal complexes exchange significantly more hydrogens than protonated Arg-Gly and Gly-Arg. We propose a mechanism where the peptide shifts between a zwitterionic salt bridge and nonzwitterionic charge solvated conformations. The increased rate of H/D exchange of the alkali metal complexes is attributed to the peptide metal complexes' small energy difference between the salt-bridge conformation and the nonzwitterionic charge-solvated conformation. Implications for the applicability of this mechanism to other zwitterionic systems are discussed. © 2011 American Chemical Society

  2. THE DISTRIBUTION OF COMMERCIAL CROWN ETHER DC18C6 AND THE EXTRACTION STUDY OF ALKALI AND EARTH ALKALI METALS

    Directory of Open Access Journals (Sweden)

    Bambang Rusdiarso

    2010-06-01

    Full Text Available Distribution of A and B isomers of crown-ether DC18C6 on their organic and water phases (chloride, nitrate and sulphocyanide salts and extraction of alkali and earth alkali metals has been studied. In LiCl 0.1 M environment, lithium extraction could be ignored. The presence of extracted potassium metal may affect the crown ether DC18C6 distribution albeit only a little. In KNO3 0.1 M environment, the distribution coefficient values (d were 6.1 and 10.3 for A and B isomers, respectively ; while in KCl  0.1 M environment the values were 4.9 and 11.8, respectively. In KSCN 0.1 M, d values for A and B isomers were 40.4 and 36.6, respectively, which were higher than the value obtained from both KNO3 and KCl  0.1 M environments. Caesium metal extraction using DC18C6 occurred weakly, up to only 5%. Strontium extraction using DC18C6 achieved better yield than the caesium extraction. The percentage of extraction increased under organic solvent according to the following: toluene (4% < chloroform (28% < TBP (35%.   Keywords: distribution, crown-ether DC18C6, extraction.

  3. Molybdenum/alkali metal/ethylene glycol complexes useful as epoxidation catalysts

    International Nuclear Information System (INIS)

    Marquis, E.T.; Sanderson, J.R.; Keating, K.P.

    1987-01-01

    This patent describes a clear, storage stable solution of a molybdenum/alkali metal/ethylene glycol complex in ethylene glycol made by the process comprising: reacting at an elevated temperature between about 25 0 and 150 0 C a solid ammonium molybdate or a hydrate thereof and a solid alkali metal molybdate or a hydrate thereof with ethylene glycol, such that the ratio of moles of ethylene glycol to total gram atoms of molybdenum in the molybdates ranges from about 7:10 to 10:1, and the ratio of gram atoms of molybdenum in the ammonium molybdate or hydrate thereof to gram atoms of molybdenum in the alkali metal molybdate is from about 1:1 to about 20:1 to thereby provide a reaction product composed of a solution of an alkali metal-containing complex of molybdenum, alkali metal and ethylene glycol and by-products, including water, in the ethylene glycol and subsequently stripping the solution at a reduced pressure to remove from about 5 to about 25% of the reaction product, as distillate, to thereby provide a storage stable solution of the complex in the ethylene glycol having a molybdenum content of about 6 wt. % to about 20 wt. %, a water concentration of about 0.1 wt. % to about 6 wt. % and an acid number of more than about 60

  4. Recent advances in Alkali Metal Thermoelectric Converter (AMTEC) electrode performance and modeling. [for space power systems

    Science.gov (United States)

    Bankston, C. P.; Williams, R. M.; Jeffries-Nakamura, B.; Loveland, M. E.; Underwood, M. L.

    1988-01-01

    The Alkali Metal Thermoelectric Converter (AMTEC) is a direct energy conversion device, utilizing a high sodium vapor pressure or activity ratio across a beta-double prime-alumina solid electrolyte (BASE). This paper describes progress on the remaining scientific issue which must be resolved to demonstrate AMTEC feasibility for space power systems: a stable, high power density electrode. Two electrode systems have recently been discovered at JPL that now have the potential to meet space power requirements. One of these is a very thin sputtered molybdenum film, less than 0.5 micron thick, with overlying current collection grids. This electrode has experimentally demonstrated stable performance at 0.4-0.5 W/sq cm for hundreds of hours. Recent modeling results show that at least 0.7 W/sq cm can be achieved. The model of electrode performance now includes all loss mechanisms, including charge transfer resistances at the electrode/electrolyte interface. A second electrode composition, cosputtered platinum/tungsten, has demonstrated 0.8 W/sq cm for 160 hours. Systems studies show that a stable electrode performance of 0.6 W/sq cm will enable high efficiency space power systems.

  5. Alkali earth metal extraction by zirconium salt of dibutylphosphoric acid

    International Nuclear Information System (INIS)

    Zil'berman, B.Ya.; Fedorov, Yu.S.; Shmidt, O.V.; Egorova, O.N.

    2006-01-01

    Zirconium salt of dibutyl phosphoric acid (ZS HDBP) could be used as a TBP-compatible solvent for the treatment of liquid radwaste containing long-lived radionuclides, strontium in particular. The alkali earth metals behaviour during their extraction with ZS HDBP and the influence of TBP on the extraction properties of ZS HDBP were investigated. The maximum of Sr extraction was observed at the molar ratio of Zr:HDBP = 1:9, which is also optimal for TPE and RE extraction. Distribution coefficients increase in the series Ba 3 ). Increase of nitric acid concentration resulted in a decrease of the Sr distribution coefficient with a slope of -3. The distribution coefficients of Sr showed quadratic dependence on the HDBP concentration. The presence of TBP in the solvent resulted in a minor decrease in Sr extraction, this effect being significantly lower than for TPE and RE during their extraction by ZS HDBP. At the same time, full saturation of solvent with Sr was not reached because of precipitation in the solvent phase. When xylene was used as the polar diluent for TBP, the influence of TBP on Sr extraction by ZS HDBP was not as significant as for the hydrocarbons, and the Sr distribution coefficients were ten times lower. Solvent saturation curves for Sr extraction by 0.4 mol/L ZS HDBP with xylene at Zr:HDBP = 1:9 showed that in the absence of TBP, the maximum solvent loading reached 0.014 mol/L Sr, which corresponded to Zr : Sr = 3:1. The solubility of Ca in the extract was significantly lower than that of Sr. A centrifugal contactor rig trial was carried out with the use of simulated solutions and 0.4 mol/L ZS HDBP in 30 % TBP with Isopar-L as the solvent. The extraction was performed while neutralizing the aqueous solution in the flow to a residual acidity of 0.05-0.2 mol/L, the stripping was performed by using 1-3 mol/L HNO 3 . Sr concentrating of 3 was achieved by purification from Cs of 50-100 during extraction from TPE and RE during selective stripping. Special

  6. Superconductivity and electrical resistivity in alkali metal doped ...

    Indian Academy of Sciences (India)

    We consider a two-peak model for the phonon density of states to investigate the nature of electron pairing mechanism for superconducting state in fullerides. We first study the intercage interactions between the adjacent C60 cages and expansion of lattice due to the intercalation of alkali atoms based on the spring model to ...

  7. Energy loss spectroscopy study of Si(111)--alkali metal interfaces at low temperatures

    International Nuclear Information System (INIS)

    Avci, R.

    1986-01-01

    Studies are made at approx.150 K under ultrahigh vacuum conditions on a wide range of alkali metal coverages on Si(111)-7 x 7. Negative second-derivative backscattered electron energy loss spectroscopy is used with 100 eV primary electrons. The interaction of the alkali metals with the silicon substrate goes through two stages as a function of alkali coverage: In the initial coverages, for less than approx.0.3 monolayer of alkali atoms, the basic reaction is that of charge transfer from the alkali atoms to the Si surface with a loss peak at approx.3.3 eV associated with the charge transfer states. The second stage of reaction: starting after the depletion of all the Si surface states: falls in a coverage range between approx.0.3 and approx.1 monolayer, in which the formation of a metallic layer with a coverage-dependent loss feature at about 2 eV is observed. At still higher coverages, multiple surface and bulk plasmon excitations and their combinations are dominant. In the overall scattering processes most of the parallel momentum (approx.3 A -1 ) is transferred to the sample during the elastic backscattering from the surface, and all the losses are essentially attributed to the forward inelastic scattering before and/or after the elastic process takes place near the metal/Si interface

  8. A brief history of residual alkali metal destruction development in the UK

    International Nuclear Information System (INIS)

    Fletcher, Brian

    2014-01-01

    The reactors at Dounreay are being decommissioned and there is a need to remove all the residual alkali metal before they can be dismantled. When the Prototype Fast Reactor was shut down work was started to remove the bulk sodium and development of the Water Vapour Nitrogen (WVN) process for the destruction of the residual alkali metal commenced. This development has been ongoing to the present day. Trials began with small amounts of sodium and NaK before moving to larger scale experiments. The development raised a number of issues. As knowledge was built up, the development was expanded to deal with NaK pools in the DFR. Differences in the behaviour of NaK and sodium led to various different processes being developed. This paper presents a brief history of the alkali metal destruction process development within the UK and highlights some of the lessons learnt for future application during reactor decommissioning (authors)

  9. Enhancing Skin Permeation of Biphenylacetic Acid (BPA) Using Salt Formation with Organic and Alkali Metal Bases.

    Science.gov (United States)

    Pawar, Vijay; Naik, Prashant; Giridhar, Rajani; Yadav, Mange Ram

    2015-01-01

    In the present study, a series of organic and alkali metal salts of biphenylacetic acid (BPA) have been prepared and evaluated in vitro for percutaneous drug delivery. The physicochemical properties of BPA salts were determined using solubility measurements, DSC, and IR. The DSC thermogram and FTIR spectra confirmed the salt formation with organic and alkali metal bases. Among the series, salts with organic amines (ethanolamine, diethanolamine, triethanolamine, and diethylamine) had lowered melting points while the alkali metal salt (sodium) had a higher melting point than BPA. The in vitro study showed that salt formation improves the physicochemical properties of BPA, leading to improved permeability through the skin. Amongst all the prepared salts, ethanolamine salt (1b) showed 7.2- and 5.4-fold higher skin permeation than the parent drug at pH 7.4 and 5.0, respectively, using rat skin.

  10. Evaluation of complexing agents and column temperature in ion chromatographic separation of alkali metals, alkaline earth metals and transition metals ion

    International Nuclear Information System (INIS)

    Kelkar, Anoop; Pandey, Ashish; Name, Anil B.; Das, D.K.; Behere, P.G.; Mohd Afzal

    2015-01-01

    The aim of ion chromatography method development is the resolution of all metal ions of interests. Resolution can be improved by changing the selectivity. Selectivity in chromatography can be altered by changes in mobile phase (eg eluent type, eluent strength) or through changes in stationary phase. Temperature has been used in altering the selectivity of particularly in reversed phase liquid chromatography and ion exchange chromatography. Present paper describe the retention behaviour of alkali metals, alkaline earth metals and transition metal ions on a silica based carboxylate function group containing analyte column. Alkali metals, alkaline earth metals and transition metal ions were detected by ion conductivity and UV-VIS detectors respectively

  11. Influence of alkali metal hydroxides on corrosion of Zr-based alloys

    International Nuclear Information System (INIS)

    Jeong, Y.H.; Ruhmann, H.; Garzarolli, F.

    1997-01-01

    In this study the influence of group-1 alkali hydroxides on different zirconium based alloys has been evaluated. The experiments have been carried out in small stainless steel autoclaves at 350 deg. C in pressurized 17 MPa water, with in low (0.32 mmol), medium (4.3 mmol) and high (31.5 mmol) equimolar concentrations of Li-, Na-, K-, Rb- and Cs-Hydroxides. Two types of alloys have been investigated: Zr-Sn-(Transition metal) and Zr-Sn-Nb-(Transition metal). The corrosion behaviour was evaluated from weight gain measurements. From the experiments the cation could be identified as the responsible species for zirconium alloy corrosion in alkalized water. The radius of the cation governs the corrosion behaviour in the pre accelerated region of zircaloy corrosion. Incorporating of alkali cations into the zirconium oxide lattice is probably the mechanism which allows the corrosion enhancement for Li and Na and the significantly lower effect for the other bases. Nb containing alloys show lower corrosion resistance than alloys from the Zr-Sn-TRM system in all alkali solutions. Both types of alloys corrode significantly more in LiOH and NaOH than in the other alkali environments. Lowest corrosive aggressiveness has been found for CsOH followed by KOH. Concluding from the corrosion behaviour in the different alkali environments and taking into account the tendency to promote accelerate corrosion, CsOH and KOH are possible alternate alkalis for PWR application. (author). 17 refs, 15 figs, 5 tabs

  12. Influence of alkali metal hydroxides on corrosion of Zr-base alloys

    International Nuclear Information System (INIS)

    Jeong, Yong Hwan

    1996-01-01

    The influence of group-1 alkali hydroxides on different Zr-based alloys have been carried out in static autoclaves at 350 deg C in pressurized water, conditioned in low(0.32 mmol), medium(4.3 mmol) and high(31.5 mmol) equimolar concentration of Li-, Na-, K-, Rb- and Cs-hydroxide. Two types of alloys have been investigated: Zr-Sn-(TRM, Transition metal) and Zr-Sn-Nb-(TRM, Transition metal). From the experiments the cation could be identified as the responsible species for corrosion of Zr alloy in alkalized water. The radius of the cation governs the accelerated corrosion in the pre-transition region of Zr alloy. Incorporation of alkali cation into the zirconium oxide lattice is probably the mechanism which allows the corrosion enhancement for Li and Na and the significant lower effect for the other bases. Nb containing alloys showed lower corrosion resistance than Zr-Sn-TRM alloys in all alkali solutions. Both types of alloys were corroded significantly more in LiOH and NaOH than in the other alkali environments. Lowest corrosive aggressiveness has been found for CsOH followed by KOH. Concluding from the corrosion behavior in the different alkali environments and taking into account the tendency to accelerate the corrosion of Zr alloys, CsOH and KOH are possible alternate alkali for PWR (Pressurized Water Reactor) application. (author)

  13. Structural Diversity in Alkali Metal and Alkali Metal Magnesiate Chemistry of the Bulky 2,6-Diisopropyl-N-(trimethylsilyl)anilino Ligand.

    Science.gov (United States)

    Fuentes, M Ángeles; Zabala, Andoni; Kennedy, Alan R; Mulvey, Robert E

    2016-10-10

    Bulky amido ligands are precious in s-block chemistry, since they can implant complementary strong basic and weak nucleophilic properties within compounds. Recent work has shown the pivotal importance of the base structure with enhancement of basicity and extraordinary regioselectivities possible for cyclic alkali metal magnesiates containing mixed n-butyl/amido ligand sets. This work advances alkali metal and alkali metal magnesiate chemistry of the bulky arylsilyl amido ligand [N(SiMe 3 )(Dipp)] - (Dipp=2,6-iPr 2 -C 6 H 3 ). Infinite chain structures of the parent sodium and potassium amides are disclosed, adding to the few known crystallographically characterised unsolvated s-block metal amides. Solvation by N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDETA) or N,N,N',N'-tetramethylethylenediamine (TMEDA) gives molecular variants of the lithium and sodium amides; whereas for potassium, PMDETA gives a molecular structure, TMEDA affords a novel, hemi-solvated infinite chain. Crystal structures of the first magnesiate examples of this amide in [MMg{N(SiMe 3 )(Dipp)} 2 (μ-nBu)] ∞ (M=Na or K) are also revealed, though these breakdown to their homometallic components in donor solvents as revealed through NMR and DOSY studies. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  14. Alkali metal ion templated transition metal formate framework materials: synthesis, crystal structures, ion migration, and magnetism.

    Science.gov (United States)

    Eikeland, Espen; Lock, Nina; Filsø, Mette; Stingaciu, Marian; Shen, Yanbin; Overgaard, Jacob; Iversen, Bo Brummerstedt

    2014-10-06

    Four transition metal formate coordination polymers with anionic frameworks, namely, Na[Mn(HCOO)3], K[Mn(HCOO)3], Na2[Cu3(HCOO)8], and K2[Cu5(HCOO)12], were synthesized using a mild solution chemistry approach. Multitemperature single-crystal (100-300 K) and powder X-ray diffraction studies of the compounds reveal structures of large diversity ranging from cubic chiral Na-Mn formate to triclinic Na-Cu formate. The structural variety is caused by the nature of the transition metals, the alkali metal ion templation, and the versatility of the formate group, which offers metal-metal coordination through three different O-C-O bridging modes (syn-syn, syn-anti, anti-anti) in addition to metal-metal bridging via a single oxygen atom. The two manganese(II) compounds contain mononuclear, octahedrally coordinated moieties, but the three-dimensional connectivity between the manganese octahedra is very different in the two structures. The two copper frameworks, in contrast, consist of binuclear and mononuclear moieties (Na-Cu formate) and trinuclear and mononuclear moieties (K-Cu formate), respectively. Procrystal electron density analysis of the compounds indicates one-dimensional K(+)-ion conductivity in K-Mn and K-Cu, and the nature of the proposed potassium ion migration is compared with results from similar analysis on known Na(+) and K(+) ion conductors. K-Mn and Na-Mn were tested as cathode materials, but this resulted in poor reversibility due to low conductivity or structural collapse. The magnetic properties of the compounds were studied by vibrating sample magnetometric measurements, and their thermal stabilities were determined by thermogravimetric analysis and differential thermal analysis. Despite structural differences, the metal formates that contain the same transition metal have similar magnetic properties and thermal decomposition pathways, that is, the nature of the transition metal controls the compound properties.

  15. In Situ Measurement of Alkali Metals in an MSW Incinerator Using a Spontaneous Emission Spectrum

    Directory of Open Access Journals (Sweden)

    Weijie Yan

    2017-03-01

    Full Text Available This paper presents experimental investigations of the in situ diagnosis of the alkali metals in the municipal solid waste (MSW flame of an industrial grade incinerator using flame emission spectroscopy. The spectral radiation intensities of the MSW flame were obtained using a spectrometer. A linear polynomial fitting method is proposed to uncouple the continuous spectrum and the characteristic line. Based on spectra processing and a non-gray emissivity model, the flame temperature, emissivity, and intensities of the emission of alkali metals were calculated by means of measuring the spectral radiation intensities of the MSW flame. Experimental results indicate that the MSW flame contains alkali metals, including Na, K, and even Rb, and it demonstrates non-gray characteristics in a wavelength range from 500 nm to 900 nm. Peak intensities of the emission of the alkali metals were found to increase when the primary air was high, and the measured temperature varied in the same way as the primary air. The temperature and peak intensities of the lines of emission of the alkali metals may be used to adjust the primary airflow and to manage the feeding of the MSW to control the alkali metals in the MSW flame. It was found that the peak intensity of the K emission line had a linear relationship with the peak intensity of the Na emission line; this correlation may be attributed to their similar physicochemical characteristics in the MSW. The variation trend of the emissivity of the MSW flame and the oxygen content in the flue gas were almost opposite because the increased oxygen content suppressed soot formation and decreased soot emissivity. These results prove that the flame emission spectroscopy technique is feasible for monitoring combustion in the MSW incinerator in situ.

  16. Thermochemistry of uranium(VI), arsenic, and alkali metal triple oxides

    International Nuclear Information System (INIS)

    Karyakin, N.V.; Chernorukov, G.N.

    1994-01-01

    The standard enthalpies of reactions of stoichiometric mixtures of potassium dyhydrogen orthoarsenate, uranium(VI) oxide, alkali metal nitrates, and of mixtures of triple oxides with the general formula M I AsUO 6 (M I =Li, Na, K, Rb, and Cs) and potassium nitrate with aqueous solution of hydrofluoric acid were determined an an adiabatic calorimeter at 298.15 K. The standard enthalpies of formation of uranium(VI), arsenic, and alkali metal triple oxides at 298.15 K were calculated form the data obtained. 8 refs., 1 tab

  17. Selective detection of polarisation components of a coherent population trapping signal in hot alkali metal atoms

    Science.gov (United States)

    Barantsev, K. A.; Popov, E. N.; Litvinov, A. N.

    2017-09-01

    A mathematical model of the interaction of bichromatic laser radiation with alkali metal atoms in an optically dense gas cell at above room temperature is constructed. Within the framework of the model, complete hyperfine and Zeeman structures of alkali metal atom levels are considered, which allows the propagation of radiation polarisation along the cell and the effect of a constant magnetic field to be correctly taken into account. It is found that the selective detection of polarisation radiation components carries additional information in comparison with a signal of total intensity.

  18. Ion conducting polymers and polymer blends for alkali metal ion batteries

    Science.gov (United States)

    DeSimone, Joseph M.; Pandya, Ashish; Wong, Dominica; Vitale, Alessandra

    2017-08-29

    Electrolyte compositions for batteries such as lithium ion and lithium air batteries are described. In some embodiments the compositions are liquid compositions comprising (a) a homogeneous solvent system, said solvent system comprising a perfluropolyether (PFPE) and polyethylene oxide (PEO); and (b) an alkali metal salt dissolved in said solvent system. In other embodiments the compositions are solid electrolyte compositions comprising: (a) a solid polymer, said polymer comprising a crosslinked product of a crosslinkable perfluropolyether (PFPE) and a crosslinkable polyethylene oxide (PEO); and (b) an alkali metal ion salt dissolved in said polymer. Batteries containing such compositions as electrolytes are also described.

  19. Adsorption of alkali, alkaline-earth, and 3d transition metal atoms on silicene

    Science.gov (United States)

    Sahin, H.; Peeters, F. M.

    2013-02-01

    The adsorption characteristics of alkali, alkaline-earth, and transition metal adatoms on silicene, a graphene-like monolayer structure of silicon are analyzed by means of first-principles calculations. In contrast to graphene, interaction between the metal atoms and the silicene surface is quite strong due to its highly reactive buckled hexagonal structure. In addition to structural properties, we also calculate the electronic band dispersion, net magnetic moment, charge transfer, work function, and dipole moment of the metal adsorbed silicene sheets. Alkali metals, Li, Na, and K, adsorb to hollow sites without any lattice distortion. As a consequence of the significant charge transfer from alkalis to silicene, metalization of silicene takes place. Trends directly related to atomic size, adsorption height, work function, and dipole moment of the silicene/alkali adatom system are also revealed. We found that the adsorption of alkaline-earth metals on silicene is entirely different from their adsorption on graphene. The adsorption of Be, Mg, and Ca turns silicene into a narrow gap semiconductor. Adsorption characteristics of eight transition metals Ti, V, Cr, Mn, Fe, Co, Mo, and W are also investigated. As a result of their partially occupied d orbital, transition metals show diverse structural, electronic, and magnetic properties. Upon the adsorption of transition metals, depending on the adatom type and atomic radius, the system can exhibit metal, half-metal, and semiconducting behavior. For all metal adsorbates, the direction of the charge transfer is from adsorbate to silicene, because of its high surface reactivity. Our results indicate that the reactive crystal structure of silicene provides a rich playground for functionalization at nanoscale.

  20. Vapor Species Over Te Precious Metal Minerals

    Science.gov (United States)

    Helle, Sonia; Wildeman, Thomas; Yarar, Baki

    1987-01-01

    This paper reports on two developments of interest to extractive metallurgists: how the knowledge of the vapors over tellurium minerals can be used to develop better processing methods and how graphite furnace atomic absorption, used at moderate temperatures, can be used to characterize the vapors over ore minerals. Elemental tellurium, Ag2Te, and AuTe2 were studied from 250°C through 1050°C. The vapors over these solids were analyzed in-situ by placing the solids directly into the graphite furnace of an atomic absorption spectrophotometer and adjusting the temperature accordingly. Atomic Ag, Au, and Te and molecular Te were analyzed in the vapor above the solids. Using absorbance versus temperature data, Clausius-Clapeyron plots were made to determine how the solids were changing.

  1. Density functional theory based screening of ternary alkali-transition metal borohydrides: A computational material design project

    DEFF Research Database (Denmark)

    Hummelshøj, Jens Strabo; Landis, David; Voss, Johannes

    2009-01-01

    We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K (M1); and 1 alkali, alkaline earth or 3d/4d transition...

  2. Behavior of Alkali Metals and Ash in a Low-Temperature Circulating Fluidized Bed (LTCFB) Gasifier

    DEFF Research Database (Denmark)

    Narayan, Vikas; Jensen, Peter Arendt; Henriksen, Ulrik Birk

    2016-01-01

    , the low reactor temperature ensures that high-alkali biomass fuels canbe used without risk of bed defluidization. This paper presents the first investigation of the fate of alkali metals and ash in lowtemperaturegasifiers. Measurements on bed material and product gas dust samples were made on a 100 k......W and a 6 MW LTCFBgasifier. Of the total fuel ash entering the system, the largest fraction (40−50%) was retained in the secondary cyclone bottoms,while a lower amount (8−10%) was released as dust in the exit gas. Most of the alkali and alkaline earth metals were retained inthe solid ash, along with Si...... by the particle size and the cut size ofthe primary and secondary cyclones. A model accounting for the ash collection by the plant cyclones was shown to predict theproduct gas ash particle release reasonably well....

  3. Thermodynamic and kinetic analysis of solid-phase interaction of alkali metal carbonates with arsenic pentoxide

    International Nuclear Information System (INIS)

    Pashinkin, A.S.; Buketov, E.A.; Isabaeva, S.M.; Kasenov, B.K.

    1985-01-01

    The thermodynamic analysis of solid-phase reactions of alkali metal carbonates with arsenic pentoxide showing the possibility of formation of all arsenates at a higher than the room temperature is performed. Energetically most advantageous is formation of meta-arsenates. It is shown that temperature increase favours the reaction process. By Gibbs standard energy decrease the reactions form the Li>Na>K>Rb>Cs series. On the base of calculation data linear dependence of Gibbs standard energy in reactions on the atomic number of alkali metalis established. By the continuous weighing method the kinetics of interaction of alkali metal carbonates with arsenic pentoxide under isothermal conditions in the 450-500 deg C range is studied. Studies is the dependence of apparent energy of interaction of carbonates wih As 2 0 5 an atomic parameters of al

  4. Fractionation of families of major, minor, and trace metals across the melt-vapor interface in volcanic exhalations

    Science.gov (United States)

    Hinkley, T.K.; Le Cloarec, M.-F.; Lambert, G.

    1994-01-01

    Chemical families of metals fractionate systematically as they pass from a silicate melt across the interface with the vapor phase and on into a cooled volcanic plume. We measured three groups of metals in a small suite of samples collected on filters from the plumes of Kilauea (Hawaii, USA), Etna (Sicily), and Merapi (Java) volcanoes. These were the major, minor, and trace metals of the alkali and alkaline earth families (K, Rb, Cs, Ca, Sr, Ba), a group of ordinarily rare metals (Cd, Cu, In, Pb, Tl) that are related by their chalcophile affinities, and the radon daughter nuclides 210Po, 210Bi, and 210Pb. The measurements show the range and some details of systematic melt-vapor fractionation within and between these groups of metals. In the plumes of all three volcanoes, the alkali metals are much more abundant than the alkaline earth metals. In the Kilauea plume, the alkali metals are at least six times more abundant than the alkaline earth metals, relative to abundances in the melt; at Etna, the factor is at least 300. Fractionations within each family are, commonly, also distinctive; in the Kilauea plume, in addition to the whole alkaline earth family being depleted, the heaviest metals of the family (Sr, Ba) are progressively more depleted than the light metal Ca. In plumes of fumaroles at Merapi, K/Cs ratios were approximately three orders of magnitude smaller than found in other earth materials. This may represent the largest observed enrichment of the "light ion lithophile" (LIL) metals. Changes in metal ratios were seen through the time of eruption in the plumes of Kilauea and Etna. This may reflect degree of degassing of volatiles, with which metals complex, from the magma bodies. At Kilauea, the changes in fractionation were seen over about three years; fractionation within the alkaline earth family increased, and that between the two families decreased, over that time. All of the ordinarily rare chalcophile metals measured are extremely abundant in

  5. Oxygen production by molten alkali metal salts using multiple absorption-desorption cycles

    Science.gov (United States)

    Cassano, A.A.

    1985-07-02

    A continuous chemical air separation is performed wherein oxygen is recovered with a molten alkali metal salt oxygen acceptor in a series of absorption zones which are connected to a plurality of desorption zones operated in separate parallel cycles with the absorption zones. A greater recovery of high pressure oxygen is achieved at reduced power requirements and capital costs. 3 figs.

  6. Stabilization of polyamides IV. Thermooxidation of hexano-6-lactam in the presence of alkali metal salts

    Czech Academy of Sciences Publication Activity Database

    Lánská, Božena; Matisová-Rychlá, L.; Rychlý, J.

    2005-01-01

    Roč. 87, č. 2 (2005), s. 361-373 ISSN 0141-3910 R&D Projects: GA AV ČR(CZ) KSK4050111 Institutional research plan: CEZ:AV0Z40500505 Keywords : oxidation of N-alkylamides * alkali metal salts * chemiluminescence of reactions Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.749, year: 2005

  7. Use of polysulfides of alkali and alkaline-earth metals to obtain highly dispersed sulfur

    International Nuclear Information System (INIS)

    Massalimov, I.A.; Vikhareva, I.N.; Kireeva, M.S.

    2008-01-01

    Possibilities of obtaining polysulfides of alkali and alkaline earth metals (M is Na, K, Ca, Sr, Ba) in aqueous solutions were considered. The composition of the polysulfides and their concentration in solutions were found. The efficiencies of application of highly dispersed sulfur, produced from calcium polysulfide, and colloid sulfur as a fungicide were compared [ru

  8. Cations in a Molecular Funnel: Vibrational Spectroscopy of Isolated Cyclodextrin Complexes with Alkali Metals

    NARCIS (Netherlands)

    Gámez, F.; Hurtado, P.; Hortal, A.R.; Martínez-Haya, B.; Berden, G.; Oomens, J.

    2013-01-01

    The benchmark inclusion complexes formed by -cyclodextrin (CD) with alkali-metal cations are investigated under isolated conditions in the gas phase. The relative CD-M+ (M=Li+, Na+, K+, Cs+) binding affinities and the structure of the complexes are determined from a combination of mass spectrometry,

  9. Oxygen production by molten alkali metal salts using multiple absorption-desorption cycles

    Science.gov (United States)

    Cassano, Anthony A.

    1985-01-01

    A continuous chemical air separation is performed wherein oxygen is recovered with a molten alkali metal salt oxygen acceptor in a series of absorption zones which are connected to a plurality of desorption zones operated in separate parallel cycles with the absorption zones. A greater recovery of high pressure oxygen is achieved at reduced power requirements and capital costs.

  10. Alkali metal ion binding to glutamine and glutamine derivatives investigated by infrared action spectroscopy and theory

    NARCIS (Netherlands)

    Bush, M. F.; Oomens, J.; Saykally, R. J.; Williams, E. R.

    2008-01-01

    The gas-phase structures of alkali-metal cationized glutamine are investigated by using both infrared multiple photon dissociation (TRMPD) action spectroscopy, utilizing light generated by a free electron laser, and theory. The IRMPD spectra contain many similarities that are most consistent with

  11. Neutron scattering investigation of layer-bending modes in alkali-metal--graphite intercalation compounds

    International Nuclear Information System (INIS)

    Zabel, H.; Kamitakahara, W.A.; Nicklow, R.M.

    1982-01-01

    Phonon dispersion curves for low-frequency transverse modes propagating in the basal plane have been measured in the alkali-metal--graphite intercalation compounds KC 8 , CsC 8 , KC 24 , and RbC 24 by means of neutron spectroscopy. The acoustic branches show an almost quadratic dispersion relation at small q, characteristic of strongly layered materials. The optical branches of stage-1 compounds can be classified as either graphitelike branches showing dispersion, or as almost dispersionless alkali-metal-like modes. Macroscopic shear constants C 44 and layer-bending moduli have been obtained for the intercalation compounds by analyzing the data in terms of a simple semicontinuum model. In stage-2 compounds, a dramatic softening of the shear constant by about a factor of 8 compared with pure graphite has been observed. Low-temperature results on KC 24 indicate the opening of a frequency gap near the alkali-metal Brillouin-zone boundary, possibly due to the formation of the alkali-metal superstructure

  12. Thermochemistry of the complex oxides of uranium, vanadium, and alkali metals

    International Nuclear Information System (INIS)

    Karyakin, N.V.; Chernorukov, N.G.; Suleimanov, E.V.; Kharyushina, E.A.

    1992-01-01

    The standard enthalpies of the formation at T 298.15 K of complex oxides of uranium(VI), vanadium(V) and alkali metals with the general formula M 1 VUO 6 where M 1 = Na, K, Rb, and Cs, were calculated from the results of calorimetric experiments and from published data. 8 refs., 1 tab

  13. Alkali metal complexes of the Dipeptides PheAla and AlaPhe : IRMPD spectroscopy

    NARCIS (Netherlands)

    Polfer, N. C.; Oomens, J.; Dunbar, R. C.

    2008-01-01

    Complexes of PheAla and AlaPhe with alkali metal ions Na+ and K+ are generated by electroscopy ionization, isolated in the Fourier-transform ion cyclotron resonance (FT-ICR) ion trapping mass spectrometer, and investigated by infrared multiple-photon dissociation (IRMPD) using light from the FELIX

  14. Determination of membrane hydration numbers of alkali metal ions by insertion in a conducting polymer

    DEFF Research Database (Denmark)

    Skaarup, Steen; Junaid Mohamed Jafeen, Mohamed; Careem, M.A.

    2010-01-01

    not necessarily define the same hydration shell. This work presents a systematic study of one special variant of the hydration numbers of the 5 alkali metal ions, using the electrochemical insertion of the ions in a conducting polymer (polypyrrole containing the large immobile anion DBS-). The technique...

  15. Theoretical evaluation on selective adsorption characteristics of alkali metal-based sorbents for gaseous oxidized mercury.

    Science.gov (United States)

    Tang, Hongjian; Duan, Yufeng; Zhu, Chun; Cai, Tianyi; Li, Chunfeng; Cai, Liang

    2017-10-01

    Alkali metal-based sorbents are potential for oxidized mercury (Hg 2+ ) selective adsorption but show hardly effect to elemental mercury (Hg 0 ) in flue gas. Density functional theory (DFT) was employed to investigate the Hg 0 and HgCl 2 adsorption mechanism over alkali metal-based sorbents, including calcium oxide (CaO), magnesium oxide (MgO), potassium chloride (KCl) and sodium chloride (NaCl). Hg 0 was found to weakly interact with CaO (001), MgO (001), KCl (001) and NaCl (001) surfaces while HgCl 2 was effectively adsorbed on top-O and top-Cl sites. Charge transfer and bond population were calculated to discuss the covalency and ionicity of HgCl 2 bonding with the adsorption sites. The partial density of states (PDOS) analysis manifests that HgCl 2 strongly interacts with surface sites through the orbital hybridizations between Hg and top O or Cl. Frontier molecular orbital (FMO) energy and Mulliken electronegativity are introduced as the quantitative criteria to evaluate the reactivity of mercury species and alkali metal-based sorbents. HgCl 2 is identified as a Lewis acid and more reactive than Hg 0 . The Lewis basicity of the four alkali metal-based sorbents is predicted as the increasing order: NaCl < MgO < KCl < CaO, in consistence with the trend of HgCl 2 adsorption energies. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Antiproton and proton collisions with the alkali-metal atoms Li, Na, and K

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Saenz, Alejandro

    2008-01-01

    Single-electron ionization and excitation cross sections as well as cross sections for excitation into the first excited p state of the alkali-metal atoms Li(2s), Na(3s), and K(4s) colliding with antiprotons and protons were calculated using a time-dependent channel-coupling approach. For antipro...

  17. Long-range interactions between excited helium and alkali-metal atoms

    KAUST Repository

    Zhang, J.-Y.

    2012-12-03

    The dispersion coefficients for the long-range interaction of the first four excited states of He, i.e., He(2 1,3S) and He(2 1,3P), with the low-lying states of the alkali-metal atoms Li, Na, K, and Rb are calculated by summing over the reduced matrix elements of the multipole transition operators. For the interaction between He and Li the uncertainty of the calculations is 0.1–0.5%. For interactions with other alkali-metal atoms the uncertainty is 1–3% in the coefficient C5, 1–5% in the coefficient C6, and 1–10% in the coefficients C8 and C10. The dispersion coefficients Cn for the interaction of He(2 1,3S) and He(2 1,3P) with the ground-state alkali-metal atoms and for the interaction of He(2 1,3S) with the alkali-metal atoms in their first 2P states are presented in this Brief Report. The coefficients for other pairs of atomic states are listed in the Supplemental Material.

  18. Alkali Metal Cation Affinities of Anionic Main Group-Element Hydrides Across the Periodic Table

    NARCIS (Netherlands)

    Boughlala, Zakaria; Fonseca Guerra, Célia; Bickelhaupt, F. Matthias

    2017-01-01

    We have carried out an extensive exploration of gas-phase alkali metal cation affinities (AMCA) of archetypal anionic bases across the periodic system using relativistic density functional theory at ZORA-BP86/QZ4P//ZORA-BP86/TZ2P. AMCA values of all bases were computed for the lithium, sodium,

  19. Van der Waals coefficients for alkali metal clusters and their size

    Indian Academy of Sciences (India)

    In this paper we employ the hydrodynamic formulation of time-dependent density functional theory to obtain the van der Waals coefficients 6 and 8 of alkali metal clusters of various sizes including very large clusters. Such calculations become computationally very demanding in the orbital-based Kohn-Sham formalism, ...

  20. Ultrafast electron dynamics at alkali/ice structures adsorbed on a metal surface

    International Nuclear Information System (INIS)

    Meyer, Michael

    2011-01-01

    The goal of this work is to study the interaction between excess electrons in water ice structures adsorbed on metal surfaces and other charged or neutral species, like alkali ions, or chemically reactive molecules, like chlorofluorocarbons (CFC), respectively. The excess electrons in the ice can interact with the ions directly or indirectly via the hydrogen bonded water molecules. In both cases the presence of the alkali influences the population, localization, and lifetime of electronic states of excess electrons in the ice adlayer. These properties are of great relevance when considering the highly reactive character of the excess electrons, which can mediate chemical reactions by dissociative electron attachment (DEA). The influence of alkali adsorption on electron solvation and transfer dynamics in ice structures is investigated for two types of adsorption configurations using femtosecond time-resolved two-photon photoelectron spectroscopy. In the first system alkali atoms are coadsorbed on top of a wetting amorphous ice film adsorbed on Cu(111). At temperatures between 60 and 100 K alkali adsorption leads to the formation of positively charged alkali ions at the ice/vacuum interface. The interaction between the alkali ions at the surface and the dipole moments of the surrounding water molecules results in a reorientation of the water molecules. As a consequence new electron trapping sites, i.e. at local potential minima, are formed. Photoinjection of excess electrons into these alkali-ion covered amorphous ice layers, results in the trapping of a solvated electron at an alkali-ion/water complex. In contrast to solvation in pure amorphous ice films, where the electrons are located in the bulk of the ice layer, solvated electrons at alkali-ion/water complexes are located at the ice/vacuum interface. They exhibit lifetimes of several picoseconds and show a fast energetic stabilization. With ongoing solvation, i.e. pump-probe time delay, the electron transfer is

  1. Liquid metal cooled reactor-alkali metal thermoelectric space power system concept for multimegawatt applications

    International Nuclear Information System (INIS)

    Schmidt, J.E.; Chi, J.W.H.; Morgan, R.E.; Hanson, J.P.; Hunt, T.K.

    1987-01-01

    This paper presents a study of a lithium cooled reactor Alkali Metal Thermoelectric (AMTEC) power system for multimegawatt space power applications. AMTEC is a thermally regenerative electrochemical device, a static energy converter that permits high power conversion efficiencies at moderate operating temperatures. Scoping designs and parametric analyses were carried out to establish the waste heat rejection temperature that yields the minimum system mass. The advantages of this power source concept are presented. They include a system that has no moving parts and total power system mass that is substantially less than those of systems using other static energy converters. The key technical issues are identified and the technology development requirements are discussed. 8 references

  2. A simple alkali-metal and noble gas ion source for SIMS equipments with mass separation of the primary ions

    International Nuclear Information System (INIS)

    Duesterhoeft, H.; Pippig, R.

    1986-01-01

    An alkali-metal ion source working without a store of alkali-metals is described. The alkali-metal ions are produced by evaporation of alkali salts and ionization in a low-voltage arc discharge stabilized with a noble gas plasma or in the case of small alkali-metal ion currents on the base of the well known thermic ionization at a hot tungsten wire. The source is very simple in construction and produces a stable ion current of 0.3 μA for more than 100 h. It is possible to change the ion species in a short time. This source is applicable to all SIMS equipments using mass separation for primary ions. (author)

  3. Thermochemistry of the alkali metal and alkaline earth-actinide complex oxides

    International Nuclear Information System (INIS)

    Fuger, J.

    1985-01-01

    After a brief discussion of the various techniques used for the preparation of actinide complex oxides, the present status of the thermochemistry of these compounds is reviewed. Perovskite-related compounds are especially considered as thermodynamic data are available for compounds of several actinides and/or several alkali and alkaline earth metals. The stabilities of the complex oxides are discussed with respect to the parent binary oxides and to the aqueous ions; trends as a function of the size and the alkali or the alkaline earth cation are presented. Suggestions for synthesis of some analogous compounds with heavier actinides are also discussed. (orig./RK)

  4. Can Cyclen Bind Alkali Metal Azides? A DFT Study as a Precursor to Synthesis.

    Science.gov (United States)

    Bhakhoa, Hanusha; Rhyman, Lydia; Lee, Edmond P F; Ramasami, Ponnadurai; Dyke, John M

    2016-03-18

    Can cyclen (1,4,7,10-tetraazacyclododecane) bind alkali metal azides? This question is addressed by studying the geometric and electronic structures of the alkali metal azide-cyclen [M(cyclen)N3] complexes using density functional theory (DFT). The effects of adding a second cyclen ring to form the sandwich alkali metal azide-cyclen [M(cyclen)2N3] complexes are also investigated. N3(-) is found to bind to a M(+) (cyclen) template to give both end-on and side-on structures. In the end-on structures, the terminal nitrogen atom of the azide group (N1) bonds to the metal as well as to a hydrogen atom of the cyclen ring through a hydrogen bond in an end-on configuration to the cyclen ring. In the side-on structures, the N3 unit is bonded (in a side-on configuration to the cyclen ring) to the metal through the terminal nitrogen atom of the azide group (N1), and through the other terminal nitrogen atom (N3) of the azide group by a hydrogen bond to a hydrogen atom of the cyclen ring. For all the alkali metals, the N3-side-on structure is lowest in energy. Addition of a second cyclen unit to [M(cyclen)N3] to form the sandwich compounds [M(cyclen)2N3] causes the bond strength between the metal and the N3 unit to decrease. It is hoped that this computational study will be a precursor to the synthesis and experimental study of these new macrocyclic compounds; structural parameters and infrared spectra were computed, which will assist future experimental work. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Synthesis and Characterization of Novel Ternary and Quaternary Alkali Metal Thiophosphates

    KAUST Repository

    Alahmary, Fatimah S.

    2014-05-01

    The ongoing development of nonlinear optical (NLO) crystals such as coherent mid-IR sources focuses on various classes of materials such as ternary and quaternary metal chalcophosphates. In case of thiophosphates, the connection between PS4-tetrahedral building blocks and metals gives rise to a broad structural variety where approximately one third of all known ternary (A/P/S) and quaternary (A/M/P/S) (A = alkali metal, M = metal) structures are acentric and potential nonlinear optical materials. The molten alkali metal polychalcophosphate fluxes are a well-established method for the synthesis of new ternary and quaternary thiophosphate and selenophosphate compounds. It has been a wide field of study and investigation through the last two decades. Here, the flux method is used for the synthesis of new quaternary phases containing Rb, Ag, P and S. Four new alkali metal thiophosphates, Rb4P2S10, RbAg5(PS4), Rb2AgPS4 and Rb3Ag9(PS4)4, have been synthesized successfully from high purity elements and binary starting materials. The new compounds were characterized by single crystal and powder X-ray diffraction, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), ultraviolet-visible (UV-VIS), Raman spectroscopy, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). These compounds show interesting structural variety and physical properties. The crystal structures feature 3D anionic framework built up of PS4 tetrahedral units and charge balanced by Ag and alkali metal cations. All prepared compounds are semiconductors with band gap between 2.3 eV to 2.6 eV and most of them are thermally stable up to 600ºC.

  6. Diode Laser Pumped Alkali Vapor Lasers with Exciplex-Assisted Absorption

    Science.gov (United States)

    2013-05-14

    gas pressure in the discharge cell was measured by a capacitance manometer (MKS Baratron). Tunable radiation with spectral bandwidth of 0 .3 cm·1...of low pressure Rb and Cs vapors from ground states and by low pressure Ar* and Kr* from metastable states. Exposed and developed PTR glass with an...provides efficient absorption of radiation by low pressure Rb and Cs vapors from ground states and by low pressure Ar* and Kr* from metastable states. The

  7. Structural and Magnetic Diversity in Alkali-Metal Manganate Chemistry: Evaluating Donor and Alkali-Metal Effects in Co-complexation Processes.

    Science.gov (United States)

    Uzelac, Marina; Borilovic, Ivana; Amores, Marco; Cadenbach, Thomas; Kennedy, Alan R; Aromí, Guillem; Hevia, Eva

    2016-03-24

    By exploring co-complexation reactions between the manganese alkyl Mn(CH2SiMe3)2 and the heavier alkali-metal alkyls M(CH2SiMe3) (M=Na, K) in a benzene/hexane solvent mixture and in some cases adding Lewis donors (bidentate TMEDA, 1,4-dioxane, and 1,4-diazabicyclo[2,2,2] octane (DABCO)) has produced a new family of alkali-metal tris(alkyl) manganates. The influences that the alkali metal and the donor solvent impose on the structures and magnetic properties of these ates have been assessed by a combination of X-ray, SQUID magnetization measurements, and EPR spectroscopy. These studies uncover a diverse structural chemistry ranging from discrete monomers [(TMEDA)2 MMn(CH2SiMe3)3] (M=Na, 3; M=K, 4) to dimers [{KMn(CH2SiMe3)3 ⋅C6 H6}2] (2) and [{NaMn(CH2SiMe3)3}2 (dioxane)7] (5); and to more complex supramolecular networks [{NaMn(CH2SiMe3)3}∞] (1) and [{Na2Mn2 (CH2SiMe3)6 (DABCO)2}∞] (7)). Interestingly, the identity of the alkali metal exerts a significant effect in the reactions of 1 and 2 with 1,4-dioxane, as 1 produces coordination adduct 5, while 2 forms heteroleptic [{(dioxane)6K2Mn2 (CH2SiMe3)4(O(CH2)2OCH=CH2)2}∞] (6) containing two alkoxide-vinyl anions resulting from α-metalation and ring opening of dioxane. Compounds 6 and 7, containing two spin carriers, exhibit antiferromagnetic coupling of their S=5/2 moments with varying intensity depending on the nature of the exchange pathways. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. High-pressure phase transition of alkali metal-transition metal deuteride Li2PdD2

    Science.gov (United States)

    Yao, Yansun; Stavrou, Elissaios; Goncharov, Alexander F.; Majumdar, Arnab; Wang, Hui; Prakapenka, Vitali B.; Epshteyn, Albert; Purdy, Andrew P.

    2017-06-01

    A combined theoretical and experimental study of lithium palladium deuteride (Li2PdD2) subjected to pressures up to 50 GPa reveals one structural phase transition near 10 GPa, detected by synchrotron powder x-ray diffraction, and metadynamics simulations. The ambient-pressure tetragonal phase of Li2PdD2 transforms into a monoclinic C2/m phase that is distinct from all known structures of alkali metal-transition metal hydrides/deuterides. The structure of the high-pressure phase was characterized using ab initio computational techniques and from refinement of the powder x-ray diffraction data. In the high-pressure phase, the PdD2 complexes lose molecular integrity and are fused to extended [PdD2]∞ chains. The discovered phase transition and new structure are relevant to the possible hydrogen storage application of Li2PdD2 and alkali metal-transition metal hydrides in general.

  9. Electrodeposition of alkali and alkali-earth metals on liquid lead cathodes in molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Caravaca, C.; De Cordoba, G. [CIEMAT/DE/DFN/URAA. Avda. Complutense, 22. 28040 Madrid (Spain)

    2008-07-01

    Pyrochemical processing of spent nuclear fuel leads to the dissolution as chlorides of fission products (FPs) that have to be removed in order to recycle the salt. Precipitation technique have been tested for the removal of these FPs in the LiCl-KCl, salt selected as reference, with different results. Salt decontamination from lanthanides can be easily achieved as solid precipitates of oxychlorides or single phosphates; however, for the alkaline and alkaline-earth metals this technique is not suitable. Within the EUROPART project (VI FP of the EC), a new route that consist of the electrodeposition of these FP on a liquid lead cathode (LLC) has been considered, including the Li and K constituting the electrolyte. First results obtained with Sr and Cs are presented herein. Although according to the thermodynamic potential values, the electrodeposition order on LLC is Ba, Sr, Li, K and Cs, during our experiments it was not possible to distinguish the electrochemical signals corresponding to the individual elements. (authors)

  10. Development and testing of on-line analytical instrumentation for alkali and heavy metal release in pressurised conversion processes

    Energy Technology Data Exchange (ETDEWEB)

    Hernberg, R.; Haeyrinen, V.; Oikari, R. [Tampere Univ. of Technology (Finland)

    1997-10-01

    The purpose of the project is to demonstrate in industrial conditions and further develop the continuous alkali measurement method plasma excited alkali resonance line spectroscopy (PEARLS) developed at Tampere University of Technology (TUT). The demonstration takes place in joint measuring campaigns, where two other continuous alkali measurement methods, ELIF and surface ionisation, are being simultaneously demonstrated. A modification of PEARLS will also be developed for the continuous measurement of heavy metal concentrations. A market study of continuous measuring techniques for alkali and heavy metals is further part of the project. The method will be demonstrated in two pressurised fluidised bed combustion facilities. One of these is the 10 MW PCFB of Foster Wheeler Energia Oy in Karhula. The second one is yet to be decided. The first measuring campaign is scheduled for the spring of 1997 in Karhula. In 1996 the group at TUT participated in the performance of a market study regarding continuous measuring techniques for alkali and heavy metal concentrations. A draft report was submitted to and approved by the EC. Development work on PEARLS in 1996 has centered around the construction of a calibration device for alkali measurements. The device can be used by all three measuring techniques in the project to check readings against a known alkali concentration at controlled and known conditions. In 1996 PEARLS was applied for alkali measurement at several pressurised combustion installations of laboratory and industrial pilot scale

  11. Hofmeister series and ionic effects of alkali metal ions on DNA conformation transition in normal and less polarised water solvent

    Science.gov (United States)

    Wen, Jing; Shen, Xin; Shen, Hao; Zhang, Feng-Shou

    2014-10-01

    Normal and less polarised water models are used as the solvent to investigate Hofmeister effects and alkali metal ionic effects on dodecamer d(CGCGAATTCGCG) B-DNA with atomic dynamics simulations. As normal water solvent is replaced by less polarised water, the Hofmeister series of alkali metal ions is changed from Li+ > Na+ ≃ K+ ≃ Cs+ ≃ Rb+ to Li+ > Na+ > K+ > Rb+ > Cs+. In less polarised water, DNA experiences the B→A conformational transition for the lighter alkali metal counterions (Li+, Na+ and K+). However, it keeps B form for the heavier ions (Rb+ and Cs+). We find that the underlying cause of the conformation transition for these alkali metal ions except K+ is the competition between water molecules and counterions coupling to the free oxygen atoms of the phosphate groups. For K+ ions, the 'economics' of phosphate hydration and 'spine of hydration' are both concerned with the DNA helixes changing.

  12. Investigation of the atom-atom and structural relaxation in liquid alkali metals by means of the memory function formalism

    International Nuclear Information System (INIS)

    Blagoveshchenskii, N. M.; Novikov, A. G.; Savostin, V. V.

    2011-01-01

    An attempt is made to systematize the data on the relaxation characteristics of liquid alkali metals (Li, Na, and K), which were investigated based on neutron-scattering data with the application of the two-time memory function formalism.

  13. Ionic structure of solutions of alkali metals and molten salts

    International Nuclear Information System (INIS)

    Chabrier, G.; Senatore, G.; Tosi, M.P.

    1982-02-01

    Neutron diffraction patterns from K-KCl and Rb-RbBr liquid solutions at various compositions are examined in an ionic-mixture model which neglects screening and aggregation due to the metallic electrons. The main feature of the observed diffraction patterns for wave number k above roughly 1A -1 are accounted for by the model. The approach to the metal-rich end of the phase diagram is analyzed in detail from different viewpoints in the K-KCl system. Short-range correlations of the potassium ions are described in this region by a metallic radius deduced from properties of the pure liquid metal, but a simple expanded-metal model must be supplemented by the assumption that considerable disorder is introduced in its structure by the halogen ions. Features of short-range ordering in the salt-rich region that are implied by a shoulder on the high-k side of the main peak in the diffraction pattern are also commented upon. (author)

  14. Emission spectra of alkali-metal (K,Na,Li)-He exciplexes in cold helium gas

    International Nuclear Information System (INIS)

    Enomoto, K.; Hirano, K.; Kumakura, M.; Takahashi, Y.; Yabuzaki, T.

    2004-01-01

    We have observed emission spectra of excimers and exciplexes composed of a light alkali-metal atom in the first excited state and 4 He atoms [K*He n (n=1-6), Na * He n (n=1-4), and Li * He n (n=1,2)] in cryogenic He gas (the temperature 2 K -1 . Differently from exciplexes with heavier alkali-metal atoms, the spectra for the different number of He atoms were well separated, so that their assignment could be made experimentally. Comparing with the spectra of K * He n , we found that the infrared emission spectrum of the K atom excited in liquid He was from K*He 6 . To confirm the assignment, we have also carried out ab initio calculation of adiabatic potential curves and peak positions of the emission spectra of the exciplexes

  15. Equation of state for thermodynamic properties of pure and mixtures liquid alkali metals

    International Nuclear Information System (INIS)

    Mousazadeh, M.H.; Faramarzi, E.; Maleki, Z.

    2010-01-01

    We developed an equation of state based on statistical-mechanical perturbation theory for pure and mixtures alkali metals. Thermodynamic properties were calculated by the equation of state, based on the perturbed-chain statistical associating fluid theory (PC-SAFT). The model uses two parameters for a monatomic system, segment size, σ, and segment energy, ε. In this work, we calculate the saturation and compressed liquid density, heat capacity at constant pressure and constant volume, isobaric expansion coefficient, for which accurate experimental data exist in the literatures. Results on the density of binary and ternary alkali metal alloys of Cs-K, Na-K, Na-K-Cs, at temperatures from the freezing point up to several hundred degrees above the boiling point are presented. The calculated results are in good agreement with experimental data.

  16. Emission Channeling Studies of the Lattice Site of Oversized Alkali Atoms Implanted in Metals

    CERN Multimedia

    2002-01-01

    % IS340 \\\\ \\\\ As alkali atoms have the largest atomic radius of all elements, the determination of their lattice configuration following implantation into metals forms a critical test for the various models predicting the lattice site of implanted impurity atoms. The site determination of these large atoms will especially be a crucial check for the most recent model that relates the substitutional fraction of oversized elements to their solution enthalpy. Recent exploratory $^{213}$Fr and $^{221}$Fr $\\alpha$-emission channeling experiments at ISOLDE-CERN and hyperfine interaction measurements on Fr implanted in Fe gave an indication for anomalously large substitutional fractions. To investigate further the behaviour of Fr and other alkali atoms like Cs and Rb thoroughly, more on-line emission channeling experiments are needed. We propose a number of shifts for each element, where the temperature of the implanted metals will be varied between 50$^\\circ$ and 700$^\\circ$~K. Temperature dependent measurements wi...

  17. Regioselective hydrogen isotope exchange reaction in benzoic acid and its alkali metal salts

    International Nuclear Information System (INIS)

    Nakagawa, Akiko; Hasegawa, Hideaki; Oohashi, Kunio; Seki, Hiroko.

    1997-01-01

    The hydrogen isotope exchange reaction of benzoic and acid its alkali metal salts with deuterium oxide was studied in the presence of RhCl 3 ·3H 2 O. The products were analyzed by 1 H- and 13 C-NMR spectroscopies. High regioselectivity of the exchange at the ortho positions was established, and the extent of deuterium labeling and the distribution of d 0 , d 1 , and d 2 were determined. The reaction mechanism was briefly discussed. (author)

  18. Ab initio GW quasiparticle calculation of small alkali-metal clusters

    CERN Document Server

    Ishii, S; Louie, S G; Ohno, K

    2001-01-01

    Quasiparticle energies of small alkali-metal clusters are evaluated from first principles by means of the GW approximation with the generalized plasmon-pole model. An all-electron mixed-basis approach, in which wave function is represented as a linear combination of both plane waves and atomic orbitals, is adopted in the calculation. Obtained quasiparticle energies (ionization potential and electron affinity) are in good agreement with experimental data.

  19. The mechanism of diffusion and ionic transport of alkali metal ions in the particles of tin(IV) antimonate

    International Nuclear Information System (INIS)

    El-Naggar, I.M.; El-Absy, M.A.; Aly, S.I.; Atomic Energy Establishment, Cairo

    1992-01-01

    The kinetics of exchange Li + , Na + , K + and Cs + ions of tin(IV) antimonate with H + form was studied under particle-diffusion-control conditions at different temperatures. The value of activation energy, diffusion coefficient and entropy of activation increase with the ionic mobilities and radii, and decrease with the hydration energy of the alkali metal ions. On the basis of the kinetic parameters, the exchange of alkali metal ions occurs in the unhydrated form. (author). 29 refs.; 4 figs.; 2 tabs

  20. Low-temperature operation of copper-vapor lasers by using vapor-complex reaction of metallic copper and metal halide

    OpenAIRE

    SAITO, HIROSHI; TANIGUCHI, HIROSHI

    1985-01-01

    The first successful use of vapor-complex reactions for a laser is reported. Vapor-complex reactions between metallic copper and metal halides are found effective in reducing the operating temperature in copper-vapor lasers. By using a vapor-complex reaction of Cu+AlBr3, a laser oscillation starts at a reservoir temperature of about 25°C. The results obtained by the mass spectroscopic analysis support the presumption that the copper vapor is generated through a vapor-complex reaction process.

  1. A review of flexible lithium-sulfur and analogous alkali metal-chalcogen rechargeable batteries.

    Science.gov (United States)

    Peng, Hong-Jie; Huang, Jia-Qi; Zhang, Qiang

    2017-08-29

    Flexible energy storage systems are imperative for emerging flexible devices that are revolutionizing our life. Lithium-ion batteries, the current main power sources, are gradually approaching their theoretical limitation in terms of energy density. Therefore, alternative battery chemistries are urgently required for next-generation flexible power sources with high energy densities, low cost, and inherent safety. Flexible lithium-sulfur (Li-S) batteries and analogous flexible alkali metal-chalcogen batteries are of paramount interest owing to their high energy densities endowed by multielectron chemistry. In this review, we summarized the recent progress of flexible Li-S and analogous batteries. A brief introduction to flexible energy storage systems and general Li-S batteries has been provided first. Progress in flexible materials for flexible Li-S batteries are reviewed subsequently, with a detailed classification of flexible sulfur cathodes as those based on carbonaceous (e.g., carbon nanotubes, graphene, and carbonized polymers) and composite (polymers and inorganics) materials and an overview of flexible lithium anodes and flexible solid-state electrolytes. Advancements in other flexible alkali metal-chalcogen batteries are then introduced. In the next part, we emphasize the importance of cell packaging and flexibility evaluation, and two special flexible battery prototypes of foldable and cable-type Li-S batteries are highlighted. In the end, existing challenges and future development of flexible Li-S and analogous alkali metal-chalcogen batteries are summarized and prospected.

  2. Inclusion separation of alkali metals in emulsion liquid membranes by nanobaskets of calix[4]crown-3

    Directory of Open Access Journals (Sweden)

    B. Mokhtari

    2012-12-01

    Full Text Available Nano-assisted inclusion separation of alkali metals from basic solutions was reported by an inclusion-facilitated emulsion liquid membrane process. The novelty of this study is application of nanobaskets of calixcrown in the selective and efficient separation of alkali metals as both the carrier and the surfactant. For this purpose, two diacids, p-tert-butylcalix[4]arene-1,2-crown-3 in the cone and the 1,2alternate conformation, as well as another diacid, p-tert-butylcalix[4]arene-1,2-thiacrown-3 in the cone conformation, were synthesized. Their inclusion-extraction parameters were optimized, including the calixcrown scaffold (04, 4 wt% as the carrier/demulsifier, commercial kerosene as the diluent in the membrane, sulphonic acid (0.2 M and ammonium carbonate (0.4 M as the strip and the feed phases; the phase and the treat ratios were 0.8 and 0.3, mixing speed (300 rpm, and initial solute concentration (100 mg/L. The selectivity of the membrane was examined for more than ten interfering cations was examined and the results reveled that, under the optimized operating condition, the degree of inclusion-extraction of alkali metals was as high as 98-99%.

  3. Solvation Effect on Complexation of Alkali Metal Cations by a Calix[4]arene Ketone Derivative.

    Science.gov (United States)

    Požar, Josip; Nikšić-Franjić, Ivana; Cvetnić, Marija; Leko, Katarina; Cindro, Nikola; Pičuljan, Katarina; Borilović, Ivana; Frkanec, Leo; Tomišić, Vladislav

    2017-09-14

    The medium effect on the complexation of alkali metal cations with a calix[4]arene ketone derivative (L) was systematically examined in methanol, ethanol, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and acetonitrile. In all solvents the binding of Na + cation by L was rather efficient, whereas the complexation of other alkali metal cations was observed only in methanol and acetonitrile. Complexation reactions were enthalpically controlled, while ligand dissolution was endothermic in all cases. A notable influence of the solvent on NaL + complex stability could be mainly attributed to the differences in complexation entropies. The higher NaL + stability in comparison to complexes with other alkali metal cations in acetonitrile was predominantly due to a more favorable complexation enthalpy. The 1 H NMR investigations revealed a relatively low affinity of the calixarene sodium complex for inclusion of the solvent molecule in the calixarene hydrophobic cavity, with the exception of acetonitrile. Differences in complex stabilities in the explored solvents, apart from N,N-dimethylformamide and acetonitrile, could be mostly explained by taking into account solely the cation and complex solvation. A considerable solvent effect on the complexation equilibria was proven to be due to an interesting interplay between the transfer enthalpies and entropies of the reactants and the complexes formed.

  4. Gaussian-basis LDA and GGA calculations for alkali-metal equations of state

    International Nuclear Information System (INIS)

    Jaffe, J.E.; Lin, Z.; Hess, A.C.

    1998-01-01

    Recently there has been renewed interest in implementations of density-functional theory for solids using various types of localized basis sets, including atom-centered Gaussian-type functions. While such methods are clearly well adapted to most insulating and semiconducting systems, one might expect them to give a less-than-optimal description of metals relative to plane-wave-type methods. Nevertheless, several successful applications of local-basis methods to metals have recently been reported. Here, we report an application of our Gaussian linear combination of atomic orbitals (LCAO) code to some extremely free-electron-like metals, namely, the alkali metals Li, Na, and K. In agreement with other calculations (both local and plane wave) we find that the local-density approximation (LDA) lattice constants are relatively poor (∼-3% from experiment for the alkali metals versus ±1% for many other solids) and that the LDA bulk moduli are ∼30% too high. We find that the Perdew-Burke-Enzerhof (PBE) version of the generalized-gradient approximation (GGA) corrects most of this error, in agreement with earlier calculations using similar GGA functionals. The Becke-Lee-Yang-Parr GGA functional gives similar results for the alkali-metal equations of state but is found to overcorrect the errors of the LDA for the cohesive energies, for which the PBE functional is in better agreement with experiment. Our results indicate that the Gaussian-LCAO method should be able to give accurate results for nearly any crystalline solid, since it succeeds even where it would be expected to have the most difficulty. copyright 1998 The American Physical Society

  5. IUPAC-NIST Solubility Data Series. 75. Nonmetals in Liquid Alkali Metals

    Science.gov (United States)

    Borgstedt, Hans Ulrich; Guminski, Cezary; Borgstedt, Hans Ulrich; Guminski, Cezary

    2001-07-01

    Liquid alkali metals have several physical properties which favor their use in a number of important applications. For example, their large liquidus temperature range and their excellent heat transfer properties are important for use as heat transfer media. They are used in large nuclear reactors in which hundreds of tons of sodium are circulating, and in small parts of engines for cooling of valves. Since these metals are among the most electropositive elements, several of them (Li, Na) can be used in high specific capacity and high energy density batteries at moderately elevated temperatures. The compatibility of metallic constructional materials which are used to contain the liquid metals is strongly influenced by nonmetals present in the liquids. The physical properties of the liquid metals are also influenced by dissolved substances. Several nonmetals dissolved in alkali metals are able to form ternary compounds with components of the constructional materials. Thus, corrosion and compatibility studies have been accompanied by extensive chemical work related to the solutions of non-metallic substances in liquid alkali metals. All available solubility data of nonmetallic elements and some of their compounds in the five liquid alkali metal solvents (Li, Na, K, Rb, and Cs) are collected and compiled. Original publications with reliable data and information on the methods used to generate them are reported in individual Compilations. When numerical data are not given in a publication, the data are often read out from figures and converted into numerical data by the compilers. The precision of this procedure is indicated in the Compilations under Estimated Error. Evaluated solubility data are tabulated at the end of the Critical Evaluations: if there is agreement of at least two independent studies within the experimental error, the solubility values are assigned to the "recommended" category. Values are assigned as "tentative," if only one reliable result was

  6. Modulation of the work function of fullerenes C60 and C70 by alkali-metal adsorption: A theoretical study

    International Nuclear Information System (INIS)

    Liang, Hong; Xu, Shunfu; Liu, Weihui; Sun, Yueqiang; Liu, Xiangfa; Zheng, Xinqing; Li, Sen; Zhang, Qiang; Zhu, Ziliang; Zhang, Xiaochun; Dong, Chengguo; Li, Chun; Yuan, Guang; Mimura, Hitenori

    2013-01-01

    The impact of alkali-metal (Li/Na/Cs) adsorption on work function of fullerenes C 60 and C 70 was investigated by first-principles calculations. After adsorption, the work functions of fullerenes C 60 and C 70 decrease distinctly and vary linearly with the electronegativity of the alkali metal elements, and the positions where the alkali atoms are adsorbed considerably influence the work functions. On the contrary, a vacancy defect elevates the work functions of the fullerenes C 60 and C 70 . The variation in the work functions rests with variation in Fermi level (which are attributed to charge transfer) and variation in vacuum levels (which are attributed to the induced dipole moments). Moreover, alkali-metal adsorption can also improve the electric conductivity of a fullerene mixture of C 60 and C 70 .

  7. Theory of alkali-metal-induced reconstructions of fcc(100) surfaces

    DEFF Research Database (Denmark)

    Christensen, Ole Bøssing; Jacobsen, Karsten Wedel

    1992-01-01

    Calculations of missing-row reconstruction energies of the fcc(100) surfaces of the metals Al, Ni, Pd, Pt, Cu, Ag, and Au have been performed with the effective-medium theory with and without the presence of a potassium overlayer. It is shown that the tendency to reconstruct in the presence...... of adsorbed K is largest for Ag. This is in accordance with recent experiments indicating a potassium-induced missing-row reconstruction for Ag, but not for other metals. The tendency is shown to be related to the relatively low bulk modulus of silver. Differences from the well-known alkali...

  8. The non-pair forces and phonon dispersion in heavy alkali metals

    International Nuclear Information System (INIS)

    Aradhana, Km.; Rathore, R.P.S.

    1990-01-01

    Two types of non-pair forces, one from the Born-Mayer and the other from the Morse potential, are derived to discuss the response of electrons in heavy alkali metals, i.e., rubidium and cesium. The potentials are added to the two-body potential of Morse to account also for the ion-ion interactions. The potentials so obtained are employed to predict the phonon dispersion relations in bcc metals, which are also compared with recent precise neutron scattering data. (author). 1 fig, 3 tabs., 24 refs

  9. Density dependent atomic motion in a liquid alkali metal

    International Nuclear Information System (INIS)

    Pilgrim, W.-C.; Hosokawa, S.; Morkel, C.

    2001-01-01

    Inelastic X-ray and neutron scattering results obtained from liquid sodium and rubidium are presented. They cover the entire liquid range between melting and liquid vapour critical point. At high densities the dynamics of the liquid metal is characterized by collective excitations. The corresponding dispersion relations indicate the existence of surprisingly stable next neighbouring shells leading to an increase of the propagation speed for the collective modes. Below 2ρ crit. the dynamics changes from collective to localized indicating the existence of molecular aggregates. This interpretation is in accord with a simple model where the properties of a Rb- and a Rb 2 - lattice are calculated using density functional theory. (orig.)

  10. Alkali or alkaline earth metal promoted catalyst and a process for methanol synthesis using alkali or alkaline earth metals as promoters

    Science.gov (United States)

    Tierney, John W.; Wender, Irving; Palekar, Vishwesh M.

    1995-01-01

    The present invention relates to a novel route for the synthesis of methanol, and more specifically to the production of methanol by contacting synthesis gas under relatively mild conditions in a slurry phase with a heterogeneous catalyst comprising reduced copper chromite impregnated with an alkali or alkaline earth metal. There is thus no need to add a separate alkali or alkaline earth compound. The present invention allows the synthesis of methanol to occur in the temperature range of approximately 100.degree.-160.degree. C. and the pressure range of 40-65 atm. The process produces methanol with up to 90% syngas conversion per pass and up to 95% methanol selectivity. The only major by-product is a small amount of easily separated methyl formate. Very small amounts of water, carbon dioxide and dimethyl ether are also produced. The present catalyst combination also is capable of tolerating fluctuations in the H.sub.2 /CO ratio without major deleterious effect on the reaction rate. Furthermore, carbon dioxide and water are also tolerated without substantial catalyst deactivation.

  11. Designable ultra-smooth ultra-thin solid-electrolyte interphases of three alkali metal anodes.

    Science.gov (United States)

    Gu, Yu; Wang, Wei-Wei; Li, Yi-Juan; Wu, Qi-Hui; Tang, Shuai; Yan, Jia-Wei; Zheng, Ming-Sen; Wu, De-Yin; Fan, Chun-Hai; Hu, Wei-Qiang; Chen, Zhao-Bin; Fang, Yuan; Zhang, Qing-Hong; Dong, Quan-Feng; Mao, Bing-Wei

    2018-04-09

    Dendrite growth of alkali metal anodes limited their lifetime for charge/discharge cycling. Here, we report near-perfect anodes of lithium, sodium, and potassium metals achieved by electrochemical polishing, which removes microscopic defects and creates ultra-smooth ultra-thin solid-electrolyte interphase layers at metal surfaces for providing a homogeneous environment. Precise characterizations by AFM force probing with corroborative in-depth XPS profile analysis reveal that the ultra-smooth ultra-thin solid-electrolyte interphase can be designed to have alternating inorganic-rich and organic-rich/mixed multi-layered structure, which offers mechanical property of coupled rigidity and elasticity. The polished metal anodes exhibit significantly enhanced cycling stability, specifically the lithium anodes can cycle for over 200 times at a real current density of 2 mA cm -2 with 100% depth of discharge. Our work illustrates that an ultra-smooth ultra-thin solid-electrolyte interphase may be robust enough to suppress dendrite growth and thus serve as an initial layer for further improved protection of alkali metal anodes.

  12. Alkali metal bismuth(III) chloride double salts

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Andrew W. [Department of Chemistry, College of William and Mary, Williamsburg, VA 23187 (United States); Nicholas, Aaron; Ahern, John C. [Department of Chemistry, University of Maine, Orono, ME 04469 (United States); Chan, Benny [Department of Chemistry, College of New Jersey, Ewing, NJ 08628-0718 (United States); Patterson, Howard H. [Department of Chemistry, University of Maine, Orono, ME 04469 (United States); Pike, Robert D., E-mail: rdpike@wm.edu [Department of Chemistry, College of William and Mary, Williamsburg, VA 23187 (United States)

    2016-06-15

    near 295, 340, and 380 nm and a broad emission near 440 nm. - Graphical abstract: The double salts Na2BiCl5·5H2O, K7Bi3Cl16, Rb3BiCl6·0.5H2O, Cs3BiCl6, and Cs3Bi2Cl9 were formed by co-crystallization of MCl (M = Na, K, Rb, Cs) with BiOCl in aqueous HCl. The crystal structures and solid state luminescence are reported. - Highlights: • New double salt phases are reported for NaCl/BiCl{sub 3}, KCl/BiCl{sub 3}, RbCl/BiCl{sub 3}, and CsCl/BiCl{sub 3}. • A variety of alkali chloride:bismuth chloride ratios are reported. • Chloride bridging produces oligomeric and/or polymeric bismuth chloride chains in several cases. • Convenient bulk synthesis from BiOCl is reported. • Four of the five reported double salts exhibit photoluminescence as a result of charge transfer.

  13. Corrosion-electrochemical behavior of metals in alkali solutions

    International Nuclear Information System (INIS)

    Levin, V.A.; Levina, E.Eh.

    1995-01-01

    Results of an investigation into corrosion-electrochemical behaviour of 12Kh18N10T, 10Kh17N13M2T, 08Kh21N6M2T and 15Kh25T steels, 06KhN28MDT and KhN78T alloys as well as NP-2 nickel in sodium, potassium and lithium hydroxide solutions at 95-180 deg C temperatures are considered. It is ascertained, that anode polarization curves of all metals irrespective of hydroxide nature, concentration, temperature, presence of chloride and chlorate additions, are of identic character. The movement of anode polarization curves in the direction of lower current of hydroxide type in NaOH-KOH-LiOH series, temperature and solution concentration reduction at other equal terms. 12 refs.; 6 figs

  14. The Corrosion Protection of Metals by Ion Vapor Deposited Aluminum

    Science.gov (United States)

    Danford, M. D.

    1993-01-01

    A study of the corrosion protection of substrate metals by ion vapor deposited aluminum (IVD Al) coats has been carried out. Corrosion protection by both anodized and unanodized IVD Al coats has been investigated. Base metals included in the study were 2219-T87 Al, 7075-T6 Al, Titanium-6 Al-4 Vanadium (Ti-6Al-4V), 4130 steel, D6AC steel, and 4340 steel. Results reveal that the anodized IVD Al coats provide excellent corrosion protection, but good protection is also achieved by IVD Al coats that have not been anodized.

  15. Microscopic structure of the alkali metal-alkali halide solutions in the metallic regime. A neutron-scattering investigation

    International Nuclear Information System (INIS)

    Jal, J.F.; Mathieu, C.; Dupuy, J.; Chieux, P.

    1990-01-01

    The partial structure factors have been measured for two compositions (x = 0.8; x = 0.6) in the metallic regime of the solutions K x (KCl) 1-x . The potassium-potassium partials are compared with the pure potassium structure factor measured at 700 0 C. Ionic-like characteristics are obtained for the partials, even for x = 0.8. The number of potassium atoms surrounding chlorine is about four, suggesting rather open structures. Details are given on the data analysis of this difficult experiment. (author)

  16. Method of physical vapor deposition of metal oxides on semiconductors

    Science.gov (United States)

    Norton, David P.

    2001-01-01

    A process for growing a metal oxide thin film upon a semiconductor surface with a physical vapor deposition technique in a high-vacuum environment and a structure formed with the process involves the steps of heating the semiconductor surface and introducing hydrogen gas into the high-vacuum environment to develop conditions at the semiconductor surface which are favorable for growing the desired metal oxide upon the semiconductor surface yet is unfavorable for the formation of any native oxides upon the semiconductor. More specifically, the temperature of the semiconductor surface and the ratio of hydrogen partial pressure to water pressure within the vacuum environment are high enough to render the formation of native oxides on the semiconductor surface thermodynamically unstable yet are not so high that the formation of the desired metal oxide on the semiconductor surface is thermodynamically unstable. Having established these conditions, constituent atoms of the metal oxide to be deposited upon the semiconductor surface are directed toward the surface of the semiconductor by a physical vapor deposition technique so that the atoms come to rest upon the semiconductor surface as a thin film of metal oxide with no native oxide at the semiconductor surface/thin film interface. An example of a structure formed by this method includes an epitaxial thin film of (001)-oriented CeO.sub.2 overlying a substrate of (001) Ge.

  17. Vaporization of tungsten-metal in steam at high temperatures

    International Nuclear Information System (INIS)

    Greene, G.A.; Finfrock, C.C.

    2000-01-01

    The vaporization of tungsten from the APT spallation target dominates the radiological source term for unmitigated target overheating accidents. Chemical reactions of tungsten with steam which persist to tungsten temperatures as low as 800 C result in the formation of a hydrated tungsten-oxide which has a high vapor pressure and is readily convected in a flowing atmosphere. This low-temperature vaporization reaction essentially removes the oxide film that forms on the tungsten-metal surface as soon as it forms, leaving behind a fresh metallic surface for continued oxidation and vaporization. Experiments were conducted to measure the oxidative vaporization rates of tungsten in steam as part of the effort to quantify the MT radiological source term for severe target accidents. Tests were conducted with tungsten rods (1/8 inch diameter, six inches long) heated to temperatures from approximately 700 C to 1350 C in flowing steam which was superheated to 140 C. A total of 19 experiments was conducted. Fifteen tests were conducted by RF induction heating of single tungsten rods held vertical in a quartz glass retort. Four tests were conducted in a vertically-mounted tube furnace for the low temperature range of the test series. The aerosol which was generated and transported downstream from the tungsten rods was collected by passing the discharged steam through a condenser. This procedure insured total collection of the steam along with the aerosol from the vaporization of the rods. The results of these experiments revealed a threshold temperature for tungsten vaporization in steam. For the two tests at the lowest temperatures which were tested, approximately 700 C, the tungsten rods were observed to oxidize without vaporization. The remainder of the tests was conducted over the temperature range of 800 C to 1350 C. In these tests, the rods were found to have lost weight due to vaporization of the tungsten and the missing weight was collected in the downstream condensate

  18. Interactions of nucleobases with alkali earth metal cations--electrospray ionization mass spectrometric study.

    Science.gov (United States)

    Frańska, Magdalena

    2007-01-01

    Interactions of nucleobases with alkali earth metal cations have been studied by electrospray ionization mass spectrometry (ESI-MS). Nucleobases containing at least one oxygen atom form stable complexes with alkali earth metal cations. This phenomenon can be explained on the grounds of the well known theory of hard and soft acids and bases. Uracil and thymine make complexes only when in their deprotonoted forms. The cations of great radii (Sr(2+), Ba(2+)) are more prone to form complexes of stoichiometry 1:1 with uracil and thymine than the cations of small radii (Mg(2+), Ca(2+)). On the other hand, Mg(2+) forms complexes of stoichiometry 2:1 and 3:2 with uracil and thymine. Gas-phase stabilities of the 1:1 complexes are higher for the cations of small radii, in contrast to the solution stabilities. For cytosine and 9- methylhypoxantine the 1:1 complexes of their deprotonated forms are observed at higher cone voltage as a result of HCl molecule loss from the complexes containing the counter ion (Cl(-)). In solution, more stable complexes are formed with metal cations of low radii. Gas-phase stability of the complexes formed by deprotonated 9- methyl-hypoxantine increases with increasing metal cation radius.

  19. Discriminating Properties of Alkali Metal Ions Towards the Constituents of Proteins and Nucleic Acids. Conclusions from Gas-Phase and Theoretical Studies.

    Science.gov (United States)

    Rodgers, Mary T; Armentrout, Peter B

    2016-01-01

    Quantitative insight into the structures and thermodynamics of alkali metal cations interacting with biological molecules can be obtained from studies in the gas phase combined with theoretical work. In this chapter, the fundamentals of the experimental and theoretical techniques are first summarized and results for such work on complexes of alkali metal cations with amino acids, small peptides, and nucleobases are reviewed. Periodic trends in how these interactions vary as the alkali metal cations get heavier are highlighted.

  20. The influence of chlorine on the fate and activity of alkali metals during the gasification of wood

    Energy Technology Data Exchange (ETDEWEB)

    Struis, R.; Scala, C. von; Schuler, A.; Stucki, S. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Chlorine clearly inhibits the CO{sub 2}-gasification reaction of charcoal at 800{sup o}C. From this and other observations the picture emerges that the reduction in the gasification reactivity of the charcoal is intimately related to the deactivation of the catalytically active alkali metals residing in the wood due to the formation of the chloride salt. It is argued that the heavy metal chlorides will likely transfer the chlorine to the indigenous alkali metals during the pyrolysis stage of the wood. The fate of the thus formed alkali metal chlorides can then be either their removal from the sample (evaporation), or, when present at the gasification stage, re-activation (i.e., de-chlorination) under our gasification conditions. (author) 3 figs., 4 refs.

  1. Binding of monovalent alkali metal ions with negatively charged phospholipid membranes.

    Science.gov (United States)

    Maity, Pabitra; Saha, Baishakhi; Kumar, Gopinatha Suresh; Karmakar, Sanat

    2016-04-01

    We have systematically investigated the effect of various alkali metal ions with negatively charged phospholipid membranes. Size distributions of large unilamellar vesicles have been confirmed using dynamic light scattering. Zeta potential and effective charges per vesicle in the presence of various alkali metal ions have been estimated from the measured electrophoretic mobility. We have determined the intrinsic binding constant from the zeta potential using electrostatic double layer theory. The reasonable and consistent value of the intrinsic binding constant of Na(+), found at moderate NaCl concentration (10-100 mM), indicates that the Gouy-Chapman theory cannot be applied for very high (> 100mM) and very low (concentrations. The isothermal titration calorimetry study has revealed that the net binding heat of interaction of the negatively charged vesicles with monovalent alkali metal ions is small and comparable to those obtained from neutral phosphatidylcholine vesicles. The overall endothermic response of binding heat suggests that interaction is primarily entropy driven. The entropy gain might arise due to the release of water molecules from the hydration layer vicinity of the membranes. Therefore, the partition model which does not include the electrostatic contribution suffices to describe the interaction. The binding constant of Na(+) (2.4 ± 0.1 M(-1)), obtained from the ITC, is in agreement with that estimated from the zeta potential (-2.0 M(-1)) at moderate salt concentrations. Our results suggest that hydration dynamics may play a vital role in the membrane solution interface which strongly affects the ion-membrane interaction. Copyright © 2016 Elsevier B.V. All rights reserved

  2. Thermochemical ablation therapy of VX2 tumor using a permeable oil-packed liquid alkali metal.

    Directory of Open Access Journals (Sweden)

    Ziyi Guo

    Full Text Available Alkali metal appears to be a promising tool in thermochemical ablation, but, it requires additional data on safety is required. The objective of this study was to explore the effectiveness of permeable oil-packed liquid alkali metal in the thermochemical ablation of tumors.Permeable oil-packed sodium-potassium (NaK was prepared using ultrasonic mixing of different ratios of metal to oil. The thermal effect of the mixture during ablation of muscle tissue ex vivo was evaluated using the Fluke Ti400 Thermal Imager. The thermochemical effect of the NaK-oil mixture on VX2 tumors was evaluated by performing perfusion CT scans both before and after treatment in 10 VX2 rabbit model tumors. VX2 tumors were harvested from two rabbits immediately after treatment to assess their viability using trypan blue and hematoxylin and eosin (H.E. staining.The injection of the NaK-oil mixture resulted in significantly higher heat in the ablation areas. The permeable oil controlled the rate of heat released during the NaK reaction with water in the living tissue. Perfusion computed tomography and its parameter map confirmed that the NaK-oil mixture had curative effects on VX2 tumors. Both trypan blue and H.E. staining showed partial necrosis of the VX2 tumors.The NaK-oil mixture may be used successfully to ablate tumor tissue in vivo. With reference to the controlled thermal and chemical lethal injury to tumors, using a liquid alkali in ablation is potentially an effective and safe method to treat malignant tumors.

  3. Electronic nature of zwitterionic alkali metal methanides, silanides and germanides - a combined experimental and computational approach.

    Science.gov (United States)

    Li, H; Aquino, A J A; Cordes, D B; Hase, W L; Krempner, C

    2017-02-01

    Zwitterionic group 14 complexes of the alkali metals of formula [C(SiMe 2 OCH 2 CH 2 OMe) 3 M], (M- 1 ), [Si(SiMe 2 OCH 2 CH 2 OMe) 3 M], (M- 2 ), [Ge(SiMe 2 OCH 2 CH 2 OMe) 3 M], (M- 3 ), where M = Li, Na or K, have been prepared, structurally characterized and their electronic nature was investigated by computational methods. Zwitterions M- 2 and M- 3 were synthesized via reactions of [Si(SiMe 2 OCH 2 CH 2 OMe) 4 ] ( 2 ) and [Ge(SiMe 2 OCH 2 CH 2 OMe) 4 ] ( 3 ) with MOBu t (M = Li, Na or K), resp., in almost quantitative yields, while M- 1 were prepared from deprotonation of [HC(SiMe 2 OCH 2 CH 2 OMe) 3 ] ( 1 ) with LiBu t , NaCH 2 Ph and KCH 2 Ph, resp. X-ray crystallographic studies and DFT calculations in the gas-phase, including calculations of the NPA charges confirm the zwitterionic nature of these compounds, with the alkali metal cations being rigidly locked and charge separated from the anion by the internal OCH 2 CH 2 OMe donor groups. Natural bond orbital (NBO) analysis and the second order perturbation theory analysis of the NBOs reveal significant hyperconjugative interactions in M- 1 -M- 3 , primarily between the lone pair and the antibonding Si-O orbitals, the extent of which decreases in the order M- 1 > M- 2 > M- 3 . The experimental basicities and the calculated gas-phase basicities of M- 1 -M- 3 reveal the zwitterionic alkali metal methanides M- 1 to be significantly stronger bases than the analogous silanides M- 2 and germanium M- 3 .

  4. Evaluation of Ce3+ and alkali metal ions Co-doped LiSrAlF6 crystalline scintillators

    International Nuclear Information System (INIS)

    Wakahara, Shingo; Yanagida, Takayuki; Fujimoto, Yutaka; Yokota, Yuui; Pejchal, Jan; Kurosawa, Shunsuke; Suzuki, Shotaro; Kawaguchi, Noriaki; Fukuda, Kentaro; Yoshikawa, Akira

    2013-01-01

    High scintillation efficiency of Eu-doped LiSrAlF 6 (LiSAF) and LiCaAlF 6 (LiCAF) codoped with alkali metal ions has been reported in our recent studies. Thus in this paper, we demonstrated the scintillation properties of 1% Ce-doped LiSAF crystals with 1% alkali metal ions co-doping to increase the light yield and understand the scintillation mechanism. The crystals showed intense emission band corresponding to the 5d-4f transition of Ce 3+ , and their light yields under thermal neutron excitation were higher than that of the Ce only doped crystal. Especially, the light yield of Ce–Na co-doped crystal exceeded about two times that of Ce only doped one. -- Highlights: ► Ce-doped and alkali metal co-doped LiSAF crystals were grown by μ-PD method. ► Alkali metal co-doped crystals showed higher light yield than Ce only doped crystal. ► Decay time of alkali metal co-doped LiSAF were longer than that of Ce only doped one

  5. Computer simulation studies of ternary uranate phases with alkali and alkaline-earth metals: Pt. 1

    International Nuclear Information System (INIS)

    Ball, R.G.J.

    1992-01-01

    Solid-state computer simulation techniques have been used to study the alkali and alkaline-earth metal MUO 3 uranate phases. These compounds display an interesting gradation in their structures which, it is shown, is accompanied by a variation in their intrinsic defect chemistry. For example, in the alkali-metal series, LiUO 3 adopts the lithium niobate structure and lithium Frenkel disorder dominates whereas KUO 3 and RbUO 3 adopt regular perovskite structures with Schottky defects being dominant. For the alkaline-earth metal compounds, both the calculations and experiment show that only SrUO 3 and BaUO 3 are stable with respect to the binary oxides. Both of these phases adopt the GdFeO 3 distorted perovskite structure and both have anti-site defects as the dominant intrinsic disorder. The tendency for anti-site disorder is also seen in the oxidation behaviour of these compounds. The calculations suggest that the oxidation will occur through the formation of a secondary UO 2 fluorite phase by the movement of alkaline-earth ions onto uranium sites, leaving behind M vacancies. The calculated energies for such oxidation processes are particularly favourable. The solution of alkaline-earth oxide, M 11 O, in M 11 UO 3 is shown to occur via a mechanism in which the M 11 ions substitute onto both the M 11 and U sublattices. (author)

  6. Implementation of Hydrodynamic Simulation Code in Shock Experiment Design for Alkali Metals

    Science.gov (United States)

    Coleman, A. L.; Briggs, R.; Gorman, M. G.; Ali, S.; Lazicki, A.; Swift, D. C.; Stubley, P. G.; McBride, E. E.; Collins, G.; Wark, J. S.; McMahon, M. I.

    2017-10-01

    Shock compression techniques enable the investigation of extreme P-T states. In order to probe off-Hugoniot regions of P-T space, target makeup and laser pulse parameters must be carefully designed. HYADES is a hydrodynamic simulation code which has been successfully utilised to simulate shock compression events and refine the experimental parameters required in order to explore new P-T states in alkali metals. Here we describe simulations and experiments on potassium, along with the techniques required to access off-Hugoniot states.

  7. Device or installation for use in a liquid alkali metal environment

    International Nuclear Information System (INIS)

    Campbell, C.S.

    1978-01-01

    The invention relates to the use of materials in liquid alkali metals, especially sodium, for support faces. It is proposed to use as a complementary support face for stainless steel bearings a nickel base aluminized alloy. The invention is explained by the example of a heat exchanger for a liquid sodium cooled fast breeder reactor. In the design, fuel rods with stainless steel claddings are supported by cell type grids. In the invention, these grids are made of nickel base alloys and carry bushings with aluminized bores constituting the complementary support faces for the nuclear fuel rods. (RW) [de

  8. Synthesis and adsorption investigations of zeolites MCM-22 and MCM-49 modified by alkali metal cations

    Czech Academy of Sciences Publication Activity Database

    Pawlesa, Justyna; Zukal, Arnošt; Čejka, Jiří

    2007-01-01

    Roč. 13, 3-4 (2007), s. 257-265 ISSN 0929-5607 Grant - others:DeSSANS(XE) SES6-CT-2005-020133; INDENS(XE) MRTN-CT-2004-005503 Institutional research plan: CEZ:AV0Z40400503 Source of funding: R - rámcový projekt EK ; R - rámcový projekt EK Keywords : MCM-22 zeolite * MCM-49 zeolite * alkali metal cation exchange * N2 and CO2 adsorption Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.880, year: 2007

  9. s-wave elastic scattering of antihydrogen off atomic alkali-metal targets

    International Nuclear Information System (INIS)

    Sinha, Prabal K.; Ghosh, A. S.

    2006-01-01

    We have investigated the s-wave elastic scattering of antihydrogen atoms off atomic alkali-metal targets (Li, Na, K, and Rb) at thermal energies (10 -16 -10 -4 a.u.) using an atomic orbital expansion technique. The elastic cross sections of these systems at thermal energies are found to be very high compared to H-H and H-He systems. The theoretical models employed in this study are so chosen to consider long-range forces dynamically in the calculation. The mechanism of cooling suggests that Li may be considered to be a good candidate as a buffer gas for enhanced cooling of antihydrogen atoms to ultracold temperature

  10. High-performance ion-exchange chromatography of alkali metals with conductivity detection

    International Nuclear Information System (INIS)

    Ahmad, M.; Khan, A.R.

    1981-01-01

    High-performance ion-exchange chromatography of alkali metal and ammonium ions was studied using a conductivity meter as detector. Elution with 0.003 N mitric acid gave excellent resolution. Sensitivity levels, for a 200 micro litre injection, vary from 5 ppm for potassium to 0.1 ppm for lithium. A method to decrease retention times by reducing the exchange capacity of the cation exchange column used by loading it with calciumions, without affecting the resolation, has been described. Application of the method to water, soil and uranium dioxide samples has been demonstrated. (author)

  11. High power density performance of WPt and WRh electrodes in the alkali metal thermoelectric converter

    Science.gov (United States)

    Williams, R. M.; Jeffries-Nakamura, B.; Underwood, M. L.; Wheeler, B. L.; Loveland, M. E.; Kikkert, S. J.; Lamb, J. L.; Cole, T.; Kummer, J. T.; Bankston, C. P.

    1989-01-01

    The properties of the alkali metal thermoelectric converter (AMTEC) are discussed together with those of an efficient AMTEC electrode. Three groups of electrodes were prepared and tested for their performance as AMTEC electrodes, including WPt-T3, WRh-B1, and WRh-B2. The best electrodes of both WPt and WRh types typically exhibited low porosity, and thickness greater than 0.8 micron, which indicated that transport in these electrodes does not occur by a purely free-molecular flow mode. The observed values of the exchange current were found to be within the range of those observed for oxide-free Mo electrodes under similar conditions.

  12. Cycle analysis of an alkali metal thermo-electric converter for small capillary type

    International Nuclear Information System (INIS)

    Yoon, Suk Goo; Ku, Jae Hyun; Lee, Jae Keun; Tanaka, Kotaro

    2000-01-01

    This paper describes the design of a small size Alkali Metal Thermal to Electric Converter (AMTEC) which employs a capillary structure for recirculating sodium working fluid. The cycle is based on the simple and small capillary type β - alumina and wick tube element. The proposed cell consists of the 37 conversion elements with capillary tube of 50μm in diameter and the sealed cylindrical vessel of 22mm in outer diameter. Results on the cycle analysis of sodium flow and heat transfer in the cell showed that the expected power output was 4.65 W and the conversion efficiency was 19% for the source temperature of 900 K

  13. Chlorination of uranium oxides in melts of alkali metal chlorides and their mixtures

    International Nuclear Information System (INIS)

    Vorobej, M.P.; Bevz, A.S.; Skiba, O.V.

    1978-01-01

    Chlorination of UO 2 , U 3 O 8 , and UO 3 in melts of chlorides of alkali metals and of their mixtures has been studied by thermogravimetric, X-ray phase, and spectrophotometric methods. The thermogravimetric method has been proposed for evaluating the state of uranylcation in the melt; the effect of the composition of the oxide being chlorinated and of the salt-solvent on the composition of the chlorination products has been studied. The effect of the composition of the chlorination products on the stoichiometry of the electrolytic uranium dioxide has been shown

  14. UV and IR spectroscopy of cold 1,2-dimethoxybenzene complexes with alkali metal ions

    OpenAIRE

    Inokuchi Y; Boyarkin OV; Ebata T; Rizzo TR

    2012-01-01

    We report UV photodissociation (UVPD) and IR UV double resonance spectra of 12 dimethoxybenzene (DMB) complexes with alkali metal ions M+center dot DMB (M = Li Na K Rb and Cs) in a cold 22 pole ion trap. The UVPD spectrum of the Li+ complex shows a strong origin band. For the K+center dot DMB Rb+center dot DMB and Cs+center dot DMB complexes the origin band is very weak and low frequency progressions are much more extensive than that of the Li+ ion. In the case of the Na+center dot DMB comple...

  15. Coprecipitation of rare earths in systems of three heterovalent ions with sulfates of alkali and alkaline-earth metals

    International Nuclear Information System (INIS)

    Bobrik, V.M.

    1977-01-01

    Co-precipitation of rare earth elements (REE) in milligram amounts (3x10 -3 -3x10 -1 M) with alkali earth (AEE) sulfates in presence of alkali metal ions has been studied, the AEE:REE ratios between the co-precipitator and a REE (up to 50:1) the latter can be co-precipitated quantitatively in presence of corresponding alkali metals linked with the AEE in the Periodic table by a diagonal, i.e. in presence of sodium in co-precipitation with calcium sulfate, potassium with strontium sulfate and rubidium with barium sulfate. Co-precipitation with sulfates of sodium and calcium occurs at temperatures above 85 deg C and presumably involves calcium semihydrate. In presence of an alkali metal REE co-precipitation with AEE becomes isomorphic, i.e. at different AEE:REE ratios the co-precipitation coefficient remains constant. In presence of corresponding alkali metals the decrease in effectiveness of co-precipitation with AEE in the La-Lu series is more pronounced

  16. A study on optical properties of poly (ethylene oxide) based polymer electrolyte with different alkali metal iodides

    Science.gov (United States)

    Rao, B. Narasimha; Suvarna, R. Padma

    2016-05-01

    Polymer electrolytes were prepared by adding poly (ethylene glycol) dimethyl ether (PEGDME), TiO2 (nano filler), different alkali metal iodide salts RI (R+=Li+, Na+, K+, Rb+, Cs+) and I2 into Acetonitrile gelated with Poly (ethylene oxide) (PEO). Optical properties of poly (ethylene oxide) based polymer electrolytes were studied by FTIR, UV-Vis spectroscopic techniques. FTIR spectrum reveals that the alkali metal cations were coordinated to ether oxygen of PEO. The optical absorption studies were made in the wavelength range 200-800 nm. It is observed that the optical absorption increases with increase in the radius of alkali metal cation. The optical band gap for allowed direct transitions was evaluated using Urbach-edges method. The optical properties such as optical band gap, refractive index and extinction coefficient were determined. The studied polymer materials are useful for solar cells, super capacitors, fuel cells, gas sensors etc.

  17. New bonding configuration on Si(111) and Ge(111) surfaces induced by the adsorption of alkali metals

    DEFF Research Database (Denmark)

    Lottermoser, L.; Landemark, E.; Smilgies, D.M.

    1998-01-01

    The structure of the (3×1) reconstructions of the Si(111) and Ge(111) surfaces induced by adsorption of alkali metals has been determined on the basis of surface x-ray diffraction and low-energy electron diffraction measurements and density functional theory. The (3×1) surface results primarily f...... from the substrate reconstruction and shows a new bonding configuration consisting of consecutive fivefold and sixfold Si (Ge) rings in 〈11̅ 0〉 projection separated by channels containing the alkali metal atoms. © 1998 The American Physical Society......The structure of the (3×1) reconstructions of the Si(111) and Ge(111) surfaces induced by adsorption of alkali metals has been determined on the basis of surface x-ray diffraction and low-energy electron diffraction measurements and density functional theory. The (3×1) surface results primarily...

  18. One-step synthesis of a singly bridged biscalix[6]arene and evaluation of its alkali metal recognition properties

    Directory of Open Access Journals (Sweden)

    Abha Naveen Kumar

    2017-10-01

    Full Text Available This article describes one-step synthesis of a singly bridged biscalix[6]arene ( 2 and evaluation of its recognition properties towards alkali metal ions for the first time. Synthesis of 2 was accomplished through coupling of two 4-tert-butylcalix[6]arene units with one molecule of diethyleneglycol ditosylate. Both base and linker were found to play a role in the outcome of coupling reaction for the simple and efficient synthesis of 2 . Complexation ability of 2 was studied by liquid-liquid extraction using alkali metal (Na +, K +, Cs + picrates. Carrier activity of 2 towards the facilitated transport of alkali metal ions across a bulk liquid membrane was also studied and the transport behaviour was mechanistically explained. The predominant role of an ion exchange action mechanism in the transport process was observed.

  19. Metal-mediated aminocatalysis provides mild conditions: Enantioselective Michael addition mediated by primary amino catalysts and alkali-metal ions

    Directory of Open Access Journals (Sweden)

    Matthias Leven

    2013-01-01

    Full Text Available Four catalysts based on new amides of chiral 1,2-diamines and 2-sulfobenzoic acid have been developed. The alkali-metal salts of these betaine-like amides are able to form imines with enones, which are activated by Lewis acid interaction for nucleophilic attack by 4-hydroxycoumarin. The addition of 4-hydroxycoumarin to enones gives ee’s up to 83% and almost quantitative yields in many cases. This novel type of catalysis provides an effective alternative to conventional primary amino catalysis were strong acid additives are essential components.

  20. Insight from first principles into the stability and magnetism of alkali-metal superoxide nanoclusters

    Science.gov (United States)

    Arcelus, Oier; Suaud, Nicolas; Katcho, Nebil A.; Carrasco, Javier

    2017-05-01

    Alkali-metal superoxides are gaining increasing interest as 2p magnetic materials for information and energy storage. Despite significant research efforts on bulk materials, gaps in our knowledge of the electronic and magnetic properties at the nanoscale still remain. Here, we focused on the role that structural details play in determining stability, electronic structure, and magnetic couplings of (MO2)n (M = Li, Na, and K, with n = 2-8) clusters. Using first-principles density functional theory based on the Perdew-Burke-Ernzerhof and Heyd-Scuseria-Ernzerhof functionals, we examined the effect of atomic structure on the relative stability of different polymorphs within each investigated cluster size. We found that small clusters prefer to form planar-ring structures, whereas non-planar geometries become more stable when increasing the cluster size. However, the crossover point depends on the nature of the alkali metal. Our analysis revealed that electrostatic interactions govern the highly ionic M-O2 bonding and ultimately control the relative stability between 2-D and 3-D geometries. In addition, we analyzed the weak magnetic couplings between superoxide molecules in (NaO2)4 clusters comparing model Hamiltonian methods based on Wannier function projections onto πg states with wave function-based multi-reference calculations.

  1. Alkali metal control over N-N cleavage in iron complexes.

    Science.gov (United States)

    Grubel, Katarzyna; Brennessel, William W; Mercado, Brandon Q; Holland, Patrick L

    2014-12-03

    Though N2 cleavage on K-promoted Fe surfaces is important in the large-scale Haber-Bosch process, there is still ambiguity about the number of Fe atoms involved during the N-N cleaving step and the interactions responsible for the promoting ability of K. This work explores a molecular Fe system for N2 reduction, particularly focusing on the differences in the results obtained using different alkali metals as reductants (Na, K, Rb, Cs). The products of these reactions feature new types of Fe-N2 and Fe-nitride cores. Surprisingly, adding more equivalents of reductant to the system gives a product in which the N-N bond is not cleaved, indicating that the reducing power is not the most important factor that determines the extent of N2 activation. On the other hand, the results suggest that the size of the alkali metal cation can control the number of Fe atoms that can approach N2, which in turn controls the ability to achieve N2 cleavage. The accumulated results indicate that cleaving the triple N-N bond to nitrides is facilitated by simultaneous approach of least three low-valent Fe atoms to a single molecule of N2.

  2. 3718-F Alkali Metal Treatment and Storage Facility Closure Plan. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    None

    1992-11-01

    The Hanford Site, located northwest of the city of Richland, Washington, houses reactors, chemical-separation systems, and related facilities used for the production of special nuclear materials, as well as for activities associated with nuclear energy development. The 300 Area of the Hanford Site contains reactor fuel manufacturing facilities and several research and development laboratories. The 3718-F Alkali Metal Treatment and Storage Facility (3718-F Facility), located in the 300 Area, was used to store and treat alkali metal wastes. Therefore, it is subject to the regulatory requirements for the storage and treatment of dangerous wastes. Closure will be conducted pursuant to the requirements of the Washington Administrative Code (WAC) 173-303-610 (Ecology 1989) and 40 CFR 270.1. Closure also will satisfy the thermal treatment facility closure requirements of 40 CFR 265.381. This closure plan presents a description of the 3718-F Facility, the history of wastes managed, and the approach that will be followed to close the facility. Only hazardous constituents derived from 3718-F Facility operations will be addressed.

  3. Structure factor of liquid alkali metals using a classical-plasma reference system

    International Nuclear Information System (INIS)

    Pastore, G.; Tosi, M.P.

    1983-11-01

    The paper presents calculations of the liquid structure factor of the alkali metals near freezing, starting from the classical plasma of bare ions as reference liquid. The indirect ion-ion interaction arising from electronic screening is treated by an optimized random phase approximation (ORPA), imposing physical requirements as in the original ORPA scheme developed by Weeks, Chandler and Andersen for liquids with strongly repulsive core potentials. A comparison of the results with computer simulation data for a model of liquid rubidium shows that the present approach overcomes the well-known difficulties met in applying to these metals the standard ORPA based on a reference liquid of neutral hard spheres. The optimization scheme is also shown to be equivalent to a reduction of the range of the indirect interaction in momentum space, as proposed empirically in earlier work. Comparison with experiment for the other alkalis shows that a good overall representation of the data can be obtained for sodium, potassium and cesium, but not for lithium, when one uses a very simple form of the electron-ion potential adjusted to the liquid compressibility. The small-angle scattering region is finally examined more carefully in the light of recent data of Waseda, with a view to possible refinements of the pseudopotential model. (author)

  4. The role of oxygen in porous molybdenum electrodes for the alkali metal thermoelectric converter

    International Nuclear Information System (INIS)

    Williams, R.M.; Nagasubramanian, G.; Khanna, S.K.; Bankston, C.P.; Thakoor, A.P.; Cole, T.

    1986-01-01

    The alkali metal thermoelectric converter is a direct energy conversion device, utilizing a high alkali metal activity gradient to generate electrical power. Its operation is based on the unique ion conductive properties of beta''-alumina solid electrolyte. The major barrier to application of this device is identification of an electrode which can maintain optimum power densities for operation times of >10,000h. Thin, porous molybdenum electrodes have shown the best performance characteristics, but show a variety of time dependent phenomena, including eventual degradation to power densities 3-5 times lower than initial values. Several Na-Mo-O compounds, including Na/sub 2/MoO/sub 4/ and Na/sub 2/Mo/sub 3/O/sub 6/, are formed during AMTEC operation. These compounds may be responsible for enhanced Na transport through Mo electrodes via sodium ion conduction, and eventual performance degradation due to their volatilization and decomposition. No decomposition of beta''-alumina has been observed under simulated AMTEC operating conditions up to 1373 K. In this paper, we present a model for chemical reactions occurring in porous molybdenum electrodes. The model is based on thermochemical and kinetic data, known sodium-molybdenum-oxygen chemistry, x-ray diffraction analysis of molybdenum and molybdenum oxide electrodes, and the electrochemical behavior of the cell

  5. Challenges and Prospect of Non-aqueous Non-alkali (NANA) Metal-Air Batteries.

    Science.gov (United States)

    Gelman, Danny; Shvartsev, Boris; Ein-Eli, Yair

    2016-12-01

    Non-aqueous non-alkali (NANA) metal-air battery technologies promise to provide electrochemical energy storage with the highest specific energy density. Metal-air battery technology is particularly advantageous being implemented in long-range electric vehicles. Up to now, almost all the efforts in the field are focused on Li-air cells, but other NANA metal-air battery technologies emerge. The major concern, which the research community should be dealing with, is the limited and rather poor rechargeability of these systems. The challenges we are covering in this review are related to the initial limited discharge capacities and cell performances. By comprehensively reviewing the studies conducted so far, we show that the implementation of advanced materials is a promising approach to increase metal-air performance and, particularly, metal surface activation as a prime achievement leading to respectful discharge currents. In this review, we address the most critical areas that need careful research attention in order to achieve progress in the understanding of the physical and electrochemical processes in non-aqueous electrolytes applied in beyond lithium and zinc air generation of metal-air battery systems.

  6. First-principles study of the alkali earth metal atoms adsorption on graphene

    Science.gov (United States)

    Sun, Minglei; Tang, Wencheng; Ren, Qingqiang; Wang, Sake; JinYu; Du, Yanhui; Zhang, Yajun

    2015-11-01

    Geometries, electronic structures, and magnetic properties for alkali earth metal atoms absorbed graphene have been studied by first-principle calculations. For Be and Mg atoms, the interactions between the adatom and graphene are weak van der Waals interactions. In comparison, Ca, Sr and Ba atoms adsorption on graphene exhibits strong ionic bonding with graphene. We found that these atoms bond to graphene at the hollow site with a significant binding energy and large electron transfer. It is intriguing that these adatoms may induce important changes in both the electronic and magnetic properties of graphene. Semimetal graphene becomes metallic and magnetic due to n-type doping. Detailed analysis shows that the s orbitals of these adatoms should be responsible for the arising of the magnetic moment. We believe that our results are suitable for experimental exploration and useful for graphene-based nanoelectronic and data storage.

  7. Resonance Raman spectra of metal halide vapor complexes

    International Nuclear Information System (INIS)

    Paptheodorou, G.N.

    1978-01-01

    Resonance Raman spectra of complex vapor phase compounds formed by reacting ''acidic'' gases (A 2 X 6 = Al 2 Cl 6 , Al 2 Br 6 , In 2 Cl 6 ) with metal halides have been measured. Spectra obtained from equilibrium vapor mixtures of A 2 X 6 over solid MX 2 (= PdCl 2 , PdBr 2 , CuCl 2 , CoBr 2 , TiCl 2 , FeCl 2 , NiCl 2 , PtCl 2 ) were a superposition of the A 2 X 6 -AX 3 bands and in few cases of new resonance-enhanced polarized bands due to MA 2 X 8 and/or MAX 5 complexes. At temperatures above 800 0 K, characteristic bands due to MX 2 (g) (M = Fe, Co, Ni, Cu, Zn) and M 2 X 4 (g) (M = Cu) were observed. The predominant features of the PdAl 2 Cl 8 , CuAl 2 Cl 8 , and PdAl 2 Br 6 spectra were three high-intensity, polarized bands which were attributed to the vibrational modes of the complex coupled to the electronic state of the central atom. The spectra of CuAlCl 5 (g), CuInCl 5 (g) and Cu 2 Cl 4 (g) species showed resonance enhancement of selective fundamentals which were attributed to vibrational modes of trigonally coordinated Cu(II). Resonance Raman spectra of U 2 Cl 10 (g) and UCl 5 .AlCl 3 (g) were characterized by the presence of a strong band attributed to the U-Cl/sub t/ stretching frequency. Raman band intensity measurements were carried out for the iron(III) chloride vapors and for the vapor complexes of CuAl 2 Cl 8 , CuInCl 5 and UCl 5 .AlCl 3 using different laser powers and frequencies. The measurements suggested increasing spectroscopic temperatures and decomposition of the vapor complexes. The data are discussed in terms of the distribution of vibrational modes and the structure of the vapor species. 22 figs

  8. Chemical vapor deposition of refractory metals and ceramics III

    International Nuclear Information System (INIS)

    Gallois, B.M.; Lee, W.Y.; Pickering, M.A.

    1995-01-01

    The papers contained in this volume were originally presented at Symposium K on Chemical Vapor Deposition of Refractory Metals and Ceramics III, held at the Fall Meeting of the Materials Research Society in Boston, Massachusetts, on November 28--30, 1994. This symposium was sponsored by Morton International Inc., Advanced Materials, and by The Department of Energy-Oak Ridge National Laboratory. The purpose of this symposium was to exchange scientific information on the chemical vapor deposition (CVD) of metallic and ceramic materials. CVD technology is receiving much interest in the scientific community, in particular, to synthesize new materials with tailored chemical composition and physical properties that offer multiple functionality. Multiphase or multilayered films, functionally graded materials (FGMs), ''smart'' material structures and nanocomposites are some examples of new classes of materials being produced via CVD. As rapid progress is being made in many interdisciplinary research areas, this symposium is intended to provide a forum for reporting new scientific results and addressing technological issues relevant to CVD materials and processes. Thirty four papers have been processed separately for inclusion on the data base

  9. Lanthanide Single-Molecule Magnets Framed by Alkali Metals & Magnetic and Spectroscopic Studies of 3d Transition Metal Complexes

    DEFF Research Database (Denmark)

    Konstantatos, Andreas

    This dissertation presents the results of our work on the synthesis and structural characterization of several families of coordination complexes as well as their study with regard to their magnetic properties. Chapter 1 provides a brief introduction in the field and theory of single-molecule mag......This dissertation presents the results of our work on the synthesis and structural characterization of several families of coordination complexes as well as their study with regard to their magnetic properties. Chapter 1 provides a brief introduction in the field and theory of single......-molecule magnets (SMMs). Starting from the archetype SMM Mn12 we present the details of the mechanisms governing the relaxation of the magnetization of these systems. In Chapter 2 we present our work on the coordination chemistry of lanthanides with a new Schiff-base ligand, H3L [(E)-3-((2-hydroxyphenyl......)imino)- methyl)benzene-1,2-diol]. Using this ligand, we were able to synthesize four different families of lanthanide complexes framed by alkali metals. Throughout the chapter we demonstrate how we can exploit the presence of the coordinated alkali metal ions in order to induce changes to the structure...

  10. Alkali metal complexes of 6-methyl-2-pyridone: simple formulae, but not so simple structures.

    Science.gov (United States)

    Clegg, William; Tooke, Duncan M

    2013-12-01

    Reaction of 6-methyl-2-pyridone (Hmhp) with Na or K metal, or with Rb or Cs 2-ethylhexoxide, in an appropriate single or mixed solvent, yields a series of solvated polymeric complexes with the empirical formulae M(mhp)(H2O)2 [(1), M = Na; (2), M = K], M(mhp)(H2O) [(3), M = Rb; (4), M = Cs] and Cs(mhp)(ROH) [(5), R = Me; (6), R = Et]. All of the products have been crystallographically characterized and show sheet polymeric structures, except for a double-chain structure for (2). In all of the structures, mhp(-) and solvent molecules function as bridging ligands; two metal ions are bridged (μ2) by each solvent molecule in (1), (5) and (6), while (2) contains both μ2 and μ3 triple bridges, and (3) and (4) display highly unusual μ4 quadruple bridging of metal ions by water molecules. The pyridonate O atom bridges two or three metal ions in each case. Nitrogen is also involved in coordination to the heavier metals; it bonds to a single ion in (3) and (4), but has an almost unprecedented bridging role in (5) and (6). As a result of the extensive bridging by ligands, coordination numbers between 6 and 8 are achieved for the metal ions. In each structure, all solvent OH groups form hydrogen bonds to pyridonate O and, in some cases, N atoms. With one exception, these are the first reported pyridonate complexes of the alkali metals Na-Cs that do not also include transition metals.

  11. Residual metallic contamination of transferred chemical vapor deposited graphene.

    Science.gov (United States)

    Lupina, Grzegorz; Kitzmann, Julia; Costina, Ioan; Lukosius, Mindaugas; Wenger, Christian; Wolff, Andre; Vaziri, Sam; Östling, Mikael; Pasternak, Iwona; Krajewska, Aleksandra; Strupinski, Wlodek; Kataria, Satender; Gahoi, Amit; Lemme, Max C; Ruhl, Guenther; Zoth, Guenther; Luxenhofer, Oliver; Mehr, Wolfgang

    2015-05-26

    Integration of graphene with Si microelectronics is very appealing by offering a potentially broad range of new functionalities. New materials to be integrated with the Si platform must conform to stringent purity standards. Here, we investigate graphene layers grown on copper foils by chemical vapor deposition and transferred to silicon wafers by wet etching and electrochemical delamination methods with respect to residual submonolayer metallic contaminations. Regardless of the transfer method and associated cleaning scheme, time-of-flight secondary ion mass spectrometry and total reflection X-ray fluorescence measurements indicate that the graphene sheets are contaminated with residual metals (copper, iron) with a concentration exceeding 10(13) atoms/cm(2). These metal impurities appear to be partially mobile upon thermal treatment, as shown by depth profiling and reduction of the minority charge carrier diffusion length in the silicon substrate. As residual metallic impurities can significantly alter electronic and electrochemical properties of graphene and can severely impede the process of integration with silicon microelectronics, these results reveal that further progress in synthesis, handling, and cleaning of graphene is required to advance electronic and optoelectronic applications.

  12. Synergetic Influence of Alkali-Metal and Lone-Pair Cations on Frameworks of Tellurites.

    Science.gov (United States)

    Chen, Yi-Gang; Yang, Nan; Yao, Xiao-Ni; Li, Cheng-Bo; Guo, Yao; Zhang, Xian-Ming

    2018-04-11

    Four new tellurites were hydrothermally synthesized by the adjustment of different alkali-metal ions, and all of the compounds demonstrate 2D layer structures. Rb 2 Te 4 O 9 ·2H 2 O in centrosymmetric space group Pccn features a new [Te 4 O 9 ] ∞ 2- anion sheet consisting of rare [Te 8 O 22 ] 12- groups. RbNaTe 8 O 14 (OH) 6 ·8H 2 O in CS space group P1̅ exhibits a [Te 4 O 9 ] ∞ 2- anion layer by linkage of the TeO 3 and TeO 4 units. NaPb 4 Te 4 O 12 F located in CS space group P4/ n displays an unusual [PbTeO 3 ] ∞ neutral layer made up of PbO 3 and TeO 3 trigonal pyramids. RbK 3 Te 8 O 18 ·5H 2 O lying in noncentrosymmetric (NCS) space group Cc shows a [Te 4 O 9 ] ∞ 2- anion layer composed of the TeO 3 and TeO 4 units; its second-harmonic-generation response is about 0.2 times that of KH 2 PO 4 ; structure analysis and local dipole moment calculation verify that the weak polarization mostly from the [Te 4 O 9 ] ∞ 2- layer results from the inverse arrangement of TeO n units, and further theoretical calculation confirms that TeO n groups dominate the band gap of RbK 3 Te 8 O 18 ·5H 2 O and optical properties. Meanwhile, systematic analyses of a series of metal tellurites reveal that the alkali-metal cations exert a considerable impact on polarization of the crystal structures, which puts forward a feasible idea about the design of new NCS materials.

  13. Semiempirical calculation of van der Waals coefficients for alkali-metal and alkaline-earth-metal atoms

    International Nuclear Information System (INIS)

    Mitroy, J.; Bromley, M.W.J.

    2003-01-01

    The van der Waals coefficients, C 6 , C 8 , and C 10 for the alkali-metal (Li, Na, K, and Rb) and alkaline-earth-metal (Be, Mg, Ca, and Sr) atoms are estimated by a combination of ab initio and semiempirical methods. Polarizabilities and atom-wall coefficients are given as a diagnostic check, and the lowest order nonadiabatic dispersion coefficient, D 8 and the three-body coefficient, C 9 are also presented. The dispersion coefficients are in agreement with the available relativistic many-body perturbation theory calculations. The contribution from the core was included by using constrained sum rules involving the core polarizability and Hartree-Fock expectation values to estimate the f-value distribution

  14. Alkali Metal Cation Affinities of Anionic Main Group-Element Hydrides Across the Periodic Table.

    Science.gov (United States)

    Boughlala, Zakaria; Fonseca Guerra, Célia; Bickelhaupt, F Matthias

    2017-10-05

    We have carried out an extensive exploration of gas-phase alkali metal cation affinities (AMCA) of archetypal anionic bases across the periodic system using relativistic density functional theory at ZORA-BP86/QZ4P//ZORA-BP86/TZ2P. AMCA values of all bases were computed for the lithium, sodium, potassium, rubidium and cesium cations and compared with the corresponding proton affinities (PA). One purpose of this work is to provide an intrinsically consistent set of values of the 298 K AMCAs of all anionic (XH n-1 - ) constituted by main group-element hydrides of groups 14-17 along the periods 2-6. In particular, we wish to establish the trend in affinity for a cation as the latter varies from proton to, and along, the alkali cations. Our main purpose is to understand these trends in terms of the underlying bonding mechanism using Kohn-Sham molecular orbital theory together with a quantitative bond energy decomposition analyses (EDA). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. The role of alkali metal cations in the stabilization of guanine quadruplexes: why K(+) is the best.

    Science.gov (United States)

    Zaccaria, F; Paragi, G; Fonseca Guerra, C

    2016-08-21

    The alkali metal ion affinity of guanine quadruplexes has been studied using dispersion-corrected density functional theory (DFT-D). We have done computational investigations in aqueous solution that mimics artificial supramolecular conditions where guanine bases assemble into stacked quartets as well as biological environments in which telomeric quadruplexes are formed. In both cases, an alkali metal cation is needed to assist self-assembly. Our quantum chemical computations on these supramolecular systems are able to reproduce the experimental order of affinity of the guanine quadruplexes for the cations Li(+), Na(+), K(+), Rb(+), and Cs(+). The strongest binding is computed between the potassium cation and the quadruplex as it occurs in nature. The desolvation and the size of alkali metal cations are thought to be responsible for the order of affinity. Until now, the relative importance of these two factors has remained unclear and debated. By assessing the quantum chemical 'size' of the cation, determining the amount of deformation of the quadruplex needed to accommodate the cation and through the energy decomposition analysis (EDA) of the interaction energy between the cation and the guanines, we reveal that the desolvation and size of the alkali metal cation are both almost equally responsible for the order of affinity.

  16. Alkali metal compatibility testing of candidate heater head materials for a Stirling engine heat transport system

    Science.gov (United States)

    Noble, Jack E.; Hickman, Gary L.; Grobstein, Toni

    1991-01-01

    The authors describe work performed as part of the 25-kWe advanced Stirling conversion system project. Liquid alkali metal compatibility is being assessed in an ongoing test program to evaluate candidate heater head materials and fabrication processes at the temperatures and operating conditions required for Stirling engines. Specific materials under evaluation are alloy 713LC, alloy 713LC coated with nickel aluminide, and Udimet 720, each in combination with Waspaloy. The tests were run at a constant 700 C. A eutectic alloy of sodium and potassium (NaK) was the working fluid. Titanium sheet in the system was shown to be an effective oxygen getter. Metallographic and microchemical examination of material surfaces, joints, and their interfaces revealed little or no corrosion after 1000 h. Tests are in progress, with up to 10,000 h exposure.

  17. Matrix isolation studies and DFT calculations on molecular alkali metal bromates.

    Science.gov (United States)

    Ogden, J Steven; Graham, John T; Joy, Jon T; Ferrante, Francesco

    2009-01-28

    DFT and MP2 calculations have been carried out on a series of molecular alkali metal bromates MBrO3 (M = Na, K, Rb, Cs), and the results compared with matrix isolation IR studies on the vaporisation of the solid salts. For M = Na, K or Rb, no ternary molecular species were detected in the low temperature matrix, but vaporisation of solid caesium bromate at 730 K resulted in the formation of molecular CsBrO3, which was identified as having a C3v structure involving tridentate coordination. Additionally, the DFT and MP2 calculations provide estimates of the molecular parameters for all four MBrO3 species, and for the related MXO3 species CsClO3 and CsIO3. The proven stability of MBrO3 molecules may have a bearing on the atmospheric chemistry of bromine oxo-species.

  18. Electrical resistivities and solvation enthalpies for solutions of salts in liquid alkali metals

    International Nuclear Information System (INIS)

    Hubberstey, P.; Dadd, A.T.

    1982-01-01

    An empirical correlation is shown to exist between the resistivity coefficients drho/dc for solutes in liquid alkali metals and the corresponding solvation enthalpies Usub(solvn) of the neutral gaseous solute species. Qualitative arguments based on an electrostatic solvation model in which the negative solute atom is surrounded by a solvation sphere of positive solvent ion cores are used to show that both parameters are dependent on the charge density of the solute atom and hence on the extent of charge transfer from solvent to solute. Thus as the charge density of the solute increases, the solvation enthalpy increases regularly and the resistivity coefficients pass through a maximum to give the observed approximately parabolic drho/dc versus Usub(solvn) relationship. (Auth.)

  19. Separation of hafnium from zirconium in their tetrachloride solution in molten alkali metal chlorides

    International Nuclear Information System (INIS)

    Salyulev, A.B.; Kudyakov, V.Ya.; Smirnov, M.V.; Moskalenko, N.I.

    1984-01-01

    The coefficient of HfCl 4 and ZrCl 4 separation in the process of vapour sublimation from their solutions in molten NaCl, KCl, CsCl, NaCl-KCl and NaCl-CsCl equimolar mixtures is found to vary in the series from approximately 1.10 to approximately 1.22 and practically not to depend on the temperature (in the 600-910 deg) range and concentration (2-25 mol.% ZrCl 4 +HfCl 4 ). HfCl 4 and ZrCl 4 are shown to form almost perfect solutions with each other, which in their turn form imperfect solutions with molten alkali metal chlorides, with the strength of hafnium complex chloride anions increasing higher than that of zirconium in the series from NaCl to CsCl

  20. Separation of hafnium from zirconium in their tetrachloride solution in molten alkali metal chlorides

    Energy Technology Data Exchange (ETDEWEB)

    Salyulev, A.B.; Kudyakov, V.Ya.; Smirnov, M.V.; Moskalenko, N.I. (AN SSSR, Sverdlovsk. Inst. Ehlektrokhimii)

    1984-08-01

    The coefficient of HfCl/sub 4/ and ZrCl/sub 4/ separation in the process of vapour sublimation from their solutions in molten NaCl, KCl, CsCl, NaCl-KCl and NaCl-CsCl equimolar mixtures is found to vary in the series from approximately 1.10 to approximately 1.22 and practically not to depend on the temperature (in the 600-910 deg) range and concentration (2-25 mol.% ZrCl/sub 4/+HfCl/sub 4/). HfCl/sub 4/ and ZrCl/sub 4/ are shown to form almost perfect solutions with each other, which in their turn form imperfect solutions with molten alkali metal chlorides, with the strength of hafnium complex chloride anions increasing higher than that of zirconium in the series from NaCl to CsCl.

  1. Rydberg States of Alkali Metal Atoms on Superfluid Helium Droplets - Theoretical Considerations

    Science.gov (United States)

    Pototschnig, Johann V.; Lackner, Florian; Hauser, Andreas W.; Ernst, Wolfgang E.

    2017-06-01

    The bound states of electrons on the surface of superfluid helium have been a research topic for several decades. One of the first systems treated was an electron bound to an ionized helium cluster. Here, a similar system is considered, which consists of a helium droplet with an ionized dopant inside and an orbiting electron on the outside. In our theoretical investigation we select alkali metal atoms (AK) as central ions, stimulated by recent experimental studies of Rydberg states for Na, Rb, and Cs attached to superfluid helium nanodroplets. Experimental spectra , obtained by electronic excitation and subsequent ionization, showed blueshifts for low lying electronic states and redshifts for Rydberg states. In our theoretical treatment the diatomic AK^+-He potential energy curves are first computed with ab initio methods. These potentials are then used to calculate the solvation energy of the ion in a helium droplet as a function of the number of atoms. Additional potential terms, derived from the obtained helium density distribution, are added to the undisturbed atomic pseudopotential in order to simulate a 'modified' potential felt by the outermost electron. This allows us to compute a new set of eigenstates and eigenenergies, which we compare to the experimentally observed energy shifts for highly excited alkali metal atoms on helium nanodroplets. A. Golov and S. Sekatskii, Physica B, 1994, 194, 555-556 E. Loginov, C. Callegari, F. Ancilotto, and M. Drabbels, J. Phys. Chem. A, 2011, 115, 6779-6788 F. Lackner, G. Krois, M. Koch, and W. E. Ernst, J. Phys. Chem. Lett., 2012, 3, 1404-1408 F. Lackner, G. Krois, M. Theisen, M. Koch, and W. E. Ernst, Phys. Chem. Chem. Phys., 2011, 13, 18781-18788

  2. Thermal behavior of heat-pipe-assisted alkali-metal thermoelectric converters

    Science.gov (United States)

    Lee, Ji-Su; Lee, Wook-Hyun; Chi, Ri-Guang; Chung, Won-Sik; Lee, Kye-Bock; Rhi, Seok-Ho; Jeong, Seon-Yong; Park, Jong-Chan

    2017-11-01

    The alkali-metal thermal-to-electric converter (AMTEC) changes thermal energy directly into electrical energy using alkali metals, such as sodium and potassium, as the working fluid. The AMTEC system primarily consists of beta-alumina solid electrolyte (BASE) tubes, low and high-pressure chambers, an evaporator, and a condenser and work through continuous sodium circulation, similar to conventional heat pipes. When the sodium ions pass through the BASE tubes with ion conductivity, this ion transfer generates electricity. The efficiency of the AMTEC directly depends on the temperature difference between the top and bottom of the system. The optimum design of components of the AMTEC, including the condenser, evaporator, BASE tubes, and artery wick, can improve power output and efficiency. Here, a radiation shield was installed in the low-pressure chamber of the AMTEC and was investigated experimentally and numerically to determine an optimum design for preventing radiation heat loss through the condenser and the wall of AMTEC container. A computational fluid dynamics (CFD) simulation was carried out to decide the optimum size of the low-pressure chamber. The most suitable height and diameter of the chamber were 270 mm and 180 mm, respectively, with eight BASE tubes, which were 150 mm high, 25 mm in diameter, and 105 mm in concentric diameter. Increasing the temperature ratio ( T Cond /T B ) led to high power output. The minimum dimensionless value (0.4611) for temperature ( T Cond /T B ) appeared when the radiation shield was made of 500-mesh nickel. Simulation results for the best position and shape for the radiation shield, revealed that maximum power was generated when a stainless steel shield was installed in between the BASE tubes and condenser.

  3. Hydrogen generation using silicon nanoparticles and their mixtures with alkali metal hydrides

    Science.gov (United States)

    Patki, Gauri Dilip

    mole of Si. We compare our silicon nanoparticles (˜10nm diameter) with commercial silicon nanopowder (<100nm diameter) and ball-milled silicon powder (325 mesh). The increase in rate upon decreasing the particle size to 10 nm was even greater than would be expected based upon the increase in surface area. While specific surface area increased by a factor of 6 in going from <100 nm to ˜10 nm particles, the hydrogen production rate increased by a factor of 150. However, in all cases, silicon requires a base (e.g. NaOH, KOH, hydrazine) to catalyze its reaction with water. Metal hydrides are also promising hydrogen storage materials. The optimum metal hydride would possess high hydrogen storage density at moderate temperature and pressure, release hydrogen safely and controllably, and be stable in air. Alkali metal hydrides have high hydrogen storage density, but exhibit high uncontrollable reactivity with water. In an attempt to control this explosive nature while maintaining high storage capacity, we mixed our silicon nanoparticles with the hydrides. This has dual benefits: (1) the hydride- water reaction produces the alkali hydroxide needed for base-catalyzed silicon oxidation, and (2) dilution with 10nm coating by, the silicon may temper the reactivity of the hydride, making the process more controllable. Initially, we analyzed hydrolysis of pure alkali metal hydrides and alkaline earth metal hydrides. Lithium hydride has particularly high hydrogen gravimetric density, along with faster reaction kinetics than sodium hydride or magnesium hydride. On analysis of hydrogen production we found higher hydrogen yield from the silicon nanoparticle—metal hydride mixture than from pure hydride hydrolysis. The silicon-hydride mixtures using our 10nm silicon nanoparticles produced high hydrogen yield, exceeding the theoretical yield. Some evidence of slowing of the hydride reaction rate upon addition of silicon nanoparticles was observed.

  4. Temperature-dependent transport properties of graphene decorated by alkali metal adatoms (Li, K)

    Science.gov (United States)

    Woo, S.; Hemmatiyan, S.; Morrison, T. D.; Rathnayaka, K. D. D.; Lyuksyutov, I. F.; Naugle, D. G.

    2017-12-01

    We report the electrical transport properties of graphene for dilute alkali metal decoration (n ˜ 2 × 1012 cm-2) at cryogenic temperatures. Upon deposition of K and Li atoms at T = 20 K, graphene devices are doped with electrons, and the charge carrier mobility is decreased. As temperature is increased, the number of electrons donated to the graphene and the number of charged scatterers are reduced, and the mobility of the metal decorated graphene is increased. This differs from the typical temperature-dependent transport in undecorated graphene, where the mobility decreases with increasing temperature. To investigate the kinetic behavior of adatoms on graphene, we estimate the hopping time of the Li and K adatoms on graphene based on the migration barrier in the low concentration regime of the metal adatoms by Density Functional Theory calculations. The calculations reveal that these adatoms are mobile even at cryogenic temperatures and become more mobile with increasing temperature, allowing for cluster formation of adatoms. This indicates that the dominant factor in the electron transport on warming is a cluster formation.

  5. First-principles study of the alkali earth metal atoms adsorption on graphene

    International Nuclear Information System (INIS)

    Sun, Minglei; Tang, Wencheng; Ren, Qingqiang; Wang, Sake; JinYu; Du, Yanhui; Zhang, Yajun

    2015-01-01

    Graphical abstract: - Highlights: • The adsorption of Be and Mg adatoms on graphene is physisorption. • Ca, Sr, and Ba adatoms bond ionically to graphene and the most stable adsorption site for them is hollow site. • The zero band gap semiconductor graphene becomes metallic and magnetic after the adsorption of Ca, Sr, and Ba adatoms. - Abstract: Geometries, electronic structures, and magnetic properties for alkali earth metal atoms absorbed graphene have been studied by first-principle calculations. For Be and Mg atoms, the interactions between the adatom and graphene are weak van der Waals interactions. In comparison, Ca, Sr and Ba atoms adsorption on graphene exhibits strong ionic bonding with graphene. We found that these atoms bond to graphene at the hollow site with a significant binding energy and large electron transfer. It is intriguing that these adatoms may induce important changes in both the electronic and magnetic properties of graphene. Semimetal graphene becomes metallic and magnetic due to n-type doping. Detailed analysis shows that the s orbitals of these adatoms should be responsible for the arising of the magnetic moment. We believe that our results are suitable for experimental exploration and useful for graphene-based nanoelectronic and data storage.

  6. Determination of a various ions such as alkali metals in leaves, stems, roots and seeds of the radish and their distribution

    International Nuclear Information System (INIS)

    Fujino, Osamu; Matsui, Masakazu.

    1995-01-01

    Determination, uptake and distribution of various ions such as alkali metals in three different parts (leaf, stem and root) and seeds of radish (Kaiware daikon) were examined using flame emission spectrometry and ICP-AES. In order to examine the influence of concentration alkali metal ion concentration in the radish culture solution on the uptake and distribution of these metals, the radish was grown at pH 5.6 in solutions containing alkali metal chloride at concentrations ranging from 10 -5 to 10 -1 mol dm -3 . When the radish were grown in culture solution with alkali metal ions of low concentrations (10 -5 and 10 -4 mol dm -3 ), Na, K, Rb and trace Li were detected in leaves, stems and roots while Cs was scarcely detected. However, the contents of Na, K, Li in these organs were the same as those in radish cultivated in pure water. An increase of Rb uptake was observed with an increased Rb concentration. In the case of high concentrations (10 -3 and 10 -2 mol dm -3 ) of alkali metals in culture solution, the all alkali ions uptake of all alkali ions suddenly accelerated. Moreover, at concentrations higher than 0.1 mol dm -3 , the radish germinated poorly and did not completely mature. (author)

  7. Collisional Broadening and Shift of D1 and D2 Spectral Lines in Atomic Alkali Vapor - Noble Gas Systems

    Science.gov (United States)

    2013-03-01

    Knollenberg, 1975; Kielkopf, 1976; Kielkopf and Allard, 1979; Allard, Biraud, and Chevillot, 1988; Ciurylo and Szudy, 1997; Allard, Royer , Kielkopf, and...Impact broadening of alkali lines in brown dwarfs.” European Physics Journal D, 44 (2007): 507-514. Allard, N. F., Royer , A., Kielkopf, J. F

  8. The impact of alkali metal halide electron donor complexes in the photocatalytic degradation of pentachlorophenol

    Energy Technology Data Exchange (ETDEWEB)

    Khuzwayo, Z., E-mail: zack.khuzwayo@up.ac.za; Chirwa, E.M.N

    2017-01-05

    Highlights: • Facilitation of photocatalysis using simple metal-halides as VB hole scavengers. • Recombination prevention by coupled valence and conduction band approaches. • Determination of anions critical levels beyond which process retardation occurs. • Determination of the photocatalytic process rate of reaction kinetics. - Abstract: The performance of photocatalytic oxidation of chemical pollutants is subjected to the presence of anion complexes in natural waters. This study investigated the influence of alkali metal (Na{sup +} (sodium), K{sup +} (potassium)) halides (Cl{sup −} (chloride), Br{sup −} (bromide), F{sup −} (fluoride)) as inorganic ion sources in the photocatalytic degradation of pentachlorophenol (PCP) in batch systems. It was found that the exclusive presence of halides in the absence of an electron acceptor adequately facilitated the photocatalyst process below critical levels of anion populations, where beyond the critical point the process was significantly hindered. Below the determined critical point, the performance in some cases near matches that of the facilitation of the photocatalytic process by exclusive oxygen, acting as an electron scavenger. The coupling of halide ions and oxygenation presented significantly improved photo-oxidation of PCP, this was confirmed by the inclusion of formic acid as a comparative electron donor. The Langmuir-Hinshelwood kinetic expression was used to calculate the performance rate kinetics. The probable impact of the halide anions was discussed with regards to the process of electron hole pair recombination prevention.

  9. Potential-modulated intercalation of alkali cations into metal hexacyanoferrate coated electrodes. 1998 annual progress report

    International Nuclear Information System (INIS)

    Schwartz, D.T.

    1998-01-01

    'This program is studying potential-driven cation intercalation and deintercalation in metal hexacyanoferrate compounds, with the eventual goal of creating materials with high selectivity for cesium separations and long cycle lifetimes. The separation of radiocesium from other benign cations has important implications for the cost of processing a variety of cesium contaminated DOE wasteforms. This report summarizes results after nine months of work. Much of the initial efforts have been directed towards quantitatively characterizing the selectivity of nickel hexacyanoferrate derivatized electrodes for intercalating cesium preferentially over other alkali metal cations. Using energy dispersive xray spectroscopy (ex-situ, but non-destructive) and ICP analysis (ex-situ and destructive), the authors have demonstrated that the nickel hexacyanoferrate lattice has a strong preference for intercalated cesium over sodium. For example, when ions are reversibly loaded into a nickel hexacyanoferrate thin film from a solution containing 0.9999 M Na + and 0.0001 M Cs + , the film intercalates 40% as much Cs + as when loaded from pure 1 M Cs + containing electrolyte (all electrolytes use nitrates as the common anion). The authors have also shown that, contrary to the common assumptions found in the literature, a significant fraction of the thin film is not active initially. A new near infrared laser has been purchased and is being added to the Raman spectroscopy facilities to allow in-situ studies of the intercalation processes.'

  10. Study of complex amalgams containing alkali metals by method of broken thermometric titration

    International Nuclear Information System (INIS)

    Filippova, L.M.; Zebreva, A.I.; Espenbetov, A.A.

    1977-01-01

    Complex potassium-cadmium and sodium-cadmium amalgams containing different amounts of the alkali metal nad cadmium have been studied by thermometric titration with mercury. The experiments have been carried out in argon atmosphere at 25 deg C. As evidenced by the titration of sodium-cadmium amalgams, in the range of concentrations studied (Csub(Na)=0.71-2.95, Csub(Cd)=4.38-6.45 g-at/lHg) no solid phase is formed in them. Potassium-cadmium amalgams where the metals content is no higher than their individual solubility in mercury, display, when being mercury-titrated, negative heat effects due to solid phase formation. An estimation is made of the solid phase composition, its solubility in mercury and the heat of dissolution. The solid phase appearing in complex K-Cd amalgams is likely to contain K and Cd in a ratio 1:1 its conventional solubility product is 5.4 g-at/l Hg, and the heat of dissolution in mercury at 25 deg is -21 +-4 kJ/g-at

  11. Stability of alkali-metal hydrides: effects of n-type doping

    Science.gov (United States)

    Olea Amezcua, Monica Araceli; de La Peña Seaman, Omar; Rivas Silva, Juan Francisco; Heid, Rolf; Bohnen, Klaus-Peter

    Metal hydrides could be considered ideal solid-state hydrogen storage systems, they have light weight and high hydrogen volumetric densities, but the hydrogen desorption process requires excessively high temperatures due to their high stability. Efforts have been performed to improve their dehydrogenation properties, based on the introduction of defects, impurities and doping. We present a systematic study of the n-type (electronic) doping effects on the stability of two alkali-metal hydrides: Na1-xMgxH and Li1-xBexH. These systems have been studied within the framework of density functional perturbation theory, using a mixed-basis pseudopotential method and the self-consistent version of the virtual crystal approximation to model the doping. The full-phonon dispersions are analyzed for several doping content, paying special attention to the crystal stability. It is found a doping content threshold for each system, where they are close to dynamical instabilities, which are related to charge redistribution in interstitial zones. Applying the quasiharmonic approximation, the vibrational free energy, the linear thermal expansion and heat capacities are obtained for both hydrides systems and are analyzed as a function of the doping content. This work is partially supported by the VIEP-BUAP 2016 and CONACYT-México (No.221807) projects.

  12. Special features of the formation of high-conductivity phases of halides of alkali metals at superhigh pressures

    International Nuclear Information System (INIS)

    Babushkin, A.N.; Babushkina, G.V.

    1999-01-01

    The halides of alkali metals are the simplest crystals with the ionic nature of chemical bonds and are used widely as modelling materials in high-pressure physics. As a result of previous theoretical and experimental (optical, structural, electro-physical and shock-waves) investigations it was shown that these materials may be characterised by the overlapping of the valency and conduction bands and by the formation of groups of free charge carriers at pressures of the megabaric level. However, the authors know of no data on the direct investigations of the electrophysical properties of the halides of alkali metals at such high static pressures. The end of this investigation was to examine the temperature dependences of the electrical conductivity and thermal EMF of halides of alkali metals AX (A = Na, K, Rb, Cs, X = Cl, Br, I) in a wide temperature range at pressures from 10 to 50 GPa in order to reveal the general leisure since governing the change of their electronic structures, in particular, the transition to the state with the activation-type or metallic conductivity

  13. Solid State Structures of Alkali Metal Ion Complexes Formed by Low-Molecular-Weight Ligands of Biological Relevance.

    Science.gov (United States)

    Aoki, Katsuyuki; Murayama, Kazutaka; Hu, Ning-Hai

    2016-01-01

    This chapter provides structural data, mainly metal binding sites/modes, observed in crystal structures of alkali metal ion complexes containing low-molecular-weight ligands of biological relevance, mostly obtained from the Cambridge Structural Database (the CSD version 5.35 updated to February 2014). These ligands include (i) amino acids and small peptides, (ii) nucleic acid constituents (excluding quadruplexes and other oligonucleotides), (iii) simple carbohydrates, and (iv) naturally occurring antibiotic ionophores. For some representative complexes of these ligands, some details on the environment of the metal coordination and structural characteristics are described.

  14. Validation of ion chromatography for the determination of transition metal ions along with alkali, alkaline earth metal elements for uranium oxide fuel

    International Nuclear Information System (INIS)

    Kelkar, Anoop; Prakash, Amrit; Afzal, Mohd.; Panakkal, J.P.

    2009-02-01

    The present report describes the use of Ion chromatography (IC) methods with spectrophotometric and direct conductivity detection for the determination of transition metal elements and alkali alkaline earth metal ions in UO 2 pellets. Transmet analytical column and Metrosep- cation 1-2 column were used for the separation of transition metal elements and alkali and alkaline earth metal elements respectively. Oxalic acid and mixture of pyridine 2,6-dicarboxylic acid (PDCA), Na 2 SO 4 and NaCl were used as mobile phase for the separation of transition metal ions and monitored after post - column reaction with 4,2-pyridylazo resorcinol (PAR) at 520nm spectrophotometrically. In the determination of alkali and alkaline earth metal ions the interference of transition metals are removed by complexing them with PDCA. Mixture of tartaric acid and PDCA employed in the separation of alkali and alkaline earth metal ions and monitored on direct conductivity detector. Mobile phase composition was optimised for the base line separation. Calibration plots of Fe 3+ , Cu 2+ , Ni 2+ , Co 2+ , Cd 2+ , Mn 2+ , Li + , Na + , K + , Mg 2+ , Ca 2+ and Sr 2+ were linear over a wide dynamic range with regression coefficient better than 0.999. Detection limit of above ions were between 5-30ppb. To prevent the overloading of the cation exchange column, uranium matrix was removed from UO 2 sample by solvent extraction with 30% TBP - TOPO/CCl 4 . Ten sintered UO2 pellets of same lot were analysed and R.S.D. ±10% was obtained. These methods were validated by analysis of ILCE standards of UO 2 . (author)

  15. Correction: A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide.

    Science.gov (United States)

    Ng, Chee Koon; Wu, Jie; Hor, T S Andy; Luo, He-Kuan

    2016-12-22

    Correction for 'A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide' by Chee Koon Ng et al., Chem. Commun., 2016, 52, 11842-11845.

  16. Poly(vinyl chloride) membrane alkali metal ion-selective electrodes based on crystalline synthetic zeolite of the Faujasite type

    International Nuclear Information System (INIS)

    Aghai, H.; Giahi, M.; Arvand Barmehi, M.

    2002-01-01

    Potentiometric electrodes based on the incorporation of zeolite particle in to poly (vinyl chloride) (pvc) membranes are described. The electrodes characteristics are evaluated regarding the response towards alkali ions. Pvc membranes plasticised with dibutyl phthalate and without lipophilic additives (co-exchanger) were used throughout this study. The electrode exhibits a Nernst ion response over the alkali metal cations concentration a range of 1.0x10 - 4 - 1.0 x 10 1 M with a slop of 57.0 ± 0.9 mV per decade of concentration a working ph range (3.0- 9.0) and a fast response time (≤15 c). The selective coefficients for cesium ion as test species with respect to alkaline earth, ammonium and some heavy metal ions were determined. Zeolite-PVC electrodes were applied to the determination of ionic surfactant

  17. Alkali metals effect on the diffusion mobility of fluorine base of GaF3 and IF3

    International Nuclear Information System (INIS)

    Bakhvalov, S.G.; Livshits, A.I.; Shubin, A.A.; Petrova, E.M.

    2000-01-01

    The structure of fluoride glasses on the basis of GaF 3 and InF 3 is studied. The glass lattice bond, i.e. its uniformity or nonuniformity, was analyzed through introduction of alkali metal (LiF, NaF, RbF, CsF) into the composition of fluoride glasses. The consecutive replacement of a modification by alkali metal fluorides made it possible to establish the nonuniformity of the glass-forming lattice by studying through the NMR 19 F method. It may be confirmed by comparing the fluorine ions dynamic behavior in the glasses, based on the indium and gallium trifluorides, that the glass fluorine subsystem on the In basis is more mobile [ru

  18. ALKALI RESISTANT CATALYST

    DEFF Research Database (Denmark)

    2008-01-01

    of alkali metal and/or alkali-earth compounds which process comprises using a catalyst combined of (i) a formed porous superacidic support, said superacidic support having an Hammett acidity stronger than Ho=-12, and (ii) a metal oxide catalytic component deposited on said superacidic support selected from...

  19. Dipole polarizability of alkali-metal (Na, K, Rb)-alkaline-earth-metal (Ca, Sr) polar molecules: Prospects for alignment

    Science.gov (United States)

    Gopakumar, Geetha; Abe, Minori; Hada, Masahiko; Kajita, Masatoshi

    2014-06-01

    Electronic open-shell ground-state properties of selected alkali-metal-alkaline-earth-metal polar molecules are investigated. We determine potential energy curves of the 2Σ+ ground state at the coupled-cluster singles and doubles with partial triples (CCSD(T)) level of electron correlation. Calculated spectroscopic constants for the isotopes (23Na, 39K, 85Rb)-(40Ca, 88Sr) are compared with available theoretical and experimental results. The variation of the permanent dipole moment (PDM), average dipole polarizability, and polarizability anisotropy with internuclear distance is determined using finite-field perturbation theory at the CCSD(T) level. Owing to moderate PDM (KCa: 1.67 D, RbCa: 1.75 D, KSr: 1.27 D, RbSr: 1.41 D) and large polarizability anisotropy (KCa: 566 a.u., RbCa: 604 a.u., KSr: 574 a.u., RbSr: 615 a.u.), KCa, RbCa, KSr, and RbSr are potential candidates for alignment and orientation in combined intense laser and external static electric fields.

  20. Modeling of time evolution of power and temperature in single-pulse and multi-pulses diode-pumped alkali vapor lasers.

    Science.gov (United States)

    Shen, Binglin; Huang, Jinghua; Xu, Xingqi; Xia, Chunsheng; Pan, Bailiang

    2017-06-12

    A physical model combining rate, power propagation, and transient heat conduction equations for diode-pumped alkali vapor lasers (DPAL) is applied to a pulsed Rb-CH 4 DPAL, which agrees well with the time evolution of laser power and temperature measured by K absorption spectroscopy. The output feature and temperature rise of a multi-pulse DPAL are also calculated in the time domain, showing that if we energize the pump light when the temperature rise decays to 1/2, rather than 1/e of its maximum, we can increase the duty cycle and obtain more output energy. The repetition rate of >100Hz is high enough to achieve QCW (quasi-continuous-wave) laser pulses.

  1. Alkali Metal Ion Complexes with Phosphates, Nucleotides, Amino Acids, and Related Ligands of Biological Relevance. Their Properties in Solution.

    Science.gov (United States)

    Crea, Francesco; De Stefano, Concetta; Foti, Claudia; Lando, Gabriele; Milea, Demetrio; Sammartano, Silvio

    2016-01-01

    Alkali metal ions play very important roles in all biological systems, some of them are essential for life. Their concentration depends on several physiological factors and is very variable. For example, sodium concentrations in human fluids vary from quite low (e.g., 8.2 mmol dm(-3) in mature maternal milk) to high values (0.14 mol dm(-3) in blood plasma). While many data on the concentration of Na(+) and K(+) in various fluids are available, the information on other alkali metal cations is scarce. Since many vital functions depend on the network of interactions occurring in various biofluids, this chapter reviews their complex formation with phosphates, nucleotides, amino acids, and related ligands of biological relevance. Literature data on this topic are quite rare if compared to other cations. Generally, the stability of alkali metal ion complexes of organic and inorganic ligands is rather low (usually log K  Na(+) > K(+) > Rb(+) > Cs(+). For example, for citrate it is: log K ML = 0.88, 0.80, 0.48, 0.38, and 0.13 at 25 °C and infinite dilution. Some considerations are made on the main aspects related to the difficulties in the determination of weak complexes. The importance of the alkali metal ion complexes was also studied in the light of modelling natural fluids and in the use of these cations as probes for different processes. Some empirical relationships are proposed for the dependence of the stability constants of Na(+) complexes on the ligand charge, as well as for correlations among log K values of NaL, KL or LiL species (L = generic ligand).

  2. Research Investigation Directed Toward Extending the Useful Range of the Electromagnetic Spectrum. [atomic spectra and electronic structure of alkali metals

    Science.gov (United States)

    Hartmann, S. R.; Happer, W.

    1974-01-01

    The report discusses completed and proposed research in atomic and molecular physics conducted at the Columbia Radiation Laboratory from July 1972 to June 1973. Central topics described include the atomic spectra and electronic structure of alkali metals and helium, molecular microwave spectroscopy, the resonance physics of photon echoes in some solid state systems (including Raman echoes, superradiance, and two photon absorption), and liquid helium superfluidity.

  3. Amperometric Ion-Selective Electrode for Alkali Metal Cations Based on a Room-Temperature Ionic Liquid Membrane

    Czech Academy of Sciences Publication Activity Database

    Langmaier, Jan; Trojánek, Antonín; Samec, Zdeněk

    2009-01-01

    Roč. 21, 17-18 (2009), s. 1977-1983 ISSN 1040-0397 R&D Projects: GA MŠk ME08098; GA AV ČR IAA400400704 Institutional research plan: CEZ:AV0Z40400503 Keywords : room-temperature ionic liquid * alkali metals * Crown ether * cyclic voltammetry * amperometric ion-selective elkectrode Subject RIV: CG - Electrochemistry Impact factor: 2.630, year: 2009

  4. pH tunability and influence of alkali metal basicity on the plasmonic resonance of silver nanoparticles

    Science.gov (United States)

    Yadav, Vijay D.; Akhil Krishnan, R.; Borade, Lalit; Shirolikar, Seema; Jain, Ratnesh; Dandekar, Prajakta

    2017-07-01

    Localized surface plasmon resonance has been a unique and intriguing feature of silver nanoparticles (AgNPs) that has attracted immense attention. This has led to an array of applications for AgNPs in optics, sensors, plasmonic imaging etc. Although numerous applications have been reported consistently, the importance of buffer and reaction parameters during the synthesis of AgNPs, is still unclear. In the present study, we have demonstrated the influence of parameters like pH, temperature and buffer conditions (0.1 M citrate buffer) on the plasmonic resonance of AgNPs. We found that neutral and basic pH (from alkali metal) provide optimum interaction conditions for nucleation of plasmon resonant AgNPs. Interestingly, this was not observed in the non-alkali metal base (ammonia). Also, when the nanoparticles synthesized from alkali metal base were incorporated in different buffers, it was observed that the nanoparticles dissolved in the acidic buffer and had reduced plasmonic resonance intensity. This, however, was resolved in the basic buffer, increasing the plasmonic resonance intensity and confirming that nucleation of nanoparticles required basic conditions. The above inference has been supported by characterization of AgNPs using UV-Vis spectrophotometer, Fluorimetry analysis, Infrared spectrometer and TEM analysis. The study concluded that the plasmonic resonance of AgNPs occurs due to the interaction of alkali (Na) and transition metal (Ag) salt in basic/neutral conditions, at a specific temperature range, in presence of a capping agent (citric acid), providing a pH tune to the overall system.

  5. Effect of thermal annealing on the redistribution of alkali metals in Cu(In,Ga)Se2 solar cells on glass substrate

    Science.gov (United States)

    Kamikawa, Yukiko; Nishinaga, Jiro; Ishizuka, Shogo; Tayagaki, Takeshi; Guthrey, Harvey; Shibata, Hajime; Matsubara, Koji; Niki, Shigeru

    2018-03-01

    The precise control of alkali-metal concentrations in Cu(In,Ga)Se2 (CIGS) solar cells via post deposition treatment (PDT) has recently attracted attention. When PDT is performed at an elevated temperature, an accompanying annealing effect is expected. Here, we investigate how thermal annealing affects the redistribution of alkali metals in CIGS solar cells on glass substrates and the properties of the solar cells. In addition, we investigate the origin of non-homogeneous alkali-metal depth profiles that are typical of CIGS grown using a three-stage process. In particular, we use secondary-ion mass spectrometry measurements of the ion concentration as a function of distance from the CIGS surface to investigate the impact of thermal annealing on the distribution of alkali metals (Na, Ka, and Rb) and constituent elements (Ga and In) in the CIGS absorbers. We find that the depth profiles of the alkali metals strongly reflect the density of sites that tend to accommodate alkali metals, i.e., vacancies. Annealing at elevated temperature caused a redistribution of the alkali metals. The thermal-diffusion kinetics of alkali metals depends strongly on the species involved. We introduced low flux potassium fluoride (KF) to study a side effect of KF-PDT, i.e., Na removal from CIGS, separately from its predominant effects such as surface modification. When sufficient amounts of Na are supplied from the soda lime glass via annealing at an elevated temperature, the negative effect was not apparent. Conversely, when the Na supply was not sufficient, it caused a deterioration of the photovoltaic properties.

  6. Effect of Thermal Annealing on the Redistribution of Alkali Metals in Cu(In,Ga)Se2 Solar Cells on Glass Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Guthrey, Harvey L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kamikawa, Yukiko [National Institute of Advanced Industrial Science and Technology (AIST); Nishinaga, Jiro [National Institute of Advanced Industrial Science and Technology (AIST); Ishizuka, Shogo [National Institute of Advanced Industrial Science and Technology (AIST); Tayagaki, Takeshi [National Institute of Advanced Industrial Science and Technology (AIST); Shibata, Hajime [National Institute of Advanced Industrial Science and Technology (AIST); Matsubara, Koji [National Institute of Advanced Industrial Science and Technology (AIST); Niki, Shigeru [National Institute of Advanced Industrial Science and Technology (AIST)

    2018-03-02

    The precise control of alkali-metal concentrations in Cu(In,Ga)Se2 (CIGS) solar cells via post deposition treatment (PDT) has recently attracted attention. When PDT is performed at an elevated temperature, an accompanying annealing effect is expected. Here, we investigate how thermal annealing affects the redistribution of alkali metals in CIGS solar cells on glass substrates and the properties of the solar cells. In addition, we investigate the origin of non-homogeneous alkali-metal depth profiles that are typical of CIGS grown using a three-stage process. In particular, we use secondary-ion mass spectrometry measurements of the ion concentration as a function of distance from the CIGS surface to investigate the impact of thermal annealing on the distribution of alkali metals (Na, Ka, and Rb) and constituent elements (Ga and In) in the CIGS absorbers. We find that the depth profiles of the alkali metals strongly reflect the density of sites that tend to accommodate alkali metals, i.e., vacancies. Annealing at elevated temperature caused a redistribution of the alkali metals. The thermal-diffusion kinetics of alkali metals depends strongly on the species involved. We introduced low flux potassium fluoride (KF) to study a side effect of KF-PDT, i.e., Na removal from CIGS, separately from its predominant effects such as surface modification. When sufficient amounts of Na are supplied from the soda lime glass via annealing at an elevated temperature, the negative effect was not apparent. Conversely, when the Na supply was not sufficient, it caused a deterioration of the photovoltaic properties.

  7. Element specificity of ortho-positronium annihilation for alkali-metal loaded SiO2 glasses.

    Science.gov (United States)

    Sato, K; Hatta, T

    2015-03-07

    Momentum distributions associated with ortho-positronium (o-Ps) pick-off annihilation photon are often influenced by light elements, as, e.g., carbon, oxygen, and fluorine. This phenomenon, so-called element specificity of o-Ps pick-off annihilation, has been utilized for studying the elemental environment around the open spaces. To gain an insight into the element specificity of o-Ps pick-off annihilation, the chemical shift of oxygen 1s binding energy and the momentum distributions associated with o-Ps pick-off annihilation were systematically investigated for alkali-metal loaded SiO2 glasses by means of X-ray photoelectron spectroscopy and positron-age-momentum correlation spectroscopy, respectively. Alkali metals introduced into the open spaces surrounded by oxygen atoms cause charge transfer from alkali metals to oxygen atoms, leading to the lower chemical shift for the oxygen 1s binding energy. The momentum distribution of o-Ps localized into the open spaces is found to be closely correlated with the oxygen 1s chemical shift. This correlation with the deepest 1s energy level evidences that the element specificity of o-Ps originates from pick-off annihilation with orbital electrons, i.e., dominantly with oxygen 2p valence electrons and s electrons with lower probability.

  8. Biodiesel production using alkali earth metal oxides catalysts synthesized by sol-gel method

    Directory of Open Access Journals (Sweden)

    Majid Mohadesi

    2014-03-01

    Full Text Available Biodiesel fuel is considered as an alternative to diesel fuel. This fuel is produced through transesterification reactions of vegetable oils or animal fat by alcohols in the presence of different catalysts. Recent studies on this process have shown that, basic heterogeneous catalysts have a higher performance than other catalysts. In this study different alkali earth metal oxides (CaO, MgO and BaO doped SiO2 were used as catalyst for the biodiesel production process. These catalysts were synthesis by using the sol-gel method. A transesterification reaction was studied after 8h by mixing corn oil, methanol (methanol to oil molar ratio of 16:1, and 6 wt. % catalyst (based on oil at 60oC and 600rpm. Catalyst loading was studied for different catalysts ranging in amounts from 40, 60 to 80%. The purity and yield of the produced biodiesel for 60% CaO/SiO2 was higher than other catalysts and at 97.3% and 82.1%, respectively.

  9. The influence of alkali metal impurities on the uranium dioxide hydrofluorination reaction

    International Nuclear Information System (INIS)

    Ponelis, A.A.

    1989-01-01

    The effect alkali metal impurities (sodium and potassium) in the uranium dioxide (UO 2 ) feed material have on the conversion to uraniumtetrafluoride (UF 4 ) was examined. A direct correlation exists between impurity level and sintering with concomitant reduced conversion. The sintering mechanism is attributable to decreased specific surface area. The typical 'die-off' of reaction or conversion can be explained in terms of increased particle growth rather than an arbitray zero porosity function. Hydrofluorination temperatures varied from 250 to 650 degrees C using pellets varying in size from 0.42 mm to 10 mm. Scanning electron microscope photographs show clearly the particle or grain growth in the pellet as well as the increased size with impurity level. A new dimensionless constant, N KP , is defined to facilitate explanation of the reaction as a function of pellet radius. N KP is defined as the ratio of pellet diffusion resistance to particle diffusion resistance of the reacting HF gas. At high values of this number (N KP >40) the conversion is limited to the outer periphery of the pellet while at low values (N KP KP at higher reaction temperatures which means that the particle diffusion resistance increases with increasing impurity level and results in easier sintering of these materials. 53 refs., 206 figs., 94 tabs

  10. Endocytic regulation of alkali metal transport proteins in mammals, yeast and plants.

    Science.gov (United States)

    Mulet, José Miguel; Llopis-Torregrosa, Vicent; Primo, Cecilia; Marqués, Ma Carmen; Yenush, Lynne

    2013-11-01

    The relative concentrations of ions and solutes inside cells are actively maintained by several classes of transport proteins, in many cases against their concentration gradient. These transport processes, which consume a large portion of cellular energy, must be constantly regulated. Many structurally distinct families of channels, carriers, and pumps have been characterized in considerable detail during the past decades and defects in the function of some of these proteins have been linked to a growing list of human diseases. The dynamic regulation of the transport proteins present at the cell surface is vital for both normal cellular function and for the successful adaptation to changing environments. The composition of proteins present at the cell surface is controlled on both the transcriptional and post-translational level. Post-translational regulation involves highly conserved mechanisms of phosphorylation- and ubiquitylation-dependent signal transduction routes used to modify the cohort of receptors and transport proteins present under any given circumstances. In this review, we will summarize what is currently known about one facet of this regulatory process: the endocytic regulation of alkali metal transport proteins. The physiological relevance, major contributors, parallels and missing pieces of the puzzle in mammals, yeast and plants will be discussed.

  11. Epitaxy of oligothiophenes on alkali metal hydrogen phthalates: Simulations and experiments.

    Science.gov (United States)

    Trabattoni, S; Raimondo, L; Sassella, A; Moret, M

    2017-03-28

    Three alkali metal hydrogen phthalate salts (denoted as XAP, X = K + , Rb + , and Cs + ) are chosen as substrates for the growth of quaterthiophene (4T) and hexathiophene (6T) thin films by organic molecular beam epitaxy to study the influence of gradual changes of surface unit cell parameters on the epitaxialgrowth. The increment of substrate lattice parameters increases the distance between the planes that define the furrows where oligothiophene molecules lie, while keeping unmodified the interactions between the overlayer and the substrate. Atom-atom potential simulations predict the preferential azimuthal orientations of the overlayer, which are compared with those experimentally observed. The agreement between simulations and experiments about contact planes and orientation of the crystalline domains in the films is satisfactory for both 4T/XAP and 6T/XAP. The increasing width of the surface furrows existing on moving from KAP to RbAP and CsAP does not cause any significant variation of the orientation and density of the overlayer domains, demonstrating that the interaction between overlayer and substrate is the key factor guiding organic epitaxialgrowth.

  12. Reaction of aluminium selenites with alkali metal selenites in hydrothermal conditions

    International Nuclear Information System (INIS)

    Tananaev, I.V.; Volodina, A.N.; Bol'shakova, N.K.; Petrov, K.I.

    1976-01-01

    In the course of hydrothermal crystallization (T from 150 deg to 200 deg C, P=20 atm) of Al 2 (SeO 3 ) 3 x6H 2 O in solutions of cesium and rubidium trihydroselenites, which contain an excess of the alkali metals, there form the isostructural mixed selenites Cssub(0.5)Hsub(0.5)Al(SeO 3 ) 2 xH 2 O and Rbsub(0.6)Hsub(0.4)Al(SeO 3 ) 2 x2H 2 O. Under the same conditions, in the solutions of lithium, sodium and potassium trihydroselenites, Al 2 (SeO 3 ) 3 x6H 2 O fails to form the mixed selenites. The IR-spectroscopic study of the mixed selenites Al has been carried out and their thermal decomposition has been investigated. The obtained data make it possible to represent the mixed selenites by the formula Msub(x)Hsub(1-x)Al(SeO 3 ) 2 xnH 2 O and to regard them as compounds of variable composition [ru

  13. The characterisation of vapour-phase alkali metal-tellurium-oxygen species

    International Nuclear Information System (INIS)

    Gomme, R.A.; Ogden, J.S.; Bowsher, B.R.

    1986-10-01

    Detailed assessments of hypothetical severe accidents in light water reactors require the identification of the chemical forms of the radionuclides in order to determine their transport characteristics. Caesium and tellurium are important volatile fission products in accident scenarios. This report describes detailed studies to characterise the chemical species that vaporise from heated mixtures of various alkali metal-tellurium-oxygen systems. The molecular species were characterised by a combination of quadrupole mass spectrometry and matrix isolation-infrared spectroscopy undertaken in conjunction with experiments involving oxygen-18 substitution. The resulting spectra were interpreted in terms of a vapour-phase molecule with the stoichiometry M 2 TeO 3 (M = K,Rb,Cs) for M/Te molecular ratios of ∼ 2, and polymeric species for ratios < 2. This work has demonstrated the stability of caesium tellurite. The formation of this relatively low-volatility, water-soluble species could significantly modify the transport and release of caesium and tellurium. The data presented in this report should allow more comprehensive thermodynamic calculations to be undertaken that assist in the quantification of fission product behaviour during severe reactor accidents. (author)

  14. Ionophore-Based Titrimetric Detection of Alkali Metal Ions in Serum.

    Science.gov (United States)

    Zhai, Jingying; Xie, Xiaojiang; Cherubini, Thomas; Bakker, Eric

    2017-04-28

    While the titrimetric assay is one of the most precise analytical techniques available, only a limited list of complexometric chelators is available, as many otherwise promising reagents are not water-soluble. Recent work demonstrated successful titrimetry with ion-exchanging polymeric nanospheres containing hydrophobic complexing agents, so-called ionophores, opening an exciting avenue in this field. However, this method was limited to ionophores of very high affinity to the analyte and exhibited a relatively limited titration capacity. To overcome these two limitations, we report here on solvent based titration reagents. This heterogeneous titration principle is based on the dissolution of all hydrophobic recognition components in a solvent such as dichloromethane (CH 2 Cl 2 ) where the ionophores are shown to maintain a high affinity to the target ions. HSV (hue, saturation, value) analysis of the images captured with a digital camera provides a convenient and inexpensive way to determine the end point. This approach is combined with an automated titration setup. The titrations of the alkali metals K + , Na + , and Li + in aqueous solution are successfully demonstrated. The potassium concentration in human serum without pretreatment was precisely and accurately determined as 4.38 mM ± 0.10 mM (automated titration), which compares favorably with atomic emission spectroscopy (4.47 mM ± 0.20 mM).

  15. Alkali Metal Modification of Silica Gel-Based Stationary Phase in Gas Chromatography

    Directory of Open Access Journals (Sweden)

    Ashraf Yehia El-Naggar

    2013-01-01

    Full Text Available Modification of the precipitated silica gel was done by treatment with alkali metal (NaCl before and after calcination. The silica surfaces before and after modification were confirmed by infrared spectroscopy in order to observe the strength and abundance of the acidic surface OH group bands which play an important role in the adsorption properties of polar and nonpolar solutes. The surface-modified silica gels were tested as GC solid stationary phases in terms of the separation efficiency for various groups of non-polar and polar solutes. Also, thermodynamic parameters (ΔH, ΔG, and ΔS were determined using n-hexane as a probe in order to show the adsorbate-adsorbent interaction. It was observed that the non-polar solutes could be separated Independent on the reactivity and porosity of the silica surfaces. The efficiency of the surface-modified silica gels to separate the aromatic hydrocarbons seemed to be strongly influenced by the density of the surface hydroxyls.

  16. Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism.

    Science.gov (United States)

    Boughlala, Zakaria; Fonseca Guerra, Célia; Bickelhaupt, F Matthias

    2016-06-01

    We have analyzed the structure and bonding of gas-phase Cl-X and [HCl-X](+) complexes for X(+)= H(+), CH3 (+), Li(+), and Na(+), using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl(-) and HCl for the various cations. The Cl-X bond becomes longer and weaker along X(+) = H(+), CH3 (+), Li(+), and Na(+). Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence of solvent) alkali metal cation affinities (AMCA) and how this compares with and differs from those of the proton affinity (PA) and methyl cation affinity (MCA). Our analyses are based on Kohn-Sham molecular orbital (KS-MO) theory in combination with a quantitative energy decomposition analysis (EDA) that pinpoints the importance of the different features in the bonding mechanism. Orbital overlap appears to play an important role in determining the trend in cation affinities.

  17. Oxygen redox chemistry without excess alkali-metal ions in Na2/3[Mg0.28Mn0.72]O2

    Science.gov (United States)

    Maitra, Urmimala; House, Robert A.; Somerville, James W.; Tapia-Ruiz, Nuria; Lozano, Juan G.; Guerrini, Niccoló; Hao, Rong; Luo, Kun; Jin, Liyu; Pérez-Osorio, Miguel A.; Massel, Felix; Pickup, David M.; Ramos, Silvia; Lu, Xingye; McNally, Daniel E.; Chadwick, Alan V.; Giustino, Feliciano; Schmitt, Thorsten; Duda, Laurent C.; Roberts, Matthew R.; Bruce, Peter G.

    2018-03-01

    The search for improved energy-storage materials has revealed Li- and Na-rich intercalation compounds as promising high-capacity cathodes. They exhibit capacities in excess of what would be expected from alkali-ion removal/reinsertion and charge compensation by transition-metal (TM) ions. The additional capacity is provided through charge compensation by oxygen redox chemistry and some oxygen loss. It has been reported previously that oxygen redox occurs in O 2p orbitals that interact with alkali ions in the TM and alkali-ion layers (that is, oxygen redox occurs in compounds containing Li+-O(2p)-Li+ interactions). Na2/3[Mg0.28Mn0.72]O2 exhibits an excess capacity and here we show that this is caused by oxygen redox, even though Mg2+ resides in the TM layers rather than alkali-metal (AM) ions, which demonstrates that excess AM ions are not required to activate oxygen redox. We also show that, unlike the alkali-rich compounds, Na2/3[Mg0.28Mn0.72]O2 does not lose oxygen. The extraction of alkali ions from the alkali and TM layers in the alkali-rich compounds results in severely underbonded oxygen, which promotes oxygen loss, whereas Mg2+ remains in Na2/3[Mg0.28Mn0.72]O2, which stabilizes oxygen.

  18. Design and Test of Advanced Thermal Simulators for an Alkali Metal-Cooled Reactor Simulator

    Science.gov (United States)

    Garber, Anne E.; Dickens, Ricky E.

    2011-01-01

    The Early Flight Fission Test Facility (EFF-TF) at NASA Marshall Space Flight Center (MSFC) has as one of its primary missions the development and testing of fission reactor simulators for space applications. A key component in these simulated reactors is the thermal simulator, designed to closely mimic the form and function of a nuclear fuel pin using electric heating. Continuing effort has been made to design simple, robust, inexpensive thermal simulators that closely match the steady-state and transient performance of a nuclear fuel pin. A series of these simulators have been designed, developed, fabricated and tested individually and in a number of simulated reactor systems at the EFF-TF. The purpose of the thermal simulators developed under the Fission Surface Power (FSP) task is to ensure that non-nuclear testing can be performed at sufficiently high fidelity to allow a cost-effective qualification and acceptance strategy to be used. Prototype thermal simulator design is founded on the baseline Fission Surface Power reactor design. Recent efforts have been focused on the design, fabrication and test of a prototype thermal simulator appropriate for use in the Technology Demonstration Unit (TDU). While designing the thermal simulators described in this paper, effort were made to improve the axial power profile matching of the thermal simulators. Simultaneously, a search was conducted for graphite materials with higher resistivities than had been employed in the past. The combination of these two efforts resulted in the creation of thermal simulators with power capacities of 2300-3300 W per unit. Six of these elements were installed in a simulated core and tested in the alkali metal-cooled Fission Surface Power Primary Test Circuit (FSP-PTC) at a variety of liquid metal flow rates and temperatures. This paper documents the design of the thermal simulators, test program, and test results.

  19. Conductivity Measurements of Alkali Metal Thiocyanates in Water-Methanol Mixtures; Mizu-metanoru kongoyoubai ni okeru arukari kinzoku chioshiansan`en no denki dendodo sokutei

    Energy Technology Data Exchange (ETDEWEB)

    Kubota, Eiji.; Horimoto, Sanaki. [Shinshu University, Nagano (Japan). Faculty of Science

    1999-03-10

    The counductivity of several alkali nmetal thiocyanates in water-methanol mixtures was measured at 25degreeC. the data were analyzed using Lee-Wheaton theory for symmetrical electroyers to cbtain ion association constant, K{sub A}, limiting molar sonductivity, {Lambda}{sub 0}, and limiting ionic molar conductivity, lamnda{sub 0}{+-}. In all the solvent systems, calculated{lambda}{sub 0}{sup +} values of the alkali metal ions increase in the order L{sub i}{sup +}alkali metal ions and thiocyanate ion showed a minimum when the molar fraction of methanol was ca.0.4. The changes in {lambda}{sub 0}{+-} of these alkali metal ions and thiocyanate ion with the molar fraction of methanol agree with change in the viscosity of the solvent or the heat of mixing of wateer-methanol mixtures. These alkali metal thiocyanates from little or no ion aggregated in water and water-methanol mixtures. These alkali metal thiocyanates K{sub A}=15-24 dm{sup 3} mol{sub -1} in methanol. (author)

  20. Effect of metallic Si addition on polymerization degree of in situ foamed alkali-aluminosilicates

    Czech Academy of Sciences Publication Activity Database

    Medri, V.; Papa, E.; Dědeček, Jiří; Jirglová, Hana; Benito, P.; Vaccari, A.; Landi, E.

    2013-01-01

    Roč. 39, č. 7 (2013), s. 7657-7668 ISSN 0272-8842 Institutional support: RVO:61388955 Keywords : B. porosity * alkali-bonded ceramics * geopolymerization Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.086, year: 2013

  1. Hydrogen production coupled to nuclear waste treatment: the safe treatment of alkali metals through a well-demonstrated process

    International Nuclear Information System (INIS)

    Rahier, A.; Mesrobian, G.

    2006-01-01

    In 1992, the United Nations emphasised the urgent need to act against the perpetuation of disparities between and within nations, the worsening of poverty, hunger, ill health and illiteracy and the continuing deterioration of ecosystems on which we depend for our well-being. In this framework, taking into account the preservation of both worldwide energy resources and ecosystems, the use of nuclear energy to produce clean energy carriers, such as hydrogen, is undoubtedly advisable. However, coping fully with the Agenda 21 statements requires defining adequate treatment processes for nuclear wastes. This paper discusses the possible use of a well-demonstrated process to convert radioactively contaminated alkali metals into sodium hydroxide while producing hydrogen. We conclude that a synergy between Chlor-Alkali specialists and nuclear specialists may help find an acceptable solution for radioactively contaminated sodium waste. (author)

  2. Study on the Characteristics of an Alkali-Metal Thermoelectric Power Generation System

    Science.gov (United States)

    Lee, Wook-Hyun; Hwang, Hyun-Chang; Lee, Ji-Su; Kim, Pan-Jo; Lim, Sang-Hyuk; Rhi, Seok-Ho; Lee, Kye-Bock; Lee, Ki-Woo

    2015-10-01

    In the present study, a numerical simulation and experimental studies of an alkali-metal thermoelectric energy converter (AMTEC) system were carried out. The present, unique AMTEC model consists of an evaporator, a β-alumina solid electrolyte (BASE) tube, a condenser, and an artery cable wick. The key points for operation of the present AMTEC were 1100 K in the evaporator and 600 K in the condenser. A numerical model based on sodium-saturated porous wicks was developed and shown to be able to simulate the AMTEC system. The simulation results show that the AMTEC system can generate up to 100 W with a given design. The AMTEC system developed in the present work and used in the practical investigations could generate an electromotive force of 7 V. Artery wick and evaporator wick structures were simulated for the optimum design. Both sodium-saturated wicks were affected by numerous variables, such as the input heat power, cooling temperature, sodium mass flow rate, and capillary-driven fluid flow. Based on an effective thermal conductivity model, the presented simulation could successfully predict the system performance. Based on the numerical simulation, the AMTEC system operates with efficiency near 10% to 15%. In the case of an improved BASE design, the system could reach efficiency of over 30%. The system was designed for 0.6 V power, 25 A current, and 100 W power input. In addition, in this study, the temperature effects in each part of the AMTEC system were analyzed using a heat transfer model in porous media to apply to the computational fluid dynamics at a predetermined temperature condition for the design of a 100-W AMTEC prototype. It was found that a current density of 0.5 A/cm2 to 0.9 A/cm2 for the BASE is suitable when the temperatures of the evaporator section and condenser section are 1100 K and 600 K, respectively.

  3. Thermal Emission of Alkali Metal Ions from Al30-Pillared Montmorillonite Studied by Mass Spectrometric Method.

    Science.gov (United States)

    Motalov, V B; Karasev, N S; Ovchinnikov, N L; Butman, M F

    2017-01-01

    The thermal emission of alkali metal ions from Al 30 -pillared montmorillonite in comparison with its natural form was studied by mass spectrometry in the temperature range 770-930 K. The measurements were carried out on a magnetic mass spectrometer MI-1201. For natural montmorillonite, the densities of the emission currents ( j ) decrease in the mass spectrum in the following sequence (T = 805 K, A/cm 2 ): K + (4.55 · 10 -14 ), Cs + (9.72 · 10 -15 ), Rb + (1.13 · 10 -15 ), Na + (1.75 · 10 -16 ), Li + (3.37 · 10 -17 ). For Al 30 -pillared montmorillonite, thermionic emission undergoes temperature-time changes. In the low-temperature section of the investigated range (770-805 K), the value of j increases substantially for all ions in comparison with natural montmorillonite (T = 805 K, A/cm 2 ): Cs + (6.47 · 10 -13 ), K + (9.44 · 10 -14 ), Na + (3.34 · 10 -15 ), Rb + (1.77 · 10 -15 ), and Li + (4.59 · 10 -16 ). A reversible anomaly is observed in the temperature range 805-832 K: with increasing temperature, the value of j of alkaline ions falls abruptly. This effect increases with increasing ionic radius of M + . After a long heating-up period, this anomaly disappears and the ln j - 1/ T dependence acquires a classical linear form. The results are interpreted from the point of view of the dependence of the efficiency of thermionic emission on the phase transformations of pillars.

  4. Thermal Emission of Alkali Metal Ions from Al30-Pillared Montmorillonite Studied by Mass Spectrometric Method

    Directory of Open Access Journals (Sweden)

    V. B. Motalov

    2017-01-01

    Full Text Available The thermal emission of alkali metal ions from Al30-pillared montmorillonite in comparison with its natural form was studied by mass spectrometry in the temperature range 770–930 K. The measurements were carried out on a magnetic mass spectrometer MI-1201. For natural montmorillonite, the densities of the emission currents (j decrease in the mass spectrum in the following sequence (T = 805 K, A/cm2: K+ (4.55 · 10−14, Cs+ (9.72 · 10−15, Rb+ (1.13 · 10−15, Na+ (1.75 · 10−16, Li+ (3.37 · 10−17. For Al30-pillared montmorillonite, thermionic emission undergoes temperature-time changes. In the low-temperature section of the investigated range (770–805 K, the value of j increases substantially for all ions in comparison with natural montmorillonite (T = 805 K, A/cm2: Cs+ (6.47 · 10−13, K+ (9.44 · 10−14, Na+ (3.34 · 10−15, Rb+ (1.77 · 10−15, and Li+ (4.59 · 10−16. A reversible anomaly is observed in the temperature range 805–832 K: with increasing temperature, the value of j of alkaline ions falls abruptly. This effect increases with increasing ionic radius of M+. After a long heating-up period, this anomaly disappears and the lnj-1/T dependence acquires a classical linear form. The results are interpreted from the point of view of the dependence of the efficiency of thermionic emission on the phase transformations of pillars.

  5. Heavy metal vaporization and abatement during thermal treatment of modified wastes

    International Nuclear Information System (INIS)

    Rio, S.; Verwilghen, C.; Ramaroson, J.; Nzihou, A.; Sharrock, P.

    2007-01-01

    This study examines the vaporization percentage and partitioning of heavy metals Cd, Pb and Zn during thermal treatment of wastes with added PVC, heavy metals or phosphate, and the efficiency of sorbents for removal of these metallic compounds in flue gas of an industrial solid waste incinerator. Firstly, vaporization experiments were carried out to determine the behavior of heavy metals during combustion under various conditions (type of waste, temperature, presence of chloride or phosphate ...). The experimental results show relatively high vaporization percentage of metallic compounds within fly ash and limestone matrix while heavy metals within sediments treated with phosphoric acid are less volatile. Vaporization of metals increases with increasing temperature and with chloride addition. The thermal behavior of the selected heavy metals and their removal by sorbents (sodium bicarbonate, activated carbon) was also studied in an industrial solid waste incinerator. These pilot scale experiments confirm that heavy metals are concentrated in fly ashes and cyclone residues, thus effectively controlling their release to the atmosphere

  6. Dimensional reduction in Bose-Einstein-condensed alkali-metal vapors

    International Nuclear Information System (INIS)

    Salasnich, L.; Reatto, L.; Parola, A.

    2004-01-01

    We investigate the effects of dimensional reduction in atomic Bose-Einstein condensates (BECs) induced by a strong harmonic confinement in the cylindric radial direction or in the cylindric axial direction. The former case corresponds to a transition from three dimensions (3D) to 1D in cigar-shaped BECs, while the latter case corresponds to a transition from 3D to 2D in disk-shaped BECs. We analyze the first sound velocity in axially homogeneous cigar-shaped BECs and in radially homogeneous disk-shaped BECs. We consider also the dimensional reduction in a BEC confined by a harmonic potential both in the radial direction and in the axial direction. By using a variational approach, we calculate monopole and quadrupole collective oscillations of the BEC. We find that the frequencies of these collective oscillations are related to the dimensionality and to the repulsive or attractive interatomic interaction

  7. Dimensional reduction in Bose-Einstein-condensed alkali-metal vapors

    Science.gov (United States)

    Salasnich, L.; Parola, A.; Reatto, L.

    2004-04-01

    We investigate the effects of dimensional reduction in atomic Bose-Einstein condensates (BECs) induced by a strong harmonic confinement in the cylindric radial direction or in the cylindric axial direction. The former case corresponds to a transition from three dimensions (3D) to 1D in cigar-shaped BECs, while the latter case corresponds to a transition from 3D to 2D in disk-shaped BECs. We analyze the first sound velocity in axially homogeneous cigar-shaped BECs and in radially homogeneous disk-shaped BECs. We consider also the dimensional reduction in a BEC confined by a harmonic potential both in the radial direction and in the axial direction. By using a variational approach, we calculate monopole and quadrupole collective oscillations of the BEC. We find that the frequencies of these collective oscillations are related to the dimensionality and to the repulsive or attractive interatomic interaction.

  8. Theoretical investigation on the alkali-metal doped BN fullerene as a material for hydrogen storage

    International Nuclear Information System (INIS)

    Venkataramanan, Natarajan Sathiyamoorthy; Belosludov, Rodion Vladimirovich; Note, Ryunosuke; Sahara, Ryoji; Mizuseki, Hiroshi; Kawazoe, Yoshiyuki

    2010-01-01

    Graphical abstract: First-principles calculations have been used to investigate hydrogen adsorption on alkali atom doped B 36 N 36 clusters. Adsorption of alkali atoms involves a charge transfer process, creating positively-charged alkali atoms and this polarizes the H 2 molecules and increases their binding energy. The maximum hydrogen storage capacity of Li doped BN fullerene is 8.9 wt.% in which 60 hydrogen atoms were chemisorbed and 12 H 2 were adsorbed in molecular form. - Abstract: First-principles calculations have been used to investigate hydrogen adsorption on alkali atom doped B 36 N 36 clusters. The alkali atom adsorption takes place near the six tetragonal bridge sites available on the cage, thereby avoiding the notorious clustering problem. Adsorption of alkali atoms involves a charge transfer process, creating positively charged alkali atoms and this polarizes the H 2 molecules thereby, increasing their binding energy. Li atom has been found to adsorb up to three hydrogen molecules with an average binding energy of 0.189 eV. The fully doped Li 6 B 36 N 36 cluster has been found to hold up to 18 hydrogen molecules with the average binding energy of 0.146 eV. This corresponds to a gravimetric density of hydrogen storage of 3.7 wt.%. Chemisorption on the Li 6 B 36 N 36 has been found to be an exothermic reaction, in which 60 hydrogen atoms chemisorbed with an average chemisorption energy of -2.13 eV. Thus, the maximum hydrogen storage capacity of Li doped BN fullerene is 8.9 wt.% in which 60 hydrogen atoms were chemisorbed and 12 hydrogen molecules were adsorbed in molecular form.

  9. Mechanical properties of vapor-deposited thin metallic films: a status report

    International Nuclear Information System (INIS)

    Adler, P.H.

    1982-01-01

    The mechanical properties of vapor-deposited thin metallic films are being studied in conjunction with the target fabrication group associated with the laser-fusion energy program. The purpose of the work is to gain an understanding as to which metals are structurally best suited to contain a glass microsphere filled with deuterium-tritium (D-T) gas at large internal pressures

  10. Association of alkali and alkaline earth metal cations with radical-anions of 9-fluorenone and 9.10-anthraquinone in dimethyl formamide medium

    International Nuclear Information System (INIS)

    Karpinets, A.P.; Bezuglyj, V.D.; Svetlichnaya, T.M.

    1988-01-01

    The polarographic method is used to estimate the stability of associates formed in dimethyl formamide by the products of one-electron reduction of 9-fluorenone and 9.10-anthraquinone with cations of alkali and alkali earth metals. It is shown that the strength of 9-fluorenone and 9.10-anthraquinone radical anion associates studied increases with cation charge increase and decrease of its crystallographic radius

  11. Methane coupling reaction in an oxy-steam stream through an OH radical pathway by using supported alkali metal catalysts

    KAUST Repository

    Liang, Yin

    2014-03-24

    A universal reaction mechanism involved in the oxidative coupling of methane (OCM) is demonstrated under oxy-steam conditions using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH radical formation from a H 2O-O2 reaction followed by C-H activation in CH 4 with an OH radical. Thus, the presence of water enhances both the CH4 conversion rate and the C2 selectivity. This OH radical pathway that is selective for the OCM was observed for the catalyst without Mn, which suggests clearly that Mn is not the essential component in a selective OCM catalyst. The experiments with different catalyst compositions revealed that the OH.-mediated pathway proceeded in the presence of catalysts with different alkali metals (Na, K) and different oxo anions (W, Mo). This difference in catalytic activity for OH radical generation accounts for the different OCM selectivities. As a result, a high C2 yield is achievable by using Na2WO4/SiO2, which catalyzes the OH.-mediated pathway selectively. Make it methane: A universal reaction mechanism involved in the oxidative coupling of methane is demonstrated under oxy-stream conditions by using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH radical formation from an H2O-O2 reaction, followed by C-H activation in CH4 with an OH radical. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Plasma assisted measurements of alkali metal concentrations in pressurised combustion processes

    Energy Technology Data Exchange (ETDEWEB)

    Hernberg, R.; Haeyrinen, V. [Tampere Univ. of Technology (Finland)

    1997-10-01

    In this project the continuous alkali measurement method plasma excited alkali resonance line spectroscopy (PEARLS) was developed, tested and demonstrated in pressurised combustion facilities. The PEARLS method has been developed at Tampere University of Technology (TUT). During 1994-1996 the PEARLS method was developed from the laboratory level to an industrial prototype. The alkali measuring instrument has been tested and used for regular measurements in four different pressurised combustion installations ranging up to industrial pilot scale. The installations are: (1) a pressurised entrained flow reactor (PEFR) at VTT Energy in Jyvaeskylae, Finland (2) a pressurised fluidised bed combustion facility, called FRED, at DMT in Essen, Germany. (3) a 10 MW pressurised circulating fluidised bed combustion pilot plant at Foster Wheeler Energia Oy in Karhula, Finland (4) PFBC Research Facility at ABB Carbon in Finspaang, Sweden

  13. Preparation, characterization and applications of novel iminodiacetic polyurethane foam (IDA-PUF) for determination and removal of some alkali metal ions from water

    Energy Technology Data Exchange (ETDEWEB)

    El-Shahat, M.F. [Chemistry Department, Faculty of Science, Ain Shams University, Cairo (Egypt); Moawed, E.A. [Chemistry Department, Faculty of Science, Mansoura University, Damietta (Egypt)], E-mail: emoawed@hotmail.com; Burham, N. [Chemistry Department, Faculty of Science, Fayoum University (Egypt)

    2008-12-30

    The new type of ion chelating resin (IDA-PUF) has iminodiacetic group that was prepared from polyurethane foam (PUF) by the reaction between primary amine of PUF and monochloro-acetic acid. The IDA-PUF was characterized using infrared spectra, elemental and thermal analysis. The exchange properties and chromatographic behaviour of the new chelating resin were investigated for removal of some alkali metal ions (lithium, sodium and potassium) using batch and column processes. The maximum distribution coefficient (K{sub D}) of trace alkali metal ions was in the pH range of 8-10. The kinetics of sorption of the alkali metal ions was found to be fast with average values of half-life of sorption (t{sub 1/2}) of 4.93 min. The values of {delta}G, {delta}S and {delta}H were -3.86 kJ mol{sup -1}, 57.73 J mol{sup -1} K{sup -1} and 14.41 kJ mol{sup -1}, respectively, which reflects the spontaneous and endothermic nature of ion exchanger process. The average sorption capacity of IDA-PUF is 4.8 mmol/g for alkali metal ions, enrichment factors {approx}40 and the recovery 95-100% were also achieved with average value of RSD% = 1.67. The proposed method has been successfully applied to preconcentrate, determinate and remove the alkali metal ions from different samples of water.

  14. Preparation, characterization and applications of novel iminodiacetic polyurethane foam (IDA-PUF) for determination and removal of some alkali metal ions from water.

    Science.gov (United States)

    El-Shahat, M F; Moawed, E A; Burham, N

    2008-12-30

    The new type of ion chelating resin (IDA-PUF) has iminodiacetic group that was prepared from polyurethane foam (PUF) by the reaction between primary amine of PUF and monochloro-acetic acid. The IDA-PUF was characterized using infrared spectra, elemental and thermal analysis. The exchange properties and chromatographic behaviour of the new chelating resin were investigated for removal of some alkali metal ions (lithium, sodium and potassium) using batch and column processes. The maximum distribution coefficient (KD) of trace alkali metal ions was in the pH range of 8-10. The kinetics of sorption of the alkali metal ions was found to be fast with average values of half-life of sorption (t1/2) of 4.93min. The values of DeltaG, DeltaS and DeltaH were -3.86kJmol(-1), 57.73Jmol(-1)K(-1) and 14.41kJmol(-1), respectively, which reflects the spontaneous and endothermic nature of ion exchanger process. The average sorption capacity of IDA-PUF is 4.8mmol/g for alkali metal ions, enrichment factors approximately 40 and the recovery 95-100% were also achieved with average value of RSD%=1.67. The proposed method has been successfully applied to preconcentrate, determinate and remove the alkali metal ions from different samples of water.

  15. Third order nonlinear optical properties and optical limiting behavior of alkali metal complexes of p-nitrophenol

    Science.gov (United States)

    Thangaraj, M.; Vinitha, G.; Sabari Girisun, T. C.; Anandan, P.; Ravi, G.

    2015-10-01

    Optical nonlinearity of metal complexes of p-nitrophenolate (M=Li, Na and K) in ethanol is studied by using a continuous wave (cw) diode pumped Nd:YAG laser (532 nm, 50 mW). The predominant mechanism of observed nonlinearity is thermal in origin. The nonlinear refractive index and the nonlinear absorption coefficient of the samples were found to be in the order of 10-8 cm2/W and 10-3 cm/W respectively. Magnitude of third-order optical parameters varies according to the choice of alkali metal chosen for metal complex formation of p-nitrophenolate. The third-order nonlinear susceptibility was found to be in the order of 10-6 esu. The observed saturable absorption and the self-defocusing effect were used to demonstrate the optical limiting action at 532 nm by using the same cw laser beam.

  16. A Non-Exploding Alkali Metal Drop on Water: From Blue Solvated Electrons to Bursting Molten Hydroxide.

    Science.gov (United States)

    Mason, Philip E; Buttersack, Tillmann; Bauerecker, Sigurd; Jungwirth, Pavel

    2016-10-10

    Alkali metals in water are always at the brink of explosion. Herein, we show that this vigorous reaction can be kept in a non-exploding regime, revealing a fascinating richness of hitherto unexplored chemical processes. A combination of high-speed camera imaging and visible/near-infrared/infrared spectroscopy allowed us to catch and characterize the system at each stage of the reaction. After gently placing a drop of a sodium/potassium alloy on water under an inert atmosphere, the production of solvated electrons became so strong that their characteristic blue color could be observed with the naked eye. The exoergic reaction leading to the formation of hydrogen and hydroxide eventually heated the alkali metal drop such that it became glowing red, and part of the metal evaporated. As a result of the reaction, a perfectly transparent drop consisting of molten hydroxide was temporarily stabilized on water through the Leidenfrost effect, bursting spectacularly after it had cooled sufficiently. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. First principles study the effects of alkali metal and chorine adatoms on the opposite surface of graphene

    Science.gov (United States)

    Xinxiang, Song; Guang, Yuan; Meifeng, Dong; Mimura, Hidenori; Chun, Li; Mang, Niu

    2018-02-01

    Study of the adsorption properties of graphene has great significance for expanding its application. So far, few studies have analyzed the effects of adatoms on opposite sides of graphene. We use density functional theory to report the effects of chlorine and alkali metal adatoms on the other side of graphene. Although there is an obvious charge transfer between the adatom and graphene, the interaction between the adatoms is shielded by the large π bonds of graphene and therefore the effects of the adatom on the other side of graphene are very weak.

  18. Metal vapor laser and medicine: laser systems, methods, and therapy

    Science.gov (United States)

    Evtushenko, V. A.; Soldatov, Anatoly N.; Vusik, M. V.; Cheremisina, O. V.; Kucherova, T. Y.; Voronov, V. I.; Kirilov, Anatoly E.; Polunin, Yu. P.

    2002-03-01

    A copper-vapor laser 'Malakhit' was used to prevent and or treat complications caused by antitumor therapy. Results obtained for 19 adult patients with cancer of the lung, 59 adult patients with cancer of the stomach, and 640 children with malignant and benign tumors are discussed.

  19. Half-sandwich cobalt complexes in the metal-organic chemical vapor deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Georgi, Colin [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany); Hapke, Marko; Thiel, Indre [Leibniz-Institut für Katalyse e.V. an der Universität Rostock (LIKAT), Albert-Einstein-Straße 29a, Rostock 18059 (Germany); Hildebrandt, Alexander [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany); Waechtler, Thomas; Schulz, Stefan E. [Fraunhofer Institute of Electronic Nano Systems (ENAS), Technologie-Campus 3, Chemnitz 09126 (Germany); Technische Universität Chemnitz, Center for Microtechnologies (ZfM), Chemnitz 09107 (Germany); Lang, Heinrich, E-mail: heinrich.lang@chemie.tu-chemnitz.de [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany)

    2015-03-02

    A series of cobalt half-sandwich complexes of type [Co(η{sup 5}-C{sub 5}H{sub 5})(L)(L′)] (1: L, L′ = 1,5-hexadiene; 2: L = P(OEt){sub 3}, L′ = H{sub 2}C=CHSiMe{sub 3}; 3: L = L′ = P(OEt){sub 3}) has been studied regarding their physical properties such as the vapor pressure, decomposition temperature and applicability within the metal-organic chemical vapor deposition (MOCVD) process, with a focus of the influence of the phosphite ligands. It could be shown that an increasing number of P(OEt){sub 3} ligands increases the vapor pressure and thermal stability of the respective organometallic compound. Complex 3 appeared to be a promising MOCVD precursor with a high vapor pressure and hence was deposited onto Si/SiO{sub 2} (100 nm) substrates. The resulting reflective layer is closed, dense and homogeneous, with a slightly granulated surface morphology. X-ray photoelectron spectroscopy (XPS) studies demonstrated the formation of metallic cobalt, cobalt phosphate, cobalt oxide and cobalt carbide. - Highlights: • Thermal studies and vapor pressure measurements of cobalt half-sandwich complexes was carried out. • Chemical vapor deposition with cobalt half-sandwich complexes is reported. • The use of Co-phosphites results in significant phosphorous-doped metallic layers.

  20. Ion Partitioning at the liquid/vapor interface of a multi-component alkali halidesolution: A model for aqueous sea salt aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Ghosal, Sutapa; Brown, Matthew A.; Bluhm, Hendrik; Krisch, Maria J.; Salmeron, Miquel; Jungwirth, Pavel; Hemminger, John C.

    2008-12-22

    The chemistry of Br species associated with sea salt ice and aerosols has been implicated in the episodes of ozone depletion reported at Arctic sunrise. However, Br{sup -} is only a minor component in sea salt, which has a Br{sup -}/Cl{sup -} molar ratio of {approx}0.0015. Sea salt is a complex mixture of many different species, with NaCl as the primary component. In recent years experimental and theoretical studies have reported enhancement of the large, more polarizable halide ion at the liquid/vapor interface of corresponding aqueous alkali halide solutions. The proposed enhancement is likely to influence the availability of sea salt Br{sup -} for heterogeneous reactions such as those involved in the ozone depletion episodes. We report here ambient pressure x-ray photoelectron spectroscopy studies and molecular dynamics simulations showing direct evidence of Br{sup -} enhancement at the interface of an aqueous NaCl solution doped with bromide. The experiments were carried out on samples with Br{sup -}/Cl{sup -} ratios in the range 0.1% to 10%, the latter being also the ratio for which simulations were carried out. This is the first direct measurement of interfacial enhancement of Br{sup -} in a multi-component solution with particular relevance to sea salt chemistry.

  1. Plasma assisted measurements of alkali metal concentrations in pressurized combustion processes

    Energy Technology Data Exchange (ETDEWEB)

    Hernberg, R.; Haeyrinen, V. [Tampere Univ. of Technology (Finland). Dept. of Physics

    1996-12-01

    The plasma assisted method for continuous measurement of alkali concentrations in product gas flows of pressurized energy processes will be tested and applied at the 1.6 MW PFBC/G facility at Delft University of Technology in the Netherlands. During the reporting period the alkali measuring device has been tested under pressurized conditions at VTT Energy, DMT, Foster-Wheeler Energia and ABB Carbon. Measurements in Delft will be performed during 1996 after installation of the hot gas filter. The original plan for measurements in Delft has been postponed due to schedule delays in Delft. The results are expected to give information about the influence of different process conditions on the generation of alkali vapours, the comparison of different methods for alkali measurement and the specific performance of our system. This will be the first test of the plasma assisted measurement method in a gasification process. The project belongs to the Joule II extension program under contract JOU2-CT93-0431. (author)

  2. Alkali metal and ammonium chlorides in water and heavy water (binary systems)

    CERN Document Server

    Cohen-Adad, R

    1991-01-01

    This volume surveys the data available in the literature for solid-fluid solubility equilibria plus selected solid-liquid-vapour equilibria, for binary systems containing alkali and ammonium chlorides in water or heavy water. Solubilities covered are lithium chloride, sodium chloride, potassium chloride, rubidium chloride, caesium chloride and ammonium chloride in water and heavy water.

  3. C-N Bond Activation and Ring Opening of a Saturated N-Heterocyclic Carbene by Lateral Alkali-Metal-Mediated Metalation.

    Science.gov (United States)

    Hernán-Gómez, Alberto; Kennedy, Alan R; Hevia, Eva

    2017-06-01

    Combining alkali-metal-mediated metalation (AMMM) and N-heterocyclic carbene (NHC) chemistry, a novel C-N bond activation and ring-opening process is described for these increasingly important NHC molecules, which are generally considered robust ancillary ligands. Here, mechanistic investigations on reactions of saturated NHC SIMes (SIMes=[:C{N(2,4,6-Me 3 C 6 H 2 )CH 2 } 2 ]) with Group 1 alkyl bases suggest this destructive process is triggered by lateral metalation of the carbene. Exploiting co-complexation and trans-metal-trapping strategies with lower polarity organometallic reagents (Mg(CH 2 SiMe 3 ) 2 and Al(TMP)iBu 2 ), key intermediates in this process have been isolated and structurally defined. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Oxidation behavior of Cr(III) during thermal treatment of chromium hydroxide in the presence of alkali and alkaline earth metal chlorides.

    Science.gov (United States)

    Mao, Linqiang; Gao, Bingying; Deng, Ning; Liu, Lu; Cui, Hao

    2016-02-01

    The oxidation behavior of Cr(III) during the thermal treatment of chromium hydroxide in the presence of alkali and alkaline earth metal chlorides (NaCl, KCl, MgCl2, and CaCl2) was investigated. The amounts of Cr(III) oxidized at various temperatures and heating times were determined, and the Cr-containing species in the residues were characterized. During the transformation of chromium hydroxide to Cr2O3 at 300 °C approximately 5% of the Cr(III) was oxidized to form intermediate compounds containing Cr(VI) (i.e., CrO3), but these intermediates were reduced to Cr2O3 when the temperature was above 400 °C. Alkali and alkaline earth metals significantly promoted the oxidation of Cr(III) during the thermal drying process. Two pathways were involved in the influences the alkali and alkaline earth metals had on the formation of Cr(VI). In pathway I, the alkali and alkaline earth metals were found to act as electron transfer agents and to interfere with the dehydration process, causing more intermediate Cr(VI)-containing compounds (which were identified as being CrO3 and Cr5O12) to be formed. The reduction of intermediate compounds to Cr2O3 was also found to be hindered in pathway I. In pathway II, the alkali and alkaline earth metals were found to contribute to the oxidation of Cr(III) to form chromates. The results showed that the presence of alkali and alkaline earth metals significantly increases the degree to which Cr(III) is oxidized during the thermal drying of chromium-containing sludge. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Effects of alkali metal cations on phospho-enzyme levels and [3H] ouabain binding to (Na+ + K+)-ATPase.

    Science.gov (United States)

    Han, C S; Tobin, T; Akera, T; Brody, T M

    1976-05-13

    The effects of several alkali metal cations on the relationship between steady state phospho-enzyme levels and initial velocity and equilibrium levels of [3H]-ouabain binding to (Na+ + K+)-ATPase (ATP phosphohydrolase EC 3.6.1.3.) were examined. Only Na+ increased both phospho-enzyme and [3H] ouabain binding levels above those observed in the presence of Mg2+ alone. While Na+ stimulated phosphorylation with an apparent Km of about 1 mM, its stimulation of [3H] ouabain binding was biphasic, the lower Km for stimulation corresponding to the Km for formation of phospho-enzyme. Among the other alkali metal cations, potassium, rubidium and lithium were at least eight times more effect in reducing phospho-enzyme levels than in reducing [3H] ouabain binding. This discrepancy is not due to the stability of the enzyme-ouabain complex, nor to any action on the rates of formation or dissociation of the enzyme-ouabain complex. The data thus suggest that [3H] ouabain interacts with the K+, Rb+ or Li+ -enzyme complexes. For Li+, this hypothesis is further supported by the observation that Li+ can cirectly increase the equilibrium level of [3H] ouabain binding to this enzyme under certain conditions.

  6. Influence of alkali metal cations on the thermal, mechanical and morphological properties of rectorite/chitosan bio-nanocomposite films.

    Science.gov (United States)

    Babul Reddy, A; Jayaramudu, J; Siva Mohan Reddy, G; Manjula, B; Sadiku, E R

    2015-05-20

    The main theme of this work is to study the influence of ion-exchangeable alkali metal cations, such as: Li(+), Na(+), K(+), and Cs(+) on the thermal, mechanical and morphological properties. In this regard, a set of rectorite/chitosan (REC-CS) bio-nanocomposite films (BNCFs) was prepared by facile reaction of chitosan with ion-exchanged REC clay. The microstructure and morphology of BNCFs were investigated with XRD, TEM, SEM and AFM. Thermal and tensile properties of BNCFs were also investigated. As revealed from TEM and XRD results, the BNCFs featured a mixed morphology. Some intercalated clay sheets, together with nano-sized clay tactoids were obtained in LiREC/CS, NaREC/CS and KREC/CS of the BNCFs. From fractured surface study, via SEM, it was observed that the dispersion of chitosan polymer attaches to (and covers) the clay platelets. FTIR confirmed strong hydrogen bonds between clay and chitosan polymer. In addition, the thermal stabilities significantly varied when alkali metal cations varied from Li(+) to Cs(+). The BNCFs featured high tensile strengths (up to 84 MPa) and tensile moduli (up to 45 GPa). After evaluating these properties of BNCFs, we came to conclusion that these bio-nano composites can be used for packaging applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Study on the metal vapor generator for the production of improved gadolinia burnable poison material

    International Nuclear Information System (INIS)

    Jeong, O. C.; Noh, S. P.; Ko, K. H.; Kim, T. S.; Lim, C. H.; Kim, C. J.

    2002-01-01

    A longer cycle operation of a nuclear fuel is one of the ways to promote the economy of a nuclear power plant. For this purpose, high burn up fuel which has initial higher enrichment is required with higher loading of fuel. As a result, adequate burnable poison material must be used to control peak fuel pin power. Devices to manufacture the improved gadolinia burnable poison are developed. The improved gadolinia contains higher abundance of the preferred thermal neutron absorbers. Devices are composed of metal vapor generator, lasers and ion extractor. In this paper, a metal vapor generator by using electron beam gun is reported

  8. Release and sorption of alkali metals in coal fired combined cycle power systems; Freisetzung und Einbindung von Alkalimetallverbindungen in kohlebefeuerten Kombikraftwerken

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Michael

    2009-07-01

    Coal fired combined cycle power systems will be a sufficient way to increase the efficiency of coal combustion. However, combined cycle power systems require a reliable hot gas cleanup. Especially alkali metals, such as sodium and potassium, can lead to hot corrosion of the gas turbine blading if they condensate as sulphates. The actual work deals with the release and sorption of alkali metals in coal fired combined cycle power systems. The influence of coal composition, temperature and pressure on the release of alkali species in coal combustion was investigated and the relevant release mechanisms identified. Alumosilicate sorbents have been found that reduce the alkali concentration in the hot flue gas of the Circulating Pressurized Fluidized Bed Combustion 2{sup nd} Generation (CPFBC 2{sup nd} Gen.) at 750 C to values sufficient for use in a gas turbine. Accordingly, alumosilicate sorbents working at 1400 C have been found for the Pressurized Pulverized Coal Combustion (PPCC). The sorption mechanisms have been identified. Thermodynamic calculations were performed to upscale the results of the laboratory experiments to conditions prevailing in power systems. According to these calculations, there is no risk of hot corrosion in both processes. Furthermore, thermodynamic calculations were performed to investigate the behaviour of alkali metals in an IGCC with integrated hot gas cleanup and H{sub 2} membrane for CO{sub 2} sequestration. (orig.)

  9. Formation of microbeads during vapor explosions of Field's metal in water

    KAUST Repository

    Kouraytem, Nadia

    2016-06-17

    We use high-speed video imaging to investigate vapor explosions during the impact of a molten Field\\'s metal drop onto a pool of water. These explosions occur for temperatures above the Leidenfrost temperature and are observed to occur in up to three stages as the metal temperature is increased, with each explosion being more powerful that the preceding one. The Field\\'s metal drop breaks up into numerous microbeads with an exponential size distribution, in contrast to tin droplets where the vapor explosion deforms the metal to form porous solid structures. We compare the characteristic bead size to the wavelength of the fastest growing mode of the Rayleigh-Taylor instability.

  10. The theory of temporal compression of intense pulses in a metal vapor

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, M.J.; Crane, J.K.

    1990-11-16

    We examine compression of near-resonant pulses in metal vapor in the nonlinear regime. Our calculations examine nonlinear effects on compression of optimally-chirped pulses of various fluences. In addition, we compare model predictions with experimental results for compression of 4 nsec Nd:YAG pumped dye pulses.

  11. A comprehensive study of the complexation of alkali metal cations by lower rim calix[4]arene amide derivatives.

    Science.gov (United States)

    Horvat, Gordan; Frkanec, Leo; Cindro, Nikola; Tomišić, Vladislav

    2017-09-13

    The complexation of alkali metal cations by lower rim N,N-dihexylacetamide (L1) and newly synthesized N-hexyl-N-methylacetamide (L2) calix[4]arene tertiary-amide derivatives was thoroughly studied at 25 °C in acetonitrile (MeCN), benzonitrile (PhCN), and methanol (MeOH) by means of direct and competitive microcalorimetric titrations, and UV and 1 H NMR spectroscopies. In addition, by measuring the ligands' solubilities, the solution (transfer) Gibbs energies of the ligands and their alkali metal complexes were obtained. The inclusion of solvent molecules in the free and complexed calixarene hydrophobic cavities was also investigated. Computational (classical molecular dynamics) investigations of the studied systems were also carried out. The obtained results were compared with those previously obtained by studying the complexation ability of an N-hexylacetamidecalix[4]arene secondary-amide derivative (L3). The stability constants of 1 : 1 complexes were determined in all solvents used (the values obtained by different methods being in excellent agreement), as were the corresponding complexation enthalpies and entropies. Almost all of the examined reactions were enthalpically controlled. The most striking exceptions were reactions of Li + with both ligands in methanol, for which the entropic contribution to the reaction Gibbs energy was substantial due the entropically favourable desolvation of the smallest lithium cation. The thermodynamic stabilities of the complexes were quite solvent dependent (the stability decreased in the solvent order: MeCN > PhCN ≫ MeOH), which could be accounted for by considering the differences in the solvation of the ligand and free and complexed alkali metal cations in the solvents used. Comparison of the stability constants of the ligand L1 and L2 complexes clearly revealed that the higher electron-donating ability of the hexyl with respect to the methyl group is of considerable importance in determining the equilibria of the

  12. Equilibrium electrode U(4)-U and redox U(4)-U(3) potentials in molten alkali metal chlorides medium

    International Nuclear Information System (INIS)

    Smirnov, M.V.; Kudyakov, V.Ya.; Komarov, V.E.; Salyulev, A.B.

    1979-01-01

    Conditional standard electrode potentials of uranium are determined for diluted solutions of its tetrachloride in alkali metal chloride melts (LiCl, NaCl, NaCl-KCl, KCl, RbCl and CsCl) when using U(4) ion activity coefficient values experimentally found by the tensimetric method. These potentials shift to the electronegative side at the temperature decrease and alkali cation radius increase rsub(Msup(+)) according to the empiric ratio E*U(4)-U= -3.06+6.87x10 -4 T-(1.67-10 -4 T-0.44) 1/rsub(Msup(+)) +-0.01. The temperature dependences of formal conditional redox potentials of the U(4)-U(3) system for above melted chlorides are estimated. The E*U(4)-U(3) value also becomes more electronegative in the series LiCl, NaCl, NaCl-KCl, KCl, RbCl and CsCl. This alternation is satisfactorily described by the empiric expression E*U(4)-U(3)= -1.74+1.74x10 -4 T-(0.71x10 -4 T-0.20) 1rsub(Msup(+)) +-0.05. The calculated values Eu*(4)-U(3) are compared with those directly measured for the NaCl-KCl equimolar mixture and 3LiCl-2KCl eutectic mixture. A satisfactory confirmity has been observed

  13. Hydration to the poly(oxyethylene) derivative complexes of alkali metal ions and barium ion in 1,2-dichloroethane

    International Nuclear Information System (INIS)

    Kikuchi, Yoichi; Kubota, Mitsuru; Suzuki, Toshio; Sawada, Kiyoshi.

    1994-01-01

    A series of poly(oxyethylene) derivatives (POE compound) complexes of alkali metal and barium ions were extracted into 1,2-dichloroethane (1,2-DCE) by forming ion-pairs with picrate ion. Water molecules were coextracted into 1,2-DCE with the ion-pairs. The mean number of water molecules bound to the POE compound, X H2O,S , and its complex, X H2O,comp , in water saturated with 1,2-DCE was determined by means of aquametry. The X H2O,S value increases with the increase in the number of the oxyethylene units (EO unit) of the POE compound. The X H2O,comp value decreases in the order Li + >Na + >K + ≅Rb + ≅Cs + in any POE compound systems, and increases with the number of EO units of the POE compounds for a given metal ion. These results are interpreted by the hypothesis that the water molecules bound to the complex are those hydrated to the central metal ion, and the hydrated metal ion is surrounded by the EO chain with a helical conformation in the complex. The large number of water molecules are coordinating to the lithium ion complexes and bring about a serious distortion in the helical structure of the complexes. Because of the ion-pair formation with two picrate ions, the X H2O,comp values of barium ion complexes are smaller than those of potassium ion complexes. (author)

  14. Molecular dynamics of 18-crown-6 complexes with alkali metal cations and urea-prediction of their conformations and comparison with data from the Cambridge Structural Database

    NARCIS (Netherlands)

    Leuwerink, F.T.H.; Harkema, Sybolt; Briels, Willem J.; Feil, D.; Feil, D.

    1993-01-01

    Complexes of 18-crown-6 with alkali-metal cations (Na+, K+, and Rb+), urea, and the uncomplexed crown ether were studied in vacuo with the molecular dynamics method. Conformational data from these calculations (simulation times in the range from 6-15 ns) was compared with information from the

  15. A new route to the syntheses of alkali metal bis(fluorosulfuryl)imides: Crystal structure of LiN(SO2F)2

    Czech Academy of Sciences Publication Activity Database

    Beran, Martin; Příhoda, J.; Žák, Z.; Černík, M.

    2006-01-01

    Roč. 25, č. 6 (2006), s. 1292-1298 ISSN 0277-5387 Institutional research plan: CEZ:AV0Z40310501 Keywords : imido-bis( sulfuric acid ) difluoride * lithium bis(fluorosulfuryl)imide * alkali metal bis(fluorosulfuryl)imides Subject RIV: CA - Inorganic Chemistry Impact factor: 1.843, year: 2006

  16. On the mechanism of ionic conductivity in the alkali metal salt-polyethylene oxide systems

    International Nuclear Information System (INIS)

    Lontsov, V.V.; Kazanskij, K.S.; Shupik, A.N.

    1985-01-01

    The state and mobility of Na + and Cs + ions in the polyethylene oxide (PEO) melt using the methods of conductivity and NMR on alkali nuclei is studied. Extremely high mobilitities for CsCNS and NaI in PEO melt are noted. This is explained by transport mechanism at which the main contribution to conductivity is made by cation motion along the parts of polymer spiral by means of consequent recomplexing. It is concluded that cation motion is realized in combination with its coordination sphere determined by large fragments of polymer chain

  17. Scoping studies of vapor behavior during a severe accident in a metal-fueled reactor

    International Nuclear Information System (INIS)

    Spencer, B.W.; Marchaterre, J.F.

    1985-01-01

    Scoping calculations have been performed examining the consequences of fuel melting and pin failures for a reactivity-insertion type accident in a sodium-cooled, pool-type reactor fueled with a metal alloy fuel. The principal gas and vapor species released are shown to be Xe, Cs,and bond sodium contained within the fuel porosity. Fuel vapor pressure is insignificant, and there is no energetic fuel-coolant interaction for the conditions considered. Condensation of sodium vapor as it expands into the upper sodium pool in a jet mixing regime may occur as rapidly as the vapor emerges from the disrupted core (although reactor-material experiments are needed to confirm these high condensation rates). If the predictions of rapid direct-contact condensation can be verified experimentally for the sodium system, the implication is that the ability of vapor expansion to perform appreciable work on the system is largely eliminated. Furthermore, the ability of an expanding vapor bubble to transport fuel and fission product species to the cover gas region where they may be released to the containment is also largely eliminated. The radionuclide species except for fission gas are largely retained within the core and sodium pool

  18. Measuring the spin polarization of alkali-metal atoms using nuclear magnetic resonance frequency shifts of noble gases

    Directory of Open Access Journals (Sweden)

    X. H. Liu

    2015-10-01

    Full Text Available We report a novel method of measuring the spin polarization of alkali-metal atoms by detecting the NMR frequency shifts of noble gases. We calculated the profile of 87Rb D1 line absorption cross sections. We then measured the absorption profile of the sample cell, from which we calculated the 87Rb number densities at different temperatures. Then we measured the frequency shifts resulted from the spin polarization of the 87Rb atoms and calculated its polarization degrees at different temperatures. The behavior of frequency shifts versus temperature in experiment was consistent with theoretical calculation, which may be used as compensative signal for the NMRG closed-loop control system.

  19. Crown-Ether Derived Graphene Hybrid Composite for Membrane-Free Potentiometric Sensing of Alkali Metal Ions

    DEFF Research Database (Denmark)

    Olsen, Gunnar; Ulstrup, Jens; Chi, Qijin

    2016-01-01

    We report the design and synthesis of newly functionalized graphene hybrid material that can be used for selective membrane-free potentiometric detection of alkali metal ions, represented by potassium ions. Reduced graphene oxide (RGO) functionalized covalently by 18-crown[6] ether with a dense...... surface coverage is achieved by the introduction of a flexible linking molecule. The resulting hybrid composite is highly stable and is capable of detecting potassium ions down to micromolar ranges with a selectivity over other cations (including Ca2+, Li+, Na+, NH4+) at concentrations up to 25 m......M. This material can be combined further with disposable chips, demonstrating its promise as an effective ion-selective sensing component for practical applications....

  20. Development of processes for the production of solar grade silicon from halides and alkali metals, phase 1 and phase 2

    Science.gov (United States)

    Dickson, C. R.; Gould, R. K.; Felder, W.

    1981-01-01

    High temperature reactions of silicon halides with alkali metals for the production of solar grade silicon are described. Product separation and collection processes were evaluated, measure heat release parameters for scaling purposes and effects of reactants and/or products on materials of reactor construction were determined, and preliminary engineering and economic analysis of a scaled up process were made. The feasibility of the basic process to make and collect silicon was demonstrated. The jet impaction/separation process was demonstrated to be a purification process. The rate at which gas phase species from silicon particle precursors, the time required for silane decomposition to produce particles, and the competing rate of growth of silicon seed particles injected into a decomposing silane environment were determined. The extent of silane decomposition as a function of residence time, temperature, and pressure was measured by infrared absorption spectroscopy. A simplistic model is presented to explain the growth of silicon in a decomposing silane enviroment.

  1. Formation of amorphous metal alloys by chemical vapor deposition

    Science.gov (United States)

    Mullendore, Arthur W.

    1990-01-01

    Amorphous alloys are deposited by a process of thermal dissociation of mixtures or organometallic compounds and metalloid hydrides, e.g., transition metal carbonyl such as nickel carbonyl, and diborane. Various sizes and shapes of deposits can be achieved, including near-net-shape free standing articles, multilayer deposits, and the like. Manipulation or absence of a magnetic field affects the nature and the structure of the deposit.

  2. Purification and characterization of an extracellular, thermo-alkali-stable, metal tolerant laccase from Bacillus tequilensis SN4.

    Directory of Open Access Journals (Sweden)

    Sonica Sondhi

    Full Text Available A novel extracellular thermo-alkali-stable laccase from Bacillus tequilensis SN4 (SN4LAC was purified to homogeneity. The laccase was a monomeric protein of molecular weight 32 KDa. UV-visible spectrum and peptide mass fingerprinting results showed that SN4LAC is a multicopper oxidase. Laccase was active in broad range of phenolic and non-phenolic substrates. Catalytic efficiency (kcat/Km showed that 2, 6-dimethoxyphenol was most efficiently oxidized by the enzyme. The enzyme was inhibited by conventional inhibitors of laccase like sodium azide, cysteine, dithiothreitol and β-mercaptoethanol. SN4LAC was found to be highly thermostable, having temperature optimum at 85°C and could retain more than 80% activity at 70°C for 24 h. The optimum pH of activity for 2, 6-dimethoxyphenol, 2, 2'-azino bis[3-ethylbenzthiazoline-6-sulfonate], syringaldazine and guaiacol was 8.0, 5.5, 6.5 and 8.0 respectively. Enzyme was alkali-stable as it retained more than 75% activity at pH 9.0 for 24 h. Activity of the enzyme was significantly enhanced by Cu2+, Co2+, SDS and CTAB, while it was stable in the presence of halides, most of the other metal ions and surfactants. The extracellular nature and stability of SN4LAC in extreme conditions such as high temperature, pH, heavy metals, halides and detergents makes it a highly suitable candidate for biotechnological and industrial applications.

  3. Defect formation and desorption of metal atoms from alkali halide crystals under low energy electron bombardment studied by optical absorption and mass spectroscopy

    International Nuclear Information System (INIS)

    Seifert, N.R.

    1993-04-01

    This work presents an extensive investigation of electronically induced desorption of ground-state alkali atoms from alkali halides and for the first time correlates directly the desorption with the stability and spatial distribution of the defects formed during bombardment. The electron impact results in the formation of stable F-centers and F-center clusters in the bulk of the crystals. In striking contrast a significant metallization of the surface is observed. Even at temperatures as low as 90 deg C the metallization is achieved within the time resolution of our detection system, which can only be explained by the rapid diffusion of hot holes. Superimposed to the fast and short diffusion of hot holes is the slow F-center diffusion. Measuring the distribution of defects with low energy ion sputtering techniques indicates that at least in the case of LiF the observed diffusion constant of F-centers agrees with values derived by using methods different from that applied here. At low temperatures the formation of F-center clusters and metal on the surface dominates. Colloid formation clearly requires higher temperatures (typically around 200 deg C). This is a strong evidence that efficient F-center diffusion is necessary for the formation of metallic particles (colloids) in the bulk of the crystals. Desorption of alkali atoms from alkali halides at temperatures around room temperature is due to weakly bound alkali atoms. For elevated temperatures the stability of the metallic clusters in the bulk of the crystals (i.e. colloids) are the rate limiting process. (author)

  4. First structural evidence for multiple alkali metals between sandwich decks in a metallocene.

    Science.gov (United States)

    Jeletic, Matthew; Perras, Frédéric A; Gorelsky, Serge I; Le Roy, Jennifer J; Korobkov, Ilia; Bryce, David L; Murugesu, Muralee

    2012-07-14

    A tetralithio salt (1) derived by treating 1,4-bis(trimethylsilyl)-cyclooctatriene with (n)BuLi serves as the first structural evidence for a multi-alkali metallocene. Single-crystal XRD confirms two Li(+) each asymmetrically bind to η(3) and η(4) between two COT'' rings and two Li(+) terminally bind to η(3). Solid-state NMR studies confirm the presence of two distinct lithium ion sites while the solution NMR studies suggest the formation of an (COT'' dianion) ion-pair in solution. Further treating of the tetralithio salt with NaCl leads to linear sodium polymeric chains. Therefore, simply changing the ionic radius changes the molecular structure.

  5. Allosteric coextraction of sodium and metal ions with calix[4]arene derivatives 2: first numerical evaluation for the allosteric effect on alkali metal extraction with crossed carboxylic acid type calix[4]arenes.

    Science.gov (United States)

    Yoneyama, Tomoaki; Sadamatsu, Hirotoshi; Kuwata, Shigemasa; Kawakita, Hidetaka; Ohto, Keisuke

    2012-01-15

    Crossed carboxylic acid types of calix[4]arene derivatives with two longer carboxylic acids and two acetic acids at the distal position have been prepared to investigate the solvent extraction of three alkali metal ions in individual and competitive systems. These extractants selectively extracted sodium ions among other alkali ions at low pH, and the first extracted sodium ion acted as a "trigger" causing a change in extraction ability and metal selectivity. Spacer groups with different lengths induced significant differences in the extraction behavior. The extraction equilibrium constants, K(ex1) and K(ex2), between the present cyclic tetramers and the extracted two alkali metal ions were estimated in order to obtain a numerical evaluation of the allosteric effect. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Absorption Spectroscopy of Rubidium in an Alkali Metal Dispenser Cell and Bleached Wave Analysis

    Science.gov (United States)

    2015-03-26

    hydride precipitates and soot, which cloud cell windows and interfere with the optical path. For these reasons, there has been some investigation...surface, necessitating the use of a getter (often a zirconium- aluminum alloy) to deplete contaminant concentrations, but for rubidium spectroscopy...outgasses hydrogen gas at a rate of approximately 10 -12 9 torr/s/cm 2 [12]. Hydrogen gas reacts with rubidium vapor to form rubidium hydride

  7. Modeling film uniformity and symmetry in ionized metal physical vapor deposition with cylindrical targets

    International Nuclear Information System (INIS)

    Lu Junqing; Yang Lin; Yoon, Jae Hong; Cho, Tong Yul; Tao Guoqing

    2008-01-01

    Severe asymmetry of the metal deposits on the trench sidewalls occurs near the wafer edge during low pressure ionized metal physical vapor deposition of Cu seed layer for microprocessor interconnects. To investigate this process and mitigate the asymmetry, an analytical view factor model based on the analogy between metal sputtering and diffuse thermal radiation was constructed to investigate deposition uniformity and symmetry for cylindrical target sputtering in low pressure (below 0.1 Pa) ionized Cu physical vapor deposition. The model predictions indicate that as the distance from the cylindrical target to wafer increases, the metal film thickness becomes more uniform across the wafer and the asymmetry of the metal deposits at the wafer edge increases significantly. These trends are similar to those for planar targets. To minimize the asymmetry, the height of the cylindrical target should be kept at a minimum. For cylindrical targets, the outward-facing sidewall of the trench could receive more direct Cu fluxes than the inward-facing one when the target to wafer distance is short. The predictions also indicate that increasing the diameter of the cylindrical target could significantly reduce the asymmetry in metal deposits at the wafer edge and make the film thickness more uniform across the wafer

  8. Analysis of triacetone triperoxide complexes with alkali metal ions by electrospray and extractive electrospray ionisation combined with ion mobility spectrometry and mass spectrometry.

    Science.gov (United States)

    Hill, Alex R; Edgar, Mark; Chatzigeorgiou, Maria; Reynolds, James C; Kelly, Paul F; Creaser, Colin S

    2015-01-01

    The complexation of triacetone triperoxide (TATP) with a range of alkali metals has been studied by electrospray ionisation-mass spectrometry yield [M+Cat](+) ions for all of the alkali metals. The formation of [2TATP+Li+LiX](+) (X = Br, Cl) sandwich complexes was also observed. Collision cross- sections for the lithium-containing complexes of TATP were measured by travelling wave ion mobility spectrometry mass spectrometry, and compared well with computationally determined structures. Extractive electrospray ionisation (EESI) using a lithium doped electrospray is demonstrated for the detection of TATP vapours desorbed from a metal surface. The limit of detection for EESI was shown to be 20 ng using the [TATP+Li](+) ion.

  9. Enhanced brightness of organic light-emitting diodes based on Mg:Ag cathode using alkali metal chlorides as an electron injection layer

    International Nuclear Information System (INIS)

    Zou Ye; Deng Zhenbo; Xu Denghui; Lü Zhaoyue; Yin Yuehong; Du Hailiang; Chen Zheng; Wang Yongsheng

    2012-01-01

    Different thicknesses of cesium chloride (CsCl) and various alkali metal chlorides were inserted into organic light-emitting diodes (OLEDs) as electron injection layers (EILs). The basic structure of OLED is indium tin oxide (ITO)/N,N′-diphenyl-N,N′-bis(1-napthyl-phenyl)-1.1′-biphenyl-4.4′-diamine (NPB)/tris-(8-hydroxyquinoline) aluminum (Alq 3 )/Mg:Ag/Ag. The electroluminescent (EL) performance curves show that both the brightness and efficiency of the OLEDs can be obviously enhanced by using a thin alkali metal chloride layer as an EIL. The electron injection barrier height between the Alq 3 layer and Mg:Ag cathode is reduced by inserting a thin alkali metal chloride as an EIL, which results in enhanced electron injection and electron current. Therefore, a better balance of hole and electron currents at the emissive interface is achieved and consequently the brightness and efficiency of OLEDs are improved. - Highlights: ► Alkaline metal chlorides were used as electron injection layers in organic light-emitting diodes based on Mg:Ag cathode. ► Brightness and efficiency of OLEDs with alkaline metal chlorides as electron injection layers were all greatly enhanced. ► The Improved OLED performance was attributed to the possible interfacial chemical reaction. ► Electron-only devices are fabricated to demonstrate the electron injection enhancement.

  10. Catalytic growth of metallic tungsten whiskers based on the vapor-solid-solid mechanism

    International Nuclear Information System (INIS)

    Wang, S L; He, Y H; Huang, B Y; Zou, J; Wang, Y; Huang, H; Liu, C T; Liaw, P K

    2008-01-01

    Metallic W whiskers with tip diameters of 50-250 nm and lengths of 2-4 μm have been successfully synthesized in large quantities using Co-Ni alloyed catalysts. The relatively low growth temperature of 850 deg. C and the large catalyst size (over 100 nm) suggest that the growth of the W whiskers must be governed by the vapor-solid-solid mechanism. Our results show that the vapor-solid-solid model is suitable not only for the growth of nano-scaled whiskers with diameters below 100 nm, but also for submicro-scaled whiskers with diameters well above 100 nm. This technique has great potential to synthesize well controlled metallic whiskers

  11. Structure of metal β-diketonates and their enthalpies of vaporization

    International Nuclear Information System (INIS)

    Domrachev, G.A.; Sevast'yanov, V.G.; Zakharov, L.N.; Krasnodubskaya, S.V.; AN SSSR, Moscow. Inst. Obshchej i Neorganicheskoj Khimii)

    1987-01-01

    Using the method of additive schemes in combinaion with the structural estimation of the degree of screening of the central atom and other elements of β-diketonate molecule while analyzing the experimental enthalpies of vaporization, the contributions of separate fragments of complexes into the enthalpy of vaporization are found. It is shown that energies of intermolecular interaction in a condensed phase of monomeric metal β-diketonates with identical substituents do not depend on the central atom type. The enthalpies of dimer dissociation in a series of rare earth dipivaloylmethanates calculated. The proposed approach is advisable fo selecting forms of metal β-diketonates, the most suitable for the purposes of deep purificaion, which are characterized by maximum chemical and physico-chemical selectivity with respect to impurities, chemical inertness to equipment material, container, etc

  12. Theoretical study of adsorption of water vapor on surface of metallic uranium

    CERN Document Server

    Xiong Bi Tao; Xue Wei Dong; Zhu Zheng He; Jiang Gang; Wang Hong Yan; Gao Tao

    2002-01-01

    According to the experimental data, there is an intermediate substance that formed in the initial stage of oxidation reaction when water vapor is absorbed onto the metallic uranium. The minimum energy of UOH sub 2 witch C sub 2 subupsilon configuration is obtained in the state of sup 5 A sub 1 by B3LYP method of the density function theory (DFT), which is consistent with that by statics of atoms and molecules reaction (AMRS) and group theory. The results from calculations indicate that the adsorption of water vapor on the metallic uranium is an exothermic reaction and that the adsorbed amount decreases with the elevated temperatures. The adsorptive heat at 1 atm is -205.4747 kJ centre dot mol sup - sup 1 , which indicates a typical chemical adsorption

  13. Organogel-derived Covalent-Noncovalent Hybrid Polymers as Alkali Metal Ion Scavengers for Partial Deionization of Water.

    Science.gov (United States)

    Prathap, Annamalai; Raju, Cijil; Sureshan, Kana M

    2018-04-12

    We show that crown ethers (CEs) 1-5 congeal both polar and non-polar solvents via their self-assembly through weak non-covalent interactions (NCI) such as CH...O and CH...π interactions. Di-isopropylidene-mannitol (6) is a known gelator that self-assembles through stronger OH...O H-bonding. These two gelators together also congeal non-polar solvents via their individual self-assembly. The gelator 6 self-assembles swiftly to fibers, which act as templates and attract CE to their surface through H-bonding and thereby facilitate their self-assembly through weak NCI. Polymerization of styrene gels made from CE and 6 followed by the washing off of the sacrificial gelator 6 yields robust porous polystyrene-crown ether hybrid matrices (PCH), having pore-exposed CEs. These PCHs were not only efficient in sequestering alkali metal ions from aqueous solutions but also can be recycled. This novel use of organogels for making solid sorbents for metal ion scavenging might be of great interest.

  14. Copper-vapor-assisted chemical vapor deposition for high-quality and metal-free single-layer graphene on amorphous SiO2 substrate.

    Science.gov (United States)

    Kim, Hyungki; Song, Intek; Park, Chibeom; Son, Minhyeok; Hong, Misun; Kim, Youngwook; Kim, Jun Sung; Shin, Hyun-Joon; Baik, Jaeyoon; Choi, Hee Cheul

    2013-08-27

    We report that high-quality single-layer graphene (SLG) has been successfully synthesized directly on various dielectric substrates including amorphous SiO2/Si by a Cu-vapor-assisted chemical vapor deposition (CVD) process. The Cu vapors produced by the sublimation of Cu foil that is suspended above target substrates without physical contact catalyze the pyrolysis of methane gas and assist nucleation of graphene on the substrates. Raman spectra and mapping images reveal that the graphene formed on a SiO2/Si substrate is almost defect-free and homogeneous single layer. The overall quality of graphene grown by Cu-vapor-assisted CVD is comparable to that of the graphene grown by regular metal-catalyzed CVD on a Cu foil. While Cu vapor induces the nucleation and growth of SLG on an amorphous substrate, the resulting SLG is confirmed to be Cu-free by synchrotron X-ray photoelectron spectroscopy. The SLG grown by Cu-vapor-assisted CVD is fabricated into field effect transistor devices without transfer steps that are generally required when SLG is grown by regular CVD process on metal catalyst substrates. This method has overcome two important hurdles previously present when the catalyst-free CVD process is used for the growth of SLG on fused quartz and hexagonal boron nitride substrates, that is, high degree of structural defects and limited size of resulting graphene, respectively.

  15. Problems of hydrogen - water vapor - inert gas mixture use in heavy liquid metal coolant technology

    International Nuclear Information System (INIS)

    Ul'yanov, V.V.; Martynov, P.N.; Gulevskij, V.A.; Teplyakov, Yu.A.; Fomin, A.S.

    2014-01-01

    The reasons of slag deposit formation in circulation circuits with heavy liquid metal coolants, which can cause reactor core blockage, are considered. To prevent formation of deposits hydrogen purification of coolant and surfaces of circulation circuit is used. It consists in introduction of gaseous mixtures hydrogen - water vapor - rare gas (argon or helium) directly into coolant flow. The principle scheme of hydrogen purification and the processes occurring during it are under consideration. Measures which make it completely impossible to overlap of the flow cross section of reactor core, steam generators, pumps and other equipment by lead oxides in reactor facilities with heavy liquid metal coolants are listed [ru

  16. Thermal expansion of NZP-family alkali-metal (Na, K) zirconium phosphates

    International Nuclear Information System (INIS)

    Orlova, A.I.; Kemenov, D.V.; Pet'kov, V.I.; Samojlov, S.G.; Kazantsev, G.N.

    2000-01-01

    By means of high-temperature X-ray diffraction one investigated into thermal expansion of alkali-zirconium phosphates crystallizing in NaZr 2 (PO 4 ) 3 structure type within 20-700 deg C temperature range. One synthesized phosphates of A x Zr 2.25-0.25x (PO 4 ) 3 type two series where A-Na (x = 0.5; 1.0; 2.0; 3.0; 4.0; 5.0) and K (x = 1.0; 3.0; 5.0). One calculated for them a and c parameters of the elementary cells and α a and α c linear expansion temperature coefficients. Anisotropy of thermal expansion the maximum one for AZr 2 (PO 4 ) 3 and Na 5 Zr(PO 4 ) 3 phosphates was determined. K 5 Zr(PO 4 ) 3 compound was characterized by the minimum thermal expansion at the near-zero anisotropy of Na 5 Zr(PO 4 ) 3 [ru

  17. Clustering of nucleosides in the presence of alkali metals: Biologically relevant quartets of guanosine, deoxyguanosine and uridine observed by ESI-MS/MS.

    Science.gov (United States)

    Aggerholm, Tenna; Nanita, Sergio C; Koch, Kim J; Cooks, R Graham

    2003-01-01

    Electrospray ionization (ESI) mass spectra of nucleosides, recorded in the presence of alkali metals, display alkali metal ion-bound quartets and other clusters that may have implications for understanding non-covalent interactions in DNA and RNA. The tetramers of guanosine and deoxyguanosine and also their metaclusters (clusters of clusters), cationized by alkali metals, were observed as unusually abundant magic number clusters. The observation of these species in the gas phase parallels previous condensed-phase studies, which show that guanine derivatives can form quartets and metaclusters of quartets in solution in the presence of metal cations. This parallel behavior and also internal evidence suggest that bonding in the guanosine tetramers involves the bases rather than the sugar units. The nucleobases thymine and uracil are known to form magic number pentameric adducts with K+, Cs+ and NH4+ in the gas phase. In sharp contrast, we now show that the nucleosides uridine and deoxythymidine do not form the pentameric clusters characteristic of the corresponding bases. More subtle effects of the sugars are evident in the fact that adenosine and cytidine form numerous higher order clusters with alkali metals, whereas deoxyadenosine and deoxycytidine show no clustering. It is suggested that hydrogen bonding between the bases in the tetramers of dG and rG are the dominant interactions in the clusters, hence changing the ribose group to deoxyribose (and vice versa) generally has little effect. However, the additional hydroxyl group of RNA nucleosides enhances the non-selective formation of higher-order aggregates for adenosine and cytidine and results in the lack of highly stable magic number clusters. Some clusters are the result of aggregation in the course of ionization (ESI) whereas others appear to be intrinsic to the solution being examined. Copyright 2003 John Wiley & Sons, Ltd.

  18. Origin of low sodium capacity in graphite and generally weak substrate binding of Na and Mg among alkali and alkaline earth metals.

    Science.gov (United States)

    Liu, Yuanyue; Merinov, Boris V; Goddard, William A

    2016-04-05

    It is well known that graphite has a low capacity for Na but a high capacity for other alkali metals. The growing interest in alternative cation batteries beyond Li makes it particularly important to elucidate the origin of this behavior, which is not well understood. In examining this question, we find a quite general phenomenon: among the alkali and alkaline earth metals, Na and Mg generally have the weakest chemical binding to a given substrate, compared with the other elements in the same column of the periodic table. We demonstrate this with quantum mechanics calculations for a wide range of substrate materials (not limited to C) covering a variety of structures and chemical compositions. The phenomenon arises from the competition between trends in the ionization energy and the ion-substrate coupling, down the columns of the periodic table. Consequently, the cathodic voltage for Na and Mg is expected to be lower than those for other metals in the same column. This generality provides a basis for analyzing the binding of alkali and alkaline earth metal atoms over a broad range of systems.

  19. Density functional study of isoguanine tetrad and pentad sandwich complexes with alkali metal ions.

    Science.gov (United States)

    Meyer, Michael; Steinke, Thomas; Sühnel, Jürgen

    2007-02-01

    Isoguanine tetraplexes and pentaplexes contain two or more stacked polyads with intercalating metal ions. We report here the results of a density functional study of sandwiched isoguanine tetrad and pentad complexes consisting of two polyads with Na(+), K(+) and Rb(+) ions at the B3LYP level. In comparison to single polyad metal ion complexes, there is a trend towards increased non-planarity of the polyads in the sandwich complexes. In general, the pentad sandwiches have relatively planar polyad structures, whereas the tetrad complexes contain highly non-planar polyad building blocks. As in other sandwich complexes and in metal ion complexes with single polyads, the metal ion-base interaction energy plays an essential role. In iG sandwich structures, this interaction energy is slightly larger than in the corresponding guanine sandwich complexes. Because the base-base interaction energy is even more increased in passing from guanine to isoguanine, the isoguanine sandwiches are thus far the only examples where the base-base interaction energy is larger than the base-metal ion interaction energy. Stacking interactions have been studied in smaller models consisting of two bases, retaining the geometry from the complete complex structures. From the data obtained at the B3LYP and BH&H levels and with Møller-Plesset perturbation theory, one can conclude that the B3LYP method overestimates the repulsion in stacked base dimers. For the complexes studied in this work, this is only of minor importance because the direct inter-tetrad or inter-pentad interaction is supplemented by a strong metal ion-base interaction. Using a microsolvation model, the metal ion preference K(+) approximately Rb(+) > Na(+) is found for tetrad complexes. On the other hand, for pentads the ordering is Rb(+) > K(+) > Na(+). In the latter case experimental data are available that agree with this prediction.

  20. Toward high value sensing: monolayer-protected metal nanoparticles in multivariable gas and vapor sensors.

    Science.gov (United States)

    Potyrailo, Radislav A

    2017-08-29

    For detection of gases and vapors in complex backgrounds, "classic" analytical instruments are an unavoidable alternative to existing sensors. Recently a new generation of sensors, known as multivariable sensors, emerged with a fundamentally different perspective for sensing to eliminate limitations of existing sensors. In multivariable sensors, a sensing material is designed to have diverse responses to different gases and vapors and is coupled to a multivariable transducer that provides independent outputs to recognize these diverse responses. Data analytics tools provide rejection of interferences and multi-analyte quantitation. This review critically analyses advances of multivariable sensors based on ligand-functionalized metal nanoparticles also known as monolayer-protected nanoparticles (MPNs). These MPN sensing materials distinctively stand out from other sensing materials for multivariable sensors due to their diversity of gas- and vapor-response mechanisms as provided by organic and biological ligands, applicability of these sensing materials for broad classes of gas-phase compounds such as condensable vapors and non-condensable gases, and for several principles of signal transduction in multivariable sensors that result in non-resonant and resonant electrical sensors as well as material- and structure-based photonic sensors. Such features should allow MPN multivariable sensors to be an attractive high value addition to existing analytical instrumentation.

  1. A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide.

    Science.gov (United States)

    Ng, Chee Koon; Wu, Jie; Hor, T S Andy; Luo, He-Kuan

    2016-09-27

    Binary catalyst systems comprising a cationic Ru-CNC pincer complex and an alkali metal salt were developed for selective hydroboration of CO 2 utilizing pinacolborane at r.t. and 1 atm CO 2 , with the combination of [Ru(CNC Bn )(CO) 2 (H)][PF 6 ] and KOCO 2 t Bu producing formoxyborane in 76% yield. A bicyclic catalytic mechanism was proposed and discussed.

  2. Ga-In liquid metal nanoparticles prepared by physical vapor deposition

    Directory of Open Access Journals (Sweden)

    Fan Yu

    2018-02-01

    Full Text Available Controlled synthesis and appropriate characterization of nanoscale particles of gallium-based liquid metals are critical to fulfilling their broad range of applications in the field of flexible, stretchable, and printable micro-/nanoelectronics. Herein, we report a new way to synthesize surfactant-free gallium-indium nanoparticles with controlled particle size on a variety of substrates through a facile physical vapor deposition method. It was found that with prolonged deposition time the liquid metal nanoparticles gradually grew from near-monodispersed small particles with a diameter of ~25 nm to bimodal distributed particles. A nucleation, growth, ripening and merging process was proposed to explain the observed evolution of particle size. Atomic force microscopy measurement indicates that the fabricated liquid metal nanoparticles demonstrate elastic deformation with a certain range of loads and the scanned particle size is dependent on the applied loads. We further investigated the gradual breaking process of the core-shell structured liquid metal nanoparticles, which was evidenced by multiple kinks on the force-separation curve. This work presents a new bottom-up approach to prepare nanoscale liquid metal particles and demonstrates that atomic force microscopy is a suitable technique to characterize the synthesized liquid metal nanoparticles. Keywords: Gallium-Indium alloy, Atomic force microscopy, Liquid metal, Nanoparticle

  3. Optimized random phase approximation for the structure of liquid alkali metals as electron-ion plasmas

    International Nuclear Information System (INIS)

    Senatore, G.; Tosi, M.P.; Trieste Univ.

    1981-08-01

    The purpose of this letter is to stress that the way towards an unconventional optimized-random-phase-approximation (ORPA) approach to the structure of liquid metals is indicated, and in fact already a good first-order solution for such an approach is provided

  4. Van der Waals coefficients for alkali metal clusters and their size ...

    Indian Academy of Sciences (India)

    . 1000 atoms) easily, thereby allowing us to study the evolution of van der Waals coefficients with the size of the clusters. For details of the ETF method and its application to study alkali–metal cluster, we refer the reader to [9,10,27–29]. In the.

  5. Ab Initio Study of Chemical Reactions of Cold SrF and CaF Molecules with Alkali-Metal and Alkaline-Earth-Metal Atoms: The Implications for Sympathetic Cooling.

    Science.gov (United States)

    Kosicki, Maciej Bartosz; Kędziera, Dariusz; Żuchowski, Piotr Szymon

    2017-06-01

    We investigate the energetics of the atom exchange reaction in the SrF + alkali-metal atom and CaF + alkali-metal atom systems. Such reactions are possible only for collisions of SrF and CaF with the lithium atoms, while they are energetically forbidden for other alkali-metal atoms. Specifically, we focus on SrF interacting with Li, Rb, and Sr atoms and use ab initio methods to demonstrate that the SrF + Li and SrF + Sr reactions are barrierless. We present potential energy surfaces for the interaction of the SrF molecule with the Li, Rb, and Sr atoms in their energetically lowest-lying electronic spin states. The obtained potential energy surfaces are deep and exhibit profound interaction anisotropies. We predict that the collisions of SrF molecules in the rotational or Zeeman excited states most likely have a strong inelastic character. We discuss the prospects for the sympathetic cooling of SrF and CaF molecules using ultracold alkali-metal atoms.

  6. A review of the high temperature oxidation of uranium oxides in molten salts and in the solid state to form alkali metal uranates, and their composition and properties

    Science.gov (United States)

    Griffiths, Trevor R.; Volkovich, Vladimir A.

    An extensive review of the literature on the high temperature reactions (both in melts and in the solid state) of uranium oxides (UO 2, U 3O 8 and UO 3) resulting in the formation of insoluble alkali metal (Li to Cs) uranates is presented. Their uranate(VI) and uranate(V) compounds are examined, together with mixed and oxygen-deficient uranates. The reactions of uranium oxides with carbonates, oxides, per- and superoxides, chlorides, sulfates, nitrates and nitrites under both oxidising and non-oxidising conditions are critically examined and systematised, and the established compositions of a range of uranate(VI) and (V) compounds formed are discussed. Alkali metal uranates(VI) are examined in detail and their structural, physical, thermodynamic and spectroscopic properties considered. Chemical properties of alkali metal uranates(VI), including various methods for their reduction, are also reported. Errors in the current theoretical treatment of uranate(VI) spectra are identified and the need to develop routes for the preparation of single crystals is stressed.

  7. Cleavage reactions of the complex ions derived from self-complementary deoxydinucleotides and alkali-metal ions using positive ion electrospray ionization with tandem mass spectrometry.

    Science.gov (United States)

    Xiang, Yun; Abliz, Zeper; Takayama, Mitsuo

    2004-05-01

    The dissociation reactions of the adduct ions derived from the four self-complementary deoxydinucleotides, d(ApT), d(TpA), d(CpG), d(GpC), and alkali-metal ions were studied in detail by positive ion electrospray ionization multiple-stage mass spectrometry (ESI-MS(n)). For the [M + H](+) ions of the four deoxydinucleotides, elimination of 5'-terminus base or loss of both of 5'-terminus base and a deoxyribose were the major dissociation pathway. The ESI-MS(n) spectra showed that Li(+), Na(+), and Cs(+) bind to deoxydinucleotides mainly by substituting the H(+) of phosphate group, and these alkali-metal ions preferred to bind to pyrimidine bases rather than purine bases. For a given deoxydinucleotide, the dissociation pathway of [M + K](+) ions differed clearly from that of [M + Li](+), [M + Na](+), and [M + Cs](+) ions. Some interesting and characteristic cleavage reactions were observed in the product-ion spectra of [M + K](+) ions, including direct elimination of deoxyribose and HPO(3) from molecular ions. The fragmentation behavior of the [M + K](+) and [M + W](+) (W = Li, Na, Cs) adduct ions depend upon the sequence of bases, the interaction between alkali-metal ions and nucleobases, and the steric hindrance caused by bases.

  8. New type of complex alkali and alkaline earth metal borates with isolated (B12O24)12) anionic group.

    Science.gov (United States)

    Wu, Hongping; Yu, Hongwei; Pan, Shilie; Jiao, Anqing; Han, Jian; Wu, Kui; Han, Shujuan; Li, Hongyi

    2014-03-28

    Compounds with isolated anionic groups often exhibit special linear and nonlinear optical properties and possess potential applications such as birefringence, second harmonic generation and stimulated Raman scattering crystals. In this paper, two new alkali and alkaline earth mixed-metal borates, Li3KB4O8 and LiNa2Sr8B12O24F6Cl, with isolated (B12O24)(12-) anionic groups have been successfully synthesized by spontaneous crystallization. Their structures were determined by single crystal X-ray diffraction and they both crystallize in the same space group, R3[combining macron]. More interestingly, further structure comparison shows that the discovered anhydrous borates with the (B12O24)(12-) groups also crystallize in the same space group R3[combining macron], which is related with the local symmetry of the (B12O24)(12-) groups. These structural features suggest that the crystal structures of the family of compounds depend more on their anionic groups. In addition, the property characterizations of the two new borates were investigated by TG-DSC, IR and UV-vis-NIR diffuse reflectance.

  9. Room temperature deintercalation of alkali metal atoms from epitaxial graphene by formation of charge-transfer complexes

    Energy Technology Data Exchange (ETDEWEB)

    Shin, H.-C.; Ahn, S. J.; Kim, H. W.; Moon, Y.; Rai, K. B. [Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Woo, S. H. [College of Pharmacy, Chungnam National University, Daejeon 305–764 (Korea, Republic of); Ahn, J. R., E-mail: jrahn@skku.edu [Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); SAINT, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2016-08-22

    Atom (or molecule) intercalations and deintercalations have been used to control the electronic properties of graphene. In general, finite energies above room temperature (RT) thermal energy are required for the intercalations and deintercalations. Here, we demonstrate that alkali metal atoms can be deintercalated from epitaxial graphene on a SiC substrate at RT, resulting in the reduction in density of states at the Fermi level. The change in density of states at the Fermi level at RT can be applied to a highly sensitive graphene sensor operating at RT. Na atoms, which were intercalated at a temperature of 80 °C, were deintercalated at a high temperature above 1000 °C when only a thermal treatment was used. In contrast to the thermal treatment, the intercalated Na atoms were deintercalated at RT when tetrafluorotetracyanoquinodimethane (F4-TCNQ) molecules were adsorbed on the surface. The RT deintercalation occurred via the formation of charge-transfer complexes between Na atoms and F4-TCNQ molecules.

  10. CO2 gasification reactivity of biomass char: catalytic influence of alkali, alkaline earth and transition metal salts.

    Science.gov (United States)

    Lahijani, Pooya; Zainal, Zainal Alimuddin; Mohamed, Abdul Rahman; Mohammadi, Maedeh

    2013-09-01

    This study investigates the influence of alkali (Na, K), alkaline earth (Ca, Mg) and transition (Fe) metal nitrates on CO2 gasification reactivity of pistachio nut shell (PNS) char. The preliminary gasification experiments were performed in thermogravimetric analyzer (TGA) and the results showed considerable improvement in carbon conversion; Na-char>Ca-char>Fe-char>K-char>Mg-char>raw char. Based on TGA studies, NaNO3 (with loadings of 3-7 wt%) was selected as the superior catalyst for further gasification studies in bench-scale reactor; the highest reactivity was devoted to 5 wt% Na loaded char. The data acquired for gasification rate of catalyzed char were fitted with several kinetic models, among which, random pore model was adopted as the best model. Based on obtained gasification rate constant and using the Arrhenius plot, activation energy of 5 wt% Na loaded char was calculated as 151.46 kJ/mol which was 53 kJ/mol lower than that of un-catalyzed char. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Performance and impedance studies of thin, porous molybdenum and tungsten electrodes for the alkali metal thermoelectric converter

    Science.gov (United States)

    Wheeler, B. L.; Williams, R. M.; Jeffries-Nakamura, B.; Lamb, J. L.; Loveland, M. E.; Bankston, C. P.; Cole, T.

    1988-01-01

    Columnar, porous, magnetron-sputtered molybdenum and tungsten films show optimum performance as alkali metal thermoelectric converter electrodes at thicknesses less than 1.0 micron when used with molybdenum or nickel current collector grids. Power densities of 0.40 W/sq cm for 0.5-micron molybdenum films at 1200 K and 0.35 W/sq cm for 0.5-micron tungsten films at 1180 K were obtained at electrode maturity after 40-90 h. Sheet resistances of magnetron sputter deposited films on sodium beta-double-prime-alumina solid electrolyte (BASE) substrates were found to increase very steeply as thickness is decreased below about 0.3-double-prime 0.4-micron. The ac impedance data for these electrodes have been interpreted in terms of contributions from the bulk BASE and the porous electrode/BASE interface. Voltage profiles of operating electrodes show that the total electrode area, of electrodes with thickness less than 2.0 microns, is not utilized efficiently unless a fairly fine (about 1 x 1 mm) current collector grid is employed.

  12. Hydrogen storage property of alkali and alkaline-earth metal atoms decorated C24 fullerene: A DFT study

    Science.gov (United States)

    Zhang, Yafei; Cheng, Xinlu

    2018-04-01

    The hydrogen storage behavior of alkali and alkaline-earth metal (AM = Li, Na, K, Mg, Ca) atoms decorated C24 fullerene was investigated by using density functional theory (DFT) study. Our results indicate that the AM atoms prefer to adsorb atop the center of tetragon of C24 fullerene with the largest binding energy than other possible adsorption sites. Moreover, the hydrogen storage gravimetric density of 24H2/6Li/C24, 24H2/6Na/C24 and 36H2/6Ca/C24 configurations reaches up to 12.7 wt%, 10.1 wt% and 12 wt%, higher than the year 2020 target from the US department of energy (DOE). Also, the average adsorption energies of H2 molecules of the 24H2/6Li/C24, 24H2/6Na/C24 and 36H2/6Ca/C24 configurations are -0.198 eV/H2, -0.164 eV/H2 and -0.138 eV/H2, locate the desirable range under the physical adsorption at near ambient conditions. These findings will have important implications on designing new hydrogen storage materials in the future.

  13. Development of a wet vapor homogeneous liquid metal MHD power system. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Branover, H.; Unger, Y.; El-Boher, A.; Schweitzer, H.

    1991-09-01

    A feasibility study for the approval of liquid metal seeds recovery from a liquid metal vapor-inert gas mixture was conducted and presented in this report. The research activity included background studies on processes relating to mixing stream condenser performance, parametric studies and its experimental validation. The condensation process under study includes mass transfer phenomena combined with heat transfer and phase change. Numerical methods were used in order to solve the dynamic equations and to carry out the parametric study as well as the experimental data reduction. The MSC performance is highly effected by droplet diameter, thus the possibility of atomizing liquid metals were experimentally investigated. The results are generalized and finally used for a set of recommendations by which the recovery of seeds is expected to be feasible.

  14. Construction of thermionic alkali-ion sources

    International Nuclear Information System (INIS)

    Ul Haq, F.

    1986-01-01

    A simple technique is described by which singly charged alkali ions of K, Na, Li, Rb and Cs are produced by heating ultra-pure chemical salts of different alkali metals on tungsten filaments without employing a temperature measuring device. The character of alkali-ion currents at different heating powers and the remarkably constant ion emission current for prolonged periods are discussed. (author)

  15. X-ray and neutron diffraction studies of some liquid alkali metals and alloys

    International Nuclear Information System (INIS)

    Huijben, M.J.

    1978-01-01

    Experimental techniques and correction procedures have been searched for, which allow a reliable and accurate determination of the structure factors of simple liquid metals, particularly in the small-angle region. A study of binary alloys was carried out and showed that clustering of like atoms (a tendency to phase separation) occurs, indicating special structural aspects. The densities of Na-K, Na-Cs, K-Rb alloys were also measured. (C.F.)

  16. Heavy main-group iodometallates hybridized by alkali metal via 1,10 ...

    Indian Academy of Sciences (India)

    throline, bipyridine, terpyridine; x =2, 3; n =2, 3);17–26 c. rare earth metal organic complexes, [Ln(L)x]3+ (Ln. =Y, Tb, Nd; L=DMF and/or DMSO; x =7, 8).27–30. In these systems, most of the second ... Mengfan Yin et al. (H3O)]·H2O}n (2). Their band gaps, fluorescence and thermal stabilities are also reported and discussed.

  17. Electrolytic method to make alkali alcoholates using ion conducting alkali electrolyte/separator

    Science.gov (United States)

    Joshi, Ashok V [Salt Lake City, UT; Balagopal, Shekar [Sandy, UT; Pendelton, Justin [Salt Lake City, UT

    2011-12-13

    Alkali alcoholates, also called alkali alkoxides, are produced from alkali metal salt solutions and alcohol using a three-compartment electrolytic cell. The electrolytic cell includes an anolyte compartment configured with an anode, a buffer compartment, and a catholyte compartment configured with a cathode. An alkali ion conducting solid electrolyte configured to selectively transport alkali ions is positioned between the anolyte compartment and the buffer compartment. An alkali ion permeable separator is positioned between the buffer compartment and the catholyte compartment. The catholyte solution may include an alkali alcoholate and alcohol. The anolyte solution may include at least one alkali salt. The buffer compartment solution may include a soluble alkali salt and an alkali alcoholate in alcohol.

  18. Magnetron target designs to improve wafer edge trench filling in ionized metal physical vapor deposition

    International Nuclear Information System (INIS)

    Lu Junqing; Yoon, Jae-Hong; Shin, Keesam; Park, Bong-Gyu; Yang Lin

    2006-01-01

    Severe asymmetry of the metal deposits on the trench sidewalls occurs near the wafer edge during low pressure ionized metal physical vapor deposition of Cu seed layer for microprocessor interconnects. To investigate this process and mitigate the asymmetry, an analytical view factor model based on the analogy between metal sputtering and diffuse thermal radiation was constructed. The model was validated based on the agreement between the model predictions and the reported experimental values for the asymmetric metal deposition at trench sidewalls near the wafer edge for a 200 mm wafer. This model could predict the thickness of the metal deposits across the wafer, the symmetry of the deposits on the trench sidewalls at any wafer location, and the angular distributions of the metal fluxes arriving at any wafer location. The model predictions for the 300 mm wafer indicate that as the target-to-wafer distance is shortened, the deposit thickness increases and the asymmetry decreases, however the overall uniformity decreases. Up to reasonable limits, increasing the target size and the sputtering intensity for the outer target portion significantly improves the uniformity across the wafer and the symmetry on the trench sidewalls near the wafer edge

  19. The Synthesis and Characterization of Ionic Liquids for Alkali-Metal Batteries and a Novel Electrolyte for Non-Humidified Fuel Cells

    Science.gov (United States)

    Tucker, Telpriore G.

    This thesis focused on physicochemical and electrochemical projects directed towards two electrolyte types: 1) class of ionic liquids serving as electrolytes in the catholyte for alkali-metal ion conduction in batteries and 2) gel membrane for proton conduction in fuel cells; where overall aims were encouraged by the U.S. Department of Energy. Large-scale, sodium-ion batteries are seen as global solutions to providing undisrupted electricity from sustainable, but power-fluctuating, energy production in the near future. Foreseen ideal advantages are lower cost without sacrifice of desired high-energy densities relative to present lithium-ion and lead-acid battery systems. Na/NiCl2 (ZEBRA) and Na/S battery chemistries, suffer from high operation temperature (>300ºC) and safety concerns following major fires consequent of fuel mixing after cell-separator rupturing. Initial interest was utilizing low-melting organic ionic liquid, [EMI+][AlCl 4-], with well-known molten salt, NaAlCl4, to create a low-to-moderate operating temperature version of ZEBRA batteries; which have been subject of prior sodium battery research spanning decades. Isothermal conductivities of these electrolytes revealed a fundamental kinetic problem arisen from "alkali cation-trapping effect" yet relived by heat-ramping >140ºC. Battery testing based on [EMI+][FeCl4 -] with NaAlCl4 functioned exceptional (range 150-180ºC) at an impressive energy efficiency >96%. Newly prepared inorganic ionic liquid, [PBr4+][Al2Br7-]:NaAl2Br 7, melted at 94ºC. NaAl2Br7 exhibited super-ionic conductivity 10-1.75 Scm-1 at 62ºC ensued by solid-state rotator phase transition. Also improved thermal stability when tested to 265ºC and less expensive chemical synthesis. [PBr4 +][Al2Br7-] demonstrated remarkable, ionic decoupling in the liquid-state due to incomplete bromide-ion transfer depicted in NMR measurements. Fuel cells are electrochemical devices generating electrical energy reacting hydrogen/oxygen gases

  20. Vanadium oxide based cpd. useful as a cathode active material - is used in lithium or alkali metal batteries to prolong life cycles

    DEFF Research Database (Denmark)

    1997-01-01

    A mixt. of metallic iron particles and vanadium pentoxide contg. V in its pentavalent state in a liq. is reacted to convert at least some of the pentavalent V to its tetravalent state and form a gel. The liq. phase is then sepd. from the oxide based gel to obtain a solid material(I) comprising Fe......, V and oxygen where at least some of the V is in the tetravalent state. USE-(I) is a cathode active material in electric current producing storage cells. ADVANTAGE-Use of (I) in Li or alkali metal batteries gives prolonged life cycles.Storage cells using (I) have improved capacity during charge...

  1. Note: Design principles of a linear array multi-channel effusive metal-vapor atom source.

    Science.gov (United States)

    Jana, B; Majumder, A; Thakur, K B; Das, A K

    2013-10-01

    Atomic beams can easily be produced by allowing atoms to effuse through a channel. In an earlier investigation [A. Majumder et al., Vacuum 83, 989 (2009)], we had designed, fabricated, and characterized an effusive metal-vapor source using collinear-array of multi-channel. In this note, we describe the theoretical basis of designing the source. Atom density in atomic beam has been estimated using a set of analytical expressions for long-channel operated in transparent mode. Parametric studies on aspect ratio of channel, inter-channel separation, beam width, and vertical distance from the source are carried out. They are useful in providing physical picture and optimizing design parameters.

  2. Modeling technique of capacitive discharge pumping of metal vapor lasers for electrode capacitance optimization.

    Science.gov (United States)

    Gubarev, F A; Evtushenko, G S; Vuchkov, N K; Sukhanov, V B; Shiyanov, D V

    2012-05-01

    To estimate optimum gas discharge tube (GDT) electrode capacitance of metal vapor lasers (MVLs) pumped by a longitudinal capacitive discharge, we offer to use series connection of capacitors to the electrodes of a conventionally pumped GDT with inner electrodes. It has been demonstrated that the maximum output power in CuBr lasers is obtained when the capacitances of high-voltage and ground electrodes are equal. When using a model circuit an average output power reaches 12 W that suggests the possibility of generating high average output power (>10 W) in MVLs pumped using a capacitive discharge.

  3. Metal oxide absorbents for regenerative carbon dioxide and water vapor removal for advanced portable life support systems

    Science.gov (United States)

    Hart, Joan M.; Borghese, Joseph B.; Chang, Craig H.; Stonesifer, Greg T.

    1991-01-01

    Recent studies of Allied Signal metal oxide based absorbents demonstrated that these absorbents offer a unique capability to regeneratively remove both metabolic carbon dioxide and water vapor from breathing air; previously, metal oxides were considered only for the removal of CO2. The concurrent removal of CO2 and H2O vapor can simplify the astronaut Portable Life Support System (PLSS) by combining the CO2 and humidity control functions into one regenerative component. The use of metal oxide absorbents for removal of both CO2 ad H2O vapor in the PLSS is the focus of an ongoing program. The full scale Metal Oxide Carbon dioxide and Humidity Remover (MOCHR) and regeneration unit is described.

  4. Interaction of Cu(+) with cytosine and formation of i-motif-like C-M(+)-C complexes: alkali versus coinage metals.

    Science.gov (United States)

    Gao, Juehan; Berden, Giel; Rodgers, M T; Oomens, Jos

    2016-03-14

    The Watson-Crick structure of DNA is among the most well-known molecular structures of our time. However, alternative base-pairing motifs are also known to occur, often depending on base sequence, pH, or the presence of cations. Pairing of cytosine (C) bases induced by the sharing of a single proton (C-H(+)-C) may give rise to the so-called i-motif, which occurs primarily in expanded trinucleotide repeats and the telomeric region of DNA, particularly at low pH. At physiological pH, silver cations were recently found to stabilize C dimers in a C-Ag(+)-C structure analogous to the hemiprotonated C-dimer. Here we use infrared ion spectroscopy in combination with density functional theory calculations at the B3LYP/6-311G+(2df,2p) level to show that copper in the 1+ oxidation state induces an analogous formation of C-Cu(+)-C structures. In contrast to protons and these transition metal ions, alkali metal ions induce a different dimer structure, where each ligand coordinates the alkali metal ion in a bidentate fashion in which the N3 and O2 atoms of both cytosine ligands coordinate to the metal ion, sacrificing hydrogen-bonding interactions between the ligands for improved chelation of the metal cation.

  5. High temperature vapor pressures of stainless steel type 1.4970 and of some other pure metals from laser evaporation

    International Nuclear Information System (INIS)

    Bober, M.; Singer, J.

    1984-10-01

    For the safety analysis of nuclear reactors vapor pressure data of stainless steel are required up to temperatures exceeding 4000 K. In analogy to the classic boiling point method a new technique was developed to measure the high-temperature vapor pressures of stainless steel and other metals from laser vaporization. A fast pyrometer, an ion current probe and an image converter camera are used to detect incipient boiling from the time-temperature curve. The saturated-vapor pressure curves of stainless steel (Type 1.4970), being a cladding material of the SNR 300 breeder reactor, and of molybdenum are experimentally determined in the temperature ranges of 2800-3900 K and 4500-5200 K, respectively. The normal boiling points of iron, nickel, titanium, vanadium and zirconium are verified. Besides, spectral emissivity values of the liquid metals are measured at the pyrometer wavelengths of 752 nm and/or 940 nm. (orig.) [de

  6. Study of Six Green Insensitive High Energetic Coordination Polymers Based on Alkali/Alkali-Earth Metals and 4,5-Bis(tetrazol-5-yl)-2 H-1,2,3-triazole.

    Science.gov (United States)

    Chen, Dong; Jing, Dong; Zhang, Qi; Xue, Xianggui; Gou, Shaohua; Li, Hongzhen; Nie, Fude

    2017-12-14

    Constructing insensitive high-performance energetic coordination polymers (ECPs) with alkali/alkali-earth metal ions and a nitrogen-rich organic backbone has been proved to be a feasible strategy in this work. Six diverse dimensional novel ECPs (compounds 1-6) were successfully synthesized from Na I , Cs I , Ca II , Sr II , Ba II ions and a nitrogen-rich triheterocyclic 4,5-bis(tetrazol-5-yl)-2 H-1,2,3-triazole (H 3 BTT). All compounds show outstanding stability and low sensitivity, the thermal stability of these ECPs are significantly improved as the structural reinforcement increases from 1D to 3D, in which the decomposition temperature of 3D Ba II based compound 6 is as high as 397 °C. Long-term storage experiments show that compounds 5 and 6 are stable enough at high temperature. Moreover, the six compounds hold considerable detonation performances, in which Ca II based compound 5 possesses the detonation velocity of 9.12 km s -1 , along with the detonation pressure of 34.51 GPa, exceeding those of most energetic coordination polymers. Burn tests further certify that the six compounds can be versatile pyrotechnics. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Structured nanocarbon on various metal foils by microwave plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Rius, G; Yoshimura, M

    2013-01-01

    We present a versatile process for the engineering of nanostructures made of crystalline carbon on metal foils. The single step process by microwave plasma-enhance chemical vapor deposition is demonstrated for various substrate materials, such as Ni or Cu. Either carbon nanotubes (CNT) or carbon nanowalls (CNW) are obtained under same growth conditions and without the need of additional catalyst. The use of spacer and insulator implies a certain control over the kind of allotropes that are obtained. High density and large surface area are morphological characteristics of the thus obtained C products. The possibility of application on many metals, and in the alloy composition, on as-delivered commercially available foils indicates that this strategy can be adapted to a bunch of specific applications, while the production of C nanostructures is of remarkable simplicity.

  8. Thermodynamic investigation of the effect of alkali metal impuries on the processing of aluminum and magnesium alloys

    Science.gov (United States)

    Zhang, Shengjun

    2006-12-01

    of aluminum and magnesium alloys. As the first step of the thermodynamic description of the high-order system, the constitutive-binary systems were modeled in the present work using the CALPHAD technique combined with first-principles calculations. Then, ternaries and higher order systems can be modeled. For ternary systems without experimental data, the thermodynamic description is extrapolated by combining three constitutive-binary systems. Alkali-metal induced high temperature embrittlement (HTE) and loss of ductility were investigated in Al-Li, Al-Mg and Mg-Li alloys. It was discovered that the alkali-metal-rich liquid-2 phase is the cause of HTE and the loss of ductility is proportional to the mole fraction of the liquid phase and the grain size. The calculated results are consistent with experimental observations in the literature and were used to determine HTE safe and sensitive zones, maximum and critical hot-rolling temperatures and the maximum allowable Na content in alloys, which can be used to industrial processing of Al and Mg alloys. The degree of HTE is proportional to the mole fraction of the liquid-2 phase and the grain size.

  9. Alloying in an Intercalation Host: Metal Titanium Niobates as Anodes for Rechargeable Alkali-Ion Batteries.

    Science.gov (United States)

    Das, Suman; Swain, Diptikanta; Araujo, Rafael B; Shi, Songxin; Ahuja, Rajeev; Row, Tayur N Guru; Bhattacharyya, Aninda J

    2018-02-02

    We discuss here a unique flexible non-carbonaceous layered host, namely, metal titanium niobates (M-Ti-niobate, M: Al 3+ , Pb 2+ , Sb 3+ , Ba 2+ , Mg 2+ ), which can synergistically store both lithium ions and sodium ions via a simultaneous intercalation and alloying mechanisms. M-Ti-niobate is formed by ion exchange of the K + ions, which are specifically located inside galleries between the layers formed by edge and corner sharing TiO 6 and NbO 6 octahedral units in the sol-gel synthesized potassium titanium niobate (KTiNbO 5 ). Drastic volume changes (approximately 300-400 %) typically associated with an alloying mechanism of storage are completely tackled chemically by the unique chemical composition and structure of the M-Ti-niobates. The free space between the adjustable Ti/Nb octahedral layers easily accommodates the volume changes. Due to the presence of an optimum amount of multivalent alloying metal ions (50-75 % of total K + ) in the M-Ti-niobate, an efficient alloying reaction takes place directly with ions and completely eliminates any form of mechanical degradation of the electroactive particles. The M-Ti-niobate can be cycled over a wide voltage range (as low as 0.01 V) and displays remarkably stable Li + and Na + ion cyclability (>2 Li + /Na + per formula unit) for widely varying current densities over few hundreds to thousands of successive cycles. The simultaneous intercalation and alloying storage mechanisms is also studied within the density functional theory (DFT) framework. DFT expectedly shows a very small variation in the volume of Al-titanium niobate following lithium alloying. Moreover, the theoretical investigations also conclusively support the occurrence of the alloying process of Li ions with the Al ions along with the intercalation process during discharge. The M-Ti-niobates studied here demonstrate a paradigm shift in chemical design of electrodes and will pave the way for the development of a multitude of improved electrodes

  10. Soil sampling and analysis plan for the 3718-F Alkali Metal Treatment and Storage Facility closure activities

    Energy Technology Data Exchange (ETDEWEB)

    Sonnichsen, J.C.

    1997-05-01

    Amendment V.13.B.b to the approved closure plan (DOE-RL 1995a) requires that a soil sampling and analysis plan be prepared and submitted to the Washington State Department of Ecology (Ecology) for review and approval. Amendment V.13.B.c requires that a diagram of the 3718-F Alkali Metal Treatment and Storage Facility unit (the treatment, storage, and disposal [TSD] unit) boundary that is to be closed, including the maximum extent of operation, be prepared and submitted as part is of the soil sampling and analysis plan. This document describes the sampling and analysis that is to be performed in response to these requirements and amends the closure plan. Specifically, this document supersedes Section 6.2, lines 43--46, and Section 7.3.6 of the closure plan. Results from the analysis will be compared to cleanup levels identified in the closure plan. These cleanup levels will be established using residential exposure assumptions in accordance with the Model Toxics Control Act (MTCA) Cleanup Regulation (Washington Administrative Code [WAC] 173-340) as required in Amendment V.13.B.I. Results of all sampling, including the raw analytical data, a summary of analytical results, a data validation package, and a narrative summary with conclusions will be provided to Ecology as specified in Amendment V.13.B.e. The results and process used to collect and analyze the soil samples will be certified by a licensed professional engineer. These results and a certificate of closure for the balance of the TSD unit, as outlined in Chapter 7.0 of the approved closure plan (storage shed, concrete pad, burn building, scrubber, and reaction tanks), will provide the basis for a closure determination.

  11. Soil sampling and analysis plan for the 3718-F Alkali Metal Treatment and Storage Facility closure activities

    International Nuclear Information System (INIS)

    Sonnichsen, J.C.

    1997-01-01

    Amendment V.13.B.b to the approved closure plan (DOE-RL 1995a) requires that a soil sampling and analysis plan be prepared and submitted to the Washington State Department of Ecology (Ecology) for review and approval. Amendment V.13.B.c requires that a diagram of the 3718-F Alkali Metal Treatment and Storage Facility unit (the treatment, storage, and disposal [TSD] unit) boundary that is to be closed, including the maximum extent of operation, be prepared and submitted as part is of the soil sampling and analysis plan. This document describes the sampling and analysis that is to be performed in response to these requirements and amends the closure plan. Specifically, this document supersedes Section 6.2, lines 43--46, and Section 7.3.6 of the closure plan. Results from the analysis will be compared to cleanup levels identified in the closure plan. These cleanup levels will be established using residential exposure assumptions in accordance with the Model Toxics Control Act (MTCA) Cleanup Regulation (Washington Administrative Code [WAC] 173-340) as required in Amendment V.13.B.I. Results of all sampling, including the raw analytical data, a summary of analytical results, a data validation package, and a narrative summary with conclusions will be provided to Ecology as specified in Amendment V.13.B.e. The results and process used to collect and analyze the soil samples will be certified by a licensed professional engineer. These results and a certificate of closure for the balance of the TSD unit, as outlined in Chapter 7.0 of the approved closure plan (storage shed, concrete pad, burn building, scrubber, and reaction tanks), will provide the basis for a closure determination

  12. The emission spectroscopy for evaluation of concentration of the metal vapor concentration in tokamak plasma

    International Nuclear Information System (INIS)

    Sarakovskis, A.; Gromuls, I.; Tale, I.

    2004-01-01

    Full text: Evaluation of the absolute concentration of the impurity metal vapors in plasma using emission spectroscopy requires development of the principles and procedure of in situ calibration of equipment. Several approaches can be used for calibration of the equipment. In the case the emission rate of single metal atom under ionizing conditions is known, the calibration of the spectroscopic equipment reduces to the calibration in radiometric units (irradiance). For unknown emission rate the routine calibration procedure involves use of the set of etalons of material under investigation with known concentration of impurity metal. For evaluation of impurity concentration in plasma it is necessary to develop a corresponding plasma source having certain plasma parameters - temperature and concentration of electrons and metal vapors in concentration, which can be measured independent procedure. Present report deals with problems of estimation of Ga impurity concentration in ISSTOK ( Portugal) tokamak plasma using decay data of atom emission lines. Emission spectra of Ga atoms show that collisions with hydrogen electrons and ions results in ionization of Ga followed by multi step radiative recombination. The main emission lines corresponds to the capture of electron to the 4s 2 5p (639 nm), transition 4s 2 5p - 4s 2 5s (1,211 μm ); and transition to the ground state 4s 2 5s - 4s 2 4p (403 nm). Some of the excited state lifetimes obtained from decay kinetics are reported. Analysis of emission line intensity ratios together with lifetime data will allow elaborate the procedure for evaluation of Ga impurity concentration in the tokamak plasma

  13. Collision Welding of Dissimilar Materials by Vaporizing Foil Actuator: A Breakthrough Technology for Dissimilar Metal Joining

    Energy Technology Data Exchange (ETDEWEB)

    Daehn, Glenn S. [The Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering; Vivek, Anupam [The Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering; Liu, Bert C. [The Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

    2016-09-30

    This work demonstrated and further developed Vaporizing Foil Actuator Welding (VFAW) as a viable technique for dissimilar-metal joining for automotive lightweighting applications. VFAW is a novel impact welding technology, which uses the pressure developed from electrically-assisted rapid vaporization of a thin aluminum foil (the consumable) to launch and ultimately collide two of more pieces of metal to create a solid-state bond between them. 18 dissimilar combinations of automotive alloys from the steel, aluminum and magnesium alloy classes were screened for weldability and characterized by metallography of weld cross sections, corrosion testing, and mechanical testing. Most combinations, especially a good number of Al/Fe pairs, were welded successfully. VFAW was even able to weld combinations of very high strength materials such as 5000 and 6000 series aluminum alloys to boron and dual phase steels, which is difficult to impossible by other joining techniques such as resistance spot welding, friction stir welding, or riveting. When mechanically tested, the samples routinely failed in a base metal rather than along the weld interface, showing that the weld was stronger than either of the base metals. As for corrosion performance, a polymer-based protective coating was used to successfully combat galvanic corrosion of 5 Al/Fe pairs through a month-long exposure to warm salt fog. In addition to the technical capabilities, VFAW also consumes little energy compared to conventional welding techniques and requires relatively light, flexible tooling. Given the technical and economic advantages, VFAW can be a very competitive joining technology for automotive lightweighting. The success of this project and related activities has resulted in substantial interest not only within the research community but also various levels of automotive supply chain, which are collaborating to bring this technology to commercial use.

  14. Complex formation during dissolution of metal oxides in molten alkali carbonates

    DEFF Research Database (Denmark)

    Li, Qingfeng; Borup, Flemming; Petrushina, Irina

    1999-01-01

    Dissolution of metal oxides in molten carbonates relates directly to the stability of materials for electrodes and construction of molten carbonate fuel cells. In the present work the solubilities of PbO, NiO, Fe2O3,and Bi2O3 in molten Li/K carbonates have been measured at 650 degrees C under...... carbon dioxide atmosphere. It is found that the solubilities of NiO and PbO decrease while those of Fe2O3 and Bi2O3 remain approximately constant as the lithium mole fraction increases from 0.43 to 0.62 in the melt. At a fixed composition of the melt, NiO and PbO display both acidic and basic dissolution...... as the partial pressure of carbon dioxide varies. By combination of solubility and electromotive force measurements, a model is constructed assuming the dissolution involves complex formation. The possible species for lead are proposed to be [Pb(CO3)(2)](-2) and/or [Pb(CO3)(3)](-4). A similar complex chemistry...

  15. Synthesis of Li2PtH6 using high pressure: Completion of the homologous series A2PtH6 (A=alkali metal)

    International Nuclear Information System (INIS)

    Puhakainen, Kati; Stoyanov, Emil; Evans, Michael J.; Leinenweber, Kurt; Haeussermann, Ulrich

    2010-01-01

    Li 2 PtH 6 , the missing member of the complex transition metal hydride series A 2 PtH 6 (A=alkali metal), was prepared by reacting mixtures of LiH and Pt in the presence of BH 3 NH 3 as hydrogen source at pressures above 8 GPa. According to powder X-ray diffraction analysis, Li 2 PtH 6 is isostructural to its heavier homologues and crystallizes in the cubic K 2 PtCl 6 structure (space group Fm3-bar m, a=6.7681(3), Z=4). However, PtH 6 2- octahedral complexes in Li 2 PtH 6 approach each other closely and its structure may likewise be regarded as a defective perovskite structure where half of the octahedrally coordinated atoms (cations) are missing. The IR spectrum of Li 2 PtH 6 reveals the Pt-H T 1u stretch and bend at 1840 and 889 cm -1 , respectively. - Graphical abstract: Li 2 PtH 6 , the missing start member of the complex metal hydride series A 2 PtH 6 (A=alkali metal) has been prepared by high pressure hydrogenation. In contrast to the heavier homologues, PtH 6 2- octahedral units in Li 2 PtH 6 are not well separated and H atoms form a substructure closely corresponding to that of O atoms in cubic perovskite.

  16. Use of alkali metal salts to prepare high purity single-walled carbon nanotube solutions and thin films

    Science.gov (United States)

    Ashour, Rakan F.

    Single-walled carbon nanotubes (SWCNTs) display interesting electronic and optical properties desired for many advanced thin film applications, such as transparent conductive electrodes or thin-film transistors. Large-scale production of SWCNTs generally results in polydispersed mixtures of nanotube structures. Since SWCNT electronic character (conducting or semiconducting nature) depends on the nanotube structure, application performance is being held back by this inability to discretely control SWCNT synthesis. Although a number of post-production techniques are able to separate SWCNTs based on electronic character, diameter, or chirality, most still suffer from the disadvantage of high costs of materials, equipment, or labor intensity to be relevant for large-scale production. On the other hand, chromatographic separation has emerged as a method that is compatible with large scale separation of metallic and semiconducting SWCNTs. In this work, SWCNTs, in an aqueous surfactant suspension of sodium dodecyl sulfate (SDS), are separated by their electronic character using a gel chromatography process. Metallic SWCNTs (m-SWCNTs) are collected as initial fractions since they show minimum interaction with the gel medium, whereas, semiconducting SWCNTs (sc- SWCNTs) remain adsorbed to the gel. The process of sc-SWCNT retention in the gel is found to be driven by the packing density of SDS around the SWCNTs. Through a series of separation experiments, it is shown that sc-SWCNTs can be eluted from the gel simply by disturbing the configuration of the SDS/SWCNT micellar structure. This is achieved by either introducing a solution containing a co-surfactant, such as sodium cholate (SC), or solutions of alkali metal ionic salts. Analysis of SWCNT suspensions by optical absorption provides insights into the effect of changing the metal ion (M+ = Li+, Na+, and K+) in the eluting solution. Salts with smaller metal ions (e.g. Li+) require higher concentrations to achieve

  17. Suitable alkaline for graphene peeling grown on metallic catalysts using chemical vapor deposition

    International Nuclear Information System (INIS)

    Karamat, S.; Sonuşen, S.; Çelik, Ü.; Uysallı, Y.; Oral, A.

    2016-01-01

    Graphical abstract: - Highlights: • Graphene layers were grown on Pt and Cu foil via ambient pressure chemical vapor deposition method and for the delicate removal of graphene from metal catalysts, electrolysis method was used by using different alkaline (sodium hydroxide, potassium hydroxide, lithium hydroxide and barium hydroxide). • The delamination speed of PMMA/graphene stack was higher during the KOH and LiOH electrolysis as compare to NaOH and Ba(OH) 2 . Ba(OH) 2 is not advisable because of the residues left on the graphene surface which would further trapped in between graphene and SiO 2 /Si surface after transfer. The average peeling time in case of Pt electrode is ∼6 min for KOH and LiOH and ∼15 min for NaOH and Ba(OH) 2 . • Electrolysis method also works for the Cu catalyst. The peeling of graphene was faster in the case of Cu foil due to small size of bubbles which moves faster between the stack and the electrode surface. The average peeling time was ∼3–5 min. • XPS analysis clearly showed that the Pt substrates can be re-used again. Graphene layer was transferred to SiO 2 /Si substrates and to the flexible substrate by using the same peeling method. - Abstract: In chemical vapor deposition, the higher growth temperature roughens the surface of the metal catalyst and a delicate method is necessary for the transfer of graphene from metal catalyst to the desired substrates. In this work, we grow graphene on Pt and Cu foil via ambient pressure chemical vapor deposition (AP-CVD) method and further alkaline water electrolysis was used to peel off graphene from the metallic catalyst. We used different electrolytes i.e., sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH) and barium hydroxide Ba(OH) 2 for electrolysis, hydrogen bubbles evolved at the Pt cathode (graphene/Pt/PMMA stack) and as a result graphene layer peeled off from the substrate without damage. The peeling time for KOH and LiOH was ∼6 min and for Na

  18. Dipole polarizability of alkali-metal (Na, K, Rb)–alkaline-earth-metal (Ca, Sr) polar molecules: Prospects for alignment

    Energy Technology Data Exchange (ETDEWEB)

    Gopakumar, Geetha, E-mail: geetha@tmu.ac.jp; Abe, Minori; Hada, Masahiko [Department of Chemistry, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397 (Japan); JST, CREST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Kajita, Masatoshi [National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795 (Japan)

    2014-06-14

    Electronic open-shell ground-state properties of selected alkali-metal–alkaline-earth-metal polar molecules are investigated. We determine potential energy curves of the {sup 2}Σ{sup +} ground state at the coupled-cluster singles and doubles with partial triples (CCSD(T)) level of electron correlation. Calculated spectroscopic constants for the isotopes ({sup 23}Na, {sup 39}K, {sup 85}Rb)–({sup 40}Ca, {sup 88}Sr) are compared with available theoretical and experimental results. The variation of the permanent dipole moment (PDM), average dipole polarizability, and polarizability anisotropy with internuclear distance is determined using finite-field perturbation theory at the CCSD(T) level. Owing to moderate PDM (KCa: 1.67 D, RbCa: 1.75 D, KSr: 1.27 D, RbSr: 1.41 D) and large polarizability anisotropy (KCa: 566 a.u., RbCa: 604 a.u., KSr: 574 a.u., RbSr: 615 a.u.), KCa, RbCa, KSr, and RbSr are potential candidates for alignment and orientation in combined intense laser and external static electric fields.

  19. Capacitance of the double electrical layer on the copper-group metals in molten alkali metal halides

    Science.gov (United States)

    Kirillova, E. V.; Stepanov, V. P.

    2016-08-01

    The electrochemical impedance is measured to study the capacitance of the double electrical layer of metallic Au, Ag, and Cu as a function of potential and temperature in nine molten salts, namely, the chlorides, bromides, and iodides of sodium, potassium, and cesium. The C- E curve of a gold electrode has an additional minimum in the anodic branch. This minimum for silver is less pronounced and is only observed at low ac signal frequencies in cesium halides. The additional minimum is not detected for copper in any salt under study. This phenomenon is explained on the assumption that the adsorption of halide anions on a positively charged electrode surface has a predominantly chemical rather than an electrostatic character. The specific adsorption in this case is accompanied by charge transfer through the interface and the formation of an adsorbent-adsorbate covalent bond.

  20. Mechanism on heavy metals vaporization from municipal solid waste fly ash by MgCl₂⋅6H₂O.

    Science.gov (United States)

    Yu, Jie; Sun, Lushi; Ma, Chuan; Qiao, Yu; Xiang, Jun; Hu, Song; Yao, Hong

    2016-03-01

    This work aims to study the mechanism of heavy metals vaporization by MgCl2⋅6H2O. Firstly, the decomposition mechanism of MgCl2⋅6H2O was investigated by thermodynamic equilibrium calculations, XRD and TG. Upon heating, MgCl2⋅6H2O went through the processes of dehydration and hydrolysis simultaneously accompanied by the release of HCl between 150 and 500°C. At temperature higher than 500°C, Mg(OH)Cl gradually release part of HCl. MgCl2⋅6H2O followed the similar processes of decomposition at both oxidative and reductive atmospheres. In oxidative atmosphere, vaporization of Zn and Cu was significantly accelerated by MgCl2⋅6H2O. However, in inert atmosphere, vaporization of Cu was not promoted since copper chloride was only stable in oxidative atmosphere. Under slow heating condition, vaporization of heavy metals were close to that under fast heating condition. This may be partially attributed to that most heavy metals already reacted with HCl forming metal chlorides below 500°C, which can be vaporized at higher temperature. Moreover, the Mg(OH)Cl contributed to release HCl up to 800°C. At such high temperature, the metal chlorides continue to be formed and then vaporized. After treatment, the leaching concentration of heavy metals from treated fly ashes were much lower than that from raw fly ash and met the regulatory limit of leachate. Since a large amount of MgSiO3 were formed during thermal treatment, the fly ash treated with MgCl2⋅6H2O can be used as raw materials for glass-ceramics production. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Ligand design for alkali-metal-templated self-assembly of unique high-nuclearity CuII aggregates with diverse coordination cage units: crystal structures and properties.

    Science.gov (United States)

    Du, Miao; Bu, Xian-He; Guo, Ya-Mei; Ribas, Joan

    2004-03-19

    The construction of two unique, high-nuclearity Cu(II) supramolecular aggregates with tetrahedral or octahedral cage units, [(mu(3)-Cl)[Li subset Cu(4)(mu-L(1))(3)](3)](ClO(4))(8)(H(2)O)(4.5) (1) and [[Na(2) subset Cu(12)(mu-L(2))(8)(mu-Cl)(4)](ClO(4))(8)(H(2)O)(10)(H(3)O(+))(2)](infinity) (2) by alkali-metal-templated (Li(+) or Na(+)) self-assembly, was achieved by the use of two newly designed carboxylic-functionalized diazamesocyclic ligands, N,N'-bis(3-propionyloxy)-1,4-diazacycloheptane (H(2)L(1)) or 1,5-diazacyclooctane-N,N'-diacetate acid (H(2)L(2)). Complex 1 crystallizes in the trigonal R3c space group (a = b = 20.866(3), c = 126.26(4) A and Z = 12), and 2 in the triclinic P1 space group (a = 13.632(4), b = 14.754(4), c = 19.517(6) A, alpha = 99.836(6), beta = 95.793(5), gamma = 116.124(5) degrees and Z = 1). By subtle variation of the ligand structures and the alkali-metal templates, different polymeric motifs were obtained: a dodecanuclear architecture 1 consisting of three Cu(4) tetrahedral cage units with a Li(+) template, and a supramolecular chain 2 consisting of two crystallographically nonequivalent octahedral Cu(6) polyhedra with a Na(+) template. The effects of ligand functionality and alkali metal template ions on the self-assembly processes of both coordination supramolecular aggregates, and their magnetic behaviors are discussed in detail.

  2. Cation-pi interactions with a model for the side chain of tryptophan: structures and absolute binding energies of alkali metal cation-indole complexes.

    Science.gov (United States)

    Ruan, Chunhai; Yang, Zhibo; Hallowita, Nuwan; Rodgers, M T

    2005-12-22

    Threshold collision-induced dissociation techniques are employed to determine bond dissociation energies (BDEs) of mono- and bis-complexes of alkali metal cations, Li+, Na+, K+, Rb+, and Cs+, with indole, C8H7N. The primary and lowest energy dissociation pathway in all cases is endothermic loss of an intact indole ligand. Sequential loss of a second indole ligand is observed at elevated energies for the bis-complexes. Density functional theory calculations at the B3LYP/6-31G level of theory are used to determine the structures, vibrational frequencies, and rotational constants of these complexes. Theoretical BDEs are determined from single point energy calculations at the MP2(full)/6-311+G(2d,2p) level using the B3LYP/6-31G* geometries. The agreement between theory and experiment is very good for all complexes except Li+ (C8H7N), where theory underestimates the strength of the binding. The trends in the BDEs of these alkali metal cation-indole complexes are compared with the analogous benzene and naphthalene complexes to examine the influence of the extended pi network and heteroatom on the strength of the cation-pi interaction. The Na+ and K+ binding affinities of benzene, phenol, and indole are also compared to those of the aromatic amino acids, phenylalanine, tyrosine, and tryptophan to elucidate the factors that contribute to the binding in complexes to the aromatic amino acids. The nature of the binding and trends in the BDEs of cation-pi complexes between alkali metal cations and benzene, phenol, and indole are examined to help understand nature's preference for engaging tryptophan over phenylalanine and tyrosine in cation-pi interactions in biological systems.

  3. Analyzing relationships between surface perturbations and local chemical reactivity of metal sites: Alkali promotion of O2 dissociation on Ag(111)

    Science.gov (United States)

    Xin, Hongliang; Linic, Suljo

    2016-06-01

    Many commercial heterogeneous catalysts are complex structures that contain metal active sites promoted by multiple additives. Developing fundamental understanding about the impact of these perturbations on the local surface reactivity is crucial for catalyst development and optimization. In this contribution, we develop a general framework for identifying underlying mechanisms that control the changes in the surface reactivity of a metal site (more specifically the adsorbate-surface interactions) upon a perturbation in the local environment. This framework allows us to interpret fairly complex interactions on metal surfaces in terms of specific, physically transparent contributions that can be evaluated independently of each other. We use Cs-promoted dissociation of O2 as an example to illustrate our approach. We concluded that the Cs adsorbate affects the outcome of the chemical reaction through a strong alkali-induced electric field interacting with the static dipole moment of the O2/Ag(111) system.

  4. Estance of gold in molten LiCl and the effect of the nature of cation on the estance zero potentials of Au in molten alkali metal chlorides

    Science.gov (United States)

    Pastukhov, Yu. G.

    2017-08-01

    The dependences estance vs. potential in molten LiCl are obtained. They have three zeros of estance near the melting temperature of the salt. When the temperature increases by 400 K, only one cathode zero is retained for equilibrium estance. A comparison of the potentials of this zero of estance in a row of alkali metal chlorides at the same temperature indicates their nonmonotonic dependence on the cation radius, in contrast to the potentials of the ECC maxima of liquid Pb, Bi, and In and the PZC of gold in this row.

  5. Affinity capillary electrophoresis and density functional theory employed for the characterization of hexaarylbenzene-based receptor complexation with alkali metal ions

    Czech Academy of Sciences Publication Activity Database

    Ehala, Sille; Toman, Petr; Rathore, R.; Makrlík, E.; Kašička, Václav

    2011-01-01

    Roč. 32, č. 9 (2011), s. 981-987 ISSN 0173-0835 R&D Projects: GA ČR(CZ) GA203/08/1428; GA ČR(CZ) GA203/09/0675; GA ČR(CZ) GAP205/10/2280; GA AV ČR 1ET400500402 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z40500505 Keywords : affinity capillary electrophoresis * alkali metal ions * binding constant Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.303, year: 2011

  6. ACE applied to the quantitative characterization of benzo-18-crown-6-ether binding with alkali metal ions in a methanol-water solvent system

    Czech Academy of Sciences Publication Activity Database

    Ehala, Sille; Makrlík, E.; Toman, Petr; Kašička, Václav

    2010-01-01

    Roč. 31, č. 4 (2010), s. 702-708 ISSN 0173-0835 R&D Projects: GA ČR(CZ) GA203/08/1428; GA ČR(CZ) GA203/09/0675; GA AV ČR 1ET400500402 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z40500505 Keywords : affinity capillary electrophoresis * alkali metal ions * binding constant Subject RIV: CB - Analytical Chemistry , Separation Impact factor: 3.569, year: 2010

  7. Thermal stability of multilayer graphene films synthesized by chemical vapor deposition and stained by metallic impurities.

    Science.gov (United States)

    Kahng, Yung Ho; Lee, Sangchul; Park, Woojin; Jo, Gunho; Choe, Minhyeok; Lee, Jong-Hoon; Yu, Hyunung; Lee, Takhee; Lee, Kwanghee

    2012-02-24

    Thermal stability is an important property of graphene that requires thorough investigation. This study reports the thermal stability of graphene films synthesized by chemical vapor deposition (CVD) on catalytic nickel substrates in a reducing atmosphere. Electron microscopies, atomic force microscopy, and Raman spectroscopy, as well as electronic measurements, were used to determine that CVD-grown graphene films are stable up to 700 °C. At 800 °C, however, graphene films were etched by catalytic metal nanoparticles, and at 1000 °C many tortuous tubular structures were formed in the film and carbon nanotubes were formed at the film edges and at catalytic metal-contaminated sites. Furthermore, we applied our pristine and thermally treated graphene films as active channels in field-effect transistors and characterized their electrical properties. Our research shows that remnant catalytic metal impurities play a critical role in damaging graphene films at high temperatures in a reducing atmosphere: this damage should be considered in the quality control of large-area graphene films for high temperature applications.

  8. In vitro studies on silver implanted pure iron by metal vapor vacuum arc technique.

    Science.gov (United States)

    Huang, Tao; Cheng, Yan; Zheng, Yufeng

    2016-06-01

    Pure iron has been verified as a promising biodegradable metal for absorbable cardiovascular stent usage. However, the degradation rate of pure iron is too slow. To accelerate the degradation of the surface of pure iron, silver ions were implanted into pure iron by metal vapor vacuum arc (MEVVA) source at an extracted voltage of 40keV. The implanted influence was up to 2×10(17)ions/cm(2). The composition and depth profiles, corrosion behavior and biocompatibility of Ag ion implanted pure iron were investigated. The implantation depths of Ag was around 60nm. The element Ag existed as Ag2O in the outermost layer, then gradually transited to metal atoms in zero valent state with depth increase. The implantation of Ag ions accelerated the corrosion rate of pure iron matrix, and exhibited much more uniform corrosion behavior. For cytotoxicity assessment, the implantation of Ag ions slightly decreased the viability of all kinds of cell lines used in these tests. The hemolysis rate of Ag ion implanted pure iron was lower than 2%, which was acceptable, whereas the platelet adhesion tests indicated the implantation of Ag ions might increase the risk of thrombosis. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. An efficient laser vaporization source for chemically modified metal clusters characterized by thermodynamics and kinetics

    Science.gov (United States)

    Masubuchi, Tsugunosuke; Eckhard, Jan F.; Lange, Kathrin; Visser, Bradley; Tschurl, Martin; Heiz, Ulrich

    2018-02-01

    A laser vaporization cluster source that has a room for cluster aggregation and a reactor volume, each equipped with a pulsed valve, is presented for the efficient gas-phase production of chemically modified metal clusters. The performance of the cluster source is evaluated through the production of Ta and Ta oxide cluster cations, TaxOy+ (y ≥ 0). It is demonstrated that the cluster source produces TaxOy+ over a wide mass range, the metal-to-oxygen ratio of which can easily be controlled by changing the pulse duration that influences the amount of reactant O2 introduced into the cluster source. Reaction kinetic modeling shows that the generation of the oxides takes place under thermalized conditions at less than 300 K, whereas metal cluster cores are presumably created with excess heat. These characteristics are also advantageous to yield "reaction intermediates" of interest via reactions between clusters and reactive molecules in the cluster source, which may subsequently be mass selected for their reactivity measurements.

  10. Composition and Morphology Control of Metal Dichalcogenides via Chemical Vapor Deposition for Photovoltaic and Nanoelectronic Applications

    Science.gov (United States)

    Samad, Leith L. J.

    The body of work reviewed here encompasses a variety of metal dichalcogenides all synthesized using chemical vapor deposition (CVD) for solar and electronics applications. The first reported phase-pure CVD synthesis of iron pyrite thin films is presented with detailed structural and electrochemical analysis. The phase-pure thin film and improved crystal growth on a metallic backing material represents one of the best options for potential solar applications using iron pyrite. Large tin-sulfur-selenide solid solution plates with tunable bandgaps were also synthesized via CVD as single-crystals with a thin film geometry. Solid solution tin-sulfur-selenide plates were demonstrated to be a new material for solar cells with the first observed solar conversion efficiencies up to 3.1%. Finally, a low temperature molybdenum disulfide vertical heterostructure CVD synthesis with layered controlled growth was achieved with preferential growth enabled by Van der Waals epitaxy. Through recognition of additional reaction parameters, a fully regulated CVD synthesis enabled the controlled growth of 1-6 molybdenum disulfide monolayers for nanoelectronic applications. The improvements in synthesis and materials presented here were all enabled by the control afforded by CVD such that advances in phase purity, growth, and composition control of several metal dichalcogenides were achieved. Further work will be able to take full advantage of these advances for future solar and electronics technologies.

  11. Low jitter metal vapor vacuum arc ion source for electron beam ion trap injections

    International Nuclear Information System (INIS)

    Holland, Glenn E.; Boyer, Craig N.; Seely, John F.; Tan, J.N.; Pomeroy, J.M.; Gillaspy, J.D.

    2005-01-01

    We describe a metal vapor vacuum arc (MeVVA) ion source containing eight different cathodes that are individually selectable via the control electronics which does not require moving components in vacuum. Inside the vacuum assembly, the arc plasma is produced by means of a 30 μs pulse (26 kV,125 A) delivering 2.4 mC of charge to the cathode sample material. The trigger jitter is minimized ( 9 ions/cm 2 , measured by an unbiased Faraday cup positioned 20 cm from the extractor grid, at discharge rates up to 5 Hz. The electronic triggering of the discharge is via a fiber optic interface. We present the design, fabrication details, and performance of this MeVVA, recently installed on the National Institute of Standards and Technology electron beam ion trap (EBIT)

  12. Laterally Stitched Heterostructures of Transition Metal Dichalcogenide: Chemical Vapor Deposition Growth on Lithographically Patterned Area

    KAUST Repository

    Li, Henan

    2016-10-31

    Two-dimensional transition metal dichalcogenides (TMDCs) have shown great promise in electronics and optoelectronics due to their unique electrical and optical properties. Heterostructured TMDC layers such as the laterally stitched TMDCs offer the advantages of better electronic contact and easier band offset tuning. Here, we demonstrate a photoresist-free focused ion beam (FIB) method to pattern as-grown TMDC monolayers by chemical vapor deposition, where the exposed edges from FIB etching serve as the seeds for growing a second TMDC material to form desired lateral heterostructures with arbitrary layouts. The proposed lithographic and growth processes offer better controllability for fabrication of the TMDC heterostrucuture, which enables the construction of devices based on heterostructural monolayers. © 2016 American Chemical Society.

  13. InAs film grown on Si(111) by metal organic vapor phase epitaxy

    International Nuclear Information System (INIS)

    Caroff, P; Jeppsson, M; Mandl, B; Wernersson, L-E; Wheeler, D; Seabaugh, A; Keplinger, M; Stangl, J; Bauer, G

    2008-01-01

    We report the successful growth of high quality InAs films directly on Si(111) by Metal Organic Vapor Phase Epitaxy. A nearly mirror-like and uniform InAs film is obtained at 580 0 C for a thickness of 2 μm. We measured a high value of the electron mobility of 5100 cm 2 /Vs at room temperature. The growth is performed using a standard two-step procedure. The influence of the nucleation layer, group V flow rate, and layer thickness on the electrical and morphological properties of the InAs film have been investigated. We present results of our studies by Atomic Force Microscopy, Scanning Electron Microscopy, electrical Hall/van der Pauw and structural X-Ray Diffraction characterization

  14. Statistical analysis of dimer formation in supersaturated metal vapor based on molecular dynamics simulation

    Science.gov (United States)

    Korenchenko, Anna E.; Vorontsov, Alexander G.; Gelchinski, Boris R.; Sannikov, Grigorii P.

    2018-04-01

    We discuss the problem of dimer formation during the homogeneous nucleation of atomic metal vapor in an inert gas environment. We simulated nucleation with molecular dynamics and carried out the statistical analysis of double- and triple-atomic collisions as the two ways of long-lived diatomic complex formation. Close pair of atoms with lifetime greater than the mean time interval between atom-atom collisions is called a long-lived diatomic complex. We found that double- and triple-atomic collisions gave approximately the same probabilities of long-lived diatomic complex formation, but internal energy of the resulted state was essentially lower in the second case. Some diatomic complexes formed in three-particle collisions are stable enough to be a critical nucleus.

  15. Optical emission spectroscopy of metal vapor dominated laser-arc hybrid welding plasma

    International Nuclear Information System (INIS)

    Ribic, B.; DebRoy, T.; Burgardt, P.

    2011-01-01

    During laser-arc hybrid welding, plasma properties affect the welding process and the weld quality. However, hybrid welding plasmas have not been systematically studied. Here we examine electron temperatures, species densities, and electrical conductivity for laser, arc, and laser-arc hybrid welding using optical emission spectroscopy. The effects of arc currents and heat source separation distances were examined because these parameters significantly affect weld quality. Time-average plasma electron temperatures, electron and ion densities, electrical conductivity, and arc stability decrease with increasing heat source separation distance during hybrid welding. Heat source separation distance affects these properties more significantly than the arc current within the range of currents considered. Improved arc stability and higher electrical conductivity of the hybrid welding plasma result from increased heat flux, electron temperatures, electron density, and metal vapor concentrations relative to arc or laser welding.

  16. Thermodynamic analysis of trimethylgallium decomposition during GaN metal organic vapor phase epitaxy

    Science.gov (United States)

    Sekiguchi, Kazuki; Shirakawa, Hiroki; Chokawa, Kenta; Araidai, Masaaki; Kangawa, Yoshihiro; Kakimoto, Koichi; Shiraishi, Kenji

    2018-04-01

    We analyzed the decomposition of Ga(CH3)3 (TMG) during the metal organic vapor phase epitaxy (MOVPE) of GaN on the basis of first-principles calculations and thermodynamic analysis. We performed activation energy calculations of TMG decomposition and determined the main reaction processes of TMG during GaN MOVPE. We found that TMG reacts with the H2 carrier gas and that (CH3)2GaH is generated after the desorption of the methyl group. Next, (CH3)2GaH decomposes into (CH3)GaH2 and this decomposes into GaH3. Finally, GaH3 becomes GaH. In the MOVPE growth of GaN, TMG decomposes into GaH by the successive desorption of its methyl groups. The results presented here concur with recent high-resolution mass spectroscopy results.

  17. Condensates from vapor made by impacts between metal-, silicate-rich bodies: Comparison with metal and chondrules in CB chondrites

    Science.gov (United States)

    Fedkin, Alexei V.; Grossman, Lawrence; Humayun, Munir; Simon, Steven B.; Campbell, Andrew J.

    2015-09-01

    The impact hypothesis for the origin of CB chondrites was tested by performing equilibrium condensation calculations in systems composed of vaporized mixtures of projectile and target materials. When one of the impacting bodies is composed of the metal from CR chondrites and the other is an H chondrite, good agreement can be found between calculated and observed compositions of unzoned metal grains in CB chondrites but the path of composition variation of the silicate condensate computed for the same conditions that reproduce the metal grain compositions does not pass through the measured compositions of barred olivine (BO) or cryptocrystalline (CC) chondrules in the CBs. The discrepancy between measured chondrule compositions and those of calculated silicates is not reduced when diogenite, eucrite or howardite compositions are substituted for H chondrite as the silicate-rich impacting body. If, however, a CR chondrite body is differentiated into core, a relatively CaO-, Al2O3-poor mantle and a CaO-, Al2O3-rich crust, and later accretes significant amounts of water, a collision between it and an identical body can produce the necessary chemical conditions for condensation of CB chondrules. If the resulting impact plume is spatially heterogeneous in its proportions of crust and mantle components, the composition paths calculated for silicate condensates at the same Ptot, Ni/H and Si/H ratios and water abundance that produce good matches to the unzoned metal grain compositions pass through the fields of BO and CC chondrules, especially if high-temperature condensates are fractionated in the case of the CCs. While equilibrium evaporation of an alloy containing solar proportions of siderophiles into a dense impact plume is an equally plausible hypothesis for explaining the compositions of the unzoned metal grains, equilibrium evaporation can explain CB chondrule compositions only if an implausibly large number of starting compositions is postulated. Kinetic models

  18. Experiment and simulation study on alkalis transfer characteristic during direct combustion utilization of bagasse.

    Science.gov (United States)

    Liao, Yanfen; Cao, Yawen; Chen, Tuo; Ma, Xiaoqian

    2015-10-01

    Bagasse is utilized as fuel in the biggest biomass power plant of China, however, alkalis in the fuel created severe agglomeration and slagging problems. Alkalis transfer characteristic, agglomeration causes in engineering practice, additive improvement effects and mechanism during bagasse combustion were investigated via experiments and simulations. Only slight agglomeration occurs in ash higher than 800°C. Serious agglomeration in practical operation should be attributed to the gaseous alkalis evaporating at high temperature and condensing on the cooler grain surfaces in CFB. It can be speculated that ash caking can be avoided with temperature lower than 750°C and heating surface corrosion caused by alkali metal vapor can be alleviated with temperature lower than 850°C. Kaolin added into the bagasse has an apparent advantage over CaO additive both in enhancing ash fusion point and relieving alkali-chloride corrosion by locking alkalis in dystectic solid compounds over the whole temperature range. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Two level undercut-profile substrate-based filamentary coated conductors produced using metal organic chemical vapor deposition

    DEFF Research Database (Denmark)

    Insinga, Andrea R.; Sundaram, Aarthi; Hazelton, Drew W.

    2018-01-01

    of a filamentary CC produced in an industrial setup by SuperPower Inc. using ion beam assisted deposition and metal organic chemical vapor deposition (IBAD-MOCVD) on a 2LUPS substrate realized at the Technical University of Denmark (DTU), whereas previous studies discussed the fabrication using alternating beam...

  20. SnO2 promoted by alkali metal oxides for soot combustion: The effects of surface oxygen mobility and abundance on the activity

    Science.gov (United States)

    Rao, Cheng; Shen, Jiating; Wang, Fumin; Peng, Honggen; Xu, Xianglan; Zhan, Hangping; Fang, Xiuzhong; Liu, Jianjun; Liu, Wenming; Wang, Xiang

    2018-03-01

    In this study, SnO2-based catalysts promoted by different alkali metal oxides with a Sn/M (M = Li, Na, K, Cs) molar ratio of 9/1 have been prepared for soot combustion. In comparison with the un-modified SnO2 support, the activity of the modified catalysts has been evidently enhanced, following the sequence of CsSn1-9 > KSn1-9 > NaSn1-9 > LiSn1-9 > SnO2. As testified by Raman, H2-TPR, soot-TPR-MS, XPS and O2-TPD results, the incorporation of various alkali metal oxides can induce the formation of more abundant and mobile oxygen species on the surface of the catalysts. Moreover, quantified results have proved that the amount of the surface active oxygen species is nearly proportional to the activity of the catalysts. CsSn1-9, the catalyst promoted by cesium oxide, owns the largest amount of surface mobile oxygen species, thus having the highest activity among all the studied catalysts. It is concluded that the amount of surface active and mobile oxygen species is the major factor determining the activity of the catalysts for soot combustion.

  1. Thermodynamic properties of alkali borosilicate gasses and metaborates

    International Nuclear Information System (INIS)

    Asano, Mitsuru

    1992-01-01

    Borosilicate glasses are the proposed solidifying material for storing high level radioactive wastes in deep underground strata. Those have low melting point, and can contain relatively large amount of high level radioactive wastes. When borosilicate glasses are used for this purpose, they must be sufficiently stable and highly reliable in the vitrification process, engineered storage and the disposal in deep underground strata. The main vaporizing components from borosilicate glasses are alkali elements and boron. In this report, as for the vaporizing behavior of alkali borosilicate glasses, the research on thermodynamic standpoint carried out by the authors is explained, and the thermodynamic properties of alkali metaborates of monomer and dimer which are the main evaporation gases are reported. The evaporation and the activity of alkali borosilicate glasses, the thermodynamic properties of alkali borosilicate glasses, gaseous alkali metaborates and alkali metaborate system solid solution and so on are described. (K.I.)

  2. Investigation of catalytic oxidation of diamond by water vapor and carbon dioxide in the presence of alkali melts of some rare earth oxides

    International Nuclear Information System (INIS)

    Kulakova, I.I.; Rudenko, A.P.; Sulejmenova, A.S.; Tolstopyatova, A.A.

    1978-01-01

    The results of an investigation of the catalytic oxydation of diamond by carbon dioxide and water vapors at 906 deg C in the presence of melts of some rare earth oxides in potassium hydroxide are given. The ion La 3+ was shown to possess the most catalytic activity. The earlier proposed mechanisms of the diamond oxidation by CO 2 and H 2 O were corroborated. The ions of rare earth elements were found to accelerate the different stages of the process

  3. Ion spectra of the metal vapor vacuum arc ion source with compound and alloy cathodes

    Science.gov (United States)

    Sasaki, Jun; Brown, Ian G.

    1990-01-01

    In metal vapor vacuum arc (MEVVA) ion sources, vacuum arc plasma with cathodes of single, pure elements has been utilized for the production of metal ions. In this study, we have investigated the charge state distributions of ions produced in vacuum arc plasmas in a MEVVA ion source for the case when the cathode is an alloy or a compound material. The ion charge state spectra were analyzed by means of a time-of-flight apparatus. We have compared the ion spectra for a cathode of an alloy or a compound material with its constituent elements: TiC/TiN/TiO2/Ti/C, SiC/Si/C, WC/W/C U/UN/(UN-ZrC)/Zr/C, and brass/Zn/Cu. We find that the MEVVA produces ions of all constituent elements in the compound and the alloy cathodes. The charge state distribution of each element differs, however, from the charge state distribution obtained in the vacuum arc with a cathode made of the pure, single constituent element. Fractional values of the total ion numbers of each constituent element in the extracted beam depart from the stoichiometry of the elements in the cathode material. In an operation with a TiC cathode, we irradiated a 304 stainless-steel plate with the extracted beam. Results from glow-discharge spectroscopy (GDS) of the surface show that both titanium and carbon are implanted in the substrate after the irradiation.

  4. Metal Nanoparticles Protected with Monolayers: Applications for Chemical Vapor Sensing and Gas Chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Grate, Jay W.; Nelson, David A.; Skaggs, Rhonda L.; Synovec, Robert E.; Gross, Gwen M.

    2004-03-31

    Nanoparticles and nanoparticle-based materials are of considerable interest for their unique properties and their potential for use in a variety of applications. Metal nanoparticles, in which each particle’s surface is coated with a protective organic monolayer, are of particular interest because the surface monolayer stabilizes them relative to aggregation and they can be taken up into solutions.(1-4) As a result they can be processed into thin films for device applications. We will refer to these materials as monolayer-protected nanoparticles, or MPNs. Typically the metal is gold, the organic layer is a self-assembled thiol layer, and this composition will be assumed throughout the remainder of this chapter. A diversity of materials and properties is readily accessible by straightforward synthetic procedures, either by the structures of the monolayer-forming thiols used in the synthesis or by post-synthetic modifications of the monolayers. A particularly promising application for these materials is as selective layers on chemical vapor sensors. In this role, the thin film of MPNs on the device surface serves to collect and concentrate gas molecules at the sensor’s surface. Their sorptive properties also lend them to use as new nanostructured gas chromatographic stationary phases. This chapter will focus on the sorptive properties of MPNs as they relate to chemical sensors and gas chromatography.

  5. Development of metal oxide gas sensors for very low concentration (ppb) of BTEX vapors

    Science.gov (United States)

    Favard, A.; Aguir, K.; Contaret, T.; Caris, L.; Bendahan, M.

    2017-12-01

    The control and analysis of air quality have become a major preoccupation of the last twenty years. In 2008, the European Union has introduced a Directive (2008/50/EC) to impose measurement obligations and thresholds to not exceed for some pollutants, including BTEX gases, in view of their adverse effects on the health. In this paper, we show the ability to detect very low concentrations of BTEX using a gas microsensor based on metal oxide thin-film. A test bench able to generate very low vapors concentrations has been achieved and fully automated. Thin metal oxides layers have been realized by reactive magnetron sputtering. The sensitive layers are functionalized with gold nanoparticles by thermal evaporation technique. Our sensors have been tested on a wide range of concentrations of BTEX (5 - 500 ppb) and have been able to detect concentrations of a few ppb for operating temperatures below 593 K. These results are very promising for detection of very low BTEX concentration for indoor as well as outdoor application. We showed that the addition of gold nanoparticles on the sensitive layers decreases the sensors operating temperature and increases the response to BTEX gas. The best results are obtained with a sensitive layer based on ZnO.

  6. Some novel design features of the LBL metal vapor vacuum arc ion sources

    International Nuclear Information System (INIS)

    MacGill, R.A.; Brown, I.G.; Galvin, J.E.

    1990-01-01

    The family of MEVVA (metal vapor vacuum arc) high current metal ion sources developed at LBL over the past several years has grown to include a number of different source versions with a wide range of some of the design and operational parameters. The MicroMEVVA source is a particularly compact version, about 2 cm diam and 10 cm long, while the MEVVA IV weighs some 30 kG. MEVVAs IV and V incorporate multiple cathode assemblies (16 and 18 separate cathodes, respectively), and the operating cathode can be switched rapidly and without downtime. The new MEVVA V embodiment is quite compact considering its broad beam (10 cm), high voltage (100 kV), and multiple cathode features. The large-area extractor grids used in MEVVA V were fabricated using a particularly simple technique, and they are clamped into position and can thus be changed simply and quickly. The electrical system used to drive the arc is particularly simple and incorporates several attractive features. In this article we review and describe a number of the mechanical and electrical design features that have been developed for these sources

  7. Epitaxial Oxide Thin Films Grown by Solid Source Metal-Organic Chemical Vapor Deposition.

    Science.gov (United States)

    Lu, Zihong

    1995-01-01

    The conventional liquid source metal-organic chemical vapor deposition (MOCVD) technique is capable of producing large area, high quality, single crystal semiconductor films. However, the growth of complex oxide films by this method has been hampered by a lack of suitable source materials. While chemists have been actively searching for new source materials, the research work reported here has demonstrated the successful application of solid metal-organic sources (based on tetramethylheptanedionate) to the growth of high quality thin films of binary compound cerium dioxide (CeO_2), and two more complex materials, the ternary compound lithium niobate (LiNbO_3), with two cations, and the quaternary compound strontium barium niobate (SBN), with three cations. The growth of CeO_2 thin films on (1012)Al_2O_3 substrates has been used as a model to study the general growth behavior of oxides. Factors affecting deposition rate, surface morphology, out-of-plane mosaic structure, and film orientation have been carefully investigated. A kinetic model based on gas phase prereaction is proposed to account for the substrate temperature dependence of film orientation found in this system. Atomically smooth, single crystal quality cerium dioxide thin films have been obtained. Superconducting YBCO films sputtered on top of solid source MOCVD grown thin cerium dioxide buffer layers on sapphire have been shown to have physical properties as good as those of YBCO films grown on single crystal MgO substrates. The thin film growth of LiNbO_3 and Sr_{1-x}Ba _{x}Nb_2 O_6 (SBN) was more complex and challenging. Phase purity, transparency, in-plane orientation, and the ferroelectric polarity of LiNbO _3 films grown on sapphire substrates was investigated. The first optical quality, MOCVD grown LiNbO _3 films, having waveguiding losses of less than 2 dB/cm, were prepared. An important aspect of the SBN film growth studies involved finding a suitable single crystal substrate material. Mg

  8. The Study of Anti-/Pro-Oxidant, Lipophilic, Microbial and Spectroscopic Properties of New Alkali Metal Salts of 5-O-Caffeoylquinic Acid

    Science.gov (United States)

    Kalinowska, Monika; Bajko, Ewelina; Matejczyk, Marzena; Kaczyński, Piotr; Łozowicka, Bożena; Lewandowski, Włodzimierz

    2018-01-01

    Lithium, sodium, potassium, rubidium and caesium salts of 5-O-caffeoylquinic acid (chlorogenic acid, 5-CQA) were synthesized and described by FT-IR (infrared spectroscopy), FT-Raman (Raman spectroscopy), UV (UV absorption spectroscopy), 1H (400.15 MHz), 13C (100.63 MHz) NMR (nuclear magnetic resonance spectroscopy). The quantum–chemical calculations at the B3LYP/6-311++G** level were done in order to obtain the optimal structures, IR spectra, NBO (natural bond orbital) atomic charges, HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) orbitals and chemical reactivity parameters for 5-CQA and Li, Na and K 5-CQAs (chlorogenates). The DPPH (α, α-diphenyl-β-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) assays were used for the preliminary estimation of the antioxidant properties of alkali metal chlorogenates and chlorogenic acid. In the DPPH assay the EC50 parameter were equal to 7.39 μM for 5-CQA and was in the range of 4.50–5.89 μM for salts. The FRAP values for two different concentrations (5 and 2.5 μM) of the studied compounds were respectively 114.22 and 72.53 μM Fe2+ for 5-CQA, whereas for salts they were 106.92–141.13 and 78.93–132.00 μM Fe2+. The 5-CQA and its alkali metal salts possess higher antioxidant properties than commonly applied antioxidants (BHA, BHT, l-ascorbic acid). The pro-oxidant action of these compounds on trolox oxidation was studied in the range of their concentration 0.05–0.35 μM. The lipophilicity (logkw) of chlorogenates and chlorogenic acid was determined by RP-HPLC (reverse phase—high performance liquid chromatography) using five different columns (C8, PHE (phenyl), CN (cyano), C18, IAM (immobilized artificial membrane)). The compounds were screened for their in vitro antibacterial activity against E. coli, Bacillus sp., Staphylococcus sp., Streptococcus pyogenes and antifungal activity against Candida sp. The 5-CQA possessed lower antibacterial (minimal

  9. The Study of Anti-/Pro-Oxidant, Lipophilic, Microbial and Spectroscopic Properties of New Alkali Metal Salts of 5-O-Caffeoylquinic Acid

    Directory of Open Access Journals (Sweden)

    Monika Kalinowska

    2018-02-01

    Full Text Available Lithium, sodium, potassium, rubidium and caesium salts of 5-O-caffeoylquinic acid (chlorogenic acid, 5-CQA were synthesized and described by FT-IR (infrared spectroscopy, FT-Raman (Raman spectroscopy, UV (UV absorption spectroscopy, 1H (400.15 MHz, 13C (100.63 MHz NMR (nuclear magnetic resonance spectroscopy. The quantum–chemical calculations at the B3LYP/6-311++G** level were done in order to obtain the optimal structures, IR spectra, NBO (natural bond orbital atomic charges, HOMO (highest occupied molecular orbital and LUMO (lowest unoccupied molecular orbital orbitals and chemical reactivity parameters for 5-CQA and Li, Na and K 5-CQAs (chlorogenates. The DPPH (α, α-diphenyl-β-picrylhydrazyl and FRAP (ferric reducing antioxidant power assays were used for the preliminary estimation of the antioxidant properties of alkali metal chlorogenates and chlorogenic acid. In the DPPH assay the EC50 parameter were equal to 7.39 μM for 5-CQA and was in the range of 4.50–5.89 μM for salts. The FRAP values for two different concentrations (5 and 2.5 μM of the studied compounds were respectively 114.22 and 72.53 μM Fe2+ for 5-CQA, whereas for salts they were 106.92–141.13 and 78.93–132.00 μM Fe2+. The 5-CQA and its alkali metal salts possess higher antioxidant properties than commonly applied antioxidants (BHA, BHT, l-ascorbic acid. The pro-oxidant action of these compounds on trolox oxidation was studied in the range of their concentration 0.05–0.35 μM. The lipophilicity (logkw of chlorogenates and chlorogenic acid was determined by RP-HPLC (reverse phase—high performance liquid chromatography using five different columns (C8, PHE (phenyl, CN (cyano, C18, IAM (immobilized artificial membrane. The compounds were screened for their in vitro antibacterial activity against E. coli, Bacillus sp., Staphylococcus sp., Streptococcus pyogenes and antifungal activity against Candida sp. The 5-CQA possessed lower antibacterial (minimal inhibitory

  10. Chemical vapor deposition of metal nitrides, phosphides and arsenides. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, D.M. [Univ. of Houston, TX (United States). Dept. of Chemistry

    1994-03-01

    The author recently reported that dialkylamido complexes are promising precursors to nitride thin films. On this basis it was reasoned that transition metal and main group disilazide complexes in which the silicon has dialkylamido substituents are potential precursors to ternary silicon nitride films. Bulky disilazide ligands are known to stabilize main group and transition metal complexes with low coordination numbers. Reaction of dimethylamine with Cl{sub 3}SiN(H)SiMe{sub 3} in hexane solution at 25{degrees}C gave the bulky disilazane [(Me{sub 2}N){sub 3}Si]N(h)SiMe{sub 3} (1) in 73% yield. Reaction of (1) with n-butyl lithium in benzene at 0{degrees}C produced [(Me{sub 2}N){sub 3}Si]N(Li)SiMe{sub 3} in 82% yield. LiN[Si(NMe{sub 2}){sub 3}]{sub 2} was chemically prepared in 92% yield and was converted to the amine with 83% yield. The author examined the use of amido precursors for main group oxide thin films. Sn(NMe{sub 2}){sub 4} and Si(NMe{sub 2}){sub 4} react with oxygen in an atmospheric pressure chemical vapor deposition reactor to give SnO{sub 2} and SiO{sub 2} films, respectively. The films were deposited on quartz, silicon, and glass at substrate temperatures of 250--400 {degrees}C. The results of the characterizations of the films and compounds are presented in this report.

  11. LINE SHAPES OF DOPPLER-FREE RESONANCE IN SRFM: STRONG ATOM-WALL INTERACTION AND PRESSURE EFFECT ON THE FREQUENCY SHIFT OF AN ALKALI VAPOR

    Directory of Open Access Journals (Sweden)

    B BOUHAFS

    2003-12-01

    Full Text Available The attractive potential energy between the atoms of rubidium vapor and a dielectric wall has been investigated by monitoring the reflection light at the interface. The atom- wall interaction potential of the form V(z = - C /z3 (z: atom-wall allows to predict experimental results only for weak regime, i.e., where C<< 0.2 kHzmm3. In the strong interaction case, the dispersive line shape is turned into an absorption-type line shape. The influence of atomic density on the shift of  the selective reflection resonance  relatively to the frequency of unperturbed atomic transition is found to be red with a negative slope. This technique opens the way to characterize the windows made of different materials thin films.

  12. Crystal structures and hydrogen bonding in the isotypic series of hydrated alkali metal (K, Rb and Cs) complexes with 4-amino?phenyl?arsonic acid

    OpenAIRE

    Smith, Graham; Wermuth, Urs D.

    2017-01-01

    The structures of the alkali metal (K, Rb and Cs) complex salts with 4-amino?phenyl?arsonic acid (p-arsanilic acid) manifest an isotypic series with the general formula [M 2(C6H7AsNO3)2(H2O)3], with M = K {poly[di-?3-4-amino?phenyl?arsonato-tri-?2-aqua-dipotassium], [K2(C6H7AsNO3)2(H2O)3], (I)}, Rb {poly[di-?3-4-amino?phenyl?arsonato-tri-?2-aqua-dirubidium], [Rb2(C6H7AsNO3)2(H2O)3], (II)}, and Cs {poly[di-?3-4-amino?phenyl?arsonato-tri-?2-aqua-dirubidium], [Cs2(C6H7AsNO3)2(H2O)3], (III)}, in ...

  13. Quantum-chemistry based calibration of the alkali metal cation series (Li(+)-Cs(+)) for large-scale polarizable molecular mechanics/dynamics simulations.

    Science.gov (United States)

    Dudev, Todor; Devereux, Mike; Meuwly, Markus; Lim, Carmay; Piquemal, Jean-Philip; Gresh, Nohad

    2015-02-15

    The alkali metal cations in the series Li(+)-Cs(+) act as major partners in a diversity of biological processes and in bioinorganic chemistry. In this article, we present the results of their calibration in the context of the SIBFA polarizable molecular mechanics/dynamics procedure. It relies on quantum-chemistry (QC) energy-decomposition analyses of their monoligated complexes with representative O-, N-, S-, and Se- ligands, performed with the aug-cc-pVTZ(-f) basis set at the Hartree-Fock level. Close agreement with QC is obtained for each individual contribution, even though the calibration involves only a limited set of cation-specific parameters. This agreement is preserved in tests on polyligated complexes with four and six O- ligands, water and formamide, indicating the transferability of the procedure. Preliminary extensions to density functional theory calculations are reported. © 2014 Wiley Periodicals, Inc.

  14. Model description of the equivalent electroconductivity of aqueous solutions of alkali metal hydroxides over a wide range of concentrations and temperatures

    Science.gov (United States)

    Kuznetsova, E. M.; Volkov, D. S.

    2011-09-01

    The possibility of a quantitative theoretical description of the λ( c) dependence for aqueous solutions of alkali metal hydroxides in a wide concentration (from 0.0001 to 12 M) and temperature (from 0 to 100°C) was considered on the basis of concept suggested earlier. Effectiveness of the description of characteristics analyzed was illustrated on the examples of the calculation of electroconductivity values for aqueous LiOH, NaOH, KOH, RbOH, and CsOH solutions and comparison of them with experimental values taken from published data. The suggestion on different H+ and OH- ion migration mechanism was made on the basis of the model used for description of λ( c).

  15. Tuning of electrical and structural properties of indium oxide films grown by metal organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Wang, Ch.Y.; Cimalla, V.; Romanus, H.; Kups, Th.; Niebelschuetz, M.; Ambacher, O.

    2007-01-01

    Tuning of structural and electrical properties of indium oxide (In 2 O 3 ) films by means of metal organic chemical vapor deposition is demonstrated. Phase selective growth of rhombohedral In 2 O 3 (0001) and body-centered cubic In 2 O 3 (001) polytypes on (0001) sapphire substrates was obtained by adjusting the substrate temperature and trimethylindium flow rate. The specific resistance of the as-grown films can be tuned by about two orders of magnitude by varying the growth conditions

  16. Metal-organic chemical vapor deposition enabling all-solid-state Li-ion microbatteries:a short review

    OpenAIRE

    Chen, C; Eichel, R-A; Notten, PHL Peter

    2017-01-01

    For powering small-sized electronic devices, all-solid-state Li-ion batteries are the most promising candidates due to its safety and allowing miniaturization. Thin film deposition methods can be used for building new all-solid-state architectures. Well-known deposition methods are sputter deposition, pulsed laser deposition, sol-gel deposition, atomic layer deposition, etc. This review summarizes thin film storage materials deposited by metal-organic chemical vapor deposition (MOCVD) for all...

  17. Thermal, structural and spectroscopic properties of Pr3+-doped lead zinc borate glasses modified by alkali metal ions

    Directory of Open Access Journals (Sweden)

    M.V. Sasi kumar

    2017-07-01

    Full Text Available This paper offers a study on Pr3+-doped alkali and mixed-alkali borate glasses prepared by the melt quenching technique and characterized by thermal, structural and spectroscopic studies. The amorphous nature of the glassy systems was identified based on X-ray diffraction. The thermal behaviour of glasses was studied using differential thermal analysis (DTA. The functional groups contained in the glasses were identified by Fourier transform infrared spectroscopy (FTIR. Spectral intensities were evaluated from the absorption spectra and used for calculating J–O intensity parameters, Ωλ (λ = 2, 4 and 6. Further, these parameters were used for calculating different radiative properties. The best radiative state was identified as the laser transition state among the various states. Emission analysis was performed for this state by calculating the branching ratios and stimulated emission cross sections (σp for all the prepared glasses. These studies suggest that borate glasses are useful for visible fluorescence.

  18. Structures of Hydrated Alkali Metal Cations, M+(H2O)nAr (m = Li, Na, K, rb and Cs, n = 3-5), Using Infrared Photodissociation Spectroscopy and Thermodynamic Analysis

    Science.gov (United States)

    Ke, Haochen; van der Linde, Christian; Lisy, James M.

    2014-06-01

    Alkali metal cations play vital roles in chemical and biochemical systems. Lithium is widely used in psychiatric treatment of manic states and bipolar disorder; Sodium and potassium are essential elements, having major biological roles as electrolytes, balancing osmotic pressure on body cells and assisting the electroneurographic signal transmission; Rubidium has seen increasing usage as a supplementation for manic depression and depression treatment; Cesium doped compounds are used as essential catalysts in chemical production and organic synthesis. Since hydrated alkali metal cations are ubiquitous and the basic form of the alkali metal cations in chemical and biochemical systems, their structural and thermodynamic properties serve as the foundation for modeling more complex chemical and biochemical processes, such as ion transport and ion size-selectivity of ionophores and protein channels. By combining mass spectrometry and infrared photodissociation spectroscopy, we have characterized the structures and thermodynamic properties of the hydrated alkali metal cations, i.e. M+(H2O)nAr, (M = Li, Na, K, Rb and Cs, n = 3-5). Ab initio calculations and RRKM-EE (evaporative ensemble) calculations were used to assist in the spectral assignments and thermodynamic analysis. Results showed that the structures of hydrated alkali metal cations were determined predominantly by the competition between non-covalent interactions, i.e. the water---water hydrogen bonding interactions and the water---cation electrostatic interactions. This balance, however, is very delicate and small changes, i.e. different cations, different levels of hydration and different effective temperatures clearly impact the balance.

  19. Passivation of metal surface states: microscopic origin for uniform monolayer graphene by low temperature chemical vapor deposition.

    Science.gov (United States)

    Jeon, Insu; Yang, Heejun; Lee, Sung-Hoon; Heo, Jinseong; Seo, David H; Shin, Jaikwang; Chung, U-In; Kim, Zheong Gou; Chung, Hyun-Jong; Seo, Sunae

    2011-03-22

    Scanning tunneling microscopy (STM) and density functional theory (DFT) calculations were used to investigate the surface morphology and electronic structure of graphene synthesized on Cu by low temperature chemical vapor deposition (CVD). Periodic line patterns originating from the arrangements of carbon atoms on the Cu surface passivate the interaction between metal substrate and graphene, resulting in flawless inherent graphene band structure in pristine graphene/Cu. The effective elimination of metal surface states by the passivation is expected to contribute to the growth of monolayer graphene on Cu, which yields highly enhanced uniformity on the wafer scale, making progress toward the commercial application of graphene.

  20. Alkali-Metal-Mediated Magnesiations of an N-Heterocyclic Carbene: Normal, Abnormal, and "Paranormal" Reactivity in a Single Tritopic Molecule.

    Science.gov (United States)

    Martínez-Martínez, Antonio J; Fuentes, M Ángeles; Hernán-Gómez, Alberto; Hevia, Eva; Kennedy, Alan R; Mulvey, Robert E; O'Hara, Charles T

    2015-11-16

    Herein the sodium alkylmagnesium amide [Na4Mg2(TMP)6(nBu)2] (TMP=2,2,6,6-tetramethylpiperidide), a template base as its deprotonating action is dictated primarily by its 12 atom ring structure, is studied with the common N-heterocyclic carbene (NHC) IPr [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene]. Remarkably, magnesiation of IPr occurs at the para-position of an aryl substituent, sodiation occurs at the abnormal C4 position, and a dative bond occurs between normal C2 and sodium, all within a 20 atom ring structure accommodating two IPr(2-). Studies with different K/Mg and Na/Mg bimetallic bases led to two other magnesiated NHC structures containing two or three IPr(-) monoanions bound to Mg through abnormal C4 sites. Synergistic in that magnesiation can only work through alkali-metal mediation, these reactions add magnesium to the small cartel of metals capable of directly metalating a NHC. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Coupling scales for modelling heavy metal vaporization from municipal solid waste incineration in a fluid bed by CFD

    Energy Technology Data Exchange (ETDEWEB)

    Soria, José, E-mail: jose.soria@probien.gob.ar [Institute for Research and Development in Process Engineering, Biotechnology and Alternative Energies (PROBIEN, CONICET – UNCo), 1400 Buenos Aires St., 8300 Neuquén (Argentina); Gauthier, Daniel; Flamant, Gilles [Processes, Materials and Solar Energy Laboratory (PROMES-CNRS, UPR 8521), 7 Four Solaire Street, Odeillo, 66120 Font-Romeu (France); Rodriguez, Rosa [Chemical Engineering Institute, National University of San Juan, 1109 Libertador (O) Avenue, 5400 San Juan (Argentina); Mazza, Germán [Institute for Research and Development in Process Engineering, Biotechnology and Alternative Energies (PROBIEN, CONICET – UNCo), 1400 Buenos Aires St., 8300 Neuquén (Argentina)

    2015-09-15

    Highlights: • A CFD two-scale model is formulated to simulate heavy metal vaporization from waste incineration in fluidized beds. • MSW particle is modelled with the macroscopic particle model. • Influence of bed dynamics on HM vaporization is included. • CFD predicted results agree well with experimental data reported in literature. • This approach may be helpful for fluidized bed reactor modelling purposes. - Abstract: Municipal Solid Waste Incineration (MSWI) in fluidized bed is a very interesting technology mainly due to high combustion efficiency, great flexibility for treating several types of waste fuels and reduction in pollutants emitted with the flue gas. However, there is a great concern with respect to the fate of heavy metals (HM) contained in MSW and their environmental impact. In this study, a coupled two-scale CFD model was developed for MSWI in a bubbling fluidized bed. It presents an original scheme that combines a single particle model and a global fluidized bed model in order to represent the HM vaporization during MSW combustion. Two of the most representative HM (Cd and Pb) with bed temperatures ranging between 923 and 1073 K have been considered. This new approach uses ANSYS FLUENT 14.0 as the modelling platform for the simulations along with a complete set of self-developed user-defined functions (UDFs). The simulation results are compared to the experimental data obtained previously by the research group in a lab-scale fluid bed incinerator. The comparison indicates that the proposed CFD model predicts well the evolution of the HM release for the bed temperatures analyzed. It shows that both bed temperature and bed dynamics have influence on the HM vaporization rate. It can be concluded that CFD is a rigorous tool that provides valuable information about HM vaporization and that the original two-scale simulation scheme adopted allows to better represent the actual particle behavior in a fluid bed incinerator.

  2. Conformation of Alkali Metal Ion-Benzo-12-Crown-4 Complexes Investigated by UV Photodissociation and UV-UV Hole-Burning Spectroscopy.

    Science.gov (United States)

    Inokuchi, Yoshiya; Nakatsuma, Maki; Kida, Motoki; Ebata, Takayuki

    2016-08-18

    We measure UV photodissociation (UVPD) spectra of benzo-12-crown-4 (B12C4) complexes with alkali metal ions, M(+)·B12C4 (M = Li, Na, K, Rb, and Cs), in the 36300-37600 cm(-1) region. Thanks to the cooling of ions to ∼10 K, all the M(+)·B12C4 complexes show sharp vibronic bands in this region. For UV-UV hole-burning (HB) spectroscopy, we first check if our experimental system works well by observing UV-UV HB spectra of the K(+) complex with benzo-18-crown-6 (B18C6), K(+)·B18C6. In the UV-UV HB spectra of the K(+)·B18C6 complex, gain signals are also observed; these are due to vibrationally hot K(+)·B18C6 complex produced by the UV excitation of cold K(+)·B18C6 complex. Then we apply UV-UV HB spectroscopy to the M(+)·B12C4 complexes, and only one conformer is found for each complex except for the Li(+) complex, which has two conformers. The vibronic structure around the origin band of the UVPD spectra is quite similar for all the complexes, indicating close resemblance of the complex structure. The most stable structures calculated for the M(+)·B12C4 (M = Li, Na, K, Rb, and Cs) complexes also have a similar conformation among them, which coincides with the UVPD results. In these conformers the metal ions are too big to be included in the B12C4 cavity, even for the Li(+) ion. In solution, it was reported that 12-crown-4 (12C4) shows the preference of Na(+) ion among alkali metal ions. From the similarity of the structure for the M(+)·B12C4 complexes, it is suggested that the solvation of free metal ions, not of the M(+)·12C4 complexes, may lead to the selectivity of Na(+) ion for 12C4 in solution.

  3. INERA Conference: Vapor Phase Technologies for Metal Oxide and Carbon Nanostructures

    International Nuclear Information System (INIS)

    2016-01-01

    We are pleased to introduce the Proceedings of the Conference “Vapor Phase Technologies for Metal Oxide and Carbon Nanostructures” (6 th to 8 th of July 2016, Velingrad, Bulgaria) organized by the Institute of Solid State Physics, Bulgarian Academy of Sciences in the frames of the Project INERA: “Research and Innovation Capacity Strengthening of ISSP-BAS in Multifunctional Nanostructures” REGPOT-2012-2013-1 NMP (http://www.inera.org). Participants from 7 different countries delivered 10 invited lectures, 16 oral and 26 poster presentations, contributing in 7 different topics. Papers submitted for publication in the Proceedings were refereed according to the standards of the Journal of Physics: Conference Series and the accepted ones illustrate the diversity and the high quality of the contributions. The Conference offered good opportunities for many interesting discussions and ample exchange of ideas between the participants. It became also a meeting point where INERA partners could plan their future collaboration and joint projects. A significant factor for the success of the Conference was the conference venue - the beautiful spa resort Velingrad located 130 km from Sofia in the western part of the Rhodope Mountains. It is one of the leading “balneological” resorts in the Balkans with its ninety mineral water springs suitable for treatment of a wide range of diseases. The participants enjoyed also the rich social program, in particular the guided trip to the excavation site Dorkovo, one of the milestones marking the beginning of the Pliocene epoch in Eastern Europe. The proceedings of conferences and workshops organized in the frames of INERA Project are regularly published by the Journal of Physics: Conference Series. We are grateful to the Journal's staff for the continuous support. Managing Editor: Diana Nesheva Co-editors: Hassan Chamati, Julia Genova, Kostadinka Gesheva, Tatyana Ivanova, Albena Paskaleva and Anna Szekeres (paper)

  4. Aluminum Nitride Micro-Channels Grown via Metal Organic Vapor Phase Epitaxy for MEMs Applications

    Energy Technology Data Exchange (ETDEWEB)

    Rodak, L.E.; Kuchibhatla, S.; Famouri, P.; Ting, L.; Korakakis, D.

    2008-01-01

    Aluminum nitride (AlN) is a promising material for a number of applications due to its temperature and chemical stability. Furthermore, AlN maintains its piezoelectric properties at higher temperatures than more commonly used materials, such as Lead Zirconate Titanate (PZT) [1, 2], making AlN attractive for high temperature micro and nanoelectromechanical (MEMs and NEMs) applications including, but not limited to, high temperature sensors and actuators, micro-channels for fuel cell applications, and micromechanical resonators. This work presents a novel AlN micro-channel fabrication technique using Metal Organic Vapor Phase Epitaxy (MOVPE). AlN easily nucleates on dielectric surfaces due to the large sticking coefficient and short diffusion length of the aluminum species resulting in a high quality polycrystalline growth on typical mask materials, such as silicon dioxide and silicon nitride [3,4]. The fabrication process introduced involves partially masking a substrate with a silicon dioxide striped pattern and then growing AlN via MOVPE simultaneously on the dielectric mask and exposed substrate. A buffered oxide etch is then used to remove the underlying silicon dioxide and leave a free standing AlN micro-channel. The width of the channel has been varied from 5 ìm to 110 ìm and the height of the air gap from 130 nm to 800 nm indicating the stability of the structure. Furthermore, this versatile process has been performed on (111) silicon, c-plane sapphire, and gallium nitride epilayers on sapphire substrates. Reflection High Energy Electron Diffraction (RHEED), Atomic Force Microscopy (AFM), and Raman measurements have been taken on channels grown on each substrate and indicate that the substrate is influencing the growth of the AlN micro-channels on the SiO2 sacrificial layer.

  5. Direct observation of metal nanoparticles as heterogeneous nuclei for the condensation of supersaturated organic vapors: Nucleation of size-selected aluminum nanoparticles in acetonitrile and n-hexane vapors

    Science.gov (United States)

    Abdelsayed, Victor; Samy El-Shall, M.

    2014-08-01

    This work reports the direct observation and separation of size-selected aluminum nanoparticles acting as heterogeneous nuclei for the condensation of supersaturated vapors of both polar and nonpolar molecules. In the experiment, we study the condensation of supersaturated acetonitrile and n-hexane vapors on charged and neutral Al nanoparticles by activation of the metal nanoparticles to act as heterogeneous nuclei for the condensation of the organic vapor. Aluminum seed nanoparticles with diameters of 1 and 2 nm are capable of acting as heterogeneous nuclei for the condensation of supersaturated acetonitrile and hexane vapors. The comparison between the Kelvin and Fletcher diameters indicates that for the heterogeneous nucleation of both acetonitrile and hexane vapors, particles are activated at significantly smaller sizes than predicted by the Kelvin equation. The activation of the Al nanoparticles occurs at nearly 40% and 65% of the onset of homogeneous nucleation of acetonitrile and hexane supersaturated vapors, respectively. The lower activation of the charged Al nanoparticles in acetonitrile vapor is due to the charge-dipole interaction which results in rapid condensation of the highly polar acetonitrile molecules on the charged Al nanoparticles. The charge-dipole interaction decreases with increasing the size of the Al nanoparticles and therefore at low supersaturations, most of the heterogeneous nucleation events are occurring on neutral nanoparticles. No sign effect has been observed for the condensation of the organic vapors on the positively and negatively charged Al nanoparticles. The present approach of generating metal nanoparticles by pulsed laser vaporization within a supersaturated organic vapor allows for efficient separation between nucleation and growth of the metal nanoparticles and, consequently controls the average particle size, particle density, and particle size distribution within the liquid droplets of the condensing vapor. Strong

  6. Direct observation of metal nanoparticles as heterogeneous nuclei for the condensation of supersaturated organic vapors: Nucleation of size-selected aluminum nanoparticles in acetonitrile and n-hexane vapors

    Energy Technology Data Exchange (ETDEWEB)

    Abdelsayed, Victor; Samy El-Shall, M., E-mail: mselshal@vcu.edu [Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284-2006 (United States)

    2014-08-07

    This work reports the direct observation and separation of size-selected aluminum nanoparticles acting as heterogeneous nuclei for the condensation of supersaturated vapors of both polar and nonpolar molecules. In the experiment, we study the condensation of supersaturated acetonitrile and n-hexane vapors on charged and neutral Al nanoparticles by activation of the metal nanoparticles to act as heterogeneous nuclei for the condensation of the organic vapor. Aluminum seed nanoparticles with diameters of 1 and 2 nm are capable of acting as heterogeneous nuclei for the condensation of supersaturated acetonitrile and hexane vapors. The comparison between the Kelvin and Fletcher diameters indicates that for the heterogeneous nucleation of both acetonitrile and hexane vapors, particles are activated at significantly smaller sizes than predicted by the Kelvin equation. The activation of the Al nanoparticles occurs at nearly 40% and 65% of the onset of homogeneous nucleation of acetonitrile and hexane supersaturated vapors, respectively. The lower activation of the charged Al nanoparticles in acetonitrile vapor is due to the charge-dipole interaction which results in rapid condensation of the highly polar acetonitrile molecules on the charged Al nanoparticles. The charge-dipole interaction decreases with increasing the size of the Al nanoparticles and therefore at low supersaturations, most of the heterogeneous nucleation events are occurring on neutral nanoparticles. No sign effect has been observed for the condensation of the organic vapors on the positively and negatively charged Al nanoparticles. The present approach of generating metal nanoparticles by pulsed laser vaporization within a supersaturated organic vapor allows for efficient separation between nucleation and growth of the metal nanoparticles and, consequently controls the average particle size, particle density, and particle size distribution within the liquid droplets of the condensing vapor. Strong

  7. High mobility single-crystalline-like GaAs thin films on inexpensive flexible metal substrates by metal-organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Dutta, P.; Rathi, M.; Gao, Y.; Yao, Y.; Selvamanickam, V.; Zheng, N.; Ahrenkiel, P.; Martinez, J.

    2014-01-01

    We demonstrate heteroepitaxial growth of single-crystalline-like n and p-type doped GaAs thin films on inexpensive, flexible, and light-weight metal foils by metal-organic chemical vapor deposition. Single-crystalline-like Ge thin film on biaxially textured templates made by ion beam assisted deposition on metal foil served as the epitaxy enabling substrate for GaAs growth. The GaAs films exhibited strong (004) preferred orientation, sharp in-plane texture, low grain misorientation, strong photoluminescence, and a defect density of ∼10 7  cm −2 . Furthermore, the GaAs films exhibited hole and electron mobilities as high as 66 and 300 cm 2 /V-s, respectively. High mobility single-crystalline-like GaAs thin films on inexpensive metal substrates can pave the path for roll-to-roll manufacturing of flexible III-V solar cells for the mainstream photovoltaics market.

  8. Cross sections and equilibrium fractions of deuterium ions and atoms in metal vapors. Progress report, June 1, 1978-May 31, 1979

    International Nuclear Information System (INIS)

    Morgan, T.J.

    1979-01-01

    The purpose of this program is to measure cross sections and equilibrium fractions of deuterium ions and atoms in metal vapors. In particular, in connection with double charge exchange D - ion sources, there is concern with D - formation in alkaline-earth vapor targets. Also, in connection with possible metal vapor contamination in the system, there is concern with cross sections for high energy D + , D 0 and D - collisions with these metal vapors. Results from this research will fill in a gap in knowledge of single and double charge transfer and multiple collision processes in alkaline-earth targets and provide a better understanding of D - formation mechanisms. A list of publications is included. 6 references

  9. Theoretical study on the ground state of the polar alkali-metal-barium molecules: Potential energy curve and permanent dipole moment

    International Nuclear Information System (INIS)

    Gou, Dezhi; Kuang, Xiaoyu; Gao, Yufeng; Huo, Dongming

    2015-01-01

    In this paper, we systematically investigate the electronic structure for the 2 Σ + ground state of the polar alkali-metal-alkaline-earth-metal molecules BaAlk (Alk = Li, Na, K, Rb, and Cs). Potential energy curves and permanent dipole moments (PDMs) are determined using power quantum chemistry complete active space self-consistent field and multi-reference configuration interaction methods. Basic spectroscopic constants are derived from ro-vibrational bound state calculation. From the calculations, it is shown that BaK, BaRb, and BaCs molecules have moderate values of PDM at the equilibrium bond distance (BaK:1.62 D, BaRb:3.32 D, and BaCs:4.02 D). Besides, the equilibrium bond length (4.93 Å and 5.19 Å) and dissociation energy (0.1825 eV and 0.1817 eV) for the BaRb and BaCs are also obtained

  10. Experimental observation of electrochemical rate limitations affecting sodium ion-electron recombination at electrodes of the alkali metal thermoelectric converter at T about 1200 K

    Science.gov (United States)

    Williams, R. M.; Jeffries-Nakamura, B.; Loveland, M. E.; Underwood, M. L.; Bankston, C. P.

    1988-01-01

    This paper considers a model of the internal impedances of thin porous Mo and W alkali metal thermoelectric converter (AMTEC), in which the kinetic parameters associated with the reaction of the beta-double-prime alumina solid electrolite (BASE)/porous metal/gas three-phase boundary can be evaluated. Impedance data in the frequency range 0.01-100,000 Hz were collected over a range of AMTEC cell operating voltages for small-area thin porous Mo and W electrodes, yielding apparent charge transfer resistances at a series of cell potentials/currents. The ohmic resistance in the AMTEC cell could be broken down and characterized with three parameters: the BASE ionic resistance, the electrode film sheet resistance, and the contact/lead resistance, all of which could be calculated or measured independently and used to calculate power curves in good agreement with observed power curves. It is shown that these calculations can be used to predict the properties of electrodes with optimized parameters or to detect enhanced transport modes.

  11. Metallic 1T phase source/drain electrodes for field effect transistors from chemical vapor deposited MoS2

    Directory of Open Access Journals (Sweden)

    Rajesh Kappera

    2014-09-01

    Full Text Available Two dimensional transition metal dichalcogenides (2D TMDs offer promise as opto-electronic materials due to their direct band gap and reasonably good mobility values. However, most metals form high resistance contacts on semiconducting TMDs such as MoS2. The large contact resistance limits the performance of devices. Unlike bulk materials, low contact resistance cannot be stably achieved in 2D materials by doping. Here we build on our previous work in which we demonstrated that it is possible to achieve low contact resistance electrodes by phase transformation. We show that similar to the previously demonstrated mechanically exfoliated samples, it is possible to decrease the contact resistance and enhance the FET performance by locally inducing and patterning the metallic 1T phase of MoS2 on chemically vapor deposited material. The device properties are substantially improved with 1T phase source/drain electrodes.

  12. Mechanical filter for alkali atoms

    CERN Document Server

    Toporkov, D K

    2000-01-01

    A device for separating gases of different mass is discussed. Such a device could be used in a laser-driven spin exchange source of polarized hydrogen atoms to reduce the contamination of alkali atoms. A Monte Carlo simulation has shown that the suggested apparatus based on a commercial turbo pump could reduce by a factor of 10-15 the concentration of the alkali-metal atoms in the hydrogen flow from a laser driven polarized source. This would greatly enhance the effective polarization in hydrogen targets.

  13. Reduced water vapor transmission rates of low-temperature solution-processed metal oxide barrier films via ultraviolet annealing

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seonuk; Jeong, Yong Jin; Baek, Yonghwa; Kim, Lae Ho; Jang, Jin Hyuk; Kim, Yebyeol [POSTECH Organic Electronics Laboratory, Polymer Research Institute, Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, 790-784 (Korea, Republic of); An, Tae Kyu [Department of Polymer Science & Engineering, Korea National University of Transportation, 50 Daehak-Ro, Chungju (Korea, Republic of); Nam, Sooji, E-mail: sjnam15@etri.re.kr [Information Control Device Section, Electronics and Telecommunications Research Institute, Daejeon, 305-700 (Korea, Republic of); Kim, Se Hyun, E-mail: shkim97@yu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeongsan, North Gyeongsang 712-749 (Korea, Republic of); Jang, Jaeyoung, E-mail: jyjang15@hanyang.ac.kr [Department of Energy Engineering, Hanyang University, Seoul, 133-791 (Korea, Republic of); Park, Chan Eon, E-mail: cep@postech.ac.kr [POSTECH Organic Electronics Laboratory, Polymer Research Institute, Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, 790-784 (Korea, Republic of)

    2017-08-31

    Highlights: • Sol-gel-derived aluminum oxide thin films were prepared using ultraviolet (UV) annealing. • UV irradiation dramatically promoted the densification of AlO{sub x} during the annealing stage, thereby forming a close-packed AlO{sub x} film. • The resulting AlO{sub x} films deposited on polymer substrates exhibited good water vapor blocking properties with low water vapor transmission rates (WVTRs). - Abstract: Here, we report the fabrication of low-temperature sol-gel-derived aluminum oxide (AlO{sub x}) films via ultraviolet (UV) annealing and the investigation of their water vapor blocking properties by measuring the water vapor transmission rates (WVTRs). The UV annealing process induced the formation of a dense metal-oxygen-metal bond (Al-O-Al structure) at low temperatures (<200 °C) that are compatible with commercial plastic substrates. The density of the UV-annealed AlO{sub x} thin film at 180 °C was comparable to that of AlO{sub x} thin films that have been thermally annealed at 350 °C. Furthermore, the UV-annealed AlO{sub x} thin films exhibited a high optical transparency in the visible region (>99%) and good electrical insulating properties (∼10{sup −7} A/cm{sup 2} at 2 MV/cm). Finally, we confirmed that a dense AlO{sub x} thin film was successfully deposited onto the plastic substrate via UV annealing at low temperatures, leading to a substantial reduction in the WVTRs. The Ca corrosion test was used to measure the WVTRs of AlO{sub x} thin films deposited onto polyethylene naphthalate or polyimide substrates, determined to be 0.0095 g m{sup −2} day{sup −1} (25 °C, 50% relative humidity) and 0.26 g m{sup −2} day{sup −1}, respectively.

  14. Thermodynamics of Small Alkali Metal Halide Cluster Ions: Comparison of Classical Molecular Simulations with Experiment and Quantum Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Vlcek, Lukas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Uhlik, Filip [Charles Univ., Prague (Czech Republic); Moucka, Filip [Purkinje Univ. (Czech Republic); Nezbeda, Ivo [Purkinje Univ. (Czech Republic); Academy of Sciences of the Czech Republic (ASCR), Prague (Czech Republic); Chialvo, Ariel A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-12-16

    We evaluate the ability of selected classical molecular models to describe the thermodynamic and structural aspects of gas-phase hydration of alkali halide ions and the formation of small water clusters. To understand the effect of many-body interactions (polarization) and charge penetration effects on the accuracy of a force field, we perform Monte Carlo simulations with three rigid water models using different functional forms to account for these effects: (i) point charge non-polarizable SPC/E, (ii) Drude point charge polarizable SWM4- DP, and (iii) Drude Gaussian charge polarizable BK3. Model predictions are compared with experimental Gibbs free energies and enthalpies of ion hydration, and with microscopic structural properties obtained from quantum DFT calculations. We find that all three models provide comparable predictions for pure water clusters and cation hydration, but differ significantly in their description of anion hydration. None of the investigated classical force fields can consistently and quantitatively reproduce the experimental gas phase hydration thermodynamics. The outcome of this study highlights the relation between the functional form that describes the effective intermolecular interactions and the accuracy of the resulting ion hydration properties.

  15. Thermal conductivity of molten alkali metal fluorides (LiF, NaF, KF) and their mixtures.

    Science.gov (United States)

    Ishii, Yoshiki; Sato, Keisuke; Salanne, Mathieu; Madden, Paul A; Ohtori, Norikazu

    2014-03-27

    The thermal conductivities of molten alkali fluorides (LiF, NaF, and KF) and their mixtures (LiF-NaF, LiF-KF, and NaF-KF binaries and LiF-NaF-KF ternary) are predicted using molecular dynamics simulation with the Green-Kubo method. A polarizable ion model is used to describe the interionic interactions. All the systems except LiF-KF and LiF-NaF-KF mixtures follow a scaling law: it is proportionnal to mA (-1/2)(N/V)(2/3), where mA is the arithmetic average of the ionic species masses in a given melt and N is the total number of ions included in the system volume V. In LiF-KF and LiF-NaF-KF mixtures a significant departure from the scaling law is observed. By examining separately the effects of the cation mass and size asymmetry in LiF-KF mixtures, we show that both of them account for half of the deviation. Finally, we observe that the temperature dependence of the thermal conductivity is very small in these molten fluorides.

  16. Effect of alkali metal ions on the pyrrole and pyridine π-electron systems in pyrrole-2-carboxylate and pyridine-2-carboxylate molecules: FT-IR, FT-Raman, NMR and theoretical studies

    Science.gov (United States)

    Świderski, G.; Wojtulewski, S.; Kalinowska, M.; Świsłocka, R.; Lewandowski, W.

    2011-05-01

    The FT-IR, FT-Raman and 1H and 13C NMR spectra of pyrrole-2-carboxylic acid (PCA) and lithium, sodium, potassium, rubidium and caesium pyrrole-2-carboxylates were recorded, assigned and compared in the Li → Na → K → Rb → Cs salt series. The effect of alkali metal ions on the electronic system of ligands was discussed. The obtained results were compared with previously reported ones for pyridine-2-carboxylic acid and alkali metal pyridine-2-carboxylates. Calculations for pyrrole-2-carboxylic acid and Li, Na, K pyrrole-2-carboxylates in B3LYP/6-311++G ** level and Møller-Plesset method in MP2/6-311++G ** level were made. Bond lengths, angles and dipole moments as well as aromaticity indices (HOMA, EN, GEO, I 6) for the optimized structures of pyrrole-2-carboxylic acid (PCA) and lithium, sodium, potassium pyrrole-2-carboxylates were also calculated. The degree of perturbation of the aromatic system of ligand under the influence of metals in the Li → Cs series was investigated with the use of statistical methods (linear correlation), calculated aromaticity indices and Mulliken, NBO and ChelpG population analysis method. Additionally, the Bader theory (AIM) was applied to setting the characteristic of the bond critical points what confirmed the influence of alkali metals on the pyrrole ring.

  17. Numerical analysis of fragmentation processes of liquid metal in vapor explosions using Moving Particle Semi-implicit method

    International Nuclear Information System (INIS)

    Ikeda, Hirokazu; Matsuura, Fumio; Koshizuka, Seiichi; Oka, Yoshiaki

    1998-01-01

    Fragmentation of liquid metal takes place as basic processes of vapor explosions. This leads to rapid evaporation on the stretched interface. To date, a number of models explaining the fragmentation mechanisms have been proposed. However, few evidence has been obtained from the experiment because the phenomena are rapid. In Moving Particle Semi-implicit (MPS) method, grids are not necessary so that fluid fragmentation as well as multi-fluid thermal hydraulics can be analyzed. A numerical model of evaporation is developed for the present study. Impingement of water jets on a liquid metal pool is analyzed using the MPS method to investigate two typical models explaining the fragmentation mechanisms: Kim-Corradini and Ciccarelli-Frost models. Penetration of the water jet, which is assumed in Kim-Corradini model, is not observed in the calculation results. A filament of the liquid metal is observed between two water jets as assumed in Ciccarelli-Frost model. The filament appears when the jet density is smaller than the pool density, while the penetration appears when the jet density is hypothetically larger. The usual combinations of densities in vapor explosions are in the region of Ciccarelli-Frost model. (author)

  18. Experimental and theoretical determinations of the absolute ionization cross section of alkali metals by electron impact in the energy range from 100 to 2000 eV

    International Nuclear Information System (INIS)

    Jalin, Rene

    1972-01-01

    The absolute electron impact ionization cross sections for the alkali metals in the energy range between 100 eV and 2000 eV were measured by the non-modulated crossed beam technique. The neutral beam of alkali atoms is produced by a Knudsen cell and crossed at right angles with the electron beam. The ions formed are collected on a plate and their intensity determined with a D.C. amplifier. The neutral beam is condensed on a cold trap cooled with liquid nitrogen, this temperature being much lower than that required to obtain total condensation. The amount of metal deposited is measured by the isotopic dilution technique and by atomic absorption, and the density of the atoms in the neutral beam is calculated. The total absolute ionization cross sections can then be determined. All possible errors have been carefully analyzed and their magnitudes estimated. The absolute ionization cross section for Li at an energy of 500 eV is: Q Li = 0,358 x 10 -16 cm 2 . This value is half of that obtained by Mac Farland and Kinney. The partial ionization cross sections for the singly and multiply charged ions is determined with a mass spectrometer attached to this apparatus. For the singly charged ions, the variation of the cross section with the energy of the ionizing electrons is in agreement with the optically allowed transition law: Q = A log BE/E. From the variation of Q with E, the squared matrix elements of the transition moment (|M i |) 2 are determined for all the elements studied. New calculations of the ionization cross section of Li and Na were performed in the framework of the Born-Bethe approximation as modified by Gaudin and Botter to take into account collisions with large momentum variation of the incident electron. Hartree-Fock type wave functions for the ground state atom (tabulated by Clementi) were used. The calculated values are in good agreement with our experimental results and with the former theoretical results calculated by various methods. This work also

  19. Method for removing heavy metal and nitrogen oxides from flue gas, device for removing heavy metal and nitrogen oxides from flue gas

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hann-Sheng; Livengood, Charles David

    1997-12-01

    A method for the simultaneous removal of oxides and heavy metals from a fluid is provided comprising combining the fluid with compounds containing alkali and sulfur to create a mixture; spray drying the mixture to create a vapor phase and a solid phase; and isolating the vapor phase from the solid phase. A device is also provided comprising a means for spray-drying flue gas with alkali-sulfide containing liquor at a temperature sufficient to cause the flue gas to react with the compounds so as to create a gaseous fraction and a solid fraction and a means for directing the gaseous fraction to a fabric filter.

  20. An evaluation of absorption spectroscopy to monitor YBa2Cu3O7-x precursors for metal organics chemical vapor deposition processing

    International Nuclear Information System (INIS)

    Matthew Edward Thomas

    1999-01-01

    Absorption spectroscopy was evaluated as a technique to monitor the metal organics chemical vapor deposition (MOCVD) process for forming YBa 2 Cu 3 O 7-x superconducting coated conductors. Specifically, this study analyzed the feasibility of using absorption spectroscopy to monitor the MOCVD supply vapor concentrations of the organic ligand 2,2,6,6-tetramethyl-3,5-heptanedionate (TMHD) metal chelates of barium, copper, and yttrium. Ba(TMHD) 2 , Cu(TMHD) 2 , and Y(TMHD) 3 compounds have successfully been vaporized in the MOCVD processing technique to form high temperature superconducting ''coated conductors,'' a promising technology for wire fabrication. The absorption study of the barium, copper, and yttrium (TMHD) precursors was conducted in the ultraviolet wavelength region from 200nm to 400nm. To simulate the MOCVD precursor flows the Ba(TMHD) 2 , Cu(TMHD) 2 , and Y(TMHD) 3 complexes were vaporized at vacuum pressures of (0.03--10)Torr. Spectral absorption scans of each precursor were conducted to examine potential measurement wavelengths for determining vapor concentrations of each precursor via Beer's law. The experimental results show that under vacuum conditions the barium, copper, and yttrium (TMHD) precursors begin to vaporize between 90 C and 135 C, which are considerably lower vaporization temperatures than atmospheric thermal gravimetric analyses indicate. Additionally, complete vaporization of the copper and yttrium (TMHD) precursors occurred during rapid heating at temperatures between 145 C and 195 C and after heating at constant temperatures between 90 C and 125 C for approximately one hour, whereas the Ba(TMHD) 2 precursor did not completely vaporize. At constant temperatures, near constant vaporization levels for each precursor were observed for extended periods of time. Detailed spectroscopic scans at stable vaporization conditions were conducted

  1. Volatile organometallic complexes suitable for use in chemical vapor depositions on metal oxide films

    Science.gov (United States)

    Giolando, Dean M.

    2003-09-30

    Novel ligated compounds of tin, titanium, and zinc are useful as metal oxide CVD precursor compounds without the detriments of extreme reactivity yet maintaining the ability to produce high quality metal oxide coating by contact with heated substrates.

  2. Hydrogen and syngas production by catalytic gasification of algal biomass (Cladophora glomerata L.) using alkali and alkaline-earth metals compounds.

    Science.gov (United States)

    Ebadi, Abdol Ghaffar; Hisoriev, Hikmat; Zarnegar, Mohammad; Ahmadi, Hamed

    2018-01-02

    The steam gasification of algal biomass (Cladophora glomerata L.) in presence of alkali and alkaline-earth metal compounds catalysts was studied to enhance the yield of syngas and reduce its tar content through cracking and reforming of condensable fractions. The commercial catalysts used include NaOH, KHCO 3 , Na 3 PO 4 and MgO. The gasification runs carried out with a research scale, biomass gasification unit, show that the NaOH has a strong potential for production of hydrogen, along with the added advantages of char converting and tar destruction, allowing enhancement of produced syngas caloric value. When the temperature increased from 700°C to 900°C, the tar content in the gas sharply decreased, while the hydrogen yield increased. Increasing steam/biomass ratio significantly increased hydrogen yield and tar destruction; however, the particle size in the range of 0.5-2.5 mm played a minor role in the process.

  3. Ion chromatography with the indirect ultraviolet detection of alkali metal ions and ammonium using imidazolium ionic liquid as ultraviolet absorption reagent and eluent.

    Science.gov (United States)

    Liu, Yong-Qiang; Yu, Hong

    2016-08-01

    Indirect ultraviolet detection was conducted in ultraviolet-absorption-agent-added mobile phase to complete the detection of the absence of ultraviolet absorption functional group in analytes. Compared with precolumn derivatization or postcolumn derivatization, this method can be widely used, has the advantages of simple operation and good linear relationship. Chromatographic separation of Li(+) , Na(+) , K(+) , and NH4 (+) was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid/organic solvent as the mobile phase, in which imidazolium ionic liquids acted as ultraviolet absorption reagent and eluting agent. The retention behaviors of four kinds of cations are discussed, and the mechanism of separation and detection are described. The main factors influencing the separation and detection were the background ultraviolet absorption reagent and the concentration of hydrogen ion in the ion chromatography-indirect ultraviolet detection. The successful separation and detection of Li(+) , Na(+) , K(+) , and NH4 (+) within 13 min was achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.02, 0.11, 0.30, and 0.06 mg/L, respectively. A new separation and analysis method of alkali metal ions and ammonium by ion chromatography with indirect ultraviolet detection method was developed, and the application range of ionic liquid was expanded. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Colorimetric Detection of Water Vapor Using Metal-Organic Framework Composites.

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-12-01

    Purpose: Water vapor trapped in encapsulation materials or enclosed volumes leads to corrosion issues for critical NW components. Sandia National Laboratories has created a new diagnostic to indicate the presence of water in weapon systems. Impact: Component exposure to water now can be determined instantly, without need for costly, time-consuming analytical methods.

  5. Aerosol - assisted Chemical Vapor Deposition of Metal Oxide Structures: Zinc Oxide Rods

    Czech Academy of Sciences Publication Activity Database

    Vallejos, S.; Pizúrová, Naděžda; Čechal, J.; Grácia, I.; Cané, C.

    2017-01-01

    Roč. 2017, Č. 127 (2017), č. článku e56127. ISSN 1940-087X Institutional support: RVO:68081723 Keywords : Zinc oxide * columnar structures * rods * AACVD * non-catalyzed growth * vapor-solid mechanism Subject RIV: CA - Inorganic Chemistry OBOR OECD: Polymer science Impact factor: 1.232, year: 2016 https://www.jove.com/video/56127

  6. Kinetic study of the α-tocopherol-regeneration reaction of ubiquinol-10 in methanol and acetonitrile solutions: notable effect of the alkali and alkaline earth metal salts on the reaction rates.

    Science.gov (United States)

    Mukai, Kazuo; Oi, Masanori; Ouchi, Aya; Nagaoka, Shin-ichi

    2012-03-01

    A kinetic study of regeneration reaction of α-tocopherol (α-TocH) by ubiquinol-10 has been performed in the presence of four kinds of alkali and alkaline earth metal salts (LiClO(4), NaClO(4), NaI, and Mg(ClO(4))(2)) in methanol and acetonitrile solutions, using double-mixing stopped-flow spectrophotometry. The second-order rate constants (k(r)'s) for the reaction of α-tocopheroxyl (α-Toc•) radical with ubiquinol-10 increased and decreased notably with increasing concentrations of metal salts in methanol and acetonitrile, respectively. The k(r) values increased in the order of no metal salt NaClO(4) ~ NaI > LiClO(4) > Mg(ClO(4))(2) at the same concentration of metal salts. The metal salts having a smaller ionic radius of cation and a larger charge of cation gave a larger k(r) value in methanol, and a smaller k(r) value in acetonitrile. The effect of anion was almost negligible in both the solvents. Notable effects of metal cations on the UV-vis absorption spectrum of α-Toc• radical were observed in aprotic acetonitrile solution, suggesting complex formation between α-Toc• and metal cations. On the other hand, effects of metal cations were negligible in protic methanol, suggesting that the complex formation between α-Toc• and metal cations is hindered by the hydrogen bond between α-Toc• and methanol molecules. The difference between the reaction mechanisms in methanol and acetonitrile solutions was discussed on the basis of the results obtained. High concentrations of alkali and alkaline earth metal salts coexist with α-TocH and ubiquinol-10 in plasma, blood, and many tissues, suggesting the contribution of the metal salts to the above regeneration reaction in biological systems.

  7. Crystal structures and hydrogen bonding in the isotypic series of hydrated alkali metal (K, Rb and Cs) complexes with 4-amino-phenyl-arsonic acid.

    Science.gov (United States)

    Smith, Graham; Wermuth, Urs D

    2017-02-01

    The structures of the alkali metal (K, Rb and Cs) complex salts with 4-amino-phenyl-arsonic acid ( p -arsanilic acid) manifest an isotypic series with the general formula [ M 2 (C 6 H 7 AsNO 3 ) 2 (H 2 O) 3 ], with M = K {poly[di-μ 3 -4-amino-phenyl-arsonato-tri-μ 2 -aqua-dipotassium], [K 2 (C 6 H 7 AsNO 3 ) 2 (H 2 O) 3 ], (I)}, Rb {poly[di-μ 3 -4-amino-phenyl-arsonato-tri-μ 2 -aqua-dirubidium], [Rb 2 (C 6 H 7 AsNO 3 ) 2 (H 2 O) 3 ], (II)}, and Cs {poly[di-μ 3 -4-amino-phenyl-arsonato-tri-μ 2 -aqua-dirubidium], [Cs 2 (C 6 H 7 AsNO 3 ) 2 (H 2 O) 3 ], (III)}, in which the repeating structural units lie across crystallographic mirror planes containing two independent and different metal cations and a bridging water mol-ecule, with the two hydrogen p -arsanilate ligands and the second water mol-ecule lying outside the mirror plane. The bonding about the two metal cations in all complexes is similar, one five-coordinate, the other progressing from five-coordinate in (I) to eight-coordinate in both (II) and (III), with overall M -O bond-length ranges of 2.694 (5)-3.009 (7) (K), 2.818 (4)-3.246 (4) (Rb) and 2.961 (9)-3.400 (10) Å (Cs). The additional three bonds in (II) and (III) are the result of inter-metal bridging through the water ligands. Two-dimensional coordination polymeric structures with the layers lying parallel to (100) are generated through a number of bridging bonds involving the water mol-ecules (including hydrogen-bonding inter-actions), as well as through the arsanilate O atoms. These layers are linked across [100] through amine N-H⋯O hydrogen bonds to arsonate and water O-atom acceptors, giving overall three-dimensional network structures.

  8. Crystal structures and hydrogen bonding in the isotypic series of hydrated alkali metal (K, Rb and Cs) complexes with 4-amino­phenyl­arsonic acid

    Science.gov (United States)

    Smith, Graham; Wermuth, Urs D.

    2017-01-01

    The structures of the alkali metal (K, Rb and Cs) complex salts with 4-amino­phenyl­arsonic acid (p-arsanilic acid) manifest an isotypic series with the general formula [M 2(C6H7AsNO3)2(H2O)3], with M = K {poly[di-μ3-4-amino­phenyl­arsonato-tri-μ2-aqua-dipotassium], [K2(C6H7AsNO3)2(H2O)3], (I)}, Rb {poly[di-μ3-4-amino­phenyl­arsonato-tri-μ2-aqua-dirubidium], [Rb2(C6H7AsNO3)2(H2O)3], (II)}, and Cs {poly[di-μ3-4-amino­phenyl­arsonato-tri-μ2-aqua-dirubidium], [Cs2(C6H7AsNO3)2(H2O)3], (III)}, in which the repeating structural units lie across crystallographic mirror planes containing two independent and different metal cations and a bridging water mol­ecule, with the two hydrogen p-arsanilate ligands and the second water mol­ecule lying outside the mirror plane. The bonding about the two metal cations in all complexes is similar, one five-coordinate, the other progressing from five-coordinate in (I) to eight-coordinate in both (II) and (III), with overall M—O bond-length ranges of 2.694 (5)–3.009 (7) (K), 2.818 (4)–3.246 (4) (Rb) and 2.961 (9)–3.400 (10) Å (Cs). The additional three bonds in (II) and (III) are the result of inter-metal bridging through the water ligands. Two-dimensional coordination polymeric structures with the layers lying parallel to (100) are generated through a number of bridging bonds involving the water mol­ecules (including hydrogen-bonding inter­actions), as well as through the arsanilate O atoms. These layers are linked across [100] through amine N—H⋯O hydrogen bonds to arsonate and water O-atom acceptors, giving overall three-dimensional network structures. PMID:28217343

  9. Extraction process for removing metallic impurities from alkalide metals

    Science.gov (United States)

    Royer, Lamar T.

    1988-01-01

    A development is described for removing metallic impurities from alkali metals by employing an extraction process wherein the metallic impurities are extracted from a molten alkali metal into molten lithium metal due to the immiscibility of the alkali metals in lithium and the miscibility of the metallic contaminants or impurities in the lithium. The purified alkali metal may be readily separated from the contaminant-containing lithium metal by simple decanting due to the differences in densities and melting temperatures of the alkali metals as compared to lithium.

  10. Milk-alkali syndrome

    Science.gov (United States)

    Calcium-alkali syndrome; Cope syndrome; Burnett syndrome; Hypercalcemia; Calcium metabolism disorder ... Milk-alkali syndrome is almost always caused by taking too many calcium supplements, usually in the form of calcium ...

  11. Metal organic chemical vapor deposition of 111-v compounds on silicon

    Science.gov (United States)

    Vernon, Stanley M.

    1986-01-01

    Expitaxial composite comprising thin films of a Group III-V compound semiconductor such as gallium arsenide (GaAs) or gallium aluminum arsenide (GaAlAs) on single crystal silicon substrates are disclosed. Also disclosed is a process for manufacturing, by chemical deposition from the vapor phase, epitaxial composites as above described, and to semiconductor devices based on such epitaxial composites. The composites have particular utility for use in making light sensitive solid state solar cells.

  12. Kinetic study of the aroxyl radical-scavenging reaction of alpha-tocopherol in methanol solution: notable effect of the alkali and alkaline earth metal salts on the reaction rates.

    Science.gov (United States)

    Ouchi, Aya; Nagaoka, Shin-ichi; Abe, Kouichi; Mukai, Kazuo

    2009-10-08

    A kinetic study of the aroxyl (ArO*) radical-scavenging reaction of alpha-tocopherol (alpha-TocH) has been performed in the presence of six kinds of alkali and alkaline earth metal salts (LiI, LiClO(4), NaI, NaClO(4), KI, and Mg(ClO(4))(2)) in methanol solution, using stopped-flow spectrophotometry. The decay rate of the ArO* for the reaction of alpha-TocH with ArO* increased linearly with increasing concentration of metal salts. The second-order rate constants (k(s)) for the reaction of alpha-TocH with ArO* increased in the order of no metal salt concentration of metal salts. For example, the k(s) values in methanol solution including 4.00 x 10(-1) M of LiI and Mg(ClO(4))(2) were 3.04 and 1.30 times larger than that in the absence of metal salts, respectively. The alkali and alkaline earth metal salts having smaller ionic radius of cation and anion and larger charge of cation gave larger rate constants (k(s)). Effects of metal cations on the UV-vis absorption spectra of the alpha-Toc* (and ArO*) radical were negligible in methanol solution, suggesting that the complex formation between the alpha-Toc* (and ArO*) radical molecule and metal cations is hindered by the hydrogen bond between radical and methanol molecules. The results indicate that the hydrogen transfer reaction of alpha-TocH proceeds via an electron transfer intermediate from alpha-TocH to ArO* radicals followed by proton transfer. Both the coordinations of metal cations to the one-electron reduced anions of ArO* (ArO: (-)) and of counteranions to the one-electron oxidized cations of alpha-TocH (alpha-TocH(+)*) may stabilize the intermediate, resulting in the acceleration of electron transfer. On the other hand, the effect of metal salts on the rate of bimolecular self-reaction (2k(d)) of the alpha-Toc* radical was not observed. The result suggests that the hydrogen transfer reaction between two alpha-Toc* radical molecules proceeds via a one-step hydrogen atom transfer mechanism rather than via an

  13. Intrinsic luminescence of alkali silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Arbuzov, V.I.; Grabovskis, V.Y.; Tolstoi, M.N.; Vitol, I.K.

    1986-09-01

    This study obtains additional information on L centers and their role in electron excitation and intrinsic luminescence of a whole series. (Li, Na, K, Rb, and Cs) of alkali silicate glasses. The authors compare the features of the interaction with radiation of specimens of glass and crystal of a similar chemical composition, since silicates of alkali metals can be obtained in both the glassy and crystalline states.

  14. Metal-boride phase formation on tungsten carbide (WC-Co) during microwave plasma chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, Jamin M.; Catledge, Shane A., E-mail: catledge@uab.edu

    2016-02-28

    Graphical abstract: - Highlights: • A detailed phase analysis after PECVD boriding shows WCoB, CoB and/or W{sub 2}CoB{sub 2}. • EDS of PECVD borides shows boron diffusion into the carbide grain structure. • Nanoindentation hardness and modulus of borides is 23–27 GPa and 600–780 GPa. • Scratch testing shows hard coating with cracking at 40N and spallation at 70N. - Abstract: Strengthening of cemented tungsten carbide by boriding is used to improve the wear resistance and lifetime of carbide tools; however, many conventional boriding techniques render the bulk carbide too brittle for extreme conditions, such as hard rock drilling. This research explored the variation in metal-boride phase formation during the microwave plasma enhanced chemical vapor deposition process at surface temperatures from 700 to 1100 °C. We showed several well-adhered metal-boride surface layers consisting of WCoB, CoB and/or W{sub 2}CoB{sub 2} with average hardness from 23 to 27 GPa and average elastic modulus of 600–730 GPa. The metal-boride interlayer was shown to be an effective diffusion barrier against elemental cobalt; migration of elemental cobalt to the surface of the interlayer was significantly reduced. A combination of glancing angle X-ray diffraction, electron dispersive spectroscopy, nanoindentation and scratch testing was used to evaluate the surface composition and material properties. An evaluation of the material properties shows that plasma enhanced chemical vapor deposited borides formed at substrate temperatures of 800 °C, 850 °C, 900 °C and 1000 °C strengthen the material by increasing the hardness and elastic modulus of cemented tungsten carbide. Additionally, these boride surface layers may offer potential for adhesion of ultra-hard carbon coatings.

  15. Metal organic chemical vapor deposition of environmental barrier coatings for the inhibition of solid deposit formation from heated jet fuel

    Science.gov (United States)

    Mohan, Arun Ram

    Solid deposit formation from jet fuel compromises the fuel handling system of an aviation turbine engine and increases the maintenance downtime of an aircraft. The deposit formation process depends upon the composition of the fuel, the nature of metal surfaces that come in contact with the heated fuel and the operating conditions of the engine. The objective of the study is to investigate the effect of substrate surfaces on the amount and nature of solid deposits in the intermediate regime where both autoxidation and pyrolysis play an important role in deposit formation. A particular focus has been directed to examining the effectiveness of barrier coatings produced by metal organic chemical vapor deposition (MOCVD) on metal surfaces for inhibiting the solid deposit formation from jet fuel degradation. In the first part of the experimental study, a commercial Jet-A sample was stressed in a flow reactor on seven different metal surfaces: AISI316, AISI 321, AISI 304, AISI 347, Inconel 600, Inconel 718, Inconel 750X and FecrAlloy. Examination of deposits by thermal and microscopic analysis shows that the solid deposit formation is influenced by the interaction of organosulfur compounds and autoxidation products with the metal surfaces. The nature of metal sulfides was predicted by Fe-Ni-S ternary phase diagram. Thermal stressing on uncoated surfaces produced coke deposits with varying degree of structural order. They are hydrogen-rich and structurally disordered deposits, spherulitic deposits, small carbon particles with relatively ordered structures and large platelets of ordered carbon structures formed by metal catalysis. In the second part of the study, environmental barrier coatings were deposited on tube surfaces to inhibit solid deposit formation from the heated fuel. A new CVD system was configured by the proper choice of components for mass flow, pressure and temperature control in the reactor. A bubbler was designed to deliver the precursor into the reactor

  16. Study of structural and spectroscopic behavior of Sm3+ ions in lead-zinc borate glasses containing alkali metal ions

    Science.gov (United States)

    Sasi Kumar, M. V.; Babu, S.; Rajeswara Reddy, B.; Ratnakaram, Y. C.

    2017-06-01

    High luminescence behavior of rare earth inorganic glasses have a variety of uses in the industry. In the past few decades, rare earth ions with characteristic photonics applications are being hosted by heavy metal oxide glasses. Among the rare earth ions Sm3+ ion has features which make it apt for high density optical storage. The authors of the paper have experimented to synthesize Sm3+ doped glasses. In this regard a new series of borate glasses doped with 1 mol% Sm3+ ion are developed by using melt-quenching technique. XRD, FTIR, optical absorption, luminescence techniques are used to study the various characteristics of Sm3+ ion in the present glass matrices. The XRD spectra confirms the amorphous nature of glasses. Further, the researchers have used differential thermal analysis to study the glass transition temperature. The structural groups in the prepared glasses are studied using Fourier transform infrared spectra. From the measurement of its optical absorption, three phenomenological Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6) have been computed. Based on these Judd-Ofelt intensity parameters, radiative properties such as radiative probabilities (Arad), branching ratios (β), and radiative life time (τR) are calculated. The excitation spectra of Sm3+ doped lithium heavy metal borate glass matrix is recorded under the emission wavelength of 600 nm. The emission spectra are recorded under 404 nm excitation wavelength. From various emission transitions, 4G5/2 → 6H7/2 and 4G5/2 → 6H9/2 bands could be of interest for various applications. The decay profiles of 4G5/2 level exhibit single exponential nature in all the prepared glass matrices. The potassium glass matrix exhibits higher quantum efficiency than the other glass matrices. Finally, by going through these several spectroscopic characterizations, it is concluded that the prepared Sm3+ doped lead-zinc borate glasses might be useful for visible light applications.

  17. Selectivity of externally facing ion-binding sites in the Na/K pump to alkali metals and organic cations.

    Science.gov (United States)

    Ratheal, Ian M; Virgin, Gail K; Yu, Haibo; Roux, Benoît; Gatto, Craig; Artigas, Pablo

    2010-10-26

    The Na/K pump is a P-type ATPase that exchanges three intracellular Na(+) ions for two extracellular K(+) ions through the plasmalemma of nearly all animal cells. The mechanisms involved in cation selection by the pump's ion-binding sites (site I and site II bind either Na(+) or K(+); site III binds only Na(+)) are poorly understood. We studied cation selectivity by outward-facing sites (high K(+) affinity) of Na/K pumps expressed in Xenopus oocytes, under voltage clamp. Guanidinium(+), methylguanidinium(+), and aminoguanidinium(+) produced two phenomena possibly reflecting actions at site III: (i) voltage-dependent inhibition (VDI) of outwardly directed pump current at saturating K(+), and (ii) induction of pump-mediated, guanidinium-derivative-carried inward current at negative potentials without Na(+) and K(+). In contrast, formamidinium(+) and acetamidinium(+) induced K(+)-like outward currents. Measurement of ouabain-sensitive ATPase activity and radiolabeled cation uptake confirmed that these cations are external K(+) congeners. Molecular dynamics simulations indicate that bound organic cations induce minor distortion of the binding sites. Among tested metals, only Li(+) induced Na(+)-like VDI, whereas all metals tested except Na(+) induced K(+)-like outward currents. Pump-mediated K(+)-like organic cation transport challenges the concept of rigid structural models in which ion specificity at site I and site II arises from a precise and unique arrangement of coordinating ligands. Furthermore, actions by guanidinium(+) derivatives suggest that Na(+) binds to site III in a hydrated form and that the inward current observed without external Na(+) and K(+) represents cation transport when normal occlusion at sites I and II is impaired. These results provide insights on external ion selectivity at the three binding sites.

  18. High mobility single-crystalline-like GaAs thin films on inexpensive flexible metal substrates by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, P., E-mail: pdutta2@central.uh.edu; Rathi, M.; Gao, Y.; Yao, Y.; Selvamanickam, V. [Department of Mechanical Engineering, University of Houston, Houston, Texas 77204 (United States); Zheng, N.; Ahrenkiel, P. [Department of Nanoscience and Nanoengineering, South Dakota School of Mines and Technology, Rapid City, South Dakota 57701 (United States); Martinez, J. [Materials Evaluation Laboratory, NASA Johnson Space Center, Houston, Texas 77085 (United States)

    2014-09-01

    We demonstrate heteroepitaxial growth of single-crystalline-like n and p-type doped GaAs thin films on inexpensive, flexible, and light-weight metal foils by metal-organic chemical vapor deposition. Single-crystalline-like Ge thin film on biaxially textured templates made by ion beam assisted deposition on metal foil served as the epitaxy enabling substrate for GaAs growth. The GaAs films exhibited strong (004) preferred orientation, sharp in-plane texture, low grain misorientation, strong photoluminescence, and a defect density of ∼10{sup 7 }cm{sup −2}. Furthermore, the GaAs films exhibited hole and electron mobilities as high as 66 and 300 cm{sup 2}/V-s, respectively. High mobility single-crystalline-like GaAs thin films on inexpensive metal substrates can pave the path for roll-to-roll manufacturing of flexible III-V solar cells for the mainstream photovoltaics market.

  19. Coupling scales for modelling heavy metal vaporization from municipal solid waste incineration in a fluid bed by CFD.

    Science.gov (United States)

    Soria, José; Gauthier, Daniel; Flamant, Gilles; Rodriguez, Rosa; Mazza, Germán

    2015-09-01

    Municipal Solid Waste Incineration (MSWI) in fluidized bed is a very interesting technology mainly due to high combustion efficiency, great flexibility for treating several types of waste fuels and reduction in pollutants emitted with the flue gas. However, there is a great concern with respect to the fate of heavy metals (HM) contained in MSW and their environmental impact. In this study, a coupled two-scale CFD model was developed for MSWI in a bubbling fluidized bed. It presents an original scheme that combines a single particle model and a global fluidized bed model in order to represent the HM vaporization during MSW combustion. Two of the most representative HM (Cd and Pb) with bed temperatures ranging between 923 and 1073K have been considered. This new approach uses ANSYS FLUENT 14.0 as the modelling platform for the simulations along with a complete set of self-developed user-defined functions (UDFs). The simulation results are compared to the experimental data obtained previously by the research group in a lab-scale fluid bed incinerator. The comparison indicates that the proposed CFD model predicts well the evolution of the HM release for the bed temperatures analyzed. It shows that both bed temperature and bed dynamics have influence on the HM vaporization rate. It can be concluded that CFD is a rigorous tool that provides valuable information about HM vaporization and that the original two-scale simulation scheme adopted allows to better represent the actual particle behavior in a fluid bed incinerator. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Synthesis of carbon nanomaterials by catalytic chemical vapor deposition: growth mechanisms on metal powders and foils

    OpenAIRE

    Romero Rodríguez, Pablo

    2017-01-01

    Actualmente, las excelentes propiedades proporcionadas a escala nanométrica por los nanomateriales de carbono, como nanotubos y grafeno, motivan la propuesta teórica de un gran número de aplicaciones. Estos nanomateriales se pueden producir por deposición química en fase vapor (CVD), que consiste en la descomposición térmica de hidrocarburos sobre catalizadores metálicos. La técnica de CVD permite, a través del control de las condiciones de síntesis y la composición y morfología del catalizad...

  1. Vapor Phase Sensing Using Metal Nanorod Thin Films Grown by Cryogenic Oblique Angle Deposition

    Directory of Open Access Journals (Sweden)

    Piyush Shah

    2013-01-01

    Full Text Available We demonstrate the chemical sensing capability of silver nanostructured films grown by cryogenic oblique angle deposition (OAD. For comparison, the films are grown side by side at cryogenic (~100 K and at room temperature (~300 K by e-beam evaporation. Based on the observed structural differences, it was hypothesized that the cryogenic OAD silver films should show an increased surface enhanced Raman scattering (SERS sensitivity. COMSOL simulation results are presented to validate this hypothesis. Experimental SERS results of 4-aminobenzenethiol (4-ABT Raman test probe molecules in vapor phase show good agreement with the simulation and indicate promising SERS applications for these nanostructured thin films.

  2. Cytogenetic effects of combined impact caused by 232Th and ions of alkali and heavy metals to plant meristem

    International Nuclear Information System (INIS)

    Evseeva, T.I.; Khramova, E.S.; Geras'kin, S.A.

    2001-01-01

    The cytogenetic effects of complex and separate action of K, Cd and 232 Th on plant - Tradescantia (clone 02) and Allium cepa - meristematic root tip cells were investigated. It was shown that cytogenetic effects of 232 Th result mainly in its ability to induce genome damages. Cd in concentration studied (it was equal to 60 mg/l) was not induce vagrants increasing and this effect does not intensified by the combined action with 232 Th. Cd induced the essential increase (1.5 times more than in control group) of the chromosome type aberration frequency and the fragments frequency, while the mitotic index was decreased. It was shown that the difference in plant cell responses to K and Cd complex action with one and the same agent - 232 Th - is due to the differences in the chemical element characteristics and their significance for biological objects. The element vital for biological objects - K -protect plant cells from 232 Th effect, but the two highly toxic metals - 232 Th and Cd - complex action results in the synergic increasing of their effects on plant cells. (author)

  3. Estimate of repulsive interatomic pair potentials by low-energy alkali-metal-ion scattering and computer simulation

    International Nuclear Information System (INIS)

    Ghrayeb, R.; Purushotham, M.; Hou, M.; Bauer, E.

    1987-01-01

    Low-energy ion scattering is used in combination with computer simulation to study the interaction potential between 600-eV potassium ions and atoms in metallic surfaces. A special algorithm is described which is used with the computer simulation code marlowes. This algorithm builds up impact areas on the simulated solid surface from which scattering cross sections can be estimated with an accuracy better than 1%. This can be done by calculating no more than a couple of thousand trajectories. The screening length in the Moliere approximation to the Thomas-Fermi potential is fitted in such a way that the ratio between the calculated cross sections for double and single scattering matches the scattering intensity ratio measured experimentally and associated with the same mechanisms. The consistency of the method is checked by repeating the procedure for different incidence conditions and also by predicting the intensities associated with other surface scattering mechanisms. The screening length estimates are found to be insensitive to thermal vibrations. The calculated ratios between scattering cross sections by different processes are suggested to be sensitive enough to the relative atomic positions in order to be useful in surface-structure characterization

  4. InAs/GaSb core-shell nanowires grown on Si substrates by metal-organic chemical vapor deposition

    Science.gov (United States)

    Ji, Xianghai; Yang, Xiaoguang; Du, Wenna; Pan, Huayong; Luo, Shuai; Ji, Haiming; Xu, Hongqi; Yang, Tao

    2017-06-01

    We report the growth of InAs/GaSb core-shell heterostructure nanowires with smooth sidewalls on Si substrates using metal-organic chemical vapor deposition (MOCVD) with no assistance from foreign catalysts. Sb adatoms were observed to strongly influence the morphology of the GaSb shell. In particular, Ga droplets form on the nanowire tips when a relatively low TMSb flow rate is used, whereas the droplets are missing and the radial growth of the GaSb is enhanced due to a reduction in the diffusion length of the Ga adatoms when the TMSb flow rate is increased. Moreover, transmission electron microscopy measurements revealed that the GaSb shell coherently grew on the InAs core without any misfit dislocations.

  5. Effect of Water Vapor and Surface Morphology on the Low Temperature Response of Metal Oxide Semiconductor Gas Sensors.

    Science.gov (United States)

    Maier, Konrad; Helwig, Andreas; Müller, Gerhard; Hille, Pascal; Eickhoff, Martin

    2015-09-23

    In this work the low temperature response of metal oxide semiconductor gas sensors is analyzed. Important characteristics of this low-temperature response are a pronounced selectivity to acid- and base-forming gases and a large disparity of response and recovery time constants which often leads to an integrator-type of gas response. We show that this kind of sensor performance is related to the trend of semiconductor gas sensors to adsorb water vapor in multi-layer form and that this ability is sensitively influenced by the surface morphology. In particular we show that surface roughness in the nanometer range enhances desorption of water from multi-layer adsorbates, enabling them to respond more swiftly to changes in the ambient humidity. Further experiments reveal that reactive gases, such as NO₂ and NH₃, which are easily absorbed in the water adsorbate layers, are more easily exchanged across the liquid/air interface when the humidity in the ambient air is high.

  6. Nanoscale leakage current measurements in metal organic chemical vapor deposition crystalline SrTiO3 films

    International Nuclear Information System (INIS)

    Rozier, Y.; Gautier, B.; Hyvert, G.; Descamps, A.; Plossu, C.; Dubourdieu, C.; Ducroquet, F.

    2009-01-01

    The properties of SrTiO 3 thin films, grown by liquid injection metal organic chemical vapor deposition on Si/SiO 2 , using a mixture of precursors, have been investigated at the nanoscale using an Atomic Force Microscope in the so-called Conductive Atomic Force Microscopy mode. Maps of the leakage currents with a nanometric resolution have been obtained on films elaborated at different temperatures and stoichiometries in order to discriminate the role of each parameter on the onset of leakage currents in the resulting layers. It appears that the higher the deposition temperature, the higher the leakage currents of the films. The mapping with a nanometric precision allows to show a heterogeneous behaviour of the surface with leaky grains and insulating boundaries. The study of films elaborated at the same temperature with different compositions supports the assumption that the leakage currents on Ti-rich layers are far higher than on Sr-rich layers

  7. Nanoscale leakage current measurements in metal organic chemical vapor deposition crystalline SrTiO{sub 3} films

    Energy Technology Data Exchange (ETDEWEB)

    Rozier, Y. [Lyon Institute of Nanotechnology (INL), CNRS-UMR5270, INSA Lyon, 7 avenue Capelle, 69621 VILLEURBANNE Cedex (France); Gautier, B. [Lyon Institute of Nanotechnology (INL), CNRS-UMR5270, INSA Lyon, 7 avenue Capelle, 69621 VILLEURBANNE Cedex (France)], E-mail: bgautier@insa-lyon.fr; Hyvert, G.; Descamps, A.; Plossu, C. [Lyon Institute of Nanotechnology (INL), CNRS-UMR5270, INSA Lyon, 7 avenue Capelle, 69621 VILLEURBANNE Cedex (France); Dubourdieu, C. [Laboratoire des Materiaux et du Genie Physique (LMGP), CNRS, INPG, 3 parvis L. Neel, BP 257, 38016 Grenoble Cedex 1 (France); Ducroquet, F. [Institut de Microelectronique, Electromagnetisme et Photonique (IMEP), 3, rue Parvis Louis Neel BP 257, 38016 GRENOBLE Cedex 1 (France)

    2009-01-30

    The properties of SrTiO{sub 3} thin films, grown by liquid injection metal organic chemical vapor deposition on Si/SiO{sub 2}, using a mixture of precursors, have been investigated at the nanoscale using an Atomic Force Microscope in the so-called Conductive Atomic Force Microscopy mode. Maps of the leakage currents with a nanometric resolution have been obtained on films elaborated at different temperatures and stoichiometries in order to discriminate the role of each parameter on the onset of leakage currents in the resulting layers. It appears that the higher the deposition temperature, the higher the leakage currents of the films. The mapping with a nanometric precision allows to show a heterogeneous behaviour of the surface with leaky grains and insulating boundaries. The study of films elaborated at the same temperature with different compositions supports the assumption that the leakage currents on Ti-rich layers are far higher than on Sr-rich layers.

  8. Vibronic transitions in the alkali-metal (Li, Na, K, Rb) - alkaline-earth-metal (Ca, Sr) series: A systematic analysis of de-excitation mechanisms based on the graphical mapping of Frank-Condon integrals

    Science.gov (United States)

    Pototschnig, Johann V.; Meyer, Ralf; Hauser, Andreas W.; Ernst, Wolfgang E.

    2017-02-01

    Research on ultracold molecules has seen a growing interest recently in the context of high-resolution spectroscopy and quantum computation. After forming weakly bound molecules from atoms in cold collisions, the preparation of molecules in low vibrational levels of the ground state is experimentally challenging, and typically achieved by population transfer using excited electronic states. Accurate potential energy surfaces are needed for a correct description of processes such as the coherent de-excitation from the highest and therefore weakly bound vibrational levels in the electronic ground state via couplings to electronically excited states. This paper is dedicated to the vibrational analysis of potentially relevant electronically excited states in the alkali-metal (Li, Na, K, Rb)- alkaline-earth metal (Ca,Sr) diatomic series. Graphical maps of Frank-Condon overlap integrals are presented for all molecules of the group. By comparison to overlap graphics produced for idealized potential surfaces, we judge the usability of the selected states for future experiments on laser-enhanced molecular formation from mixtures of quantum degenerate gases.

  9. Half-metallic properties of the (1 1 0) surface of alkali earth metal monosilicides in the zinc blende phase

    International Nuclear Information System (INIS)

    Bialek, B; Lee, J I

    2011-01-01

    An all electron ab initio method was employed to study the electronic and magnetic properties of the (1 1 0) surface of alkaline-earth metal silicides: CaSi, SrSi and BaSi, in the zinc blende structure. The three surfaces are found to conserve the half-metallic properties of their bulk structures with a wide semiconducting energy gap in the spin-up channel. Half-metallic energy gap at the surfaces is small. In the CaSi surface it is of the order of k B T, which indicates that in the CaSi (1 1 0) a transition to a metallic state is possible due to temperature fluctuations. At the same time, the CaSi surface exhibits the strongest magnetic properties with 0.91 μ B magnetic moment on the Si atom in the topmost layer and 0.21 μ B magnetic moment on the Ca atom. In each of the three surfaces we observe a reduction of magnetic moments on the atoms in the subsurface layer and the enhancement of the magnetic moment on the atoms in the topmost layer, as compared with the properties of atoms in the bulk. An analysis of the calculated total and atom projected densities of states leads to a conclusion that the surface effects in the structures are short-range phenomena

  10. D- production by multiple charge-transfer collisions in metal-vapor targets. [1 to 50 keV D/sup +/

    Energy Technology Data Exchange (ETDEWEB)

    Schlachter, A.S.

    1977-09-01

    A beam of D/sup -/ions can be produced by multiple charge-transfer collisions of a D/sup +/ beam in a thick metal-vapor target. Cross sections and equilibrium charge-state fractions are presented and discussed.

  11. Vapor Phase Ketonization of Acetic Acid on Ceria Based Metal Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Changjun; Karim, Ayman M.; Lebarbier, Vanessa M.; Mei, Donghai; Wang, Yong

    2013-06-27

    The activities of CeO2, Mn2O3-CeO2 and ZrO2-CeO2 were measured for acetic acid ketonization under reaction conditions relevant to pyrolysis vapor upgrading. We show that the catalyst ranking changed depending on the reaction conditions. Mn2O3-CeO2 was the most active catalyst at 350 oC, while ZrO2 - CeO2 was the most active catalyst at 450 oC. Under high CO2 and steam concentration in the reactants, Mn2O3-CeO2 was the most active catalyst at 350 and 450 °C. The binding energies of steam and CO2 with the active phase were calculated to provide the insight into the tolerance of Mn2O3-CeO2 to steam and CO2.

  12. The effect of metal ion exchange and alkali metal doping on the electrical conductivity of the Faujasite-type zeolite 13X

    International Nuclear Information System (INIS)

    Swart, S.

    1983-12-01

    Zeolite 13X was synthesized in the sodium form. Some transition metal cations were introduced into the zeolite framework by ion exchange reactions. These different cationic zeolite forms were doped or impregnated with sodium metal, utilizing the adsorptive properties of the zeolite. An A.C. technique was used to determine the electrical conductivity of the dehydrated ion exchanged zeolites and the sodium impregnated zeolite samples as a function of temperature. The conductivity value obtained was used to determine some thermodynamic parameters relating to the conduction process. For the dehydrated ion exchanged zeolites the electrical conductivity showed a general decrease with a decreasing ion exchange capacity. The sodium impregnated zeolites showed an increase in conductivity with respect to the dehydrated unimpregnated samples. This was attributed to the presence of Na 6 5 + centres in the impregnated zeolites. The reduction of some of the metal cations by the sodium on impregnation did not appear to have any significant effect on the overall ionic conductivity of the samples. The conductivity as a function of temperature and pressure for the dehydrated sodium form of zeolite 13X and its impregnated counterpart was determined. The conductivity was found to increase with increasing pressure and temperature

  13. Syntheses and characterization of one-dimensional alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs)

    Energy Technology Data Exchange (ETDEWEB)

    Yohannan, Jinu P.; Vidyasagar, Kanamaluru, E-mail: kvsagar@iitm.ac.in

    2015-01-15

    Three new isostructural quaternary antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs) have been synthesized by using alkali metal thiosulfate flux and structurally characterized by X-ray diffraction. Their structures contain A{sup +} ions around the [Sb{sub 2}Sn{sub 3}S{sub 10}]{sup 2−} chains, which are built from SbS{sub 3} pyramids, SnS{sub 6} octahedra and SnS{sub 4} tetrahedra. Raman and Mössbauer spectroscopic measurements corroborate the oxidation states and coordination environments of Sb(III) and Sn(IV). All three compounds are wide band gap semiconductors. Potassium compound undergoes partial exchange with strontium, cadmium and lead ions. - Graphical abstract: Syntheses, crystal structure, spectroscopic and partial ion-exchange studies of new one-dimensional alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs) are described. - Highlights: • Syntheses of new alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs). • Wide band gap semiconductors with one-dimensional structure. • Topotactic partial exchange of K{sup +} ions of K{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} with Sr{sup 2+}, Cd{sup 2+} and Pb{sup 2+} ions.

  14. Synthesis of high performance ceramic fibers by chemical vapor deposition for advanced metallics reinforcing

    Science.gov (United States)

    Revankar, Vithal; Hlavacek, Vladimir

    1991-01-01

    The chemical vapor deposition (CVD) synthesis of fibers capable of effectively reinforcing intermetallic matrices at elevated temperatures which can be used for potential applications in high temperature composite materials is described. This process was used due to its advantage over other fiber synthesis processes. It is extremely important to produce these fibers with good reproducible and controlled growth rates. However, the complex interplay of mass and energy transfer, blended with the fluid dynamics makes this a formidable task. The design and development of CVD reactor assembly and system to synthesize TiB2, CrB, B4C, and TiC fibers was performed. Residual thermal analysis for estimating stresses arising form thermal expansion mismatch were determined. Various techniques to improve the mechanical properties were also performed. Various techniques for improving the fiber properties were elaborated. The crystal structure and its orientation for TiB2 fiber is discussed. An overall view of the CVD process to develop CrB2, TiB2, and other high performance ceramic fibers is presented.

  15. The role of the alkali and chalcogen atoms on the stability of the layered chalcogenide [Formula: see text] (A  =  alkali-metal; M  =  metal-cations; Q  =  chalcogen) compounds: a density functional theory investigation within van der Waals corrections.

    Science.gov (United States)

    Besse, Rafael; Da Silva, Juarez L F

    2017-01-25

    There is a great interest to design two-dimensional (2D) chalcogenide materials, however, our atomistic understanding of the major physical parameters that drive the formation of 2D or three-dimensional (3D) chalcogenides is far from satisfactory, in particular, for complex quaternary systems. To address this problem, we selected a set of quaternary 2D and 3D chalcogenide compounds, namely, [Formula: see text] (A  =  Li, K, Cs; Q  =  S, Se, Te), which were investigated by density functional theory calculations within van der Waals (vdW) corrections. Employing experimental crystal structures and well designed crystal modifications, we found that the average atomic radius of the alkali-metal, A, and chalcogen, Q, species play a crucial role in the stability of the 2D structures. For example, the 2D structures are energetically favored for smaller [Formula: see text] and larger [Formula: see text] average atomic radius, while 3D structures are favored at intermediate average atomic radius. Those results are explained in terms of strain minimization and Coulomb repulsion of the anionic species in the structure framework. Furthermore, the equilibrium lattice parameters are in excellent agreement with experimental results. Thus, the present insights can help in the design of stable quartenary 2D chalcogenide compounds.

  16. Fabrication of single-phase ε-GaSe films on Si(100) substrate by metal organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Chang, Chia-Chen; Zeng, Jia-Xian; Lan, Shan-Ming; Uen, Wu-Yih; Liao, Sen-Mao; Yang, Tsun-Neng; Ma, Wei-Yang; Chang, Kuo-Jen

    2013-01-01

    Single-phase ε-gallium selenide (GaSe) films were fabricated on Si(100) substrate by metal organic chemical vapor deposition using dual-source precursors: triethylgallium (TEG) and hydrogen selenide (H 2 Se) with the flow ratio of [H 2 Se]/[TEG] being maintained at 1.2. In particular, an arsine (AsH 3 ) flow was introduced to the Si substrate before the film deposition to induce an arsenic (As)-passivation effect on the substrate. The crystalline structure of GaSe films prepared was analyzed using X-ray diffraction and the surface morphology of them was characterized by scanning electron microscopy. It was found that the film quality could be improved by the As-passivation effect. The optical properties of the films were studied by temperature dependent photoluminescence (PL) measurements. PL spectra obtained with different distributions and intensities favored for resolving the superior material quality of the films produced on the substrate with As-passivation compared to those produced on the substrate without As-passivation. The former was dominated by the excitonic emissions for the whole temperature range of 20–300 K examined, while the latter was initially dominated by the defect-related emission at 1.907 eV for a low-temperature range ≦ 80 K and then became dominated by the weak excitonic emission band instead. The ε modification of GaSe films prepared was further recognized by the Raman scattering measurements conducted at room temperature. - Highlights: • Gallium selenide (GaSe) layered structures are fabricated on Si(100) substrate. • Metal–organic chemical vapor deposition is used for film fabrication. • Arsenic-passivation effects of Si substrate on the GaSe film quality are analyzed. • Photoluminescence measurements of GaSe polycrystals are reported

  17. Theoretical Investigation of the Structural Stabilities of Ceria Surfaces and Supported Metal Nanocluster in Vapor and Aqueous Phases

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Zhibo [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Liu, Ning [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Chen, Biaohua [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Li, Jianwei [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Mei, Donghai [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States

    2018-01-25

    Understanding the structural stability and dynamics at the interface between the solid metal oxide and aqueous phase is significant in a variety of industrial applications including heterogeneous catalysis and environmental remediation. In the present work, the stabilities of three low-index ceria (CeO2) surfaces, i.e., (111), (110) and (100) in vapor and aqueous phases were studied using ab initio molecular dynamics simulations and density functional theory (DFT) calculations. Gibbs surface free energies as a function of temperature, water partial pressure, and water coverages were calculated using DFT based atomistic thermodynamic approach. On the basis of surface free energies, the morphology and exposed surface structures of the CeO2 nanoparticle were predicted using Wulff construction principle. It is found that the partially hydroxylated (111) and (100) are two major surface structures of CeO2 nanoparticles in vapor phase at ambient temperature (300 K). As the temperature increases, the fully dehydrated (111) surface gradually becomes the most dominant surface structure. While in aqueous phase, the exposed surface of the CeO2 nanoparticle is dominated by the hydroxylated (110) structure at 393 K. Finally, the morphology and stability of a cuboctahedron Pt13 nanocluster supported on CeO2 surfaces in both gas and aqueous phases were investigated. In gas phase, the supported Pt13 nanocluster has the tendency to wetting the CeO2 surface due to the strong metal-support interaction. The calculated interaction energies suggest the CeO2(110) surface provides the best stability for the Pt13 nanocluster. The CeO2 supported Pt13 nanoclusters are oxidized. Compared to the gas phase, the morphology of the CeO2 supported Pt13 nanocluster is less distorted due to the solvation effect provided by surrounding water molecules in aqueous phase. More electrons are transferred from the Pt13 nanocluster to the CeO2 support, implying the supported Pt13 nanocluster is further

  18. Growth dynamics of carbon-metal particles and nanotubes synthesized by CO2 laser vaporization

    Science.gov (United States)

    Kokai, F.; Takahashi, K.; Yudasaka, M.; Iijima, S.

    To study the growth of carbon-Co/Ni particles and single-wall carbon nanotubes (SWNTs) by 20 ms CO2 laser-pulse irradiation of a graphite-Co/Ni (1.2 at.%) target in an Ar gas atmosphere (600 Torr), we used emission imaging spectroscopy and shadowgraphy with a temporal resolution of 1.67 ms. Wavelength-selected emission images showed that C2 emission was strong in the region close to the target (within 2 cm), while for the same region the blackbody radiation from the large clusters or particles increased with increasing distance from the target. Shadowgraph images showed that the viscous flow of carbon and metal species formed a mushroom or a turbulent cloud spreading slowly into the Ar atmosphere, indicating that particles and SWNTs continued to grow as the ejected material cooled. In addition, emission imaging spectroscopy at 1200 °C showed that C2 and hot clusters and particles with higher emission intensities were distributed over much wider areas. We discuss the growth dynamics of the particles and SWNTs through the interaction of the ambient Ar with the carbon and metal species released from the target by the laser pulse.

  19. New quaternary alkali metal cadmium selenites, A2Cd(SeO3)2 (A = K, Rb, and Cs) and Li2Cd3(SeO3)4

    Science.gov (United States)

    Lü, Minfeng; Jo, Hongil; Oh, Seung-Jin; Ok, Kang Min

    2017-12-01

    A series of new alkali metal cadmium selenites, A2Cd(SeO3)2 (A = K, Rb, and Cs) and Li2Cd3(SeO3)4 have been synthesized in phase pure forms through hydrothermal and solid-state reactions. Structural analyses using single crystal X-ray diffraction indicate that while A2Cd(SeO3)2 and Li2Cd3(SeO3)4 reveal layered structures consisting of CdO6 and SeO3 polyhedra, their symmetry, bonding modes, and the orientation of lone pairs on Se4+ cations are different. A closer examination suggests that the observed structural variations found in the reported materials are attributed to the structure-directing effect of alkali metal cations with different sizes. Scanning electron microscopy/energy dispersive analysis by X-ray, thermogravimetric analysis, Infrared and UV-vis diffuse reflectance spectroscopy, transformation reactions under hydrothermal conditions, and local dipole moment calculations for the reported materials are also reported.

  20. Crystal growth and evaluation of scintillation properties of Eu and alkali-metal co-doped LiSrAlF{sub 6} single crystals for thermal neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    Wakahara, Shingo; Yokota, Yuui; Yamaji, Akihiro; Fujimoto, Yutaka; Sugiyama, Makoto; Kurosawa, Shunsuke [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yanagida, Takayuki [New Industry Creation Hatchery Center (NICHe), 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Pejchal, Jan [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Institute of Physics AS CR, Cukrovarnicka 10, Prague 16253 (Czech Republic); Kawaguchi, Noriaki [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Tokuyama, Co. Ltd., Shibuya 3-chome, Shibuya-ku, Tokyo 150-8383 (Japan); Fukuda, Kentaro [Tokuyama, Co. Ltd., Shibuya 3-chome, Shibuya-ku, Tokyo 150-8383 (Japan); Yoshikawa, Akira [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan)

    2012-12-15

    In recent work, Na co-doping have found to improve the light output of Eu doped LiCaAlF{sub 6} (Eu:LiCAF) for thermal neutron scintillator. We grew Eu 2% and alkali metal 1% co-doped LiSAF crystals by Micro-Pulling down method to understand the effect of alkali metal co-doping on scintillation properties and mechanism compared with LiCAF. In photo- and {alpha}-ray induced radio-luminescence spectra of the all grown crystals, the emissions from d-f transition of Eu{sup 2+} were observed. Without relation to excitation source, decay times of co-doped LiSAF were longer than Eu only doped one. The light yield of Na, K and Cs co-doped LiSAF under {sup 252}Cf neutron excitation were improved. Especially, K co-doped Eu:LiSAF reached 33200 ph/n, which outperformed Eu only doped one by approximately 20% (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)