Method of handling radioactive alkali metal waste

DOEpatents

Wolson, Raymond D.; McPheeters, Charles C.

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.

Method of handling radioactive alkali metal waste

DOEpatents

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.

Upgrading platform using alkali metals

DOEpatents

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.

Controlled in-situ dissolution of an alkali metal

DOEpatents

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.

Method of making alkali metal hydrides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pecharsky, Vitalij K.; Gupta, Shalabh; Pruski, Marek

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.

Electrochemical devices utilizing molten alkali metal electrode-reactant

DOEpatents

Hitchcock, David C.; Mailhe, Catherine C.; De Jonghe, Lutgard C.

1986-01-01

Electrochemical cells are provided with a reactive metal to reduce the oxide of the alkali metal electrode-reactant. Cells employing a molten alkali metal electrode, e.g., sodium, in contact with a ceramic electrolyte, which is a conductor of the ions of the alkali metal forming the electrode, exhibit a lower resistance when a reactive metal, e.g., vanadium, is allowed to react with and reduce the alkali metal oxide. Such cells exhibit less degradation of the electrolyte and of the glass seals often used to joining the electrolyte to the other components of the cell under cycling conditions.

Electrochemical devices utilizing molten alkali metal electrode-reactant

DOEpatents

Hitchcock, D.C.; Mailhe, C.C.; De Jonghe, L.C.

1985-07-10

Electrochemical cells are provided with a reactive metal to reduce the oxide of the alkali metal electrode-reactant. Cells employing a molten alkali metal electrode, e.g., sodium, in contact with a ceramic electrolyte, which is a conductor of the ions of the alkali metal forming the electrode, exhibit a lower resistance when a reactive metal, e.g., vanadium, is allowed to react with and reduce the alkali metal oxide. Such cells exhibit less degradation of the electrolyte and of the glass seals often used to joining the electrolyte to the other components of the cell under cycling conditions.

Spill-Resistant Alkali-Metal-Vapor Dispenser

NASA Technical Reports Server (NTRS)

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.

Alkali Metal Handling Practices at NASA MSFC

NASA Technical Reports Server (NTRS)

Salvail, Patrick G.; Carter, Robert R.

2002-01-01

NASA Marshall Space Flight Center (MSFC) is NASA s principle propulsion development center. Research and development is coordinated and carried out on not only the existing transportation systems, but also those that may be flown in the near future. Heat pipe cooled fast fission cores are among several concepts being considered for the Nuclear Systems Initiative. Marshall Space Flight Center has developed a capability to handle high-purity alkali metals for use in heat pipes or liquid metal heat transfer loops. This capability is a low budget prototype of an alkali metal handling system that would allow the production of flight qualified heat pipe modules or alkali metal loops. The processing approach used to introduce pure alkali metal into heat pipe modules and other test articles are described in this paper.

40 CFR 721.4660 - Alcohol, alkali metal salt.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 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...

Recovery of alkali metal constituents from catalytic coal conversion residues

DOEpatents

Soung, W.Y.

In a coal gasification operation (32) or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by contacting them with water or an aqueous solution to remove water-soluble alkali metal constituents and produce an aqueous solution enriched in said constituents. The aqueous solution thus produced is then contacted with carbon dioxide to precipitate silicon constituents, the pH of the resultant solution is increased, preferably to a value in the range between about 12.5 and about 15.0, and the solution of increased pH is evaporated to increase the alkali metal concentration. The concentrated aqueous solution is then recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

Recovery of alkali metal constituents from catalytic coal conversion residues

DOEpatents

Soung, Wen Y.

1984-01-01

In a coal gasification operation (32) or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by contacting them (46, 53, 61, 69) with water or an aqueous solution to remove water-soluble alkali metal constituents and produce an aqueous solution enriched in said constituents. The aqueous solution thus produced is then contacted with carbon dioxide (63) to precipitate silicon constituents, the pH of the resultant solution is increased (81), preferably to a value in the range between about 12.5 and about 15.0, and the solution of increased pH is evaporated (84) to increase the alkali metal concentration. The concentrated aqueous solution is then recycled to the conversion process (86, 18, 17) where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

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

DOEpatents

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.

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

Code of Federal Regulations, 2010 CFR

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...

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

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 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...

Salts of alkali metal anions and process of preparing same

DOEpatents

Dye, James L.; Ceraso, Joseph M.; Tehan, Frederick J.; Lok, Mei Tak

1978-01-01

Compounds of alkali metal anion salts of alkali metal cations in bicyclic polyoxadiamines are disclosed. The salts are prepared by contacting an excess of alkali metal with an alkali metal dissolving solution consisting of a bicyclic polyoxadiamine in a suitable solvent, and recovered by precipitation. The salts have a gold-color crystalline appearance and are stable in a vacuum at -10.degree. C. and below.

Electrochemical cell utilizing molten alkali metal electrode-reactant

DOEpatents

Virkar, Anil V.; Miller, Gerald R.

1983-11-04

An improved electrochemical cell comprising an additive-modified molten alkali metal electrode-reactant and/or electrolyte is disclosed. Various electrochemical cells employing a molten alkali metal, e.g., sodium, electrode in contact with a cationically conductive ceramic membrane experience a lower resistance and a lower temperature coefficient of resistance whenever small amounts of selenium are present at the interface of the electrolyte and the molten alkali metal. Further, cells having small amounts of selenium present at the electrolyte-molten metal interface exhibit less degradation of the electrolyte under long term cycling conditions.

Process for the disposal of alkali metals

DOEpatents

Lewis, Leroy 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.

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

NASA Astrophysics Data System (ADS)

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.

Coherent control of alkali cluster fragmentation dynamics

NASA Astrophysics Data System (ADS)

Lindinger, Albrecht; Lupulescu, Cosmin; Bartelt, Andreas; Vajda, Štefan; Wöste, Ludger

2003-06-01

Metal clusters exhibit extraordinary chemical and catalytic properties, which sensitively depend upon their size. This behavior makes them interesting candidates for the real-time analysis of ultrafast photo-induced processes—ultimately leading to coherent control scenarii. We have performed transient multi-photon ionization experiments on small alkali clusters of different size in order to probe their wave packet dynamics, structural reorientations, charge transfers and dissociative events in different vibrationally excited electronic states including their ground state. The observed processes were highly dependent on the irradiated pulse parameters, like its phase, amplitude and duration; an emphasis to employ a feedback control system for generating the optimum pulse shapes. Their spectral and temporal behavior reflects interesting properties about the investigated system and the irradiated photochemical process. We present first the vibrational dynamics of bound, dissociated, and pre-dissociated electronically excited states of alkali dimers and trimers. The scheme for observing the wave packet dynamics in the electronic ground state using stimulated Raman-pumping is shown. Since the employed pulse parameters significantly influence the efficiency of the irradiated dynamic pathways photo-induced fragmentation experiments on bifurcating reaction channels were carried out. In these experiments different branching ionization and fragmentation pathways of electronically excited Na 2K were investigated. By employing an evolutionary algorithm for optimizing the phase and amplitude of the applied laser field, the yield of the resulting parent or fragment ions could significantly be influenced and interesting features could be concluded from the obtained optimum pulse shapes revealing the characteristic molecular oscillation period. Moreover, the influence on the optimal pulse shape due to fragmentation from larger clusters into NaK is obtained. The substructure of

Alkali metal intercalates of molybdenum disulfide.

NASA Technical Reports Server (NTRS)

Somoano, R. B.; Hadek, V.; Rembaum, A.

1973-01-01

Study of some of the physicochemical properties of compounds obtained by subjecting natural molybdenite and single crystals of molybdenum disulfide grown by chemical vapor transport to intercalation with the alkali group of metals (Li, Na, K, Rb, and Cs) by means of the liquid ammonia technique. Reported data and results include: (1) the intercalation of the entire alkali metal group, (2) stoichiometries and X-ray data on all of the compounds, and (3) superconductivity data for all the intercalation compounds.

Alkali Metal/Salt Thermal-Energy-Storage Systems

NASA Technical Reports Server (NTRS)

Phillips, Wayne W.; Stearns, John W.

1987-01-01

Proposed thermal-energy-storage system based on mixture of alkali metal and one of its halide salts; metal and salt form slurry of two immiscible melts. Use of slurry expected to prevent incrustations of solidified salts on heat-transfer surfaces that occur where salts alone used. Since incrustations impede heat transfer, system performance improved. In system, charging heat-exchanger surface immersed in lower liquid, rich in halide-salt, phase-charge material. Discharging heat exchanger surface immersed in upper liquid, rich in alkali metal.

COMPLEX FLUORIDES OF PLUTONIUM AND AN ALKALI METAL

DOEpatents

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.

Spectroscopic studies of transition-metal ions in molten alkali-metal carboxylates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maroni, V.A.; Maciejewski, M.L.

This paper presents the results of electronic absorption and /sup 13/C-NMR measurements on molten alkali metal formates and acetates and on solutions of selected 3d transition metal ions therein. These studies provide a unique opportunity to explore (1) the highly ordered nature of alkali carboxylates, (2) the ligand field properties of acetate and formate ions, and (3) the coordination chemistry of the 3d transition metals in molten carboxylates. 1 figure, 2 tables.

Major signal suppression from metal ion clusters in SFC/ESI-MS - Cause and effects.

PubMed

Haglind, Alfred; Hedeland, Mikael; Arvidsson, Torbjörn; Pettersson, Curt E

2018-05-01

The widening application area of SFC-MS with polar analytes and water-containing samples facilitates the use of quick and simple sample preparation techniques such as "dilute and shoot" and protein precipitation. This has also introduced new polar interfering components such as alkali metal ions naturally abundant in e.g. blood plasma and urine, which have shown to be retained using screening conditions in SFC/ESI-TOF-MS and causing areas of major ion suppression. Analytes co-eluting with these clusters will have a decreased signal intensity, which might have a major effect on both quantification and identification. When investigating the composition of the alkali metal clusters using accurate mass and isotopic pattern, it could be concluded that they were previously not described in the literature. Using NaCl and KCl standards and different chromatographic conditions, varying e.g. column and modifier, the clusters proved to be formed from the alkali metal ions in combination with the alcohol modifier and make-up solvent. Their compositions were [(XOCH 3 ) n  + X] + , [(XOH) n  + X] + , [(X 2 CO 3 ) n  + X] + and [(XOOCOCH 3 ) n  + X] + for X = Na + or K + in ESI+. In ESI-, the clusters depended more on modifier, with [(XCl) n  + Cl] - and [(XOCH 3 ) n  + OCH 3 ] - mainly formed in pure methanol and [(XOOCH) n  + OOCH] - when 20 mM NH 4 Fa was added. To prevent the formation of the clusters by avoiding methanol as modifier might be difficult, as this is a widely used modifier providing good solubility when analyzing polar compounds in SFC. A sample preparation with e.g. LLE would remove the alkali ions, however also introducing a time consuming and discriminating step into the method. Since the alkali metal ions were retained and affected by chromatographic adjustments as e.g. mobile phase modifications, a way to avoid them could therefore be chromatographic tuning, when analyzing samples containing them. Copyright © 2018 Elsevier

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

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 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...

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

Code of Federal Regulations, 2010 CFR

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...

40 CFR 721.4660 - Alcohol, alkali metal salt.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alcohol, alkali metal salt. 721.4660 Section 721.4660 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4660 Alcohol, alkali metal sal...

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

Code of Federal Regulations, 2010 CFR

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...

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

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 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...

40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

Code of Federal Regulations, 2011 CFR

2011-07-01

... metal salts. 721.4663 Section 721.4663 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... 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...

Adsorption of alkali and alkaline earth metal atoms and dimers on monolayer germanium carbide

NASA Astrophysics Data System (ADS)

Gökçe, Aytaç Gürhan; Ersan, Fatih

2017-01-01

First-principles plane wave calculations have been performed to study the adsorption of alkali and alkaline earth metals on monolayer germanium carbide (GeC). We found that the favourable adsorption sites on GeC sheet for single alkali and alkaline earth adatoms are generally different from graphene or germanene. Among them, Mg, Na and their dimers have weakly bounded to GeC due to their closed valence electron shells, so they may have high mobility on GeC. Two different levels of adatom coverage (? and ?) have been investigated and we concluded that different electronic structures and magnetic moments for both coverages owing to alkali and alkaline earth atoms have long range electrostatic interactions. Lithium atom prefers to adsorbed on hollow site similar to other group-IV monolayers and the adsorption results in metallisation of GeC instead of semiconducting behaviour. Na and K adsorption can induce 1 ? total magnetic moment on GeC structures and they have shown semiconductor property which may have potential use in spintronic devices. We also showed that alkali or alkaline earth metal atoms can form dimer on GeC sheet. Calculated adsorption energies suggest that clustering of alkali and alkaline earth atoms is energetically favourable. All dimer adsorbed GeC systems have nonmagnetic semiconductor property with varying band gaps from 0.391 to 1.311 eV which are very suitable values for various device applications.

Electrochemical cell having an alkali-metal-nitrate electrode

DOEpatents

Roche, M.F.; Preto, S.K.

1982-06-04

A power-producing secondary electrochemical cell includes a molten alkali metal as the negative-electrode material and a molten-nitrate salt as the positive-electrode material. The molten material in the respective electrodes are separated by a solid barrier of alkali-metal-ion conducting material. A typical cell includes active materials of molten sodium separated from molten sodium nitrate and other nitrates in mixture by a layer of sodium ..beta..'' alumina.

Alkali metal vapors - Laser spectroscopy and applications

NASA Technical Reports Server (NTRS)

Stwalley, W. C.; Koch, M. E.

1980-01-01

The paper examines the rapidly expanding use of lasers for spectroscopic studies of alkali metal vapors. Since the alkali metals (lithium, sodium, potassium, rubidium and cesium) are theoretically simple ('visible hydrogen'), readily ionized, and strongly interacting with laser light, they represent ideal systems for quantitative understanding of microscopic interconversion mechanisms between photon (e.g., solar or laser), chemical, electrical and thermal energy. The possible implications of such understanding for a wide variety of practical applications (sodium lamps, thermionic converters, magnetohydrodynamic devices, new lasers, 'lithium waterfall' inertial confinement fusion reactors, etc.) are also discussed.

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

Code of Federal Regulations, 2010 CFR

2010-07-01

..., alkali metal salt (generic). 721.10097 Section 721.10097 Protection of Environment ENVIRONMENTAL... metal salt (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as disubstituted benzenesulfonic acid, alkali metal salt (PMN P...

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

Code of Federal Regulations, 2011 CFR

2011-07-01

..., alkali metal salt (generic). 721.10097 Section 721.10097 Protection of Environment ENVIRONMENTAL... metal salt (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as disubstituted benzenesulfonic acid, alkali metal salt (PMN P...

Neuropsychiatric manifestations of alkali metal deficiency and excess

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 investigatedmore » 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.« less

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

Code of Federal Regulations, 2010 CFR

2010-07-01

... metal salt (generic). 721.10098 Section 721.10098 Protection of Environment ENVIRONMENTAL PROTECTION... 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...

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

Code of Federal Regulations, 2011 CFR

2011-07-01

... metal salt (generic). 721.10098 Section 721.10098 Protection of Environment ENVIRONMENTAL PROTECTION... 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...

Effects of pH on frog gustatory responses to chloride salts of alkali-metal and alkali-earth-metal.

PubMed

Kumai, T; Nomura, H

1980-01-01

The pH effects on frog gustatory responses to alkali-metal and alkali-earth-metal chloride salts were examined using single fungi-form papilla preparations. Responses to 0.1-0.5 M NaCl were clearly dependent upon the pH of the stimulating solutions. The responses increased as the pH decreased from 6.5 to 4.5 and were almost completely suppressed at pH's above 6.5. There was no significant difference in the pH dependency of the response among alkali-metal chlorides. HCl solutions elicited only a poor response under conditions in which the water response was suppressed by the simultaneous presence of a low NaCl concentration. Responses to alkali-earth-metal chlorides varied in their pH dependency. Response to CaCl2 was slightly affected by pH changes from 4.5 to 9.0, response to SrCl2 was considerably suppressed in the alkaline region, and responses to BaCl2 and MgCl2 were strongly suppressed at pH's above 6.5. BeCl2 solutions showed less marked stimulating effects over the pH range tested. The differences in pH dependency described above suggest the existence of two kinds of receptor sites, one being pH-insensitive sites responsible for the calcium response and the other pH-sensitive sites responsible for the sodium response. A cross-adaptation test appeared to support this possibility. Assuming that the pH effect mentioned is related to changes in the state of ionization of the receptor molecule, the pKa of the ionizable group responsible for the sodium response was determined to be approximately 5.5.

Method of assembling and sealing an alkali metal battery

DOEpatents

Elkins, Perry E.; Bell, Jerry E.; Harlow, Richard A.; Chase, Gordon G.

1983-01-01

A method of initially assembling and then subsequently hermetically sealing a container portion of an alkali metal battery to a ceramic portion of such a battery is disclosed. Sealing surfaces are formed respectively on a container portion and a ceramic portion of an alkali metal battery. These sealing surfaces are brought into juxtaposition and a material is interposed therebetween. This interposed material is one which will diffuse into sealing relationship with both the container portion and the ceramic portion of the alkali metal battery at operational temperatures of such a battery. A pressure is applied between these sealing surfaces to cause the interposed material to be brought into intimate physical contact with such juxtaposed surfaces. A temporary sealing material which will provide a seal against a flow of alkali metal battery reactants therethrough at room temperatures and is applied over the juxtaposed sealing surfaces and material interposed therebetween. The entire assembly is heated to an operational temperature so that the interposed material diffuses into the container portion and the ceramic portion to form a hermetic seal therebetween. The pressure applied to the juxtaposed sealing surfaces is maintained in order to ensure the continuation of the hermetic seal.

Solvent- and catalyst-free mechanochemical synthesis of alkali metal monohydrides

DOE PAGES

Hlova, Ihor Z.; Castle, Andra; Goldston, Jennifer F.; ...

2016-07-06

Alkali metal monohydrides, AH (A = Li–Cs) have been synthesized in quantitative yields at room temperature by reactive milling of alkali metals in the presence of hydrogen gas at 200 bar or less. The mechanochemical approach reported here eliminates problems associated with the malleability of alkali metals — especially Li, Na, and K — and promotes effective solid–gas reactions, ensuring their completion. This is achieved by incorporating a certain volume fraction of the corresponding hydride powder as a process control agent, which allows continuous and efficient milling primarily by coating the surface of metal particles, effectively blocking cold welding. Formationmore » of high-purity crystalline monohydrides has been confirmed by powder X-ray diffraction, solid-state NMR spectroscopy, and volumetric analyses of reactively desorbed H 2 from as-milled samples. The proposed synthesis method is scalable and particularly effective for extremely air-sensitive materials, such as alkali and alkaline earth metal hydrides. Furthermore, the technique may also be favorable for production in continuous reactors operating at room temperature, thereby reducing the total processing time, energy consumption and, hence, the cost of production of these hydrides or their derivatives and composites.« less

Vacancy defects and defect clusters in alkali metal ion-doped MgO nanocrystallites studied by positron annihilation and photoluminescence spectroscopy

NASA Astrophysics Data System (ADS)

Sellaiyan, S.; Uedono, A.; Sivaji, K.; Janet Priscilla, S.; Sivasankari, J.; Selvalakshmi, T.

2016-10-01

Pure and alkali metal ion (Li, Na, and K)-doped MgO nanocrystallites synthesized by solution combustion technique have been studied by positron lifetime and Doppler broadening spectroscopy methods. Positron lifetime analysis exhibits four characteristic lifetime components for all the samples. Doping reduces the Mg vacancy after annealing to 800 °C. It was observed that Li ion migrates to the vacancy site to recover Mg vacancy-type defects, reducing cluster vacancies and micropores. For Na- and K-doped MgO, the aforementioned defects are reduced and immobile at 800 °C. Coincidence Doppler broadening studies show the positron trapping sites as vacancy clusters. The decrease in the S parameter is due to the particle growth and reduction in the defect concentration at 800 °C. Photoluminescence study shows an emission peak at 445 nm and 498 nm, associated with F2 2+ and recombination of higher-order vacancy complexes. Further, annealing process is likely to dissociate F2 2+ to F+ and this F+ is converted into F centers at 416 nm.

Method of assembling and sealing an alkali metal battery

DOEpatents

Elkins, P.E.; Bell, J.E.; Harlow, R.A.; Chase, G.G.

1983-03-01

A method of initially assembling and then subsequently hermetically sealing a container portion of an alkali metal battery to a ceramic portion of such a battery is disclosed. Sealing surfaces are formed respectively on a container portion and a ceramic portion of an alkali metal battery. These sealing surfaces are brought into juxtaposition and a material is interposed there between. This interposed material is one which will diffuse into sealing relationship with both the container portion and the ceramic portion of the alkali metal battery at operational temperatures of such a battery. A pressure is applied between these sealing surfaces to cause the interposed material to be brought into intimate physical contact with such juxtaposed surfaces. A temporary sealing material which will provide a seal against a flow of alkali metal battery reactants there through at room temperatures and is applied over the juxtaposed sealing surfaces and material interposed there between. The entire assembly is heated to an operational temperature so that the interposed material diffuses into the container portion and the ceramic portion to form a hermetic seal there between. The pressure applied to the juxtaposed sealing surfaces is maintained in order to ensure the continuation of the hermetic seal. 4 figs.

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

DOEpatents

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.

The interactions of sorbates with gallosilicates and alkali-metal exchanged gallosilicates

NASA Astrophysics Data System (ADS)

Limtrakul, J.; Kuno, M.; Treesukol, P.

1999-11-01

Structures, energetics and vibrational frequencies of the interaction of adsorbates with H-aluminosilicates (H-AlZ), H-gallosilicates (H-GaZ), alkali-metal exchanged aluminosilicates (X-AlZ) and alkali-metal exchanged gallosilicates (X-GaZ), where X being Li, Na, or K, have been carried out at B3LYP and HF levels of theory with 6-31G(d) as the basis set. The charge compensating alkali-metal ions can affect the catalytically active site (Si-O-T where T=Al or Ga) by weakening the Si-O, Al-O, and Ga-O bonds as compared to their anionic frameworks. Comparing the net stabilization energies, Δ ENSE, of the naked alkali-metal/H 2O adducts with those of the alkali-metal exchanged zeolite/H 2O systems, the latter amounts only to about 50% of the former, which is partly due to the destabilizing role of the negative zeolitic oxygen frameworks surrounding the cations. The interaction of sorbates with the alkali-metal exchanged gallosilicates can be employed to probe the field strength inside the catalytic frameworks as indicated by the plot of the binding energy, Δ E, versus 1/ RX-O w2, with R(X-O w) being the distance between the cationic nucleus and the oxygen atom of the adsorbate. The IR spectra of H 2O adsorbed on Na-AlZ are calculated to be 3584, 3651, and 1686 cm -1. The obtained results are in excellent agreement with the very recent experimental IR spectra of water adsorbed on Na-ZSM-5 of Zecchina et al. (J. Phys. Chem., 100 (1996) 16 484). Other important features, i.e. the correlation between Δ νOH and, Δ E, R(X-O w) , and 1/ RX-O w2, cationic size, demonstrate that the interactions of sorbates with alkali-metal exchanged gallosilicates are well approximated by electrostatic contribution.

Role of crystal field in mixed alkali metal effect: electron paramagnetic resonance study of mixed alkali metal oxyfluoro vanadate glasses.

PubMed

Honnavar, Gajanan V; Ramesh, K P; Bhat, S V

2014-01-23

The mixed alkali metal effect is a long-standing problem in glasses. Electron paramagnetic resonance (EPR) is used by several researchers to study the mixed alkali metal effect, but a detailed analysis of the nearest neighbor environment of the glass former using spin-Hamiltonian parameters was elusive. In this study we have prepared a series of vanadate glasses having general formula (mol %) 40 V2O5-30BaF2-(30 - x)LiF-xRbF with x = 5, 10, 15, 20, 25, and 30. Spin-Hamiltonian parameters of V(4+) ions were extracted by simulating and fitting to the experimental spectra using EasySpin. From the analysis of these parameters it is observed that the replacement of lithium ions by rubidium ions follows a "preferential substitution model". Using this proposed model, we were able to account for the observed variation in the ratio of the g parameter, which goes through a maximum. This reflects an asymmetric to symmetric changeover of the alkali metal ion environment around the vanadium site. Further, this model also accounts for the variation in oxidation state of vanadium ion, which was confirmed from the variation in signal intensity of EPR spectra.

DFT study of the interaction between DOTA chelator and competitive alkali metal ions.

PubMed

Frimpong, E; Skelton, A A; Honarparvar, B

2017-09-01

1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetracetic acid (DOTA) is an important chelator for radiolabeling of pharmaceuticals. The ability of alkali metals found in the body to complex with DOTA and compete with radio metal ions can alter the radiolabeling process. Non-covalent interactions between DOTA complexed with alkali metals Li + , Na + , K + and Rb + , are investigated with density functional theory using B3LYP and ωB97XD functionals. Conformational possibilities of DOTA were explored with a varying number of carboxylic pendant arms of DOTA in close proximity to the ions. It is found that the case in which four arms of DOTA are interacting with ions is more stable than other conformations. The objective of this study is to explore the electronic structure properties upon complexation of alkali metals Li + Na + , K + and Rb + with a DOTA chelator. Interaction energies, relaxation energies, entropies, Gibbs free energies and enthalpies show that the stability of DOTA, complexed with alkali metals decreases down the group of the periodic table. Implicit water solvation affects the complexation of DOTA-ions leading to decreases in the stability of the complexes. NBO analysis through the natural population charges and the second order perturbation theory, revealed a charge transfer between DOTA and alkali metals. Conceptual DFT-based properties such as HOMO/LUMO energies, ΔE HOMO-LUMO and chemical hardness and softness indicated a decrease in the chemical stability of DOTA-alkali metal complexes down the alkali metal series. This study serves as a guide to researchers in the field of organometallic chelators, particularly, radiopharmaceuticals in finding the efficient optimal match between chelators and various metal ions. Copyright © 2017 Elsevier Inc. All rights reserved.

Is Electronegativity a Useful Descriptor for the "Pseudo-Alkali-Metal" NH4?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whiteside, Alexander; Xantheas, Sotiris S.; Gutowski, Maciej S.

2011-11-18

Molecular ions in the form of "pseudo-atoms" are common structural motifs in chemistry, with properties that are transferrable between different compounds. We have determined the electronegativity of the "pseudo-alkali metal" ammonium (NH4) and evaluated its reliability as a descriptor in comparison to the electronegativities of the alkali metals. The computed properties of its binary complexes with astatine and of selected borohydrides confirm the similarity of NH4 to the alkali metal atoms, although the electronegativity of NH4 is relatively large in comparison to its cationic radius. We paid particular attention to the molecular properties of ammonium (angular anisotropy, geometric relaxation, andmore » reactivity), which can cause deviations from the behaviour expected of a conceptual "true alkali metal" with this electronegativity. These deviations allow for the discrimination of effects associated with the polyatomic nature of NH4.« less

Alkali metal/sulfur battery

DOEpatents

Anand, Joginder N.

1978-01-01

Alkali metal/sulfur batteries in which the electrolyte-separator is a relatively fragile membrane are improved by providing means for separating the molten sulfur/sulfide catholyte from contact with the membrane prior to cooling the cell to temperatures at which the catholyte will solidify. If the catholyte is permitted to solidify while in contact with the membrane, the latter may be damaged. The improvement permits such batteries to be prefilled with catholyte and shipped, at ordinary temperatures.

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

NASA Astrophysics Data System (ADS)

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.

Alkali metal yttrium neo-pentoxide double alkoxide precursors to alkali metal yttrium oxide nanomaterials

DOE PAGES

Boyle, Timothy J.; Neville, Michael L.; Sears, Jeremiah Matthew; ...

2016-03-15

In this study, a series of alkali metal yttrium neo-pentoxide ([AY(ONep) 4]) compounds were developed as precursors to alkali yttrium oxide (AYO 2) nanomaterials. The reaction of yttrium amide ([Y(NR 2) 3] where R=Si(CH 3) 3) with four equivalents of H-ONep followed by addition of [A(NR 2)] (A=Li, Na, K) or A o (A o=Rb, Cs) led to the formation of a complex series of A nY(ONep) 3+n species, crystallographically identified as [Y 2Li 3(μ 3-ONep)(μ 3-HONep)(μ-ONep) 5(ONep) 3(HONep) 2] (1), [YNa 2(μ 3-ONep) 4(ONep)] 2 (2), {[Y 2K 3(μ 3-ONep) 3(μ-ONep) 4(ONep) 2(ηξ-tol) 2][Y 4K 2(μ 4-O)(μ 3-ONep) 8(ONep)more » 4]•η x-tol]} (3), [Y 4K 2(μ 4-O)(μ 3-ONep) 8(ONep) 4] (3a), [Y 2Rb 3(μ 4-ONep) 3(μ-ONep) 6] (4), and [Y 2Cs 4(μ 6-O)(μ 3-ONep) 6(μ 3-HONep) 2(ONep) 2(η x-tol) 4]•tol (5). Compounds 1–5 were investigated as single source precursors to AYOx nanomaterials following solvothermal routes (pyridine, 185 °C for 24h). The final products after thermal processing were found by powder X-ray diffraction experiments to be Y 2O 3 with variable sized particles based on transmission electron diffraction. Energy dispersive X-ray spectroscopy studies indicated that the heavier alkali metal species were present in the isolated nanomaterials.« less

Upgrading of petroleum oil feedstocks using alkali metals and hydrocarbons

DOEpatents

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.

Highly reproducible alkali metal doping system for organic crystals through enhanced diffusion of alkali metal by secondary thermal activation.

PubMed

Lee, Jinho; Park, Chibeom; Song, Intek; Koo, Jin Young; Yoon, Taekyung; Kim, Jun Sung; Choi, Hee Cheul

2018-05-16

In this paper, we report an efficient alkali metal doping system for organic single crystals. Our system employs an enhanced diffusion method for the introduction of alkali metal into organic single crystals by controlling the sample temperature to induce secondary thermal activation. Using this system, we achieved intercalation of potassium into picene single crystals with closed packed crystal structures. Using optical microscopy and Raman spectroscopy, we confirmed that the resulting samples were uniformly doped and became K 2 picene single crystal, while only parts of the crystal are doped and transformed into K 2 picene without secondary thermal activation. Moreover, using a customized electrical measurement system, the insulator-to-semiconductor transition of picene single crystals upon doping was confirmed by in situ electrical conductivity and ex situ temperature-dependent resistivity measurements. X-ray diffraction studies showed that potassium atoms were intercalated between molecular layers of picene, and doped samples did not show any KH- nor KOH-related peaks, indicating that picene molecules are retained without structural decomposition. During recent decades, tremendous efforts have been exerted to develop high-performance organic semiconductors and superconductors, whereas as little attention has been devoted to doped organic crystals. Our method will enable efficient alkali metal doping of organic crystals and will be a resource for future systematic studies on the electrical property changes of these organic crystals upon doping.

Process for carbonaceous material conversion and recovery of alkali metal catalyst constituents held by ion exchange sites in conversion residue

DOEpatents

Sharp, David W.

1980-01-01

In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered for the particles by contacting or washing them with an aqueous solution containing calcium or magnesium ions in an alkali metal recovery zone at a low temperature, preferably below about 249.degree. F. During the washing or leaching process, the calcium or magnesium ions displace alkali metal ions held by ion exchange sites in the particles thereby liberating the ions and producing an aqueous effluent containing alkali metal constituents. The aqueous effluent from the alkali metal recovery zone is then recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

Is electronegativity a useful descriptor for the pseudo-alkali metal NH4?

PubMed

Whiteside, Alexander; Xantheas, Sotiris S; Gutowski, Maciej

2011-11-18

Molecular ions in the form of "pseudo-atoms" are common structural motifs in chemistry, with properties that are transferrable between different compounds. We have determined one such property--the electronegativity--for the "pseudo-alkali metal" ammonium (NH(4)), and evaluated its reliability as a descriptor versus the electronegativities of the alkali metals. The computed properties of ammonium's binary complexes with astatine and of selected borohydrides confirm the similarity of NH(4) to the alkali metal atoms, although the electronegativity of NH(4) is relatively large in comparison to its cationic radius. We have paid particular attention to the molecular properties of ammonium (angular anisotropy, geometric relaxation and reactivity), which can cause deviations from the behaviour expected of a conceptual "true alkali metal" with this electronegativity. These deviations allow for the discrimination of effects associated with the molecular nature of NH(4). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Observation of Raman self-focusing in an alkali-metal vapor cell

NASA Astrophysics Data System (ADS)

Proite, N. A.; Unks, B. E.; Green, J. T.; Yavuz, D. D.

2008-02-01

We report an experimental demonstration of Raman self-focusing and self-defocusing in a far-off resonant alkali-metal atomic system. The key idea is to drive a hyperfine transition in an alkali-metal atom to a maximally coherent state with two laser beams. In this regime, the two-photon detuning from the Raman resonance controls the nonlinear index of the medium.

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

DOEpatents

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.

Compression-Driven Enhancement of Electronic Correlations in Simple Alkali Metals

NASA Astrophysics Data System (ADS)

Fabbris, Gilberto; Lim, Jinhyuk; Veiga, Larissa; Haskel, Daniel; Schilling, James

2015-03-01

Alkali metals are the best realization of the nearly free electron model. This scenario appears to change dramatically as the alkalis are subjected to extreme pressure, leading to unexpected properties such as the departure from metallic behavior in Li and Na, and the occurrence of remarkable low-symmetry crystal structures in all alkalis. Although the mechanism behind these phase transitions is currently under debate, these are believed to be electronically driven. In this study the high-pressure electronic and structural ground state of Rb and Cs was investigated through low temperature XANES and XRD measurements combined with ab initio calculations. The results indicate that the pressure-induced localization of the conduction band triggers a Peierls-like mechanism, inducing the low symmetry phases. This localization process is evident by the pressure-driven increase in the number of d electrons, which takes place through strong spd hybridization. These experimental results indicate that compression turns the heavy alkali metals into strongly correlated electron systems. Work at Argonne was supported by DOE No. DE-AC02-06CH11357. Research at Washington University was supported by NSF DMR-1104742 and CDAC/DOE/NNSA DE-FC52-08NA28554.

Advances in high temperature components for AMTEC (alkali metal thermal-to-electric converter)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, R.M.; Jeffries-Nakamura, B.; Underwood, M.L.

1991-12-31

Long lifetimes are required for AMTEC (or sodium heat engine) components for aerospace and terrestrial applications, and the high heat input temperature as well as the alkali metal liquid and vapor environment places unusual demands on the materials used to construct AMTEC devices. In addition, it is important to maximize device efficiency and power density, while maintaining a long life capability. In addition to the electrode, which must provide both efficient electrode kinetics, transport of the alkali metal, and low electrical resistance, other high temperature components of the cell face equally demanding requirements. The beta{double_prime} alumina solid electrolyte (BASE), themore » seal between the BASE ceramic and its metallic transition to the hot alkali metal (liquid or vapor) source, and metallic components of the device are exposed to hot liquid alkali metal. Modification of AMTEC components may also be useful in optimizing the device for particular operating conditions. In particular, a potassium AMTEC may be expected to operate more efficiently at lower temperatures.« less

Advances in high temperature components for AMTEC (alkali metal thermal-to-electric converter)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, R.M.; Jeffries-Nakamura, B.; Underwood, M.L.

1991-01-01

Long lifetimes are required for AMTEC (or sodium heat engine) components for aerospace and terrestrial applications, and the high heat input temperature as well as the alkali metal liquid and vapor environment places unusual demands on the materials used to construct AMTEC devices. In addition, it is important to maximize device efficiency and power density, while maintaining a long life capability. In addition to the electrode, which must provide both efficient electrode kinetics, transport of the alkali metal, and low electrical resistance, other high temperature components of the cell face equally demanding requirements. The beta{double prime} alumina solid electrolyte (BASE),more » the seal between the BASE ceramic and its metallic transition to the hot alkali metal (liquid or vapor) source, and metallic components of the device are exposed to hot liquid alkali metal. Modification of AMTEC components may also be useful in optimizing the device for particular operating conditions. In particular, a potassium AMTEC may be expected to operate more efficiently at lower temperatures.« less

Secondary cell with orthorhombic alkali metal/manganese oxide phase active cathode material

DOEpatents

Doeff, Marca M.; Peng, Marcus Y.; Ma, Yanping; Visco, Steven J.; DeJonghe, Lutgard C.

1996-01-01

An alkali metal manganese oxide secondary cell is disclosed which can provide a high rate of discharge, good cycling capabilities, good stability of the cathode material, high specific energy (energy per unit of weight) and high energy density (energy per unit volume). The active material in the anode is an alkali metal and the active material in the cathode comprises an orthorhombic alkali metal manganese oxide which undergoes intercalation and deintercalation without a change in phase, resulting in a substantially linear change in voltage with change in the state of charge of the cell. The active material in the cathode is an orthorhombic structure having the formula M.sub.x Z.sub.y Mn.sub.(1-y) O.sub.2, where M is an alkali metal; Z is a metal capable of substituting for manganese in the orthorhombic structure such as iron, cobalt or titanium; x ranges from about 0.2 in the fully charged state to about 0.75 in the fully discharged state, and y ranges from 0 to 60 atomic %. Preferably, the cell is constructed with a solid electrolyte, but a liquid or gelatinous electrolyte may also be used in the cell.

Secondary cell with orthorhombic alkali metal/manganese oxide phase active cathode material

DOEpatents

Doeff, M.M.; Peng, M.Y.; Ma, Y.; Visco, S.J.; DeJonghe, L.C.

1996-09-24

An alkali metal manganese oxide secondary cell is disclosed which can provide a high rate of discharge, good cycling capabilities, good stability of the cathode material, high specific energy (energy per unit of weight) and high energy density (energy per unit volume). The active material in the anode is an alkali metal and the active material in the cathode comprises an orthorhombic alkali metal manganese oxide which undergoes intercalation and deintercalation without a change in phase, resulting in a substantially linear change in voltage with change in the state of charge of the cell. The active material in the cathode is an orthorhombic structure having the formula M{sub x}Z{sub y}Mn{sub (1{minus}y)}O{sub 2}, where M is an alkali metal; Z is a metal capable of substituting for manganese in the orthorhombic structure such as iron, cobalt or titanium; x ranges from about 0.2 in the fully charged state to about 0.75 in the fully discharged state, and y ranges from 0 to 60 atomic %. Preferably, the cell is constructed with a solid electrolyte, but a liquid or gelatinous electrolyte may also be used in the cell. 11 figs.

Alkali metal-refractory metal biphase electrode for AMTEC

NASA Technical Reports Server (NTRS)

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.

Hall Determination of Atomic Radii of Alkali Metals

ERIC Educational Resources Information Center

Houari, Ahmed

2008-01-01

I will propose here an alternative method for determining atomic radii of alkali metals based on the Hall measurements of their free electron densities and the knowledge of their crystal structure. (Contains 2 figures.)

Process for preparing higher oxides of the alkali and alkaline earth metals

NASA Technical Reports Server (NTRS)

Sadhukhan, P.; Bell, A. (Inventor)

1978-01-01

High purity inorganic higher oxides of the alkali and alkaline earth metals are prepared by subjecting the hydroxide of the alkali and alkaline earth metal to a radio frequency discharge sustained in oxygen. The process is particulary adaptable to the production of high purity potassium superoxide by subjecting potassium hydroxide to glow discharge sustained in oxygen under the pressure of about 0.75 to 1.00 torr.

Stabilized Alkali-Metal Ultraviolet-Band-Pass Filters

NASA Technical Reports Server (NTRS)

Mardesich, Nick; Fraschetti, George A.; Mccann, Timothy; Mayall, Sherwood D.; Dunn, Donald E.; Trauger, John T.

1995-01-01

Layers of bismuth 5 to 10 angstrom thick incorporated into alkali-metal ultraviolet-band-pass optical filters by use of advanced fabrication techniques. In new filters layer of bismuth helps to reduce surface migration of sodium. Sodium layer made more stable and decreased tendency to form pinholes by migration.

Method for inhibiting alkali metal corrosion of nickel-containing alloys

DOEpatents

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.

Alkali Metal Heat Pipe Life Issues

NASA Technical Reports Server (NTRS)

Reid, Robert S.

2004-01-01

One approach to space fission power system design is predicated on the use of alkali metal heat pipes, either as radiator elements, thermal management components, or as part of the core primary heat-transfer system. This synopsis characterizes long-life core heat pipes. References are included where more detailed information can be found. Specifics shown here are for demonstrational purposes and do not necessarily reflect current Project Prometheus point designs.

Method for intercalating alkali metal ions into carbon electrodes

DOEpatents

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.

Method for intercalating alkali metal ions into carbon electrodes

DOEpatents

Doeff, M.M.; Ma, Y.; Visco, S.J.; DeJonghe, L.

1995-08-22

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.

A simple model for metal cation-phosphate interactions in nucleic acids in the gas phase: alkali metal cations and trimethyl phosphate.

PubMed

Ruan, Chunhai; Huang, Hai; Rodgers, M T

2008-02-01

Threshold collision-induced dissociation techniques are employed to determine the bond dissociation energies (BDEs) of complexes of alkali metal cations to trimethyl phosphate, TMP. Endothermic loss of the intact TMP ligand is the only dissociation pathway observed for all complexes. Theoretical calculations at the B3LYP/6-31G* level of theory are used to determine the structures, vibrational frequencies, and rotational constants of neutral TMP and the M+(TMP) complexes. Theoretical BDEs are determined from single point energy calculations at the B3LYP/6-311+G(2d,2p) level using the B3LYP/6-31G* optimized geometries. The agreement between theory and experiment is reasonably good for all complexes except Li+(TMP). The absolute M+-(TMP) BDEs are found to decrease monotonically as the size of the alkali metal cation increases. No activated dissociation was observed for alkali metal cation binding to TMP. The binding of alkali metal cations to TMP is compared with that to acetone and methanol.

Ion conducting polymers and polymer blends for alkali metal ion batteries

DOEpatents

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.

New gas phase inorganic ion cluster species and their atmospheric implications

NASA Technical Reports Server (NTRS)

Maerk, T. D.; Peterson, K. I.; Castleman, A. W., Jr.

1980-01-01

Recent experimental laboratory observations, with high-pressure mass spectroscopy, have revealed the existence of previously unreported species involving water clustered to sodium dimer ions, and alkali metal hydroxides clustered to alkali metal ions. The important implications of these results concerning the existence of such species are here discussed, as well as how from a practical aspect they confirm the stability of certain cluster species proposed by Ferguson (1978) to explain masses recently detected at upper altitudes using mass spectrometric techniques.

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

DOEpatents

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.

Photodissociation Studies of Metal-Containing Clusters and Complexes

NASA Astrophysics Data System (ADS)

Pilgrim, Jeffrey Scott

1995-01-01

There have been two major areas of investigation for researchers working with laser ablation in molecular beams. The first area is the study of weakly-bound complexes. These complexes are bound by electrostatic interactions. In the present study the weakly bound interactions of the rare gases with the magnesium ion are investigated with electronic spectroscopy. The second major area is the study of metal and metal-containing clusters. Examples of previous investigations are the alkali metal clusters and the fullerenes. The present investigation is on metal -carbon clusters. The so-called metallo-carbohedrenes and metal-carbon nanocrystals are studied. Resonance enhanced photodissociation spectroscopy is used to obtain electronic excitation spectra of the Mg^+-rare gas species in the ultraviolet region. This investigation is facilitated by a reflectron time-of-flight mass spectrometer. The interaction of the rare gas with the metal ion is attributed to a "solvation" of the atomic ion transition. Simple bonding arguments predict that the excited state is more bound than the ground state for these complexes. This will result in a shift of the complex vibronic origin to lower energy from the atomic ion transition. This is exactly what is observed in the experiment with progressively larger shifts for the heavier rare gases. The electronic excitation spectra allow the vibrational frequencies and anharmonicities for these complexes to be obtained for the excited state. In turn, the excited state bond dissociation energies can be determined. Finally, conservation of energy allows calculation of the ground state bond dissociation energies. In the metal-carbon systems the stability of the metallo-carbohedrene, met-car, stoichiometry is shown to extend into the transition period at least to the iron group. Photodissociation with a 532 nm laser causes a loss of metal atoms for met-cars formed with first row transition metals and a loss of metal-carbon units for met

Device and method for upgrading petroleum feedstocks and petroleum refinery streams using an alkali metal conductive membrane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gordon, John Howard; Alvare, Javier

A reactor has two chambers, namely an oil feedstock chamber and a source chamber. An ion separator separates the oil feedstock chamber from the source chamber, wherein the ion separator allows alkali metal ions to pass from the source chamber, through the ion separator, and into the oil feedstock chamber. A cathode is at least partially housed within the oil feedstock chamber and an anode is at least partially housed within the source chamber. A quantity of an oil feedstock is within the oil feedstock chamber, the oil feedstock comprising at least one carbon atom and a heteroatom and/or onemore » or more heavy metals, the oil feedstock further comprising naphthenic acid. When the alkali metal ion enters the oil feedstock chamber, the alkali metal reacts with the heteroatom, the heavy metals and/or the naphthenic acid, wherein the reaction with the alkali metal forms inorganic products.« less

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

NASA Astrophysics Data System (ADS)

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

Investigation of Anti-Relaxation Coatings for Alkali-Metal Vapor Cells using Surface Science Techniques

DTIC Science & Technology

2011-02-01

worldwide. Lawrence Berkeley National Laboratory Peer Reviewed Title: Investigation of anti-Relaxation coatings for alkali-metal vapor cells using ...2010 Abstract: 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

Alkali metal protective garment and composite material

DOEpatents

Ballif, III, John L.; Yuan, Wei W.

1980-01-01

A protective garment and composite material providing satisfactory heat resistance and physical protection for articles and personnel exposed to hot molten alkali metals, such as sodium. Physical protection is provided by a continuous layer of nickel foil. Heat resistance is provided by an underlying backing layer of thermal insulation. Overlying outer layers of fireproof woven ceramic fibers are used to protect the foil during storage and handling.

Elliptical polarization of near-resonant linearly polarized probe light in optically pumped alkali metal vapor

PubMed Central

Li, Yingying; Wang, Zhiguo; Jin, Shilong; Yuan, Jie; Luo, Hui

2017-01-01

Optically pumped alkali metal atoms currently provide a sensitive solution for magnetic microscopic measurements. As the most practicable plan, Faraday rotation of linearly polarized light is extensively used in spin polarization measurements of alkali metal atoms. In some cases, near-resonant Faraday rotation is applied to improve the sensitivity. However, the near-resonant linearly polarized probe light is elliptically polarized after passing through optically pumped alkali metal vapor. The ellipticity of transmitted near-resonant probe light is numerically calculated and experimentally measured. In addition, we also analyze the negative impact of elliptical polarization on Faraday rotation measurements. From our theoretical estimate and experimental results, the elliptical polarization forms an inevitable error in spin polarization measurements. PMID:28216649

Alkali-metal induced band structure deformation investigated by angle-resolved photoemission spectroscopy and first-principles calculations

NASA Astrophysics Data System (ADS)

Ito, S.; Feng, B.; Arita, M.; Someya, T.; Chen, W.-C.; Takayama, A.; Iimori, T.; Namatame, H.; Taniguchi, M.; Cheng, C.-M.; Tang, S.-J.; Komori, F.; Matsuda, I.

2018-04-01

Alkali-metal adsorption on the surface of materials is widely used for in situ surface electron doping, particularly for observing unoccupied band structures by angle-resolved photoemission spectroscopy (ARPES). However, the effects of alkali-metal atoms on the resulting band structures have yet to be fully investigated, owing to difficulties in both experiments and calculations. Here, we combine ARPES measurements on cesium-adsorbed ultrathin bismuth films with first-principles calculations of the electronic charge densities and demonstrate a simple method to evaluate alkali-metal induced band deformation. We reveal that deformation of bismuth surface bands is directly correlated with vertical charge-density profiles at each electronic state of bismuth. In contrast, a change in the quantized bulk bands is well described by a conventional rigid-band-shift picture. We discuss these two aspects of the band deformation holistically, considering spatial distributions of the electronic states and cesium-bismuth hybridization, and provide a prescription for applying alkali-metal adsorption to a wide range of materials.

First-principles study on interlayer state in alkali and alkaline earth metal atoms intercalated bilayer graphene

NASA Astrophysics Data System (ADS)

Kaneko, Tomoaki; Saito, Riichiro

2017-11-01

Energetics and electronic structures of alkali metal (Li, Na, K, Rb, and Cs) and alkaline earth metal (Be, Mg, Ca, Sr, and Ba) atoms intercalated bilayer graphene are systematically investigated using first-principles calculations based on density functional theory. Formation of alkali and alkaline earth metal atoms intercalated bilayer graphene is exothermic except for Be and Mg. The interlayer state between two graphene layers is occupied for K, Rb, Cs, Ca, Sr, and Ba. We find that the energetic position of the interlayer states between bilayer graphene monotonically shifts downward with increasing of interlayer distance. The interlayer distances of more than 4.5 Å and 4.0 Å, respectively, are necessary for the occupation of the interlayer state in bilayer graphene for alkali and alkaline earth metal atoms, which is almost independent of the intercalant metal species. We discuss the relevance to occurrence of superconductivity for the metal intercalated bilayer graphene in terms of the occupation of the interlayer state and the phonon frequency of metal ions.

Alkali metal intercalated fullerene-like MS(2) (M = W, Mo) nanoparticles and their properties.

PubMed

Zak, Alla; Feldman, Yishay; Lyakhovitskaya, Vera; Leitus, Gregory; Popovitz-Biro, Ronit; Wachtel, Ellen; Cohen, Hagai; Reich, Shimon; Tenne, Reshef

2002-05-01

Layered metal disulfides-MS(2) (M = Mo, W) in the form of fullerene-like nanoparticles and in the form of platelets (crystallites of the 2H polytype) have been intercalated by exposure to alkali metal (potassium and sodium) vapor using a two-zone transport method. The composition of the intercalated systems was established using X-ray energy dispersive spectrometer and X-ray photoelectron spectroscopy (XPS). The alkali metal concentration in the host lattice was found to depend on the kind of sample and the experimental conditions. Furthermore, an inhomogeneity of the intercalated samples was observed. The product consisted of both nonintercalated and intercalated phases. X-ray diffraction analysis and transmission electron microscopy of the samples, which were not exposed to the ambient atmosphere, showed that they suffered little change in their lattice parameters. On the other hand, after exposure to ambient atmosphere, substantial increase in the interplanar spacing (3-5 A) was observed for the intercalated phases. Insertion of one to two water molecules per intercalated metal atom was suggested as a possible explanation for this large expansion along the c-axis. Deintercalation of the hydrated alkali atoms and restacking of the MS(2) layers was observed in all the samples after prolonged exposure to the atmosphere. Electric field induced deintercalation of the alkali metal atoms from the host lattice was also observed by means of the XPS technique. Magnetic moment measurements for all the samples indicate a diamagnetic to paramagnetic transition after intercalation. Measurements of the transport properties reveal a semiconductor to metal transition for the heavily K intercalated 2H-MoS(2). Other samples show several orders of magnitude decrease in resistivity and two- to five-fold decrease in activation energies upon intercalation. These modifications are believed to occur via charge transfer from the alkali metal to the conduction band of the host lattice

Ion conducting fluoropolymer carbonates for alkali metal ion batteries

DOEpatents

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.

Aqueous alkali metal hydroxide insoluble cellulose ether membrane

NASA Technical Reports Server (NTRS)

Hoyt, H. E.; Pfluger, H. L. (Inventor)

1969-01-01

A membrane that is insoluble in an aqueous alkali metal hydroxide medium is described. The membrane is a resin which is a water-soluble C2-C4 hydroxyalkyl cellulose ether polymer and an insolubilizing agent for controlled water sorption, a dialytic and electrodialytic membrane. It is particularly useful as a separator between electrodes or plates in an alkaline storage battery.

Evidence for alkali metal formation at a cathode interface of organic electroluminescent devices by thermal decomposition of alkali metal carboxylates during their vapor deposition

NASA Astrophysics Data System (ADS)

Ganzorig, Chimed; Fujihira, Masamichi

2004-11-01

This study examines the possibility of thermal decomposition of Na salts of acetate, benzoate, and fluoride during vacuum vapor deposition using a quartz crystal microbalance to measure negative frequency shift (Δf) caused by increasing mass deposited from the same amount of source materials. Cs acetate is also examined. We compare the negative frequency shift-source current (Δf -I) curves of the Na salts with those of organic materials such as tris(8-hydroxyquinoline)aluminum and N ,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine. CH3COONa and C6H5COONa exhibit much lower Δf than the organic materials. CH3COOCs gives much larger Δf than CH3COONa due to the higher atomic weight of Cs. These exhibit clear evidence for alkali metal formation by thermal decomposition during vapor deposition of alkali metal carboxylates.

Thermodynamics of Liquid Alkali Metals and Their Binary Alloys

NASA Astrophysics Data System (ADS)

Thakor, P. B.; Patel, Minal H.; Gajjar, P. N.; Jani, A. R.

2009-07-01

The theoretical investigation of thermodynamic properties like internal energy, entropy, Helmholtz free energy, heat of mixing (ΔE) and entropy of mixing (ΔS) of liquid alkali metals and their binary alloys are reported in the present paper. The effect of concentration on the thermodynamic properties of Ac1Bc2 alloy of the alkali-alkali elements is investigated and reported for the first time using our well established local pseudopotential. To investigate influence of exchange and correlation effects, we have used five different local field correction functions viz; Hartree(H), Taylor(T), Ichimaru and Utsumi(IU), Farid et al. (F) and Sarkar et al. (S). The increase of concentration C2, increases the internal energy and Helmholtz free energy of liquid alloy Ac1Bc2. The behavior of present computation is not showing any abnormality in the outcome and hence confirms the applicability of our model potential in explaining the thermodynamics of liquid binary alloys.

Cluster-assembled metallic glasses

PubMed Central

2013-01-01

A bottom-up approach to nanofabricate metallic glasses from metal clusters as building blocks is presented. Considering metallic glasses as a subclass of cluster-assembled materials, the relation between the two lively fields of metal clusters and metallic glasses is pointed out. Deposition of selected clusters or collections of them, generated by state-of-the-art cluster beam sources, could lead to the production of a well-defined amorphous material. In contrast to rapidly quenched glasses where only the composition of the glass can be controlled, in cluster-assembled glasses, one can precisely control the structural building blocks. Comparing properties of glasses with similar compositions but differing in building blocks and therefore different in structure will facilitate the study of structure–property correlation in metallic glasses. This bottom-up method provides a novel alternative path to the synthesis of glassy alloys and will contribute to improving fundamental understanding in the field of metallic glasses. It may even permit the production of glassy materials for alloys that cannot be quenched rapidly enough to circumvent crystallization. Additionally, gaining deeper insight into the parameters governing the structure–property relation in metallic glasses can have a great impact on understanding and design of other cluster-assembled materials. PMID:23899019

High capacity nickel battery material doped with alkali metal cations

DOEpatents

Jackovitz, John F.; Pantier, Earl A.

1982-05-18

A high capacity battery material is made, consisting essentially of hydrated Ni(II) hydroxide, and about 5 wt. % to about 40 wt. % of Ni(IV) hydrated oxide interlayer doped with alkali metal cations selected from potassium, sodium and lithium cations.

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

NASA Astrophysics Data System (ADS)

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.

Effect of thermal annealing on the redistribution of alkali metals in Cu(In,Ga)Se 2 solar cells on glass substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamikawa, Yukiko; Nishinaga, Jiro; Ishizuka, Shogo

The precise control of alkali-metal concentrations in Cu(In,Ga)Se 2 (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 frommore » 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.« less

Effect of thermal annealing on the redistribution of alkali metals in Cu(In,Ga)Se 2 solar cells on glass substrate

DOE PAGES

Kamikawa, Yukiko; Nishinaga, Jiro; Ishizuka, Shogo; ...

2018-03-07

The precise control of alkali-metal concentrations in Cu(In,Ga)Se 2 (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 frommore » 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.« less

Transversely diode-pumped alkali metal vapour laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parkhomenko, A I; Shalagin, A M

2015-09-30

We have studied theoretically the operation of a transversely diode-pumped alkali metal vapour laser. For the case of high-intensity laser radiation, we have obtained an analytical solution to a complex system of differential equations describing the laser. This solution allows one to exhaustively determine all the energy characteristics of the laser and to find optimal parameters of the working medium and pump radiation (temperature, buffer gas pressure, and intensity and width of the pump spectrum). (lasers)

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

NASA Astrophysics Data System (ADS)

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

Helium cluster isolation spectroscopy

NASA Astrophysics Data System (ADS)

Higgins, John Paul

Clusters of helium, each containing ~103- 104 atoms, are produced in a molecular beam and are doped with alkali metal atoms (Li, Na, and K) and large organic molecules. Electronic spectroscopy in the visible and UV regions of the spectrum is carried out on the dopant species. Since large helium clusters are liquid and attain an equilibrium internal temperature of 0.4 K, they interact weakly with atoms or molecules absorbed on their surface or resident inside the cluster. The spectra that are obtained are characterized by small frequency shifts from the positions of the gas phase transitions, narrow lines, and cold vibrational temperatures. Alkali atoms aggregate on the helium cluster surface to form dimers and trimers. The spectra of singlet alkali dimers exhibit the presence of elementary excitations in the superfluid helium cluster matrix. It is found that preparation of the alkali molecules on the surface of helium clusters leads to the preferential formation of high-spin, van der Waals bound, triplet dimers and quartet trimers. Four bound-bound and two bound-free transitions are observed in the triplet manifold of the alkali dimers. The quartet trimers serve as an ideal system for the study of a simple unimolecular reaction in the cold helium cluster environment. Analysis of the lowest quartet state provides valuable insight into three-body forces in a van der Waals trimer. The wide range of atomic and molecular systems studied in this thesis constitutes a preliminary step in the development of helium cluster isolation spectroscopy, a hybrid technique combining the advantages of high resolution spectroscopy with the synthetic, low temperature environment of matrices.

Theory of metal atom-water interactions and alkali halide dimers

NASA Technical Reports Server (NTRS)

Jordan, K. D.; Kurtz, H. A.

1982-01-01

Theoretical studies of the interactions of metal atoms with water and some of its isoelectronic analogs, and of the properties of alkali halides and their aggregates are discussed. Results are presented of ab initio calculations of the heats of reaction of the metal-water adducts and hydroxyhydrides of Li, Be, B, Na, Mg, and Al, and of the bond lengths and angles an; the heats of reaction for the insertion of Al into HF, H2O, NH3, H2S and CH3OH, and Be and Mg into H2O. Calculations of the electron affinities and dipole moments and polarizabilities of selected gas phase alkali halide monomers and dimers are discussed, with particular attention given to results of calculations of the polarizability of LiF taking into account electron correlation effects, and the polarizability of the dimer (LiF)2.

Thermal Coefficient of Redox Potential of Alkali Metals

NASA Astrophysics Data System (ADS)

Fukuzumi, Yuya; Hinuma, Yoyo; Moritomo, Yutaka

2018-05-01

The thermal coefficient (α) of redox potential (V) is a significant physical quantity that converts the thermal energy into electric energy. In this short note, we carefully determined α of alkali metals (A = Li and Na) against electrolyte solution. The obtained α is much larger than that expected from the specific heat (CpA) of solid A and depends on electrolyte solution. These observations indicate that the solvent has significant effect on α.

Alkali metal carbon dioxide electrochemical system for energy storage and/or conversion of carbon dioxide to oxygen

NASA Technical Reports Server (NTRS)

Hagedorn, Norman H. (Inventor)

1993-01-01

An alkali metal, such as lithium, is the anodic reactant; carbon dioxide or a mixture of carbon dioxide and carbon monoxide is the cathodic reactant; and carbonate of the alkali metal is the electrolyte in an electrochemical cell for the storage and delivery of electrical energy. Additionally, alkali metal-carbon dioxide battery systems include a plurality of such electrochemical cells. Gold is a preferred catalyst for reducing the carbon dioxide at the cathode. The fuel cell of the invention produces electrochemical energy through the use of an anodic reactant which is extremely energetic and light, and a cathodic reactant which can be extracted from its environment and therefore exacts no transportation penalty. The invention is, therefore, especially useful in extraterrestrial environments.

Effect of Alkali Metal Cations on Slow Inactivation of Cardiac Na+ Channels

PubMed Central

Townsend, Claire; Horn, Richard

1997-01-01

Human heart Na+ channels were expressed transiently in both mammalian cells and Xenopus oocytes, and Na+ currents measured using 150 mM intracellular Na+. The kinetics of decaying outward Na+ current in response to 1-s depolarizations in the F1485Q mutant depends on the predominant cation in the extracellular solution, suggesting an effect on slow inactivation. The decay rate is lower for the alkali metal cations Li+, Na+, K+, Rb+, and Cs+ than for the organic cations Tris, tetramethylammonium, N-methylglucamine, and choline. In whole cell recordings, raising [Na+]o from 10 to 150 mM increases the rate of recovery from slow inactivation at −140 mV, decreases the rate of slow inactivation at relatively depolarized voltages, and shifts steady-state slow inactivation in a depolarized direction. Single channel recordings of F1485Q show a decrease in the number of blank (i.e., null) records when [Na+]o is increased. Significant clustering of blank records when depolarizing at a frequency of 0.5 Hz suggests that periods of inactivity represent the sojourn of a channel in a slow-inactivated state. Examination of the single channel kinetics at +60 mV during 90-ms depolarizations shows that neither open time, closed time, nor first latency is significantly affected by [Na+]o. However raising [Na+]o decreases the duration of the last closed interval terminated by the end of the depolarization, leading to an increased number of openings at the depolarized voltage. Analysis of single channel data indicates that at a depolarized voltage a single rate constant for entry into a slow-inactivated state is reduced in high [Na+]o, suggesting that the binding of an alkali metal cation, perhaps in the ion-conducting pore, inhibits the closing of the slow inactivation gate. PMID:9234168

Coordination effect-regulated CO2 capture with an alkali metal onium salts/crown ether system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Zhen-Zhen; Jiang, Deen; Zhu, Xiang

2014-01-01

A coordination effect was employed to realize equimolar CO2 absorption, adopting easily synthesized amino group containing absorbents (alkali metal onium salts). The essence of our strategy was to increase the steric hindrance of cations so as to enhance a carbamic acid pathway for CO2 capture. Our easily synthesized alkali metal amino acid salts or phenolates were coordinated with crown ethers, in which highly sterically hindered cations were obtained through a strong coordination effect of crown ethers with alkali metal cations. For example, a CO2 capacity of 0.99 was attained by potassium prolinate/18-crown-6, being characterized by NMR, FT-IR, and quantum chemistrymore » calculations to go through a carbamic acid formation pathway. The captured CO2 can be stripped under very mild conditions (50 degrees C, N-2). Thus, this protocol offers an alternative for the development of technological innovation towards efficient and low energy processes for carbon capture and sequestration.« less

40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Fluorinated carboxylic acid alkali metal salts. 721.4663 Section 721.4663 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4663...

Ultrafast selective transport of alkali metal ions in metal organic frameworks with subnanometer pores

PubMed Central

Zhang, Huacheng; Hou, Jue; Hu, Yaoxin; Wang, Peiyao; Ou, Ranwen; Jiang, Lei; Liu, Jefferson Zhe; Freeman, Benny D.; Hill, Anita J.; Wang, Huanting

2018-01-01

Porous membranes with ultrafast ion permeation and high ion selectivity are highly desirable for efficient mineral separation, water purification, and energy conversion, but it is still a huge challenge to efficiently separate monatomic ions of the same valence and similar sizes using synthetic membranes. We report metal organic framework (MOF) membranes, including ZIF-8 and UiO-66 membranes with uniform subnanometer pores consisting of angstrom-sized windows and nanometer-sized cavities for ultrafast selective transport of alkali metal ions. The angstrom-sized windows acted as ion selectivity filters for selection of alkali metal ions, whereas the nanometer-sized cavities functioned as ion conductive pores for ultrafast ion transport. The ZIF-8 and UiO-66 membranes showed a LiCl/RbCl selectivity of ~4.6 and ~1.8, respectively, which are much greater than the LiCl/RbCl selectivity of 0.6 to 0.8 measured in traditional porous membranes. Molecular dynamics simulations suggested that ultrafast and selective ion transport in ZIF-8 was associated with partial dehydration effects. This study reveals ultrafast and selective transport of monovalent ions in subnanometer MOF pores and opens up a new avenue to develop unique MOF platforms for efficient ion separations in the future. PMID:29487910

Ultrafast selective transport of alkali metal ions in metal organic frameworks with subnanometer pores.

PubMed

Zhang, Huacheng; Hou, Jue; Hu, Yaoxin; Wang, Peiyao; Ou, Ranwen; Jiang, Lei; Liu, Jefferson Zhe; Freeman, Benny D; Hill, Anita J; Wang, Huanting

2018-02-01

Porous membranes with ultrafast ion permeation and high ion selectivity are highly desirable for efficient mineral separation, water purification, and energy conversion, but it is still a huge challenge to efficiently separate monatomic ions of the same valence and similar sizes using synthetic membranes. We report metal organic framework (MOF) membranes, including ZIF-8 and UiO-66 membranes with uniform subnanometer pores consisting of angstrom-sized windows and nanometer-sized cavities for ultrafast selective transport of alkali metal ions. The angstrom-sized windows acted as ion selectivity filters for selection of alkali metal ions, whereas the nanometer-sized cavities functioned as ion conductive pores for ultrafast ion transport. The ZIF-8 and UiO-66 membranes showed a LiCl/RbCl selectivity of ~4.6 and ~1.8, respectively, which are much greater than the LiCl/RbCl selectivity of 0.6 to 0.8 measured in traditional porous membranes. Molecular dynamics simulations suggested that ultrafast and selective ion transport in ZIF-8 was associated with partial dehydration effects. This study reveals ultrafast and selective transport of monovalent ions in subnanometer MOF pores and opens up a new avenue to develop unique MOF platforms for efficient ion separations in the future.

[On-line analysis and mass concentration characters of the alkali metal ions of PM10 in Beijing].

PubMed

Zhang, Kai; Wang, Yue-Si; Wen, Tian-Xue; Liu, Guang-Ren; Hu, Bo; Zhao, Ya-Nan

2008-01-01

The mass concentration characters and the sources of water-soluble alkali metal ions in PM10 in 2004 and 2005 in Beijing were analyzed by using the system of rapid collection of particles. The result showed that the average concentration of Na+, K+, Mg2+ and Ca2+ was 0.5-1.4, 0.5-2.5, 0.1-0.5 and 0.6-5.8 microg/m3, respectively. The highest and lowest concentration appeared in different seasons for the alkali metal ions, which was related to the quality and source. The concentration of alkali metal ions was no difference between the heating period and no heating period, which meant the heating was not the main source. Sea salt and soil were the important sources of Na+. The source of K+ came from biomass burning and vegetation. Soil was the large source of Mg2+ and Ca2+. The alkali metal ions appeared different daily variation in different seasons. Precipitation could decrease the concentration of Na+, K+, Mg2+ and Ca2+, which was 10%-70%, 20%-80%, 10%-77%, 5%-80% respectively.

Fluorescent probes and bioimaging: alkali metals, alkaline earth metals and pH.

PubMed

Yin, Jun; Hu, Ying; Yoon, Juyoung

2015-07-21

All living species and life forms have an absolute requirement for bio-functional metals and acid-base equilibrium chemistry owing to the critical roles they play in biological processes. Hence, a great need exists for efficient methods to detect and monitor biometals and acids. In the last few years, great attention has been paid to the development of organic molecule based fluorescent chemosensors. The availability of new synthetic fluorescent probes has made fluorescence microscopy an indispensable tool for tracing biologically important molecules and in the area of clinical diagnostics. This review highlights the recent advances that have been made in the design and bioimaging applications of fluorescent probes for alkali metals and alkaline earth metal cations, including lithium, sodium and potassium, magnesium and calcium, and for pH determination within biological systems.

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

PubMed

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.

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

PubMed

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.

Electrolytic method to make alkali alcoholates using ion conducting alkali electrolyte/separator

DOEpatents

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.

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

PubMed Central

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. PMID:26839810

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.

PubMed

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.

Crown Ether Complexes of Alkali-Metal Chlorides from SO2.

PubMed

Reuter, Kirsten; Rudel, Stefan S; Buchner, Magnus R; Kraus, Florian; von Hänisch, Carsten

2017-07-18

The structures of alkali-metal chloride SO 2 solvates (Li-Cs) in conjunction with 12-crown-4 or 1,2-disila-12-crown-4 show strong discrepancies, despite the structural similarity of the ligands. Both types of crown ethers form 1:1 complexes with LiCl to give [Li(1,2-disila-12-crown-4)(SO 2 Cl)] (1) and [Li(12-crown-4)Cl]⋅4 SO 2 (2). However, 1,2-disila-12-crown-4 proved unable to coordinate cations too large for the cavity diameter, for example, by the formation of sandwich-type complexes. As a result, 12-crown-4 reacts exclusively with the heavier alkali-metal chlorides NaCl, KCl and RbCl. Compounds [Na(12-crown-4) 2 ]Cl⋅4 SO 2 (3) and [M(12-crown-4) 2 (SO 2 )]Cl⋅4 SO 2 (4: M=K; 5: M=Rb) all showed S-coordination to the chloride ions through four SO 2 molecules. Compounds 4 and 5 additionally exhibit the first crystallographically confirmed non-bridging O,O'-coordination mode of SO 2 . Unexpectedly, the disila-crown ether supports the dissolution of RbCl and CsCl in the solvent and gives the homoleptic SO 2 -solvated alkali-metal chlorides [MCl⋅3 SO 2 ] (6: M=Rb; 7: M=Cs), which incorporate bridging μ-O,O'-coordinating moieties and the unprecedented side-on O,O'-coordination mode. All compounds were characterised by single-crystal X-ray diffraction. The crown ether complexes were additionally studied by using NMR spectroscopy, and the presence of SO 2 at ambient temperature was revealed by IR spectroscopy of the neat compounds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Path integral Monte Carlo study on the structure and absorption spectra of alkali atoms (Li, Na, K) attached to superfluid helium clusters

NASA Astrophysics Data System (ADS)

Nakayama, Akira; Yamashita, Koichi

2001-01-01

Path integral Monte Carlo calculations have been performed to investigate the microscopic structure and thermodynamic properties of the AkṡHeN (Ak=Li, Na, K,N⩽300) clusters at T=0.5 K. Absorption spectra which correspond to the 2P←2S transitions of alkali atoms are also calculated within a pairwise additive model, which employs diatomic Ak-He potential energy curves. The size dependences of the cluster structure and absorption spectra that show the influence of the helium cluster environment are examined in detail. It is found that alkali atoms are trapped in a dimple on the helium cluster's surface and that, from the asymptotic behavior, the AkṡHe300 cluster, at least semiquantitatively, mimics the local structure of experimentally produced large helium clusters in the vicinity of alkali atoms. We have successfully reproduced the overall shapes of the spectra and explained their features from a static and structural point of view. The positions, relative intensities, and line widths of the absorption maxima are calculated to be in moderate agreement with experiments [F. Stienkemeier, J. Higgins, C. Callegari, S. I. Kanorsky, W. E. Ernst, and G. Scoles, Z. Phys. D 38, 253 (1996)].

Cathode architectures for alkali metal / oxygen batteries

DOEpatents

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.

Thermodynamics of Small Alkali Metal Halide Cluster Ions: Comparison of Classical Molecular Simulations with Experiment and Quantum Chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vlcek, Lukas; Uhlik, Filip; Moucka, Filip

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 ionmore » 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.« less

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

PubMed

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.

The Alkali Metal Thermal-To-Electric Converter for Solar System Exploration

NASA Technical Reports Server (NTRS)

Ryan, M.

1999-01-01

AMTEC, the Alkali Metal Thermal to Electric Converter, is a direct thermal to electric energy conversion device; it has been demostrated to perform at high power densities, with open circuit voltages in single electrochemical cells up to 1.6 V and current desities up to 2.0 A/cm(sup 2).

Molybdenum cell for x-ray diffraction measurements of fluid alkali metals at high temperatures and high pressures

NASA Astrophysics Data System (ADS)

Matsuda, Kazuhiro; Tamura, Kozaburo; Katoh, Masahiro; Inui, Masanori

2004-03-01

We have developed a sample cell for x-ray diffraction measurements of fluid alkali metals at high temperatures and high pressures. All parts of the cell are made of molybdenum which is resistant to the chemical corrosion of alkali metals. Single crystalline molybdenum disks electrolytically thinned down to 40 μm were used as the walls of the cell through which x rays pass. The crystal orientation of the disks was controlled in order to reduce the background from the cell. All parts of the cell were assembled and brazed together using a high-temperature Ru-Mo alloy. Energy dispersive x-ray diffraction measurements have been successfully carried out for fluid rubidium up to 1973 K and 16.2 MPa. The obtained S(Q) demonstrates the applicability of the molybdenum cell to x-ray diffraction measurements of fluid alkali metals at high temperatures and high pressures.

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

NASA Astrophysics Data System (ADS)

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.

Investigating the effects of alkali metal Na addition on catalytic activity of HZSM-5 for methyl mercaptan elimination

NASA Astrophysics Data System (ADS)

Yu, Jie; He, Dedong; Chen, Dingkai; Liu, Jiangping; Lu, Jichang; Liu, Feng; Liu, Pan; Zhao, Yutong; Xu, Zhizhi; Luo, Yongming

2017-10-01

Na-modified HZSM-5 catalysts with different Na loading amounts were prepared by incipient-wetness impregnation method and their catalytic activities for methyl mercaptan catalytic elimination were analyzed. XRD, N2 adsorption-desorption, NH3-TPD, CO2-TPD and FT-IR measurements were carried out to investigate the effects of modification of alkali metal Na on the physicochemical properties of the HZSM-5 zeolite catalyst. Research results illustrated that the introduction of alkali metal Na can improve catalytic activity for CH3SH catalytic elimination. CH3SH can be almost completely converted over 3%-Na/HZSM-5 at 450 °C compared to pure HZSM-5 at 600 °C based on our experimental results and the results from previous research. The improved catalytic activity could be attributed to the regulated acid-base properties of the HZSM-5 catalysts by doping with alkali metal Na. High alkali concentration treatment, however, may destroy the framework structure of the catalyst sample, thus causing the poor stability performance of the obtained catalyst.

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

PubMed

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.

A Study of the Hydration of the Alkali Metal Ions in Aqueous Solution

PubMed Central

2011-01-01

The hydration of the alkali metal ions in aqueous solution has been studied by large angle X-ray scattering (LAXS) and double difference infrared spectroscopy (DDIR). The structures of the dimethyl sulfoxide solvated alkali metal ions in solution have been determined to support the studies in aqueous solution. The results of the LAXS and DDIR measurements show that the sodium, potassium, rubidium and cesium ions all are weakly hydrated with only a single shell of water molecules. The smaller lithium ion is more strongly hydrated, most probably with a second hydration shell present. The influence of the rubidium and cesium ions on the water structure was found to be very weak, and it was not possible to quantify this effect in a reliable way due to insufficient separation of the O–D stretching bands of partially deuterated water bound to these metal ions and the O–D stretching bands of the bulk water. Aqueous solutions of sodium, potassium and cesium iodide and cesium and lithium hydroxide have been studied by LAXS and M–O bond distances have been determined fairly accurately except for lithium. However, the number of water molecules binding to the alkali metal ions is very difficult to determine from the LAXS measurements as the number of distances and the temperature factor are strongly correlated. A thorough analysis of M–O bond distances in solid alkali metal compounds with ligands binding through oxygen has been made from available structure databases. There is relatively strong correlation between M–O bond distances and coordination numbers also for the alkali metal ions even though the M–O interactions are weak and the number of complexes of potassium, rubidium and cesium with well-defined coordination geometry is very small. The mean M–O bond distance in the hydrated sodium, potassium, rubidium and cesium ions in aqueous solution have been determined to be 2.43(2), 2.81(1), 2.98(1) and 3.07(1) Å, which corresponds to six-, seven-, eight- and

Alkali-metal silicate binders and methods of manufacture

NASA Technical Reports Server (NTRS)

Schutt, J. B. (Inventor)

1979-01-01

A paint binder is described which uses a potassium or sodium silicate dispersion having a silicon dioxide to alkali-metal oxide mol ratio of from 4.8:1 to 6.0:1. The binder exhibits stability during both manufacture and storage. The process of making the binder is predictable and repeatable and the binder may be made with inexpensive components. The high mol ratio is achieved with the inclusion of a silicon dioxide hydrogel. The binder, which also employs a silicone, is in the final form of a hydrogel sol.

Study of the reaction of tungsten carbide in molten alkali metal nitrates. Syntheses of divalent (s and d blocks) metal tungstates

NASA Astrophysics Data System (ADS)

Deloume, Jean-Pierre; Marote, Pedro; Sigala, Catherine; Matei, Cristian

2003-08-01

WC is tested as precursor to synthesize metal tungstates by reaction in molten alkali metal nitrates. This constitutes a complex redox system with two reducing agents, W and C, and an oxidizer having several oxidation states. The mass loss due to the evolution of gases reveals the reaction steps. The infrared analyses of the gas phase show what kind of reaction develops according to the temperature. WC produces a water-soluble alkali metal tungstate. The reaction of a mixture of WC and a divalent metal chloride (Mg, Ca, Ba, Ni, Cu, Zn) leads to water-insoluble metal tungstates. As the reactivity of the cations increases in the order Zn, Ni, Cu, the reaction of WC is modified by their presence. The physico-chemical characterizations of the products show that some of them are contaminated either by WC or by metal oxide. Some others are rather pure products. These differences, in relationship with the other analyses, allow to propose first reaction pathways of the tungsten carbide in molten salts.

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

DOEpatents

Tierney, J.W.; Wender, I.; Palekar, V.M.

1995-01-31

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--160 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.

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

DOEpatents

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.

Internal gettering by metal alloy clusters

DOEpatents

Buonassisi, Anthony; Heuer, Matthias; Istratov, Andrei A.; Pickett, Matthew D.; Marcus, Mathew A.; Weber, Eicke R.

2010-07-27

The present invention relates to the internal gettering of impurities in semiconductors by metal alloy clusters. In particular, intermetallic clusters are formed within silicon, such clusters containing two or more transition metal species. Such clusters have melting temperatures below that of the host material and are shown to be particularly effective in gettering impurities within the silicon and collecting them into isolated, less harmful locations. Novel compositions for some of the metal alloy clusters are also described.

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

PubMed

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.

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

NASA Astrophysics Data System (ADS)

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.

Understanding and Practical Use of Ligand and Metal Exchange Reactions in Thiolate-Protected Metal Clusters to Synthesize Controlled Metal Clusters.

PubMed

Niihori, Yoshiki; Hossain, Sakiat; Sharma, Sachil; Kumar, Bharat; Kurashige, Wataru; Negishi, Yuichi

2017-05-01

It is now possible to accurately synthesize thiolate (SR)-protected gold clusters (Au n (SR) m ) with various chemical compositions with atomic precision. The geometric structure, electronic structure, physical properties, and functions of these clusters are well known. In contrast, the ligand or metal atom exchange reactions between these clusters and other substances have not been studied extensively until recently, even though these phenomena were observed during early studies. Understanding the mechanisms of these reactions could allow desired functional metal clusters to be produced via exchange reactions. Therefore, we have studied the exchange reactions between Au n (SR) m and analogous clusters and other substances for the past four years. The results have enabled us to gain deep understanding of ligand exchange with respect to preferential exchange sites, acceleration means, effect on electronic structure, and intercluster exchange. We have also synthesized several new metal clusters using ligand and metal exchange reactions. In this account, we summarize our research on ligand and metal exchange reactions. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Al7CX (X=Li-Cs) clusters: Stability and the prospect for cluster materials

NASA Astrophysics Data System (ADS)

Ashman, C.; Khanna, S. N.; Pederson, M. R.; Kortus, J.

2000-12-01

Al7C clusters, recently found to have a high-electron affinity and exceptional stability, are shown to form ionic molecules when combined with alkali-metal atoms. Our studies, based on an ab initio gradient-corrected density-functional scheme, show that Al7CX (X=Li-Cs) clusters have a very low-electron affinity and a high-ionization potential. When combined, the two- and four-atom composite clusters of Al7CLi units leave the Al7C clusters almost intact. Preliminary studies indicate that Al7CLi may be suitable to form cluster-based materials.

Electronic and structural ground state of heavy alkali metals at high pressure

DOE PAGES

Fabbris, G.; Lim, J.; Veiga, L. S. I.; ...

2015-02-17

Here, alkali metals display unexpected properties at high pressure, including emergence of low symmetry crystal structures, that appear to occur due to enhanced electronic correlations among the otherwise nearly-free conduction electrons. We investigate the high pressure electronic and structural ground state of K, Rb, and Cs using x-ray absorption spectroscopy and x-ray diffraction measurements together with ab initio theoretical calculations. The sequence of phase transitions under pressure observed at low temperature is similar in all three heavy alkalis except for the absence of the oC84 phase in Cs. Both the experimental and theoretical results point to pressure-enhanced localization of themore » valence electrons characterized by pseudo-gap formation near the Fermi level and strong spd hybridization. Although the crystal structures predicted to host magnetic order in K are not observed, the localization process appears to drive these alkalis closer to a strongly correlated electron state.« less

Electronic and structural ground state of heavy alkali metals at high pressure

NASA Astrophysics Data System (ADS)

Fabbris, G.; Lim, J.; Veiga, L. S. I.; Haskel, D.; Schilling, J. S.

2015-02-01

Alkali metals display unexpected properties at high pressure, including emergence of low-symmetry crystal structures, which appear to occur due to enhanced electronic correlations among the otherwise nearly free conduction electrons. We investigate the high-pressure electronic and structural ground state of K, Rb, and Cs using x-ray absorption spectroscopy and x-ray diffraction measurements together with a b i n i t i o theoretical calculations. The sequence of phase transitions under pressure observed at low temperature is similar in all three heavy alkalis except for the absence of the o C 84 phase in Cs. Both the experimental and theoretical results point to pressure-enhanced localization of the valence electrons characterized by pseudogap formation near the Fermi level and strong s p d hybridization. Although the crystal structures predicted to host magnetic order in K are not observed, the localization process appears to drive these alkalis closer to a strongly correlated electron state.

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

PubMed

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.

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

NASA Astrophysics Data System (ADS)

Hummelshøj, J. S.; Landis, D. D.; Voss, J.; Jiang, T.; Tekin, A.; Bork, N.; Dułak, M.; Mortensen, J. J.; Adamska, L.; Andersin, J.; Baran, J. D.; Barmparis, G. D.; Bell, F.; Bezanilla, A. L.; Bjork, J.; Björketun, M. E.; Bleken, F.; Buchter, F.; Bürkle, M.; Burton, P. D.; Buus, B. B.; Calborean, A.; Calle-Vallejo, F.; Casolo, S.; Chandler, B. D.; Chi, D. H.; Czekaj, I.; Datta, S.; Datye, A.; DeLaRiva, A.; Despoja, V.; Dobrin, S.; Engelund, M.; Ferrighi, L.; Frondelius, P.; Fu, Q.; Fuentes, A.; Fürst, J.; García-Fuente, A.; Gavnholt, J.; Goeke, R.; Gudmundsdottir, S.; Hammond, K. D.; Hansen, H. A.; Hibbitts, D.; Hobi, E.; Howalt, J. G.; Hruby, S. L.; Huth, A.; Isaeva, L.; Jelic, J.; Jensen, I. J. T.; Kacprzak, K. A.; Kelkkanen, A.; Kelsey, D.; Kesanakurthi, D. S.; Kleis, J.; Klüpfel, P. J.; Konstantinov, I.; Korytar, R.; Koskinen, P.; Krishna, C.; Kunkes, E.; Larsen, A. H.; Lastra, J. M. G.; Lin, H.; Lopez-Acevedo, O.; Mantega, M.; Martínez, J. I.; Mesa, I. N.; Mowbray, D. J.; Mýrdal, J. S. G.; Natanzon, Y.; Nistor, A.; Olsen, T.; Park, H.; Pedroza, L. S.; Petzold, V.; Plaisance, C.; Rasmussen, J. A.; Ren, H.; Rizzi, M.; Ronco, A. S.; Rostgaard, C.; Saadi, S.; Salguero, L. A.; Santos, E. J. G.; Schoenhalz, A. L.; Shen, J.; Smedemand, M.; Stausholm-Møller, O. J.; Stibius, M.; Strange, M.; Su, H. B.; Temel, B.; Toftelund, A.; Tripkovic, V.; Vanin, M.; Viswanathan, V.; Vojvodic, A.; Wang, S.; Wellendorff, J.; Thygesen, K. S.; Rossmeisl, J.; Bligaard, T.; Jacobsen, K. W.; Nørskov, J. K.; Vegge, T.

2009-07-01

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 metal atom (M2) plus two to five (BH4)- groups, i.e., M1M2(BH4)2-5, using a number of model structures with trigonal, tetrahedral, octahedral, and free coordination of the metal borohydride complexes. Of the over 700 investigated structures, about 20 were predicted to form potentially stable alloys with promising decomposition energies. The M1(Al/Mn/Fe)(BH4)4, (Li/Na)Zn(BH4)3, and (Na/K)(Ni/Co)(BH4)3 alloys are found to be the most promising, followed by selected M1(Nb/Rh)(BH4)4 alloys.

Yarrowia lipolytica possesses two plasma membrane alkali metal cation/H+ antiporters with different functions in cell physiology.

PubMed

Papouskova, Klara; Sychrova, Hana

2006-04-03

The family of Nha antiporters mediating the efflux of alkali metal cations in exchange for protons across the plasma membrane is conserved in all yeast species. Yarrowia lipolytica is a dimorphic yeast, phylogenetically very distant from the model yeast Saccharomyces cerevisiae. A search in its sequenced genome revealed two genes (designated as YlNHA1 and YlNHA2) with homology to the S. cerevisiae NHA1 gene, which encodes a plasma membrane alkali metal cation/H+ antiporter. Upon heterologous expression of both YlNHA genes in S. cerevisiae, we showed that Y. lipolytica antiporters differ not only in length and sequence, but also in their affinity for individual substrates. While the YlNha1 protein mainly increased cell tolerance to potassium, YlNha2p displayed a remarkable transport capacity for sodium. Thus, Y. lipolytica is the first example of a yeast species with two plasma membrane alkali metal cation/H+ antiporters differing in their putative functions in cell physiology; cell detoxification vs. the maintenance of stable intracellular pH, potassium content and cell volume.

Alkali activation of recovered fuel-biofuel fly ash from fluidised-bed combustion: Stabilisation/solidification of heavy metals.

PubMed

Yliniemi, Juho; Pesonen, Janne; Tiainen, Minna; Illikainen, Mirja

2015-09-01

Recovered fuel-biofuel fly ash from a fluidized bed boiler was alkali-activated and granulated with a sodium-silicate solution in order to immobilise the heavy metals it contains. The effect of blast-furnace slag and metakaolin as co-binders were studied. Leaching standard EN 12457-3 was applied to evaluate the immobilisation potential. The results showed that Ba, Pb and Zn were effectively immobilised. However, there was increased leaching after alkali activation for As, Cu, Mo, Sb and V. The co-binders had minimal or even negative effect on the immobilisation. One exception was found for Cr, in which the slag decreased leaching, and one was found for Cu, in which the slag increased leaching. A sequential leaching procedure was utilized to gain a deeper understanding of the immobilisation mechanism. By using a sequential leaching procedure it is possible fractionate elements into watersoluble, acid-soluble, easily-reduced and oxidisable fractions, yielding a total 'bioavailable' amount that is potentially hazardous for the environment. It was found that the total bioavailable amount was lower following alkali activation for all heavy metals, although the water-soluble fraction was higher for some metals. Evidence from leaching tests suggests the immobilisation mechanism was chemical retention, or trapping inside the alkali activation reaction products, rather than physical retention, adsorption or precipitation as hydroxides. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

PubMed

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). Na 2/3 [Mg 0.28 Mn 0.72 ]O 2 exhibits an excess capacity and here we show that this is caused by oxygen redox, even though Mg 2+ 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, Na 2/3 [Mg 0.28 Mn 0.72 ]O 2 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 Mg 2+ remains in Na 2/3 [Mg 0.28 Mn 0.72 ]O 2 , which stabilizes oxygen.

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

NASA Astrophysics Data System (ADS)

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.

Production of metal particles and clusters

NASA Technical Reports Server (NTRS)

Mcmanus, S. P.

1982-01-01

The feasibility of producing novel metals or metal clusters in a low gravity environment was studied. The production of coordinately unsaturated metal carbonyls by thermolysis or photolysis of stable metal carbonyls has the potential to generate novel catalysts by this technique. Laser irradiation of available metal carbonyls was investigated. It is found that laser induced decomposition of metal carbonyls is feasible for producing a variety of coordinately unsaturated species. Formation of clustered species does occur but is hampered by weak metal-metal bonds.

Theoretical analysis of oxygen diffusion at startup in an alkali metal heat pipe with gettered alloy walls

NASA Technical Reports Server (NTRS)

Tower, L. K.

1973-01-01

The diffusion of oxygen into, or out of, a gettered alloy exposed to oxygenated alkali liquid metal coolant, a situation arising in some high temperature heat transfer systems, was analyzed. The relation between the diffusion process and the thermochemistry of oxygen in the alloy and in the alkali metal was developed by making several simplifying assumptions. The treatment is therefore theoretical in nature. However, a practical example pertaining to the startup of a heat pipe with walls of T-111, a tantalum alloy, and lithium working fluid illustrates the use of the figures contained in the analysis.

Integrated oil production and upgrading using molten alkali metal

DOEpatents

Gordon, John Howard

2016-10-04

A method that combines the oil retorting process (or other process needed to obtain/extract heavy oil or bitumen) with the process for upgrading these materials using sodium or other alkali metals. Specifically, the shale gas or other gases that are obtained from the retorting/extraction process may be introduced into the upgrading reactor and used to upgrade the oil feedstock. Also, the solid materials obtained from the reactor may be used as a fuel source, thereby providing the heat necessary for the retorting/extraction process. Other forms of integration are also disclosed.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

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 tomore » 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.« less

Radioisotope powered alkali metal thermoelectric converter design for space systems

NASA Technical Reports Server (NTRS)

Sievers, R. K.; Bankston, C. P.

1988-01-01

The design concept of an alkali-metal thermoelectric converter (AMTEC) for 15-30-percent-efficient conversion of heat from the General Purpose (radioisotope) Heat Source (GPHS) on spacecraft is presented. The basic physical principles of the conversion cycle are outlined; a theoretical model is derived; a modular design is described and illustrated with drawings; and the overall AMTEC/GPHS system design is characterized. Predicted performance data are presented in extensive tables and graphs and discussed in detail.

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

DOEpatents

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.

Quantum Mechanical Studies of Large Metal, Metal Oxide, and Metal Chalcogenide Nanoparticles and Clusters

DOE PAGES

Fernando, Amendra; Weerawardene, K. L. Dimuthu M.; Karimova, Natalia V.; ...

2015-04-21

Here, metal, metal oxide, and metal chalcogenide materials have a wide variety of applications. For example, many metal clusters and nanoparticles are used as catalysts for reactions varying from the oxidation of carbon monoxide to the reduction of protons to hydrogen gas. Noble metal nanoparticles have unique optical properties such as a surface plasmon resonance for large nanoparticles that yield applications in sensing and photonics. In addition, a number of transition metal clusters are magnetic. Metal oxide clusters and surfaces are commonly used as catalysts for reactions such as water splitting. Both metal oxide and metal chalcogenide materials can bemore » semiconducting, which leads to applications in sensors, electronics, and solar cells. Many researchers have been interested in studying nanoparticles and/or small clusters of these materials. Some of the system sizes under investigation have been experimentally synthesized, which enables direct theory–experiment comparison. Other clusters that have been examined theoretically are of interest as models of larger systems or surfaces. Often, the size-dependence of their properties such as their HOMO–LUMO gap, magnetic properties, optical properties, etc., is of interest.« less

Fluconazole affects the alkali-metal-cation homeostasis and susceptibility to cationic toxic compounds of Candida glabrata.

PubMed

Elicharova, Hana; Sychrova, Hana

2014-08-01

Candida glabrata is a salt-tolerant and fluconazole (FLC)-resistant yeast species. Here, we analyse the contribution of plasma-membrane alkali-metal-cation exporters, a cation/proton antiporter and a cation ATPase to cation homeostasis and the maintenance of membrane potential (ΔΨ). Using a series of single and double mutants lacking CNH1 and/or ENA1 genes we show that the inability to export potassium and toxic alkali-metal cations leads to a slight hyperpolarization of the plasma membrane of C. glabrata cells; this hyperpolarization drives more cations into the cells and affects cation homeostasis. Surprisingly, a much higher hyperpolarization of C. glabrata plasma membrane was produced by incubating cells with subinhibitory concentrations of FLC. FLC treatment resulted in a substantially increased sensitivity of cells to various cationic drugs and toxic cations that are driven into the cell by negative-inside plasma-membrane potential. The effect of the combination of FLC plus cationic drug treatment was enhanced by the malfunction of alkali-metal-cation transporters that contribute to the regulation of membrane potential and cation homeostasis. In summary, we show that the combination of subinhibitory concentrations of FLC and cationic drugs strongly affects the growth of C. glabrata cells. © 2014 The Authors.

Alkali Metal Doping for Improved CH3NH3PbI3 Perovskite Solar Cells.

PubMed

Zhao, Wangen; Yao, Zhun; Yu, Fengyang; Yang, Dong; Liu, Shengzhong Frank

2018-02-01

Organic-inorganic hybrid halide perovskites are proven to be a promising semiconductor material as the absorber layer of solar cells. However, the perovskite films always suffer from nonuniform coverage or high trap state density due to the polycrystalline characteristics, which degrade the photoelectric properties of thin films. Herein, the alkali metal ions which are stable against oxidation and reduction are used in the perovskite precursor solution to induce the process of crystallization and nucleation, then affect the properties of the perovskite film. It is found that the addition of the alkali metal ions clearly improves the quality of perovskite film: enlarges the grain sizes, reduces the defect state density, passivates the grain boundaries, increases the built-in potential ( V bi ), resulting to the enhancement in the power conversion efficiency of perovskite thin film solar cell.

Esr Spectra of Alkali-Metal Atoms on Helium Nanodroplets: a Theoretical Model for the Prediction of Helium Induced Hyperfine Structure Shifts

NASA Astrophysics Data System (ADS)

Hauser, Reas W.; Filatov, Michael; Ernst, Wolfgang E.

2013-06-01

We predict He-droplet-induced changes of the isotropic HFS constant a_{HFS} of the alkali-metal atoms M = Li, Na, K and Rb on the basis of a model description. Optically detected electron spin resonance spectroscopy has allowed high resolution measurements that show the influence of the helium droplet and its size on the unpaired electron spin density at the alkali nucleus. Our theoretical approach to describe this dependence is based on a combination of two well established techniques: Results of relativistic coupled-cluster calculations on the alkali-He dimers (energy and HFS constant as functions of the binding length) are mapped onto the doped-droplet-situation with the help of helium-density functional theory. We simulate doped droplets He_{N} with N ranging from 50 to 10000, using the diatomic alkali-He-potential energy curves as input. From the obtained density profiles we evaluate average distances between the dopant atom and its direct helium neighborhood. The distances are then set in relation to the variation of the HFS constant with binding length in the simplified alkali-He-dimer model picture. This method yields reliable relative shifts but involves a systematic absolute error. Hence, the absolute values of the shifts are tied to one experimentally determined HFS constant for ^{85}Rb-He_{N = 2000}. With this parameter choice we obtain results in good agreement with the available experimental data for Rb and K^{a,b} confirming the predicted 1/N trend of the functional dependence^{c}. M. Koch, G. Auböck, C. Callegari, and W. E. Ernst, Phys. Rev. Lett. 103, 035302-1-4 (2009) M. Koch, C. Callegari, and W. E. Ernst, Mol. Phys. 108 (7), 1005-1011 (2010) A. W. Hauser, T. Gruber, M. Filatov, and W. E. Ernst, ChemPhysChem (2013) online DOI: 10.1002/cphc.201200697

Raman and nuclear magnetic resonance investigation of alkali metal vapor interaction with alkene-based anti-relaxation coating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tretiak, O. Yu., E-mail: otretiak@genphys.ru; Balabas, M. V.; Blanchard, J. W.

2016-03-07

The use of anti-relaxation coatings in alkali vapor cells yields substantial performance improvements compared to a bare glass surface by reducing the probability of spin relaxation in wall collisions by several orders of magnitude. Some of the most effective anti-relaxation coating materials are alpha-olefins, which (as in the case of more traditional paraffin coatings) must undergo a curing period after cell manufacturing in order to achieve the desired behavior. Until now, however, it has been unclear what physicochemical processes occur during cell curing, and how they may affect relevant cell properties. We present the results of nondestructive Raman-spectroscopy and magnetic-resonancemore » investigations of the influence of alkali metal vapor (Cs or K) on an alpha-olefin, 1-nonadecene coating the inner surface of a glass cell. It was found that during the curing process, the alkali metal catalyzes migration of the carbon-carbon double bond, yielding a mixture of cis- and trans-2-nonadecene.« less

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

DOEpatents

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.

Structural and dynamical trends in alkali-metal silanides characterized by neutron-scattering methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Wan Si; Dimitrievska, Mirjana; Chotard, Jean -Noel

Structural, vibrational, and dynamical properties of the mono- and mixed-alkali silanides (MSiH 3, where M = K, Rb, Cs, K 0.5Rb 0.5, K 0.5Cs 0.5, and Rb 0.5Cs 0.5) were investigated by various neutron experiments, including neutron powder diffraction (NPD), neutron vibrational spectroscopy (NVS), neutron-scattering fixed-window scans (FWSs), and quasielastic neutron scattering (QENS) measurements. Structural characterization showed that the mixed compounds exhibit disordered (α) and ordered (β) phases for temperatures above and below about 200–250 K, respectively, in agreement with their monoalkali correspondents. Vibrational and dynamical properties are strongly influenced by the cation environment; in particular, there is a redmore » shift in the band energies of the librational and bending modes with increasing lattice size as a result of changes in the bond lengths and force constants. Additionally, slightly broader spectral features are observed in the case of the mixed compounds, indicating the presence of structural disorder caused by the random distribution of the alkali-metal cations within the lattice. FWS measurements upon heating showed that there is a large increase in reorientational mobility as the systems go through the order–disorder (β–α) phase transition, and measurements upon cooling of the α-phase revealed the known strong hysteresis for reversion back to the β-phase. Interestingly, at a given temperature, among the different alkali silanide compounds, the relative reorientational mobilities of the SiH 3 – anions in the α- and β-phases tended to decrease and increase, respectively, with increasing alkali-metal mass. Lastly, this dynamical result might provide some insights concerning the enthalpy–entropy compensation effect previously observed for these potentially promising hydrogen storage materials.« less

Structural and dynamical trends in alkali-metal silanides characterized by neutron-scattering methods

DOE PAGES

Tang, Wan Si; Dimitrievska, Mirjana; Chotard, Jean -Noel; ...

2016-09-02

Structural, vibrational, and dynamical properties of the mono- and mixed-alkali silanides (MSiH 3, where M = K, Rb, Cs, K 0.5Rb 0.5, K 0.5Cs 0.5, and Rb 0.5Cs 0.5) were investigated by various neutron experiments, including neutron powder diffraction (NPD), neutron vibrational spectroscopy (NVS), neutron-scattering fixed-window scans (FWSs), and quasielastic neutron scattering (QENS) measurements. Structural characterization showed that the mixed compounds exhibit disordered (α) and ordered (β) phases for temperatures above and below about 200–250 K, respectively, in agreement with their monoalkali correspondents. Vibrational and dynamical properties are strongly influenced by the cation environment; in particular, there is a redmore » shift in the band energies of the librational and bending modes with increasing lattice size as a result of changes in the bond lengths and force constants. Additionally, slightly broader spectral features are observed in the case of the mixed compounds, indicating the presence of structural disorder caused by the random distribution of the alkali-metal cations within the lattice. FWS measurements upon heating showed that there is a large increase in reorientational mobility as the systems go through the order–disorder (β–α) phase transition, and measurements upon cooling of the α-phase revealed the known strong hysteresis for reversion back to the β-phase. Interestingly, at a given temperature, among the different alkali silanide compounds, the relative reorientational mobilities of the SiH 3 – anions in the α- and β-phases tended to decrease and increase, respectively, with increasing alkali-metal mass. Lastly, this dynamical result might provide some insights concerning the enthalpy–entropy compensation effect previously observed for these potentially promising hydrogen storage materials.« less

Extraction process for removing metallic impurities from alkalide metals

DOEpatents

Royer, L.T.

1987-03-20

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.

Electron core ionization in compressed alkali metal cesium

NASA Astrophysics Data System (ADS)

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.

Alkali metal/halide thermal energy storage systems performance evaluation

NASA Technical Reports Server (NTRS)

Phillips, W. M.; Stearns, J. W.

1986-01-01

A pseudoheat-pipe heat transfer mechanism has been demonstrated effective in terms of both total heat removal efficiency and rate, on the one hand, and system isothermal characteristics, on the other, for solar thermal energy storage systems of the kind being contemplated for spacecraft. The selection of appropriate salt and alkali metal substances for the system renders it applicable to a wide temperature range. The rapid heat transfer rate obtainable makes possible the placing of the thermal energy storage system around the solar receiver canister, and the immersing of heat transfer fluid tubes in the phase change salt to obtain an isothermal heat source.

Analysis of the Alkali Metal Diatomic Spectra; Using molecular beams and ultracold molecules

NASA Astrophysics Data System (ADS)

Kim, Jin-Tae

2014-12-01

This ebook illustrates the complementarity of molecular beam (MB) spectra and ultracold molecule (UM) spectra in unraveling the complex electronic spectra of diatomic alkali metal molecules, using KRb as a prime example. Researchers interested in molecular spectroscopy, whether physicist, chemist, or engineer, may find this ebook helpful and may be able to apply similar ideas to their molecules of interest.

Post-harvest processing methods for reduction of silica and alkali metals in wheat straw.

PubMed

Thompson, David N; Shaw, Peter G; Lacey, Jeffrey A

2003-01-01

Silica and alkali metals in wheat straw limit its use for bioenergy and gasification. Slag deposits occur via the eutectic melting of SiO2 with K2O, trapping chlorides at surfaces and causing corrosion. A minimum melting point of 950 degrees C is desirable, corresponding to an SiO2:K2O weight ratio of about 3:1. Mild chemical treatments were used to reduce Si, K, and Cl, while varying temperature, concentration, % solids, and time. Dilute acid was more effective at removing K and Cl, while dilute alkali was more effective for Si. Reduction of minerals in this manner may prove economical for increasing utilization of the straw for combustion or gasification.

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

NASA Astrophysics Data System (ADS)

Pastore, G.; Tosi, M. P.

1984-06-01

This 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 an 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.

Ternary Amides Containing Transition Metals for Hydrogen Storage: A Case Study with Alkali Metal Amidozincates.

PubMed

Cao, Hujun; Richter, Theresia M M; Pistidda, Claudio; Chaudhary, Anna-Lisa; Santoru, Antonio; Gizer, Gökhan; Niewa, Rainer; Chen, Ping; Klassen, Thomas; Dornheim, Martin

2015-11-01

The alkali metal amidozincates Li4 [Zn(NH2)4](NH2)2 and K2[Zn(NH2)4] were, to the best of our knowledge, studied for the first time as hydrogen storage media. Compared with the LiNH2-2 LiH system, both Li4 [Zn(NH2)4](NH2)2-12 LiH and K2[Zn(NH2)4]-8 LiH systems showed improved rehydrogenation performance, especially K2[Zn(NH2)4]-8 LiH, which can be fully hydrogenated within 30 s at approximately 230 °C. The absorption properties are stable upon cycling. This work shows that ternary amides containing transition metals have great potential as hydrogen storage materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Low-temperature fabrication of alkali metal-organic charge transfer complexes on cotton textile for optoelectronics and gas sensing.

PubMed

Ramanathan, Rajesh; Walia, Sumeet; Kandjani, Ahmad Esmaielzadeh; Balendran, Sivacarendran; Mohammadtaheri, Mahsa; Bhargava, Suresh Kumar; Kalantar-zadeh, Kourosh; Bansal, Vipul

2015-02-03

A generalized low-temperature approach for fabricating high aspect ratio nanorod arrays of alkali metal-TCNQ (7,7,8,8-tetracyanoquinodimethane) charge transfer complexes at 140 °C is demonstrated. This facile approach overcomes the current limitation associated with fabrication of alkali metal-TCNQ complexes that are based on physical vapor deposition processes and typically require an excess of 800 °C. The compatibility of soft substrates with the proposed low-temperature route allows direct fabrication of NaTCNQ and LiTCNQ nanoarrays on individual cotton threads interwoven within the 3D matrix of textiles. The applicability of these textile-supported TCNQ-based organic charge transfer complexes toward optoelectronics and gas sensing applications is established.

Electrolytic systems and methods for making metal halides and refining metals

DOEpatents

Holland, Justin M.; Cecala, David M.

2015-05-26

Disclosed are electrochemical cells and methods for producing a halide of a non-alkali metal and for electrorefining the halide. The systems typically involve an electrochemical cell having a cathode structure configured for dissolving a hydrogen halide that forms the halide into a molten salt of the halogen and an alkali metal. Typically a direct current voltage is applied across the cathode and an anode that is fabricated with the non-alkali metal such that the halide of the non-alkali metal is formed adjacent the anode. Electrorefining cells and methods involve applying a direct current voltage across the anode where the halide of the non-alkali metal is formed and the cathode where the non-alkali metal is electro-deposited. In a representative embodiment the halogen is chlorine, the alkali metal is lithium and the non-alkali metal is uranium.

Heteronuclear Metal Cluster Compounds Synthesis and Reactivity

DTIC Science & Technology

1990-08-10

important role in the formation of complexes with heteronuclear metal - metal bonds. Since this is our Final Report recent results are reported and...DTe FL’ Copy AFOSR-86-0125 Lfl X’ HETERONUCLEAR METAL CLUSTER COMPOUNDS00 SYNTHESIS AND REACTIVITY F. Gordon A. Stone, IDepartment of Inorganic...Security Classification) HETERONUCLEAR METAL CLUSTER COMPOUNDS: SYNTHESIS AND REACTIVITY 12. PERSONAL AUTHOR(S) F. GORDON A. STONE 13a. TYPE OF REPORT

Heavier alkali-metal monosulfides (KS, RbS, CsS, and FrS) and their cations.

PubMed

Lee, Edmond P F; Wright, Timothy G

2005-10-08

The heavier alkali-metal monosulfides (KS, RbS, CsS, and FrS) have been studied by high-level ab initio calculations. The RCCSD(T) method has been employed, combined with large flexible valence basis sets. All-electron basis sets are used for potassium and sulfur, with effective core potentials being used for the other metals, describing the core electrons. Potential-energy curves are calculated for the lowest two neutral and cationic states: all neutral monosulfide species have a (2)Pi ground state, in contrast with the alkali-metal monoxide species, which undergo a change in the electronic ground state from (2)Pi to (2)Sigma(+) as the group is descended. In the cases of KS, RbS, and CsS, spin-orbit curves are also calculated. We also calculate potential-energy curves for the lowest (3)Sigma(-) and (3)Pi states of the cations. From the potential-energy curves, spectroscopic constants are derived, and for KS the spectroscopic results are compared to experimental spectroscopic values. Ionization energies, dissociation energies, and heats of formation are also calculated; for KS, we explore the effects of relativity and basis set extrapolation on these values.

Surface Tension of Liquid Alkali, Alkaline, and Main Group Metals: Theoretical Treatment and Relationship Investigations

NASA Astrophysics Data System (ADS)

Aqra, Fathi; Ayyad, Ahmed

2011-09-01

An improved theoretical method for calculating the surface tension of liquid metals is proposed. A recently derived equation that allows an accurate estimate of surface tension to be made for the large number of elements, based on statistical thermodynamics, is used for a means of calculating reliable values for the surface tension of pure liquid alkali, alkaline earth, and main group metals at the melting point, In order to increase the validity of the model, the surface tension of liquid lithium was calculated in the temperature range 454 K to 1300 K (181 °C to 1027 °C), where the calculated surface tension values follow a straight line behavior given by γ = 441 - 0.15 (T-Tm) (mJ m-2). The calculated surface excess entropy of liquid Li (- dγ/ dT) was found to be 0.15 mJ m-2 K-1, which agrees well with the reported experimental value (0.147 mJ/m2 K). Moreover, the relations of the calculated surface tension of alkali metals to atomic radius, heat of fusion, and specific heat capacity are described. The results are in excellent agreement with the existing experimental data.

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

PubMed

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.

Origin of low sodium capacity in graphite and generally weak substrate binding of Na and Mg among alkali and alkaline earth metals.

PubMed

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.

Theoretical study of mixed MLaX(4) (M = Na, K, Cs; X = F, Cl, Br, I) rare earth/alkali metal halide complexes.

PubMed

Groen, Cornelis Petrus; Oskam, Ad; Kovács, Attila

2003-02-10

The structure, bonding, and vibrational properties of the mixed MLaX(4) (M = Na, K, Cs; X = F, Cl, Br, I) rare earth/alkali metal halide complexes have been studied using the MP2 method in conjunction with polarized triple-zeta valence basis sets and quasi-relativistic effective core potentials for the heavy atoms. From the three characteristic structures, possessing 1- (C(3)(v)), 2- (C(2)(v)), or 3-fold coordination (C(3)(v)) between the alkali metal and the bridging halide atoms, the bi- and tridentate forms are stable isomers with close dissociation energies. In general, for the complexes existing of lighter alkali metals and halogens, the bidentate structure corresponds to the global minimum of the potential energy surface, while the heavier analogues favor the tridentate structure. At experimentally relevant temperatures (T > 800 K), however, the isomerization entropy leads to a domination of the bidentate structures over the tridentate forms for all complexes. An important effect of the size of the alkali metal is manifested in the larger stabilities of the K and Cs complexes. The natural atomic charges are in agreement with strong electrostatic interactions in the title complexes. The marginal covalent contributions show a slight increasing trend in the heavier analogues. The calculated vibrational data indicate that infrared spectroscopy may be an effective tool for experimental investigation and characterization of MLaX(4) molecules.

Fission of Polyanionic Metal Clusters

NASA Astrophysics Data System (ADS)

König, S.; Jankowski, A.; Marx, G.; Schweikhard, L.; Wolfram, M.

2018-04-01

Size-selected dianionic lead clusters Pbn2 -, n =34 - 56 , are stored in a Penning trap and studied with respect to their decay products upon photoexcitation. Contrary to the decay of other dianionic metal clusters, these lead clusters show a variety of decay channels. The mass spectra of the fragments are compared to the corresponding spectra of the monoanionic precursors. This comparison leads to the conclusion that, in the cluster size region below about n =48 , the fission reaction Pbn2 -→Pbn-10 -+Pb10- is the major decay process. Its disappearance at larger cluster sizes may be an indication of a nonmetal to metal transition. Recently, the pair of Pb10- and Pbn-10 - were observed as pronounced fragments in electron-attachment studies [S. König et al., Int. J. Mass Spectrom. 421, 129 (2017), 10.1016/j.ijms.2017.06.009]. The present findings suggest that this combination is the fingerprint of the decay of doubly charged lead clusters. With this assumption, the dianion clusters have been traced down to Pb212 -, whereas the smallest size for the direct observation was as high as n =28 .

Bond-length distributions for ions bonded to oxygen: alkali and alkaline-earth metals.

PubMed

Gagné, Olivier Charles; Hawthorne, Frank Christopher

2016-08-01

Bond-length distributions have been examined for 55 configurations of alkali-metal ions and 29 configurations of alkaline-earth-metal ions bonded to oxygen, for 4859 coordination polyhedra and 38 594 bond distances (alkali metals), and for 3038 coordination polyhedra and 24 487 bond distances (alkaline-earth metals). Bond lengths generally show a positively skewed Gaussian distribution that originates from the variation in Born repulsion and Coulomb attraction as a function of interatomic distance. The skewness and kurtosis of these distributions generally decrease with increasing coordination number of the central cation, a result of decreasing Born repulsion with increasing coordination number. We confirm the following minimum coordination numbers: ([3])Li(+), ([3])Na(+), ([4])K(+), ([4])Rb(+), ([6])Cs(+), ([3])Be(2+), ([4])Mg(2+), ([6])Ca(2+), ([6])Sr(2+) and ([6])Ba(2+), but note that some reported examples are the result of extensive dynamic and/or positional short-range disorder and are not ordered arrangements. Some distributions of bond lengths are distinctly multi-modal. This is commonly due to the occurrence of large numbers of structure refinements of a particular structure type in which a particular cation is always present, leading to an over-representation of a specific range of bond lengths. Outliers in the distributions of mean bond lengths are often associated with anomalous values of atomic displacement of the constituent cations and/or anions. For a sample of ([6])Na(+), the ratio Ueq(Na)/Ueq(bonded anions) is partially correlated with 〈([6])Na(+)-O(2-)〉 (R(2) = 0.57), suggesting that the mean bond length is correlated with vibrational/displacement characteristics of the constituent ions for a fixed coordination number. Mean bond lengths also show a weak correlation with bond-length distortion from the mean value in general, although some coordination numbers show the widest variation in mean bond length for zero distortion, e.g. Li(+) in

Alkali-Metal-Ion-Functionalized Graphene Oxide as a Superior Anode Material for Sodium-Ion Batteries.

PubMed

Wan, Fang; Li, Yu-Han; Liu, Dai-Huo; Guo, Jin-Zhi; Sun, Hai-Zhu; Zhang, Jing-Ping; Wu, Xing-Long

2016-06-06

Although graphene oxide (GO) has large interlayer spacing, it is still inappropriate to use it as an anode for sodium-ion batteries (SIBs) because of the existence of H-bonding between the layers and ultralow electrical conductivity which impedes the Na(+) and e(-) transformation. To solve these issues, chemical, thermal, and electrochemical procedures are traditionally employed to reduce GO nanosheets. However, these strategies are still unscalable, consume high amounts of energy, and are expensive for practical application. Here, for the first time, we describe the superior Na storage of unreduced GO by a simple and scalable alkali-metal-ion (Li(+) , Na(+) , K(+) )-functionalized process. The various alkali metals ions, connecting with the oxygen on GO, have played different effects on morphology, porosity, degree of disorder, and electrical conductivity, which are crucial for Na-storage capabilities. Electrochemical tests demonstrated that sodium-ion-functionalized GO (GNa) has shown outstanding Na-storage performance in terms of excellent rate capability and long-term cycle life (110 mAh g(-1) after 600 cycles at 1 A g(-1) ) owing to its high BET area, appropriate mesopore, high degree of disorder, and improved electrical conductivity. Theoretical calculations were performed using the generalized gradient approximation (GGA) to further study the Na-storage capabilities of functionalized GO. These calculations have indicated that the Na-O bond has the lowest binding energy, which is beneficial to insertion/extraction of the sodium ion, hence the GNa has shown the best Na-storage properties among all comparatives functionalized by other alkali metal ions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spin relaxation in ultracold collisions of molecular radicals with alkali-metal atoms

NASA Astrophysics Data System (ADS)

Tscherbul, Timur; Klos, Jacek; Zukowski, Piotr

2016-05-01

We present accurate quantum scattering calculations of spin relaxation in ultracold collisions of alkali-metal atoms and polar 2 Σ molecules CaH, SrF, and SrOH. The calculations employ state-of-the-art ab initio interaction potentials and a rigorous quantum theory of atom-molecule collisions in a magnetic field based on the total angular momentum representation. We will further discuss the relevance of the results to atom-molecule sympathetic cooling experiments in a magnetic trap.

Alkali Metal CO2 Sorbents and the Resulting Metal Carbonates: Potential for Process Intensification of Sorption-Enhanced Steam Reforming.

PubMed

Memon, Muhammad Zaki; Zhao, Xiao; Sikarwar, Vineet Singh; Vuppaladadiyam, Arun K; Milne, Steven J; Brown, Andy P; Li, Jinhui; Zhao, Ming

2017-01-03

Sorption-enhanced steam reforming (SESR) is an energy and cost efficient approach to produce hydrogen with high purity. SESR makes it economically feasible to use a wide range of feedstocks for hydrogen production such as methane, ethanol, and biomass. Selection of catalysts and sorbents plays a vital role in SESR. This article reviews the recent research aimed at process intensification by the integration of catalysis and chemisorption functions into a single material. Alkali metal ceramic powders, including Li 2 ZrO 3 , Li 4 SiO 4 and Na 2 ZrO 3 display characteristics suitable for capturing CO 2 at low concentrations (<15% CO 2 ) and high temperatures (>500 °C), and thus are applicable to precombustion technologies such as SESR, as well as postcombustion capture of CO 2 from flue gases. This paper reviews the progress made in improving the operational performance of alkali metal ceramics under conditions that simulate power plant and SESR operation, by adopting new methods of sorbent synthesis and doping with additional elements. The paper also discusses the role of carbonates formed after in situ CO 2 chemisorption during a steam reforming process in respect of catalysts for tar cracking.

Ultralow-power local laser control of the dimer density in alkali-metal vapors through photodesorption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jha, Pankaj K.; Scully, Marlan O.; Princeton University, Princeton, New Jersey 08544

2012-08-27

Ultralow-power diode-laser radiation is employed to induce photodesorption of cesium from a partially transparent thin-film cesium adsorbate on a solid surface. Using resonant Raman spectroscopy, we demonstrate that this photodesorption process enables an accurate local optical control of the density of dimer molecules in alkali-metal vapors.

Pseudopotential theoretical study of the alkali metals under arbitrary pressure: Density, bulk modulus, and shear moduli

NASA Astrophysics Data System (ADS)

Rasky, Daniel J.; Milstein, Frederick

1986-02-01

Milstein and Hill previously derived formulas for computing the bulk and shear moduli, κ, μ, and μ', at arbitrary pressures, for cubic crystals in which interatomic interaction energies are modeled by pairwise functions, and they carried out the moduli computations using the complete family of Morse functions. The present study extends their work to a pseudopotential description of atomic binding. Specifically: (1) General formulas are derived for determining these moduli under hydrostatic loading within the framework of a pseudopotential model. (2) A two-parameter pseudopotential model is used to describe atomic binding of the alkali metals, and the two parameters are determined from experimental data (the model employs the Heine-Abarenkov potential with the Taylor dielectric function). (3) For each alkali metal (Li, Na, K, Rb, and Cs), the model is used to compute the pressure-versus-volume behavior and, at zero pressure, the binding energy, the density, and the elastic moduli and their pressure derivatives; the theoretical behavior is found to be in excellent agreement with experiment. (4) Calculations are made of κ, μ, and μ' of the bcc alkali metals over wide ranges of hydrostatic compression and expansion. (5) The pseudopotential results are compared with those of arbitrary-central-force models (wherein κ-(2/3)μ=μ'+2P) and with the specific Morse-function results. The pressures, bulk moduli, and zero-pressure shear moduli (as determined for the Morse and pseudopotential models) are in excellent agreement, but important differences appear in the shear moduli under high compressions. The computations in the present paper are for the bcc metals; a subsequent paper will extend this work to include both the bcc and fcc structures, at compressions and expansions where elastic stability or lattice cohesion is, in practice, lost.

Promoter Effects of Alkali Metal Cations on the Electrochemical Reduction of Carbon Dioxide

DOE PAGES

Resasco, Joaquin; Chen, Leanne D.; Clark, Ezra; ...

2017-07-24

The electrochemical reduction of CO 2 is known to be influenced by the identity of the alkali metal cation in the electrolyte; however, a satisfactory explanation for this phenomenon has not been developed. Here we present the results of experimental and theoretical studies aimed at elucidating the effects of electrolyte cation size on the intrinsic activity and selectivity of metal catalysts for the reduction of CO 2. Experiments were conducted under conditions where the influence of electrolyte polarization is minimal in order to show that cation size affects the intrinsic rates of formation of certain reaction products, most notably formore » HCOO –, C 2H 4, and C 2H 5OH over Cu(100)- and Cu(111)-oriented thin films, and for CO and HCOO– over polycrystalline Ag and Sn. Interpretation of the findings for CO 2 reduction was informed by studies of the reduction of glyoxal and CO, key intermediates along the reaction pathway to final products. Density functional theory calculations show that the alkali metal cations influence the distribution of products formed as a consequence of electrostatic interactions between solvated cations present at the outer Helmholtz plane and adsorbed species having large dipole moments. As a result, the observed trends in activity with cation size are attributed to an increase in the concentration of cations at the outer Helmholtz plane with increasing cation size.« less

Promoter Effects of Alkali Metal Cations on the Electrochemical Reduction of Carbon Dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Resasco, Joaquin; Chen, Leanne D.; Clark, Ezra

The electrochemical reduction of CO 2 is known to be influenced by the identity of the alkali metal cation in the electrolyte; however, a satisfactory explanation for this phenomenon has not been developed. Here we present the results of experimental and theoretical studies aimed at elucidating the effects of electrolyte cation size on the intrinsic activity and selectivity of metal catalysts for the reduction of CO 2. Experiments were conducted under conditions where the influence of electrolyte polarization is minimal in order to show that cation size affects the intrinsic rates of formation of certain reaction products, most notably formore » HCOO –, C 2H 4, and C 2H 5OH over Cu(100)- and Cu(111)-oriented thin films, and for CO and HCOO– over polycrystalline Ag and Sn. Interpretation of the findings for CO 2 reduction was informed by studies of the reduction of glyoxal and CO, key intermediates along the reaction pathway to final products. Density functional theory calculations show that the alkali metal cations influence the distribution of products formed as a consequence of electrostatic interactions between solvated cations present at the outer Helmholtz plane and adsorbed species having large dipole moments. As a result, the observed trends in activity with cation size are attributed to an increase in the concentration of cations at the outer Helmholtz plane with increasing cation size.« less

Silicon halide-alkali metal flames as a source of solar grade silicon

NASA Technical Reports Server (NTRS)

Olsen, D. B.; Miller, W. J.

1979-01-01

The feasibility of using alkali metal-silicon halide diffusion flames to produce solar-grade silicon in large quantities and at low cost is demonstrated. Prior work shows that these flames are stable and that relatively high purity silicon can be produced using Na + SiCl4 flames. Silicon of similar purity is obtained from Na + SiF4 flames although yields are lower and product separation and collection are less thermochemically favored. Continuous separation of silicon from the byproduct alkali salt was demonstrated in a heated graphite reactor. The process was scaled up to reduce heat losses and to produce larger samples of silicon. Reagent delivery systems, scaled by a factor of 25, were built and operated at a production rate of 0.5 kg Si/h. Very rapid reactor heating rates are observed with wall temperatures reaching greater than 2000 K. Heat release parameters were measured using a cooled stainless steel reactor tube. A new reactor was designed.

Method of treating alkali metal sulfide and carbonate mixtures

DOEpatents

Kohl, Arthur L.; Rennick, Robert D.; Savinsky, Martin W.

1978-01-01

A method of removing and preferably recovering sulfur values from an alkali metal sulfide and carbonate mixture comprising the steps of (1) introducing the mixture in an aqueous medium into a first carbonation zone and reacting the mixture with a gas containing a major amount of CO.sub.2 and a minor amount of H.sub.2 S; (2) introducing the resultant product from step 1 into a stripping zone maintained at subatmospheric pressure, and contacting this product with steam to produce a gaseous mixture, comprising H.sub.2 S and water vapor, and a liquor of reduced sulfide content; (3) introducing the liquor of reduced sulfide content into a second carbonation zone, and reacting the liquor with substantially pure gaseous CO.sub.2 in an amount sufficient to precipitate bicarbonate crystals and produce an offgas containing CO.sub.2 and H.sub.2 S for use in step 1; (4) recovering the bicarbonate crystals from step 3, and thermally decomposing the crystals to produce an alkaline metal carbonate product and a substantially pure CO.sub.2 offgas for use in step 3.

Experimental (FT-IR, FT-Raman, 1H, 13C NMR) and theoretical study of alkali metal 2-aminobenzoates

NASA Astrophysics Data System (ADS)

Samsonowicz, M.; Świsłocka, R.; Regulska, E.; Lewandowski, W.

2008-09-01

The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of the 2-aminobenzoic acid was studied by the methods of molecular spectroscopy. The vibrational (FT-IR, FT-Raman) and NMR ( 1H and 13C) spectra for 2-aminobenzoic acid and its alkali metal salts were recorded. The assignment of vibrational spectra was done on the basis of literature data, theoretical calculations and our previous experience. Characteristic shifts of bands and changes in intensities of bands along the metal series were observed. The changes of chemical shifts of protons ( 1H NMR) and carbons ( 13C NMR) in the series of studied alkali metal 2-aminobenzoates were observed too. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G ∗∗ basis set. Geometric aromaticity indices, dipole moments and energies were also calculated. The theoretical wavenumbers and intensities of IR and Raman spectra were obtained. The calculated parameters were compared to experimental characteristic of studied compounds.

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

NASA Astrophysics Data System (ADS)

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.

Electron detachment energies in high-symmetry alkali halide solvated-electron anions

NASA Astrophysics Data System (ADS)

Anusiewicz, Iwona; Berdys, Joanna; Simons, Jack; Skurski, Piotr

2003-07-01

We decompose the vertical electron detachment energies (VDEs) in solvated-electron clusters of alkali halides in terms of (i) an electrostatic contribution that correlates with the dipole moment (μ) of the individual alkali halide molecule and (ii) a relaxation component that is related to the polarizability (α) of the alkali halide molecule. Detailed numerical ab initio results for twelve species (MX)n- (M=Li,Na; X=F,Cl,Br; n=2,3) are used to construct an interpolation model that relates the clusters' VDEs to their μ and α values as well as a cluster size parameter r that we show is closely related to the alkali cation's ionic radius. The interpolation formula is then tested by applying it to predict the VDEs of four systems [i.e., (KF)2-, (KF)3-, (KCl)2-, and (KCl)3-] that were not used in determining the parameters of the model. The average difference between the model's predicted VDEs and the ab initio calculated electron binding energies is less than 4% (for the twelve species studied). It is concluded that one can easily estimate the VDE of a given high-symmetry solvated electron system by employing the model put forth here if the α, μ and cation ionic radii are known. Alternatively, if VDEs are measured for an alkali halide cluster and the α and μ values are known, one can estimate the r parameter, which, in turn, determines the "size" of the cluster anion.

Absorption Spectroscopy of Rubidium in an Alkali Metal Dispenser Cell and Bleached Wave Analysis

DTIC Science & Technology

2015-03-26

Department of Engineering Physics Graduate School of Engineering and Management Air Force Institute of Technology Air University Air Education and...at atmospheric temperatures and pressures, so none of the safety measures needed with pure solid alkali metal would be required. AMDs can also be...Institute of Technology Graduate School of Engineering and Management (AFIT/ENP) 2950 Hobson Way WPAFB OH 45433-7765 8. PERFORMING ORGANIZATION

Ionic conductivity of β-cyclodextrin-polyethylene-oxide/alkali-metal-salt complex.

PubMed

Yang, Ling-Yun; Fu, Xiao-Bin; Chen, Tai-Qiang; Pan, Li-Kun; Ji, Peng; Yao, Ye-Feng; Chen, Qun

2015-04-20

Highly conductive, crystalline, polymer electrolytes, β-cyclodextrin (β-CD)-polyethylene oxide (PEO)/LiAsF6 and β-CD-PEO/NaAsF6 , were prepared through supramolecular self-assembly of PEO, β-CD, and LiAsF6 /NaAsF6 . The assembled β-CDs form nanochannels in which the PEO/X(+) (X=Li, Na) complexes are confined. The nanochannels provide a pathway for directional motion of the alkali metal ions and, at the same time, separate the cations and the anions by size exclusion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Supersonic Bare Metal Cluster Beams. Final Report

DOE R&D Accomplishments Database

Smalley, R. E.

1997-10-14

A major portion of the project involved elucidating the relation between reactivity and the electronic structure of transition-metal (TM) clusters of 2--200 atoms, which required the construction and continuous development of two principal apparati; the Fourier Transform-Ion Cyclotron Resonance (FT-ICR) apparatus, and Ultraviolet Photoelectron Spectroscopy (UPS). Together, these machines have enabled the most detailed probing of the structure and chemical reactivity of TM clusters. Clusters of all the transition metals were included in these studies. Fundamental aspects in chemisorption, reactivity, and heterogeneous catalysis have also become better understood as a result of these experiments for important classes of systems such as H{sub 2}, CO, and CO{sub 2} adsorbed onto clusters of many of the metals listed above. In particular, a correlation was found between reactivity of H{sub 2} with Fe, Co, and Ni clusters and differences between the cluster IP and EA. As recounted in a previous technical report, the DOE`s role in the initial discovery of fullerenes at Rice was central, and from the start investigations were made into metal atoms trapped in the fullerenes cage. More recently, the authors have discovered that 2--4 atoms of La, Y, or Sc can be produced by laser vaporization of composite graphite/metal-oxide disks. This work was largely motivated by the prospects of using such endohedral TM metals for their catalytic activity without the well-known difficulties of effective support media and lack of control over particle size. Thus, while it will certainly be important to discover ways to efficiently scale up production (e.g., the solar generation method explored with DOE support), the efforts have concentrated more on characterization, purification, and manipulation of doped fullerenes. For the past two years, much of the group`s effort has involved the production, purification, and characterization of carbon nanotubes.

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

NASA Astrophysics Data System (ADS)

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.

Chemical effects of alkali atoms on critical temperature in superconducting alkali-doped fullerides

NASA Astrophysics Data System (ADS)

Hetfleisch, F.; Gunnarsson, O.; Srama, R.; Han, J. E.; Stepper, M.; Roeser, H.-P.; Bohr, A.; Lopez, J. S.; Mashmool, M.; Roth, S.

2018-03-01

Alkali metal doped fullerides (A3C60) are superconductors with critical temperatures, Tc, extending up to 38 K. Tc is known to depend strongly on the lattice parameter a, which can be adjusted by physical or chemical pressure. In the latter case an alkali atom is replaced by a different sized one, which changes a. We have collected an extensive data base of experimental data for Tc from very early up to recent measurements. We disentangle alkali atom chemical effects on Tc, beyond the well-known consequences of changing a. It is found that Tc, for a fixed a, is typically increased as smaller alkali atoms are replaced by larger ones, except for very large a. Possible reasons for these results are discussed. Although smaller in size than the lattice parameter contribution, the chemical effect is not negligible and should be considered in future physical model developments.

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

PubMed

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 < 2) and depends on the charge of the ligand, owing to the ionic nature of the interactions. At the same time, the size of the cation is an important factor that influences the stability: very often, but not always (e.g., for sulfate), it follows the trend Li(+) > 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).

Microwave Heating of Metal Power Clusters

NASA Astrophysics Data System (ADS)

Rybakov, K. I.; Semenov, V. E.; Volkovskaya, I. I.

2018-01-01

The results of simulating the rapid microwave heating of spherical clusters of metal particles to the melting point are reported. In the simulation, the cluster is subjected to a plane electromagnetic wave. The cluster size is comparable to the wavelength; the perturbations of the field inside the cluster are accounted for within an effective medium approximation. It is shown that the time of heating in vacuum to the melting point does not exceed 1 s when the electric field strength in the incident wave is about 2 kV/cm at a frequency of 24 GHz or 5 kV/cm at a frequency of 2.45 GHz. The obtained results demonstrate feasibility of using rapid microwave heating for the spheroidization of metal particles with an objective to produce high-quality powders for additive manufacturing technologies.

Alkali-Resistant Mechanism of a Hollandite DeNOx Catalyst.

PubMed

Hu, Pingping; Huang, Zhiwei; Gu, Xiao; Xu, Fei; Gao, Jiayi; Wang, Yue; Chen, Yaxin; Tang, Xingfu

2015-06-02

A thorough understanding of the deactivation mechanism by alkalis is of great importance for rationally designing improved alkali-resistant deNOx catalysts, but a traditional ion-exchange mechanism cannot often accurately describe the nature of the deactivation, thus hampering the development of superior catalysts. Here, we establish a new exchange-coordination mechanism on the basis of the exhaustive study on the strong alkali resistance of a hollandite manganese oxide (HMO) catalyst. A combination of isothermal adsorption measurements of ammonia with X-ray absorption near-edge structure spectra and X-ray photoelectron spectra reveals that alkali metal ions first react with protons from Brønsted acid sites of HMO via the ion exchange. Synchrotron X-ray diffraction patterns and extended X-ray absorption fine structure spectra coupled with theoretical calculations demonstrate that the exchanged alkali metal ions are subsequently stabilized at size-suitable cavities in the HMO pores via a coordination model with an energy savings. This exchange-coordination mechanism not only gives a wholly convincing explanation for the intrinsic nature of the deactivation of the reported catalysts by alkalis but also provides a strategy for rationally designing improved alkali-resistant deNOx catalysts in general.

Alkali metal cation complexation by 1,3-alternate, mono-ionisable calix[4]arene-benzocrown-6 compounds

DOE PAGES

Surowiec, Malgorzata A.; Custelcean, Radu; Surowiec, Kazimierz; ...

2014-04-23

Alkali metal cation extraction behavior for two series of 1,3-alternate, mono-ionizable calix[4]arene-benzocrown-6 compounds is examined. In Series 1, the proton-ionizable group is a substituent on the benzo group of the polyether ring that directs it away from the crown ether cavity. In Series 2, the proton-ionizable group is attached to one para position in the calixarene framework, thus positioning it over the crown ether ring. Competitive solvent extraction of alkali metal cations from aqueous solutions into chloroform shows high Cs+ efficiency and selectivity. Single-species extraction pH profiles of Cs+ for Series 1 and 2 ligands with the same proton-ionizable groupmore » are very similar. Thus, association of Cs+ with the calixcrown ring is more important than the the proton-ionizable group’s position in relation to the crown ether cavity. Solid-state structures are presented for two unionized ligands from Series 2, as is a crystal containing two different ionized ligand–Cs+ complexes.« less

Calculating the thermodynamic properties of aqueous solutions of alkali metal carboxylates

NASA Astrophysics Data System (ADS)

Rudakov, A. M.; Sergievskii, V. V.; Zhukova, T. V.

2014-06-01

A modified Robinson-Stokes equation with terms that consider the formation of ionic hydrates and associates is used to describe thermodynamic properties of aqueous solutions of electrolytes. The model is used to describe data on the osmotic coefficients of aqueous solutions of alkali metal carboxylates, and to calculate the mean ionic activity coefficients of salts and excess Gibbs energies. The key contributions from ionic hydration and association to the nonideality of solutions is determined by analyzing the contributions of various factors. Relations that connect the hydration numbers of electrolytes with the parameters of the Pitzer-Mayorga equation and a modified Hückel equation are developed.

Effect of Graphene with Nanopores on Metal Clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Hu; Chen, Xianlang; Wang, Lei

Porous graphene, which is a novel type of defective graphene, shows excellent potential as a support material for metal clusters. In this work, the stability and electronic structures of metal clusters (Pd, Ir, Rh) supported on pristine graphene and graphene with different sizes of nanopore were investigated by first-principle density functional theory (DFT) calculations. Thereafter, CO adsorption and oxidation reaction on the Pd-graphene system were chosen to evaluate its catalytic performance. Graphene with nanopore can strongly stabilize the metal clusters and cause a substantial downshift of the d-band center of the metal clusters, thus decreasing CO adsorption. All binding energies,more » d-band centers, and adsorption energies show a linear change with the size of the nanopore: a bigger size of nanopore corresponds to a stronger metal clusters bond to the graphene, lower downshift of the d-band center, and weaker CO adsorption. By using a suitable size nanopore, supported Pd clusters on the graphene will have similar CO and O2 adsorption ability, thus leading to superior CO tolerance. The DFT calculated reaction energy barriers show that graphene with nanopore is a superior catalyst for CO oxidation reaction. These properties can play an important role in instructing graphene-supported metal catalyst preparation to prevent the diffusion or agglomeration of metal clusters and enhance catalytic performance. This work was supported by National Basic Research Program of China (973Program) (2013CB733501), the National Natural Science Foundation of China (NSFC-21176221, 21136001, 21101137, 21306169, and 91334013). D. Mei acknowledges the support from the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computational

Non-Adiabatic Atomic Transitions: Computational Cross Section Calculations of Alkali Metal-Noble Gas Collisions

DTIC Science & Technology

2011-09-01

there a one time transfer of prob- ability between Coriolis coupled states. One possible way to answer this question would be to literally create and... time -dependent numerical algorithm was developed using FORTRAN 90 to predict S-Matrix elements for alkali metal - noble gas (MNg) collisions. The...committee and the physics department for their time and effort to see me through the completion of my doctorate degree. Charlton D. Lewis, II v Table of

Probing the History of Galaxy Clusters with Metallicity and Entropy Measurements

NASA Astrophysics Data System (ADS)

Elkholy, Tamer Yohanna

Galaxy clusters are the largest gravitationally bound objects found today in our Universe. The gas they contain, the intra-cluster medium (ICM), is heated to temperatures in the approximate range of 1 to 10 keV, and thus emits X-ray radiation. Studying the ICM through the spatial and spectral analysis of its emission returns the richest information about both the overall cosmological context which governs the formation of clusters, as well as the physical processes occurring within. The aim of this thesis is to learn about the history of the physical processes that drive the evolution of galaxy clusters, through careful, spatially resolved measurements of their metallicity and entropy content. A sample of 45 nearby clusters observed with Chandra is analyzed to produce radial density, temperature, entropy and metallicity profiles. The entropy profiles are computed to larger radial extents than in previous Chandra analyses. The results of this analysis are made available to the scientific community in an electronic database. Comparing metallicity and entropy in the outskirts of clusters, we find no signature on the entropy profiles of the ensemble of supernovae that produced the observed metals. In the centers of clusters, we find that the metallicities of high-mass clusters are much less dispersed than those of low-mass clusters. A comparison of metallicity with the regularity of the X-ray emission morphology suggests that metallicities in low-mass clusters are more susceptible to increase from violent events such as mergers. We also find that the variation in the stellar-to-gas mass ratio as a function of cluster mass can explain the variation of central metallicity with cluster mass, only if we assume that there is a constant level of metallicity for clusters of all masses, above which the observed galaxies add more metals in proportion to their mass. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu)

3718-F Alkali Metal Treatment and Storage Facility Closure Plan

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

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; wastemore » characteristics; groundwater; closure strategy and performance standards; closure activities; postclosure; and references.« less

Development of processes for the production of solar grade silicon from halides and alkali metals

NASA Technical Reports Server (NTRS)

Dickson, C. R.; Gould, R. K.

1980-01-01

High temperature reactions of silicon halides with alkali metals for the production of solar grade silicon in volume at low cost were studied. Experiments were performed to evaluate product separation and collection processes, measure heat release parameters for scaling purposes, determine the effects of reactants and/or products on materials of reactor construction, and make preliminary engineering and economic analyses of a scaled-up process.

STAR CLUSTERS IN M31. II. OLD CLUSTER METALLICITIES AND AGES FROM HECTOSPEC DATA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caldwell, Nelson; Schiavon, Ricardo; Morrison, Heather

2011-02-15

We present new high signal-to-noise spectroscopic data on the M31 globular cluster (GC) system, obtained with the Hectospec multifiber spectrograph on the 6.5 m MMT. More than 300 clusters have been observed at a resolution of 5 A and with a median S/N of 75 per A, providing velocities with a median uncertainty of 6 km s{sup -1}. The primary focus of this paper is the determination of mean cluster metallicities, ages, and reddenings. Metallicities were estimated using a calibration of Lick indices with [Fe/H] provided by Galactic GCs. These match well the metallicities of 24 M31 clusters determined frommore » Hubble Space Telescope color-magnitude diagrams, the differences having an rms of 0.2 dex. The metallicity distribution is not generally bimodal, in strong distinction with the bimodal Galactic globular distribution. Rather, the M31 distribution shows a broad peak, centered at [Fe/H] = -1, possibly with minor peaks at [Fe/H] = -1.4, -0.7, and -0.2, suggesting that the cluster systems of M31 and the Milky Way had different formation histories. Ages for clusters with [Fe/H] > - 1 were determined using the automatic stellar population analysis program EZ{sub A}ges. We find no evidence for massive clusters in M31 with intermediate ages, those between 2 and 6 Gyr. Moreover, we find that the mean ages of the old GCs are remarkably constant over about a decade in metallicity (-0.95{approx}< [Fe/H] {approx}<0.0).« less

Preparation and Use of Alkali Metals (Li and Na) in Alumina and Silica Gel as Reagents in Organic Syntheses

NASA Astrophysics Data System (ADS)

Jalloh, Fatmata

This work describes the development of alkali metals (Li and Na) encapsulated in silica and alumina gel (SG and AG), and their applications in organic syntheses. The methods elucidated involved the thermal incorporation of these metals into the pores of SG and AG, serving as solid-state reagents. The encapsulation method/approach addresses the problems associated with the high reactivity of these metals that limit their synthetic utility in research laboratories, pharmaceutical, and manufacturing industries. These problems include their sensitivity to air and moisture, pyrophoricity, difficulty in handling, non-commercial availability, and instability of some of the organoalkali metals reagents. Herein, we describe the developments to synthesize alkali metal precursor (Li-AG) in solid form that offer safer organolithium reagents. This precursor reduces or eliminates the danger associated with the traditional handling of organolithium reagents stored in flammable organic solvents. The use of Li-AG to prepare and deliver organolithium reagents from organic halides and ethers, as needed especially for those that are commercially not available is put forward. In addition, exploration of additional applications of Na-SG and Na-AG reagents in the demethoxylation of Weinreb amides to secondary amines, and Bouveault-Blanc type reduction of amides to amines are described.

Interaction of Cu(+) with cytosine and formation of i-motif-like C-M(+)-C complexes: alkali versus coinage metals.

PubMed

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.

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

NASA Astrophysics Data System (ADS)

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.

Alkali-earth metal bridges formed in biofilm matrices regulate the uptake of fluoroquinolone antibiotics and protect against bacterial apoptosis.

PubMed

Kang, Fuxing; Wang, Qian; Shou, Weijun; Collins, Chris D; Gao, Yanzheng

2017-01-01

Bacterially extracellular biofilms play a critical role in relieving toxicity of fluoroquinolone antibiotic (FQA) pollutants, yet it is unclear whether antibiotic attack may be defused by a bacterial one-two punch strategy associated with metal-reinforced detoxification efficiency. Our findings help to assign functions to specific structural features of biofilms, as they strongly imply a molecularly regulated mechanism by which freely accessed alkali-earth metals in natural waters affect the cellular uptake of FQAs at the water-biofilm interface. Specifically, formation of alkali-earth-metal (Ca 2+ or Mg 2+ ) bridge between modeling ciprofloxacin and biofilms of Escherichia coli regulates the trans-biofilm transport rate of FQAs towards cells (135-nm-thick biofilm). As the addition of Ca 2+ and Mg 2+ (0-3.5 mmol/L, CIP: 1.25 μmol/L), the transport rates were reduced to 52.4% and 63.0%, respectively. Computational chemistry analysis further demonstrated a deprotonated carboxyl in the tryptophan residues of biofilms acted as a major bridge site, of which one side is a metal and the other is a metal girder jointly connected to the carboxyl and carbonyl of a FQA. The bacterial growth rate depends on the bridging energy at anchoring site, which underlines the environmental importance of metal bridge formed in biofilm matrices in bacterially antibiotic resistance. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

PubMed Central

Leven, Matthias; Neudörfl, Jörg M

2013-01-01

Summary 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. PMID:23400419

Embedded cluster metal-polymeric micro interface and process for producing the same

DOEpatents

Menezes, Marlon E.; Birnbaum, Howard K.; Robertson, Ian M.

2002-01-29

A micro interface between a polymeric layer and a metal layer includes isolated clusters of metal partially embedded in the polymeric layer. The exposed portion of the clusters is smaller than embedded portions, so that a cross section, taken parallel to the interface, of an exposed portion of an individual cluster is smaller than a cross section, taken parallel to the interface, of an embedded portion of the individual cluster. At least half, but not all of the height of a preferred spherical cluster is embedded. The metal layer is completed by a continuous layer of metal bonded to the exposed portions of the discontinuous clusters. The micro interface is formed by heating a polymeric layer to a temperature, near its glass transition temperature, sufficient to allow penetration of the layer by metal clusters, after isolated clusters have been deposited on the layer at lower temperatures. The layer is recooled after embedding, and a continuous metal layer is deposited upon the polymeric layer to bond with the discontinuous metal clusters.

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

NASA Astrophysics Data System (ADS)

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.

Heating rates in collisionally opaque alkali-metal atom traps: Role of secondary collisions

NASA Astrophysics Data System (ADS)

Beijerinck, H. C. W.

2000-12-01

Grazing collisions with background gas are the major cause of trap loss and trap heating in atom traps. To first order, these effects do not depend on the trap density. In collisionally opaque trapped atom clouds, however, scattered atoms with an energy E larger than the effective trap depth Eeff, which are destined to escape from the atom cloud, will have a finite probability for a secondary collision. This results in a contribution to the heating rate that depends on the column density of the trapped atoms, i.e., the product of density and characteristic size of the trap. For alkali-metal atom traps, secondary collisions are quite important due to the strong long-range interaction with like atoms. We derive a simple analytical expression for the secondary heating rate, showing a dependency proportional to E1/2eff. When extrapolating to a vanishing column density, only primary collisions with the background gas will contribute to the heating rate. This contribution is rather small, due to the weak long-range interaction of the usual background gas species in an ultrahigh-vacuum system-He, Ne, or Ar-with the trapped alkali-metal atoms. We conclude that the transition between trap-loss collisions and heating collisions is determined by a cutoff energy 200 μK<=Eeff<=400 μK, much smaller than the actual trap depth E in most magnetic traps. Atoms with an energy Eeffalkali-metal atoms Li through Cs as a function of the effective trap depth, the column density of the trap, and the species in the background gas. The predictions of our model are in good agreement with the experimental data of Myatt for heating rates in high-density 87Rb-atom magnetic traps at JILA, including the effect of the rf shield and the composition of the background gas. It is shown that collisions with atoms from the Oort

Topological Aspects of Infinite Metal Clusters and Superconductors.

DTIC Science & Technology

1987-08-11

tetrahedra. T chemical bonding topologies qf discrete octahedral metal clusters can be either edge- localized (e.g., MoX8L 6 4 derivatives), face- localized ...constructed from edge- localized metal polyhedra such as the Mo 6 octahedra in the ternary molybdenum chalcogenides (Chevrel phases) and Rh4 tetrahedra in the...chemical bonding topologies of discrete octahedral metal clusters can be either e4ge- localized (e.g., No X L 4+ derivatives), face- localized (e.g

Metal nanostructures: from clusters to nanocatalysis and sensors

NASA Astrophysics Data System (ADS)

Smirnov, B. M.

2017-12-01

The properties of metal clusters and nanostructures composed of them are reviewed. Various existing methods for the generation of intense beams of metal clusters and their subsequent conversion into nanostructures are compared. Processes of the flow of a buffer gas with active molecules through a nanostructure are analyzed as a basis of using nanostructures for catalytic applications. The propagation of an electric signal through a nanostructure is studied by analogy with a macroscopic metal. An analysis is given of how a nanostructure changes its resistance as active molecules attach to its surface and are converted into negative ions. These negative ions induce the formation of positively charged vacancies inside the metal conductor and attract the vacancies to together change the resistance of the metal nanostructure. The physical basis is considered for using metal clusters and nanostructures composed of them to create new materials in the form of a porous metal film on the surface of an object. The fundamentals of nanocatalysis are reviewed. Semiconductor conductometric sensors consisting of bound nanoscale grains or fibers acting as a conductor are compared with metal sensors conducting via a percolation cluster, a fractal fiber, or a bunch of interwoven nanofibers formed in superfluid helium. It is shown that sensors on the basis of metal nanostructures are characterized by a higher sensitivity than semiconductor ones, but are not selective. Measurements using metal sensors involve two stages, one of which measures to high precision the attachment rate of active molecules to the sensor conductor, and in the other one the surface of metal nanostructures is cleaned from the attached molecules using a gas discharge plasma (in particular, capillary discharge) with a subsequent chromatography analysis for products of cleaning.

Intracellular acidification-induced alkali metal cation/H+ exchange in human neutrophils

PubMed Central

1987-01-01

Pretreatment of isolated human neutrophils (resting pHi congruent to 7.25 at pHo 7.40) with 30 mM NH4Cl for 30 min leads to an intracellular acidification (pHi congruen to 6.60) when the NH4Cl prepulse is removed. Thereafter, in 140 mM Na+ medium, pHi recovers exponentially with time (initial rate, approximately 0.12 pH/min) to reach the normal resting pHi by approximately 20 min, a process that is accomplished mainly, if not exclusively, though an exchange of internal H+ for external Na+. This Na+/H+ countertransport is stimulated by external Na+ (Km congruent to 21 mM) and by external Li+ (Km congruent to 14 mM), though the maximal transport rate for Na+ is about twice that for Li+. Both Na+ and Li+ compete as substrates for the same translocation sites on the exchange carrier. Other alkali metal cations, such as K+, Rb+, or Cs+, do not promote pHi recovery, owing to an apparent lack of affinity for the carrier. The exchange system is unaffected by ouabain or furosemide, but can be competitively inhibited by the diuretic amiloride (Ki congruent to 8 microM). The influx of Na+ or Li+ is accompanied by an equivalent counter-reflux of H+, indicating a 1:1 stoichiometry for the exchange reaction, a finding consistent with the lack of voltage sensitivity (i.e., electroneutrality) of pHi recovery. These studies indicate that the predominant mechanism in human neutrophils for pHi regulation after intracellular acidification is an amiloride-sensitive alkali metal cation/H+ exchange that shares a number of important features with similar recovery processes in a variety of other mammalian cell types. PMID:3694176

Manipulating Light with Transition Metal Clusters, Organic Dyes, and Metal Organic Frameworks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogut, Serdar

The primary goals of our research program is to develop and apply state-of-the-art first-principles methods to predict electronic and optical properties of three systems of significant scientific and technological interest: transition metal clusters, organic dyes, and metal-organic frameworks. These systems offer great opportunities to manipulate light for a wide ranging list of energy-related scientific problems and applications. During this grant period, we focused our investigations on the development, implementation, and benchmarking of many-body Green’s function methods (GW approximation and the Bethe-Salpeter equation) to examine excited-state properties of transition metal/transition-metal-oxide clusters and organic molecules that comprise the building blocks of dyesmore » and metal-organic frameworks.« less

James C. McGroddy Prize Talk: Superconductivity in alkali-metal doped Carbon-60

NASA Astrophysics Data System (ADS)

Hebard, Arthur

2008-03-01

Carbon sixty (C60), which was first identified in 1985 in laser desorption experiments, is unquestionably an arrestingly beautiful molecule. The high symmetry of the 12 pentagonal and 20 hexagonal faces symmetrically arrayed in a soccer-ball like structure invites special attention and continues to stimulate animated speculation. The availability in 1990 of macroscopic amounts of purified C60 derived from carbon-arc produced soot allowed the growth and characterization of both bulk and thin-film samples. Crystalline C60 is a molecular solid held together by weak van der Waals forces. The fcc structure has a 74% packing fraction thus allowing ample opportunity (26% available volume) for the intercalation of foreign atoms into the interstitial spaces of the three dimensional host. This opportunity catalyzed much of the collaborative work amongst chemists, physicists and materials scientists at Bell Laboratories, and resulted in the discovery of superconductivity in alkali-metal doped C60 with transition temperatures (Tc) in the mid-30-kelvin range. In this talk I will review how the successes of this initial team effort stimulated a worldwide collaboration between experimentalists and theorists to understand the promise and potential of an entirely new class of superconductors containing only two elements, carbon and an intercalated alkali metal. Although the cuprates still hold the record for the highest Tc, there are still open scientific questions about the mechanism that gives rise to such unexpectedly high Tc's in the non-oxide carbon-based superconductors. The doped fullerenes have unusual attributes (e.g., narrow electronic bands, high disorder, anomalous energy scales, and a tantalizing proximity to a metal-insulator Mott transition), which challenge conventional thinking and at the same time provide useful insights into new directions for finding even higher Tc materials. The final chapter of the `soot to superconductivity' story has yet to be written.

Infrared Multiple Photon Dissociation Spectroscopy Of Metal Cluster-Adducts

NASA Astrophysics Data System (ADS)

Cox, D. M.; Kaldor, A.; Zakin, M. R.

1987-01-01

Recent development of the laser vaporization technique combined with mass-selective detection has made possible new studies of the fundamental chemical and physical properties of unsupported transition metal clusters as a function of the number of constituent atoms. A variety of experimental techniques have been developed in our laboratory to measure ionization threshold energies, magnetic moments, and gas phase reactivity of clusters. However, studies have so far been unable to determine the cluster structure or the chemical state of chemisorbed species on gas phase clusters. The application of infrared multiple photon dissociation IRMPD to obtain the IR absorption properties of metal cluster-adsorbate species in a molecular beam is described here. Specifically using a high power, pulsed CO2 laser as the infrared source, the IRMPD spectrum for methanol chemisorbed on small iron clusters is measured as a function of the number of both iron atoms and methanols in the complex for different methanol isotopes. Both the feasibility and potential utility of IRMPD for characterizing metal cluster-adsorbate interactions are demonstrated. The method is generally applicable to any cluster or cluster-adsorbate system dependent only upon the availability of appropriate high power infrared sources.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, R.M.; Nagasubramanian, G.; Khanna, S.K.

1986-08-01

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/submore » 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.« less

Neutral glycoconjugated amide-based calix[4]arenes: complexation of alkali metal cations in water.

PubMed

Cindro, Nikola; Požar, Josip; Barišić, Dajana; Bregović, Nikola; Pičuljan, Katarina; Tomaš, Renato; Frkanec, Leo; Tomišić, Vladislav

2018-02-07

Cation complexation in water presents a unique challenge in calixarene chemistry, mostly due to the fact that a vast majority of calixarene-based cation receptors is not soluble in water or their solubility has been achieved by introducing functionalities capable of (de)protonation. Such an approach inevitably involves the presence of counterions which compete with target cations for the calixarene binding site, and also rather often requires the use of ion-containing buffer solutions in order to control the pH. Herein we devised a new strategy towards the solution of this problem, based on introducing carbohydrate units at the lower or upper rim of calix[4]arenes which comprise efficient cation binding sites. In this context, we prepared neutral, water-soluble receptors with secondary or tertiary amide coordinating groups, and studied their complexation with alkali metal cations in aqueous and methanol (for the comparison purpose) solutions. Complexation thermodynamics was quantitatively characterized by UV spectrometry and isothermal titration calorimetry, revealing that one of the prepared tertiary amide derivatives is capable of remarkably efficient (log K ≈ 5) and selective binding of sodium cations among alkali metal cations in water. Given the ease of the synthetic procedure used, and thus the variety of accessible analogues, this study can serve as a platform for the development of reagents for diverse purposes in aqueous media.

Rare-gas impurities in alkali metals: Relation to optical absorption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meltzer, D.E.; Pinski, F.J.; Stocks, G.M.

1988-04-15

An investigation of the nature of rare-gas impurity potentials in alkali metals is performed. Results of calculations based on simple models are presented, which suggest the possibility of resonance phenomena. These could lead to widely varying values for the exponents which describe the shape of the optical-absorption spectrum at threshold in the Mahan--Nozieres--de Dominicis theory. Detailed numerical calculations are then performed with the Korringa-Kohn-Rostoker coherent-potential-approximation method. The results of these highly realistic calculations show no evidence for the resonance phenomena, and lead to predictions for the shape of the spectra which are in contradiction to observations. Absorption and emission spectramore » are calculated for two of the systems studied, and their relation to experimental data is discussed.« less

Energetics of charged metal clusters containing vacancies

NASA Astrophysics Data System (ADS)

Pogosov, Valentin V.; Reva, Vitalii I.

2018-01-01

We study theoretically large metal clusters containing vacancies. We propose an approach, which combines the Kohn-Sham results for monovacancy in a bulk of metal and analytical expansions in small parameters cv (relative concentration of vacancies) and RN,v -1, RN ,v being cluster radii. We obtain expressions of the ionization potential and electron affinity in the form of corrections to electron work function, which require only the characteristics of 3D defect-free metal. The Kohn-Sham method is used to calculate the electron profiles, ionization potential, electron affinity, electrical capacitance; dissociation, cohesion, and monovacancy-formation energies of the small perfect clusters NaN, MgN, AlN (N ≤ 270) and the clusters containing a monovacancy (N ≥ 12) in the stabilized-jellium model. The quantum-sized dependences for monovacancy-formation energies are calculated for the Schottky scenario and the "bubble blowing" scenario, and their asymptotic behavior is also determined. It is shown that the asymptotical behaviors of size dependences for these two mechanisms differ from each other and weakly depend on the number of atoms in the cluster. The contribution of monovacancy to energetics of charged clusters and the size dependences of their characteristics and asymptotics are discussed. It is shown that the difference between the characteristics for the neutral and charged clusters is entirely determined by size dependences of ionization potential and electron affinity. Obtained analytical dependences may be useful for the analysis of the results of photoionization experiments and for the estimation of the size dependences of the vacancy concentration including the vicinity of the melting point.

Correspondence between ion-cluster and bulk thermodynamics: on the validity of the cluster pair approximation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vlcek, Lukas; Chialvo, Ariel; Simonson, J Michael

2013-01-01

Molecular models and experimental estimates based on the cluster pair approximation (CPA) provide inconsistent predictions of absolute single-ion hydration properties. To understand the origin of this discrepancy we used molecular simulations to study the transition between hydration of alkali metal and halide ions in small aqueous clusters and bulk water. The results demonstrate that the assumptions underlying the CPA are not generally valid as a result of a significant shift in the ion hydration free energies (~15 kJ/mol) and enthalpies (~47 kJ/mol) in the intermediate range of cluster sizes. When this effect is accounted for, the systematic differences between modelsmore » and experimental predictions disappear, and the value of absolute proton hydration enthalpy based on the CPA gets in closer agreement with other estimates.« less

A Quantitative Tunneling/Desorption Model for the Exchange Current at the Porous Electrode/Beta - Alumina/Alkali Metal Gas Three Phase Zone at 700-1300K

NASA Technical Reports Server (NTRS)

Williams, R. M.; Ryan, M. A.; Saipetch, C.; LeDuc, H. G.

1996-01-01

The exchange current observed at porous metal electrodes on sodium or potassium beta -alumina solid electrolytes in alkali metal vapor is quantitatively modeled with a multi-step process with good agreement with experimental results.

Alkali-ion microsolvation with benzene molecules.

PubMed

Marques, J M C; Llanio-Trujillo, J L; Albertí, M; Aguilar, A; Pirani, F

2012-05-24

The target of this investigation is to characterize by a recently developed methodology, the main features of the first solvation shells of alkaline ions in nonpolar environments due to aromatic rings, which is of crucial relevance to understand the selectivity of several biochemical phenomena. We employ an evolutionary algorithm to obtain putative global minima of clusters formed with alkali-ions (M(+)) solvated with n benzene (Bz) molecules, i.e., M(+)-(Bz)(n). The global intermolecular interaction has been decomposed in Bz-Bz and in M(+)-Bz contributions, using a potential model based on different decompositions of the molecular polarizability of benzene. Specifically, we have studied the microsolvation of Na(+), K(+), and Cs(+) with benzene molecules. Microsolvation clusters up to n = 21 benzene molecules are involved in this work and the achieved global minimum structures are reported and discussed in detail. We observe that the number of benzene molecules allocated in the first solvation shell increases with the size of the cation, showing three molecules for Na(+) and four for both K(+) and Cs(+). The structure of this solvation shell keeps approximately unchanged as more benzene molecules are added to the cluster, which is independent of the ion. Particularly stable structures, so-called "magic numbers", arise for various nuclearities of the three alkali-ions. Strong "magic numbers" appear at n = 2, 3, and 4 for Na(+), K(+), and Cs(+), respectively. In addition, another set of weaker "magic numbers" (three per alkali-ion) are reported for larger nuclearities.

Monitoring of photoluminescence decay by alkali and alkaline earth metal cations using a photoluminescent bolaamphiphile self-assembly as an optical probe.

PubMed

Kim, Sunhyung; Kwak, Jinyoung; Lee, Sang-Yup

2014-05-01

Photoluminescence (PL) decay induced by the displacement of an ionic fluorescence component, Tb(3+), with alkali and alkaline earth metal cations was investigated using photoluminescent spherical self-assemblies as optical probes. The photoluminescent spherical self-assembly was prepared by the self-organization of a tyrosine-containing bolaamphiphile molecule with a photosensitizer and Tb(3+) ion. The lanthanide ion, Tb(3+), electrically bound to the carboxyl group of the bolaamphiphile molecule, was displaced by alkali and alkaline earth metal cations that had stronger electrophilicity. The PL of the self-assembly decayed remarkably due to the substitution of lanthanide ions with alkali and alkaline earth metal cations. The PL decay showed a positive correlation with cation concentration and was sensitive to the cation valency. Generally, the PL decay was enhanced by the electrophilicity of the cations. However, Ca(2+) showed greater PL decay than Mg(2+) because Ca(2+) could create various complexes with the carboxyl groups of the bolaamphiphile molecule. Microscopic and spectroscopic investigations were conducted to study the photon energy transfer and displacement of Tb(3+) by the cation exchange. This study demonstrated that the PL decay by the displacement of the ionic fluorescent compound was applied to the detection of various cations in aqueous media and is applicable to the development of future optical sensors. Copyright © 2014 Elsevier B.V. All rights reserved.

Cation and anion dependence of stable geometries and stabilization energies of alkali metal cation complexes with FSA(-), FTA(-), and TFSA(-) anions: relationship with physicochemical properties of molten salts.

PubMed

Tsuzuki, Seiji; Kubota, Keigo; Matsumoto, Hajime

2013-12-19

Stable geometries and stabilization energies (Eform) of the alkali metal complexes with bis(fluorosulfonyl)amide, (fluorosulfonyl)(trifluoromethylslufonyl)amide and bis(trifluoromethylsulfonyl)amide (FSA(-), FTA(-) and TFSA(-)) were studied by ab initio molecular orbital calculations. The FSA(-) complexes prefer the bidentate structures in which two oxygen atoms of two SO2 groups have contact with the metal cation. The FTA(-) and TFSA(-) complexes with Li(+) and Na(+) prefer the bidentate structures, while the FTA(-) and TFSA(-) complexes with Cs(+) prefer tridentate structures in which the metal cation has contact with two oxygen atoms of an SO2 group and one oxygen atom of another SO2 group. The two structures are nearly isoenergetic in the FTA(-) and TFSA(-) complexes with K(+) and Rb(+). The magnitude of Eform depends on the alkali metal cation significantly. The Eform calculated for the most stable TFSA(-) complexes with Li(+), Na(+), K(+), Rb(+) and Cs(+) cations at the MP2/6-311G** level are -137.2, -110.5, -101.1, -89.6, and -84.1 kcal/mol, respectively. The viscosity and ionic conductivity of the alkali TFSA molten salts have strong correlation with the magnitude of the attraction. The viscosity increases and the ionic conductivity decreases with the increase of the attraction. The melting points of the alkali TFSA and alkali BETA molten salts also have correlation with the magnitude of the Eform, which strongly suggests that the magnitude of the attraction play important roles in determining the melting points of these molten salts. The anion dependence of the Eform calculated for the complexes is small (less than 2.9 kcal/mol). This shows that the magnitude of the attraction is not the cause of the low melting points of alkali FTA molten salts compared with those of corresponding alkali TFSA molten salts. The electrostatic interactions are the major source of the attraction in the complexes. The electrostatic energies for the most stable TFSA

Effect of charging on silicene with alkali metal atom adsorption

NASA Astrophysics Data System (ADS)

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.

Influence of reactive gas admixture on transition metal cluster nucleation in a gas aggregation cluster source

NASA Astrophysics Data System (ADS)

Peter, Tilo; Polonskyi, Oleksandr; Gojdka, Björn; Mohammad Ahadi, Amir; Strunskus, Thomas; Zaporojtchenko, Vladimir; Biederman, Hynek; Faupel, Franz

2012-12-01

We quantitatively assessed the influence of reactive gases on the formation processes of transition metal clusters in a gas aggregation cluster source. A cluster source based on a 2 in. magnetron is used to study the production rate of titanium and cobalt clusters. Argon served as working gas for the DC magnetron discharge, and a small amount of reactive gas (oxygen and nitrogen) is added to promote reactive cluster formation. We found that the cluster production rate depends strongly on the reactive gas concentration for very small amounts of reactive gas (less than 0.1% of total working gas), and no cluster formation takes place in the absence of reactive species. The influence of discharge power, reactive gas concentration, and working gas pressure are investigated using a quartz micro balance in a time resolved manner. The strong influence of reactive gas is explained by a more efficient formation of nucleation seeds for metal-oxide or nitride than for pure metal.

Probing Globular Cluster Formation in Low Metallicity Dwarf Galaxies

NASA Astrophysics Data System (ADS)

Johnson, Kelsey E.; Hunt, Leslie K.; Reines, Amy E.

2008-12-01

The ubiquitous presence of globular clusters around massive galaxies today suggests that these extreme star clusters must have been formed prolifically in the earlier universe in low-metallicity galaxies. Numerous adolescent and massive star clusters are already known to be present in a variety of galaxies in the local universe; however most of these systems have metallicities of 12 + log(O/H) > 8, and are thus not representative of the galaxies in which today's ancient globular clusters were formed. In order to better understand the formation and evolution of these massive clusters in environments with few heavy elements, we have targeted several low-metallicity dwarf galaxies with radio observations, searching for newly-formed massive star clusters still embedded in their birth material. The galaxies in this initial study are HS 0822+3542, UGC 4483, Pox 186, and SBS 0335-052, all of which have metallicities of 12 + log(O/H) < 7.75. While no thermal radio sources, indicative of natal massive star clusters, are found in three of the four galaxies, SBS 0335-052 hosts two such objects, which are incredibly luminous. The radio spectral energy distributions of these intense star-forming regions in SBS 0335-052 suggest the presence of ~12,000 equivalent O-type stars, and the implied star formation rate is nearing the maximum starburst intensity limit.

H-1 NMR study of ternary ammonia-alkali metal-graphite intercalation compounds

NASA Technical Reports Server (NTRS)

Tsang, T.; Fronko, R. M.; Resing, H. A.; Qian, X. W.; Solin, S. A.

1987-01-01

For the first-stage ternary ammonia-alkali metal-graphite intercalation compounds M(NH3)(x)C24(x of about 4, M = K, Rb, Cs), three sets of triplet H-1 NMR spectral lines have been observed at various temperatures and orientations due to the H-1 - H-1 and N-14 - H-1 dipolar interactions. The structures of these compounds have been inferred as mobile (liquid-like) intercalant layers of planar M(NH3)4 ions in between the carbon layers. For the intercalated ammonia molecules, the potential barrier is about 0.2 eV and the molecular geometry is very close to the free NH3 in gas phase.

Structural and optical characterization of Er-alkali-metals codoped MgO nanoparticles synthesized by solution combustion route

NASA Astrophysics Data System (ADS)

Sivasankari, J.; Selvakumar Sellaiyan, S.; Sankar, S.; Devi, L. Vimala; Sivaji, K.

2017-01-01

Pure MgO, rare-earth (Er) doped MgO (MgO:Er), and alkali metal ions (Li, Na and K) co-doped MgO:Er [i.e. MgO: Er+X (X=Li, Na, and K)] nanopowders were synthesized by solution combustion method and characterized. The XRD analysis reveals the cubic structure and the substitution of dopants and co-dopants in MgO. Annealing at 800 °C, increases the sizes of nano-crystallites of all samples appreciably, indicating the grain growth and the improvement in crystallinity of all the samples. Increase in lattice parameter, d spacing and band gap were observed after annealing. Structural and morphological analysis using scanning electron microscope (SEM) and transmission electron microscope (TEM) studies has shown that the samples contain structures like agglomerated clusters. FT-IR spectra confirm the stretching mode of hydroxyl groups, carbonate and presence of MgO bonding. The characteristic wavelength ranging from 2600 cm-1 to 3000 cm-1 were assigned to transition of 4S3/2→4I13/2 and 4I11/2→4I15/2 of Er3+.

Alkali metals levels in the human brain tissue: Anatomical region differences and age-related changes.

PubMed

Ramos, Patrícia; Santos, Agostinho; Pinto, Edgar; Pinto, Nair Rosas; Mendes, Ricardo; Magalhães, Teresa; Almeida, Agostinho

2016-12-01

The link between trace elements imbalances (both "toxic" and "essential") in the human brain and neurodegenerative disease has been subject of extensive research. More recently, some studies have highlighted the potential role of the homeostasis deregulation of alkali metals in specific brain regions as key factor in the pathogenesis of neurodegenerative diseases such as multiple sclerosis and Alzheimer's disease. Using flame atomic emission spectrometry and inductively coupled plasma-mass spectrometry after microwave-assisted acid digestion of the samples, alkali metals (Na, K, Li, Rb and Cs) were determined in 14 different areas of the human brain (frontal cortex, superior and middle temporal gyri, caudate nucleus, putamen, globus pallidus, cingulated gyrus, hippocampus, inferior parietal lobule, visual cortex of the occipital lobe, midbrain, pons, medulla and cerebellum) of adult individuals (n=42; 71±12, range: 50-101 years old) with no known history and evidence of neurodegenerative, neurological or psychiatric disorder. Potassium was found as the most abundant alkali metal, followed by Na, Rb, Cs and Li. Lithium, K and Cs distribution showed to be quite heterogeneous. On the contrary, Rb and Na appeared quite homogeneously distributed within the human brain tissue. The lowest levels of Na, K, Rb and Li were found in the brainstem (midbrain, medulla and pons) and cerebellum, while the lowest levels of Cs were found in the frontal cortex. The highest levels of K (mean±sd; range 15.5±2.5; 8.9-21.8mg/g) Rb (17.2±6.1; 3.9-32.4μg/g and Cs (83.4±48.6; 17.3-220.5ng/g) were found in putamen. The highest levels of Na and Li were found in the frontal cortex (11.6±2.4; 6.6-17.1mg/g) and caudate nucleus (7.6±4.6 2.2-21.3ng/g), respectively. Although K, Cs and Li levels appear to remain largely unchanged with age, some age-related changes were observed for Na and Rb levels in particular brain regions (namely in the hippocampus). Copyright © 2016 Elsevier GmbH. All

Alkali metal thermal to electric conversion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sievers, R.K.; Ivanenok, J.F. III; Hunt, T.K.

1995-10-01

With potential efficiencies of up to 40%, AMTEC technology offers reliability and fuel flexibility for aerospace and ground power applications. Alkali Metal Thermal to Electric Conversion (AMTEC), a direct power-conversion technology, is emerging from the laboratory for use in a number of applications that require lightweight, long-running, efficient power systems. AMTEC is compatible with many heat and fuel sources, and it offers the reliability of direct (that is, no moving parts) thermal to electric conversion. These features make it an attractive technology for small spacecraft used in deep-space missions and for ground power applications, such as self-powered furnaces and themore » generators used in recreational vehicles. Researchers at Ford Scientific Laboratories, in Dearborn, Michigan, first conceived AMTEC technology in 1968 when they identified and patented a converter known as the sodium heat engine. This heat engine was based on the unique properties of {beta}-alumina solid electrolyte (BASE), a ceramic material that is an excellent sodium ion conductor but a poor electronic conductor. BASE was used to form a structural barrier across which a sodium concentration gradient could be produced from thermal energy. The engine provided a way to isothermally expand sodium through the BASE concentration gradient without moving mechanical components. Measured power density and calculated peak efficiencies were impressive, which led to funding from the Department of Energy for important material technology development.« less

Thermally stable solids based on endohedrally doped ZnS clusters.

PubMed

Matxain, Jon M; Piris, Mario; Lopez, Xabier; Ugalde, Jesus M

2009-01-01

The existence of inorganic, hollow, fullerene-like ZnS clusters has been theoretically predicted and then recently confirmed experimentally. These clusters were observed to trap alkali metals and halogens because the ionization energies (IE) of alkali metals are very similar to the electron affinities (EA) of halogens. This opens the possibility of forming molecular solids composed of these fullerene building blocks because the energy released due to the difference between the IE and EA would be very small. Herein we have focused on assembling bare Zn(12)S(12) and endohedral X@Zn(12)S(12)-Y@Zn(12)S(12) dimers (X = Na, K; Y = Cl, Br) by considering the square-faces-square orientation of every two adjacent clusters, which leads to a fcc cubic crystal structure in the solid. The structures were fully optimized in all cases, and their thermal stability was confirmed by ab initio thermal molecular dynamics calculations. The optimum lattice parameter of the solids was found to be around 13.8 A, which corresponds to distances of about 2.5 A between monomers, which is typical of covalent Zn-S bonds. The resulting solids are nanoporous materials similar to B(12)N(12). Due to their nanoporous structure, these zeolite-shaped solids could be used in heterogeneous catalysis and as storage materials and molecular sieves.

Color-magnitude diagrams for six metal-rich, low-latitude globular clusters

NASA Technical Reports Server (NTRS)

Armandroff, Taft E.

1988-01-01

Colors and magnitudes for stars on CCD frames for six metal-rich, low-latitude, previously unstudied globular clusters and one well-studied, metal-rich cluster (47 Tuc) have been derived and color-magnitude diagrams have been constructed. The photometry for stars in 47 Tuc are in good agreement with previous studies, while the V magnitudes of the horizontal-branch stars in the six program clusters do not agree with estimates based on secondary methods. The distances to these clusters are different from prior estimates. Redding values are derived for each program cluster. The horizontal branches of the program clusters all appear to lie entirely redwards of the red edge of the instability strip, as is normal for their metallicities.

Spectroscopic studies of transition metal ions in molten alkali metal carboxylates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maroni, V.A.; Maciejewski, M.L.

Electronic absorption and C-13 NMR spectroscopic studies were carried out to investigate the structure of (i) alkali metal formate (Fm) and acetate (Ac) eutectic melts and (ii) solutions of 3d transition metal (TM) cations in these eutectics. Measurements were made over the temperature range 90..-->..190/sup 0/C. The most stable oxidation states of the individual TMs in the Fm and Ac eutectics were: Ti/sup 3 +/, V/sup 3 +/, VO/sup 2 +/, Cr/sup 3 +/, Mn/sup 2 +/, Fe/sup 2 +/, Co/sup 2 +/, Ni/sup 2 +/, and Cu/sup 2 +/. The ligand field absorption spectra obtained in these carboxylate meltsmore » bore a consistent resemblance to the spectra of these same cations in aqueous media, but the absorptivities were generally higher than are observed for the hexaquo complexes. The results were interpreted in terms of the existence of bidentate coordination in some (if not all) cases, leading to noncentrosymmetric complexation geometries. Key results of the NMR measurements included the apparent observation of two different carboxylate anion environments in Ni/sup 2 +/ solutions. C-13 spin-lattice relaxation of the carboxylate anions in the TM-free eutectics was found to be controlled by dipolar coupling to another nucleus. In the TM-containing solutions, the spin-lattice relaxation times were reduced by a factor of 10 to 1000, evidencing the expected shift to electron-nuclear dipolar coupling. Activation energies for viscous flow derived from the spin-lattice relaxation measurements on TM-free melts were in the 10..-->..11 kcal/mol range, reflecting the highly ordered, glassy nature of the eutectics studied.« less

Carbonation of metal silicates for long-term CO2 sequestration

DOEpatents

Blencoe, James G; Palmer, Donald A; Anovitz, Lawrence M; Beard, James S

2014-03-18

In a preferred embodiment, the invention relates to a process of sequestering carbon dioxide. The process comprises the steps of: (a) reacting a metal silicate with a caustic alkali-metal hydroxide to produce a hydroxide of the metal formerly contained in the silicate; (b) reacting carbon dioxide with at least one of a caustic alkali-metal hydroxide and an alkali-metal silicate to produce at least one of an alkali-metal carbonate and an alkali-metal bicarbonate; and (c) reacting the metal hydroxide product of step (a) with at least one of the alkali-metal carbonate and the alkali-metal bicarbonate produced in step (b) to produce a carbonate of the metal formerly contained in the metal silicate of step (a).

Low work function, stable compound clusters and generation process

DOEpatents

Dinh, Long N.; Balooch, Mehdi; Schildbach, Marcus A.; Hamza, Alex V.; McLean, II, William

2000-01-01

Low work function, stable compound clusters are generated by co-evaporation of a solid semiconductor (i.e., Si) and alkali metal (i.e., Cs) elements in an oxygen environment. The compound clusters are easily patterned during deposition on substrate surfaces using a conventional photo-resist technique. The cluster size distribution is narrow, with a peak range of angstroms to nanometers depending on the oxygen pressure and the Si source temperature. Tests have shown that compound clusters when deposited on a carbon substrate contain the desired low work function property and are stable up to 600.degree. C. Using the patterned cluster containing plate as a cathode baseplate and a faceplate covered with phosphor as an anode, one can apply a positive bias to the faceplate to easily extract electrons and obtain illumination.

Metal Sulfide Cluster Complexes and their Biogeochemical Importance in the Environment

NASA Astrophysics Data System (ADS)

Luther, George W.; Rickard, David T.

2005-10-01

Aqueous clusters of FeS, ZnS and CuS constitute a major fraction of the dissolved metal load in anoxic oceanic, sedimentary, freshwater and deep ocean vent environments. Their ubiquity explains how metals are transported in anoxic environmental systems. Thermodynamic and kinetic considerations show that they have high stability in oxic aqueous environments, and are also a significant fraction of the total metal load in oxic river waters. Molecular modeling indicates that the clusters are very similar to the basic structural elements of the first condensed phase forming from aqueous solutions in the Fe-S, Zn-S and Cu-S systems. The structure of the first condensed phase is determined by the structure of the cluster in solution. This provides an alternative explanation of Ostwald's Rule, where the most soluble, metastable phases form before the stable phases. For example, in the case of FeS, we showed that the first condensed phase is nanoparticulate, metastable mackinawite with a particle size of 2 nm consisting of about 150 FeS subunits, representing the end of a continuum between aqueous FeS clusters and condensed material. These metal sulfide clusters and nanoparticles are significant in biogeochemistry. Metal sulfide clusters reduce sulfide and metal toxicity and help drive ecology. FeS cluster formation drives vent ecology and AgS cluster formation detoxifies Ag in Daphnia magna neonates. We also note a new reaction between FeS and DNA and discuss the potential role of FeS clusters in denaturing DNA.

Metal-atom Interactions and Clustering in Organic Semiconductor Systems

NASA Astrophysics Data System (ADS)

Tomita, Yoko; Park, Tea-uk; Nakayama, Takashi

2017-07-01

The interatomic interactions and clustering of metal atoms have been studied by first-principles calculations in graphene, pentacene, and polyacetylene as representative organic systems. It is shown that long-range repulsive Coulomb interaction appears between metal atoms with small electronegativity such as Al due to their ionization on host organic molecules, inducing their scattered distribution in organic systems. On the other hand, metal atoms with large electronegativity such as Au are weakly bonded to organic molecules, easily diffuse in molecular solids, and prefer to combine with each other owing to their short-range strong metallic-bonding interaction, promoting metal cluster generation in organic systems.

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

PubMed

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.

Spin-driven structural effects in alkali doped (4)He clusters from quantum calculations.

PubMed

Bovino, S; Coccia, E; Bodo, E; Lopez-Durán, D; Gianturco, F A

2009-06-14

In this paper, we carry out variational Monte Carlo and diffusion Monte Carlo (DMC) calculations for Li(2)((1)Sigma(g) (+))((4)He)(N) and Li(2)((3)Sigma(u) (+))((4)He)(N) with N up to 30 and discuss in detail the results of our computations. After a comparison between our DMC energies with the "exact" discrete variable representation values for the species with one (4)He, in order to test the quality of our computations at 0 K, we analyze the structural features of the whole range of doped clusters. We find that both species reside on the droplet surface, but that their orientation is spin driven, i.e., the singlet molecule is perpendicular and the triplet one is parallel to the droplet's surface. We have also computed quantum vibrational relaxation rates for both dimers in collision with a single (4)He and we find them to differ by orders of magnitude at the estimated surface temperature. Our results therefore confirm the findings from a great number of experimental data present in the current literature and provide one of the first attempts at giving an accurate, fully quantum picture for the nanoscopic properties of alkali dimers in (4)He clusters.

Metal Hydride and Alkali Halide Opacities in Extrasolar Giant Planets and Cool Stellar Atmospheres

NASA Technical Reports Server (NTRS)

Weck, Philippe F.; Stancil, Phillip C.; Kirby, Kate; Schweitzer, Andreas; Hauschildt, Peter H.

2006-01-01

The lack of accurate and complete molecular line and continuum opacity data has been a serious limitation to developing atmospheric models of cool stars and Extrasolar Giant Planets (EGPs). We report our recent calculations of molecular opacities resulting from the presence of metal hydrides and alkali halides. The resulting data have been included in the PHOENIX stellar atmosphere code (Hauschildt & Baron 1999). The new models, calculated using spherical geometry for all gravities considered, also incorporate our latest database of nearly 670 million molecular lines, and updated equations of state.

Theoretical research program to study transition metal trimers and embedded clusters

NASA Technical Reports Server (NTRS)

Walch, S. P.

1984-01-01

Small transition metal clusters were studied at a high level of approximation, including all the valence electrons in the calculation and extensive electron correlation, in order to understand the electronic structure of these small metal clusters. By comparison of dimers, trimers, and possibly higher clusters, the information obtained was used to provide insights into the electronic structure of bulk transition metals. Small metal clusters are currently of considerable experimental interest and some information is becomming available both from matrix electron spin resonance studies and from gas phase spectroscopy. Collaboration between theorists and experimentalists is thus expected to be especially profitable at this time since there is some experimental information which can serve to guide the theoretical work.

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

NASA Astrophysics Data System (ADS)

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.

Unified mechanism of alkali and alkaline earth catalyzed gasification reactions of carbon by CO2 and H2O

USGS Publications Warehouse

Chen, S.G.; Yang, R.T.

1997-01-01

From molecular orbital calculations, a unified mechanism is proposed for the gasification reactions of graphite by CO2 and H2O, both uncatalyzed and catalyzed by alkali and alkaline earth catalysts. In this mechanism, there are two types of oxygen intermediates that are bonded to the active edge carbon atoms: an in-plane semiquinone type, Cf(O), and an off-plane oxygen bonded to two saturated carbon atoms that are adjacent to the semiquinone species, C(O)Cf(O). The rate-limiting step is the decomposition of these intermediates by breaking the C-C bonds that are connected to Cf(O). A new rate equation is derived for the uncatalyzed reactions, and that for the catalyzed reactions is readily available from the proposed mechanism. The proposed mechanism can account for several unresolved experimental observations: TPD and TK (transient kinetics) desorption results of the catalyzed systems, the similar activation energies for the uncatalyzed and catalyzed reactions, and the relative activities of the alkali and alkaline earth elements. The net charge of the edge carbon active site is substantially changed by gaining electron density from the alkali or alkaline earth element (by forming C-O-M, where M stands for metal). The relative catalytic activities of these elements can be correlated with their abilities of donating electrons and changing the net charge of the edge carbon atom. As shown previously (Chen, S. G.; Yang, R. T. J. Catal. 1993, 141, 102), only clusters of the alkali compounds are active. This derives from the ability of the clusters to dissociate CO2 and H2O to form O atoms and the mobility of the dissociated O atoms facilitated by the clusters.

The uniformity and time-invariance of the intra-cluster metal distribution in galaxy clusters from the IllustrisTNG simulations

NASA Astrophysics Data System (ADS)

Vogelsberger, Mark; Marinacci, Federico; Torrey, Paul; Genel, Shy; Springel, Volker; Weinberger, Rainer; Pakmor, Rüdiger; Hernquist, Lars; Naiman, Jill; Pillepich, Annalisa; Nelson, Dylan

2018-02-01

The distribution of metals in the intra-cluster medium (ICM) encodes important information about the enrichment history and formation of galaxy clusters. Here, we explore the metal content of clusters in IllustrisTNG - a new suite of galaxy formation simulations building on the Illustris project. Our cluster sample contains 20 objects in TNG100 - a ˜(100 Mpc)3 volume simulation with 2 × 18203 resolution elements, and 370 objects in TNG300 - a ˜(300 Mpc)3 volume simulation with 2 × 25003 resolution elements. The z = 0 metallicity profiles agree with observations, and the enrichment history is consistent with observational data going beyond z ˜ 1, showing nearly no metallicity evolution. The abundance profiles vary only minimally within the cluster samples, especially in the outskirts with a relative scatter of ˜ 15 per cent. The average metallicity profile flattens towards the centre, where we find a logarithmic slope of -0.1 compared to -0.5 in the outskirts. Cool core clusters have more centrally peaked metallicity profiles (˜0.8 solar) compared to non-cool core systems (˜0.5 solar), similar to observational trends. Si/Fe and O/Fe radial profiles follow positive gradients. The outer abundance profiles do not evolve below z ˜ 2, whereas the inner profiles flatten towards z = 0. More than ˜ 80 per cent of the metals in the ICM have been accreted from the proto-cluster environment, which has been enriched to ˜0.1 solar already at z ˜ 2. We conclude that the intra-cluster metal distribution is uniform among our cluster sample, nearly time-invariant in the outskirts for more than 10 Gyr, and forms through a universal enrichment history.

Electrophobic interaction induced impurity clustering in metals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Hong-Bo; Wang, Jin-Long; Jiang, W.

2016-10-01

We introduce the concept of electrophobic interaction, analogous to hydrophobic interaction, for describing the behavior of impurity atoms in a metal, a 'solvent of electrons'. We demonstrate that there exists a form of electrophobic interaction between impurities with closed electron shell structure, which governs their dissolution behavior in a metal. Using He, Be and Ar as examples, we predict by first-principles calculations that the electrophobic interaction drives He, Be or Ar to form a close-packed cluster with a clustering energy that follows a universal power-law scaling with the number of atoms (N) dissolved in a free electron gas, as wellmore » as W or Al lattice, as Ec is proportional to (N2/3-N). This new concept unifies the explanation for a series of experimental observations of close-packed inert-gas bubble formation in metals, and significantly advances our fundamental understanding and capacity to predict the solute behavior of impurities in metals, a useful contribution to be considered in future material design of metals for nuclear, metallurgical, and energy applications.« less

Variable Stars In the Unusual, Metal-Rich Globular Cluster

NASA Technical Reports Server (NTRS)

Pritzl, Barton J.; Smith, Horace A.; Catelan, Marcio; Sweigart, Allen V.; Oegerle, William R. (Technical Monitor)

2002-01-01

We have undertaken a search for variable stars in the metal-rich globular cluster NGC 6388 using time-series BV photometry. Twenty-eight new variables were found in this survey, increasing the total number of variables found near NGC 6388 to approx. 57. A significant number of the variables are RR Lyrae (approx. 14), most of which are probable cluster members. The periods of the fundamental mode RR Lyrae are shown to be unusually long compared to metal-rich field stars. The existence of these long period RRab stars suggests that the horizontal branch of NGC 6388 is unusually bright. This implies that the metallicity-luminosity relationship for RR Lyrae stars is not universal if the RR Lyrae in NGC 6388 are indeed metal-rich. We consider the alternative possibility that the stars in NGC 6388 may span a range in [Fe/H]. Four candidate Population II Cepheids were also found. If they are members of the cluster, NGC 6388 would be the most metal-rich globular cluster to contain Population II Cepheids. The mean V magnitude of the RR Lyrae is found to be 16.85 +/- 0.05 resulting in a distance of 9.0 to 10.3 kpc, for a range of assumed values of (M(sub V)) for RR Lyrae. We determine the reddening of the cluster to be E(B - V) = 0.40 +/- 0.03 mag, with differential reddening across the face of the cluster. We discuss the difficulty in determining the Oosterhoff classification of NGC 6388 and NGC 6441 due to the unusual nature of their RR Lyrae, and address evolutionary constraints on a recent suggestion that they are of Oosterhoff type II.

Dispersed metal cluster catalysts by design. Synthesis, characterization, structure, and performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arslan, Ilke; Dixon, David A.; Gates, Bruce C.

2015-09-30

To understand the class of metal cluster catalysts better and to lay a foundation for the prediction of properties leading to improved catalysts, we have synthesized metal catalysts with well-defined structures and varied the cluster structures and compositions systematically—including the ligands bonded to the metals. These ligands include supports and bulky organics that are being tuned to control both the electron transfer to or from the metal and the accessibility of reactants to influence catalytic properties. We have developed novel syntheses to prepare these well-defined catalysts with atomic-scale control the environment by choice and placement of ligands and applied state-of-themore » art spectroscopic, microscopic, and computational methods to determine their structures, reactivities, and catalytic properties. The ligands range from nearly flat MgO surfaces to enveloping zeolites to bulky calixarenes to provide controlled coverages of the metal clusters, while also enforcing unprecedented degrees of coordinative unsaturation at the metal site—thereby facilitating bonding and catalysis events at exposed metal atoms. With this wide range of ligand properties and our arsenal of characterization tools, we worked to achieve a deep, fundamental understanding of how to synthesize robust supported and ligand-modified metal clusters with controlled catalytic properties, thereby bridging the gap between active site structure and function in unsupported and supported metal catalysts. We used methods of organometallic and inorganic chemistry combined with surface chemistry for the precise synthesis of metal clusters and nanoparticles, characterizing them at various stages of preparation and under various conditions (including catalytic reaction conditions) and determining their structures and reactivities and how their catalytic properties depend on their compositions and structures. Key characterization methods included IR, NMR, and EXAFS spectroscopies to

Structures and stability of metal-doped GenM (n = 9, 10) clusters

NASA Astrophysics Data System (ADS)

Qin, Wei; Lu, Wen-Cai; Xia, Lin-Hua; Zhao, Li-Zhen; Zang, Qing-Jun; Wang, C. Z.; Ho, K. M.

2015-06-01

The lowest-energy structures of neutral and cationic GenM (n = 9, 10; M = Si, Li, Mg, Al, Fe, Mn, Pb, Au, Ag, Yb, Pm and Dy) clusters were studied by genetic algorithm (GA) and first-principles calculations. The calculation results show that doping of the metal atoms and Si into Ge9 and Ge10 clusters is energetically favorable. Most of the metal-doped Ge cluster structures can be viewed as adding or substituting metal atom on the surface of the corresponding ground-state Gen clusters. However, the neutral and cationic FeGe9,10,MnGe9,10 and Ge10Al are cage-like with the metal atom encapsulated inside. Such cage-like transition metal doped Gen clusters are shown to have higher adsorption energy and thermal stability. Our calculation results suggest that Ge9,10Fe and Ge9Si would be used as building blocks in cluster-assembled nanomaterials because of their high stabilities.

Carbonation of metal silicates for long-term CO.sub.2 sequestration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blencoe, James G.; Palmer, Donald A.; Anovitz, Lawrence M.

In a preferred embodiment, the invention relates to a process of sequestering carbon dioxide. The process comprises the steps of: (a) reacting a metal silicate with a caustic alkali-metal hydroxide to produce a hydroxide of the metal formerly contained in the silicate; (b) reacting carbon dioxide with at least one of a caustic alkali-metal hydroxide and an alkali-metal silicate to produce at least one of an alkali-metal carbonate and an alkali-metal bicarbonate; and (c) reacting the metal hydroxide product of step (a) with at least one of the alkali-metal carbonate and the alkali-metal bicarbonate produced in step (b) to producemore » a carbonate of the metal formerly contained in the metal silicate of step (a).« less

Carbonation of metal silicates for long-term CO.sub.2 sequestration

DOEpatents

Blencoe, James G [Harriman, TN; Palmer, Donald A [Oliver Springs, TN; Anovitz, Lawrence M [Knoxville, TN; Beard, James S [Martinsville, VA

2012-02-14

In a preferred embodiment, the invention relates to a process of sequestering carbon dioxide. The process comprises the steps of: (a) reacting a metal silicate with a caustic alkali-metal hydroxide to produce a hydroxide of the metal formerly contained in the silicate; (b) reacting carbon dioxide with at least one of a caustic alkali-metal hydroxide and an alkali-metal silicate to produce at least one of an alkali-metal carbonate and an alkali-metal bicarbonate; and (c) reacting the metal hydroxide product of step (a) with at least one of the alkali-metal carbonate and the alkali-metal bicarbonate produced in step (b) to produce a carbonate of the metal formerly contained in the metal silicate of step (a).

Atomically precise arrays of fluorescent silver clusters: a modular approach for metal cluster photonics on DNA nanostructures.

PubMed

Copp, Stacy M; Schultz, Danielle E; Swasey, Steven; Gwinn, Elisabeth G

2015-03-24

The remarkable precision that DNA scaffolds provide for arraying nanoscale optical elements enables optical phenomena that arise from interactions of metal nanoparticles, dye molecules, and quantum dots placed at nanoscale separations. However, control of ensemble optical properties has been limited by the difficulty of achieving uniform particle sizes and shapes. Ligand-stabilized metal clusters offer a route to atomically precise arrays that combine desirable attributes of both metals and molecules. Exploiting the unique advantages of the cluster regime requires techniques to realize controlled nanoscale placement of select cluster structures. Here we show that atomically monodisperse arrays of fluorescent, DNA-stabilized silver clusters can be realized on a prototypical scaffold, a DNA nanotube, with attachment sites separated by <10 nm. Cluster attachment is mediated by designed DNA linkers that enable isolation of specific clusters prior to assembly on nanotubes and preserve cluster structure and spectral purity after assembly. The modularity of this approach generalizes to silver clusters of diverse sizes and DNA scaffolds of many types. Thus, these silver cluster nano-optical elements, which themselves have colors selected by their particular DNA templating oligomer, bring unique dimensions of control and flexibility to the rapidly expanding field of nano-optics.

Site-specific polarizabilities as descriptors of metallic behavior in atomic clusters

NASA Astrophysics Data System (ADS)

Jackson, Koblar; Jellinek, Julius

The electric dipole polarizability of a cluster is a measure of its response to an applied electric field. The site specific polarizability method decomposes the total cluster polarizability into contributions from individual atoms and also allows it to be partitioned into charge transfer and electric dipole contributions. By systematically examining the trends in these quantities for several types of metal atom clusters over a wide range of cluster sizes, we find common characteristics that uniquely link the behavior of the clusters to that of the corresponding bulk metals for clusters as small as 10 atoms. We discuss these trends and compare and contrast them with results for non-metal clusters. This work was supported by the Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences, U.S. Department of Energy under Grant SC0001330 (KAJ) and Contract No. DE-AC02-06CH11357 (JJ).

Doppler-free satellites of resonances of electromagnetically induced transparency and absorption on the D 2 lines of alkali metals

NASA Astrophysics Data System (ADS)

Sargsyan, A.; Sarkisyan, D.; Staedter, D.; Akulshin, A. M.

2006-11-01

The peculiarities of intra-Doppler structures that are observed in the atomic absorption spectrum of alkali metals with the help of two independent lasers have been studied. These structures accompany ultranarrow coherent resonances of electromagnetically induced transparency and absorption. With the D 2 line of rubidium taken as an example, it is shown that, in the scheme of unidirectional waves, the maximum number of satellite resonances caused by optical pumping selective with respect to the atomic velocity is equal to seven, while only six resonances are observed in the traditional scheme of saturated absorption with counterpropagating waves of the same frequency. The spectral position of the resonances and their polarity depend on the frequency of the saturating radiation, while their number and relative amplitude depend also on the experimental geometry. These features are of general character and should show themselves in the absorption spectrum on the D 2 lines of all alkali metals. An explanation of these features is given. The calculated spectral separations between the resonances are compared to the experimental ones, and their possible application is discussed.

Deliberate and Accidental Gas-Phase Alkali Doping of Chalcogenide Semiconductors: Cu(In,Ga)Se2

PubMed Central

Colombara, Diego; Berner, Ulrich; Ciccioli, Andrea; Malaquias, João C.; Bertram, Tobias; Crossay, Alexandre; Schöneich, Michael; Meadows, Helene J.; Regesch, David; Delsante, Simona; Gigli, Guido; Valle, Nathalie; Guillot, Jérome; El Adib, Brahime; Grysan, Patrick; Dale, Phillip J.

2017-01-01

Alkali metal doping is essential to achieve highly efficient energy conversion in Cu(In,Ga)Se2 (CIGSe) solar cells. Doping is normally achieved through solid state reactions, but recent observations of gas-phase alkali transport in the kesterite sulfide (Cu2ZnSnS4) system (re)open the way to a novel gas-phase doping strategy. However, the current understanding of gas-phase alkali transport is very limited. This work (i) shows that CIGSe device efficiency can be improved from 2% to 8% by gas-phase sodium incorporation alone, (ii) identifies the most likely routes for gas-phase alkali transport based on mass spectrometric studies, (iii) provides thermochemical computations to rationalize the observations and (iv) critically discusses the subject literature with the aim to better understand the chemical basis of the phenomenon. These results suggest that accidental alkali metal doping occurs all the time, that a controlled vapor pressure of alkali metal could be applied during growth to dope the semiconductor, and that it may have to be accounted for during the currently used solid state doping routes. It is concluded that alkali gas-phase transport occurs through a plurality of routes and cannot be attributed to one single source. PMID:28233864

Deliberate and Accidental Gas-Phase Alkali Doping of Chalcogenide Semiconductors: Cu(In,Ga)Se2.

PubMed

Colombara, Diego; Berner, Ulrich; Ciccioli, Andrea; Malaquias, João C; Bertram, Tobias; Crossay, Alexandre; Schöneich, Michael; Meadows, Helene J; Regesch, David; Delsante, Simona; Gigli, Guido; Valle, Nathalie; Guillot, Jérome; El Adib, Brahime; Grysan, Patrick; Dale, Phillip J

2017-02-24

Alkali metal doping is essential to achieve highly efficient energy conversion in Cu(In,Ga)Se 2 (CIGSe) solar cells. Doping is normally achieved through solid state reactions, but recent observations of gas-phase alkali transport in the kesterite sulfide (Cu 2 ZnSnS 4 ) system (re)open the way to a novel gas-phase doping strategy. However, the current understanding of gas-phase alkali transport is very limited. This work (i) shows that CIGSe device efficiency can be improved from 2% to 8% by gas-phase sodium incorporation alone, (ii) identifies the most likely routes for gas-phase alkali transport based on mass spectrometric studies, (iii) provides thermochemical computations to rationalize the observations and (iv) critically discusses the subject literature with the aim to better understand the chemical basis of the phenomenon. These results suggest that accidental alkali metal doping occurs all the time, that a controlled vapor pressure of alkali metal could be applied during growth to dope the semiconductor, and that it may have to be accounted for during the currently used solid state doping routes. It is concluded that alkali gas-phase transport occurs through a plurality of routes and cannot be attributed to one single source.

Coverage dependent work function of graphene on a Cu(111) substrate with intercalated alkali metals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cook, Brandon G.; Russakoff, Arthur; Varga, Kalman

2015-05-26

Using first-principles calculations, it is shown that the work function of graphene on copper can be adjusted by varying the concentration of intercalated alkali metals. Using density functional theory, we calculate the modulation of work function when Li, Na, or K are intercalated between graphene and a Cu(111) surface. Furthermore, the physical origins of the change in work function are explained in terms of phenomenological models accounting for the formation and depolarization of interfacial dipoles and the shift in the Fermi-level induced via charge transfer.

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

PubMed

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.

Metal Adatoms and Clusters on Ultrathin Zirconia Films

PubMed Central

2016-01-01

Nucleation and growth of transition metals on zirconia has been studied by scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. Since STM requires electrical conductivity, ultrathin ZrO2 films grown by oxidation of Pt3Zr(0001) and Pd3Zr(0001) were used as model systems. DFT studies were performed for single metal adatoms on supported ZrO2 films as well as the (1̅11) surface of monoclinic ZrO2. STM shows decreasing cluster size, indicative of increasing metal–oxide interaction, in the sequence Ag < Pd ≈ Au < Ni ≈ Fe. Ag and Pd nucleate mostly at steps and domain boundaries of ZrO2/Pt3Zr(0001) and form three-dimensional clusters. Deposition of low coverages of Ni and Fe at room temperature leads to a high density of few-atom clusters on the oxide terraces. Weak bonding of Ag to the oxide is demonstrated by removing Ag clusters with the STM tip. DFT calculations for single adatoms show that the metal–oxide interaction strength increases in the sequence Ag < Au < Pd < Ni on monoclinic ZrO2, and Ag ≈ Au < Pd < Ni on the supported ultrathin ZrO2 film. With the exception of Au, metal nucleation and growth on ultrathin zirconia films follow the usual rules: More reactive (more electropositive) metals result in a higher cluster density and wet the surface more strongly than more noble metals. These bind mainly to the oxygen anions of the oxide. Au is an exception because it can bind strongly to the Zr cations. Au diffusion may be impeded by changing its charge state between −1 and +1. We discuss differences between the supported ultrathin zirconia films and the surfaces of bulk ZrO2, such as the possibility of charge transfer to the substrate of the films. Due to their large in-plane lattice constant and the variety of adsorption sites, ZrO2{111} surfaces are more reactive than many other oxygen-terminated oxide surfaces. PMID:27213024

Method of coating metal surfaces to form protective metal coating thereon

DOEpatents

Krikorian, Oscar H.; Curtis, Paul G.

1992-01-01

A process is disclosed for forming a protective metal coating on a metal surface using a flux consisting of an alkali metal fluoride, an alkaline earth metal fluoride, an alkali metal fluoaluminate, an alkali metal fluosilicate, and mixtures thereof. The flux, in particulate form, is mixed with particles of a metal coating material which may comprise aluminum, chromium, mixtures thereof, and alloys containing at least 50 wt. % aluminum and the particulate mixture is applied to the metal surface in a single step, followed by heating the coated metal surface to a temperature sufficient to cause the metal coating material to react with the metal surface to form a protective reaction product in the form of a metal coating bonded to the metal surface. The metal surface which reacts with the metal coating material to form the protective coating may comprise Fe, Co, Ni, Ti, V, Cr, Mn, Zr, Nb, Mo, Tc, Hf, Ta, W, Re and alloys thereof.

Method of coating metal surfaces to form protective metal coating thereon

DOEpatents

Krikorian, O.H.; Curtis, P.G.

1992-03-31

A process is disclosed for forming a protective metal coating on a metal surface using a flux consisting of an alkali metal fluoride, an alkaline earth metal fluoride, an alkali metal fluoaluminate, an alkali metal fluosilicate, and mixtures thereof. The flux, in particulate form, is mixed with particles of a metal coating material which may comprise aluminum, chromium, mixtures thereof, and alloys containing at least 50 wt. % aluminum and the particulate mixture is applied to the metal surface in a single step, followed by heating the coated metal surface to a temperature sufficient to cause the metal coating material to react with the metal surface to form a protective reaction product in the form of a metal coating bonded to the metal surface. The metal surface which reacts with the metal coating material to form the protective coating may comprise Fe, Co, Ni, Ti, V, Cr, Mn, Zr, Nb, Mo, Tc, Hf, Ta, W, Re and alloys thereof. 1 figure.

Structures and stability of metal-doped Ge nM (n = 9, 10) clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qin, Wei; Lu, Wen-Cai; Xia, Lin-Hua

The lowest-energy structures of neutral and cationic Ge nM (n = 9, 10; M = Si, Li, Mg, Al, Fe, Mn, Pb, Au, Ag, Yb, Pm and Dy) clusters were studied by genetic algorithm (GA) and first-principles calculations. The calculation results show that doping of the metal atoms and Si into Ge 9 and Ge 10 clusters is energetically favorable. Most of the metal-doped Ge cluster structures can be viewed as adding or substituting metal atom on the surface of the corresponding ground-state Ge n clusters. However, the neutral and cationic FeGe 9,10,MnGe 9,10 and Ge 10Al are cage-like withmore » the metal atom encapsulated inside. Such cage-like transition metal doped Ge n clusters are shown to have higher adsorption energy and thermal stability. Our calculation results suggest that Ge 9,10Fe and Ge 9Si would be used as building blocks in cluster-assembled nanomaterials because of their high stabilities.« less

Structures and stability of metal-doped Ge nM (n = 9, 10) clusters

DOE PAGES

Qin, Wei; Lu, Wen-Cai; Xia, Lin-Hua; ...

2015-06-26

The lowest-energy structures of neutral and cationic Ge nM (n = 9, 10; M = Si, Li, Mg, Al, Fe, Mn, Pb, Au, Ag, Yb, Pm and Dy) clusters were studied by genetic algorithm (GA) and first-principles calculations. The calculation results show that doping of the metal atoms and Si into Ge 9 and Ge 10 clusters is energetically favorable. Most of the metal-doped Ge cluster structures can be viewed as adding or substituting metal atom on the surface of the corresponding ground-state Ge n clusters. However, the neutral and cationic FeGe 9,10,MnGe 9,10 and Ge 10Al are cage-like withmore » the metal atom encapsulated inside. Such cage-like transition metal doped Ge n clusters are shown to have higher adsorption energy and thermal stability. Our calculation results suggest that Ge 9,10Fe and Ge 9Si would be used as building blocks in cluster-assembled nanomaterials because of their high stabilities.« less

High-temperature, high-pressure hydrothermal synthesis, characterization, and structural relationships of mixed-alkali metals uranyl silicates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Yi-Hsin; Liu, Hsin-Kuan; Chang, Wen-Jung

2016-04-15

Three mixed-alkali metals uranyl silicates, Na{sub 3}K{sub 3}[(UO{sub 2}){sub 3}(Si{sub 2}O{sub 7}){sub 2}]·2H{sub 2}O (1), Na{sub 3}Rb{sub 3}[(UO{sub 2}){sub 3}(Si{sub 2}O{sub 7}){sub 2}] (2), and Na{sub 6}Rb{sub 4}[(UO{sub 2}){sub 4}Si{sub 12}O{sub 33}] (3), have been synthesized by high-temperature, high-pressure hydrothermal reactions at 550 °C and 1440 bar, and characterized by single-crystal X-ray diffraction, photoluminescence, and thermogravimetric analysis. Compound 1 and 2 are isostructural and contain layers of uranyl disilicate. The smaller cation, Na{sup +}, is located in the intralayer channels, whereas the larger cations, K{sup +} and Rb{sup +}, and water molecule are located in the interlayer region. The absencemore » of lattice water in 2 can be understood according to the valence-matching principle. The structure is related to that of a previously reported mixed-valence uranium(V,VI) silicate. Compound 3 adopts a 3D framework structure and contains a unique unbranched dreier fourfold silicate chain with the structural formula {uB,4"1_∞}[{sup 3}Si{sub 12}O{sub 33}] formed of Q{sup 2}, Q{sup 3}, and Q{sup 4} Si. The connectivity of the Si atoms in the Si{sub 12}O{sub 33}{sup 18−} anion can be interpreted on the basis of Zintl–Klemm concept. Crystal data for compound 1: triclinic, P-1, a=5.7981(2) Å, b=7.5875(3) Å, c=12.8068(5) Å, α=103.593(2)°, β=102.879(2)°, γ=90.064(2)°, V=533.00(3) Å{sup 3}, Z=1, R1=0.0278; compound 2: triclinic, P-1, a=5.7993(3) Å, b=7.5745(3) Å, c=12.9369(6) Å, α=78.265(2)°, β=79.137(2)°, γ=89.936(2)°, V=546.02(4) Å{sup 3}, Z=1, R1=0.0287; compound 3: monoclinic, C2/m, a=23.748(1) Å, b=7.3301(3) Å, c=15.2556(7) Å, β=129.116(2)°, V=2060.4(2) Å{sup 3}, Z=2, R1=0.0304. - Graphical abstract: Three mixed-alkali metals uranyl silicates were synthesized under hydrothermal conditions at 550 °C and 1400 bar and structurally characterized by single-crystal X-ray diffraction. Two of them have a layer

Structure of overheated metal clusters: MD simulation study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vorontsov, Alexander

2015-08-17

The structure of overheated metal clusters appeared in condensation process was studied by computer simulation techniques. It was found that clusters with size larger than several tens of atoms have three layers: core part, intermediate dense packing layer and a gas- like shell with low density. The change of the size and structure of these layers with the variation of internal energy and the size of cluster is discussed.

Star clusters: age, metallicity and extinction from integrated spectra

NASA Astrophysics Data System (ADS)

González Delgado, Rosa M.; Cid Fernandes, Roberto

2010-01-01

Integrated optical spectra of star clusters in the Magellanic Clouds and a few Galactic globular clusters are fitted using high-resolution spectral models for single stellar populations. The goal is to estimate the age, metallicity and extinction of the clusters, and evaluate the degeneracies among these parameters. Several sets of evolutionary models that were computed with recent high-spectral-resolution stellar libraries (MILES, GRANADA, STELIB), are used as inputs to the starlight code to perform the fits. The comparison of the results derived from this method and previous estimates available in the literature allow us to evaluate the pros and cons of each set of models to determine star cluster properties. In addition, we quantify the uncertainties associated with the age, metallicity and extinction determinations resulting from variance in the ingredients for the analysis.

Supersonic Bare Metal Cluster Beams. Technical Progress Report, March 16, 1984 - April 1, 1985

DOE R&D Accomplishments Database

Smalley, R. E.

1985-01-01

There have been four major areas of concentration for the study of bare metal cluster beams: neutral cluster, chemical reactivity, cold cluster ion source development (both positive and negative), bare cluster ion ICR (ion cyclotron resonance) development, and photofragmentation studies of bare metal cluster ions.

Metal Cluster Models for Heterogeneous Catalysis: A Matrix-Isolation Perspective.

PubMed

Hübner, Olaf; Himmel, Hans-Jörg

2018-02-19

Metal cluster models are of high relevance for establishing new mechanistic concepts for heterogeneous catalysis. The high reactivity and particular selectivity of metal clusters is caused by the wealth of low-lying electronically excited states that are often thermally populated. Thereby the metal clusters are flexible with regard to their electronic structure and can adjust their states to be appropriate for the reaction with a particular substrate. The matrix isolation technique is ideally suited for studying excited state reactivity. The low matrix temperatures (generally 4-40 K) of the noble gas matrix host guarantee that all clusters are in their electronic ground-state (with only a very few exceptions). Electronically excited states can then be selectively populated and their reactivity probed. Unfortunately, a systematic research in this direction has not been made up to date. The purpose of this review is to provide the grounds for a directed approach to understand cluster reactivity through matrix-isolation studies combined with quantum chemical calculations. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Study of Anti-/Pro-Oxidant, Lipophilic, Microbial and Spectroscopic Properties of New Alkali Metal Salts of 5-O-Caffeoylquinic Acid

PubMed Central

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

Calorimetric Study of Alkali Metal Ion (K +, Na +, Li +) Exchange in a Clay-Like MXene

DOE PAGES

Sharma, Geetu; Muthuswamy, Elayaraja; Naguib, Michael; ...

2017-06-21

Intercalation of ions in layered materials has been explored to improve the rate capability in Li-ion batteries and supercapacitors. This work investigates the energetics of alkali ion exchange in a clay-like MXene, Ti 3C 2T x, where T x stands for anionic surface moieties, by immersion calorimetry in aqueous solutions. The measured immersion enthalpies of clay-like Ti 3C 2T x, ΔH imm, at 25 °C in 1 M KCl, 1 M NaCl, 1 M LiCl, and nanopure water are -9.19 (±0.56), -5.90 (±0.31), -1.31 (±0.20), and -1.29 (±0.13) kJ/mol of MXene, respectively. Inductively coupled plasma mass spectrometry is used tomore » obtain the concentrations of alkali ions in the solid and aqueous phases. Using these concentrations, the enthalpies of exchange of alkali metal ions (Li+, Na+, and K+) are calculated; ΔHex in 1 M KCl, 1 M NaCl, 1 M LiCl, and nanopure water are -9.3 (±2.2), 21.0 (±0.9), -1.3 (±0.2), and 302.4 (±0.6) kJ/mol of MXene, respectively. Both immersion and exchange enthalpies are most exothermic for potassium. This suggests that K+ ions interact more strongly with anions present in the interlayers of this MXene than Na + and Li + ions. Water vapor adsorption calorimetry indicates very weak interaction of water with the MXene, while immersion calorimetry suggests a weakly hydrophilic nature of the MXene surface.« less

Calorimetric Study of Alkali Metal Ion (K +, Na +, Li +) Exchange in a Clay-Like MXene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Geetu; Muthuswamy, Elayaraja; Naguib, Michael

Intercalation of ions in layered materials has been explored to improve the rate capability in Li-ion batteries and supercapacitors. This work investigates the energetics of alkali ion exchange in a clay-like MXene, Ti 3C 2T x, where T x stands for anionic surface moieties, by immersion calorimetry in aqueous solutions. The measured immersion enthalpies of clay-like Ti 3C 2T x, ΔH imm, at 25 °C in 1 M KCl, 1 M NaCl, 1 M LiCl, and nanopure water are -9.19 (±0.56), -5.90 (±0.31), -1.31 (±0.20), and -1.29 (±0.13) kJ/mol of MXene, respectively. Inductively coupled plasma mass spectrometry is used tomore » obtain the concentrations of alkali ions in the solid and aqueous phases. Using these concentrations, the enthalpies of exchange of alkali metal ions (Li+, Na+, and K+) are calculated; ΔHex in 1 M KCl, 1 M NaCl, 1 M LiCl, and nanopure water are -9.3 (±2.2), 21.0 (±0.9), -1.3 (±0.2), and 302.4 (±0.6) kJ/mol of MXene, respectively. Both immersion and exchange enthalpies are most exothermic for potassium. This suggests that K+ ions interact more strongly with anions present in the interlayers of this MXene than Na + and Li + ions. Water vapor adsorption calorimetry indicates very weak interaction of water with the MXene, while immersion calorimetry suggests a weakly hydrophilic nature of the MXene surface.« less

Metal clusters and nanoparticles in dielectric matrices: Formation and optical properties

NASA Astrophysics Data System (ADS)

Gladskikh, I. A.; Vartanyan, T. A.

2016-12-01

The optical properties of thin dielectric films with metal inclusions and their dependence on thermal and laser annealing are studied experimentally. Metal clusters (Ag, Au, and Cu) in dielectric materials (Al2O3 and SiO2) are obtained by simultaneous vacuum deposition of metal and dielectric on the surface of a corresponding dielectric substrate (sapphire and quartz). It is shown that, depending on the deposited dielectric material, on the weight ratio of deposited metal and dielectric, and on the subsequent thermal treatment, one can obtain different metal structures, from clusters with a small number of atoms to complex dendritic plasmonic structures.

Alkali and alkaline earth metal salts of tetrazolone: structurally interesting and excellently thermostable.

PubMed

He, Piao; Wu, Le; Wu, Jin-Ting; Yin, Xin; Gozin, Michael; Zhang, Jian-Guo

2017-07-04

Tetrazolone (5-oxotetrazole) was synthesized by a moderate strategy through three steps (addition, cyclization and catalytic hydrogenation) avoiding the unstable intermediate diazonium, as reported during the previous preparation. Alkali and alkaline earth metal salts with lithium (1), sodium (2), potassium (3), rubidium (4) caesium (5), magnesium (6), calcium (7), strontium (8) and barium (9) were prepared and fully characterized using elemental analysis, IR and NMR spectroscopy, DSC and TG analysis. All metal salts were characterized via single-crystal X-ray diffraction. They crystallize in common space groups with high densities ranging from 1.479 (1) to 3.060 g cm -3 (5). Furthermore, the crystal structures of 7, 8 and 9 reveal interesting porous energetic coordination polymers with strong hydrogen bond interactions. All new salts have good thermal stabilities with decomposition temperature between 215.0 °C (4) and 328.2 °C (7), significantly higher than that of the reported nitrogen-rich salt neutral tetrazolone. The sensitivities towards impact and friction were tested using standard methods, and all the tetrazolone-based compounds investigated can be classified into insensitive. The flame test of these metal salts supports their potential use as perchlorate-free pyrotechnics or eco-friendly insensitive energetic materials.

Molecular origin of high free energy barriers for alkali metal ion transfer through ionic liquid-graphene electrode interfaces.

PubMed

Ivaništšev, Vladislav; Méndez-Morales, Trinidad; Lynden-Bell, Ruth M; Cabeza, Oscar; Gallego, Luis J; Varela, Luis M; Fedorov, Maxim V

2016-01-14

In this work we study mechanisms of solvent-mediated ion interactions with charged surfaces in ionic liquids by molecular dynamics simulations, in an attempt to reveal the main trends that determine ion-electrode interactions in ionic liquids. We compare the interfacial behaviour of Li(+) and K(+) at a charged graphene sheet in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, and its mixtures with lithium and potassium tetrafluoroborate salts. Our results show that there are dense interfacial solvation structures in these electrolytes that lead to the formation of high free energy barriers for these alkali metal cations between the bulk and direct contact with the negatively charged surface. We show that the stronger solvation of Li(+) in the ionic liquid leads to the formation of significantly higher interfacial free energy barriers for Li(+) than for K(+). The high free energy barriers observed in our simulations can explain the generally high interfacial resistance in electrochemical storage devices that use ionic liquid-based electrolytes. Overcoming these barriers is the rate-limiting step in the interfacial transport of alkali metal ions and, hence, appears to be a major drawback for a generalised application of ionic liquids in electrochemistry. Some plausible strategies for future theoretical and experimental work for tuning them are suggested.

Alkali metals in addition to acidic pH activate the EvgS histidine kinase sensor in Escherichia coli.

PubMed

Eguchi, Yoko; Utsumi, Ryutaro

2014-09-01

Two-component signal transduction systems (TCSs) in bacteria perceive environmental stress and transmit the information via phosphorelay to adjust multiple cellular functions for adaptation. The EvgS/EvgA system is a TCS that confers acid resistance to Escherichia coli cells. Activation of the EvgS sensor initiates a cascade of transcription factors, EvgA, YdeO, and GadE, which induce the expression of a large group of acid resistance genes. We searched for signals activating EvgS and found that a high concentration of alkali metals (Na(+), K(+)) in addition to low pH was essential for the activation. EvgS is a histidine kinase, with a large periplasmic sensor region consisting of two tandem PBPb (bacterial periplasmic solute-binding protein) domains at its N terminus. The periplasmic sensor region of EvgS was necessary for EvgS activation, and Leu152, located within the first PBPb domain, was involved in the activation. Furthermore, chimeras of EvgS and PhoQ histidine kinases suggested that alkali metals were perceived at the periplasmic sensor region, whereas the cytoplasmic linker domain, connecting the transmembrane region and the histidine kinase domain, was required for low-pH perception. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Elucidation of Proton-Assisted Fluxionality in Transition-Metal Oxide Clusters

NASA Astrophysics Data System (ADS)

Ramabhadran, Raghunath O.; Mayhall, Nicholas J.; Becher, Edwin L. Becher, Iii; Chowdhury, Arefin; Raghavachari, Krishnan

2012-06-01

The phenomenon of fluxionality in the reactions of transition-metal oxide clusters provides many opportunities in various industrial and catalytic processes. We present an electronic structure investigation of the fluxionality pathways when anionic W3O6- and Mo3O6- clusters react with three small molecules - water, ammonia and hydrogen sulfide. The presentation features a detailed understanding of (a) how the fluxionality pathway occurs and (b) the various factors that affect the fluxionality pathway - such as the metal, different spin-states and the nature of the non-metal in the reacting small molecule.

Volume shift and charge instability of simple-metal clusters

NASA Astrophysics Data System (ADS)

Brajczewska, M.; Vieira, A.; Fiolhais, C.; Perdew, J. P.

1996-12-01

Experiment indicates that small clusters show changes (mostly contractions) of the bond lengths with respect to bulk values. We use the stabilized jellium model to study the self-expansion and self-compression of spherical clusters (neutral or ionized) of simple metals. Results from Kohn - Sham density functional theory are presented for small clusters of Al and Na, including negatively-charged ones. We also examine the stability of clusters with respect to charging.

Spectroscopic and theoretical investigations of alkali metal linoleates and oleinates

NASA Astrophysics Data System (ADS)

Świsłocka, Renata; Regulska, Ewa; Jarońko, Paweł; Lewandowski, Włodzimierz

2017-11-01

The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of the linoleic (cis-9,cis-12-octadecadienoic) and oleic (cis-9-octadecenoic) acids was investigated. The complementary analytical methods: vibrational (IR, Raman) and electronic (UV) molecular absorption spectroscopy as well as DFT quantum mechanical calculations (charge distribution, angles between bonds, bond lengths, theoretical IR and NMR spectra) were carried out. The regular shifts of bands connected with carboxylate anion in the spectra of studied salts were observed. Some bonds and angles reduced or elongated in the series: acid→Li→Na→K linoleates/oleinates. The highest changes were noted for bond lengths and angles concerning COO- ion. The electronic charge distribution in studied molecules was also discussed. Total atomic charges of carboxylate anion decrease as a result of the replacement of hydrogen atom with alkali metal cation. The increasing values of dipole moment and decreasing values of total energy in the order: linoleic/oleic acid→lithium→sodium→potassium linoleates/oleinates indicate an increase in stability of the compounds.

Bonding and Mobility of Alkali Metals in Helicenes.

PubMed

Barroso, Jorge; Murillo, Fernando; Martínez-Guajardo, Gerardo; Ortíz-Chi, Filiberto; Pan, Sudip; Fernández-Herrera, María A; Merino, Gabriel

2018-06-04

In this work, we analyze the interaction of alkali metal cations with [6]- and [14]helicene and the cation mobility of therein. We found that the distortion of the carbon skeleton is the cause that some of the structures that are local minima for the smallest cations are not energetically stable for K+, Rb+, and Cs+. Also, the most favorable complexes are those where the cation is interacting with two rings forming a metallocene-like structure, except for the largest cation Cs+, where the distortion provoked by the size of the cation desestabilizes the complex. As far as mobility is concerned, the smallest cations, particularly Na+, are the ones that can move most efficiently. In [6]helicene, the mobility is limited by the capture of the cation forming the metallocene-like structure. In larger helicenes, the energy barriers for the cation to move are similar both inside and outside the helix. However, complexes with the cation between two layers are more energetically favored so that the movement will be preferred in that region. The bonding analysis reveals that interactions with no less than 50% of orbitalic contribution are taking place for the series of E+-[6]helicene. Particularly, the complexes of Li+ stand out showing a remarkably orbitalic character bonding (72.5 - 81.6%). © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pal 12 - A metal-rich globular cluster in the outer halo

NASA Technical Reports Server (NTRS)

Cohen, J. G.; Frogel, J. A.; Persson, S. E.; Zinn, R.

1980-01-01

New optical and infrared observations of several stars in the distant globular cluster Pal 12 show that they have CO strengths and heavy element abundances only slightly less than in M 71, one of the more metal-rich globular clusters. Pal 12 thus has a metal abundance near the high end of the range over which globular clusters exist and lies in the outer galactic halo. Its red horizontal branch is not anomalous in view of the abundance that has been found.

Structure of fluorescent metal clusters on a DNA template.

NASA Astrophysics Data System (ADS)

Vdovichev, A. A.; Sych, T. S.; Reveguk, Z. V.; Smirnova, A. A.; Maksimov, D. A.; Ramazanov, R. R.; Kononov, A. I.

2016-08-01

Luminescent metal clusters are a subject of growing interest in recent years due to their bright emission from visible to near infrared range. Detailed structure of the fluorescent complexes of Ag and other metal clusters with ligands still remains a challenging task. In this joint experimental and theoretical study we synthesized Ag-DNA complexes on a DNA oligonucleotide emitting in violet- green spectral range. The structure of DNA template was determined by means of various spectral measurements (CD, MS, XPS). Comparison of the experimental fluorescent excitation spectra and calculated absorption spectra for different QM/MM optimized structures allowed us to determine the detailed structure of the green cluster containing three silver atoms in the stem of the DNA hairpin structure stabilized by cytosine-Ag+-cytosine bonds.

Tracing the Chemical Evolution of Metal-rich Galactic Bulge Globular Clusters

NASA Astrophysics Data System (ADS)

Munoz Gonzalez, Cesar; Saviane, Ivo; Geisler, Doug; Villanova, Sandro

2018-01-01

We present in this poster the metallicity characterization of the four metal rich Bulge Galactic Gobular Clusters, which have controversial metallicities. We analyzed our high-resolution spectra (using UVES-580nm and GIRAFFE-HR13 setups) for a large sample of RGB/AGB targets in each cluster in order to measure their metallicity and prove or discard the iron spread hypothesis. We have also characterized chemically stars with potentially different iron content by measuring light (O, Na, Mg, Al), alpha (Si, Ca, Ti), iron–peak (V, Cr, Ni, Mn) and s and r process (Y, Zr, Ba, Eu) elements. We have identified possible channels responsible for the chemical heterogeneity of the cluster populations, like AGB or massive fast-rotating stars contamination, or SN explosion. Also, we have analyzed the origin and evolution of these bulge GCs and their connection with the bulge itself.

Estimating metallicities with isochrone fits to photometric data of open clusters

NASA Astrophysics Data System (ADS)

Monteiro, H.; Oliveira, A. F.; Dias, W. S.; Caetano, T. C.

2014-10-01

The metallicity is a critical parameter that affects the correct determination of stellar cluster's fundamental characteristics and has important implications in Galactic and Stellar evolution research. Fewer than 10% of the 2174 currently catalogued open clusters have their metallicity determined in the literature. In this work we present a method for estimating the metallicity of open clusters via non-subjective isochrone fitting using the cross-entropy global optimization algorithm applied to UBV photometric data. The free parameters distance, reddening, age, and metallicity are simultaneously determined by the fitting method. The fitting procedure uses weights for the observational data based on the estimation of membership likelihood for each star, which considers the observational magnitude limit, the density profile of stars as a function of radius from the center of the cluster, and the density of stars in multi-dimensional magnitude space. We present results of [Fe/H] for well-studied open clusters based on distinct UBV data sets. The [Fe/H] values obtained in the ten cases for which spectroscopic determinations were available in the literature agree, indicating that our method provides a good alternative to estimating [Fe/H] by using an objective isochrone fitting. Our results show that the typical precision is about 0.1 dex.

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

PubMed

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

A Simple MO Treatment of Metal Clusters.

ERIC Educational Resources Information Center

Sahyun, M. R. V.

1980-01-01

Illustrates how a qualitative description of the geometry and electronic characteristics of homogeneous metal clusters can be obtained using semiempirical MO (molecular orbital theory) methods. Computer applications of MO methods to inorganic systems are also described. (CS)

Composition formulas of Fe-based transition metals-metalloid bulk metallic glasses derived from dual-cluster model of binary eutectics.

PubMed

Naz, Gul Jabeen; Dong, Dandan; Geng, Yaoxiang; Wang, Yingmin; Dong, Chuang

2017-08-22

It is known that bulk metallic glasses follow simple composition formulas [cluster](glue atom) 1 or 3 with 24 valence electrons within the framework of the cluster-plus-glue-atom model. Though the relevant nearest-neighbor cluster can be readily identified from a devitrification phase, the glue atoms remains poorly defined. The present work is devoted to understanding the composition rule of Fe-(B,P,C) based multi-component bulk metallic glasses, by introducing a cluster-based eutectic liquid model. This model regards a eutectic liquid to be composed of two stable liquids formulated respectively by cluster formulas for ideal metallic glasses from the two eutectic phases. The dual cluster formulas are first established for binary Fe-(B,C,P) eutectics: [Fe-Fe 14 ]B 2 Fe + [B-B 2 Fe 8 ]Fe ≈ Fe 83.3 B 16.7 for eutectic Fe 83 B 17 , [P-Fe 14 ]P + [P-Fe 9 ]P 2 Fe≈Fe 82.8 P 17.2 for Fe 83 P 17 , and [C-Fe 6 ]Fe 3  + [C-Fe 9 ]C 2 Fe ≈ Fe 82.6 C 17.4 for Fe 82.7 C 17.3 . The second formulas in these dual-cluster formulas, being respectively relevant to devitrification phases Fe 2 B, Fe 3 P, and Fe 3 C, well explain the compositions of existing Fe-based transition metals-metalloid bulk metallic glasses. These formulas also satisfy the 24-electron rule. The proposition of the composition formulas for good glass formers, directly from known eutectic points, constitutes a new route towards understanding and eventual designing metallic glasses of high glass forming abilities.

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

NASA Technical Reports Server (NTRS)

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.

Structures and stability of metal-doped Ge{sub n}M (n = 9, 10) clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qin, Wei, E-mail: qinw@qdu.edu.cn; Xia, Lin-Hua; Zhao, Li-Zhen

The lowest-energy structures of neutral and cationic Ge{sub n}M (n = 9, 10; M = Si, Li, Mg, Al, Fe, Mn, Pb, Au, Ag, Yb, Pm and Dy) clusters were studied by genetic algorithm (GA) and first-principles calculations. The calculation results show that doping of the metal atoms and Si into Ge{sub 9} and Ge{sub 10} clusters is energetically favorable. Most of the metal-doped Ge cluster structures can be viewed as adding or substituting metal atom on the surface of the corresponding ground-state Ge{sub n} clusters. However, the neutral and cationic FeGe{sub 9,10},MnGe{sub 9,10} and Ge{sub 10}Al are cage-like withmore » the metal atom encapsulated inside. Such cage-like transition metal doped Ge{sub n} clusters are shown to have higher adsorption energy and thermal stability. Our calculation results suggest that Ge{sub 9,10}Fe and Ge{sub 9}Si would be used as building blocks in cluster-assembled nanomaterials because of their high stabilities.« less

Universal scaling of potential energy functions describing intermolecular interactions. II. The halide-water and alkali metal-water interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Werhahn, Jasper C.; Akase, Dai; Xantheas, Sotiris S.

2014-08-14

The scaled versions of the newly introduced [S. S. Xantheas and J. C. Werhahn, J. Chem. Phys.141, 064117 (2014)] generalized forms of some popular potential energy functions (PEFs) describing intermolecular interactions – Mie, Lennard-Jones, Morse, and Buckingham exponential-6 – have been used to fit the ab initio relaxed approach paths and fixed approach paths for the halide-water, X -(H 2O), X = F, Cl, Br, I, and alkali metal-water, M +(H 2O), M = Li, Na, K, Rb, Cs, interactions. The generalized forms of those PEFs have an additional parameter with respect to the original forms and produce fits tomore » the ab initio data that are between one and two orders of magnitude better in the χ 2 than the original PEFs. They were found to describe both the long-range, minimum and repulsive wall of the respective potential energy surfaces quite accurately. Overall the 4-parameter extended Morse (eM) and generalized Buckingham exponential-6 (gBe-6) potentials were found to best fit the ab initio data for these two classes of ion-water interactions. Finally, the fitted values of the parameter of the (eM) and (gBe-6) PEFs that control the repulsive wall of the potential correlate remarkably well with the ionic radii of the halide and alkali metal ions.« less

Systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooks, Robert Graham; Li, Anyin; Luo, Qingjie

The invention generally relates to systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions. In certain aspects, the invention provides methods that involve providing a metal and a solvent. The methods additionally involve applying voltage to the solvated metal to thereby produce solvent droplets including ions of the metal containing compound, and directing the solvent droplets including the metal ions to a target. In certain embodiments, once at the target, the metal ions can react directly or catalyze reactions.

Systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions

DOEpatents

Cooks, Robert Graham; Li, Anyin; Luo, Qingjie

2017-01-24

The invention generally relates to systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions. In certain aspects, the invention provides methods that involve providing a metal and a solvent. The methods additionally involve applying voltage to the solvated metal to thereby produce solvent droplets including ions of the metal containing compound, and directing the solvent droplets including the metal ions to a target. In certain embodiments, once at the target, the metal ions can react directly or catalyze reactions.

Development of Metal Cluster-Based Energetic Materials at NSWC-IHD

DTIC Science & Technology

2011-01-01

reactivity of NixAly + clusters with nitromethane was investigated using a gas-phase molecular beam system. Results indicate that nitromethane is highly...clusters make up the subunit of a molecular metal-based energetic material. The reactivity of NixAly+ clusters with nitromethane was investigated using...a gas-phase molecular beam system. Results indicate that nitromethane is highly reactive toward the NixAly+ clusters and suggests it would not make

Influence of alkali metal cations/type of activator on the structure of alkali-activated fly ash - ATR-FTIR studies

NASA Astrophysics Data System (ADS)

Król, M.; Rożek, P.; Chlebda, D.; Mozgawa, W.

2018-06-01

Coal fly ash as a secondary aluminosiliceous raw material that is commonly used in the so-called geopolymerization process has been activated with different alkali hydroxides solutions: LiOH, NaOH and KOH. Changes in the aluminosilicate structure of the material during alkali-activation have been analyzed in detail on the basis of ATR/FT-IR spectra. These changes mainly affect both the integral intensity and FWHM of bands in the range of 1200-950 cm-1, however dehydration and carbonation process can be also analyzed based on obtaining results.

On the origin of alkali metals in Europa exosphere

NASA Astrophysics Data System (ADS)

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.

Structural and electronic engineering of 3DOM WO3 by alkali metal doping for improved NO2 sensing performance

NASA Astrophysics Data System (ADS)

Wang, Zhihua; Fan, Xiaoxiao; Han, Dongmei; Gu, Fubo

2016-05-01

Novel alkali metal doped 3DOM WO3 materials were prepared using a simple colloidal crystal template method. Raman, XRD, SEM, TEM, XPS, PL, Hall and UV-Vis techniques were used to characterize the structural and electronic properties of all the products, while the corresponding sensing performances targeting ppb level NO2 were determined at different working temperatures. For the overall goal of structural and electronic engineering, the co-effect of structural and electronic properties on the improved NO2 sensing performance of alkali metal doped 3DOM WO3 was studied. The test results showed that the gas sensing properties of 3DOM WO3/Li improved the most, with the fast response-recovery time and excellent selectivity. More importantly, the response of 3DOM WO3/Li to 500 ppb NO2 was up to 55 at room temperature (25 °C). The especially high response to ppb level NO2 at room temperature (25 °C) in this work has a very important practical significance. The best sensing performance of 3DOM WO3/Li could be ascribed to the most structure defects and the highest carrier mobility. And the possible gas sensing mechanism based on the model of the depletion layer was proposed to demonstrate that both structural and electronic properties are responsible for the NO2 sensing behavior.Novel alkali metal doped 3DOM WO3 materials were prepared using a simple colloidal crystal template method. Raman, XRD, SEM, TEM, XPS, PL, Hall and UV-Vis techniques were used to characterize the structural and electronic properties of all the products, while the corresponding sensing performances targeting ppb level NO2 were determined at different working temperatures. For the overall goal of structural and electronic engineering, the co-effect of structural and electronic properties on the improved NO2 sensing performance of alkali metal doped 3DOM WO3 was studied. The test results showed that the gas sensing properties of 3DOM WO3/Li improved the most, with the fast response-recovery time and

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

NASA Astrophysics Data System (ADS)

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.

Effect of functionalization of boron nitride flakes by main group metal clusters on their optoelectronic properties

NASA Astrophysics Data System (ADS)

Chakraborty, Debdutta; Chattaraj, Pratim Kumar

2017-10-01

The possibility of functionalizing boron nitride flakes (BNFs) with some selected main group metal clusters, viz. OLi4, NLi5, CLi6, BLI7 and Al12Be, has been analyzed with the aid of density functional theory (DFT) based computations. Thermochemical as well as energetic considerations suggest that all the metal clusters interact with the BNF moiety in a favorable fashion. As a result of functionalization, the static (first) hyperpolarizability (β ) values of the metal cluster supported BNF moieties increase quite significantly as compared to that in the case of pristine BNF. Time dependent DFT analysis reveals that the metal clusters can lower the transition energies associated with the dominant electronic transitions quite significantly thereby enabling the metal cluster supported BNF moieties to exhibit significant non-linear optical activity. Moreover, the studied systems demonstrate broad band absorption capability spanning the UV-visible as well as infra-red domains. Energy decomposition analysis reveals that the electrostatic interactions principally stabilize the metal cluster supported BNF moieties.

Effect of functionalization of boron nitride flakes by main group metal clusters on their optoelectronic properties.

PubMed

Chakraborty, Debdutta; Chattaraj, Pratim Kumar

2017-10-25

The possibility of functionalizing boron nitride flakes (BNFs) with some selected main group metal clusters, viz. OLi 4 , NLi 5 , CLi 6 , BLI 7 and Al 12 Be, has been analyzed with the aid of density functional theory (DFT) based computations. Thermochemical as well as energetic considerations suggest that all the metal clusters interact with the BNF moiety in a favorable fashion. As a result of functionalization, the static (first) hyperpolarizability ([Formula: see text]) values of the metal cluster supported BNF moieties increase quite significantly as compared to that in the case of pristine BNF. Time dependent DFT analysis reveals that the metal clusters can lower the transition energies associated with the dominant electronic transitions quite significantly thereby enabling the metal cluster supported BNF moieties to exhibit significant non-linear optical activity. Moreover, the studied systems demonstrate broad band absorption capability spanning the UV-visible as well as infra-red domains. Energy decomposition analysis reveals that the electrostatic interactions principally stabilize the metal cluster supported BNF moieties.

Long-Range Adiabatic Corrections to the Ground Molecular State of Alkali-Metal Dimers.

NASA Astrophysics Data System (ADS)

Marinescu, M.; Dalgarno, A.

1997-04-01

The structure of the long-range limit of the diagonal adiabatic corrections to the ground molecular state of diatomic molecules, may be expressed as a series of inverse powers of internuclear distance, R. The coefficients of this expansion are proportional to the inverse of the nuclear mass. Thus, they may be interpreted as a nuclear mass-dependent corrections to the dispersion coefficients. Using perturbation theory we have calculated the long-range coefficients of the diagonal adiabatic corrections up to the order of R-10. The final expressions are in terms of integrals over imaginary frequencies of products of atomic matrix elements involving Green's functions of complex energy. Thus, in our approach the molecular problem is reduced to an atomic one. Numerical evaluations have been done for all alkali-metal dimers. We acknowledge the support of the U.S. Dept. of Energy.

Optical properties from time-dependent current-density-functional theory: the case of the alkali metals Na, K, Rb, and Cs

NASA Astrophysics Data System (ADS)

Ferradás, R.; Berger, J. A.; Romaniello, Pina

2018-06-01

We present the optical conductivity as well as the electron-energy loss spectra of the alkali metals Na, K, Rb, and Cs calculated within time-dependent current-density functional theory. Our ab initio formulation describes from first principles both the Drude-tail and the interband absorption of these metals as well as the most dominant relativistic effects. We show that by using a recently derived current functional [Berger, Phys. Rev. Lett. 115, 137402 (2015)] we obtain an overall good agreement with experiment at a computational cost that is equivalent to the random-phase approximation. We also highlight the importance of the choice of the exchange-correlation potential of the ground state.

Development of operationally stable inverted organic light-emitting diode prepared without using alkali metals (Presentation Recording)

NASA Astrophysics Data System (ADS)

Fukagawa, Hirohiko; Morii, Katsuyuki; Hasegawa, Munehiro; Gouda, Shun; Tsuzuki, Toshimitsu; Shimizu, Takahisa; Yamamoto, Toshihiro

2015-10-01

The OLED is one of the key devices for realizing future flexible displays and lightings. One of the biggest challenges left for the OLED fabricated on a flexible substrate is the improvement of its resistance to oxygen and moisture. A high barrier layer [a water vapor transmission rate (WVTR) of about 10-6 g/m2/day] is proposed to be necessary for the encapsulation of conventional OLEDs. Some flexible high barrier layers have recently been demonstrated; however, such high barrier layers require a complex process, which makes flexible OLEDs expensive. If an OLED is prepared without using air-sensitive materials such as alkali metals, no stringent encapsulation is necessary for such an OLED. In this presentation, we will discuss our continuing efforts to develop an inverted OLED (iOLED) prepared without using alkali metals. iOLEDs with a bottom cathode are considered to be effective for realizing air-stable OLEDs since the electron injection layer (EIL) can be prepared by fabrication processes that might damage the organic layers, resulting in the enhanced range of materials suitable for EILs. We have demonstrated that a highly efficient and relatively air-stable iOLED can be realized by employing poly(ethyleneimine) as an EIL. Dark spot formation was not observed after 250 days in the poly(ethyleneimine)-based iOLED encapsulated by a barrier film with a WVTR of 10-4 g/m2/day. In addition, we have demonstrated the fabrication of a highly operational stable iOLED utilizing a newly developed EIL. The iOLED exhibits an expected half-lifetime of over 10,000 h from an initial luminance of 1,000 cd/m2.

[Novel process utilizing alkalis assisted hydrothermal process to stabilize heavy metals both from municipal solid waste or medical waste incinerator fly ash and waste water].

PubMed

Wang, Lei; Jin, Jian; Li, Xiao-dong; Chi, Yong; Yan, Jian-hua

2010-08-01

An alkalis assisted hydrothermal process was induced to stabilize heavy metals both from municipal solid waste or medical waste incinerator fly ash and waste water. The results showed that alkalis assisted hydrothermal process removed the heavy metals effectively from the waste water, and reduced leachability of fly ash after process. The heavy metal leachabilities of fly ash studied in this paper were Mn 17,300 microg/L,Ni 1650 microg/L, Cu 2560 microg/L, Zn 189,000 microg/L, Cd 1970 microg/L, Pb 1560 microg/L for medical waste incinerator fly ash; Mn 17.2 microg/L, Ni 8.32 microg/L, Cu 235.2 microg/L, Zn 668.3 microg/L, Cd 2.81 microg/L, Pb 7200 microg/L for municipal solid waste incinerator fly ash. After hydrothermal process with experimental condition [Na2CO3 dosage (5 g Na2CO3/50 g fly ash), reaction time = 10 h, L/S ratio = 10/1], the heavy metal removal efficiencies of medical waste incinerator fly ash were 86.2%-97.3%, and 94.7%-99.6% for municipal solid waste incinerator fly ash. The leachabilities of both two kinds of fly ash were lower than that of the Chinese national limit. The mechanism of heavy metal stabilization can be concluded to the chemisorption and physically encapsulation effects of aluminosilicates during its formation, crystallization and aging process, the high pH value has some contribution to the heavy metal removal and stabilization.

A theoretical study of the structure and thermochemical properties of alkali metal fluoroplumbates MPbF3.

PubMed

Boltalin, A I; Korenev, Yu M; Sipachev, V A

2007-07-19

Molecular constants of MPbF3 (M=Li, Na, K, Rb, and Cs) were calculated theoretically at the MP2(full) and B3LYP levels with the SDD (Pb, K, Rb, and Cs) and cc-aug-pVQZ (F, Li, and Na) basis sets to determine the thermochemical characteristics of the substances. Satisfactory agreement with experiment was obtained, including the unexpected nonmonotonic dependence of substance dissociation energies on the alkali metal atomic number. The bond lengths of the theoretical CsPbF3 model were substantially elongated compared with experimental estimates, likely because of errors in both theoretical calculations and electron diffraction data processing.

An efficient laser vaporization source for chemically modified metal clusters characterized by thermodynamics and kinetics

NASA Astrophysics Data System (ADS)

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.

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

PubMed

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.

Catalysis using hydrous metal oxide ion exchanges

DOEpatents

Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.

1985-01-01

In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

Catalysis using hydrous metal oxide ion exchangers

DOEpatents

Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

1983-07-21

In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

An alkali-metal ion extracted layered compound as a template for a metastable phase synthesis in a low-temperature solid-state reaction: preparation of brookite from K0.8Ti1.73Li0.27O4.

PubMed

Ozawa, Tadashi C; Sasaki, Takayoshi

2010-03-15

We have designed a new approach to synthesize brookite, i.e., to extract alkali-metal ions from K(0.8)Ti(1.73)Li(0.27)O(4) (KTLO) and to apply simultaneous heat treatment to the remaining lepidocrocite-type layers of TiO(6) octahedra. For the alkali-metal ion extraction and the simultaneous heat treatment, KTLO was heated at 400 degrees C with polytetrafluoroethylene (PTFE) in flowing Ar. PTFE has been found to be an effective agent to extract strongly electropositive alkali-metal ions from KTLO because of the strong electronegativity of F as its component. The product of this reaction consists of a mixture of brookite, K(2)CO(3), LiF, and PTFE derivatives, indicating the complete extraction of K(+) and Li(+) from KTLO and formation of brookite from the lepidocrocite-type layer of TiO(6) octahedra as a template. This brookite has a partial replacement of O(2-) with F(-) and/or slight oxygen deficiency; thus, its color is light-bluish gray. Fully oxidized brookite formation and complete decomposition of PTFE derivatives have been achieved by further heating in flowing air, and coproduced alkali-metal salts have been removed by washing in water. Powder X-ray diffraction, Raman spectroscopy, and chemical analysis results have confirmed that the final brookite product treated at 600 degrees C is single phase, and it is white. The method to extract alkali-metal ions from a crystalline material using PTFE is drastically different from the common methods such as soft-chemical and electrochemical reactions. It is likely that this new synthetic approach is applicable to other layered systems to prepare a diverse family of compounds, including novel metastable ones.

Time-Dependent Thomas-Fermi Approach for Electron Dynamics in Metal Clusters

NASA Astrophysics Data System (ADS)

Domps, A.; Reinhard, P.-G.; Suraud, E.

1998-06-01

We propose a time-dependent Thomas-Fermi approach to the (nonlinear) dynamics of many-fermion systems. The approach relies on a hydrodynamical picture describing the system in terms of collective flow. We investigate in particular an application to electron dynamics in metal clusters. We make extensive comparisons with fully fledged quantal dynamical calculations and find overall good agreement. The approach thus provides a reliable and inexpensive scheme to study the electronic response of large metal clusters.

Protein-protected luminescent noble metal quantum clusters: an emerging trend in atomic cluster nanoscience

PubMed Central

Xavier, Paulrajpillai Lourdu; Chaudhari, Kamalesh; Baksi, Ananya; Pradeep, Thalappil

2012-01-01

Noble metal quantum clusters (NMQCs) are the missing link between isolated noble metal atoms and nanoparticles. NMQCs are sub-nanometer core sized clusters composed of a group of atoms, most often luminescent in the visible region, and possess intriguing photo-physical and chemical properties. A trend is observed in the use of ligands, ranging from phosphines to functional proteins, for the synthesis of NMQCs in the liquid phase. In this review, we briefly overview recent advancements in the synthesis of protein protected NMQCs with special emphasis on their structural and photo-physical properties. In view of the protein protection, coupled with direct synthesis and easy functionalization, this hybrid QC-protein system is expected to have numerous optical and bioimaging applications in the future, pointers in this direction are visible in the literature. PMID:22312454

Monte Carlo simulation of the mixed alkali effect with cooperative jumps

NASA Astrophysics Data System (ADS)

Habasaki, Junko; Hiwatari, Yasuaki

2000-12-01

In our previous works on molecular dynamics (MD) simulations of lithium metasilicate (Li2SiO3), it has been shown that the long time behavior of the lithium ions in Li2SiO3 has been characterized by the component showing the enhanced diffusion (Lévy flight) due to cooperative jumps. It has also been confirmed that the contribution of such component decreases by interception of the paths in the mixed alkali silicate (LiKSiO3). Namely, cooperative jumps of like ions are much decreased in number owing to the interception of the path for unlike alkali-metal ions. In the present work, we have performed a Monte Carlo simulation using a cubic lattice in order to establish the role of the cooperative jumps in the transport properties in a mixed alkali glass. Fixed particles (blockage) were introduced instead of the interception of the jump paths for unlike alkali-metal ions. Two types of cooperative motions (a pull type and a push type) were taken into account. Low-dimensionality of the jump path caused by blockage resulted in a decrease of a diffusion coefficient of the particles. The effect of blockage is enhanced when the cooperative motions were introduced.

In situ alkali-silica reaction observed by x-ray microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurtis, K.E.; Monteiro, P.J.M.; Brown, J.T.

1997-04-01

In concrete, alkali metal ions and hydroxyl ions contributed by the cement and reactive silicates present in aggregate can participate in a destructive alkali-silica reaction (ASR). This reaction of the alkalis with the silicates produces a gel that tends to imbibe water found in the concrete pores, leading to swelling of the gel and eventual cracking of the affected concrete member. Over 104 cases of alkali-aggregate reaction in dams and spillways have been reported around the world. At present, no method exists to arrest the expansive chemical reaction which generates significant distress in the affected structures. Most existing techniques availablemore » for the examination of concrete microstructure, including ASR products, demand that samples be dried and exposed to high pressure during the observation period. These sample preparation requirements present a major disadvantage for the study of alkali-silica reaction. Given the nature of the reaction and the affect of water on its products, it is likely that the removal of water will affect the morphology, creating artifacts in the sample. The purpose of this research is to observe and characterize the alkali-silica reaction, including each of the specific reactions identified previously, in situ without introducing sample artifacts. For observation of unconditioned samples, x-ray microscopy offers an opportunity for such an examination of the alkali-silica reaction. Currently, this investigation is focusing on the effect of calcium ions on the alkali-silica reaction.« less

Growth Behavior and Electronic Structure of Noble Metal-Doped Germanium Clusters.

PubMed

Mahtout, Sofiane; Siouani, Chaouki; Rabilloud, Franck

2018-01-18

Structures, energetics, and electronic properties of noble metal-doped germanium (MGe n with M = Cu, Ag, Au; n = 1-19) clusters are systematically investigated by using the density functional theory (DFT) approach. The endohedral structures in which the metal atom is encapsulated inside of a germanium cage appear at n = 10 when the dopant is Cu and n = 12 for M = Ag and Au. While Cu doping enhances the stability of the corresponding germanium frame, the binding energies of AgGe n and AuGe n are always lower than those of pure germanium clusters. Our results highlight the great stability of the CuGe 10 cluster in a D 4d structure and, to a lesser extent, that of AgGe 15 and AuGe 15 , which exhibits a hollow cage-like geometry. The sphere-type geometries obtained for n = 10-15 present a peculiar electronic structure in which the valence electrons of the noble metal and Ge atoms are delocalized and exhibit a shell structure associated with the quasi-spherical geometry. It is found that the coinage metal is able to give both s- and d-type electrons to be reorganized together with the valence electrons of Ge atoms through a pooling of electrons. The cluster size dependence of the stability, the frontier orbital energy gap, the vertical ionization potentials, and electron affinities are given.

SnO2 promoted by alkali metal oxides for soot combustion: The effects of surface oxygen mobility and abundance on the activity

NASA Astrophysics Data System (ADS)

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.

The most metal-poor Galactic globular cluster: the first spectroscopic observations of ESO280-SC06

NASA Astrophysics Data System (ADS)

Simpson, Jeffrey D.

2018-07-01

We present the first spectroscopic observations of the very metal-poor Milky Way globular cluster ESO280-SC06. Using spectra acquired with the 2dF/AAOmega spectrograph on the Anglo-Australian Telescope, we have identified 13 members of the cluster, and estimate from their infrared calcium triplet lines that the cluster has a metallicity of [Fe/H]=-2.48^{+0.06 }_{ -0.11}. This would make it the most metal-poor globular cluster known in the Milky Way. This result was verified with comparisons to three other metal-poor globular clusters that had been observed and analysed in the same manner. We also present new photometry of the cluster from EFOSC2 and SkyMapper and confirm that the cluster is located 22.9 ± 2.1 kpc from the Sun and 15.2 ± 2.1 kpc from the Galactic Centre, and has a radial velocity of 92.5^{+2.4 }_{ -1.6} km s-1. These new data finds the cluster to have a radius about half that previously estimated, and we find that the cluster has a dynamical mass of the cluster of (12 ± 2) × 103 M⊙. Unfortunately, we lack reliable proper motions to fully characterize its orbit about the Galaxy. Intriguingly, the photometry suggests that the cluster lacks a well-populated horizontal branch, something that has not been observed in a cluster so ancient or metal poor.

The most metal-poor Galactic globular cluster: the first spectroscopic observations of ESO280-SC06

NASA Astrophysics Data System (ADS)

Simpson, Jeffrey D.

2018-04-01

We present the first spectroscopic observations of the very metal-poor Milky Way globular cluster ESO280-SC06. Using spectra acquired with the 2dF/AAOmega spectrograph on the Anglo-Australian Telescope, we have identified 13 members of the cluster, and estimate from their infrared calcium triplet lines that the cluster has a metallicity of [Fe/H]={-2.48}^{+0.06}_{-0.11}. This would make it the most metal-poor globular cluster known in the Milky Way. This result was verified with comparisons to three other metal-poor globular clusters that had been observed and analyzed in the same manner. We also present new photometry of the cluster from EFOSC2 and SkyMapper and confirm that the cluster is located 22.9 ± 2.1 kpc from the Sun and 15.2 ± 2.1 kpc from the Galactic centre, and has a radial velocity of 92.5 + 2.4-1.6 km s-1. These new data finds the cluster to have a radius about half that previously estimated, and we find that the cluster has a dynamical mass of the cluster of (12 ± 2) × 103 M⊙. Unfortunately, we lack reliable proper motions to fully characterize its orbit about the Galaxy. Intriguingly, the photometry suggests that the cluster lacks a well-populated horizontal branch, something that has not been observed in a cluster so ancient or metal-poor.

LOW-METALLICITY YOUNG CLUSTERS IN THE OUTER GALAXY. II. SH 2-208

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yasui, Chikako; Kobayashi, Naoto; Izumi, Natsuko

We obtained deep near-infrared images of Sh 2-208, one of the lowest-metallicity H ii regions in the Galaxy, [O/H] = −0.8 dex. We detected a young cluster in the center of the H ii region with a limiting magnitude of K = 18.0 mag (10 σ ), which corresponds to a mass detection limit of ∼0.2 M {sub ⊙}. This enables the comparison of star-forming properties under low metallicity with those of the solar neighborhood. We identified 89 cluster members. From the fitting of the K -band luminosity function (KLF), the age and distance of the cluster are estimated to be ∼0.5more » Myr and ∼4 kpc, respectively. The estimated young age is consistent with the detection of strong CO emission in the cluster region and the estimated large extinction of cluster members ( A{sub V}  ∼ 4–25 mag). The observed KLF suggests that the underlying initial mass function (IMF) of the low-metallicity cluster is not significantly different from canonical IMFs in the solar neighborhood in terms of both high-mass slope and IMF peak (characteristic mass). Despite the very young age, the disk fraction of the cluster is estimated at only 27% ± 6%, which is significantly lower than those in the solar metallicity. Those results are similar to Sh 2-207, which is another star-forming region close to Sh 2-208 with a separation of 12 pc, suggesting that their star-forming activities in low-metallicity environments are essentially identical to those in the solar neighborhood, except for the disk dispersal timescale. From large-scale mid-infrared images, we suggest that sequential star formation is taking place in Sh 2-207, Sh 2-208, and the surrounding region, triggered by an expanding bubble with a ∼30 pc radius.« less

Formation of the metal and energy-carrier price clusters on the world market of nonferrous metals in the postcrisis period

NASA Astrophysics Data System (ADS)

Bogdanov, S. V.; Shevelev, I. M.; Chernyi, S. A.

2016-06-01

The laws of formation of price clusters are revealed upon statistical processing of the data on changing the quotation prices of nonferrous and precious metals, oil, black oil, gasoline, and natural gas in the postcrisis period from January 1, 2009 to November 1, 2013. It is found that the metal prices entering in the price cluster of nonferrous metals most strongly affect the formation of the nonferrous metal price and that the prices of precious metals and energy carriers correct the exchange price of the metal to some extent but do not determine its formation. Equations are derived to calculate the prices. The results of calculation by these equations agree well with the real nonferrous metal prices in the near future.

Using numerical simulations to study the ICM metallicity fields in clusters and groups

NASA Astrophysics Data System (ADS)

Mazzei, Renato; Vijayaraghavan, Rukmani; Sarazin, Craig L.

2018-01-01

Most baryonic matter in clusters resides in the intracluster medium (ICM) as hot and diffuse gas. The metal content of this gas is deposited from dying stars, typically synthesized in type Ia or core-collapse supernovae. The ICM gas traces the formation history of the cluster and the compositional signature of its constituent galaxies as a function of time. Studying the metallicity content thus aids in understanding the gradual evolution of the cluster as it is constructed. Within this framework, galaxy and star formation and evolution can be studied by tracing metals in the ICM. In this work we use numerical simulations to study the evolution of ICM metallicity due to the stripping of galaxies’ gas. We model metallicity fields using cloud-in-cell techniques, to determine the ratio between the mass of particles tracing galaxy outflows and the mass of ICM gas at different spatial locations in each simulation time step. Integrated abundance maps are produced. We then project photons and construct mock X-ray images to investigate the relationship between ICM metallicity and observable information.

Effective cluster model of dielectric enhancement in metal-insulator composites

NASA Astrophysics Data System (ADS)

Doyle, W. T.; Jacobs, I. S.

1990-11-01

The electrical permittivity of a suspension of conducting spheres at high volume loading exhibits a large enhancement above the value predicted by the Clausius-Mossotti approximation. The permittivity enhancement is a dielectric anomaly accompanying a metallization transition that occurs when conducting particles are close packed. In disordered suspensions, close encounters can cause a permittivity enhancement at any volume loading. We attribute the permittivity enhancements typically observed in monodisperse disordered suspensions of conducting spheres to local metallized regions of high density produced by density fluctuations. We model a disordered suspension as a mixture, or mesosuspension, of isolated spheres and random close-packed spherical clusters of arbitrary size. Multipole interactions within the clusters are treated exactly. External interactions between clusters and isolated spheres are treated in the dipole approximation. Model permittivities are compared with Guillien's experimental permittivity measurements [Ann. Phys. (Paris) Ser. 11, 16, 205 (1941)] on liquid suspensions of Hg droplets in oil and with Turner's conductivity measurements [Chem. Eng. Sci. 31, 487 (1976)] on fluidized bed suspensions of ion-exchange resin beads in aqueous solution. New permittivity measurements at 10 GHz on solid suspensions of monodisperse metal spheres in polyurethane are presented and compared with the model permittivities. The effective spherical cluster model is in excellent agreement with the experiments over the entire accessible range of volume loading.

Multiple populations in more metal-rich galactic globular clusters

NASA Astrophysics Data System (ADS)

Cordero, Maria J.

In this thesis we present chemical abundances for bright stars in the intermediate metallicity globular cluster (GC) M5, and the relatively metal-rich GCs M71 and 47 Tuc with the goal of improving the understanding of chemical evolution in the metallicity regime sampled by these three GCs. The first chapter presents a brief historical overview in light element abundance variations in globular clusters. In the second chapter we present the results obtained for 47 Tuc, the most-metal rich cluster of my sample. 47 Tuc is an ideal target to study chemical evolution and GC formation in massive more metal-rich GCs since it is the closest massive GC. Chemical abundances for O, Na, Al, Si, Ca, Ti, Fe, Ni, La, and Eu were determined for 164 red giant branch (RGB) stars in 47 Tuc using spectra obtained with both the Hydra multi-fiber spectrograph at the Blanco 4-m telescope and the FLAMES multi-object spectrograph at the ESO Very Large Telescope. The average [Fe/H]= --0.79+/-0.09 dex is consistent with literature values, as well as over-abundances of alpha-elements ([alpha/Fe] ~ 0.3 dex). The n-capture process elements indicate that 47 Tuc is r-process dominated ([Eu/La]=+0.24), and the light elements O, Na, and Al exhibit star-to-star variations. The Na-O anti-correlation, a signature typically seen in Galactic GCs, is present in 47 Tuc, and extends to include a small number of stars with [O/Fe] ~ --0.5. Additionally, the [O/Na] ratios of our sample reveal that the cluster stars can be separated into three distinct populations. A KS-test demonstrates that the O-poor/Na-rich stars are more centrally concentrated than the O-rich/Na-poor stars. The observed number and radial distribution of 47 Tuc's stellar populations, as distinguished by their light element composition, agrees closely with the results obtained from photometric data. We do not find evidence supporting a strong Na-Al correlation in 47 Tuc, which is consistent with current models of AGB nucleosynthesis yields

Clusters, Assemble: Growth of Intermetallic Compounds from Metal Flux Reactions.

PubMed

Latturner, Susan E

2018-01-16

Metal flux synthesis involves the reaction of metals and metalloids in a large excess of a low-melting metal that acts as a solvent. This technique makes use of an unusual temperature regime (above the temperatures used for solvothermal methods and below the temperatures used in traditional solid state synthesis) and facilitates the growth of products as large crystals. It has proven to be a fruitful method to discover new intermetallic compounds. However, little is known about the chemistry occurring within a molten metal solvent; without an understanding of the nature of precursor formation and assembly, it is difficult to predict product structures and target properties. Organic chemists have a vast toolbox of well-known reagents and reaction mechanisms to use in directing their synthesis toward a desired molecular structure. This is not yet the case for the synthesis of inorganic extended structures. We have carried out extensive explorations of the growth of new magnetic intermetallic compounds from a variety of metal fluxes. This Account presents a review of some of our results and recent reports by other groups; this work indicates that products with common building blocks and homologous series with identical structural motifs are repeatedly seen in metal flux chemistry. For instance, fluorite-type layers comprised of transition metals coordinated by eight main group metal atoms are found in the Th 2 (Au x Si 1-x )[AuAl 2 ] n Si 2 and R[AuAl 2 ] n Al 2 (Au x Si 1-x ) 2 series grown from aluminum flux, the Ce n PdIn 3n+2 series grown from indium flux, and CePdGa 6 and Ce 2 PdGa 10 grown from gallium flux. Similarly, our investigations of reactions of heavy main group metals, M, in rare earth/transition metal eutectic fluxes reveal that the R/T/M/M' products usually feature M-centered rare earth clusters M@R 8-12 , which share faces to form layers and networks that surround transition metal building blocks. These structural trends, temperature dependence of

PROCESSING OF URANIUM-METAL-CONTAINING FUEL ELEMENTS

DOEpatents

Moore, R.H.

1962-10-01

A process is given for recovering uranium from neutronbombarded uranium- aluminum alloys. The alloy is dissolved in an aluminum halide--alkali metal halide mixture in which the halide is a mixture of chloride and bromide, the aluminum halide is present in about stoichiometric quantity as to uranium and fission products and the alkali metal halide in a predominant quantity; the uranium- and electropositive fission-products-containing salt phase is separated from the electronegative-containing metal phase; more aluminum halide is added to the salt phase to obtain equimolarity as to the alkali metal halide; adding an excess of aluminum metal whereby uranium metal is formed and alloyed with the excess aluminum; and separating the uranium-aluminum alloy from the fission- productscontaining salt phase. (AEC)

Mass Spectroscopy of Neutral Metal Oxide Clusters Using a Desk-Top Soft X-Ray Laser

NASA Astrophysics Data System (ADS)

Dong, F.; Heinbuch, S.; Bernstein, E. R.; Rocca, J. J.

We report the use of a compact 46.9 nm capillary discharge soft x-ray laser in the study of metal-oxide nanoclusters using mass spectroscopy. Transition metal oxides are widely used as heterogeneous catalysts and catalytic supports in industrial processes. There are numerous applications for transition metal oxide catalysts, and although they are widely used, there is a lack of fundamental understanding of the complicated processes that occur on the metal oxide surface during catalysis. Conventional nanocluster spectroscopy techniques have used 193 nm radiation from an ArF excimer laser corresponding to a photon energy of 6.4 eV in order to photoionize a sample. Typical metal oxide nanocluster ionization energies fall into the range of 7-12 eV while some have even higher energies. Therefore a single 6.4 eV photon can not ionize the cluster making multiphoton processes the dominant ionization method. A major problem associated with mass spectroscopy can become evident during the multiphoton ionization of clusters. Specifically, the clusters may fragment during the ionization process and the identification of the neutral parent cluster can become difficult. In the present experiment neutral vanadium, niobium and tantalum oxide clusters are studied by single photon ionization with the 26.5 eV photons produced by a capillary discharge soft x-ray laser.1 During ionization, the metal oxide clusters are observed to be almost free of serious fragmentation. The most stable neutral cluster of vanadium, niobium, and tantalum oxide growth in a saturated oxygen condition are identified as MO2, M2O4/M2O5, M3O7, M4O10, M5O12, M6O15, M7O17, M8O20, and M9O22, which can be represented as a form (MO2)0,1(M2O5)y. M2O5 is identified as a basic unit to build-up the three kinds of metal oxide clusters. In the case of niobium and tantalum oxide clusters, the oxygen-deficient clusters with a structure of (MO2)2(M2O5)y are detected for groups that contain an even number of metal atoms. For

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)

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 andmore » 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.« less

FAST TRACK COMMUNICATION: Poly(methyl methacrylate)-palladium clusters nanocomposite formation by supersonic cluster beam deposition: a method for microstructured metallization of polymer surfaces

NASA Astrophysics Data System (ADS)

Ravagnan, Luca; Divitini, Giorgio; Rebasti, Sara; Marelli, Mattia; Piseri, Paolo; Milani, Paolo

2009-04-01

Nanocomposite films were fabricated by supersonic cluster beam deposition (SCBD) of palladium clusters on poly(methyl methacrylate) (PMMA) surfaces. The evolution of the electrical conductance with cluster coverage and microscopy analysis show that Pd clusters are implanted in the polymer and form a continuous layer extending for several tens of nanometres beneath the polymer surface. This allows the deposition, using stencil masks, of cluster-assembled Pd microstructures on PMMA showing a remarkably high adhesion compared with metallic films obtained by thermal evaporation. These results suggest that SCBD is a promising tool for the fabrication of metallic microstructures on flexible polymeric substrates.

Binding selectivity of dibenzo-18-crown-6 for alkali metal cations in aqueous solution: A density functional theory study using a continuum solvation model.

PubMed

Choi, Chang Min; Heo, Jiyoung; Kim, Nam Joon

2012-08-08

Dibenzo-18-crown-6 (DB18C6) exhibits the binding selectivity for alkali metal cations in solution phase. In this study, we investigate the main forces that determine the binding selectivity of DB18C6 for the metal cations in aqueous solution using the density functional theory (DFT) and the conductor-like polarizable continuum model (CPCM). The bond dissociation free energies (BDFE) of DB18C6 complexes with alkali metal cations (M+-DB18C6, M = Li, Na, K, Rb, and Cs) in aqueous solution are calculated at the B3LYP/6-311++G(d,p)//B3LYP/6-31 + G(d) level using the CPCM. It is found that the theoretical BDFE is the largest for K+-DB18C6 and decreases as the size of the metal cation gets larger or smaller than that of K+, which agrees well with previous experimental results. The solvation energy of M+-DB18C6 in aqueous solution plays a key role in determining the binding selectivity of DB18C6. In particular, the non-electrostatic dispersion interaction between the solute and solvent, which depends strongly on the complex structure, is largely responsible for the different solvation energies of M+-DB18C6. This study shows that the implicit solvation model like the CPCM works reasonably well in predicting the binding selectivity of DB18C6 in aqueous solution.

Alkali-Metal-Mediated Magnesiations of an N-Heterocyclic Carbene: Normal, Abnormal, and "Paranormal" Reactivity in a Single Tritopic Molecule.

PubMed

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.

Geographic clustering of elevated blood heavy metal levels in pregnant women.

PubMed

King, Katherine E; Darrah, Thomas H; Money, Eric; Meentemeyer, Ross; Maguire, Rachel L; Nye, Monica D; Michener, Lloyd; Murtha, Amy P; Jirtle, Randy; Murphy, Susan K; Mendez, Michelle A; Robarge, Wayne; Vengosh, Avner; Hoyo, Cathrine

2015-10-09

Cadmium (Cd), lead (Pb), mercury (Hg), and arsenic (As) exposure is ubiquitous and has been associated with higher risk of growth restriction and cardiometabolic and neurodevelopmental disorders. However, cost-efficient strategies to identify at-risk populations and potential sources of exposure to inform mitigation efforts are limited. The objective of this study was to describe the spatial distribution and identify factors associated with Cd, Pb, Hg, and As concentrations in peripheral blood of pregnant women. Heavy metals were measured in whole peripheral blood of 310 pregnant women obtained at gestational age ~12 weeks. Prenatal residential addresses were geocoded and geospatial analysis (Getis-Ord Gi* statistics) was used to determine if elevated blood concentrations were geographically clustered. Logistic regression models were used to identify factors associated with elevated blood metal levels and cluster membership. Geospatial clusters for Cd and Pb were identified with high confidence (p-value for Gi* statistic <0.01). The Cd and Pb clusters comprised 10.5 and 9.2 % of Durham County residents, respectively. Medians and interquartile ranges of blood concentrations (μg/dL) for all participants were Cd 0.02 (0.01-0.04), Hg 0.03 (0.01-0.07), Pb 0.34 (0.16-0.83), and As 0.04 (0.04-0.05). In the Cd cluster, medians and interquartile ranges of blood concentrations (μg/dL) were Cd 0.06 (0.02-0.16), Hg 0.02 (0.00-0.05), Pb 0.54 (0.23-1.23), and As 0.05 (0.04-0.05). In the Pb cluster, medians and interquartile ranges of blood concentrations (μg/dL) were Cd 0.03 (0.02-0.15), Hg 0.01 (0.01-0.05), Pb 0.39 (0.24-0.74), and As 0.04 (0.04-0.05). Co-exposure with Pb and Cd was also clustered, the p-values for the Gi* statistic for Pb and Cd was <0.01. Cluster membership was associated with lower education levels and higher pre-pregnancy BMI. Our data support that elevated blood concentrations of Cd and Pb are spatially clustered in this urban environment compared to

Binary Alkali-Metal Silicon Clathrates by Spark Plasma Sintering: Preparation and Characterization

PubMed Central

Veremchuk, Igor; Beekman, Matt; Antonyshyn, Iryna; Schnelle, Walter; Baitinger, Michael; Nolas, George S.; Grin, Yuri

2016-01-01

The binary intermetallic clathrates K8-xSi46 (x = 0.4; 1.2), Rb6.2Si46, Rb11.5Si136 and Cs7.8Si136 were prepared from M4Si4 (M = K, Rb, Cs) precursors by spark-plasma route (SPS) and structurally characterized by Rietveld refinement of PXRD data. The clathrate-II phase Rb11.5Si136 was synthesized for the first time. Partial crystallographic site occupancy of the alkali metals, particularly for the smaller Si20 dodecahedra, was found in all compounds. SPS preparation of Na24Si136 with different SPS current polarities and tooling were performed in order to investigate the role of the electric field on clathrate formation. The electrical and thermal transport properties of K7.6Si46 and K6.8Si46 in the temperature range 4–700 K were investigated. Our findings demonstrate that SPS is a novel tool for the synthesis of intermetallic clathrate phases that are not easily accessible by conventional synthesis techniques. PMID:28773710

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

PubMed Central

Boughlala, Zakaria; Fonseca Guerra, Célia

2016-01-01

Abstract 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. PMID:27551660

Reversible thermodynamic cycle for AMTEC power conversion. [Alkali Metal Thermal-to-Electric Converter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vining, C.B.; Williams, R.M.; Underwood, M.L.

1993-10-01

An AMTEC cell, may be described as performing two distinct energy conversion processes: (i) conversion of heat to mechanical energy via a sodium-based heat engine and (ii) conversion of mechanical energy to electrical energy by utilizing the special properties of the electrolyte material. The thermodynamic cycle appropriate to an alkali metal thermal-to-electric converter cell is discussed for both liquid- and vapor-fed modes of operation, under the assumption that all processes can be performed reversibly. In the liquid-fed mode, the reversible efficiency is greater than 89.6% of Carnot efficiency for heat input and rejection temperatures (900--1,300 and 400--800 K, respectively) typicalmore » of practical devices. Vapor-fed cells can approach the efficiency of liquid-fed cells. Quantitative estimates confirm that the efficiency is insensitive to either the work required to pressurize the sodium liquid or the details of the state changes associated with cooling the low pressure sodium gas to the heat rejection temperature.« less

Probing C-O bond activation on gas-phase transition metal clusters: Infrared multiple photon dissociation spectroscopy of Fe, Ru, Re, and W cluster CO complexes

NASA Astrophysics Data System (ADS)

Lyon, Jonathan T.; Gruene, Philipp; Fielicke, André; Meijer, Gerard; Rayner, David M.

2009-11-01

The binding of carbon monoxide to iron, ruthenium, rhenium, and tungsten clusters is studied by means of infrared multiple photon dissociation spectroscopy. The CO stretching mode is used to probe the interaction of the CO molecule with the metal clusters and thereby the activation of the C-O bond. CO is found to adsorb molecularly to atop positions on iron clusters. On ruthenium and rhenium clusters it also binds molecularly. In the case of ruthenium, binding is predominantly to atop sites, however higher coordinated CO binding is also observed for both metals and becomes prevalent for rhenium clusters containing more than nine atoms. Tungsten clusters exhibit a clear size dependence for molecular versus dissociative CO binding. This behavior denotes the crossover to the purely dissociative CO binding on the earlier transition metals such as tantalum.

The alkali metal thermoelectric converter /AMTEC/ - A new direct energy conversion technology for aerospace power

NASA Technical Reports Server (NTRS)

Bankston, C. P.; Cole, T.; Jones, R.; Ewell, R.

1982-01-01

A thermally regenerative electrochemical device for the direct conversion of heat to electrical energy, the alkali metal thermoelectric converter (AMTEC), is characterized by potential efficiencies on the order of 15-40% and possesses no moving parts, making it a candidate for space power system applications. Device conversion efficiency is projected on the basis of experimental voltage vs current curves exhibiting power densities of 0.7 W/sq cm and measured electrode efficiencies of up to 40%. Preliminary radiative heat transfer measurements presented may be used in an investigation of methods for the reduction of AMTEC parasitic radiation losses. AMTEC assumes heat input and rejection temperatures of 900-1300 K and 400-800 K, respectively. The working fluid is liquid sodium, and the porous electrode employed is of molybdenum.

Formation of metallic magnetic clusters in a Kondo-lattice metal: Evidence from an optical study

PubMed Central

Kovaleva, N. N.; Kugel, K. I.; Bazhenov, A. V.; Fursova, T. N.; Löser, W.; Xu, Y.; Behr, G.; Kusmartsev, F. V.

2012-01-01

Magnetic materials are usually divided into two classes: those with localised magnetic moments, and those with itinerant charge carriers. We present a comprehensive experimental (spectroscopic ellipsomerty) and theoretical study to demonstrate that these two types of magnetism do not only coexist but complement each other in the Kondo-lattice metal, Tb2PdSi3. In this material the itinerant charge carriers interact with large localised magnetic moments of Tb(4f) states, forming complex magnetic lattices at low temperatures, which we associate with self-organisation of magnetic clusters. The formation of magnetic clusters results in low-energy optical spectral weight shifts, which correspond to opening of the pseudogap in the conduction band of the itinerant charge carriers and development of the low- and high-spin intersite electronic transitions. This phenomenon, driven by self-trapping of electrons by magnetic fluctuations, could be common in correlated metals, including besides Kondo-lattice metals, Fe-based and cuprate superconductors. PMID:23189239

Experiment and simulation study on alkalis transfer characteristic during direct combustion utilization of bagasse.

PubMed

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.

Radial metal abundance profiles in the intra-cluster medium of cool-core galaxy clusters, groups, and ellipticals

NASA Astrophysics Data System (ADS)

Mernier, F.; de Plaa, J.; Kaastra, J. S.; Zhang, Y.-Y.; Akamatsu, H.; Gu, L.; Kosec, P.; Mao, J.; Pinto, C.; Reiprich, T. H.; Sanders, J. S.; Simionescu, A.; Werner, N.

2017-07-01

The hot intra-cluster medium (ICM) permeating galaxy clusters and groups is not pristine, as it has been continuously enriched by metals synthesised in Type Ia (SNIa) and core-collapse (SNcc) supernovae since the major epoch of star formation (z ≃ 2-3). The cluster/group enrichment history and mechanisms responsible for releasing and mixing the metals can be probed via the radial distribution of SNIa and SNcc products within the ICM. In this paper, we use deep XMM-Newton/EPIC observations from a sample of 44 nearby cool-core galaxy clusters, groups, and ellipticals (CHEERS) to constrain the average radial O, Mg, Si, S, Ar, Ca, Fe, and Ni abundance profiles. The radial distributions of all these elements, averaged over a large sample for the first time, represent the best constrained profiles available currently. Specific attention is devoted to a proper modelling of the EPIC spectral components, and to other systematic uncertainties that may affect our results. We find an overall decrease of the Fe abundance with radius out to 0.9 r500 and 0.6 r500 for clusters and groups, respectively, in good agreement with predictions from the most recent hydrodynamical simulations. The average radial profiles of all the other elements (X) are also centrally peaked and, when rescaled to their average central X/Fe ratios, follow well the Fe profile out to at least 0.5 r500. As predicted by recent simulations, we find that the relative contribution of SNIa (SNcc) to the total ICM enrichment is consistent with being uniform at all radii, both for clusters and groups using two sets of SNIa and SNcc yield models that reproduce the X/Fe abundance pattern in the core well. In addition to implying that the central metal peak is balanced between SNIa and SNcc, our results suggest that the enriching SNIa and SNcc products must share the same origin and that the delay between the bulk of the SNIa and SNcc explosions must be shorter than the timescale necessary to diffuse out the metals

Delayed Ionization in Transition Metal Carbon Clusters

NASA Astrophysics Data System (ADS)

Kooi, S. E.; Castleman, A. W., Jr.

1997-03-01

Mass spectrometric studies of several single and binary transition metal carbon cluster systems, produced in a laser vaporization source, reveal several species that undergo delayed ionization. Pulsed extraction and blocking electric fields, in a time-of-flight mass spectrometer, allow the study of delayed ionization over a time window after excitation with a pulsed laser. In systems where metallocarbohedrenes (Met-Cars) are produced, the Met-Cars are the dominate delayed species. Delayed ionization of binary metal Met-Cars Ti_xM_yC_12 (M=Zr,Nb,Y; x+y=8) is dependent on the ratio of the two metals. Delayed behavior is investigated over a range of photoionization wavelengths and fluences. In order to determine the degree to which the delayed ionization is thermionic in character, the experimental data have been compared to Klots's model for thermionic emission from small particles.

Globular Cluster Abundances from High-resolution, Integrated-light Spectroscopy. II. Expanding the Metallicity Range for Old Clusters and Updated Analysis Techniques

NASA Astrophysics Data System (ADS)

Colucci, Janet E.; Bernstein, Rebecca A.; McWilliam, Andrew

2017-01-01

We present abundances of globular clusters (GCs) in the Milky Way and Fornax from integrated-light (IL) spectra. Our goal is to evaluate the consistency of the IL analysis relative to standard abundance analysis for individual stars in those same clusters. This sample includes an updated analysis of seven clusters from our previous publications and results for five new clusters that expand the metallicity range over which our technique has been tested. We find that the [Fe/H] measured from IL spectra agrees to ˜0.1 dex for GCs with metallicities as high as [Fe/H] = -0.3, but the abundances measured for more metal-rich clusters may be underestimated. In addition we systematically evaluate the accuracy of abundance ratios, [X/Fe], for Na I, Mg I, Al I, Si I, Ca I, Ti I, Ti II, Sc II, V I, Cr I, Mn I, Co I, Ni I, Cu I, Y II, Zr I, Ba II, La II, Nd II, and Eu II. The elements for which the IL analysis gives results that are most similar to analysis of individual stellar spectra are Fe I, Ca I, Si I, Ni I, and Ba II. The elements that show the greatest differences include Mg I and Zr I. Some elements show good agreement only over a limited range in metallicity. More stellar abundance data in these clusters would enable more complete evaluation of the IL results for other important elements. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Alkali and alkaline earth metallic (AAEM) species leaching and Cu(II) sorption by biochar.

PubMed

Li, Mi; Lou, Zhenjun; Wang, Yang; Liu, Qiang; Zhang, Yaping; Zhou, Jizhi; Qian, Guangren

2015-01-01

Alkali and alkaline earth metallic (AAEM) species water leaching and Cu(II) sorption by biochar prepared from two invasive plants, Spartina alterniflora (SA) and water hyacinth (WH), were explored in this work. Significant amounts of Na and K can be released (maximum leaching for Na 59.0 mg g(-1) and K 79.9 mg g(-1)) from SA and WH biochar when they are exposed to contact with water. Cu(II) removal by biochar is highly related with pyrolysis temperature and environmental pH with 600-700 °C and pH of 6 showing best performance (29.4 and 28.2 mg g(-1) for SA and WH biochar). Cu(II) sorption exerts negligible influence on Na/K/Mg leaching but clearly promotes the release of Ca. Biochars from these two plant species provide multiple benefits, including nutrient release (K), heavy metal immobilization as well as promoting the aggregation of soil particles (Ca) for soil amelioration. AAEM and Cu(II) equilibrium concentrations in sorption were analyzed by positive matrix factorization (PMF) to examine the factors underlying the leaching and sorption behavior of biochar. The identified factors can provide insightful understanding on experimental phenomena. Copyright © 2014 Elsevier Ltd. All rights reserved.

Photosensitized Reduction of Carbon Dioxide in Solution Using Noble-Metal Clusters for Electron Transfer

NASA Astrophysics Data System (ADS)

Toshima, Naoki; Yamaji, Yumi; Teranishi, Toshiharu; Yonezawa, Tetsu

1995-03-01

Carbon dioxide was reduced to methane by visible-light irradiation of a solution composed of tris(bipyridine)ruthenium(III) as photosensitizer, ethylenediaminetetraacetic acid disodium salt as sacrificial reagent, methyl viologen as electron relay, and a colloidal dispersion of polymer-protected noble-metal clusters, prepared by alcohol-reduction, as catalyst. Among the noble-metal clusters examined, Pt clusters showed the highest activity for the formation of methane as well as hydrogen. In order to improve the activity, oxidized clusters and bimetallic clusters were also applied. For example, the CH4 yield in 3-h irradiation increased from 51 x 10-3 μmol with unoxidized Pt clusters to 72 x 10-3 μmol with partially oxidized ones. In the case of Pt/Ru bimetalic systems, the improvement of the catalytic activity by air treatment was much greater than in case of monometallic clusters.

Alkali silica reaction (ASR) in cement free alkali activated sustainable concrete.

DOT National Transportation Integrated Search

2016-12-19

This report summarizes the findings of an experimental evaluation into alkali silica : reaction (ASR) in cement free alkali-activated slag and fly ash binder concrete. The : susceptibility of alkali-activated fly ash and slag concrete binders to dele...

Method of bonding metals to ceramics and other materials

DOEpatents

Gruen, Dieter M.; Krauss, Alan R.; DeWald, A. Bruce; Ju, Chien-Ping; Rigsbee, James M.

1993-01-01

A composite and method of forming same wherein the composite has a non-metallic portion and an alloy portion wherein the alloy comprises an alkali metal and a metal which is an electrical conductor such as Cu, Ag, Al, Sn or Au and forms an alloy with the alkali metal. A cable of superconductors and composite is also disclosed.

Method of bonding metals to ceramics and other materials

DOEpatents

Gruen, D.M.; Krauss, A.R.; DeWald, A.P.; Chienping Ju; Rigsbee, J.M.

1993-01-05

A composite and method of forming same wherein the composite has a non-metallic portion and an alloy portion wherein the alloy comprises an alkali metal and a metal which is an electrical conductor such as Cu, Ag, Al, Sn or Au and forms an alloy with the alkali metal. A cable of superconductors and composite is also disclosed.

On the lithium dip in the metal poor open cluster NGC 2243

NASA Astrophysics Data System (ADS)

François, P.; Pasquini, L.; Biazzo, K.; Bonifacio, P.; Palsa, R.

2014-05-01

Lithium is a key element for studying the mixing mechanisms operating in stellar interiors. It can also be used to probe the chemical evolution of the Galaxy and the Big Bang nucleosynthesis. Measuring the abundance of Lithium in stars belonging to Open Clusters (hereafter OC) allows a detailed comparison with stellar evolutionary models. NGC 2243 is particularly interesting thanks to its relative low metallicity ([Fe/H]=-0.54 ± 0.10 dex). We performed a detailed analysis of high-resolution spectra obtained with the multi-object facility FLAMES at the VLT 8.2m telescope. Lithium abundance has been measured in 27 stars. We found a Li dip center of 1.06 M⊙, which is significantly smaller than that observed in solar metallicity and metal-rich clusters. This finding confirms and strengthens the conclusion that the mass of the stars in the Li dip strongly depends on stellar metallicity. The mean Li abundance of the cluster is log n(Li) = 2.70 dex, which is substantially higher than that observed in 47 Tue. We derived an iron abundance of [Fe/H]=-0.54±0.10 dex for NGC 2243, in agreement (within the errors) with previous findings.

NGC 6067: a young and massive open cluster with high metallicity

NASA Astrophysics Data System (ADS)

Alonso-Santiago, J.; Negueruela, I.; Marco, A.; Tabernero, H. M.; González-Fernández, C.; Castro, N.

2017-08-01

NGC 6067 is a young open cluster hosting the largest population of evolved stars among known Milky Way clusters in the 50-150 Ma age range. It thus represents the best laboratory in our Galaxy to constrain the evolutionary tracks of 5-7 M⊙ stars. We have used high-resolution spectra of a large sample of bright cluster members (45), combined with archival photometry, to obtain accurate parameters for the cluster as well as stellar atmospheric parameters. We derive a distance of 1.78 ± 0.12 kpc, an age of 90 ± 20 Ma and a tidal radius of 14.8^{+6.8}_{-3.2} arcmin. We estimate an initial mass above 5700 M⊙, for a present-day evolved population of two Cepheids, two A supergiants and 12 red giants with masses ≈6 M⊙. We also determine chemical abundances of Li, O, Na, Mg, Si, Ca, Ti, Ni, Rb, Y and Ba for the red clump stars. We find a supersolar metallicity, [Fe/H] = +0.19 ± 0.05, and a homogeneous chemical composition, consistent with the Galactic metallicity gradient. The presence of a Li-rich red giant, star 276 with A(Li) = 2.41, is also detected. An overabundance of Ba is found, supporting the enhanced s-process. The ratio of yellow to red giants is much smaller than 1, in agreement with models with moderate overshooting, but the properties of the cluster Cepheids do not seem consistent with current Padova models for supersolar metallicity.

Structural basis for regioisomerization in the alkali-metal-mediated zincation (AMMZn) of trifluoromethyl benzene by isolation of kinetic and thermodynamic intermediates.

PubMed

Armstrong, David R; Blair, Victoria L; Clegg, William; Dale, Sophie H; Garcia-Alvarez, Joaquin; Honeyman, Gordon W; Hevia, Eva; Mulvey, Robert E; Russo, Luca

2010-07-14

Performed with a desire to advance knowledge of the structures and mechanisms governing alkali-metal-mediated zincation, this study monitors the reaction between the TMP-dialkylzincate reagent [(TMEDA)Na(TMP)((t)Bu)Zn((t)Bu)] 1 and trifluoromethyl benzene C(6)H(5)CF(3) 2. A complicated mixture of products is observed at room temperature. X-ray crystallography has identified two of these products as ortho- and meta-regioisomers of heterotrianionic [(TMEDA)Na(TMP)(C(6)H(4)-CF(3))Zn((t)Bu)], 3-ortho and 3-meta, respectively. Multinuclear NMR data of the bulk crystalline product confirm the presence of these two regioisomers as well as a third isomer, 3-para, in a respective ratio of 20:11:1, and an additional product 4, which also exhibits ortho-zincation of the aryl substrate. Repeating the reaction at 0 degrees C gave exclusively 4, which was crystallographically characterized as [{(TMEDA)(2)Na}(+){Zn(C(6)H(4)-CF(3))((t)Bu)(2)}(-)]. Mimicking the original room-temperature reaction, this kinetic product was subsequently reacted with TMP(H) to afford a complicated mixture of products, including significantly the three regioisomers of 3. Surprisingly, 4 adopts a solvent-separated ion pair arrangement in contrast to the contacted ion variants of 3-ortho and 3-meta. Aided by DFT calculations on model systems, discussion focuses on the different basicities, amido or alkyl, and steps, exhibited in these reactions, and how the structures and bonding within these isolated key metallic intermediates (prior to any electrophilic interception step), specifically the interactions involving the alkali metal, influence the regioselectivity of the Zn-H exchange process.

The Design, Synthesis, and Characterization of Open Sites on Metal Clusters

NASA Astrophysics Data System (ADS)

Nigra, Michael Mark

Coordinatively unsaturated corner and edge atoms have been hypothesized to have the highest activity of sites responsible for many catalytic reactions on a metal surface. Recent studies have validated this hypothesis in varied reaction systems. However, quantification of different types of coordinatively unsaturated sites, and elucidation of their individual catalytic rates has remained a largely unresolved challenge when understanding catalysis on metal surfaces. Yet such structure-function knowledge would be invaluable to the design of more active and selective metal-surface catalysts in the future. I investigated the catalytic contributions of undercoordinated sites such as corner and edge atoms are investigated in a model reaction system using organic ligands bound to the gold nanoparticle surface. The catalyst consisted of 4 nm gold nanoparticles on a metal oxide support, using resazurin to resorufin as a model reaction system. My results demonstrate that in this system, corner atom sites are the most undercoordinated sites, and are over an order of magnitude more active when compared to undercoordinated edge atom sites, while terrace sites remain catalytically inactive for the reduction reaction of resazurin to resorufin. Catalytic activity has been also demonstrated for calixarene-bound gold nanoparticles using the reduction of 4-nitrophenol. With the 4-nitrophenol reduction reaction, a comparative study was undertaken to compare calixarene phosphine and calixarene thiol bound 4 nm gold particles. The results of the study suggested that a leached site was responsible for catalysis and not sites on the original gold nanoparticles. Future experiments with calixarene bound gold clusters could investigate ligand effects in reactions where the active site is not a leached or aggregated gold species, possibly in oxidation reactions, where electron-rich gold is hypothesized to be a good catalyst. The results that emphasize the enhanced catalytic activity of

Entrapment of metal clusters in metal-organic framework channels by extended hooks anchored at open metal sites.

PubMed

Zheng, Shou-Tian; Zhao, Xiang; Lau, Samuel; Fuhr, Addis; Feng, Pingyun; Bu, Xianhui

2013-07-17

Reported here are the new concept of utilizing open metal sites (OMSs) for architectural pore design and its practical implementation. Specifically, it is shown here that OMSs can be used to run extended hooks (isonicotinates in this work) from the framework walls to the channel centers to effect the capture of single metal ions or clusters, with the concurrent partitioning of the large channel spaces into multiple domains, alteration of the host-guest charge relationship and associated guest-exchange properties, and transfer of OMSs from the walls to the channel centers. The concept of the extended hook, demonstrated here in the multicomponent dual-metal and dual-ligand system, should be generally applicable to a range of framework types.

A bronze matryoshka: the discrete intermetalloid cluster [Sn@Cu12@Sn20](12-) in the ternary phases A12Cu12Sn21 (A = Na, K).

PubMed

Stegmaier, Saskia; Fässler, Thomas F

2011-12-14

The synthesis and crystal structure of the first ternary A-Cu-Sn intermetallic phases for the heavier alkali metals A = Na to Cs is reported. The title compounds A(12)Cu(12)Sn(21) show discrete 33-atom intermetalloid Cu-Sn clusters {Sn@Cu(12)@Sn(20)}, which are composed of {Sn(20)} pentagonal dodecahedra surrounding {Cu(12)} icosahedra with single Sn atoms at the center. Na(12)Cu(12)Sn(21) and K(12)Cu(12)Sn(21) were characterized by single-crystal XRD studies, and the successful synthesis of analogous A-Cu-Sn compounds with A = Rb and Cs is deduced from powder XRD data. The isotypic A(12)Cu(12)Sn(21) phases crystallize in the cubic space group Pn ̅3m (No. 224), with the Cu-Sn clusters adopting a face centered cubic arrangement. A formal charge of 12- can be assigned to the {Sn@Cu(12)@Sn(20)} cluster unit, and the interpretation of the title compounds as salt-like intermetallic phases featuring discrete anionic intermetalloid [Sn@Cu(12)@Sn(20)](12-) clusters separated by alkali metal cations is supported by electronic structure calculations. For both Na(12)Cu(12)Sn(21) and K(12)Cu(12)Sn(21), DFT band structure calculations (TB-LMTO-ASA) reveal a band gap. The discrete [Sn@Cu(12)@Sn(20)](12-) cluster is analyzed in consideration of the molecular orbitals obtained from hybrid DFT calculations (Gaussian 09) for the cluster anion. The [Sn@Cu(12)@Sn(20)](12-) cluster MOs can be classified with labels indicating the numbers of radial and angular nodes, in the style of spherical shell models of cluster bonding. © 2011 American Chemical Society

Structure and thermodynamics of liquid alkali metals in variational modified hypernetted-chain theory

NASA Astrophysics Data System (ADS)

Chen, H. C.; Lai, S. K.

1992-03-01

The role of the Percus-Yevick hard-sphere bridge function in the modified hypernetted-chain integral equation is examined within the context of Lado's criterion [F. Lado, S. M. Foiles, and N. W. Ashcroft, Phys. Rev. A 28, 2374 (1983)]. It is found that the commonly used Lado's criterion, which takes advantage of the analytical simplicity of the Percus-Yevick hard-sphere bridge function, is inadequate for determining an accurate static pair-correlation function. Following Rosenfeld [Y. Rosenfeld, Phys. Rev. A 29, 2877 (1984)], we reconsider Lado's criterion in the so-called variational modified hypernetted-chain theory. The main idea is to construct a free-energy functional satisfying the virial-energy thermodynamic self-consistency. It turns out that the widely used Gibbs-Bogoliubov inequality is equivalent to this integral approach of Lado's criterion. Detailed comparison between the presently obtained structural and thermodynamic quantities for liquid alkali metals and those calculated also in the modified hypernetted-chain theory but with the one-component-plasma reference system leads us to a better understanding of the universality property of the bridge function.

GLOBULAR CLUSTER ABUNDANCES FROM HIGH-RESOLUTION, INTEGRATED-LIGHT SPECTROSCOPY. II. EXPANDING THE METALLICITY RANGE FOR OLD CLUSTERS AND UPDATED ANALYSIS TECHNIQUES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colucci, Janet E.; Bernstein, Rebecca A.; McWilliam, Andrew

2017-01-10

We present abundances of globular clusters (GCs) in the Milky Way and Fornax from integrated-light (IL) spectra. Our goal is to evaluate the consistency of the IL analysis relative to standard abundance analysis for individual stars in those same clusters. This sample includes an updated analysis of seven clusters from our previous publications and results for five new clusters that expand the metallicity range over which our technique has been tested. We find that the [Fe/H] measured from IL spectra agrees to ∼0.1 dex for GCs with metallicities as high as [Fe/H] = −0.3, but the abundances measured for more metal-rich clustersmore » may be underestimated. In addition we systematically evaluate the accuracy of abundance ratios, [X/Fe], for Na i, Mg i, Al i, Si i, Ca i, Ti i, Ti ii, Sc ii, V i, Cr i, Mn i, Co i, Ni i, Cu i, Y ii, Zr i, Ba ii, La ii, Nd ii, and Eu ii. The elements for which the IL analysis gives results that are most similar to analysis of individual stellar spectra are Fe i, Ca i, Si i, Ni i, and Ba ii. The elements that show the greatest differences include Mg i and Zr i. Some elements show good agreement only over a limited range in metallicity. More stellar abundance data in these clusters would enable more complete evaluation of the IL results for other important elements.« less

Photochemical cleavage of metal--carbon nanocrystals and their reconstruction into met--cars clusters

NASA Astrophysics Data System (ADS)

Pilgrim, J. S.; Duncan, M. A.

1994-10-01

Titanium and zirconium metal--carbon clusters are produced by laser vaporization in a pulsed nozzle source and detected with time-of-flight mass spectrometry. In addition to the now-familiar "met-cars" stoichiometry (M8C12), larger magic number clusters are produced with near 1:1 metal--carbon ratios. The special stoichiometries observed correspond to face-centered cubic crystal fragments, with a strong preference for fragments with symmetrical x,y,z dimensions. Mass-selected photodissociation experiments are used to investigate the structural patterns and stabilities of these systems. Photodissociation of the larger "nanocrystal" clusters leads to cleavage along crystal planes, producing smaller crystals also having highly symmetric dimensions. Photoexcitation of all these crystallites, in particular the 3 × 3 × 3 species, also leads to surface reconstruction, forming the M8C12 met-cars cluster and/or the M8C13 cluster, the latter of which is assigned to a met--cars cage with an endohedral carbon atom.

Advanced Electrochemistry of Individual Metal Clusters Electrodeposited Atom by Atom to Nanometer by Nanometer.

PubMed

Kim, Jiyeon; Dick, Jeffrey E; Bard, Allen J

2016-11-15

Metal clusters are very important as building blocks for nanoparticles (NPs) for electrocatalysis and electroanalysis in both fundamental and applied electrochemistry. Attention has been given to understanding of traditional nucleation and growth of metal clusters and to their catalytic activities for various electrochemical applications in energy harvesting as well as analytical sensing. Importantly, understanding the properties of these clusters, primarily the relationship between catalysis and morphology, is required to optimize catalytic function. This has been difficult due to the heterogeneities in the size, shape, and surface properties. Thus, methods that address these issues are necessary to begin understanding the reactivity of individual catalytic centers as opposed to ensemble measurements, where the effect of size and morphology on the catalysis is averaged out in the measurement. This Account introduces our advanced electrochemical approaches to focus on each isolated metal cluster, where we electrochemically fabricated clusters or NPs atom by atom to nanometer by nanometer and explored their electrochemistry for their kinetic and catalytic behavior. Such approaches expand the dimensions of analysis, to include the electrochemistry of (1) a discrete atomic cluster, (2) solely a single NP, or (3) individual NPs in the ensemble sample. Specifically, we studied the electrocatalysis of atomic metal clusters as a nascent electrocatalyst via direct electrodeposition on carbon ultramicroelectrode (C UME) in a femtomolar metal ion precursor. In addition, we developed tunneling ultramicroelectrodes (TUMEs) to study electron transfer (ET) kinetics of a redox probe at a single metal NP electrodeposited on this TUME. Owing to the small dimension of a NP as an active area of a TUME, extremely high mass transfer conditions yielded a remarkably high standard ET rate constant, k 0 , of 36 cm/s for outer-sphere ET reaction. Most recently, we advanced nanoscale

Synthesis, structures and stabilities of thioanisole-functionalised phosphido-borane complexes of the alkali metals.

PubMed

Izod, Keith; Watson, James M; Clegg, William; Harrington, Ross W

2011-11-28

Treatment of the secondary phosphine {(Me(3)Si)(2)CH}PH(C(6)H(4)-2-SMe) with BH(3)·SMe(2) gives the corresponding phosphine-borane {(Me(3)Si)(2)CH}PH(BH(3))(C(6)H(4)-2-SMe) (9) as a colourless solid. Deprotonation of 9 with n-BuLi, PhCH(2)Na or PhCH(2)K proceeds cleanly to give the corresponding alkali metal complexes [[{(Me(3)Si)(2)CH}P(BH(3))(C(6)H(4)-2-SMe)]ML](n) [ML = Li(THF), n = 2 (10); ML = Na(tmeda), n = ∞ (11); ML = K(pmdeta), n = 2 (12)] as yellow/orange crystalline solids. X-ray crystallography reveals that the phosphido-borane ligands bind the metal centres through their sulfur and phosphorus atoms and through the hydrogen atoms of the BH(3) group in each case, leading to dimeric or polymeric structures. Compounds 10-12 are stable towards both heat and ambient light; however, on heating in toluene solution in the presence of 10, traces of free phosphine-borane 9 are slowly converted to the free phosphine {(Me(3)Si)(2)CH}PH(C(6)H(4)-2-SMe) (5) with concomitant formation of the corresponding phosphido-bis(borane) complex [{(Me(3)Si)(2)CH}P(BH(3))(2)(C(6)H(4)-2-SMe)]Li (14).

Metal phthalocyanine catalysts

DOEpatents

Ellis, Jr., Paul E.; Lyons, James E.

1994-01-01

As a new composition of matter, alkali metal or ammonium or tetraalkylammonium diazidoperfluorophthalocyanatoferrate. Other embodiments of the invention comprise compositions wherein the metal of the coordination complex is cobalt, manganese and chromium.

Alkali slurry ozonation to produce a high capacity nickel battery material

DOEpatents

Jackovitz, John F.; Pantier, Earl A.

1984-11-06

A high capacity battery material is made, consisting essentially of hydrated Ni(II) hydroxide, and about 5 wt. % to about 40 wt. % of Ni(IV) hydrated oxide interlayer doped with alkali metal cations selected from potassium, sodium and lithium cations.

Alkali metal pool boiler life tests for a 25 kWe advanced Stirling conversion system

NASA Technical Reports Server (NTRS)

Anderson, W. G.; Rosenfeld, J. H.; Noble, J.

1991-01-01

The overall operating temperature and efficiency of solar-powered Stirling engines can be improved by adding an alkali metal pool boiler heat transport system to supply heat more uniformly to the heater head tubes. One issue with liquid metal pool boilers is unstable boiling. Stable boiling is obtained with an enhanced boiling surface containing nucleation sites that promote continuous boiling. Over longer time periods, it is possible that the boiling behavior of the system will change. An 800-h life test was conducted to verify that pool boiling with the chosen fluid/surface combination remains stable as the system ages. The apparatus uses NaK boiling on a - 100 + 140 stainless steel sintered porous layer, with the addition of a small amount of xenon. Pool boiling remained stable to the end of life test. The pool boiler life test included a total of 82 cold starts, to simulate startup each morning, and 60 warm restarts, to simulate cloud cover transients. The behavior of the cold and warm starts showed no significant changes during the life test. In the experiments, the fluid/surface combination provided stable, high-performance boiling at the operating temperature of 700 C. Based on these experiments, a pool boiler was designed for a full-scale 25-kWe Stirling system.

Processes of conversion of a hot metal particle into aerogel through clusters

NASA Astrophysics Data System (ADS)

Smirnov, B. M.

2015-10-01

Processes are considered for conversion into a fractal structure of a hot metal micron-size particle that is located in a buffer gas or a gas flow and is heated by an external electric or electromagnetic source or by a plasma. The parameter of this heating is the particle temperature, which is the same in the entire particle volume because of its small size and high conductivity. Three processes determine the particle heat balance: particle radiation, evaporation of metal atoms from the particle surface, and heat transport to the surrounding gas due to its thermal conductivity. The particle heat balance is analyzed based on these processes, which are analogous to those for bulk metals with the small particle size, and its high temperature taken into account. Outside the particle, where the gas temperature is lower than on its surface, the formed metal vapor in a buffer gas flow is converted into clusters. Clusters grow as a result of coagulation until they become liquid, and then clusters form fractal aggregates if they are removed form the gas flow. Subsequently, associations of fractal aggregates join into a fractal structure. The rate of this process increases in medium electric fields, and the formed fractal structure has features of aerogels and fractal fibers. As a result of a chain of the above processes, a porous metal film may be manufactured for use as a filter or catalyst for gas flows.

Zirconium and hafnium fractionation in differentiation of alkali carbonatite magmatic systems

NASA Astrophysics Data System (ADS)

Kogarko, L. N.

2016-05-01

Zirconium and hafnium are valuable strategic metals which are in high demand in industry. The Zr and Hf contents are elevated in the final products of magmatic differentiation of alkali carbonatite rocks in the Polar Siberia region (Guli Complex) and Ukraine (Chernigov Massif). Early pyroxene fractionation led to an increase in the Zr/Hf ratio in the evolution of the ultramafic-alkali magmatic system due to a higher distribution coefficient of Hf in pyroxene with respect to Zr. The Rayleigh equation was used to calculate a quantitative model of variation in the Zr/Hf ratio in the development of the Guli magmatic system. Alkali carbonatite rocks originated from rare element-rich mantle reservoirs, in particular, the metasomatized mantle. Carbonated mantle xenoliths are characterized by a high Zr/Hf ratio due to clinopyroxene development during metasomatic replacement of orthopyroxene by carbonate fluid melt.

The spectroscopic (FT-IR, FT-Raman and 1H, 13C NMR) and theoretical studies of cinnamic acid and alkali metal cinnamates

NASA Astrophysics Data System (ADS)

Kalinowska, Monika; Świsłocka, Renata; Lewandowski, Włodzimierz

2007-05-01

The effect of alkali metals (Li → Na → K → Rb → Cs) on the electronic structure of cinnamic acid (phenylacrylic acid) was studied. In this research many miscellaneous analytical methods, which complement one another, were used: infrared (FT-IR), Raman (FT-Raman), nuclear magnetic resonance ( 1H, 13C NMR) and quantum mechanical calculations. The spectroscopic studies lead to conclusions concerning the distribution of the electronic charge in molecule, the delocalization energy of π-electrons and the reactivity of metal complexes. The change of metal along with the series: Li → Na → K → Rb → Cs caused: (1) the change of electronic charge distribution in cinnamate anion what is seen via the occurrence of the systematic shifts of several bands in the experimental and theoretical IR and Raman spectra of cinnamates, (2) systematic chemical shifts for protons 1H and 13C nuclei.

Refractories for high alkali environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rau, A.W.; Cloer, F.

1996-12-31

Information on refractories for high alkali environments is outlined. Information is presented on: product gallery; alkali attack; chemical reactions; basic layout of alkali cup test; criteria for rating alkali cup test samples; and basic layout of physical properties test.

Sound controlled rotation of a cluster of small particles on an ultrasonically vibrating metal strip

NASA Astrophysics Data System (ADS)

Zhang, Xueyi; Zheng, Yun; Hu, Junhui

2008-01-01

We show that a vibrating metal strip, mechanically driven by an ultrasonic transducer, can rotate a cluster of small particles around a fixed point, and the diameter of the cluster of small particles can reach a stable value (steady diameter) for a given driving condition. The rotation is very stable when the vibration of the metal strip is appropriate. The revolution speed, its direction, and steady diameter of the particle cluster can be controlled by the operating frequency of the ultrasonic transducer. For shrimp eggs, a revolution speed up to 360rpm can be obtained.

Effect of basic alkali-pickling conditions on the production of lysinoalanine in preserved eggs.

PubMed

Zhao, Yan; Luo, Xuying; Li, Jianke; Xu, Mingsheng; Tu, Yonggang

2015-09-01

During the pickling process, strong alkali causes significant lysinoalanine (LAL) formation in preserved eggs, which may reduce the nutritional value of the proteins and result in a potential hazard to human health. In this study, the impacts of the alkali treatment conditions on the production of LAL in preserved eggs were investigated. Preserved eggs were prepared using different times and temperatures, and alkali-pickling solutions with different types and concentrations of alkali and metal salts, and the corresponding LAL contents were measured. The results showed the following: during the pickling period of the preserved egg, the content of LAL in the egg white first rapidly increased and then slowly increased; the content of LAL in the egg yolk continued to increase significantly. During the aging period, the levels of LAL in both egg white and egg yolk slowly increased. The amounts of LAL in the preserved eggs were not significantly different at temperatures between 20 and 25ºC. At higher pickling temperatures, the LAL content in the preserved eggs increased. With the increase of alkali concentration in the alkali-pickling solution, the LAL content in the egg white and egg yolk showed an overall trend of an initial increase followed by a slight decrease. The content of LAL produced in preserved eggs treated with KOH was lower than in those treated with NaOH. NaCl and KCl produced no significant effects on the production of LAL in the preserved eggs. With increasing amounts of heavy metal salts, the LAL content in the preserved eggs first decreased and then increased. The LAL content generated in the CuSO4 group was lower than that in either the ZnSO4 or PbO groups. © 2015 Poultry Science Association Inc.

Metal phthalocyanine catalysts

DOEpatents

Ellis, P.E. Jr.; Lyons, J.E.

1994-10-11

A new composition of matter is described which is an alkali metal or ammonium or tetraalkylammonium diazidoperfluorophthalocyanatoferrate. Other embodiments of the invention comprise compositions wherein the metal of the coordination complex is cobalt, manganese and chromium.

Methods for synthesizing metal oxide nanowires

DOEpatents

Sunkara, Mahendra Kumar; Kumar, Vivekanand; Kim, Jeong H.; Clark, Ezra Lee

2016-08-09

A method of synthesizing a metal oxide nanowire includes the steps of: combining an amount of a transition metal or a transition metal oxide with an amount of an alkali metal compound to produce a mixture; activating a plasma discharge reactor to create a plasma discharge; exposing the mixture to the plasma discharge for a first predetermined time period such that transition metal oxide nanowires are formed; contacting the transition metal oxide nanowires with an acid solution such that an alkali metal ion is exchanged for a hydrogen ion on each of the transition metal oxide nanowires; and exposing the transition metal oxide nanowires to the plasma discharge for a second predetermined time period to thermally anneal the transition metal oxide nanowires. Transition metal oxide nanowires produced using the synthesis methods described herein are also provided.

Binding of Alkali Metal Ions with 1,3,5-Tri(phenyl)benzene and 1,3,5-Tri(naphthyl)benzene: The Effect of Phenyl and Naphthyl Ring Substitution on Cation-π Interactions Revealed by DFT Study.

PubMed

Mirchi, Ali; Sizochenko, Natalia; Dinadayalane, Tandabany; Leszczynski, Jerzy

2017-11-22

The effect of substitution of phenyl and naphthyl rings to benzene was examined to elucidate the cation-π interactions involving alkali metal ions with 1,3,5-tri(phenyl)benzene (TPB) and 1,3,5-tri(naphthyl)benzene (TNB). Benzene, TPB, and four TNB isomers (with ααα, ααβ, αββ, and βββ types of fusion) and their complexes with Li + , Na + , K + , Rb + , and Cs + were optimized using DFT approach with B3LYP and M06-2X functionals in conjunction with the def2-QZVP basis set. Higher relative stability of β,β,β-TNB over α,α,α-TNB can be attributed to peri repulsion, which is defined as the nonbonding repulsive interaction between substituents in the 1- and the 8-positions on the naphthalene core. Binding energies, distances between ring centroid and the metal ions, and the distance to metal ions from the center of other six-membered rings were compared for all complexes. Our computational study reveals that the binding affinity of alkali metal cations increases significantly with the 1,3,5-trisubstitution of phenyl and naphthyl rings to benzene. The detailed computational analyses of geometries, partial charges, binding energies, and ligand organization energies reveal the possibility of favorable C-H···M + interactions when a α-naphthyl group exists in complexes of TNB structures. Like benzene-alkali metal ion complexes, the binding affinity of metal ions follows the order: Li + > Na + > K + > Rb + > Cs + for any considered 1,3,5-trisubstituted benzene systems. In case of TNB, we found that the strength of interactions increases as the fusion point changes from α to β position of naphthalene.

Theoretical research program to study transition metal trimers and embedded clusters

NASA Technical Reports Server (NTRS)

Walch, Stephen P.

1987-01-01

The results of ab-initio calculations are reported for (1) small transition metal clusters and (2) potential energy surfaces for chemical reactions important in hydrogen combustion and high temperature air chemistry.

Unified picture of the doping dependence of superconducting transition temperatures in alkali metal/ammonia intercalated FeSe

NASA Astrophysics Data System (ADS)

Guterding, Daniel; Jeschke, Harald; Hirschfeld, Peter; Valenti, Roser

2015-03-01

We present a theoretical investigation of alkali metal/ammonia intercalated iron selenide. Using ab-initio density functional theory we unravel how charge doping and dimensionality of the electronic structure can be controlled through the chemical composition of the intercalated molecules. Within random phase approximation spin fluctuation theory we analyze the impact of intercalation on the superconducting pairing strength. We find that high Tc is to be expected away from perfect nesting. While experimental studies have focused on the intercalation of larger molecules in the spacer layer so far, we argue that no higher Tc can be achieved this way. This work was supported by Deutsche Forschungsgemeinschaft under Grant No. SPP 1458, the National Science Foundation under Grant No. PHY11-25915 and the Department of Energy under Grant No. DE-FG02-05ER46236.

Particle size dependence of alkali and alkaline earth metal enrichment in marine aerosols from Bermuda

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffman, E.J.; Hoffman, G.L.; Duce, R.A.

1980-10-20

Three cascade impactor samples were collected from a 20-m-high tower on the southeastern coast of Bermuda. These samples were analyzed for Na, K, Ca, Mg, and Fe by atomic absorption spectrophotometry. When the alkali-alkakine earth metal concentrations are corrected for a soil-derived component, utilizing the atmospheric Fe concentrations, Mg, Ca, and Na are found to be present in the same relative abundances as in seawater for all particle sizes sampled. Potassium also shows no deviation from a bulk seawater composition for particles with radii greater than approx.0.5 ..mu..m. However, excess K above that expected from either a bulk seawater ormore » soil source is observed on particles with radii less than approx.0.5 ..mu..m. While oceanic chemical fractionation processes during bubble bursting may be responsible for this excess small particle K, it is most likely due to long-range transport of K-rich particles of terrestrial vegetative origin.« less

The role of halide ions on the electrochemical behaviour of iron in alkali solutions

NASA Astrophysics Data System (ADS)

Begum, S. Nathira; Muralidharan, V. S.; Basha, C. Ahmed

2008-02-01

Active dissolution and passivation of transition metals in alkali solutions is of technological importance in batteries. The performance of alkaline batteries is decided by the presence of halides as they influence passivation. Cyclic voltammetric studies were carried out on iron in different sodium hydroxide solutions in presence of halides. In alkali solutions iron formed hydroxo complexes and their polymers in the interfacial diffusion layer. With progress of time they formed a cation selective layer. The diffusion layer turned into bipolar ion selective layer consisted of halides, a selective inner sublayer to the metal side and cation selective outer layer to the solution side. At very high anodic potentials, dehydration and deprotonation led to the conversion of salt layer into an oxide.

Inherent size effects on XANES of nanometer metal clusters: Size-selected platinum clusters on silica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Yang; Gorey, Timothy J.; Anderson, Scott L.

2016-12-12

X-ray absorption near-edge structure (XANES) is commonly used to probe the oxidation state of metal-containing nanomaterials, however, as the particle size in the material drops below a few nanometers, it becomes important to consider inherent size effects on the electronic structure of the materials. In this paper, we analyze a series of size-selected Pt n/SiO 2 samples, using X-ray photoelectron spectroscopy (XPS), low energy ion scattering, grazing-incidence small angle X-ray scattering, and XANES. The oxidation state and morphology are characterized both as-deposited in UHV, and after air/O 2 exposure and annealing in H 2. Here, the clusters are found tomore » be stable during deposition and upon air exposure, but sinter if heated above ~150 °C. XANES shows shifts in the Pt L 3 edge, relative to bulk Pt, that increase with decreasing cluster size, and the cluster samples show high white line intensity. Reference to bulk standards would suggest that the clusters are oxidized, however, XPS shows that they are not. Instead, the XANES effects are attributable to development of a band gap and localization of empty state wavefunctions in small clusters.« less

Fourier transform infrared isotopic studies on novel metal-carbon clusters trapped in argon matrix environments

NASA Astrophysics Data System (ADS)

Bates, Sarah Anne

The characterization of the vibrational spectra and structures of small metal-carbon (MnCm) clusters is important to the detection of astrophysical species and may elucidate the bonding and growth mechanisms of metallocarbohedrenes, or metcars. Additionally, transition metal-carbon clusters have applications in modern materials science as catalysts for nanomaterial formation. A new experimental apparatus for the preparation of MnC m clusters has been designed and constructed, incorporating a new closed cycle refrigeration system, a chamber for the deposition of samples, associated vacuum system, and a fully automated mechanism to simultaneously translate and rotate carbon and metal rods during laser ablation. A new technique for fabricating carbon rods has been developed to expedite carbon rod production and to facilitate the formation of the MnC m clusters studied. Fourier transform infrared (FTIR) investigations have been done for the first time on transition metal-carbon clusters. The molecular clusters were formed by trapping the products from dual laser ablation of metal and carbon rods in solid Ar at ˜10 K. Comparing FTIR measurements of vibrational fundamentals and 13C isotopic shifts with the predictions of density functional theory (DFT) calculations has enabled the identification of five novel metal-carbon molecules, establishing their ground state geometries and permitting the assignment of vibrational fundamentals, including the nu 1(sigma) modes of (5pi) linear CrC3, ( 2Delta) linear CoC3, and (2pi) linear CuC3 at 1789.5, 1918.2, and 1830.0 cm-1, respectively, the nu3(sigmau)=1624.0 and nu 4(sigmau)=528.3 cm-1 modes of (1Sigmag+) linear AlC3Al, and the nu2(sigma)=1210.9 cm -1 mode of linear AlC3. Evidence for the tentative identification of the nu1(a1)=1554.3 cm-1 mode of (3B1) fanlike CrC4 and the nu4(sigmau)=1987.3 cm-1 mode of (1Sigmag +) linear AlC4Al is also presented. All FTIR measurements of vibrational frequencies and 13C shifts are in very

PROCESS FOR TREATING VOLATILE METAL FLUORIDES

DOEpatents

Rudge, A.J.; Lowe, A.J.

1957-10-01

This patent relates to the purification of uranium hexafluoride, made by reacting the metal or its tetrafluoride with fluorine, from the frequently contained traces of hydrofluoric acid. According to the present process, UF/sub 6/ containing as an impurity a small amount of hydrofluoric acid, is treated to remove such impurity by contact with an anhydrous alkali metal fluoride such as sodium fluoride. In this way a non-volatile complex containing hydrofluoric acid and the alkali metal fluoride is formed, and the volatile UF /sub 6/ may then be removed by distillation.

Thermal effects in Cs DPAL and alkali cell window damage

NASA Astrophysics Data System (ADS)

Zhdanov, B. V.; Rotondaro, M. D.; Shaffer, M. K.; Knize, R. J.

2016-10-01

Experiments on power scaling of Diode Pumped Alkali Lasers (DPALs) revealed some limiting parasitic effects such as alkali cell windows and gain medium contamination and damage, output power degradation in time and others causing lasing efficiency decrease or even stop lasing1 . These problems can be connected with thermal effects, ionization, chemical interactions between the gain medium components and alkali cells materials. Study of all these and, possibly, other limiting effects and ways to mitigate them is very important for high power DPAL development. In this talk we present results of our experiments on temperature measurements in the gain medium of operating Cs DPAL at different pump power levels in the range from lasing threshold to the levels causing damage of the alkali cell windows. For precise contactless in situ temperature measurements, we used an interferometric technique, developed in our lab2 . In these experiments we demonstrated that damage of the lasing alkali cell starts in the bulk with thermal breakdown of the hydrocarbon buffer gas. The degradation processes start at definite critical temperatures of the gain medium, different for each mixture of buffer gas. At this critical temperature, the hydrocarbon and the excited alkali metal begin to react producing the characteristic black soot and, possibly, some other chemical compounds, which both harm the laser performance and significantly increase the harmful heat deposition within the laser medium. This soot, being highly absorptive, is catastrophically heated to very high temperatures that visually observed as bulk burning. This process quickly spreads to the cell windows and causes their damage. As a result, the whole cell is also contaminated with products of chemical reactions.

Metal-cluster ionization energy: A profile-insensitive exact expression for the size effect

NASA Astrophysics Data System (ADS)

Seidl, Michael; Perdew, John P.; Brajczewska, Marta; Fiolhais, Carlos

1997-05-01

The ionization energy of a large spherical metal cluster of radius R is I(R)=W+(+c)/R, where W is the bulk work function and c~-0.1 is a material-dependent quantum correction to the electrostatic size effect. We present 'Koopmans' and 'displaced-profile change-in-self-consistent-field' expressions for W and c within the ordinary and stabilized-jellium models. These expressions are shown to be exact and equivalent when the exact density profile of a large neutral cluster is employed; these equivalences generalize the Budd-Vannimenus theorem. With an approximate profile obtained from a restricted variational calculation, the 'displaced-profile' expressions are the more accurate ones. This profile insensitivity is important, because it is not practical to extract c from solutions of the Kohn-Sham equations for small metal clusters.

Reddenings, Metallicities, and Possible Abundance Anomalies in Young Globular Clusters

NASA Astrophysics Data System (ADS)

Sarajedini, Ata; Layden, Andrew

1997-01-01

We present new photometry in the VI passbands for the ``young'' globular clusters Rup 106, Ter 7, and Arp 2. After formulating the simultaneous reddening and metallicity (SRM) method of Sarajedini (1994) in the BV passbands, we apply it, along with the SRM method in VI, to the red giant branches (RGBs) of these clusters using B-V photometry from the literature and the V-I data presented herein. We find [Fe/H] = -1.90 +/- 0.10, E(B-V) = 0.18 +/- 0.02 for Rup 106, [Fe/H] = -0.82 +/- 0.15, E(B-V) = 0.07 +/- 0.03 for Ter 7, and [Fe/H] = -1.84 +/- 0.09, E(B-V) = 0.10 +/- 0.02 for Arp 2. Furthermore, in light of this new abundance for Ter 7 and recent work on the luminosity of the red horizontal branch, we rederive the age of Ter 7 finding it to be some 6 Gyr younger than 47 Tuc. We show that the SRM method is insensitive to age for clusters with purely red HBs and ages as young as ~ 5 Gyr; for clusters with bluer HBs, the SRM method is only mildly sensitive to age differences between such clusters and the calibrating (standard) clusters. From these metallicity estimates, we conclude that the photometric abundances of the program clusters based on the properties of the RGB are systematically lower (Delta [Fe/H] = 0.1-0.4 dex) than those derived using other indicators, in particular the Ca 2 triplet method. We note that the young globular clusters Pal 12 and possibly IC 4499 also exhibit this behavior. We suggest that this discrepancy is due to systematic differences in the [alpha /Fe] ratios between the young clusters and the ``normal'' Galactic globulars used to calibrate the abundance determination methods. However, we are unable to completely reconcile all the observations of Rup 106 using this approach. Systematic differences in [alpha /Fe] between the young clusters and the rest of the Galactic globulars may indicate differences in their chemical enrichment histories, perhaps due to differing environments at the times of their formation. Interestingly, both Ter 7

Electronic Interactions of Size-Selected Oxide Clusters on Metallic and Thin Film Oxide Supports

DOE PAGES

Xue, Meng; Nakayama, Miki; Liu, Ping; ...

2017-09-13

The interfacial electronic structure of various size-selected metal oxide nanoclusters (M 3O x; M = Mo, Nb, Ti) on Cu(111) and a thin film of Cu 2O supports were investigated in this paper by a combination of experimental methods and density functional theory (DFT). These systems explore electron transfer at the metal–metal oxide interface which can modify surface structure, metal oxidation states, and catalytic activity. Electron transfer was probed by measurements of surface dipoles derived from coverage dependent work function measurements using two-photon photoemission (2PPE) and metal core level binding energy spectra from X-ray photoelectron spectroscopy (XPS). The measured surfacemore » dipoles are negative for all clusters on Cu(111) and Cu 2O/Cu(111), but those on the Cu 2O surface are much larger in magnitude. In addition, sub-stoichiometric or “reduced” clusters exhibit smaller surface dipoles on both the Cu(111) and Cu 2O surfaces. Negative surface dipoles for clusters on Cu(111) suggest Cu → cluster electron transfer, which is generally supported by DFT-calculated Bader charge distributions. For Cu 2O/Cu(111), calculations of the surface electrostatic potentials show that the charge distributions associated with cluster adsorption structures or distortions at the cluster–Cu 2O–Cu(111) interface are largely responsible for the observed negative surface dipoles. Changes observed in the XPS spectra for the Mo 3d, Nb 3d, and Ti 2p core levels of the clusters on Cu(111) and Cu 2O/Cu(111) are interpreted with help from the calculated Bader charges and cluster adsorption structures, the latter providing information about the presence of inequivalent cation sites. Finally, the results presented in this work illustrate how the combined use of different experimental probes along with theoretical calculations can result in a more realistic picture of cluster–support interactions and bonding.« less

Electronic Interactions of Size-Selected Oxide Clusters on Metallic and Thin Film Oxide Supports

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xue, Meng; Nakayama, Miki; Liu, Ping

The interfacial electronic structure of various size-selected metal oxide nanoclusters (M 3O x; M = Mo, Nb, Ti) on Cu(111) and a thin film of Cu 2O supports were investigated in this paper by a combination of experimental methods and density functional theory (DFT). These systems explore electron transfer at the metal–metal oxide interface which can modify surface structure, metal oxidation states, and catalytic activity. Electron transfer was probed by measurements of surface dipoles derived from coverage dependent work function measurements using two-photon photoemission (2PPE) and metal core level binding energy spectra from X-ray photoelectron spectroscopy (XPS). The measured surfacemore » dipoles are negative for all clusters on Cu(111) and Cu 2O/Cu(111), but those on the Cu 2O surface are much larger in magnitude. In addition, sub-stoichiometric or “reduced” clusters exhibit smaller surface dipoles on both the Cu(111) and Cu 2O surfaces. Negative surface dipoles for clusters on Cu(111) suggest Cu → cluster electron transfer, which is generally supported by DFT-calculated Bader charge distributions. For Cu 2O/Cu(111), calculations of the surface electrostatic potentials show that the charge distributions associated with cluster adsorption structures or distortions at the cluster–Cu 2O–Cu(111) interface are largely responsible for the observed negative surface dipoles. Changes observed in the XPS spectra for the Mo 3d, Nb 3d, and Ti 2p core levels of the clusters on Cu(111) and Cu 2O/Cu(111) are interpreted with help from the calculated Bader charges and cluster adsorption structures, the latter providing information about the presence of inequivalent cation sites. Finally, the results presented in this work illustrate how the combined use of different experimental probes along with theoretical calculations can result in a more realistic picture of cluster–support interactions and bonding.« less

Experimental and Theoretical Studies of Pressure Broadened Alkali-Metal Atom Resonance Lines

NASA Technical Reports Server (NTRS)

Shindo, F.; Zhu, C.; Kirby, K.; Babb, J. F.

2006-01-01

We are carrying out a joint theoretical and experimental research program to study the broadening of alkali atom resonance lines due to collisions with helium and molecular hydrogen for applications to spectroscopic studies of brown dwarfs and extrasolar giant planets.

An updated survey of globular clusters in M 31. III. A spectroscopic metallicity scale for the Revised Bologna Catalog

NASA Astrophysics Data System (ADS)

Galleti, S.; Bellazzini, M.; Buzzoni, A.; Federici, L.; Fusi Pecci, F.

2009-12-01

Aims. We present a new homogeneous set of metallicity estimates based on Lick indices for the old globular clusters of the M 31 galaxy. The final aim is to add homogeneous spectroscopic metallicities to as many entries as possible of the Revised Bologna Catalog of M 31 clusters, by reporting Lick index measurements from any source (literature, new observations, etc.) on the same scale. Methods: New empirical relations of [Fe/H] as a function of [MgFe] and Mg2 indices are based on the well-studied galactic globular clusters, complemented with theoretical model predictions for -0.2≤ [Fe/H]≤ +0.5. Lick indices for M 31 clusters from various literature sources (225 clusters) and from new observations by our team (71 clusters) have been transformed into the Trager et al. system, yielding new metallicity estimates for 245 globular clusters of M 31. Results: Our values are in good agreement with recent estimates based on detailed spectral fitting and with those obtained from color magnitude diagrams of clusters imaged with the Hubble Space Telescope. The typical uncertainty on individual estimates is ≃±0.25 dex, as resulted from the comparison with metallicities derived from color magnitude diagrams of individual clusters. Conclusions: The metallicity distribution of M 31 globular cluster is briefly discussed and compared with that of the Milky Way. Simple parametric statistical tests suggest that the distribution is probably not unimodal. The strong correlation between metallicity and kinematics found in previous studies is confirmed. The most metal-rich GCs tend to be packed into the center of the system and to cluster tightly around the galactic rotation curve defined by the HI disk, while the velocity dispersion about the curve increases with decreasing metallicity. However, also the clusters with [Fe/H]<-1.0 display a clear rotation pattern, at odds with their Milky Way counterparts. Based on observations made at La Palma, at the Spanish Observatorio del Roque

Evaluation Of Demercurization Efficiency Of Chlor-Alkali Production In Pavlodar City, Kazakhstan

EPA Science Inventory

Mercury pollution in Pavlodar, a city in northeastern Kazakhstan, is the result of chlor-alkali chemical plant operations in 1975-1993, where chlorine production capacity was approximately 100,000 tons per year. The total quantity of metallic mercury released into the environmen...

Coordination Chemistry of Alkali and Alkaline-Earth Cations with Macrocyclic Ligands.

ERIC Educational Resources Information Center

Dietrich, Bernard

1985-01-01

Discusses: (l) alkali and alkaline-earth cations in biology (considering naturally occurring lonophores, their X-ray structures, and physiochemical studies); (2) synthetic complexing agents for groups IA and IIA; and (3) ion transport across membranes (examining neutral macrobicyclic ligands as metal cation carriers, transport by anionic carriers,…

New mechanisms of cluster diffusion on metal fcc(100) surfaces

NASA Astrophysics Data System (ADS)

Trushin, Oleg; Salo, Petri; Alatalo, Matti; Ala-Nissila, Tapio

2001-03-01

We have studied atomic mechanisms of the diffusion of small clusters on the fcc(100) metal surfaces using semi-empirical and ab-initio molecular static calculations. Primary goal of these studies was to investigate possible many-body mechanisms of cluster motion which can contribute to low temperature crystal growth. We used embedded atom and Glue potentials in semi-empirical simulations of Cu and Al. Combination of the Nudged Elastic Band and Eigenvector Following methods allowed us to find all the possible transition paths for cluster movements on flat terrace. In case of Cu(001) we have found several new mechanisms for diffusion of clusters, including mechanisms called row-shearing and dimer-rotating in which a whole row inside an island moves according to a concerted jump and a dimer rotates at the periphery of an island, respectively. In some cases these mechanisms yield a lower energy barrier than the standard mechanisms.

Theoretical investigations on the d-p hybridized aromaticity, photoelectron spectroscopy and neutral salts of the LaX2- (X=Al, Ga, In) clusters.

PubMed

Chen, Jing; Yang, Huan; Wang, Jing; Cheng, Shi-Bo

2018-05-30

We present an extensive density functional theory (DFT) calculations on the geometrical and electronic structures of the triatomic LaX 2 - (X=Al, Ga, In) clusters. Various trail structures and spin states have been attempted to determine the lowest-energy geometries of these La-doped metal clusters. The ground states of all three clusters are calculated to possess the trigonal structures with the singlet multiplicities. The calculations on molecular orbitals (MOs) and nucleus-independent chemical shift (NICS) values have been performed to examine the aromatic characteristics of the LaX 2 - (X=Al, Ga, In) clusters. The present calculations disclose that all these metal clusters are doubly aromatic, namely d-p hybridized σ and π aromaticity resulting from the effective overlap between the 5d atomic orbital of the La atom and the p orbitals of the IIIA group elements. Theoretical vertical detachment energies (VDEs) were also calculated to simulate the photoelectron spectra (PES) of the clusters. In addition, by adding the alkali cations (Li + and Na + ) into the LaX 2 - (X=Al, Ga, In) clusters, the geometries and electronic structures of the corresponding neutral salts have also been investigated to gain more insights in the potential of using these aromatic anions as building blocks. Copyright © 2018 Elsevier B.V. All rights reserved.

Alkali-lead-iron phosphate glass and associated method

DOEpatents

Boatner, Lynn A.; Sales, Brian C.; Franco, Sofia C. S.

1994-01-01

A glass composition and method of preparation utilizes a mixture consisting of phosphorus oxide within the range of about 40 to 49 molar percent, lead oxide within the range of about 10 to 25 molar percent, iron oxide within the range of about 10 to 17 molar percent and an alkali oxide within the range of about 23 to 30 molar percent. The glass resulting from the melting and subsequent solidifying of the mixture possesses a high degree of durability and a coefficient of thermal expansion as high as that of any of a number of metals. Such features render this glass highly desirable in glass-to-metal seal applications.

Scattering of ultrashort electromagnetic pulses on metal clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Astapenko, V. A., E-mail: astval@mail.ru; Sakhno, S. V.

We have calculated and analyzed the probability of ultrashort electromagnetic pulse (USP) scattering on small metal clusters in the frequency range of plasmon resonances during the field action. The main attention is devoted to dependence of the probability of scattering on the pulse duration for various detunings of the USP carrier frequency from the plasmon resonance frequency. Peculiarities of the USP scattering from plasmon resonances with various figures of merit are revealed.

Scattering of ultrashort electromagnetic pulses on metal clusters

NASA Astrophysics Data System (ADS)

Astapenko, V. A.; Sakhno, S. V.

2016-12-01

We have calculated and analyzed the probability of ultrashort electromagnetic pulse (USP) scattering on small metal clusters in the frequency range of plasmon resonances during the field action. The main attention is devoted to dependence of the probability of scattering on the pulse duration for various detunings of the USP carrier frequency from the plasmon resonance frequency. Peculiarities of the USP scattering from plasmon resonances with various figures of merit are revealed.

Computational studies of solid-state alkali conduction in rechargeable alkali-ion batteries

DOE PAGES

Deng, Zhi; Mo, Yifei; Ong, Shyue Ping

2016-03-25

The facile conduction of alkali ions in a crystal host is of crucial importance in rechargeable alkali-ion batteries, the dominant form of energy storage today. In this review, we provide a comprehensive survey of computational approaches to study solid-state alkali diffusion. We demonstrate how these methods have provided useful insights into the design of materials that form the main components of a rechargeable alkali-ion battery, namely the electrodes, superionic conductor solid electrolytes and interfaces. We will also provide a perspective on future challenges and directions. Here, the scope of this review includes the monovalent lithium- and sodium-ion chemistries that aremore » currently of the most commercial interest.« less

Theoretical study on the ground state of the polar alkali-metal-barium molecules: Potential energy curve and permanent dipole moment